Selective enrichment of U(VI), Th(IV) and La(III) from high acidic streams using a new chelating ion-exchange polymeric matrix

An off-line extraction chromatographic technique has been developed using Amberlite XAD-16 (AXAD-16)-N,N-dihexylcarbamoylmethyl phosphonic acid, as the stationary phase for the extraction of uranium, thorium and lanthanum from nuclear spent fuels as well as from geological and natural water resources. The chemical modifications of the polymeric matrix were monitored using FT-IR spectroscopy, CHNPS elemental analysis and also by thermo gravimetric analysis for water regain measurements. Various physio-chemical parameters influencing the quantitative metal ion extraction by the resin phase were optimized by both static and dynamic methods. The developed resin matrix showed good distribution ratio values under wide concentrations of acidity and pH conditions. Moreover, the sequential separation of analytes is also possible at sample pH 6.5. Also, the polymeric matrix showed superior metal sorption capacities and rapid metal exchange kinetics with a high sample flow rate value of 26 cm³ min⁻¹ for all the three analytes. Thus, reducing the time of analyte extraction from large number of samples anticipated in nuclear waste management programs. The quantitative metal ion recovery of >99.8% was effected with 0.5 M (NH₄)₂CO₃ solution. The method was highly sensitive with lower limits of detections to be 10, 20 and 15 ng cm⁻³ for U(VI), Th(IV) and La(III), respectively, with a better pre-concentration values of 333 for U(VI) and Th(IV) and 400 for La(III), respectively paving way for its applicability in pre-concentrating trace analytes from large sample volumes. The analytical data were within 4.2% R.S.D. reflecting the reproducibility and reliability of the developed method.     

Expanding Horizons of Metal Oxide-based Chemical and Electrochemical Sensors

Metal-oxide (MOx) are widely used in electrical/electrochemical sensors owing to their quick-response ability, High surface-to-volume ratio, matching lateral-dimensions with surface-charge zone and modifiable with dopants significantly enhances their sensing performance. Typically, MOx-based sensors are used in gaseous-analytes for monitoring environmental-pollutants and gas-leakage. Tuning the properties of nanostructured-metal-oxides advanced their applications beyond environmental-monitoring. This review focuses on the emerging-dimensions of MOx-based sensors in hazard-surveillance and risk-investigation like in deployment to detect fire-hazards, chemical-warfare agents, oil-spills and explosives. Recent advances of using MOx-based sensors as electronic-tongue and electronic-nose for non-invasive health monitoring and MOx-based sensor mobile robots for remote surveillance is also discussed.     

Effect of iron scrap additives in stearic acid as PCM for thermal energy storage system

Journal of Thermal Analysis and Calorimetry - The thermal energy storage (TES) system is used to store the heat energy for longer periods and retrieve the heat energy as and when required....     

A facile regio- and stereoselective synthesis of novel dispirooxindolyl-[acridine-2′,3-pyrrolidine/thiapyrrolizidine]-1′-ones via 1,3-dipolar cycloaddition of azomethine ylides

A facile regio- and stereoselective synthesis of novel dispirooxindolyl-[acridine-2′,3-pyrrolidine]-1′-ones and dispirooxindolyl-[acridine-2′,3-thiapyrrolizidine]-1′-ones have been accomplished via 1,3-dipolar cycloaddition of azomethine ylides, generated in situ from the reaction of sarcosine/1,3-thiazolane-4-carboxylic acid and substituted isatins, to a series of (E)-2-[arylmethylidene]-3,4-dihydro-1(2H)-acridinones in good yields.     

One-Pot Sequential Synthesis of β-Hydroxy-1,4-disubstituted-1,2,3-triazoles from in-situ Generated β-Azido Alcohol by Click Chemistry

β-Hydroxy 1,2,3-triazoles from in situ generated 1,2-azidols were synthesized employing two sequential click reactions in very high yields with high regioselectivity using Cu(OAc)₂·H₂O as a catalyst in water at ambient temperature     

Mechanical Properties and Chemical Resistance of Short Tamarind Fiber/Unsaturated Polyester Composites: Influence of Fiber Modification and Fiber Content

In the present work, tamarind fibers were extracted from ripened fruits by the water retting process. Using these fibers as reinforcement and unsaturated polyester as matrix, composite samples were prepared by the hand lay-up technique. The effect of chemical surface treatments (alkali and silane) of tamarind fibers on the mechanical properties, chemical resistance, and interfacial bonding was studied. The mechanical properties of the composites with surface modified fibers were found to be higher than those with unmodified fibers. Morphological studies indicated improvement of interfacial bonding by alkali and silane coupling agent treatments of the fibers. The composites were found to be resistant to many chemicals.     

Analytical solution of non-linear enzyme reaction equations arising in mathematical chemistry

The boundary value problem in basic enzyme reactions is formulated and approximate expressions for substrate and substrate-enzyme complex are presented. He’s Homotopy Perturbation method is used to give approximate and analytical solutions of non-linear reaction equations containing a non-linear term related to enzymatic reaction. The pertinent analytical solutions for the substrate, enzyme- substrate complex and free enzyme are discussed in terms of dimensionless parameters σ, ρ and e{\varepsilon} . The obtained concentration results are compared with the numerical solution acquired using Matlab program. They are found to be in satisfactory agreement.     

Purely imaginary roots of kac-moody algebras

In this paper, we introduce a new class of imaginary roots, called purely imaginary roots and give a necessary and sufficient condition for an imaginary root to be purely imaginary,thereby giving a complete classification of those Kac-Moody algebras with the purely imaginary property, namely, all their imaginary roots are purely imaginary. We also define a new class of non-hyperbolic indefinite Kac-Moody algebras, called the extended hyperbolic kac-Moody algebras possessing the purely imaginary property.     

Studies on the uptake behavior of nickel from flowing sodium for Mn,Co and Zn

Journal of Radioanalytical and Nuclear Chemistry - In this study, the natural luffa fiber was easily modified by chemical method with amide groups and phosphoric acid (LF-A2-M1/P). SEM, XRD, FTIR...