简介：Poly(vinylalcohol)(PVA)/hydroxyapatite(HA)compositehydrogelspecimenswerepreparedwith15%PVAand1%,2%,3%,4%and5%HAbyrepeatedfreezing-thawing.ThetestsofstaticanddynamicmechanicalpropertieswerecarriedouttodiscusstheinfluenceofdifferentcontentsofHAandfreezing-thawingcyclesonthemechanicalpropertiesofPVA/HAcompositehydrogel.TheresultsofstaticmechanicaltestsshowedthatthePVA/HAcompositehydrogelwith3%HAandninefreezing-thawingcycleshadexcellentstressrelaxationproperties,higherrelaxationratio,lowerstressequilibriumvalueandpresentedbetterpropertiesofcreepandrecovery.TheresultsofdynamicmechanicaltestshowedthatthePVA/HAcompositehydrogelwithninefreezing-thawingcycleshadhigherstoragemodulusandlossmodulus,sowasthePVA/HAcompositehydrogelwith3%HA.

简介：Wedescribeafewmathematicaltoolswhichallowtoinvestigatewhetherair-waterinterfacesexist(underprescribedconditions)andaremechanicallystableandtemporallypersistent.Intermsofphysics,air-waterinterfacesaregovernedbytheYoung-Laplaceequation.Mathematicallytheyaresurfacesofconstantmeancurvaturewhichrepresentsolutionsofanonlinearellipticpartialdifferentialequation.Althoughexplicitsolutionsofthisequationcanbeobtainedonlyinveryspecialcases,itis-undermoderatelyspecialcircumstances-possibletoestablishtheexistenceofasolutionwithoutactuallysolvingthedifferentialequation.Wealsoderivecriteriaformechanicalstabilityandtemporalpersistenceofanairlayer.Furthermorewecalculatethelifetimeofanon-persistentairlayer.Finally,weapplythesetoolstotwoexampleswhichexhibitthesymmetriesof2Dlattices.TheseexamplescanbeviewedasabstractionsofthebiologicalmodelrepresentedbytheaquaticfernSalvinia.