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Experimental evidence for field-induced metamagnetic transition of EuCd_(2)As_(2)

Journal of Rare Earths 2022年第10期40卷 1606-1610页

作者： Yingkai Sun Yong Li Shuaishuai Li Changjiang Yi Hanbin Deng xin du Limin Liu Changjiang Zhu Yuan Li Zheng Wang Hanqing Mao Youguo Shi Rui Wu Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBejing 100049China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China

Recent studies have shown that layered compound EuCd_(2)As_(2) could exhibit diverse topological states depending on the different magnetic structures,such as Weyl semimetal,Dirac semimetal and topological insulato r.In order to further study the interplay between magnetism and topology of EuCd_(2)As_(2),it is necessary to figure out its magnetic structure.Here,by magnetization(M) measurements and negative magnetostriction(λ) along the [001] direction measured by scanning tunneling microscopy on EuCd_(2)As_(2) single crystals,we observe field-induced metamagnetic phase transition from A-type antiferromagnetic(AFM) ground state to field-polarized state,with canted AFM(CAFM) state in between.Magnetization and magnetostriction are more sensitive to the in-plane field than the out-of-plane field,indicating the magnetic moments lying in the ab plane.The absence of abrupt jump on M-H and λ-H curves demonstrates that the phase transition is a second-order type.In CAFM state,M increases linearly with the field and λ is proportional to M~2.Tunneling conductance spectra show the field-induced evolution of the electronic density of states.Our results provide experimental evidence for understanding the magnetic structure of EuCd_(2)As_(2).

关键词： Metamagnetic phase transitions Magnetostriction Scanning tunneling microscopy/spectroscopy Rare earths

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Highly Enantioselective Reactions of Cyclohexanone and β,γ-Unsaturated α-Keto Ester: The Tuning of Chemoselectivities by Secondary and Primary Amine Catalysts

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Chinese Journal of Chemistry 2014年第10期32卷 985-990页

作者： Jianwei Wei Wengang Guo xin Zhou xin du Yan Liu Can Li State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalianLiaoning 116023China Department of Chemistry Dalian University of TechnologyDalianLiaoning 116024China

A series of of amphiphilic imidazole based secondary and primary amine catalysts were synthesized and shown to be very effective with an acid cocatalyst for the asymmetric reaction of cyclohexanone to β,γ-unsaturated α-keto ester.Interestingly,primary and secondary amine catalysts show different regio-selectivities in this reaction.Under the catalysis of secondary amine 1,excellent enantioselectivities were observed for the products from direct 3+3 reactions of cyclohexanone withβ,γ-unsaturated α-keto esters using water as the solvent.Moreover,the same reactants catalyzed by the primary amines 2 lead to the aldol reactions,affording the corresponding products with high diastereoselectivities and up to 97%ee.Theoretical studies on the transition states by using a model in gas phase revealed that steric effect plays an important role on different chemo-selective induction between the secondary amine 1 and primary amine 2.

关键词： emulsion catalysis asymmetric catalysis organocatalysis

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Universal and one-step visualization of latent fingermarks onvarious surfaces using hydrophilic cellulose membrane and dye aqueous solution

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Science China Chemistry 2017年第9期60卷 1250-1257页

作者： Qianhui Wei Xiaolong Li xin du Xueji Zhang Meiqin Zhang Research Center for Bioengineering&Sensing Technology University of Science&Technology BeoingBeijing 100083China

A high-resolution and universal method for the rapid visualization of latent fingermarks on a broad variety of surfaces has been achieved by simply combining hydrophilic cellulose membrane with dye aqueous solution.In this approach,the relatively hydrophobic characteristic of fingermark residue enable the deposit act as a "mask",directing dye absorption processes to regions of both furrows without the ridge residues and bare cellulose membrane substrate.This effect during the spatially selective dye absorption generates a negative pattern of the fingermark within a few seconds to minutes depending on the properties of the substrates and fingermark types.It provides observation of latent fingermarks on cellulose membrane surface with high definition of level 2 and level 3 details used for personal identification purposes.It is also highly-efficient for visualizing the latent fingermarks lifted from various common(glass,carton,ceramic cup) and problematic(banknote,human skin and leather) surfaces by using transparent adhesive tape.To examine the generality of the proposed method,eight different kinds of dye aqueous solutions have been tested for developing latent fingermarks and they all provide very good results as expected.Moreover,this approach is easily used for aged fingermarks and natural fingermarks as well.Imaging may be accomplished visibly(by dye color) and topographically(using a microscope or a camera).This approach is a simple,rapid,non-destructive,safe,low-cost,universal and high resolution method compared with conventional approaches,so it demonstrates good potentiality in individual identity validation related applications.

关键词： latent fingermarks visualization, cellulose membrane, dye solution, universal and high resolution, various substrates

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Comparative analysis reveals epigenomic evolution related to species traits and genomic imprinting in mammals

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The Innovation 2023年第3期4卷 91-101页

作者： Yisi Hu Shenli Yuan xin du Jiang Liu Wenliang Zhou Fuwen Wei CAS Key Laboratory of Animal Ecology and Conservation Biology Institute of ZoologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Center for Evolution and Conservation Biology Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)Guangzhou 511458China CAS Key Laboratory of Genome Sciences and Information Beijing Institute of GenomicsChinese Academy of SciencesBeijing 100101China

DNA methylation is an epigenetic modification that plays a crucial role in various regulatory processes,including gene expression regulation,transposable element repression,and genomic imprinting.However,most studies on DNA methylation have been conducted in humans and other model species,whereas the dynamics of DNA methylation across mammals remain poorly explored,limiting our understanding of epigenomic evolution in mammals and the evolutionary impacts of conserved and lineage-specific DNA methylation.Here,we generated and gathered comparative epigenomic data from 13 mammalian species,including two marsupial species,to demonstrate that DNA methylation plays critical roles in several aspects of gene evolution and species trait evolution.We found that the species-specific DNA methylation of promoters and noncoding elements correlates with species-specific traits such as body patterning,indicating that DNA methylation might help establish or maintain interspecies differences in gene regulation that shape phenotypes.For a broader view,we investigated the evolutionary histories of 88 known imprinting control regions across mammals to identify their evolutionary origins.By analyzing the features of known and newly identified potential imprints in all studied mammals,we found that genomic imprinting may function in embryonic development through the binding of specific transcription factors.Our findings show that DNA methylation and the complex interaction between the genome and epigenome have a significant impact on mammalian evolution,suggesting that evolutionary epigenomics should be incorporated to develop a unified evolutionary theory.

关键词： imprinting evolution mammals

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黄柏提取物的生物学功能及其在动物生产中的应用

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饲料工业 2024年第1期45卷 61-66页

作者：高阳马雪杜鑫白城师范学院生命科学学院吉林白城137000 吉林农业大学动物科学与技术学院吉林长春130118 扬州大学动物科学与技术学院江苏扬州225009

黄柏为芸香科植物黄皮树的干燥树皮,是我国传统的中草药。研究表明,黄柏提取物具有抗炎、抗氧化、抗菌、促进肠道健康、缓解应激和提高动物生产性能等功能。目前,新型抗生素替代添加剂产品的开发成为热点,黄柏提取物以其无药物残留、无... 详细信息

黄柏为芸香科植物黄皮树的干燥树皮,是我国传统的中草药。研究表明,黄柏提取物具有抗炎、抗氧化、抗菌、促进肠道健康、缓解应激和提高动物生产性能等功能。目前,新型抗生素替代添加剂产品的开发成为热点,黄柏提取物以其无药物残留、无耐药性等特点,在动物生产中也得到研究应用。文章综述了黄柏提取物的主要活性成分及结构、生物学功能与机制以及其在动物生产中的应用,以期为黄柏提取物在动物生产中的合理应用提供理论依据。

关键词：黄柏提取物生物学功能动物生产饲料添加剂

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Near-infrared light-driven yolk@shell carbon@silica nanomotors for fuel-free triglyceride degradation

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Nano Research 2021年第3期14卷 654-659页

作者： Yi xing Songsong Tang xin du Tailin Xu Xueji Zhang Research Center for Bioengineering and Sensing Technology Beijing Key Laboratory for Bioengineering and Sensing TechnologyDepartment of Chemistry&Biological EngineeringUniversity of Science&Technology BeijingBeijing100083China

Yolk@shell mesoporous nanoparticles have received close attention due to their controllable structures and integrated functions.However,most yolk@shell nanosystems lack self-propulsion.Herein,yolk@spiky-shell structured carbon@silica nanomotors are fabricated with near-infrared(NIR)light self-thermophoretic propulsion as lipase nanocarriers for fuel-free triglyceride degradation.The light propulsion accelerates the accumulation of nanomotors on the droplet interface,and the efficient lipase loading further facilitates the rapid degradation of tributyrin droplets.By adjusting the yolk and spiky structure,the obtained semi-yolk@spiky-shell structured nanomotors exhibit the highest capacity of lipase(442 mg/g)and the highest light-driven diffusion coefficient(ca.55%increase under 2 W/cm^(2 )irradiation),thus improving the degradation efficiency of triglyceride(93.1%under NIR light vs.66.7%without NIR light within 20 min).This work paves the way to rationally design yolk@shell structured nanomotors for diverse applications.

关键词： yolk@spiky-shell carbon@silica nanomotors self-thermophoresis triglyceride degradations

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云环境下工业信息物理系统现场层安全策略决策方法

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控制与决策 2024年第1期39卷 281-290页

作者：朱美潘杨健晖李欣格杜鑫周纯杰华中科技大学人工智能与自动化学院武汉430070 华中科技大学网络空间安全学院武汉430070

云环境下工业信息物理系统架构的转变使得工业现场设备更加暴露于网络攻击下,对工业现场层提出更高的安全需求.随着系统结构愈渐复杂,网络攻击更加智能,系统难以准确获取安全状态,传统的基于状态的安全决策方法将不能实现有效防护,对此... 详细信息

云环境下工业信息物理系统架构的转变使得工业现场设备更加暴露于网络攻击下,对工业现场层提出更高的安全需求.随着系统结构愈渐复杂,网络攻击更加智能,系统难以准确获取安全状态,传统的基于状态的安全决策方法将不能实现有效防护,对此提出一种工业信息物理系统现场层安全策略决策方法.首先,根据功能结构划分现场区域,分析潜在的攻击目标、攻击事件与系统防御策略间的关联性,构建攻击防御树;然后,从攻击和防护属性的视角,利用模糊层次分析法量化防御策略收益;接着,结合部分攻击状态构建部分可观的马尔可夫决策过程模型,通过求解模型得到最优安全策略;最后,以简化的田纳西-伊斯曼过程控制系统为对象验证所提出方法能够有效地决策出最优安全策略.

关键词：工业信息物理系统现场层安全策略决策部分可观的马尔可夫决策过程

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微型高压空压机动力学优化设计

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液压与气动 2024年第1期48卷 159-164页

作者：杜鑫李鹏飞庆安集团有限公司陕西西安710077

随着高压空气作为新型清洁动力源和冷却源的应用越来越多,微型高压压缩机便成为该领域研究的一项重点。传统的压缩机经验设计方法很难满足所有设计要求的最优方案。在传统热力设计的基础上,充分考虑压缩机的动力平衡特性,以各级缸径为... 详细信息

随着高压空气作为新型清洁动力源和冷却源的应用越来越多,微型高压压缩机便成为该领域研究的一项重点。传统的压缩机经验设计方法很难满足所有设计要求的最优方案。在传统热力设计的基础上,充分考虑压缩机的动力平衡特性,以各级缸径为主要设计变量,以各级气体力合力为优化目标开展多目标多变量优化研究。经过动力学优化设计,压缩机各级气体力相比传统设计更加均衡。气体力合力最大值降低了18.4%,合力的波动幅值降低了56.1%,同时指示功率也降低了4.2%。

关键词：微型高压空压机气体力动力学优化设计

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Quantitative extraction of the bedrock exposure rate based on unmanned aerial vehicle data and Landsat-80LI image in a karst environment

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Frontiers of Earth Science 2018年第3期12卷 481-490页

作者： Hongyan WANG Qiangzi LI xin du Longcai ZHAO Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences Beijing 100101 China

In the karst regions of southwest China, rocky desertification is one of the most serious problems in land degradation. The bedrock exposure rate is an important index to assess the degree of rocky desertification in karst regions. Because of the inherent merits of macro-scale, frequency, efficiency, and synthesis, remote sensing is a promising method to monitor and assess karst rocky desertification on a large scale. However, actual measurement of the bedrock exposure rate is difficult and existing remote-sensing methods cannot directly be exploited to extract the bedrock exposure rate owing to the high complexity and heterogeneity of karst environments. Therefore, using unmanned aerial vehicle （UAV） and Landsat-8 Operational Land Imager （OLI） data for xingren County, Guizhou Province, quantitative extraction of the bedrock exposure rate based on multi-scale remote-sensing data was developed. Firstly, we used an object-oriented method to carry out accurate classification of UAV images. From the results of rock extraction, the bedrock exposure rate was calculated at the 30 m grid scale. Parts of the calculated samples were used as training data; other data were used for model validation. Secondly, in each grid the band reflectivity ofLandsat-80LI data was extracted and a variety of rock and vegetation indexes （e.g., NDVI and SAVI） were calculated. Finally, a network model was established to extract the bedrock exposure rate. The correlation coefficient of the network model was 0.855, that of the validation model was 0.677 and the root mean square error of the validation model was 0.073. This method is valuable for wide-scale estimation of bedrock exposure rate in karst environments. Using the quantitative inversion model, a distribution map of the bedrock exposure rate in xingren County was obtained.

关键词： bedrock exposure rate quantitative extraction UAV and Landsat-80LI data karst rocky desertification

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数字时代创业加速器如何赋能新创企业成长?——基于海创汇的探索性案例研究

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华东经济管理 2024年第7期38卷 1-16页

作者：李志刚周琳杜鑫中国海洋大学管理学院山东青岛266100 中国海洋大学海洋发展研究院山东青岛266100 南开大学商学院天津300071

鉴于当下赋能研究难以诠释数字时代的组织间关联,文章以海创汇为研究对象,探究数字时代创业加速器赋能新创企业成长的情境、行为与结果。研究发现:基于企业成长时期演变,创业加速器的赋能情境分为新创企业“定位模糊”“规模约束”和“... 详细信息

鉴于当下赋能研究难以诠释数字时代的组织间关联,文章以海创汇为研究对象,探究数字时代创业加速器赋能新创企业成长的情境、行为与结果。研究发现:基于企业成长时期演变,创业加速器的赋能情境分为新创企业“定位模糊”“规模约束”和“路径依赖”三种类型;创业加速器历经“预加速—加速中—加速后”三个阶段,且各加速阶段的赋能维度机理存在明显差异;在新创企业接受赋能实现成长的背后,以创业加速器为主导的赋能互动关系从单向联动逐渐转为双向强联动的稳固关系。研究有助于拓展赋能理论的研究维度与理论内涵,也为数字时代创业加速器及新创企业的高质量发展提供实践启发。

关键词：创业加速器赋能理论新创企业数字技术企业成长组织间关系

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