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  <xsd:element abstract="true" id="astm_ValuationAllowancesAndReservesPeriodDomain" name="ValuationAllowancesAndReservesPeriodDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="astm_ValuationAllowancesAndReservesPeriodRelatedTo2016Member" name="ValuationAllowancesAndReservesPeriodRelatedTo2016Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="astm_ValuationAllowancesAndReservesPeriodRelatedTo2017Member" name="ValuationAllowancesAndReservesPeriodRelatedTo2017Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="astm_WarrantsAndRightsNoteDisclosureTextBlock" name="WarrantsAndRightsNoteDisclosureTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="astm_WarrantsAndRightsRollForward" name="WarrantsAndRightsRollForward" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="astm_WarrantsIssuedDecember212017Member" name="WarrantsIssuedDecember212017Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="astm_WarrantsIssuedInAugust2013Member" name="WarrantsIssuedInAugust2013Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="astm_WarrantsIssuedInSeptember2016Member" name="WarrantsIssuedInSeptember2016Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="astm_WarrantsIssuedOnDecember72017Member" name="WarrantsIssuedOnDecember72017Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="astm_WarrantsPolicyTextBlock" name="WarrantsPolicyTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
</xsd:schema>