Parameters physico-mechanical

Table 1 presents as an example the experimental dependences of kinetic parameters of the reaction, structural parameters of the network and some physico-mechanical characteristics on the molar fraction of monofunctional molecules in the reactant mixture, which is specific of FTD in the given case. As can be seen, the presence of monofunctional molecules, even in minor amounts (only 3-10%), exerts a strong influence on the kinetic and physico-mechanical parameters. 

Table 1. Dependence of the kinetic parameters of the reaction, the structural parameters of the network and the physico-mechanical properties of polyurethane elastomers on the molar fraction of OH groups in the monofunctional reagent21...

The fibres produced according to the above procedure, which resulted in the data presented in Table 11.3, were further subjected to heat treatment. These fibres were exposed to 473 K for approximately 2h, and again the physico-mechanical properties were investigated (Table 11.4). It can be seen that an important decrease of the mechanical parameters is obtained however, this reduction is not due to the fact that these fibres are metallised, because the unmetallised PAN fibres showed a similar shift in physico-mechanical properties. 

Meanwhile, based on another study reported by A. B. Moustafa et al [2], sandy, silty, loamy, clayey, and sandy-loamy soils were impregnated with three types of binding materials, namely, urea formaldehyde, phenol formaldehyde, and sodium silicate. Ammonium chloride, hexamethylene tetramine, and sodium fluorosilicate were used as catalysts for the previously mentioned substances, respectively. Some physico-mechanical tests were carried out with the stabilized soils and different parameters affecting the strength, absorption and durability of stabilized soils were studied [3]. 

The use of the PES mono and multifilament yams allowed the ensuring of the proper level of the physico-mechanical characteristics, resistance to the action of the chmnical agents as part of the liquids, serums and human body blood, maintenance of the product biofunctional properties during implant process, thus contributing to the avoidance of new surgical operations with traumatic effects on human body and psychic. All these elements determined the achieving of a complex product with dimensional stability dominant conferred by the link type and the structure parameters as well as by using... 

Table 1. Physico-mechanical parameters of rock masses. 

All parameters used this paper are from measured data of physico-mechanical properties of soil samples (Table 1). 

Extending the a-olefin to RCH = CH2, where R is a C2—Cg alkyl group, one obtains copolymers with superior processibility and physical properties, including high creep resistance and low cold flow [30c,d]. Many other cyclic and polycyclic dienes have been copolymerized with ethylene, propylene, and various a-olefins using conventional Ziegler-Natta catalysts. Of these, compounds (34-40) yield products displaying attractive physico-mechanical parameters [30e-l]. 

The performance of a product where adhesion plays a role is determined both by its adhesive and cohesive properties. In the case of silicones, the promotion of adhesion and cohesion follows different mechanisms [37]. In this context, adhesion promotion deals with the bonding of a silicone phase to the substrate and reinforcement of the interphase region formed at the silicone-substrate interphase. The thickness and clear definition of this interphase is not well known, and in fact depends on many parameters including the surface physico-chemistry of... 

The monograph is devoted to scientific basis of semiconductor chemical sensors technique. Its attention is focused at the usage of semiconductor sensors in the precision physico-chemical studies. The monograph expounds physical and chemical basis underlying the semiconductor sensor method, discusses the mechanism of processes occurring under interaction of gas with semiconductor adsorbent surface, leading to changed electrophysical parameters of the latter. 

In this chapter the roles of various physico-chemical parameters in the interaction between globular proteins, e.g. enzymes, and soil minerals have been discussed semi-quantitatively. Knowledge of the mechanism of that interaction provides a basis to manipulate biological activity in soils. 

The original model regarding surface intermediates is a system of ordinary differential equations. It corresponds to the detailed mechanism under an assumption that the surface diffusion factor can be neglected. Physico-chemical status of the QSSA is based on the presence of the small parameter, i.e. the total amount of the surface active sites is small in comparison with the total amount of gas molecules. Mathematically, the QSSA is a zero-order approximation of the original (singularly perturbed) system of differential equations by the system of the algebraic equations (see in detail Yablonskii et al., 1991). Then, in our analysis... 

Huang, C.H., et al. 1985. Mechanism of nasal absorption of drugs. I Physico-chemical parameters influencing the rate of in situ nasal absorption of drugs in rats. J Pharm Sci 74 608. 

For linear mechanisms we have obtained structurized forms of steady-state kinetic equations (Chap. 4). These forms make possible a rapid derivation of steady-state kinetic equations on the basis of a reaction scheme without laborious intermediate calculations. The advantage of these forms is, however, not so much in the simplicity of derivation as in the fact that, on their basis, various physico-chemical conclusions can be drawn, in particular those concerning the relation between the characteristics of detailed mechanisms and the observable kinetic parameters. An interesting and important property of the structurized forms is that they vividly show in what way a complex chemical reaction is assembled from simple ones. Thus, for a single-route linear mechanism, the numerator of a steady-state kinetic equation always corresponds to the kinetic law of the overall reaction as if it were simple and obeyed the law of mass action. This type of numerator is absolutely independent of the number of steps (a thousand, a million) involved in a single-route mechanism. The denominator, however, characterizes the "non-elementary character accounting for the retardation of the complex catalytic reaction by the initial substances and products. 

Since about 15 years, with the advent of more and more powerfull computers and appropriate softwares, it is possible to develop also atomistic models for the diffusion of small penetrants in polymeric matrices. In principle the development of this computational approach starts from very elementary physico-chemical data - called also first-principles - on the penetrant polymer system. The dimensions of the atoms, the interatomic distances and molecular chain angles, the potential fields acting on the atoms and molecules and other local parameters are used to generate a polymer structure, to insert the penetrant molecules in its free-volumes and then to simulate the motion of these penetrant molecules in the polymer matrix. Determining the size and rate of these motions makes it possible to calculate the diffusion coefficient and characterize the diffusional mechanism. 

Foam films are usually used as a model in the study of various physicochemical processes, such as thinning, expansion and contraction of films, formation of black spots, film rupture, molecular interactions in films. Thus, it is possible to model not only the properties of a foam but also the processes undergoing in it. These studies allow to clarify the mechanism of these processes and to derive quantitative dependences for foams, O/W type emulsions and foamed emulsions, which in fact are closely related by properties to foams. Furthermore, a number of theoretical and practical problems of colloid chemistry, molecular physics, biophysics and biochemistry can also be solved. Several physico-technical parameters, such as pressure drop, volumetric flow rate (foam rotameter) and rate of gas diffusion through the film, are based on the measurement of some of the foam film parameters. For instance, Dewar [1] has used foam films in acoustic measurements. The study of the shape and tension of foam bubble films, in particular of bubbles floating at a liquid surface, provides information that is used in designing pneumatic constructions [2], Given bellow are the most important foam properties that determine their practical application. The processes of foam flotation of suspensions, ion flotation, foam accumulation and foam separation of soluble surfactants as well as the treatment of waste waters polluted by various substances (soluble and insoluble), are based on the difference in the compositions of the initial foaming solution and the liquid phase in the foam. Due ro this difference it is possible to accelerate some reactions (foam catalysis) and to shift the chemical equilibrium of some reactions in the foam. The low heat... 

Effects of Capillary Number, Capillary Pressure, and the Porous Medium. Since the mechanisms of leave-behind, snap-off, lamella division and coalescence have been observed in several types of porous media, it may be supposed that they all play roles in the various combinations of oil-bearing rocks and types of dispersion-based mobility control (35,37,39-41). However, the relative importance of these mechanisms depends on the porous medium and other physico-chemical conditions. Hence, it is important to understand quantitatively how the various mechanisms depend on capillary number, capillary pressure, interfacial properties, and other parameters. 

In a next step, the part of the isotherm for pressures smaller than p/po = 10 was fitted with various equations. As only a limited number of data points were available (in some cases as few as three points) a reasonable fitting could be achieved with various equations. However, to be accepted, these equations had to obey two supplementary conditions general applicability and physico-chemical consistency. To answer to the first condition the same equation (possibly with different parameters) had to be applicable to all adsorbents, and preferably to both argon and nitrogen (the carbon dioxide data being discarded). The second condition is rather straightforward if the first part of the isotherm really depicts a different adsorption mechanism, the equation that describes this part should represent a physico-chemical adsorption phenomenon. 

In the present paper are presented the results of the investigation of their physico-chemical and mechanical properties, chemical stability, as well as the data on water and sulphur dioxide sorption as a function of their concentration in the gas phase. Influence of different parameters on the efficiency of absorption of SO2 from air by COg and HCOj foimofthe fibres has been tested. These parameters are gas flow rate, concentration, and air humidity. The optimal condition for regeneration has been established. It has been shown that the fibrous ion-exchange materials made of strong-base fibres are highly efficient means for removal of SO2 from air. 

The effect of different physico-chemical parameters, namely pH, ionic strength, presence of a competing cation and cation concentration, has been studied in order to understand complexation mechanisms. 

Understanding Claus Catalyst Deactivation Mechanisms Optimization of Alumina Using Physico-chemical Parameters... 

A significant amount of work has demonstrated the feasibility and the interest of reversed micelles for the separation of proteins and for the enhancement or inhibition of specific reactions. The number of micellar systems presently available and studied in the presence of proteins is still limited. An effort should be made to increase the number of surfactants used as well as the set of proteins assayed and to characterize the molecular mechanism of solubilization and the microstructure of the laden organic phases in various systems, since they determine the efficiency and selectivity of the separation and are essential to understand the phenomena of bio-activity loss or preservation. As the features of extraction depend on many parameters, particular attention should be paid to controlling all of them in each phase. Simplified thermodynamic models begin to be developed for the representation of partition of simple ions and proteins between aqueous and micellar phases. Relevant experiments and more complete data sets on distribution of salts, cosurfactants, should promote further developments in modelling in relation with current investigations on electrolytes, polymers and proteins. This work could be connected with distribution studies achieved in related areas as microemulsions for oil recovery or supercritical extraction (74). In addition, the contribution of physico-chemical experiments should be taken into account to evaluate the size and structure of the micelles. 

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