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  <xsd:element abstract="false" id="arct_RevenueRecognitionResearchActivitiesPeriod" name="RevenueRecognitionResearchActivitiesPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_ResearchFundingPaymentsReceived" name="ResearchFundingPaymentsReceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_DevelopmentAndOptionAgreementDate" name="DevelopmentAndOptionAgreementDate" nillable="true" substitutionGroup="xbrli:item" type="xbrli:dateItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_UpfrontLicenseFees" name="UpfrontLicenseFees" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_PercentageOfGlobalRightsReassumed" name="PercentageOfGlobalRightsReassumed" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_CollaborativeArrangementSharingPercentage" name="CollaborativeArrangementSharingPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_CollaborationAgreementTerminationDate" name="CollaborationAgreementTerminationDate" nillable="true" substitutionGroup="xbrli:item" type="xbrli:dateItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_PercentageOfCashPaymentsReceived" name="PercentageOfCashPaymentsReceived" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_PercentageOfConsiderationReceived" name="PercentageOfConsiderationReceived" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_RevenueRelatedToAmortizationOfUpfrontPayment" name="RevenueRelatedToAmortizationOfUpfrontPayment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_LaborReimbursementAndSublicenseRevenueRecognized" name="LaborReimbursementAndSublicenseRevenueRecognized" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_ShortTermDepositWeightedAverageInterestRate" name="ShortTermDepositWeightedAverageInterestRate" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_CertificatesOfDepositFairValueDisclosure" name="CertificatesOfDepositFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_CorporateDebtSecuritiesFairValueDisclosure" name="CorporateDebtSecuritiesFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRestrictedCash" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRestrictedCash" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_BusinessCombinationChargeToAdditionalPaidInCapital" name="BusinessCombinationChargeToAdditionalPaidInCapital" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_AmiserviceMember" name="AmiserviceMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_DebtInstrumentInterestOnlyRepaymentPeriod" name="DebtInstrumentInterestOnlyRepaymentPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_DebtInstrumentInterestOnlyRepaymentPeriodExtended" name="DebtInstrumentInterestOnlyRepaymentPeriodExtended" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_DebtInstrumentAmortizationPeriod" name="DebtInstrumentAmortizationPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_DebtInstrumentAmortizationPeriodForExtendedInterestOnlyPeriod" name="DebtInstrumentAmortizationPeriodForExtendedInterestOnlyPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_WesternAllianceBankMember" name="WesternAllianceBankMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_WarrantFeePayable" name="WarrantFeePayable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_PrepaymentFeePercentage" name="PrepaymentFeePercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_PrepaymentFeePercentageAfterAcceptingNewDrugApplicationsPriorToMaturity" name="PrepaymentFeePercentageAfterAcceptingNewDrugApplicationsPriorToMaturity" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_FeePayableUponRepayment" name="FeePayableUponRepayment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_PercentageOfFeeLiableOnPrincipalBalance" name="PercentageOfFeeLiableOnPrincipalBalance" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_PercentageRequiredToBeMaintainedInDepositAndInvestmentAccount" name="PercentageRequiredToBeMaintainedInDepositAndInvestmentAccount" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_AccruedInterestOnPromissoryNote" name="AccruedInterestOnPromissoryNote" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_ConversionOfStockConversionRatio" name="ConversionOfStockConversionRatio" nillable="true" substitutionGroup="xbrli:item" type="xbrli:pureItemType" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="arct_ArcturusIncMember" name="ArcturusIncMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_ShareBasedCompensationAwardTrancheFourMember" name="ShareBasedCompensationAwardTrancheFourMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_RestrictedCommonStockMember" name="RestrictedCommonStockMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_UnvestedRestrictedOrdinarySharesMember" name="UnvestedRestrictedOrdinarySharesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_StockIssuedDuringPeriodSharesSubjectToRepurchaseOption" name="StockIssuedDuringPeriodSharesSubjectToRepurchaseOption" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionRepurchasePeriodFromTerminationDate" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionRepurchasePeriodFromTerminationDate" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_NumberOfMilestonesAchieved" name="NumberOfMilestonesAchieved" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_UnvestedRestrictedStockShares" name="UnvestedRestrictedStockShares" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_SharesIssuedUponWarrantConversion" name="SharesIssuedUponWarrantConversion" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="arct_TwoThousandThirteenEquityIncentivePlanMember" name="TwoThousandThirteenEquityIncentivePlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_TwoThousandTenEquityIncentivePlanMember" name="TwoThousandTenEquityIncentivePlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_TwoThousandEighteenOmnibusInactivePlanMember" name="TwoThousandEighteenOmnibusInactivePlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_NonExecutiveOfficerMember" name="NonExecutiveOfficerMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_PerformanceBasedOptionsMember" name="PerformanceBasedOptionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_BoardOfMembersMember" name="BoardOfMembersMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableSubjectToRepurchaseConditionsNumber" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableSubjectToRepurchaseConditionsNumber" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_NumberOfBoardMembers" name="NumberOfBoardMembers" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_MaximumPercentageOfLikelihoodOfUncertainTaxPositionRecognizedToBeSustained" name="MaximumPercentageOfLikelihoodOfUncertainTaxPositionRecognizedToBeSustained" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_IncomeTaxesLineItems" name="IncomeTaxesLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_IncomeTaxesTable" name="IncomeTaxesTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_AlcobraIncorporationAndAlcobraLimitedMember" name="AlcobraIncorporationAndAlcobraLimitedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_DeferredTaxAssetsPropertyPlantAndEquipmentAndIntangibleAssets" name="DeferredTaxAssetsPropertyPlantAndEquipmentAndIntangibleAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_DeferredTaxLiabilitiesPropertyPlantAndEquipmentAndIntangibleAssets" name="DeferredTaxLiabilitiesPropertyPlantAndEquipmentAndIntangibleAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_OperatingLossCarryforwardsExpirationYear" name="OperatingLossCarryforwardsExpirationYear" nillable="true" substitutionGroup="xbrli:item" type="xbrli:gYearItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_NetOperatingLossExcludedFromDeferredTaxAssets" name="NetOperatingLossExcludedFromDeferredTaxAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="false" id="arct_TaxCreditCarryforwardExpirationYear" name="TaxCreditCarryforwardExpirationYear" nillable="true" substitutionGroup="xbrli:item" type="xbrli:gYearItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_NetOperatingLossAndResearchAndDevelopmentCreditCarryforwardsLimitationsOnCumulativeChangeInOwnershipMinimumPercentage" name="NetOperatingLossAndResearchAndDevelopmentCreditCarryforwardsLimitationsOnCumulativeChangeInOwnershipMinimumPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_NetOperatingLossAndResearchAndDevelopmentCreditCarryforwardsLimitationsOnCumulativeChangeInOwnershipPeriod" name="NetOperatingLossAndResearchAndDevelopmentCreditCarryforwardsLimitationsOnCumulativeChangeInOwnershipPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Percent" name="EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Percent" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_TaxCutsAndJobsActOf2017MeasurementPeriodAdjustmentIncomeTaxExpenseBenefit" name="TaxCutsAndJobsActOf2017MeasurementPeriodAdjustmentIncomeTaxExpenseBenefit" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateProvisionalIncomeTaxExpenseBenefit" name="TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateProvisionalIncomeTaxExpenseBenefit" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_GrantsReceived" name="GrantsReceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_CommitmentAndContingenciesLineItems" name="CommitmentAndContingenciesLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_CommitmentAndContingenciesTable" name="CommitmentAndContingenciesTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_CysticFibrosisFoundationTherapeuticsMember" name="CysticFibrosisFoundationTherapeuticsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_SanDiegoCaliforniaMember" name="SanDiegoCaliforniaMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="arct_OctoberTwoThousandAndSeventeenLeaseAmendmentMember" name="OctoberTwoThousandAndSeventeenLeaseAmendmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_LessorLeasingArrangementsOperatingLeasesExpirationPeriodYearAndMonth" name="LessorLeasingArrangementsOperatingLeasesExpirationPeriodYearAndMonth" nillable="true" substitutionGroup="xbrli:item" type="xbrli:gYearMonthItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="false" id="arct_LessorLeasingArrangementsOperatingLeasesExtendedLease" name="LessorLeasingArrangementsOperatingLeasesExtendedLease" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
</xsd:schema>