The graphite arc-discharge in the presence of CCl4: Chlorinated carbon clusters in relation with fullerenes formation

通讯作者地址: Xie, SY (通讯作者), Xiamen Univ, Dept Chem, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Dept Chem, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Wuhan Univ, Dept Chem, Wuhan 430072, Peoples R ChinaThe graphite arc-discharge in the atmosphere consisting of CCl4 40 Torr and increasing partial pressure of He from 0 to 300 Torr produced, in addition to carbon species such as graphite and fullerenes C60 and C70, numerous chlorinated carbon clusters (CCCs). The yields of some CCCs, including C6Cl6 (perchlorobenzene), C10Cl8 (perchloronaphthalene), C12Cl8 (perchloroacenaphthylene) and C12Cl8 (isomer II), C14Cl8 (isomer I), C16Cl10 (perchlorofluoranthene), C18Cl10 (isomer I and II), and C20Cl10 (isomer I), correspond well with C60 yields, which may imply these CCCs share the same growth mechanism with fullerenes. Such a yield correlation can be used to distinguish the fullerene precursors from the irrelevant by-products, thus contributes to the mechanistic study of fullerene formation

产量与经济效益共赢的高效生态农业模式:以弘毅生态农场为例

化学物质的大量投入以及元素不能循环导致农田生态系统退化,耕地质量和产量均呈下降趋势,食物链受到污染.本研究从低产田开始,通过秸秆养牛、腐熟牛粪还田恢复地力;以物理+生物方法控制虫害;以人工+机械管理杂草,停用农药、化肥和除草剂,同时不用地膜、人工合成激素、转基因种子生产优质安全食品,并在线上与线下销售.10年的长期实验结果表明,所在村庄农田生态环境改善,减少农药用量58.3%;物理+生物控虫效果明显,每盏灯年捕获量从2009年的33 kg下降到2014年的2.1 kg,下降93.8%;年消耗秸秆1000 t,秸秆利用率从1.1%提高到62.5%.有机肥还田提高了土壤生物多样性,有机果园蚯蚓数量317条m~(-2),而普通果园只有16条m~(-2);大量有机肥还田(75 t hm~(-2)),土壤有机质从实验初期的0.7%提高到2.4%.粮食产量从最初的11.43 t hm~(-2)提高到目前的17.43 t hm~(-2),其中冬小麦(Triticum aestivum)、夏玉米(Zea mays)、大豆(Glycine max(Linn.)Merr.)和花生(Arachis hypogaea Linn.)产量分别超出山东省平均水平42.6%,60.9%,32.2%和38.1%.由于质量好,产品已销售往除西藏以外的30个省、市、自治区,经济效益明显,平均每公顷效益是普通农田的3~5倍,带动所在村庄67户农民从事高效生态农业.本研究可为国家制定生态农业发展规划、精准扶贫、农村环境保护等提供科学依据

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements