Poly（silanylenediethynylanthracene） （PSDEA） exhibits a hole-transporting ability experimentally. In order to simulate the property of PSDEA, a series of silanylenediethynylanthracene oligomers were designed. The s...Poly（silanylenediethynylanthracene） （PSDEA） exhibits a hole-transporting ability experimentally. In order to simulate the property of PSDEA, a series of silanylenediethynylanthracene oligomers were designed. The structures of these oligomers were optimized by using density function theory at B3LYP/6-31G（d） level. The energy gaps of the oligomers decrease with the increase in the chain length. The energy gaps of the oligomers also decrease in the presence of the electron-withdrawing group on the anthracene ring. The 13C chemical shifts and nucleus independent chemical shifts （NICS） at the anthracene ring center in the oligomers were calculated at B3LYP/6-31G level. The chemical shifts of the carbon atoms connected with the nitryl group changed upfield, compared with those of the carbon atoms without the nitryl group. The aromaticity at the anthracene ring center decreases in the presence of the electron-withdrawing group, whereas increases with the increase in the number of the silanylene units. The most sensitive location for calculating the NICS values is 0.1 nm above the anthracene plane.展开更多
A series of fluorescent chemosensors 1-3 were synthesized to detect transition metal ions. At the room temperature, fluorescence intensities of these chemosensors in acetonitrile without transition metal ions were fou...A series of fluorescent chemosensors 1-3 were synthesized to detect transition metal ions. At the room temperature, fluorescence intensities of these chemosensors in acetonitrile without transition metal ions were found to be very weak, due to the process of the efficient intramolecular photoinduced electron transfer （PET）. However, after addition of the transition metal ions, the chemoscnsor 1-3 exhibits obvious fluorescence enhancement. Moreover, the intensity of the fluorescence emission of chemosensors increases significantly in the presence of Zn^2＋ and Cd^2＋. The fluorescent chemosensors with different polyamine as receptors show diverse affinity abilities to the transition metal ions and signal the receptor-metal ion interaction by the intensity change of fluorescence emission.展开更多
Potassium transporters play crucial roles in K^＋ uptake and translocation in plants. However, so far little is known about the regulatory mechanism of potassium transporters. Here, we show that a Shaker-like potassiu...Potassium transporters play crucial roles in K^＋ uptake and translocation in plants. However, so far little is known about the regulatory mechanism of potassium transporters. Here, we show that a Shaker-like potassium channel AtKC1, encoded by the AtLKT1 gene cloned from the Arabidopsis thaliana low-K^＋ （LK）-tolerant mutant Atlktl, significantly regulates AKTl-mediated K^＋ uptake under LK conditions. Under LK conditions, the Atkcl mutants maintained their root growth, whereas wild-type plants stopped their root growth. Lesion of AtKC1 significantly enhanced the tolerance of the Atkcl mutants to LK stress and markedly increased K^＋ uptake and K^＋ accumulation in the Atkclmutant roots under LK conditions. Electrophysiological results showed that AtKC1 inhibited the AKT1-mediated inward K^＋ currents and negatively shifted the voltage dependence of AKT1 channels. These results demonstrate that the ‘silent＇ K^＋ channel α-subunit AtKC1 negatively regulates the AKTl-mediated K^＋ uptake in Arabidopsis roots and consequently alters the ratio of root-to-shoot under LK stress conditions.展开更多
This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable cond...This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable conductor temperature as well as load current determination principles are proposed. On one hand, the principles are based on mechanical limitations; on the other hand, they are based on thermal limitations. The simulation tasks were based on specific data information of three existing overhead lines of Latvian power system as well as the planned 330 kV overhead line. Moreover, the special thermovision device was used for precious determination of conductor temperature of the existing transmission lines. The simulation results of the obtained data are reviewed in the paper.展开更多
间充质干细胞具有高度增殖、自我更新和多向分化的潜能。大电导钙离子激活的钾通道M亚族α亚基(potassium large conductance calcium-activated channel,subfamily M,alpha member 1,KCNMA1)介导细胞内K+的外流,使细胞膜超极化,降低细...间充质干细胞具有高度增殖、自我更新和多向分化的潜能。大电导钙离子激活的钾通道M亚族α亚基(potassium large conductance calcium-activated channel,subfamily M,alpha member 1,KCNMA1)介导细胞内K+的外流,使细胞膜超极化,降低细胞的兴奋性。该研究通过制备KCNMA1重组慢病毒载体和空白对照慢病毒载体,将其转染至间充质干细胞内,测定转染复数值(MOI),并通过RT-PCR和Western blot比较转染前后KCNMA1的表达变化情况,检测转染前后细胞微环境中电解质浓度变化。结果成功包装了KCNMA1慢病毒载体和空白病毒载体并转染入干细胞内;含有目的基因的慢病毒转染间充质干细胞后,RT-PCR和Western blot提示KCNMA1过表达,且细胞微环境中K+浓度升高。证实成功地将含KCNMA1的慢病毒载体转染进入大鼠间充质干细胞内,并在细胞内过表达且发挥功能,为体内研究KCNMA1结合干细胞治疗相关疾病奠定了基础。展开更多
文摘Poly（silanylenediethynylanthracene） （PSDEA） exhibits a hole-transporting ability experimentally. In order to simulate the property of PSDEA, a series of silanylenediethynylanthracene oligomers were designed. The structures of these oligomers were optimized by using density function theory at B3LYP/6-31G（d） level. The energy gaps of the oligomers decrease with the increase in the chain length. The energy gaps of the oligomers also decrease in the presence of the electron-withdrawing group on the anthracene ring. The 13C chemical shifts and nucleus independent chemical shifts （NICS） at the anthracene ring center in the oligomers were calculated at B3LYP/6-31G level. The chemical shifts of the carbon atoms connected with the nitryl group changed upfield, compared with those of the carbon atoms without the nitryl group. The aromaticity at the anthracene ring center decreases in the presence of the electron-withdrawing group, whereas increases with the increase in the number of the silanylene units. The most sensitive location for calculating the NICS values is 0.1 nm above the anthracene plane.
基金supported by the National Natural Science Foundation of China(No.20332020,No.20472079).
文摘A series of fluorescent chemosensors 1-3 were synthesized to detect transition metal ions. At the room temperature, fluorescence intensities of these chemosensors in acetonitrile without transition metal ions were found to be very weak, due to the process of the efficient intramolecular photoinduced electron transfer （PET）. However, after addition of the transition metal ions, the chemoscnsor 1-3 exhibits obvious fluorescence enhancement. Moreover, the intensity of the fluorescence emission of chemosensors increases significantly in the presence of Zn^2＋ and Cd^2＋. The fluorescent chemosensors with different polyamine as receptors show diverse affinity abilities to the transition metal ions and signal the receptor-metal ion interaction by the intensity change of fluorescence emission.
基金Acknowledgments We thank Dr Emily Liman （University of Southern California, USA） for providing the pGEMHE vector for the Xenopus oocyte experiments. We also thank Dr Richer Gaber （Northwestern Uni- versity, USA） for providing the yeast mutant strain with K＋ transport deficiency. We are grateful to Dr Rainer Hedrich （University of Wurzburg, Germany） for critical discussion. This work was supported by the National Natural Science Foundation of China （grant no. 30830013 to WHW）, the Beijing Municipal Education Commission （grant no. YB20081001901 to WHW） and the Program of Introducing Talents of Discipline to Universities （grant no. B06003 to WHW）.
文摘Potassium transporters play crucial roles in K^＋ uptake and translocation in plants. However, so far little is known about the regulatory mechanism of potassium transporters. Here, we show that a Shaker-like potassium channel AtKC1, encoded by the AtLKT1 gene cloned from the Arabidopsis thaliana low-K^＋ （LK）-tolerant mutant Atlktl, significantly regulates AKTl-mediated K^＋ uptake under LK conditions. Under LK conditions, the Atkcl mutants maintained their root growth, whereas wild-type plants stopped their root growth. Lesion of AtKC1 significantly enhanced the tolerance of the Atkcl mutants to LK stress and markedly increased K^＋ uptake and K^＋ accumulation in the Atkclmutant roots under LK conditions. Electrophysiological results showed that AtKC1 inhibited the AKT1-mediated inward K^＋ currents and negatively shifted the voltage dependence of AKT1 channels. These results demonstrate that the ‘silent＇ K^＋ channel α-subunit AtKC1 negatively regulates the AKTl-mediated K^＋ uptake in Arabidopsis roots and consequently alters the ratio of root-to-shoot under LK stress conditions.
文摘This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable conductor temperature as well as load current determination principles are proposed. On one hand, the principles are based on mechanical limitations; on the other hand, they are based on thermal limitations. The simulation tasks were based on specific data information of three existing overhead lines of Latvian power system as well as the planned 330 kV overhead line. Moreover, the special thermovision device was used for precious determination of conductor temperature of the existing transmission lines. The simulation results of the obtained data are reviewed in the paper.
文摘间充质干细胞具有高度增殖、自我更新和多向分化的潜能。大电导钙离子激活的钾通道M亚族α亚基(potassium large conductance calcium-activated channel,subfamily M,alpha member 1,KCNMA1)介导细胞内K+的外流,使细胞膜超极化,降低细胞的兴奋性。该研究通过制备KCNMA1重组慢病毒载体和空白对照慢病毒载体,将其转染至间充质干细胞内,测定转染复数值(MOI),并通过RT-PCR和Western blot比较转染前后KCNMA1的表达变化情况,检测转染前后细胞微环境中电解质浓度变化。结果成功包装了KCNMA1慢病毒载体和空白病毒载体并转染入干细胞内;含有目的基因的慢病毒转染间充质干细胞后,RT-PCR和Western blot提示KCNMA1过表达,且细胞微环境中K+浓度升高。证实成功地将含KCNMA1的慢病毒载体转染进入大鼠间充质干细胞内,并在细胞内过表达且发挥功能,为体内研究KCNMA1结合干细胞治疗相关疾病奠定了基础。
