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[en] A radio frequency induced helium plasma (RFIHP) detector was designed and tested as a sensor for volatile chlorinated compounds. The RFIHP detector uses a critical orifice air inlet and an RF-excited sub-atmospheric pressure helium plasma to excite the ambient air sample. The excitation source is coupled to a fiber-optic cable and associated collection optics to monitor the emission intensity of the 837.6-nm emission line of chlorine. The RFIHP detector demonstrated linearity from 0 to 500 ppMv carbon tetrachloride with a correlation coefficient of 0.996 and excellent reproducibility. The detection limit for carbon tetrachloride in air was 5 ppMv. Fluorinated compounds can also be readily analyzed by changing the analytical wavelength to 739.9 nm. 10 refs., 9 figs
[en] The γ-radiation degradation of trace amounts (70-440 ppb) of trichloroethylene and tetrachloroethylene in drinking water has been investigated. The doses necessary to reduce the pollutant concentration to 1 ppb are in the order of 1kGy. (Author)
[en] The effect of Organo-Chlorine Compounds (OCC) on the radiation structuring of SKN-40 was investigated in filled model systems with 5 mass. h. of ZnO.The content of gel was determined at various dosages of OCC after irradiation with doses from 5 to 40 MRad. With increasing dosages of OCC, it takes part in the formation of rubber. After radiation exposure, the optimal conditions for the content of gel systems are 62-65%, and the activity in the processes of radiation structuring of OCC is located in the same row that was composed of the composition of the heating. The effective concentration of cross-links at optimal dosages of OCC (n'e 10''-''1''9, cm''-''3) in the optimum vulcanization constitute model systems with HCCP-5,3, adduct 1-5,3, adduct 2-6,3, adduct 3-6,5. In the presence of OCC, the optimal dose of radiation is reduced, so they can be considered as sensitizers of radiation structuring. Thus, it was found that the investigated OCC are effective structuring agents for SKN-40 both during heating and exposure to λ irradiation.
[en] The cross sections for dissociative attachment in the chlorosilanes and chloromethanes for electrons in the energy range 0.2--5.0 eV have been measured. In addition, measurements of the total electron scattering cross sections of the chloromethanes in the 0.2--12.0 eV range are reported. It is observed that dissociative attachment is much more probable in the chloromethanes than the chlorosilanes. This is explained by quantum mechanical calculations which reveal qualitative differences in the nature of the electron--molecule complex for the silanes as compared to the methanes
[en] Reaction of recoil 38Cl atoms with o-dichlorobenzene in the presence of carbon tetrachloride or iodine has been studied by using radio-high performance liquid chromatography. The major products were detected by a 4-channel-wavelengths spectrophotometric detector. The radioactivity of 38Cl compounds including minor products was measured with a NaI(Tl) scintillation detector. The main products found were 38Cl labeled HCl/Cl2, CHCl3, CCl4, o-, p-, m-C6H6Cl2 and polymer,, whereas only miner products such as HCl/CR2, C2,Cl6, C6H3Cl3, and polymer were found in the radio-chromatogram. The reaction mechanisms of recoil 38Cl atom are briefly described. (author) 9 refs.; 5 figs.; 3 tabs
[en] The stereochemistry of high energy chlorine-for-chlorine substitution was studied in gaseous and condensed phase 2(S)-chloropropionyl chloride and 2(R)-chloropropionyl chloride. Greater than 80% inversion of configuration was observed at the chiral center for both high energy 38Cl and /sup 34m/Cl substitution. Net retention is observed in gaseous 2(S)-chloro-4-methylvaleryl chloride where steric hindrance to backside attack is enhanced relative to 2(S)-chloropropionyl chloride. Condensed state data suggest caged radical recombination reactions. 2 tables
[en] The technique of pulse radiolysis was used to study the reactions of the hydrated electron and H atom in aqueous media with platinum(II) amine complex ions; chloro(diethylenetriamine)platinum(II), chloro(1,1,7,7-tetraethyldiethylenetriamine)platinum(II) and bis(ethylenediamine)platinum(II). The second-order rate constants for these reactions are near 1 x 1010dm3mol-1s-1, and the products absorb in the region of 240 to 450 nm. A comparison of the spectral and kinetic properties of the transients indicates that the esub(aq)sup(-) and H atom reaction products are different. The reactions of Cl2- with these complexes and with PtCl42- occur rapidly (second-order rate constants greater than 1 x 108dm3mol-1s-1) to yield transients absorbing strongly in the region of 230 to 400 nm. Very similar products are formed through the reactions of trans-dichlorobis(ethylenediamine)platinum(IV) ion with esub(aq)sup(-), H atom, methanol and isopropanol radicals; the associated rate constants range from 6.9 to 108dm3mol-1s-1 for methanol radical to 6.6 x 1010dm3mol-1s-1 for esub(aq)sup(-). Evidence is presented to show that these transients are platinum(III) species. Their possible structures and substitutional labilities are discussed. (author)
[en] Current pesticide registration guidelines call for short-term testing of plants; long-term effects on vegetative parts and reproduction remain untested. The aims of our study were to determine level of recovery and recovery times for plants exposed to the sulfonylurea herbicide chlorimuron ethyl using data collected from single species, dose–response greenhouse experiments. The nine terrestrial and eight wetland species tested showed variable levels of recovery and recovery timeframes. Many species (six terrestrial and five wetland) were vegetatively stunted at sublethal doses and were reproductively impaired. Full recovery did not occur at all doses and maximum recovery times varied from 3 to 15 weeks in this controlled environment. In a complex community, affected species may be displaced by tolerant species, through interspecific competition, before they fully recover. It is plausible that individual populations could be diminished or eliminated through reduced seedbank inputs (annuals and perennials) and asexual reproduction (perennials). - Highlights: ► Native terrestrial and wetland plants were used to assess the risks of herbicide drift. ► Vegetative and reproductive health endpoints were evaluated over time. ► Recovery rates were found to be both species and dose dependant. ► Reproductive recovery does not always equal vegetative recovery. ► Susceptible species may be displaced by resilient or resistant species. - Capsule: This study serves to bridge the gap between simplified short-term greenhouse tests and effects of herbicides on recovery of non-target plant species after sublethal exposures.