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On the experimental characterization of the fluid volume influence on the friction between rough surfaces

Friction 2023年第7期11卷 1334-1348页

作者： lukas STAHL Michael MÜLLER Georg-Peter OSTERMEYER Institute of Dynamics and Vibrations Technische Universität BraunschweigBraunschweig 37106Germany

The load-bearing behaviour of lubricated contacts depends primarily on the normal force,the relative velocity,and the ***,with the aid of the Stribeck curve,it is usually well possible to characterize whether hydrodynamics,mixed friction,or boundary friction is more likely to be *** fact that the load regime can also depend on the fluid quantity is obvious,but has hardly been systematically investigated so *** for contacts with microscopic roughness,the defined application of a very small amount of fluid is a very challenging *** this paper,a very fundamental study shows how a pin-on-disc tribometer can be used to achieve the transition from dry friction via mixed friction to predominant hydrodynamics by the amount of supplied *** experiments are carried out on samples filed with different *** addition,the simultaneous influence of partial filling and normal force as well as relative velocity is also *** good reproducibility has been practically reached over the entire range of the *** the quantities for the coefficient of friction(COF),it was concluded that close to full filling,a reduction of the fluid quantity has a similar effect on the COF as the reduction of the *** property goes along with the common theory of starved lubricated *** behaviour was not observed to the same extent for the normal *** the vicinity of smaller fluid quantities,the COF increases very rapidly with further reduction in fluid quantity,far more disproportionately than that with reduction in *** a deeper understanding of this problem,various practical issues such as idling or the run-up process in bearings can also be studied in a more focused manner.

关键词： starved lubrication Stribeck curve pin-on-disc tribometer fluid supply experimental studies

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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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Experimental investigation of radiative heat propagation in a simplified generic packed bed

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Particuology 2024年第5期88卷 149-160页

作者： Matthias Tyslik lukas Pörtner Siegmar Wirtz Martin Schiemann Institute of Energy Plant Technology Ruhr-University Bochum44780 BochumGermany

A novel test rig for the investigation of radiative heat transfer in packed beds has been developed and is introduced with representative experimental *** individual components and the calibration are *** generic packed bed is realized in a simplified way by an arrangement of parallel rods,which represent particles in *** this arrangement,electrically heated rods provide the radiation propagating through the rod array to heat the passive counterparts.A sophisticated temperature-control scheme with a large number of thermocouples and infrared-imaging provides in-depth information about heat transfer in the *** radiation intensities are determined with a Fourier-transform infrared spectroscopy,which has been modified and validated for this specific *** order to compare the influence of different surface properties of particles on the heat propagation and surface reflections,rod samples made of stainless steel and magnesium oxide are *** influence of material properties becomes clearly visible by comparing the high radiation intensities resulting from a stainless steel rod array to the same geometry built from magnesium oxide *** addition,the influence of the surface properties is particularly evident in the infrared images since the reflections are significantly higher for the stainless steel samples than for the magnesium oxide *** experimental results in the current work demonstrate the ability of the test rig to provide data with a well-defined accuracy as a validation base for numerical radiation simulations in packed beds.

关键词： Thermal radiation Spectral reflections Fourier-transform infrared spectroscopy

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Development and characterization of photovoltaic tandemjunction nanowires using electron-beam-induced current measurements

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Nano Research 2022年第9期15卷 8510-8515页

作者： lukas Hrachowina Enrique Barrigón Magnus T.Borgström NanoLund and Divison of Solid State Physics Lund UniversityBox 11822100 LundSweden Universidad de Málaga Andalucía TechDepartamento de Física Aplicada ⅠCampus de Teatinoss/nMálaga 29071Spain

Nanowires have many interesting properties that are of advantage for solar cells,such as the epitaxial combination of latticemismatched materials without plastic *** could be utilized for the synthesis of axial tandem-junction nanowire solar cells with high efficiency at low material ***-beam-induced current measurements have been used to optimize the performance of single-junction nanowire solar ***,we use electron-beam-induced current measurements to break the barrier to photovoltaic tandem-junction *** particular,we identify and subsequently prevent the occurrence of a parasitic junction when combining an InP n-i-p junction with a tunnel ***,we demonstrate how to use optical and electrical biases to individually measure the electron-beam-induced current of both sub-cells of photovoltaic tandem-junction *** show that with an applied voltage in forward direction,all junctions can be analyzed *** development of this characterization technique enables further optimization of tandem-junction nanowire solar cells.

关键词： Ⅲ-Ⅴnanowire nanowire solar cell tandem-junction Esaki tunnel diode electron-beam induced current(EBIC)

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Mid-infrared-perturbed molecular vibrational signatures in plasmonic nanocavities

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Light(Science & Applications) 2022年第1期11卷 127-135页

作者： Rohit Chikkaraddy Angelos Xomalis lukas A.Jakob Jeremy J.Baumberg NanoPhotonics Centre Cavendish LaboratoryDepartment of PhysicsJJ Thompson AvenueUniversity of CambridgeCambridge CB30HEUK Empa Swiss Federal Laboratories for Materials Science and TechnologyLaboratory for Mechanics of Materials and NanostructuresThunSwitzerland

Recent developments in surface-enhanced Raman scattering(SERS)enable observation of single-bond vibrations in real time at room *** contrast,mid-infrared(MIR)vibrational spectroscopy is limited to inefficient slow *** we develop a new method for MIR sensing using *** method utilizes nanoparticle-on-foil(NPoF)nanocavities supporting both visible and MIR plasmonic hotspots in the same nanogap formed by a monolayer of *** SERS signals from individual NPoF nanocavities are modulated in the presence of MIR *** strength of this modulation depends on the MIR wavelength,and is maximized at the 6–12μm absorption bands of SiO_(2) or polystyrene placed under the *** a single-photon lock-in detection scheme we time-resolve the rise and decay of the signal in a few 100 *** observations reveal that the phonon resonances of SiO_(2) can trap intense MIR surface plasmons within the Reststrahlen band,tuning the visible-wavelength localized plasmons by reversibly perturbing the localized few-nm-thick water shell trapped in the nanostructure *** suggests new ways to couple nanoscale bond vibrations for optomechanics,with potential to push detection limits down to single-photon and single-molecule regimes.

关键词： visible signature utilize

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Cytokines and fatty liver diseases

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Liver Research 2018年第1期2卷 14-20页

作者： lukas Niederreiter Herbert Tilg Department of Internal Medicine I GastroenterologyEndocrinology&MetabolismMedical University InnsbruckInnsbruckAustria

Cytokines are considered crucial players in inflammatory-associated disorders throughout the *** liver diseases such as alcoholic liver disease(ALD)and non-alcoholic fatty liver disease(NAFLD)are commonly characterized by lipid accumulation and in a substantial subset of patients with inflammation in the *** of inflammation affects long-term outcome of liver disease including evolution of liver fibrosis,cirrhosis and hepatocellular *** the pro-inflammatory cytokines Interleukin(IL)-1(αandβ)and tumor necrosis factor(TNF)αplay a central role in many stages of liver diseases mediating fundamental aspects of those diseases including acute phase protein synthesis,lipid metabolism,cholestasis and degree of *** key cytokines released mainly by mononuclear cells affect all liver cell types and orchestrate the production of many other mediators relevant in chronic liver *** cytokines also regulate crucially the development of insulin resistance,a key component of *** these critical mediators of inflammation by specific antibodies,especially TNFα,has so far not been proven successful in alcoholic steatohepatitis,a cytokine-driven *** summary,inflammatory cytokines are continuously present locally and systemically in patients with advanced fatty liver diseases,mediating and affecting the clinical phenotype and many features of these disorders.

关键词： Alcoholic hepatitis(AH) Cytokines Inflammation Interleukin(IL)-1 Alcoholic liver disease(ALD) Non-alcoholic fatty liver disease(NAFLD) Tumor necrosis factor(TNF)α

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Repeated Multiview Imaging for Estimating Seedling Tiller Counts of Wheat Genotypes Using Drones

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Plant Phenomics 2020年第1期2卷 279-298页

作者： lukas Roth Moritz Camenzind Helge Aasen lukas Kronenberg Christoph Barendregt Karl-Heinz Camp Achim Walter Norbert Kirchgessner Andreas Hund ETH Zurich Institute of Agricultural SciencesUniversitätstrasse 28092 ZurichSwitzerland Delley Samen und Pflanzen AG Route de Portalban 401567 DelleySwitzerland

Early generation breeding nurseries with thousands of genotypes in single-row plots are well suited to capitalize on high throughput ***,methods to monitor the intrinsically hard-to-phenotype early development of wheat are yet *** aimed to develop proxy measures for the rate of plant emergence,the number of tillers,and the beginning of stem elongation using drone-based *** used RGB images(ground sampling distance of 3mm pixel-1)acquired by repeated flights(≥2 flights per week)to quantify temporal changes of visible leaf *** exploit the information contained in the multitude of viewing angles within the RGB images,we processed them to multiview ground cover images showing plant pixel *** on these images,we trained a support vector machine for the beginning of stem elongation(GS30).Using the GS30 as key point,we subsequently extracted plant and tiller counts using a watershed algorithm and growth modeling,*** results show that determination coefficients of predictions are moderate for plant count(R^(2)=0:52),but strong for tiller count(R^(2)=0:86)and GS30(R^(2)=0:77).Heritabilities are superior to manual measurements for plant count and tiller count,but inferior for GS30 *** the selection intensity due to throughput may overcome this *** image traits can replace hand measurements with high efficiency(85-223%).We therefore conclude that multiview images have a high potential to become a standard tool in plant phenomics.

关键词： Wheat watershed breeding

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New approaches for brazing temperature sensitive materials

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China Welding 2014年第3期23卷 21-25页

作者： Wolfgang TiUmann Chunlai Liu lukas Wojarski Institute of Materials Engineering Technical University of Dortmund

PVD deposited copper interlayers as filler materials were used in order to manufacture TLP brazed magnesium joints. The microstructure and interface characteristics of the overlap joints were investigated by optical microscopy, scanning electron microscope with energy dispersive spectrometer and tensile testing. Sound brazed joints could be achieved. The dwell time is the main factor to control the thickness of the reaction layer. It was shown that the deposited copper filler metal clearly reacted with the magnesium substrate , resulting in the formation of a magnesium solid solution （Mg） with different amount of copper, aluminum and zinc as well as Mg2Cu phases. With the progressing diffusion, the formation of intermetaUic compounds was suppressed and the hardness distribution in the brazing seam homogenized. The joints fractured at the interface, and the maximum average tensile shear strength of overlap joints reached 85 MPa.

关键词： brazing TLP diffusion magnesium

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The emergence and evolution of OpenStreetMap: a cellular automata approach

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International Journal of Digital Earth 2015年第1期8卷 76-90页

作者： Jamal Jokar Arsanjani Marco Helbich Mohamed Bakillah lukas Loos GIScience Research Group Institute of GeographyHeidelberg UniversityHeidelbergGermany

Collaborative mapping projects,such as OpenStreetMap(OSM),have received tremendous amounts of contributed data from voluntary participants over *** far,most research efforts deal with data quality issues,but the OSM evolution across space and over time has not been ***,this study is dedicated to the evolution of the contributed information in order to understand an emergent phenomenon of so-called collaborative *** main objective of this paper is to monitor the evolutional pattern of OSM and predict potential future states through a cellular automata(CA)*** is exceedingly relevant for numerous OSM-based *** spatiotemporal analysis of the contributions for the time period 2007–2012,using the city of Heidelberg(Germany)as a case study,reveals that early contributions are given three years after the launching of OSM,while after nearly six years,most of the areas are *** simulation results for the validated CA model,predicting OSM states for 2014,provide clear evidence that most of the areas have been explored three years after people began mapping until 2010,and thereafter,the densification process has begun and will cover most parts of the city although the amount of contribution depends on the land use types.

关键词： cellular automata OpenStreetMap transition rules spatiotemporal analysis collaborative contributing

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Solid-state emissive biphenylene bridged bisaroyl-S,N-ketene acetals as distinct aggregation-induced enhanced emitters and fluorometric probes

Aggregate

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Aggregate 2021年第5期2卷 179-184页

作者： lukas Biesen Thomas J.J.Muller Institut fur Organische und Makromolekulare Chemie Heinrich-Heine-Universitat DusseldorfDüsseldorfGermany

Biphenylene bridged bisaroyl-S,N-ketene acetals can be readily synthesized by a one-pot Masuda borylation-Suzuki arylation sequence,thus,yielding a library of 20 bisaroyl-S,N-ketene acetals with tunable solid-state emission and aggregationinduced enhanced emission characteristics depending on the para substituents in the starting *** applications as fluorometric probe of alcoholic beverages are outlined.

关键词： aggregation-induced emission aroyl-S N-ketene acetals liquor sensors one-pot reaction solid-state

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