Self-Assembled Surfactant-Polyoxovanadate Soft Materials as Tuneable Vanadium Oxide Cathode Precursors for Lithium-Ion Batteries

The mixing of [V₁₀O₂₈]⁶⁻ decavanadate anions with a dicationic gemini surfactant ( gem ) leads to the spontaneous self-assembly of surfactant-templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge-like V₂O₅ ( gem -V₂O₅ ). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V₂O₅ consisting of very small crystallites ( TBA -V₂O₅ ). Electrochemical analysis of the materials’ performance as lithium-ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long-range microstructure of the gem -V₂O₅ cathode deliver higher initial capacity and superior capacity retention than TBA -V₂O₅ . The smaller crystallite size and higher surface area of TBA -V₂O₅ allow faster lithium insertion and superior rate performance to gem -V₂O₅ .     

Synthesis and characterization of cadmium tartrate single crystals

Efforts have been successful to crystallize the electroceramic compound of cadmium tartrate through silica hydrogel. Analysis of thermograms reveals decomposition of the crystals to take place within the temperature range 65 to 442°C in air atmosphere. Some important characteristic data, i.e., valance electron plasma energy, Penn gap, Fermi energy, interionic distance, electronic polarizability have been obtained. The DC conductivity of the crystal typically lies between the conductivities of metal and insulator and we derived several pertinent parameters such as hopping energy, hopping distance, coulomb gap, etc. The micromechanical indentation of the crystal shows nonlinear variation of the impact microhardness as a function of the applied load. The estimation of fracture toughness, fragility coefficient and yield strength has too been made for the synthesized crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Possible lattice formation of new materials within a piezoelectric semiconductor plasma

The possible lattice formation of grains of chosen material in a magnetized current carrying n-type piezoelectric semiconductor plasma has been examined. In addition to the repulsive Coulomb potential, there appears a non-Coulombic oscillatory potential among the highly charged grains due to the strong resonant collective interaction of the grains and the electron-acoustic mode of the host semiconductor giving rise to the possibility of the lattice formation of grains of new materials.     

An algebraic closure for the DNS of fiber-induced turbulent drag reduction in a channel flow

An algebraic closure for the non-Newtonian Navier–Stokes equations is presented which accounts for the effect of a dilute fiber suspension. The model is intended to be used in simulations of turbulent drag reduction by fiber additives, and can be considered as a computationally efficient alternative to the existing rheological models for fiber suspensions in turbulent wall-bounded flows. It is based on the assumption that the suspended elongated particles are aligned with the local velocity fluctuation vector. The model is proved to be Galilean invariant. One-way coupled simulations and comparison with a direct solution of the underlying Fokker–Planck equation show a considerable improvement over an existing and comparable model. Finally, two-way coupled simulations demonstrate that the model predicts flow statistics that are in very good agreement with those obtained by the moment approximation approach. Interestingly, the model is realistic in terms of the polymer concentration. Using the proposed model, the cost of simulating a drag-reduced flow in terms of CPU-time is slightly more than that of a Newtonian flow.     

Numerical simulation of flow-induced fiber orientation using normalization of second moment

A normalization scheme for the numerical solution of the moment approximation equation in fiber suspension flows is presented. Here, normalization refers to rescaling the trace of the second moment tensor to unity at each time step. The equivalence between the normalization scheme and the quadratic closure model is analytically proved. The performance of the scheme is investigated in simple shear flow with respect to the quadratic and hybrid closures, and a stochastic Monte-Carlo simulator that provides exact solution. The proposed scheme is a computationally efficient alternative to the quadratic closure: it performs equally well and is more efficient regarding computational time.     

Visualization of spontaneous aggregates by diblock poly(styrene)‐b‐poly(L‐lactide)/poly(D‐lactide) pairs in solution with new fluorescent CdSe quantum dot labels

Spontaneous stereocomplex aggregation of diblock poly(styrene)‐b‐poly(L ‐lactide) PS‐b‐PLLA/poly(D ‐lactide) PDLA pairs has been investigated under ambient temperature in tetrahydrofuran solution. First, diblock PS₂₆₀‐b‐PLLA₁₆₅ and PS₂₆₀‐b‐PDLA₁₆₂ bearing similar lengths of respective PLLA and PDLA blocks were synthesized through controlled atom‐transfer radical polymerization of styrene, and a subsequent living ring‐opening polymerization of optically pure lactides, and their structures were further characterized by nuclear magnetic resonance spectroscopy (NMR) and gel‐permeation chromatography (GPC). Subsequently, new enantiomeric poly(D ‐lactide) stabilized core‐shell fluorescent CdSe quantum dots (CdSe/PDLA QD) were designed and prepared as sensitive fluorescence labels to shed new lights on the spontaneous stereocomplex aggregation in THF, which was mediated by stereocomplexation of the PLLA and PDLA chains. Upon simply mixing two individual THF solution of diblock PS₂₆₀‐b‐PLLA₁₆₅ and HO‐PDLA₃₀‐SH, spontaneous stereocomplex aggregation was studied, and the aggregated uniform spherical particles were observed by scanning electronic microscopy (SEM) to exhibit average particle diameters of 2.0 μm. Finally, utilizing the prepared CdSe/PDLA QDs as new fluorescent labels, morphologies of the spontaneous aggregates by new diblock PS₂₆₀‐b‐PLLA₁₆₅/HO‐PDLA₃₀‐SH pair were for the first time directly visualized by a confocal laser scanning fluorescence microscopy (CLSFM). These results might suggest alternative ways to simply prepare functional fluorescent particles with tunable diameter sizes and would be helpful to understand the mechanism of stereocomplex particle aggregation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1393–1405, 2009     

Efficient photoelectrodes from anatase TiO2 nanotube arrays decorated with particles/rods/3D microflower rutile crystals for photoelectrochemical water splitting

Journal of Solid State Electrochemistry - Efficient photoanodes are designed of vertically aligned anatase TiO2 nanotube arrays (anatase TNTAs) decorated with different shaped rutile TiO2...     

Comparative study between chloramine-T and iodogen to prepare radioiodinated etodolac for inflammation imaging

This study describes a fast and efficient method for radiolabeling of etodolac with iodine-125 [¹²⁵I], where both chloramine-T and iodogen were used as oxidizing agents. The labeling reaction was carried out via electrophilic substitution of hydrogen atom with the iodonium cation I⁺. The labeling yield was found to be influenced by different factors such as drug concentration, pH of the reaction mixtures, different oxidizing agents, reaction time, temperature and different organic media. The radiochemical yield (RCY) was determined by TLC system using methylene chloride:ethyl acetate (3:7 v/v) as a developing solvent and by electrophoresis using cellulose acetate moistened with 0.02 M phosphate buffer pH 7. The maximum radiochemical yield of [¹²⁵I]Etodolac (87.7%) was obtained. Labeled etodolac shows a good localization in inflamed muscle. It excretes mainly via kidney and to some via liver.     

Parametric aggregation in ordered weighted averaging

Incorporating further information into the ordered weighted averaging (OWA) operator weights is investigated in this paper. We first prove that for a constant orness the minimax disparity model [13] has unique optimal solution while the modified minimax disparity model [16] has alternative optimal OWA weights. Multiple optimal solutions in modified minimax disparity model provide us opportunity to define a parametric aggregation OWA which gives flexibility to decision makers in the process of aggregation and selecting the best alternative. Finally, the usefulness of the proposed parametric aggregation method is illustrated with an application in metasearch engine.