Effect of formic acid on O + OH˙CHOH → HCOOH + HO reaction under tropospheric condition: kinetics of and isomers.

Formic acid (HCOOH) is one of the highly abundant acids in the troposphere. It is important in the formation of atmospheric aerosols and impacts the acidity of rainwater. In the present scenario, the model chemistry of HCOOH(FA) sources and sinks is poorly understood.

Photodissociation of CHBrCHBrC(O)Cl at 248 nm: probing Br as the primary fragment using cavity ring-down spectroscopy.

The photodissociation of 2,3-dibromopropionyl chloride (CHBrCHBrC(O)Cl, 2,3-DBPC) at 248 nm was carried out to study Br as the primary molecular product in the BΠ ← XΣ transition using cavity ring-down absorption spectroscopy. The rotational spectra ('' = 0-2) were acquired and assigned with the aid of spectral simulation. It is verified that the obtained Br fragment is attributed to the one-photon dissociation of 2,3-DBPC and is free from contributions of secondary reactions.

Effect of ammonia and water molecule on OH + CHOH reaction under tropospheric condition.

The rate coefficients for OH + CHOH and OH + CHOH (+ X) (X = NH, HO) reactions were calculated using microcanonical, and canonical variational transition state theory (CVT) between 200 and 400 K based on potential energy surface constructed using CCSD(T)//M06-2X/6-311++G(3df,3pd). The results show that OH + CHOH is dominated by the hydrogen atoms abstraction from CH position in both free and ammonia/water catalyzed ones. This result is in consistent with previous experimental and theoretical studies.

Cavity Ring-Down Absorption Spectroscopy: Optical Characterization of ICl Product in Photodissociation of CHICl at 248 nm.

Iodine monochloride (ICl) elimination from one-photon dissociation of CHICl at 248 nm is monitored by cavity ring-down absorption spectroscopy (CRDS). The spectrum of ICl is acquired in the transition of BΠ ← XΣ and is confirmed to result from a primary photodissociation, that is, CHICl + hν → CH + ICl. The vibrational population ratio is determined with the aid of spectral simulation to be 1:(0.

Catalytic effect of a single water molecule on the OH + CHNH reaction.

In recent work, there has been considerable speculation about the atmospheric reaction of methylenimine (CHNH), because this compound is highly reactive, soluble in water, and sticky, thus posing severe experimental challenges. In this work, we have revisited the kinetics of the OH + CHNH reaction assisted by a single water molecule. The potential energy surfaces (PESs) for the water-assisted OH + CHNH reaction were calculated using the CCSD(T)//BH&HLYP/aug-cc-pVTZ levels of theory.

Experimental and computational investigation on the gas phase reaction of ethyl formate with Cl atoms.

The rate coefficient for the gas-phase reaction of Cl atoms with ethyl formate was measured over the temperature range of 268-343 K using relative rate methods, with ethyl chloride as a reference compound. The temperature dependent relative rate coefficients for the ethyl formate + Cl reaction were measured, and the modified Arrhenius expression kethyl formate(268-343) = (2.54 ± 0.

Mechanism, kinetics and atmospheric fate of CF₃CH=CH₂, CF₃CF=CH₂, and CF₃CF=CF₂ by its reaction with OH-radicals: CVT/SCT/ISPE and hybrid meta-DFT methods.

The dual level direct dynamic study is carried out for the reactions of CF₃CH=CH₂, CF₃CF=CH₂ and CF₃CF=CF₂ with hydroxyl radicals. The dynamic calculations are performed using the variational transition state theory (VTST) with interpolated single-point energies (ISPE) method at M06-2X/MG3S//M06-2X/6-31+G(d,p) level of theory. All the possible reactions such as abstraction and addition-elimination pathways are explored for the title reactions.

Rate coefficients and reaction mechanism for the reaction of OH radicals with (E)-CF3CH═CHF, (Z)-CF3CH═CHF, (E)-CF3CF═CHF, and (Z)-CF3CF═CHF between 200 and 400 K: hybrid density functional theory and canonical variational transition state theory calculations.

The rate coefficients of ((E)-CF(3)CH═CHF, (Z)-CF(3)CH═CHF, (E)-CF(3)CF═CHF, and (Z)-CF(3)CF═CHF) + OH reactions were computed using M06-2X/6-31+G(d,p) theory in the temperature range of 200 and 400 K. The possible reaction mechanisms of the ((E)-CF(3)CH═CHF, (Z)-CF(3)CH═CHF, (E)-CF(3)CF═CHF, and (Z)-CF(3)CF═CHF) + OH reactions were examined. The rate coefficients for the addition and abstraction reactions were calculated using canonical variational transition state theory (CVT) and conventional transition state theory (CTST), respectively, and we concluded that abstraction reactions are negligible within the temperature range and addition reactions take the lead role.

Dihydrotestosterone is a determinant of calcaneal bone mineral density in men.

Male osteoporosis is an increasingly important health problem worldwide. Though androgen deficiency leads to bone loss in men, information on the relative contribution of aromatizable and non-aromatizable androgens in maintaining bone mineral density (BMD) and the mechanisms involved are unclear. This cross-sectional study was designed to explore the same.

Differential response of Leydig cells in expressing 11beta-HSD type I and cytochrome P450 aromatase in male rats subjected to corticosterone deficiency.

Emerging evidence suggests that the glucocorticoid and estradiol are important for Leydig cell steroidogenesis and are regulated via aromatase for estradiol production and 11beta-HSD for oxidatively inactivating glucocorticoid. Although it is known that corticosterone deficiency impaired Leydig cell steroidogenesis, its effect on the expression of Leydig cell 11beta-HSD type I and aromatase are yet to be recognized. Following metyrapone-induced corticosterone deficiency, serum corticosterone and testosterone levels decrease, whereas serum estradiol remains unaltered.

Effects of polychlorinated biphenyl (Aroclor 1254) on steroidogenesis and antioxidant system in cultured adult rat Leydig cells.

Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental contaminants that disturb normal endocrine functions, including gonadal functions in humans and mammals. In the present study, we examined the direct effects of PCB on rat Leydig cells in vitro. Adult Leydig cells were purified by Percoll gradient centrifugation method and the purity of Leydig cells was also determined by 3beta-hydroxysteroid dehydrogenase (3beta-HSD) staining method.

Effect of ethanol on human osteosarcoma cell proliferation, differentiation and mineralization.

The habitual consumption of even moderate quantities of alcoholic beverages is clearly associated with reduced bone mass, increased prevalence of skeletal fracture and also it is the major risk factor for the development of secondary osteoporosis. The present in vitro study was designed to determine the dose response effects of ethanol on osteoblast-like human osteosarcoma cells (SaOS-2) proliferation, differentiation, mineralization and cyto-toxicity. SaOS-2 cells were plated in 48 and 6 well culture plates and exposed to different concentrations of ethanol (1, 10, 100, 200 and 300 mM) for 24, 48 and 72 h.