学科分类
/ 1
5 个结果
  • 简介:Systemsofphotosyntheticreactioncentreshavebeenmodelledasheatengines,whileithasalsobeenreportedthattheefficiencyandpowerofsuchheatenginescanbeenhancedbyquantuminterference—atraitthathasattractedmuchinterest.Wecomparetwodefinitionsoftheworkofsuchaphotosyntheticheatengine,i.e.definitionAusedbyWeimeretal.andBbyDorfmanetal.Wealsointroduceacoherentinteractionbetweendonorandacceptor(CIDA)todemonstrateareversibleenergytransport.Weshowthatthesetwodefinitionsofworkcanimpartcontradictoryresults,thatis,CIDAenhancesthepowerandefficiencyofthephotosyntheticheatenginewithdefinitionBbutnotwithA.Additionally,wefindthatbothreversibleandirreversibleexcitation-energytransportcanbedescribedwithdefinitionA,butdefinitionBcanonlymodelirreversibletransport.Asaresult,weconcludethatdefinitionAismoresuitableforphotosyntheticsystemsthandefinitionB.

  • 标签: QUANTUM WORK HEAT ENGINE PHOTOSYNTHESIS
  • 简介:Biologicalmaterialssuchasbone,tooth,andnacreareload-bearingnanocompositescomposedofmineralandprotein.Sincethemineralcrystalsoftenhaveslendergeometry,thenanocompositesaresusceptibletobuckleunderthecompressiveload.Inthispaper,weanalyzethelocalbucklingbehaviorsofthenanocompositestructureofthebiologicalmaterialsusingabeam-springmodelbywhichwecanconsiderplentyofmineralcrystalsandtheirinteractioninouranalysiscomparedwithexistingstudies.Weshowthatthereisatransitionofthebucklingbehaviorsfromalocalbucklingmodetoaglobalonewhenwecontinuouslyincreasetheaspectratioofmineral,leadingtoanincreaseofthebucklingstrengthwhichlevelsofftothestrengthofthecompositesreinforcedwithcontinuouscrystals.Wefindthatthecontactconditionatthemineraltipshasastrikingeffectonthelocalbucklingmodeatsmallaspectratio,buttheeffectdiminisheswhentheaspectratioislarge.Ouranalysesalsoshowthatthestaggeredarrangementofmineralplaysacentralroleinthestabilityofthebiologicalnanocomposites.

  • 标签: 纳米复合材料 生物材料 弹簧模型 屈曲分析 蛋白质复合物 矿物晶体
  • 简介:CymbopogoncitratusisawidelydistributedperennialherbbelongingtothePoaceaefamilyandhasbeenextensivelyconsumedforitsmedicinal,cosmetic,andnutritionaleffectsforcenturies.Alargenumberofreportshavebeenpublisheddescribingthepharmacological,biological,andtherapeuticactionsofthisherb.Inthisreview,wesummarizedtheliteraturesonrelatedstudies(uptoJanuary,2014)thathighlightedthepharmacologicandbiologicaleffectsofthemajorphytochemicalsisolatedfromC.citratusextractsanditsessentialoil.ThecomponentsoftheessentialoilsfoundinC.citratushaveasimilarpharmacokineticproperties,includingabsorption,distribution,metabolism,andexcretion.Theyarequicklyabsorbedfollowingoral,pulmonary,anddermaladministration.Basedonthepublishedreports,itcanalsobeinferredthat,afterabsorptionfromthesmallintestine,somephytochemicalsinC.citratuscanundergooxidation,glucuronidation,sulfation,and/orO-methylation.Excretionisthroughurine,fecesand/orexpiredvolatiles.ThebiotransformationreactionsofC.citratusbioactiveconstituentsareessentialforitsrelativelysafeconsumptionandtherapeuticapplications.ThedataavailablesofarwarrantfurtherstudiesevaluatingC.citratuspharmacokinetics.ReliablepharmacokineticdatainhumanswouldbecriticalforabetterunderstandingofthethesystemichandlingofC.citratus.

  • 标签:
  • 简介:Purpose:Thisstudywastoinvestigatetheassociationbetweenulnarvariance(UV)andbiologicalandtrainingcharacteristics,handgrip,andwristpaininagroupof23Portugueseskeletallyimmaturemalegymnasts(aged11.22.5years).Methods:LeftandrightUVwasobtainedusingHafner'sprocedureandskeletalagewasdeterminedbytheTannereWhitehouse3-method.AnegativemeanvalueforUVmeasureswasobserved(2.4to3.6mm)withoutsignificantdifferenceswithincreasingage-category(p=0.09top=0.48).SignificantlowcorrelationswereobservedbetweensomeUVparametersandstature,fatpercentage,yearsoftraining,andlefthandgripstrength.Results:TengymnastsreportedwristpainwithgradualonsetandUVvalueswereverysimilarbetweenpainlessandpainfulwrists.Conclusion:ThefindingsofthisstudydonotdirectlysupportthethesisthatgymnasticstrainingandbiologicalvariablesorwristpainareassociatedwithUV.

  • 标签: 运动员 葡萄牙 疼痛 生物 体操 成熟