Study of the reactions of OH with HCl, HBr, and HI between 298 K and 460 K.

The reactions between OH radicals and hydrogen halides (HCl, HBr, HI) have been studied between 298 and 460 K by using a discharge flow-electron paramagnetic resonance technique. The rate constants were found to be (298 K) = (7.9 ± 1.

Atmospheric Lifetimes of Halogenated Hydrocarbons: Improved Estimations from an Analysis of Modeling Results.

Detailed results of computer modeling of halocarbon removal rates from the atmosphere are analyzed to find simple correlations useful for improving estimations of the atmospheric lifetimes of industrial chemicals based on the rate constants for their reactions with OH and O(D) and their UV absorption spectra. Ths analysis is limited to relatively long-lived chemicals that are well mixed in the troposphere.

Deriving Global OH Abundance and Atmospheric Lifetimes for Long-Lived Gases: A Search for CHCCl Alternatives.

An accurate estimate of global hydroxyl radical (OH) abundance is important for projections of air quality, climate, and stratospheric ozone recovery. As the atmospheric mixing ratios of methyl chloroform (CHCCl) (MCF), the commonly used OH reference gas, approaches zero, it is important to find alternative approaches to infer atmospheric OH abundance and variability. The lack of global bottom-up emission inventories is the primary obstacle in choosing a MCF alternative.

Photochemical Properties of CH═CH-CFCl-CFBr (4-Bromo-3-chloro-3,4,4-trifluoro-1-butene) and CH-O-CH(CF) (Methyl Hexafluoroisopropyl Ether): OH Reaction Rate Constants and UV and IR Absorption Spectra.

Rate constants for the reactions of hydroxyl radicals (OH) with 1,1,1,3,3,3-hexafluoroisopropyl methyl ether (CH-O-CH(CF)) and 4-bromo-3-chloro-3,4,4-trifluoro-1-butene (CH═CH-CFCl-CFBr) have been measured over the temperature range 230-370 K to give the following Arrhenius expressions: k(T) = 7.69 × 10 × (T/298) × exp(+342/T), cm molecule s, and k(T) = (6.45 ± 0.

Photochemical properties of hydrofluoroethers CH3OCHF2, CH3OCF3, and CHF2OCH2CF3: reactivity toward OH, IR absorption cross sections, atmospheric lifetimes, and global warming potentials.

Rate constants for the gas phase reactions of OH radicals with three partially fluorinated ethers, CH3OCF3 (kHFE-143a), CH3OCHF2 (kHFE-152a), and CHF2OCH2CF3 (kHFE-245fa2), were measured using a discharge flow-electron paramagnetic resonance technique over the temperature range 298-460 K. The temperature dependences of the rate constants can be represented by the following expressions: kHFE-143a(T) = (1.10 ± 0.

Photochemical properties of trans-1-chloro-3,3,3-trifluoropropene (trans-CHCl═CHCF3): OH reaction rate constant, UV and IR absorption spectra, global warming potential, and ozone depletion potential.

Measurements of the rate constant for the gas-phase reactions of OH radicals with trans-1-chloro-3,3,3-trifluoropropene (trans-CHCl═CHCF3) were performed using a flash photolysis resonance-fluorescence technique over the temperature range 220-370 K. The reaction rate constant exhibits a noticeable curvature of the temperature dependence in the Arrhenius plot, which can be represented by the following expression: kt-CFP (220-370 K) = 1.025 × 10(-13) × (T/298)(2.

Photochemical properties of some Cl-containing halogenated alkanes.

Rate constants for the gas-phase reactions of OH radicals with three partially halogenated alkanes, CH3Cl (kMC), CHFClCFCl2 (k122a), and CH2FCFCl2 (k132c), were measured using a discharge flow-electron paramagnetic resonance technique over the temperature range from 298 to 460 K. The temperature dependences of the rate constants can be represented by the expressions kMC(298-460 K) = (3.09 ± 0.

Measurements of rate constants for the OH reactions with bromoform (CHBr3), CHBr2Cl, CHBrCl2, and epichlorohydrin (C3H5ClO).

Measurements of the rate constants for the gas phase reactions of OH radicals with bromoform (CHBr3) and epichlorohydrin (C3H5ClO) were performed using a flash photolysis resonance-fluorescence technique over the temperature range 230-370 K. The temperature dependences of the rate constants can be represented by the following expressions: kBF(230-370 K) = (9.94 ± 0.

High accuracy measurements of OH reaction rate constants and IR absorption spectra: substituted 2-propanols.

Rate constants for the gas phase reactions of OH radicals with 2-propanol and three fluorine substituted 2-propanols, (CH(3))(2)CHOH (k(0)), (CF(3))(2)CHOH (k(1)), (CF(3))(2)C(OH)CH(3) (k(2)), and (CF(3))(3)COH (k(3)), were measured using a flash photolysis resonance-fluorescence technique over the temperature range 220-370 K. The Arrhenius plots were found to exhibit noticeable curvature for all four reactions. The temperature dependences of the rate constants can be represented by the following expressions: k(0)(T) = 1.

High-accuracy measurements of OH(•) reaction rate constants and IR and UV absorption spectra: ethanol and partially fluorinated ethyl alcohols.

Rate constants for the gas phase reactions of OH(•) radicals with ethanol and three fluorinated ethyl alcohols, CH(3)CH(2)OH (k(0)), CH(2)FCH(2)OH (k(1)), CHF(2)CH(2)OH (k(2)), and CF(3)CH(2)OH (k(3)) were measured using a flash photolysis resonance-fluorescence technique over the temperature range 220 to 370 K. The Arrhenius plots were found to exhibit noticeable curvature for all four reactions. The temperature dependences of the rate constants can be represented by the following expressions over the indicated temperature intervals: k(0)(220-370 K) = 5.

Rate constants for the reactions between OH and perfluorinated alkenes.

The rate constants for the reactions of OH radicals with fully fluorinated alkenes containing different numbers of -CF(3) groups next to olefinic carbon, CF(2)═CF(2), CF(2)═CFCF(3), CF(3)CF═CFCF(3), and (CF(3))(2)C═CFC(2)F(5), were measured between 230 and 480 K using the flash photolysis resonance fluorescence technique to give the following expressions: k(C(2)F(4))(250-480 K) = 1.32 × 10(-12) × (T/298 K)(0.9) × exp(+600 K/T) cm(3) molecule(-1) s(-1), k(C(3)F(6))(230-480 K) = 9.

High-accuracy measurements of OH reaction rate constants and IR absorption spectra: CH2=CF-CF3 and trans-CHF=CH-CF3.

Rate constants for the gas phase reactions of OH radicals with two isomers of tetrafluoropropene, CH(2)=CF-CF(3) (k(1)) and trans-CHF=CH-CF(3) (k(2)); were measured using a flash photolysis resonance-fluorescence technique over the temperature range 220 to 370 K. The Arrhenius plots were found to exhibit a noticeable curvature. The temperature dependences of the rate constants are very weak and can be represented by the following expressions over the indicated temperature intervals: k(1)(220-298 K) = 1.

Rate constant for the reaction of OH with H2 between 200 and 480 K.

The rate constant for the reaction of OH radicals with molecular hydrogen was measured using the flash photolysis resonance-fluorescence technique over the temperature range of 200-479 K. The Arrhenius plot was found to exhibit a noticeable curvature. Careful examination of all possible systematic uncertainties indicates that this curvature is not due to experimental artifacts.

[The characteristics of the clinical picture of candidiasis of the skin and mucous membranes in patients with chronic dermatosis].

The author describes the clinical picture and course of candida infection of the skin and mucous membranes in 176 patients with chronic dermatoses (eczema, atopic dermatitis, psoriasis). Several patients (9%) showed torpid, atypical manifestations of candidosis, often masqueraded by other skin pathology. It was established that Candida infection is one of the causes of long-term, torpid course and increase of number of recurrences of the main dermatosis, development of a polymorphous clinical picture and mycogenous sensibilization.

[Secondary candidal infection in patients with chronic dermatoses].

Clinical and laboratory examinations of 250 patients with chronic dermatoses (eczema, neurodermatitis, psoriasis, pemphigus, etc.) have revealed secondary candidal involvement of the skin and mucosa in 121 (46.6%).

[Diagnosis of oil-induced folliculitis].

Clinical, electrophysiologic and immunologic study of 113 patients with oil folliculitis was carried out. High electric resistance of hair follicles was established along with some immunologic shifts, i.e.

[Stab wounds of the liver and injuries of the extrahepatic bile ducts and vessels and specific features of their surgical treatment].

The authors observed 24 patients with wounds of the liver and injuries of extrahepatic bile ducts and vessels. In 14 patients with stab-cut injuries of the liver catgut sutures were used, in 3 patients catgut sutures with suturing the portion of the greater omentum on the pedicle. The microsurgery technique was used in order to reestablish the integrity of the hepatic artery, portal vein and common bile duct.