Advances in theoretical and experimental XAFS studies of thermodynamic properties,anharmonic effects and structural determination of fcc crystals

Thermodynamic properties, anharmonic effects and structural determination of fcc crystals have been studied based on the theoretical and experimental Debye–Waller factors presented in terms of cumulant expansion up to the third order, thermal expansion coefficient, X-ray absorption fine structure (XAFS) spectra and their Fourier transform magnitudes. The advances in these studies are performed by the further development of the anharmonic correlated Einstein model primary only for approximating three first XAFS cumulants into the method using that all the considered theoretical and experimental XAFS parameters have been provided based on only the calculated and measured second cumulants. The obtained cumulants describe the anharmonic effects in XAFS contributing to the accurate structural determination. Numerical results for Cu are found to be in good agreement with the experimental values extracted by using the present advanced method and with those obtained by the other measurements.     

Premières applications du thiocarbohydrazide en chimie minérale

Résumé Les auteurs proposent l'emploi du thiocarbohydrazide en chimie minérale. Ils donnent une première liste d'ions réagissants. Ce réactif apparaît déjà intéressant pour le dosage gravimétrique ou colorimétrique du molybdène en présence de tungstène et d'uranium.

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Summary The authors propose the use of thiocarbohydrazide in inorganic chemistry. They give a preliminary list of reacting ions. This reagent appears to have some interest for the gravimetric or colorimetric determination of molybdenum in the presence of tungsten and uranium.

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Zusammenfassung Die Anwendung von Thiocarbohydrazid in der anorganischen Chemie wird vorgeschlagen und eine Liste der mit dieser Verbindung reagierenden Ionen angeführt. Für die gravimetrische oder kolorimetrische Bestimmung von Molybdän in Gegenwart von Wolfram und Uran scheint das Reagens von Interesse zu sein.

     

Two-dimensional model of molecule—surface scattering

Rotational excitation in molecule—surface scattering is analyzed in a simple quantum two-dimensional model. The true molecule—surface potential is replaced by a hard-core ellipsoid. The model accurately describes the dominant features of the transition probability distribution. This is demonstrated by comparing rotational transition probabilities calculated from our model with the results of IOS calculations of Voges and Schinke using realistic potential. The model predicts a new scaling property concerning the anisotropy parameter of the potential surface.     

Plasma quantification of quazepam and its 2-oxo and N-desmethyl metabolites by capillary gas chromatography

The authors have developed a gas chromatographic method for the simultaneous quantification of quazepam in plasma and its two main metabolites, 2-oxoquazepam and N-desmethylquazepam. This method involves an extraction from plasma using butyl acetate, and an analysis by electron-capture detection on a CP-Sil 5 WSCOT capillary column. Intra- and inter-day precision and accuracy were better than 10% for each of these three compounds, even near their detection limit estimated at 0.2 ng/ml. Linearity proved satisfactory between 0.2 and 60-70 ng/ml. For endogenous plasma components, adequate specificity was achieved. Despite some inconveniences, a long analysis time, a progressive saturation of the column owing to a low oven temperature, and a relatively short life-span of the CP-Sil 5 columns, this method was the only one available in the literature for the quantification of quazepam and its metabolites from the same plasma sample. It was successfully applied to phase I studies in healthy volunteers.     

3-Dimethylarsino-propylamin, (CH3)2As?(CH2)3?NH2, und Bis-[3-amino-propyl]-methylarsan,CH3As[(CH2)3?NH2]2

3-Dimethylarsino-propylamine, (CH₃)₂As? (CH₂)₃? NH₂, and Bis-[3-aminopropyl]-methylarsane, CH₃As[(CH₂)₃? NH₂]₂ The reduction of the nitriles Me₂As(CH₂)₂? CN (Me?CH₃) and MeAs(CH₂CH₂? CN)₂ results in the formation of the arsines Me₂As(CH₂)₃? NH₂ and MeAs[(CH₂)₃? NH₂]₂, respectively. The reactivity of these compounds, especially the formation of carbonyl complexes and heterocyclic compounds are described.     

The use of bathoferroine for extraction-spectrophotometric determinations of microamounts of perchlorate and perrhenate

Bathoferroine can be used for anion determinations by a method based on selective ion-pair extraction if the selectivity of extraction has been enhanced by addition of nonelectrolyte to the water phase. The method of perchlorate and perrhenate determinations characterizes parameters similar to those obtained by methods in which other cation complexes have been used. The advantage of the proposed method is the possibility of considerable concentration of ion association compound extracts by nitromethane reextraction.     

Structural variations among the aporphine-benzylisoquinoline dimers

$\text{Thalictrum}$$\text{minus}$ L. var. $\text{microphyllum}$ Boiss. (Ranunculaceae) has yielded (+)-istanbulamine ($\text{5}$) which is the first aporphine-benzylisoquinoline formed from one (+)-reticuline-type unit linked to a (+)-N-methylcoclaurine moiety. Other new dimers also present are (+)-bursanine ($\text{6}$) and (+)-iznikine ($\text{7}$).     

Thermodynamics of the Interaction Between Graphene Quantum Dots with Human Serum Albumin and γ-Globulins

As one of the newly emerged nanomaterials, graphene quantum dots (GQDs) have shown great application potential as tracking probes and drug carriers in biological areas. The GQDs synthesized via the nitric acid reflux method in this study turned out to quench the fluorescence of human serum albumin (HSA) and gamma globulin (γ-globulin) in two different functional ways. The fluorescence quenching effect of GQDs on HSA is a static pattern and the predominant interaction forces are hydrogen bonds and van der Waals forces. Distinct from HSA, the interaction between GQDs and γ-globulins belongs to dynamic quenching and is driven by electrostatic forces. Ultraviolet–visible (UV–vis) differential spectrometry and transient state fluorescence spectrometry were also utilized to further confirm their quenching types. Also, thermodynamics parameters, the enthalpy change (ΔH) and entropy change (ΔS) of reaction between GQDs and proteins were obtained through a series of calculations from the van’t Hoff equation. Furthermore, the effect of GQDs on the conformational structure of proteins was characterized by synchronous fluorescence spectra (SFS), three-dimensional (3D) fluorescence and circular dichroism (CD) spectra. In addition, the binding mechanism of GQDs with HSA and γ-globulins were proposed based on the obtained experimental results. The research on the reaction between GQDs with HSA and γ-globulins offers promising insight for the further application of nanomaterials in biomedical fields.     

Application of a renewable silver based mercury film electrode to the determination of Cr(VI) in soil samples

The design and experimental results of the application of a renewable mercury film silver based electrode to the determination of Cr(VI) in soil samples are presented. The main feature of this procedure is that it can be used in field measurements. The procedure is based on the extraction of total Cr(VI) exploiting the complexation property of diethylenetriaminepentaacetic acid (DTPA) followed by electrochemical reduction of Cr(VI) to Cr(III) with the formation of Cr(III)-H₂DTPA complex adsorbed on mercury film electrode. The voltammetric signal is caused by reduction of this complex. The validation of the proposed procedure was made by Cr(VI) determination in the certified reference material “Chromium VI in soil”. The protocol for Cr(VI) determination has also been applied to the analysis of Rendoll soil samples with satisfying precision.