Thermal detection

Thermography is a predictive maintenance technique that can be used to monitor the condition of plant machinery, structures and systems. It uses instrumentation designed to monitor the emission of infrared energy, i.e. temperature, to determine their operating condition. By detecting thermal anomalies, i.e. areas that are hotter or colder than they should be, an experienced surveyor can locate and define incipient problems within the plant. 

Positive ion FAB mass spectra obtained with a double focusing mass spectrometer produced abundant molecular ions ([M] +) of carotenes and xanthophyUs with minimal fragmentation and no detectable thermal decomposition. Fragmentation of the precursor ion was enhanced by collision-induced dissociation (CID) using helium gas. ... 

P.Y.17 is also frequently used in polyolefins, sometimes in the form of pigment preparations. Its heat stability in these media was said to be about 220 to 240°C, but must now, as a result of the detected thermal decomposition of diarylide yellow pigments in plastics, be limited to 200°C. This tendency to decompose excludes P.Y.17 from recommendation for use in polystyrene, in which the pigment largely dissolves under the processing conditions. The same is true for ABS. 

Using ion-exchange techniques, the selenato-species [ScCSeO )]" and [Sc(Se04)2] have been detected thermal decomposition of 802(8004)3,-5H2O gave SC2O3. 

The major concern is that the character of the sample is not changed in the injection port, the column, or the detector prior to its actual detection. Thermal decomposition, catalyzed or thermal reaction, and adsorption of part or all of the sample will contribute to error in the analysis. Problems such as these may be determined by using the chromatograph itself first to detect possible problems by unexpected results and then confirmation of the problem by variation of the actual operating parameters of the chromatograph. 

Madansky, L. and Rasetti, F. (1950). An attempt to detect thermal energy positrons. Phys. Rev. 79 397. 

Taylor and Morken extended the use of IR-thermography to the monitoring of the change in the heat of reaction on and in the surroundings of a bead carrying an active catalyst (Figure 5.4.4) [13]. In a search for acylation catalysts an encoded library of 3150 different potential nucleophilic catalysts was prepared by the split-and-mix procedure and tested for their acylation properties. The library beads were spread in a reaction solution of chloroform-ethanol-triethylamine-acetic anhydride, 40 6 6 3, and monitored with an IR camera. Whereas no detectable thermal... 

It is possible to detect thermally induced circumambulations in certain substituted homotropenylium ions. Hehre in his theoretical study (HF/STO-3G) of 11 suggested that the placement of methyl substituent at C(8) of the homotropenylium ions should reduce the barrier to the thermally induced circumambulation" . The correctness of this prediction was confirmed by Childs and Varadarajan who reported the generation of the deuterium labelled cation 67 and the measurement of the rate of deuterium scrambling associated with circumambulation of C(8) around the seven-membered ring (Scheme 24) 58 barrier for this circumambulation was found to be 14.5 kcalmoT. Scott and Brunsvold have also reported the occurrence of a circumambulation in a bridged homotropylium ion, 68 (Scheme 25). ... 

In this new technique,microwaves are used both to heat a material and to detect thermal transitions. 

Although there is no detectable thermal reaction between COF temperature [93], reaction occurs under UV irradiation at 35 C to give CF3OF (one of the few thermally stable compounds containing an oxygen-fluorine bond) in 80% yield [93] ... 

In conclusion, CRDS can successfully be applied to highly diluted, mono-dispersed gold clusters on amorphous silica in order to measure the evolution of the optical properties with size, detect thermal stabilities of the cluster, characterize the trapping centers and in the future to get structural information on the deposited clusters. 

In addition to DTA, other techniques used to detect thermal activity in PVC include differential scanning calorimetry, specific heat, thermal conductivity, and thermal diffusity. 

Differential thermal gas analysis Elemental analysis (pyrochrom) Evolved radiactive gas Flame ionization detection (Thermal Evolution Analysis)... 

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