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Spectrally tunable high-power Yb:fiber chirped-pulse amplifier

Photonics Research 2022年第10期10卷 2309-2316页

作者： VALENTINA SHUMAKOVA VITO F.PECILE JAKOB FELLINGER MICHAEL LESKOWSCHEK P.E.COLLIN ALDIA ALINE S.MAYER LUKAS W.PERNER SARPER SALMAN MINGQI FAN PRANNAY BALLA STÉPHANE SCHILT CHRISTOPH M.HEYL ingmar hartl GIL PORAT OLIVER H.HECKL Christian Doppler Laboratory for Mid-IR Spectroscopy and Semiconductor Optics Faculty Center for Nano Structure ResearchFaculty of PhysicsUniversity of ViennaA-1090 ViennaAustria Photonics Institute TU WienA-1040 ViennaAustria Vienna Doctoral School in Physics University of ViennaA-1090 ViennaAustria Deutsches Elektronen-Synchrotron DESY 22607 HamburgGermany Laboratoire Temps-Fréquence Universitéde NeuchâtelCH-2000 NeuchâtelSwitzerland GSI Helmholtzzentrum für Schwerionenforschung GmbH 64291 DarmstadtGermany Helmholtz-Institute Jena 07743 JenaGermany Department of Electrical and Computer Engineering University of AlbertaEdmontonAlberta T6G 1H9Canada Department of Physics University of AlbertaEdmontonAlberta T6G 2E1Canada

Tailoring the properties of the driving laser to the need of applications often requires compromises among laser stability,high peak and average power levels,pulse duration,and spectral *** instance,spectroscopy with optical frequency combs in the extreme/visible ultraviolet spectral region requires a high peak power of the near-IR driving laser,and therefore high average power,pulse duration of a few tens of fs,and maximal available spectral ***,the parametric conversion efficiency is higher for pulses with a duration in the 100-fs range due to temporal walk-off and coating *** we suggest an approach to adjust the spectral characteristics of high-power chirped-pulse amplification(CPA)to the requirements of different nonlinear frequency converters while preserving the low-phase-noise(PN)properties of the *** achieve spectral tunability,we installed a mechanical spectral shaper in a free-space section of the stretcher of an in-house-developed ytterbium-fiber-based CPA *** CPA system delivers 100 W of average power at a repetition rate of 132.4 *** gaining control over the spectral properties,we preserve the relative-intensity-noise and PN properties of the *** high-power CPA can easily be adjusted to deliver either a spectrum ideal for mid-IR light generation(full width at half maximum of∼11 nm,compressed pulse duration of 230 fs)or a spectrum ideal for highly nonlinear processes such as high-harmonic generation(−10 dB level of>50 nm,transform-limited pulse duration of∼65 fs).

关键词： pulse power fiber

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Factor 30 Pulse Compression by Hybrid Multipass Multiplate Spectral Broadening

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Ultrafast Science 2022年第1期2卷 17-26页

作者： Marcus Seidel Prannay Balla Chen Li Gunnar Arisholm Lutz Winkelmann ingmar hartl Christoph M.Heyl Deutsches Eilektronen Synchrotron DESY Notkestrasse 8522607 HamburgGermany Helmholtz Institute Jena Frobelstieg 307743 JenaGermany GSI Helmholtzzentrum fir Schwerionenforschung GmbH Planckstrasse 164291 DarmstadtGermany FFI(Norwegian Defence Research Estabishment) P.O.Box 25NO 2027 KjellerNorway

As ultrafast laser technology advances towards ever higher peak and average powers,generating sub-50 fs pulses from laser architectures that exhibit best power-scaling capabilities remains a major ***,we present a very compact and highly robust method to compress 1.24 ps pulses to 39fs by means of only a single spectral broadening stage which neither requires vacuum parts nor custom-made *** approach is based on the hybridization of the multiplate continuum *** multipass cell spectral broadening *** combination leads to significantly higher spectral broadening factors in bulk material than what has been reported from either method ***,our approach efficiently suppresses adverse features of single-pass bulk spectral *** use a burst-mode Yb:YAG laser emitting pulses with 80 MW peak power that are enhanced to more than 1 GW after *** only 0.19%rms pulse-to-pulse energy fluctuations,the technique exhibits excellent ***,we have measured state-of-the-art spectral-spatial homogeneity and good beam quality of M^(2)=1.2 up to a spectral broadening factor of *** to the method's simplicity,compactness,and scalability,it is highly attractive for turning a picosecond laser into an ultrafast light source that generates pulses of only a few tens of femtoseconds duration.

关键词： attractive simplicity Pulse

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Investigation of the tribological performance of ionic liquids in non-conformal EHL contacts under electric field activation

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Friction 2020年第5期8卷 982-994页

作者： Michal MICHALEC Petr SVOBODA Ivan KRUPKA Martin hartl Aleksandar VENCL Faculty of Mechanical Engineering Brno University of TechnologyBrno 61669Czech Republic Central European Institute of Technology Brno University of TechnologyBrno 61200Czech Republic Faculty of Mechanical Engineering University of BelgradeBelgrade 11120Serbia South Ural State University Chelyabinsk 454080Russia

Real-time external alteration of the internal properties of lubricants is highly desirable in all mechanical systems. However, fabricating a suitable and effective smart lubricant is a long-lasting experimental process. In this study, the film thickness and frictional response of ionic liquid-lubricated non-conformal contacts to an electric field excitation under elastohydrodynamic conditions were examined. Film thickness was evaluated using a "ball-on-disc" optical tribometer with an electric circuit. Friction tests were carried on a mini traction machine (MTM) tribometer with a "ball-on-disc" rotation module and an electric circuit for contact area excitation. The results demonstrate that there is a difference in the behaviour of the ionic liquid during electric field excitation at the evaluated film thicknesses. The results of evaluated film thicknesses demonstrate that there is a difference in the behaviour of the ionic liquid during electric field excitation. Therefore, the ionic liquids could be a new basis for the smart lubrication of mechanical components. Moreover, the proposed experimental approach can be used to identify electrosensitive fluids.

关键词： friction thin film lubrication electro-rheological fluid smart fluid lubrication

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Lubricant flow in thin-film elastohydrodynamic contact under extreme conditions

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Friction 2016年第4期4卷 380-390页

作者： P.SPERKA I.KRUPKA M.hartl Faculty of Mechanical Engineering Brno University of Technology Technicka 2896/2 Brno 61669 Czech Republic

To further extend knowledge about fluid film friction in elastohydrodynamic contact,it is important to examine how lubricant *** this paper,several film thickness results obtained by interferometry technique for different kinds of experiments were analyzed and discussed based on lubricant flow *** of two steady-state and two transient experiments are *** speed profiles that can explain observed film thickness distributions were *** is shown that major part of present experiments can be explained by a single speed profile known as a plug *** finding is in contradiction to usual linear speed profile predicted by Reynolds equation.

关键词： fluid film friction speed profile flow rate continuity lubricant rheology plug flow

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Running-in friction of hip joint replacements can be significantly reduced:The effect of surface-textured acetabular cup

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Friction 2020年第6期8卷 1137-1152页

作者： David NECAS Hatsuhiko USAMI Tatsuya NIIMI Yoshinori SAWAE Ivan KRUPKA Martin hartl Faculty of Mechanical Engineering Brno University of TechnologyBrno 61669Czech Republic Faculty of Science and Technology Meijo UniversityNagoya 468-8502Japan Kanefusa Corporation Nagoya 480-0192Japan Faculty of Engineering Kyushu UniversityFukuoka 819-0395Japan

Hip joint replacements represent the most effective way of treatment for patients suffering from joint *** the rapid improvement of implant materials over the last few decades,limited longevity associated with wear-related complications persists as the main ***,improved tribological perfor-mance is required in order to extend the service life of *** effect of surface texturing of ultra-high molecular weight polyethylene(UHMWPE)acetabular cup was investigated in the present *** tilling method was utilized for manufacturing the dimples with controlled diameter and depths on the contact surface of the *** experiments with four commercial femoral components and two model lubricants were *** main attention was paid to a coefficient of friction considering the differences between the original and the dimpled *** showed remarkable lowering of friction,in *** on the simulated human synovial fluid,friction was reduced by 40%(alumina ceramic),38.8%(zirconia toughened ceramic),25.5%(metal),and 9.9%(oxinium).In addition,the dimples helped to keep the friction stable without *** conclude,the paper brings a new insight into frictional behaviour of the hip replacements during running-in phase which is essential for overall implant *** is believed that proper surface texturing may rapidly improve the life quality of millions of patients and may lead to considerable financial savings.

关键词： hip joint replacement friction texturing dimple longevity

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Attractive but Toxic： Emerging Roles of Glycosidically Bound Volatiles and Glycosyltransferases Involved in Their Formation

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Molecular Plant 2018年第10期11卷 1225-1236页

作者： Chuankui Song Katja hartl Kate McGraphery Thomas Hoffmann Wilfried Schwab State Key Laboratory of Tea Plant Biology and Utilization Anhui Agricultural University West Changjiang Road Hefei Anhui 230036 China Biotechnology of Natural Products Technische Universitat Munchen Liesel-Beckmann-Str. 1 Freising 85354 Germany

Plants emit an overabundance of volatile compounds, which act in their producers either as appreciated attractants to lure beneficial animals or as repellent toxins to deter pests in a species-specific and concentration-dependent manner. Plants have evolved solutions to provide sufficient volatiles without poisoning themselves. Uridine-diphosphate sugar-dependent glycosyltransferases （UGTs） acting on vola-tiles is one important part of this sophisticated system, which balances the levels of bioactive metabolites and prepares them for cellular and long-distance transport and storage but enables the remobilization of disarmed toxins for the benefit of plant protection. This review provides an overview of the research history of glycosidically bound volatiles （GBVs）, a relatively new group of plant secondary metabolites, and discusses the role of UGTs in the production of GBVs for plant protection.

关键词： glycosyltransferases terpenoids volatiles plant protection transport storage

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Redox Regulation of Arabidopsis Mitochondrial Citrate Synthase

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Molecular Plant 2014年第1期7卷 156-169页

作者： Elisabeth Schmidtmann Ann-Christine Konig Anne Orwat Dario Leister Markus hartl Iris Finkemeier Botany Department I of Biology Ludwig-Maximilians-University Munich Grosshaderner Strasse 2 82152 Planegg-Martinsried Germany

Citrate synthase has a key role in the tricarboxylic （TCA） cycle of mitochondria of all organisms, as it cata- lyzes the first committed step which is the fusion of a carbon-carbon bond between oxaloacetate and acetyl CoA. The regulation of TCA cycle function is especially important in plants, since mitochondrial activities have to be coordinated with photosynthesis. The posttranslational regulation of TCA cycle activity in plants is thus far almost entirely unexplored. Although several TCA cycle enzymes have been identified as thioredoxin targets in vitro, the existence of any thioredoxin-dependent regulation as known for the Calvin cycle, yet remains to be demonstrated. Here we have investigated the redox regulation of the Arabidopsis citrate synthase enzyme by site-directed mutagenesis of its six cysteine residues. Our results indicate that oxidation inhibits the enzyme activity by the formation of mixed disulfides, as the partially oxidized citrate synthase enzyme forms large redox-dependent aggregates. Furthermore, we were able to demonstrate that thioredoxin can cleave diverse intraas well as intermolecular disulfide bridges, which strongly enhances the activity of the enzyme. Activity measurements with the cysteine variants of the enzyme revealed important cysteine residues affecting total enzyme activity as well as the redox sensitivity of the enzyme.

关键词： citrate synthase mitochondria cysteine residues redox regulation thioredoxin TCA cycle Arabidopsis.

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Individualized treatment options for patients with non-cirrhotic and cirrhotic liver disease

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World Journal of Gastroenterology 2021年第19期27卷 2281-2298页

作者： Lukas hartl Joshua Elias Gerhard Prager Thomas Reiberger Lukas W Unger Division of Gastroenterology and Hepatology Department of Internal Medicine IIIMedical University of ViennaVienna A-1090Austria Vienna Hepatic Hemodynamic Lab Medical University of ViennaVienna A-1090Austria Cambridge Institute of Therapeutic Immunology and Infectious Disease Jeffrey Cheah Biomedical CentreUniversity of CambridgeCambridge CB20AWUnited Kingdom Division of Gastroenterology and Hepatology Department of MedicineUniversity of CambridgeAddenbrooke’s HospitalCambridge CB20QQUnited Kingdom Division of Visceral Surgery Department of General SurgeryMedical University of ViennaVienna A-1090Austria

The obesity pandemic has led to a significant increase in patients with metabolic dysfunction-associated fatty liver disease(MAFLD).While dyslipidemia,type 2 diabetes mellitus and cardiovascular diseases guide treatment in patients without signs of liver fibrosis,liver related morbidity and mortality becomes relevant for MAFLD’s progressive form,non-alcoholic steatohepatitis(NASH),and upon development of liver *** should be prescribed in patients without significant fibrosis despite concomitant liver diseases but are underutilized in the real-world *** surgery,especially Y-Roux bypass,has been proven to be superior to conservative and/or medical treatment for weight loss and resolution of obesity-associated diseases,but comes at a low but existent risk of surgical complications,reoperations and very rarely,paradoxical progression of *** end-stage liver disease develops,obese patients benefit from liver transplantation(LT),but may be at increased risk of perioperative infectious *** LT,metabolic comorbidities are commonly observed,irrespective of the underlying liver disease,but MAFLD/NASH patients are at even higher risk of disease *** studies with low patient numbers evaluated if,and when,bariatric surgery may be an option to avoid disease recurrence but more high-quality studies are needed to establish clear *** this review,we summarize the most recent literature on treatment options for MAFLD and NASH and highlight important considerations to tailor therapy to individual patient’s needs in light of their risk profile.

关键词： Metabolic dysfunction-associated fatty liver disease Non-alcoholic fatty liver disease Portal hypertension Cirrhosis Bariatric surgery Metabolism

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Effects of solid friction modifier on friction and rolling contact fatigue damage of wheel-rail surfaces

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Friction 2022年第4期10卷 597-607页

作者： Jingdong SONG Lubing SHI Haohao DING Radovan GALAS Milan OMASTA Wenjian WANG Jun GUO Qiyue LIU Martin hartl Tribology Research Institute State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengdu 610031China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China Faculty of Mechanical Engineering Brno University of TechnologyBrno 61669Czech Republic

In railway network,friction is an important factor to consider in terms of the service behaviors of wheel-rail *** objective of this study was to investigate the effect of a solid friction modifier(FM)in a railway *** was achieved by studying the friction,wear,and rolling contact fatigue(RCF)damage on the wheel-rail materials at different slip *** results showed that when a solid FM was applied,the friction coefficient *** the solid FM was separated from the wheel-rail interface,the friction coefficient gradually increased to its original *** the application of the solid FM,the wear rates of the wheel-rail *** addition,the thickness and hardness of the plastic deformation layers of the wheel-rail materials were *** worn surfaces of the wheel-rail were dominated by pits and RCF *** the FM,RCF cracks ranged from 84 to 120μm,and subsurface cracks were ***,with the FM,RCF cracks ranged from 17 to 97μm and no subsurface cracks were *** findings indicate possible methods of improving the performance of railway rolling stock by managing friction,and reducing wear and permanent RCF damage affecting both the wheels and rails.

关键词： wheel-rail solid friction modifier(FM) friction wear rolling contact fatigue(RCF)damage

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Raman analysis of chemisorbed tribofilm for metal-on-polyethylene hip joint prostheses

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Biosurface and Biotribology 2021年第1期7卷 1-11页

作者： Risha Rufaqua Martin Vrbka Dušan Hemzal Dipankar Choudhury David Rebenda Ivan Křupka Martin hartl Faculty of Mechanical Engineering Brno University of TechnologyBrnoCzech Republic Department of Condensed Matter Physics Faculty of ScienceMasaryk UniversityBrnoCzech Republic Nano Mechanics and Tribology Laboratory Department of Mechanical EngineeringUniversity of ArkansasFayettevilleArkansasUSA

The biochemical reaction during the formation of lubricant film the in case of a cobalt-chromium ball on an ultrahigh-molecular weight polyethylene cup was *** types of model synovial fluids and hyaluronic acid(HA)at physiologic concentrations were used in the *** coefficient of friction was measured using a pendulum hip simulator,and Raman spectroscopy was used to perceive chemical reactions between the synovial fluid and implant *** spectra evidenced that the three model fluids and HA chemisorbed onto the cobalt-chromium ***α-helix structure of the model fluid components was detected on the surface of the prosthesis.

关键词： material surface experiment

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