Histidine(His),as the most chemically active and versatile member among the 20 natural amino acids,plays a key role in the coordination of copper(Ⅱ)(Cu(Ⅱ))in biological systems.Cu(II)-His species are ubiquitous in m...Histidine(His),as the most chemically active and versatile member among the 20 natural amino acids,plays a key role in the coordination of copper(Ⅱ)(Cu(Ⅱ))in biological systems.Cu(II)-His species are ubiquitous in metalloenzymes and proteins associated with various neurodegenerative diseases,where they regulate catalytic activity and mediate intracellular copper transport.While the steric influence of His is known to dictate donor group selection in Cu(Ⅱ)coordination,the extent of these constraints on peptide complexes remains unclear.In this study,we employed a multi-spectroscopic approach(FTIR,2D IR,UV-Vis,EPR,and NMR)to systematically investigate pH-dependent Cu(Ⅱ)coordination in three tripeptides.Our results demonstrate that Cu(Ⅱ)coordination geometries are cooperatively determined by both the protonation state of the N-terminus and the steric constraints imposed by the His residue.展开更多
Engineering the morphology of the support is effective in tuning the redox properties of active metals for efficient catalytic methane combustion via tailoring the metal-support interaction.Herein,uniform Ir nanoparti...Engineering the morphology of the support is effective in tuning the redox properties of active metals for efficient catalytic methane combustion via tailoring the metal-support interaction.Herein,uniform Ir nanoparticles supported on anatase TiO_(2)with different morphologies predominantly exposing{100},{101},and{001}planes were synthesized and tested for methane combustion.The CH_(4) catalytic activity shows a remarkable TiO_(2)-facet-dependent effect and follows the order of Ir/TiO_(2)-{100}>Ir/TiO_(2)-{101}>>Ir/TiO_(2)-{001}.Detailed characterizations and DFT calculations reveal that compared with Ir-TiO_(2)-{101}and Ir-TiO_(2)-{001}interfaces,the superior Ir-TiO_(2)-{100}interface facilitates the generation of electron-rich Ir species through more profound charge transfer from TiO_(2)-{100}to Ir atoms.The electron-rich Ir structure,featuring abundant defect oxygen vacancies,significantly enhances the redox properties of active Ir species and reduces the activation energy for breaking the initial C-H bond in CH_(4),resulting in the superior catalytic activity for methane combustion.These findings deepen fundamental insights into the TiO_(2)-facet-dependent reactivity of different Ir/TiO_(2)nanomaterials in methane oxidation and pave the way for designing efficient Ir-based methane oxidation catalysts.展开更多
目的:探讨针刺对2型糖尿病(T2DM)大鼠肝组织胰岛素受体底物1和2基因(IRS1和2mRNA)表达的影响。方法:给食源性肥胖大鼠腹腔注射小剂量链脲佐菌素(STZ)(25mg/kg)造模成T2DM大鼠,随机分为针刺组、优降糖组和模型组,处理4周后,用快速血糖仪...目的:探讨针刺对2型糖尿病(T2DM)大鼠肝组织胰岛素受体底物1和2基因(IRS1和2mRNA)表达的影响。方法:给食源性肥胖大鼠腹腔注射小剂量链脲佐菌素(STZ)(25mg/kg)造模成T2DM大鼠,随机分为针刺组、优降糖组和模型组,处理4周后,用快速血糖仪检测空腹血糖(FBS)、用放免法检测空腹胰岛素(FINS)、用实时定量荧光PCR(real-tim e RT PCR)法检测肝组织IRS1和2mRNA表达,并与正常组大鼠进行对照。结果:针刺组和优降糖组FBS和FINS比模型组显著降低(P<0.05);模型组IRS1mRNA相对含量是正常组的25%,针刺组为正常组的2.83倍,优降糖组为正常组的1.23倍。模型组IRS2mRNA相对含量为正常组的2.19倍,针刺组IRS2mRNA相对含量为正常组的4.84%,优降糖组IRS2mRNA相对含量为正常组的4.59倍。结论:肝组织IRS1和2mRNA表达异常可能是T2DM的发病机制之一,针刺和优降糖均可上调T2DM大鼠肝组织IRS1mRNA的表达,针刺对T2DM大鼠肝组织IRS1 mRNA表达的上调作用优于优降糖;针刺具有显著抑制T2DM大鼠肝组织IRS2mRNA表达的作用,而优降糖无此作用。展开更多
以2-氯喹啉和苯硼酸为原料,在四(三苯基膦)钯作催化剂下反应得到主配体2-苯基喹啉(pq),之后pq与水合三氯化铱在乙二醇单乙醚溶剂中反应得到铱的氯桥二聚体(pq)_2Ir(μ-Cl_2)Ir(pq)_2,然后在碱性条件下和乙酰丙酮反应合成出高效磷光红光...以2-氯喹啉和苯硼酸为原料,在四(三苯基膦)钯作催化剂下反应得到主配体2-苯基喹啉(pq),之后pq与水合三氯化铱在乙二醇单乙醚溶剂中反应得到铱的氯桥二聚体(pq)_2Ir(μ-Cl_2)Ir(pq)_2,然后在碱性条件下和乙酰丙酮反应合成出高效磷光红光材料二(2-苯基喹啉-C2,N')(乙酰丙酮)合铱(Ⅲ)Ir(pq)_2(acac)。通过元素分析、红外光谱、核磁共振谱(~1 H NMR、^(13)C NMR)、质谱和单晶X射线衍射等表征手段确定了分子结构,利用紫外-可见吸收光谱和光致发光光谱对其光物理性能进行了测试。结果表明,Ir(pq)_2(acac)为电中性八面体配合物,Ir—O键的平均长度为0.21741(18)nm,而Ir—C键的平均长度0.1983(3)nm,Ir—N键的平均长度为0.2079(2)nm,在600nm处出现了较强的红光发射,其合成产率>95%,该方法适于Ir(pq)_2(acac)的小批量制备。展开更多
文摘近年来,许多实际应用不仅需要支持空间连接查询而且需要具备关键词搜索功能,以帮助用户查找那些既满足空间连接条件又包含指定关键词的空间对象组合。正是在这种需求的驱动之下,定义了一种具备关键词搜索功能的空间连接查询(Spatial Join with Keyword Search,缩写SJKS),并提出了一种基于IR2-Tree的SJKS查询处理算法(IR2-TreeSJKS算法),旨在实现关键词搜索与空间连接查询的高效结合。实验表明,本算法可有效支持具有关键词搜索功能的空间连接查询处理。
基金supported by the National Natural Science Foundation of China(No.22403012 to Chunyang Wang,Wenzhe Zhou,and Xin-Xing Zhang,Nos.22241304 and 22225303 to Kaijun Yuan)the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB0970000 and XDB0970200).
文摘Histidine(His),as the most chemically active and versatile member among the 20 natural amino acids,plays a key role in the coordination of copper(Ⅱ)(Cu(Ⅱ))in biological systems.Cu(II)-His species are ubiquitous in metalloenzymes and proteins associated with various neurodegenerative diseases,where they regulate catalytic activity and mediate intracellular copper transport.While the steric influence of His is known to dictate donor group selection in Cu(Ⅱ)coordination,the extent of these constraints on peptide complexes remains unclear.In this study,we employed a multi-spectroscopic approach(FTIR,2D IR,UV-Vis,EPR,and NMR)to systematically investigate pH-dependent Cu(Ⅱ)coordination in three tripeptides.Our results demonstrate that Cu(Ⅱ)coordination geometries are cooperatively determined by both the protonation state of the N-terminus and the steric constraints imposed by the His residue.
文摘Engineering the morphology of the support is effective in tuning the redox properties of active metals for efficient catalytic methane combustion via tailoring the metal-support interaction.Herein,uniform Ir nanoparticles supported on anatase TiO_(2)with different morphologies predominantly exposing{100},{101},and{001}planes were synthesized and tested for methane combustion.The CH_(4) catalytic activity shows a remarkable TiO_(2)-facet-dependent effect and follows the order of Ir/TiO_(2)-{100}>Ir/TiO_(2)-{101}>>Ir/TiO_(2)-{001}.Detailed characterizations and DFT calculations reveal that compared with Ir-TiO_(2)-{101}and Ir-TiO_(2)-{001}interfaces,the superior Ir-TiO_(2)-{100}interface facilitates the generation of electron-rich Ir species through more profound charge transfer from TiO_(2)-{100}to Ir atoms.The electron-rich Ir structure,featuring abundant defect oxygen vacancies,significantly enhances the redox properties of active Ir species and reduces the activation energy for breaking the initial C-H bond in CH_(4),resulting in the superior catalytic activity for methane combustion.These findings deepen fundamental insights into the TiO_(2)-facet-dependent reactivity of different Ir/TiO_(2)nanomaterials in methane oxidation and pave the way for designing efficient Ir-based methane oxidation catalysts.
文摘目的:探讨针刺对2型糖尿病(T2DM)大鼠肝组织胰岛素受体底物1和2基因(IRS1和2mRNA)表达的影响。方法:给食源性肥胖大鼠腹腔注射小剂量链脲佐菌素(STZ)(25mg/kg)造模成T2DM大鼠,随机分为针刺组、优降糖组和模型组,处理4周后,用快速血糖仪检测空腹血糖(FBS)、用放免法检测空腹胰岛素(FINS)、用实时定量荧光PCR(real-tim e RT PCR)法检测肝组织IRS1和2mRNA表达,并与正常组大鼠进行对照。结果:针刺组和优降糖组FBS和FINS比模型组显著降低(P<0.05);模型组IRS1mRNA相对含量是正常组的25%,针刺组为正常组的2.83倍,优降糖组为正常组的1.23倍。模型组IRS2mRNA相对含量为正常组的2.19倍,针刺组IRS2mRNA相对含量为正常组的4.84%,优降糖组IRS2mRNA相对含量为正常组的4.59倍。结论:肝组织IRS1和2mRNA表达异常可能是T2DM的发病机制之一,针刺和优降糖均可上调T2DM大鼠肝组织IRS1mRNA的表达,针刺对T2DM大鼠肝组织IRS1 mRNA表达的上调作用优于优降糖;针刺具有显著抑制T2DM大鼠肝组织IRS2mRNA表达的作用,而优降糖无此作用。
文摘以2-氯喹啉和苯硼酸为原料,在四(三苯基膦)钯作催化剂下反应得到主配体2-苯基喹啉(pq),之后pq与水合三氯化铱在乙二醇单乙醚溶剂中反应得到铱的氯桥二聚体(pq)_2Ir(μ-Cl_2)Ir(pq)_2,然后在碱性条件下和乙酰丙酮反应合成出高效磷光红光材料二(2-苯基喹啉-C2,N')(乙酰丙酮)合铱(Ⅲ)Ir(pq)_2(acac)。通过元素分析、红外光谱、核磁共振谱(~1 H NMR、^(13)C NMR)、质谱和单晶X射线衍射等表征手段确定了分子结构,利用紫外-可见吸收光谱和光致发光光谱对其光物理性能进行了测试。结果表明,Ir(pq)_2(acac)为电中性八面体配合物,Ir—O键的平均长度为0.21741(18)nm,而Ir—C键的平均长度0.1983(3)nm,Ir—N键的平均长度为0.2079(2)nm,在600nm处出现了较强的红光发射,其合成产率>95%,该方法适于Ir(pq)_2(acac)的小批量制备。
