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Slice Thickness Optimization for the Focused Ion Beam-Scanning electron microscopy 3. Tomography of Hierarchical Nanoporous Gold

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Nanomanufacturing and Metrology 2022年第2期5卷 112-118页

作者： Alexander Shkurmanov Tobias Krekeler Martin Ritter electron microscopy Unit Hamburg University of Technology(TUHH)Eißendorfer Straße 4221073HamburgGermany

The combination of focused ion beam (FIB) with scanning electron microscopy (SEM), also known as FIB-SEM tomography, has become a powerful 3. imaging technique at the nanometer scale. This method uses an ion beam to mill away a thin slice of material, which is then block-face imaged using an electron beam. With consecutive slicing along the z-axis and subsequent imaging, a volume of interest can be reconstructed from the images and further analyzed. Hierarchical nanoporous gold (HNPG) exhibits unique structural properties and has a ligament size of 15–110 nm and pore size of 5–20 nm. Accurate reconstruction of its image is crucial in determining its mechanical and other properties. Slice thickness is one of the most critical and uncertain parameters in FIB-SEM tomography. For HNPG, the slice thickness should be at least half as thin as the pore size and, in our approach, should not exceed 10 nm. Variations in slice thickness are caused by various microscope and sample parameters, e.g., converged ion milling beam shape, charging effects, beam drift, or sample surface roughness. Determining and optimizing the actual slice thickness variation appear challenging. In this work, we examine the influence of ion beam scan resolution and the dwell time on the mean and standard deviation of slice thickness. After optimizing the resolution and dwell time to achieve the target slice thickness and lowest possible standard deviation, we apply these parameters to analyze an actual HNPG sample. Our approach can determine the thickness of each slice along the z-axis and estimate the deviation of the milling process along the y-axis (slow imaging axis). For this function, we create a multi-ruler structure integrated with the HNPG sample.

关键词： Focused ion beam Scanning electron microscopy Tomography Hierarchical nanoporous gold

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Revisit of the anisotropic vortex states of 2H-NbSe_(2) towards the zero-field limit

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Chinese Physics B 2024年第6期33卷 80-86页

作者：张凡侯兴元姜宇轩张宗源涂玉兵朱相德陈根富单磊 Beijing National laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Center of Free electron Laser and High Magnetic Field Anhui UniversityHefei 230601China Information Materials and Intelligent Sensing laboratory of Anhui Province Institutes of Physical Science and Information TechnologyAnhui UniversityHefei 230601China Key laboratory of Structure and Functional Regulation of Hybrid Materials in Anhui University Ministry of EducationHefei 230601China School of Physics and Materials Science Anhui UniversityHefei 230601China Anhui Key laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field LaboratoryHFIPSAnhuiChinese Academy of Sciencesand University of Science and Technology of ChinaHefei 230031China Hefei National laboratory Hefei 230088China

We revisited the vortex states of 2H-NbSe_(2) towards zero fields by a low-temperature scanning tunneling *** structures of the anisotropic vortex states were distinguished, one is a spatially non-splitting zero bias peak, and the other is an in-gap conductance anomaly resembling evolved crossing features around the center of the three nearest *** of them distribute solely along the next nearest neighboring direction of the vortex lattice and become unresolved in much higher magnetic fields, implying an important role played by the vortex–vortex interactions. To clarify these issues,we have studied the intrinsic vortex states of the isolated trapped vortex in zero fields at 0.45 K. It is concluded that the anisotropic zero bias peak is attributed to the superconducting gap anisotropy, and the spatially evolved crossing features are related to the vortex–vortex interaction. The vortex core size under the zero-field limit is determined. These results provide a paradigm for studying the inherent vortex states of type-II superconductors especially based on an isolated vortex.

关键词： vortex states zero-bias conductance peak scanning tunneling microscopy

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electron microscopy methods for space-, energy-, and time-resolved plasmonics

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Frontiers of physics 2017年第1期12卷 23-49页

作者： Arthur Losquin Tom T. A. Lummen Department of Physics Lund University P.O. Box 118 SE-22100 Lund Sweden laboratory for Ultrafast microscopy and electron Scattering ICMP Ecole Polytechnique Federale de Lausanne Station 6 CH-1015 Lausanne Switzerland

Nanoscale plasmonic systems combine the advantages of optical frequencies with those of small spatial scales, circumventing the limitations of conventional photonic systems by exploiting the strong field confinement of surface plasmons. As a result of this miniaturization to the nanoscale, electron microscopy techniques are the natural investigative methods of choice. Recent years have seen the development of a number of electron microscopy techniques that combine the use of electrons and photons to enable unprecedented views of surface plasmons in terms of combined spatial, energy, and time resolution. This review aims to provide a comparative survey of these different approaches from an experimental viewpoint by outlining their respective experimental domains of suitability and highlighting their complementary strengths and limitations as applied to plasmonics in particular.

关键词： plasmonics electron microscopy electron Energy Loss Spectroscopy (EELS) cathodoluminescence Photoemission electron microscopy (PEEM) Photo-Induced Near-field electron microscopy (PINEM) electron Energy Gain Spectroscopy (EEGS)

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Mapping carbon distribution in 3.SiMn steel by energy-filtered transmission electron microscopy

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Science China(Technological Sciences) 2012年第7期55卷 1833-1837页

作者： ZHONG XiaoYan ZHOU HuiHua WANG FengYing ZHU YueFeng Department of Materials Science and Engineering Beijing National Center for Electron MicroscopyLaboratory of Advanced MaterialsTsinghua UniversityBeijing 100084China Key laboratory for Advanced Materials Processing Technology Ministry of Education&Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

In this study,the three-windows method,the jump-ratio method and the R-map method in energy-filtered transmission electron microscopy(EFTEM) have been applied to mapping carbon distribution in 3.SiMn steel after a quenching-partitioning *** carbon contamination is successfully suppressed by using EFTEM and plasma-cleaning TEM *** to the three-windows method and the jump-ratio method,the R-map method provides carbon distribution with less noises,and is insensitive to changes in sample *** have demonstrated that the R-map method is a better way for carbon mapping in middle-carbon steel without the influence of carbon contamination.

关键词： carbon mapping distribution steel energy-filtered transmission electron microscopy

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The structure of HSV-1 gB bound to a potent neutralizing antibody reveals a conservative antigenic domain across herpesviruses

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hLife 2024年第3期2卷 141-146页

作者： Cong Sun Jia-Wen Yang Chu Xie Xin-Yan Fang Guo-Long Bu Ge-Xin Zhao Dan-Ling Dai Zheng Liu Mu-Sheng Zeng State Key laboratory of Oncology in South China Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and TherapyGuangdong Provincial Clinical Research Center for CancerSun Yat-sen University Cancer CenterGuangdongChina Cryo-electron microscopy Center Southern University of Science and TechnologyGuangdongChina Department of Biology Southern University of Science and TechnologyGuangdongChina

Human herpesviruses(HHV),including the alpha,beta,andgamma subfamilies,are enveloped viruses with broad prevalence,establishing life-time latent infections and inducing a variety of diseases[1].Among them,herpes simplex virus(HSV),consists of two HSV-1 and HSV-2 variants,ubiquitouslyaffecting global populations[2].As an enveloped virus,HSV features a repertoire of glycoproteins such as glycoproteins D(gD),glycoproteins H(gH),glycoproteins L(gL),and glycoproteins B(gB),to orchestrate host cell recognition and infection[3.4].

关键词： diseases neutral envelope

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Enhancing 3. Reconstruction Accuracy of FIB Tomography Data Using Multi‑voltage Images and Multimodal Machine Learning

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Nanomanufacturing and Metrology 2024年第1期7卷 48-60页

作者： Trushal Sardhara Alexander Shkurmanov Yong Li Lukas Riedel Shan Shi Christian J.Cyron Roland C.Aydin Martin Ritter Institute for Continuum and Material Mechanics Hamburg University of TechnologyHamburgGermany electron microscopy Unit Hamburg University of TechnologyHamburgGermany Institute of Materials Physics and Technology Hamburg University of TechnologyHamburgGermany Institute of Materials Mechanics Helmholtz-Zentrum HereonGeesthachtGermany Research Group of Integrated Metallic Nanomaterials Systems Hamburg University of TechnologyHamburgGermany Institute of Material Systems Modeling Helmholtz-Zentrum HereonGeesthachtGermany

FIB-SEM tomography is a powerful technique that integrates a focused ion beam(FIB)and a scanning electron microscope(SEM)to capture high-resolution imaging data of *** approach involves collecting in-plane SEM imagesand using FIB to remove material layers for imaging subsequent planes,thereby producing image ***,theseimage stacks in FIB-SEM tomography are subject to the shine-through effect,which makes structures visible from theposterior regions of the current *** artifact introduces an ambiguity between image intensity and structures in thecurrent plane,making conventional segmentation methods such as thresholding or the k-means algorithm *** study,we propose a multimodal machine learning approach that combines intensity information obtained at differentelectron beam accelerating voltages to improve the three-dimensional(3.)reconstruction of *** treatingthe increased shine-through effect at higher accelerating voltages as a form of additional information,the proposed methodsignificantly improves segmentation accuracy and leads to more precise 3. reconstructions for real FIB tomography data.

关键词： Multimodal machine learning Multi-voltage images FIB-SEM Overdeterministic systems 3. reconstruction FIB tomography

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Half a century after their discovery:Structural insights into exonuclease and annealase proteins catalyzing recombineering

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Engineering Microbiology 2024年第1期4卷 39-54页

作者： Lucy J.Fitschen Timothy P.Newing Nikolas P.Johnston Charles E.Bell Gökhan Tolun School of Chemistry and Molecular Bioscience and Molecular HorizonsUniversity of WollongongWollongongNSWAustralia The ARC Training Centre for Cryo-electron microscopy of Membrane Proteins University of WollongongWollongongNSWAustralia Faculty of Science University of Technology SydneyUltimoNSW 2007Australia Department of Biological Chemistry and Pharmacology The Ohio State University College of MedicineColumbusOH 43210

Recombineering is an essential tool for molecular biologists,allowing for the facile and efficient manipulation of bacterial genomes directly in cells without the need for costly and laborious in vitro manipulations involving restriction *** main workhorses behind recombineering are bacteriophage proteins that promote the single-strand annealing(SSA)homologous recombination pathway to repair double-stranded DNA *** there have been several reviews examining recombineering methods and applications,comparatively few have focused on the mechanisms of the proteins that are the key players in the SSA pathway:a 5′→3.exonuclease and a single-strand annealing protein(SSAP or“annealase”).This review dives into the structures and functions of the two SSA recombination systems that were the first to be developed for recombineering in ***:the RecET system from *** Rac prophage and the𝜆Red system from bacteriophageλ.By comparing the structures of the RecT and Red𝛽annealases,and the RecE and𝜆Exo exonucleases,we provide new insights into how the structures of these proteins dictate their *** the sequence conservation of the𝜆λExo and RecE exonucleases gives more profound insights into their critical functional ***,as recombineering accelerates and evolves in the laboratory,a better understanding of the mechanisms of the proteins behind this powerful technique will drive the development of improved and expanded capabilities in the future.

关键词： Recombineering Redβ λExo RecE RecT Protein structure Annealase Exonuclease

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LPA_(1) antagonist-derived LNPs deliver A20 mRNA and promote anti-fibrotic activities

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Nano Research 2024年第10期17卷 9095-9102页

作者： Jingyue Yan Diana D.Kang Chang Wang Xucheng Hou Shi Du Siyu Wang Yonger Xue Zhengwei Liu Haoyuan Li Yichen Zhong Binbin Deng David W.McComb Yizhou Dong Division of Pharmaceutics&Pharmacology College of PharmacyThe Ohio State UniversityColumbusOH 43210USA Icahn Genomics Institute Precision Immunology InstituteDepartment of Immunology and ImmunotherapyDepartment of Oncological SciencesTisch Cancer InstituteBiomedical Engineering and Imaging InstituteFriedman Brain InstituteIcahn School of Medicine at Mount SinaiNew YorkNY 10029USA Center for electron microscopy and Analysis The Ohio State UniversityColumbusOH 43212USA Department of Materials Science and Engineering The Ohio State UniversityColumbusOH 43210USA

Activated fibroblasts are major mediators of pulmonary *** are generally found in the connective tissue but upon activation can generate excess extracellular matrix(ECM)in the lung interstitial ***,fibroblasts are one of the most targeted cells for treating idiopathic pulmonary fibrosis(IPF).Here,we develop an anti-fibrotic platform that can modulate both the lysophosphatidic acid receptor 1(LPA_(1))and the inflammatory pathway through tumor necrosis factorα-induced protein 3.TNFAIP3.also known as A20)in ***,we synthesized a series of LPA_(1) antagonists,AM095 and AM966,derived amino lipids(LA lipids)which were formulated into LA-lipid nanoparticles(LA-LNPs)encapsulating ***,LA5-LNPs,with AM966 head group and biodegradable acetal lipid tails,showed efficient A20 mRNA delivery to lung fibroblasts in vitro(80.2%±1.5%)and ex vivo(17.2%±0.4%).When treated to primary mouse lung fibroblasts(MLF),this formulation inhibited fibroblast migration and collagen production,thereby slowing the progression of ***,LA5-LNPs encapsulated with A20 mRNA is a novel platform offering a potential approach to regulate fibroblast activation for the treatment of IPF.

关键词： lysophosphatidic acid receptor 1(LPA_(1))antagonist tumor necrosis factorα-induced protein 3.A20) lung fibrosis lipid nanoparticles mRNA

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Annealing-induced long-range charge density wave order in magnetic kagome FeGe:Fluctuations and disordered structure

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 112-121页

作者： Chenfei Shi Yi Liu Bishal Baran Maity Qi Wang Surya Rohith Kotla Sitaram Ramakrishnan Claudio Eisele Harshit Agarwal Leila Noohinejad Qian Tao Baojuan Kang Zhefeng Lou Xiaohui Yang Yanpeng Qi Xiao Lin Zhu-An Xu Arumugam Thamizhavel Guang-Han Cao Sander Van Smaalen Shixun Cao Jin-Ke Bao Department of Physics Materials Genome InstituteInstitute for Quantum Science and TechnologyShanghai UniversityShanghai 200444China Key laboratory of Quantum Precision Measurement of Zhejiang Province School of PhysicsZhejiang University of TechnologyHangzhou 310023China School of Physics Zhejiang UniversityHangzhou 310027China Department of Condensed Matter Physics and Materials Science Tata Institute of Fundamental ResearchMumbai 400005India School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China ShanghaiTech laboratory for Topological Physics ShanghaiTech UniversityShanghai 201210China laboratory of Crystallography University of BayreuthBayreuth 95447Germany Department of Quantum Matter AdSEHiroshima UniversityHigashi-Hiroshima 739-8530Japan P24 PETRA IIIDeutsches Elektronen-Synchrotron DESYHamburg 22607Germany Key laboratory for Quantum Materials of Zhejiang Province School of ScienceWestlake UniversityHangzhou 310024China Department of Physics China Jiliang UniversityHangzhou 310018China Shanghai Key laboratory of High-resolution electron microscopy ShanghaiTech UniversityShanghai 201210China Collaborative Innovation Centre of Advanced Microstructures Nanjing UniversityNanjing 210093China Shanghai Key laboratory of High Temperature Superconductors Shanghai UniversityShanghai 200444China School of Physics Hangzhou Normal UniversityHangzhou 311121China

Charge density wave(CDW) in kagome materials with the geometric frustration is able to carry unconventional ***, a CDW has been observed below the antiferromagnetic order in kagome FeGe, in which magnetism and CDW are intertwined to form an emergent quantum ground state. However, the CDW is only short-ranged and the structural modulation originating from it has yet to be determined experimentally. Here we realize a long-range CDW order by post-annealing process,and resolve the structure model through single crystal X-ray diffraction. Occupational disorder of Ge resulting from short-range CDW correlations above T_(CDW) is identified from structure refinements. The partial dimerization of Ge along the c axis is unveiled to be the dominant distortion for the CDW. Occupational disorder of Ge is also proved to exist in the CDW phase due to the random selection of partially dimerized Ge sites. Our work provides useful insights for understanding the unconventional nature of the CDW in FeGe.

关键词： charge density wave kagome disordered structure fluctuations

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What Can Topology Bring to Chemistry?

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CCS Chemistry 2024年第9期6卷 2084-2109页

作者： Wei Wang Songtao Zhou Xiujun Yu Qing-Hui Guo Yanhang Ma Jie Song Liang Zhang Xuzhou Yan Lu Han Qing Liao Xiaopeng Li Wen-Bin Zhang Yiyong Mai Shaodong Zhang Shunai Che Hai-Bo Yang Xuefeng Fu Mei-Xiang Wang School of Chemistry and Molecular Engineering East China Normal UniversityShanghai 200062 Hangzhou Institute of Medicine Chinese Academy of SciencesHangzhou 310022Zhejiang College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060Guangdong MOE Key laboratory of Bioorganic Phosphorous and Chemical Biology Department of ChemistryTsinghua UniversityBeijing 100084 School of Physical Science and Technology and Shanghai Key laboratory of High-Resolution electron microscopy ShanghaiTech UniversityShanghai 201210 School of Chemistry and Chemical Engineering Frontiers Science Center for Transformative MoleculesState Key Laboratory of Composite MaterialsShanghai Key Laboratory for Molecular Engineering of Chiral DrugsShanghai Jiao Tong UniversityShanghai 200240 School of Chemical Science and Engineering Tongji UniversityShanghai 200092 Beijing Key laboratory for Optical Materials and Photonic Devices Department of ChemistryCapital Normal UniversityBeijing 100048 Beijing National laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of EducationCenter for Soft Matter Science and EngineeringCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871 Department of Chemical Sciences National Natural Science Foundation of ChinaBeijing 10085

The unique mathematical perspectives and principal concepts of topology have not only promoted the development of other branches of mathematics but have also deeply influenced other subjects,particularly physics and *** minireview aims to elucidate the substantial influence of topology on chemistry by critically examining both the contributions of topology to current chemical science and its potential future *** will discuss the topology of molecular structures and assemblies across various scales—from small molecules and mechanically interlocked molecules to polymers,biomacromolecules,and supramolecular *** discussion will include an exploration of cutting-edge techniques for characterizing topological features,underscoring the role of topology as a novel paradigm for the design and synthesis of new molecular ***,a critical analysis of topology’s role in the development of functional materials—such as photonic materials,polymers,biomacromolecules,and chiral materials—will demonstrate its emerging significance as a crucial parameter in unveiling novel properties and *** topology’s formidable potential,it is anticipated to be used increasingly to address pivotal challenges within chemistry and adjacent disciplines.

关键词： chemical topology topological invariants molecular graphs links and knots structureproperty relationship

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