Characteristic temperature isobaric

The most important phase for the membranes of living cells is the lamellar fluid pliase, In this phase, the conformational order of the fatty acid chains is low and the lipid lateral mobility is substantial. The lempcrature at which the liquid crystal phase alters to gel phase and, as a result, the fatty acid chains obtain a high degree of conformational order with low mobility, is called the main transition temperature (Tm). This temperature is considered as an important physicochemical characteristic at isobaric conditions, indicating that the system exists in equilibrium and the AG at the Tm point is zero (AG=0). 

Kovacs, A. J., and Hutchinson, J. M., Isobaric thermal behavior of glasses during uniform cooling and heating dependence of the characteristic temperatures on the relative contribntions... 

The prediction of miscibility requires knowledge of the parameters T" (the characteristic temperature), p (the characteristic pressure) and V (the characteristic specific volume) of the corresponding equation of state which can be calculated from the density, thermal expansivity and isothermal compressibility. The isobaric thermal expansivity and the isothermal compressibility can be determined experimentally from p-V-Tmeasurements where these values can be calculated from V T) and V(p)j. The characteristic temperature T is a measure of the interaction energy per mer, V is the densely packed mer volume so that p is defined as the interaction energy per... 

Young and O Connell [140] introduced a characteristic temperature T = 0.4/ p i.e., a temperature that is inversely proportional to the isobaric expansibility p. The temperatures T for molten alkali metal halides, hydroxides and nitrates were listed. For the alkali metal halides T = (1.15 0.04)rm, but different ratios were obtained for the nitrates (1.56 0.11) and the two hydroxides tested (1.99 0.003). With a set of characteristic molar volumes V listed for these salts a universal expression over the range 0.5 < TIT <1.2 was obtained for the reduced molar volumes ... 

As a matter of fact there is a striking parallelism between both systems, H2-ZnO and O2-NiO. Thus the adsorption isobar (60 mm. Hg) corresponding to the amount of oxygen taken up after 100 min. by NiO between room temperature and 700°C. has the characteristic shape of hydrogen adsorption lobars a curve with a flat minimum between 200° and 300°C. (37). 

Duration of a cycle of HHP operation is defined as time required for reaction hydrogenation/dehydrogenation in pair hydride system. This time determines heat capacity of HHP. Duration of a cycle depends on kinetics of hydrogenation reactions, a heat transfer between the heated up and cooling environment, heat conductivities of hydride beds. Rates of reactions are proportional to a difference of dynamic pressure of hydrogen in sorbers of HHP and to constants of chemical reaction of hydrogenation. The relation of dynamic pressure is adjusted by characteristics of a heat emission in beds of metal hydride particles (the heat emission of a hydride bed depends on its effective specific heat conductivity) and connected to total factor of a heat transfer of system a sorber-heat exchanger. The modified constant of speed, as function of temperature in isobaric process [1], can characterize kinetics of sorption reactions. In HHP it is not sense to use hydrides with a low kinetics of reactions. The basic condition of an acceptability of hydride for HHP is a condition of forward rate of chemical reactions in relation to rate of a heat transmission. 

Supercritical fluid extraction (SFE) is a suitable process for many separation problems. The regeneration of the supercritical fluid is as important as the extraction step itself Therefore this paper presents a method to do this in a more isobaric way than the customary pressure reduction regeneration. For the example of soil remediation we have investigated the activated carbon regeneration of supercritical carbon dioxide loaded with the low-volatile polycyclic aromatic hydrocarbon (PAH) pyrene. Characteristics of supercritical fluid extraction for soil remediation are elevated temperatures and pressures up to 370 K and 300 bar. For this reason adsorption isotherms of pyrene on activated carbon up to these conditions are measured first. Subsequently this method is used to regenerate carbon dioxide in a closed solvent cycle plant with a 4 1 extractor. An economic analysis using these results indicate that the soil remediation costs will decrease for about 20 - 30 % by means of an activated carbon adsorber. 

Light water was superheated in tubes of optieal quartz or pyrex glass. Experiments were made in the pressure ranges 0.1-3.3 MPa (H2O) and 0.1-2.1 MPa (D2O) at nueleation rates 3-10 -5 10 s m. On experimental isobars (Fig. 1) there are no flattened seetions and sections with curvature of different sign characteristic of other liquids. The maximum value of an experimental temperature of superheat in light water at atmospheric pressure is 521.4 K, which is 55 K lower than the theoretical value. For heavy water these values are 531.4 K and 44 K, respectively. With increasing pressure, discrepancies between theory and experiment decrease, which is mainly connected with a decrease in the dimensions of the metastable region. 

Adsorption capacity (or loading) is probably the most important characteristic of an adsorbent. More detail is provided in Section 14.3.2. The loading is the amount of adsorbate taken up by the adsorbent, per unit mass (or volume) of the adsorbent, and it depends on the fluid-phase concentration, the temperature, and other conditions (especially the initial condition of the adsorbent). Typically, adsorption capacity data are plotted as isotherms (loading of adsorbate on the adsorbent versus fluid-phase adsorbate concentration at constant temperature), isosteres, isobars, and others mentioned later. Examples are shown in Figures 14.1 through 14.3. Adsorption capacity is of paramount importance to the capital cost, because it sets the amount of adsorbent required and also the volume of the adsorber vessels the costs of both are significant if not dominant. When comparing alternate adsorbents, it is fair to express their capacity on a per unit volume basis, since that fixes... 

Historically, the MNSJ equations (6.33) and (6.34) were evaluated using x-ray data on the crystalline specific volume. Thus, the isobars of linear polyethylene (LPE), poly(viny lidene fluoride) (PVDF), and poly(chlorotrifluoroethylene) (PCIF3), and an isotherm at atmospheric pressure of LPE were fitted to the theoretical dependencies [Simha and Jain, 1978 Jain and Simha, 1979a,b]. The fitting requires five characteristic parameters P T V, c/s, and 60, the last two having universal values. While in the melt, the macromolecular external degrees of freedom 3c/s 1 in the crystalline polymers, c/s l. For different crystalline species the characteristic reduced quantum temperature value adopted at 0 (K) is o = (hpvo/ksT ) 0.022, where... 

The shape of characteristic isobaric T[x) and isothermal p x) sections can be deduced from the three-dimensional phase diagrams in the upper row of Fig. 4 p x) sections are also given in Figs. 15c and d (for details see the Refs. [2-6,10,12]). Systems exhibiting lower critical solution temperatures (LCST) or closed loops in isobaric T x) diagrams have also been studied extensively at pressures even up to about 3 GPa [1,3,70,71,81,82,85]. 

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