Isolation of Bisphenol A-Tolerating/degrading Shewanella haliotis Strain MH137742 from an Estuarine Environment

Applied Biochemistry and Biotechnology - The human exposure to bisphenol A (BPA) occurs frequently. Once, this compound was one of the highest volume chemicals produced worldwide and used as a...     

Probing the Catalytic Activity of Reduced Graphene Oxide Decorated with Au Nanoparticles Triggered by Visible Light

Hybrid materials in which reduced graphene oxide (rGO) is decorated with Au nanoparticles (rGO–Au NPs) were obtained by the in situ reduction of GO and AuCl₄^?_(aq) by ascorbic acid. On laser excitation, rGO could be oxidized as a result of the surface plasmon resonance (SPR) excitation in the Au NPs, which generates activated O₂ through the transfer of SPR‐excited hot electrons to O₂ molecules adsorbed from air. The SPR‐mediated catalytic oxidation of p‐aminothiophenol (PATP) to p,p′‐dimercaptoazobenzene (DMAB) was then employed as a model reaction to probe the effect of rGO as a support for Au NPs on their SPR‐mediated catalytic activities. The increased conversion of PATP to DMAB relative to individual Au NPs indicated that charge‐transfer processes from rGO to Au took place and contributed to improved SPR‐mediated activity. Since the transfer of electrons from Au to adsorbed O₂ molecules is the crucial step for PATP oxidation, in addition to the SPR‐excited hot electrons of Au NPs, the transfer of electrons from rGO to Au contributed to increasing the electron density of Au above the Fermi level and thus the Au‐to‐O₂ charge‐transfer process.     

Hydrogenation homogene catalysee par les composes de coordination des platinoides : I. Proprietes catalytiques de derives organometalliques de l'iridium

The definition is stated for a catalytic test working at constant total pressure. The hydrogenation of 1-hexene has been studied with organoiridium compounds as catalysts. Of the derivatives [IrCl(cod)PR₃], the compound with PR₃ = tricyclohexylphosphine (PCy₃) has shown an activity and a selectivity superior to those of previously known catalysts.Two kinetic domains are found according to the temperature. Above ?10°C, the reaction is first order in hydrogen, one-third order in catalyst and zero order in 1-hexane. Below ?10°C it is first order in hydrogen, one-half order in catalyst and one-third order in 1-hexane.The optimum ratio PCy₃/Ir is 1 instead of 2, the value commonly found for other phosphine ligands.Other interesting catalysts containing acetato ligands are described.     

Adsorption of organic substances on broken clay surfaces: a quantum chemical study

Hydrogen-bonded interactions between local defect structures on broken clay surfaces modeled as molecular clusters and the organic molecules acetic acid, acetate, and N-methylacetamide (NMA) have been investigated. Density functional theory and polarized basis sets have been used for the computation of optimized interaction complexes and formation energies. The activity of the defect structures has been characterized as physical or chemical in terms of the strength of the hydrogen bonds formed. Chemical defects lead to significantly enhanced interactions with stronger hydrogen bonds and larger elongation of OH bonds in comparison to the physical defects. The type of interaction with the defect structure significantly influences the planarity of the model peptide bond in NMA. Both cases, enhancement of the planarity by increase of the CN double bond character and strong deviations from planarity, are observed.     

Improvement in steroid screening for doping control with special emphasis on stanozolol

The Medical Commission of the International Olympic Committee forbids the use of anabolic androgenic steroids and beta2-agonists to improve athletic performance. In this work we have selected examples of anabolic androgenic compounds and their metabolites to evaluate the GC-MS analysis of some trimethylsilyl derivatives. The aim is to set the best GC conditions to improve the detection within the whole range of analyte elution temperatures. The initial column temperature was changed to 105 or 140 degrees C followed by 40 degrees C min(-1) to 200 degrees C and then 15 degrees C min(-1) to 300 degrees C. Using 140 degrees C as the initial oven temperature it was possible to obtain narrower initial analyte distributions for the compounds that elutes at the beginning of the chromatogram as clenbuterol, mabuterol, epimethylenediol and norandrosterone, without loss of derivatized metabolites signal. Later. eluting analytes, such as the stanozolol metabolites, furazabol and oxandrolone were not affected. Temperatures below 140 degrees C. resulted in partial derivatization for some analytes mainly stanozolol related structures. Therefore evaluation of derivatization conditions as occurring in three steps, the vial, vaporization chamber and capillary column, was thoroughly assessed. The new program temperature improves the signal-to-noise ratio for some compounds and shows adequate resolution for endogenous compounds. Some of the difficult key separations necessary for doping control enforcement were also obtained with the proposed method.     

Infrared,raman and nmr study of (Ch2CH)3Snx compounds (X = Cl,Br, I)

The infrared, Raman and (¹H, ¹³C) NMR spectra of trivinyltin chloride, bromide and iodide have been analyzed and discussed. The vibrational assignment has been confirmed by an approximate normal coordinate analysis. Evidence has been found for a marked influence of the X substituent on the tin-carbon bond due to isovalent rehybridization. Variations in the π electron system of the vinyl group are hardly significant.     

Lewis acid-base adducts of zwitterionic alkali metal methanides and silanides with BH3

The synthesis, structures and spectroscopic properties of M(MeOCH₂CH₂OMe₂Si)₃CBH₃ (M-1-BH₃) and M(MeOCH₂CH₂OMe₂Si)₃SiBH₃ (M-2-BH₃) (M?=?Li, Na, K) derived from reactions of BH₃ with the alkali metal zwitterions [M(MeOCH₂CH₂OMe₂Si)₃C] (M-1) and [M(MeOCH₂CH₂OMe₂Si)₃Si] (M-2) (M?=?Li, Na, K), resp., are reported. X-ray analysis and DFT calculations reveal discrete zwitterionic structures with the octahedral alkali metal cations rigidly locked and charge separated from the BH₃ units via pendant donors groups. Solution experiments with the hydride acceptors B(C₆F₅)₃ and [Ph₃C]₂[B₁₂C₁₂] indicate that Na-1-BH₃ can donate hydrides to form cations of formula [Na(MeOCH₂CH₂OMe₂Si)₃CBH₂]⁺.     

Determination and assessments of selected heavy metals in eye shadow cosmetics from China,Italy, and USA

This study evaluated the content of heavy metals in samples of eye shadows. Samples were manufactured in different countries (China, Italy, and USA). The content of Pb was measured by flame-atomic absorption spectrometry (F-AAS). The quantification of cadmium, cobalt, chromium, and nickel was performed by inductively coupled plasma-mass spectrometry (ICP-MS). The analyses were preceded by microwave-assisted acid digestion of the eye shadows. In many samples the lead was present within 20 μg g^? 1, the value indicated as safe in good manufacturing practice, but it exceed this limit in four Chinese samples. The levels of cadmium, chromium and cobalt were always low and within acceptable and safe concentrations for the products made in Italy and USA, but the nickel concentrationexceeded the safe limit in many Chinese eye shadows. The overall results indicate that eye shadows are likely harmful when they are made according to current regulations, while products imported from China can be harmful. Therefore, major quality controls are recommended for products designed to enter in direct and long contact with the skin of eyelids when imported from countries with different regulations.