学科分类
/ 7
129 个结果
  • 简介:Arapidmethodhasbeendevelopedforrapidsampleclean-upinthedeterminationofthepharmacologicallyactiveterpenoidincludingginkgolideA,B,Candbilobalideinginkgobilobaleavesextracts(GBE).Theextractsaredissolvedin7%ofethanolaqueoussolutionandthenpurifiedbyahighlyselectivepolyericadsorbentsolid-phasechromatographiccolumn.Afterbeingconcentrated,theseparatedterpenoidswithnophenolicdistrubancearedeterminedbyhighperformanceliquidchromatorgraphyonaNova-PakC18columnwithmethanol-water(30:70)aseffluentandrefractiveindexdetection.Therecoveryofthemethodisabout95%andthenewmethodsavesmoretimethantheconventionaltwo-columnpurificationmethod.

  • 标签: 吸附剂 银杏酚 提纯
  • 简介:疲劳裂缝和疲劳损坏是为轮船的重要的期并且近海结构很长时间。在最后十年,与在壳结构和逐渐地大的轮船尺寸的更高张力的钢的介绍,然而,更大的注意应该被给予使问题疲劳。的大多数研究焦点更容易存取轮船的疲劳力量。另外,主要分类社会已经释放了他们的疲劳评价笔记。由于影响疲劳表演的因素的复杂性,然而从货物,不同压力部件的联合,本地结构细节的集中上的压力,工具压力,和腐蚀剂环境装载例如波浪并且迫使,有有改变分类社会的不同说明,从不同疲劳评价方法导致不同结果。这篇论文证实DetNorskeVeritas(DNV)分类笔记使对解释疲劳评价的过程的轮船结构的评价疲劳并且简化了方法。最后,疲劳分析被一艘真实轮船的使用数据执行,结果的可靠性被估计。

  • 标签: 疲劳分析 船体结构 快速估算 载重吨 挪威船级社 疲劳评估
  • 简介:Inthisstudy,threerapidrepairtechniquesareproposedtoretrofitcircularbridgepiersthatareseverelydamagedbytheflexuralfailuremodeinmajorearthquakes.Thequasi-statictestsonthree1:2.5scaledcircularpierspecimensareconductedtoevaluatetheefficiencyoftheproposedrepairtechniques.Forthepurposeofrapidrepair,therepairprocedureforallthespecimensisconductedwithinfourdays,andthebehavioroftherepairedspecimensisevaluatedandcomparedwiththeoriginalones.Afiniteelementmodelisdevelopedtopredictthecyclicbehavioroftherepairedspecimensandthenumericalresultsarecomparedwiththetestdata.Itisfoundthatalltherepairedspecimensexhibitsimilarorlargerlateralstrengthanddeformationcapacitythantheoriginalones.Theinitiallateralstiffnessofalltherepairedspecimensislowerthanthatoftheoriginalones,whiletheyshowahigherlateralstiffnessatthelaterstageofthetest.Nonoticeabledifferenceisobservedfortheenergydissipationcapacitybetweentheoriginalandrepairedpierspecimens.Itissuggestedthattherepairtechniqueusingtheearly-strengthconcretejacketconfinedbycarbonfiberreinforcedpolymer(CFRP)sheetscanbeanoptimalmethodfortherapidrepairofseverelyearthquake-damagedcircularbridgepierswithflexuralfailuremode.

  • 标签:
  • 简介:NanocrystallineMg2Ni-typealloyswithnominalcompositionsofMg20Ni10–xCux(x=0,1,2,3,4,massfraction,%)weresynthesizedbyrapidquenchingtechnique.Themicrostructuresoftheas-castandquenchedalloyswerecharacterizedbyXRD,SEMandHRTEM.Theelectrochemicalhydrogenstorageperformancesweretestedbyanautomaticgalvanostaticsystem.ThehydridinganddehydridingkineticsofthealloysweremeasuredusinganautomaticallycontrolledSievertsapparatus.Theresultsshowthatalltheas-quenchedalloysholdthetypicalnanocrystallinestructureandtherapidquenchingdoesnotchangethemajorphaseMg2Ni.Therapidquenchingsignificantlyimprovestheelectrochemicalhydrogenstoragecapacityofthealloys,whereasitslightlyimpairsthecyclingstabilityofthealloys.Additionally,thehydrogenabsorptionanddesorptioncapacitiesofthealloyssignificantlyincreasewithrisingquenchingrate.

  • 标签: 合金成分 快淬技术 储氢特性 高分辨透射电子显微镜 纳米晶 MG2NI
  • 简介:记忆B和T淋巴细胞的功能的角色位于预防种痘的非凡的成功下面,它减少了从传染疾病的病态和死亡全球性在最后50年。然而,逐渐地欣赏了那,正在变得记忆房间也能够调停与自体免疫的混乱联系的病理并且移植拒绝,并且可以提出一个重要障碍到未来在immunoregulation的临床的前进。因此,理解记忆淋巴细胞的唯一的性质(作为与他们的天真的先锋相比)是调查的一个主要区域。这里,我们集中于记忆T房间(TM)的那些单个性质之一鈥攔apid召回。当愿望更详细地被讨论,快速的召回指静止TM房间的能力到“高效地并且要用体力地快速的受动器功能”跟随刺激。用CD4+T房间推进了我们TM房间的快速的召回的理解的研究是熟练地在其它地方考察了1,我们将因此首先集中于CD8+T房间的研究。我们将首先考察CD8+TM房间能被产生的不同方法,由讨论这怎么在有免疫力的保护和病理的背景影响他们的功能的性质列在后面。然后,快速的召回能力将被讨论,与放在当前对机制被知道位于TM房间的这个唯一的性质下面的上的强调。

  • 标签: 理解记忆 T细胞 CD8 快速反应 召回 自身免疫性疾病
  • 简介:粘贴的性质在淀粉的最重要的特征之中,决定它在食物处理和另外的工业的应用。粘贴温度源于快速的Visco分析器(RVA)(Newport科学)在大多数情况中,被Thermocline为Windows过高估计软件节目。这里,便于由RVA粘贴温度的精确测量的二个方法被描述。一个人到变化参数设定到“屏幕”粘贴的粘性开始增加的真点,其它将手工地记录粘贴的粘性开始与公式增加并且计算粘贴的温度的时间(T1)(45/3.8)为米饭的x(T1-1)+50面粉。后者方法给了显著地与gelatinization被相关的手工地坚定的粘贴温度微分扫描caiorimetry测量的温度。

  • 标签: 稻子 淀粉 凝胶温度 方法论
  • 简介:Haveyoueverseenscientistslisteningattentivelytoresearchtalkswhilstsitting,standingorlyingonthesand?Well-knownscientificpersonalitiespresentingtheirresultsonanimprovisedblackboardleaningagainstafour-wheeldrivevehicle,oranacaciatree(weavoidedcamelswhichdefinitivelymovetoomuch)?Ifnot,youshouldhavetakenparttothefirstofsixinternationalmeetingson“RapidandcatastrophicenvironmentalchangesintheHoloceneandhumanresponse”.ThisconferencewasheldinMauritaniafrom4to18January2004,withthefirstweekalongthecoastoftheNatureParkofBancd'ArguinandthesecondoneontheAdrarplateau.Inattendancewere29participantsfrom17countrieswhoweredrawntheretoexamineinthefieldvariousphenomenalinkedtothethemeofthemeeting,

  • 标签: 人类活动 自然灾难 观测预报 防治方法 学术交流
  • 简介:CellularspacingselectionofCu-27.3wtpctMnalloyhasbeeninvestigatedbylasersurfacerapidresolidificationexperiments.Theexperimentalresultsshowthatthereexistsawidedistributionrangeincellularspacingunderultra-hightemperaturegradientandrapidsolidificationconditionsandtheaveragespacingdecreasewithincreaseofthegrowthrate.TheexperimentalresultsarecomparedwiththecurrentKGTmodelforrapidcellular/dendriticgrowth,andareasonableagreementisfound.

  • 标签:
  • 简介:AbstractA series of stringent non-pharmacological and pharmacological interventions were implemented to contain the pandemic but the pandemic continues. Moreover, vaccination breakthrough infection and reinfection in convalescent coronavirus disease 2019 (COVID-19) cases have been reported. Further, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants emerged with mutations in spike (S) gene, the target of most current vaccines. Importantly, the mutations exhibit a trend of immune escape from the vaccination. Herein the scientific question that if the vaccination drives genetic or antigenic drifts of SARS-CoV-2 remains elusive. We performed correlation analyses to uncover the impacts of wide vaccination on epidemiological characteristics of COVID-19. In addition, we investigated the evolutionary dynamics and genetic diversity of SARS-CoV-2 under immune pressure by utilizing the Bayesian phylodynamic inferences and the lineage entropy calculation respectively. We found that vaccination coverage was negatively related to the infections, severe cases, and deaths of COVID-19 respectively. With the increasing vaccination coverage, the lineage diversity of SARS-CoV-2 dampened, but the rapid mutation rates of the S gene were identified, and the vaccination could be one of the explanations for driving mutations in S gene. Moreover, new epidemics resurged in several countries with high vaccination coverage, questioning their current pandemic control strategies. Hence, integrated vaccination and non-pharmacological interventions are critical to control the pandemic. Furthermore, novel vaccine preparation should enhance its capabilities to curb both disease severity and infection possibility.

  • 标签: SARS-CoV-2 Vaccine Genetic evolution Genetic drift Antigenic drift Lineage divergence Epidemiological characteristics
  • 简介:Asanimportantnon-ferrousmetalstructuralmaterialmostusedinindustryandproduction,aluminum(Al)alloyshowsitsgreatvalueinthenationaleconomyandindustrialmanufacturing.HowtoclassifyAlalloyrapidlyandaccuratelyisasignificant,popularandmeaningfultask.Classificationmethodsbasedonlaser-inducedbreakdownspectroscopy(LIBS)havebeenreportedinrecentyears.AlthoughLIBSisanadvanceddetectiontechnology,itisnecessarytocombineitwithsomealgorithmtoreachthegoalofrapidandaccurateclassification.Asanimportantmachinelearningmethod,therandomforest(RF)algorithmplaysagreatroleinpatternrecognitionandmaterialclassification.ThispaperintroducesarapidclassificationmethodofAlalloybasedonLIBSandtheRFalgorithm.TheresultsshowthatthebestaccuracythatcanbereachedusingthismethodtoclassifyAlalloysamplesis98.59%,theaverageofwhichis98.45%.ItalsorevealsthroughtherelationshiplawsthattheaccuracyvarieswiththenumberoftreesintheRFandthesizeofthetrainingsamplesetintheRF.Accordingtothelaws,researcherscanfindouttheoptimizedparametersintheRFalgorithminordertoachieve,asexpected,agoodresult.TheseresultsprovethatLIBSwiththeRFalgorithmcanexactlyclassifyAlalloyeffectively,preciselyandrapidlywithhighaccuracy,whichobviouslyhassignificantpracticalvalue.

  • 标签: LASER-INDUCED BREAKDOWN spectroscopy(LIBS) random forest(RF) aluminum(Al)alloy
  • 简介:ToestablisharapididentificationmethodforcommonpathogenicbacteriaonthebasisofmolecularbiologyandtoconstructapreliminaryPolymeraseChainReaction-CapillaryElectrophoresis-RestrictionFragmentLengthPolymorphism(PCR-CE-RFLP)databaseofbacteriaisolatedfromclinicalspecimensfrequently,183strainscollectedfromclinicalsamplesbelongingto12generaand19specieswhosebiochemicalcharacterizationscorrespondedtothetypicaloneswereexamined.ThegenomicDNAswereamplifiedbytwopairsoffluorescencelabeledprimersaimingat16SrRNAgeneand16S-23SrRNAspacerregiongenerespectivelyatthesametime.PCRproductswerethendigestedbyrestrictionendonucleaseHaeⅢin-completelybeforetakingcapillaryelectrophoresis.TheresultswiththePCR-CE-RFLPpatternsof16SrRNAgeneswerejustalikewithinsomegenera,butwhenitcomesto16S-23SrRNAspacerregiongenes,eachbacteriumshowedauniquepattern,whichcanbedistinguishedfromeachothereasily.ItseemsthatPCR-CE-RFLPpatternsof16SrRNAgenecouldonlybeusedtoclassifythebacteriaintofamilylevel,whereasthedataof16S-23SrRNAspacerregiongenecouldbeutilizedtoidentifythewholemicroorganismsaspreciselyasthespecieslevel.Inspiteofthedataofthespacerregiongenealonecanbesufficientlytoverifythewholebacteria,weinsistthatthe16SrRNAgenecouldbeofsomeassistantincasethatthereshouldbelotsoffamiliesofbacteria,inwhichsomesimilarones,withthesameRFLPdataof16S-23SrRNAspacerregiongene,maycoexist.ThisstudyprovesthattheutilityofPCR-CE-RFLPisaconvenient,rapidmethodtoidentifypathogenicbacteria,andisalsoaquickdiagnosismeasureforapplicationtoclinicaluse.

  • 标签: 快速鉴定法 保守基因 特效药 PCR-CE-RFLP 16S RRNA基因
  • 简介:Foraccuracyandrapidityofaudioeventdetectioninthemass-dataaudioprocessingtasks,agenericmethodofrapidlyrecognizingaudioeventbasedon2D-HaaracousticsuperfeaturevectorandAdaBoostisproposed.Firstly,itcombinescertainnumberofcontinuousaudioframestobean'acousticfeatureimage',secondly,usesAdaBoost.MHorfastRandomAdaBoostfeatureselectionalgorithmtoselecthighrepresentative2D-Haarpatterncombinationstoconstructsuperfeaturevectors;thirdly,analyzesthecommonalityanddifferencesbetweensubcategories,thenextractscommonfeaturesandreducesdifferentfeaturestoobtainagenericaudioeventtemplate,whichcansupporttheaccurateidentificationofmultiplesub-classesanddetectandlocatethespecificaudioeventfromtheaudiostreamaccurately.Experimentalresultsshowthattheuseof2D-Haaracousticfeaturesupervectorcanmakerecognitionaccuracy5%higherthanonesthatMFCC,PLP,LPCCandothertraditionalacousticfeaturesyielded,andcanmakethetrainingprocessing7-20timesfasterandtherecognitionprocessing5-10timesfaster,itcanevenachieveanaverageprecisionof93.38%,anaveragerecallof95.03%undertheoptimalparameterconfigurationfoundbygridmethod.Aboveall,itcanprovideanaccurateandfastmass-dataprocessingmethodforaudioeventdetection.

  • 标签: 事件检测 特征向量 音频帧 ADABOOST 声学特征 平均精度
  • 简介:AbstractBackground:Despite major reductions in malaria burden across Myanmar, clusters of the disease continue to persist in specific subregions. This study aimed to assess the predictors of test positivity among people living in Paletwa Township of Chin State, an area of persistently high malaria burden.Methods:Four villages with the highest malaria incidence from Paletwa Township were purposively selected. The characteristics of 1045 subjects seeking malaria diagnosis from the four assigned village health volunteers from January to December, 2018 were retrospectively analyzed. Their household conditions and surroundings were also recorded using a checklist. Descriptive statistics and logistic regression models were applied to investigate potential associations between individual and household characteristics and malaria diagnosis.Results:In 2017, the Paletwa township presented 20.9% positivity and an annual parasite index of 46.9 cases per 1000 people. Plasmodium falciparum was the predominant species and accounted for more than 80.0% of all infections. Among 1045 people presenting at a clinic with malaria symptoms, 31.1% were diagnosed with malaria. Predictors for test positivity included living in a hut [adjusted odds ratios (a OR): 2.3, 95% confidence intervals (CI): 1.2-4.6], owning farm animals (aOR: 1.7, 95% CI: 1.1-3.6), using non-septic type of toilets (aOR: 1.9, 95% CI: 1.1-8.4), presenting with fever (aOR: 1.9, 95% CI: 1.1-3.0), having a malaria episode within the last year (aOR: 2.9, 95% CI: 1.4-5.8), traveling outside the village in the previous 14 days (aOR: 4.5, 95% CI: 1.5-13.4), and not using bed nets (a OR: 3.4, 95% CI: 2.3-5.1). There were no statistically significant differences by age or gender in this present analysis.Conclusions:The results from this study, including a high proportion of P. falciparum infections, little difference in age, sex, or occupation, suggest that malaria is a major burden for these study villages. Targeted health education campaigns should be introduced to strengthen synchronous diagnosis-seeking behaviors, tighten treatment adherence, receiving a diagnosis after traveling to endemic regions, and using bed nets properly. We suggest increased surveillance, early diagnosis, and treatment efforts to control the disease and then to consider the local elimination.

  • 标签: Malaria Trend Risk Endemic area Myanmar
  • 简介:Energy-storageweldingconnectioncharacteristicsofrapidlysolidifiedAZ91DMgalloyribbonswith40~70μmthicknessareinvestigatedusingamicrotypeenergy-storageweldingmachine.Themicrostructureandperformanceoftheconnectionjointsareanalyzedandstudied.Theresearchresultsindicatethatenergy-storageweldingisabletorealizethespotweldingconnectionofAZ9lDMgalloyribbons.Theweldingnuggetconsistsofdevelopedα-Mgequiaxedgrainswiththesizesof1.2~2.7μmandintergranulardistributedβ-Mg17Al12compounds.Thethicknessofbondzoneisabout4μmandthesolidificationmicrostructureischaracterizedbythefineequiaxedgrainswiththesizesof0.8~1.2μm,andgrainboundaryhasbecomecoarsening.ThecolumnarcrystalinHAZalsobecomesslightlycoarseningandthegrainboundaryhasbroadened,however,thereisnoobviouschangeinitsprimitivemorphologyandcrystallographicdirection.Whenweldingenergyisabout2.0J,theweldingjointswithhighershearstrengthandsmallerelectricalresistivityareobtained.

  • 标签: AZ91D 快速硬化 储能焊接 微结构 镁合金
  • 简介:模仿半固体金属形成要求建模半固体行为。然而,因为半固体行为是thixotropic并且取决于液体固体,如此的建模是困难的在材料以内的空间分发。以便更好理解并且当模特儿在微观结构和行为之间的关系,一个模型基于micromechanical,途径和homogenisation技术被介绍。这个模型是在一个纯viscoplastic框架建立说明弹性的一个以前的模型的扩展。确实,当半固体在快速的压缩下面被装载时,试验性的负担排水量信号在变丑的更早的阶段揭示有弹性类型的回答的存在。行为的这个有弹性的特征被归因于多孔的稳固的骨骼的反应由不可压缩的液体浸透了。好量的同意在elastic-viscoplastic之间被发现的A预言了反应和试验性的数据。更精确,在负担的负担排水量曲线,山峰负担和随后的秋天的强壮的起始的升起部分很好被捕获。机械反应上的稳固的部分的效果在对实验的质的同意。

  • 标签: 半固态金属成形 不可压缩液体 实验测试 模拟 多尺度 弹性功能
  • 简介:Significantpostseismicdeformationofthe2008MW7.9WenchuanearthquakehasbeenobservedfromGPSdataofthefirst14daysaftertheearthquake.Thepossiblemechanismsfortherapidpostseismicdeformationareassumedtobeafterslipontheearthquakeruptureplaneandviscoelasticrelaxationofcoseismicllystresschangeinthelowercrustoruppermantle.WefirstlyusetheconstrainedleastsquaresmethodtofindanafterslipmodelwhichcanfittheGPSdatabest.Theafterslipmodelcanexplainnear-fielddataverywellbutshowsconsiderablediscrepanciesinfittingfar-fielddata.Toestimatetheeffectduetotheviscoelasticrelaxationinthelowercrust,wethenignorethecontributionfromtheafterslipandattempttoinverttheviscositystructurebeneaththeLongmenshanfaultwheretheWenchuanearthquakeoccurredfromthepostseismicdeformationdata.Forthispurpose,weuseaviscoelasticmodelwitha2DgeometrybasedonthegeologicalandseismologicalobservationsandthecoseismicslipdistributionderivedfromthecoseismicGPSandInSARdata.Bymeansofagridsearchwefindthattheoptimumviscosityis9×1018Pa·sforthemiddle-lowercrustintheChengduBasin,4×1017Pa·sforthemiddle-lowercrustintheChuanxiPlateauand7×1017Pa·sforthelowvelocityzoneintheChuanxiplateau.Theviscoelasticmodelexplainsthepostseismicdeformationobservedinthefar-fieldsatisfactorily,butitisconsiderablyworsethantheafterslipmodelinfittingthenear-faultdata.Itsuggeststhereforeahybridmodelincludingbothafterslipandrelaxationeffects.Sincetheviscoelasticmodelproducesmainlythefar-fieldsurfacedeformationandhasfewerdegreeoffreedoms(threeviscosityparameters)thantheafterslipmodelwithahugenumberofsourceparameters,wefixtheviscositiystructureasobtainedbeforebutredeterminetheafterslipdistributionusingtheresidualdatafromtheviscoelasticmodeling.Theredeterminedafterslipdistributionbecomesphysicallymorereas

  • 标签:
  • 简介:InthisstudyweassessedthecurrentstatusofcoralreefsalongtheSaudiArabiancoastoftheRedSea.AmongthethreegrowthformsofAcroporidcorals,thebranchingformswerefoundtodominateintheFarassanIslands(44.55%±11.10%cover)followedbytabularformsintheDogaIslands(rangingbetween18%±6.47%and18.30%±9.47%cover).DigitateformswererarelyfoundalongthecoastexceptatMaqna.Amongthefivegrowthformsofnon-Acroporidcorals,weobservedmaximumcoverofbranchingformsintheYanbuoffshorearea(58.89%±15.11%cover)followedbytheJeddahcoast(24.76%±14.04%cover).TheMilleporaspp.,anon-Scleractiniancoral,wasabundantatallthenear-shoresites,suchasJeddah(10.70%±8.21%)andAl-Wajh(9.81%±6.69%).Thelivecoralcover(includingbothScleractinianandnon-Scleractiniancorals)ofSaudiRedSeacoastwasseentobehigherinthenorthandgraduallydecreasetowardsthesouth.PrincipalComponentanalysisshowedthatthecontributionofAcroporidcoralswasgreaterinthesouthernregionthaninthenorthernandmiddleregions,butvice-versainthecaseofnon-Acroporidcorals.Bray-Curtisclusteranalysiscategorizedallthestudysitesintotwomajorclusterswith60%similarity.Amongthem,onecluster-formingsitesfromMaqnatoMasturah(Northernregion)andthesecondonecomprisedthemiddleandsouthernregions(JeddahtoFarassanIslands),andoneoutlierRabigh.

  • 标签: 造礁石珊瑚 沙特阿拉伯 快速评估 海岸 生长形态 红海