Circulating Selenium and Cardiovascular or All-Cause Mortality in the General Population: a Meta-Analysis

Biological Trace Element Research - The association of circulating selenium level with mortality remains controversial. This meta-analysis investigated the association between elevated circulating...     

High-frequency stimulation induces axonal conduction block without generating initial action potentials

Journal of Computational Neuroscience - The purpose of this modeling study is to develop a novel method to block nerve conduction by high frequency biphasic stimulation (HFBS) without generating...     

Rare Earth Element Transfer from Soil to Navel Orange Pulp (Citrus sinensis Osbeck cv. Newhall) and the Effects on Internal Fruit Quality

The effects of soil rare earth element (REE) on navel orange quality and safety in rare earth ore areas have gained great attention. This study investigated the transfer characteristics of REE from soil to navel orange pulp (Citrus sinensis Osbeck cv. Newhall) and examined the effects of soil REE on internal fruit quality in Xinfeng County, Jiangxi province, China. Path analysis showed that soil REE, pH, cation exchange capacity (CEC), and Fe oxide (Fe_ox) significantly affected pulp REE concentrations. A Freundlich-type prediction model for pulp REE was established: log[REE_pulp] = -1.036 + 0.272 log[REE_soil] - 0.056 pH - 0.360 log[CEC] + 0.370 log[Fe_ox] (n = 114, R² = 0.60). From the prediction model, it was inferred that even when soil REE and Fe_ox were as high as 1038 mg kg^-1 and 96.4 g kg^-1, respectively, and pH and CEC were as low as 3.75 and 5.08 cmol kg^-1, respectively, pulp REE concentrations were much lower than the food limit standard. Additionally, soil REE levels were significantly correlated with selected fruit quality indicators, including titratable acidity (r = 0.52, P < 0.01), total soluble solids (r = 0.48, P < 0.01) and vitamin C (r = 0.56, P < 0.01). Generally, under routine methods of water and fertilization management, the cultivation of navel oranges in rare earth ore areas of south China with soil REE ranging from 38.6 to 546 mg kg^-1 had improved in internal fruit quality.     

人工湿地处理重金属Pb,Cd污水的机理探讨

1 引言 人工湿地系统是70年代提出,80年代得到迅速发展的一种污水处理新技术,具有投资少,处理效果好,运转费用低和能耗少等优点,已用于污水处理,我们对人工湿地处理污水技术进行了初步研究,结果表明,该技术对氮、磷、BOD、COD和重金属Pb、Cd等均有良     

水母消亡对海洋生态环境的影响

近年来全球水母出现频率呈增加趋势,水母暴发已成为一种海洋生态灾害,可使海洋生态系统正常的结构和功能失常,同时水母暴发后的消亡对海水生态环境有重要影响,因此,对海洋水母消亡的生态环境影响研究意义重大。系统总结水母消亡的观测及方法、水母沉降速率及影响因素,重点探讨了水母消亡对海水中生源要素、溶解氧、酸碱度及海洋生物群落的影响,并对水母生物量的增加与海洋系统的耦合关系进行了初步评估。水母消亡是持续性快速反应过程,消亡速度主要受沉降速率与腐烂速率影响,水母的平均沉降速率可达850—1500 m/d,腐烂系数为0.67—1.12 d-1;水母死亡后向水体释放DOC速率为0.36mg g-1d-1,DON、DOP释放速率分别为(7182±2934)μmol m-2h-1、(725±124)μmol m-2h-1,NH+4、PO3-4的释放速率分别为(2044±519)μmol m-2h-1、(287±47)μmol m-2h-1;消亡时水体酸化,p H降幅可达1.3;平均耗氧量可达65.5μmol kg-1h-1。水母消亡对生源要素循环及其生物地球化学过程产生影响,死亡水母既可被微型、小型食腐动物吞食,直接参与海洋生物食物链,又可为微生物提供溶解有机物质,影响浮游生物的聚集分布与生物量,还可使水体酸化并形成低氧区。因此,水母消亡对海水环境的影响巨大,值得深入探讨。     

An infrared spectroscopic based method to measure membrane permeance in liposomes

A new method for studying membrane permeance in liposomes is described. The method uses liposomes fabricated to contain IR probe molecules with CN moieties in combination with attenuated total reflection—Fourier transform infrared (ATR-FTIR) spectroscopy. The liposomes are adsorbed on a TiO₂ coated ATR crystal and remain intact to flowing aqueous solutions. A change in permeance is determined by monitoring the time dependent decrease in the intensity of a band due to CN groups. It is shown that the transport of the probe molecule depends on the size of the probe molecule and the structure of the liposome membrane. A much clearer molecular understanding of membrane permeance is obtained when the information derived from transport of the probe molecules is combined with the membrane packing arrangement determined from the infrared bands due to the lipids.