Irradiation time, effect

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. 

PL spectra of Mn-doped ZnS nanoparticles optically annealai in air (a) and in vacuum (b) are shown in Fig. 2. For Mn-doped ZnS nanoparticles, the PL band is seen at around 585mn. When Mn-doped ZnS nanoparticles were annealed in air, PL intensity is increased more significantly with UV irradiation time compared with ones ann ed in vacuum. PL spectra of Pr-doped ZnS nanoparticles axe shown in Fig. 3. The broad emission at 430 nm corresponds to the emission of the undoped ZnS nanoparticles. The other peak is relaftrii to the Pr-related complexes. The effect of the optical aimealing in air is more notable than in vacuum on the enhancement of luminescent intensity. The incre e of PL intensity for Pr-doped ZnS nanoparticles in mr is more rapid than undoped or Mn-doped ZnS nanoparticles. 

Effect of microwave irradiation time on conversion and product yield during i iigDin decoinposiuoii... 

It is possible to distinguish between direct and indirect nOes from their kinetic behavior. The direct nOes grow immediately upon irradiation of the neighboring nucleus, with a first-order rate constant, and their kinetics depend initially only on the intemuclear distance r" indirect nOes are observable only after a certain time lag. We can thus suppress or enhance the indirect nOe s (e.g., at He) by short or long irradiations, respectively, of Ha- a long irradiation time of Ha allows the buildup of indirect negative nOe at He, while a short irradiation time of Ha allows only the direct positive nOe effects of Ha on He to be recorded. 

For the sonochemical mineralization of reactive dye Cl Reactive Black 5 with 20, 279 and 817 kHz irradiation, the discoloration and radical formation both are directly dependent upon ultrasonic frequency, acoustic power and irradiation time and indirectly on the number of free radicals thus generated, as their suppression decreased the discoloration rate due to radical scavenging effect. Although ultrasound alone is capable of decolorizing Reactive Black 5 but inefficient in mineralization as only 50% degradation was observed after 6 h of ultrasonic irradiation [121]. The sonochemical... 

The effect of microwave irradiation on the catalytic hydrogenation, dehydrogenation, and hydrogenolysis of cydohexene was studied by Wolf et al. [81]. Optimum conditions for benzene formation were a hydrogen flow, N-CaNi5 catalyst, atmospheric pressure, and 70 s irradiation time. Cydohexane was the main product when the irradiation time was 20 s, or in a batch/static system. 

Figure 11.4. Effect of UV-C irradiation time (0, 1, 3, 5, 10 min) on (I) ascorbic acid (mg/100 g FW), (II) p-carotene (mg/100 g FW), and (III) total phenols (mg/100 g FW) of fresh-cut mango (cv. Tommy Atkins) stored at 5°C. Bars show the final values after treatments. Different letters on top of the bars indicate statistical differences among treatments (p < 0.05).

Increased ring strain in the C-4 ( = 2) and C-5 (n — 3) products may be a reason for lower yields (and longer irradiation times). The effect of strain on cyclizations is well-documented outside of cycloaromatization chemistry, as well. For example, annealing of a cyclopentene ring leads to a decrease in the cyclization rate and an inversion of the 5-exo/6-endo selectivity for all three patterns shown in Fig. 22. 

Fig. 12 (a) Image of PMAA-protected fluorescent silver clusters prepared with increasing initial ratio Ag+ MAA from 0.5 1 to 12 1 and equal irradiation time, (b) Absorption spectra of the same samples as in (a), (c) Variation of absorption maxima of some of the samples in (a) with molar ratio. Black arrows indicate how the absorption band shifts to the blue with the addition of extra polymer to a fluorescent cluster solution explaining the transfer effect of silver clusters among PMAA chains [20]... 

An RP-HPLC method was employed for the investigation of the effect of solar light and TiOz on decomposition of the textile dye Reactive blue 4 (RB4). The chemical structure of Reactive blue 4 is shown in Fig. 3.51. RP-HPLC measurements were performed in an ODS column. Chromatographic profiles demonstrating the effect of irradiation time and the... 

Fig. 5.11. Effect of irradiation time on the ultrasonic degradation of aqueous native dextran [2% w/v 60 W 30°C 20 kHz).

Fig. 5.22. Effect of intensity on degradation of polystyrene in toluene initial R.M.M. = 300 000 irradiation time 90 min.

Theoretical Extrapolation Can Natural Radiation be Simulated by a Billion Times More Intense Artificial One This is acommon question in all dating method utilizing natural radiation effects. The irradiation time t in hour is less than one-billionth of the age T, while the dose rate of artificial irradiation, D is a billion times higher than natural one D. 

This idea was probed by irradiating two samples of CN-DHA with the same concentration and volume in a one pump pulse and a two pump pulses experiment [7] In the one pulse experiment the photoconversion to CN-VHF-trans was triggered at 340 nm under similar conditions as in the two color time resolved measurements. The irradiation time t was chosen such that a significant amount of CN-VHF-trans was converted. In the two pulses experiment an additional pulse at 530 nm which was delayed by 25 ps from the first pulse excited the transient CN-VHF-cis for the same time t. After the irradiation much less CN-VHF-trans is found in the two pulse experiment than in the one pulse experiment (Fig. 4). We conclude that a significant amount of CN-DHA was regenerated from the transient species by the second pulse. Photodegradation and thermal activation by the 530 nm pulses were eliminated as possible reasons for the observed effect. 

Fig. 5. Pressure effect in the photooxidation of 1-butene by nitrogen dioxide (1 mm. NOj, 1 mm. 1-butene, varying amounts of N. Irradiation time 30 min. 25 2°C.).

Figure 3. Effect of initial ferrous ion concentration on linear portion of absorbance-irradiation time (dose) relationship...

In mixed solutions of ferro- and ferri-cytochrome c cross saturation effects could be observed by this technique. For example when the methyl resonance at +23.2 ppm of ferricytochrome c (Fig. 19) was irradiated, saturation effects were also observed in the methyl resonance of ferro-cytochrome c at +3.3 ppm (Fig. 27). This cross relaxation was shown to arise from an exchange of protein molecules, and hence also the saturated spins, between the ferrous and ferric oxidation states. The life-time in either oxidation state then has to be comparable to or shorter than the longitudinal spin relaxation time of the observed protons. Besides... 

For irradiation times of J short with respect to the relaxation time of / the NOE extent is independent of the relaxation time of the nucleus and provides a direct measurement of time required to saturate signal J is not negligible compared with t, the response of the system is not linear [18]. The truncated NOE is independent of paramagnetism as it does not depend on p/, which contains the electron spin vector S in the R[m term, and only depends on gkj), which does not contain S. If then the steady state NOE is reached, the value of p/ can also be obtained. This is the correct way to measure p/ of a nucleus, provided saturation of J can be considered instantaneous. In general, measurements at short t values minimize spin diffusion effects. In fact, in the presence of short saturation times, the transfer of saturation affects mainly the nuclei directly coupled to the one whose signal is saturated. Secondary NOEs have no time to build substantially. As already said, this is more true in paramagnetic systems, the larger the R[m contribution to p/. 

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