Menopausal Voice-Related Work Limitation Scale (MenoVWL): Development and Validation.

Objectives: Menopause has been reported to affect the voice of female professional voice users (FPVUs). The present study aims at the development and validation of a scale to measure self-perceived menopausal voice-related limitation to work in FPVUs, henceforth the Menopausal Voice-Related Work Limitation Scale (MenoVWL).

Methods: Items were drawn from previous studies on impacts of sex steroid hormones on voice, available validated scales, and in-depth interviews with post-menopausal FPVUs.

What Voice-Related Metrics Change With Menopause? A Systematic Review and Meta-Analysis Study.

Voice complaints associated with menopause have been reported by a substantial number of studies. However, to assess the clinical relevance of menopause to voice is still difficult as the extent to which menopausal symptoms are reflected on voice metrics remains unclear. A comprehensive review and meta-analysis were carried out to identify voice-related metrics that change with menopause and to quantify the magnitude of those changes.

Mechanism of aqueous-phase ozonation of S(IV).

The ozonation of dissolved sulfur dioxide is an important route for sulfate formation, especially in fog and cloud droplets of high pH. However, little is known about the detailed chemical mechanism of this process. We have mapped out the fate of aqueous SO(2) in the presence of ozone by use of density functional theory (DFT) calculations in solution (via the polarized continuum model, PCM), including up to two explicit water molecules.

Where does acid hydrolysis take place?

We present the results of computations on the dissociation of HCl and HNO(3) at the air-water interface. Molecular dynamics simulations of the acid molecule and 200 water molecules were propagated for several nanoseconds, and the resulting structures were used as input to QM/MM geometry optimization runs. Approximately 20-30 water molecules were included along with the acid in the QM portion of the calculation, which was carried out at the B3LYP/6-31+G(d) level.

A theoretical investigation of the Co(CO)4--catalyzed carbonylative ring expansion of N-benzoyl-2-methylaziridine to beta-lactams: reaction mechanism and effect of substituent at the aziridine Calpha atom.

The reaction mechanism of the Co(CO)4--catalyzed carbonylative ring expansion of N-benzoyl-2-methylaziridine to afford N-benzoyl-4-methyl-2-azetidinone and N-benzoyl-3-methyl-2-azetidinone was investigated by using the B3LYP density functional theory methodology in conjunction with the conductor polarizable continuum model/united atom Kohm-Sham method to take into account solvent effects. Computations predict that the most favorable reaction mechanism differs from the experimental proposals except for the nucleophilic ring-opening step, which is the rate-determining one. The regioselectivity and stereospecificity experimentally observed is explained in terms of the located reaction mechanism.

A theoretical study of rhodium(I) catalyzed carbonylative ring expansion of aziridines to beta-lactams: crucial activation of the breaking C-N bond by hyperconjugation.

The regioselectivity and enantiospecificity of the [Rh(CO)2Cl]2-catalyzed carbonylative ring expansions of N-tert-butyl-2-phenylaziridine to yield 2-azetidinone and the lack of reactivity of N-tert-butyl-2-methylaziridine along this process were investigated at the B3LYP/6-31G(d) (LANL2DZ for Rh) theory level taking into account solvent effects. According to our results, the regioselectivity in the ring expansion of N-tert-butyl-2-phenylaziridine and the unreactivity of N-tert-butyl-2-methylaziridine experimentally observed are determined by the different degree of activation of the breaking C-N bond in the initial aziridine-Rh(CO)2Cl complex due to its hyperconjugation interaction with the substituent on the carbon atom. When a phenyl substituent is present its hyperconjugation interaction with the C(alpha)-N bond facilitates the insertion of the metal atom into this bond.

Radical ring expansion reactions of methylenecyclopropane derivatives: a theoretical study.

The evolution of the primary radicals from 1-(3-bromopropyl)-2-ethyl-3-methylenecyclopropane, 1-(3-bromopropyl)-1-trimethylsilyl-2-methylenecyclopropane, 1-(3-bromobutyl)-2-ethyl-3-methylenecyclopropane, and 1-(3-bromobutyl)-1-trimethylsilyl-2-methylenecyclopropane was theoretically studied at the ROMP2/6-311++G(d,p)//UB3LYP/6-31G(d,p) theory level taking into account the effect of solvent through a PCM-UAHF model. For the propyl-substituted radicals, the attack of the radical center on the double bond takes place most favorably in an exo fashion. The subsequent ring expansions yield the product corresponding to the rupture of the endo C-C bond as the most favorable one in accordance with the experimental results.

Relative Gibbs energies in solution through continuum models: effect of the loss of translational degrees of freedom in bimolecular reactions on Gibbs energy barriers.

We present here a cell model for evaluating Gibbs energy barriers corresponding to bimolecular reactions (or processes of larger molecularity) in which a loss of translational degrees of freedom takes place along the reaction coordinate. With this model, we have studied the Walden inversion processes: Xa- + H3CXb --> XaCH3 + Xb- (X = F, Cl, Br, and I). In these processes, our model yields an increase of about 2.

Three-carbon Dowd-Beckwith ring expansion reaction versus intramolecular 1,5-hydrogen transfer reaction: a theoretical study.

[Reaction: see text]. The evolution of the primary radicals formed by addition of AIBN/HSnBu3 to methyl 1-(3-iodopropyl)-5-oxocyclopentanecarboxylate, methyl (1R,2R)-1-(3-iodopropyl)-2-methyl-5-oxocyclopentanecarboxylate, and methyl (1R,2S)-1-(3-iodopropyl)-2-methyl-5-oxocyclopentanecarboxylate in benzene has been theoretically investigated by ROMP2/6-311++G(2d,2p)//UB3LYP/6-31G(d,p) calculations taking into account the effect of solvent through a PCM-UAHF model. According to the theoretical results, for methyl 1-(3-iodopropyl)-5-oxocyclopentanecarboxylate and methyl (1R,2S)-1-(3-iodopropyl)-2-methyl-5-oxocyclopentanecarboxylate the major product is the cyclooctane derivative from the three-carbon ring expansion, whereas for methyl (1R,2R)-1-(3-iodopropyl)-2-methyl-5-oxocyclopentanecarboxylate the major product is that corresponding to the 1,5-H transposition in agreement with the experimental findings.