Two distinct lithium diffusive species for polymer gel electrolytes containing LiBF₄, propylene carbonate (PC) and PVDF

Polymer gel electrolytes have been prepared using lithium tetrafluoroborate (LiBF₄), propylene carbonate (PC) and polyvinylidene fluoride (PVDF) at 20% and 30% concentration by mass. Self diffusion coefficients have been measured using pulse field gradient nuclear magnetic resonance (PFG-NMR) for the cation and anion using ⁷Li and ¹⁹F resonant frequencies respectively. It was found that lithium ion diffusion was slow compared to the much larger fluorine anion likely resulting from a large solvation shell of the lithium. Lithium ion diffusion measurements exhibited two distinct diffusive species, whereas the fluorine ions exhibited only a single diffusive species

Evaluation of the Theoretical Uncertainties in the Z to ll Cross Sections at the LHC

We study the sources of systematic errors in the measurement of the Z to ll cross-sections at the LHC. We consider the systematic errors in both the total cross-section and acceptance for anticipated experimental cuts. We include the best available analysis of QCD effects at NNLO in assessing the effect of higher order corrections and PDF and scale uncertainties on the theoretical acceptance. In addition, we evaluate the error due to missing NLO electroweak corrections and propose which MC generators and computational schemes should be implemented to best simulate the events.Comment: 23 pages, 52 eps figures, LaTeX with JHEP3.cls, epsfig. Added a reference, acknowledgment, and a few clarifying comments. 4/29: Changes in references, minor rewordings and misprint corrections, and one new table (Table 4) comparing CTEQ and MRST PDFs in the NNLO calculation. Version 6 adds email addresses and corrects one referenc

NMR Self Diffusion and Relaxation Time Measurements for Poly (vinylidene fluoride) (PVDF) Based Polymer Gel Electrolytes Containing LiBF4 and Propylene Carbonate

Polymer gel electrolytes (PGEs) have been prepared using lithium tetrafluoroborate (LiBF4), propylene carbonate (PC) and poly (vinylidene fluoride) (PVDF). Self diffusion coefficients have been measured using pulse field gradient nuclear magnetic resonance (PFG-NMR) for the lithium cation, BF4 anion and solvent molecules using 7Li, 19F and 1H nuclei, respectively. It was found that lithium ion diffusion was slow compared to the much larger fluorinated BF4 anion, which is attributed to a large solvation shell around the lithium ions. The 7Li and 1H diffusion measurements also exhibited two unique environments for the diffusive species. The measurement of NMR transverse relaxation times has confirmed the presence of lithium ions in multiple phases as shown by the diffusion measurements

Relationship of Dental Caries and Fluorosis to Fluoride Supplement History in a Non-Fluoridated Sample of Schoolchildren

A random sample of 206 Michigan children, aged from 9 to 13, were examined for fluorosis from a larger group of 2038 children participating in a dental project. Clinical examinations included caries data (DMFS) and assessment of fluorosis by use of the Tooth Surface Index of Fluorosis (TSIF). Separate examiners were used for each index. The response rate of a questionnaire mailed to parents to gather information on residence histories, use of fluoride supplements, and antibiotics was 78%. The prevalence of fluorosis was about 20% among the respondents. Of the 4868 tooth surfaces examined, 9.2% were affected by fluorosis. In all cases, dental fluorosis was judged as mild, with most occurrences on the posterior teeth. No instances of moderate or severe fluorosis were found. The caries experience of respondents was 1.69 ± 2.73 DMFS. Caries experience does not appear to be significantly related to income, education, or fluoride supplement use. Approximately 52% of respondents were reported to have taken fluoride supplements with various degrees of consistency. Parents' education was positively related to both prevalence of fluorosis (odds ratio = 2.2) and use of fluoride supplements (odds ratio = 2.7). No significant relation was revealed with evidence of fluorosis and use of supplements. This study shows a relatively mild level of dental fluorosis in a sample of children from a non-fluoridated area. Dental fluorosis in this group does not appear to be related to use of fluoride supplements or differences in caries experience.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66503/2/10.1177_08959374890030021501.pd

Individual isotopic specializations predict subsequent inter-individual variation in movement in a freshwater fish

Despite many similarities and intuitive links between individual dietary specialization and behavioral inter-individual variation, these phenomena have been studied in isolation, and empirical data confirming relationships between these intraspecific variance sources are lacking. Here we use stable isotope analysis and acoustic telemetry to test the hypothesis that individual specialization in trophic (d15N) and littoral/pelagic prey reliance (d13C) covary with inter-individual variation in movement in a group of 34 free-swimming burbot (Lota lota). By performing stable isotope analysis on tissues with differing isotopic turnover rates (anal fin and dorsal muscle), in 24 lethally sampled burbot, we demonstrate that individual specialization in trophic niche (d15N) and li

Measurement of the partial widths of the Z into up- and down-type quarks

Using the entire OPAL LEP1 on-peak Z hadronic decay sample, Z -> qbarq gamma decays were selected by tagging hadronic final states with isolated photon candidates in the electromagnetic calorimeter. Combining the measured rates of Z -> qbarq gamma decays with the total rate of hadronic Z decays permits the simultaneous determination of the widths of the Z into up- and down-type quarks. The values obtained, with total errors, were Gamma u = 300 ^{+19}_{-18} MeV and Gamma d = 381 ^{+12}_{-12} MeV. The results are in good agreement with the Standard Model expectation.Comment: 22 pages, 5 figures, Submitted to Phys. Letts.

Search for R-Parity Violating Decays of Scalar Fermions at LEP

A search for pair-produced scalar fermions under the assumption that R-parity is not conserved has been performed using data collected with the OPAL detector at LEP. The data samples analysed correspond to an integrated luminosity of about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An important consequence of R-parity violation is that the lightest supersymmetric particle is expected to be unstable. Searches of R-parity violating decays of charged sleptons, sneutrinos and squarks have been performed under the assumptions that the lightest supersymmetric particle decays promptly and that only one of the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield final states consisting of leptons, jets, or both with or without missing energy. No significant single-like excess of events has been observed with respect to the Standard Model expectations. Limits on the production cross- section of scalar fermions in R-parity violating scenarios are obtained. Constraints on the supersymmetric particle masses are also presented in an R-parity violating framework analogous to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.

Measurement of the Strong Coupling alpha s from Four-Jet Observables in e+e- Annihilation

Data from e+e- annihilation into hadrons at centre-of-mass energies between 91 GeV and 209 GeV collected with the OPAL detector at LEP, are used to study the four-jet rate as a function of the Durham algorithm resolution parameter ycut. The four-jet rate is compared to next-to-leading order calculations that include the resummation of large logarithms. The strong coupling measured from the four-jet rate is alphas(Mz0)= 0.1182+-0.0003(stat.)+-0.0015(exp.)+-0.0011(had.)+-0.0012(scale)+-0.0013(mass) in agreement with the world average. Next-to-leading order fits to the D-parameter and thrust minor event-shape observables are also performed for the first time. We find consistent results, but with significantly larger theoretical uncertainties.Comment: 25 pages, 15 figures, Submitted to Euro. Phys. J.