Rapid extraction and high-performance liquid chromatographic determination of parthenolide in feverfew (Tanacetum parthenium).

A rapid and sensitive method for quantifying parthenolide in feverfew herb (Tanacetum parthenium) was developed that is significantly faster than those reported in the literature. The extraction system consisted of acetonitrile/water (90:10, v/v) in a bottle with stirring for 30 min. Both Soxhlet and bottle-stirring extractions were studied. Samples were analyzed using high-performance liquid chromatography with a Cosmosil C18-AR column (150 x 4.6 mm, 5 microm, 120 A). The mobile phase consisted of acetonitrile/water (55:45, v/v) with a flow rate of 1.5 mL/min and UV detection at 210 nm. Analysis time was 6 min, with a detection limit of 0.10 ng on column. The calibration curve was linear over a range of 0.160-850 microg/mL parthenolide with R(2) = 0.9999. Replicate tests indicated good reproducibility of the method with an RSD% = 0.88 (n = 10). Spike recovery of parthenolide was found to be 99.3% with an RSD% = 1.6 (n = 6).     

本溪冬半年降水相态的识别判据研究

利用本溪1981—2013年10月—次年4月降水资料,统计分析了近33年本溪冬半年不同降水相态的气候特征,得出本溪雨雪转换多发季节主要为3月和11月。利用2005—2013年10月—次年4月的探空资料和自动站数据,对近9年本溪冬半年不同相态降水过程的大气层结特征进行统计研究。结果表明：本溪冬半年出现雪时各层温度及地面温度均低于0℃;出现雨时0℃层高度在850~700 hPa之间;雨雪转换时0℃层高度在925 hPa附近,各层温度范围分别为：700 hPa的温度范围[-11℃,-7℃]、850 hPa的温度范围[-6.5℃,-1.5℃]、9250 hPa的温度范围[-3℃,1℃]、1000 hPa的温度范围[0℃,3℃],地面温度小于1000 hPa温度。本工作的结果除适用于本溪地区的相关预报业务以外,还可以对辽宁东部山区及吉林部分地区的降水相态预报提供较好的参考。     

西安市汛期降雨特征的多尺度分析及未来趋势预测

利用1951—2013年汛期降雨量（日）资料,采用线性回归、Mann-Kendall检验、小波分析和R/S分析等方法,对西安市汛期降雨特征及未来演变趋势进行研究。结果表明：（1）汛期总降雨量、总降雨日、小雨量和小雨日均表现出减少趋势,倾向率为-1.9 mm/10 a,-0.3 d/10 a,-2.9 mm/10 a和-0.4 d/10 a,均在20世纪60年代和21世纪前10年出现减少和增加的突变。中雨和大雨及以上等级降雨量（日）表现出微弱增加趋势。（2）各等级降雨量和降雨日的周期震荡较一致,小雨、大雨及以上和总降雨量（日）以年代际震荡（20~25年）为主,中雨以年际震荡（3~4年）为主。未来小雨、中雨和总降雨量（日）继续减少,大雨及以上降雨量（日）短期内继续微弱增加,2015年后减少。（3）综合利用小波分析和Hurst指数试验可为未来降雨气候变化趋势做出全面诊断和预测。     

Feasibility of open recirculating system in temperate climate – a case study

The increasing number of depleted, overexploited and recovering world marine stocks, together with increasing demand for fish and need for sustainable management of aquatic resources has led to a gradual shift to inland intensive aquaculture with water reuse. Intensive recirculating systems are becoming a rapidly developing sector of aquaculture, with the objectives to increase production and minimize environmental impact. However, transfer of technologies from original sites to locations of different climate is not always successful. The present study evaluates the use of an open recirculating system in a temperate climate. The 3‐year study showed successful production with better fish growth and feed utilization than in a flow‐through facility at the same site, but presented significant issues necessitating changes in technology as well as physical adaptations. A positive effect of the technology with respect to the environment is possible, but systems must be adapted to temperate climatic conditions.     

5GDZ1500钢带式干燥设备均风装置风速场数值仿真分析

基于CFD数值模拟技术,研究5GDZ1500型钢带式干燥设备均风装置内气流速度的分布,运用k-ε标准双方程湍流模型对不同气流速度对均风装置内气流分布的情况进行仿真模拟,并与试验测得结果相比较,证明模拟方案可行,而且说明气流通过均风装置后不是直接穿过干燥钢带。     

Nitrogen additions inhibit nitrification in acidic soils in a subtropical pine plantation: effects of soil pH and compositional shifts in microbial groups

Plantation forests play a pivotal role in carbon sequestration in terrestrial ecosystems, but enhanced nitrogen(N) deposition in these forests may affect plantation productivity by altering soil N cycling. Hence,understanding how simulated N deposition affects the rate and direction of soil N transformation is critically important in predicting responses of plantation productivity in the context of N loading. This study reports the effects of N addition rate(0, 40, and 120 kg N ha^-1 a^-1) and form(NH_4Cl vs. NaNO_3) on net N mineralization and nitrification estimated by in situ soil core incubation and on-soil microbial biomass determined by the phospholipid fatty acid(PLFA) method in a subtropical pine plantation. N additions had no influences on net N mineralization throughout the year. Net nitrification rate was significantly reduced by additions of both NH_4Cl(71.5) and NaNO_3(47.1%) during the active growing season, with the stronger inhibitory effect at high N rates. Soil pH was markedly decreased by 0.16 units by NH_4Cl additions. N inputs significantly decreased the ratio of fungal-to-bacterial PLFAs on average by 0.28(49.1%) in November. Under NH_4Cl additions, nitrification was positively related with fungal biomass and soil pH. Under NaNO_3 additions,nitrification was positively related with all microbial groups except for bacterial biomass. We conclude that simulated N deposition inhibited net nitrification in the acidic soils of a subtropical plantation forest in China,primarily due to accelerated soil acidification and compositional shifts in microbial functional groups. These findings may facilitate a better mechanistic understanding of soil N cycling in the context of N loading.     

呼伦贝尔退化草场土壤AM真菌多样性及与土壤因子的相关性分析

指出了草原是我国面积最大的陆地生态系统,约占陆地总面积的20%,在国家生态安全中有着重要的作用。但是由于近年来过量的放牧和毁草开荒等人为因素,使草原生态环境受到严重破坏,这严重影响了我国的社会经济发展。以内蒙古呼伦贝尔退化草原为研究对象,调查研究了不同退化程度草场的牧草根段AM真菌侵染率及多样性的变化,根据土壤因子分析引起这种变化的原因。研究结果显示:土壤含水量、土壤团聚体结构数量、总碳含量、土壤脲酶活性随草地退化程度的加深而显著下降,土壤pH值和EC值随草地退化程度的增加而显著升高,而土壤有效磷含量、土壤蔗糖酶活性和碱性磷酸酶活性则呈现出轻度退化>未退化>中度退化>重度退化的趋势。牧草根段AM真菌侵染率随退化程度加深而显著下降,并与土壤含水量、脲酶活性呈显著正相关,与土壤pH值、EC值呈显著负相关。从土壤样品DNA中扩增AM真菌特异性片段并采用DGGE技术对AM真菌多样性进行分析,发现AM真菌多样性指数、丰富度、均匀度变化均呈现轻度退化>未退化>中度退化>重度退化的趋势,且都与土壤有效磷、碱性磷酸酶活性呈显著正相关,与蔗糖酶活性呈极显著正相关。研究表明:人为干扰对草原土壤根际AM真菌群落有不同程度的影响,且于土壤因子之间存在一定的相关性。这些研究可为更好地理解草原退化原因及更有效地进行草原植被开发和修复提供可靠地理论依据。     

Rf-1位点CAPS标记对水稻不同胞质雄性不育育性恢复系的关系分析

水稻育性恢复基因Rf-1是目前水稻上克隆的唯一恢复基因.通过位于Rf-1位点的两个特异性CAPS(cleavable amplified polymorphic sequences)标记对滇I型、野败型、红莲型及BT型恢复系基因型分析,发现这四种不同胞质的恢复系在Rf-1位点具有相同的带型,滇I型的两个保持系具有不同的带型.结果表明这四种不同胞质系统的恢复系均具有Rf-1基因.该结论与从恢复系选育的系谱分析的结果相一致的.