检索结果-南通市图书馆

Auto Machine Learning Assisted Preparation of Carboxylic Acid by tempo-Catalyzed Primary Alcohol Oxidation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2023年第2期41卷 143-150页

作者： Jia Qiu Yougen Xu Shimin Su Yadong Gao Peiyuan Yu Zhixiong Ruan Kuangbiao Liao Guangdong laboratory Animals Monitoring Institute Guangdong Provincial Key Laboratory of Laboratory AnimalsGuangzhouGuangdong 510663China Guangzhou Municipal and Guangdong Provincial Key laboratory of Molecular Target&Clinical Pharmacology the NMPA and State Key Laboratory of Respiratory DiseaseSchool of Pharmaceutical Sciences and the Fifth Affiliated HospitalGuangzhou Medical UniversityGuangzhouGuangdong 511436China Bioland laboratory GuangzhouGuangdong 510005China Department of Chemistry Southern University of Science and TechnologyShenzhenGuangdong 518055China Guangzhou laboratory GuangzhouGuangdong 510320China

Though alcohol oxidations were considered as well-established reactions,selecting productive conditions or predicting reaction yields for unseen alcohols remained as major ***,an auto machine learning(ML)model for tempo-catalyzed oxida-tion of primary alcohols to the corresponding carboxylic acids is disclosed.A dataset of 3444 data,consisting of 282 primary alco-hols and 45 conditions,were generated using high-throughput experimentation(HTE).With the HTE data and 105 descriptors,a multi-label prediction was performed with AutoGluon(an open-source auto machine learning framework)and KNIME(an open-source data analytics platform).For the independent test of 240 reactions(a full matrix of 20 unseen alcohols and 12 condi-tions),AutoGluon with multi-label prediction for yield prediction(AGMP)gave excellent *** external test of 1308 re-actions(consisting of 84 alcohols and 45 conditions),AGMP still afforded good results with R2 as 0.767 and MAE as 4.9%.The model also revealed that the newly generated descriptor(Y/N,classification of the reaction reactivity)was the most relevant descriptor for yield prediction,offering a new perspective to integrate HTE and ML in organic synthesis.

关键词： tempo Oxidation Primary alcohols Carboxylic acids AutoGluon

Polyphosphoester-modified Cellulose Nanocrystals for Stabilizing Pickering Emulsion Polymerization of Styrene

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第9期38卷 921-931,I0005页

作者： Kun-Ming Che Ming-Zu Zhang Jin-Lin He Pei-Hong Ni College of Chemistry Chemical Engineering and Materials ScienceState and Local Joint Engineering Laboratory for Novel Functional Polymeric MaterialsJiangsu Key Laboratory of Advanced Functional Polymer Design and ApplicationSuzhou Key Laboratory of Macromolecular Design and Precision SynthesisSoochow UniversitySuzhou 215123China

The structure and properties of functional nanoparticles are important for stabilizing Pickering emulsion ***,cellulose nanocrystals(CNCs)are increasingly favored as a bio-based stabilizer for Pickering *** this study,we reported a novel functionalized polyphosphoester-grafted CNCs for the stabilization of oil-in-water Pickering emulsions and the emulsion polymerization of ***,polyphosphoester containing an amino group at one end of the chain,abbreviated as PBYP-NH2,was prepared by ring-opening polymerization(ROP)and hydrolysis reaction,wherein PBYP represents poly[2-(but-3-yn-1-yloxy)-2-oxo-1,3,2-dioxaphospholane].Subsequently,CNC-COOH was obtained via 2,2,6,6-tetramethylpiperidine-1-oxyl(tempo)oxidation of *** functionalized nanocrystals CNC-PBYP-COOH with carboxyl groups and polyphosphoester on the surface were obtained by the amidation reaction of PBYP-NH2 with ***,we used CNC-PBYP-COOH as sole particle emulsifiers to stabilize styrene-in-water Pickering emulsions and studied its effects on the emulsions in details by using dynamic light scattering(DLS).The results indicated that the properties of these emulsions depended on the concentration of hydrophobically modified CNCs,volume ratios of oil to water,and pH *** modified CNCs had higher ability to stabilize the styrene-in-water emulsions relative to the unmodified CNCs,and a stable oil-in-water(o/w)Pickering emulsion with diameter of hundreds of nanometers could be *** resulting emulsions could be polymerized to yield nanosized *** polyphosphoester-modified CNCs as green particle emulsifiers can efficiently stabilize nanoemulsions and latexes,which would promote the development of novel environmentally friendly materials.

关键词： Cellulose nanocrystals(CNCs) Polyphosphoesters(PPEs) Pickering emulsion Emulsion polymerization

Metal-free synthesis of nitriles from aldehydes and ammonium by visible-light photocatalysis

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2023年第10期66卷 2852-2857页

作者： Xu He Yi-Wen Zheng Bin Chen Ke Feng Chen-Ho Tung Li-Zhu Wu Key laboratory of Photochemical Conversion and Optoelectronic Materials New Cornerstone Science LaboratoryTechnical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China School of Future Technology University of Chinese Academy of SciencesBeijing 100049China BayRay Innovation Center Shenzhen Bay LaboratoryShenzhen 518107China

A green method for synthesis of nitriles from aldehydes and ammonium salts under air is developed under extremely mild conditions,i.e.,1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene(4Cz IPN)as a photocatalyst,2,2,6,6-tetrametylpiperidine-1-oxyl(tempo)as a cocatalyst,and oxygen(ambient air)as the terminal oxidant,visible light irradiation of substrate solutions,producing the desired nitriles with excellent *** reaction involves two distinct transformations,imine formation between an aldehyde and an ammonium salt and photocatalytic oxidation of the formed imine by air to a nitrile.

关键词： visible-light photocatalysis aldehydes nitriles metal-free ambient air

tempo-spatial distribution of Ulva ***-propagules in the Yellow Sea during and after green tide in 2019

在线全文

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2022年第6期40卷 2462-2472页

作者： Jin ZHAO Fanzhou KONG Qianchun LIU Fengjie LI Xiu WEI Tian YAN Peng JIANG CAS and Shandong Province Key laboratory of Experimental Marine Biology Center for Ocean Mega-ScienceInstitute of OceanologyChinese Academy of SciencesQingdao 266071China laboratory for Marine Biology and Biotechnology Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China CAS Key laboratory of Marine Ecology and Environmental Sciences Institute of OceanologyChinese Academy of SciencesQingdao 266071China laboratory of Marine Ecology and Environmental Science Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China University of Chinese Academy of Sciences Beijing 100049China College of Life Science Qingdao UniversityQingdao 266071China

Large-scale green tides occur frequently in summer in the Yellow Sea in recent ***,providing“seeds”for the seaweeds,play an important role in the formation of green *** studied the distribution pattern and genetic composition of the Ulva micro-propagules in the Yellow Sea during and after the green tide in *** April,a great amount of Ulva micro-propagules was detected in the Subei Shoal,with the average density of 908 inds./L,being similar to that of previous *** was found out at a low percentage(4%),and 25%of them were positive when tested by the specific marker for the floating *** percentage of *** was obviously lower than that in the same season from 2009 to ***,the quantity of *** micro-propagules sharply *** variation in composition of the micro-propagules in Subei radial sand ridges was revealed in the background of the alternation of macroalgal tides in the Yellow Sea in the latest *** the green tide in June and July,Ulva micro-propagules were detected from some nearshore sites where the floating seaweeds distributed,and *** was the dominate *** September,when the green tide ended,no Ulva micro-propagule was detected from the open sea area of the Yellow *** is indicated that the green algae micro-propagules were unlikely to exist in the open water of the Yellow Sea for a long time according to the large-scale *** mechanism of preserving micro-propagules in Subei radial sand ridges,and the destination of *** micro-propagules in the open sea area of the Yellow Sea after green tide deserves further study.

关键词： green tide Ulva prolifera micro-propagule Yellow Sea

Transformations of N-arylpropiolamides to indoline-2,3-diones and acids via C≡C triple bond oxidative cleavage and C(sp^2)–H functionalization

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2020年第2期63卷 222-227页

作者： Ming-Bo Zhou Yang Li Xuan-Hui Ouyang Jin-Heng Li Key laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle Nanchang Hangkong UniversityNanchang 330063China Key laboratory of Chemical Biology&Traditional Chinese Medicine Research(Ministry of Education) Hunan Normal UniversityChangsha 410081China State Key laboratory of Applied Organic Chemistry Lanzhou University'Lanzhou 730000China

A new palladium-catalyzed oxidative conversion of N-arylpropiolamides and H2O to various indoline-2,3-diones and acids through the C≡C triple bond cleavage and C(sp2)–H functionalization is described,which is promoted by a cooperative action of catalytic CuBr2,2,2,6,6-tetramethyl-1-piperidinyloxy(tempo)and *** method provides a practical tool for transformations of alkynes by means of a C–H functionalization strategy,which enables the formation of one C–C bond and multiple C–O bonds in a single reaction with high substrates compatibility and excellent functional group tolerance.

关键词： alkynes indoline-2,3-diones acids C≡C bond oxidative cleavage C–H functionalization

Dynamic Characteristics of SF_6-N_2-CO_2 Gas Mixtures in DC Discharge Process

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2014年第9期16卷 848-855页

作者： ZHENG Dianchun WANG Jia CHEN Chuntian ZHAO Dawei ZHANG Chunxi YANG Jiaxiang Key laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and Technology

Dynamic characteristics of discharge particles are described within the framework of a two-dimensional photoionization-hydrodynamic numerical model for the discharge process of SF6-N2-CO2 gas mixtures at atmospheric pressure, under a uniform DC applied field. The finite difference flux corrected transport （FD-FCT） algorithm is used in the numerical implementation for improving the accuracy and efficiency. Then the tempo-spatial distributions of the gap space electric field and electron velocity are calculated from the microscopic mechanism, and the dynamic behaviors of charged particles are obtained in detail. Meanwhile, the tempo-spatial critical point of the avalanche-to-streamer in this model is discovered, and several microscopic parameters are also investigated. The results showed that the entire gap discharge process can be divided into two phases of avalanche and streamer according to Raether-Meek criterion; the electron density within the discharge channel is lower compared to that of positive and negative ions; space charge effect is a dominant factor for the distortion of spatial electric field, making the discharge channel expand toward both electrodes faster; photoionization provides seed electrons for a secondary electron avalanche, promoting the formation and development speed of the streamer.

关键词： hydrodynamic model photoionization short gap streamer discharge ternarymixture

Electrochemical conversion of furfural to furoic acid:a more stable,efficient and energy-saving system

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2022年第12期65卷 2576-2587页

作者： Xinxin Li Linchuan Cong Haibo Lin Fangbing Liu Fuyu Han Nan Lin State Key laboratory of Inorganic Synthesis and Preparative Chemistry Jilin UniversityChangchun130012China

The paired electrolytic system is constructed by combining the valuable organic electro-oxidation and electro-reduction reactions,which can replace the ineffective water splitting *** reducing the energy consumption of the electrolytic cell,the value-added electrolysis is *** indirect electrolysis method greatly reduces the dependence of the organic electrolysis reaction on electrode potential by introducing the redox mediators,which solves the problem on the matching of anode and cathode current under potentiostatic ***,we report a more stable,efficient and energy-saving linear paired electrochemical synthesis system that can simultaneously convert furfural to furoic acid at both the anode and cathode at higher current *** three-dimensional networked PbO_(2)is used as the anode and the catalytic amount of 2,2,6,6-tetramethyl-1-piperidinyloxy(tempo)is used as the mediator to realize the efficient conversion of furfural to furoic acid in a wide potential *** cathode catalyzes two-electron oxygen reduction to hydrogen peroxide using Pb/RHPC gas-diffusion electrode,which mediates the oxidation of furfural to furoic acid *** potentiostatic electrolysis,the selectivity of the furoic acid in the cathode and anode is 33.2%and 99.3%,respectively,and the total electron efficiency is 127.1%.The properties of the cathode and anode remain stable after the long-time electrolysis in a flow *** choosing a stable anode with high oxygen evolution overpotential and a gas-diffusion cathode with high hydrogen evolution overpotential,the electrolytic cell can be operated efficiently and stably by introducing reasonable mediated *** two half-reactions have good compatibility during the electrolysis process,saving energy consumption by about 12.3%,for certain industrial application prospects.

关键词： furfural furoic acid paired electrolytic system indirect electrosynthesis

Novel Reaction of Nitroxide with Hantzsch Dihydropyridines

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2002年第10期13卷 923-925页

作者： Man LU Jian Guo FANG Zhong Li LIU Long Min WU National laboratory of Applied Organic Chemistry Lanzhou UniversityLanzhou 730000

4-oxo-2. 2, 6, 6-tetramethylpiperidinyl-1-oxy radical (tempo), a nitroxide, oxidized 4-substituted Hantzsch 1,4-dihydropyridines (DHP) under UV irradiation in CH3CN to give aromatic products in good yields. A possible... 详细信息

关键词： Nitroxide Hantzsch dihydropyridines photoinduced electron transfer.

Estimated evolutionary tempo of East Asian gobionid fishes (Teleostei:Cyprinidae) from mitochondrial DNA sequence data

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2010年第15期55卷 1501-1510页

作者： LIU HuanZhang YANG JinQuan TANG QiongYing Key laboratory of Aquatic Biodiversity and Conservation Institute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China laboratory of Fishes Shanghai Ocean University Shanghai 200090 China

The rapid development of molecular phylogenetic analysis has provided a new path to investigate the tempo of *** this work,a rather complete molecular phylogeny of the East Asian gobionid fishes was constructed based on mtDNA cytochrome b gene *** clock analysis was then applied to investigate the speciation tempo of this *** phylogenetic analysis revealed four major groups that were in agreement with previous *** numbers plotted over time indicate that gobionid lineages increased in an exponential mode with the equation expressed as y=87.562×e 0.1141x,where y is the number of lineages and x represents the geological time,and 0 < x ≤ 30,1≤ y ≤ *** speciation rate of gobionid fishes calculated by LASER program was *** of speciation were identified and found approximately to be coincident with East Asian geological events,such as uplifts of the Tibetan plateau and formation of the monsoon system.

关键词：真骨鱼类线粒体DNA 序列数据东亚速度估计线粒体细胞色素b基因系统发育分析分子系统发育