Thermodynamic activation functions of viscous flow of non-polar liquids

The thermodynamic activation function of viscous flow may be determined from the expression for the pre-exponential factor in the Eyring relationship (the viscosity coefficient), which is a function of density and relative permittivity, together with the thermal dependence of the viscosity coefficient. This method of determination is demonstrated for a series of n-alkanes C₆–C₂₀.List of symbols A, B, C parameters in empirical viscosity-temperature dependence - E molecular bond energies of liquid calculated from heat of evaporation in vacuum - E _v viscous flow activation energy - G activation Gibbs function of viscous flow - H _v heat of evaporation - H _vb heat of evaporation at boiling point - H viscous flow activation enthalpy - k Boltzmann constant - m weight of molecule - M relative molecular weight - N _A Avogadro constant - q total number of bonds in one mole of liquid - R gas constant - S _id entropy of one mole of compound in ideal gas state - S _sat entropy of one mole of compound in saturated vapour state - S activation entropy of viscous flow - T absolute temperature - T _c critical temperature - T _r reduced temperature - T _c critical volume - T _f free volume of liquid per molecule - V ₀ molar volume of molecules - V _m molar volume of liquid - relative permittivity - viscosity - density - _r reduced density     

羟丙基甲基纤维素作为水泥添加剂研究(一)

以三聚氯胺甲醛树脂磺酸盐（MS）为分散剂，羟丙基甲基纤维素衍生物为粘稠剂，研究了它们的复合物对混凝土材料的分散性与粘稠性及其它性能的影响，并探索了其作用机理．     

PREPARATION AND CHARACTERIZATION OF SCHIFF BASE POLYMERS DERIVED FROM 4,4''''-METHYLENEBIS(CINNAMALDEHYDE)

New Schiff base polymers poly[4,4'-methylenebis(cinnamaldehyde)ethylenediimine] (PMBCen), poly[4,4'-methylenebis(cinnamaldehyde) 1,2-propylenediimine] (PMBCPn), poly[4,4'-methylenebis(cinnamaldehyde) 1,3-propylenediimine] (PMBCPR), poly[4,4'-methylenebis(cinnamaldehyde)l,2-phenylenediimine] (PMBCPh), poly[4,4'-methylene-bis(cinnamaldehyde)meso-stilbenediimine] (PMBCS), poly[4,4'-methylenebis(cinnamaldehyde)urea] (PMBCUR), poly[4,4'-methylenebis(cinnamaldehyde)semicarbazone] (PMBCSc), poly[4,4'-methylenebis(cinnamaldehyde)thiosemicarbazone] (PMBCTSc) and poly[4,4'-methylenebis(cinnamaldehyde)hydrazone] (PMBCH) were formed by polycondensation of 4,4'-methylenebis(cinnamaldehyde) with ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,2-phenylenediamine, meso-stilbenediamine, urea, semicarbazide, thiosemicarbazide and hydrazine, respectively. The dialdehyde and polymers have been characterized through elemental micro-analysis, IR, UV-Vis and 'H-NMR spectroscopic techniques. Thermoanalytical studies and viscous flow of dilute solutions of dialdehyde and its polymers have been examined and compared.     

Excess volumes and viscosities of mixtures of nitrobenzene and certain aromatic bases

Excess molar volumes V ^E , excess viscosities ^E , excess Gibbs energy changes for viscous flow G^E and interaction parameters d for binary mixtures of nitrobenzene with aniline, N-methylaniline and m-chloroaniline at selected compositions were determined from the measured values of densities and viscosities of pure components and their mixtures at 30°C. UV-visible spectra for all the binary mixtures were recorded and showed a characteristic absorption maximum. The results are analyzed in terms of interactions arising due to electrondonor-acceptor (EDA) or charge transfer (CT) complexation.     

Native Cellulose II Production by Acetobacter Xylinum Under Physical Constraints

Acetobacter xylinum, which normally produces ribbon-like microfibrils of cellulose I, occasionally synthesizes a band-like cellulose (native band, or NB) having a cellulose II crystal structure with a putative folded-chain structure. In contrast to a previous finding of NB production by a mutant strain of A. xylinum, we found that the wild-type strain also produced NB when incubated on agar plate medium. Incubation of the same strain in liquid media of varying viscosity with the addition of polyethylene glycol (PEG) resulted in the production of normal ribbon at low viscosities and NB at high viscosities. This behaviour was independent of the molecular weight of PEG and there seemed to be a critical level in viscosity for the switching from ribbon production to NB production. These findings strongly suggest that NB production is induced by a low mobility of cells in the culture medium due to physical constraints.     

Global Existence and Blow-up of Solutions to Multi-dimensional （n ≤ 5） Viscous Cahn-Hilliard Equation

In this paper we consider the viscous Cahn-Hilliard equation with spatial dimension n ≤5, and established global existence of weak solutions for small initial value and blow-up of solutions for any nontrivial initial data.     

Viscous compressible barotropic symmetric flows with free boundary under general mass force Part I: Uniform‐in‐time bounds and stabilization

We consider symmetric flows of a viscous compressible barotropic fluid with a free boundary, under a general mass force depending both on the Eulerian and Lagrangian co‐ordinates, with arbitrarily large initial data. For a general non‐monotone state function p, we prove uniform‐in‐time energy bound and the uniform bounds for the density ρ, together with the stabilization as t → ∞ of the kinetic and potential energies. We also obtain H¹‐stabilization of the velocity v to zero provided that the second viscosity is zero. For either increasing or non‐decreasing p, we study the L^λ‐stabilization of ρ and the stabilization of the free boundary together with the corresponding ω‐limit set in the general case of non‐unique stationary solution possibly with zones of vacuum. In the case of increasing p and stationary densities ρ_S separated from zero, we establish the uniform‐in‐time H¹‐bounds and the uniform stabilization for ρ and v. All these results are stated and mainly proved in the Eulerian co‐ordinates. They are supplemented with the corresponding stabilization results in the Lagrangian co‐ordinates in the case of ρ_S separated from zero. Copyright © 2005 John Wiley & Sons, Ltd.     

Spatial instability of a viscous liquid sheet

In the present study, the spatial instability for a two‐dimensional viscous liquid sheet, which is thinning with time, has been analysed. The study includes the derivation of a spatial dispersion equation, numerical solutions for the growth rate of sinuous disturbances, and parameter sensitivity studies. For a given wave number, the growth rate of the disturbance is essentially a function of Weber number, Reynolds number, and gas/liquid density ratio. The analysis indicates that the cut‐off wave number of the disturbance becomes larger with an increase in Weber number or gas/liquid density ratio. Thus, the liquid sheet should produce finer drops. When the Reynolds number decreases, the higher viscosity has a greater damping effect on shorter waves than longer waves. This could explain that only large drops and ligaments were observed in past measurements for the disintegration of a very viscous sheet. The spatial instability results of the present study were also compared with the temporal theory. The importance of spatial analysis was found and demonstrated for the cases of low Weber numbers. The temporal theory underestimates growth rates when the Weber number is less than 100. The discrepancy between the two theories increases as the Weber number further decreases. Copyright © 2005 John Wiley & Sons, Ltd.     

Electro-spray of high viscous liquids for producing mono-sized spherical alginate beads

Alginate beads, often used for controlled release of enzymes and drugs, are usually produced by spraying sodium alginate liquid into a gelling agent using mechanical vibration nozzle or air jet. In this work an alternative method of electro-spray was employed to form droplets with desired size from a highly viscous sodium alginate solution using constant DC voltage. The droplets were then cured in a calcium chloride solution. The main objective was to produce mono-sized beads from such a highly viscous and non-Newtonian liquid (1000-5000 mPa s). The effects of nozzle diameter, flow rate and concentration of liquid on the size of the beads were investigated. Among the parameters studied, voltage had a pronounced effect on the size of beads as compared to flow rate zzle diameter and concentration of alginate liquid. The size of beads was reduced to a minimum value with increasing the voltage in the range of 0-10 kV. At the early stages of voltage increase (I.e. Up to about 4 kV), the rate of size reduction was relatively low, while the dripping mode dominated. However, in the middle part of the range of applied voltage, where the rate of size reduction was high (I.e. About 4-7 kV), an unstable transition occurred between dripping and jetting. At the end part of the range (I.e. 7-10 kV) jet mode of spray was observed. Increasing the height of fall of the droplets was found to improve the sphericity of the beads, because of the increased time of flight for the droplets. This was especially identifiable at higher concentrations of the alginate liquid (I.e. 3 w/v%)     

Coefficient inverse extremum problems for stationary heat and mass transfer equations

A technique is developed for analyzing coefficient inverse extremum problems for a stationary model of heat and mass transfer. The model consists of the Navier-Stokes equations and the convection-diffusion equations for temperature and the pollutant concentration that are nonlinearly related via buoyancy in the Boussinesq approximation and via convective heat and mass transfer. The inverse problems are stated as the minimization of certain cost functionals at weak solutions to the original boundary value problem. Their solvability is proved, and optimality systems describing the necessary optimality conditions are derived. An analysis of the latter is used to establish sufficient conditions ensuring the local uniqueness and stability of solutions to the inverse extremum problems for particular cost functionals.