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  <xs:element id="flks_SecuritiesSalesATMAgreementMember" abstract="true" name="SecuritiesSalesATMAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="flks_SeriesAPreferredStockAndSeriesBPreferredStockMember" abstract="true" name="SeriesAPreferredStockAndSeriesBPreferredStockMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="flks_PreFundedWarrantsMember" abstract="true" name="PreFundedWarrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="flks_SeriesAWarrantsMember" abstract="true" name="SeriesAWarrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="flks_SeriesBWarrantsMember" abstract="true" name="SeriesBWarrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="flks_PreFundedWarrantsSeriesAWarrantsAndSeriesBWarrantsMember" abstract="true" name="PreFundedWarrantsSeriesAWarrantsAndSeriesBWarrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="flks_StockIssuedDuringPeriodSharesAcquisitionsReserved" abstract="false" name="StockIssuedDuringPeriodSharesAcquisitionsReserved" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="flks_BusinessCombinationIssuedAndReservedShares" abstract="false" name="BusinessCombinationIssuedAndReservedShares" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="flks_SaleOfStockOptionPeriod" abstract="false" name="SaleOfStockOptionPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
</xs:schema>
