Superconductivity and Magnetism in R 2CaBa2Cu5O z (R=La, Pr, Nd and Eu)

A series of compounds R ₂CaBa₂Cu₅O _z (R=La, Pr, Nd and Eu) have been synthesized by conventional solid state reaction and characterized for their structural, superconducting and magnetic properties. All compounds crystallize with the tetragonal LaBa₂Cu₃O _z type structure, space group P4/mmm. Among the four compounds studied here, R=La, Nd and Eu are superconductors with superconducting transition temperatures (T _c ^R=0) of 72, 40 and 55 K, respectively. On the other hand, neither superconductivity nor magnetic ordering is seen for R=Pr down to 3 K. The effect of the magnetic field on the susceptibility and (magneto) resistance for the superconducting samples has been investigated. The superconductivity of compounds with magnetic rare-earth ions Nd and Eu exhibit a profound influence of the magnetic field, whereas the application of the magnetic field has a limited effect on the La compound. The Pr compound is paramagnetic and does not exhibit magnetic ordering either.     

Visible light irradiated photocatalytic and magnetic properties of Fe-doped SnS<Subscript>2</Subscript> nanopowders

Fe-doped SnS₂ (SnS₂:Fe) nanopowders were synthesized by cost effective chemical method and characterized by thermo gravimetric-differential thermal analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and vibrating sample magnetometer techniques. The photocatalytic activity was evaluated for the degradation of congo red dye under visible light irradiation. XRD studies indicate that both the undoped and doped SnS₂ nanopowders exhibit hexagonal crystal structure with a strong (1 0 1) preferential growth. Nanosized grains are evinced from the TEM images. XPS spectra confirmed the presence of Fe in the doped samples. Photodegradation efficiency increased with increase in Fe doping concentration and the SnS₂:Fe nanopowder with 10 wt% Fe doping concentration exhibits a maximum efficiency of 93.94% after 180 min light irradiation. Ferromagnetic ordering of pure SnS₂ improved with Fe doping. The outcome of the results indicated that Fe-doped SnS₂ nanopowders are well suited as diluted magnetic semiconductor and also can be used as an efficient photocatalyst.     

Green Computing Process and its Optimization Using Machine Learning Algorithm in Healthcare Sector

Mobile Networks and Applications - Handling the information is crucial task in healthcare sector; the data mining techniques will be right choice to address the complex problems. The hybridized...     

Real Time Authenticated Spectrum Access and Encrypted Image Transmission via Cloud Enabled Fusion centre

Wireless Personal Communications - Spectrum scarcity and the number of mobile users accessing the spectrum are increasing radically, as a complement to this, under utilization of the licensed...     

Dynamic characterization of the thickness-tapered laminated plant fiber-reinforced polymer composite plates

Evolution of the laminated woven natural fiber fabric-reinforced polymer composite structures makes a way to the development of the non-uniform laminated composite structures in order to achieve the stiffness variation throughout the structure. An attempt is made in this work to carry out the experimental and numerical investigations on the dynamic characteristics of the thickness-tapered laminated woven jute/epoxy and woven aloe/epoxy composite plates. The governing differential equations of motion for the thickness-tapered laminated composite plate are developed using the h-p version FEM based on higher order shear deformation theory. The validation of the present finite element formulation is carried out by comparing the natural frequencies obtained using the finite element formulation with those natural frequencies determined experimentally. The developed model is further validated with the available literature works on tapered composite plate to confirm the efficiency of h-p version FEM. This work also explores the study of the vibrational characteristics of composite plates under the influence of plant fiber’s transverse isotropic material characteristics and porosity associated with plant fiber composites through the elastic constants evaluated in the author’s previous work. Also the influences of aspect ratios, ply orientations, and taper angles under various end conditions on the natural frequencies of the woven jute/epoxy composite plate are studied using the present finite element formulation. The forced vibration response of the thickness-tapered laminated woven jute/epoxy composite plate under the harmonic force excitation is carried out considering CFCF and CFFF end conditions.     

Detailed Physical Characterizations of Cu-rich and Ru-poor (Ru0.9Cu0.1)Sr2YCu2O7.9

The optimized nominal composition, (Ru_0.9Cu_0.1) Sr₂YCu₂O_7.9 sample, has been prepared through high-pressure and high-temperature solid-state densification method. The obtained material has been studied by X-ray (laboratory) diffraction powder technique, magnetization and detailed magneto-transport measurements. The title compound indicates bulk magneto-superconducting properties under field strengths of H=10, 100, 500 and 1000 Oe. It shows diamagnetic transition at T _d=54, 38, 20 and 8 K for H=10, 100, 500 and 1000 Oe, respectively, in the zero-field-cooled susceptibility measurements. The high-field (H=5 and 10 kOe) molar susceptibility measurements show sharp ferromagnetic transition at ∼150 K with reduced molar susceptibility values. The various field dependence of magnetization, M(H), isotherm curves recorded at constant temperatures (5, 10, 25, 50, 100 and 150 K) indicate ferromagnetic saturation, whereas the MH curves measured at 200 and 300 K conditions reveal the paramagnetic state of the compound. Though the sample showed onset transition temperature, T_c^onsetT_{mathrm{c}}^{mathrm{onset}}, at ∼34 K under different field strengths (H=0, 10, 30, 50, 70 and 90 kOe), no T_c^R=0T_{mathrm{c}}^{R=0} is seen down to 2 K. Even under relatively low applied field (ΔH=10 kOe) the title compound shows large negative magnetoresistance (MR) of about 68% at 2 K and increases with increasing the field strength up to ΔH=90 kOe (MR=77% at 2 K). This value is amazing and probably higher than other 1212 type ruthenocuprates. The title compound which shows little negative MR (about 1%) in the high temperature regions (125–300 K) is not affected much by different field strengths. Among the different fixed temperature MR(H) isotherms, the MR(H) curve measured at 5 K shows maximum negative MR of about 47% at 90 kOe compared to other four (T=50, 100, 200 and 300 K) MR(H) curves.     

Science and engineering of electrospun nanofibers for advances in clean energy,water filtration,and regenerative medicine

Nanostructured materials with high aspect ratio and one-dimensional (ID) morphology are nature’s choices when high degree of functional performances and flexible properties are concerned. Two examples are extracellular matrices in tissues of living organism, and light harvesting rods of the retina and chlorophyll. Electrospinning (E-spinning) is a simple processing technique that allows fabrication of high aspect ratio nanofibers (NFs) in a commercial scale. Electrospun nanofibers (E-spun NFs) combine a number of physical properties such as guided electron transport, strain-induced electronic properties, high mechanical strength, high degree of flexibility, large specific surface area, high electron and thermal diffusivity, and tailorable pore distribution. Our laboratory has been involved in fabrication of E-spun polymeric, inorganic, and polymer-nanocomposite fibers in random, aligned, cross-aligned, sheaths, tubes, yarns, core/shell, and trilayer morphologies. This article focuses on application of the E-spun fibers in the areas of clean energy, water treatment, and regenerative medicine in the authors’ laboratory. In addition, the article briefly reviews the progress made in these areas using E-spun NFs.     

Wrinkling in polymer film‐polymer substrate systems and a technique to minimize these surface distortions

Thermally induced wrinkling during thermoforming of a commercial multi‐layered polymer film/substrate laminate has been reported. The differential thermal expansion of component layers coupled with phase transition of the substrate with increasing temperature, determined the critical conditions for wrinkling with a specific wavelength and amplitude. An effective technique to minimize wrinkling by biaxially stretching the samples at high temperature before the forming operation, has been proposed. The samples were biaxially stretched by inflating the samples using a specially designed blowing unit retrofitted to a conventional vacuum thermoformer. This method involved heating, inflation and forming, together to provide stretch‐assisted thermoforming. During biaxial stretching the stored compressive stresses in a wrinkled sample were relieved before the forming step, producing a decorative part without losses in surface appearance. POLYM. ENG. SCI., 57:31–43, 2017. © 2016 Society of Plastics Engineers     

An experimental study of mass transfer in pulse reversal plating

An experimental study has been made of the limiting pulse current density for a periodic pulse reversal plating of copper on a rotating disc electrode from an acidic copper sulfate bath containing 0.05m CuSO₄ and 0.5M H₂SO₄. The measurements were made over a range of the electrode rotational speeds of 400–2500 r.p.m., pulse periods of 1–100 ms, cathodic duty cycles of 0.25–0.9, and dimension-less anodic pulse reversal current densities of 0 to 50. The experimental limiting pulse current data were compared to the theoretical prediction of Chin's mass transfer model. A satisfactory agreement was obtained over the range of a dimensionless pulse period ofDT/ ²=0.001–1; the root mean square deviation between the theory and 128 experimental data points was ±8.5%.Notation C _b bulk concentration of the diffusing ion (mol cm^–3) - C _s surface concentration of the diffusing ion (mol cm^–3) - D diffusivity of the diffusing ion (cm² s^–1) - F Faraday's constant (96 500C equiv^–1) - i current density (A cm^–2) - i ₁ cathodic pulse current density (A cm^–2) - i ₃ anodic pulse reversal current density (A cm^–2) - i ₃ ^* dimensionless anodic pulse reversal density defined asi ₃/i _lim - i _lim cathodic d.c. limiting current density (A cm^–2) - i _{lim, a} anodic d.c. limiting current density (A cm^–2) - i _PL cathodic limiting pulse current density (A cm^–2) - i _PL ^* dimensionless limiting pulse current density defined asi _PL/i _lim - m dummy index in Equation 1 - n number of electrons transferred in the electrode reaction (equiv/mol) - l time (s) - t ₁ cathodic pulse time (s) - i ₃ anodic pulse reversal time (s) - T pulse period equal tot ₁+t ₃ (s) - T ^* pulse period defined asDT/ ² (dimensionless) Greek letters thickness of the steady-state Nernst diffusion layer (cm) - electrode potential (V) - _de time-averaged electrode potential (V) - _m eigenvalues given by Equation 2 (dimensionless) - ₁ cathodic duty cycle (dimensionless) - ₃ anodic duty cycle in pulse reversal plating (dimensionless) - kinematic viscosity (cm² s^–1) - electrode rotational speed (rad s^–1)     

Influence of Germanium Source Dual Halo Dual Dielectric Triple Material Surrounding Gate Tunnel FET for Improved Analog/RF Performance

Silicon - This paper investigates the RF Stability performance of the Germanium Source Dual Halo Dual Dielectric Triple Material Surrounding Gate Tunnel FET Ge(SRC)-DH-DD-TM-SG-TFET using 3D -...