Articles you may be interested inRotational spectroscopy and molecular structure of the 1-chloro-1-fluoroethylene-acetylene complex J. Chem. Phys. 134, 034303 (2011); 10.1063/1.3517494 Fourier transform microwave spectroscopy and molecular structure of the trans-1,2-difluoroethylene-hydrogen fluoride complex Rotational spectroscopy and molecular structure of 1,1,2-trifluoroethylene and the 1,1,2-trifluoroethylenehydrogen fluoride complex Effect of solvent on molecular conformation: Microwave spectra and structures of 2-aminoethanol van der Waals complexes Fourier transform microwave, rotational spectra in the 6 -21 GHz region are obtained for the complex formed between 1,1-difluoroethylene and acetylene, including the normal isotopomer and each singly substituted 13 C species along with complexes derived from commercially available isotopic varieties of acetylene ͑HCCD, DCCD, and H 13 C 13 CH͒. Although two possible planar structures are consistent with the rotational constants derived from analysis of the spectra, ab initio calculations, as well as chemical intuition, support only one of the two as the structure of the complex. Nuclear quadrupole coupling constants for D-containing species show no evidence of electric field gradient perturbation and are consistent with the structures obtained from inertial data. The primary interaction between the two molecules is a 2.646͑11͒ Å hydrogen bond with acetylene as the donor and a 1,1-difluoroethylene fluorine as the acceptor that forms a 122.41͑79͒°C-F¯H angle. A secondary interaction between the acetylenic bond and the difluoroethylene hydrogen atom cis to the acceptor fluorine atom causes the hydrogen bond to deviate 53.25͑24͒°from linearity. Structural comparisons with the related complex, 1,1-difluoroethylene-hydrogen chloride ͓Z. Kisiel et al., J. Chem. Soc., Faraday Trans. 88, 3385 ͑1992͔͒, suggest that the hydrogen bond in the acetylene complex is weaker, whereas comparisons with vinyl fluoride-acetylene ͓G. C. Cole and A. C. Legon, Chem. Phys. Lett. 369, 31 ͑2003͔͒ indicate that the fluorine atoms in 1,1-difluoroethylene are less basic than the one in vinyl fluoride. a ⌬I rms = ͱ͚͑I obs − I calc ͒ 2 / ͑No. of observables− No. of parameters͒.

Guided by ab initio calculations, Fourier transform microwave rotational spectra in the 6-22 GHz region are obtained for the complex formed between 1,1,2-trifluoroethylene and acetylene, including the normal isotopomer, three of four singly substituted (13)C species obtained in natural abundance, and using commercially available isotopic varieties of acetylene, species containing HCCD and H(13)C(13)CH. Although the ab initio calculations suggest two possible low energy planar arrangements for the molecules in the complex, only a single, unique structure is obtained from a combined analysis of the rotational constants derived from the spectra and atomic positions determined using Kraitchman [Am. J. Phys. 21, 17 (1953)] substitution coordinates. This structure is similar to that obtained for the CF(2)CHF[Single Bond]HF complex [H. O. Leung and M. D. Marshall, J. Chem. Phys. 126, 114310 (2007)] in which both the primary and secondary interactions occur between the HCCH molecule and a F atom and a H atom bonded to the same carbon of CF(2)CHF. The 2.748(15) A hydrogen bond has acetylene as the donor and 1,1,2-trifluoroethylene as the acceptor and forms a 104.49(15) degrees C[Single Bond]Fcdots, three dots, centeredH angle. The 2.8694(9) A secondary interaction between the pi bond of acetylene and the H atom geminal to the acceptor F atom causes the hydrogen bond to deviate 69.24(67) degrees from linearity. This large deviation from linearity and the similarity of the two intermolecular bond lengths suggest that the two interactions are becoming comparable in importance.

Purpose Medications can have unintended effects. High medication use populations may benefit from increased regimen oversight. Limited knowledge exists concerning racial and regional polypharmacy variation. We estimated total medication distributions (excluding supplements) of American black and white adults and assessed racial and regional polypharmacy variation. Methods REasons for Geographic And Racial Differences in Stroke (REGARDS) cohort data (N=30,239 U.S. blacks/whites ages ≥45 years) were analyzed. Home pill-bottle inspections assessed the last two weeks’ medications. Polypharmacy (≥ 8 medications) was determined by summing prescription and/or OTC ingredients. Population-weighted logistic regression assessed polypharmacy’s association with census region, race, and gender. Results The mean ingredient number was 4.12 (SE = 0.039), with 15.7% of REGARDS using ≥8 ingredients. In crude comparisons, women used more medications than men, and blacks and whites reported similar mean ingredients. A cross-sectional, logistic model adjusting for demographics, socioeconomics, and comorbidities showed increased polypharmacy prevalence in whites vs. blacks (OR, [95% CI]: 0.63, [0.55–0.72]), women (1.94, [1.68–2.23]), and Southerners {broadly Southeasterners and Texans} (1.48, [1.17–1.87]) vs. Northeasterners {broadly New England and upper Mid-Atlantic}. Possible limitations include polypharmacy misclassification and model mis-specification. Conclusion Polypharmacy is common. Race and geography are associated with polypharmacy variation. Further study of underlying factors explaining these differences is warranted.

Metformin, an insulin-sensitizing drug, is a first line treatment for type 2 diabetes. Long-term use of metformin has been associated with subsequent reductions in vitamin B12 concentrations. The objective of our study was to determine whether metformin use is associated with lower serum vitamin B12 concentrations in older adults, and whether concurrent use of multivitamins modifies this association. We examined 2,510 participants aged 50 years and over, participating in the national population-based Reasons for Geographic And Racial Differences in Stroke (REGARDS) Study. Multivariable linear and logistic regression models were used to assess associations between multivitamin use and serum vitamin B12 concentrations. We estimated adjusted odds ratios (aOR)s and confidence intervals (CI)s. Results were stratified by three metformin/diabetes sub-groups: 1) participants with diabetes who were metformin users; 2) participants with diabetes who were not metformin users; and 3) participants without diabetes. We found that diabetic metformin users had significantly lower geometric mean serum B12 concentrations (409 pmol/L) than the group with diabetes not taking metformin (485 pmol/L; P<0.01), and the group without diabetes (445 pmol/L; P = 0.02). The geometric mean serum B12 concentrations were greater for multivitamin users (509 pmol/L) compared to those who did not use multivitamins (376 pmol/L; p<0.01). Among the participants with diabetes who were on metformin therapy, multivitamin use was associated with geometric mean serum vitamin B12 concentrations that were 50% (or 161 pmol/L) higher, compared to those not using multivitamins. Among metformin users, multivitamin use was associated with lower prevalence of combined low and borderline vitamin B12 concentrations (aOR = 0.14; 95% CI = 0.04, 0.54) compared to those not using multivitamins. In conclusion, metformin use was associated with lower geometric mean serum vitamin B12 concentrations among diabetic older adults compared to their counterparts. Concurrent multivitamin use may potentially protect against low or borderline vitamin B12 concentrations in long-term metformin users. Additional research is needed to further examine this association as low or borderline vitamin B12 concentrations can be preventable, or treatable if detected at an early stage, in long-term metformin users.

The microwave spectra of six isotopomers of HCl-N(2)O have been obtained in the 7-19 GHz region with a pulsed molecular beam, Fourier transform microwave spectrometer. The nuclear quadrupole hyperfine structure due to all quadrupolar nuclei is resolved and the spectra are analyzed using the Watson S-reduced Hamiltonian with the inclusion of nuclear quadrupole coupling interactions. The spectroscopic constants determined include rotational constants, quartic and sextic centrifugal distortion constants, and nuclear quadrupole coupling constants for each quadrupolar nucleus. Due to correlations of the structural parameters, the effective structure of the complex cannot be obtained by fitting to the spectroscopic constants of the six isotopomers. Instead, the parameters for each isotopomer are calculated from the A and C rotational constants and the chlorine nuclear quadrupole coupling constant along the a-axis, chi(aa). There are two possible structures; the one in which hydrogen of HCl interacts with the more electronegative oxygen of N(2)O is taken to represent the complex. The two subunits are approximately slipped parallel. For H (35)Cl-(14)N(2)O, the distance between the central nitrogen and chlorine is 3.5153 A and the N(2)O and HCl subunits form angles of 72.30 degrees and 119.44 degrees with this N-Cl axis, respectively. The chlorine and oxygen atoms occupy the opposite, obtuse vertices of the quadrilateral formed by O, central N, Cl, and H. Nuclear quadrupole coupling constants show that while the electric field gradient of the HCl subunit remains essentially unchanged upon complexation, there is electronic rearrangement about the two nitrogen nuclei in N(2)O.