Numerical simulation of magnetohydrodynamic buoyancy-induced flow in a non-isothermally heated square enclosure

Numerical simulation of magnetohydrodynamic (MHD) buoyancy-induced heat transfer and fluid flow has been analyzed in a non-isothermally heated square enclosure using finite volume method. The bottom wall of enclosure were heated and cooled with a sinusoidal function and top wall was cooled isothermally. Vertical walls of the enclosure were adiabatic. Effects of Rayleigh number (Ra = 10⁴, 10⁵ and 10⁶), Hartman number (Ha = 0, 50 and 100) and amplitude of sinusoidal function (n = 0.25, 0.5 and 1) on temperature and flow fields were analyzed. It was observed that heat transfer was decreased with increasing Hartmann number and decreasing value of amplitude of sinusoidal function.     

The effects of a high-frequency suppressor on tuning curves and derived basilar-membrane response functions

Forward-masked psychophysical tuning curves were obtained using a fixed, low-level signal at a frequency of 4 kHz, and masker frequencies of 2.0, 2.5, 3.0, 3.5, 3.75, 4.0, 4.25, 4.5, 4.75, 5.0, and 5.5 kHz, at masker-signal gaps of 20, 30, 40, 60, 80, and 100 ms. An adaptive two-interval, two alternative forced-choice (21-2AFC) procedure was used to obtain the masker level at threshold. This procedure was repeated with the addition of a 4.75-kHz suppressor at 50 or 60 dB SPL, gated with the masker. Tuning curves were broader, and estimates of compression and gain from derived input/output functions were decreased in the presence of a suppressor as compared to the no-suppressor condition. The results are consistent with physiological results, which show that suppression leads to a broadening of tuning curves and a partial linearization of the midlevel portion of the basilar-membrane input/output function.     

First natural urease inhibitor from Euphorbia decipiens

Three new diterpene esters with a myrsinol-type skeleton have been isolated from Euphorbia decipiens BOISS. & BUHSE. The structure elucidation of the isolated compounds was based primarily on two-dimensional (2D)-NMR techniques including correlation spectroscopy (COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple bond correlation (HMBC) and nuclear Overhauser effect spectroscopy (NOESY) experiments. Compounds 1 and 3 are active against prolyl endopeptidase and compound 2 showed inhibitory activity against urease enzyme.     

Synthesis and properties of isoviagra. A 2‐methyl‐2H‐pyrazolo[4,3‐d]pyrirnidin‐7‐one isomer of viagra®

The synthesis and spectral properties (ir, ms, nmr) of a substituted 2‐methyl‐2H‐pyrazolo[4,3‐d]‐pyrimidin‐7‐one ( 3 ), an isomer of Viagra^®, are described. The key synthon, 4‐amino‐1‐methyl‐5‐propyl‐3‐pyrazolecarboxamide ( 7 ), is prepared via the reaction of ethyl 2,4‐dioxoheptanoate with methylhydrazine, followed by cyclization, nitration, amidation, and nitro group reduction. Interaction of 7 with 2‐ethoxyben‐zoyl chloride yielded the respective bis‐amide ( 8 ) which was cyclized in polyphosphoric acid to the corresponding pyrazolo[4,3‐d]pyrimidin‐7‐one derivative 9 . Chlorosulfonylation of 9 , and subsequent treatment with 1‐methylpiperazine furnished iso Viagra ( 3 ).     

Principal component analysis and cluster analysis for the characterisation of marbles by capillary electrophoresis

Chemical characterisation has been carried out on 25 quarry marbles collected from Marmara, Aegean and Thrace regions of Turkey. Ten elements were determined by capillary electrophoresis (CE). Principal component analysis and cluster analysis techniques were utilised to define grouping of different marble samples. These techniques showed that the analysed marbles were differentiable mainly by provenance. Experimental conditions such as pH, applied voltage and concentration of α-hydroxyisobutyric acid (HIBA) were optimised to achieve the best separation of metal ions using central composite design. The optimum pH 3.7, applied voltage 15 kV and concentration of HIBA 10 mM were found to provide the best separation for all metal ions investigated.     

MB-硬脂酸复合薄膜光波导传感器检测氯化氢气体

利用旋转甩涂法将亚甲基蓝(MB)掺杂的硬脂酸溶液涂成薄膜固定在钾离子(K⁺)交换玻璃光波导表面上, 研制了MB-硬脂酸复合薄膜/K⁺交换玻璃光波导传感器, 并对酸性气体进行了检测. 该复合薄膜与氯化氢(HCl)气体作用时, 薄膜颜色从深蓝色变为浅蓝色, 导致薄膜对倏逝波的吸收降低, 使传感器的输出光强度增强. 结果表明, 在室温下该传感器对低浓度的氯化氢气体仍具有较好的重复性和选择性响应, 可检测到体积分数为1×10^-6%的HCl气体, 响应和恢复时间分别为7和20 s, 相对标准偏差为±6.06%. 该传感器具有灵敏度高、 响应-恢复速度快、 可逆性好、 成本低和容易制备等特点.     

Determination of aluminum in environmental and biological samples by reversed-phase high-performance liquid chromatography via pre-column complexation with morin

Morin was used as a pre-column reagent for the determination of aluminum by RP-HPLC with fluorescence detection. This method has been successfully applied to direct determination of trace Al in environmental and biological samples. The response was linear from 6 x 10(-9) to 6 x 10(-5) M with a detection limit of 2 x 10(-9) M. In addition, the different Al complexes with morin were separated by the proposed HPLC procedure and their coordination ratios were depicted by molar-ratio method. The results showed that 1:1 and 2:1 Al-morin complexes formed.     

Benchmarking in a multiple criteria performance context: An application and a conceptual framework

This article presents a conceptual benchmarking framework which applies a multiple criteria approach to assess performance. In the process, a multiple criteria procedure is used to assess the performance of three hundred and ninety two (392) Portuguese firms. Based on the results of this procedure, a conceptual framework is devised to facilitate addressing relevant benchmarking implications. The framework is designed to provide a conceptual linkage between the performance measurement methodology and the organizational benchmarking system.     

Large tunneling anisotropic magnetoresistance in (Ga,Mn)As nanoconstrictions

We report a large tunneling anisotropic magnetoresistance (TAMR) in (Ga,Mn)As lateral nanoconstrictions. Unlike previously reported tunneling magnetoresistance effects in nanocontacts, the TAMR does not require noncollinear magnetization on either side of the constriction. The nature of the effect is established by a direct comparison of its phenomenology with that of normal anisotropic magnetoresistance (AMR) measured in the same lateral geometry. The direct link we establish between the TAMR and AMR indicates that TAMR may be observable in other materials showing room temperature AMR and demonstrates that the physics of nanoconstriction magnetoresistive devices can be much richer than previously thought.