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101.
A theoretical analysis is made for thermophoretic transport of small particles through a fully developed laminar, mixed convection
flow in a parallel vertical channel. The governing gas-particle ordinary differential equations are expressed in non-dimensional
form and are solved numerically for some values of the governing parameters so as to investigate extensively their distinct
influence on the flow pattern. These equations are solved also analytically in the special case when the thermophoretic effect
is absent and the obtained analytical solution can be regarded as a verification of the numerical results, simultaneously.
The parameter zone for the occurrence of reversed flow is presented. It is found that the effect of thermophoretic can be
quite significant in appropriate situations. 相似文献
102.
103.
104.
This paper deals with a theoretical (numerical) analysis of the effects that blowing/injection and suction have on the steady mixed convection or combined forced and free convection boundary layer flows over a vertical slender cylinder with a mainstream velocity and a wall surface temperature proportional to the axial distance along the surface of the cylinder. Both cases of buoyancy forces aid and oppose the development of the boundary layer are considered. Similarity equations are derived and their solutions are dependent upon the mixed convection parameter, the non-dimensional transpiration parameter and the curvature parameter, as well as of the Prandtl number. Dual solutions for the previously studied mixed convection boundary layer flows over an impermeable surface of the cylinder are shown to exist also in the present problem for aiding and opposing flow situations. 相似文献
105.
106.
Orlik S. N. Pop G. Ganea R. Ostapyuk V. A. Alekseenko L. M. 《Theoretical and Experimental Chemistry》2004,40(3):187-191
We used X-ray phase analysis, IR, X-ray photoelectron, and NMR spectroscopy to characterize a synthesized mesoporous material (Fe,Al)-MCM-41. As a result of a certain combination of structural, acidic, and oxidation–reduction properties of the surface, (Fe,Al)-MCM-41 exhibits catalytic activity in reactions with participation of nitrogen oxides, in particular partial oxidation of propane by nitrogen(I) oxide to isopropanol. 相似文献
107.
Anamaria Iulia Torok Erika Andrea Levei Silviu Constantin Oana Teodora Moldovan Marin Senila Oana Cadar Dorina Casoni Simion Bogdan Angyus Claudiu Tanaselia Eniko Covaci Tiberiu Frentiu 《Molecules (Basel, Switzerland)》2021,26(22)
The aim of the study was to develop the hydrogeochemical profiling of caves based on the elemental composition of water and silty soil samples and a multivariate statistical analysis. Major and trace elements, including rare earths, were determined in the water and soil samples. The general characteristics of water, anions content, inorganic and organic carbon fractions and nitrogen species (NO3− and NH4+) were also considered. The ANOVA—principal component analysis (PCA) and two-way joining analysis were applied on samples collected from Cloșani Cave, Romania. The ANOVA-PCA revealed that the hydrogeochemical characteristics of Ca2+-HCO3− water facies were described by five factors, the strongest being associated with water-carbonate rock interactions and the occurrence of Ca, Mg and HCO3− (43.4%). Although organic carbon fractions have a lower influence (20.1%) than inorganic ones on water characteristics, they are involved in the chemical processes of nitrogen and of the elements involved in redox processes (Fe, Mn, Cr and Sn). The seasonal variability of water characteristics, especially during the spring, was observed. The variability of silty soil samples was described by four principal components, the strongest influence being attributed to rare earth elements (52.2%). The ANOVA-PCA provided deeper information compared to Gibbs and Piper diagrams and the correlation analysis. 相似文献
108.
Dr. Agnieszka Swiderska-Mocek Izabela Karczewska Dr. Agnieszka Gabryelczyk Dr. Mikołaj Popławski Prof. Dr. Dorota Czarnecka-Komorowska 《Chemphyschem》2023,24(20):e202300090
A gel polymer electrolyte based on poly(vinyl alcohol) (PVA) is used in sodium-ion batteries (SIBs). The use of biodegradable and water-soluble polymer potentially reduces the negative environmental impact. The other components include sodium salt (NaPF6), sulfolane (TMS) as a plasticizer and talc. For the first time, natural and abundant talc has been used as an inert filler in a gel polymer electrolyte. The best results were obtained for moderate amounts of filler (1 and 3 wt%). Then, an increase in the conductivity, transference numbers, and thermal stability of the membranes was observed. Moreover, the presence of talc had a positive effect on the cyclability of the hard carbon electrode. The discharge capacity after 50 cycles of HC|1 % T_TMS|Na and HC|3 % T_TMS|Na was 243 and 225 mAh g−1, respectively. The use of talc in gel polymer electrolytes containing sodium ions improves the safety and efficiency of SIBs. 相似文献
109.
N. I. Ionescu B. Albu I. Iosif M. Bozeanu G. Musca Gr. Pop 《Reaction Kinetics and Catalysis Letters》1985,28(2):437-441
The catalytic conversion of methanol to olefins over ZSM-5 zeolite modified by ion exchange with Mg exhibits an autocatalytic character. On this basis an overall kinetic model of the reaction was proposed which allowed the determination of rate constants and apparent activation energy.
ZSM-5, Mg, . , .相似文献
110.
Iulia Matei Anca Nicolae Mihaela Hillebrand 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):597-601
The complex formed by the inclusion of the polarity-sensitive fluorescent probe 2-[2′-quinoxalinyl]-phenoxathiin (QP) into
β-cyclodextrin (β-CD) was investigated by steady-state fluorescence spectroscopy in order to confirm the previously stated intramolecular charge
transfer nature of the first excited singlet state of QP. A decrease in the emission intensity in the presence of β-CD was observed and explained on this basis. The 1:1 stoichiometry of the inclusion complex and its association constant
of 2,223 M−1 were computed. The QP–β-CD complex was further studied by molecular mechanics (MM+ force field), in order to determine its structure and the type
of interactions between QP and β-CD. All possible ways QP could penetrate the β-CD cavity were considered and several structures were generated and optimized. The interaction, binding (van der Waals and
electrostatic contributions) and perturbation energies were also calculated. The results have showed that the β-CD cavity incorporates the central part of QP and that complexation is mainly due to van der Waals host–guest interactions. 相似文献