Electrochemical reduction of some rhodanine derivatives at the DME

The electroreduction of two series of rhodanine derivatives has been investigated at the DME. The first wave was assigned to the saturation of the azomethine linkage and the reduction of the ethylenic double bond in series I and II, respectively. On the other hand, the second wave in both series was assigned to the reduction of the C-S group and partly to the catalytic hydrogen evolution catalyzed by these compounds.     

Simultaneous Analysis of Fluoxetine, Norfluoxetine, Citalopram, and Haloperidol in Plasma by LC–ESI-IT-MS

A reliable and simple method has been developed for simultaneous analysis of fluoxetine, its metabolite norfluoxetine, citalopram, and haloperidol with lamotrigine as internal standard. The method is based on solid-phase extraction on mixed-mode cation-exchange cartridges followed by LC separation on a C₁₈ column at ambient temperature with a gradient prepared from acetonitrile and 5 mM ammonium acetate in 0.1% (v/v) aqueous formic acid. The flow rate was 0.5 mL min^?1. Eluted compounds were ionized by the electrospray ionization ion source of an ion-trap mass spectrometer and were detected by selected ion monitoring. Co-extracted endogenous compounds from plasma were eluted in the first 5 min and discarded by valve-switching. The target drugs were eluted in the period 5.5–11 min. Calibration plots were linear in the ranges 5 (or 10)–400 ng mL^?1 with correlation coefficients >0.999. Other statistical and validation results were within accepted ranges for clinical analysis.     

Simulation of the condenser of the seawater greenhouse

A theoretical model is developed in Part I of this study to simulate the physical process of condensation of the humid air in the condenser of an existing seawater greenhouse that is located in Muscat, Oman. Application is conducted in this part to validate the theoretical developments. Comparisons are made between the predictions and the existing experimental results. The results indicate that the comparison is well consistent. The effect of the relative humidity, the dry bulb temperature and the solar radiation are also discussed to see their effects on the condensate values.     

Potential anti-inflammatory diterpenes from Premna obtusifolia

Eleven new diterpenoids: pimaranes (1,2), rosanes (3) abietanes (4–7), icetexanes (8), and rearranged icetexanes (9–11), together with fifteen known diterpenes (12–26) and two known sesquiterpenes (27,28) have been isolated from the roots and twigs of Premna obtusifolia. The structures of these compounds were elucidated on the basis of spectroscopic analysis and X-ray crystallographic data of 8 and 9 were also determined. The antibacterial and anti-inflammatory activities of the isolates were evaluated.     

Simulation of the condenser of the seawater greenhouse

The BaF₂-YF₃ system was partially investigated, with focus given to the BaY₂F₈ compound and its neighboring phases. In this report, various difficulties that hinder the thermal analysis investigation of this binary fluoride system are described in detail. Samples of various compositions ranging from 58 to 79% YF₃ were prepared and subjected to thermal analysis (DTA, TG and DSC) and X-ray diffraction. Diffraction patterns were analyzed through the Rietveld method for the calculation of phase concentrations in samples and determination of the lattice parameters of monoclinic BaY₂F₈. Thermal results were compared with data from the literature and discrepancies were found.     

Modelling the clogging of gas turbine filter houses in heavy-duty power generation systems

ABSTRACT

A prognostic approach based on a MISO (multiple inputs and single output) fuzzy logic model was introduced to estimate the pressure difference across a gas turbine (GT) filter house in a heavy-duty power generation system. For modelling and simulation of clogging of the GT filter house, nine real-time process variables (ambient temperature, humidity, ambient pressure, GT produced load, inlet guide vane position, airflow rate, wind speed, wind direction and PM10 dust concentration) were fuzzified using a graphical user interface within the framework of an artificial intelligence-based methodology. The results revealed that the proposed fuzzy logic model produced very small deviations and showed a superior predictive performance than the conventional multiple regression methodology, with a very high determination coefficient of 0.974. A complicated dynamic process, such as clogging phenomenonin heavy-duty GT system, was successfully modelled due to high capability of the fuzzy logic-based prognostic approach in capturing the nonlinear interactions.     

The effects of solute-solvent interactions on the electronic visible spectra of bis(β-diketonato)oxovanadium(IV) complexes

Summary The solvatochromic behaviour of bis(-diketonato)oxovanadium(IV) complexes is quantitatively correlated by an approach that models specific and non-specific solute-solvent interactions. The applicability of the Selbin-Gutmann relation is discussed. The solvent-induced spectral shifts in VO(acac)₂ are dominated by specific interactions of the donor-acceptor type, whereas for VO(tfa)₂, the nonspecific solute-solvent interactions make the dominant contribution.

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Der Einfluß von Wechselwirkungen zwischen Lösungsmittel und gelöstem Stoff auf die VIS-Spektren von Bis(-diketonato)oxovanadium(IV)-Komplexen

Zusammenfassung Das solvatochrome Verhalten von Bis(-diketonato)oxovanadium(IV)-Komplexen wird mit einem Modell, das spezifische und nichtspezifische Wechselwirkungen in Lösung berücksichtigt, quantitativ beschrieben. Es wird die Anwendbarkeit der Selbin-Gutmann-Relation diskutiert. Die Solvens-induzierten Verschiebungen in den VIS-Spektren von VO(acac)₂ werden von den spezifischen Wechselwirkungen vom Donor-Acceptor-Typ bestimmt, währenddessen für VO(tfa)₂ die nichtspezifischen Wechselwirkungen zwischen Substrat und Lösungsmittel den dominierenden Beitrag liefern.

     

A Thermodynamic Study of Complexation of Iron Ions with Clarithromycin and Roxithromycin in Methanol Using a Conductometric Method

The formation constants K _ML of Clarithromycin (CLA) and Roxithromycin (ROX) with Fe(III) and Fe(II) ions in methanol have been determined at various temperatures using a conductometric technique. The interaction yields complexes with metal-to-ligand compositions of 1:1. The conductivity data were analyzed using a computer program based on 1:1 stoichiometry from which the stability constants and the limiting molar conductance were obtained. The stability of these complexes was found to increase with temperature. Compared with Fe(II), Fe(III) forms more stable complexes with ROX and CLA. The values of the thermodynamic parameters enthalpies (??H ^°), entropies (??S ^°), and the derived Gibbs energies (??G ^°) were deduced from the dependence of the formation constants on temperature. The positive values of ??H ^° and ??S ^° indicate that the complexation processes is enthalpically unfavorable but entropically favored. The negative values of ??G ^° show the ability of the studied ligand to form stable complexes and that the complexation process is favorable.