839 research outputs found

    A novel measurement of Bs0B^0_s and Ds−D^-_s lifetimes using semileptonic decays at LHCb

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    I report new, world-leading LHCb results on heavy meson lifetimes. We use a novel approach that suppresses the shortcomings typically associated with reconstruction of semileptonic decays, allowing for precise measurements of lifetimes and other properties in collider experiments. We achieve a 15% and a 2×2\times improvement over current best determinations of the flavor-specific Bs0B^0_s lifetime and Ds−D^-_s lifetime, respectively.Comment: 12 pages, 6 figures. Talk presented at the APS Division of Particles and Fields Meeting (DPF 2017), July 31-August 4, 2017, Fermilab. C17073

    Metal (Ni, Pd, and Pt)-Doped BS Monolayers as a Gas Sensor upon Vented Gases in Lithium-Ion Batteries: A First-Principles Study

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    Real-time monitoring of the vented gases emitted by the thermal runaway of lithium-ion batteries (LIBs) is of great significance to the normal use of LIBs. We study systematically the adsorption and sensing performances of pristine and metal-doped BS monolayers to five typical gases (CO, CO2, CH4, C2H2, and C2H4) emitted from LIBs employing the first-principles method. The adsorption structure and energetics, charge transfer, band structure, density of states, sensitivity, and recovery time are simulated and analyzed. Outstanding sensing properties are predicted for the Ni-, Pd-, and Pt-doped BS monolayers, although their recently synthesized pristine counterpart shows little sensing potential for those gases. The magnitude of the adsorption energy increases from 0.249 eV to 2.32 eV (Ni-BS), 1.954 eV(Pd-BS), and 2.994 eV (Pt-BS) for the CO gas after doping. Besides, significant variation of band gap is observed after gas adsorption in doped BS nanosheets, which leads to huge theoretical values of the sensitivity. The sensitivity for CO, CO2, CH4, C2H2, and C2H4 on Pt-BS may reach up to 5.87 × 105, 1.57 × 106, 1.81 × 105, 8.33 × 104, and 8.18 × 103, respectively. In addition, the calculated recovery times indicate that the doped BS monolayers have strong selectivity for the adsorption and detection of these five gases. The three metal-doped BS monolayers should have great potential for application in sensors monitoring the gases emitted from LIBs

    Surface-Based Control of Oxygen Interstitial Injection into ZnO via Submonolayer Sulfur Adsorption

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    Semiconductor surfaces offer efficient pathways for injecting native point defects into the underlying bulk. Adsorption of a suitably chosen foreign element serves to modulate the injection rate, even at small percentages of a monolayer. Through self-diffusion experiments using isotopic exchange with labeled oxygen, the present work demonstrates such behavior in the case of sulfur adsorption on <i>c</i>-axis Zn-terminated ZnO(0001), wherein the clean surface injects with exceptional efficiency. The experiments provide strong evidence that the injection sites comprise only a small fraction of the total surface atom density and that sulfur adsorption merely blocks those sites. Comparison with related systems shows this simple mechanism is surprisingly uncommon

    Quantitative Analysis of the Shape Effect of Thermoplasmonics in Gold Nanostructures

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    The shape effect of thermoplasmonic properties of Au nanostructures remains largely unexplored. Herein, we report a systematic investigation on the photothermal effects of Au nanoparticles (NPs) of different shapes: nanosphere, nanocube, nanorod, nanostar, and nanobipyramid. The Joule (Jo) number (absorption cross section normalized by the particulate volume) is utilized for quantitatively assessing the photothermal properties of these different shaped Au NPs. It is shown that the Jo number of Au NPs greatly varies with the geometric shape and localized surface plasmon resonance (LSPR) wavelength. Specifically, the Jo number decreases with the red-shifting of the LSPR wavelength in these Au NPs, and the Au NPs of sharp structural features such as Au nanorod, nanostar and nanobipyramid have a much larger Jo number, indicative of their exceptional light-to-heat conversion ability. We further demonstrate the close correlation of the Jo number of Au NPs of different shapes with their optical absorption power density

    DataSheet1_Efficacy and safety of total glucosides of paeony as an add-on treatment in adolesents and adults with chronic urticaria: A systematic review and meta-analysis.PDF

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    Background: Total glycosides of paeony (TGP), an active compound extracted from the dried roots of Paenoia lactiflora Pall., has been widely used to treat chronic urticaria (CU) in China. This study aims to systematically evaluate the efficacy and safety of TGP as an add-on treatment for the treatment of CU in adolescents and adults.Methods: Eight literature databases and two clinical trial registries were searched from their inception to 31 May 2022. Randomized controlled trials on TGP as an add-on treatment for CU in adolescents and adults were included. The Cochrane Collaboration’s risk of bias tool was used for the methodological quality assessment, and RevMan 5.3 software and Stata 12.0 software were used for data analyses.Results: A total of 30 studies with 2,973 participants were included in this meta-analysis. The methodological qualities of all included studies were suboptimal. The pooled results showed that TGP combined with H1-antihistamine was superior to H1-antihistamine alone in the cure rate (risk ratio (RR) = 1.54, 95% confidence interval (CI) = 1.39 to 1.71, p Conclusions: TGP as an add-on treatment could provide a good effect for CU in adolescents and adults with mild and tolerable adverse events. However, in view of poor methodological quality, high-quality and long-term clinical trials are needed in the future to confirm and update the evidence.</p

    Three-Component Cascade Annulation of β‑Ketothioamides Promoted by CF<sub>3</sub>CH<sub>2</sub>OH: A Regioselective Synthesis of Tetrasubstituted Thiophenes

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    A rapid and highly efficient method for the regioselective synthesis of thiophene derivatives has been developed by annulation of β-ketothioamides with arylglyoxals and 5,5-dimethyl-1,3-cyclohexanedione in CF<sub>3</sub>CH<sub>2</sub>OH within 15 min. The present synthesis has several desirable features, such as high regioselectivity, a concise one-pot protocol, short reaction time, and easy purification. This methodology provides an alternative approach for easy access to tetrasubstituted thiophenes via a one-pot cascade reaction without other additives

    Three-Component Cascade Annulation of β‑Ketothioamides Promoted by CF<sub>3</sub>CH<sub>2</sub>OH: A Regioselective Synthesis of Tetrasubstituted Thiophenes

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    A rapid and highly efficient method for the regioselective synthesis of thiophene derivatives has been developed by annulation of β-ketothioamides with arylglyoxals and 5,5-dimethyl-1,3-cyclohexanedione in CF<sub>3</sub>CH<sub>2</sub>OH within 15 min. The present synthesis has several desirable features, such as high regioselectivity, a concise one-pot protocol, short reaction time, and easy purification. This methodology provides an alternative approach for easy access to tetrasubstituted thiophenes via a one-pot cascade reaction without other additives

    Dual Roles of β‑Oxodithioesters in the Copper-Catalyzed Synthesis of Benzo[<i>e</i>]pyrazolo[1,5‑<i>c</i>][1,3]thiazine Derivatives

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    A facile and efficient method for the chemoselective synthesis of benzo­[<i>e</i>]­pyrazolo­[1,5-<i>c</i>]­[1,3]­thiazine derivatives has been developed by tandem Ullmann coupling reactions of β-oxodithioesters (ODEs) with 3-(2-bromoaryl)-1<i>H</i>-pyrazoles in C–S bond formation manner, in which ODEs play dual roles as both a substrate and a ligand. A series of benzo­[<i>e</i>]­pyrazolo­[1,5-<i>c</i>]­[1,3]­thiazine derivatives were provided in good to excellent yields with CuI as the copper source in the presence of NaOH in CH<sub>3</sub>CN at 80 °C under a N<sub>2</sub> atmosphere
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