Transformation Active temperature

Reaction decomposition or transformation of Temperature of equal reaction velocity (absolute) Energy of activation (calories per gram molecule)... 

Shape-memory alloys (e.g. Cu-Zn-Al, Fe-Ni-Al, Ti-Ni alloys) are already in use in biomedical applications such as cardiovascular stents, guidewires and orthodontic wires. The shape-memory effect of these materials is based on a martensitic phase transformation. Shape memory alloys, such as nickel-titanium, are used to provide increased protection against sources of (extreme) heat. A shape-memory alloy possesses different properties below and above the temperature at which it is activated. Below this temperature, the shape of the alloy is easily deformed due to its flexible structure. At the activation temperature, the alloy can be changed by applying a force, but the structure resists this deformation and returns back to its initial shape. The activation temperature is a function of the ratio of nickel to titanium in the alloy. In contrast with Ni-Ti, copper-zinc alloys are capable of a two-way activation, and therefore a reversible variation of the shape is possible, which is a necessary condition for protection purposes in textiles used to resist changeable weather conditions. 

Activation of Ru(III)hexammine in CO atmosphere At activation temperatures below 373 K, Ru(III)hexammine in the presence of CO is transformed into a Ru(II)pentammine complex. The identification of this complex is based on earlier work (7, 8) and the information is summarized in Table 4. This transformation is almost quantitative and the material formed shows already a low WGS-activity. Chemically, this transformation can be visualized as follows (8) ... 

At still higher activation temperatures, the Ru(II)pentammine carbonyl is transformed into a Ru(I)triscarbonyl, the characteristics of which are shown in Table 5a. It should be noted that the volumetric data shown, have been corrected for a simultaneously occurring WGS-activity using the method described earlier (8). This complex shows a characteristic triplet of bands in infrared... 

Very many oxidation tests for transformer oils have been used at one time or another. Most of these tests are of a similar pattern The oil is heated and subjected to oxidation by either air or oxygen and usually in the presence of a metallic catalyst, almost invariably copper, which is the main active metal in transformer construction. Temperatures and duration have varied within wide limits, from 95 to 150°C (203-302°F) and from 14 to 672 h. 

Since this early discovery there has been considerable appreciation for the role of the soil microbial community in pesticide transformations. In some cases the role of microorganisms has been stressed by comparison of degradation rates in natural and sterilized systems (32), while in others researchers have chosen to use isolation of pesticide-degrading microorganisms from soil sis evidence of microbial involvement (33). It has also been recognized that environmental conditions that influence microbial activity (temperature, moisture,...) affect the microbial degradation of pesticides in soil (34). The importance of microbial involvement is demonstrated by the many reviews of pesticide/microbe interactions that have appeared (35-41). 

Thermal analysis of glasses using the differential scanning calorimeter has become a major technique for determination of the effect of temperature on glasses. The speed of measurement, combined with the small sample size and ease of sample preparation, leads to the use of the DSC for many measurements. Determination of the glass transformation and Active temperatures, crystallization temperatures and kinetics, and estimation of nucleation and viscosity curves have become routine using this instrument. 

Den et aL, 1971). Experiments in our own laboratory on normal and Py-BHK cells obtained from Dr. Walter Eckhart of the Salk Institute did not show a difference in the Gms content of these cell lines. The quantity of hematoside and level of sialyltransferase activity were similar in both cell lines and not affected by cell density in culture (Table IV). Further studies in another polyoma transformant as well as two lines transformed by temperature-sensitive mutants of the virus gave similar results. 

Sintering is a thermal process through which a loose mass of particles is transformed to a coherent body. It usually takes place at a temperature equal to two-thirds the melting point, or ca 800—1000°C for nickel. The sintered nickel stmcture without active material is called a plaque and it can be prepared by either dry or wet processes (see Metallurgy, powder). 

The high temperature tx-fi transformation of shock-activated silicon nitride powder has been investigated at temperatures of 1600 and 1700°C [84B01]. 

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