The Structural Temperature

The concept of a structural temperature of electrolyte solutions was introduced long ago by Bernal and Fowler (1933). This stmctural temperature , Tstr, of an electrolyte solution at a given temperature T is that temperature, at which pure water would have effectively the same inner structure. They suggested that could be estimated from viscosity, x-ray diffraction, Raman spectroscopy, etc., but did not provide explicit methods and values. 

Bunzl (1967) used the shift of the 0.97 pm band of water in the infrared spectra of aqueous tetraalkylammonium bromides at 10-70 °C to establish their structural temperatures. The differences AT = T — Tstr for 1 m solutions at 35 °C are 11-14 K, not showing a clear dependence on the nature of the cation, ranging from (CH3)4N+ to (C4H9)4N+. The temperature dependence of the differences does show cation size 

Luck (1965,1975) used infrared spectroscopy to obtain the fraction of non-bonded OH groups at the wavelength of the peak of free OH in water at 200 °C. He then derived values of Tst ranging from 10-85 °C for salt solutions at T from 20-65 °C, but shown only in diagrams. Leyendekkers (1983) used these data at 25 °C to obtain the A r = Tsti - T values shown as Ar(IR) in Table 3.4. When the structure breaking properties of a salt dominate over the structure making ones AT is positive but is negative otherwise. 

3 Effects of Ions on Water Structure and Vice Versa 

The concept of structural temperature of aqueous electrolytes has more or less been abandoned in recent years. 

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Test Measurements. A 20-gage Chromel-Alumel thermocouple was welded to the center of the exterior surface of each test panel and three were freely suspended 5 feet above the surface of the oil in separate sections within the structure. Temperature measurements were recorded by the two General Electric potentiometer recorders, connected by means of rotary selector switches. As the switches were rotated,... 

In contrast to urea itself, its N-methylated derivatives enhance water-water interactions, i.e. lower the structural temperature hexa-methylene tetramine produces similar marked effects (Barone et al., 1968). Glycine and /3-alanine appear to be structure breakers (Devine and Lowe, 1971) according to their effect on the viscosity of water (Herskovitz and Kelly, 1973). The viscosities and diffusion properties of urea solutions show striking changes as the concentration increases (MacDonald and Guerrera, 1970). 

Another way of reducing the temperature of vulcanization of rubber binder is regulation of the micro structure and viscosity of the dienic oligomer. We know that liquid dienic rubbers are the macromolecules of oligomers withl,4-cis-, 1,4-trans-, and 1,2-vinyl- links with viscosities from 0.4 up to 10 Pac. It was found experimentally that production of cold-cured RubCon is possible if the content of 1,4-cis- links in a macromolecule of rubber is more than 65%, and the viscosity of the polymer is more than 17 Pa c. Increasing the viscosity of rubber up to 7 Pa c leads to lowering of the structurization temperature from 125°C to 60°C. 

From a kinetic viewpoint, salinity action on the water solution structure is similar to the action of temperature and pressure. This was a reason to compare the effect of temperature and pressure, on the one hand, and salinity, on the other, on the mobility of solution components, and therefore, on its structure. In this connection John Desmond Bernal (1901-1971) and Ralph Howard Fowler (1889-1944) introduced the concept of structural temperature of the solution. Under their definition, structural temperature of a given solution is equal to the temperatme of pine water with the solution s structural properties (viscosity, density, refraction, etc.). Ions with positive hydration work as lowering of temperature and have structural temperature below the solution temperature ions with negative hydration - as increase of temperature, and their structural temperature is higher than the solution s temperature. Non-polar compounds occupy plentiful space, thereby lowering the intensity of translation motion of the water molecules, lowering the structural temperature of the solution, as in a case of positive hydration. 

The structural temperature of the solution, with Ns moles of s at temperature T, is defined as the temperature T for which we have the equality... 

Note that the concept of the structural temperature, though using the concept of structure, does not define the concept of the structure of water. The idea underlying this definition is qualitatively clear. It is intuitively clear that, however we choose to define the structure of water, this quantity must be a monotonically decreasing function of the temperature. Therefore, the changes in the structure can be detected on a corresponding temperature scale. ... 

The safety of ship lock is related to the people s life and property in the downstream, so that the ship lock structure health monitoring is a critical issue to avoid its damages. The stress state of ship lock structure is dependent on its type and structural complexity. In addition, the temperature and construction methods have a great influence on the structural quality. Thus, strengthening the structural temperature and stress-strain monitoring during the construction plays a significant role to ensure the construction quality of the ship lock. 

The detailed analysis of the structure, temperature behavior and phase as weUl as relaxational transitions of two representatives of thermotropic LC copolyesters with a statistical sequence of monomers in chains shows the strong dependence of their phase composition on the chemical stmcture of monomeric units. One of the most important factors appears to be the geometrical dimensions of the monomeric groups, from which the chain of copolymer is constructed jfrom, and the presence (or absence) of relatively large side substituents. 

Abstract This chapter presents a description of the interstellar medium. It starts with a summary of the interstellar medium stmcture and how the various phases are related to each other. The emphasis is put on molecular clouds, and on their densest regions, the dense cores, which are the birth place of stars. The evolution of matter during the star formation process and its observable consequences, especially in term of chemical composition is presented. The next section is dedicated to the constituents of the interstellar medium, with separate presentations of the gas species and the dust grains. Methods used by astronomers to derive useful information on the structure, temperature, ionization rate of interstellar environments as well as magnetic fields are briefly described. The last part of the chapter presents the telescopes and their instruments used for studying the interstellar medium across the electromagnetic spectrum. 

Finally, Figure 12-27 provides a sensitivity study showing the effect on power of moving all the negative reactivity feedback into the fuel temperature reactivity coefticient. Because the fuel temperature responds faster than the structural temperature, there is less power undershoot, and power more rapidly approaches 50% power. 

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