Simultaneous determination of trace amounts of borate, chloride and fluoride in nuclear fuels employing ion chromatography (IC) after their extraction by pyrohydrolysis

An accurate and sensitive method based on the combination of pyrohydrolysis-ion chromatography (PH-IC) is proposed for the simultaneous separation and determination of boron as borate, chloride and fluoride in nuclear fuels such as U(3)O(8), (Pu,U)C and Pu-alloys. The determination is based on the initial pyrohydrolytic extraction of B, Cl and F from the samples as boric acid, HCl and HF, respectively, which are subsequently separated by ion chromatography (IC). The proposed method significantly improves the existing analytical methodology as it combines the determination of boron, a critical trace constituent in nuclear materials, along with F(-) and Cl(-) for chemical quality control measurements. Various experimental parameters were optimized to achieve maximum recoveries of the analytes during the pyrohydrolysis and to get better ion chromatographic (IC) separation of borate, F(-) and Cl(-) along with other anions such as CH(3)COO(-), NO(2)(-), NO(3)(-), Br(-), PO(4)(3-) and SO(4)(2-). Recoveries of more than 93% could be obtained for all the analytes in the sample (0.5-1.5 g) at 1200+/-25K and distilled with pre-heated steam at the flow rate of 0.3 mL/min. An isocratic elution with a mobile phase of 0.56 M d-mannitol in 6.5mM NaHCO(3) was used for the IC separation. The detection limits for B (as borate), F(-) and Cl(-) were 24, 13 and 25 microgL(-1), respectively. Precision of about 5% was achieved for determination of boron, Cl(-) and F(-) in the samples containing 1-5 ppm(w) of boron, and 10-25 ppm(w) of Cl and F. The method was validated with reference materials and successfully applied to the nuclear fuels. The methodology is easy to adapt on routine basis.     

Separation of carrier-free 90Y from 90Sr using flat sheet supported liquid membranes containing multiple diglycolamide-functionalized calix[4]arenes

Abstract

Five diglycolamide-appended calix[4]arene (C4DGA) ligands, viz. C4DGA with no substituent (L-I), n-propyl (L-II), 3-pentyl (L-III), n-octyl (L-IV) and both side (L-V) substituents were evaluated for the separation of carrier free ⁹⁰Y from a ⁹⁰Y–⁹⁰Sr mixture using the flat sheet supported liquid membrane technique. Based on the results of earlier batch studies, the transport properties of the C4DGA ligands towards Y(III) and Sr(II) were monitored at two different feed acidities. The transport rates were significantly lower for 6 M HNO₃ as compared to 3 M HNO₃ as the feed. After 6 h, the observed trend of Y(III) transport with the C4DGA ligands using a feed of 3 M HNO₃ was: L-I ~ L-III > L-V > L-IV > L-II which changed to L-III > L-I > L-IV > L-V > L-II for 6 M HNO₃ as the feed. With 3 M HNO₃ as feed, >97% Y(III) transport was obtained with L-I and L-III in 6 h. Comparative Sr(II) transport was negligible resulting in high decontamination factors. In a one-step separation process, using L-I as the carrier ligand, pure ⁹⁰Y was obtained as the respective complex with either EDTA or DOTA. The highlights of this liquid membrane-based separation method comprise: its easiness, one-step separation, low ligand inventory, relatively pure product and continuous method.     

Experimental studies on droplet characteristics in a microfluidic flow focusing droplet generator: effect of continuous phase on droplet encapsulation

The European Physical Journal E - Interaction of cytoskeletal filaments, motor proteins, and crosslinking proteins drives important cellular processes such as cell division and cell movement....     

Microwave‐mediated synthesis and antibacterial activity of some novel 2‐(substituted biphenyl) benzimidazoles via Suzuki‐Miyaura cross coupling reaction and their N‐substituted derivatives

A series of some novel 2‐(substituted biphenyl) benzimidazoles and their N‐substituted derivatives were synthesized via microwave‐mediated Suzuki‐Miyaura coupling of 2‐(4‐iodophenyl)‐1H‐benzimidazole or 2‐(4‐iodophenyl)‐6‐amino‐1H‐benzimidazole and arylboronic acids. The method reported herein offers advantageous shorter reaction times, higher yields and is applicable to a large set of substrates. All the synthesized compounds were screened for their antibacterial activity against Staphylococcus aureus and Salmonella typhimurium bacterial species. J. Heterocyclic Chem., (2011).     

Engineered cells as biosensing systems in biomedical analysis

Over the past two decades there have been great advances in biotechnology, including use of nucleic acids, proteins, and whole cells to develop a variety of molecular analytical tools for diagnostic, screening, and pharmaceutical applications. Through manipulation of bacterial plasmids and genomes, bacterial whole-cell sensing systems have been engineered that can serve as novel methods for analyte detection and characterization, and as more efficient and cost-effective alternatives to traditional analytical techniques. Bacterial cell-based sensing systems are typically sensitive, specific and selective, rapid, easy to use, low-cost, and amenable to multiplexing, high-throughput, and miniaturization for incorporation into portable devices. This critical review is intended to provide an overview of available bacterial whole-cell sensing systems for assessment of a variety of clinically relevant analytes. Specifically, we examine whole-cell sensing systems for detection of bacterial quorum sensing molecules, organic and inorganic toxic compounds, and drugs, and for screening of antibacterial compounds for identification of their mechanisms of action. Methods used in the design and development of whole-cell sensing systems are also reviewed.     

Ionic liquid promoted expeditious synthesis of flavones

A smooth conversion of substituted 1-(2-hydroxy phenyl)-3-phenyl-1,3-propane diones to flavones has been done using n-butyl-3-methyl-imidazolium tetrafluoroborate ionic liquid.     

Axially Symmetric Bianchi Type-IX Inflationary Universe in General Relativity

Axially symmetric Bianchi type-IX space-time in the presence of mass less scalar field with a flat potential V is investigated. To get an inflationary universe, we have considered a flat region in which potential V is constant. Some physical and kinematical properties of the model are discussed.     

Uncapped silver nanoparticles synthesized by DC arc thermal plasma technique for conductor paste formulation

Uncapped silver nanoparticles were synthesized by DC arc thermal plasma technique. The synthesized nanoparticles were structurally cubic and showed wide particle size variation (between 20–150 nm). Thick film paste formulated from such uncapped silver nanoparticles was screen-printed on alumina substrates and the resultant ‘green’ films were fired at different firing temperatures. The films fired at 600 °C revealed better microstructure properties and also yielded the lowest value of sheet resistance in comparison to those corresponding to conventional peak firing temperature of 850 °C. Our findings directly support the role of silver nanoparticles in substantially depressing the operative peak firing temperature involved in traditional conductor thick films technology.     

A Palladium‐Catalyzed Carbonylation Approach to Eight‐Membered Lactam Derivatives with Antitumor Activity

The reactivity of 2‐(2‐alkynylphenoxy)anilines under PdI₂/KI‐catalyzed oxidative carbonylation conditions has been studied. Although a different reaction pathway could have been operating, N‐palladation followed by CO insertion was the favored pathway with all substrates tested, including those containing an internal or terminal triple bond. This led to the formation of a carbamoylpalladium species, the fate of which, as predicted by theoretical calculations, strongly depended on the nature of the substituent on the triple bond. In particular, 8‐endo‐dig cyclization preferentially occurred when the triple bond was terminal, leading to the formation of carbonylated ζ‐lactam derivatives, the structures of which have been confirmed by XRD analysis. These novel medium‐sized heterocyclic compounds showed antitumor activity against both estrogen receptor‐positive (MCF‐7) and triple negative (MDA‐MB‐231) breast cancer cell lines. In particular, ζ‐lactam 3 j′ may represent a novel and promising antitumor agent because biological tests clearly demonstrate that this compound significantly reduces cell viability and motility in both MCF‐7 and MDA‐MB‐231 breast cancer cell lines, without affecting normal breast epithelial cell viability.     

Simultaneous determination of metformin and glimepride in pharmaceutical dosage form by reverse-phase liquid chromatography

A simple, rapid, and precise reversed-phase liquid chromatographic method has been developed for the simultaneous determination of metformin in combination with glimepride. Under the developed conditions, good separation of the analytes was achieved in short analysis time. Several parameters affecting the separation of the analytes were studied, including pH and the concentration of SDS. The method is validated and shown to be linear in the range of 25 microg/mL to 150 microg/mL for metformin and 0.1 microg/mL to 0.6 microg/mL for glimepride. The method is applied for the analysis of these analytes in commercially available tablets.