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Solid-state phase transformations toward a metal-organic framework of 7-connected Zn_(4)0 secondary building units

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Nano Research 2021年第2期14卷 411-416页

作者： Jaehui Kim Junsu ha Jae Hwa Lee Hoi ri Moon Department of Chemistry Ulsan National Institute of Science and Technology(UNIST) Ulsan 44919Republic of Korea

In the development of metal-organic frameworks(MOFs),secondary building units(Sbus)have been utilized as molecular modules for the construction of nanoporous materials with robust *** solvothermal synthetic conditions,dynamic changes in the metal coordination environments and ligand coordination modes of Sbus determine the resultant product ***,MOF phases with new topologies can also be achieved by post-synthetic treatment of as-synthesized MOFs via the introduction of acidic or basic moieties that cause the simultaneous cleavage/reformation of coordination bonds in the solid *** this sense,we studied the solid-state transformation of two ndc-based Zn-MOFs(ndc=1,4-naphthalene dicarboxylate)with different Sbus but the same pcu topology to another MOF with sev *** of the chosen MOFs with pcu nets is[Zn_(2)(ndc)_(2)(bpy)]_(n)(bpy=4,4,-bipyridine),(6C_(bpy)-MOF)consisting of a 6-connected pillared-paddlewheel Sbu,and the other is IRMOF-7 composed of 6-connected Zn40(C 00)6 Sbus and *** post-structural modification,these pcu MOFs were converted into the same MOF with sev topology constructed from the uncommon 7-connected Zri_(4)O(COO)_(7)Sbu(7C-MOF).The appropriate post-synthetic conditions for the transformation of each Sbus were systematically *** addition,the effect of the pillar molecules in the pillared-paddlewheel MOFs on the topology conversion was studied in terms of the linker basicity,which determines the inertness during the solid-state phase *** post-synthetic modification approach is expected to expand the available methods for designing and synthesizing MOFs with controlled topologies.

关键词： metal-organic framework secondary building units solid-state transform ation linker basicity ligand addition reaction

青藏高原重要交通国道路侧土壤重金属分布特征及生态风险评价

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环境科学 2024年第8期45卷 4825-4836页

作者：南维鸽董治宝薛亮张智哈延庆邵天杰陕西师范大学地理科学与旅游学院西安710119

为了阐明交通对青藏高原敏感脆弱生态系统和主要生态安全屏障功能的影响,在G214、G213、G345、G109、G316和G317等国道部分路段,采集路边0~25 m范围内土壤样品,分析6种土壤重金属含量及分布特征,运用单因子污染指数法(P_(i))、内梅罗综... 详细信息

为了阐明交通对青藏高原敏感脆弱生态系统和主要生态安全屏障功能的影响,在G214、G213、G345、G109、G316和G317等国道部分路段,采集路边0~25 m范围内土壤样品,分析6种土壤重金属含量及分布特征,运用单因子污染指数法(P_(i))、内梅罗综合指数法(P_N)及潜在生态风险指数法(ri)对路侧土壤重金属的污染程度及潜在生态风险进行综合评价.结果表明,青藏高原重要交通国道路侧土壤重金属ω(As)、ω(Cd)、ω(Hg)、ω(Ni)、ω(Pb)和ω(Zn)分别介于5.65~176.00、0.04~0.27、0.01~0.14、9.52~113.00、9.16~54.50和24.70~109.00 mg·k^(-1),呈高度变异,部分采样路段存在As、Cd和Hg元素高于当地土壤背景值.路侧土壤重金属单因子污染指数大小为:P_(i)(As)>P_(i)(Hg)>P_(i)(Cd)>P_(i)(Pb)>P_(i)(Ni)>P_(i)(Zn),内梅罗综合污染指数在0.41~9.20,平均值为1.53,属于清洁或轻度污染,局部处于中度或重度污染.研究路段综合潜在生态风险指数平均值为106.2,土壤总体处于无污染和轻度污染,仅有两个路段的土壤重金属富集达到中等及强度生态危害,其G213a土壤综合潜在风险指数显示为中度至重度生态危害,主要受到Hg、As和Cd的影响,G317土壤综合潜在风险指数显示为轻度至中度生态危害,主要受到Hg和Cd的影响.青藏高原路侧土壤重金属含量与路侧距离及土壤深度没有显著相关性,与年均气温呈显著正相关(P<0.05).青藏高原道路建设人为活动剧烈、交通流量较大的区域有土壤重金属富集趋势.

关键词：青藏高原道路交通土壤重金属路侧分布特征生态风险评价

基于cytb和rag2基因探讨叶须鱼属分子系统进化关系

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四川农业大学学报 2024年第1期42卷 140-148页

作者：陈鲆曾如奎杨德英哈西罗文杰徐丹刘飞秦云鑫熊金鑫丁文祥黄俊杰刘日唐子婷何智严太明四川农业大学动物科技学院成都611130 长江上游鱼类资源与环境四川省野外科学观测研究站成都611130 雅砻江流域水电开发有限公司成都610051

【目的】探究叶须鱼属的分子系统进化关系,筛选种间鉴定分子标记。【方法】构建叶须鱼属的cytb(5个种)和rag2(修长叶须鱼和裸腹叶须鱼)基因序列的NJ及贝叶斯系统进化树,并结合核苷酸多态位点、单倍型、核酸多态性、遗传距离、遗传分化... 详细信息

【目的】探究叶须鱼属的分子系统进化关系,筛选种间鉴定分子标记。【方法】构建叶须鱼属的cytb(5个种)和rag2(修长叶须鱼和裸腹叶须鱼)基因序列的NJ及贝叶斯系统进化树,并结合核苷酸多态位点、单倍型、核酸多态性、遗传距离、遗传分化系数和基因流等,分析种间进化关系和种内遗传多样性。【结果】叶须鱼属每个种的cytb序列单独聚为一支,表明cytb基因序列能将叶须鱼属5个种区分开;种间高度遗传分化(F_(st)>0.25),物种之间基因流较弱(Nm<1);修长叶须鱼遗传多样性水平最高,锥吻叶须鱼遗传多样性水平最低。基于rag2基因序列的分子系统发育进化树显示,修长叶须鱼和裸腹叶须鱼均单独聚为一支,为独立的种。【结论】cytb和rag2可作为叶须鱼属种间鉴定的分子标记基因,这为叶须鱼属物种的鉴定和系统分类奠定了基础,也为叶须鱼属鱼类保护措施的制定提供了遗传学依据。

关键词：叶须鱼属 cytb基因 rag2基因系统发育关系遗传多样性

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基于连续小波变换和机器学习的小麦产量预测

光谱学与光谱分析 2024年第10期44卷 2890-2899页

作者：樊杰杰邱春霞樊意广陈日强刘杨边明博马彦鹏杨福芹冯海宽西安科技大学测绘科学与技术学院陕西西安710054 农业农村部农业遥感机理与定量遥感重点实验室北京市农林科学院信息技术研究中心北京100097 南京农业大学国家信息农业工程技术中心江苏南京210095 河南工程学院土木工程学院河南郑州451191

及时、准确的作物估产,对作物管理决策和粮食安全评估具有重要意义。该研究在建立一种耦合连续小波变换(CWT)与机器学习准确预测小麦产量的方法。基于2020年—2021年两年小麦田间试验获取的开花期和灌浆期冠层高光谱数据及产量数据,首... 详细信息

及时、准确的作物估产,对作物管理决策和粮食安全评估具有重要意义。该研究在建立一种耦合连续小波变换(CWT)与机器学习准确预测小麦产量的方法。基于2020年—2021年两年小麦田间试验获取的开花期和灌浆期冠层高光谱数据及产量数据,首先采用CWT提取三种小波特征(WFs),分别为:基于Bortua方法筛选的特征波段(Bortua-WFs)、提取WFs与小麦产量确定系数的前1%(1%R^(2)-WFs)和单一分解尺度下的所有WFs(SS-WFs)。然后采用随机森林(RF)、 K最邻近(KNN)和极端梯度提升(XGBoost)三种机器学习算法构建产量预测模型。最后选取最优的光谱特征,采用相同的方法进行建模并比较。结果表明:(1)三种WFs结合机器学习方法的模型均表现良好,基于Bortua-WFs构建的模型具有更高的精度和稳定性。(2)相比光谱特征模型,Bortua-WFs模型在各生育期的精度均有所提高,开花期的R^(2)精度分别提高了17.5%、 4%和39.6%,灌浆期分别提高了8.4%、 5.6%和16.9%。(3)灌浆期的产量估算模型优于开花期,结合Bortua-WFs和XGBoost的模型表现最佳,R^(2)为0.83, RMSE为0.78 t·ha^(-1)。该研究比较了不同特征和方法相结合的性能,确定了不同方案下的最佳模型精度,为光谱准确预测小麦产量提供技术参考。

关键词：连续小波变换高光谱机器学习小麦产量预测

Optimizing agronomic practices for closing rapeseed yield gaps under intensive cropping systems in China

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Journal of Integrative Agriculture 2020年第5期19卷 1241-1249页

作者： ZhaNG Zhi CONG ri-huan REN Tao LI Hui ZHU Yun LU Jian-wei College of Resources and Environment Huazhong Agricultural University/Key Laboratory of Arable Land Conservation(Middle and Lower Reaches of Yangtze River)Ministry of Agriculture and Rural AffairsWuhan 430070P.R.China Key Laboratory of Fertilization from Agricultural Wastes Ministry of Agriculture and Rural Affairs/Institute of Plant Protection and Soil FertilizerHubei Academy of Agricultural SciencesWuhan 430064P.R.China

A yield gap analysis for rapeseed(Brassica napus L.) is critical to meeting the oil demand by identifying yield potential and yield constraints. In this study, potential yield(Y_p), attainable yield(Y_(att)), and actual yield(Y_(act)) for winter rapeseed were determined in five different zones of China. A boundary line approach was adopted to calculate Y_p, based on a large-scale field experimental database. A meta-analysis was conducted on the data obtained from 118 published studies to evaluate the effects of agronomic factors on rapeseed yield. The main results indicated that farmers only achieved 37–56% of the yield potential across the zones. The low altitude areas(L-URY) and lower reaches(LRY) of the Yangtze river Basin(YRB), China had high yield levels. The total yield gap was 1 893 kg ha^(–1), due to the agronomic management factors, environmental factors, and socioeconomic factors. The meta-analysis showed that weed control and drainage were the best management practices to improve yields(45.6 and 35.3%, respectively), and other practices improved yields by 17.1–21.6%. Consequently, to narrow the yield gap over the short term, the study could focus on techniques that are easily implemented to farmers.

关键词： rapeseed yield gap potential yield boundary line meta-analysis Yangtze river Basin

Study on SCR De NO_x mechanism through in situ electrical conductivity measurements on V_2O_5-WO_3/TiO_2 catalysts

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Rare Metals 2006年第Z2期25卷 77-83页

作者： ha Heon Phil JUNG Soon Hyo LEE Jun Yub HONG Sung Ho Metal Processing Research Center Korea Institute of Science and Technology Cheongryang Seoul 130-650 Republic of Korea Power Engineering Research Institute Korea Power Engineering Company Inc. 360-9 Mabuk-ri Guseong-eup Yongin-si Gyeonggi-do 449-713 Republic of Korea

V2O5-WO3/TiO2 catalysts were prepared by impregnation method and in situ electrical conductivity measurements were carried out to investigate the reaction mechanism for ammonia SCR (selective catalytic reduction) of NOx. The electrical conductivity change with ammonia supply and the increase of electrical conductivity were mainly caused by reduction of the labile surface oxygen. The electrical conductivity change of catalysts shows close relationship with the conversion rate of NOx. Variation of conversion rate in atmosphere without gaseous oxygen also supports that the labile lattice oxygen is indispensable in the initial stage of the de NOx reaction. These results suggest that the liable lattice oxygen acts decisive role in the de NOx mechanism. They also support that De NOx reaction occurs through the Eley-rideal type mechanism. The amount of labile oxygen can be estimated from the measurement of electrical conductivity change for catalysts with ammonia supply.

关键词： De NOx selective catalytic reduction electrical conductivity lattice oxygen

Evaluation of nitrogen requirement and efficiency of rice in the region of Yangtze river Valley based on large-scale field experiments

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Journal of Integrative Agriculture 2015年第10期14卷 2090-2098页

作者： CONG ri-huan ZhaNG Zhi LU Jian-wei LI Xiao-kun REN Tao WANG Wei-ni Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze river) Ministry of Agriculture/College of Resources and Environmental Sciences Huazhong Agricultural University

Overestimation of nitrogen（N） uptake requirement is one of the driving forces of the overuse of N fertilization and the low efficiency of N use in China. In this study, we collected data from 1 844 site-years of rice（Oryza sativa L.） under various rotation cropping systems across the Yangtze river Valley. Selected treatments included without（N0 treatment） and with N application（N treatment） which were recommended by local technicians, with a wide grain range of 1.5–11.9 t ha–1. Across the 1 844 site-years, over 96% of the sites showed yield increase（relative yield〉105%） with N fertilization, and the increase rates decreased from 78.9 to 16.2% within the lowest range 〈4.0 to the highest 〉6.5 t ha–1. To produce one ton of grain, the rice absorbed approximately 17.8 kg N in the N0 treatment and 20.4 kg N in the N treatment. The value of partial factor productivity by N（PFP N） reached a range of 35.2–51.4 kg grain kg–1 with N application under the current recommended N rate. Averaged recovery rate of N（RE N） was above 36.0% in yields below 6.0 t ha–1 and lower than 31.7% in those above 6.0 t ha–1. Soil properties only affected yield increments within low rice yield levels（〈5.5 t ha–1）. There is a poor relationship between N application rates and indigenous nitrogen supply（INS）. From these observations and considering the local INS, we concluded there was a great potential for improvement in regional grain yield and N efficiency.

关键词： nitrogen fertilization yield increment N uptake requirement N efficiency rice

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上市公司资产出售对财务绩效影响的实证研究

经济研究导刊 2021年第30期 81-83页

作者：哈布日吴继忠上海理工大学上海200093

资产出售是上市公司通过调动投资而进行资产重新配置的经济活动,国外已经广泛应用,并对公司的绩效产生了正向影响。国内资本市场近年来在不断地发展完善,为了优化上市公司的内部资源配置,提升公司的核心竞争力,上市公司也纷纷采取资产... 详细信息

资产出售是上市公司通过调动投资而进行资产重新配置的经济活动,国外已经广泛应用,并对公司的绩效产生了正向影响。国内资本市场近年来在不断地发展完善,为了优化上市公司的内部资源配置,提升公司的核心竞争力,上市公司也纷纷采取资产出售这一方式。通过选取2015—2019年间333家上市公司的资产出售事件为研究样本,实证分析研究资产出售对上市公司财务绩效的影响。研究结果显示,分析论证后得出资产出售数额的大小与资产出售的相对交易价值对公司财务绩效有正向影响,股权集中度与上市公司资产出售的财务绩效成正比,而股权制衡度则与上市公司资产出售的财务绩效成反比。

关键词：上市公司资产出售财务绩效实证研究

Morphological and serum hyaluronic acid, laminin and type Ⅳ collagen changes in dimethylnitrosamine-induced hepatic fibrosis of rats

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World Journal of Gastroenterology 2005年第48期11卷 7620-7624页

作者： Chun-Hui Li Dong-Ming Piao Wen-Xie Xu Zheng-ri Yin Jing-Shun Jin Zhe-Shi Shen Department of Pathology Affiliated Hospital of Yanbian University College of Medicine Yanji 133000 Jilin Province China Department of Physiology College of Medicine Shanghai Jiaotong University Shanghai 200030 China Affiliated Hospital of Chengde Medical College Chengde 067000 Hebei Province China

AIM： To study the morphological and serum hyaluronic acid （ha）, laminin （LN）, and type IV collagen changes in hepatic fibrosis of rats induced by dimethylnitrosamine （DMN）.METHODS： The rat model of liver fibrosis was induced by DMN. Serum ha, type IV collagen, and LN were measured by ELISA. The liver/weight index and morphological changes were examined under electron microscope on d 7, 14, 21, and 28 by immunohistochemical alpha smooth muscle actin α-SMA staining as well as Sirius-red and HE ***： The levels of serum ha, type IV collagen and LN significantly increased from d 7 to d 28 （P = 0.043）. The liver/weight index increased on d 7 and decreased on d 28. In the model group, the rat liver stained with lie and Sirius-red showed evident hemorrhage and necrosis in the central vein of hepatic 10 Iobules on d 7. Thin fibrotic septa were formed joining central areas of the liver on d 14. The number of α-SMA positive cells was markedly increased in the model group. Transitional hepatic stellate cells were observed under electron microscope. All rats in the model group showed micronodular fibrosis in the hepatic parenchyma and a network of α-SMA positive cells. Typical myofibroblasts were embedded in the core of a fibrous septum. Compared to the control group, the area-density percentage of collagen fibrosis and pathologic grading were significantly different in the model group （P〈0.05） on different d （7, 14, and 28）. The area-density percentage of collagen fibrosis in hepatic tissue had a positive correlation with the levels of serum ha, LN, and type IV ***： The morphological and serum ha, type IV collagen, and LN are changed in DMN-induced liver fibrosis in rats.

关键词： Rat Hepatic fibrosis DMN Morphologicalchange Serum Experimental studies