Density of supercritical CO_2-tetrahydrofuran binary mixture and the partial molar volume of the cosolvent

The densities of supercritical CO2-tetrahydrofuran (cosolvent) binary mixture weremeasured at temperatures in range of 308.15 to 323.15 K and at pressure up to 16.5 MPa.The concentrations of tetrahydrofuran were from 0 to 0.57 mol/L.The partial molar volume of tetrahydrofuran was calculated based on the relationship between the density of the mixture and the concentration of the cosolvent.It is observed that the partial molar volume of the cosolvent is negative and the absolute value decreases with increasing pressure and the concentration of the cosolvent.     

A New Method for the Synthesis of C/D Ring Synthon of Vitamin D

Inrecentyears,vitaminDresearchareahasbeenstimulatedbythediscoveriesthatIQ,25-dihydroxyvitaminD,,theactivemetaboliteofvitaminD,,inadditiontotheclassicalrolesofregulatingcalciumandphosphorusmetabolisms',hasamuchbroaderspectrumofactivitiesthanoriginallythought,suchaspromotingcelldifferelltiationandinhibitingcellproliferation"'.Thebiologicalsignificanceandmedicalneedshaveledeffortstowardthesearchforanaloguesofpotentcelldifferelltiationandantiproliferationactivitywithouttoxichypercalcemiaassociate…     

Eucaglobulin, A New Complex of Gallotannin and Monoterpene from Eucalyptus globulus

EucalyPtusgl0bulusLabill.(Myrtaceae)isakindofmedicinalplantwidelydistributedintheYunnanpr0vinceofChina.ItSleaves,rootSandffoitShavebeenusedastraditionalremediesforthetreatmentofinfluenza,dysentery,enteritis,rheumatalgiaandbleeding.BesidesvolatileterpenoidconstituentSintheessential0iloftheleavesandfruits,theoccurrenceofanumber0fphloroglucinol-sesquiterpene-or-m0n0terpene-c0upledcomPoundsnamedmacrocarpals'andeugl0bals'intheleavesandbudshasbeenrepofted.Inordertostudythechendcalandbioactivecon…     

Quantitation of PCR Products by Capillary Electrophoresis in a Single Run

IntroductionItisnecessarytoevaluatetheamountofDNAfragmentinsuchcasesasgeneexpressioninvestigati0n.HybridizationwithradioactivitytaggedoligonucleotidesfollowedbyphotograPhyanddensitometricscanisoftenemployedtomeettheneedsofsuchrequirementS,whichislaborintensive,timec0nsumingandunautomated-CaPillaryelectrophoresis(CE)tendst0beastrongtoolintheanalysis0fDNAfragmentSwiththeadvantagesofhighsensitivity,highres0luti0nandautomation.QuantitativeanalysisofDNAfragmentshasbeendonebysomeauthorsusingC…     

A Convenient Method for the Stereoselective Synthesis of 7αHydroxycholesterol

7-Hydroxyderivativesofcholesteroldisplayawidevarietyofbiologicalactivities'-',mostofwhicharerelatedtothephysiologicalcontrolofcholesterolbiosynthesisandantitumoractivity.Inearlyreports',the7-hydroxycholesterolswerepreparedbythesequenceofacetylation,allylicchromicoxidation,andhydridereduction.Generally,theproductisamixtureof7a-and76-epimerswhichisdifficulttobeseparated.V.Kumaretal5improvedthisprocedurebyusingstereospecificreducingreagentsinsteadofthesimplehydride.7a-and7o-epimerscouldbeobtained…     

Stability and Luminescence Properties of Tb (Ⅲ) Complexes with Adrenaline

Theinteractionofrareearthwithhormoneshouldbestudiedindetailinordertoexploremechanismoftheneuralandendocrineeffectofrareearth.Asacontinuationofourresearchontheinteractionofrareeafthwithhormone',stabilityandluminescencepropertiesofTb(lII)complexeswithadrenalineorepinephrine(3,4-dihydroxy-a(methylaminomethyl)benzylalcohol,(HO)zCeH3CH(OH)CH=NHCHshavebeenstudiedinthiswork.Satisfactoryresultshavebeenobtained.PotentiometrictitrationsweremadeonapHS-3CpHmeterbymeansofthemethoddescribedinpreviou…     

Pt/Nafion膜制备的研究

采用还原剂渗透还原法制备了不同Pt载量的Pt/Nafion膜,并利用扫描电镜(SEM),X射线衍射分析(XRD)对反应不同时间制得的Pt/Nafion膜中的Pt在膜内及膜表面的生长情况进行了研究。实验发现:Pt在膜内及膜表面均能发生生长,且主要沉积在膜内靠近膜表面处的一段区间。采用KBH~4还原H~2PtCl~6有利于Pt(111)晶面的生长。分析不同反应时间的横截面及正面照片,提出了Pt生长的可能机理。     

超高交联树脂的功能基化及应用研究进展

作为一类新型的复合功能吸附材料,含功能基的超高交联树脂以其较高的比表面积、刚性的骨架、良好的亲水性、较高的机械强度、可调的孔径结构、良好的选择吸附性和易再生的优势已在许多领域得到广泛应用。本文综述了近年来不同功能基修饰的超高交联复合功能树脂的合成方法、功能基对目标吸附质的选择性机理以及该类新吸附材料在废水处理、药物分离提纯、化学分析等领域的应用研究进展,最后对超高交联复合功能树脂的进一步推广应用中面临的问题提供了建议和展望。     

θ-2θ型X射线衍射仪测定水溶液的结构

采用θ-2θ型粉末衍射仪并以NaCl溶液为研究对象,完成了该溶液不同浓度的结构测定,验证了方法在测定溶液尤其是低浓度溶液中的可行性。由衍射数据可知,随着浓度的提高,溶液的衍射曲线的特征峰由13.4°到14°发生偏移,且19°肩峰逐渐消失,表明随着浓度的增大,NaCl溶液的微观结构发生了较明显的变化。利用PDFgetX3软件对衍射数据进行了处理,得到了溶液的差值对分布函数,由差值对分布函数分析得到水分子间O-O间的峰位为0.276nm,该峰随浓度的增大,逐渐降低,当质量分数大于15%时出现了较明显的0.314nm处的Cl--O峰。     

离子色谱法同时测定不同时段酸雨中17种离子

应用离子色谱法同时测定不同时段酸雨中17种离子的含量。样品经离心沉淀后,经0.45μm滤膜过滤,滤液供离子色谱分析。阴离子分离时用Shodex SI-52 4E阴离子色谱柱,并用3.6mmol·L-1碳酸钠-0.6 mmol·L-1碳酸氢钠缓冲溶液作为淋洗液;阳离子分离时用TSKGEL阳离子色谱柱,并用2mmol·L-1硝酸溶液作为淋洗液,采用电导检测器进行检测。17种离子均在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在1.4~18.7μg·L-1之间。回收率在95.0%~105%之间,测定值的相对标准偏差(n=6)在1.7%~7.2%之间。