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Molecular dynamics simulation of the Stribeck curve: Boundary lubrication, mixed lubrication, and hydrodynamic lubrication on the atomistic level

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Friction 2023年第12期11卷 2342-2366页

作者： simon stephan Sebastian SCHMITT Hans HASSE Herbert M.URBASSEK Laboratory of Engineering Thermodynamics(LTD) Department of Mechanical and Process EngieeringTU KaiserslauternRheinland-Pfalz 67663Germany Physics Department and Research Center(OPTIMAS) TU KaiserslauternRheinland-Pfalz 67663Germany

Lubricated contact processes are studied using classical molecular dynamics simulations for determining the entire range of the Stribeck ***,the lateral movement of two solid bodies at different gap height are *** each simulation,a rigid asperity is moved at constant height above a flat iron surface in a lubricating *** methane and decane are considered as *** three main lubrication regimes of the Stribeck curve and their transition regions are covered by the study:Boundary lubrication(significant elastic and plastic deformation of the substrate),mixed lubrication(adsorbed fluid layer dominates the process),and hydrodynamic lubrication(shear flow is set up between the surface and the asperity).We find the formation of a tribofilm in which lubricant molecules are immersed into the metal surface—not only in the case of scratching,but also for boundary lubrication and mixed *** formation of a tribofilm is found to have important consequences for the contact ***,the two fluids are found to show distinctly different behavior in the three lubrication regimes:For hydrodynamic lubrication(large gap height),decane yields a better tribological performance;for boundary lubrication(small gap height),decane shows a larger friction coefficient than methane,which is due to the different mechanisms observed for the formation of the tribofilm;the mixed lubrication regime can be considered as a transition regime between the two other ***,it is found that the nature of the tribofilm depends on the lubricant:While methane particles substitute substrate atoms sustaining mostly the crystalline structure,the decane molecules distort the substrate surface and an amorphous tribofilm is formed.

关键词： boundary lubrication mixed lubrication hydrodynamic lubrication molecular dynamics simulation tribofilm

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Immunological memory: resting on two shoulders at antigen entrance sites?

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Cellular & Molecular Immunology 2019年第10期16卷 835-836页

作者： Clemens Wulfing stephan Henne Jasmin Oehlmann Hauke simon Gunther Group for Interdisciplinary Neurobiology and Immunology Biozentrum GrindelUniversity of HamburgHamburgGermany

Memory is a term used in two important systems:the nervous system and the immune *** systems need to recognize alterations and threats in an ever-changing *** a consequence,both systems during their evolution perfected their abilities to recall earlier challenges in mounting protective *** ability gives both systems the power to facilitate these protective responses if confronted with the same or similar challenges again.

关键词： protective system. mount

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Reliability of the ocular trauma score for the predictability of traumatic and post-traumatic retinal detachment after open globe injury

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International Journal of Ophthalmology(English edition) 2021年第10期14卷 1589-1594页

作者： simon Dulz Vasilis Dimopoulos Toam Katz Robert Kromer Eileen Bigdon Martin stephan Spitzer Christos Skevas Department of Ophthalmology University Medical Center Hamburg-EppendorfHamburg 20246Germany Care-Vision Hamburg 20246Germany

AIM: To elucidate the question of whether the ocular trauma score(OTS) and the zones of injury could be used as a predictive model of traumatic and post traumatic retinal detachment(RD) in patients with open globe injury(OGI).METHODS: A retrospective observational chart analysis of OGI patients was performed. The collected variables consisted of age, date, gender, time of injury, time until repair, mechanism of injury, zone of injury, injury associated vitreous hemorrhage, trauma associated RD, post traumatic RD, aphakia at injury, periocular trauma and OTS in cases of OGI. RESULTS: Totally 102 patients with traumatic OGI with a minimum of 12 mo follow-up and a median age at of 48.6 y(range: 3-104 y) were identified. Final best corrected visual acuity(BCVA) was independent from the time of repair, yet a statistically significant difference was present between the final BCVA and the zone of injury. Severe trauma presenting with an OTS score Ⅰ(PⅢ. OGI associated RD was observed in 36/102 patients(35.3%), whereas post traumatic RD(defined as RD following 14 d after OGI) occurred in 37 patients(36.3%). OGI associated RD did not correlate with the OTS and the zone of injury(P=0.193), yet post traumatic RD correlated significantly with zone Ⅲ injuries(P=0.013). CONCLUSION: The study shows a significant association between lower OTS score and zone Ⅲ injury with lower final BCVA and a higher number of surgeries, but only zone Ⅲ could be significantly associated with a higher rate of RD.

关键词： intraocular foreign body ocular trauma score open globe injury retina retinal and vitreous surgery retinal detachment trauma

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Rapid chromatographic method to decipher distinct alterations in lipid classes in NAFLD/NASH

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World Journal of Hepatology 2013年第10期5卷 558-567页

作者： stephan Laggai Yvette simon Theo Ranssweiler Alexandra K Kiemer Sonja M Kessler Department of Pharmacy Pharmaceutical Biology Saarland University

AIM: To establish a simple method to quantify lipid classes in liver diseases and to decipher the lipid profile in p62/IMP2-2/IGF2BP2-2 transgenic ***: Liver-specific overexpression of the insulin-like growth factor 2 mRNA binding protein p62/IMP2-2/IGF2BP2-2 was used as a model for *** was induced by feeding a methioninecholine deficient diet. Steatosis was assessed histologically. For thin layer chromatographic analysis, lipids were extracted from freeze-dried tissues by hexane/2-propanol, dried, redissolved, and chromatographically separated by a two-solvent system. Dilution series of lipid standards were chromatographed, detected, andquantified. The detection was performed by either2',7'-dichlorofluoresceine or a sulfuric acid/ethanol ***: Histological analyses confirmed steatosis and steatohepatitis development. The extraction,chromatographic, and detection method showed high inter-assay reproducibility and allowed quantification of the different lipid classes. The analyses confirmed an increase of triglycerides and phosphatidylethanolamine and a decrease in phosphatidylcholine in the methionine-choline deficient diet. The method was used for the first time to asses the lipid classes induced in the p62-overexpressing mouse model and showed a significant increase in all detected lipid species with a prominent increase of triglycerides by 2-fold. Interestingly, the ratio of phosphatidylcholine to phosphatidylethanolamine was decreased, as previously suggested as a marker in the progression from steatosis to ***: The thin layer chromatography analysis allows a reliable quantification of lipid classes and provides detailed insight into the lipogenic effect of p62.

关键词： Non alcoholic steatohepatitis Non alcoholic fatty liver disease Thin layer chromatography IMP2/IGF2BP2 p62 Methionine choline deficient diet Polar lipids neutral lipids Phosphatidylcholine/phosphatidylethanolamine ratio Triglycerides

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3D printed micro-optics for quantum technology:Optimised coupling of single quantum dot emission into a single-mode fibre

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Light(Advanced Manufacturing) 2021年第2期2卷 1-17页

作者： Marc Sartison Ksenia Weber simon Thiele Lucas Bremer Sarah Fischbach Thomas Herzog Sascha Kolatschek Michael Jetter stephan Reitzenstein Alois Herkommer Peter Michler simone Luca Portalupi Harald Giessen Institut für Halbleiteroptik und Funktionelle Grenzflächen Research Center SCoPEand Integrated Quantum Science and Technology Center IQSTUniversity of Stuttgart70569 StuttgartGermany 4^(th)Physics Institute Research Center SCoPEand Integrated Quantum Science and Technology Center IQSTUniversity of Stuttgart70569 StuttgartGermany Institute of Applied Optics(ITO)and Research Center SCoPE University of Stuttgart70569 StuttgartGermany Institute of Solid State Physics Technical University of Berlin10623 BerlinGermany

Future quantum technology relies crucially on building quantum networks with high *** achieve this challenging goal,it is of utmost importance to connect individual quantum systems such that their emitted single photons overlap with the highest possible degree of *** requires perfect mode overlap of the emitted light from different emitters,which necessitates the use of single-mode ***,we present an advanced manufacturing approach to accomplish this *** combined 3D printed complex micro-optics,such as hemispherical and Weierstrass solid immersion lenses,as well as total internal reflection solid immersion lenses,on top of individual indium arsenide quantum dots with 3D printed optics on single-mode fibres and compared their key *** observed a systematic increase in the collection efficiency under variations of the lens geometry from roughly 2 for hemispheric solid immersion lenses up to a maximum of greater than 9 for the total internal reflection ***,the temperature-induced stress was estimated for these particular lens dimensions and results to be approximately 5 ***,the use of solid immersion lenses further increased the localisation accuracy of the emitters to less than 1 nm when acquiring micro-photoluminescence ***,we show that the single-photon character of the source is preserved after device fabrication,reaching a g^((2))(0)value of approximately 0.19 under pulsed optical *** printed lens device can be further joined with an optical fibre and permanently *** integrated system can be cooled by dipping into liquid helium using a Stirling cryocooler or by a closed-cycle helium cryostat without the necessity for optical windows,as all access is through the integrated single-mode *** identify the ideal optical designs and present experiments that demonstrate excellent high-rate single-photon emission.

关键词： mode fibre optics

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The WNT1^(G177C) mutation specifically affects skeletal integrity in a mouse model of osteogenesis imperfecta type XV

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Bone Research 2021年第4期9卷 593-605页

作者： Nele Vollersen Wenbo Zhao Tim Rolvien Fabiola Lange Felix Nikolai Schmidt stephan Sonntag Doron Shmerling simon von Kroge Kilian Elia Stockhausen Ahmed Sharaf Michaela Schweizer Meliha Karsak Bjorn Busse Ernesto Bockamp Oliver Semler Michael Amling Ralf Oheim Thorsten Schinke Timur Alexander Yorgan Department of Osteology and Biomechanics University Medical Center Hamburg-Eppendorf20246 HamburgGermany PolyGene AG 8153 RumlangSwitzerland ETH Phenomics Center(EPIC) ETH Zurich8092 ZurichSwitzerland Neuronal and Cellular Signal Transduction Center for Molecular Neurobiology Hamburg(ZMNH)University Medical Center Hamburg-Eppendorf20246 HamburgGermany Center for Molecular Neurobiology Hamburg(ZMNH) University Medical CenterHamburg-Eppendorf20246 HamburgGermany Institute for Translational Immunology and Research Center for Immunotherapy University Medical CenterJohannes Gutenberg UniversityD 55131 MainzGermany Faculty of Medicine and University Hospital Cologne Department of PediatricsUniversity of Cologne50937 CologneGermany

The recent identification of homozygous WNT1 mutations in individuals with osteogenesis imperfecta type XV(OI-XV)has suggested that WNT1 is a key ligand promoting the differentiation and function of bone-forming *** such aninfluence was supported by subsequent studies,a mouse model of OI-XV remained to be ***,we introduced a previously identified disease-causing mutation(G177C)into the murine Wnt1 *** Wnt1^(G177C/G177C)mice were viable and did not display defects in brain development,but the majority of 24-week-old Wnt1^(G177C/G177C)mice had skeletal *** increased bone fragility was not fully explained by reduced bone mass but also by impaired bone matrix ***,the homozygous presence of the G177C mutation did not interfere with the osteoanabolic influence of either parathyroid hormone injection or activating mutation of LRP5,the latter mimicking the effect of sclerostin ***,transcriptomic analyses revealed that short-term administration of WNT1 to osteogenic cells induced not only the expression of canonical WNT signaling targets but also the expression of genes encoding extracellular matrix *** together,our data demonstrate that regulating bone matrix quality is a primary function of *** further suggest that individuals with WNT1 mutations should profit from existing osteoanabolic therapies.

关键词： WNT1 skeletal impaired

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Review of the impact of heat stress on reproductive performance of sheep

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Journal of Animal Science and Biotechnology 2021年第3期12卷 859-876页

作者： William H.E.J.van Wettere Karen L.Kind Kathryn L.Gatford Alyce M.Swinbourne stephan T.Leu Peter T.Hayman Jennifer M.Kelly Alice C.Weaver David O.Kleemann simon K.Walker The University of Adelaide School of Animal and Veterinary SciencesDavies Livestock Research CentreRoseworthy CampusMudla Wirra RdRoseworthySouth Australia 5371Australia The University of Adelaide Robinson Research InstituteAdelaide Medical SchoolNorth TerraceAdelaideSouth Australia 5000Australia The University of Adelaide School of AgricultureFood and WineWaite Research InstituteUrrbraeSouth Australia 5064Australia South Australian Research and Development Institute Primary Industries and Regions SAGovernment of South AustraliaClimate ApplicationsWaite Research PrecinctUrrbraeSouth Australia 5064Australia South Australian Research and Development Institute Primary Industries and Regions SAReproductive BiologyLivestock SciencesTurretfield Research Centre129 Holland RdRosedaleSouth Australia 5350Australia

Heat stress significantly impairs reproduction of sheep,and under current climatic conditions is a significant risk to the efficiency of the meat and wool production,with the impact increasing as global temperatures *** from field studies and studies conducted using environmental chambers demonstrate the effects of hot temperatures(≥32℃)on components of ewe fertility(oestrus,fertilisation,embryo survival and lambing)are most destructive when experienced from 5 d before until 5 d after *** controlled studies also demonstrate that ram fertility,as measured by rates of fertilisation and embryo survival,is reduced when mating occurs during the period 14 to 50 d ***,the contribution of the ram to heat induced reductions in flock fertility is difficult to determine *** primarily on temperature controlled studies,it is clear that sustained exposure to high temperatures(≥32℃)during pregnancy reduces lamb birthweight and will,therefore,decrease lamb survival under field *** is concluded that both ewe and ram reproduction is affected by relatively modest levels of heat stress(≥32℃)and this is a concern given that a significant proportion of the global sheep population experiences heat stress of this magnitude around mating and during *** this,strategies to limit the impacts of the climate on the homeothermy,behaviour,resource use and reproduction of extensively grazed sheep are limited,and there is an urgency to improve knowledge and to develop husbandry practices to limit these impacts.

关键词： Fertility Heat stress Oogenesis Pregnancy Sheep Spermatogenesis

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Protective and Regenerative Efficacy of a Plant Oil-Based Day and Night Cream: Investigated by a Novel Approach to Reveal the Impact of Blue Light Irradiation on Epidermal Barrier Integrity and Lipid Matrix

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Journal of Cosmetics, Dermatological Sciences and Applications 2024年第3期14卷 227-241页

作者： Dorothee Dähnhardt stephan Dähnhardt-Pfeiffer Isabel simon Dana Ditgen Inge Holland Dörte Segger Peter Staib Microscopy Services Dhnhardt GmbH Flintbek Germany Research & Development and Regulatory Affairs Kneipp GmbH Wuerzburg Germany SGS INSTITUT FRESENIUS GmbH Hamburg Germany

In recent years, the harmful effects of blue light (400 - 500 nm) as a component of visible light (400 - 700 nm) have increasingly gained attention of science, industry, and consumers. To date, only a few in vivo test methods for measuring the effects of blue light on the skin have been described. A direct measurement method that can detect the immediate effects of blue light on the epidermal permeability barrier (EPB) is still lacking. In this study, we present a new methodological approach that can be used to investigate both the protective and regenerative effects of cosmetic products on the EPB after blue light irradiation. In a study with 14 female volunteers, it was investigated whether the regular application of an O/W emulsion (day cream) can strengthen and protect the epidermal barrier against damaging blue light radiation of 60 J/cm2 (protective study design) and also whether a disruption of the epidermal barrier caused by blue light radiation is restored faster and better by the regular application of another O/W emulsion (night cream) than in product-untreated skin (regenerative study design). The two O/W emulsions are different in plant oil, active ingredient composition and texture. The seven-day treatment with the day cream initially led to a significant increase in the normalized lipid lamellae length in the intercellular space, whereas the irradiation with blue light after 24 hours led to a significant decrease in the lipid lamellae length in the untreated test area, but not in the area previously treated with the product. Regarding the regenerative study design, a two-day treatment with the night cream was able to restore a blue-light-induced decrease in lipid lamellae length in the intercellular space. In summary, with the study designs presented here, the protective and regenerative effect of two cosmetic products could be demonstrated for the first time on the integrity of the EPB after blue light irradiation and the data showed that the Lipbarv

关键词： Skin Care Blue Light Irradiation Skin Barrier Intercellular Lipid Lamellae Electron Microscopy

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Protective and Regenerative Anti-Pollution Efficacy of a Plant Oil-Based Day and Night Cream: Investigated by a Novel Approach to Reveal the Impact of Pollutants on Epidermal Barrier Integrity and Lipid Matrix

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Journal of Cosmetics, Dermatological Sciences and Applications 2023年第4期13卷 302-321页

作者： Dorothee Dähnhardt stephan Dähnhardt-Pfeiffer Isabel simon Dana Ditgen Inge Holland Dörte Segger Jürgen Blaak Peter Staib Microscopy Services Dä hnhardt GmbH Flintbek Germany Research & Development and Regulatory Affairs Kneipp GmbH Wuerzburg Germany SGS INSTITUT FRESENIUS GmbH Hamburg Germany

In the wake of ever-increasing environmental pollution, human skin in the modern urban world is exposed to increased levels of harmful environmental pollutants. Many studies have shown that these pollutants can weaken the epidermal skin barrier and thus facilitate the penetration of these substances into the skin. An important goal of modern skin care against harmful environmental influences should therefore be to protect and strengthen the epidermal barrier and to repair occurring damage quickly and efficiently. With this in mind, in the present study we investigated what damage cigarette smoke causes to the epidermal barrier and 1) whether the regular application of a O/W emulsion (Day Cream) can protectively strengthen the epidermal barrier against environmental damage and 2) whether a cigarette smoke-induced disruption of the epidermal barrier is restored faster and better by the regular application of a another O/W emulsion (Night Cream) than in product-untreated skin. The two products are slightly different in plant-oil, active ingredient composition and texture. Firstly, the study has shown that the Lipbarvis? method is suitable for measuring the effect of cigarette smoke, in contrast to conventional biophysical measurement methods (transepidermal water loss, skin hydration). Secondly, both products were able to improve skin barrier function in the corresponding test scenario. This was demonstrated for both test products by a significantly reduced TEWL, significantly increased skin hydration and significantly improved length of the lipid lamellae in the intercellular space, as well as the protective effect of the day cream on the epidermal skin barrier and the regenerative properties of the tested night cream. .

关键词： Skin Care Anti-Pollution Skin Barrier Intercellular Lipid Lamellae Cigarette Smoke

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制动盘表面螺旋纹理的消除方法(英文)

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2014年第1期15卷 53-60页

作者： Adrián RODRíGUEZ L.Norberto LóPEZ de LACALLE Asier FERNáNDEZ stephan BRAUN Department of Mechanical Engineering University of the Basque Country (UPV/EHU) Faculty of Engineering of Bilbao Department of Mechanical Engineering Georg-Simon-Hochschule Nuremberg Faculty of Engineering Kesslerplatz 12

创新要点:提出以冲刷代替传统磨削过程对制动盘进行抛光;研究获取规定表面质量下的最优冲刷条件。

关键词：制动盘冲刷表叫粗糙度螺旋模式铸铁

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