50%利谷隆可湿性粉剂防除蔺草田杂草效果试验

本试验于1月上中旬蔺草田杂草石龙芮出苗初见期．用50％利谷隆可湿性粉剂150g／667m。拌化肥均匀撒施，进行了50％利谷隆可湿性粉剂防除蔺草田杂草效果试验。试验结果显示，50％利谷隆对阔叶类杂草的株、鲜重防效分别为97．3％和96．2％；对杂草株、鲜重总防效分别为94．1％和95．5％；且对蔺草十分安全，未见异常现象。

Research on infiltration clogging effect and its application prospect in anti-seepage project

Clogging effect,as a new concept in geological engineering,is a phenomenon of permeability decreasing under seeping in reservoir dam foundation of the alluvial and diluvial deposits with deep and thick layer,coarse particle and high permeability in mountains-gully rivers of Tibetan Plateau.A clogging infiltration instrument has been designed successfully and a series of simulation tests have been done.Based on large amounts of data,it is confirmed that the existence of the clogging effect and the law of infiltration clogging is found out.Three indexes are proposed such as "optimal size of particle","optimal size range of particle" and "characteristic pore",which are closely related with effect of infiltration clogging.The concept and results can offer a new idea to solve problems on anti-seepage of dam foundation in mountains-gully rivers environment and to study artificial clogging,meanwhile supplement of the concept of seepage deformation.

Analysis of Electrical and Non-electrical Causes of Variable Frequency Drive Failures

VFDs （variable frequency drives） are an integral part of many industrial plants and stations. Reliable operation and maintenance of these drives is vital to ensure sustained plant operation and availability. Understanding of the principles of operation of VFD systems as well as knowledge about their required operating environment is necessary for all operating personnel. Many times the operating personnel do not get involved with different technical issues until a complete failure has occurred. Hence, the awareness of the most dominant failure causes has a significant impact on assisting operators to avoid catastrophic failures and tremendous economic losses due to VFD shutdown. Proper plant design, accurate monitoring and data logging, following manufacturer preventive maintenance schedule, and choosing qualified team of operators can be the key to an efficient operation and a long lifetime for any VFD system. In this paper, we have analyzed the electrical and non-electrical causes of VFD failures based on a case study of a typical medium voltage VFD pumping station. Finally, recommendations are given from field analysis and observations.

Simultaneous determination of 27 preservatives in toothpaste by high-performance liquid chromatography

A method of high-performance liquid chromatography(HPLC)was established for simultaneous determination of 27 preservatives in toothpaste.Toothpaste samples were extracted with 50%aqueous methanol solution,ultrasonicated and then filtered.The target compounds were separated on a C_(18) column(250 mm×4.6μm,5μm)with the mobile phase consisting of acetonitrile and aqueous phosphoric acid solution,the column temperature was 30℃,the sample volume was 10μL,the flow rate was 1 mL/min,and diode array detector was used.Under the optimal experimental conditions,good linear relationship was obtained and the correlation coefficient(R^(2))was greater than 0.9995.This method was accurate and sensitive,which was suitable for the qualitative and quantitative analysis of 27 preservatives in toothpaste.

Determination of 13 preservatives in cosmetics by high performance liquid chromatography and verification by mass spectrometry

A method using high performance liquid chromatography(HPLC)was developed for the s imultaneous determination of 13 preservatives(levulinic acid,p-hydroxyacetophenone,raspberry ketone,p-anisic acid,caprylhydroxamic acid,hydroxyethoxyphenyl butanone,methylisothiazolinone,phenoxyethanol,b e n z oic acid,methylparaben,chlorphenesin,dehydroacetic acid,and 5-bromo-5-nitro-1,3-dioxane)in cosmetics.Different types of samples were ultrasonically extracted by methanol,then the separation of 13 preservatives was carried out on a column of Agilent ZORBAX Eclipse XDB-C18(250 mm×4.6 mm,5μm)by gradient elution at a flow rate of 1.0 mL/min,using 0.1%phosphoric acid solution and acetonitrile as mobile phases.The column temperature was 30℃,and the detection was completed by a diode array detector with the wavelengths at 275,230 and 210 nm.Suspected positive samples were further confirmed by liquid chromatography-tandem mass spectrometry or gas chromatography-mass spectrometry.The linear regression analysis data shows good linearity for 13 preservatives in the respective mass concentration range,with their correlation coefficients(r)greater than 0.9998.The limits of detection(LODs)and limits of quantitation(LOQs)of the method are in the ranges of 0.4-100.0 mg/kg and 1.2-250.0 mg/kg,respectively.At three spiked levels,the average recoveries for 13 target compounds in three kinds of matrix samples are within 84.0%-115.4%,and the relative standard deviations(RSD)are within 0.5%-4.8%(n=6).This method is convenient,efficient,and precise,which can be used for qualitative and quantitative analysis of common preservatives in daily cosmetics.

Acute effect of tetrandrine pulmonary targeting microspheres on hypoxic pulmonary hypertension in rats

Objective To assess the effect of tetrandrine (Tet) pulmonary targeting microspheres on hypoxic pulmonary hypertension and evaluate its selective action on pulmonary circulation.Methods Twenty rats were exposed to hypoxic conditions for 3 weeks. Ten rats were used as normoxic controls. We administered Tet pulmonary targeting microspheres to 10 hypoxic rats and Tet aqueous solution to 10 hypoxic rats and the 10 control rats. Mean pulmonary arterial pressure (mPAP) was measured by a right cardiac catheterization, and mean systemic blood pressure (mSBP) was measured by left femoral catheterization. Results Rats exposed to hypoxia developed pulmonary hypertension. The decrease in mPAP in rats treated with Tet pulmonary targeting microspheres was significantly greater than that in rats receiving Tet aqueous solution (P【0.05), and the effects were longer with Tet pulmonary targeting microspheres. Moreover, Tet pulmonary targeting microspheres, unlike Tet aqueous solution, did not decrease mSBP.Conclusion Tet pulmonary targeting microspheres were more effective than Tet aqueous solution in treating hypoxic pulmonary hypertension and acted selectively on the pulmonary circulation.