A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The ...A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.展开更多
Shenqi Fuzheng injection is extracted from the Chinese herbs Radix Astragali and Radix Codonopsis. The aim of the present study was to investigate the neuroprotective effects of Shenqi Fuzheng injection in cerebral is...Shenqi Fuzheng injection is extracted from the Chinese herbs Radix Astragali and Radix Codonopsis. The aim of the present study was to investigate the neuroprotective effects of Shenqi Fuzheng injection in cerebral ischemia and reperfusion. Aged rats（20–22 months） were divided into three groups： sham, model, and treatment. Shenqi Fuzheng injection or saline（40 m L/kg） was injected into the tail vein daily for 1 week, after which a cerebral ischemia/reperfusion injury model was established. Compared with model rats that received saline, rats in the treatment group had smaller infarct volumes, lower brain water and malondialdehyde content, lower brain Ca2＋ levels, lower activities of serum lactate dehydrogenase and creatine kinase, and higher superoxide dismutase activity. In addition, the treatment group showed less damage to the brain tissue ultrastructure and better neurological function. Our findings indicate that Shenqi Fuzheng injection exerts neuroprotective effects in aged rats with cerebral ischemia/reperfusion injury, and that the underlying mechanism relies on oxygen free radical scavenging and inhibition of brain Ca2＋ accumulation.展开更多
The injection of a self-avoiding flexible polymer into a spherical cavity under a driving force is studied by using Langevin dynamics simulation.For given polymer length(N)and driving force(f),the polymer can be compl...The injection of a self-avoiding flexible polymer into a spherical cavity under a driving force is studied by using Langevin dynamics simulation.For given polymer length(N)and driving force(f),the polymer can be completely injected into the cavity only when the radius of the cavity is larger than a transition radius(ReC).The dependence of ReC on N and f can be described by a scaling relation ReC∝N ^(1/3) f−δ.The value ofδchanges from 4/15 in the small f region to 1/6 in the moderate f region due to the screening of the excluded-volume interaction between monomers.We find the complete injection time(τ)decreases monotonously with increasing the cavity radius or decreasing the polymer length.The simulation results are in good agreement with the theoretical predictions from the free energy analysis and a simple kinetic model.展开更多
Free convection flow between two vertical parallel plates with transverse sinusoidal injection of the fluid at the stationary plate and its corresponding removal by constant suction through the plate in uniform motion...Free convection flow between two vertical parallel plates with transverse sinusoidal injection of the fluid at the stationary plate and its corresponding removal by constant suction through the plate in uniform motion has been analyzed. Due to this type of injection velocity, the flow becomes three-dimensional. Analytical expressions for the velocity, temperature, skin friction and rate of heat transfer were obtained. The important characteristics of the problem, namely the skin friction and the rate of heat transfer are discussed in detail with the help of graphs.展开更多
Recent interest by physicists in social networks and disease transmission factors has prompted debate over the topology of degree distributions in sexual networks. Social network researchers have been critical of “sc...Recent interest by physicists in social networks and disease transmission factors has prompted debate over the topology of degree distributions in sexual networks. Social network researchers have been critical of “scale-free” Barabasi-Albert approaches, and largely rejected the preferential attachment, “rich-get-richer” assumptions that underlie that model. Instead, research on sexual networks has pointed to the importance of homophily and local sexual norms in dictating degree distributions, and thus disease transmission thresholds. Injecting Drug User (IDU) network topologies may differ from the emerging models of sexual networks, however. Degree distribution analysis of a Brooklyn, NY, IDU network indicates a different topology than the spanning tree configurations discussed for sexual networks, instead featuring comparatively short cycles and high concurrency. Our findings suggest that IDU networks do in some ways conform to a “scale-free” topology, and thus may represent “reservoirs” of potential infection despite seemingly low transmission thresholds.展开更多
目的:研究并建立气相色谱(GC)法测定庚酸炔诺酮中游离庚酸的含量。方法:采用HP-FFAP(0.53 mm×30 m, 1.00μm)毛细管色谱柱(固定相为硝基对苯二甲酸改性的聚乙二醇),以氮气为载气,FID检测器,采用程序升温,分流直接进样,标准曲线法...目的:研究并建立气相色谱(GC)法测定庚酸炔诺酮中游离庚酸的含量。方法:采用HP-FFAP(0.53 mm×30 m, 1.00μm)毛细管色谱柱(固定相为硝基对苯二甲酸改性的聚乙二醇),以氮气为载气,FID检测器,采用程序升温,分流直接进样,标准曲线法计算游离庚酸的含量。结果:游离庚酸的检测限为0.49 ng,定量限为2.45 ng,线性范围9.84~118.04μg·mL^(-1)(r=0.999 9),平均回收率(n=3)为98.8%~101.0%(RSD=1.24%),样品中游离庚酸含量分别为0.69%(批号:ALT803730)、0.54%(批号:80703)。结论:本法简单、快速、灵敏、准确,可对庚酸炔诺酮中游离庚酸进行质量控制。展开更多
基金This study was supported by the National Natural Science Foundation of China
文摘A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.
基金supported by a grant from Key Technology Research and Development Program of Shaanxi Province of China,No.2003K10-G86the National Natural Science Foundation of China,No.30070731
文摘Shenqi Fuzheng injection is extracted from the Chinese herbs Radix Astragali and Radix Codonopsis. The aim of the present study was to investigate the neuroprotective effects of Shenqi Fuzheng injection in cerebral ischemia and reperfusion. Aged rats（20–22 months） were divided into three groups： sham, model, and treatment. Shenqi Fuzheng injection or saline（40 m L/kg） was injected into the tail vein daily for 1 week, after which a cerebral ischemia/reperfusion injury model was established. Compared with model rats that received saline, rats in the treatment group had smaller infarct volumes, lower brain water and malondialdehyde content, lower brain Ca2＋ levels, lower activities of serum lactate dehydrogenase and creatine kinase, and higher superoxide dismutase activity. In addition, the treatment group showed less damage to the brain tissue ultrastructure and better neurological function. Our findings indicate that Shenqi Fuzheng injection exerts neuroprotective effects in aged rats with cerebral ischemia/reperfusion injury, and that the underlying mechanism relies on oxygen free radical scavenging and inhibition of brain Ca2＋ accumulation.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY20A040004)the National Natural Science Foundation of China(Grant Nos.11604232 and 11974305)。
文摘The injection of a self-avoiding flexible polymer into a spherical cavity under a driving force is studied by using Langevin dynamics simulation.For given polymer length(N)and driving force(f),the polymer can be completely injected into the cavity only when the radius of the cavity is larger than a transition radius(ReC).The dependence of ReC on N and f can be described by a scaling relation ReC∝N ^(1/3) f−δ.The value ofδchanges from 4/15 in the small f region to 1/6 in the moderate f region due to the screening of the excluded-volume interaction between monomers.We find the complete injection time(τ)decreases monotonously with increasing the cavity radius or decreasing the polymer length.The simulation results are in good agreement with the theoretical predictions from the free energy analysis and a simple kinetic model.
文摘Free convection flow between two vertical parallel plates with transverse sinusoidal injection of the fluid at the stationary plate and its corresponding removal by constant suction through the plate in uniform motion has been analyzed. Due to this type of injection velocity, the flow becomes three-dimensional. Analytical expressions for the velocity, temperature, skin friction and rate of heat transfer were obtained. The important characteristics of the problem, namely the skin friction and the rate of heat transfer are discussed in detail with the help of graphs.
文摘Recent interest by physicists in social networks and disease transmission factors has prompted debate over the topology of degree distributions in sexual networks. Social network researchers have been critical of “scale-free” Barabasi-Albert approaches, and largely rejected the preferential attachment, “rich-get-richer” assumptions that underlie that model. Instead, research on sexual networks has pointed to the importance of homophily and local sexual norms in dictating degree distributions, and thus disease transmission thresholds. Injecting Drug User (IDU) network topologies may differ from the emerging models of sexual networks, however. Degree distribution analysis of a Brooklyn, NY, IDU network indicates a different topology than the spanning tree configurations discussed for sexual networks, instead featuring comparatively short cycles and high concurrency. Our findings suggest that IDU networks do in some ways conform to a “scale-free” topology, and thus may represent “reservoirs” of potential infection despite seemingly low transmission thresholds.
