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Recent progress in carbene-catalyzed fluoroalkylation

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Science China Chemistry 2024年第8期67卷 2448-2460页

作者： bei Zhang Xuan Zhang jian Wang jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science and TechnologyNanjing 210044China School of Pharmaceutical Sciences Tsinghua UniversityBeijing 100084China

The fluoroalkyl fragment plays a vital role in various fields such as pharmaceuticals and materials science, and has a significant impact on human life not only on the present but also in the future. The insertion of fluoroalkyl groups into the chemical skeletons can cause considerable alternations in the chemical, physical and biological properties of molecules, which has attracted numerous scientists from different fields. This review focuses on N-heterocyclic carbene(NHC)-catalyzed fluoroalkylation reactions, providing a detailed analysis and summary of the achievements in the past two decades. Many successful examples clearly indicate that NHCs can catalyze the tranformation of fluoroalkylation reagents with various electronic characteristics, whether electrophilic, nucleophilic, or radical precursors. Herein, the fluoroalkylation reactions are classified based on different catalytic modes of NHCs: Lewis base catalysis, Umploung catalysis, radical catalysis and others. Meanwhile, by refining and systematically studying the contribution of NHC catalysis in fluoroalkylation reactions, this review is expected to provide valuable insights and enlightenment for related fields.

关键词： N-heterocyclic carbene fluoroalkylation radical catalysis

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Experimental investigation on using CO_(2)/H_(2)O emulsion with high water cut in enhanced oil recovery

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Petroleum Science 2024年第2期21卷 974-986页

作者： Xi-Dao Wu Peng Xiao bei Liu Guang-Jin Chen jian-Hua Pang State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China Ocean Intelligence Technology Center Shenzhen Institute of Guangdong Ocean UniversityShenzhen518120GuangdongChina

CO_(2) emulsions used for EOR have received a lot of interest because of its good performance on CO_(2)mobility ***,most of them have been focusing on the high quality CO_(2) emulsion(high CO_(2) fraction),while CO_(2) emulsion with high water cut has been rarely *** this paper,we carried out a comprehensive experimental study of using high water cut CO_(2)/H_(2)O emulsion for enhancing oil ***,a nonionic surfactant,alkyl glycosides(APG),was selected to stabilize CO_(2)/H_(2)O emulsion,and the corresponding morphology and stability were evaluated with a transparent PVT ***,plugging capacity and apparent viscosity of CO_(2)/H_(2)O emulsion were measured systematically by a sand pack displacement apparatus connected with a 1.95-m long capillary ***,a high water cut(40 vol%) CO_(2)/H_(2)O emulsion was selected for flooding experiments in a long sand pack and a core sample,and the oil recovery,the rate of oil recovery,and the pressure gradients were *** results indicated that APG had a good performance on emulsifying and stabilizing CO_(2) *** inversion from H_(2)O/CO_(2) emulsion to CO_(2)/H_(2)O emulsion with the increase in water cut was ***_(2)/H_(2)O emulsions with lower water cuts presented higher apparent viscosity,while the optimal plugging capacity of CO_(2)/H_(2)O emulsion occurred at a certain water ***,the displacement using CO_(2)/H_(2)O emulsion provided 18.98% and 13.36% additional oil recovery than that using pure CO_(2) in long sand pack and core tests,*** work may provide guidelines for EOR using CO_(2) emulsions with high water cut.

关键词： CO_(2)/H_(2)O emulsion High water cut CO_(2) mobility control Enhanced oil recovery

A New Sesquiterpene from the Roots of Lindera strychnifolia

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Chinese Chemical Letters 2002年第10期13卷 965-967页

作者： jian bei LI Yi DING Wei Min LI Institute of Materia Medica Chinese Academy of Medical SciencesBeijing 100050 Guangzhou University of Traditional Chinese Medicine Guangzhou 510405

A new sesquiterpene lactone, strychnilactone (1), together with five known sesquiterpenoids, linderane (2), lindenenol (3), linderalactone (4), hydroxylindestenolide (5), pseudoneolinderane (6) have been isolated from the extracts of Supercritical Fluid Extraction of Lindera strychnifolia. The structure of the new compound was elucidated by means of spectroscopic analysis. And the relative configuration of 1 was assigned on the basis of NOE analysis.

关键词： Lindera strychnifolia sesquiterpene lactone supercritical fluid extraction.

One-pot and One-step Cu(0)-mediated Reversible-Deactivation Radical Polymerization of N-Isopropylacrylamide(NIPAM) in Water

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Chinese Journal of Polymer Science 2024年第1期42卷 1-6,I0004页

作者： Zi-Shan Li Jing Lyu bei Qiu Ying-Hao Li Ruth Foley Ri-jian Song Melissa Johnson Qiang Geng Wen-Xin Wang Institute of Precision Medicine(AUST-IPM) Anhui University of Science and TechnologyHuainan 232001China Charles Institute of Dermatology School of MedicineUniversity College DublinDublin D04 V1W8Ireland

Copper(0)-mediated reversible-deactivation radical polymerization(Cu(0)-mediated RDRP) of the water-soluble monomer Nisopropylacrylamide(NIPAM) has been challenging with the problems of high dispersity, poor control over the molecular weights(MWs) or complex or multi reaction steps, etc. In this work, we report the well-controlled polymerization of NIPAM in water via a facile one-pot and one-step Cu(0)-mediated RDRP. The results of this approach show that the key for kicking off the Cu(0)-mediated NIPAM RDRPs is to ensure sufficient Cu~I at the very beginning, and the key to achieve a well-controlled chain growth is to provide adequate deactivation strength during the polymerization process. For NIPAM, which has a high propagation rate constant, the deactivation control can be effectively enhanced by extra adding deactivator(i.e., Cu~II) to the system. Moreover, a low reaction temperature(4 ℃) is necessary in the controlled synthesis of higher MW poly(Nisopropylacrylamide)(PNIPAM) to avoid the compromise in control caused by the phase transition from its lower critical solution temperature(LCST). Through this new kinetically controlled strategy, PNIPAMs with well-defined structure, narrow molecular weight distributions(MWDs) and varied MWs were successfully achieved.

关键词： Cu(0)-mediated RDRP N-isopropylacrylamide Propagation Deactivation Reaction parameters

Unleashing the Power of Bio-based Thermotropic Liquid Crystal Modifiers:Toughening and Reinforcing Petroleum-based Epoxy Resin without Compromising Other Properties

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Chinese Journal of Polymer Science 2024年第8期42卷 1093-1102页

作者： Qing-Yun Lu Hong-Wei Gu Jia-Hui Li Qian-Qian Fan bei-Tao Liu Yan Kou Xi-Gao jian Zhi-Huan Weng State Key Laboratory of Fine Chemicals Frontiers Science Center for Smart MaterialsLiaoning Technology Innovation Center of High Performance Resin MaterialsDepartment of Polymer Science&EngineeringDalian University of TechnologyDalian 116024China Thermochemistry Laboratory Liaoning Province Key Laboratory of Thermochemistry for Energy and MaterialsDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China

Toughening the petroleum-based epoxy resin blends with bio-based modifiers without compromising their modulus,mechanical strength,and other properties is still a big challenge in view of the *** this study,a bio-based liquid crystal epoxy resin(THMT-E P)with an s-triazine ring structure was utilized to modify a petroleum-based bisphenol A epoxy resin(E51)with 4,4'-diaminodiphenylsulfone(DDS)as a curing agent,and the blended systems were evaluated for their thermal stability,mechanical properties,and flame *** results showed that the impact strength of the blended system initially increased and then decreased with the increase in THMT-EP content,and it reached the a maximum value of 26.5 kJ/m^(2)when the THMT-EP content was 5%,which was 31.2%higher than that of E51/***,the flexural strength,modulus,and glass transition tem perature of the blended system were all simultaneously improved with the addition of *** the same time,the addition of THMT-EP enhanced the flame retardancy of the system by increasing the char yield at 700℃and decreasing the peak heat release rate and total heat release *** work paves the way for a more sustainable improvement in the comprehensive performance of epoxy resin.

关键词： Epoxy resin Toughening Bio-based Thermotropic liquid crystal

Poly(L-lactide)-Poly(ethylene glycol) Multiblock Copolymers: Synthesis and Properties

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Chinese Chemical Letters 2002年第1期13卷 33-36页

作者： Wei Jun LUO Su Ming LI jian Zhong bei Shen Guo WANG Center fpr Molecular Science Institute of ChemistryChinese Academy of SciencesBeijing 100080

Poly (L-lactide)-poly(ethylene glycol) multiblock copolymers with predetermined block lengths were synthesized by polycondensation of PLA diols and PEG diacids. These copolymers presented special properties, such as better miscibility between the two components, low crystallinity and better hydrophilicity, which can be modulated by adjusting the block lengths of the two components.

关键词： Poly (L-lactide) poly(ethylene glycol) biodegradability multiblock copolymer miscibility crystallinity hydrophilicity.

METTL5 promotes gastric cancer progression via sphingomyelin metabolism

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World Journal of Gastrointestinal Oncology 2024年第5期16卷 1925-1946页

作者： Ya-Qiong Zhang jian Li Zhe Qin De-Ming Li Fang-Zhou Ye Song-Hua bei Xiao-Hong Zhang Li Feng Endoscopy Center Minhang Hospital Affiliated to Fudan UniversityShanghai 201100China

BACKGROUND The treatment of gastric cancer(GC)has caused an enormous social burden *** studies have reported that N6-methyladenosine(m6A)is closely related to tumor ***5 is a m6A methyltransferase that plays a pivotal role in maintaining the metabolic stability of ***,its aberrant regulation in GC has not been fully *** To excavate the role of METTL5 in the development of *** METTL5 expression and clinicopathological characteristics were analyzed via The Cancer Genome Atlas dataset and further verified via immunohistochemistry,western blotting and real-time quantitative polymerase chain reaction in tissue microarrays and clinical *** tumor-promoting effect of METTL5 on HGC-27 and AGS cells was explored in vitro by Cell Counting Kit-8 assays,colony formation assays,scratch healing assays,transwell assays and flow *** tumor-promoting role of METTL5 in vivo was evaluated in a xenograft tumor *** EpiQuik m6A RNA Methylation Quantification Kit was used for m6A ***,liquid chromatography-mass spectrometry was used to evaluate the association between METTL5 and sphingomyelin metabolism,which was confirmed by Enzyme-linked immunosorbent assay and rescue *** addition,we investigated whether METTL5 affects the sensitivity of GC cells to cisplatin via colony formation and transwell *** Our research revealed substantial upregulation of METTL5,which suggested a poor prognosis of GC *** METTL5 expression indicated distant lymph node metastasis,advanced cancer stage and pathological *** increased level of METTL5 correlated with a high degree of m6A ***5 markedly promotes the proliferation,migration,and invasion of GC cells in ***5 also promotes the growth of GC in animal ***5 knockdown resulted in significant changes in sphingomyelin metabolism,which implies that METTL5 may impact the development of GC via sphin

关键词： Gastric cancer METTL5 Sphingomyelin metabolism Cisplatin

Characteristics of Gas Emission at Super-Length Fully-Mechanized Top Coal Caving Face

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Journal of China University of Mining and Technology 2007年第4期17卷 447-452页

作者： XU Jia-lin YU bei-jian LOU Jin-fu WANG Dong-ping State Key Laboratory of Coal Resource and Mine Safety Xuzhou Jiangsu 221008 China School of Mineral and Safety Engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China Yangquan Coal Group Yangquan Shanxi 045008 China

Characteristics of gas emission at the K8206 working face in the Third mine of the Yangquan Coal Group were investigated. The effects of strata movement,advancing velocity of working face,production capacity of working face and gas extraction capability of strike high-level entry on gas emission at K8206 working face were analyzed. A regression equation,reflecting the relationship between relative gas emission rate and the production capacity of work-ing faces,was established. Another regression equation showing the relationship between the gas emission rate from adjacent layers when the working face was advancing for one metre and advancing velocity was derived. It can be con-cluded that,1) the amount of gas emitted at the K8206 working face is far greater than that of ordinary top coal caving faces with a dip length of 180-190 m; 2) the dynamic process of gas emission from adjacent layers during the initial mining stage is controlled by the movement of key strata; 3) the amount of gas emitted that needs to be forced out by air is greatly affected by the capability of gas extraction; 4) when the advancing velocity is between 3.5-5.5 m/d or when the output is up to 8-12 kt/d,the gas emission from adjacent layers is almost constant.

关键词：煤矿超长矿井崩落开采法瓦斯

A Novel Phenylpropanoid-substituted Catechin Glycoside and a New Dihydrochalcone from Sarcandra glabra

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Chinese Chemical Letters 2006年第2期17卷 207-210页

作者： Yuan LI Dong Ming ZHANG Shi Shah YU jian bei LI Yong Ming LUO Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine Ministry of Education Institute of Materia Medica Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 100050 Faculty of Pharmacy Jiangxi University of Traditional Chinese Medicine Nanchang 330006

A novel phenylpropanoid-substituted catechin glycoside glabraoside A 1 and a new dihydrochalcone 3＇-（7＂-allylphenyl）-2＇,4＇,4＂-trihydroxy-6＇-methoxydihydrochalcone 2 were isolated from the herbs of Sarcandra gl... 详细信息

关键词： Sarcandra glabra glabraoside A phenylpropanoid-substituted flavan-3-ols dihydrochalcone.