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  <xsd:element abstract="true" id="flks_NonvestedRestrictedCommonStockIssuedUponEarlyExerciseOfOptionsMember" name="NonvestedRestrictedCommonStockIssuedUponEarlyExerciseOfOptionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="flks_ProceedsFromSaleOfRestrictedCommonStock" name="ProceedsFromSaleOfRestrictedCommonStock" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="flks_ProceedsfromEarlyExerciseofStockOptions" name="ProceedsfromEarlyExerciseofStockOptions" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="flks_PropertyAndEquipmentPurchasesInAccruedExpense" name="PropertyAndEquipmentPurchasesInAccruedExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="flks_RevenueRecognitionRefundPeriod" name="RevenueRecognitionRefundPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
</xsd:schema>