Thermal scans

A thermal scan showed that the exotherm of the principal reaction can be significant if the system is neither controlled nor vented. From isothermal studies (i.e., experiments at constant temperature), time-to-maximum rate was determined which was comparable to that obtained from the DCS data. The larger scale data showed, not surprisingly, more rapid reactions at elevated temperatures. Thus, it was decided to use the DSC data at lower temperatures, and the larger scale test data at higher temperatures for hazard evaluation. 

Contact Non-contact Intermittent contact Lateral force Magnetic force Thermal scanning... 

With decreasing UV dose T(tan 6niax) also decreases. When free monomer is still present additional polymerization causes a stepwise increase of E and T(tan max) during a thermal scan. In the presence of sufficient monomer the tan 6 peak splits up into two peaks one at a constant and the other at a dose-dependent position, representing monomer and network, respectively. 

During the TSR process, the concentration of holes and electrons is determined by the balance between thermal emission and recapture by traps and capture by recombination centers, hi principle, integration of corresponding equations yields ric(t,T) and p t,T) for both isothermal current transients (ICTs) or during irreversible thermal scans. Obviously, the trapping parameters hsted together with the capture rates of carriers in recombination centers determine these concentrations. Measurement of the current density J = exp(/in c + yUpP) will provide trap-spectroscopic information. The experimental techniques employed in an attempt to perform trap level spectroscopy on this basis are known as Isothermal Current Transients (ICTs) [6], TSC [7]. 

One of the most commonly employed techniques is TSL, which monitors photons as a function of temperature during the thermal scan. These photons are the result of radiative transitions (luminescence) of free carriers, previously released from the traps, to recombination centers. 

The occurrence of TSL and TSC during a thermal scan of a previously excited material is probably the most direct evidence we have for the existence of electronic... 

The occurrence of TSDC during a thermal scan of a previously excited ( perturbed ) material is probably the most direct evidence we have for the existence of electronic trap levels in the band gap of these materials. The main attraction of TSDC and related techniques as experimental methods for the study of the trapping levels in high-resistance semiconductors was their apparent simplicity. A TSDC spectrum (for historical reasons, frequently referred to as a glow curve ) usually consists of a number of more or less resolved peaks in current versus temperature dependence. The latter, in most cases, may be attributed to a species of traps. 

Figure 3 (A) Cooling and (B) heating thermal scanning rheograms for a vaginal cream formulation. The dashed vertical line indicates the 38° C point in both plots. This is clearly the initiation temperature of the phase transition leading to increased apparent viscosity during both heating and cooling.

Fig. 5.7 Thermal scans of DPPC multil-amellar dispersions with various mole ratios of sulindac sulfide, sulindac, and sulindac sulfone (50 mM phosphate buffer, pH 7.0). (Reprinted from Fig. 6 of ref. 28 with permission from the American Chemical Society.)...

Slow cooling from the melt at 0.31°C/min results in only minor changes in the Cp curve. Annealing of a quenched sample near its Tg, on the other hand, produces noticeable differences in the thermal scan. 

Figure 3-35 Schematic Diagram of a Thermal Scanning Rigidity Monitor (Okechukwu et al., 1991).

Collection of Fe Mossbauer spectra with adequate signal/noise ratios requires a minimum of several hours under ideal conditions, extending to several days or weeks for experiments where conditions are less than optimal. This is most relevant for in situ experiments, because it limits the number of temperatures and/or pressures at which spectra can be collected. One technique that avoids this limitation is thermal scanning (e.g. Nolle et al. 1983), although the information provided is generally limited to only the phase transformation temperature. 

Nolle G, Ullrich H, Muller JB, Hesse J (1983) A microprocessor controlled spectrometer for thermal scan Mossbauer spectroscopy. Nucl Instr Meth Phys Res 207 459-463 Nomura K, UjiMra Y, Vertes A (1996) Apphcations of conversion electron Mossbauer spectrometry (GEMS). J Radioanal Nucl Chem 202 103-199... 

H-NMR Thermal Scanning Methods for Studying Oil Shale Pyrolysis... 

This paper reports on the use of -H NMR thermal scanning for studying the pyrolysis of oil shales. 

The temperature dependencies of these parameters reveal chemical and physical transformations that occur in the nature of the kerogen materials and the pyrolysis products. Examples of -H NMR thermal scanning of Australian oil shales are presented which illustrate this method of 1h NMR thermal analysis. 

The analysis of the 1-H NMR thermal scan data has been in three parts ... 

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