Effect of UV-irradiance

The effects of UV irradiation to enhance the degradation of aged Pu(IV) polymer in HClOi. Depolymerization under dark conditions for each experiment is shown by a data point directly above the last light sample point (4). 

Abollino et al. [690] compared cathodic stripping voltammetry and graphite furnace AAS in determination of cadmium, copper, iron, manganese, nickel, and zinc in seawater. The effects of UV irradiation, acidification, and online sample preconcentration were studied. 

The p53 protein is central to a control function that imderlies progress in the cell cycle when DNA damage or other faults in the cell cycle are present. If cells are exposed to damage such as UV irradiation, an increase in the concentration of p53 protein is observed and the p53 protein is activated. One of the signals that has been identified as leading to activation of the p53 protein is a DNA strand break. Conditions that favor a strand break are the effect of UV irradiation, incomplete repair processes or a pause in DNA replication due to a damaged DNA template. 

The transient radical, CHr C(CH3) CH2, has not yet been observed. However, it has been shown that the evolution of CO and CHzO gas are the main radiation-chemical products from PMMA [48, 49], and C=C double bond forms during the radiolysis of PMMA [50], The effect of UV-irradiation mentioned previously also supports the reaction path of (38) and (39). Since the acyl-type radical is quantitatively converted to the propagating-type radical as the side-chain radical is, it is reasonable to assume that the above transient radical is the common intermediate for the two reactions the radical conversions to the propagating-type radical from the side-chain radical and from the acyl-type radical. The reaction mechanism involving the acyl-type radical will be expressed as... 

An interesting additional effect of UV irradiation on some semiconductor surfaces is the increase in the extent and rate of adsorption of gases. As an example, in the absence of UV irradiation, SO2 adsorbs on the a-Fe203 surface with a very low sticking coefficient. However, formation of electron-hole pairs by UV irradiation results in the creation of Fe2+ defect sites, enhancing... 

Irradiation crosslinking of PVC-U, carried out using electron beam, has shown a marked increase in glass transition temperature in the presence of a triacrylate, with minimal thermal degradation (216). Electron beam irradiation has also been investigated on a PVC-P wire coating formulation in the presence of different reactive monomers (185). Flame retardancy has also been improved with the incorporation of appropriate flame retardants (118). The effect of UV irradiation on formulations, incorporating iron chloride or cobalt chloride, has also been studied (67). 

Alkaline elution techniques In one type of method the cellular DNA is denatured in alkali followed by hydroxyapatite chromatography which separates single stranded DNA from double stranded DNA (Britten and Kohne, 1965). The production of single-stranded DNA is related to the number of SSBs in the DNA which act as unwinding points. As an example the effects of UV-irradiation on the integrity of mammalian cell DNA has been studied using this approach (Collins, 1977). Initially mammalian cells in culture are extensively labelled with [3H]thymidine (see Adams, this series, 1980). 

Raman spectroscopy was used to characterise densely-assembled Ti02 nanorods (diameters 150-200 nm).37 High-temperature Raman spectra of nanocrystalline Ti02 powders (25-1200°C) were used to monitor temperature-dependent effects on the samples.38 The effects of UV irradiation on the structure of sol-gel Ti02 films were followed by IR and Raman spectroscopy.39... 

G. Dohler (1996). Effect of UV irradiance on utilization of inorganic nitrogen by the Antarctic diatom Odontella weissflogii (Janisch) grunow. Bot. Acta, 109,35-42. 

Work by Maher et al. (51) on the effect of UV irradiation on human fibroblasts has shown that cell survival is lower and mutation rates higher upon UV irradiation in DNA excision-repair-incompetent cells than in normal cells. Normal cells were also observed to survive a usually lethal and mutagenic UV dose upon being held in confluence (nondividing) for a period of time prior to assessment of survival and mutation rate. These results suggest that this recovery was a result of the increased time given DNA repair mechanisms to remove thymine dimers prior to replication. These workers have also demonstrated that the actual number of DNA alkylation sites removed from the DNA of benzo(a)pyrene exposed fibroblasts by repair mechanisms is directly related to cell survival (52). 

Figure 3.104 Effect of UV irradiation in a QUV Weather-o-meter on the tensile properties of PVF, PVDF and ETFE (a) tensile modulus b) tensile strength (c) break elongationJ i...

Caibamate insecticides in water are subject to photo decomposition under the effects of ultraviolet radiation, the rate of which is related with pH, tending to increase with increasing pH. The first effect of UV irradiation is the cleavage of the ester bond, resulting in the phenol or the heterocyclic enol of the carbamate ester [9]. The studies concerning the half-life for photo decomposition process suggest that the light source characteristics influence the extent of the process. 

Fig. 6a, b. Effect of UV irradiation on bacterial production in the Gulf of Mexico [127]. Note the strong inhibition of bacterial production in the photic zone (0-125 m), where dissolved organic carbon (DOC) is high. In deeper water, where DOC is low, production is enhanced. The enhancement and inhibition of bacterial production are plotted as percent departures from the production measured in non-irradiated controls (vertical broken line)... 

Aouida, S., Saadoun, M. and Boujmil, M. E Effect of UV irradiation on the structural and optical features of porous silicon Application in silicon solar cells , (2004) Appl. Surf. Sci. 238,193-8. 

On the other hand, there are also studies showing the effects of UV irradiation on the change of migration characteristics of the matrix polymer, (i.e., effect on the migration of phthalate ester plasticisers from clear PET water bottles [87]), and some data are provided on the effects of ionising irradiation on polymer additives, monomers and polymers themselves in general [88]. 

Kolomiets, Y.N. Pervukhin, V.V., Effect of UV irradiation on detection of cocaine hydrochloride and crack vapors by IMIS and API-MS methods, Talanta 2009, 78,... 

Kaczmarek, H., Podgorski, A. J. Photochem. Photobiol. A The effect of UV-irradiation on poly(vinyl alcohol) composites with montmorillonite. Journal of Photochemistry and Photobiology. Journal of Photochemistry and Photobiology. Chemi. 191, 209-215 (2007)... 

Tsuji, H., Echizen, Y. and Nishimura, Y, Y. (2006) Enzymatic degradation of poly(L-lactic acid) Effects of UV irradiation. Journal of Polymers and the Environment, 14, 239-248. 

The orb-web is irradiated outdoors by ultraviolet (UV) rays. It is interesting to ask from the aging point of view how UV-irradiation affects spider silks at different stages of life and to study the effects of UV-irradiation. However, there have been no reports on the effects of UV rays upon draglines. 

Zhang, D., Dougal, S.M., and Yeganeh, M.S. (2000) Effects of UV irradiation and plasma treatment on a polystyrene surface studied by IR-visible sum frequency generation spectroscopy. Langmuir, 16, 4528-4532. 

Fechine and co-workers [36] studied the effect of UV irradiation on the structure of oriented films of PET, noting that chain scission, while not immediately changing the crystallinity of the sample, could lead to increased crystallinity if the films were heated because long chains in the amorphous regions which had been broken could now rearrange into a crystalline phase. 

---