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1.
The kinetic theory of the substrate reaction during the modification of enzyme activity previously described by Tsou has been applied to a study on the kinetics of slow irreversible inhibition of creatine kinase by planar anions. Kinetic equation of substrate reaction was derived according to the theoretical analysis and experiment data, and then was simplified. From the simplified equation for the substrate reaction in the presence of the inhibitors, the microscopic rate constants for the reaction of the inhibitors with enzyme were obtained. The mechanism of inhibition of enzyme activity was discussed.  相似文献   

2.
The influence of basic horizontal current on the propagation of internal wave in the non-homogeneous ocean is studied in this paper. By means of pseudo-static hypothesis, the basic equation on propagation of internal wave in the non-homogeneous ocean is derived. By using geometric optics approximation the eikonal equation and transport equation are obtained, at the same time in a sort of fluid field, i. e. M= M(y)i+t-M(x)j, the extended Snell law and analytical solution of the rays are also obtained. The present work is an extension to the ray theory of internal wave in the static ocean.  相似文献   

3.
4.
A modified kinetic equation was derived from an improved model by consideringthe influence of molar ratio on the two-reactant plasma reaction.The equation satisfactorilydescribes the relation of the conversion or the selectivity to the plasma power,the total flow rate andthe molar ratio used in the oxidation reaction of methane in nonequilibrium plasma and well tallieswith the experimental data.  相似文献   

5.
A theoretical form of the Martin-Hou equation of state   总被引:1,自引:0,他引:1  
A new equation of state is derived from the Barker-Henderson hard-sphere perturbation theory. It has the form similar to the Martin-Hou equation of state. The numerical values of the characteristic constants in the equation can be calculated by the method of Martin and Hou. The equation can be used to predict P-V-T properties accurately for fluids when the critical parameters (T_c, P_c and V_c) and one point on the vapor pressure cure are given. By using the functional relationships between the characteristic constants and the microscopic parameters, the molecular microscopic parameters of the substance can be obtained.  相似文献   

6.
A hypercrosslinked adsorption resin (ZH-05) modified by N-acetylaniline in the post crosslinking process was prepared. The adsorption properties of ZH-05 toward 2,4-dichlorophenol in comparison with granular activated carbon (GAC) and Amberlite XAD-4 were observed. The present study mainly focuses on the static equilibrium adsorption behaviors, desorption profiles and the proof of chemisorption. The results show that the Langmuir equation can give a perfect fitting to experimental data, and high temperature was favorable for adsorption of 2,4-dichlorophenol on ZH-05. A related equation was used to correlate the amount of chemisorption and the suppositionai chemisorption equilibrium concentration of adsorbate in aqueous solution. The adsorption capacities from different ranges of temperature and the static desorption experiment both reveal the same conclusion, i.e., the adsorption of 2,4-dichlorophenol from water on ZH-05 is a coexistent process of physical adsorption and chemical transition as on GAC.  相似文献   

7.
Based on an axial dispersion model, a generalized equation for HETP in column chromatography ispresented. From this equation, Van Deemter's equation for packed column and Golay's for capillary col-umn can be derived under simplified conditions. The generalized equation can be used to obtain variousempirical equations for HETP and gives physical significance to the empirical constants in them. It isadaptable to all column chromatography including packed and capillary columns as well as gas andliguid chromatography.  相似文献   

8.
The kinetics of the oxidation of lactic acid(Lac) by dihydroxyditelluratoargentate(Ⅲ)[abbreviated as DDA of Ag(Ⅲ)]anions was studied in an aqueous alkaline medium by conventional spectrophotometry in a temperature range of 25-40℃.The order of the redox reaction of lactic acid and DDA was found to be first-order.The rates increased with the increase in [OH^-]and decreased with the increase in [tellurate].No free radical was detected.In the view of this the dihydroxymonotelluratoargentate(Ⅲ)species(DMA) is assumed to be the active species.A plausible mechanism involving a two-electron transfer is proposed,and the rate equation derived from the mechanism can be used to explain all the experimenttal results.The activation parameters(25℃)and the rate constants of the rate-determining step along with the preequilibrium constants at different temperatures were evaluated.  相似文献   

9.
WANG Xin  ANG  Zhong-Zhi TANG  Dian 《结构化学》2010,29(6):972-976
RuO2,IrO2 and PdO are the most frequently employed active oxides in titanium anode coatings,so studies on the kinetics of their crystal-growth are important for anode material preparations.In this paper,the particle growths of RuO2,IrO2 and PdO with increased temperature were discussed.The least-squares method was used to fit the kinetic data.As a result,the two-stage phenomena are found in all three noble material systems.The linear regression equations are correct both for the first and second stages.It is suggested that based on the corresponding kinetics equation Ln D =-QL/kT + a,the sizes of oxide particles can be controlled for the three noble oxides.  相似文献   

10.
In this study, a constitutive model based on microscopic physical mechanism of silicone rubber foams was established. A theoretical statistical model of rubber elasticity considering the effect of dangling chains was modified to build this model. When a strain amplification factor(X) was introduced, the theoretical model could fit the tensile stress-strain data of mono-and bi-modal foam matrix well(Adj. R-Square = 0.9989, 0.9983). Parameters related to the polymer network, namely, average molecular weight(Mc) and volume fraction(ф) of chain segments between adjacent cross-linking points(network strands), were calculated by probabilistic method from the number-average molecular weight(Mn), vinyl content(w Vi) of the primary polysiloxanes and percent conversion(q) of vinyl groups. The primary and infinite strain amplification factors(X0, X∞) and decay exponent(z), introduced by X and related to the nanoparticles, were obtained by fitting. Inspired by the fact that the actual strain of matrix was lower than that of the foams', we introduced another item, strain hysteresis item(H, related with the foam porosity and cell structure), into the statistical model as well. With the same above values of Mc,ф, X0 and X∞, the model could also fit the compressive stress-strain data of mono-and bi-modal foams well(Adj. R-Square = 0.9948,0.9985). Interestingly, the strain hysteresis items of the mono-and bi-modal foams almost completely coincided under all experimental strains, which may be attributed to the almost equal porosity and similar cell structure of the two foams. This constitutive model may connect the macroscopic stress-strain behaviour to the parameters of microscopic molecular structures, promisingly providing a basis for the performance improvement and optimization of silicone rubber foams.  相似文献   

11.
Stress relaxation of poly(styrene-b-butadiene-b-styrene) thermoplastic elastomers is studied in dependence of molecular weight and degree of hydrogenation in the temperature range between ?30° and +80 °C. The influence of these parameters on the structure of the physical network and the degree of partial mixing in the domain boundary is investigated by separating the stress-relaxation modulus into a viscoelastic term and an equilibrium network modulus calculated from the relaxation-time spectrum. The temperature dependence of the one-second relaxation modulus is quantitatively described by use of a modified Kerner model for the simulation of the viscoelastic term. The modification allows the estimation of the volume fraction of interfacial material and its correlation to the parameters which govern phase separation.  相似文献   

12.
In this work, we present the modeling of the peak deceleration (PD) using data of the experimental drop test. Specimens with different thicknesses and areas tested in the drop test device which has adaptable height and weight. In the empirical modeling of the PD, the thickness, area, drop mass and drop height considered as separable functions. An analytical model and Neural Network (NN) was used as the empirical models. Further, the stress on the material was calculated using differential equations and the Finite Element Method (FEM). The Obtained PD from the experimental test, analytical and NN models was converted to the stress on the material using a derived differential equation. Finally, the best model for analyzing the PD and Stress on the material was presented.  相似文献   

13.
Calculation of polarizability gradients have been made for a number of diatomic molecules using the Finite Field CNDO/II approximate SCF method. Comparison with experimental results suggests that the method will be generally useful for the prediction and interpretation of Raman intensities.  相似文献   

14.
Stress relaxation has been studied in networks of styrene-butadiene-styrene triblock copolymers with spherical styrene domain structure containing 0.10 weight fraction of unattached linear polybutadiene (Mw = 389,000) or styrene-butadiene diblocks with very long butadiene segments (M = 225,000 or 510,000). The stretch ratio (uniaxial extension) was usually 1.15 and the temperature ranged from ?20 to +20°C. The contribution of the linear polybutadiene species to relaxation was essentially the same in two triblock networks with very different butadiene block lengths, as expected if the configurational rearrangements are dominated by reptation. In the diblock-triblock mixtures, in which the diblock butadiene segments are free at one end but anchored at the other and therefore incapable of reptation, there was no contribution to relaxation from the dangling butadiene segments of the diblock component; this would be expected if there are no relaxation mechanisms alternative to reptation for these very long semiattached species within the experimental time scale.  相似文献   

15.
1H spin-spin relaxation time(T2) measurement of polyampholyte hydrogel poly(methylacrylic acidacryloyloxyethyl trimethylammonium chloride)[P(MA-DAC)] in different pH, ionic strength and temperature was carried out to reveal the molecular mobility. Spontaneous volume transition of the polyampholyte hydrogel was also investigated by spin-spin relaxation time measurement. Meanwhile T2 and the proton component fraction were acquired to study the swelling behaviour of the hydrogel. Moreover the changes of T2 characterized the molecular mo- bility of polyampholyte hydrogel in various swelling states. And the results suggest that the mobility of the main chains and a few free side chains(the long T2) of P(MA-DAC) was dominated by the mesh size in the hydrogel net- work, depending on the swelling ratio(Q) and the mobility of the side chains(the short T2) was influenced by electrostatic interaction between different charges in polymer side chains. Finally the T2 measurements of P(MA-DAC) hydrogel in the spontaneous swelling-deswelling process demonstrated the electrostatic interaction of the charged side chains caused deswelling behavior. At the same time, the mobility state transition temperature of the charged side chains was also studied by the lH spin-spin relaxation time measurements, and the transition activation energy of the side chains is 2.72 kJ.  相似文献   

16.
An aqueous PVA-Cu2+ solution at pH = 3 is in the hydrated form and becomes green at pH ? 6 with a decrease in viscosity. The structure of the copper ion is suggested to be that of a polynuclear complex at pH > 6. For the green solution the polynuclear chains of the copper complex are believed to be surrounded by the PVA chains with the hydrophobic backbones facing toward the inside and the hydrophilic OH groups oriented toward the outside facing the bulk water. The proton spin-lattice relaxation rate 1/T1p and the spin-spin relaxation rate 1/T2 of CH and CH2 in PVA and H2O for aqueous PVA-Cu2+ solutions at pH = 3, can be explained by the two site exchange model in the region of the fast exchange limit. The dipolar correlation time τc is dominated by the reorientational process with a dipolar correlation time of 2.11 × 10?11 s. When the pH rises from pH=3 to pH=12.5, the variation of 1/T1p and 1/T2p of CH and CH2 in PVA with Cu2+ ion concentration in aqueous PVA-Cu2+ solution at pH=12.5 can be explained in terms of the relaxation by an inclusive model of the polynuclear copper complex and PVA. Furthermore, the frequency (or field) dependence of 1/T1p, 1/T2p of CH in PVA for aqueous PVA-Cu2+ solution at pH = 12.5 suggests that the dipolar relaxation is dominated by the electron-spin relaxation with the electron spin relaxation time T1e = 1 ? 2 × 10?10 s. The invariance of 1/T1p and 1/T2p of H2O with the variation of the Cu2+ ion concentration in aqueous PVA-Cu2+ solution at pH = 12.5 supports the hypothesis that the water is not directly bound to the Cu2+ ion.  相似文献   

17.
A generalized response function based on the use of dielectric spectra for dielectric relaxation process is derived. We apply the general response function to the special case in order to examine how special dielectric relaxation functions developed by other authors for solvent relaxation can be derived based on our formulations. Three typical solvents, water, methanol, and acetonitrile are used to investigate the electronic polarization processes of polar solvents. The solvent electronic polarization process is shown after a linear variation with the external electric field imposed on the solvent. The results show a conclusion that the electronic polarization of the solvents will accompany the electronic transition synchronously, without time lag.  相似文献   

18.
19.
The primitive chain model of Doi and Edwards is generalized to include the short-time relaxation process. Stress relaxation after a sudden imposition of strain is studied in detail. It is shown that in the linear region (small strain) stress relaxation occurs in two steps, the relaxation of chain segments between the fixed entanglement points, and the relaxation of the entanglement points, in accordance with the conventional picture, whereas in the nonlinear region (large strain) there appears a new relaxation process between the above two. The characteristic time of this process is the Rouse relaxation time which the entire chain would have if there were no entanglements, and increases with the square of the molecular weight. This result is consistent with experimental observations.  相似文献   

20.
Viscoelastic and thermodynamic properties of transient gels formed by telechelic associating polymers are studied on the basis of the transient network theory that considers the correlation among polymer chains via network junctions. The global information of the gel is incorporated into the theory by introducing elastically effective chains defined according to the criterion of Scanlan [J. Polym. Sci. 43, 501 (1960)] and Case [J. Polym. Sci. 45, 397 (1960)]. We also consider the effects of superbridges whose backbone is formed by several chains connected in series and containing several breakable junctions. The dynamic shear moduli of this system are well described in terms of the Maxwell model characterized by a single relaxation time and high-frequency plateau modulus. Near the critical concentration at the sol/gel transition, superbridges become infinitely long along the backbone, thereby leading to a short relaxation time tau for the network. It is shown that tau is proportional to the concentration deviation Delta near the gelation point. The plateau modulus G(infinity) increases as the cube of Delta near the gelation point as a result of the mean-field treatment, and hence the zero-shear viscosity increases as eta(0) approximately G(infinity)tau approximately Delta(4). The present model can explain the concentration dependence of the dynamic moduli observed for aqueous solutions of telechelic poly(ethylene oxide).  相似文献   

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