Synthesis and characterization of various phases of cobalt oxide nanoparticles using inorganic precursor

Controllable and uniform doping of nanowires (NWs) is the ultimate challenge prior to their effective application. Si NWs amorphize and bend toward the impinging ions under ion irradiation as a result of viscous flow. We demonstrate that thermal annealing induces a full recovery of the crystalline phase corresponding to the unbending of the NWs. The competition between Solid Phase Epitaxy and Random Nucleation and Growth at the nanoscale is the key parameter controlling the recovery.     

Thermodynamic investigations of uranium-rich binary and ternary alloys

Uranium–zirconium, uranium niobium, and uranium–zirconium–niobium alloys were synthesized by the arc melting technique and their phase transition temperatures were determined using a high temperature calorimeter. Heat capacities of U–7 wt%Zr, U–7 wt%Nb, U–5 wt%Zr–2 wt%Nb, U–3.5 wt%Nb–3.5 wt%Zr, and U–2 wt%Zr–5 wt%Nb were measured using a differential scanning calorimeter in the temperature range 303–921 K. A set of self-consistent thermodynamic functions such as entropy, enthalpy, and Gibbs energy function data for these binary and ternary alloys were reported for the first time using heat capacity data obtained in this study and required literature data.     

Synthesis and characterization of a novel copolymer of glyoxal dihydrazone and glyoxal dihydrazone bis(dithiocarbamate) and application in heavy metal ion removal from water

We demonstrate synthesis of water insoluble, novel copolymer P_A1 from condensation of glyoxal dihydrazone and glyoxal dihydrazone bis(dithiocarbamate) monomers having high capacity to remove metal ions from aqueous solution. The presence of a high atomic percentage of nitrogen and sulfur atoms in P_A1 leads to strong ligating ability with metal ions. The monomers and the polymer have been characterized by FTIR, UV–Visible spectroscopy, CHNS elemental analysis, NMR, MALDI-MS, and TG/DTA. As a proof of concept, the P_A1 is tested for its ability to remove heavy metal ions Cu²⁺, Co²⁺, Fe²⁺, Ni²⁺, Mn²⁺, and CrO ₇ ^2? from aqueous solutions. P_A1 efficiently removed metals ions from the metal solutions. The highest absorption ability has been observed toward the iron salts where 0.969 g metal salt is absorbed by 1 g polymer. This study has implication for inexpensive and efficient polymer for purification of water.     

Association reaction between SiH3 and H2O2: a computational study of the reaction mechanism and kinetics

The association reaction between silyl radical (SiH₃) and H₂O₂ has been studied in detail using high-level composite ab initio CBS-QB3 and G4MP2 methods. The global hybrid meta-GGA M06 and M06-2X density functionals in conjunction with 6-311++G(d,p) basis set have also been applied. To understand the kinetics, variational transition-state theory calculation is performed on the first association step, and successive unimolecular reactions are subjected to Rice–Ramsperger–Kassel–Marcus calculations to predict the reaction rate constants and product branching ratios. The bimolecular rate constant for SiH₃–H₂O₂ association in the temperature range 250–600 K, k(T) = 6.89 × 10^?13 T ^?0.163exp(?0.22/RT) cm³ molecule^?1 s^?1 agrees well with the current literature. The OH production channel, which was experimentally found to be a minor one, is confirmed by the rate constants and branching ratios. Also, the correlation between our theoretical work and experimental literature is established. The production of SiO via secondary reactions is calculated to be one of the major reaction channels from highly stabilized adducts. The H-loss pathway, i.e., SiH₂(OH)₂ + H, is the major decomposition channel followed by secondary dissociation leading to SiO.     

Stereoselective Bromination of 2-Vinyl Chromones Using NBS

A simple one-step synthetic methodology for stereoselective synthesis of E- and Z-3-bromo-2-vinyl chromones in quantitative yield in polar solvents under ambient conditions without the use of catalysts is reported.     

An efficient synthesis of β-ketoesters via transesterification and its application in Biginelli reaction under solvent-free,catalyst-free conditions

A simple and efficient transesterification process for the synthesis of β-ketoester derivatives has been achieved by the reaction of methyl β-ketoester with higher alcohols at 110 °C under solvent-free, catalyst-free conditions and its application in synthesis of 3,4-dihydropyrimidin-2(1H)-ones C-5 ester derivatives via Biginelli reaction has been described.     

Determination of calcium and iron in silicon and uranium silicide using ion chromatography

Two separate ion chromatography methods were developed for the determination of calcium and iron in silicon and uranium silicide. A cation exchange separation with conductivity detection was developed for Ca. A reversed phase column modified with 50 mM camphor-10-sulphonic acid was used for separating Fe. Iron was detected photometrically. Linear calibrations for Ca (0.1–10 ppm) and Fe (0.5–25 ppm) were performed. Limits of detections for Ca and Fe are 0.03 and 0.2 ppm, respectively. The precision of the methods are better than 2 % for Ca at 0.2 ppm and Fe at 2 ppm.     

Kinetics of Pu(IV) sorption by smectite-rich natural clay

Kinetics of sorption of Pu(IV) by smectite-rich clay has been studied at varying metal ion concentrations. Different concentrations were achieved using different isotopes of Pu, namely, ²³⁹Pu, ²³⁸Pu and ²³⁷Pu. ²³⁷Pu was produced by alpha induced reaction on ²³⁵U, followed by radiochemical separation of Pu from irradiated U₃O₈ target. The concentrations used are above and below the solubility of Pu(IV) under neutral pH conditions, thereby, indicating the mechanism of sorption reactions of Pu(IV) in typical laboratory experiments and field level observations. Kinetics of Pu(IV) at 10^?13 M concentration was found to be fast whereas at higher metal concentration the rate is governed by a slow step, indicating the role of formation of Pu(IV) polymeric species at the sorbent surface.     

Assessing the feasibility study of highly efficient and selective co-sequestration process for cesium and strontium utilizing calix-crown and crown-ether based combined solvent systems

Journal of Radioanalytical and Nuclear Chemistry - Efficient and selective extraction of 137Cs and 90Sr from high level liquid waste (HLLW) is of utmost importance in the back end nuclear fuel...     

Numerical Investigation of Graphene as a Back Surface Field Layer on the Performance of Cadmium Telluride Solar Cell

This paper numerically explores the possibility of ultrathin layering and high efficiency of graphene as a back surface field (BSF) based on a CdTe solar cell by Personal computer one-dimensional (PC1D) simulation. CdTe solar cells have been characterized and studied by varying the carrier lifetime, doping concentration, thickness, and bandgap of the graphene layer. With simulation results, the highest short-circuit current (I_sc = 2.09 A), power conversion efficiency (η = 15%), and quantum efficiency (QE~85%) were achieved at a carrier lifetime of 1 × 10³ μs and a doping concentration of 1 × 10¹⁷ cm⁻³ of graphene as a BSF layer-based CdTe solar cell. The thickness of the graphene BSF layer (1 μm) was proven the ultrathin, optimal, and obtainable for the fabrication of high-performance CdTe solar cells, confirming the suitability of graphene material as a BSF. This simulation confirmed that a CdTe solar cell with the proposed graphene as the BSF layer might be highly efficient with optimized parameters for fabrication.