Peristaltic motion induced by a surface acoustic wave of a viscous, compressible and electrically conducting Maxwell fluid in a confined parallel-plane microchannel through a porous medium is investigated in the presence of a constant magnetic field. The slip velocity is considered and the problem is discussed only for the free pumping case. A perturbation technique is employed to analyze the problem in terms of a small amplitude ratio. The phenomenon of a “backward flow” is found to exist in the center and at the boundaries of the channel. In the second order approximation, the net axial velocity is calculated for various values of the fluid parameters. Finally, the effects of the parameters of interest on the mean axial velocity, the reversal flow, and the perturbation function are discussed and shown graphically. We find that in the non-Newtonian regime, there is a possibility of a fluid flow in the direction opposite to the propagation of the traveling wave. This work is the most general model of peristalsis created to date with wide-ranging applications in biological, geophysical and industrial fluid dynamics. 相似文献
Spectral properties of some 2-Quinolones were investigate-ed. IR and 1H NMR were applied to characterize the ligands. The hydrogen bond property is of important parameter for controlling the behaviour of the compounds. The N[sbnd]H, O[sbnd]H, C[dbnd]O, C[sbnd]H, and C[sbnd]N fundamental functional groups are characterized. The electronic transitions are assigned. The data are explained on the basis of molecular structure and substituents effects. The acid-base equilibria and the phenomena of tautomerism for these compounds are explained and discussed. The acid exponents (pKOH, and pKNH) are evaluated. 相似文献
Innovative poly‐substituted heterocyclic rings incorporating dioxoisoindoline ( 2 – 25 ) were synthesized through the reaction of dioxoisoindoline derivative 2 as starting compound with various types of reagents. All compounds were characterized by appropriate means of (1H‐NMR, 13C‐NMR, IR, and mass). The prepared compounds were evaluated as antimicrobial agents against Escherichia coli, Staphylococcus aureus, and Candida albicans microorganisms. The tested compounds exhibited low to moderate antibacterial activities and promising results as antifungal agents. 相似文献
Russian Journal of General Chemistry - 2-Aminouracil is used in the synthesis of a new series of tri- and tetracyclic pyrimidine scaffolds as the precursor. Thiazolo[5,4-d]triazolo[4,3-a]pyrimidine... 相似文献
Poisoning the illicit materials by a neutron absorber leads to false detection when the detection is relied on combined thermal neutron activation and fast neutron activation to identify the elements of interest. The use of adjacent transmission thermal neutron detector for verifying the presence of neutron poisons and to trigger an alarm was investigated experimentally and using MCNP calculations. The illicit material of high hydrogen content will affect the detector response in the presence or absence of poisons. 相似文献
Journal of Radioanalytical and Nuclear Chemistry - Neutron backscattering technique is investigated as an alternative way for measuring the level of water in the horizontal oil gravity separators.... 相似文献
Thermal events encountered throughout the heat treatment of praseodymium acetate, Pr(CH3COO)3·H2O, were studied in nitrogen and air atmospheres. The samples calcined at the 300–700 °C temperature range were characterized using XRD, IR and N2 adsorption. Moreover, in situ electrical conductivity was employed to follow up the formation of the different decomposition intermediates. The results indicated that the anhydrous salt decomposes to the final product, PrO1.833, through the formation of the following intermediates: Pr(OH)(CH3COO)2, PrO(CH3COO) and Pr2O2(CO3). PrO1.833 formed at 500, 600, and 700 °C possesses a surface area of 17, 16 and 10 m2/g and crystallites size of 14, 17 and 30 nm, respectively. 相似文献
The molecular structure of 1,3-dimethyluracil (C6H8N2O2; 1,3-DMU) is studied theoretically and experimentally using Gaussian 98 calculations and different spectroscopic techniques. The vibrational spectrum for 1,3-DMU in the solid phase is recorded in the IR range 4000-400 cm–1. Initially, in order to get the most stable structure, twelve structures were proposed for the titled compound as a result of the internal rotation of CH3 around C–N bonds and keto-enol tautomerism. The single point energy and frequency calculations are obtained by MP2 (Full) and DFT/B3LYP methods with the 6-31G(d) basis set using the Gaussian 98 computation package. After the complete relaxation of twelve isolated isomers, the (diketo) tautomer was the only favored structure owing to its low energy relative to the other isomers and the prediction of real frequencies. This interpretation is supported by the recorded infrared spectrum that shows the presence of only the diketo tautomer. Aided by the normal coordinate analysis and potential energy distributions, a confident vibrational assignment of the fundamental frequencies is calculated. The results are discussed herein and compared with similar molecules whenever possible. 相似文献
The solid–solid interactions between cobalt and ferric oxides to produce CoFe2O4 were followed up using XRD investigation. The effect of Li2O-doping on the ferrite formation was also studied. The electrical and dielectric parameters of pure and doped mixed solids precalcined at 1273 K were measured using d.c and a.c instruments.The dopant concentration was varied between 0.5 and 6 mol% Li2O. The results obtained revealed that Li2O doping much enhanced the ferrite formation due to an increase in the mobility of the reacting species.
The addition of the smallest amount of Li2O (0.5 mol%) resulted in measurable variations in the electrical constants (ρ, Ea, ′, ″ and tan δ). Resistivity increased upon increasing the dopant concentration up to 1.5 mol% exceeding the values measured for the undoped sample. Furthermore, the presence of 6 mol% Li2O brought about a significant decrease of electrical resistivity. Also, the activation energy decreased with increasing the dopant concentration. The dielectric constant behaves according to ε=const. 1/ρ1/2.
The Li2O-doping modified the values of different dielectric constants, the change in these constants was found to be strongly dependent on the amount of Li2O added.These results have been discussed in terms of the potentiality of Li2O in increasing the mobility of the reacting species involved in the ferrite formation. 相似文献