Heating experiments

Ogawa, T., and Ikawa, K., High Temperature Heating Experiments on Unirradiated ZrC-Coated Fuel Particles, J. Nucl. Mater., 99(l) 85-93 (July 1981)... 

In this context, the treatment of the AT-phosphinyl iminoethers 15 with methyl iodide furnish the P-methyl phosphonium iodides, which by heating experience an 0-dealkylation, reminiscent of the Arbuzov reaction, for yielding the iV-acylphosphazenes 16 [45] (Scheme 16). 

In slow heating experiments, slow removal of the volatiles from the bed of biomass allows for secondary reactions between... 

Last but not least of the liquid calorimetric media are aqueous solutions used in the hydrolysis of simple and complex fluorides. Stepwise replacement of F by OH occurs, and mixed products are not unusual. Thus the BFj ion hydrolyzes to species BF (OH)l and one has to ensure that the same product composition is formed in the auxiliary heat experiments (99). The problem is accentuated when polynuclear species form, as the equilibration can be slow. The inconsistencies in the heats of alkaline hydrolysis of MoF6 and WFe found by various authors and of the enthalpy of SbF5—derived by assuming SbF5 and Sb205 dissolved in 10 M HF produced the same species in solution—illustrate the difficulties. It is as well to confirm enthalpies of higher valent fluorides obtained by hydrolysis by alternative nonaqueous methods, especially since uncertainty in the Afl (Fderived enthalpy. The advantage of hydrolysis methods, apart from the simplicity of technique, is that the heats are small and one can tolerate... 

Figure 11. Schematic representation of a laser heating experiment in the DAC. The IR laser beam is directed onto the absorbing sample immersed in a compression medium acting also as thermal insulator. The thermal emission of the sample is employed for the temperature measurement, while the local pressure is obtained by the ruby fluorescence technique (see next section).

Figure 12. Typical procedure to measure the sample temperature in a laser heating experiment. The experimental emission spectrum (thick line) htted according to Eq. (1) (thin line) gives a sample temperature of 3000 K.

Heating experiments on P2ilm amphiboles (cummingtonite) show transition to the C2lm polymorph at low T (50 to 100 °C Prewitt et ah, 1970 Sueno et ah, 1972) in analogy to the behavior of pigeonitic pyroxenes (P2jlc), which show transition to the form C2/c (cf. section 5.4.3). Phase stability limits are markedly conditioned by the chemistry of the system and, particularly, by the partial pres-... 

The original specific heat experiments on BaPb xB Og by Methfessel et al (60) immediately raised the prospect that an unusual mechanism was operative in this newly found system. Their finding of no heat capacity anomaly at Tc could actually have a number of possible interpretations, including an impurity phase giving rise to superconductivity, a non-phonon mechanism, or some new form of conductivity. 

The carriers of anomalous Ne-E (two forms of which were now known) and Xe-S were quickly identified. Neon-E(H), which is released at temperatures above 1200 °C in stepped heating experiments, and Xe-S were found to be carried in presolar silicon carbide (Tang and Anders, 1988). Neon-E(L), which is released below 900 °C, was found to be carried by presolar graphite (Amari et al., 1990). Once these presolar compounds were shown to be present in meteorites, studies were carried out to identify all of the different types of meteorites that carry presolar grains. Concentrated searches for other presolar phases were also initiated, and many new types of presolar grains have been found. This work is just beginning, however, and we cannot yet account for the majority of the presolar components that must have been present in the Sun s parent molecular cloud. 

Bowden Singh (Ref 7) studied the effect of size of primary expl crystals on their expl decompn when heated. Experiments with Cd azide, alpha LA Ag azide showed that crystals having a thickness greater than a critical value always exploded when kept at a fixed temp. Crystals smaller in thickness than the critical value decompd slowly at that same temp... 

The interactive effect of the polymer and the solvent can be easily demonstrated in a very simple but crude microwave heating experiment, where no consideration is given... 

Measurements on cooling are often difficult to carry out, so that heating experiments are usually substituted. These may lead, however, to hysteresis phenomena if heating and cooling are not carried out at similar rates, or if annealing occurred close to the glass transition temperature before analysis. Figure 5 shows typical apparent heat... 

The purpose of the experiments described below was to study the effect of the pretreatment of the substrate and of the pH of the silane solution on the structure of the film. Only thin films, as described in the previous section for SAAPS on zinc, were prepared and analyzed. Heating experiments were not performed, but will be reported in a forthcoming paper. All spectra were run under conditions of high mass resolution. 

Table 1. Heating experiments on shell material olNautilus pompilius at temperature of 150° to 250 °C under dry conditions and in the presence of water. Amino acids in residues/1000 oxygen and carbon isotopes expressed as 8-deviation relative to a belemnite standard... 

Heating experiments on Nautilus shell material (see page 10) indicates a retardation in the rates of thermal decomposition of mineral and organic phase. This has been attributed to the development of a topochemical boundary at the contact protein-mineral. X-ray diffraction analysis gives no evidence for structural alteration of the original aragonite during the thermal treatment up to 200 °C. 

Figure 7. A and B. Map and topographic cross-sectional view of sample locations from Shuster et al. s (2005) study of incision of the Kliniklini valley, Coast Mountains, British Columbia. C. Model thermal histories for each sample, derived from 4He/3He evolution of step-heating experiments on proton-irradiated samples, and bulk grain (U-Th)/He dates. Samples from the valley bottom require rapid cooling, from 80 °C to surface temperatures, at 1.8 0.2 Ma, and samples from higher elevations require thermal histories with progressively smaller extents of cooling (beginning at 1.8 Ma) with elevation. The highest sample (TEKI-23) was at surface temperature before the 1.8 Ma cooling event experienced by the other samples. Collectively, these data are interpreted to be the result of -2 km incision at 1.8 Ma. After Shuster et al. (2005).

For the constant-temperature heating experiments different product water contents were obtained by storage of freeze-dried carrots over saturated salt solutions (17). 

The equipment heat transfer coefficient determined from a cooling (or heating) experiment performed in the industrial reactor containing a known amount of a compound with known physical properties. 

The electrocyclic cyclization was investigated by heating the sample in o-dichlorobenzene (o-DCB), both under conventional heating conditions and under microwave irradiation in a dedicated monomode apparatus. It was found that the microwave-assisted cyclization provided slightly elevated yields at the lower reaction temperature of 150 °C, in comparison with the conventional heating experiment conducted at 180 °C (Scheme 14). The intermediate isoquinoline was then converted to the final alkaloid using known synthetic manipulations to complete the synthesis. 

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