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Effect of wire-arc directed energy deposition on the microstructural formation and age-hardening response of the Mg-9Al-1Zn(AZ91)alloy

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Journal of Magnesium and Alloys 2023年第6期11卷 1944-1958页

作者： Gloria Graf Petra Spoerk-Erdely Emad Maawad Michael Burtscher Daniel Kiener helmut clemens Thomas Klein Department of Materials Science Montanuniversität LeobenFranz Josef-Straße 188700 LeobenAustria Institute of Materials Physics Helmholtz-Zentrum HereonMax-Planck-Straße 121502 GeesthachtGermany LKR Light Metals Technologies Ranshofen Austrian Institute of TechnologyLamprechtshausener Straße 615282 RanshofenAustria Institute of Materials Science Joining and FormingGraz University of TechnologyKopernikusgasse 24/I8010 GrazAustria

In recent years,wire-arc directed energy deposition(wa DED),which is also commonly known as wire-arc additive manufacturing(WAAM),has emerged as a promising new fabrication technique for magnesium *** major reason for this is the possibility of producing parts with a complex geometry as well as a fine-grained *** the process has been shown to be applicable for Mg-Al-Zn alloys,there is still a lack of knowledge in terms of the influence of the WAAM process on the age-hardening ***,this study deals with the aging response of a WAAM AZ91 *** order to fully understand the mechanisms during aging,first,the as-built condition was analyzed by means of high-energy X-ray diffraction(hEXRD)and scanning electron *** investigations revealed a finegrained,equiaxed microstructure with adjacent areas of alternating Al ***,the difference between single-and double-step aging as well as conventional and direct aging was studied on the as-built WAAM AZ91 alloy for the first *** aging response during the various heat treatments was monitored via in situ hEXRD *** electron microscopy and hardness studies were *** results showed that the application of a double-step aging heat treatment at 325℃with pre-aging at 250℃slightly improves the mechanical properties when compared to the single-step heat treatment at 325℃.however,the hardness decreases considerably after the pre-aging ***,aging at lower temperatures is preferable within the investigated temperature range of 250-325℃.Moreover,no significant difference between the conventionally aged and directly aged samples was ***,the specimens showed enhanced precipitation kinetics during aging as compared to cast *** could be attributed to a higher amount of nucleation sites and the particular temperature profile of the solution heat treatment.

关键词： Wire-arc directed energy deposition Additive manufacturing high-energy X-ray diffraction Synchrotron Mg-Al-Zn alloys Age-hardening

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Robotic surgery and liver transplantation:A single-center experience of 501 robotic donor hepatectomies

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hepatobiliary & Pancreatic Diseases International 2022年第4期21卷 334-339页

作者： Maren Schulze Yasser Elsheikh Markus Ulrich Boehnert Yasir Alnemary Saleh Alabbad Dieter clemens Broering Organ Transplant Center of Excellence King Faisal Specialist Hospital&Research CentreP.O.Box 3354Riyadh 11211Saudi Arabia

Background:Over the past two decades robotic surgery has been introduced to many areas including liver *** liver surgery is an alternative minimally invasive ***,moving on to the complexity of living donor hepatectomies,the advantages of robotic versus laparoscopic approach have convinced us to establish the robotic platform as a standard for living donor ***:From November 2018 to January 2022,501 fully robotic donor hepatectomies,including 177 left lateral donor lobes,112 full left lobes and 212 full right lobes were *** were donated to 296 adult recipients and 205 pediatric *** age,sex,body weight,body mass index(BMI),graft weight,graft to body weight ratio(GBWR),operative time,blood loss,first warm ischemic time,pain score,length of intensive care unit(ICU)stay and hospital stay,and complications were retrospectively analyzed based on a prospectively kept *** were evaluated for graft and patient survival,age,sex,BMI,body weight,model of end-stage liver disease score,blood loss,transfusions,operative time,cold ischemic time,length of hospital stay and ***:There was no donor *** cases needed to be converted to open *** median blood loss was 60 mL(range 20-800),median donor operative time was 6.77 h(range 2.93-11.53),median length of hospital stay was 4 days(range 2-22).Complication rate in donors classified following ClavienDindo was 6.4%(n=32)with one grade Ⅲ ***-year actual recipient overall survival was 91.4%;87.5% for adult recipients and 97.1% for pediatric ***-year actual graft overall survival was 90.6%;87.5% for adult recipients and 95.1% for pediatric ***-hospital mortality was 6%,9.1%(27/296)for adult recipients and 1.4%(3/205)for pediatric *** recipients’morbidity was 19.8%(n=99).Twenty-eight recipients(5.6%)had biliary and 22(4.4%)vascular ***(12.0%)recipients needed to

关键词： Living liver donor Innovation Robotic donor surgery Donor safety Minimally invasive donor surgery

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The Role of Vanes in the Damping of Bird Feathers

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Journal of Bionic Engineering 2023年第4期20卷 1646-1655页

作者： Kai Deng hamed Rajabi Alexander Kovalev clemens F.Schaber Zhendong Dai Stanislav N.Gorb Functional Morphology and Biomechanics Institute of ZoologyKiel University24098KielGermany School of Engineering London South Bank UniversityLondonSE10AAUK Institute of Bioinspired Structure and Surface Engineering Nanjing University of Aeronautics and AstronauticsNanjing210026People’s Republic of China

Bird feathers sustain bending and vibrations during *** unwanted vibrations could potentially cause noise and flight *** could alter the system response,resulting in improving quiet flight,stability,and *** of feathers are known to be indispensable for supporting the aerodynamic function of the *** relationship between the hierarchical structures of vanes and the mechanical properties of the feather has been previously ***,still little is known about their relationship with feathers’damping ***,the role of vanes in feathers’damping properties was *** vibrations of the feathers with vanes and the bare shaft without vanes after step deflections in the plane of the vanes and perpendicular to it were measured using high-speed video *** presence of several main natural vibration modes was observed in the feathers with *** trimming vanes,more vibration modes were observed,the fundamental frequencies increased by 51-70%,and the damping ratio decreased by 38-60%.Therefore,we suggest that vanes largely increase feather damping *** mechanisms based on the morphology of feather vanes are *** aerodynamic damping is connected with the planar vane surface,the structural damping is related to the interlocking between barbules and barbs,and the material damping is caused by the foamy medulla inside barbs.

关键词： Bird Feather Vibrations Damping Bionic

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Influence of high-Speed Milling Process on Mechanical and Microstructural Properties of Ultrafine Grained Profiles Produced by Linear Flow Splitting

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Transactions of Nanjing University of Aeronautics and Astronautics 2017年第4期34卷 349-356页

作者： Abele Eberhard Müller clemens Turan Emrah Niehuesbernd Joern Bruder Enrico Falk Florian Institute of Production Management Technology and Machine Tools(PTW)Technische Universitt Darmstadt Physical Metallurgy(PhM) Technische Universitt Darmstadt

The effects of milling parameters on the surface quality,microstructures and mechanical properties of machined parts with ultrafine grained(UFG)gradient microstructures are *** effects of the cutting speed,feed per tooth,cutting tool geometry and cooling strategy are *** has been found that the surface quality of machined grooves can be improved by increasing the cutting ***,cryogenic cooling with CO_2 exhibits no significant improvement of surface *** and hardness investigations revealed similar microstructure and hardness variations near the machined groove walls for both utilized tool ***,cryogenic cooling can decrease more far-ranging hardness reductions due to high process temperatures,especially in the UFG regions of the machined parts,whilst it cannot prevent the drop in hardness directly at the groove walls.

关键词： high-speed milling ultrafine grained microstructure linear flow splitting hardness

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Changes of protein expression during tumorosphere formation of small cell lung cancer circulating tumor cells

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Oncology Research 2023年第1期31卷 13-22页

作者： SANDRA STICKLER BARBARA RATh MAXIMILIAN hOChMAIR clemens LANG LUKAS WEIGL GERhARD hAMILTON Institute of Pharmacology Medical University of ViennaViennaAustria Karl Landsteiner Institute of Lung Research and Pulmonary Oncology Klinik FloridsdorfViennaAustria Department of Trauma Surgery Sozialmedizinisches Zentrum OstDonauspitalViennaAustria Division of Special Anesthesia and Pain Medicine Medical University of ViennaViennaAustria

Small cell lung cancer(SCLC)is frequently disseminated and has a dismal prognosis with survival times of approximately two *** cancer responds well to initial chemotherapy but recurs within a short time as a globally chemoresistant *** tumor cells(CTCs)are held responsible for metastasis,the extremely high numbers of these cells in advanced SCLC allowed us to establish several permanent CTC cell *** CTCs are distinguished by the spontaneous formation of large spheroids,termed tumorospheres,in regular tissue *** contain quiescent and hypoxic cells in their interior and are associated with high chemoresistance compared to single cell *** CTC lines were compared for their expression of 84 proteins associated with cancer either as single cells or in the form of tumorospheres in Western blot *** the exception of the UhGc5 line,all other CTC lines express EpCAM and lack a complete EpCAM-negative,vimentin-positive epithelial-mesenchymal transition(EMT)*** formation of tumorospheres the expression of EpCAM,that mediates cell-cell adhesion is markedly *** such as E-Cadherin,p27 KIP1,Progranulin,BXclx,Galectin-3,and Survivin showed variable changes for the distinct CTC cell *** conclusion,EpCAM presents the most critical marker for individual SCLC CTCs and the assembly of highly chemoresistant tumorospheres.

关键词： SCLC Spheroid Chemoresistance EpCAM Topotecan Epirubicin

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In vivo radiometric analysis of glucose uptake and distribution in mouse bone

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Bone Research 2016年第1期4卷 31-38页

作者： Meredith L Zoch Diane S Abou Thomas L clemens Daniel LJ Thorek Ryan C Riddle Department of Orthopaedic Surgery Johns Hopkins University School of Medicine Baltimore USA Division of Nuclear Medicine an Molecular Imaging Department of Radiology and Radiological Science Johns Hopkins University School of Medicine Baltimore USA Baltimore Veterans Administration Medical Center Baltimore USA Department of Oncology Cancer Molecular and Functional Imaging Program Sidney Kimmel Comprehensive Cancer Center Johns Hopkins University School of Medicine Baltimore USA

Bone formation and remodeling occurs throughout life and requires the sustained activity of osteoblasts and osteoclasts, particularly during periods of rapid bone growth. Despite increasing evidence linking bone cell activity to global energy homeostasis, little is known about the relative energy requirements or substrate utilization of bone cells. In these studies, we measured the uptake and distribution of glucose in the skeleton in vivo using positron-emitting 18F-fluorodeoxyglucose （[lSF]-FDG） and non-invasive, high-resolution positron emission tomography/computed tomography （PE~/CT） imaging and ex vivo autoradiography. Assessment of [~SF]-FDG uptake demonstrated that relative to other tissues bone accumulated a significant fraction of the total dose of the glucose analog..Skeletal accumulation was greatest in young mice undergoing the rapid bone formation that characterizes early development. PET/CT imaging revealed that [lSF]-FDG uptake was greatest in the epiphyseal and metaphyseal regions of long bones, which accords with the increased osteoblast numbers and activity at this skeletal site. Insulin administration significantly increased skeletal accumulation of [lSF]-FDG, while uptake was reduced in mice lacking the insulin receptor specifically in osteoblasts or fed a high-fat diet. Our results indicated that the skeleton is a site of significant glucose uptake and that its consumption by bone cells is subject to regulation by insulin and disturbances in whole-body metabolism.

关键词： bone FDG

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Ballistic tests on hot-rolled Ti-6Al-4V plates:Experiments and numerical approaches

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Defence Technology（防务技术） 2023年第8期26卷 39-53页

作者： Alexander Janda Benjamin James Ralph Yael Demarty Marcel Sorger Stefan Ebenbauer Aude Prestl Ingo Siller Martin Stockinger helmut clemens Department of Materials Science Montanuniversitat LeobenFranz Josef-Straße 188700 LeobenAustria Department Product Engineering Montanuniversitat LeobenFranz Josef-Straße 188700 LeobenAustria French-German Research Institute of Saint-Louis 5 Rue du General Cassagnou68300 Saint-LouisFrance voestalpine BOEhLER Bleche Gmbh&Co KG Boehler-Gasse 18680MürzzuschlagAustria

Superior ballistic performance and the lightweight character of Ti alloys are considered as main reasons for their use in armour applications against a broad spectrum of ballistic threats,***,fragment or blast *** dynamic loading caused by typical penetrators is characterized by high strain rates,only specific test methods allow a closer investigation of the respective material *** the present study,quasi-static and dynamic compression tests as well as ballistic tests were conducted on a twophase a+βalloy Ti-6Al-4V(in m%)manufactured by ***-deformation heat treatments,influencing microstructure and mechanical properties were applied in order to compare three different microstructural configurations:as-rolled,mill-annealed and ***,on the one hand,ballistic tests were employed for the determination of the ballistic limit velocity v_(50),compression tests,on the other hand,delivered essential input parameters for the application of the Johnson-Cook constitutive model in a finite element simulation of the impact *** comparison of experimental results to simulation results was supplemented by means of microstructural characterization of tested samples with the focus set on the prevalently observed deformation and damage mechanisms,as for example adiabatic shearing.

关键词： Ti-6Al-4V Ballistic performance Split hopkinson pressure bar FE simulation Adiabatic shear bands Intermetallic phase

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A global assessment of recent trends in gastrointestinal cancer and lifestyle-associated risk factors

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Cancer Communications 2021年第11期41卷 1137-1151页

作者： Lili Lu Christina S.Mullins clemens Schafmayer Sebastian Zeißig Michael Linnebacher Department of General Surgery Molecular Oncology and ImmunotherapyRostock University Medical CenterRostock 18057Germany Department of Medicine I University Hospital Carl Gustav CarusTechnische Universität(TU)DresdenDresden 01307Germany

Background:Gastrointestinal(GI)cancers were responsible for 26.3%of cancer cases and 35.4%of deaths worldwide in *** study aimed to analyze the global incidence,mortality,prevalence,and contributing risk factors of the 6 major GI cancer entities[esophageal cancer(EC),gastric cancer(GC),liver cancer(LC),pancreatic cancer(PC),colon cancer,and rectal cancer].Methods:Using the Global Cancer Observatory and the Global health Observatory databases,we reviewed the current GI cancer incidence,prevalence,and mortality,analyzed the association of GI cancer prevalence with national human development indices(hDIs),identified the contributing risk factors,and estimated developing age-and sex-specific trends in incidence and ***:In 2020,the trend in age-standardized rate of incidence of GI cancers closely mirrored that of mortality,with the highest rates of LC,EC,and GC in Asia and of colorectal cancer(CRC)and PC mainly in *** and mortality were positively,but the mortality-to-incidence ratio(MIR)was inversely correlated with the national hDI *** MIRs in developing countries likely reflected the lack of preventive strategies and effective *** cancer prevalence was highest in Europe and was also positively correlated with hDIs and lifestyle-associated risk factors,such as alcohol consumption,smoking,obesity,insufficient physical activity,and high blood cholesterol level,but negatively correlated with hypertension and *** of EC were consistently and those of GC mostly decreasing,whereas incidences of CRC were increasing in most countries/regions,especially in the younger *** of LC and PC were also increasing in all age-gender populations except for younger *** were decreasing for EC,GC,and CRC in most countries/regions, and age-specific trends were observed in PC and LC with adecrease in the younger but an increase in the older ***: On the global scale, higher GI c

关键词： annual percentage change(APC) diabetes gastrointestinal(GI)cancer high blood cholesterol human development indices(hDI) hypertension incidence lifestyle mortality prevalence

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Deflation and Stock Prices

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Management Studies 2019年第2期7卷 113-129页

作者： Michael clemens BankInvest Group CopenhagenDenmark

While the literature on inflation and stock prices is plentiful,there is little literature on deflation and stock *** paper explores the empirical data and makes a theoretical analysis of the likely impact on stock prices when expectations change from inflation to *** has a bad name among some economists and most ***,from a stock market perspective,deflations’bad name may not be *** observations support this:1)The 1930s was a statistical outlier and not representative for a deflationary period and deflation does not seem to create recessions,causality goes the other way;2)real stock returns are positive and around average in the periods leading up to and following the onset of deflation;3)when moving from low inflation to mild deflation,P/E ratios are virtually unchanged;and 4)peak P/E ratios seem to be reached at inflation rates close to *** author proposes three possible explanations for the seemingly disconnect between the empirical data and the“default”ex ante belief of most economists and investors:availability heurist,deflation illusion,and tax related issues in connection with the tax hypothesis.

关键词： deflation stock prices price-to-earnings ratio availability heuristic deflation illusion tax hypothesis

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Chip-compatible wide-field 3D nanoscopy through tunable spatial frequency shift effect

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Science China(Physics,Mechanics & Astronomy) 2021年第9期64卷 41-50页

作者： Xiaowei Liu Mingwei Tang Chao Meng Chenlei Pang Cuifang Kuang Wei Chen clemens F.Kaminski Qing Yang Xu Liu State Key Lab of Modern Optical Instrumentation College of Optical Science and EngineeringInternational Research Center for Advanced PhotonicsZhejiang UniversityHangzhou 310058China Research Center for Inteligent Sensing Zhejiang LabHangzhou 311100China Department of Cell Biology Department of Cardiology of the Second Affiliated HospitalSchool of MedicineZhejiang UniversityHangzhou 310058China Department of Chemical Engineering and Biotechnology University of CambridgeCambridge CB30ASUK

Spatial frequency shift(SFS) microscopy with evanescent wave illumination shows intriguing advantages, including large field of view(FOV), high speed, and good modularity. however, a missing band in the spatial frequency domain hampers the SFS superresolution microscopy from achieving resolution better than 3 folds of the Abbe diffraction limit. here, we propose a novel tunable large-SFS microscopy, making the resolution improvement of a linear system no longer restricted by the detection numerical aperture(NA). The complete wide-range detection in the spatial frequency domain is realized by tuning the illumination spatial frequency actively and broadly through an angle modulation between the azimuthal propagating directions of two evanescent waves. The vertical spatial frequency is tuned via a sectional saturation effect, and the reconstructed depth information can be added to the lateral superresolution mask for 3D imaging. A lateral resolution of λ/9, and a vertical localization precision of ~λ/200(detection objective NA = 0.9) are realized with a gallium phosphide(GaP) waveguide. Its unlimited resolution enhancing capability is demonstrated by introducing a designed metamaterial chip with an unusual large refractive index. Besides the great resolution enhancement, this method shows better anti-noise capability than classical structured illumination microscopy without SFS tunability. This method is chip-compatible and can potentially provide a massproducible illumination chip module achieving the fast, large-FOV, and deep-subwavelength 3D nanoscopy.

关键词： superresolution spatial frequency shift evanescent wave wide-field microscopy chip-compatible microscopy

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