Cassini observations of Saturn provide the most extensive dataset available to characterize the atmosphere of any giant planet.I will celebrate the 20th anniversary of Cassini orbit insertion at Saturn(July 1)by presenting results based on the analysis of observations of the middle and upper atmosphere obtained by the UVIS and CIRS instruments during the last two years of the Cassini mission in 2016-2017.These results provide asnapshot of the middle and upper atmosphere around the northern summer solstice,including apole-to-pole map of temperatures as well as the distribution of methane and its photochemical products.They provide evidence that the seasonal circulation pattern in the stratosphere penetrates to the thermosphere and allow us,for the first time,infer neutral wind speeds in the upper atmosphere.The retrieved temperatures and winds also demonstrate the importance auroral electrodynamics and heating in controlling both the dynamics and energy balance of the thermosphere.They indicate that polar auroral heating followed by redistribution of energy to lower latitudes(stirring),enabled by momentum deposition by gravity waves and other sources of drag(shaking),is afeasible mechanism to explain the higher than expected temperatures in the thermosphere and therefore to solve the long-standing“energy crisis”on Saturn.Given the similarity of the subsequently observed temperatures on Jupiter,the same mechanism may also explain the temperatures observed in Jupiter’s thermosphere.Finally,we conclude by providing preliminary estimates of what is required to explain the observed temperatures in the upper atmosphere of Uranus,as afirst step towards apossible common mechanism to explain the higher than expected upper atmosphere temperatures on the giant planets. 查看详细>>

6月26日，浙江大学与中国机械工业集团有限公司（简称国机集团）在北京签署战略合作框架协议。浙江大学党委书记任少波、校长杜江峰院士与国机集团党委书记、董事长张晓仑出席见证签约。国机集团是中央直接管理的国有重要骨干企业，是国际化的综合性装备工业集团，连续多年位居中国机械工业百强首位。双方签署战略合作框架协议将进一步深化在高层次人才引育、联合开展核心技术研究、促进科技成果转移转化、专业学位研究生联合培养等领域的务实合作。浙江大学副校长黄先海与国机集团党委常委、副总经理、总工程师陈学东院士代表双方签署协议。浙江大学杨华勇院士、任其龙院士、郑津洋院士和校发展委员会副主任应义斌以及国机集团董事、党委副书记丁宏祥，相关部门负责人共同见证签约。签约仪式前，浙大一行还参观了国机集团展厅，了解集团整体建设发展情况。双方围绕学科建设、人才培养、科研合作深入交流，谋划未来合作发展。 查看详细>>

An Engineering research team led by Professor Yue Chen from the Department of Mechanical Engineering at the University of Hong Kong(HKU)has achieved aremarkable milestone in the realm of thermal transport in crystals.The research highlights the potential of simple crystal structures to achieve low thermal conductivity.This discovery not only underscores the importance of exploring new materials for applications in thermal insulation and thermoelectrics but also calls for further experimental investigations to expand the repertoire of materials with ultralow thermal conductivity.Traditionally,efforts to lower the lattice thermal conductivity of materials have focused on complex material systems,where lower thermal conductivity is typically observed.However,the pursuit of simple crystals with ultralow thermal conductivity has proven to be achallenging task.In their research,the team identified an exceptional candidate,AgTlI2,which defies conventional expectations by exhibiting an extraordinarily low thermal conductivity of 0.25 W/mK at room temperature—a rarity among simple crystals.Through acombination of state-of-the-art experimental techniques,including X-ray diffraction experiments and ab initio molecular dynamics simulations,coupled with advanced anharmonic lattice dynamics,the team gained comprehensive insights into the complex thermal transport mechanisms of AgTlI2 at room temperature.Their findings revealed acoexistence of ultralow particle-like and wavelike phonon thermal transports in AgTlI2,elucidating the underlying nature of its ultralow thermal conductivity.Moreover,leveraging their understanding of thermal transport in AgTlI2,the team proposed an effective alternative approach for identifying other simple materials with ultralow thermal conductivity,promising to expand the repertoire of materials with strongly suppressed thermal transport.This interdisciplinary study was conducted in collaboration with Professor Emmanuel Guilmeau‘s team from CRISMAT at Normandie University in France,Professor Zheyong Fan‘s team from Bohai University,China,and Professor Pierric Lemoine from Institute Jean Lamour,France.The collaborative effort allowed for the integration of expertise from multiple research groups,including sample preparation,synchrotron X-ray scattering,low-temperature thermal conductivity measurement,and ab initio simulations.“The discovery of the ultralow thermal conductivity of AgTlI2 is aresult of acombined effort of both theorists and experimentalists.”the first author of the paper,Dr Zezhu Zeng,expressed.He is currently aPost-doctoral Fellow in Professor Geoff Thornton‘s group at University College London and Professor Bingqing Cheng‘s group at University of California,Berkeley and Institute of Science and Technology,Austria.Dr Xingchen Shen from CRISMAT at French National Center for Scientific Research(CNRS)also contributed as aco-first author.“This work implies the important role of simple crystals on thermal insulation,paving the way for new research directions.”said Professor Chen.The findings have been published in the scientific journal Nature Communications with the title“Pushing thermal conductivity to its lower limit in crystals with simple structures”. 查看详细>>

DALLAS–June 25,2024–Patients with moderate to severe treatment-resistant depression(TRD)might have better symptom relief from ketamine infusions than from electroconvulsive therapy(ECT),but those with severe TRD could benefit more from ECT early in treatment,an analysis led by aUT Southwestern Medical Center researcher shows.The findings,published in JAMA Network Open,are the first to identify characteristics that distinguish which treatments might benefit TRD patients more.“Patients with TRD and their physicians can incorporate these findings in their shared decision-making process when selecting between ketamine and ECT,”said first author Manish Jha,M.D.,Associate Professor of Psychiatry and an O’Donnell Clinical Neuroscience Scholar at UT Southwestern.Dr.Jha is also an Investigator in the Peter O’Donnell Jr.Brain Institute.Previous studies have suggested that up to athird of adults with major depressive disorder have TRD,meaning they haven’t experienced adequate improvement with two or more courses of antidepressants.For decades,doctors have treated TRD patients with ECT,which delivers ajolt of electricity to the brain.More recently,ketamine–a drug historically used as an anesthetic–has also been used to treat TRD.In astudy known as the ELEKT-D clinical trial that published last year in the New England Journal of Medicine and was led by Amit Anand,M.D.,Professor of Psychiatry at Harvard Medical School,Dr.Jha and his colleagues showed that ECT and ketamine produced comparable results in agroup of 403 patients with TRD at five U.S.medical centers.However,it was unclear whether patients’baseline characteristics could predict which would be more beneficial.So Dr.Jha and research colleagues across the U.S.analyzed ELEKT-D’s results in asubgroup of 365 patients–195 had received up to six ketamine infusions over three weeks,and 170 had received up to nine ECT treatments over three weeks.Twice weekly during the treatment phase and at one follow-up after their treatments ended,these patients filled out aquestionnaire designed to assess their depression symptoms.The questionnaire was developed by former UTSW physician-researcher A.John Rush,M.D.,Professor Emeritus at the Duke-NUS Medical School at the National University of Singapore,and Madhukar Trivedi,M.D.,Professor of Psychiatry,Chief of the Division of Mood Disorders,and founding Director of the Center for Depression Research and Clinical Care at UT Southwestern.The patients also were assessed with aclinician-administered diagnostic tool.In addition,they underwent evaluations assessing various demographic and clinical characteristics,such as age,sex,concurrent use of other treatments,cognitive function,and whether they were being treated for their depression as an inpatient or outpatient.When the researchers compared the patients’symptom assessments over three weeks with their demographic and clinical characteristics,they found that patients were most likely to benefit from ketamine if they had moderate to severe overall depression at baseline or were receiving treatments as outpatients.Patients with very severe depression or who received their treatments as inpatients had more benefit early in their treatment course from ECT.However,by their last appointment,patients with these characteristics who received ketamine had similar outcomes. 查看详细>>

Cyclodextrins(CDs),a class of cyclic oligosaccharides that were“born”in 1891,have opened up endless research and commercial opportunities in numerous fields that span carbohydrate,supramolecular(host-guest)and analytical chemistry all the way from research laboratories in academia to the mass production of products—e.g.,skin care enablers to drug delivery systems—in industry.Although they have been known for over 130 years,the most accessible cyclic homologues areα-,β-,andγ-CDs,which contain six,seven,and eight D-glucopyranosyl units,respectively.The odyssey of naturally occurring CDs suggests that despite the number of CDs is rather limited,their reach has been limitless.For along time,scientists(chemists,biologists,medical scientists,etc)have been exploring novel methods to synthesise—both chemically and enzymatically—CD homologues.These efforts include the syntheses of unusual smaller analogues with only 3,4,and 5D-glucose units and the making of rare larger CDs with 9to 12 D-glucose units.All the currently available CDs are composed solely of D-glucopyranosyl units as the monomers,while the syntheses of mirror-image CDs have remained an untouched goal of the CD community,limiting the realisation of their full potential,such as in the development of new supramolecular sensors and catalysts,chiral materials,as well as innovative drug delivery systems and active pharmaceutical ingredients.In order to fulfil this fundamental research niche,a collaborative research team led by Professor Sir Fraser STODDART in the Department of Chemistry of The University of Hong Kong(HKU)and Professor Daniel ARMSTRONG in the Department of Chemistry and Biochemistry of The University of Texas at Arlington,recently developed aconcise approach to link L-glucopyranosyl monosaccharides together in ahighly diastereoselective and scalable manner,resulting in the production of circa half-gram quantities ofα-,β-,andγ-L-CDs.The availability of L-CDs for the first time—ever since the serendipitous discovery of their natural counterparts back in 1891—has enabled the elucidation of an unprecedented chiral self-sorting of aracemic modification ofβ-CDs in the solid state and an investigation of the chiral recognition of enantiomeric guests byα-L-CD in water.The research work was recently published and featured on the Cover in aleading scientific journal–Nature Synthesis.A corresponding News&Views Article written by Professor Sophie BEEREN,a cyclodextrin expert working at Technical University of Denmark,was also published in the same Journal(https://www.nature.com/articles/s44160-024-00512-w). 查看详细>>

6月17日，中国科学院与南京大学在京举行战略合作座谈会。中国科学院院长、党组书记侯建国，南京大学党委书记谭铁牛出席并讲话；中国科学院副院长、党组成员汪克强与南京大学校长谈哲敏签署战略合作备忘录。会议期间，中国科学院大气物理所、自动化所、上海药物所、紫金山天文台、苏州医工所、深圳先进院、西北研究院、青海盐湖所等8家相关院属单位与南京大学签署了8项相关领域合作协议。 查看详细>>

近日，南方科技大学理学院化学系副教授刘柳团队在双亲性主族元素多重键化学领域取得重要进展。研究成果以“一例晶态的锡炔（A Crystalline Stannyne）”为题，发表在《自然化学》（Nature Chemistry）杂志上。该成果通过取代基的π供电子效应和空间保护，合成了一种双亲性锡炔分子（R1−C≡Sn−R2↔R1−C(:)−Sn(:)−R2）。这类分子的分离表征扩展了人们对元素化学的认知，推动了双亲性（ambiphilicity；既亲核也亲电）主族元素化学的发展。新型主族元素结构基元的创制对合成化学、药物化学以及材料科学等多个领域的发展至关重要。大多数过渡金属具有部分占据的d电子，价层轨道既亲核也亲电，和小分子发生较强的相互作用。不同于过渡金属元素，主族元素的非价层电子是完全填充的，这一特点使得主族元素化合物的化学活性直接与其价层电子的能级和分布有关，同时也受到原子半径和元素电负性的显著影响。然而，近期的研究揭示，低价态下的配位不饱和主族元素化合物展现出与过渡金属相似的前线轨道特性和化学行为。这些具有“类过渡金属”行为的主族元素化合物，其化学特性主要体现为双亲性。双亲性的主族分子不仅能够活化惰性小分子，还在催化和材料科学等领域展现了巨大的潜力。炔烃分子（R1−C≡C−R2）无法共振成两个双亲的卡宾中心（图1a）。然而，炔烃的重元素类似物与炔烃有着显著不同的电子结构。由于重元素中心孤对电子惰性以及最外层轨道半径匹配差等原因，削弱了其形成多重键，因此炔烃的重元素类似物具有邻位双亲性质（R1−E≡E−R2↔R1−E(:)−E(:)−R2;E=Si,Ge,Sn,Pb）。值得注意的是，自从1836年首次发现乙炔，异核的炔烃重元素类似物（R1−C≡E−R2↔R1−C(:)−E(:)−R2;E=Si,Ge,Sn,Pb）一直未被科学家突破（图1）。近期，课题组利用π电子“推拉”策略和大位阻取代基，稳定了双亲性锡炔分子（R1−C≡Sn−R2↔R1−C(:)−Sn(:)−R2）（图2），首次实现了相邻异核双亲元素中心的构建（图3a），解决了主族元素化学领域内的重要难题。核磁共振和理论计算均支持锡炔3为单线态化合物。其中锡炔最主要的共振式为3A联烯结构（图3b）。基于理论计算，作者发现锡炔的碳原子具有反电子态卡宾的性质。通过实验研究，作者探索了锡炔的反应化学。所有化合物均经过了核磁、晶体结构、高分辨质谱等表征（图4）。该研究填补了异核炔烃重元素类似物的空白，扩展了人们对重元素化学的认知。鉴于独特的电子性质，锡炔分子有望革新双亲性主族元素的发展。近年来，刘柳课题组一直致力于双亲性主族元素化学的研究。瞄准主族结构基元“0到1”的原始创新，就“如何稳定（多重）双亲性结构基元”这一核心科学问题，通过合理的设计，成功分离表征或原位构建了一系列双亲性主族化合物，深度探讨了这些新颖结构基元的化学性质以及潜在的应用前景。截至目前，课题组以南科大为通讯单位发表Science 1篇、Nat.Chem.1篇、Nat.Synth.1篇、Chem.1篇、CCS Chem.1篇、J.Am.Chem.Soc.7篇、Angew.Chem.Int.Ed.8篇。这些研究工作先后多次被ChemistryViews、Nat.Synth.、Chem.、Synfacts以Highlight或Preview进行介绍。 查看详细>>

6月13日下午，国家能源集团—西安交通大学共建能源创新联合研究院（创新中心）签约揭牌仪式暨成立大会举行。西安交通大学党委书记卢建军，国家能源集团董事、总经理、党组副书记余兵，党组成员、副总经理傅振邦，西安交大党委常委、常务副校长别朝红，国电电力党委书记、董事长唐坚等出席。活动由党委常委、副校长严俊杰主持。严俊杰在致辞中表示，西安交大在创新港深入实施“产教融合、协同育人”创新工程，持续推进教育科技人才一体化发展，国家能源集团具有显著的产业优势，希望双方开展务实合作，实现高水平互利共赢，为保障国家能源安全、落实“双碳”目标贡献力量。傅振邦宣布国家能源集团—西安交通大学联合研究院组织机构。他表示，联合研究院实行管理委员会领导下的院长负责制，下设4个创新研究中心。中心将组建国家能源集团“首席科学家（工程师）”等科技人才与西安交大有关专家教授组成的联合团队，共同推进产学研用协同创新和科技成果的转化及推广应用。西安交大科研院常务副院长邵金友、国家能源集团科技与信息化部主任周光华签署国家能源集团—西安交通大学能源创新联合研究院共建协议。卢建军、余兵、傅振邦、别朝红见证。卢建军、余兵、傅振邦、别朝红为联合研究院揭牌。化工学院党委书记苗晋英，国电电力党委书记、董事长唐坚为能源动力与化工创新研究中心揭牌；能动学院院长苏光辉、国家能源集团氢能事业部主任刘玮为氢能创新研究中心揭牌；机械学院副院长崔健磊，朔黄铁路公司党委书记、董事长兰力为能源运输创新研究中心揭牌；电气学院院长杨旭，龙源电力党委书记、董事长宫宇飞为新能源创新研究中心揭牌。联合研究院院长何深表示，研究院将牢记习近平总书记嘱托，在服务国家高水平能源科技自立自强上勇担重任，坚决执行落实管理委员会决策部署，加强统筹协调，服务科研创新，培养科技人才，为打造能源领域高水平战略科技力量和重要原创技术策源地贡献智慧。杨旭代表创新研究中心发言。他表示，创新研究中心拓展了新的科研方向，壮大了高水平人才队伍，开启了发展新篇章。将以此次合作为契机，加强科学研究和人才培养，力争取得更大成果和突破。余兵表示，成立联合研究院是贯彻落实党的二十大关于教育、科技、人才一体化部署的重大举措，对推进产学研深度融合、强化国家战略科技力量意义重大。西安交大历史底蕴厚，学科实力强，发展理念新，为国家建设作出了卓越贡献，国家能源集团致力于打造能源领域原创技术策源地，科技创新需求旺盛，与西安交大合作空间广阔。希望以此次成立联合研究院作为新的起点，强化协同共赢、协同共建、协同共创、协同共研，推动更多科技成果转化落地，培养能源领域各类优秀人才，培育发展新质生产力，携手为打造产学研一体化标杆、为推动国家能源高质量发展作出贡献。卢建军对联合研究院的成立表示祝贺。他指出，西安交大深入贯彻落实党的二十大精神和习近平总书记在新时代推动西部大开发座谈会上的重要讲话精神，不忘西迁初心，聚焦“四个面向”，依托创新港扎实推进“6352”工程，不断深化企业主导的“1121”产学研深度融合新模式，加快构建“四链”融合，推进教育、科技、人才“三位一体”协同融合发展。国家能源集团肩负着推动能源高质量发展的国家使命，希望校企双方在联合研究院平台上实现深度融合，完善运行管理，深化学科交叉，建强人才队伍。学校将全力支持联合研究院各项工作走深走实，携手国家能源集团将联合研究院建设成集科研攻关、成果孵化、人才培养等于一体的综合型创新驱动平台，在我国能源事业发展和强国建设、民族复兴伟业中作出新的更大贡献。 查看详细>>

Chemotherapy and other treatments that take down cancer cells can also destroy patients’immune cells.Every year,that leads tens of thousands of cancer patients with weakened immune systems to contract infections that can turn deadly if unmanaged.Doctors must strike abalance between giving enough chemotherapy to eradicate cancer while not giving so much that the patient’s white blood cell count gets dangerously low,a condition known as neutropenia.It can also leave patients socially isolated in between rounds of chemotherapy.Currently,the only way for doctors to monitor their patients’white blood cells is through blood tests.Now Leuko is developing an at-home white blood cell monitor to give doctors amore complete view of their patients’health remotely.Rather than drawing blood,the device uses light to look through the skin at the top of the fingernail,and artificial intelligence to analyze and detect when white blood cells reach dangerously low levels.The technology was first conceived of by researchers at MIT in 2015.Over the next few years,they developed aprototype and conducted asmall study to validate their approach.Today,Leuko’s devices have accurately detected low white blood cell counts in hundreds of cancer patients,all without drawing asingle drop of blood.“We expect this to bring aclear improvement in the way that patients are monitored and cared for in the outpatient setting,”says Leuko co-founder and CTO Ian Butterworth,a former research engineer in MIT’s Research Laboratory of Electronics.“I also think there’s amore personal side of this for patients.These people can feel vulnerable around other people,and they don‘t currently have much they can do.That means that if they want to see their grandkids or see family,they’re constantly wondering,‘Am Iat high risk?’”The company has been working with the Food and Drug Administration(FDA)over the last four years to design studies confirming their device is accurate and easy to use by untrained patients.Later this year,they expect to begin apivotal study that will be used to register for FDA approval.Once the device becomes an established tool for patient monitoring,Leuko’s team believes it could also give doctors anew way to optimize cancer treatment.“Some of the physicians that we have talked to are very excited because they think future versions of our product could be used to personalize the dose of chemotherapy given to each patient,”says Leuko co-founder and CEO Carlos Castro-Gonzalez,a former postdoc at MIT.“If apatient is not becoming neutropenic,that could be asign that you could increase the dose.Then every treatment could be based on how each patient is individually reacting.” 查看详细>>

近日，上海交通大学电子信息与电气工程学院感知科学与工程学院黄震宇团队在基于变换声学的降噪且通流应用方向取得重要进展，相关成果以“Meta-barriers for ventilated sound reduction via transformation acoustics”（通过变换声学实现通风隔音的超屏障）为题，以上海交通大学电子信息与电气工程学院为第一单位发表在International Journal of Mechanical Sciences上。研究背景大型动力装备的噪声控制不仅需要采用各种措施来降低声音，还需要确保噪声控制措施的实施对装备通流散热的影响尽可能小。在保持介质有效流动的同时阻断声波的传播是一个违反直觉的物理过程。根据经典波动力学，介质充当声波传播的载体，阻断声波会限制介质流动，从而影响通流散热性能。作为一个具体实用性的研究课题，学者们在解决降噪与通流散热之间的矛盾方面付出了巨大的努力。然而，现有的方案无法兼顾低频宽带声波抑制与高通量介质流动，无法满足大型动力装备的噪声控制需求。创新成果针对以上问题，黄震宇团队提出了一种基于变换声学的超屏障（Meta-barrier），用于实现低频宽带降噪，同时保持高通量介质流动。所提出的超屏障由内部空气核心和由具有高阻尼耗散的双负声学超材料制成的涂层组成。与传统屏障不同，超屏障具有远超过其实际尺寸的散射截面，使其能够在增强的阻挡效应之外提供相干干涉效应。而相干干涉效应则可直接降低由开孔辐射的声波辐射效率。此外，涂层中固有的材料阻尼在宽频范围内对超屏障的降噪性能具有积极影响。论文详细推导了超屏障的构成参数，并给出了超屏障与开孔之间的多重散射现象的理论描述。基于有限元数值模型，演示了在大放置距离和宽入射角的情况下超屏障的稳健降噪性能。制备的元屏障样件，具备75%的风速比，可以在500–1000Hz的频率范围内实现卓越的透射声衰减。这项工作对基于变换声学的无源声学装置的设计和开发具有极大的启发和推动作用。变换声学的基本原理是通过数学变换，通常为坐标变换，来设计声学材料或结构，从而实现对声波传播的控制。变换声学是一个跨学科的研究领域，它结合了数学、物理和工程学的知识，为声波的控制和应用提供了新的可能性。随着声学超材料技术的发展，变换声学有望在未来的声学研究和应用中发挥更大的作用。这项工作可视为基于变换声学的超屏障实现低频宽带降噪和高效通流应用的前奏。后续研究工作包括使用更多的单元组成层来构建双负声学超材料涂层以接近连续梯度阻抗，制造三维超屏障并在真实房间尺度进行试验验证，平面结构形式设计的超屏障以减少空间占用，并寻求更容易生产和更具成本效益的制造超屏障的技术以促进其实际应用。 查看详细>>