نتایج جستجو برای: methanol
تعداد نتایج: 30713 فیلتر نتایج به سال:
Supercritical fluid extraction using carbon dioxide modified with methanol, methanol-diethylamine, or methanol-triethylamine was used to extract vinblastine from the aerial portions of Catharanthus roseus. An HPLC-electrospray ionization (ESI)/MS analysis method was also developed to quantify the alkaloids in these extracts. Of the supercritical solvents evaluated, carbon dioxide-methanol-triet...
Optimal conditions necessary for the cytochemical demonstration of megakaryocyte (Mk) and platelet acid phosphatase (AP) were determined. Methanol, a constituent of fixatives commor)Iy used in AP cytochemistry, was found to inhibit MkAP, and the degree of inhibition varied with Mk maturity. Immature Mk contained predominantly methanol-resistant AP, and mature Mk, predominantly methanol-sensitiv...
The explanation of the dielectric dynamics in methanol would offer knowledge of the Debye relaxation in supercooled monoalcohols. However, due to the fast crystallization, it is hard to attain the dynamics of pure methanol in the deeply supercooled region. In this paper, we studied the dynamics of methanol – 2-ethyl-1-hexanol mixtures with methanol concentration up to 80 mol% using dielectric a...
Using density functional theory (DFT) calculations, we performed a thorough theoretical investigation on the catalytic mechanism of oxidative self-coupling of methanol with molecular oxygen on Au-Ag catalysts. It is found that molecular oxygen can be activated via a hydroperoxyl (OOH) intermediate by taking a hydrogen atom from co-adsorbed methanol with an energy barrier of 0.51 eV, which is ac...
The European VLBI Network (EVN) has been used to make phase referenced, wide-field (several arcminute) spectral line observations of the 6.7-GHz methanol maser emission towards W51. In the W51main region, the bulk of the methanol is offset from an UCHii region. This probably indicates the methanol emission arises at the interface of the expanding UCHii region and not from an edge-on circumstell...
The coadsorption of methanol (CH3OH) and water (D2O) on the MgO~100!/Mo~100! surface at 100 K has been studied by metastable impact electron spectroscopy ~MIES!, ultraviolet photoelectron spectroscopy @UPS ~HeI!#, and by thermal programmed desorption ~TPD!. Methanol wets the MgO surface and adsorbs nondissociatively within the first monolayer with the hydroxyl group oriented toward the substrat...
To suppress methanol crossover in direct methanol fuel cells DMFCs , a Nafion-Bi2V0.75Sb0.25O5.4 composite membrane was prepared by recast method. Oxygen-ion conductive Bi2V0.75Sb0.25O5.4 powders were highly dispersed in a Nafion 117 membrane to physically block methanol crossover and/or chemically oxidize the methanol, which was confirmed by the difference in the methanol diffusion coefficient...
Optimal conditions necessary for the cytochemical demonstration of megakaryocyte (Mk) and platelet acid phosphatase (AP) were determined. Methanol, a constituent of fixatives commonly used in AP cytochemistry, was found to inhibit MkAP, and the degree of inhibition varied with Mk maturity. Immature Mk contained predominantly methanol-resistant AP, and mature Mk, predominantly methanol-sensitive...
A recombinant Pichia pastoris containing enterokinase light chain gene from bovine was cultured in flasks firstly at different pH, methanol addition, and cell mass concentration for enterokinase production. Activity of enterokinase increased as cell mass concentration increased at more than = 6 % methanol added. No significant change of activity of enterokinase was observed when methanol added ...
The direct methanol fuel cell (DMFC) is considered a viable power production technology for portable electronics equipment (10’s-100’s watts) and transportation vehicles (10’s-100’s kilowatts). Since methanol is relatively inexpensive and a reformer or other fuel processing equipment is not required for the DMFC, this power system has the potential to be low cost, compact, reliable and fuel eff...
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