检索结果-南通市图书馆

维普期刊数据库

A novel manganese tungstate nanorod catalyst for the oxidation of styrene with tert-butyl hydroperoxide as oxidant

在线全文

学校读者我要写书评

暂无评论

Tungsten 2024年第4期6卷 845-858页

作者： Shanmugam Manimaran Arumugam pandurangan gopalakrishnan govindasamy department of chemistry Anna University Energy Cluster School of Engineering University of Petroleum and Energy Studies (UPES)

Catalyst,solvent and process parameters are the keys for the selective oxidation of styrene and other olefins to value added *** MnWO4was synthesized by the one-pot hydrothermal method using pluronic F127 as a surfactant,characterized and evaluated for the oxidation of styrene and different olefins,using tert-butyl hydroperoxide（TBHp） as oxidant.X-ray diffractogram confirmed the phase purity of MnWO4which became further evident from the near surface equimolar proposition of Mn and W in+2 and+6 oxidation states,respectively,as inferred from X-ray photoelectron spectra.N2sorption followed type Ⅳa isotherm with H3 hysteresis loop,starting at the relative pressure（p/p_o） of 0.9,typically of mesoporous materials containing macropores as further confirmed by pore-size *** electron microscope images of MnWO4revealed its nanorod *** the absence of catalyst,styrene conversion was 35%with benzaldehyde as the sole product and addition of 75 g of MnWO4increased the styrene conversion to 97.3%,and the styrene oxide selectivity from 0% to 85% demonstrated its activity and *** the maximum conversion and styrene oxide selectivity optimum temperature,styrene:TBHp molar ratio,catalyst amount and solvent were found to be 70 ℃,1:2,75 mg,and acetonitrile,***4catalyst retained its activity and selectivity for five recycles,confirming its recoverability and *** the kinetic studies,pre-exponential factor and apparent activation energy were found to be 0.206 s-1and 31.5 kJ·mol-1,respectively,and a reaction mechanism was ***4catalyst was active for oxidation of alkenes,cycloolefins and alkenyl aromatics with high selectivity for epoxides.

关键词： Epoxidation Manganese tungstate nanorod Styrene oxidation

Investigation of HO_(2) uptake mechanisms onto multiple-component ambient aerosols collected in summer and winter time in Yokohama,Japan

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第3期137卷 18-29页

作者： Jun Zhou Yukiko Fukusaki Kentaro Murano Tania gautam Yu Bai Yoshimi Inomata Hiroaki Komatsu Mayuko Takeda Bin Yuan Min Shao Yosuke Sakamoto Yoshizumi Kajii Institute for Environmental and Climate research Jinan UniversityGuangzhou 511443China guangdong-Hongkong-Macao Joint Laboratory of Collaborative Innovation forEnvironmental Quality Guangzhou 511443China graduate School of global Environmental studies Kyoto UniversityKyoto606-8501Japan Yokohama Environmental Science research Institute Yokohama Kanagawa 221–0024Japan department of chemistry University of AlbertaAlbertaEdmonton T6G 2G2Canada graduate School of Human and Environmental studies Kyoto UniversityKyoto 606-8501Japan Kanagawa Environmental research Center Kanagawa 254-0014Japan Center for Regional Environmental research National Institute for Environmental StudiesIbaraki305-8506Japan

The heterogeneous loss of HO_(2)radicals onto ambient aerosols plays an important role in tropospheric ***,sparse investigation of the dominating parameters controlling the HO_(2)uptake coefficients onto ambient aerosols(γHO_(2))has largely hindered the application of the measuredγHO_(2)to the global spatial *** we induced an offine method using LFp-LIF technique to measure the kinetics of HO_(2)uptake onto ambient aerosols collected in summertime and wintertime in Yokohama city,a regional urban site near Tokyo,*** controlling the dominating parameters which infuenceγHO_(2),we were able to investigate the detailed HO_(2)uptake *** characterized the chemical composition of the collected ambient aerosols,including organics,inorganics,transition metals ions,*** modeledγHO_(2)using different *** show thatγHO_(2)increased with the increase in RH,and the aerosol states(“dry”or wet/aqueous)have large effects onγHO_(2).With fixed RH and aerosol chemical composition,γHO_(2)was highly dependent on pH and inversely correlated with[HO_(2)]_*** combing the measuredγHO_(2)values with the modeled ones,we found that both the HO_(2)self-reaction and transition metal-catalyzed reactions should be accounted for to yield a single parameterization to predictγHO_(2),and different chemical compositions may have collective effects onγHO_(2).Results may serve for extending theγHO_(2)values measured at one observation site to different environmental conditions,which will help us to achieve more accurate modeling results concerning secondary pollutant formation(i.e.,ozone).

关键词： HO_(2)uptake kinetics Offine method Impacting factors Mechanism

维普期刊数据库

Visible-light-induced organocatalyzed C（sp2）–H bond functionalization of 1,3-azoles with trifluoroacetylsilanes

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2024年第11期67卷 3662-3668页

作者： Zhengyu Li Zeguo Zhang Zhihan Zhang gang Zhou Yizhi Zhang Shanshan Liu Xiao Shen The Institute for Advanced studies Engineering Research Center of Organosilicon Compounds & Materials Ministry of EducationWuhan University College of chemistry Central China Normal University

previous carbene insertion to C–H bonds of 1,3-azoles relied on metal carbene species. Herein, we report a metal-free C（sp2）–H bond functionalization of 1,3-azoles with trifluoroacetylsilanes. The reaction features mild conditions, broad substrate scope and wide functional group tolerance. The mechanistic study supports that the success of the reaction is probably attributed to the dual roles of trifluoroacetylsilanes under the photocatalyzed conditions: generating carbenes which undergo cyclopropanation and generating biradicals which promote ring-opening aromatization of the in situ generated fused cyclopropanes.

关键词： C(sp2)–H bond functionalization carbenes biradicals cyclopropanation brook rearrangement

STINg agonist-conjugated metal-organic framework induces artificial leukocytoid structures and immune hotspots for systemic antitumor responses

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2024年第7期11卷 189-204页

作者： Taokun Luo Xiaomin Jiang Yingjie Fan Eric Yuan Jinhong Li Langston Tillman Wenbin Lin department of chemistry University of Chicago department of Radiation and Cellular Oncology and the Ludwig Center for Metastasis research University of Chicago

Radiotherapy is widely used for cancer treatment, but its clinical utility is limited by radioresistance and its inability to target metastases. Nanoscale metal-organic frameworks(MOFs) have shown promise as high-Z nanoradiosensitizers to enhance radiotherapy and induce immunostimulatory regulation of the tumor microenvironment. We hypothesized that MOFs could deliver small-molecule therapeutics to synergize with radiotherapy for enhanced antitumor efficacy. Herein, we develop a robust nanoradiosensitizer,gA-MOF, by conjugating a STINg agonist, 2,3-cyclic guanosine monophosphate–adenosine monophosphate(gA), on MOFs for synergistic radiosensitization and STINg activation. gA-MOF demonstrated strong anticancer efficacy by forming immune-cell-rich nodules(artificial leukocytoid structures) and transforming them into immunostimulatory hotspots with radiotherapy. Further combination with an immune checkpoint blockade suppressed distant tumors through systemic immune activation. Our work not only demonstrates the potent radiosensitization of gA-MOF, but also provides detailed mechanisms regarding MOF distribution, immune regulatory pathways and long-term immune effects.

关键词： metal-organic framework radiosensitization STINg agonist artificial leukocytoid structures immune hotspots immunotherapy nanomedicine

Supramolecular Biomaterials for Cancer Immunotherapy

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

research 2024年第2期2023卷 491-509页

作者： Huan Liang Qingqing Lu Jie Yang guocan Yu College of Science Nanjing Forestry UniversityNanjing 210037P.R.China Key Laboratory of Bioorganic phosphorus chemistry&Chemical Biology Department of ChemistryTsinghua UniversityBeijing 100084P.R.China

Cancer immunotherapy has achieved tremendous successful clinical results and obtained historic victories in tumor ***,great limitations associated with feeble immune responses and serious adverse effects still cannot be neglected due to the complicated multifactorial etiology and pathologic microenvironment in *** rapid development of nanomedical science and material science has facilitated the advanced progress of engineering biomaterials to tackle critical *** supramolecular biomaterials with flexible and modular structures have exhibited unparalleled advantages of high cargo-loading efficiency,excellent biocompatibility,and diversiform immunomodulatory activity,thereby providing a powerful weapon for cancer *** past decades,supramolecular biomaterials were extensively explored as versatile delivery platforms for immunotherapeutic agents or designed to interact with the key moleculars in immune system in a precise and controllable *** this review,we focused on the crucial role of supramolecular biomaterials in the modulation of pivotal steps during tumor immunotherapy,including antigen delivery and presentation,T lymphocyte activation,tumor-associated macrophage elimination and repolarization,and myeloid-derived suppressor cell *** on extensive research,we explored the current limitations and development prospects of supramolecular biomaterials in cancer immunotherapy.

关键词： biomaterials limitations thereby

Single-atom catalysts for the electrochemical reduction of carbon dioxide into hydrocarbons and oxygenates

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Carbon Energy 2024年第3期6卷 64-117页

作者： Karl Adrian gandionco Juwon Kim Lieven Bekaert Annick Hubin Jongwoo Lim department of chemistry Seoul National UniversitySeoulRepublic of Korea research group Electrochemical and Surface Engineering(SURF) Department of Materials and ChemistryVrije Universiteit BrusselBrusselsBelgium

The electrochemical reduction of carbon dioxide offers a sound and economically viable technology for the electrification and decarbonization of the chemical and fuel *** this technology,an electrocatalytic material and renewable energy-generated electricity drive the conversion of carbon dioxide into high-value chemicals and carbon-neutral *** the past few years,single-atom catalysts have been intensively studied as they could provide near-unity atom utilization and unique catalytic ***-atom catalysts have become one of the state-of-the-art catalyst materials for the electrochemical reduction of carbon dioxide into carbon ***,it remains a challenge for single-atom catalysts to facilitate the efficient conversion of carbon dioxide into products beyond carbon *** this review,we summarize and present important findings and critical insights from studies on the electrochemical carbon dioxide reduction reaction into hydrocarbons and oxygenates using single-atom *** is hoped that this review gives a thorough recapitulation and analysis of the science behind the catalysis of carbon dioxide into more reduced products through singleatom catalysts so that it can be a guide for future research and development on catalysts with industry-ready performance for the electrochemical reduction of carbon dioxide into high-value chemicals and carbon-neutral fuels.

关键词： electrocatalysis electrochemical CO_(2)reduction hydrocarbons oxygenates single-atom catalysts

Nanozyme catalysis in a crowded environment:The impact of diffusion and surface shielding

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano research 2024年第7期17卷 5795-5800页

作者： Vasily g.panferov Juewen Liu department of chemistry Waterloo Institute for NanotechnologyWaterlooOntario N2L 3G1Canada

Nanozymes are widely used in various applications as nanosized catalysts for replacing *** accurate estimation of the catalytic activity of nanozymes in real conditions is *** this article,for the first time,we systematically studied the effect of macromolecular molecules co-existing in the real system on the oxidoreductase(peroxidase,oxidase,and catalase)-mimicking nanozymes made of a gold nanoparticle core and a platinum shell,prussian Blue,Mn_(2)O_(3) and CoO *** were made with horseradish *** distinguished two main mechanisms of the negative impact of macromolecules on nanozyme catalysis—slowed diffusion and surface shielding of *** the first mechanism is typical for enzymes,the second one is specific only for *** the mechanisms is essential for developing approaches to reduce the unavoidable impact of macromolecules for various analytical and biomedical applications.

关键词： molecular crowding biosensors nanoparticles

Recent Advances in 0D Ni/Co-based Hollow Electrocatalysts for Electrochemical Water Splitting

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical research in Chinese Universities 2024年第3期40卷 437-450页

作者： gE Wenjing CHEN Xiaocui MA Ruizhao ZHENg Siyuan SHANg Ningzhao ZHAO Xiaoxian department of chemistry College of ScienceHebei Agricultural UniversityBaoding 071001P.R.China

Electrochemical water splitting using renewable energy sources has been recognized as a sustainable way to produce hydrogen energy due to the characteristics of low-carbon and no ***,the slow hydrogen/oxygen evolution reactions(HER/OER)seriously hinder the practical application of large-scale water *** this paper,the 0D Ni/Co-based hollow material is discussed in detail because of adjustable morphology,low mass density and abundant active sites,which provides an effective solution for improving the HER/OER reaction *** synthesis methods of hollow materials,such as hard template,soft template and self-template are ***,catalysts with different structural designs of hollow structures are reviewed,including hollow single-shelled structure,hollow core-shelled structure,hollow double-shelled structure and hollow multi-shelled structure(HoMS)***,the research progress of the 0D Ni/Co-based HoMS electrocatalysts in recent years and their prominent performances in water splitting are ***,the challenges and development prospects of designing Ni/Co-based HoMS catalysts in water splitting in the future are discussed.

关键词： Electrochemical watersplitting Morphological regulation Hollow structure Hollow multi-shelled structure(HoMS)

Regioselective C-C bond cleavage/aminocarbonylation cascade under copper catalysis

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 chemistry 2024年第11期67卷 3798-3806页

作者： Qi-Chao Shan Yan Zhao Yong Wu Hong-Fei Liu Xin-Hua Duan Li-Na guo department of chemistry School of Chemistry Energy Research Center of Energy Storage Materials and Devices Ministry of EducationXi'an Jiaotong University State Key Laboratory of Applied Organic chemistry Lanzhou University

A regioselective C-C bond cleavage/aminocarbonylation cascade is presented. In recent years, tremendous progress has been made in the alkoxyl radical-mediated C-C bond cleavage of unstrained monocarbocycles. In contrast, the deconstruction and functionalization of bicyclic skeletons has been less developed and has mainly focused on the ring expansion process. Inspired by the aromatization-driven C-C bond cleavage, here we demonstrate a ring-opening/aminocarbonylation cascade under copper catalysis, in which the formation of a stable γ-lactam or succinimide skeleton reverses the selectivity of C-C cleavage. Remarkably, the photo and thermal assistance is not required when the succinimide skeleton is formed during the ring opening process. DFT calculations revealed that this unexpected ring-opening process is thermodynamically and kinetically favourable.

关键词： C-C bond cleavage controllable regioselectivity aminocarbonylation bicyclic alkoxy radical