检索结果-南通市图书馆

Metal-Free Synthesis of 2-Aminobenzothiazoles via I2-Catalyzed Tandem Cyclization Reaction of Amines and Carbon Disulfide

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2024年第8期42卷 846-852页

作者： Ting chen wei Feng Ruitong Yang Shanping chen Guo-Jun Deng Key Laboratory for Green Organic Synthesis and Application of Hunan Province Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of EducationCollege of ChemistryXiangtan UniversityXiangtanHunan411105 China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiangHunan453007 China

Comprehensive Summary,A convenient approach for the construction of 2-aminobenzothiazoles via I2-catalyzed tandem cyclization reaction of amines and carbon disulfide has been *** present approach starts from simple and readily available starting materials,affording a series of 2-aminobenzothiazoles in up to 89%yields under metal-free *** this work,C—H/N—H functionalization was achieved and multiple C-hetero bonds were successfully constructed in one pot.

关键词： Sulfur heterocycles C-H functionalization Cyclization Tandem reaction Transition-metal-free Amines lodine N-Heterocycles

Unveiling the secrets of diatom-mediated calcification:Implications for the biological pump

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第9期67卷 2895-2909页

作者： Yiwen PAN Yifan LI chen-Tung Arthur chen Zong-Pei JIANG wei-Jun CAI Yunwen SHEN Zesheng DING Qixian chen Yanan DI wei FAN chenba ZHU Ying chen Ocean College Zhejiang UniversityZhoushan 316021China Hainan Institute of Zhejiang University Sanya 570203China Department of Oceanography Sun Yat-Sen UniversityGaoxiong 80424China School of Marine Science and Policy University of DelawareNewark DE 19716USA Carbon Neutral Innovation Research Center Xiamen UniversityXiamen 361005China

Siliceous diatoms are one of the most prominent actors in the oceans,and they account for approximately 40%of the primary production and particulate organic carbon export *** is believed that changes in carbon flux caused by variations in diatom distribution can lead to significant climate *** the fundamental pathways of diatom-driven carbon sequestration have long been established,there are no reports of CaCO_(3) precipitation induced by marine diatom *** manuscript introduces novel details regarding the enhancement of aragonite precipitation during photosynthesis in Skeletonema costatum in both artificial and natural *** direct measurements of cell surfaces via a pH microelectrode and zeta potential analyzer,it was determined that the diatom-mediated promotion of CaCO_(3) precipitation is achieved through the creation of specific microenvironments with concentrated[CO_(3)^(2-)]and[Ca^(2+)]and/or the dehydrating effect of adsorbed Ca^(2+).Based on this mechanism,it is highly plausible that diatom-mediated calcification could occur in the oceans,an assertion that was supported by the significant deviation of total alkalinity(TA)from the conservative TA-salinity mixing line during a Skeletonema costatum bloom in the East China Sea and other similar *** newly discovered calcification pathway establishes a link between particulate inorganic and organic carbon flux and thus helps in the reassessment of marine carbon export fluxes and CO_(2) sequestration *** discovery may have important ramifications for assessing marine carbon cycling and predicting the potential effects of future ocean acidification.

关键词： Diatom bloom Skeletonema costatum Calcification Biological carbon pump Counter carbonate pump

Building Semantic Communication System via Molecules:An End-to-End Training Approach

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第7期21卷 113-124页

作者： cheng Yukun chen wei Ai Bo School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing 100091China Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong UniversityBeijing 100091China Key Laboratory of Railway Industry of Broadband Mobile Information Communications Beijing Jiaotong UniversityBeijing 100091China Beijing Engineering Research Center of High-speed Railway Broadband Mobile Communications Beijing Jiaotong UniversityBeijing 100091China School of Information Engineering Zhengzhou UniversityZhengzhou 450001China

The concept of semantic communication provides a novel approach for applications in scenarios with limited communication *** this paper,we propose an end-to-end(E2E)semantic molecular communication system,aiming to enhance the efficiency of molecular communication systems by reducing the transmitted ***,following the joint source channel coding paradigm,the network is designed to encode the task-relevant information into the concentration of the information molecules,which is robust to the degradation of the molecular communication ***,we propose a channel network to enable the E2E learning over the non-differentiable molecular *** results demonstrate the superior performance of the semantic molecular communication system over the conventional methods in classification tasks.

关键词： deep learning end-to-end learning molecular communication semantic communication

Preparation of yttrium oxide coating with enhanced thermal shock resistance on refractories used for titanium alloy melting and casting

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第6期31卷 1411-1422页

作者： Ao chen Yan Ma Zhou-fu Wang Hao Liu Xi-tang Wang Sen-na chen chen-xin Zhang Zi-yi Tang wei-dong Fu wei cheng The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Xiangyang Juli High Technology Material Co. Ltd.Xiangyang 441705HubeiChina Xiangyang Public Inspection and Testing Center Xiangyang 441000HubeiChina

In order to enhance the service life of refractories for melting and casting of titanium alloy,preparation of yttrium oxide coatings on the refractories surface is an effective *** improvement of thermal shock stability of the coating is beneficial to its spalling resistance during the high-temperature service,and the available slurry with good performance is the *** effects of the varieties and contents of dispersant(sodium tripolyphosphate,sodium hexametaphosphate,sodium pyrophosphate,citric acid and polycarboxylate ammonium salt)and binder(aluminum dihydrogen phosphate,zirconium acetate and yttria sol)on the stability,rheological and thixotropic properties of yttrium oxide waterbased slurry were investigated,and the effects of slurry composition design on the thermal shock resistance of the coating were *** results showed that the introduction of polycarboxylate ammonium salt as dispersant significantly improved the stability of the slurry,and the varieties of the binders had significant effects on the dispersibility of the *** aluminum dihydrogen phosphate and polycarboxylate ammonium salt were used as binder and dispersant,respectively,the slurry had better stability,suitable rheological and thixotropic *** using aluminum dihydrogen phosphate as binder,the coating had good thermal shock resistance and no obvious cracks were observed for the coating after thermal shock,which was attributed to the yttrium aluminate binding phase generated in the *** effective method was provided for preparing yttrium oxide coatings with enhanced thermal shock resistance applied in the process of titanium alloy melting and casting.

关键词： Yttrium oxide-Slurry Stability Rheological property Thixotropic property-Coating Thermal shock resistance

High-resolution tsunami hazard assessment for the Guangdong-Hong Kong-Macao Greater Bay Area based on a non-hydrostatic tsunami model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第7期67卷 2326-2351页

作者： Yifan ZHU Chao AN Houyun YU wei ZHANG Xiaofei chen Key Laboratory of Hydrodynamics(Ministry of Education) School of Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Department of Earth and Space Sciences Southern University of Science and Technology Shenzhen 518055China

The Guangdong-Hong Kong-Macao Greater Bay Area(GBA)is threatened by potential tsunami hazards from the Littoral Fault Zone(LFZ)and the Manila subduction zone(MSZ),and may suffer huge damage because of its dense population,concentrated infrastructure,and low-lying *** tsunami studies for the GBA made simple assumptions on the mechanisms of LFZ earthquakes,and used coarse bathymetry data in tsunami simulation,which limited the prediction of detailed tsunami hazard *** this paper,we develop a parallel dispersive tsunami model PCOMCOT to efficiently simulate dispersive,nonlinear,and breaking tsunami *** also construct large-scale and high-resolution bathymetry models for the GBA by correcting and integrating various data *** rupture simulation is performed for the LFZ to obtain a more reliable earthquake source *** propose several representative earthquake scenarios for the LFZ and MSZ,and use PCOMCOT to calculate the resulting tsunami waves,currents,and inundation in the *** results indicate that if an M_(w)7.5 oblique-slip earthquake occurs in the LFZ off the Pearl River Estuary(PRE),the subsequent tsunami will primarily impact Hong Kong,causing maximum positive and negative waves of around 1 m and -2 m,respectively,along with slightly destructive currents(≥1.5 m/s).An M_(w)9.0 MSZ megathrust earthquake can lead to widespread inundation with>1 m depth on the outlying islands of Macao and in the urban areas of Hong Kong around the Victoria ***,it will also cause catastrophic tsunami currents along the narrow waterways in Hong Kong and Macao,and the spatial distribution of strong currents(≥3 m/s)shows a considerable discrepancy from the areas of serious ***,more attention should be paid to the potential impacts of tsunami currents on the GBA.

关键词： Tsunami hazards Inundation Tsunami currents Non-hydrostatic model Guangdong-Hong Kong-Macao Greater Bay Area

Molecular dynamics simulation study of nitrogen vacancy color centers prepared by carbon ion implantation into diamond

在线全文

学校读者我要写书评

暂无评论

Nanotechnology and Precision Engineering 2024年第3期7卷 71-78页

作者： wei Zhao Zongwei Xu Pengfei Wang Hanyi chen State Key Laboratory of Precision Measuring Technology and Instruments Tianjin UniversityTianjin 300072China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

Nitrogen vacancy(NV)color centers in diamond have useful applications in quantum sensing andﬂuorescent *** can be gen-erated experimentally by ion implantation,femtosecond lasers,and chemical vapor ***,there is a lack of studies of the yield of NV color centers at the atomic *** the molecular dynamics simulations described in this paper,NV color centers are pre-pared by ion implantation in diamond with pre-doped nitrogen and subsequent *** differences between the yields of NV color centers produced by implantation of carbon(C)and nitrogen(N)ions,respectively,are *** is found that C-ion implantation gives a greater yield of NV color centers and superior location *** effects of different pre-doping concentrations(400–1500 ppm)and implantation energies(1.0–3.0 keV)on the NV color center yield are analyzed,and it is shown that a pre-doping concentra-tion of 1000 ppm with 2 keV C-ion implantation can produce a 13%yield of NV color centers after 1600 K annealing for 7.4 ***,a brief comparison of the NV color center identiﬁcation methods is presented,and it is found that the error rate of an analysis utiliz-ing the identify diamond structure coordination analysis method is reduced by about 7%compared with conventional identiﬁcation+methods.

关键词： NV color center Ion implantation Molecular dynamics(MD)simulation Yield enhancement

Can Industrial Structure Upgrading Restrain Industrial Land Expansion?Evidence from China

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2024年第3期34卷 504-518页

作者： chen wei LI Qiao ZHANG Sun ZHOU Xue College of Economics and Management Northwest A&F UniversityYangling Shaanxi 712100China Institute of Geographic Sciences&Natural Resources Research Chinese Academy of SciencesBeijing 100101China

China has made great achievements in industrial development and is transforming into a powerful manufacturing ***,the industrial land scale is also ***,whether industrial structure upgrading achieves the purpose of restraining industrial land expansion remains *** calculating the industrial land structure index(ILSI)and industrial land expansion scale(ILES),this study analyzed their temporal and spatial distribution characteristics at both regional and city levels from 2007to 2020 in *** show that industrial land expansion presents a different trend in the four regions,the ILES in the eastern region is the largest,and the speed of industrial land expansion has declined since 2013,but it has gradually increased since *** ILSI of the eastern and central regions is higher than that of the western and northeastern ***,a spatial Durbin model(SDM)has been established to estimate the spatial effect of industrial structure upgrading on industrial land expansion from 2007 ***,industrial structure upgrading has not slowed industrial land *** eastern and western regions require a greater amount of industrial land while upgrading the industrial *** improvement of the infrastructure level and international trade level has promoted industrial land expansion.

关键词： industrial development industrial structure upgrading industrial land expansion regional differences China

Shear strength degradation of gas hydrate-bearing sediment due to partial hydrate dissociation

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2749-2763页

作者： Yuan Zhou Jiazuo Zhou Pan chen Changfu wei State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China China University of Geosciences Wuhan430074China

Extraction of methane hydrate from subseafloor reservoir may potentially trigger seabed slides and induce *** address the problems,it is crucial to properly characterize the phase equilibrium condition of pore hydrate and the shear strength of the *** one of the key constitutive components,the phase equilibrium condition enforces a constraint over pore gas pressure,temperature and unhydrated water *** a constraint,however,has been traditionally ignored in analyzing the mechanical behavior of hydrate-bearing *** this paper,a series of stepwise hydrate dissociation tests was performed,and the phase equilibrium condition of pore hydrate was determined,providing an effective way to evaluate the unhydrated water content during hydrate ***,a series of direct shear tests was also conducted to explore the shear strength characteristics of the *** is shown that the shear strength of the hydrate-bearing soil can be significantly influenced by pore gas pressure,unhydrated water content,hydrate saturation and several other *** particular,the measured shear strength depends upon the initial water content of the sample,pointing to a potential problem that the shear strength could be wrongly determined if not properly interpreted.A shear strength criterion,which enforces the equilibrium condition of pore hydrate,is developed for hydrate-bearing soil,establishing a link between the equilibrium condition and the shear *** proposed equation describes well the shear strength characteristics of hydrate-bearing soils,remarkably unifying the effects of pore pressure,temperature,water content and hydrate saturation.

关键词： Hydrate-bearing soil Phase equilibrium condition Shear strength Unhydrated water content Mechanical behavior

Constructing the metabolic network of wheat kernels based on structure-guided chemical modification and multi-omics data

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Genetics and Genomics 2024年第7期51卷 714-722页

作者： Zhitao Tian Jingqi Jia Bo Yin wei chen National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research(Wuhan) Huazhong Agricultural UniversityWuhanHubei 430070China Hubei Hongshan Laboratory WuhanHubei 430070China

Metabolic network construction plays a pivotal role in unraveling the regulatory mechanism of biological activities,although it often proves to be challenging and labor-intensive,particularly with non-model *** this study,we develop a computational approach that employs reaction models based on the structure-guided chemical modification and related compounds to construct a metabolic network in *** construction results in a comprehensive structure-guided network,including 625 identified metabolites and additional 333 putative reactions compared with the Kyoto Encyclopedia of Genes and Genomes *** a combination of gene annotation,reaction classification,structure similarity,and correlations from transcriptome and metabolome analysis,a total of 229 potential genes related to these reactions are identified within this *** validate the network,the functionality of a hydroxycinnamoyltransferase(TraesCS3D01G314900)for the synthesis of polyphenols and a rhamnosyltransferase(TraesCS2D01G078700)for the modification of flavonoids are verified through in vitro enzymatic studies and wheat mutant tests,*** research thus supports the utility of structure-guided chemical modification as an effective tool in identifying causal candidate genes for constructing metabolic networks and further in metabolomic genetic studies.

关键词： Metabolic network Chemical modification Genetic study Wheat kernel Multi-omics