Combined with the existing stochastic lightning parameterization scheme, a classic tripole charge structure in thunderstorms is assumed in the paper, and then 2-dimensional fine-resolution lighting discharge simulatio...Combined with the existing stochastic lightning parameterization scheme, a classic tripole charge structure in thunderstorms is assumed in the paper, and then 2-dimensional fine-resolution lighting discharge simulations are performed to quantitatively investigate the effect of lower positive charge(LPC) on different types of lightning. The results show:(1) The LPC plays a key role in generating negative cloud-to-ground(CG) flashes and inverted intra-cloud(IC) lightning, and with the increase of charge density or distribution range of LPC region, lightning type changes from positive polarity IC lightning to negative CG flashes and then to inverted IC lightning.(2) Relative to distribution range of charge regions, the magnitude of charge density of the LPC region plays a dominant role in lightning type. Only when the maximal charge density value of LPC region is within a certain range, can negative CG flashes occur, and the occurrence probability is relatively fixed.(3) In this range, the charge density and distribution range of LPC region jointly determine the occurrence of negative CG flashes, which has a linear boundary with the trigger condition of IC lightning.(4) The common effect of charge density and distribution range of the LPC region is to change the distribution of positive potential well of bottom part of thunderstorms, and inverted IC lightning occurs when the initial reference potential is close to 0 MV, and negative CG flashes occur when the initial reference potential is far less than 0 MV.展开更多
Photodynamic therapy(PDT)has emerged as a significant cancer therapy option.Currently,cation-based organic small molecule aggregation-induced emission(AIE)photosensitizers(PSs)attract the wide atten-tion of many scien...Photodynamic therapy(PDT)has emerged as a significant cancer therapy option.Currently,cation-based organic small molecule aggregation-induced emission(AIE)photosensitizers(PSs)attract the wide atten-tion of many scientists,due to improved reactive oxygen species(ROS)production after cationization.However,such PSs tend to localize only the mitochondria,limiting the death way of tumor cells(usu-ally apoptosis)during PDT process,which may affect the therapeutic effect under some circumstances.Herein,we designed a novel water-soluble three positive charge PS,TPAN-18F,which could be distributed uniformly in cell cytoplasm and had distribution in different sub-organelles(mitochondria,endoplasmic reticulum,lysosome).The experimental results showed that TPAN-18F-based PDT process can not only disrupt mitochondrial functions(reducing ATP production and destroying mitochondrial membrane po-tential),but also elevate the intracellular lipid peroxides(LPOs)level,which evoke the non-apoptotic death manner of tumor cells.Further,in vivo studies showed that TPAN-18F-based PDT could effectively inhibit tumor growth.Accordingly,we believe that the construction of TPAN-18F is suggestive for tumor non-apoptotic therapy.展开更多
Cationic gold nanoparticles(cAuNPs)have been regarded as promising candidates for antibacterial applications due to their high surface charge density,favorable biocompatibility,and controllable surface chemistry.Never...Cationic gold nanoparticles(cAuNPs)have been regarded as promising candidates for antibacterial applications due to their high surface charge density,favorable biocompatibility,and controllable surface chemistry.Nevertheless,the complicated fabrication process and unclear antibacterial mechanism have greatly hindered the further biomedical application of cAuNPs.Herein,we have developed a simple and controllable strategy for synthesizing cAuNPs with tailored size and antibacterial behavior by kinetically modulating the reaction process.Specifically,a functional ligand,(11-mercaptoundecyl)-N,N,Ntrimethylammonium bromide(MUTAB),was chosen to chemically manipulate the positive surface charge of cAuNPs via a one-step strategy.The size of cAuNPs could be flexibly adjusted from 1.1 to 14.8 nm by simply elevating the stirring speed of the reaction from 0 to 1500 rpm.Further studies revealed that the antibacterial effect of cAuNPs was strongly correlated with the particle size.MUTAB-protected ultrasmall gold nanoclusters(MUTAB-AuNCs)were able to eradicate E.coli at a concentration as low as 1.25μg mL^(-1),while the minimum inhibitory concentration of MUTAB-AuNPs with a large size for E.coli was 5μg mL^(-1).Mechanistic investigation revealed that MUTAB-AuNPs were able to damage the bacterial membrane and stimulate the production of reactive oxygen species more effectively than MUTAB-AuNCs.Conversely,MUTAB-AuNCs were more active in inducing membrane depolarization in contrast to MUTAB-AuNPs,suggesting the unique size-dependent antibacterial manner of cAuNPs.This study presents a new strategy for the controlled preparation of cAuNPs with distinct sizes and antibacterial behavior,laying a valuable foundation for developing efficient cationic NP-based bactericidal agents.展开更多
A new lightning locating technology, called Lightning Mapping Array （LMA）, has been developed. The system takes advantage of GPS technology to measure the times of arrival （TOA） of lightning impulsive very high fr...A new lightning locating technology, called Lightning Mapping Array （LMA）, has been developed. The system takes advantage of GPS technology to measure the times of arrival （TOA） of lightning impulsive very high frequency （VHF） radiation events at each remote location. The spatiotemporal development processes of lightning are described in three-dimension by measurement of the system with high time resolution （50 ns） and space precision （50-100 m）. The charge structures in thunderstorm and their relationship with lightning discharge processes are revealed. The temporal and spatial characteristics of preliminary breakdown process involved in negative cloud-to-ground （CG） lightning discharges are analyzed based on the data of lightning VHF radiation events. The effect of positive charge region in lower part of thunderstorm on the occurrence of negative CG lightning discharge is discussed. The results indicate that the preliminary breakdown process with longer duration in negative CG lightning discharges is an intracloud discharge process. It occurs between negative and positive charge regions located in middle and lower parts of thunderstorm respectively. It initiates from the negative charge region and propagates downward. After propagating into the positive charge region, the lightning channel develops horizontally. The characteristics of the preliminary breakdown process are consistent with that of intracloud lightning discharges. The stepped leaders are initiated by the K type breakdown which occurs in the last stage of the preliminary breakdown process and develops downward through the positive charge region. The existence of positive charge region in lower part of thunderstorm results in the occurrence of preliminary breakdown process with longer duration before the return stroke of negative CG lightning discharges.展开更多
研究了基于DOE(Design of experiments,实验设计)统计理论量化正电荷纳滤膜的配方成分和界面聚合过程工艺变量因子的交互效应对所制备纳滤膜的氯化镁截留率、硫酸钠截留率和纯水通量3个响应变量的单因素以及交互影响。结果表明,综合单...研究了基于DOE(Design of experiments,实验设计)统计理论量化正电荷纳滤膜的配方成分和界面聚合过程工艺变量因子的交互效应对所制备纳滤膜的氯化镁截留率、硫酸钠截留率和纯水通量3个响应变量的单因素以及交互影响。结果表明,综合单一因素以及交互影响,水相单体N,N'-双(3-氨丙基)甲胺和吸酸剂NaOH含量是膜综合性能影响的主要因素,两者含量越高,油相均苯三甲酰氯含量和温度、烘箱温度越低,所制备膜的综合性能越优。利用DOE拟合的回归方程计算所得优化条件,并设置重复实验证实,所制备纳滤膜平均氯化镁,硫酸钠截留率分别为94.1%、14.2%,平均水通量47.9 L(m^2·h),可作为高效分离正电荷纳滤膜,应用于1价和2价阳离子分离浓缩资源化领域。展开更多
Bioaerosol charge information is of vital importance for their electrostatic collection. Here, electrostatic means and molecular tools were applied to studying bioaerosol charge dynamics. Positively or negatively char...Bioaerosol charge information is of vital importance for their electrostatic collection. Here, electrostatic means and molecular tools were applied to studying bioaerosol charge dynamics. Positively or negatively charged bioaerosols were collected using an electrostatic sampler operated with a field strength of 1.1 kV cm 1 at a flow rate of 3 L min 1 for 40 min. Those with fewer or no charges bypassing the sampler were also collected using a filter at the downstream of the electrostatic sampler in one environment. The experiments were independently conducted three times in three different environments. The collected bacterial aerosols were cultured directly on agar plates at 26°C, and the colony forming units (CFU) were manually counted. In addition, the CFUs were washed off from the agar plates, and further subjected to polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) for culturable diversity analysis. The results revealed remarkable differences in positively and negatively charged culturable bacterial aerosol concentration and diversity among the studied environments. In the office environment, negatively charged culturable bacterial aerosols appeared to dominate (P = 0.0489), while in outdoor and hotel environments both polarities had similar concentration levels (P = 0.078, P = 0.88, respectively). DGGE patterns for positively charged culturable bacterial aerosols were shown strikingly different from those of negatively charged regardless of the sampling environments. In addition, for each of the environments positively charged culturable bacterial aerosols collected were found to have more band pattern similarity with those positively charged for respective regions of agar plates than those negatively charged, and vice versa. The information developed here is useful for developing efficient electrostatic sampling protocols for bioaerosols.展开更多
基金supported by the National Basic Research Program of China(Grant No.2014CB441403)the National Natural Science Foundation of China(Grant No.41175003)Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Combined with the existing stochastic lightning parameterization scheme, a classic tripole charge structure in thunderstorms is assumed in the paper, and then 2-dimensional fine-resolution lighting discharge simulations are performed to quantitatively investigate the effect of lower positive charge(LPC) on different types of lightning. The results show:(1) The LPC plays a key role in generating negative cloud-to-ground(CG) flashes and inverted intra-cloud(IC) lightning, and with the increase of charge density or distribution range of LPC region, lightning type changes from positive polarity IC lightning to negative CG flashes and then to inverted IC lightning.(2) Relative to distribution range of charge regions, the magnitude of charge density of the LPC region plays a dominant role in lightning type. Only when the maximal charge density value of LPC region is within a certain range, can negative CG flashes occur, and the occurrence probability is relatively fixed.(3) In this range, the charge density and distribution range of LPC region jointly determine the occurrence of negative CG flashes, which has a linear boundary with the trigger condition of IC lightning.(4) The common effect of charge density and distribution range of the LPC region is to change the distribution of positive potential well of bottom part of thunderstorms, and inverted IC lightning occurs when the initial reference potential is close to 0 MV, and negative CG flashes occur when the initial reference potential is far less than 0 MV.
基金supported by the National Science Foundation of China(No.21890744)the National Key R&D Program of China(No.2019YFA0210100).
文摘Photodynamic therapy(PDT)has emerged as a significant cancer therapy option.Currently,cation-based organic small molecule aggregation-induced emission(AIE)photosensitizers(PSs)attract the wide atten-tion of many scientists,due to improved reactive oxygen species(ROS)production after cationization.However,such PSs tend to localize only the mitochondria,limiting the death way of tumor cells(usu-ally apoptosis)during PDT process,which may affect the therapeutic effect under some circumstances.Herein,we designed a novel water-soluble three positive charge PS,TPAN-18F,which could be distributed uniformly in cell cytoplasm and had distribution in different sub-organelles(mitochondria,endoplasmic reticulum,lysosome).The experimental results showed that TPAN-18F-based PDT process can not only disrupt mitochondrial functions(reducing ATP production and destroying mitochondrial membrane po-tential),but also elevate the intracellular lipid peroxides(LPOs)level,which evoke the non-apoptotic death manner of tumor cells.Further,in vivo studies showed that TPAN-18F-based PDT could effectively inhibit tumor growth.Accordingly,we believe that the construction of TPAN-18F is suggestive for tumor non-apoptotic therapy.
基金supported by the National Natural Science Foundation of China(No.52103320)the Fundamental Research Funds for the Central Universities(No.G2021KY05102)the Key Research and Development Projects of Shaanxi Province(No.2023-YBSF-163).
文摘Cationic gold nanoparticles(cAuNPs)have been regarded as promising candidates for antibacterial applications due to their high surface charge density,favorable biocompatibility,and controllable surface chemistry.Nevertheless,the complicated fabrication process and unclear antibacterial mechanism have greatly hindered the further biomedical application of cAuNPs.Herein,we have developed a simple and controllable strategy for synthesizing cAuNPs with tailored size and antibacterial behavior by kinetically modulating the reaction process.Specifically,a functional ligand,(11-mercaptoundecyl)-N,N,Ntrimethylammonium bromide(MUTAB),was chosen to chemically manipulate the positive surface charge of cAuNPs via a one-step strategy.The size of cAuNPs could be flexibly adjusted from 1.1 to 14.8 nm by simply elevating the stirring speed of the reaction from 0 to 1500 rpm.Further studies revealed that the antibacterial effect of cAuNPs was strongly correlated with the particle size.MUTAB-protected ultrasmall gold nanoclusters(MUTAB-AuNCs)were able to eradicate E.coli at a concentration as low as 1.25μg mL^(-1),while the minimum inhibitory concentration of MUTAB-AuNPs with a large size for E.coli was 5μg mL^(-1).Mechanistic investigation revealed that MUTAB-AuNPs were able to damage the bacterial membrane and stimulate the production of reactive oxygen species more effectively than MUTAB-AuNCs.Conversely,MUTAB-AuNCs were more active in inducing membrane depolarization in contrast to MUTAB-AuNPs,suggesting the unique size-dependent antibacterial manner of cAuNPs.This study presents a new strategy for the controlled preparation of cAuNPs with distinct sizes and antibacterial behavior,laying a valuable foundation for developing efficient cationic NP-based bactericidal agents.
基金Supported by the Natural Science Foundation of China under Grant No.40875003the National Basic Research Program of China under No.2004CB418306the Special Development Item of the Ministry of Science and Technology of China.
文摘A new lightning locating technology, called Lightning Mapping Array （LMA）, has been developed. The system takes advantage of GPS technology to measure the times of arrival （TOA） of lightning impulsive very high frequency （VHF） radiation events at each remote location. The spatiotemporal development processes of lightning are described in three-dimension by measurement of the system with high time resolution （50 ns） and space precision （50-100 m）. The charge structures in thunderstorm and their relationship with lightning discharge processes are revealed. The temporal and spatial characteristics of preliminary breakdown process involved in negative cloud-to-ground （CG） lightning discharges are analyzed based on the data of lightning VHF radiation events. The effect of positive charge region in lower part of thunderstorm on the occurrence of negative CG lightning discharge is discussed. The results indicate that the preliminary breakdown process with longer duration in negative CG lightning discharges is an intracloud discharge process. It occurs between negative and positive charge regions located in middle and lower parts of thunderstorm respectively. It initiates from the negative charge region and propagates downward. After propagating into the positive charge region, the lightning channel develops horizontally. The characteristics of the preliminary breakdown process are consistent with that of intracloud lightning discharges. The stepped leaders are initiated by the K type breakdown which occurs in the last stage of the preliminary breakdown process and develops downward through the positive charge region. The existence of positive charge region in lower part of thunderstorm results in the occurrence of preliminary breakdown process with longer duration before the return stroke of negative CG lightning discharges.
文摘研究了基于DOE(Design of experiments,实验设计)统计理论量化正电荷纳滤膜的配方成分和界面聚合过程工艺变量因子的交互效应对所制备纳滤膜的氯化镁截留率、硫酸钠截留率和纯水通量3个响应变量的单因素以及交互影响。结果表明,综合单一因素以及交互影响,水相单体N,N'-双(3-氨丙基)甲胺和吸酸剂NaOH含量是膜综合性能影响的主要因素,两者含量越高,油相均苯三甲酰氯含量和温度、烘箱温度越低,所制备膜的综合性能越优。利用DOE拟合的回归方程计算所得优化条件,并设置重复实验证实,所制备纳滤膜平均氯化镁,硫酸钠截留率分别为94.1%、14.2%,平均水通量47.9 L(m^2·h),可作为高效分离正电荷纳滤膜,应用于1价和2价阳离子分离浓缩资源化领域。
基金supported by the National Natural Science Foundation of China (21277007, 21077005 and 41121004)
文摘Bioaerosol charge information is of vital importance for their electrostatic collection. Here, electrostatic means and molecular tools were applied to studying bioaerosol charge dynamics. Positively or negatively charged bioaerosols were collected using an electrostatic sampler operated with a field strength of 1.1 kV cm 1 at a flow rate of 3 L min 1 for 40 min. Those with fewer or no charges bypassing the sampler were also collected using a filter at the downstream of the electrostatic sampler in one environment. The experiments were independently conducted three times in three different environments. The collected bacterial aerosols were cultured directly on agar plates at 26°C, and the colony forming units (CFU) were manually counted. In addition, the CFUs were washed off from the agar plates, and further subjected to polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) for culturable diversity analysis. The results revealed remarkable differences in positively and negatively charged culturable bacterial aerosol concentration and diversity among the studied environments. In the office environment, negatively charged culturable bacterial aerosols appeared to dominate (P = 0.0489), while in outdoor and hotel environments both polarities had similar concentration levels (P = 0.078, P = 0.88, respectively). DGGE patterns for positively charged culturable bacterial aerosols were shown strikingly different from those of negatively charged regardless of the sampling environments. In addition, for each of the environments positively charged culturable bacterial aerosols collected were found to have more band pattern similarity with those positively charged for respective regions of agar plates than those negatively charged, and vice versa. The information developed here is useful for developing efficient electrostatic sampling protocols for bioaerosols.
