351 research outputs found
Ultrasound promoted regioselective synthesis of beta-iodoethers from olefin-I2-alcohol.
Regioselective synthesis of beta-iodoethers in high yields by sonicating alkene and alcohol in the presence of iodine in a bath at 35 kHz is reporte
Regiospecific Reduction of Oxetanes with Lithium under Aprotic Conditions
Substituted oxetanes have been found to give exclusively terminal alcohols by regiospecific ring-opening with
lithium and biphenyl (cat.) in THF at reflu
ChemInform Abstract: Reductive Dehalogenation of 뱉Haloketones with Zinc in Presence of Ammonium Salts under Sonic Conditions.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a âFull Textâ option. The original article is trackable via the âReferencesâ option
Qualitative study of supramolecular assemblies of ÎČ-cyclodextrin and cholecalciferol and the cobalt (II), copper (II) and zinc (II) ions
A 13C NMR in DMSO-d6 as solvent, diffuse reflectance spectra and X-ray powder diagram study of the inclusion of vitamin D in ÎČ-cyclodextrin and of the ternary assemblies with ÎČ-cyclodextrin, vitamin D and metal ions (e.g. Co(II), Cu(II) and Zn(II)) was carried out to determine the structure of these associations in which the molecular ratios (ÎČ-cyclodextrin:vitamin D:metal ions) were 5:1:1 or 10:1:1
Supramolecular assemblies of Al3+ complexes with vitamin D3 (cholecalciferol) and phenothiazine. Encapsulation and complexation studies in ÎČ-cyclodextrin
Ternary assemblies of ÎČ-cyclodextrin with cholecalciferol (or vitamin D3) or phenothiazine and Al3+ ions were studied. The stability constants of aluminium binary complexes with cholecalciferol or phenothiazine and of ternary assemblies (ÎČ-cyclodextrin, cholecalciferol or phenothiazine and Al3+) were determined using potentiometric titrations at 25 °C (I = 0.100 M). The 13C NMR spectra of the supramolecular structures in the solid state showed that ternary supramolecular structures associating ÎČ-cyclodextrin, cholecalciferol or phenothiazine and aluminium(III) ions were obtained. Finally, X-ray powder diffraction patterns showed that the ternary assemblies with phenothiazine are channel type inclusion complexes
Evolution of the electronic structure with size in II-VI semiconductor nanocrystals
In order to provide a quantitatively accurate description of the band gap
variation with sizes in various II-VI semiconductor nanocrystals, we make use
of the recently reported tight-binding parametrization of the corresponding
bulk systems. Using the same tight-binding scheme and parameters, we calculate
the electronic structure of II-VI nanocrystals in real space with sizes ranging
between 5 and 80 {\AA} in diameter. A comparison with available experimental
results from the literature shows an excellent agreement over the entire range
of sizes.Comment: 17 pages, 4 figures, accepted in Phys. Rev.
Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider
This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the Ï(4S), Ï(3S), and Ï(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-âe+e- and (for the Ï(4S) only) e+e-âÎŒ+ÎŒ- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-âe+e- and e+e-âÎŒ+ÎŒ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the Ï(3S) and Ï(2S) resonances, an additional uncertainty arises due to Ïâe+e-X background. For data collected off the Ï resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the Ï(4S), 0.58% (0.72%) for the Ï(3S), and 0.68% (0.88%) for the Ï(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat Ă lâEnergie Atomique and Institut National de Physique NuclĂ©aire et de Physiquedes Particules (France), the Bundesministerium fĂŒr Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e InnovaciĂłn (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
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