Hydrothermal reactions of biphenyl-2,3,3A,5A-tetracarboxylic acid（H4bptc） with cobalt salt in the presence of 1,4-bis（2-pyridylmethyl）piperazin（bpmp） afforded one novel coordination polymer, namely, [Co（H2bptc...Hydrothermal reactions of biphenyl-2,3,3A,5A-tetracarboxylic acid（H4bptc） with cobalt salt in the presence of 1,4-bis（2-pyridylmethyl）piperazin（bpmp） afforded one novel coordination polymer, namely, [Co（H2bptc）（bpmp）0.5（H2O）]n（1）. Its structure was established by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra and TG analysis. Complex 1 crystallizes in monoclinic, space group P21/c with a = 11.4839（11）, b = 16.6690（16）, c = 11.5559（11） A, V = 2201.8（4） A3, Mr = 539.35, Dc = 1.627 g/cm^3, μ（MoK α） = 0.841 mm-1, F（000） = 1108, Z = 4, the final R = 0.0309 and w R = 0.0705 for 4090 observed reflections（I 2σ（I））. Complex 1 displays a one-dimensional（1D） chain bridged by bpmp. Two carboxylic groups of H4 bptc ligand adopt μ01-η1：η1 and μ1-η1：η coordination modes to bridge adjacent Co（Ⅱ） ions together with bpmp ligand to give alternately arranged left- and right-handed helical chains. In addition, variable-temperature magnetic susceptibility measurements indicate that complex 1 shows weak antiferromagnetic interactions between the adjacent Co（Ⅱ） ions.展开更多
A new terbium complex based on biphenyl-2,3,3’,5’-tetracarboxylic acid（H4bptc） has been synthesized, {[Tb（Hbptc）（H2O）4]×H2O}n（1）. Its structure was determined by single-crystal X-ray diffraction analysi...A new terbium complex based on biphenyl-2,3,3’,5’-tetracarboxylic acid（H4bptc） has been synthesized, {[Tb（Hbptc）（H2O）4]×H2O}n（1）. Its structure was determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra and TG analyses. Title complex crystallizes in monoclinic, space group P21/n with a = 14.090（2）, b = 8.0824（13）, c = 15.5591（17） ?, V = 1775.4（5） ?3, Mr = 576.22, Dc = 2.156 g/cm3, μ（Mo Kα） = 4.059 mm-1, F（000） = 1128, Z = 4, the final R = 0.027 and w R = 0.0726 for 3296 observed reflections（I > 2σ（I））. Complex 1 exhibits a 2 D layer structure, and such layers are further united together into a three-dimensional supramolecular structure through π···π interaction and intricate hydrogen bonding. The fluorescence excitation and emission spectroscopy of 1 showed that H4 bptc is a kind of highly efficient sensitizer for terbium（Ⅲ） ion. The title complex also displays efficient ligand sensitized luminescence in the visible region with long lifetime of 2.02 ms in the solid state.展开更多
自然语言视频定位(Natural Language Video Localization, NLVL)是一项新颖而富有挑战性的任务。该任务的目的是根据给定的查询文本从未修剪的视频中找到与这条查询文本语义最为相似的目标片段。与传统的时序动作定位任务不同,NLVL具有...自然语言视频定位(Natural Language Video Localization, NLVL)是一项新颖而富有挑战性的任务。该任务的目的是根据给定的查询文本从未修剪的视频中找到与这条查询文本语义最为相似的目标片段。与传统的时序动作定位任务不同,NLVL具有更强的灵活性,因为它不受预定义动作列表的限制;同时也更具挑战性,因为NLVL需要从视频和文本两种模态间对齐语义信息。此外,在对齐关系中获取最终的时间戳也是一个艰巨的任务。首先,描述了NLVL的流程;其次,根据是否有监督信息将NLVL算法分为监督方法和弱监督方法两大类并分析其优缺点;然后,总结了常用的数据集和评估指标,对现有的研究进行了总体性能的评估和分析;最后,讨论了技术难点及未来的研究趋势,为今后的工作提供参考。展开更多
基金supported by the National Natural Science Foundation of China(No.21273101 and 21302082)the Foundation of the Program for Backbone Teachers in Universities of Henan Province(No.2012GGJS158)
文摘Hydrothermal reactions of biphenyl-2,3,3A,5A-tetracarboxylic acid（H4bptc） with cobalt salt in the presence of 1,4-bis（2-pyridylmethyl）piperazin（bpmp） afforded one novel coordination polymer, namely, [Co（H2bptc）（bpmp）0.5（H2O）]n（1）. Its structure was established by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra and TG analysis. Complex 1 crystallizes in monoclinic, space group P21/c with a = 11.4839（11）, b = 16.6690（16）, c = 11.5559（11） A, V = 2201.8（4） A3, Mr = 539.35, Dc = 1.627 g/cm^3, μ（MoK α） = 0.841 mm-1, F（000） = 1108, Z = 4, the final R = 0.0309 and w R = 0.0705 for 4090 observed reflections（I 2σ（I））. Complex 1 displays a one-dimensional（1D） chain bridged by bpmp. Two carboxylic groups of H4 bptc ligand adopt μ01-η1：η1 and μ1-η1：η coordination modes to bridge adjacent Co（Ⅱ） ions together with bpmp ligand to give alternately arranged left- and right-handed helical chains. In addition, variable-temperature magnetic susceptibility measurements indicate that complex 1 shows weak antiferromagnetic interactions between the adjacent Co（Ⅱ） ions.
基金supported by the National Natural Science Foundation of China(No.21671114 and U1804131)Natural Science Foundation of Henan Province(No.182300410166,182102310909 and 182102310897)
文摘A new terbium complex based on biphenyl-2,3,3’,5’-tetracarboxylic acid（H4bptc） has been synthesized, {[Tb（Hbptc）（H2O）4]×H2O}n（1）. Its structure was determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra and TG analyses. Title complex crystallizes in monoclinic, space group P21/n with a = 14.090（2）, b = 8.0824（13）, c = 15.5591（17） ?, V = 1775.4（5） ?3, Mr = 576.22, Dc = 2.156 g/cm3, μ（Mo Kα） = 4.059 mm-1, F（000） = 1128, Z = 4, the final R = 0.027 and w R = 0.0726 for 3296 observed reflections（I > 2σ（I））. Complex 1 exhibits a 2 D layer structure, and such layers are further united together into a three-dimensional supramolecular structure through π···π interaction and intricate hydrogen bonding. The fluorescence excitation and emission spectroscopy of 1 showed that H4 bptc is a kind of highly efficient sensitizer for terbium（Ⅲ） ion. The title complex also displays efficient ligand sensitized luminescence in the visible region with long lifetime of 2.02 ms in the solid state.
文摘自然语言视频定位(Natural Language Video Localization, NLVL)是一项新颖而富有挑战性的任务。该任务的目的是根据给定的查询文本从未修剪的视频中找到与这条查询文本语义最为相似的目标片段。与传统的时序动作定位任务不同,NLVL具有更强的灵活性,因为它不受预定义动作列表的限制;同时也更具挑战性,因为NLVL需要从视频和文本两种模态间对齐语义信息。此外,在对齐关系中获取最终的时间戳也是一个艰巨的任务。首先,描述了NLVL的流程;其次,根据是否有监督信息将NLVL算法分为监督方法和弱监督方法两大类并分析其优缺点;然后,总结了常用的数据集和评估指标,对现有的研究进行了总体性能的评估和分析;最后,讨论了技术难点及未来的研究趋势,为今后的工作提供参考。
