Temperature indication

Fig. XVII-1. Adsorption of N2 on rutile temperatures indicated are in degrees Kelvin. (a) Low-pressure region (b) high-pressure region. (From Ref. 1.).

For a fixed nucleophile the rate constant of each compound at 50 C Cdiffercni temperatures indicated) was divided by the following values of 2-chlorothia20le (k in unless otherwise indicated) ... 

The heating phase is used to take a molecular system smoothly from lower temperatures, indicative of a static initial (possibly optimized) structure, to the temperature T at which it is desired to perform the molecular dynamics simulation. The run phase then constitutes a simulation at temperature T. If the heating has been done carefully, it may be possible to skip the equilibration phase... 

Brix hydrometer is graduated so that the number of degrees is identical with the percentage by weight of cane sugar and is used at the temperature indicated on the hydrometer. 

The table below gives the weight in grams X 10 of 1 mL of air at 760 mm of mercury pressure and at the temperature indicated. Density in grams per milliliter is the same as the specific gravity referred to water at 4°C as unity. To convert to density referred to air at 70°F as unity, divide the values below by 12,00,... 

Fig. 2.24 Adsorption isotherms of argon at 78 K on Spheron-6 carbon black, heated to various temperatures indicated in °C on each isotherm. (After Polley, Schaeffer and Smith. )...

Figure 4.17 Experimental stress relaxation moduli of polystyrene measured over about two orders of magnitude in time at the temperatures indicated. [Reprinted with permission from H. Fujita and K. Ninomiya, J. Polym. Sci. 24 233 (1957).]...

Figure 10.8 Light-scattering data plotted to give slope-intercept values which can be interpreted in terms of M and B. (a) Polystyrene in methyl ethyl ketone. [From B. A. Brice, M. Halwer, and R. Speiser,/. Opt. Soc. Am. 40 768 (1950), used with permission.] (b) Polystyrene in cyclohexane at temperatures indicated. Units of ordinates are given in Example 10.4. [Reprinted with permission from W. R. Krigbaum and D. K. Carpenter,7. Phys. Chem. 59 1166 (1955), copyright 1955 by the American Chemical Society.]...

Mechanical Properties. Table 2 shows the physical properties of Teflon PEA (22,23). At 20—25°C the mechanical properties of PEA, EEP, and PTEE are similar differences between PEA and EEP become significant as the temperature is increased. The latter should not be used above 200°C, whereas PEA can be used up to 260°C. Tests at Hquid nitrogen temperature indicate that PEA performs well in cryogenic appHcations (Table 3). 

The rates and chemiluminescent intensities of atom-transfer reactions are proportional to the concentrations of the reactants, but the intensity is inversely proportional to the concentration of inert gas present. The latter quenches the excited state through coUision with an efficiency dependent on the stmcture of the inert gas. Chemiluminescence Qc increases with temperature, indicating that excitation has a higher activation energy than the ground state... 

Cuprous iodomercurate [13876-85-2] Cu2Hgl4, is a bright red water-insoluble compound prepared by precipitation from a solution of K Hgl with cuprous chloride. It is used in temperature-indicating paints because it reversibly changes color to brown at 70°C (see Chromogenic materials). 

Calcium Pyrophosphates. As is typical of the pyrophosphate salts of multiple-charged or heavy-metal ions, the calcium pyrophosphates are extremely insoluble ia water. Calcium pyrophosphate exists ia three polymorphic modifications, each of which is metastable at room temperature. These are formed progressively upon thermal dehydration of calcium hydrogen phosphate dihydrate as shown below. Conversion temperatures indicated are those obtained from thermal analyses (22,23). The presence of impurities and actual processing conditions can change these values considerably, as is tme of commercial manufacture. 

Results obtained at high temperatures indicate that the solubihties of the crystalline modifications of sihca are in the order tridymite > cristobahte > quartz, an order that parallels to some extent the chemical reactivity of these forms. Lower values for solubihty of crystalline as compared to amorphous sihca are consistent with the free-energy differences between them. 

The subject of thermochromism in organic and polymeric compounds has been reviewed in some depth previously (8,16,18), and these expansive overviews should be used by readers with deeper and more particular interest in the subject. Many more examples can be found in the reviews that further illustrate the pattern of association between thermochromism and molecular restmcturing of one kind or another. The specific assignment of stmctures is still Open to debate in many cases, and there are still not many actual commercial uses for these or any of the other thermally reversible materials discussed herein. Temperature indicators have been mentioned, though perhaps as much or more for irreversible materials. 

MiscelEneous. Small quantities of cobalt compounds are used in the production of electronic devices such as thermistors, varistors, piezoelectrics (qv), and solar collectors. Cobalt salts are useful indicators for humidity. The blue anhydrous form becomes pink (hydrated) on exposure to high humidity. Cobalt pyridine thiocyanate is a useful temperature indicating salt. A conductive paste for painting on ceramics and glass is composed of cobalt oxide (62). 

Dilute solutions and 1 atm unless otherwise noted use Di iJT = constant to estimate effect of temperature ° indicates that reference gives effect of concentration. 

These steels are intended for use at liigh temperatures however, they may have low ductility and/or low impact properties at room temperature after being used above the temperature indicated by the single bar (I). 

After use above the temperature indicated by a single bar (I), use at a lower temperahire shall be based on the stress values allowed for the annealed condition of the material. 

It is recommended that the motor should have separate terminal boxes for the main supply and for the accessories such as space heaters, embedded teinpertiture detectors, bearing temperature indicators and moisture detector terminals, etc. In LT motors, however, if it is not possible to provide a separate terminal box for these accessories, the main terminal box may be adequately spaced to segregate the.se terminals from the main terminals within the box. 

For ihe proleeiion of series reactors, w hen used t)ii large installations, and are oil cooled, a Buchholz relay may be provided for oil temperature indication once any other proieciion deemed necessary... 

In what way would you expect the setting and hardening reactions in cement paste to change with temperature Indicate the practical significance of your result. 

They include the combustion chamber, gas burners, burner controls, and exit temperature indicator. Usual exit temperatures for the destruction of most organic materials are in the range of 650°-825°C, with retention times at the elevated temperature of 0.3-0.5 sec. 

A typical lubrication oil system is shown in Figure 15-1. Oil is stored in a reservoir to feed the pumps and is then cooled, filtered, distributed to the end users, and returned to the reservoir. The reservoir can be heated for startup purposes and is provided with local temperature indication, a high-tempera-ture alarm and high/low level alarm in the control room, a sight glass, and a controlled dry nitrogen purge blanket to minimize moisture intake. 

It is interesting to note that these crystalline materials do not dissolve in tetrahydrofuran or cyclohexanone at room temperature, indicating that PVC is too weak a proton donor to overcome extensive crystallisation. Crystalline PVC has a greater tensile strength and creep resistance than conventional polymer. It is, however, brittle, and whilst most conventional impact modifiers appear ineffective, EVA polymers are said to be quite useful. Plasticised compounds may also be prepared although mixing temperatures of up to 190°C are necessary. 

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