Novel Li4Ti5O12/Sn nano-composites as anode material for lithium ion batteries

Li₄Ti₅O₁₂/Sn nano-composites have been prepared as anode material for lithium ion batteries by high-energy mechanical milling method. Structure of the samples has been characterized by X-ray diffraction (XRD), which reveals the formation of phase-pure materials. Scanning electron microscope (SEM) and transmission electron microscope (TEM) suggests that the primary particles are around 100 nm size. The local environment of the metal cations is confirmed by Fourier transform infrared (FT-IR) and the X-ray photoelectron spectroscopy (XPS) confirms that titanium is present in Ti⁴⁺ state. The electrochemical properties have been evaluated by galvanostatic charge/discharge studies. Li₄Ti₅O₁₂/Sn-10% composite delivers stable and enhanced discharge capacity of 200 mAh g⁻¹ indicates that the electrochemical performance of Li₄Ti₅O₁₂/Sn nano-composites is associated with the size and distribution of the Sn particles in the Li₄Ti₅O₁₂ matrix. The smaller the size and more homogeneous dispersion of Sn particles in the Li₄Ti₅O₁₂ matrix exhibits better cycling performance of Li₄Ti₅O₁₂/Sn composites as compared to bare Li₄Ti₅O₁₂ and Sn particles. Further, Li₄Ti₅O₁₂ provides a facile microstructure to fairly accommodate the volume expansion during the alloying and dealloying of Sn with lithium.     

Investigation on the Nonlinear Excitation in an Array of Spin Valve Pillars During the propagation of Electromagnetic Wave

We have investigated the nonlinear excitations in an array of spin valve pillars during the propagation of an electromagnetic wave. The flowing electrons exhibit spins transportation effect due to the torque experienced by the spin magnetization. From the Hamiltonian which models the spin interaction in a spin valve array, we have studied the effect of perturbation using multiple scale expansion and Reduction Perturbation method. The Landau–Lifshitz–Gilbert equation of magnetization, which models the evolution of magnetization of the ferromagnetic layer, is studied along with Maxwell’s equation for the electromagnetic waves. It is found that the system of equations reduce to the celebrated modified KdV equation. The solution of the spin excitations are localized solitons. The physically interesting solitons can be harnessed to the increase in density of memory devices.     

Synthesis of gold nanoparticles: an ecofriendly approach using Hansenula anomala

This work describes a bioassisted approach for the preparation of metal nanoparticles using yeast species Hansenula anomala. Gold nanoparticles were prepared using gold salt as the precursor, amine-terminated polyamidoamine dendrimer as the stabilizer, and the extracellular material from H. anomala as the bioreductant. It could also be demonstrated that, using our approach, small molecules such as cysteine can act as stabilizers as well. This synthetic approach offers a greener alternative route to the preparation of gold sols that are devoid of cellular and toxic chemical components. The ability of as-synthesized gold sol to function as biological ink for producing patterns for the analysis of fingerprints and to act as an antimicrobial reagent is evaluated. The generality of this toxin-free synthetic approach to other metals was assessed using palladium and silver.     

Investigations on the Magnetization Switching Dynamics in Spin Valve Multilayers Under Periodic Applied Magnetic Field

Magnetization switching dynamics in a spin valve nanopillar, induced by spin transfer torque in the presence of a periodic applied field is investigated by solving the Landau–Lifshitz–Gilbert–Slonczewski equation. Under steady state conditions, the switching of magnetization occurs in the system, above a threshold current density value J _c. A general expression for the critical current density is derived and it is shown that this further reduces when there is magnetic interface anisotropy present in the free layer of the spin valve. We also investigated the chaotic behavior of the free layer magnetization vector in a periodically varying applied magnetic field, in the presence of a constant DC magnetic field and spin current. Further, it is found that in the presence of a nonzero interfacial anisotropy, chaotic behavior is observed even at much smaller values of the spin current and DC applied field.     

Crystal chemistry and properties of mixed ionic-electronic conductors

Oxides exhibiting mixed oxide-ion and electronic conducting (MIEC) properties have been attracting great interest in recent years due to their technological applications in solid-state electrochemical devices such as solid oxide fuel cells (SOFC), oxygen separation membranes, and electrochemical sensors. This article provides an overview of the composition-structure–property-performance relationships of several mixed conducting oxides: disordered ABO₃ perovskite oxides, A-site ordered layered LnBaCo₂O_5+δ (Ln = lanthanide) perovskite oxides, Ruddlesden-Popper series of perovskite-based (La,Sr)_n+1M_nO_3n+1 (n = 1–3 and M = Fe, Co, and Ni) intergrowth oxides, and hexagonal RBa(Co_1-yM_y)₄O₇ (R = rare earth or alkaline earth and M = Zn) oxides. Based on the available data, the role of chemical composition, crystal chemistry, and chemical bonding on the electrical and ionic transport, thermal, and electrochemical properties is discussed.     

Effect of Process Parameters on Microstructure and Mechanical Properties of Al-11.5%Si-1%Mg/bimodal SiC(m–n)composites

Silicon - Bimodal size SiC particles reinforced Al-Si alloy composites were fabricated by powder metallurgy route. Three different bimodal reinforcements with various volume fractions of micro and...     

Dynamic analysis of concrete pavements resting on a two-parameter medium

An analysis procedure based on the finite element method is presented to solve moving-load problems of rigid pavements. The algorithm presented considers the dynamic pavement-aircraft interaction effects. The pavement-foundation system is modelled by thin-plate, non-conforming finite elements resting on a two-parameter elastic medium. The moving aircraft loads are represented by masses supported by a spring-dashpot system moving at a specified initial horizontal velocity and acceleration. The accuracy of the finite element program developed is verified by comparing the numerical results of a static problem with the available solution. A parametric study is conducted to determine the effects of the various parameters on the dynamic response of pavements. Emphasis is placed on identifying the influence of fictitious edge and corner forces acting on the plate due to the deformation of the soil medium outside the plate.     

Bioglass® coated poly(DL‐lactide) foams for tissue engineering scaffolds

The purpose of this study was to prepare poly(DL‐lactic acid) (PDLLA)/Bioglass® composites of foam‐like structure, to measure the degree of bioactivity of the composites by studying the formation of hydroxyapatite (HA) after immersion in simulated body fluid (SBF) and to test the initial attachment of human osteoblasts within the porous network. It was found that crystalline HA formed on the Bioglass® coated PDLLA foams after 7 days of immersion in SBF. HA formed also on the surfaces of non‐coated PDLLA foams, however the rate and amount of HA formation were much lower than in the composites. The rapid formation of HA on the Bioglass®/PDLLA foam surfaces confirmed the high bioactivity of these materials. Osteoblasts attached within the porous network throughout the depth of the foams. Cell density was found to be higher in the PDLLA/Bioglass® composites compared to the pure PDLLA foams. The composite foams developed here exhibit the required bioactivity to be used as scaffolds for bone tissue engineering.     

Compatibility studies on polystyrene and poly‐n‐butyl methacrylate

Polystyrene (PS) was a solution blended with poly‐n‐butyl methacrylate (PnBMA) at different compositions and the interactions between the two polymers were studied by using viscometry, ultrasound studies, and mechanical properties. All the properties show a characteristic variation in three stages. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2322–2330, 2002