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991.
Top layers of γ-Al2O3 composite membranes have been modified by the silane coupling technique using phenyltriethoxysilane for improving the separation factor of CO2 to N2. The separation efficiency of the modified membranes was strongly dependent upon the hydroxylation tendency of the support materials and the amount of the special functional group (i.e. phenyl radical) which was coupled onto a top layer. The separation factor through the TiO2 supported γ-Al2O3 membrane was found to be fairly enhanced by silane coupling, but in case of the -Al2O3 supported membrane was not. The CO2/N2 separation factor through the modified γ-Al2O3/TiO2 composite membrane is 1.7 at 90°C and ΔP = 2 × 105 Pa for the binary mixture containing 50 vol% CO2. The separation factor is proportional to the CO2 concentration in the gas mixture, and the modified membrane is stable up to 100°C. The main mechanism of the CO2 transport through the modified γ-Al2O3 layer is known to be a surface diffusion. 相似文献
992.
Analysis of scopolamine and its eighteen metabolites in rat urine by liquid chromatography-tandem mass spectrometry 总被引:1,自引:0,他引:1
A rapid and sensitive method is described for the determination of scopolamine and its metabolites in rat urine by combining liquid chromatography and tandem mass spectrometry (LC–MS/MS). Various extraction techniques (free fraction, acid hydrolyses and enzyme hydrolyses) and their comparison were carried out for investigation of the metabolism of scopolamine. After extraction procedure, the pretreated samples were injected into a reversed-phase C18 column with mobile phase of methanol/ ammonium acetate (2 mM, adjusted to pH 3.5 with formic acid) (70:30, v/v) and detected by an on-line MS/MS system. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular masses (ΔM), retention-times and full scan MSn spectra with those of the parent drug. The results revealed that at least 18 metabolites (norscopine, scopine, tropic acid, aponorscopolamine, aposcopolamine, norscopolamine, hydroxyscopolamine, hydroxyscopolamine N-oxide, p-hydroxy-m-methoxyscopolamine, trihydroxyscopolamine, dihydroxy-methoxyscopolamine, hydroxyl-dimethoxyscopolamine, glucuronide conjugates and sulfate conjugates of norscopolamine, hydroxyscopolamine and the parent drug) and the parent drug existed in urine after ingesting 55 mg/kg scopolamine to healthy rats. Hydroxyscopolamine, p-hydroxy-m-methoxyscopolamine and the parent drug were detected in rat urine for up 106 h after ingestion of scopolamine. 相似文献
993.
Din-Goa Liu Jyh-Fu Lee Mau-Tsu Tang 《Journal of molecular catalysis. A, Chemical》2005,240(1-2):197-206
X-ray absorption spectroscopy (XAS) was employed to characterize carbon black supported Pt-Ru catalysts, which are commercially available to be utilized as the anode of polymeric-electrolyte-membrane fuel cells. Both Pt and Ru were found partially oxidized in the as-received form. Upon exposure to hydrogen at room temperature, the catalysts were completely reduced to the metallic state. The bimetallic nanoparticles on the Pt-Ru/C catalysts possess an inner core enriched in Pt, which is surrounded by a Ru-rich outer shell. Such a core–shell structure retained even at an elevated reduction temperature of 623 K. Temperature-programmed surface reaction (TPSR) was carried out to explore the reactivity of adsorbed CO toward hydrogen on various catalysts. Both the peak temperature of the TPSR profile and the amount of methane generated during the course of TPSR were sensitive to the surface composition of Pt–Ru nanoparticles. In combination of XAS and TPSR results, a slight difference in the nanostructure between two Pt-Ru/C catalysts was manifested. 相似文献
994.
S. Cebulak B. Smieja-Król S. Duber M. Misz A. W. Morawski 《Journal of Thermal Analysis and Calorimetry》2004,77(1):201-206
The paper presents the applicability of Oxyreactive Thermal Analysis (OTA) for the investigation of different kinds of carbon
matter. For comparative reasons and more precise interpretation, along with OTA some physico-chemical properties of analyzed
materials were used as the methods commonly applied for the investigations.
The carbon materials of both natural (anthracites, graphite and diamonds) and synthetic origin (active carbon, glass carbon,
expanded graphite, soot and synthetic diamonds) were investigated.
It was stated that there is close relationship between structure parameters and physico-chemical properties and the thermal
reactivity within the investigated groups of carbon matters. The results show that OTA can be accepted as a good investigative
way for such materials.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
995.
996.
The reaction of dibenzylphosphine oxide with O-methyloximes of some ,-unsaturated ketones results in the phosphorylation at the -carbon atom to form methoxyiminophosphine oxides, whereas the reaction of dibenzylphosphine oxide with O-methyloximes of ,-unsaturated aldehydes affords aminodihydrophosphole oxides. 相似文献
997.
Rupert B. Hurley 《Journal of separation science》1980,3(3):147-148
This paper describes a design for an all-glass GC/MS interface. The design has advantages due to low dead volume, lack of column effluent adsorption and degradation, simple interface production and installation, and ease of column mounting/dismounting. 相似文献
998.
Vinzenz Bachler Gottfried Olbrich Oskar E. Polansky Yuh-Kang Pan 《Theoretical chemistry accounts》1979,50(4):327-342
A CNDO/2 SCF perturbation theory is presented for interpreting the form of CNDO/2 potential energy surfaces of unimolecular reactions. The analysis is performed by calculating the energy change E arising from a distortion of the molecular geometry along the reaction coordinate. E is decomposed into different perturbational contributions which are appropriate for an interpretation of the perturbation energy E. Moreover, E is resolved into energy parts arising from a single occupied orbital and contributions due to pairwise orbital interactions. In this way one evaluates numerically how the form of the occupied and unoccupied orbitals determines the magnitude of E. If the distortion occurs along a definite symmetry coordinate, group-theoretical arguments can be applied to discuss the magnitude of characteristic components of the perturbation energy. The SCF perturbation theory is used to analyze the isomerization of ethylene, cis-2-butene and cis-2-butenenitrile.This work was partially supported by Nato-Grant No. 1072 相似文献
999.
Ming-Wei Yang Shi-Yow Lin 《Colloids and surfaces. A, Physicochemical and engineering aspects》2003,220(1-3):199-210
The θ/2 method, a widely used technique on measuring the contact angle of a sessile drop, assumes that the drop profile is part of a sphere. However, the shape profile of a sessile drop is governed by the Young–Laplace equation and is different from a sphere, especially for drops with a large bound number (e.g. large volume or small surface tension). The spherical assumption, therefore, causes errors on evaluating the contact angles. The deviation of contact angle from the θ/2 method is evaluated from a theoretical calculation in this work. A simple means is given for correcting the measurement error. The corrected angle results from the drop volume, surface tension, liquid density and the contact angle from θ/2 method. An algorithm for finding the correct contact angle without knowing the density and surface tension is also given. At the end, two examples of pendant drops are given for the illustration. 相似文献
1000.
Zheng-Ping Yi Jun Hu Hui-Lan Chen 《Journal of inclusion phenomena and macrocyclic chemistry》2003,45(1-2):1-8
Conformational analysis of inclusion complexes of sodium 3-hydroxy-2-naphthalenecarboxylate with -cyclodextrin and heptakis-(2,3,6-tri-o-methyl)--cyclodextrin in D2O was investigated by 1D and 2D 1HNMR measurements. The results show that part of the naphthyl group of sodium 3-hydroxy-2-naphthalenecarboxylate is situated in the 2,3-OH side of the -cyclodextrin cavity asymmetrically while the whole naphthyl group is included in the heptakis-(2,3,6-tri-o-methyl)--cyclodextrin cavity with the caboxylate and hydroxy group close to the 6-OCH3 group. 相似文献