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Product Code:SAE AMS5524
Title:Steel, Corrosion and Heat-Resistant, Sheet, Strip and Plate, 18Cr - 13Ni - 2.5Mo (SAE 30316), Solution Heat Treated
Issuing Committee:Ams F Corrosion Heat Resistant Alloys Committee
Scope:This specification covers a corrosion and heat-resistant steel in the form of sheet, strip, and plate.These products have been used typically for parts requiring both corrosion and heat resistance up to 1600 掳F (871 掳C), but usage is not limited to such applications. At elevated temperatures, strength of this steel is slightly higher than, and oxidation resistance is similar to that of 18-8 type steels.Certain design and processing procedures may cause these products to become susceptible to stress-corrosion cracking; ARP1110 recommends practices to minimize such conditions.【英文标准名称】:StandardTestMethodforDeterminingDegreeofDeacetylationinChitosanSaltsbyProtonNuclearMagneticResonance(1HNMR)Spectroscopy
【原文标准名称】:用质子核磁共振(1HNMR)光谱法测定脱乙酰壳多糖盐的脱乙酰作用程度的标准试验方法
【标准号】:ASTMF2260-2003(2008)
【标准状态】:现行
【国别】:美国
【发布日期】:2003
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:F04.42
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:Chitosansalts;Deacetylation;GlcNAc;Nuclearmagneticresonance(NMR)spectrometry;TEMPs(tissueengineeredmedicalproducts)
【摘要】:Thedegreeofdeacetylationofchitosansaltsisanimportantcharacterizationparametersincethechargedensityofthechitosanmoleculeisresponsibleforpotentialbiologicalandfunctionaleffects.Thedegreeofdeacetylation(%DA)ofwater-solublechitosansaltscanbedeterminedby1Hnuclearmagneticresonancespectroscopy(1HNMR).SeveralworkershavereportedontheNMRdeterminationofchemicalcompositionandsequentialarrangementofmonomerunitsinchitinandchitosan.ThetestmethoddescribedisprimarilybasedontheworkofV?/span>rumetal.(1991),whichrepresentsthefirstpublicationonroutinedeterminationofchemicalcompositioninchitosansbysolutionstate1HNMRspectroscopy.Thistestmethodisapplicablefordeterminingthe%DAofchitosanchlorideandchitosanglutamatesalts.Itisasimple,rapid,andsuitablemethodforroutineuse.Quantitative1HNMRspectroscopyreportsdirectlyontherelativeconcentrationofchemicallydistinctprotonsinthesample,consequently,noassumptions,calibrationcurvesorcalculationsotherthandeterminationofrelativesignalintensityratiosarenecessary.Inordertoobtainwell-resolvedNMRspectra,depolymerizationofchitosanstoanumberaveragedegreeofpolymerization(DPn)of~15to30isrequired.Thisreducestheviscosityandincreasesthemobilityofthemolecules.Althoughthereareseveraloptionsfordepolymerizationofchitosans,themostconvenientprocedureisthatofnitrousaciddegradationindeuteratedwater.Thereactionisselective,stoichiometricwithrespecttoGlcN,rapid,andeasilycontrolled(Allanx0026;Peyron,1995).ThereactionselectivelycleavesafteraGlcN-residue,transformingitinto2,5-anhydro-D-mannose(chitose),consequently,depletionofGlcNafterdepolymerizationisexpected.Ontheotherhand,thechitoseunitdisplayscharacteristic1HNMRsignalstheintensityofwhichmaybeestimatedandutilizedinthecalculationof%DA,eliminatingtheneedforcorrectionfactors.Usingtheintensityofthechitosesignals,thenumberaveragedegreeofpolymerizationcaneasilybecalculatedasacontrolofthedepolymerization.Samplesareequilibratedandanalyzedatatemperatureof90x00B1;1x00B0;C.Elevatedsampletemperaturecontributestoreducingsampleviscosityandrepositionstheprotonsignalofresidualwatertoanareaoutsidethatofinterest.Whilesamplesarenotstoredat90x00B0;Cbutonlyanalyzedatthiselevatedtemperature,theNMRtubesshouldbesealedwithastoppertoavoidanyevaporation.AtasamplepH*of3.8-4.3(see6.1.5below),artifactualdeacetylationofthesampledoesnotoccurduringtheshortequilibrationandanalysistime.AgeneraldescriptionofNMRcanbefoundinx003C;761>oftheUSP24-NF19.1.1ThistestmethodcoversthedeterminationofthedegreeofdeacetylationinchitosanandchitosansaltsintendedforuseinbiomedicalandpharmaceuticalapplicationsaswellasinTissueEngineeredMedicalProducts(TEMPs)byhigh-resolutionprotonNMR(1HNMR).AguideforthecharacterizationofchitosansaltshasbeenpublishedasGuideF2103.1.2Thetestmethodisapplicablefordeterminingthedegreeofdeacetylation(%DA)ofchitosanchlorideandchitosanglutamatesaltsandisvalidfor%DAvaluesfrom50uptoandincluding99.Itissimple,rapid,andsuitableforroutineuse.KnowledgeofthedegreeofdeacetylationisimportantforanunderstandingofthefunctionalityofchitosansaltsinTEMPformulationsandapplications.Thistestmethodwillassistendusersinchoosing......
【中国标准分类号】:C10
【国际标准分类号】:71_040_50
【页数】:5P.;A4
【正文语种】:英语