Growth and thermal behavior of mixed crystals of calcium cadmium tartrate in silica gels

In this study, calcium cadmium tartrate single crystals were grown in silica gel at ambient temperature. Effects of various parameters like gel pH, gel aging, gel density, and concentration of reactants on the growth of these crystals were studied. Crystals having different morphologies and habits were obtained. Transparent, diamond-like pyramidal-shaped crystals of calcium cadmium tartrate were obtained. Some of the crystals obtained were faint yellowish, with some milky white crystals being attched to them due to fast growth rate; faces are well developed and polished. The grown crystals were characterized by thermoanalytic techniques (TG, DTA, and DTG), and powder X-ray diffraction (XRD). The crystal system is confirmed to be orthorhombic having lattice parameters a = 7.9411 Å, b = 7.0396 Å, and c = 6.7271 Å as determined by powder XRD analysis. TG, DTA, and DTG analyses show a remarkable thermal stability. The results of these observations are described and discussed.     

Bis-(2-ethylhexyl) carbamoyl methoxy phenoxy-bis-(2-ethylhexyl) acetamide [BenzoDODA]—first selective extractant for plutonium(IV) recovery (SEPUR) from acidic media

A novel extractant, namely, Benzodioxodiamide (BenzoDODA) has been synthesized and evaluated for its extraction behaviour towards plutonium and other elements present in the spent nuclear fuel. High separation factors for plutonium over other elements were observed, indicating the high selectivity of the extractant for plutonium. The extractant is quite promising for the selective separation of plutonium from dissolver solution and various acidic waste streams.     

Structural insights of dipeptidyl peptidase-IV inhibitors through molecular dynamics-guided receptor-dependent 4D-QSAR studies

Dipeptidyl peptidase-IV (DPP-IV) inhibitors are promising antidiabetic agents. Currently, several DPP-IV inhibitors have been approved for therapeutic use in diabetes mellitus. Receptor-dependent 4D-QSAR is comparatively a new approach which uses molecular dynamics simulations to generate conformational ensemble profiles of compounds representing a dynamic state of compounds at a target’s binding site. This work describes a receptor-dependent 4D-QSAR study on triazolopiperazine derivatives. QSARINS multiple linear regression method was adopted to generate 4D-QSAR models. A model with 9 variables was found to have better predictive accuracy with \({R}^{2}=0.692\), \({Q}^{2}\) (leave-one-out) = 0.592 and \({R}^{2}\) predicted = 0.597. The location of these 9 variables at the binding site of DPP-IV revealed the importance of the residues Val711, Tyr662, Tyr666, Val202, Asp200 and Thr199 in making critical interactions with DPP-IV inhibitors. The study of these critical interactions revealed the structural features required in DPP-IV inhibitors. Thus, in this study the importance of a halogen substituent on a phenyl ring, the extent of substitution on the triazolopiperazine ring, the presence of an ionizable amino group and the presence of a hydrophobic substituent that can bind deeper in binding pocket of DPP-IV were revealed.     

Differential pulse voltammetric determination of uranium in low concentration streams

A differential pulse voltammetric method has been successfully used for the determination of uranium in low concentration streams of a uranium plant. The method gives a precision of about 13% to 7% in the range of 300 ppb to 15 ppm. The accuracy of the results was ascertained by comparing the values with those obtained by a spectrophotometric method. The method is simple, fast, sensitive, fairly accurate and does not require a preconcentration step.     

Determination of hexamethylene tetramine in the process solution of sol-gel method for nuclear fuel fabrication

Hexamethylene tetramine (HMTA) was determined in the presence of large quantities of urea, formaldehyde and ammonium hydroxide by potentiometric titration with perchloric acid solution using an autotitrator coupled to a personal computer. This analysis is required for the process control of the sol-gel method in the production of ceramic metal oxide (e.g., oxides and mixed oxides of Th, U and Pu) microspheres using the internal gelation route. Feed solution used for preparation of microspheres contains large quantities of urea. The washings of gel microspheres produced after the internal geletion process contain urea, formaldehyde, urea-formaldehyde complex and ammonium hydroxide. The presence of these constituents in the feed solution and washings seriously interfere in the commonly used methods for the determination of HMTA. Using this method the relative standard deviation was found to be 0.27% in eleven determinations of a typical feed solution (3.0M HMTA) when the aliquots contained 75 to 125 mg of HMTA. Time required for each titration was 5–7 minutes. Feed and effluent solutions of sol-gel process were analysed.     

Solid-phase synthesis of 2-aminoquinazolinone derivatives with two- and three-point diversity

A versatile solid-phase method for the synthesis of various substituted 2-amino-4(3H)-quinazolinones with two- and three-point diversity is described. The synthesis commenced with the generation of polymer-bound S-methylisothiourea followed by N-acylation with different substituted o-nitrobenzoic acid. Finally, reduction of the nitro group triggered intramolecular cyclization via formation of guanidine to afford 2-amino-4(3H)-quinazolinone and its derivatives in high yields and purities.     

Creating new supramolecular materials by architecture of three-dimensional nanocrystal fiber networks

The architecture of three-dimensional interconnecting self-organized nanofiber networks from separate needlelike crystals of L-DHL (lanosta-8,24-dien-3beta-ol:24,25-dihydrolanosterol = 56:44) in di-isooctylphthalate has been achieved for the first time, on the basis of the completely new concept of branching creation by additives (branching promoters). [In this work, an additive, ethylene/vinyl acetate copolymer (EVACP), is used at a concentration of several 10 ppm.] We demonstrate that this novel technique enables us to produce previously unknown self-supporting supramolecular functional materials with tailormade micro- or nanostructures, possessing significantly modified macroscopic properties, by utilizing materials thus far considered to be "useless". In addition, both the self-organized structure and the properties of the new materials can be fine-tuned by altering the processing conditions. Our results show that the formation of the interconnecting 3D self-organized network structure is controlled by a new mechanism, so-called crystallographic mismatch branching mechanism, as opposed to the conventionally adopted molecular self-assembly mechanism. The principles and criteria for the selection of branching promoters are also discussed from the point of view of molecular structures.     

Removal of Phenol from Wastewater Using Date Seed Carbon

The adsorption of phenol on Date Seed Carbon (DSC) was investigated to assess its possible use as an adsorbent for the processing of phenolic wastewater. The influence of various factors such as initial concentration, agitation speed, amount of adsorbent and temperature on the adsorption capacity has been studied. The percentage removal of phenol was observed to increase with increase an initial concentration of phenol. The adsorption of phenol decrease with an increase in temperature indicated the exothermic nature of the reaction. The Langmuir and Freundlich equations interpret adsorption isothermal data. Kinetic data was obtained by using a pseudo‐second‐order equation to understand the reaction mechanism. Thermodynamic parameters such as ΔG, ΔH and ΔS for the adsorption process were calculated.     

A study on the hydrolytic behavior of thorium (IV) and dioxo-uranium(VI) in the absence and presence of fluoride ions

The hydrolytic behavior of thorium(IV) and dioxo-uranium(VI) was studied in the absence as well as in the presence of small concentration of fluoride in the pH range of 2.0 to 4.0 and 2.0 to 5.5, respectively. Effects of metal ion concentration and time dependence of the hydrolytic process were also investigated. The log values of ₁₁ ^* and ₁₃ ^* computed from the best model of species distribution were found to be -3.51±0.03, and -10.75±0.14 for thorium(IV). Similarly, the best model for dioxo-uranium consisted of ₂₂ ^*, ₄₆ ^* and ₄₇ ^* species having values -6.15±0.05-18.43±0.09 and -23.36±0.07, respectively. Recently developed HYPERQUAD computer program was used for analyzing the various aspects of solution equilibrium species. Different models of chemically possible species distribution were invoked to identify the best model for which HYPERQUAD yields the best fitting of experimental data with least errors. The best model was also decided on the basis of chemical feasibility of the reaction. The species distribution of hydrolytic product remained unaffected in the presence of small quantity of fluoride ions (~1% of thorium and uranium concentration). Moreover, fluoride was found to be helpful in suppressing the early polymerization and colloid formation at the metal ion concentrations investigated. The small amounts of fluoride did not seem to affect the response of glass electrode significantly. The formations of fluoride containing ternary complexes were also not observed at 1% fluoride concentration.