A study is carried out to investigate the heat transfer characteristics in peristaltic flow of Oldroyd 8-constant in a curved channel when inertial and streamline-curvature effects are negligible. The solution of resulting nonlinear governing equations is obtained using finite difference technique (FDM) combined with an iterative scheme. The impacts of physical parameters on the flow and heat transfer characteristics is investigated in detail. Particular attention is given to explain the pumping and trapping phenomena in detail. A comparative study between curved and straight channels is also made. It is found that, the rate of heat transfer increases with increasing the curvature of the channel. The current two-dimensional analysis is applicable in bio-fluid mechanics, industrial fluid mechanics, and some of the engineering fields.

Slip effects on unsteady non-Newtonian blood hydro-magnetic flow through an inclined catheterized overlapping stenotic artery are analyzed. The constitutive equation of power law model is employed to simulate the rheological characteristics of the blood. The governing equations giving the flow derived by assuming the flow to be unsteady and two-dimensional. Mild stenosis approximation is employed to obtain the reduced form of the governing equations. Finite difference method is employed to obtain the solution of the non-linear partial differential equation in the presence of slip at the surface. An extensive quantitative analysis is performed for the effects of slip parameter, Hartmann number, cathetered parameter and arterial geometrical parameters of stenosis on the quantities of interest such as axial velocity, flow rate, resistance impedance and wall shear stress. The streamlines for theblood flow through the artery are also included.

The aim of present analysis is to investigate the effects of heat source/sink, chemical and material composition on steady MHD mixed convection axisymmetric flow of an incompressible Maxwell fluid between two infinite stretching disks in the presence of viscous dissipation and Joule heating. The lower disk is subjected to an exothermic surface reaction, while an upper disk is maintained at uniform temperature and concentration. Also an exothermal surface reaction modeled by Arrhenius kinetics supplied heat to the Maxwell fluid. Similarity transformations are used for simplifying equations governing the flow, thermal fields, material and chemical composition fields. The analytic solution of dimensionless governing ordinary differential equations is successfully obtained using homotopy analysis method (HAM). Here, convergence of the derived series solution is ensured. We mainly focus on the effects of Hartmann number, Archimedes number, Eckert number, Prandtl number, heat generation or absorption parameter, activation energy parameter, chemical reaction parameter on dimensionless velocity, pressure, temperature and concentration distribution. The results with several values of the problem parameters are expressed graphically. To understand the behavior of flow between stretching isothermal and exothermal disks, the values of skin friction coefficient, Nusselt number and Sherwood number are tabulated for both lower and upper disks. Further, the critical value of Frank-Kamenetskii are presented through graphs and tables and discussed for different values of parameters involved in problem.

The two-dimensional boundary layer flow of an electrically conducting micropolar fluid and heat transfer subject to a transverse uniform magnetic field over a curved stretching sheet coiled in a circle of radius R has been studied. The effect of thermal radiation is also considered using linearized Rosseland approximation. For mathematical formulation of the flow equations, curvilinear coordinates system is used. The governing partial differential equations describing the flow phenomena and heat transfer characteristics are reduced to ordinary differential equations by means of suitable transformations. The system of differential equations is solved numerically by shooting method using Runge-Kutta algorithm combined with the Newtons-Raphson technique. Some physical features of the flow and heat transfer in terms of fluid velocity, angular velocity, temperature profile, the skin-friction coefficient, couple wall stress and the local Nusselt number for several values of fluid parameters are analyzed, discussed and presented in graphs and tables. Comparison of the present results with the published data for the flat surface i.e. (???) is found in good agreement.

LiNiFe-based layered structure oxide and composite for advanced single layer fuel cells

Gliding bacteria are an assorted group of rod-shaped prokaryotes that adhere to and glide on certain layers of ooze slime attached to a substratum. Due to the absence of organelles of motility, such as flagella, the gliding motion is caused by the waves moving down the outer surface of these rod-shaped cells. In the present study we employ an undulating surface model to investigate the motility of bacteria on a layer of non-Newtonian slime. The rheological behavior of the slime is characterized by an appropriate constitutive equation, namely the Carreau model. Employing the balances of mass and momentum conservation, the hydrodynamic undulating surface model is transformed into a fourth-order nonlinear differential equation in terms of a stream function under the long wavelength assumption. A perturbation approach is adopted to obtain closed form expressions for stream function, pressure rise per wavelength, forces generated by the organism and power required for propulsion. A numerical technique based on an implicit finite difference scheme is also employed to investigate various features of the model for large values of the rheological parameters of the slime. Verification of the numerical solutions is achieved with a variational finite element method (FEM). The computations demonstrate that the speed of the glider decreases as the rheology of the slime changes from shear-thinning (pseudo-plastic) to shear-thickening (dilatant). Moreover, the viscoelastic nature of the slime tends to increase the swimming speed for the shear-thinning case. The fluid flow in the pumping (generated where the organism is not free to move but instead generates a net fluid flow beneath it) is also investigated in detail. The study is relevant to marine anti-bacterial fouling and medical hygiene biophysics.

This article describes the time dependent flow of a non-Newtonian fluid with heat transfer. We consider three dimensional unsteady flow and heat transfer of an Oldroyd-B fluid for constant temperature (CT) and constant heat flux (CH) cases over an unsteady bidirectional stretching surface. Homotopic solutions of the governing boundary value problems have been computed. Convergence for both velocity and temperature profiles is explored. The effects of emerging parameters on the velocity and temperature fields are investigated with the help of graphs and tabular data. It is observed that due to unsteadiness temperature in both the constant temperature and constant heat flux cases decrease significantly. Comparison of obtained and previously published results is found in excellent agreement.

Nickel ferrite (NiFe2O4) nanoparticles and Cu0.5Tl0.5Ba2Ca2Cu3O10?? (CuTl-1223) superconductor were prepared separately and then mixed in an appropriate ratios at the final stage to obtain (NiFe2O4) x/CuTl-1223 (x = 0, 0.5, and 1.0 wt%) nano-superconductor composites. There was no significant change observed in crystal structure of the host CuTl-1223 superconducting matrix after the addition of NiFe2O4 nanoparticles. The value of zero-resistivity critical temperature { T c(R = 0) (K)} was decreased with increasing content of these nanoparticles in these composites. Maximum values of dielectric loss tangent (tan?) at lowest possible frequency of 40 Hz were increased with the increase of operating temperature, while its values were decreased and become almost zero at higher frequencies for all these samples at all operating temperatures. A peak in dielectric loss tangent was shifted towards lower frequency values with the addition of these nanoparticles in CuTl-1223 superconducting matrix. The dielectric loss tangent peak was also shifted towards lower frequency values in all these samples with increasing operating temperature, which shows the relaxator-like behavior in these samples. The dielectric parameters of these composites can be tuned by frequency, operating temperatures, and nature and content of these nanoparticles.

The GMM is a conventional approach which has been recently applied in many face recognition studies. However, the question about how to deal with illumination changes while ensuring high performance is still a challenge, especially with real-world databases. In this paper, we propose a Visual Observation Confidence (VOC) measure for robust face recognition for illumination changes. Our VOC value is a combined confidence value of three measurements: Flatness Measure (FM), Centrality Measure (CM), and Illumination Normality Measure (IM). While FM measures the discrimination ability of one face, IM represents the degree of illumination impact on that face. In addition, we introduce CM as a centrality measure to help FM to reduce some of the errors from unnecessary areas such as the hair, neck or background. The VOC then accompanies the feature vectors in the EM process to estimate the optimal models by modified-GMM training. In the experiments, we introduce a real-world database, called KoFace, besides applying some public databases such as the Yale and the ORL database. The KoFace database is composed of 106 face subjects under diverse illumination effects including shadows and highlights. The results show that our proposed approach gives a higher Face Recognition Rate (FRR) than the GMM baseline for indoor and outdoor datasets in the real-world KoFace database (94% and 85%, respectively) and in ORL, Yale databases (97% and 100% respectively).

Peristaltic motion of a non-Newtonian Carreau fluid is analyzed in a curved channel under the long wavelength and low Reynolds number assumptions, as a simulation of digestive transport. The flow regime is shown to be governed by a dimensionless fourth-order, nonlinear, ordinary differential equation subject to no-slip wall boundary conditions. A well-tested finite difference method based on an iterative scheme is employed for the solution of the boundary value problem. The important phenomena of pumping and trapping associated with the peristaltic motion are investigated for various values of rheological parameters of Carreau fluid and curvature of the channel. An increase in Weissenberg number is found to generate a small eddy in the vicinity of the lower wall of the channel, which is enhanced with further increase in Weissenberg number. For shear-thinning bio-fluids (power-law rheological index, n < 1) greater Weissenberg number displaces the maximum velocity toward the upper wall. For shear-thickening bio-fluids, the velocity amplitude is enhanced markedly with increasing Weissenberg number.

By employing impedance spectroscopy, switchover of one phase (RLF) into another phase (RHF) is reported with time for polycrystalline La0.40Pr0.10Ca0.50MnO3 compound. An irreversible increase in the impedance is explored in terms of the competition of two coexisting contending phases. An increasing along with switchover tendency of the impedance of RLF with RHF with time is conferred having different kinetics of the two coexisting competing phases. The increase in the resistance of the La0.40Pr0.10Ca0.50MnO3 sample is originated in terms of the polar nature of RHF (O-deficient related traps) and structural as well as trap associated nature of RLF.

Flower-like hierarchical Zinc oxide nanostructures synthesized by co-precipitation method have been hydrothermally functionalized with 8 nm Au NPs and 15 nm Ag nanoparticles. The photocatalytic and electrochemical performance of these structures are investigated. XPS studies show that the composite exhibits a strong interaction between noble metal nanoparticles (NPs) and Zinc oxide nanoflowers. The PL spectra exhibit UV emission arising due to near band edge transition and show that the reduced PL intensities of Au¿ZnO and Ag¿ZnO composites are responsible for improved photocatalytic activity arising due to increase in defects. Moreover, the presence of Au NPs on ZnO surface remarkably enhances photocatalytic activity as compared to Ag¿ZnO and pure ZnO due to the higher catalytic activity and stability of Au NPs. On the other hand, Ag¿ZnO-modified glassy carbon electrode shows good amperometric response to hydrogen peroxide (H2O2), with linear range from 1 to 20 µM, and detection limit of 2.5 µM (S/N = 3). The sensor shows high and reproducible sensitivity of 50.8 ?A cm?2 ?M?1 with a fast response less than 3 s and good stability as compared to pure ZnO and Au¿ZnO-based sensors. All these results show that noble metal NPs-functionalized ZnO base nanocomposites exhibit great prospects for developing efficient non-enzymatic biosensor and environmental remediators.

The latent tracks in mono- and few-layer molybdenum disulfide (MoS2) induced by 209Bi ions with energies of 0.45¿1.23 GeV were characterized by atomic force microscopy (AFM). The hillock-like latent tracks were observed on the surface of irradiated monolayer MoS2. The diameter of the hillock after deconvolution procedure is 15.8 ± 1.7 nm and the height is 1.0 ± 0.3 nm. Hillock-like tracks are induced by energy transfer from energetic 209Bi ions to electron system of MoS2, resulting in the ionization and excitation and then the displacement of target atoms. Since Raman spectroscopy is sensitive to damages induced by swift-heavy ion irradiation, the in-plane E 2g 1mode (~385 cm?1) and the out-of-plane A 1g mode (~408 cm?1) of MoS2 were investigated. With increasing ion fluence, the A 1g peak shifts to higher frequencies, and the intensity ratio between A1g and E 2g 1 peak increases. Besides, the A 1g peak narrows. The evolution of the structural and vibrational properties of MoS2 with fluence is discussed. It can be concluded that the blue shift and narrowing of A 1g peak in irradiated MoS2 is due to the adsorption of oxygen molecules at latent tracks. With decreasing thickness of MoS2, the irradiation resistance decreases.

Linear and nonlinear characteristics of electrostatic waves in a multicomponent magnetoplasma comprising of Boltzmann distributed electrons, Cairn¿s distributed hot electrons, and cold dynamic ions are studied. It is found that the effect of superthermal electrons, ion-neutral collisions, and ion shear flow modifies the propagation of ion-acoustic and drift waves. The growth rate of the ion shear flow instability varies with the addition of Cairn¿s distributed hot electrons. It is also investigated that the behavior of different type of vortices changes with the inclusion of superthermal hot electrons. The relevance of this investigation in space plasmas such as in auroral region and geomagnetic tail is also pointed out.

InP crystals and GaN films were irradiated by swift heavy ions 86Kr and 209Bi with kinetic energies of 25 and 9.5 MeV per nucleon and ion fluence in the range 5 × 1010 to 3.6 × 1012 ions/cm2. The characteristic optical bands were studied by Raman spectroscopy to reveal the disorder and defects induced in the samples during the irradiation process. The crystallinity of InP and GaN was found to be deteriorated after irradiation by the swift heavy ions and resulted in the amorphous nature of the samples along the ion tracks. The amorphous tracks observed by transmission electron microscopy (TEM) images confirmed the formation of lattice defects. In typical F2(LO) mode, in case of InP, the spectra shifted towards the lower wavenumbers with a maximum shift of 7.6 cm?1 induced by 1030 MeV Bi ion irradiation. While in case of GaN, the typical E2(high) mode shifted towards the higher wavenumbers, with maximum shift of 5.4 cm?1 induced by 760 MeV Bi ion irradiation at ion fluence of 1 × 1012 ions/cm2. The observed Raman shifts reveal the presence of lattice defects and disorder induced in the samples after irradiation by the swift heavy ions. This irradiation also generated lattice stress in the samples, which has been investigated and discussed in detail in this work.

In nuclear reactors, safety is of prime importance in their operation. Fault detection and isolation (FDI) methods are making their applications to improve safety, reliability and availability of nuclear reactors. Among various FDI techniques, data-driven techniques are best suited for fault diagnosis of nuclear reactors because process data is available to sensors, both in normal operation and under faulty conditions. Among data-driven techniques, principle component analysis (PCA) and Fisher discriminant analysis (FDA) have been successfully applied to many industrial processes. In this paper, PCA and FDA are applied for fault detection and fault isolation in Pakistan Research Reactor-2 (PARR-2) for known faults of control rod withdrawal and external reactivity insertion. PCA model is developed using training data set obtained during normal operation of PARR-2. It is then applied to test data set collected from the reactor during control rod withdrawal fault and external reactivity insertion fault. Likewise, FDA model is constructed for the above mentioned faults using the training data set and applied to the test data for fault isolation. The results demonstrate that PCA is successful in detection of both the faults. Additionally, FDA not only detects faults, but it is also successful in isolation/localization of the two faults in PARR-2.

Adsorption and electronic properties of Fullerene/Zn-Phthalocyanine (C60/ZnPc) interface with face-on orientation: A van der Waals corrected Density Functional Theory investigation

This paper describes synthesis of the functional BaTiO3 (BT) nanostructures by composite-hydroxide-mediated (CHM) approach. The effect of processing temperature on the nucleation and the optical, structural properties is investigated. The nanostructures prepared at various temperatures (180, 220 and 250 °C) are thermally stable and nucleate in different morphologies, which shows a temperature-dependent mechanism of the CHM approach. The nanostructures are cubic in nature with an average particle size in the range of 97¿250 nm. The local crystal structure investigated by Raman spectroscopy reveals a certain degree of tetragonality on atomic scale in the local phase structure. The micrographs of scanning electron microscopy (SEM) indicate formation of the nanocuboids at 180 and 220 °C with larger particle size. At 250 °C, the product shows ball-like spherical morphology. Energy-dispersive X-ray (EDX) confirms the existence of Ba, Ti and O elements in the product, which indicates a chemically pure product. Further signature on the formation, purity and chemical bonding is obtained from FT-IR spectroscopy. Based on these experimental results, size, morphology manipulation and possible growth mechanisms are proposed with CHM at low temperature and without surfactant.

Bimagnetic monodisperse CoFe2O4/Fe3O4 core/shell nanoparticles have been prepared by solution evaporation route. To demonstrate preferential coating of iron oxide onto the surface of ferrite nanoparticles X-ray diffraction (XRD), High resolution transmission electron microscope (HR-TEM) and Raman spectroscopy have been performed. XRD analysis using Rietveld refinement technique confirms single phase nanoparticles with average seed size of about 18 nm and thickness of shell is 3 nm, which corroborates with transmission electron microscopy (TEM) analysis. Low temperature magnetic hysteresis loops showed interesting behavior. We have observed large coercivity 15.8 kOe at T = 5 K, whereas maximum saturation magnetization (125 emu/g) is attained at T = 100 K for CoFe2O4/Fe3O4 core/shell nanoparticles. Saturation magnetization decreases due to structural distortions at the surface of shell below 100 K. Zero field cooled (ZFC) and Field cooled (FC) plots show that synthesized nanoparticles are ferromagnetic till room temperature and it has been noticed that core/shell sample possess high blocking temperature than Cobalt Ferrite. Results indicate that presence of iron oxide shell significantly increases magnetic parameters as compared to the simple cobalt ferrite.

The effects of heat and mass transfer on blood flow through a tapered artery with overlapping stenosis are analyzed in this article. An appropriate mathematical relation is used for the geometry of the stenosed artery. The rheological behavior of streaming blood in the artery is characterized by the Cross non-Newtonian model. The constitutive equation in conjunction with equation of motion is used to analyze momentum transfer while the heat and mass transfer effects are modeled through heat conduction and diffusion equations, respectively. The simplified form of momentum, heat and mass transfer equations are obtained by employing the mild stenosis condition. The emerging unsteady non-linear coupled partial differential equations are solved numerically using a well-tested explicit finite difference scheme. The influence of various emerging parameters on blood flow and on heat and mass transfer is evaluated via various plots. The instantaneous global behavior of temperature and concentration is also illustrated through contour plots for pertinent parameters.

Core-shell magnetic nanowires of nickel and cobalt embedded in ion-track etched polycarbonate (PC) template were fabricated by two step etching and deposition technique. Structural investigations reveal the successful fabrication of 60 nm nickel core nanowires surrounded by ?20 nm concentric cobalt shell. X-ray diffraction and electron microscopy studies confirmed the presence of fcc nickel and hcp cobalt at the core and shell regions, respectively. Low temperature magnetic studies performed between 5 and 300 K indicate the ferromagnetic nature of the nanowires with coercivity and magnetization that are increasing with decreasing temperature of the nanowires. Temperature dependence of coercivity can be understood in term of thermal activation over the energy barrier with m-power dependence on the field, while the saturation magnetization was found to follow the modified Bloch's law at low temperatures.

The water-gas-shift reaction (WGSR) is an important industrial process that can be significantly enhanced at suitable catalyst surfaces. In this work, we investigate the catalytic behavior of metallic Cu(1?0?0) and bimetallic Cu¿Au(1?0?0) surfaces. With density functional theory calculations, the variation in the Gibbs free energy (?G°), the activation barriers, and the rate constants for the WGSR are calculated. The variation in ?G° for water dissociation shows that the process is spontaneous up to 520?K on the bimetallic surface and up to 229?K on the Cu(1?0?0) surface. The calculated rate constants for the process also show that the bimetallic surface is much more reactive than the Cu(1?0?0) surface. The calculated pressure¿temperature phase diagram for water dissociation shows that the partial pressure of H2O required for water dissociation on the bimetallic surface is substantially lower than that on the Cu(1?0?0) surface at all the studied temperatures. Additionally, the calculations demonstrate that the kinetics of the water-gas-shift reaction is dominated by redox processes on both the surfaces.

Hydromagnetic slip flow of nanofluid over a curved stretching surface with heat generation and thermal radiation

Multifunctional roles of La0.2Sr0.25Ca0.45TiO3 (LSCT) perovskite material as anode, cathode, and electrolyte for low temperature solid oxide fuel cell (LT-SOFC) are discovered for the first time, and have been investigated via electrochemical impedance spectroscopy (EIS) and fuel cell (FC) measurements. LSCT resistance decreases prominently in FC environment as shown in this study. An improved performance was observed by compositing LSCT with samaria doped ceria (SDC) at 550 °C when the FC power density increased from tens of mW cm?2 for the pure LSCT system up to hundreds of mW cm?2. The improved conductivity of LSCT¿SDC composite is highlighted. The multifunctionality of LSCT as cathode, anode and electrolyte could be attributed to different conducting behavior at high and low oxygen partial pressures and ionic conduction at intermediate oxygen partial pressures. These new discoveries not only indicate great potential for exploring multifunctional perovskites for the next generation SOFC, but also deepen SOFC science and develop new technologies.

The stagnation-point flow of a second-grade fluid past a power law lubricated surface is considered in this paper. It is assumed that the fluid impinges on the wall obliquely. A suitable choice of similarity transformations reduces the governing partial differential equations into ordinary differential equations. The thin lubrication layer suggests that the interface conditions between the fluid and the lubricant can be imposed on the boundary. An implicit finite difference scheme known as the Keller-Box method is employed to obtain the numerical solutions. The effects of slip parameter and Weissenberg number on the fluid velocity and streamlines is discussed in the graphs. The limiting cases of partial-slip and no-slip can be deduced from the present solutions.

Underwater characterizations of (Pb0.94Sr0.04)(Zr0.52Ti0.48)O3 (PZT) and PZT/araldite-F 1¿3 composite were carried out through a self-designed transducer. Disc-shaped samples of bulk PZT and PZT/araldite-F composite were first characterized in air and then were assembled in the transducer individually. The transducer¿s underwater voltage receiving sensitivity (Sh) and transmitting voltage response (Sv) were investigated in the frequency range of 10¿200 kHz (well below thickness mode resonance) using a calibrated projector and receiver method with pulse technique. Results revealed that the transducer made with composite sample exhibited better (Sh) values (?214 dB ref 1 V/µPa) due to ~295% higher piezoelectric voltage coefficient gh (30 × 10?3 Vm/N) of the composite compared to PZT. In addition, the transducer with the PZT sample showed better Sv values (80 dB ref 1 µPa/1 V at 1 m) due to the presence of planar mode peaks in the frequency range of 10¿200 kHz. These results indicate that the monolithic piezoceramic can exhibit underwater Sv response in both planar and thickness resonance modes owing to the admittance peaks in these frequency regions.

Cyclohexenone containing chalcones core is one important class of materials, which exhibit high nonlinear optical (NLO) responses and good crystallizability. The present study reports the successful development of six new fluorescent cyclohexenone derivatives (CDs) via conventional Robinson annulation method. The molecular structures of these newly synthesized CDs were confirmed by using various analytical techniques such as 1H NMR, 13C NMR, FTIR, EIMS, UV¿Vis spectroscopy and single crystal X-ray diffraction. The crystallographic data revealed that the spatial structure of the representative CD (4BE) belongs to monoclinic, P21/c space group. The results from luminescence studies show that the CDs molecules apparently emit intense green light at room temperature in aqueous media. The relative polarity and molecular chemical stability of the CDs molecules were predicted by measuring the molecular electrostatic potential and frontier molecular orbital energy. In addition, the UV¿Vis spectra, transition character and electronic structures of these CDs were computed by using quantum chemical methodology. It was interesting to note that the values of computed and experimental electronic transitions (?max) were in good agreement and these CDs display high hyperpolarizability (?) values. The present work will be helpful for systematical understanding of the structures and the optical properties of CDs for studying the structure¿activity relationship that will suggest their potential application in photonic devices. Copyright © 2015 John Wiley & Sons, Ltd.

NdFe1?x NixO3 (0.1 ? x ? 0.7) orthoferrites are synthesized by solid state reaction method, and the structural properties of these materials are investigated by employing x-ray diffraction (XRD), scanning electron microscopy (SEM) and Mössbauer spectroscopy. The orthorhombic structure is observed in all systems; however, with the increase in Ni doping, the increase in tolerance factor and the decrease in the cell volume are observed. Orthorhombic distortion decreases with Ni content increasing up to 50%, while above 50% Ni doping it increases. SEM examination indicates the increases in grain size and intermixing of grains with increase in Ni concentration. Comparison between bulk and theoretical densities shows that in each of all samples porosity is less than 2%. Mössbauer spectroscopic investigations are performed to explain local structure, Fe oxidation states and collapse of the magnetic ordering. In these samples the Fe oxidation state remains +3 and there is no considerable increase in hole states observed; however due to mismatch of the ionic radii between Fe3+ and Ni3+, octahedral distortions, sagging and distribution of hyperfine parameters increase with increase in Ni concentration. The major factors behind the collapse of magnetic ordering in the Ni-doped systems are the weakening of the super-exchange interactions, decrease in the Neel temperature, increase in spin¿spin relaxation frequency and high spin to low spin transition.

The influence of slip and magnetic field on transport characteristics of a bio-fluid are analyzed in a curved channel. The problem is modeled in curvilinear coordinate system under the assumption that the wavelength of the peristaltic wave is larger in magnitude compared to the width of the channel. The resulting nonlinear boundary value problem (BVP) is solved using an implicit finite difference technique (FDT). The flow velocity, pressure rise per wavelength and stream function are illustrated through graphs for various values of rheological and geometrical parameters of the problem. The study reveals that a thin boundary layer exists at the channel wall for strong magnetic field. Moreover, small values of Weissenberg number counteract the curvature and make the velocity profile symmetric. It is also observed that pressure rise per wavelength in pumping region increases (decreases) by increasing magnetic field, Weissenberg number and curvature of the channel (slip parameter).

Flow units perspective on sensitivity and reliability of metallic glass properties

Polymer films were cast from aqueous solutions of chitosan (CS) and poly(vinyl alcohol) (PVA) in employing tetraethoxysilane (TEOS) as a crosslinking agent. Different amounts of TEOS were used and the presence of siloxane bond was confirmed by Fourier transform infrared (FTIR) spectroscopy. The swelling behavior of the films was determined by exploring the time-dependent swelling in distilled water. The swelling kinetics showed a linear increase and achieved maximum value within half an hour. The emergence of one arc in complex impedance plane plot exhibited the presence of one type of relaxation process. The ac conductivity was also calculated which was increased from 2.55?×?10?12 to 9.05?×?10?12???1cm?1 as the amount of crosslinker was increased from 2 to 6 %. Further increase in the amount of crosslinker (up to 10 %) reduced the conductivity to minimum value of 0.24?×?10?12???1cm?1. The novel properties of the biocompatible films can be utilized in biomedical applications concerning the biological systems which require smaller charge in medicinal apparatus, bioelectrodes coatings, etc.

Silicene and related buckled materials are distinct from both the conventional two dimensional electron gas and the famous graphene due to strong spin orbit coupling and the buckled structure. These materials have potential to overcome limitations encountered for graphene, in particular the zero band gap and weak spin orbit coupling. We present a theoretical realization of quantum capacitance which has advantages over the scattering problems of traditional transport measurements. We derive and discuss quantum capacitance as a function of the Fermi energy and temperature taking into account electron-hole puddles through a Gaussian broadening distribution. Our predicted results are very exciting and pave the way for future spintronic and valleytronic devices.

The boundary layer flow of a third grade fluid and mass transfer near a stagnation-point with diffusion of chemically reacting species on a porous plate is investigated. Due to a porous plate the suction is taken into an account. Using suitable transformations, the momentum and concentration equations are first transformed into nonlinear ordinary ones and then solved using a hybrid numerical method. This method combines the features of finite difference and shooting methods. The effects of various controlling parameters on the flow velocity, concentration profile, skin friction and rate of mass transfer on surface are analyzed graphically and in tabular form. Comparison of the present results with the previous reported results has been found in excellent agreement.

The objective of this work is to study the peristaltic motion of an incompressible Giesekus fluid in a circular cylindrical tube. The problem is modeled in a fixed frame of reference and then transformed into a frame that moves with the wave speed. The most widely taken assumptions of long wavelength and low Reynolds number are applied in the wave frame. Both exact and approximate solutions of governing equation for stream function are obtained at each cross-section by solving nonlinear algebraic equations. The comparison of the two solutions is presented graphically. The exact solution is then used to analyze the effects of parameters of interest on velocity profile, pressure rise per wavelength and trapping phenomenon. The results disclose that the magnitude of velocity increases in the middle-most region of the tube whereas it decreases in the vicinity of wall with increasing the Giesekus model parameters. It is also observed that the size and circulation of the trapped bolus decrease with increasing the Giesekus model parameters. Moreover, much greater mixing is realized in a plane channel than in a circular tube.

A revised translating bed total body irradiation (TBI) technique is developed for shielding organs at risk (lungs) to tolerance dose limits, and optimizing dose distribution in three dimensions (3D) using an asymmetrically-adjusted, dynamic multileaf collimator. We present a dosimetric comparison of this technique with a previously developed symmetric MLC-based TBI technique. An anthropomor-phic RANDO phantom is CT scanned with 3 mm slice thickness. Radiological depths (RD) are calculated on individual CT slices along the divergent ray lines. Asymmetric MLC apertures are defined every 9 mm over the phantom length in the craniocaudal direction. Individual asymmetric MLC leaf positions are optimized based on RD values of all slices for uniform dose distributions. Dose calculations are performed in the Eclipse treatment planning system over these optimized MLC apertures. Dose uniformity along midline of the RANDO phantom is within the confidence limit (CL) of 2.1% (with a confidence probability p = 0.065). The issue of over- and underdose at the interfaces that is observed when symmetric MLC apertures are used is reduced from more than ± 4% to less than ± 1.5% with asymmetric MLC apertures. Lungs are shielded by 20%, 30%, and 40% of the prescribed dose by adjusting the MLC apertures. Dose-volume histogram analysis confirms that the revised technique provides effective lung shielding, as well as a homogeneous dose coverage to the whole body. The asymmetric technique also reduces hot and cold spots at lung-tissue interfaces compared to previous symmetric MLC-based TBI technique. MLC-based shielding of OARs eliminates the need to fabricate and setup cumbersome patient-specific physical blocks.

Manganese substituted cobalt ferrites, i.e., Co1?xMnxFe2O4 (0.0 ? x ? 0.4) were prepared by a solid state reaction method. XRD analysis confirmed the formation of a single-phase cubic spinel structure for all of the synthesized compositions, whereas an SEM study revealed that Mn substitution changes the microstructure. 57Fe Mössbauer spectroscopy measurements suggested that Fe3+ cations progressively migrate with Mn addition from tetrahedral (A) sites to octahedral (B) sites which have a relatively smaller covalency. Therefore, the distribution of cations between the A- and B-sites changed with increasing x. Moreover, interestingly, the Fe2+/Fe3+ cation ratio remains zero and high spin Fe3+ is the only oxidation state observed at both sites for all of the synthesized compositions. In order to explore the effects of observed variations in the microstructure and cation distribution on the dielectric and resistive properties, the prepared samples were subjected to impedance spectroscopic experiments in a wide frequency range at room temperature. Mn substitution is found to improve the resistive properties by about two orders of magnitude. This increase in the resistive properties is explained in terms of the variations in the microstructure and decrease in the mobility of the charge carriers associated with the cations redistribution. Similarly, the variation in the dielectric permittivity is also conferred in terms of the change in microstructure and cation redistribution.

Pure zinc oxide (ZnO) and Sn-doped ZnO hexagonal sheets were synthesized by template free hydrothermal growth mechanism with controlled morphology by using zinc acetate dihydrate (Zn(CH?COO)?· 2H?O), tin chloride pentahydrate (SnCl? · 5H?O), Polyvinylpyrrolidone (PVP) and H?O as precursors. The structural, physical, chemical, and magnetic characteristics were investigated by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy and alternating gradient magnetometer (AGM), respectively. The average crystalline size of hexagonal phase of ZnO sheets was calculated to be about 34 nm from XRD patterns. Energy dispersive spectroscopy provided the compositional analysis of pure and Sn-doped ZnO. Room temperature ferromagnetism (RTFM) was observed by AGM for pure and Sn-doped ZnO hexagonal plates. RTFM increases monotonically for Sn doping and reaches maximum saturation magnetization 0.045 emu/g for 3% Sn-doped ZnO.

We have analyzed peristaltic flow of an Oldroyd-B fluid in a curved channel. Assuming the flow to be incompressible, laminar and two-dimensional, the governing partial differential equations are reduced under long wavelength and low Reynolds number approximations into a single nonlinear ordinary differential equation in the stream function. Matlab built-in routine bvp4c is utilized to solve this nonlinear ordinary differential equation. The solution thus obtained is used to investigate the effects of curvature of the channel and Weissenberg number on important phenomena of pumping and trapping associated with peristaltic motion. It is found that for small values of Weissenberg number, the effects of curvature are dominant. However, for large values of Weissenberg number, viscoelastic effects counteract the effects of curvature and help the flow velocity and circulating bolus of fluid to regain their symmetry.

The purpose of this study was to ensure accuracy in radiation dose delivery, external dosimetry quality audit has an equal importance with routine dosimetry performed at clinics. To do so, dosimetry quality audit was organized by the Secondary Standard Dosimetry Laboratory (SSDL) of Pakistan Institute of Nuclear Science and Technology (PINSTECH) at the national level to investigate and minimize uncertainties involved in the measurement of absorbed dose, and to improve the accuracy of dose measurement at different radiotherapy hospitals. A total of 181 dosimetry quality audits (i.e., 102 of Co-60 and 79 of linear accelerators) for tele­therapy units installed at 22 different sites were performed from 1989 to 2015. The percent deviation between users¿ calculated/stated dose and evaluated dose (in the result of on-site dosimetry visits) were calculated and the results were analyzed with respect to the limits of ± 2.5% (ICRU ¿optimal model¿) ± 3.0% (IAEA on-site dosimetry visits limit) and ± 5.0% (ICRU minimal or ¿lowest acceptable¿ model). The results showed that out of 181 total on-site dosimetry visits, 20.44%, 16.02%, and 4.42% were out of acceptable limits of ± 2.5% ± 3.0%, and ± 5.0%, respectively. The importance of a proper ongoing quality assurance program, recommendations of the followed protocols, and properly calibrated thermometers, pressure gauges, and humidity meters at radiotherapy hospitals are essential in maintaining consistency and uniformity of absorbed dose measurements for precision in dose delivery.

The adsorption and dissociation mechanisms of H2S on a TiO2 (001) surface were elucidated using first principles calculation based on the density functional theory. The interaction of the intermediates involving S, HS and OH species has been discussed in detail. For these species, the most favorable adsorption sites were determined and led to further computations involving dissociation of H2S into HS and H and bonding of H-atom with the OH to form water on the surface. The creation of vacancies along with the presence of S on the surface enhanced the H2S adsorption energy slightly. However, addition of OH in the system caused H2S to bind on the surface sufficiently strongly. Additionally, H2S decomposition was found to be a spontaneous process in the presence of OH radicals.

Various electrostatic twisted modes are re-investigated with finite orbital angular momentum in an unmagnetized collisionless multi-component dusty plasma, consisting of positive/negative charged dust particles, ions, and electrons. For this purpose, hydrodynamical equations are employed to obtain paraxial equations in terms of density perturbations, while assuming the Gaussian and Laguerre-Gaussian (LG) beam solutions. Specifically, approximated solutions for potential problem are studied by using the paraxial approximation and expressed the electric field components in terms of LG functions. The energy fluxes associated with these modes are computed and corresponding expressions for orbital angular momenta are derived. Numerical analyses reveal that radial/angular mode numbers as well asdustnumber density and dust charging states strongly modify the LG potential profiles attributed to different electrostatic modes. Our results are important for understanding particle transport and energy transfer due to wave excitations in multi-component dusty plasmas.

Co3O4 mesoporous nanosheets/three-dimensional graphene networks (Co3O4MNSs/3DGNs) nanohybrids have been successfully synthesized and investigated as anode materials for sodium ion batteries (SIBs). Microstructure characterizations have been performed to confirm the 3DGNs and Co3O4 MNSs nanostructures. It has been found that the present Co3O4 MNSs/3DGNs nanohybrids exhibit better SIB performance with enhanced reversible capacity, good cycle performance and rate capability as compared to Co3O4 MNSs and Co3O4 nanoparticles. The improved electrochemical performance is considered due to the mesoporous nature of the products, the addition of 3DGNs, 3D assembled hierarchical architecture and decrease in volume expansion during cycling. Thus, SIB is considered as a low cost alternative to LIBs for large-scale electric storage applications.

In this study a series of Bi1-xSrxFeO3-d (0 ? x ? 0.45) multiferroic samples have been prepared in order to study the effect of divalent Sr content on the crystal structure, dielectric and magnetic properties. Rietveld refinement of X-ray diffraction data revealed a structural phase transition from rhombohedral to pseudo cubic phase at x = 0.25. Mössbauer measurements showed that Fe ions retained their trivalent state while the Sr2+ ion substitution at Bi3+ site results in oxygen deficiency and in tetrahedral coordination for some of the Fe¿O ions. For x ? 0.25 all the compositions are ferromagnetic with a strong magnetization enhancement between x = 0.15 and x = 0.25. The ferromagnetic onset is consistent with the structural transformation at x = 0.25 that is understood to destroy the parent antiferromagnetic cycloidal spin structure. Oxygen annealing was observed to result in a decrease of the magnetic moment suggesting that oxygen vacancies also contribute to the observed magnetization. The observed decrease in the values of magnetic coercivity at low temperatures is suggested to be indicative of magnetoelectric coupling in these multiferroic samples. The dielectric response depends in general on the crystal structure and oxygen vacancies while the x = 0.45 composition shows a marked anomaly in e(T). This anomaly is explained in terms of relaxation effects originating presumably in nanoscale polar inhomogeneities.

Nanocrystalline ferrites with general formula of Co1-xMnxFe2O4 (0 ? x ? 1) have been synthesized via wet chemical coprecipitation technique. Structural and magnetic investigations were performed at room temperature. The results revealed the formation of single phase Mn-substituted CoFe2O4 nanoparticles with crystallite sizes in the range 12¿15 nm. An increase in lattice parameter and decrease in X-ray density were observed with increasing Mn concentration in CoFe2O4. FTIR results showed two (vibrational) frequency bands (?1 and ?2) for tetrahedral and octahedral sites confirming the formation of spinel ferrite. Magnetic measurements showed increasing behavior of both coercivity and saturation magnetization of cobalt ferrite up to 20¿30% manganese concentration followed by a monotonic decrease in these parameters for higher Mn concentrations.

Structural and optoelectronic properties of nanostructured TiO2 thin films with annealing

Magnetoelectric (ME) composites with the composition (x)PbZr0.52Ti0.48O3 + (1 - x)CoFe2O4 where x = 0.0, 0.5 and 1.0 are synthesized by ball milling method. X-ray diffraction (XRD) analysis revealed the presence of both PbZr0.52Ti0.48O3 (PZT) and CoFe2O4 (CFO) pure phases in the PZT¿CFO composite. Scanning electron micrographs (SEM) showed distribution of constituent phases throughout the sample. Magnetic hysteresis loop showed ferromagnetic like behaviour of the composite with a coercive field larger than cobalt ferrite. Impedance (Z' and Z?) and electrical modulus (M' and M?) spectra suggested two distinct electrical responses which are observed in the temperature range of 300¿370 K. These contributions are arising due to the coexistence of two relaxation processes: one is attributed to the high resistive (PZT) phase; while the second one is due to the comparatively conductive (CFO) phase in the PZT¿CFO composite, respectively. The electrical conduction and dipolar relaxation are dominated by small polaron hopping (SPH) model, whereas the activation energies calculated from SPH model suggested that p-type carriers are responsible for the conduction in the PZT¿CFO composite. Furthermore, ion hopping and conduction mechanism are discussed using an ac conductivity analysis.

The work presents a comparative study of the effects of divalent (Pb), trivalent (La) and tetravalent (Ti) substituents on the multiferroic properties of BiFeO3 (BFO). Both A and B-sites were substituted to obtain the compositions i.e. (Bi1-x-yLaxPby)(Fe1-zTiz)O3 (x, y = 0, 0.1, 0.2 and z = 0, 0.05, 0.1, 0.15). Each of the substituent was particularly chosen i.e. Pb was chosen to keep the lone pair character which is the similar case as Bi ion. Additionally isovalent La was chosen to achieve single phase by reducing Bi volatization. Both these ions, on substitution, stabilized the crystal structure and suppressed the formation of extra phases which are unavoidable in pure BFO. All the Ti substituted and Bi0.8La0.2FeO3compositions exhibited rhombohedral perovskite (R3c) phase, while Bi0.8Pb0.2FeO3 and Bi0.8La0.1Pb0.1FeO3 exhibited cubic phase. Mössbauer measurements revealed that impurity phase in case of compositions with divalent and trivalent substituents, disappeared completely when Ti substituted Fe. For all the compositions Fe ions were found in +3 state. High temperature dielectric properties showed that all the compositions were ferroelectric with paraelectric transition lying well above the room temperature. Weak ferromagnetism was found in Ti substituted compositions where coercivity was found to increase as the Ti concentration increases. All the BFO samples substituted with Pb, exhibited a dielectric anomaly in the temperature range, 100 °C ? T ? 250 °C. A systematic reduction in the intensity of the dielectric anomaly peak was observed as a function of Ti concentration which indicates that the anomaly is related to the conductivity and is element specific. However, Mössbauer data revealed absence of Fe2+ state, which ensured that it was not related with the presence of Fe2+ ions. Saturation polarization was found to increase as Ti concentration increased from 0% to 10%.

A two-dimensional model is used to analyze the unsteady pulsatile flow of blood through a taperedartery with stenosis. The rheology of the flowing blood is captured by the constitutive equation of Carreau model. The geometry of the time-variant stenosis has been used to carry out the present analysis. The flow equations are set up under the assumption that the lumen radius is sufficiently smaller than the wavelength of the pulsatile pressure wave. A radial coordinate transformation is employed to immobilize the effect of the vessel wall. The resulting partial differential equations along with the boundary and initial conditions are solved using finite difference method. The dimensionless radial and axial velocity, volumetric flow rate, resistance impedance and wall shear stress are analyzed for normal and diseased artery with particular focus on variation of these quantities with non-Newtonian parameters.

Nickel nanowires (NWs) of 98 nm diameter and 17 micron length were fabricated by electrodeposition in anodic aluminum oxide (AAO) membranes. Structural analyses reveal that the NWs have face centered cubic (fcc) structure with preferred orientation along (111) plane. Low temperature magnetic measurements (10¿300 K) show that coercivity (Hc) of nanowires increases with decreasing temperature following Kneller?s law similar to the ferromagnetic nanoparticle system. In addition, the saturation magnetization follows the modified Bloch?s law in the temperature range 50¿300 K. However, at temperatures below 50 K there is an abrupt increase in net magnetization of the NWs that has been attributed to the presence of paramagnetic impurities in the samples that are activated at low temperatures and at high fields.

The unsteady flow characteristics of blood in a catheterized overlapping stenosed artery are analyzed in presence of body acceleration and magnetic field. The stenosed arterial segment is modeled as a rigid constricted tube. An improved shape of stenosis in the realm of the formulation of the arterial narrowing caused by atheroma is integrated in the present study. The catheter inside the artery is approximated by a thin rigid tube of small radius while the streaming blood in the artery is characterized by the Carreau model. Employing mild stenosis condition, the governing equation of the flow is derived which is then solving numerically using finite difference scheme. The variation of axial velocity, flow rate, resistance impendence and wall shear stress is shown graphically for various parameters of interest. The flow patterns illustrating the global behavior of blood are also presented.

Ni¿Cu¿Co composite magnetic nanowires have been successfully synthesized by electrochemical deposition. Microstructural and compositional analyses were carried out using FESEM, TEM, HRTEM and XRD. Magnetic measurements were performed from in the temperature range 5¿300 K. A strong diamagnetic contribution, which results from the polycarbonate template, was found to show s-shape behavior of the hysteresis loops of the nanowires. The coercivity of the samples was found to increase with the decreasing temperature following simple model of thermal activation of particle¿s moment over the anisotropy barrier in the temperature range 50¿300 K. Saturation magnetization was found to increase with decreasing temperature following the modified Bloch¿s law at low temperatures.

In this study, the iron nanoparticles were synthesized by ferrous sulfate method using LiBH4as a reducing agent. The reduction of Cr(VI) to Cr(III) by iron nanoparticles supported on a porous cation-exchange resin and the retention of Cr(III) and Fe(III) as products on the resin were achieved in a single step. The size and surface area of iron nanoparticles were determined by transmission electron microscopy and BET surface area analysis. The loading of the iron nanoparticles on porous cationic resin support was confirmed by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy as well as chemical analysis. Porous cationic support material composed of sulphonated styrene¿divinylbenzene copolymer of three different diameter sizes i.e., 1.2¿45, 45¿150 and 150¿270 µm was synthesized by suspension polymerization. The cationic support was characterized by FTIR spectroscopy, mercury porosimetry, particle size analysis, and sulphonic acid content estimations. The iron nanoparticles were dispersed into porous cationic support material and then the composite was applied for reduction of Cr(VI). The reduction capacity of Cr(VI) was higher in smaller size diameter of support material (1.2 to 45 µm) as compared to the larger diameter. Fe(III) and Cr(III) produced from the reaction of Fe0 and Cr(VI) were adsorbed onto the porous cationic support material. The reduction capacity of Cr(VI) and adsorption capacities of Fe(III) and Cr(III) were evaluated at different temperatures, concentrations of iron nanoparticles loaded on porous cationic exchange resin and pH.

Crystalline boron carbide powder was synthesized by carbothermal reduction of the condensed product of boric acid and three different carbon sources, i.e., cellulose, glucose, and starch. The effects of structural homogeneity of precursors on the low-temperature synthesis of B4C powder were investigated on the basis of sacchridederiven structural development. The formation of condensed products was confirmed by FTIR and TGA analyses. The conditions suitable for preparation of precursors were optimized. The precursors obtained by thermal decomposition of condensed cellulose products had more homogeneous and fine structure composed of B2O3and carbon fibers. The dispersion state of B2O3 in carbon matrix of precursors significantly affected the acceleration of synthesis reaction. The formation of B4C in the case of the cellulose precursor started at a temperature of about 1100 °C which is around 150¿250 °C lower than that for glucose and starch precursors. The B4C formation completed for cellulose precursor at 1200 °C (one of the lowest temperatures reported for polymeric precursor route) within a short time because the diffusion of reacting species was favored by increasing the contact area of carbon fibers/B2O3. The B4C particles synthesized from glucose and starch precursors were polyhedral. The morphology of B4C particles, synthesized from cellulose precursor, transformed from polyhedral to equiaxed as the synthesis temperature was raised from 1150 °C to 1200 °C. The nitrogen physisorption measurements had revealed that the synthesized B4C powder exhibited the mesopores and the macropores, and the powder synthesized from cellulose precursor had the highest specific surface area among all the tested materials.

Sputter deposited thin film AlN:Er (1 at.%) emits at 554 nm and 561 nm as a result of2H11/2 ? 4I15/2 and 4S3/2 ? 4I15/2 transitions under 532 nm NdYAG laser and 783.3 nm crystal laser excitation. An external magnetic field of 0.1 T enhances the green emission and splits the 4S3/2 energy level in two sub-levels with a difference of 0.013 eV. The splitting of energy level produces new emission from Er3+ with a wavelength of 564.5 nm. Infrared emission is also observed at 1552 nm as a result of 4I13/2 ? 4I15/2 transition. Enhanced luminescence shows the suitability of Er3+ for high efficiency optical devices.

The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Koeteweg-deVries-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration.

The fabrication of a highly sensitive amperometric glucose biosensor based on silver nanowires (AgNWs) is presented. The electrochemical behavior of glassy carbon electrode modified by Ag NWs exhibits remarkable catalytic performance towards hydrogen peroxide (H2O2) and glucose detection. The biosensor could detect glucose in the linear range from 0.005 mM to 10 mM, with a detection limit of 50 µM (S/N=3). The glucose biosensor shows high and reproducible sensitivity of 175.49 µA cm-2 mM and good stability. In addition, the biosensor exhibits a good anti-interference ability and favorable stability over relatively long-term storage (more than 21 days).

The electrical transport properties of hydrothermally synthesized V2O5 nanowires were investigated by impedance spectroscopy at room temperature in the frequency range of 1 Hz¿1 MHz. The structural and morphological analyses confirm the single crystalline orthorhombic nature of the nanowires. The complex impedance plane plot showed two overlapping semicircles with dominating low frequency arc. The resistance from the oxygen vacancies and oxygen stoichiometric V2O5 NWs regions contribute to the overall transport behavior of NWs. The normalized functions ( and ) suggests that the long range movements of the charge carriers are dominant at 100 Hz. The tangent loss (tan d) was observed in accordance with the impedance plane plot. The ac conductivity sacshowed substantial increase from 1 × 10-6¿3 × 10-5 (S/cm2) in the frequency range of 5 × 103¿105 Hz attributing to a large number of charge carriers available for conduction by hopping.

The investigation of heat transfer analysis on steady MHD axi-symmetric flow between two infinite stretching disks in the presence of viscous dissipation and Joule heating is basic objective of this paper. Attention has been focused to acquire the similarity solutions of the equations governing the flow and thermal fields. The transformed boundary value problem is solved analytically using homotopy analysis method. The series solutions are developed and the convergence of thesesolutions is explicitly discussed. The analytical expressions for fluid velocity, pressure and temperature are constructed and analyzed for various set of parameter values. The numerical values for skin friction coefficient and the Nusselt number are presented in tabular form. Particular attention is given to the variations of Prandtl and Eckert numbers. We examined that the dimensionless temperature field is enhanced when we increase the values of Eckert number and Prandtl number.

With the development of digital image processing, analysis and modeling techniques, automatic retinal image analysis is emerging as an important screening tool for early detection of ophthalmologic disorders such as diabetic retinopathy and glaucoma. In this paper, a robust method for optic disc detection and extraction of the optic disc boundary is proposed to help in the development of computer-assisted diagnosis and treatment of such ophthalmic disease. The proposed method is based on morphological operations, smoothing filters, and the marker controlled watershed transform. Internal and external markers are used to first modify the gradient magnitude image and then the watershed transformation is applied on this modified gradient magnitude image for boundary extraction. This method has shown significant improvement over existing methods in terms of detection and boundary extraction of the optic disc. The proposed method has optic disc detection success rate of 100%, 100%, 100% and 98.9% for the DRIVE, Shifa, CHASE_DB1, and DIARETDB1 databases, respectively. The optic disc boundary detection achieved an average spatial overlap of 61.88%, 70.96%, 45.61%, and 54.69% for these databases, respectively, which are higher than currents methods.

It is pointed out that the analysis of the shear flow and its different limiting cases presented in the paper, Phys. Plasmas 18, 102105 (2011), using kinetic approach is misleading.

Atomistic simulations based on the static lattice model are performed to calculate the equilibrium and growth morphologies of CdS polymorphs. Morphologically important surfaces are optimized to calculate their structural and energetical properties such as surface and attachment energies. A common feature of all the nonpolar CdS surfaces is the outward movement of their anions and the inward movement of their cations. The relaxation of surfaces is critically important as it changes the surface and attachment energies significantly. The {112¯0} surface has the lowest surface energy (0.58 J/m2) for the wurtzite phase of CdS, whereas {110} surface has the lowest surface energy (0.62 J/m2) for the zincblend phase of CdS. The {101¯0}, {123¯0}, and {11¯00} surfaces of wurtzite CdS all have the same surface energy value (0.60 J/m2), which is very close to that of {112¯0} surface. Therefore, all these surfaces appear in the equilibrium morphology of the wurtzite CdS. The equilibrium morphology of the zincblend CdS is completely dominated by the {110} surface. The growth morphology of the wurtzite CdS consists of {101¯0}, {11¯00}, {0001}, and {0001¯} surfaces. The growth morphology of the zincblend CdS is found to be identical to its equilibrium morphology and, therefore, includes only the {110} surface.

In this paper, a robust image segmentation and intelligent decision making system for carotid artery ultrasound images is proposed. Medical images may have various types of inherent degradations due to imaging equipments, operating environment, etc. For instance, carotid artery ultrasound images are affected by low resolution, speckle noise, and wave interferences. Hence, robust medical image clustering technique is inevitable for obtaining accurate results in the subsequent stages. In this context, a robust fuzzy radial basis function network (RFRBFN) technique is proposed. The proposed technique modified fuzzy RBF algorithm by incorporating spatial information and a smoothing parameter into its objective function, consequently, the proposed technique is able to cope with noise related variations. To assess the effectiveness, the RFRBFN technique is applied to segment carotid artery ultrasound images and its performance has been evaluated against impulse, and Gaussian noises of various intensities. Performance comparison with existing methods shows that the proposed RFRBFN outperforms the existing fuzzy based c-means and RBF techniques in case of both noisy and noise-free images. Experiments on 200 real carotid artery ultrasound images reveal the proposed technique offers effective segmentation results. Finally, intima-media thickness is measured from the obtained segmented images and multi-layer backpropagation neural network is employed to classify the segmented images into normal or diseased subjects. The proposed intelligent decision making system can thus be used as a secondary observer for identification of plaque in the carotid artery.

The structural, electronic, and magnetic properties of ferromagnetic bismuth ferrate (Bi2Fe4O9) are investigated using density functional theory (DFT). Different exchange¿correlation (xc) functionals (LSDA, PBE-GGA, PBEsol-GGA and WC-GGA) are tested to calculate various properties of Bi2Fe4O9. All the exchange correlation functionals accurately describe the structural properties of Bi2Fe4O9 but fail to calculate its correct band structure. The calculated band structure improves when DFT + U method is employed. The PBE-GGA + U calculations predict a bandgap of 2.1 eV for the ferromagnetic Bi2Fe4O9 in close agreement with the experiment. The calculated density of states shows appreciable hybridization between Fe-3d states and O-2p states along with minor overlap between Bi-6p and O-2p states. The magnetic properties of Bi2Fe4O9 are primarily due to Fe3+ ions, each of which has a non-integer magnetic moment of approximately 3.9 µB. The values of the induced magnetic moments at the other atomic sites depend on their local environments.

In this work, structural and electrical properties of Y0.5Ca0.5MnO3 are investigated by employing X-ray diffraction and impedance spectroscopy, respectively. Applied ac electric field showed the charge ordering transition temperature around 265 K and below this temperature the heteromorphic behavior of the sample is discussed in the proximity of TCO. With frequency effects the volume of robust charge orbital ordering (COO) domains diminishes due to different competing phases along with Jahn Teller distortions. Comprehensive melting and collapse of charge orbital ordering occurs below TN(125 K), where a colossal drop in the value of impedance is observed. The change in profile of modulus plane plots determines the spreading of relaxation time of intermingled phases. Hopping mechanism is elaborated in terms of strong electron phonon coupling. Variable range hopping model and Arrhenius model are used to discuss the short and long range hopping between Mn3+ and Mn4+ channels assessing the activation energy Ea.

Current investigation deals with the effect of grain growth process as a function of sintering temperature on the electromagnetic properties (initial permeability, impedance, and gain) of Mn¿Zn ferrite (MZF) cores (toroids). By employing auto combustion process, nanosized [(20 ± 5) nm] MZF powders were synthesized and toroid shape cores were obtained after subsequent calcination and firing (sintering) process. It was observed that the submicron structure (0.5 µm) achieved in the ferrite core sintered at 1,000 °C was gradually transformed into micron size grains by increasing the firing temperature i.e., 1,100, 1,200, and 1,350 °C. The results reveal that MZF core sintered at low temperature (1,000 °C) showed high impedance, low initial permeability, and narrow working frequency range i.e., 3¿15 MHz. However, the improvement in initial permeability, sintered density, and operational frequency range (100 kHz¿17 MHz) was observed at high temperature (1,350 °C) firing in the inert environment. This synthesized MZF core is more suitable for miniaturized switch mode power supply applications.

Piezoelectric ceramics with compositions (Pb0.94Sr0.04) (Zr0.52Ti0.48)O3 (PZT) and (Ba0.95Pb0.05) (Ti0.99Co0.01)O3 (BT) were synthesized by conventional solid state reaction technique. Three series of 1¿3 composites; PZT/monothane-A70, BT/monothane-A70 and PZT/araldite-F were fabricated by a modified align-and-fill technique using the above mentioned piezoceramic compositions. Each series of the fabricated composite comprise five samples with variable ceramic contents (12¿35 vol.%) and four samples with fixed ceramic volume fraction (28%) and varied ceramic aspect ratio (0.34¿1.00). Dielectric, elastic and resonant characteristics of theses samples were measured. Effects of active piezoceramic composition and polymer influence on the electrical and mechanical properties of fabricated composites as a function of ceramic volume fraction were investigated. Results revealed that PZT based composites exhibit superior properties due to high piezoelectric charge coefficient (d33 ~ 335 pC/N) and high electromechanical coupling coefficient (k33 ~ 67%) compared to those of BT composites. It was also observed that electromechanical properties of composites are highly affected by the stiffness of the passive polymer matrix. Low stiffness (C33D ~ 21¿55 GPa) PZT/monothane-A70 composites have better acoustic impedance (Z ~ 6¿14 Mrayl), high piezoelectric charge coefficient (d33 ~ 202¿271 pC/N), high hydrostatic charge coefficient (dh ~ 136¿171 pC/N), high hydrostatic voltage coefficient (gh ~ 33¿114 × 10-3 Vm/N) and high figure of merit (FOM ~ 4488¿19,364 fm2/N) compared to PZT/araldite-F composites encompassing high stiffness (C33D ~ 23¿60 GPa). The influences of ceramic aspect ratio on the electrical properties of fabricated 1¿3 composites are also discussed.

The Kadomtsev¿Petviashvili (KP) equation for electrostatic ion acoustic solitons in a warm electronegative plasma with q-nonextensive electrons is derived. It is pointed out with the help of some suitable parameters that the phase speed of two acoustic modes and two-dimensional KP solitons are significantly modified by variation of quantities such as q (nonextensive parameter), a (the ratio of the mass of negative to positive ion), µ (the electron to positive ion number density ratio) and &${{\theta }_{i}}$; (the ratio of positive ion to electron temperature).

First-principles density functional theory (DFT) calculations were carried out to investigate the structural and electronic properties of beryllium (Be) doped and Be and boron (B) co-doped graphene systems. We observed that not only the concentration of impurity atoms is important to tune the band-gap to some desired level, but also the specific substitution sites play a key role. In our system, which consists of 32 atoms, a maximum of 4Be and, in the co-doped state, 2Be and 3B atom substitutions are investigated. Both dopants are electron deficient relative to C atoms and cause the Fermi level to shift downward (p-type doping). A maximum band gap of 1.44 eV can be achieved on incorporation of 4Be atoms. The introduction of Be is more sensitive in terms of geometry and stability than B. However, in opening the energy gap, Be is more effective than B and N (nitrogen). Our results offer the possibility to modify the band-gap of graphene sufficiently for utilization in diverse electronic device applications.

Comprehensive microstructural, electronic and magnetic analyses have been carried out on ZnO:Cu thin films grown by pulsed laser deposition on c-plane sapphire under different oxygen partial pressures. Detailed X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM) analyses reveal that increase in oxygen growth pressure degrades the epitaxy of ZnO:Cu thin films due to inclusion of nanosize CuO in the ZnO host lattice. HRTEM and magnetization studies suggest that thin film quality plays a less effective role in governing the magnetic properties of these samples. Instead, room temperature ferromagnetism (FM) of these ZnO:Cu thin film samples are highly tunable by the simultaneous presence of CuO nanophases and multivalent Cu and concentrations, which are in strong contest with each other. For low oxygen partial pressure grown sample, the effective network is the main contributor to the observed FM and is in competition with CuO nanophases only when there is a relatively low concentration with a dominant Cu2+ oxidation state. For vacuum grown samples containing high concentration and Cu1+ as dominant oxidation state, the network becomes less effective and a CuO nanophase (4-5 nm) is the dominent FM supplier. The extrinsic FM in the vacuum grown sample, which is the best epitaxial quality sample, is further confirmed by the zero field cooled (ZFC) and field cooled (FC) magnetization protocols.

Understanding and controlling structural properties of the materials are crucial in materials research. In this paper, we report that crystallinity and crystallographic orientation of Pd nanowires can be tailored by varying the fabrication conditions during electrochemical deposition in polycarbonate ion-track templates. By changing the deposition temperature during the fabrication process, the nanowires with both single- and poly-crystallinities were obtained. The wires with preferred crystallographic orientations along [111], [100], and [110] directions were achieved via adjusting the applied voltage and temperature during electrochemical deposition.

SiC nanowires are produced by employing a novel synthesis process involving the carbothermal reduction reaction of Polyacrylamide (PAM)-assisted low-temperature combustion synthesis (LCS) precursors. PAM-assisted LCS mixtures with high specific surface area and fibers with various size are used as precursors. The precursors, derived from silicic acid (Si source), PAM (additive), nitric acid (oxidizer), urea (fuel), and glucose (C source) mixed solution, are prepared by PAM-assisted LCS method. The prepared precursors have exhibited a high contact area of reactants. The carbothermal reduction of these high specific surface area precursors results in the formation of pure and well-distributed SiC nanowires with a diameter of 50 nm and a length of up to several micrometers. The effects of PAM contents and carbothermal reduction parameters on the production of SiC nanowires are discussed in detail. The precursors and corresponding carbothermal reduction products are investigated by FESEM, TEM, HRTEM, and XRD analyses.

Linear and nonlinear dynamics of electron temperature gradient mode along with parallel electron dynamics is investigated by considering hydrodynamic electrons and non-Maxwellian ions. It is noticed that the growth rate of ?e-mode driven linear instability decreases by increasing the value of spectral index and increases by reducing the ion/electron temperature ratio along the magnetic field lines. The eigen mode dispersion relation is also found in the ballooning mode limit. Stationary solutions in the form of dipolar vortices are obtained for both circular and elliptic boundary conditions.It is shown that the dynamics of both circular and elliptic vortices changes with the inclusion of inhomogeneity and non-Maxwellian effects.

The aim of present paper is to provide mathematical modelling for the two-dimensional MHD flow with induced magnetic field. The flaws in the already existing equations have been pointed out. The results of low magnetic Reynolds number approximation are recovered as a special case from the developed equations. As an example, the peristaltic flow for a couple stress fluid in a channel is considered. For the solution of the problem the governing equations are simplified under the realistic assumption of long wavelength. Exact solution of the problem is presented and some features of peristaltic motion have been discussed. It is observed that the applied magnetic field increases the pressure rise in the pumping region. However, the presence of applied electric field reduced it in that region. It is also found that the stream function is independent of applied electric field.

The properties of dust acoustic and drift waves are investigated in a charge varying magnetized dusty plasma. The plasma is composed of non-thermal electrons and ions with dynamic dust particles. The mathematical expression which describes the dust charge fluctuation is obtained using -distribution for both the electrons and ions. A dispersion relation is derived and analysed numerically by choosing space plasma parameters. It is found that the inclusion of variable dust charge along with the non-thermal effects of electrons and ions significantly affect linear/nonlinear properties of the dust acoustic and dust drift waves. The effects of different physical parameters including spectral index (), dust charge number (), electron density () and ion temperature () on the wave dispersion and instability are presented. It is found that the presence of the non-thermal electron and ion populations reduce the growth rate of the instability which arises due to the dust charging effect. In addition, the nonlinear vortex solutions are also obtained. For illustration, the results are analysed by using the dusty plasma parameters of Saturn¿s magnetosphere.

Linear and nonlinear ion-acoustic waves are studied in a fluid model for non-relativistic, unmagnetized quantum plasma with electrons with an arbitrary degeneracy degree. The equation of state for electrons follows from a local Fermi-Dirac distribution function and apply equally well both to fully degenerate or classical, non-degenerate limits. Ions are assumed to be cold. Quantum diffraction effects through the Bohm potential are also taken into account. A general coupling parameter valid for dilute and dense plasmas is proposed. The linear dispersion relation of the ion-acoustic waves is obtained and the ion-acoustic speed is discussed for the limiting cases of extremely dense or dilute systems. In the long wavelength limit the results agree with quantum kinetic theory. Using the reductive perturbation method, the appropriate Korteweg-de Vries equation for weakly nonlinear solutions is obtained and the corresponding soliton propagation is analyzed. It is found that soliton hump and dip structures are formed depending on the value of the quantum parameter for the degenerate electrons, which affect the phase velocities in the dispersive medium.

A theoretical model is presented to analyze the calendering process wherein, the material to be calendered, is represented by the constitutive equation of a FENE-P fluid. The continuity and momentum equations are used in conjunction with lubrication theory to derive the governing equation of the flow under consideration. Exact expressions for the velocity and pressure gradients are obtained. Numerical integration is performed to compute the pressure for a given dimensionless leave-off distance. The quantities of interest in the mechanical design of calendering system such as, the force separating the two rolls and total power input into both rolls are calculated and shown graphically over a wide range of Deborah number. It is found that rheological features of the material modify the pressure, flow characteristics and all other operating variables significantly. In fact, the present analysis highlights some interesting features of the pressure and other operating variables of the calendering problem which are not reported in the available literature.

The kinetic theory of Landau damping of Langmuir twisted modes is investigated in the presence of orbital angular momentum of the helical (twisted) electric field in plasmas with kappa distributed electrons. The perturbed distribution function and helical electric field are considered to be decomposed by Laguerre-Gaussian mode function defined in cylindrical geometry. The Vlasov-Poisson equation is obtained and solved analytically to obtain the weak damping rates of the Langmuir twisted waves in a nonthermal plasma. The strong damping effects of the Langmuir twistedwaves at wavelengths approaching Debye length are also obtained by using an exact numerical method and are illustrated graphically. The damping rates of the planar Langmuir waves are found to be larger than the twisted Langmuir waves in plasmas which shows opposite behavior as depicted in Fig. 3 by J. T. Mendoça [Phys. Plasmas19, 112113 (2012)].

A complex of lincomycin was synthesized with technetium-99m. The synthesis was carried out by using SnCl 2 .2H 2 O as reducing agent and ascorbic acid as stabilizer. The effect of various parameters such as amount of ligand/reducing agent, pH value and reaction time on radio labeling process was studied. The characterization of the 99m Tc-Lincomycin was performed by HPLC and electrophoresis Biodistribution studies were carried out by analyzing the model of bacterial infectious rats (Sprague-Dawley). The uptake of infectious lesions at different time interval was also studied by using scintigraphic technique. The complex showed effective target to non-target ratio for various inflammatory or infectious lesions. The 99m Tc-Lincomycin effective binding to living bacteria and could be used successfully as an infection imaging agent.

Nonlinear ion acoustic shocks in homogenous multicomponent electron-positron-ion (e-p-i) dissipative magneto rotating plasmas are studied. Dissipation in the plasma system is included via kinematic viscosity of ions. The electrons and positrons are Lorentzian and following kappa distribution function. Reductive perturbation technique is applied to derive Korteweg de Vries Burgers (KdVB) equation. The effects of variation of positron density, positron spectral index, temperature ratio of kappa distributed electrons to kappa distributed positrons, ion kinematic viscosity and rotational frequency effects are discussed in the context of pulsar magnetosphere.

We model the current characteristics of the Dual Segmented Langmuir Probe (DSLP), which is a part of the scientific payload of the ESA satellite PROBA2. It is used for the directional measurement of plasma parameters in the ionosphere at an altitude of approximately 725 km. The DSLP consists of two independent segmented Langmuir probes. Each probe is partitioned into eight collectors: seven electrically insulated spherical segments and a Guard electrode (the rest of the sphere and a small post). The current characteristics of the DSLP are computed by using the 3D particle-in-cell code PTetra. The model is electrostatic and it accounts for a uniform background magnetic field. The computed characteristics of different probe segments exhibit significant variation which depends on their orientation with respect to the ram direction. The floating potential and ion current branch of the I-V curves of each segment illustrate the directional sensitivity of the DSLP. It is found that the magnetic field also affects the electron current branch of the I-V curves of certain segments on the DSLP. The I-V curves computed with and without the ambient magnetic field are then used to estimate the electron temperature. This study will be helpful to understand the floating potential and electron temperature anisotropies measured by the DSLP.

Transport of mercury ions (Hg (II)), through a polypropylene (Celgard 2400) supported liquid membrane (SLM), employing trioctylphosphine oxide (TOPO) as carrier and toluene as a solvent, has been investigated. The work was conducted under different operating conditions with respect to feed pH and concentration, carrier concentration, and stripping phase concentration to explore optimum conditions for maximum extraction of Hg (II) ions; 0.2?mol/L was the optimum concentration of TOPO for recovery of mercury. Experiments were conducted in the cotransport mode using hydrazine as the stripping reagent. It was observed that extraction of mercury increased with increase in concentration of hydrazine up to 0.05?mol/L when stirred at 1,500?rpm. Extraction of mercury was about 90%, under optimum conditions in 3?h. The present SLM was found to be stable for about 50?h of use.

A hybrid homotopy analysis method is presented in this paper. This method combines the features of homotopy analysis and shooting methods. In this method, the accuracy and speed of convergence is established by dividing the entire domain in subintervals. In each subinterval, the solution is approximated by employing homotopy analysis method using polynomial base functions. The proposed hybrid homotopy analysis method is computationally more efficient and offered not only numerical values, but also closed-form analytic solutions in each subinterval. The proposed method is applied to discuss the stagnation point flow of viscoelastic Walters¿ B fluid. The overshoot in the velocity profile predicted in the existing approximate numerical solutions is controlled, and physically realistic solutions are presented for both weakly and strongly viscoelastic Walters¿ B fluids. The convergence and accuracy of the obtained solutions is validated through the residual errors. It is evident from the obtained results that proposed hybrid homotopy analysis method is a powerful technique for solving nonlinear problems

The agglomerated MoSi2 powders, ideal for air plasma spraying, were prepared by spray drying and subsequent vacuum sintering of ultrafine MoSi2 powders. The apparent density and flowability were measured by an apparent density instrument and a hall flowmeter. The structure of as-prepared powders and coatings was analyzed by X-ray diffraction and scanning electron microscopy. The results indicated that resultant powders were spherical and porous. It was found that heat treatment had decreased the sphericity as well as the porosity of the MoSi2 particles. The agglomerated powders, sintered at 1300 °C for 1 h, showed 57.0% and 46% more flowability and apparent density, respectively, compared to that of the spray dried powders. The as-sintered MoSi2 powders subjected to the plasma flame exhibited a further increase in the density. The as-sprayed coating by using the agglomerated powders with a size of 30¿54 µm yielded a network structural MoSi2composite coating with MoSi2 as the major phase.

This study presents survey of gamma radiation exposure around Pakistan Institute of Nuclear Science and Technology (PINSTECH). PINSTECH hosts two research reactors, two isotope production plants and several radiochemistry laboratories. Dose measurement was performed in thirty villages around PINSTECH. The average outdoor absorbed dose rate in air was 59 ± 16 nGy h-1. The average annual outdoor dose rate due to terrestrial gamma-rays was 71.4 ± 20.0 µSv y-1. The annual collective effective dose equivalent was 415 man-Sv and the estimated excess life-time cancer risk was 7.3 × 10-4. The study revealed that inhabitants living in the area surrounding PINSTECH were radiologically safe.

In this paper, effects of Hall currents and nonlinear radiative heat transfer in a viscous fluid passing through a semi-porous curved channel coiled in a circle of radius R are analyzed. A curvilinear coordinate system is used to develop the mathematical model of the considered problem in the form partial differential equations. Similarity solutions of the governing boundary value problems are obtained numerically using shooting method. The results are also validated with the well-known finite difference technique known as the Keller-Box method. The analysis of the involved pertinent parameters on the velocity and temperature distributions is presented through graphs and tables.

A nonlinear Zakharov¿Kuznetsov (ZK) equation for ion acoustic solitary waves (IASWs) is derived using the reductive perturbation method (RPM) for magnetized plasmas in which the inertialess electrons and positrons are nonextensively -distributed while ions are assumed to be warm and inertial. It is found that both compressive as well as rarefactive solitons coexist in the present model for different regions of non-extensive electron and positron parameters,  and . The magnetic field has no effect on the amplitude of the IASW, whereas the obliqueness angle of the wave propagation, the ion-to-electron temperature ratio  and positron-to-ion density concentration ratio  affect both the amplitude and the width of the solitary wave structures. The transverse instability analysis illustrates that the one soliton solution has a constant growth rate, and it suffers from instability in the transverse direction. The relevance of the present study to astrophysical space plasmas is also discussed.

Multiferroic composites of (1 - x)PbZr0.52Ti0.48O3 + (x)CoFe2O4 with x = 0.0, 0.15, 0.30, 0.45 and 1.0 are synthesized by using ball milling method. Rietveld refinement of XRD patterns confirmed the single phase formation in x = 0.0 and x = 1.0 and two distinct phase formation in x = 0.15, 0.30 and 0.45 composites. SEM images explored the effect of CFO content on the grain connectivity of each phase in the prepared composites. The dielectric properties showed dielectric dispersion with increasing frequency due to interfacial polarization; whereas the dielectric constant is found to increase with increasing CFO content which is attributed to the space charge effect. AC conductivity analysis suggested the mixed polaron hopping type of conduction mechanism. Magnetic hysteresis loops exhibited ferromagnetic like behaviour, indicating the presence of ordered magnetic structure in the prepared composites. Furthermore, with increasing CFO content, the saturation magnetization, magnetostriction and strain sensitivity is found to be increased which in turn have a significant effect on the magnetoelectric coefficient. The maximum magnetoelectric coefficient of 1.45 mV cm-1 Oe-1is obtained for x = 0.30 composite. Here, the observed variation in the magnetoelectric coefficient is correlated with the microstructure as well as the amount of CFO content.

A pressure driven axisymmetric ow in a circular tube, having a non-Newtonian Oldroyd 8-constant uid in the core, is considered in this paper. The Oldroyd8-constant uid is surrounded by a Newtonian uid in the present study. The exact solution of the governing equation is obtained in the form of an integral which is evaluated using Gaussian quadrature. The expression for the apparent viscosity is obtained. The graphical results are presented for the pro_les of apparent viscosity for di_erent values of the material parameters plotted against tube radius. It is found that for all the values of the material parameters, the apparent viscosity decreases as the tube radius decreases which is the Fahraeus-Lindqvist e_ect. The results for the case, when there is no Newtonian uid present in the periphery, are also deduced.

The double perovskite Sr2FeCoO6 oxide powder has been prepared by nitrate-citrate gel-combustion process for different ratios of citric acid and metals under various pH values and calcined at 700oC for the complete decomposition of the carbonaceous residues. The effect of pH on crystal development and ionic state of iron has been determined by X-ray diffraction and Mössbauer spectroscopic studies. The analysis revealed that calcinated powder is a single phase cubic perveoskite structure SrFe0.5Co0.5O3 with space group Pm3m and lattice parameter 3.867 Å. Mössbauer spectroscopic results indicate that as-synthesized and calcined samples have mixed ionic states like Fe3+, Fe3.5+ and Fe4+ in the tetrahedral framework of SrFe0.5Co0.5O3.

We have presented a mechanism to explain why the resulting oxide morphology becomes a porous or a tubular nanostructure when a zircaloy is electrochemically anodized. A porous zirconium oxide nanostructure is always formed at an initial anodization stage, but the degree of interpore dissolution determines whether the final morphology is nanoporous or nanotubular. The interpore dissolution rate can be tuned by changing the anodization parameters such as anodization time and water content in an electrolyte. Consequently, porous or tubular oxide nanostructures can be selectively fabricated on a zircaloy surface by controlling the parameters. Based on this mechanism, zirconium oxide layers with completely nanoporous, completely nanotubular, and intermediate morphologies between a nanoporous and a nanotubular structure were controllably fabricated.

A theoretical model of a nonlinear hyperbolic metamaterial is presented in the form of a stack of subwavelength layers of linear plasmonic and nonlinear dielectric materials. A broad picture of the properties of evanescent waves (high-k modes) in this stack is investigated by plotting global transmission diagrams. The presence of nonlinearity strongly modifies these diagrams. The emergence and modification of nonlinear evanescent waves is observed. Some signatures of nonlinear phenomenon such as formation of orbits and trajectories around fixed points are also seen in our work.

Development of thin, flexible, light-weight, renewable, low-cost, and environmentally friendly electrode materials are highly feasible in era of modern disposable electronic technology. This article presents the synthesis and dielectric studies of polypyrrole (PPy) coated pulp fibers, directly collected from wasted egg holder's tray. PPy coated pulp fibers converted into compact sheet for the development of potential renewable and low-cost electrode materials. The morphology, chemical structure, and thermal stability of naked and PPy coated pulp fibril sheets were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA), respectively. PPy coated pulp fibers revealed better thermal stability and compactness of sheet morphology. Impedance measurements showed a high value of dielectric constant of 1.15 × 106 at 0.5 Hz and conductivity of 7.45 × 10-4 S/cm at room temperature for PPy coated pulp fibril sheet. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42422.

Cerium activated yttrium aluminium garnet (Y3Al5O12; YAG) powder was synthesized by co-precipitation method using aluminium nitrate, yttrium nitrate and cerium nitrate as starting materials and ammonium carbonate as precipitant. The concentration of cerium (Ce) was varied from 0.02 to 0.1 mol. The precursor of Ce doped YAG was calcined at 1250 °C for 1¿12 h for achieving different morphology of particles. X-ray diffraction analysis was carried out to confirm the formation of YAG phase. Electrophoretic deposition was used for uniform coating of synthesized YAG:Ce powder on glass substrate. The deposition time was varied from 1 to 9 min for achieving different thickness of coating. Photoluminescence property of coating was investigated as a function of dopant concentration, particle morphology and coating thickness. The excitation wavelength used in this investigation was 430 nm. YAG:Ce showed peak emission at ~530 nm. The maximum emission intensity was achieved at Ce content of 0.04 mol in YAG with spherical morphology of particles having 300 nm particle size and 11 µm coating thickness.

In this paper we study the ion acoustic oscillatory and monotonic shocks in dissipative homogeneous magnetized plasmas. The dissipation in the plasma system is considered via kinematic viscosity of ions and quantum effects are included through degeneracy pressure of ultra-relativistic electrons. Korteweg de Vries Burgers (KdVB) equation is derived by using reductive perturbation method. Numerical and analytical solutions of KdVB equation are presented. The transition from oscillatory profile to monotonic shock are studied numerically at different values of kinematic viscosity. We also analyzed the effects of variations of different plasma parameters on the strength of the shock structure in dense plasmas. The relevance of the work to astrophysical plasma conditions such as in compact stars is also pointed out.

In this paper, the flow of couple stress fluid is investigated in a helical screw rheometer (HSR). By unwrapping the channel, lands, and the outside rotating barrel, the geometry of HSR is approximated as a shallow infinite channel. Both one- and two-dimensional analysis of the problem is presented using rectangular coordinates. In either case an exact solution of the flow problem is presented and the formulas of velocity profile and volumetric flow rate are obtained as a function of couple stress parameter. It is observed that velocity profile decreases in going from Newtonian to couple stress fluid which indicates a decrease in extrusion process for a couple stress fluid in comparison with Newtonian fluid. Moreover, the volumetric flow rate is found to be a decreasing function of couple stress parameter.

The Mössbauer spectroscopy and X-ray di_raction techniques have been used to investigate the e_ect of boron concentration on the structural and magnetic properties of as-quenched and heat-treated melt-spun alloys Nd7:5Pr2:5Fe90??xBx (x = 6, 8, 10) produced by melt-spinning technique. X-ray di_raction and Mössbauer spectroscopy results indicate that as-prepared samples are completely amorphous in nature. The X-ray di_raction patterns of samples heat-treated at 700_C are indexed as Fe3B, _-Fe, (NdPr)2Fe14B and Fe23B6 phases. The Mössbauer spectra of heat-treated samples are very complex and constituted a number of sextets and a quadrupole doublet. Two main phases are (NdPr)2Fe14B hard and t-Fe3B soft magnetic phases while _-Fe and Nd23Fe6 are detected as minor phases. The average internal magnetic _eld decreases with the increase of boron content; more sharply in as-prepared and comparatively slowly in heat-treated samples. The X-ray di_raction and Mössbauer spectroscopy results are in good agreement with each other.

Highly ordered zircaloy-4 (Zr-4) oxide nanostructures with nanoporous or nanotubular morphologies are prepared using two-step anodization. The first-step anodization in ethylene glycol (EG) electrolyte containing 0.3 wt% ammonium fluoride and 0.2 wt% de-ionized water produced bundled oxide nanotubes on the surface of Zr-4. The as-grown oxide nanotubes obtained by the first-step anodization were detached ultrasonically in ethanol, leaving an ordered concave surface on the Zr-4 substrate. When the Zr-4 substrate with an ordered concave surface was secondly anodized, nanotubes with clear and open top surfaces were fabricated. In addition, the morphologies of the oxide nanostructures could be controlled to have tubular or porous structure only by changing the electrolyte from EG to glycerol in the second anodization.

In the present study, x-ray absorption fine structure (XAFS) spectroscopy has been employed to investigate the cationic distribution in Zn1-x Ni x Fe2O4 (x = 0.0 to 1.0) spinel ferrites. The phase purity and lattice parameters of freshly synthesized Zn1-x Ni x Fe2O4 were verified by laboratory x-ray diffraction analysis. It is observed that lattice parameters decrease with increase in the Ni concentration, while the system retains cubic symmetry in Fd3m space group. To investigate the local structural environment and cationic distribution, XAFS data were collected at room temperature for the Fe, Zn, and Ni K-edges in Zn1-x Ni x Fe2O4, using the x-ray absorption facilities of the Elettra synchrotron source, Trieste, Italy. In the case of Fe, pre-edge features provide valuable information regarding the octahedral or tetrahedral site occupancy, while Zn and Ni edges do not show any appreciable change in the near-edge region. From extended x-ray absorption fine structure (EXAFS) spectroscopy, it is observed that all Zn and Ni atoms occupy tetrahedral and octahedral sites, respectively, whereas Fe atoms occupy octahedral sites in ZnFe2O4 but for the other compositions are present at both octahedral and tetrahedral sites. The occupancy of Fe at octahedral sites decreases with increasing Ni concentration in Zn1-x Ni x Fe2O4. These results demonstrate that the local environment of Zn does not show significant variations as the changes at second nearest neighbors are due to Fe and Ni, which have similar scattering factors. However, variations in the Ni surroundings are due to the change of Fe and Zn ratio at A sites, having a relatively larger difference in scattering factor. However, the changes observed in the EXAFS spectra of Fe are a consequence of variation in the occupancy of Fe at tetrahedral and octahedral sites.

Nickel ferrite, i.e., NiFe2O4, nanoparticles are synthesized by sol¿gel method using urea as a neutralizing agent. The formation of spinel phase and crystal structure of the as-prepared sample is analyzed by X-ray diffraction and transmission electron microscope. In order to confirm phase formation and cation arrangement, room temperature 57Fe Mössbauer spectroscopy is employed. The degree of inversion (i) estimated from the relative peak area is found to be 0.6, which confirms a mixed spinel structure of the as-prepared sample. Zero-field-cooled/field-cooled measurements showed evidence of superparamagnetic behavior associated with the nanosized particles. Hysteresis loop measurements revealed temperature-dependent magnetic properties: The coercive field (H C) decreases with increasing temperature and deviates from the Kneller¿s law for ferromagnetic nanostructures; and the saturation magnetization (M s) follows modified Bloch¿s law in the temperature range between 25 and 400 K. However, below 25 K, an abrupt increase in magnetization of nanoparticles is observed. In order to understand this behavior, an additional contribution has to be added to the core magnetization to properly fit the data. Hence, a surface correction term to the Bloch¿s law is found to describe the temperature dependence of magnetization in the core¿shell NiFe2O4 nanoparticles.

The plasma density non-uniformity gives rise to the coupling of transverse magnetic electron drift vortex (MEDV) mode with the longitudinal perturbations in dissipative and non-dissipative electronplasmas. This coupling produces partially transverse and partially longitudinal low frequencyinstabilities in classical un-magnetized laser plasmas. The MEDV mode couples with the ion acoustic wave, when the ion dynamics is also included. Both the modes have frequencies of the same order of magnitude and couple to give rise to electromagnetic instabilities in un-magnetized plasmas.

A medical linear accelerator (LINAC) room must be properly shielded to limit the outside radiation exposure to an acceptable safe level defined by individual state and international regulations. However, along with this prime objective, some additional issues are also important. The current case-study was designed to unfold the issues related to over-shielded and unplanned treatment rooms for LINACs. In this connection, an apparently unplanned and over-shielded treatment room of 610 × 610 cm2 in size was compared with a properly designed treatment room of 762 × 762 cm2 in size (i.e., by following the procedures and recommendations of the IAEA Safety Reports Series No. 47 and NCRP 151). Evaluation of the unplanned room indicated that it was over-shielded and that its size was not suitable for total body irradiation (TBI), although the license for such a treatment facility had been acquired for the installed machine. An overall 14.96% reduction in the total shielding volume (i.e., concrete) for an optimally planned room as compared to a non-planned room was estimated. Furthermore, the inner room¿s dimensions were increased by 25%, in order to accommodate TBI patients. These results show that planning and design of the treatment rooms are imperative to avoid extra financial burden to the hospitals and to provide enough space for easy and safe handling of the patients. A spacious room is ideal for storing treatment accessories and facilitates TBI treatment.

In this article, axisymmetric stagnation-point flow of a third-grade fluid over a disk lubricated with a power law fluid is considered. Due to thin lubrication layer of variable thickness, third-grade fluid experiences a partial slip on the surface. The flow problem is governed through a system of nonlinear partial differential equations with nonlinear boundary conditions. A nonsimilar solution is presented in this article by implementing hybrid homotopy analysis method. This method combines the features of homotopy analysis and shooting methods. The results varying from no-slip to full-slip case are discussed under the influence of pertinent parameters.

This paper is concerned with the effects of body acceleration on an unsteady pulsatile flow of blood in a vessel. The non-Newtonian behavior of blood is modeled by the constitutive equation of an Oldroyd-B fluid. The behavior of the blood is assumed as an Oldroyd-B fluid in the core and a viscous fluid in the periphery. This new model predicts the relaxation and retardation phenomena in a pulsatile flow. Our interest lies in investigating the effects of stress relaxation and retardation in unsteady pulsatile flow of an Oldroyd-B fluid. The modeled equations are normalized and solved numerically using finite difference method. The results are graphically displayed and influence of the pertinent parameter on various physical quantities of interest is analyzed.

We have employed density functional theory to study the C60/ZnPc interface with face-on orientation, which has recently been tailored experimentally. For this purpose, adsorption of ZnPc on C60 has been studied, while taking into account different orientations of C60. Out of various adsorption sites investigated, 6:6 C-C bridge position in apex configuration of C60 has been found energetically the most favourable one with C60-ZnPc adsorption distance of ~2.77?Å. The adsorption of ZnPc on C60 ensues both charge re-organization and charge transfer at the interface, resulting in the formation of interfacedipole. Moreover, by comparing results with that of C60/CuPc interface, we show that the direction ofinterface dipole can be tuned by the change of the central atom of the phthalocyanine molecule. These results highlight the complexity of electronic interactions present at the C60/Phthalocyanine interface.

Perovskite type LaFeO3 has been synthesized by autocombustion of the gel complex obtained from citrate and metal nitrate precursors. The crystallinity in the as-combusted powder and effects of heat treatment temperature up to 800 °C have been investigated by XRD. Thermal stability of the organic residue obtained after combustion has been studied by TGA of as-combusted powder and FTIR analysis after heat treatment at different temperatures. In addition to the crystalline LaFeO3, amorphous organic residue was found in the as-combusted powder that gradually decomposed upon heat treatment. Effects of the amorphous organic residue on the dielectric properties of LaFeO3 has been explored and discussed in details by collecting the room temperature ac impedance data in a wide frequency range for the synthesized samples. The amorphous organic residue strongly alter the resistive and dielectric properties of LaFeO3. The frequency response of the dielectric polarization is associated with the dielectric relaxations from the amorphous residual carbonates, crystalline LaFeO3 grain interiors and the grain boundaries.

The three-dimensional microstructure of cast AlSi12Ni and AlSi10Cu5Ni2 alloys is investigated by laboratory X-ray computed tomography, synchrotron X-ray computed microtomography, light optical tomography and synchrotron X-ray computed microtomography with submicrometre resolution. The results obtained with each technique are correlated with the size of the scanned volumes and resolved microstructural features. Laboratory X-ray computed tomography is sufficient to resolve highly absorbing aluminides but eutectic and primary Si remain unrevealed. Synchrotron X-ray computed microtomography at ID15/ESRF gives better spatial resolution and reveals primary Si in addition to aluminides. Synchrotron X-ray computed microtomography at ID19/ESRF reveals all the phases = ~1 µm in volumes about 80 times smaller than laboratory X-ray computed tomography. The volumes investigated by light optical tomography and submicrometre synchrotron X-ray computed microtomography are much smaller than laboratory X-ray computed tomography but both techniques provide local chemical information on the types of aluminides. The complementary techniques applied enable a full three-dimensional characterization of the microstructure of the alloys at length scales ranging over six orders of magnitude.

Ti-doped (Cu0.5Tl0.5)Ba2Ca2 (Cu3-xTix)O10-d (x = 0, 0.25, 0.50, 0.75) samples have been synthesized at 860° C by following two step solid state reaction methods and studied their superconducting properties by X-ray diffraction, resistivity, ac-susceptibility, FTIR absorption measurements. Ti-doped samples have shown orthorhombic crystal structure and the cell parameters increase with the increase of Ti-contents. The Tc(R = 0) and onset of diamagnetism increases with increase Ti-doping in the final compound. The magnitude of superconductivity, however, increases for Ti-doping of y = 0.25, 0.75. The numbers of carriers in the conducting planes have been optimized by carrying out post-annealing of the samples in oxygen atmosphere. After the post-annealing the Tc(R = 0) is improved in un-doped samples whereas it is suppressed in all Ti-doped samples. After post annealing in oxygen atmosphere, the magnitude of superconductivity (measured in emu/gm.Os) remains unchanged in un-doped samples whereas it is suppressed in all Ti-doped samples. In FTIR absorption measurements, the CuO2/TiO2 planar oxygen modes are slightly hardened in Ti-doped samples. The most likely reason for the hardening of the planar oxygen modes is decrease in the mass of Ti (47.90 amu) in comparison with Cu (63.54 amu) atoms; the atoms with lighter-mass vibrate at higher frequency. It is most likely that the existence of atoms of different masses in CuO2/TiO2 planes may suppress the density of phonon population due to setting-in of an-harmonic oscillations. The phonons of harmonic oscillation with wave vector q interact with q' of an-harmonic oscillation and produce a new phonon with wave vector Q. The phonons with wave vector Q do not contribute in the Cooper-pair formation. It is most likely that a decrease in the population of desired phonons required for higher Tc occurs that in turn suppress the density of the Cooper-pair which in turn promote a decrease in the magnitude of superconductivity. These studies indicate the essential role of electron¿phonons-interactions in the mechanism of high Tc superconductivity.

Crystalline boron carbide (B4C) powder was synthesized by carbothermal reduction of condensed boric acid-cellulose product and effect of structural homogeneity of precursor on low-temperature synthesis of B4C was investigated on basis of cellulose-derived structural development. The formation of condensed products was confirmed by FTIR and TGA analyses. The pyrolyzed products of cellulose precursor at 400 °C for 2 h were composed of fine dispersion of carbon fibers with B2O3particles. The formation of carbon fibers favored conversion kinetics of B4C synthesis. The formation of crystalline B4C started and completed at 1100 and 1200 °C, which was one of the lowest temperatures reported for polymeric precursor route. Morphology of synthesized B4C transformed from polyhedral to equiaxed as synthesis temperature was raised from 1150 to 1200 °C. Nitrogen physisorption measurements revealed that synthesized B4C powders had mesopores with high surface area indicating large interfacial area of B2O3/carbon fibers resulting in more nucleation sites.

A series of dyes using tetrachloroperylene dianhydride as fluorescent chromophore was synthesized by the substitution of suitable aliphatic and alicyclic alcohols in alkaline medium, and evaluation of dyes was done for their optical, electrochemical and thermal properties. These dyes exhibited absorption maxima ?max in the range of 440-460 nm in aqueous medium due to the presence of highly-conjugated framework. Fluorescence spectra of these dyes in water showed sharp emission peaks with small bandwidths and large fluorescence rate constants, i e., 1.36?×?10(8) to 2.25?×?10(8) S(-1). Redox potential E1/2 and band gap energy Eg were observed in the range of -0.689 to -0.784 and 2.530 to 2.610 eV, respectively. Thermal stability was noticed up to 300 °C on the basis of TG and DTA findings. The structures of perylene-azo dyes were confirmed by FTIR and NMR spectroscopy. Graphical Abstract Optical, electrochemical and thermoanalytical investigations on newly-synthesized perylene-3,4,9,10-dianhydride fluorescent dyes.

This article addresses the two-dimensional boundary layer flow of third order fluid in the region of a stagnation point over a surface lubricated with a power law fluid. The lubricant is assumed to have a thin layer of variable thickness over the surface. The third order fluid experiences a partial slip due to thislubrication layer. Mathematical model of the flow problem is represented through a system of nonlinear partial differential equations with nonlinear boundary conditions. The non-similar numerical and analyticsolutions of the transformed ordinary differential equation are obtained using hybrid homotopy analysismethod based on the combination of homotopy analysis and shooting methods. It is observed that extra drag force is required in order to achieve no-slip regime from full slip and thus slip has suppressed the effects of free stream velocity. The results varying from no-slip to full slip case are discussed under the influence of pertinent parameters.

Groundwater is considered to be the second largest contributor to the indoor radon concentration after soil. Therefore, measurement of waterborne radon has remained a point of interest for many researchers. The main objective of this study is to study waterborne radon activity in the city of Dera Ismail Khan. In this context, water samples were collected from different locations of the city and waterborne radon was measured using a pylon vacuum water degassing system and CR-39 based radon detectors. The pylon system measured waterborne radon activities in samples of hand pumps and motor driven pumps varying from 0.015 to 0.066 Bq/L and 0.021 to 0.145 Bq/L with average values of 0.041 ± 0.015 Bq/L and 0.076 ± 0.024 Bq/L, respectively. Whereas CR-39 based measured values ranged from 0.042 to 0.125 Bq/L and 0.075 to 0.158 Bq/L with average values of 0.081 ± 0.021 Bq/L and 0.120 ± 0.020 Bq/L, respectively. The estimated average annual effective dose due to ingestion of radon from drinking water using pylon and CR-39 based radon detectors for hand and motor pump samples was found to be 1.055×10-4 mSv and 1.947×10-4 mSv, and 2.067×10-4 mSv and 3.058×10-4 mSv, respectively. The waterborne radon concentrations and as a result the annual effective dose expected to be received from it are within the recommended safe limits.

Maximum removal (94±1.2%) of 2, 4 dichlorophenol (50 mg.dm-3) was achieved on silica with agitation of 4 hours, at pH 8 and 42°C. The positive enthalpy (?H) and negative free energy values (?G315K) suggested the endothermic and a spontaneous nature of sorption. The free energy of the process at all temperature was negative and increased with the increase in temperature. The values of free energy suggested a spontaneous process where the spontaneity decreased with the rise in temperature. Positive values of ?S described the randomness and a greater stability of sorption process with no structural changes at the solid-solution interface during the sorption. The data was subjected to Freundlich and Langmuir isotherms and the values of qe (mg.g-1), K1,ads and K2,ads(min-1) demonstrated that pseudo first order model was not fit for process, whereas, the pseudo second order kinetic model was best to describe the kinetics of process. The Elovich model and Intra particle diffusion kinetic model graph were best to describe the kinetics for DCP. A comparative experimental data revealed that developed method might be employed for removal of DCP from the aqueous industrial effluents before discharging them into water bodies. 

This paper is an attempt to compare the pollution status in two sediment cores, one from a polluted site (Ghizri Creek) and another from a relatively unpolluted site (Sandspit). Sediment cores (45 cm in length) from coastal locations were characterized in terms of grain size, sediment composition, pH, organic matter, calcium carbonate, and metal element contents. Metal elements, including Al, Ca, Cr, Co Cu, Fe, K, Mg, Mn, Ni, Pb, V, Ti, and Zn, were determined using PIXE. Grain size analysis and sediment composition demonstrated a sandy nature of both cores. Acidic trend in sediment core I was predominant from bottom to top, whereas neutral pH was observed throughout core II. TOC values varied in the range of 1.23-2.68 and 1.14-2.60% in core I and core II, respectively; however, there was an increasing trend in TOC level from bottom to top. The values of enrichment factor for Zn, Cu, Co, Ni, Pb, and Cr were slightly higher in core I than core II. The average geo-accumulation index values for core I and core II showed that sediments were moderately Co- and Pb-polluted but not polluted with Mg, Al, Ca, K, Cr, Cu, Fe, Mn, Ni, Ti, V, and Zn. The degree of contamination was however considerably higher in core I relative to core II. The pollution load index values, although showing an increasing trend from bottom to top in both cores, overall rendered the marine sediment pollution free. The metal toxicology results demonstrated that heavy metal pollution, except Cr, may pose low to moderate risk to marine biota. The sum of toxic unit values however indicated that sediment core I was relatively more polluted than that of core II.

Being a major constituent of hard tissues found in humans, synthetic hydroxyapatite (HA) as a substitute to natural bone and teeth is gaining importance. In particular, nano hydroxyapatite is expected to impart considerably superior properties. The current research focuses on identification of mechanism of the formation of HA nano-crystals during its preparation when surfactant nano reactors are used for their nucleation and growth. In addition to having a rod-shaped morphology, high resolution electron microscopy has revealed the presence of 2-5 nm crystals within individual particles of HA. The HA particles were not completely hollow, rather nano sized spherical pores of about 5 nm size, have been observed in TEM. These pores are suggested to have formed due to evolution of gases during processing.

Two facile and efficient methods, to synthesize zinc oxide (ZnO) particles with different morphologies, have been reported here. Thermal decomposition route yielded micron sized irregular shaped ZnO particles. While co-precipitation method rendered transparent flakes which then transformed to hexagonal discs with relatively more uniform size and shape. These hexagonal discs were further converted to the cone type morphology when hexamethylenetetramine was added in the precursor solution. However, spherical type ZnO nanoparticles were obtained by incorporating polyvinyl alcohol during co-precipitation strategy. XRD confirmed the formation of wurtzite structure in all the samples. FTIR spectroscopy revealed the presence of ZnO characteristic peaks. Moreover, 3-D directional growths and the presence of UV-Vis broadband multi-absorption peaks, and green to orange photoluminescence emissions confirmed the potential application of the synthesized ZnO particles in various piezoelectric and luminescence applications.

Reflection electron energy loss spectra (REELS) have been measured on a highly oriented pyrolytic graphite (HOPG) sample. Two spectra were measured for different energies, 1600 eV, being more sensitive to the bulk and 500 eV being more sensitive to the surface. The energy loss distributions for a single surface and bulk excitation were extracted from the two spectra using a simple decomposition procedure. These single scattering loss distributions correspond to electron trajectories with significantly different penetration depths and agree with energy loss spectra measured on free standing single layer graphene and multilayer graphene (i.e. graphite). This result implies that for a layered electron gas (LEG) material, the number of layers which responds in a correlated fashion to an external perturbation is determined by the depth range penetrated by the external perturbation, and not by the number of layers actually present in the specimen.

In the present work, a two-step carbothermal reduction method is employed to prepare the AlN¿SiC solid solution (AlN¿SiCss) powders by using a combustion synthesized precursor. The precursor is prepared by low-temperature combustion synthesis (LCS) method using a mixed solution of aluminum nitrate, silicic acid, polyacrylamide, glucose, and urea. The synthesized LCS precursor exhibits a porous and foamy uniform mixture of Al2O3 + SiO2 + C consisting of flaky particles. The carbothermal reduction in the LCS precursor is carried out in two steps. First, the precursors are calcined at 1600°C in argon for 3 h. Subsequently, the precursors are further calcined at 1600°C¿1900°C in nitrogen for 3 h. The results indicate that the precursor calcined at and above 1850°C in nitrogen for 3 h yields the single-phase AlN¿SiCss powders. The synthesized AlN¿SiCss powder exhibits near-spherical particles with diameter of 200¿500 nm. The experimental and thermodynamical results reveal that the formation of AlN¿SiCss occurs via the diffusion of AlN into SiC by virtue of formation of a highly defective ß' intermediate during the second step reaction.

The present study deals with the flow and heat transfer analysis of two immiscible fluids in an inclined channel embedded in a porous medium. The channel is divided in two phases such that a third grade fluid occupies the phase I and a viscous fluid occupies the phase II. Both viscous and third grade fluids are electrically conducting. A constant magnetic field is imposed perpendicular to the channel walls. The mathematical model is developed by using Darcy's and modified Darcy's laws for viscous and third grade fluids respectively. The transformed ordinary differential equations are solved numerically using a shooting method. The obtained results are presented graphically and influence of emerging parameters is discussed in detail.

The 6061-Al powder was degassed under vacuum, argon and hydrogen before mixing with 5 mass.% B4C particles. After compaction, the supersolidus liquid phase sintering was performed at 630oC under high purity argon and nitrogen atmosphere. The purpose of this experimental plan was to study the effect of different degassing and sintering environments on the compressibility and sinterability of Al/B4C composites. The efficacy of degassing condition in-terms of sintered density is in the order of hydrogen, argon and vacuum (highest). Al/B4C composite sintered under argon atmosphere after vacuum degassing showed ~ 8% higher sintered density as compared to the sample with similar condition except degassing. Al/B4C composite sintered under N2 atmosphere without degassing showed ~89% density and 65 HRB while the composite sintered under N2 atmosphere after degassing in vacuum showed ~98 % density and 89 HRB with faded boundaries between 6061- Al particles in the microstructure.

In the present work reverse micro emulsion has been employed as nano reactors to synthesize nano crystalline Hydroxyapatite (HA). Two precursors; calcium and phosphate with different counter ions of each were used for the synthesis of HA at two different temperatures. To maintain the emulsified nano reactor, cyclohexane, TX-100 and 1-butanol including phosphate precursor was the continuous phase while aqueous Ca precursor solution was taken as the dispersed phase. Nano crystalline particles thus produced were evaluated on the basis of synthesis route, counter ions and temperature. It has been shown that emuslsified nano reactors control the morphology, particle size and minimize phase transformation of HA. Characterizations of nano powder of HA are carried out using x-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), and scanning electron microscopy (SEM). HA crystallite size was found to be in the range of 20-25 nm whereas the morphology of nano particles changed from spheres to rods.

A gel type acrylic acid resin, based on ethyl acrylate-co-1,7-octadiene, has been synthesized by suspension polymerization at 20% cross-linking and subsequent hydrolysis by H2SO4. Capacity of the resin was observed to be 8.90?meq/g or 3.28?meq/mL. The iron nanoparticles used in this study were synthesized by ferrous sulphate method by using LiBH4 as a reductant and characterized by SEM, TEM, XRD, surface area, and electrical properties. Later, the resin was applied for the dispersion of iron nanoparticles over its surface for the reduction of Cr(VI) and subsequent adsorption of Fe(III) and Cr(III) as byproducts. In the column studies the reduction of Cr(VI) and the adsorption of Cr(III) and Fe(III) have been observed up to 240?µmole/L.

Carbon nanotubes (CNTs) were irradiated in air at 100 kGy under gamma radiations. The Raman spectroscopy of ?-treated CNTs showed distinctive changes in the absorption bands. The CNTs were mixed with blend of chitosan (Cs)/poly (vinyl alcohol) (PVA) and crosslinked with silane. The chemical reactions between the components affected the position and intensities of the infrared bands. Scanning electron micrograph of Cs/CNTs nanocomposite membrane showed the homogeneous dispersion of CNTs in the polymer matrix. The addition of CNTs lowered its swelling in water. Naphthalene (NAPH) was selected as a model compound and its removal was studied using HPLC technique. This membrane showed fast uptake of NAPH and 87% was removed from water within 30 min. The NAPH loaded membrane showed strong chemical interactions and cannot be desorbed. The fast uptake of PAHs and the green nature of this membrane made them suitable candidates for clean-up purposes.

Nanocrystalline nickel ferrite and copper nickel ferrite materials were synthesized through surfactant Tween 80-assisted hydrothermal reaction at low temperature using metallic copper, nickel, and iron as raw materials. Thermogravimetric (TG) and differential thermal analysis (DTA) were used to determine the decomposition of the precursors. Phase composition, microstructural characterization, and distribution of cations in tetrahedral and octahedral sites of crystal structure properties of synthesized ferrite materials were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) absorption, and Mössbauer spectroscopy. The impedance spectroscopic studies of copper nickel ferrite sintered ceramics were carried out at room temperature. TG and DTA of precursors revealed that the crystallization temperature for spinel ferrites phases formation was around 650 °C which were being synthesized through Tween 80-assisted hydrothermal process in highly basic reaction at 180¿200 °C for 11¿13 h in PTFE-lined stainless steel autoclave. XRD analysis and Rietveld refinement study confirm the formation of single-phase cubic spinel nickel ferrite (NiFe2O4) and copper nickel ferrite (Ni0.5Cu0.5Fe2O4) with cell parameters 8.3385, 8.3595 Å and space group Fd3 m, respectively. The synthesized ferrite products showed extensive XRD line broadening, and the average crystallite sizes of NiFe2O4 and Cu0.5Ni0.5Fe2O4 ferrites were in range of 21¿29 nm and 18¿23 nm, respectively. Mössbauer parameters are characteristic of substituted Cu-Ni-Fe2O4 ferrite material. Isothermal shrinkage characteristic and coefficient of thermal expansion were determined by dilatometry. The ferrite specimens showed excellent densification at 1,050 °C temperature, and uniformly fine grain-sintered ceramics with submicron grain size (10¿18 µm) were obtained after sintering at 850 and 1,050 °C. Sintering at 1,050 °C, results in the formation of depletion layer at grain boundaries which act as trapping centers for the carriers and an increase in the impedance values are conferred.

We model the particle velocity distribution functions around the entrance window of the Suprathermal Ion Imager (SII). The SII sensor was mounted on a 1 m boom carried by the scientific payload of NASA rocket 36.234 as part of Joule II mission to investigate Joule heating in the E-region ionosphere. The rocket flew above Northern Alaska on 19 January 2007. The payload was spin-stabilized with a period of 1.6 s, giving an apparent rotation of the ion flow velocity in the frame of reference of the payload. The SII sensor is an electrostatic analyzer that measures two dimensional slices of the distribution of the kinetic energies and arrival-angles of low energy ions. The study is concerned with the interpretation of data obtained from the SII sensor. For this purpose, we numerically investigate ram velocity effects on ions velocity distributions in the vicinity of the SII sensor aperture at an altitudes of approximately 150 km. The electrostatic sheath profiles surrounding the SII sensor, boom and payload are calculated numerically with the PIC code PTetra. It is observed that the direction of the ion flow velocity modifies the plasma sheath potential profile. This in turn impacts the velocity distributions of NO+ and O+2O2+ ions at the aperture of the particle sensor. The velocity distribution functions at the sensor aperture are calculated by using test-particle modeling. These particle distribution functions are then used to inject particles in the sensor, and calculate the fluxes on the sensor microchannel plate (MCP), from which comparisons with the measurements can be made.

Density functional theory calculations were performed to examine the formation of oxygen atom vacancies on three model surfaces namely, clean anatase TiO2(001) and, Au3 and Au10 clusters supported on anatase TiO2(001). On the Au/TiO2 systems, three different types of lattice oxygen atoms can be identified: the Ti-O-Au bridge, the Ti-O-Ti bridge in the perimeter of the Au cluster and the Ti-O-Ti bridge away from the Au cluster, the oxygen atoms on the clean surface. The variation in ?G° with temperature for surface O vacancy formation was calculated for these three situations using total-energy, vibrational structure and optimized geometries of the material surfaces and the O2 molecule. The calculations reveal that the O defect formation on the clean anatase TiO2(001) surface seems very difficult due to the large positive value of ?G° (290 kJ mol(-1)) from 0 to 650 K. However, the presence of the Au cluster on the TiO2 surface changes the surface chemistry of the TiO2 significantly. We observed that the trend in ?G° variation for the vacancy formation from the Ti-O-Au bridge is the same as on Au3/TiO2 and Au10/TiO2 systems, almost constant with large positive values of ?G° around 250 and 350 kJ mol(-1), respectively. The ?G° for the perimeter defect formation (Ti-O-Ti bridge in the perimeter of the Au cluster) is smaller for Aun/TiO2 systems than the clean TiO2 surface, however, the vacancy formation is possible only for the Au10/TiO2 system (close to 506 K). Finally, extended calculations for other oxygen atoms on the Au10/TiO2 model reveal that the trend in ?G° variation is similar for all the interface or perimeter O atoms around the Au cluster with marginal differences in the numerical value of ?G°. Since, the surface O atoms are activated only in the presence of a particular sized Au, we propose that a Au catalyzed Mars-van Krevelen mechanism could be a possible reaction mechanism for CO oxidation on Au/TiO2 catalysts at slightly elevated temperatures.

Density functional theory calculations were performed to model a reaction relevant bimetallic surface and study the water gas shift reaction. It was found that under vacuum, Pd prefers to stay in the bulk due to more negative formation energies. However, the strong CO-phillic nature of Pd makes the surface segregation of Pd a relevant process, with segregation energy increasing linearly with the number of Pd atoms segregated. Therefore, it is expected that under CO rich environments, Pd covered Au could be the relevant structure of a Pd¿Au bimetallic surface. The surface is highly active for water dissociation and subsequent reactions leading to CO oxidation. Based on our results, it is predictable that the adsorbed carboxyl pathway will dominate the kinetics. Our results show that H2 adsorbs dissociatively on this surface, which opens new channels for research regarding the candidature of such model surfaces as hydrogen storage materials. An important consequence of our results is that they may be useful in the selective development of alloy surfaces keeping adsorbate induced surface segregations in view.

This paper describes the electromagnetic design of a new concept of permeameter capable of providing a measurement of the magnetic permeability of sheet strips up to 1.5 mm thick. The measurements are performed in DC. A specific feature of the device is its ability to follow the history of the excitation, representing an ideal tool to experimentally characterize hysteresis cycles as a function of the initial magnetization status of the material. The first preliminary results taken with measurement frame are also presented.