31 research outputs found

    Precise Measurements of Branching Fractions for Ds+D_s^+ Meson Decays to Two Pseudoscalar Mesons

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    We measure the branching fractions for seven Ds+D_{s}^{+} two-body decays to pseudo-scalar mesons, by analyzing data collected at s=4.178∼4.226\sqrt{s}=4.178\sim4.226 GeV with the BESIII detector at the BEPCII collider. The branching fractions are determined to be B(Ds+→K+η′)=(2.68±0.17±0.17±0.08)×10−3\mathcal{B}(D_s^+\to K^+\eta^{\prime})=(2.68\pm0.17\pm0.17\pm0.08)\times10^{-3}, B(Ds+→η′π+)=(37.8±0.4±2.1±1.2)×10−3\mathcal{B}(D_s^+\to\eta^{\prime}\pi^+)=(37.8\pm0.4\pm2.1\pm1.2)\times10^{-3}, B(Ds+→K+η)=(1.62±0.10±0.03±0.05)×10−3\mathcal{B}(D_s^+\to K^+\eta)=(1.62\pm0.10\pm0.03\pm0.05)\times10^{-3}, B(Ds+→ηπ+)=(17.41±0.18±0.27±0.54)×10−3\mathcal{B}(D_s^+\to\eta\pi^+)=(17.41\pm0.18\pm0.27\pm0.54)\times10^{-3}, B(Ds+→K+KS0)=(15.02±0.10±0.27±0.47)×10−3\mathcal{B}(D_s^+\to K^+K_S^0)=(15.02\pm0.10\pm0.27\pm0.47)\times10^{-3}, B(Ds+→KS0π+)=(1.109±0.034±0.023±0.035)×10−3\mathcal{B}(D_s^+\to K_S^0\pi^+)=(1.109\pm0.034\pm0.023\pm0.035)\times10^{-3}, B(Ds+→K+π0)=(0.748±0.049±0.018±0.023)×10−3\mathcal{B}(D_s^+\to K^+\pi^0)=(0.748\pm0.049\pm0.018\pm0.023)\times10^{-3}, where the first uncertainties are statistical, the second are systematic, and the third are from external input branching fraction of the normalization mode Ds+→K+K−π+D_s^+\to K^+K^-\pi^+. Precision of our measurements is significantly improved compared with that of the current world average values

    New Insight into the Photoprotection Mechanism of Plant Sunscreens: Adiabatic Relaxation Competing with Nonadiabatic Relaxation in the cis -> trans Photoisomerization of Methyl Sinapate

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    A great deal of thermally instable cis form photoisomerization products will be formed from the thermally stable trans form of the plant sunscreens sinapate esters upon ultraviolet radiation. To reveal the photoisomerization mechanism of the cis-isomer, we explore the photodynamics of a model plant sunscreen methyl sinapate (MS) in the cis form in organic solution. The high photoisomerization quantum yield of the cis-isomer results in the relatively higher photostability of trans-MS. By utilizing femtosecond transient absorption spectroscopy and quantum chemical calculation, we propose that an adiabatic relaxation competes with nonadiabatic relaxation for the excited-state cis form of methyl sinapate. These results suggest that the photoprotection mechanism of the cis form of sinapate esters is significantly different from that of the trans form of sinapate esters and plays an important role in the overall photoprotection effect

    Progesterone/estradiol ratio <0.25 on the day of human chorionic gonadotropin administration is associated with adverse pregnancy outcomes in prolonged protocols for in vitro fertilization/intracytoplasmic sperm injection

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    Objective: It has been suggested that a progesterone/estradiol ratio (P/E2) ≥ 1.0 on the day of human chorionic gonadotropin (hCG) administration indicates premature luteinization and might be associated with an adverse pregnancy; however, a lower limit of this ratio has not been determined. We aimed to identify a lower limit of P/E2 that correlates significantly with an increase in adverse pregnancies in patients undergoing a prolonged in vitro fertilization/intracytoplasmic sperm injection therapy. Materials and Methods: This retrospective analysis involved 7451 patients who received the first cycle of in vitro fertilization/intracytoplasmic sperm injection therapy treatment at the Reproductive and Genetic Hospital of Citic–Xiangya between January 2008 and April 2012. Patients were stratified into six groups according to their P/E2 on the day of hCG administration. Primary pregnancy outcomes, rates of implantation, clinical pregnancy, ongoing pregnancies, spontaneous abortions, and live births were recorded. The association between P/E2 on the day of hCG administration and primary pregnancy outcomes was assessed using logistic regression analysis. Results: The rates of implantation (23.85–33.44%), clinical pregnancy (47.42–67.12%), ongoing pregnancy (40.83–61.48%), and live birth (34.40–57.65%) were significantly decreased in patients with a P/E2 < 0.25. These indicators were significantly associated with P/E2, but no significant correlation was observed between P/E2 and early spontaneous abortion rate. Conclusion: P/E2 < 0.25 on the day of hCG administration was associated with adverse pregnancy outcomes in extended treatments of gonadotropin-releasing hormone agonist IVF/ICSI

    The Impact of Residences and Roads on Wind Erosion in a Temperate Grassland Ecosystem: A Spatially Oriented Perspective

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    TUdi - Transforming Unsustainable management of soils in key agricultural systems in EU and China. Developing an integrated platform of alternatives to reverse soil degradation. Referencia del proyecto: 101000224. Partner/Coordinador principal: José Alfonso Gómez Calero – Instituto de Agricultura Sostenible IAS- CSIC.The existence of residences and roads is an important way in which human activity affects wind erosion in arid and semiarid environments. Studies assessing the impact of these elements on wind erosion have only focused on limited plots, and their threat of erosion to the surrounding environment has been ignored by many studies. This study was based on spatially overlayed analysis of independent wind erosion distribution simulated by the revised wind erosion equation (RWEQ) and remote-sensing-image-derived residence and road distribution data. Wind erosion at different distances from residences and roads was quantified at the landscape scale of a typical temperate grassland ecosystem, explicitly demonstrating the crucial impacts of both elements on wind erosion. The results showed that wind erosion weakened as the distance from residences and roads increased due to the priority pathways of human activities, and the wind erosion around the residence was more severe than around the road. Human activities in the buffer zones 0-200 m from the residences most frequently caused severe wind erosion, with a wind soil loss of 25 t ha-1 yr-1 and a wind soil loss of approximately 5.25 t ha-1 yr-1 for 0-60 m from the roads. The characteristics of wind erosion variation in the buffer zones were also affected by residence size and the environments in which the residences were located. The variation in wind erosion was closely related to the road levels. Human activities intensified wind erosion mainly by affecting the soil and vegetation around residences and roads. Ecological management should not be limited to residences and roads but should also protect the surrounding environments. The findings of this study are aimed towards a spatial perspective that can help implement rational and effective environmental management measures for the sustainability of wind-eroded ecosystems.This research was supported by the National Key R&D Program of China (2021YFD1500701, 2022YFE0115300), projects funded by the National Natural Science Foundation of China (41730748, 41301282), and projects supported by the State Key Laboratory of Earth Surface Processes and Resource Ecology, China (2022-KF-04, 2021-TS-07).Peer reviewe

    The Impact of Residences and Roads on Wind Erosion in a Temperate Grassland Ecosystem: A Spatially Oriented Perspective

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    The existence of residences and roads is an important way in which human activity affects wind erosion in arid and semiarid environments. Studies assessing the impact of these elements on wind erosion have only focused on limited plots, and their threat of erosion to the surrounding environment has been ignored by many studies. This study was based on spatially overlayed analysis of independent wind erosion distribution simulated by the revised wind erosion equation (RWEQ) and remote-sensing-image-derived residence and road distribution data. Wind erosion at different distances from residences and roads was quantified at the landscape scale of a typical temperate grassland ecosystem, explicitly demonstrating the crucial impacts of both elements on wind erosion. The results showed that wind erosion weakened as the distance from residences and roads increased due to the priority pathways of human activities, and the wind erosion around the residence was more severe than around the road. Human activities in the buffer zones 0&ndash;200 m from the residences most frequently caused severe wind erosion, with a wind soil loss of 25 t ha&minus;1 yr&minus;1 and a wind soil loss of approximately 5.25 t ha&minus;1 yr&minus;1 for 0&ndash;60 m from the roads. The characteristics of wind erosion variation in the buffer zones were also affected by residence size and the environments in which the residences were located. The variation in wind erosion was closely related to the road levels. Human activities intensified wind erosion mainly by affecting the soil and vegetation around residences and roads. Ecological management should not be limited to residences and roads but should also protect the surrounding environments. The findings of this study are aimed towards a spatial perspective that can help implement rational and effective environmental management measures for the sustainability of wind-eroded ecosystems

    Substitution Dependent Ultrafast Ultraviolet Energy Dissipation Mechanisms of Plant Sunscreens

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    An ultraviolet energy dissipation mechanism plays a critical role in the photoprotection effect of sunscreens. In this work, we discovered substitution dependent UV energy dissipation mechanisms of model plant sunscreen methyl sinapate (MS). We found that the initially populated V(pi pi*) states of MS and p-OMeMS relax to the ground state nonradiatively along an ultrafast trans-cis photoisomerization in tens of picoseconds. However, for p-HMS, an internal conversion from V(pi pi*) to a relative dark V'(pi pi*) state occurs in less than 1 ps, leading to a branching of the excited-state relaxations. The V (pi pi*) state still relaxes nonradiatively as in the case of MS and p-OMeMS. In contrast, the V'(pi pi*) state decays to the ground state mainly by emitting photons, exhibiting a lifetime as long as 5 ns. It is the first time to definitely distinguish the dynamics between V(pi pi*) and V'(pi pi*) states in the study of sinapates and cinnamates. These results indicate the anticipation of the V'(pi pi*) state should be avoided when designing sunscreens

    Ultrafast barrierless photoisomerization and strong ultraviolet absorption of photoproducts in plant sunscreens

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    Sunscreens are aimed at protecting skin from solar ultraviolet (UV) irradiation. By utilizing femtosecond transient absorption spectroscopy and time-dependent density functional theory, we explain nature's selection of sinapoyl malate rather than sinapic acid as the plant sunscreen molecule. In physiological pH conditions, the two molecules are deprotonated, and their excited pi pi* states are found to relax to the ground states in a few tens of picoseconds via a barrierless trans-cis photoisomerization. After the cis-photoproduct is formed, the efficacy of sinapic acid is greatly reduced. In contrast, the efficacy of sinapoyl malate is affected only slightly because the cis-product still absorbs UV light strongly. In addition, protonated sinapic acid is found to be a good potential sunscreen molecule
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