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101.
Katya Arishtirova Barbara Pawelec Rodimir N. Nikolov J. L. G. Fierro Sonia Damyanova 《Reaction Kinetics and Catalysis Letters》2007,91(2):241-248
The effect of Pt/Ni ratio on the surface properties and catalytic behavior of bimetallic PtNi catalysts for reforming of methane
with CO2 was studied. The TPR, FTIR of adsorbed CO and XPS data showed that introduction of a small amount of Pt (0.3 – 0.5 wt.%)
into the Ni catalyst leads to a decrease of the NiO size, its easy reduction and a uniform distribution of the nickel metal
particles. 相似文献
102.
Clay A. Henry Mel Judy Barbara Dyer Martin Wagner James L. Matthews 《Photochemistry and photobiology》1995,61(4):410-413
Abstract— The phototoxicity of argon laser irradiation was studied in aqueous suspensions of Porphyromonas endodontalis (American Type Culture Collection [ATCC] 35406), Porphyromonas gingivalis (ATCC 33277), Prevotella denticola (ATCC 33184) and two strains of Prevotella intermedia (ATCC 15033 and 49046), all "black-pigmented bacteria," BPB, that accumulate cellular porphyrins. Several of these species have been implicated in the etiology of Periodontol disease. Non-black-pigmented bacteria were also studied to test the specificity of irradiation as a potential photodynamic treatment for Periodontol infections. Cell suspensions were irradiated with an argon laser at fluences of 20–200 J/cm2 . When cultured in hemin-supplemented media, ATCC 15033 was the most sensitive to irradiation. However, a second strain of the same species (ATCC 49046) was resistant. The photosensitivity of other species ranked ATCC 33277 > 35406 = 33184 = 35496. When hemin was replaced in media by hemoglobin, ATCC 33277 became resistant to irradiation. Protoporphyrin IX content in BPB cells was shown not to be a major factor determining photosensitivity. Oxygen was required during irradiation for BPB species to be affected. Non-black-pigmented bacteria were much less sensitive to irradiation than BPB. 相似文献
103.
We introduce a dynamical system, for which it is possible to get such a large number of eigenvalues that deviations from Wigner's surmise are visible. The obtained level-spacing distribution agrees much better with the distribution derived from random matrix theory. 相似文献
104.
Congo red (CR) is an azo dye which not only preferentially binds to elastin, an extracellular matrix protein found in the media of arterial vessel walls, but also fluoresces when it binds to this protein. Protein solubilization data following laser irradiation of elastin:CR suspensions determined that the amount of elastin solubilized by laser irradiation increased with the increase in CR. The saturation point of CR to elastin was attained when 400 g CR was added to 20 mg elastin suspension. When 20 ml of a 5% CR solution in 5% dextrose was administered intravenously, the CR was absorbed in levels sufficient to produce fluorescence of the main arteries in rabbits. Layers of tissue both in the media of the vessels and at the endothelial/intimal interface were clearly differentiated. Therefore, the elastin:CR complex appears to be an ideal system in which the elastin fluorescence could aid in distinguishing between normal and diseased tissue in certain pathological conditions, such as atherosclerosis and some types of breast tumors. 相似文献
105.
Magdalena Kloskowska Jarosaw Chojnacki Wiesaw Wojnowski Barbara Becker 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(11):m541-m544
The title complex, [Li2(D2O)6][Li(C9H27SSiO3)2]2·2D2O, is the first compound with an S—M bond (M = alkali metal) within an unusual type of lithate anion, [Li(SR)2]− {where R is Si[OC(CH3)3]3}. There is a centre of symmetry located in the middle of the Li2O2 ring of the cation. All Li atoms are four‐coordinate, with LiO4 (cations) and LiO2S2 (anions) cores. The singly charged [Li(SR)2]− anions are well separated from the doubly charged [Li2(D2O)6]2+ cations; the distance between Li atoms from differently charged ions is greater than 5 Å. Both ion types are held within an extended network of O—D⋯O and O—D⋯S hydrogen bonds. 相似文献
106.
The NCI(F?) and NCI(NH2?) mass spectra of a series of aliphatic acetates and of methyl and ethyl trimethylacetate have been obtained. The formation of fluoroenolate ions CH2COF? and of carboxamide anions RCONH? (R ? CH3))CH3C). respectively, is observed besides formation of [M ? H]? ions and carboxylate ions RCOO? (R ? CH3, (CH3)3C). The relative intensities of the different anions depend on the structure of the ester molecules and on the primary reactant anions. Usually, the NCI(NH2?) spectra of the acetates are dominated by [M ? H]? ions ([M? D]? ions in the case of trideuteroacetates) fragmenting unimolecularly by elimination of an alcohol. The carboxylate ions are important fragments, too, but carboxamide ions are only observed with large intensities in the NCI(NH2? spectra of the trimethylacetates. The NCI(F?) spectra show much larger intensities of carboxylate ions and fluoroenolate ions. The mechanisms of the fragmentation reactions are discussed. The results indicate that most or even all of the fragment ions in the NCI(F? mass spectra of aliphatic esters are formed by addition-elimination reactions via a tetrahedral intermediate, while competition between direct proton abstraction and addition-elimination reactions occurs in the NCI(NH2?) mass spectra because of the higher basicity of NH2? resulting in an early transition state for direct proton abstraction. 相似文献
107.
A new oblique impinging-jet (OBIJ) cell was developed, suitable for colloid deposition studies at various interfaces. In contrast to previously used orthogonal cells, the OBIJ construction makes possible direct microscope observations of particle deposition on nontransparent substrates. The cell performance was tested by studying kinetics of polystyrene latex particle deposition on mica. Two limiting cell configuration were used in the experiments: (i) the lower position (inverted microscope observation of substrate surface through air) and (ii) the upper position (observation of the substrate surface with adsorbed particles through the suspension layer). The dependence of local mass transfer rate (particle flux) on the position over the substrate surface was studied for various flow Reynolds numbers. It was demonstrated that deposition rate attained maximum at the flow stagnation point whose position was dependent on Re number. Moreover, it was shown that the local flux decreased at much slower rate when moving in the downstream direction, than for previously used impinging-jet cells. Consequently, the area of uniform transport conditions was larger, enabling more precise determination of the limiting particle flux at the stagnation-point. The dependence of the flux on Re number was systematically studied for various ionic strength of the suspension. It was demonstrated, in accordance with previous results for the ordinary impinging-jet, that the flux increased significantly for low ionic strength and high Re number. This phenomenon, referred to as the inverse salt effect, was interpreted in terms of the convective diffusion theory. The governing transport equation originating from this theory was solved numerically, for the region near the stagnation point, using the finite-difference method. These numerical solutions were used for nonlinear fitting of the flow intensity parameter dependence on the Re number. In this way the flow field in the vicinity of the stagnation point was fully characterized. It was concluded that the new cell can be exploited as an effective experimental tool for colloid deposition studies on various substrates. 相似文献
108.
Magdalena Kurdziel Elżbieta Szczepaniec-Cieciak Monika Watorczyk Barbara Dabrowska 《Journal of solution chemistry》2004,33(5):453-464
The solubility of solid 2-methyl-1,3-butadiene (isoprene) in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K has been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in the solute. The experimental value of the mole fraction solubility of solid isoprene in liquid argon at 87.3 K is (1.41 ± 0.27) × 10–6 and (1.56 ± 0.36) × 10–7 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbon in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l
12 were also calculated. At 90.0 K liquid argon is a better solvent for isoprene than is liquid nitrogen. The experimental values of the solubilities of isoprene in liquid argon and nitrogen were compared with results obtained for selected unsaturated and aromatic hydrocarbons. 相似文献
109.
Magdalena Kurdziel Elżbieta Szczepaniec-Cięciak Barbara Dąbrowska Wojciech Nitek Katarzyna Paliś Edyta Ślusarska 《Journal of solution chemistry》2003,32(7):601-615
The solubilities of solid 2,3-dimethylbutane and cyclopentene in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in solutes. The experimental value of the mole fraction solubility of solid 2,3-dimethyl-butane in liquid argon at 87.3 K is (8.26 ± 1.60) × 10–6 and (2.77 ± 0.94) × 10–8 in liquid nitrogen at 77.4 K. The experimental value of the mole fraction solubility of solid cyclopentene in liquid argon at 87.3 K is (5.11 ± 0.44) × 10–6 and (4.60 ± 0.76) × 10–8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbons in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l
12 were also calculated. At 90.0 K liquid argon is a better solvent for investigated solid hydrocarbons than is liquid nitrogen. 相似文献
110.
Aromatic aldehydes (1 a-g) yield linear condensation products (3 a-1) with dimeric ethyl and methyl cyanoacetate, resp., and dimeric malonitrile. Reduction of the condensation product of o-nitrobenzaldehyde with dimeric methyl cyanoacetate leads to methyl (3-methoxycarbonyl-1,2-dihydro-2-chinolinylidene)-cyanoacetate (4), with o-aminobenzaldehyde a carbostyril derivative5 a is obtained. In the presence of ammonium acetate aromatic aldehydes react with dimeric methyl and ethyl cyanoacetate, resp. to hexahydro-pyrimidinylidene cyanoacetates (8). 相似文献