编译|未玖Nature,23May2024,VOL629,ISSUE8013《自然》2024年5月23日，第629卷，8013期天文学AstronomyThesolardynamobeginsnearthesurface太阳发电机效应始于太阳表面附近▲作者：GeoffreyM.Vasil,DanielLecoanet,KyleAugustson,KeatonJ.Burns,JeffreyS.Oishi,BenjaminP.Brown,etal.▲链接：https://www.nature.com/articles/s41586-024-07315-1▲摘要：太阳磁发电机效应周期具有独特模式：太阳黑子出现的传播区域位于纬度30°附近，每11年在赤道附近消失。此外，被称为扭转振荡的纵向流动与太阳黑子迁移密切相关，毫无疑问具有共同原因。与暗示这些现象深层起源的理论相反，日震学将低纬度扭转振荡精确定位于太阳外层的5~10%，即近太阳表面剪切层。在该区域内，向内增加的差动旋转与极向磁场耦合，强烈暗示了磁旋转不稳定性，这在吸积盘理论中很突出，在实验室中亦可观测。总之，这两个事实引出了一个普遍的问题：太阳发电机效应是否源于近太阳表面的不稳定性。研究组报告了强有力的肯定证据，与关注更深差旋层的传统模型形成鲜明对比。简单的分析估计表明，近太阳表面磁旋转不稳定性更好地解释了扭转振荡的时空尺度和推断的太阳内部磁场振幅。最先进的数值模拟证实了这些估计，并重现了半球磁流螺旋度定律。发电机效应产生于一个被充分理解的近太阳表面现象，这有助于对影响地球电磁基础设施的全磁周期和空间天气进行准确预测。▲Abstract：ThemagneticdynamocycleoftheSunfeaturesadistinctpattern:apropagatingregionofsunspotemergenceappearsaround30°latitudeandvanishesneartheequatorevery11?years.Moreover,longitudinalflowscalledtorsionaloscillationscloselyshadowsunspotmigration,undoubtedlysharingacommoncause.Contrarytotheoriessuggestingdeeporiginsofthesephenomena,helioseismologypinpointslow-latitudetorsionaloscillationstotheouter5–10%oftheSun,thenear-surfaceshearlayer.Withinthiszone,inwardlyincreasingdifferentialrotationcoupledwithapoloidalmagneticfieldstronglyimplicatesthemagneto-rotationalinstability,prominentinaccretion-disktheoryandobservedinlaboratoryexperiments.Together,thesetwofactspromptthegeneralquestion:whetherthesolardynamoispossiblyanear-surfaceinstability.Herewereportstrongaffirmativeevidenceinstarkcontrasttotraditionalmodelsfocusingonthedeepertachocline.Simpleanalyticestimatesshowthatthenear-surfacemagneto-rotationalinstabilitybetterexplainsthespatiotemporalscalesofthetorsionaloscillationsandinferredsubsurfacemagneticfieldamplitudes.State-of-the-artnumericalsimulationscorroboratetheseestimatesandreproducehemisphericalmagneticcurrenthelicitylaws.Thedynamoresultingfromawell-understoodnear-surfacephenomenonimprovesprospectsforaccuratepredictionsoffullmagneticcyclesandspaceweather,affectingtheelectromagneticinfrastructureofEarth.物理学PhysicsLithiumtantalatephotonicintegratedcircuitsforvolumemanufacturing可量产的钽酸锂光子集成电路▲作者：ChengliWang,ZihanLi,JohannRiemensberger,GrigoryLihachev,MikhailChuraev,WilKao,etal.▲链接：https://www.nature.com/articles/s41586-024-07369-1▲摘要：基于铌酸锂（LiNbO3）的电-光光子集成电路（PICs）已被证明具有高Pockels系数材料的巨大能力。这实现了互补金属-氧化物-半导体电压水平下工作的线性和高速调制器可用于数据中心通信、高性能计算和AI光子加速器等应用。然而，这种技术的工业应用受到单片晶圆高成本和有限晶圆尺寸的阻碍。高成本是由于在微电子领域的巨大投资推动了绝缘体上硅（SOI）光子学的采用，而在其他领域缺乏现有的高容量应用。研究组报道了由钽酸锂（LiTaO3）制成的低损耗PIC，LiTaO3已在商业上用于5G射频滤波器，因此可以低成本进行可扩展的制造，并且LiTaO3具有与LiNbO3相似甚至在某些情况下更优的性能。结果表明，使用基于深紫外（DUV）步进的制造工艺，LiTaO3可被蚀刻以创建低损耗（5.6dBm-1）PIC。他们演示了一种LiTaO3马赫-曾德尔调制器（MZM），其半波电压-长度积为1.9Vcm，电光带宽高达40GHz。与LiNbO3相比，LiTaO3具有极低的双折射率，可实现所有电信频段上的高密度电路和宽带操作。此外，该平台还支持生成孤子微梳。该工作为低成本和大批量的下一代光电PIC的可扩展制造铺平了道路。▲Abstract：Electro-opticalphotonicintegratedcircuits(PICs)basedonlithiumniobate(LiNbO3)havedemonstratedthevastcapabilitiesofmaterialswithahighPockelscoefficient.Theyenablelinearandhigh-speedmodulatorsoperatingatcomplementarymetal–oxide–semiconductorvoltagelevelstobeusedinapplicationsincludingdata-centrecommunications,high-performancecomputingandphotonicacceleratorsforAI.However,industrialuseofthistechnologyishinderedbythehighcostperwaferandthelimitedwafersize.Thehighcostresultsfromthelackofexistinghigh-volumeapplicationsinotherdomainsofthesortthatacceleratedtheadoptionofsilicon-on-insulator(SOI)photonics,whichwasdrivenbyvastinvestmentinmicroelectronics.Herewereportlow-lossPICsmadeoflithiumtantalate(LiTaO3),amaterialthathasalreadybeenadoptedcommerciallyfor5Gradiofrequencyfiltersandthereforeenablesscalablemanufacturingatlowcost,andithasequal,andinsomecasessuperior,propertiestoLiNbO3.WeshowthatLiTaO3canbeetchedtocreatelow-loss(5.6dBm-1)PICsusingadeepultraviolet(DUV)stepper-basedmanufacturingprocess.WedemonstrateaLiTaO3Mach–Zehndermodulator(MZM)withahalf-wavevoltage–lengthproductof1.9Vcmandanelectro-opticbandwidthofupto40GHz.IncomparisonwithLiNbO3,LiTaO3exhibitsamuchlowerbirefringence,enablinghigh-densitycircuitsandbroadbandoperationoveralltelecommunicationbands.Moreover,theplatformsupportsthegenerationofsolitonmicrocombs.Ourworkpavesthewayforthescalablemanufactureoflow-costandlarge-volumenext-generationelectro-opticalPICs.材料科学MaterialsScienceSelenium-alloyedtelluriumoxideforamorphousp-channeltransistors硒合金氧化碲助力非晶p沟道晶体管▲作者：AoLiu,Yong-SungKim,MinGyuKim,YoujinReo,TaoyuZou,TaesuChoi,etal.▲链接：https://www.nature.com/articles/s41586-024-07360-w▲摘要：与多晶半导体相比，非晶半导体提供了固有成本效益，易于加工和统一制造。传统的非晶氢化硅在电性能方面存在不足，亟需开发新材料。高迁移率非晶n型金属氧化物（如a-InGaZnO）的产生及其与薄膜晶体管（TFTs）的集成，推动了现代大面积电子器件和新一代显示器的进步。然而，寻找类似的p型对应物颇具挑战，阻碍了互补金属-氧化物-半导体技术和集成电路的进展。研究组介绍了一种非晶p型半导体的开创性设计策略，将高迁移率碲引入至非晶亚氧化碲基体，并展示了其在高性能、稳定的p沟道TFTs和互补电路中的应用。理论分析揭示了具有浅受主态的碲5p带的离域价带，可实现过量的空穴掺杂和输运。硒合金化抑制了空穴浓度，促进了p轨道的连接，实现了高性能的p沟道TFTs，其平均场效应空穴迁移率约为15cm2V-1s-1，开/关电流比为106~107，且在偏置应力和环境老化下具有晶圆级均匀性和长期稳定性。这项研究代表了以低成本和工业兼容的方式建立商业上可行的非晶p沟道TFT技术和互补电子设备的关键一步。▲Abstract：Comparedtopolycrystallinesemiconductors,amorphoussemiconductorsofferinherentcost-effective,simpleanduniformmanufacturing.TraditionalamorphoushydrogenatedSifallsshortinelectricalproperties,necessitatingtheexplorationofnewmaterials.Thecreationofhigh-mobilityamorphousn-typemetaloxides,suchasa-InGaZnO,andtheirintegrationintothin-filmtransistors(TFTs)havepropelledadvancementsinmodernlarge-areaelectronicsandnew-generationdisplays.However,findingcomparablep-typecounterpartsposesnotablechallenges,impedingtheprogressofcomplementarymetal–oxide–semiconductortechnologyandintegratedcircuits.Hereweintroduceapioneeringdesignstrategyforamorphousp-typesemiconductors,incorporatinghigh-mobilitytelluriumwithinanamorphoustelluriumsuboxidematrix,anddemonstrateitsuseinhigh-performance,stablep-channelTFTsandcomplementarycircuits.Theoreticalanalysisunveilsadelocalizedvalencebandfromtellurium5pbandswithshallowacceptorstates,enablingexcessholedopingandtransport.Seleniumalloyingsuppressesholeconcentrationsandfacilitatesthep-orbitalconnectivity,realizinghigh-performancep-channelTFTswithanaveragefield-effectholemobilityofaround15?ccm2V-1s-1andon/offcurrentratiosof106~107,alongwithwafer-scaleuniformityandlong-termstabilitiesunderbiasstressandambientageing.Thisstudyrepresentsacrucialstridetowardsestablishingcommerciallyviableamorphousp-channelTFTtechnologyandcomplementaryelectronicsinalow-costandindustry-compatiblemanner.电子工程ElectronicEngineeringFull-colour3Dholographicaugmented-realitydisplayswithmetasurfacewaveguides具有超表面波导的全彩3D全息增强现实显示器▲作者：ManuGopakumar,Gun-YealLee,SuyeonChoi,BrianChao,YifanPeng,JonghyunKim,etal.▲链接：https://www.nature.com/articles/s41586-024-07386-0▲摘要：新兴空间计算系统将数字信息无缝叠加在用户观察到的物理环境上，从而实现了娱乐、教育、通信和培训等各个领域的变革性体验。然而，由于增强现实（AR）显示器的光引擎投影光学元件体积庞大，且无法准确描绘虚拟内容的三维（3D）深度信号等因素，其广泛采用受到限制。研究组介绍了一种全息AR系统，使用反向设计的全彩超表面光栅、紧凑的色散补偿波导几何结构和人工智能驱动的全息算法的独特组合来克服这些挑战。这些元件是协同设计的，消除了空间光调制器和波导之间对庞大准直光学器件的需求，并以紧凑设备规格来呈现生动的全彩3DAR内容。为了通过该原型提供前所未有的视觉质量，研究组开发了一种融合物理精确的波导模型与相机反馈自动校准的学习组件的创新图像形成模型。这种独特的纳米光子超表面波导和人工智能驱动全息算法的联合设计代表了在紧凑可穿戴设备中创建视觉上引人注目的3DAR体验的重大进步。▲Abstract：Emergingspatialcomputingsystemsseamlesslysuperimposedigitalinformationonthephysicalenvironmentobservedbyauser,enablingtransformativeexperiencesacrossvariousdomains,suchasentertainment,education,communicationandtraining.However,thewidespreadadoptionofaugmented-reality(AR)displayshasbeenlimitedduetothebulkyprojectionopticsoftheirlightenginesandtheirinabilitytoaccuratelyportraythree-dimensional(3D)depthcuesforvirtualcontent,amongotherfactors.HereweintroduceaholographicARsystemthatovercomesthesechallengesusingauniquecombinationofinverse-designedfull-colourmetasurfacegratings,acompactdispersion-compensatingwaveguidegeometryandartificial-intelligence-drivenholographyalgorithms.Theseelementsareco-designedtoeliminatetheneedforbulkycollimationopticsbetweenthespatiallightmodulatorandthewaveguideandtopresentvibrant,full-colour,3DARcontentinacompactdeviceformfactor.Todeliverunprecedentedvisualqualitywithourprototype,wedevelopaninnovativeimageformationmodelthatcombinesaphysicallyaccuratewaveguidemodelwithlearnedcomponentsthatareautomaticallycalibratedusingcamerafeedback.Ouruniqueco-designofananophotonicmetasurfacewaveguideandartificial-intelligence-drivenholographicalgorithmsrepresentsasignificantadvancementincreatingvisuallycompelling3DARexperiencesinacompactwearabledevice.化学ChemistryObservationofapromethiumcomplexinsolution溶液中钷配合物的观测▲作者：DarrenM.Driscoll,FrankieD.White,SubhamayPramanik,JeffreyD.Einkauf,BruceRavel,DmytroBykov,etal.▲链接：https://www.nature.com/articles/s41586-024-07267-6▲摘要：镧系稀土金属在现代技术中普遍存在，但人们对第61号元素钷（Pm）的化学性质知之甚少，Pm是一种高度放射性且难以接近的镧系元素。尽管Pm很重要，但其在镧系元素的实验研究中罕有涉及，阻碍了人们对所谓镧系元素收缩现象的全面理解：这是通用化学教科书中引用元素周期表的一个基本方面。研究组证明了通过新合成的有机二甘醇酰胺配体在水溶液中可与147Pm放射性核素（半衰期为2.62年）稳定螯合。利用同步X射线吸收光谱和量子化学计算，研究了所得到的均配型PmIII配合物，确定了钷的配位结构和键距。这些基本见解使人们能够对一整套同构镧系元素配合物进行完整的结构研究，最终仅在实验观察的基础上捕获溶液中的镧系收缩。研究结果表明，在镧系元素系列开始时键缩短加速，这与二甘醇酰胺显示的分离趋势有关。在水环境中对放射性PmIII配合物的表征加深了人们对镧系元素内部行为以及f区元素化学和分离的理解。▲Abstract：Lanthaniderare-earthmetalsareubiquitousinmoderntechnologies,butweknowlittleaboutchemistryofthe61stelement,promethium(Pm),alanthanidethatishighlyradioactiveandinaccessible.Despiteitsimportance,Pmhasbeenconspicuouslyabsentfromtheexperimentalstudiesoflanthanides,impedingourfullcomprehensionoftheso-calledlanthanidecontractionphenomenon:afundamentalaspectoftheperiodictablethatisquotedingeneralchemistrytextbooks.Herewedemonstrateastablechelationofthe147Pmradionuclide(half-lifeof2.62years)inaqueoussolutionbythenewlysynthesizedorganicdiglycolamideligand.TheresultinghomolepticPmIIIcomplexisstudiedusingsynchrotronX-rayabsorptionspectroscopyandquantumchemicalcalculationstoestablishthecoordinationstructureandabonddistanceofpromethium.Thesefundamentalinsightsallowacompletestructuralinvestigationofafullsetofisostructurallanthanidecomplexes,ultimatelycapturingthelanthanidecontractioninsolutionsolelyonthebasisofexperimentalobservations.Ourresultsshowacceleratedshorteningofbondsatthebeginningofthelanthanideseries,whichcanbecorrelatedtotheseparationtrendsshownbydiglycolamides.ThecharacterizationoftheradioactivePmIIIcomplexinanaqueousenvironmentdeepensourunderstandingofintra-lanthanidebehaviourandthechemistryandseparationofthef-blockelements.Boroncatalysisinadesignerenzyme人工酶中的硼催化作用▲作者：LarsLongwitz,ReubenB.Leveson-Gower,Henri?tteJ.Rozeboom,Andy-MarkW.H.Thunnissen&GerardRoelfes▲链接：https://www.nature.com/articles/s41586-024-07391-3▲摘要：酶在提高化工生产的友好性和效率方面发挥着越来越重要的作用，但由于酶的反应机理范围相对狭窄，其应用的多样性严重落后于化学催化剂。含有非生物功能酶的创造促进了自然界经典之外的反应机制，并为完全可编程的生物催化铺平了道路。研究组提出了一种完全遗传编码的含硼酸的人工酶，其有机催化活性是天然或工程生物催化剂无法实现的。这种硼酶通过肟形成催化羟基酮的动力学拆分，其中与蛋白质支架的关键相互作用有助于催化。定向进化运动导致了对几种不同底物具有天然酶样对映体选择性的变体。利用X射线晶体学、高分辨率质谱（HRMS）和11BNMR波谱证实了硼酶的独特活化模式。研究结果表明，遗传密码扩展可用于创建可进化的对映选择性酶，这些酶依赖于外源性催化部分，如硼酸和通过天然或人工酶的催化混杂性无法达到的通路反应机制。▲Abstract：Enzymesplayanincreasinglyimportantroleinimprovingthebenignityandefficiencyofchemicalproduction,yetthediversityoftheirapplicationslagsheavilybehindchemicalcatalystsasaresultoftherelativelynarrowrangeofreactionmechanismsofenzymes.Thecreationofenzymescontainingnon-biologicalfunctionalitiesfacilitatesreactionmechanismsoutsidenature’scanonandpavesthewaytowardsfullyprogrammablebiocatalysis.Herewepresentacompletelygeneticallyencodedboronic-acid-containingdesignerenzymewithorganocatalyticreactivitynotachievablewithnaturalorengineeredbiocatalysts.Thisboronenzymecatalysesthekineticresolutionofhydroxyketonesbyoximeformation,inwhichcrucialinteractionswiththeproteinscaffoldassistinthecatalysis.Adirectedevolutioncampaignledtoavariantwithnatural-enzyme-likeenantioselectivitiesforseveraldifferentsubstrates.TheuniqueactivationmodeoftheboronenzymewasconfirmedusingX-raycrystallography,high-resolutionmassspectrometry(HRMS)and11BNMRspectroscopy.Ourstudydemonstratesthatgenetic-codeexpansioncanbeusedtocreateevolvableenantioselectiveenzymesthatrelyonxenobioticcatalyticmoietiessuchasboronicacidsandaccessreactionmechanismsnotreachablethroughcatalyticpromiscuityofnaturalorengineeredenzymes.澳门新葡萄新京6663·「中国」官方网站-2024App Store！
