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  <xsd:element abstract="true" id="xbit_NoteToFinancialStatementDetailsTextual" name="NoteToFinancialStatementDetailsTextual" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_NotesToFinancialStatements" name="NotesToFinancialStatements" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_NotesToFinancialStatementsAbstract" name="NotesToFinancialStatementsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element id="xbit_OtherRelatedFeeAttributableToIssuanceOfCommonStock" name="OtherRelatedFeeAttributableToIssuanceOfCommonStock" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element id="xbit_PercentageOfOutstandingSharesRepurchased" name="PercentageOfOutstandingSharesRepurchased" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element id="xbit_ProceedsFromIssuanceOfCommonStockNet" name="ProceedsFromIssuanceOfCommonStockNet" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element id="xbit_ProceedsFromPaymentsForRepurchaseOfCommonStockAndWarrantsNet" name="ProceedsFromPaymentsForRepurchaseOfCommonStockAndWarrantsNet" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element id="xbit_SharesBuybackEquityImpactAmount" name="SharesBuybackEquityImpactAmount" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element id="xbit_StockRepurchaseProgramPurchasePricePerShare" name="StockRepurchaseProgramPurchasePricePerShare" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="instant"/>
  <xsd:element id="xbit_StockRepurchasedDuringPeriodPricePerShare" name="StockRepurchasedDuringPeriodPricePerShare" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration"/>
  <xsd:element id="xbit_SubscriptionReceivable" name="SubscriptionReceivable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_ThePlanMember" name="ThePlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="xbit_TransitionServicesAgreementMarkupPercentage" name="TransitionServicesAgreementMarkupPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant"/>
  <xsd:element id="xbit_TransitionServicesAgreementNumberOfOngoingClinicalTrialsEnteredInto" name="TransitionServicesAgreementNumberOfOngoingClinicalTrialsEnteredInto" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration"/>
  <xsd:element id="xbit_UnderwritersCommissionAttributableToIssuanceOfCommonStock" name="UnderwritersCommissionAttributableToIssuanceOfCommonStock" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_WinnebagoBuildingMember" name="WinnebagoBuildingMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-note-2-significant-accounting-policies-sharebased-compensation-expense-details" name="statement-statement-note-2-significant-accounting-policies-sharebased-compensation-expense-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-note-2-significant-accounting-policies-stock-option-valuation-assumptions-details" name="statement-statement-note-2-significant-accounting-policies-stock-option-valuation-assumptions-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-note-2-significant-accounting-policies-tables" name="statement-statement-note-2-significant-accounting-policies-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-note-4-property-and-equipment-property-and-equipment-net-details" name="statement-statement-note-4-property-and-equipment-property-and-equipment-net-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-note-4-property-and-equipment-tables" name="statement-statement-note-4-property-and-equipment-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-note-6-common-stock-options-changes-in-common-stock-options-issued-details" name="statement-statement-note-6-common-stock-options-changes-in-common-stock-options-issued-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-note-6-common-stock-options-tables" name="statement-statement-note-6-common-stock-options-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-note-7-net-income-loss-per-share-computation-of-basic-and-diluted-net-loss-per-share-details" name="statement-statement-note-7-net-income-loss-per-share-computation-of-basic-and-diluted-net-loss-per-share-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-note-7-net-income-loss-per-share-tables" name="statement-statement-note-7-net-income-loss-per-share-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="xbit_statement-statement-significant-accounting-policies-policies" name="statement-statement-significant-accounting-policies-policies" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
</xsd:schema>
