期刊文献+
共找到361篇文章
< 1 2 19 >
每页显示 20 50 100
C-H bond activation of propane on Ga_(2)O_(2)^(2+) in Ga/H-ZSM-5 and its mechanistic implications
1
作者 Zhaoqi Zhao Yunzhu Zhong +1 位作者 Xiaoxia Chang Bingjun Xu 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第9期32-43,共12页
Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified ... Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified as the most active species in Ga/H-ZSM-5 for PDH in our recent work.Here we demonstrate a strong correlation between the PDH activity and a fraction of Ga_(2)O_(2)^(2+) species corresponding to the infrared GaH band of higher wavenumber(GaHHW)in reduced Ga/H-ZSM-5,instead of the overall Ga_(2)O_(2)^(2+) species,by employing five H-ZSM-5 supports sourced differently with comparable Si/Al ratio.This disparity in Ga_(2)O_(2)^(2+) species stems from their differing capacity in completing the catalytic cycle.Spectroscopic results suggest that PDH proceeds via a two-step mechanism:(1)C-H bond activation of propane on H-Ga_(2)O_(2)^(2+) species(rate determining step);(2)β-hydride elimination of adsorbed propyl group,which only occurs on active Ga_(2)O_(2)^(2+) species corresponding to GaHHW. 展开更多
关键词 Propane dehydrogenation Ga_(2)O_(2)^(2+) activation of C-H bond Ga species
下载PDF
CoFe_(2)O_(4)/MXene复合材料的构筑及活化过氧单硫酸盐降解阿特拉津
2
作者 曹梦寒 徐鹏 +4 位作者 石凤银 李桂鄂 张国栋 郑庆柱 张广山 《应用化学》 CAS CSCD 北大核心 2024年第2期256-267,共12页
通过微波辅助水热法将双金属氧化物(CoFe_(2)O_(4))负载在MXene上,成功制备了CoFe_(2)O_(4)/MXene复合催化剂并用于活化过氧单硫酸盐(Peroxymonosulfate,PMS)。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)等技... 通过微波辅助水热法将双金属氧化物(CoFe_(2)O_(4))负载在MXene上,成功制备了CoFe_(2)O_(4)/MXene复合催化剂并用于活化过氧单硫酸盐(Peroxymonosulfate,PMS)。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)等技术手段对复合催化剂的结构、形貌和元素价态进行表征,发现CoFe_(2)O_(4)被成功负载到了MXene上。以阿特拉津(ATZ)为目标污染物,研究了CoFe_(2)O_(4)/MXene活化PMS降解ATZ体系中催化剂投加量、过硫酸盐浓度和pH值等因素对ATZ降解的影响。结果表明,在pH=6.35的条件下,当CoFe_(2)O_(4)/MXene(0.1 g/L)和PMS(0.37 mmol/L)用量较低时,ATZ的降解率在15 min内达到100%;并且该体系具有较广的pH值适用范围(2~10)和应用范围;淬灭实验表明,反应体系中自由基途径和非自由基途径均存在,其中SO_(4)•^(−)、O_(2)•^(−)和^(1)O_(2)占主导作用,共同作用于ATZ的降解过程。这项研究开发了具有优异催化性能的新型材料,可为CoFe_(2)O_(4)/MXene非均相催化剂活化PMS降解有机污染物提供新思路。 展开更多
关键词 Cofe_(2)O_(4)/MXene 微波水热 过氧单硫酸盐 阿特拉津 活性物种
下载PDF
Biocatalytic enhancement of laccase immobilized on ZnFe_(2)O_(4) nanoparticles and its application for degradation of textile dyes
3
作者 Yuhang Wei Qingpeng Zhu +3 位作者 Weiwei Xie Xinyue Wang Song Li Zhiming Chen 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第4期216-223,共8页
Efficient and convenient treatment of industrial dyeing wastewater is of great significance to guarantee human and animal health.This work presented the enhanced catalytic activity at pH 3.0 of laccase immobilized on ... Efficient and convenient treatment of industrial dyeing wastewater is of great significance to guarantee human and animal health.This work presented the enhanced catalytic activity at pH 3.0 of laccase immobilized on amino-functionalized ZnFe_(2)O_(4) nanoparticles(ZnFe_(2)O_(4)-laccase)and its application for the degradation of textile dyes.Due to the existence of a large number of oxygen vacancies on the surface of the ZnFe_(2)O_(4) nanoparticles,negative ions accumulated on the magnetic carriers,which resulted in a harsh optimal pH value of the ZnFe_(2)O_(4)-laccase.Laccase activity assays revealed that the ZnFe_(2)O_(4)-laccase possessed superior pH and thermal stabilities,excellent reusability,and noticeable organic solvent tolerance.Meanwhile,the ZnFe_(2)O_(4) laccase presented efficient and sustainable degradation of high concentrations of textile dyes.The initial decoloration efficiencies of malachite green(MG),brilliant green(BG),azophloxine,crystal violet(CV),reactive blue 19(RB19),and procion red MX-5B were approximately 99.1%,95.0%,93.3%,87.4%,86.1%,and 85.3%,respectively.After 10 consecutive reuses,the degradation rates of the textile dyes still maintained about 98.2%,92.5%,83.2%,81.5%,79.8%and 65.9%,respectively.The excellent dye degradation properties indicate that the ZnFe_(2)O_(4)-laccase has a technical application in high concentrations of dyestuff treatment. 展开更多
关键词 ZnFe_(2)O_(4)-laccase Catalytic activity Stability and reusability Degradation of textile dye
下载PDF
Protective effect of camellia oil on H_(2)O_(2)-induced oxidative stress injury in H9C2 cardiomyocytes of rats
4
作者 YAN Qing GUO Zhen +3 位作者 SUN Sai-nan LI Jing TAN Ji-yong LI Jing 《Journal of Hainan Medical University》 CAS 2024年第1期1-7,共7页
Objective: To explore the protective effect of camellia oil against H2O2-induced oxidative stress injury in rat H9C2 cardiomyocytes. Methods: CCK8 method was used to detect the cell survival rate of H9C2 cardiomyocyte... Objective: To explore the protective effect of camellia oil against H2O2-induced oxidative stress injury in rat H9C2 cardiomyocytes. Methods: CCK8 method was used to detect the cell survival rate of H9C2 cardiomyocytes treated with different concentrations of H2O2. Normal cultured cells were used as the blank control group, and the cells were treated with 200 μmol/L H2O2 for 24 h. An oxidative stress injury model was constructed as the model group. The cells were pretreated with 1%, 0.1% and 0.01% camellia oil for 24 h, and then H2O2 was added for 24 h as the experimental group. The β-galactosidase senescence staining assay, mitochondrial membrane potential assay, EdU cell proliferation staining assay and scratch assay were used to observe the changes of cell senescence, mitochondrial membrane potential, proliferation, apoptosis and migration in each group. The superoxide dismutase (SOD) activity, lactate dehydrogenase (LDH) activity, and malondialdehyde (MDA) content of the cells in each group were detected by using the kit. Results: The cell viability of H9C2 cardiomyocytes treated with different concentrations of H2O2 was inhibited and positively correlated with the concentration of H2O2 (P<0.01). Compared with the blank control group, the positive rate of cell senescence, MDA content and LDH activity increased in the H2O2 model group (P<0.01);mitochondrial membrane potential, cellular value-added rate, migration rate and SOD activity decreased (P<0.01). Compared with the H2O2 model group, the positive rate of cellular senescence (P<0.01 or P<0.05), MDA content and LDH activity decreased (P< 0.01 or P<0.05);mitochondrial membrane potential increased, cell proliferation rate and migration rate increased (P<0.01 or P<0.05) in the experimental group. Conclusion: Camellia oil can significantly inhibit oxidative stress injury in H9C2 cells and exert cardiomyocyte protective effects. 展开更多
关键词 Camellia oil H_(2)O_(2) H9C2 Oxidative stress Protective
下载PDF
Active Cancelation of Acoustic Noise in Waveguides by Standard Control Task Decision Usage
5
作者 Alexey A. Pudovkin 《Journal of Applied Mathematics and Physics》 2024年第4期1188-1202,共15页
Cybernetic decision variants were analyzed in order to use for physical task of active noise cancelation. 10 dB mean active noise cancellation is demonstrated in two decades frequency band by usage of cybernetic decis... Cybernetic decision variants were analyzed in order to use for physical task of active noise cancelation. 10 dB mean active noise cancellation is demonstrated in two decades frequency band by usage of cybernetic decision for acoustical duct physical scale model. The used decision was found on minimization of acoustical field power transfer function from the beginning of waveguide to their end. 展开更多
关键词 Waveguide Noise Active Cancelation CONTROL Synthesis Procedure H2
下载PDF
Modulation of gastric mucosal inflammatory responses to <i>Helicobacter pylori</i>by ghrelin: Role of cNOS-dependent IKK-<i>β</i>S-nitrosylation in the regulation of COX-2 activation 被引量:4
6
作者 Bronislaw L. Slomiany Amalia Slomiany 《American Journal of Molecular Biology》 2012年第2期113-123,共11页
Disturbances in nitric oxide synthase (NOS) and cyclooxygenase (COX) isozyme systems, manifested by the excessive NO and prostaglandin (PGE2) generation, are well-recognized features of gastric mucosal inflammatory re... Disturbances in nitric oxide synthase (NOS) and cyclooxygenase (COX) isozyme systems, manifested by the excessive NO and prostaglandin (PGE2) generation, are well-recognized features of gastric mucosal inflammatory responses to H. pylori infection. In this study, we report that H. pylori LPS-induced enhancement in gastric mucosal inducible (i) iNOS expression and COX-2 activation was accompanied by the impairment in constitutive (c) cNOS phosphorylation, up-regulation in the inhibitory κB kinase-β (IKKβ) activation and the increase in the transcriptional factor, NF-κB, nuclear translocation. Further, we show that abrogation of cNOS control over NF-κB activation has lead to induction of iNOS expression and COX-2 activation through S-nitrosylation. Moreover, we demonstrate that the modulatory effect of peptide hormone, ghrelin, on the LPS-induced changes was reflected in the increase in Src/Akt-dependent cNOS activation through phosphorylation and the suppression of IKK-β activity through cNOS-mediated IKK-β protein S-nitrosylation. As a result, ghrelin exerted the inhibitory effect on NF-κB nuclear translocation, thus causing the repression of iNOS gene induction and the inhibition in COX-2 activation through iNOS-dependent S-nitrosylation. Our findings point to cNOS activation as a pivotal element in the signaling cascade by which ghrelin exerts modulatory control over proinflammatory events triggered in gastric mucosa by H. pylori infection. 展开更多
关键词 H. pylori Gastric Mucosa iNOS Induction COX-2 activation GHRELIN cNOS Phosphorylation IKK-β S-NITROSYLATION
下载PDF
CoFe_(2)O_(4)/MnO_(2)活化过一硫酸盐降解盐酸四环素的研究 被引量:1
7
作者 张贤胜 孙婧雯 刘智峰 《能源环境保护》 2023年第5期57-70,共14页
针对四环素类抗生素污染物在水中不断累积,对人体健康和生态环境造成严重危害这一问题,本研究制备了CoFe_(2)O_(4)/MnO_(2)新型复合材料,并将其作为高效过一硫酸盐(PMS)活化剂,用于降解水体中的盐酸四环素(TCH)。降解结果表明CoFe_(2)O_... 针对四环素类抗生素污染物在水中不断累积,对人体健康和生态环境造成严重危害这一问题,本研究制备了CoFe_(2)O_(4)/MnO_(2)新型复合材料,并将其作为高效过一硫酸盐(PMS)活化剂,用于降解水体中的盐酸四环素(TCH)。降解结果表明CoFe_(2)O_(4)/MnO_(2)-PMS体系具有突出的TCH去除效率,反应40 min后,去除率可达92.7%,远高于单一催化剂-PMS体系。影响因素实验结果显示,CoFe_(2)O_(4)/MnO_(2)-PMS降解体系具有广泛的pH适用性,并且在各种阴离子的存在下仍能保持较高的降解活性。此外,CoFe_(2)O_(4)/MnO_(2)-PMS降解体系具有良好的稳定性和可重复利用性,在5次循环后仍保持较高的催化活性和TCH降解率。机理分析表明CoFe_(2)O_(4)/MnO_(2)复合材料在催化PMS降解TCH的过程中,存在Co^(2+)/Co^(3+)、Fe^(3+)/Fe^(2+)和Mn^(3+)/Mn^(4+)的价态循环并参与电子转移过程,从而使得活化过程中SO_(4)^(-)·和·OH被充分释放,并通过一系列典型的链式反应高效降解TCH。 展开更多
关键词 高级氧化技术 过硫酸盐活化 硫酸根自由基 Cofe_(2)O_(4)/MnO_(2) 盐酸四环素
下载PDF
Activation of Carcinogenic Non-aminoazo Compounds iu Horseradish Peroxidase/H_2O_2 System
8
作者 Min ZHU Xue Mei HUANG and Han Xi SHEN (Department of Chemistry, Nankai University, Tianjin, 300071) 《Chinese Chemical Letters》 SCIE CAS CSCD 1997年第11期979-982,共4页
Eriochrome black T and Nitrosulfophenol S were advocated as the chemical models of carcinogenic non-aminoazo compounds. The main products of their oxidative cleavage in horseradish peroxidase/H2O2 system was identifie... Eriochrome black T and Nitrosulfophenol S were advocated as the chemical models of carcinogenic non-aminoazo compounds. The main products of their oxidative cleavage in horseradish peroxidase/H2O2 system was identified as the benezenediazonium ion, the ultimate carcinogens, which could bind to DNA. The reaction conditions were investigated preliminarily. Some inhibitors and inducers of the reaction were discovered. 展开更多
关键词 MILLER activation of Carcinogenic Non-aminoazo Compounds in Horseradish Peroxidase/H2O2 System
下载PDF
CoFe_(2)O_(4)@Zeolite催化剂活化过一硫酸盐对甲基橙的强化降解:性能与机理
9
作者 王磊 李建军 +4 位作者 宁军 胡天玉 王洪阳 张占群 武琳馨 《无机材料学报》 SCIE EI CAS CSCD 北大核心 2023年第4期469-476,共8页
采用共沉淀水热法制备了CoFe_(2)O_(4)@Zeolite(CFZ),并将其用于活化过一硫酸盐(PMS)降解合成染料。综合表征表明,组成多孔壳层的CoFe_(2)O_(4)纳米颗粒均匀地覆盖在Na-A沸石上。CFZ的比表面积为107.06 m^(2)/g,是原始沸石比表面积的3倍... 采用共沉淀水热法制备了CoFe_(2)O_(4)@Zeolite(CFZ),并将其用于活化过一硫酸盐(PMS)降解合成染料。综合表征表明,组成多孔壳层的CoFe_(2)O_(4)纳米颗粒均匀地覆盖在Na-A沸石上。CFZ的比表面积为107.06 m^(2)/g,是原始沸石比表面积的3倍。CFZ的饱和磁化强度为29.0 A·m^(2)·kg^(–1),可以进行有效磁分离。催化降解实验表明,CFZ/PMS体系对甲基橙(MO)的去除率远远高于单独使用CFZ或PMS。在最佳条件([MO]=50 mg/L、[PMS]=1.0 mmol/L、0.2 g/L CFZ、pH 8和T=25℃)下,MO去除率可达到97.1%。实验研究了pH、PMS用量、CFZ用量、MO浓度以及共存阴离子等因素对CFZ催化性能的影响。活性氧粒子淬灭实验表明,1O2和O_(2)^(•–)在降解过程中起主导作用。CFZ具有良好的回收性能,5次循环后MO去除效率仅下降2.4%。本文还详细讨论了CFZ/PMS体系的催化降解机理。 展开更多
关键词 高级氧化技术 过一硫酸盐活化 磁性催化剂 Cofe_(2)O_(4)@Zeolite 活性氧粒子 降解
下载PDF
Effect of ZnO,La_(2)O_(3),and YF_(3)on Crystallization and Rehological Behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)Glass
10
作者 王君 GAO Shengnan +6 位作者 ZHENG Qingshuang ZHANG Xiaowei ZHANG Dongliang XIONG Dehua JIN Siqingaowa 王觅堂 焦国豪 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第4期753-758,共6页
The effect of substitution La_(2)O_(3)and YF_(3)as network modifiers respectively for Y_(2)O_(3),and ZnO as intermediate oxide for Al_(2)O_(3)on crystallization and viscous behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)gl... The effect of substitution La_(2)O_(3)and YF_(3)as network modifiers respectively for Y_(2)O_(3),and ZnO as intermediate oxide for Al_(2)O_(3)on crystallization and viscous behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass was studied.La_(2)O_(3)and YF_(3)substitution for Y_(2)O_(3)decreases the melting temperature of studied glass from 1402 to 1346 and 1379℃,and the activation energy of viscous flow decreases from 340 to 250 and 265 kJ/mol.Meanwhile,ZnO substitution for Al_(2)O_(3)decreases the melting temperature to 1379℃while increases the activation energy of viscous flow to 542 kJ/mol,due to their different role in glass structure.Substitution ZnO for Al_(2)O_(3)refines and homogenizes the crystals size and lowers crystallinity because the nucleation and crystal growth are depressed by higher activation energy of crystallization and change of crystallization mechanism from bulk crystallization to surface crystallization.Replacement of Y_(2)O_(3)by La_(2)O_(3)and YF_(3)respectively also decreases the crystallinity of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass ceramic due to competitive and hindering effect on the rearranged atoms,structural units and groups required by precipitated two crystals.Besides,y-Y2Si2O7,precipitation of Y4.67(SiO4)3O,ZnAl_(2)O_(4),and Y3Si3O10F were observed respectively due to incorporation of La_(2)O_(3),ZnO,and YF_(3). 展开更多
关键词 Y_(2)O_(3) aluminosilicate glass CRYSTALLIZATION viscous activation energy
下载PDF
Formation of Polytypoids(12H and 21R)in High Temperature Nitrogen Atmosphere and Their Effects on SiC-MgAl_(2)O_(4) Composites
11
作者 GU Chenwei WANG Zhanmin +2 位作者 ZHAO Shixian SI Yaochen XIA Miao 《China's Refractories》 CAS 2023年第2期45-50,共6页
SiC-MgAl_(2)O_(4) composites with SiAlON polytypoids(12H and 21R)as the bonding phases were prepared using SiC fine powder,MgAl_(2)O_(4)fine powder and Al powder as raw materials.The effects of the firing temperature ... SiC-MgAl_(2)O_(4) composites with SiAlON polytypoids(12H and 21R)as the bonding phases were prepared using SiC fine powder,MgAl_(2)O_(4)fine powder and Al powder as raw materials.The effects of the firing temperature and the mass ratio of SiC to MgAl_(2)O_(4) on the formation of SiAlON polytypoids as well as on the properties of samples were studied.The formation mechanism of SiAlON polytypoids was discussed.The results show that firing at 1650℃in the nitrogen atmosphere,SiC-MgAl_(2)O_(4) composites with SiAlON polytypoids can be obtained.With the gradual increase of the mass ratio of SiC to MgAl_(2)O_(4) in the raw materials,12H forms first,and then coexists with 21H,finally,all 12H converts into 21R in samples.Both phases are plate crystals with flat and smooth edges.Compared with 21R,12H is conducive to improving the density and the cold mechanical properties of materials.After firing at 1650℃in the nitrogen atmosphere,with the mass ratio of SiC to MgAl_(2)O_(4) of 6:4,the sample has the cold modulus of rupture of 27 MPa,showing the optimal performance. 展开更多
关键词 silicon carbide MgAl_(2)O_(4) silicon carbide-MgAl_(2)O_(4)composites SiAION polytypoids 12H 21R
下载PDF
Accurate design of spatially separated double active site in Bi_(4)NbO_(8)Cl single crystal to promote Z-Scheme photocatalytic overall water splitting
12
作者 Kailong Gao Hongxia Guo +4 位作者 Yanan Hu Hongbin He Mowen Li Xiaoming Gao Feng Fu 《Journal of Energy Chemistry》 SCIE EI CSCD 2023年第12期568-582,I0014,共16页
The efficiency of photocatalytic overall water splitting was mainly limited by the slow reaction kinetics of water oxidation.How to design effective surface active site to overcome the slow water oxidation reaction wa... The efficiency of photocatalytic overall water splitting was mainly limited by the slow reaction kinetics of water oxidation.How to design effective surface active site to overcome the slow water oxidation reaction was a major challenge.Here,we propose a strategy to accelerate surface water oxidation through the fabrication spatially separated double active sites.FeCoPi/Bi_(4)NbO_(8)Cl-OVs photocatalyst with spatially separated double active site was prepared by hydrogen reduction photoanode deposition method.Due to the high matching of the spatial loading positions of FeCoPi and OVs with the photogenerated charge distribution of Bi_(4)NbO_(8)Cl and corresponding reaction mechanisms of substrate,the FeCoPi and OVs on the(001)and(010)crystal planes of Bi_(4)NbO_(8)Cl photocatalyst provided surface active site for water oxidation reaction and electron shuttle reaction(Fe^(3+)/Fe^(2+)),respectively.Under visible light irradiation,the evolution O_(2)rate of FeCoPi/Bi_(4)NbO_(8)Cl OVs was 16.8μmol h^(-1),as 32.9 times as Bi_(4)NbO_(8)Cl.Furthermore,a hydrogen evolution co-catalyst PtRu@Cr_(2)O_(3)was prepared by sequential photodeposition method.Due to the introduction of Ru,the Schottky barrier between PbTiO_(3)and Pt was effectively reduced,which promoted the transfer of photogenerated electrons to PtRu@Cr_(2)O_(3)thermodynamically,the evolution H_(2)rate on PtRu@Cr_(2)O_(3)/PbTiO_(3)increased to 664.8 times.On based of the synchronous enhancement of the water oxidation performance on FeCoPi/Bi_(4)NbO_(8)Cl-OVs and water reduction performance on PtRu@Cr_(2)O_(3)/PbTiO_(3),a novel Z-Scheme photocatalytic overall water splitting system(FeCoPi/Bi_(4)NbO_(8)Cl-OVs)mediated by Fe^(3+)/Fe^(2+)had successfully constructed.Under visible light irradiation,the evolution rates of H_(2)and O_(2)were 2.5 and 1.3μmol h^(-1),respectively.This work can provide some reference for the design of active site and the controllable synthesis of OVs spatial position.On the other hand,the hydrogen evolution co catalyst(PtRu@Cr_(2)O_(3))and the co catalyst FeCoPi for oxygen evolution contributed to the construction of an overall water splitting system. 展开更多
关键词 Spatially separated double active sites FeCoPi/Bi_(4)NbO_(8)Cl-OVs Photocatalytic water oxidation Photocatalytic hydrogen evolution Hydrogen evolution co-catalyst PtRu@Cr_(2)O_(3) Z-Scheme photocatalytic overall water splitting system
下载PDF
Al_(2)O_(3)-Ce_(2)O_(3)复合薄膜对304不锈钢抗高温氧化性能的影响
13
作者 马静 王铁凝 +3 位作者 姜秋月 冯志浩 张欣 李建辉 《材料保护》 CAS CSCD 2024年第10期19-26,共8页
为提高304不锈钢的抗高温氧化性能,采用溶胶-凝胶法以异丙醇铝和CeCl_3·7H_(2)O为原料,在304不锈钢表面分别制备了Al_(2)O_(3)薄膜和Al_(2)O_(3)-Ce_(2)O_(3)复合薄膜,通过氧化动力学曲线、XRD、SEM和EDS分析,研究了不同Ce/Al比例... 为提高304不锈钢的抗高温氧化性能,采用溶胶-凝胶法以异丙醇铝和CeCl_3·7H_(2)O为原料,在304不锈钢表面分别制备了Al_(2)O_(3)薄膜和Al_(2)O_(3)-Ce_(2)O_(3)复合薄膜,通过氧化动力学曲线、XRD、SEM和EDS分析,研究了不同Ce/Al比例(摩尔比,下同)的Al_(2)O_(3)-Ce_(2)O_(3)复合薄膜对304不锈钢900℃抗高温氧化性能的影响。结果表明,涂覆Ce∶Al=1∶10的薄膜试样在900℃循环氧化100 h后的氧化增重与氧化剥落量仅为未涂覆试样的34.1%和51.8%,抗高温氧化性能最佳。Al_(2)O_(3)-Ce_(2)O_(3)复合薄膜降低了304不锈钢基体表面的氧分压,有利于生成保护性的Cr_2O_(3)氧化层,有效抑制了Cr_2O_(3)的挥发;添加Ce_(2)O_(3)降低了氧化层中的热应力,提高了其附着力;Ce_(2)O_(3)起到了活性元素效应,改变了氧化膜的生长机制,因此显著提高了不锈钢的抗高温氧化性能。 展开更多
关键词 溶胶-凝胶法 Al_(2)O_(3)-Ce_(2)O_(3)复合薄膜 高温氧化 活性元素效应
下载PDF
免疫检查点T细胞激活抑制物免疫球蛋白可变区结构域、人内源性逆转录病毒-H长端重复相关蛋白2在子宫内膜癌中的表达及临床意义
14
作者 柴静 张家弘 李梦雪 《中国性科学》 2024年第4期118-121,共4页
目的分析免疫检查点T细胞激活抑制物免疫球蛋白可变区结构域(VISTA)、人内源性逆转录病毒-H长端重复相关蛋白2(HHLA2)在子宫内膜癌(EC)中的表达及临床意义。方法选取2017年9月至2019年10月唐山市妇幼保健院收治的120例的EC患者作为研究... 目的分析免疫检查点T细胞激活抑制物免疫球蛋白可变区结构域(VISTA)、人内源性逆转录病毒-H长端重复相关蛋白2(HHLA2)在子宫内膜癌(EC)中的表达及临床意义。方法选取2017年9月至2019年10月唐山市妇幼保健院收治的120例的EC患者作为研究对象,收集其的EC组织和癌旁正常组织。检测EC组织和癌旁正常组织VISTA、HHLA2的表达;采用Spearman分析免疫检查点VISTA、HHLA2的相关性;Kaplan-Meier分析VISTA、HHLA2与预后的关系;Cox回归分析影响EC患者预后的危险因素。结果EC组织中VISTA、HHLA2阳性表达率显著高于正常癌旁组织(P<0.05)。Spearman相关性结果显示EC组织中VISTA与HHLA2表达呈正相关性(r=0.587,P<0.05)。EC组织中VISTA、HHLA2表达与临床病理特征有关(P<0.05)。Kaplan-Meier曲线结果显示VISTA阳性表达患者3年生存率低于阴性表达患者(χ^(2)=11.864,P<0.05),HHLA2阳性表达患者3年生存率低于阴性表达患者(χ^(2)=4.975,P<0.05)。Cox回归分析结果显示VISTA和HHLA2是影响EC患者预后的危险因素(P<0.05)。结论免疫检查点VISTA、HHLA2在EC中高表达,其是影响EC预后的危险因素,二者可能是有价值的预后标志物。 展开更多
关键词 T细胞激活抑制物免疫球蛋白可变区结构域 人内源性逆转录病毒-H长端重复相关蛋白2 子宫内膜癌 预后
下载PDF
复合催化剂S-CuCo_(2)O_(4)的制备及其活化PMS降解CIP性能研究 被引量:1
15
作者 张孟洋 侯东睿 +3 位作者 罗静 孙庆功 杨豪 王剑峰 《广西师范大学学报(自然科学版)》 CAS 北大核心 2024年第1期156-167,共12页
采用水热法,以硫脲为硫源对CuCo_(2)O_(4)进行硫化处理合成S-CuCo_(2)O_(4),对复合催化剂S-CuCo_(2)O_(4)进行XRD、FT-IR、SEM、XPS、ICP-OES、EPR表征,并考察其活化过一硫酸盐(PMS)降解环丙沙星(ciprofloxacin,CIP)的效果。实验结果表... 采用水热法,以硫脲为硫源对CuCo_(2)O_(4)进行硫化处理合成S-CuCo_(2)O_(4),对复合催化剂S-CuCo_(2)O_(4)进行XRD、FT-IR、SEM、XPS、ICP-OES、EPR表征,并考察其活化过一硫酸盐(PMS)降解环丙沙星(ciprofloxacin,CIP)的效果。实验结果表明:成功制备出S-CuCo_(2)O_(4)催化剂,在其表面富含Co(Ⅱ)和Cu(Ⅰ);当催化剂投加量为0.06 g/L、PMS投加量为0.2 g/L、pH=6.4时,复合催化剂S-CuCo_(2)O_(4)在25 min后对CIP的降解效率可达96.8%,降解效果明显优于CuCo_(2)O_(4)、CuCo_(2)S_(4)。自由基淬灭实验和EPR测试表明,SO_(4)^(-)·和^(1)O_(2)是反应体系的主要活性氧物种,其可能的催化机理是:Cu(Ⅰ)和Co(Ⅱ)能直接与PMS反应生成自由基,同时Cu(Ⅰ)能还原Co(Ⅲ)生成Co(Ⅱ),促进Co(Ⅱ)/Co(Ⅲ)循环,催化剂表面存在的氧空位也可与PMS反应生成^(1)O_(2),在活性氧物种的共同作用下CIP被高效降解。复合催化剂S-CuCo_(2)O_(4)在4次循环使用后对CIP的降解效率仍可达93.5%,证明其循环稳定性较好;对其他污染物也有较好的降解效率,具有较好的通用性,在废水处理中具有良好的应用前景。 展开更多
关键词 环丙沙星 过一硫酸盐 活化 降解 非均相催化剂 CuCo_(2)O_(4) 硫化
下载PDF
H_(2)O_(2)降解多糖的作用机制及降解产物构效关系研究进展
16
作者 彭谦 周鹏程 +2 位作者 徐同成 李富军 宗爱珍 《食品与发酵工业》 CAS CSCD 北大核心 2024年第19期353-360,共8页
多糖因其优异的生物活性而备受关注,但由于其大分子结构较难以被人体直接利用。近年来,关于降解多糖的研究已成为新的热点,多糖的降解的方式有很多,其中自由基降解多糖有着对降解程度的可控性以及生产成本低等独特的优势。因此有必要了... 多糖因其优异的生物活性而备受关注,但由于其大分子结构较难以被人体直接利用。近年来,关于降解多糖的研究已成为新的热点,多糖的降解的方式有很多,其中自由基降解多糖有着对降解程度的可控性以及生产成本低等独特的优势。因此有必要了解多糖降解机制以及探究降解产物的构效关系,以期对多糖高值化利用。该文首先系统全面地介绍了H_(2)O_(2)产生自由基进而介导多糖降解的研究进展,重点阐述了H_(2)O_(2)产生自由基的机制,剖析了自由基降解多糖的机理,分析了自由基对于多糖降解产物构效关系的影响。该综述对多糖降解产物的生物构效关系解析和高值化开发提供理论依据。 展开更多
关键词 多糖 H_(2)O_(2) 自由基 构效关系 生物活性
下载PDF
中性条件Fe/Cu-MCM-41光催化活化H_(2)O_(2)/PDS的构-效关系
17
作者 张传波 熊志超 +4 位作者 邓佩 刘力章 冯斐 邵莉 陈建新 《环境化学》 CAS CSCD 北大核心 2024年第6期2036-2046,共11页
本文在室温下制备了Fe-MCM-41和Cu-MCM-41,利用XRD、BET、SEM和TEM等手段对催化剂进行了表征.选取金橙Ⅱ为探针分子、H_(2)O_(2)和PDS作为氧化剂,构建了多相光催化氧化体系,研究中性条件下Fe-MCM-41和Cu-MCM-41光催化活化H_(2)O_(2)和PD... 本文在室温下制备了Fe-MCM-41和Cu-MCM-41,利用XRD、BET、SEM和TEM等手段对催化剂进行了表征.选取金橙Ⅱ为探针分子、H_(2)O_(2)和PDS作为氧化剂,构建了多相光催化氧化体系,研究中性条件下Fe-MCM-41和Cu-MCM-41光催化活化H_(2)O_(2)和PDS的构-效关系.结果表明,Fe-MCM-41为同晶替换型催化剂,Cu-MCM-41为同晶替换和CuO孤岛共存型催化剂.中性条件下,H_(2)O_(2)受空间位阻和电性排斥影响小,能被Fe-MCM-41孔道内外铁离子高效光催化产生·OH,但难以被Cu-MCM-41中同晶替换和孤岛的铜离子高效光催化;PDS由于受到空间位阻和电性排斥的影响,难以进入Fe-MCM-41和Cu-MCM-41孔道之中,但Cu-MCM-41表面和孤岛上的铜离子能高效光催化PDS产生^(1)O_(2)和SO_(4)^(−·)·UV+H_(2)O_(2)体系中加入Fe-MCM-41,金橙Ⅱ的脱色速率提升了52.9%,反应180 min时体系矿化率从43%提高到了57%;UV+PDS体系中加入Cu-MCM-41,金橙Ⅱ的脱色速率提升了38.7%,反应180 min时体系矿化率从48%提高到了76%.本研究为介孔分子筛光催化剂的开发利用提供理论依据. 展开更多
关键词 MCM-41 过氧化氢 过二硫酸盐 光催化活化 构-效关系
下载PDF
山茶油对H_(2)O_(2)诱导大鼠H9C2心肌细胞氧化应激损伤的保护作用
18
作者 晏庆 郭蓁 +3 位作者 孙赛男 黎婧 谭机永 黎静 《海南医学院学报》 北大核心 2024年第1期1-7,共7页
目的:探讨山茶油对H_(2)O_(2)诱导大鼠H9C2心肌细胞氧化应激损伤的保护作用。方法:CCK8法检测不同浓度H_(2)O_(2)处理H9C2心肌细胞后细胞存活率,以正常培养的细胞为空白对照组,以200μmol/L H_(2)O_(2)处理细胞24 h,构建氧化应激损伤模... 目的:探讨山茶油对H_(2)O_(2)诱导大鼠H9C2心肌细胞氧化应激损伤的保护作用。方法:CCK8法检测不同浓度H_(2)O_(2)处理H9C2心肌细胞后细胞存活率,以正常培养的细胞为空白对照组,以200μmol/L H_(2)O_(2)处理细胞24 h,构建氧化应激损伤模型作为模型组。分别用1%,0.1%,0.01%浓度的山茶油预处理细胞24 h后,加入H_(2)O_(2)作用24 h作为实验组。利用β-半乳糖苷酶衰老染色实验,线粒体膜电位实验,EdU细胞增殖染色实验及划痕实验来观察各组细胞衰老,线粒体膜电位,增殖凋亡,迁移的变化。利用试剂盒检测各组细胞超氧化物歧化酶(SOD)活性、乳酸脱氢酶(LDH)活性、丙二醛(MDA)含量。结果:不同浓度H_(2)O_(2)处理H9C2心肌细胞后,细胞活力均受到抑制,且与H_(2)O_(2)浓度正相关(P<0.01)。与空白对照组相比,H_(2)O_(2)模型组细胞衰老阳性率、MDA含量和LDH活性增加(P<0.01);线粒体膜电位、细胞增殖率、迁移率、SOD活性下降(P<0.01)。与H_(2)O_(2)模型组相比,实验组细胞衰老阳性率(P<0.05)、MDA含量和LDH活性降低(P<0.05);线粒体膜电位增加、细胞增殖率和迁移率增加(P<0.05)。结论:山茶油可显著抑制H9C2细胞的氧化应激损伤,发挥心肌细胞保护作用。 展开更多
关键词 山茶油 H_(2)O_(2) H9C2 氧化应激 保护
下载PDF
有机-有机界面效应的原位及非原位研究
19
作者 冀连连 王现鹏 +7 位作者 张莹莹 申学礼 薛娣 王璐 王滋 王文冲 黄丽珍 迟力峰 《物理化学学报》 SCIE CAS CSCD 北大核心 2024年第1期30-31,共2页
有机-有机异质结构已被广泛应用于各种有机电子器件,包括有机发光二极管(OLEDs)、有机场效应晶体管(OFETs)和有机太阳能电池等。全面理解有机-有机异质结构的界面效应,对于器件的设计和性能优化具有重要意义。然而由于有机半导体具有多... 有机-有机异质结构已被广泛应用于各种有机电子器件,包括有机发光二极管(OLEDs)、有机场效应晶体管(OFETs)和有机太阳能电池等。全面理解有机-有机异质结构的界面效应,对于器件的设计和性能优化具有重要意义。然而由于有机半导体具有多样的化学特性以及分子间较弱的范德华力,界面电荷传输特性与有机-有机电子结构、环境气氛等密切相关。在此,我们报道了随着顶层半导体并五苯(pentacene)的沉积,并五苯/酞菁氧钒(VOPc)异质结构的原位实时电学性能监测。结果显示,异质结构晶体管的p型迁移率从0.4 cm2∙V−1∙s^(−1)下降至0.2 cm2∙V−1∙s^(−1),而n型迁移率从0.01 cm2∙V−1∙s^(−1)迅速增加至约0.9 cm2∙V−1∙s^(−1)。这种n型输运行为的增强归因于pentacene向VOPc的界面电子转移效应以及由此导致的VOPc层中陷阱态的填充。此外,非原位实验对比表明,当晶体管制备过程暴露于大气时会明显抑制这种界面电荷转移效应,导致沉积pentacene后n型输运几乎没有得到改善。薄膜形态、开尔文探针力显微镜(KPFM)和X射线光电子能谱(XPS)的结果表明,界面处存在从pentacene到VOPc的电子转移。进一步的密度泛函理论(DFT)计算表明,由于pentacene/VOPc之间较强的相互作用,pentacene往VOPc的电荷转移量约为0.15 e。此外,O_(2)/H2O的存在会抑制这种界面电荷转移效应,这与我们的实验结果一致。本研究通过原位电学表征对有机-有机界面之间的电荷转移效应给出了深入解释,有利于进一步的器件性能优化及界面效应分析。 展开更多
关键词 有机-有机异质结构 原位表征 电荷转移效应 有机场效应晶体管 O_(2)/H2O掺杂
下载PDF
纳米Ce_(1-4x)(FeAlCoLa)_(x)O_(2-δ)固溶体微观光谱特征及氧化还原性能研究
20
作者 孙世龙 张国芳 +5 位作者 束俊 郭瑞华 李一鸣 刘卓承 许剑轶 葛启录 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2024年第7期1883-1888,共6页
采用水热法合成Fe^(3+)、Al^(3+)、Co^(2+)及La^(3+)共掺杂纳米Ce_(1-4x)(FeAlCoLa)_(x)O_(2-δ)(x=0.00~0.05)固溶体,利用X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、紫外吸收光谱(UV)、荧光光谱(PL)、拉曼光谱(Raman... 采用水热法合成Fe^(3+)、Al^(3+)、Co^(2+)及La^(3+)共掺杂纳米Ce_(1-4x)(FeAlCoLa)_(x)O_(2-δ)(x=0.00~0.05)固溶体,利用X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、紫外吸收光谱(UV)、荧光光谱(PL)、拉曼光谱(Raman)以及与H2的程序升温还原反应(TPR)等方法对固溶体的微观结构、形貌、光谱特征和氧化还原活性进行系统表征及分析。XRD结果表明,Ce_(1-4x)(FeAlCoLa)_(x)O_(2-δ)固溶体均呈CeO_(2)立方萤石结构,当掺杂量增加到x=0.04时,在36.6°处出现了微弱的Co_(3)O_(4)杂相,可以确定掺杂离子在CeO_(2)晶格中的固溶度x<0.04。样品的(111)衍射峰位向高角度偏移,表明掺杂离子引起晶格发生畸变。TEM及SEM结果显示样品为球形纳米颗粒,掺杂离子引起晶面间距变小。紫外吸收光谱表明,与纯CeO_(2)相比,掺杂样品的吸收边逐渐红移,在560~780 nm范围观察到掺杂离子的紫外吸收峰。掺杂引起样品能隙降低,从2.84 eV(纯CeO_(2))逐渐降低至2.10 eV(x=0.05)。其原因可归结为掺杂离子在CeO_(2)的价带和导带之间形成新的杂质能级,允许电子从价带跃迁到较低的杂质能级上,继而降低了跃迁能隙。由于掺杂离子引起晶格内部发生畸变以及氧空位比例增大,阻碍了电子的高能跃迁,也可引起能隙减小。荧光光谱证明,掺杂样品的发射峰强度明显降低。Raman光谱表明,掺杂引起F_(2g)峰位发生偏移,峰强减小,峰宽变大。同时,对应于氧空位峰的相对强度逐渐提高。荧光光谱及Raman光谱均证明掺杂离子引起固溶体晶格畸变程度增加,氧空位浓度提高。H_(2)-TPR测试表明,掺杂可以有效降低CeO_(2)的氧化还原反应温度,提高氧化还原活性,当x=0.03的样品表面还原温度最低,还原峰的面积最大,即氧化还原反应活性最佳,表明样品的氧化还原性能与晶粒尺寸、晶格缺陷及氧空位浓度密切相关。通过以上研究证明,四种离子共掺杂CeO_(2)能够有效修饰微观晶体结构,在较低掺杂浓度下即可显著改善样品的催化活性。 展开更多
关键词 纳米Ce_(1-4x)(FeAlCoLa)_(x)O_(2-δ)固溶体 共掺杂 氧空位 氧化还原活性
下载PDF
上一页 1 2 19 下一页 到第
使用帮助 返回顶部