Irradiation times

Specimens used in tests were sections of cables with PVC outer coating. PVC was plasticized with DOF softener. The materials considered were exposed to the radiation and thermal aging. The samples have been irradiated at room temperature by hard gamma rays with 10 rad/sec dose power. A number of samples had been heated for long different times at 90°C. Besides a special specimens were cut out from outer coating for test on tensile machine like "Instron". The total doses of irradiation, times of heating and elongations at break obtained with "Instron" are listed in Table 1. 

It has been estimated that using available neutron intensities such as 10 neutrons/(cm -s) concentrations of B from 10—30 lg/g of tumor with a tumor cell to normal cell selectivity of at least five are necessary for BNCT to be practical. Hence the challenge of BNCT ties in the development of practical means for the selective deUvery of approximately 10 B atoms to each tumor cell for effective therapy using short neutron irradiation times. Derivatives of B-enriched /oj o-borane anions and carboranes appear to be especially suitable for BNCT because of their high concentration of B and favorable hydrolytic stabiUties under physiological conditions. 

Small scale test runs prior to preparative irradiation experiments may be carried out in tubes which are either taped to the lamp housings (immersion wells) depicted in Figures 13-1 and 13-2 or placed in turntable reactors ( merry-go-rounds ). These arrangements permit the simultaneous irradiation of several samples, but only a fraction of the available light emission is used. In Figure 13-4 a simple reactor is shown which focusses almost all the emitted light into one sample which can be scaled up also to semi-preparative volumes. In this way the necessary irradiation time can be reduced sharply. 

Figure 2 Plot of carbonyl index versus irradiation time in i-PP films at 0.2 wt% concentration of stabilizers.

Figure 4 Changes in (a) carbonyl index and (b) hydroxyl index versus irradiation time for polystyrene films. O-con-trol -2,4-DHBP -2H-4MBP -2H-4BB X-DHBP-F A-HMBP-F and D-HBBP-F.

Ultraviolet spectra has been recorded between 200-400 nm to see the increase in number of chromophore by recording optical density (OD) (at 280 nm) versus irradiation time Fig. 7, 8, and 9. 

Figure 9 Optical density (280 nm) versus irradiation time (hours) for PMMA films. -2,4-DHB -2H-4BB -DHBP-F A-2H-4MB A-HMBP-F and B-HBBP-F.

Figure 11 (a) Tensile strength (TS), and (b) elongation at break (EB) versus irradiation time for PMMA films X-control ... 

Photo-induced grafting onto wood cellulose with several vinyl monomers using phenyl acetophenone and benzophenone derivatives as photosensitizers has been reported [72]. A fast increase in grafting was observed for short irradiation times, whereas longer ones resulted in a decreased percent grafting. 

The same synthesis could be carried out in an ordinary flask using one or two sunlamps or sunlight, but the irradiation time would necessarily be much longer. 

A solution of the 2-azido ester or amide (ca. 2 g) in a mixture of MeOII (95 mL) and sodium-dried THF (95 mL) was photolyzed under N2 in a Hanovia photochemical reactor (110-W medium-pressure Hg lamp with a Pyrex filter). The reaction was monitored by observing the rate of disappearance of the absorption band (Nf) at 2140 cm 1 (irradiation times of 3-5 h were generally required). When the reaction was complete the solvent was removed in vacuo and the brown residual oil chromatographed on alumina [petroleum ether (bp 60-803C)/benzene 7 3]. Further elution with benzene followed by removal of the solvent gave the product (the esters as pale yellow oils, the amides as crystalline solids), which were further purified by vacuum distillation or by recrysiallization. 

Practicable yields of 5-substituted 2-methoxy-3//-azepines 94 can be obtained by photolysis of aryl azides 56 bearing an electron-withdrawing group para to the azide function, although irradiation times tend to be longer and, in general, yields lower than with the corresponding 2-substituted azides.197... 

Based on the properties of ionic hquids in high-temperature microwave-enhanced reactions, the authors chose l-butyl-3-methylimidazolium tetraflu-orophosphate ([bmimjPFe) as the suitable ionic liquid (Scheme 23). The addition of 0.15 mmol of [bmimjPFe to a reaction in 2.0 mL of DCF was found to increase the reaction rate dramatically and a set-temperature of 190 °C was reached in a mere 1 min, while the reactions programmed at 190 °C, in the absence of the ionic liquid, reached only 170 °C in 10 min. The reactions were finished in a mere 18-25 min of irradiation time, including the hydrolysis of the sensitive imidoyl chloride moiety with water. The formed bis-lactams were isolated in good yield and purity. 

Kinetic studies of the cryophotoclustering process are now in progress. Preliminary results indicate that, under certain conditions, the rates of formation of diatomic and triatomic silver may usefully be approximated by simple, second-order kinetics 149). A simple analysis predicts that the slope of a log[Ag ]/[Ag] versus log ) plot, where Ag and Ag represent absorbances, and t represents the irradiation time, should have a value close to 1.0 for n = 2, and 2.0 for n =3 149). A typical plot is shown in Fig. 17. The observed slopes, 0.9/1.0 and 2.1/2.2, support the Agj and Agj assignments for the run indicated in Fig. 18, and correlate exactly with earlier assignments based on Ag-atom concentration experiments. 

Fig. 17. Kinetic plots showing a linear dependence on irradiation time (305 nm) of the absorbance ratios and AgJ " (O) and a linear dependence on...

Fig. 18. UV-visible spectra of Agi,j.s/Ar mixtures (Ag Ar = 1 1(F) at 10-12K. Note the growth of Agj and Ag, clusters and loss of Ag atoms as a result of 305 nm, Ag atom excitation. Spectra A, B, and C represent irradiation times of 0,1, and 4 min, respectively (149).

While Funk et al. did not use temperatures above 30 °C during the irradiation times discussed above, Sistovaris combined UV irradiation with simultaneous heating (70 °C, 2 h) of the TLC layers [24]. After this treatment nomifensine and its metabolites appeared as intense yellow fluorescent ehromatogram zones on a dark background. 

Of these radioactive atoms, a fraction Fj are produced in a specified form the value of Fj may depend on the irradiation temperature, T, the y-flux, and consequently on the irradiation time, t. This fraction may be altered by subsequent thermal treatment and by a variety of spurious reactions, to an extent expressible as T, y. ..). Thus, the activity of a given species, i, can be expressed as... 

Fig. 2 shows the temperature as a function of irradiation time of Cu based material under microwave irradiation. CuO reached 792 K, whereas La2Cu04, CuTa20e and Cu-MOR gave only 325, 299 and 312 K, respectively. The performances of the perovskite type oxides were not very significant compared to the expectation from the paper reported by Will et al. [5]. This is probably because we used a single mode microwave oven whereas Will et al. employed multi-mode one. The multi-mode microwave oven is sometimes not very sensitive to sample s physical properties, such as electronic conductivity, crystal sizes. From the results by electric fixmace heating in Fig. 1, at least 400 K is necessary for NH3 removal. So, CuO was employed in the further experiments although other materials still reserve the possibility as active catalysts when we employ a multi-mode microwave oven. 

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