Determination of arsenic species in Solanum Lyratum Thunb using capillary electrophoresis with inductively coupled plasma mass spectrometry

A simple and highly efficient interface to couple capillary electrophoresis with inductively coupled plasma mass spectrometry by a microflow polyfluoroalkoxy nebulizer and a quadruple ion deflector was developed in this study. By using this interface, six arsenic species, including arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, and arsenocholine, were baseline‐separated and determined in a single run within 11 min under the optimized separation conditions. The instrumental detection limit was in the range of 0.02–0.06 ng/mL for the six arsenic compounds. Repeatability expressed as the relative standard deviation (n = 5) of both migration time and peak area were better than 2.5 and 4.3% for six arsenic compounds. The proposed method, combined with a closed‐vessel microwave‐assisted extraction procedure, was successfully applied for the determination of arsenic species in the Solanum Lyratum Thunb samples from Anhui province in China with the relative standard deviations (n = 5) ≤4%, method detection limits of 0.2–0.6 ng As/g and a recovery of 98–104%. The experimental results showed that arsenobetaine was the main speciation of arsenic in the Solanum Lyratum Thunb samples from different provinces in China, with a concentration of 0.42–1.30 μg/g.     

Kinetics and mechanisms of oxidation by metalions. Part XI(1). Kinetics of the osmium(VIII)-catalysed oxidation of glycols by alkaline hexacyanoferrate(III)

Summary The kinetics of the Os^VIII-catalysed oxidation of glycols by alkaline hexacyanoferrate(III) ion exhibits zerothorder dependence in [Fe(CN) ₆ ^3– ] and first-order dependence in [OsO₄]. The order with respect to glycols is less than unity, whereas the rate dependence on [OH^–] is a combination of two rate constants; one independent of and the other first-order in [OH^–]. These observations are commensurate with a mechanism in which two complexes, [OsO₄(H₂O)G]^– and [OsO₄(OH)G]^2–, are formed either from [OsO₄(H₂O)(OH)]^– or [OsO₄(OH)₂]^2– and the glycol GH, or by [OsO₄(H₂O)₂] and [OsO₄(H₂O)(OH)]^– and the glycolate ion, G^–, which is in equilibrium with the glycol GH through the reaction between GH and OH^–. Hence there is an ambiguity about the true path for the formation of the two Os^VIII-glycol complexes. A reversal in the reactivity order of glycols in the two rate-determining steps, despite the common attack of OH^– ion on the two species of Os^VIII-complexes, indicates that the two complexes are structurally different because S changes from the negative (corresponding to k₁₁) to positive (related to k₂).     

Linear diacetylene polymers containing bis(dimethylsilyl) phenyl and/or bis-(tetramethyldisiloxane) carborane residues: Their synthesis,characterization and thermal and oxidative properties

A series of inorganic-organic linear diacetylenic hybrid polymers ( 5a–e ) were prepared by the polycondensation reaction of 1,4-dilithiobutadiyne with 1,4-bis(dimethylchlorosilyl)benzene and/or 1,7-bis(tetramethylchlorodisiloxane)-m-carborane. Their structures were characterized using FTIR, and ¹³C and ¹H NMR spectroscopies, and their thermal and oxidative properties were evaluated by DSC and TGA analyses. The hybrid polymers exhibited solubility in common organic solvents and were viscous liquids or low melting solids at room temperature. Broad prominent exotherms, attributed to reaction of the diacetylenic units, were observed by DSC in the 306°C to 354°C temperature range. When 5a–e were analyzed by TGA to 1000°C under nitrogen, weight retention between 79 and 86% were obtained. Ageing studies, performed at elevated temperatures in air on a thermoset and a ceramic obtained from polymer 5b , showed this system to have excellent thermal and oxidative stability. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2387–2391, 1997     

Voltammetric determination of the anti-cancer drug nilutamide using a screen-printed carbon electrode modified with a composite prepared from β-cyclodextrin,gold nanoparticles and graphene oxide

The authors describe an electrochemical method for the determination of the anti-cancer drug nilutamide. The method is based on the use of a composite prepared from β-cyclodextrin, gold nanoparticles and graphene oxide (β-CD-AuNP/GO). An alkaline solution of glucose was used as a reducing agent to reduce the gold ions, rather than citric acid and a harmful reducing agent such as hydrazine and sodium borohydride. The structure and surface morphology of the β-CD-AuNP/GO composite was characterized by Raman spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. A screen printed carbon electrode was modified with the nanocomposite, and the resulting electrode used as a disposable sensor for the determination of nilutamide by differential pulse voltammetry. Best operated at a working voltage of 0.43 V (vs Ag/AgCl), it exhibits excellent electrocatalytic activity and a detection limit as low as 0.4 nM. The sensor was applied to the determination of nilutamide in (spiked) human serum, as well as in a tablet, where it displays good recovery and accuracy. The sensor is repeatable, reproducible, stable and selective even in the presence of other aromatic nitro compounds.

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Graphical abstract An electrochemical method for the determination of the anti-cancer drug nilutamide is described. A screen printed carbon electrode is modified with the nanocomposite prepared from β-cyclodextrin, gold nanoparticles and graphene oxide (β-CD-AuNP/GO). Best operated at a working voltage of 0.43 V (vs Ag/AgCl), it exhibits excellent electrocatalytic activity and a detection limit as low as 0.4 nM. The sensor was applied to the determination of nilutamide in (spiked) human serum and a tablet where it displays good recovery and accuracy.

     

Base-catalyzed cross coupling of secondary alcohols and aryl-aldehydes with concomitant oxidation of alcohols to ketones: An alternative route for synthesis of the Claisen-Schmidt condensation products

Base-catalyzed C–C cross coupling of secondary alcohols and aryl-aldehydes was achieved, when an alcoholic solution of an aryl-aldehyde was stirred under reflux for 45 h in the presence of a catalytic (20 mol%) amount of K₂CO₃. The consistent formation of α,α′-bis-(benzylidene) alkanones was obtained in moderate to good yields using various secondary alcohols and substituted aryl-aldehydes. Herein, α,α′-bis-(benzylidene)alkanones, which are the classical products of Claisen-Schmidt (cross aldol) condensation, have been synthesized via an alternative strategy using secondary alcohols. Bis-(benzylidene) alkanones are an integral part of various drug regimes and the production of bis-(benzylidene) alkanones without using any precious metal is a major outcome of the present reaction.     

One pot synthesis of important retinoid synthon by the catalytic regioselective bi-functionalization of acetylenes,alcohol and carbon monoxide

Base free Fe(CO)₅ catalyzed one-pot synthesis of E/Z alkyl 3-formyl-3-alkyl/aryl/ferrocenyl-2-propenoates (retinoid esters) was achieved by the photolysis of alcoholic solution of terminal acetylenes and carbon monoxide. 8–10 Mol% of ironpentacarbonyl was used as a catalyst for significant transformations of retinoid esters. During the photolysis, alkynes reduced by the simultaneous double functionalization esterification and formylation and resulted in regioselective E/Z isomers of alkyl 3-formyl-3-alkyl/aryl/ferrocenyl-2-propenoates. The bi-functionalization of acetylene is quite unusual and is not observed frequently. The highest yield of the retinoid esters was achieved with 3° alcohols (96%, for E and Z isomers) while the least yield was observed with 1° alcohols (25%, for E and Z isomers). All retinoid esters are regiospecific and have exceptional biological significance to serve as key structural motifs in drug and pharmaceutical applications.     

Recent advancement in inorganic-organic electron transport layers in perovskite solar cell: current status and future outlook

Organic-inorganic lead halide perovskite solar cells have captured significant attention in recent years due to low processing costs and unprecedented development in power conversion efficiency (PCE). It has appeared from 2009 with PCE of 3.8% to being claimed more than 25.2% PCE in a very short span of time, showing their future prospective toward the fabrication of less expensive and stable solar cells. The incredible advancement in this technology encourages at one end, whereas several hurdles restricting its complete utilization for commercial purposes at another end. Although the selection of perovskite structure is limited with planar and mesoporous electron transport layers (ETLs), but identification of appropriate ETLs necessitates excellent effort to improve the surface morphology of absorber and obtain enhanced PCE with higher stability. In the present review, we have investigated various inorganic-organic ETLs with different device configurations of PSCs, primarily focusing on crystallization and morphology control techniques of ETL thin films. Numerous strategies such as surface functionalization, doping, and addition of interfacial layer are adopted for ETLs, and their effect on device efficiency, performance, and hysteresis is also discussed in detail. Additionally, designs of PSCs with different device configurations are discussed as well, providing future guidelines for significant progress in PSCs structure with different ETLs.     

The aftermath of the interplay between the endoplasmic reticulum stress response and redox signaling

The endoplasmic reticulum (ER) is an essential organelle of eukaryotic cells. Its main functions include protein synthesis, proper protein folding, protein modification, and the transportation of synthesized proteins. Any perturbations in ER function, such as increased demand for protein folding or the accumulation of unfolded or misfolded proteins in the ER lumen, lead to a stress response called the unfolded protein response (UPR). The primary aim of the UPR is to restore cellular homeostasis; however, it triggers apoptotic signaling during prolonged stress. The core mechanisms of the ER stress response, the failure to respond to cellular stress, and the final fate of the cell are not yet clear. Here, we discuss cellular fate during ER stress, cross talk between the ER and mitochondria and its significance, and conditions that can trigger ER stress response failure. We also describe how the redox environment affects the ER stress response, and vice versa, and the aftermath of the ER stress response, integrating a discussion on redox imbalance-induced ER stress response failure progressing to cell death and dynamic pathophysiological changes.Subject terms: Mechanisms of disease, Cell biology