148 research outputs found

    Probing electronic-vibrational dynamics of N2+ induced by strong-field ionization

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    The coupled electronic-vibrational dynamics of nitrogen ions induced by strong-field ionization is investigated theoretically to corroborate the recent transient X-ray K-edge absorption experiment [PRL 129, 123002 (2022)], where the population distribution of three electronic states in air lasing of N2+ was determined for the first time. By extending the ionization-coupling model to include the transient absorption, we successfully reproduce the time-resolved X-ray absorption spectra of nitrogen ions observed in the experiment. By identifying the contributions from different electronic states, the study provides different interpretation revealing the significant role of excited state A arising from the strong coupling between vibrational states in strong laser fields. It indicates that the electronic population inversion occurs at least for certain alignment of nitrogen molecules. The theory helps uncovering new features of absorption from forbidden transitions during ionization and confirming that the vibration coherence at each electronic channel induces the modulation of absorbance after strong field ionization. A new scheme is proposed to determine the population transfer at different probing geometry to avoid the spectral overlap. This work offers valuable insights into the intricate interplay between electronic and vibrational dynamics and helps to resolve the debate on nitrogen air lasing

    Partial Wave Analysis of J/ψγ(K+Kπ+π)J/\psi \to \gamma (K^+K^-\pi^+\pi^-)

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    BES data on J/ψγ(K+Kπ+π)J/\psi \to \gamma (K^+K^-\pi^+\pi^-) are presented. The KKˉK^*\bar K^* contribution peaks strongly near threshold. It is fitted with a broad 0+0^{-+} resonance with mass M=1800±100M = 1800 \pm 100 MeV, width Γ=500±200\Gamma = 500 \pm 200 MeV. A broad 2++2^{++} resonance peaking at 2020 MeV is also required with width 500\sim 500 MeV. There is further evidence for a 2+2^{-+} component peaking at 2.55 GeV. The non-KKˉK^*\bar K^* contribution is close to phase space; it peaks at 2.6 GeV and is very different from KKˉK^{*}\bar{K^{*}}.Comment: 15 pages, 6 figures, 1 table, Submitted to PL

    Measurement of ψ(2S)\psi(2S) decays to baryon pairs

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    A sample of 3.95M ψ(2S)\psi(2S) decays registered in the BES detector are used to study final states containing pairs of octet and decuplet baryons. We report branching fractions for ψ(2S)ppˉ\psi(2S)\to p\bar{p}, ΛΛˉ\Lambda\bar{\Lambda}, Σ0Σˉ0\Sigma^0\bar{\Sigma}{}^0, ΞΞˉ+\Xi^-\bar{\Xi}{}^+, Δ++Δˉ\Delta^{++}\bar{\Delta}{}^{--}, Σ+(1385)Σˉ(1385)\Sigma^+(1385)\bar{\Sigma}{}^-(1385), Ξ0(1530)Ξˉ0(1530)\Xi^0(1530)\bar{\Xi}{}^0(1530), and ΩΩˉ+\Omega^-\bar{\Omega}{}^+. These results are compared to expectations based on the SU(3)-flavor symmetry, factorization, and perturbative QCD.Comment: 22 pages, 21 figures, 4 table

    Magnetic Particle-Based Hybrid Platforms for Bioanalytical Sensors

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    Biomagnetic nano and microparticles platforms have attracted considerable interest in the field of biological sensors due to their interesting physico-chemical properties, high specific surface area, good mechanical stability and opportunities for generating magneto-switchable devices. This review discusses recent advances in the development and characterization of active biomagnetic nanoassemblies, their interaction with biological molecules and their use in bioanalytical sensors

    Methodology and applications of city level CO2 emission accounts in China

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    China is the world's largest energy consumer and CO2 emitter. Cities contribute 85% of the total CO2 emissions in China and thus are considered as the key areas for implementing policies designed for climate change adaption and CO2 emission mitigation. However, the emission inventory construction of Chinese cities has not been well researched, mainly owing to the lack of systematic statistics and poor data quality. Focusing on this research gap, we developed a set of methods for constructing CO2 emissions inventories for Chinese cities based on energy balance table. The newly constructed emission inventory is compiled in terms of the definition provided by the IPCC territorial emission accounting approach and covers 47 socioeconomic sectors, 17 fossil fuels and 9 primary industry products, which is corresponding with the national and provincial inventory. In the study, we applied the methods to compile CO2 emissions inventories for 24 common Chinese cities and examined uncertainties of the inventories. Understanding the emissions sources in Chinese cities is the basis for many climate policy and goal research in the future

    Prevalence and trend of hepatitis C virus infection among blood donors in Chinese mainland: a systematic review and meta-analysis

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    <p>Abstract</p> <p>Background</p> <p>Blood transfusion is one of the most common transmission pathways of hepatitis C virus (HCV). This paper aims to provide a comprehensive and reliable tabulation of available data on the epidemiological characteristics and risk factors for HCV infection among blood donors in Chinese mainland, so as to help make prevention strategies and guide further research.</p> <p>Methods</p> <p>A systematic review was constructed based on the computerized literature database. Infection rates and 95% confidence intervals (95% CI) were calculated using the approximate normal distribution model. Odds ratios and 95% CI were calculated by fixed or random effects models. Data manipulation and statistical analyses were performed using STATA 10.0 and ArcGIS 9.3 was used for map construction.</p> <p>Results</p> <p>Two hundred and sixty-five studies met our inclusion criteria. The pooled prevalence of HCV infection among blood donors in Chinese mainland was 8.68% (95% CI: 8.01%-9.39%), and the epidemic was severer in North and Central China, especially in Henan and Hebei. While a significant lower rate was found in Yunnan. Notably, before 1998 the pooled prevalence of HCV infection was 12.87% (95%CI: 11.25%-14.56%) among blood donors, but decreased to 1.71% (95%CI: 1.43%-1.99%) after 1998. No significant difference was found in HCV infection rates between male and female blood donors, or among different blood type donors. The prevalence of HCV infection was found to increase with age. During 1994-1995, the prevalence rate reached the highest with a percentage of 15.78% (95%CI: 12.21%-19.75%), and showed a decreasing trend in the following years. A significant difference was found among groups with different blood donation types, Plasma donors had a relatively higher prevalence than whole blood donors of HCV infection (33.95% <it>vs </it>7.9%).</p> <p>Conclusions</p> <p>The prevalence of HCV infection has rapidly decreased since 1998 and kept a low level in recent years, but some provinces showed relatively higher prevalence than the general population. It is urgent to make efficient measures to prevent HCV secondary transmission and control chronic progress, and the key to reduce the HCV incidence among blood donors is to encourage true voluntary blood donors, strictly implement blood donation law, and avoid cross-infection.</p

    Recent advances in designing and fabricating self-supported nanoelectrodes for supercapacitors

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    Owing to the outstanding advantages as electrical energy storage system, supercapacitors have attracted tremendous research interests over the past decade. Current research efforts are being devoted to improve the energy storage capabilities of supercapacitors through either discovering novel electroactive materials or nanostructuring existing electroactive materials. From the device point of view, the energy storage performance of supercapacitor not only depends on the electroactive materials themselves, but importantly, relies on the structure of electrode whether it allows the electroactive materials to reach their full potentials for energy storage. With respect to utilizing nanostructured electroactive materials, the key issue is to retain all advantages of the nanoscale features for supercapacitors when being assembled into electrodes and the following devices. Rational design and fabrication of self‐supported nanoelectrodes is therefore considered as the most promising strategy to address this challenge. In this review, we summarize the recent advances in designing and fabricating self‐supported nanoelectrodes for supercapacitors towards high energy storage capability. Self‐supported homogeneous and heterogeneous nanoelectrodes in the forms of one‐dimensional (1D) nanoarrays, two‐dimensional (2D) nanoarrays, and three‐dimensional (3D) nanoporous architectures are introduced with their representative results presented. The challenges and perspectives in this field are also discussed

    A Measurement of the Mass and Full-Width of the ηc\eta_c Meson

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    In a sample of 7.8 million J/ψJ/\psi decays collected in the Beijing Spectrometer, the process J/ψγηc\psi\to\gamma\eta_c is observed for five different ηc\eta_c decay channels: K+Kπ+πK^+K^-\pi^+\pi^-, π+ππ+π\pi^+\pi^-\pi^+\pi^-, K±KS0πK^\pm K^0_S \pi^\mp (with KS0π+πK^0_S\to\pi^+\pi^-), ϕϕ\phi\phi (with ϕK+K\phi\to K^+K^-) and K+Kπ0K^+K^-\pi^0. From these signals, we determine the mass of ηc\eta_c to be 2976.6±2.9±1.32976.6\pm2.9\pm1.3 MeV. Combining this result with a previously reported result from a similar study using ψ(2S)γηc\psi(2S)\to\gamma\eta_c detected in the same spectrometer gives mηc=2976.3±2.3±1.2m_{\eta_c} = 2976.3\pm2.3\pm1.2 MeV. For the combined samples, we obtain Γηc=11.0±8.1±4.1\Gamma_{\eta_c} = 11.0\pm 8.1\pm 4.1 MeV.Comment: 4 pages, 3 figures and 1 tabl

    Limits on active to sterile neutrino oscillations from disappearance searches in the MINOS, Daya Bay, and bugey-3 experiments

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    Searches for a light sterile neutrino have been performed independently by the MINOS and the Daya Bay experiments using the muon (anti)neutrino and electron antineutrino disappearance channels, respectively. In this Letter, results from both experiments are combined with those from the Bugey-3 reactor neutrino experiment to constrain oscillations into light sterile neutrinos. The three experiments are sensitive to complementary regions of parameter space, enabling the combined analysis to probe regions allowed by the Liquid Scintillator Neutrino Detector (LSND) and MiniBooNE experiments in a minimally extended four-neutrino flavor framework. Stringent limits on sin^2 2θμe are set over 6 orders of magnitude in the sterile mass-squared splitting Δm^2 41. The sterile-neutrino mixing phase space allowed by the LSND and MiniBooNE experiments is excluded for Δm^2 41 < 0.8 eV^2 at 95% CLs
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