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Automatic identification of crystal structures and interfaces via artificial-intelligence-based electron microscopy

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npj Computational Materials 2023年第1期9卷 489-499页

作者： andreas Leitherer Byung Chul Yeo christian H.Liebscher Luca M.Ghiringhelli The NOMAD Laboratory at the Fritz-Haber-Institut of the Max-Planck-Gesellschaft and IRIS-Adlershof of the Humboldt-Universität zu Berlin BerlinGermany Department of Energy Resources Engineering Pukyong National UniversityBusan 48513Republic of Korea Max-Planck-Institut für Eisenforschung 40237 DüsseldorfGermany Physics Department and IRIS Adlershof Humboldt-Universität zu BerlinBerlinGermany Present address:Department of Materials Science and Engineering Friedrich-Alexander Universität Erlangen-NürnbergErlangenGermany

Characterizing crystal structures and interfaces down to the atomic level is an important step for designing advanced materials.Modern electron microscopy routinely achieves atomic resolution and is capable to resolve complex arrangements of atoms with picometer precision.Here,we present AI-STEM,an automatic,artificial-intelligence based method,for accurately identifying key characteristics from atomic-resolution scanning transmission electron microscopy(STEM)images of polycrystalline materials.The method is based on a Bayesian convolutional neural network(BNN)that is trained only on simulated images.AI-STEM automatically and accurately identifies crystal structure,lattice orientation,and location of interface regions in synthetic and experimental images.The model is trained on cubic and hexagonal crystal structures,yielding classifications and uncertainty estimates,while no explicit information on structural patterns at the interfaces is included during training.This work combines principles from probabilistic modeling,deep learning,and information theory,enabling automatic analysis of experimental,atomic-resolution images.

关键词： materials crystal estimates

Lateral dipole moments induced by all-cis-pentafluorocyclohexyl groups cause unanticipated effects in self-assembled monolayers

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Nano Research 2023年第8期16卷 11030-11041页

作者： christian Fischer Saunak Das Qingzhi Zhang Yangbiao Liu Lothar Weinhardt David O’Hagan Michael Zharnikov andreas Terfort Institute of Inorganic and Analytical Chemistry Goethe University FrankfurtMax-von-Laue-Straße 760438 Frankfurt am MainGermany Applied Physical Chemistry Heidelberg UniversityIm Neuenheimer Feld 25369120 HeidelbergGermany School of Chemistry University of St AndrewsNorth HaughSt AndrewsFifeKY169STUK Institute for Photon Science and Synchrotron Radiation Karlsruhe Institute of Technology(KIT)Hermann-v.-Helmholtz-Platz 176344 Eggenstein-LeopoldshafenGermany Institute for Chemical Technology and Polymer Chemistry(ITCP) Karlsruhe Institute of Technology(KIT)Engesserstr.18/2076128 KarlsruheGermany Department of Chemistry and Biochemistry University of NevadaLas Vegas(UNLV)4505 Maryland ParkwayLas VegasNV 89154-4003USA

All-cis-hexafluoro-and all-cis-pentafluoro-cyclohexane(PFCH)derivatives are new kinds of materials,the structures and properties of which are dominated by the highly dipolar Janus-face motif.Here,we report on the effects of integrating the PFCH groups into self-assembled monolayers(SAMs)of alkanethiolates on Au(111).Monolayers with an odd(eleven)and even(twelve)number of methylene groups were characterized in detail by several complementary experimental tools,supported by theoretical calculations.Surprisingly,all the data show a high similarity of both kinds of monolayers,nearly lacking the typically observed odd-even effects.These new monolayers have a packing density about 1/3 lower than that of non-substituted alkanethiolate monolayers,caused by the bulkiness of the PFCH moieties.The orientations of the PFCH groups and the alkyl chains could be determined independently,suggesting a conformation similar to the one found in the solid state structure of an analogous compound.Although in the SAMs the PFCH groups are slightly tilted away from the surface normal with the axial fluorine atoms pointing downwards,most of the dipole moments of the group remain oriented parallel to the surface,which is a unique feature for a SAM system.The consequences are much lower water contact angles compared to other partly fluorinated SAMs as well as rather moderate work function values.The interaction between the terminal PFCH moieties results in an enhanced stability of the PFCH-decorated SAMs toward exchange reaction with potential molecular substituents in spite of the lower packing density of these films.

关键词： odd-even-effects work function self-assembled monolayer(SAM) kinetic stability infrared-reflection absorption spectroscopy X-ray photoelectron spectroscopy

Quasi-optimal control of a solar thermal system via neural networks✩

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能源与人工智能(英文)

能源与人工智能(英文) 2023年第2期12卷 128-144页

作者： Jana Friese Niklas Brandt andreas Schulte christian Kirches Wilhelm Tegethoff Jürgen Köhler Technische Universität braunschweig Institut für ThermodynamikHans–Sommer–Straße 538106 BraunschweigGermany Technische Universität braunschweig Institut für Mathematische OptimierungUniversitätsplatz 238106 BraunschweigGermany

The optimal control of complex thermal energy systems is a challenge due to their dynamic behavior andconstantly changing boundary conditions. To maximize the energy efficiency of such a dynamic system, optimaltrajectories for the controlled variables are needed. Extensive system knowledge is required to model the systemaccurately enough to be able to compute optimal trajectories. The high computational cost of computingoptimal control solutions with traditional approaches, especially with changing boundary conditions, oftenmakes this approach unusable for applications with limited computational power, such as real-time applicationson electronic control units (ECUs). This study investigates a possible solution to this challenge using a simplifiedexample system. Optimal control solutions for different boundary and initial conditions are generated forthe selected solar thermal system using a direct multiple shooting algorithm. Based on Bellman’s optimalityprinciple, the generated solutions are transformed into a data set of optimal state–action pairs. On this basis,different types of neural networks are trained, specifically a feed-forward, a recurrent, and a radial basisfunction network. Thus, data generation and training can be performed offline, and the required online computations are significantly reduced since the evaluation of a trained neural network requires comparatively lowcentral processing unit (CPU) power. The trained neural network controllers are tested for their ability to outputnear-optimal control actions based on the current system state. The feed-forward and recurrent neural networksshow promising initial results in this regard. Open questions and the need for improvements are discussed.

关键词： Optimal control Neural networks Bellmann equation Thermal systems Optimization

Optimized Three-Dimensional Cardiovascular Magnetic Resonance Whole Heart Imaging Utilizing Non-Selective Excitation and Compressed Sensing in Children and Adults with Congenital Heart Disease

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Congenital Heart Disease 2023年第3期18卷 279-294页

作者： Ingo Paetsch Roman Gebauer christian Paech Frank-Thomas Riede Sabrina Oebel andreas Bollmann christian Stehning Jouke Smink Ingo Daehnert Cosima Jahnke Department of Electrophysiology Heart Center Leipzig at University of LeipzigLeipzigGermany Department of Pediatric Cardiology Heart Center Leipzig at University of LeipzigLeipzigGermany Philips Research Laboratories HamburgGermany Philips Medical Systems BestThe Netherlands

Background:In congenital heart disease(CHD)patients,detailed three-dimensional anatomy depiction plays a pivotal role for diagnosis and therapeutical decision making.Hence,the present study investigated the applicability of an advanced cardiovascular magnetic resonance(CMR)whole heart imaging approach utilizing nonselective excitation and compressed sensing for anatomical assessment and interventional guidance of CHD patients in comparison to conventional dynamic CMR angiography.Methods:86 consecutive pediatric patients and adults with congenital heart disease(age,1 to 74 years;mean,35 years)underwent CMR imaging including a freebreathing,ECG-triggered 3D nonselective SSFP whole heart acquisition using compressed SENSE(nsWHcs).Anatomical assessability and signal intensity ratio(SIR)measurements were compared with conventional dynamic 3D-/4D-MR angiography.Results:The most frequent diagnoses were partial anomalous pulmonary venous drainage(17/86,20%),transposition of the great arteries(15/86,17%),tetralogy of Fallot(12/86,14%),and a single ventricle(7/86,8%).Image quality of nsWHcs was rated as excellent/good in 98%of patients.nsWHcs resulted in a reliable depiction of all large thoracic vessels(anatomic assessability,99%–100%)and the proximal segments of coronary arteries and coronary sinus(>90%).nsWHcs achieved a homogenously distributed SIR in all cardiac cavities and thoracic vessels without a significant difference between pulmonary and systemic circulation(10.9±3.5 and 10.6±3.4;p=0.15),while 3D angiography showed significantly increased SIR for targeted vs.non-targeted circulation(PA-angiography,15.2±8.1 vs.5.8±3.6,p<0.001;PV-angiography,7.0±3.9 vs.17.3±6.8,p<0.001).Conclusions:The proposed nsWHcs imaging approach provided a consistently high image quality and a homogeneous signal intensity distribution within the pulmonary and systemic circulation in pediatric patients and adults with a wide spectrum of congenital heart diseases.nsWHcs enabled detailed anatomical assessment and three-dimensional reconstruct

关键词： Cardiovascular magnetic resonance imaging congenital heart disease whole heart imaging nonselective SSFP compressed SENSE MR angiography

Treatment of clinical stage I non-seminoma

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Asian Journal of Urology 2021年第2期8卷 161-169页

作者： christian Winter andreas Hiester Department of Urology University of DuesseldorfMedical FacultyHeinrich-Heine-UniversityDuesseldorfGermany

Germ cell cancers are the most common solid tumors among men between 15 and 40 years.Non-seminomatous germ cell tumors(NSGCTs)represent a unique and exclusive cohort of germ cell tumor patients.Non-seminoma can harbor different histologic components.The most commonly found histologies are embryonal cell cancer,teratoma,yolk sack tumor and choriocarcinoma,as well as teratocarcinoma and seminoma,in combination with non-seminomatous germ cell tumors histologic types.The clinical definition of stage I nonseminoma is the absence of metastatic lesions on imaging and normal tumor markers.The cure rate for clinical stage I NSGCT is 99%and this can be achieved by three therapeutic strategies:Active surveillance with treatment at the time of relapse,retroperitoneal lymph node dissection or adjuvant chemotherapy.The balancing of these various strategies should always be based on an individual risk profile of NGSCG patient depending on the lymphovascular invasion of the tumor.

关键词： Germ cell tumors Non-seminomatous germ cell tumors Active surveillance Retroperitoneal lymph node dissection

Norton-Hoff model for deformation of growing solid shell of thin slab casting in funnel-shape mold

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Journal of Iron and Steel Research(International) 2022年第1期29卷 88-102页

作者： Alexander Vakhrushev Abdellah Kharicha Menghuai Wu andreas Ludwig Gerald Nitzl Yong Tang Gernot Hackl Josef Watzinger christian M.G.Rodrigues christian-Doppler Laboratory for Metallurgical Applications of Magnetohydrodynamics Montanuniversitat Leoben8700 LeobenAustria Primetals Technologies 4031 LinzAustria Chair of Simulation and Modeling of Metallurgical Processes Department of MetallurgyMontanuniversit?t Leoben8700 LeobenAustria RHI Magnesita GmbH 1120 ViennaAustria RHI Magnesita GmbH 8700 LeobenAustria

A funnel-type mold is commonly used to provide necessary clearance for the submerged entry nozzle in the thin slab casting(TSC).The partially solidified shell is subjected to the mechanical deformations,which can lead to the defects formation and,as a results,to a breakout.Traditionally,the results of the flow simulation,performed by the finite volume method(FVM),are fed to the external package for the finite element analysis of stress and strain.A coupled model was assembled using“creeping solid”approach by blending the Norton-Hoff viscoplastic stress for the solidifying shell with the Newtonian viscous stress of the liquid melt.The FVM was used to combine both liquid and solid stress models within a single solver.The iterative procedure based on the improved both side diffusion method was introduced to treat the nonlinear relation between the viscoplastic stress and the strain rate.The modeled shell thickness was verified by previously published breakout measurements and the simulation results.Temperature distribution,obtained during the TSC simulation,dominantly corresponds to the viscoplastic range.Developed numerical approach is robust and has direct industrial application.

关键词： Solid shell Viscoplastic stress Solidification Norton-Hoff model Thin slab Continuous casting Improved both side diffusion method OpenFOAM

Miniaturization of a coherent monocular structured illumination system for future combination with digital holography

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Light(Advanced Manufacturing) 2022年第3期3卷 160-167页

作者： andreas Walter Stark Eugene Wong Holger Babovsky christian Franke Richard Kowarschik Institute of Applied Optics and Biophysics Friedrich Schiller University Jena07743 JenaGermany University Hospital 07743 JenaGermany

Holographic and 3D-measurement processes are an often-used tool in industry,medicine,and scientific applications.While small deviations of objects can be visualized by holographic means with high accuracy,optical systems with active structured illumination are a reliable source of absolute 3D-information in these fields.The combination of digital holography with structured illumination allows to simultaneously measure deformations and absolute 3D coordinates but also requires coherent light and has already been demonstrated in principle with a stereo camera setup.Multi-camera systems are limited to certain setup sizes given by the volume and distance of the detectors.Reducing the system to a one-camera(monocular)setup reduces space and acquisition costs.By using a multi-aperture illumination source an extremely high projection rate could be realized and reduced to a monocular approach with a novel voxel-calibration technique,while the projection system itself still requires a large amount of space.In this paper we present a miniaturized,monocular 3D-measurement system that works with repeatable,coherent speckles,generated by a fiber-coupled laser whose light was distributed by a fiber-switch to a diffuser plate connected with a measurement-head,also including a camera.By addressing different fibers through the switch,varying but repeatable patterns are generated.The size of the device(diameter<3 cm)is now mainly limited by the volume of the camera.A first 3D-reconstruction of an object and an outlook for a combination of this system with digital holography is given,allowing absolute 3D-coordinates and relative deviations of object points to be measured simultaneously.

关键词： 3D-measurement Structured illumination Speckle projection Monocular 3D-measurement Combination 3D-measurment and holography

Systematic Cross-biospecimen Evaluation of DNA Extraction Kits for Long-and Short-read Multi-metagenomic Sequencing Studies

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Genomics, Proteomics & Bioinformatics 2022年第2期20卷 405-417页

作者： Jacqueline Rehner Georges Pierre Schmartz Laura Groeger Jan Dastbaz Nicole Ludwig Matthias Hannig Stefan Rupf Berthold Seitz Elias Flockerzi Tim Berger Matthias christian Reichert Marcin Krawczyk Eckart Meese christian Herr Robert Bals Soren L.Becker andreas Keller Rolf Muller The IMAGINE Consortium Institute of Medical Microbiology and Hygiene Saarland UniversityD-66421 HomburgGermany Clinical Bioinformatics Saarland UniversityD-66123 SaarbruckenGermany Department of Human Genetics Saarland UniversityD-66421 HomburgGermany Helmholtz Institute for Pharmaceutical Research Saarland D-66123 SaarbruckenGermany Clinic of Operative Dentistry Periodontology and Preventive DentistrySaarland UniversityD-66421 HomburgGermany Department of Ophthalmology Saarland University Medical CenterD-66421 HomburgGermany Department of Medicine Ⅱ Saarland University Medical CenterD-66421 HomburgGermany Department of Internal Medicine V–Pulmonology AllergologyIntensive Care MedicineSaarland UniversityD-66421 HomburgGermany

High-quality DNA extraction is a crucial step in metagenomic studies.Bias by different isolation kits impairs the comparison across datasets.A trending topic is,however,the analysis of multiple metagenomes from the same patients to draw a holistic picture of microbiota associated with diseases.We thus collected bile,stool,saliva,plaque,sputum,and conjunctival swab samples and performed DNA extraction with three commercial kits.For each combination of the specimen type and DNA extraction kit,20-gigabase(Gb)metagenomic data were generated using short-read sequencing.While profiles of the specimen types showed close proximity to each other,we observed notable differences in the alpha diversity and composition of the microbiota depending on the DNA extraction kits.No kit outperformed all selected kits on every specimen.We reached consistently good results using the Qiagen QiAamp DNA Microbiome Kit.Depending on the specimen,our data indicate that over 10 Gb of sequencing data are required to achieve sufficient resolution,but DNA-based identification is superior to identification by mass spectrometry.Finally,longread nanopore sequencing confirmed the results(correlation coefficient>0.98).Our results thus suggest using a strategy with only one kit for studies aiming for a direct comparison of multiple microbiotas from the same patients.

关键词： Whole-genome analysis Comparative genomics Short-read sequencing Long-read sequencing DNA extraction Metagenomics

Laser-Welded Steel Foils with Sapphire Substrates

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Acta Metallurgica Sinica(English Letters) 2016年第7期29卷 683-688页

作者： Araceli de Pablos-Martin christian Grosse andreas Cismak Thomas Hoche Fraunhofer Institute for Microstructure of Materials and Systems IMWS Walter-Htilse-Strage 1 06120 HalleGermany

A nanosecond pulsed laser was used to weld stainless steel foils of 10 ~tm thickness to the sapphire substrates. The microstructure of the bonded interface was studied. Both materials were partially ablated under the influence of the laser beam. An inhomogeneous distribution of the steel and sapphire along the bonded interface is observed. The electrical resistance of the steel foil was measured before and after laser welding, showing that the weld slightly increases the electrical resistance but still keeps the values acceptable for electrical contacts.

关键词： Laser welding Stainless steel Sapphire Electrical resistance