简介：Huanghe河三角洲是世界的大河之一，自从最后，Huanghe河里的Huanghe河三角洲paleoenvironmental进化是一个热问题冰川。基于联合AMS14核心DYZK1沉积标明日期在的C在亚底部侧面上Huanghe河三角洲和声学的顺序沉没了，phytolith分析在96件沉积样品上被执行。谷物尺寸参数，磁性的危险性与biostratum的垂直变化被相结合重建在Huanghe河三角洲的paleo沉积、气候的条件。在索引参数有一条重要垂直变化法律的学习结果表演，和Huanghe河三角洲的那沉积环境经历了河的facies-sealand转变的进化进程外形潮汐的完全外形浅海的faciesdelta外形自从26.0kaB。P...phytolith分析结果如下。第一，phytoliths被划分成矛尖状，光滑伸长，多刺伸长，一种特殊格律，长矩形，bulliform和其它类型。在不同sedimental环境，phytolith内容定期变化，显示phytolith在沉积环境有的一样装配稳定性的某个度。第二，矛尖状，phytoliths的光滑伸长和多刺伸长范畴在潮汐的扁平的外形和三角洲免职有更大的内容，当时一在浅海的外形的更小的内容和河的外形环境。通过变化系数的比较分析，第三，在沉积的主要phytolith范畴的内容在sealand转变外形和河的外形免职有一个更大的变化振幅，当在tidalflat外形和三角洲外形免职是更稳定的时。

简介：Thehighstrengthlow-alloysteelsareweldedbyunderwaterwetweldingwithstainlesssteelelectrodes.Themicrostructuralandelectrochemicalcorrosionstudyofbasemetal(BM),weldzone(WZ)andheataffectedzone(HAZ)arecarriedouttounderstandtheinfluenceofthecorrosionproductlayergeneratedonthehighstrengthlow-alloysteelsweldedbyunderwaterwetweldingwithstainlesssteelelectrodes,methodsusedincluding,potentiodynamicpolarization,electrochemicalimpedancespectroscopy(EIS)andscanningelectronmicroscope(SEM).TheresultsindicatethattheWZactsasacathodeandthereisnocorrosionproductonitthroughouttheimmersionperiodinseawater.TheHAZandBMactsasanodes.ThecorrosionratesoftheHAZandBMchangewiththeimmersiontimeincreasing.Intheinitialimmersionperiod,theHAZhasthehighestcorrosionratebecauseithasacoarsetemperedmartensitestructureandtheBMexhibitesamicrostructurewithveryfinegrainsofferriteandpearlite.Afteraperiodofimmersion,theBMhasthehighestcorrosionrate.ThereasonisthatthecorrosionproductlayerontheHAZisdenseandhasabetterprotectivepropertywhilethatontheBMislooseandcannotinhibitthediffusionofoxygen.

简介：Theproceduresofultrasonicextractionandclean-upwereoptimizedforthedeterminationofpolycyclicaromatichydrocarbons(PAHs)inmarinesediments.Sampleswereultrasonicallyextracted,andtheextractswerepurifiedwithaminiaturizedsilicagelchromatographiccolumnandanalyzedwithhighperformanceliquidchromatography(HPLC)withafluorescencedetector.Ultrasonicationwithmethanol-dichloromethane(2:1,v/v)mixturegavehigherextractionefficiencythanthatwithdichloromethane.Amongthethreeelutionsolventsusedinclean-upstep,dichloromethane-hexane(2:3,v/v)mixturewasthemostsatisfactory.Undertheoptimizedconditions,therecoveriesintherangeof54.82%to94.70%withRSDsof3.02%to23.22%foraspikedblank,andintherangeof61.20%to127.08%withRSDsof7.61%to26.93%foraspikedmatrix,wereobtainedforthe15PAHsstudied,whiletherecoveriesforaNISTstandardreferenceSRM1941bwereintherangeof50.79%to83.78%withRSDsof5.24%to21.38%.Thedetectionlimitswerebetween0.75ngL-1and10.99ngL-1fordifferentPAHs.AsamplefromtheJiaozhouBayareawasexaminedtotesttheestablishedmethods.