Herein the use of rare-earth compounds in catalytic reduction systems for the end-group functionalization of carboxyl-terminated low-molecularweight fluoropolymers was explored.Leveraging the high catalytic activity a...Herein the use of rare-earth compounds in catalytic reduction systems for the end-group functionalization of carboxyl-terminated low-molecularweight fluoropolymers was explored.Leveraging the high catalytic activity and selectivity of rare-earth compounds along with no residual impact on polymer product's performance,highly efficient catalytic reduction systems containing sodium borohydride(NaBH_(4))and rare-earth chloride(RECl_(3))were specifically designed for a telechelic carboxyl-terminated liquid fluoroeslastomer,aiming to facilitate the conversion of chainend carboxyl groups into hydroxyl groups and improvement in end-group reactivity.To achieve this,lanthanum chloride(LaCl_(3)),cerium chloride(CeCl_(3)),and neodymium chloride(NdCl_(3))were used separately to form catalytic reduction systems with NaBH_(4).The effects of solvent dosage,reaction temperature,reaction time length,and reductant dosage on carboxylic conversion were investigated,and the molecular chain structure,molecular weight,and functional group content of the raw materials and the products were analyzed and characterized by means of infrared spectroscopy(FTIR),proton nuclear magnetic resonance(^(1)H-NMR),fluorine-19 nuclear magnetic resonance(^(19)F-NMR),gel permeation chromatography(GPC),and chemical titration.Moreover,the catalytic activity and selectivity of the rare-earth chlorides,as well as the corresponding underlying interactions were discussed.Results indicated that the rare-earth-containing catalytic reduction systems studied in this work could efficiently convert the chain-end carboxyl groups into highly active hydroxyl groups,with a highest conversion up to 87.0%and differing catalytic reduction activities ranked as NaBH_(4)/CeCl_(3)>NaBH_(4)/LaCl_(3)>NaBH_(4)/NdCl_(3).Compared with the conventional lithium aluminum hydride(LiAIH_(4))reduction system,the NaBH_(4)/RECl_(3)systems provide multiple advantages such as mild reaction conditions,high conversion ratio with good selectivity,and environmental innocuity,and are potentially applicable as new reduction-catalysis combinations for the synthesis and functionalization of polymer materials.展开更多
The development of efficient and robust oxygen non-precious catalysts for the oxygen evolution reaction(OER)remains a critical scientific hurdle in realizing cost-effective renewable energy conversion systems.Herein,w...The development of efficient and robust oxygen non-precious catalysts for the oxygen evolution reaction(OER)remains a critical scientific hurdle in realizing cost-effective renewable energy conversion systems.Herein,we present a rapid laser irradiation synthesis strategy for the successful fabrication of sub-10 nm FeCoNiMnCr high-entropy alloy nanoparticles(HEA-NPs)on multi-wall carbon nanotube(MWCNT)paper,serving as highly efficient OER electrocatalysts.The synthesis of high-entropy alloy nanoparticles with pre-cise control was accomplished through systematic optimization of laser processing parameters.Structural characterization via X-ray diffraction,high-resolution transmission electron microscopy,and high-angle annular dark-field scanning transmission electron microscopy collectively verified the formation of a phase-pure face-centered cubic crystal structure with homogeneous elemental mixing at the atomic scale.Furthermore,COMSOL Multiphysics simulations confirm that this rapid and discontinuous laser irradiation approach enables the precursor material to undergo ultrafast heating and quenching processes,effectively suppressing Ostwald ripening phenomena,which is conducive to the formation of ultrafine(sub-10 nm)high-entropy alloy nanoparticles.The synthesized HEA-NPs catalyst demonstrates exceptional oxygen evolution activity in alkaline electrolyte(1 M KOH),achieving a current density of 10 mA·cm^(−2) at a low overpoten-tial of 255 mV while maintaining remarkable stability with negligible activity decay during prolonged operation(>100 h),representing state-of-the-art performance among non-precious metal catalysts.This study provides perspectives on the rapid preparation and performance regulation of HEA-NPs catalysts.展开更多
心律失常是临床常见的心血管疾病,药物治疗是目前的常规治疗方法。但临床上使用的抗心律失常药物大多属于单离子通道阻滞剂,除个体差异外还存在各种副作用。因此,单一离子通道阻滞剂不能完全治疗心律失常,而多离子通道阻滞往往是关键因...心律失常是临床常见的心血管疾病,药物治疗是目前的常规治疗方法。但临床上使用的抗心律失常药物大多属于单离子通道阻滞剂,除个体差异外还存在各种副作用。因此,单一离子通道阻滞剂不能完全治疗心律失常,而多离子通道阻滞往往是关键因素。中药具有多途径、多靶点的特点和优势,与心律失常的理想治疗原则不谋而合。研究证实,中药中含有具有抗心律失常作用的活性成分。选择这些活性成分进行抗心律失常治疗,不仅可能优于中药本身,而且成分明确,靶点明确。因此,从中药中研究多途径、多靶点的抗心律失常活性成分是未来的研究方向。基于此,本文检索CNKI、万方、维普、SinoMed、Pubmed、Web of Sciencce、Cochrane、EMbase数据库,总结了近5年来中药抗心律失常活性成分的研究现状,分析了研究中存在的不足和挑战,进而指出了未来的研究方向,以期明确当前的研究热点和趋势。展开更多
文摘Herein the use of rare-earth compounds in catalytic reduction systems for the end-group functionalization of carboxyl-terminated low-molecularweight fluoropolymers was explored.Leveraging the high catalytic activity and selectivity of rare-earth compounds along with no residual impact on polymer product's performance,highly efficient catalytic reduction systems containing sodium borohydride(NaBH_(4))and rare-earth chloride(RECl_(3))were specifically designed for a telechelic carboxyl-terminated liquid fluoroeslastomer,aiming to facilitate the conversion of chainend carboxyl groups into hydroxyl groups and improvement in end-group reactivity.To achieve this,lanthanum chloride(LaCl_(3)),cerium chloride(CeCl_(3)),and neodymium chloride(NdCl_(3))were used separately to form catalytic reduction systems with NaBH_(4).The effects of solvent dosage,reaction temperature,reaction time length,and reductant dosage on carboxylic conversion were investigated,and the molecular chain structure,molecular weight,and functional group content of the raw materials and the products were analyzed and characterized by means of infrared spectroscopy(FTIR),proton nuclear magnetic resonance(^(1)H-NMR),fluorine-19 nuclear magnetic resonance(^(19)F-NMR),gel permeation chromatography(GPC),and chemical titration.Moreover,the catalytic activity and selectivity of the rare-earth chlorides,as well as the corresponding underlying interactions were discussed.Results indicated that the rare-earth-containing catalytic reduction systems studied in this work could efficiently convert the chain-end carboxyl groups into highly active hydroxyl groups,with a highest conversion up to 87.0%and differing catalytic reduction activities ranked as NaBH_(4)/CeCl_(3)>NaBH_(4)/LaCl_(3)>NaBH_(4)/NdCl_(3).Compared with the conventional lithium aluminum hydride(LiAIH_(4))reduction system,the NaBH_(4)/RECl_(3)systems provide multiple advantages such as mild reaction conditions,high conversion ratio with good selectivity,and environmental innocuity,and are potentially applicable as new reduction-catalysis combinations for the synthesis and functionalization of polymer materials.
基金supported by the National Key Research and Development Program of China(No.2024YFB3411500)the Shihezi Municipal Science and Technology Project(No.2024ZD02)support from the Center for Hydrogen Innovations of National University of Singapore(NUS CHI)research grant(CHI-P2024-06-S1).
文摘The development of efficient and robust oxygen non-precious catalysts for the oxygen evolution reaction(OER)remains a critical scientific hurdle in realizing cost-effective renewable energy conversion systems.Herein,we present a rapid laser irradiation synthesis strategy for the successful fabrication of sub-10 nm FeCoNiMnCr high-entropy alloy nanoparticles(HEA-NPs)on multi-wall carbon nanotube(MWCNT)paper,serving as highly efficient OER electrocatalysts.The synthesis of high-entropy alloy nanoparticles with pre-cise control was accomplished through systematic optimization of laser processing parameters.Structural characterization via X-ray diffraction,high-resolution transmission electron microscopy,and high-angle annular dark-field scanning transmission electron microscopy collectively verified the formation of a phase-pure face-centered cubic crystal structure with homogeneous elemental mixing at the atomic scale.Furthermore,COMSOL Multiphysics simulations confirm that this rapid and discontinuous laser irradiation approach enables the precursor material to undergo ultrafast heating and quenching processes,effectively suppressing Ostwald ripening phenomena,which is conducive to the formation of ultrafine(sub-10 nm)high-entropy alloy nanoparticles.The synthesized HEA-NPs catalyst demonstrates exceptional oxygen evolution activity in alkaline electrolyte(1 M KOH),achieving a current density of 10 mA·cm^(−2) at a low overpoten-tial of 255 mV while maintaining remarkable stability with negligible activity decay during prolonged operation(>100 h),representing state-of-the-art performance among non-precious metal catalysts.This study provides perspectives on the rapid preparation and performance regulation of HEA-NPs catalysts.
文摘心律失常是临床常见的心血管疾病,药物治疗是目前的常规治疗方法。但临床上使用的抗心律失常药物大多属于单离子通道阻滞剂,除个体差异外还存在各种副作用。因此,单一离子通道阻滞剂不能完全治疗心律失常,而多离子通道阻滞往往是关键因素。中药具有多途径、多靶点的特点和优势,与心律失常的理想治疗原则不谋而合。研究证实,中药中含有具有抗心律失常作用的活性成分。选择这些活性成分进行抗心律失常治疗,不仅可能优于中药本身,而且成分明确,靶点明确。因此,从中药中研究多途径、多靶点的抗心律失常活性成分是未来的研究方向。基于此,本文检索CNKI、万方、维普、SinoMed、Pubmed、Web of Sciencce、Cochrane、EMbase数据库,总结了近5年来中药抗心律失常活性成分的研究现状,分析了研究中存在的不足和挑战,进而指出了未来的研究方向,以期明确当前的研究热点和趋势。
