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Electrostatic interactions in twisted bilayer graphene

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Nano Materials Science 2022年第1期4卷 27-35页

作者： Tommaso Cea Pierre A.Pantaleón niels R.Walet Francisco Guinea Imdea Nanoscience Faraday 928015MadridSpain Department of Physics and Astronomy University of ManchesterManchesterM13 9PYUK Donostia International Physics Center Paseo Manuel de Lardizabal 420018San SebastianSpain

The effects of the long range electrostatic interaction in twisted bilayer graphene are described using the HartreeFock approximation. The results show a significant dependence of the band widths and shapes on electron filling,and the existence of broken symmetry phases at many densities, either valley/spin polarized, with broken sublattice symmetry, or both.

关键词： Graphene Twisted Interactions

Microstructure and strength of a tantalum-tungsten alloy after cold rolling from small to large strains

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Journal of Materials Science & Technology 2021年第24期83卷 34-48页

作者： Guoqiang Ma Darcy A.Hughes Andrew W.Godfrey Qiang Chen niels Hansena Guilin Wu College of Materials Science and Engineering Chongqing UniversityChongqing400044China Department of Mechanical Engineering Technical University of DenmarkDK-2800KgsLyngbyDenmark Fremont CAUSA Laboratory of Advanced Materials(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing100084China Southwest Technology and Engineering Research Institute Chongqing400039China Technical University of Denmark Risoe CampusDK-4000RoskildeDenmark Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing100083China

Microstructural evolution of a refractory tantalum-tungsten alloy(Ta-4%W)after cold rolling from small to large von-Mises strains(0.12-2.7)was quantitatively studied using transmission electron *** subdivision was observed to take place at two *** necessary boundaries nearly paralleling to slip planes enclosed volumes further divided by diffuse cells and by remnants of Taylor *** increasing strain,the diffuse cells evolved into clear incidental dislocation boundaries enclosing cells,while the Taylor lattices *** subdivision was thus intermediate between those observed in cell forming and in non-cell forming ***,the average misorientation angle across all boundaries increased while the average boundary spacing *** of the microstructural parameters at each strain level were found to exhibit universal scaling *** microstructural evolution was found closely linking to the observed high strength and strain hardening of this *** on measured microstructural parameters,the flow stress was calculated utilizing linearly addition of the strengthening by solutes,incidental dislocation boundaries(Taylor strengthening)and geometrically necessary boundaries(Hall-Petch equation).The relative contribution of each strength mechanism evolved with increasing strain and with microstructural evolution:solutes and friction stress dominated at small strains while boundaries dominated at larger *** strengths were in close agreement with experimental tension tests and demonstrated an unexpectedly high and continuous parabolic hardening without transition across this large strain range.

关键词： Tantalum Deformation microstructure Geometrically necessary boundaries Taylor lattices Flow stress

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

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Optoelectronics Letters 2008年第2期4卷 140-142页

作者： Robert Schmitt Tilo Pfeifer Frank Depiereux niels Knig Fraunhofer Institute for Production Technology (IPT) Steinbachstrasse 17 52074 Aachen Germany

Today, micro-system technology and the development of new MEMS (Micro-Electro-Mechanical Systems) are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.

关键词：纤维光干扰术光检测技术测量方法

Net absorption and liver metabolism of amino acids and heat production of portaldrained viscera and liver in multiparous sows during transition and lactation

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Journal of Animal Science and Biotechnology 2020年第2期11卷 424-439页

作者： Liang Hu niels Bastian Kristensen Lianqiang Che De Wu Peter Kappel Theil Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education Institute of Animal NutritionSichuan Agricultural UniversityNo.211Huimin RoadWenjiang DistrictChengduSichuan 611130People’s Republic of China Department of Animal Science Faculty of Science and TechnologyAarhus UniversityDK-8830 TjeleDenmark Present address:SEGES Danish Pig Research Centre DK-1609 CopenhagenDenmark

Background:Determination of nutrient requirements in the late gestating and lactating sows is essential to optimize sow *** objectives of the present study were to quantify amino acid(AA)fluxes and heat production across portal-drained viscera(PDV)and liver in multiparous sows during transition and ***:Eight second parity sows were fitted with indwelling catheters in the femoral artery and in the mesenteric,portal and hepatic *** hourly sets of blood samples were taken starting 0.5 h before feeding at−10,−3,+3,and+17 d in milk(DIM).Blood gases,plasma metabolites and apparent total tract digestibility(ATTD)of nutrients were ***:Feed intake,the ATTD of DM,energy,nitrogen,fat and crude fiber changed with DIM(P<0.001).Except for Glu,O2,and urea,all net portal fluxes were positive,and all were affected by DIM(P<0.05)and by sampling time(P<0.01).Compared with pre partum levels,net portal uptake of AA was 3-63%lower at+3 DIM but 40-100%higher at+17 *** portal fluxes of AA peaked at 1.5 to 2.5 h after feeding except for Glu,and they were positively correlated with changes in sow feed intake across *** net portal recovery was low for Met(49%),Thr(54%),and His(54%)and high for the remaining essential AA(63-69%)and none of them differed across *** hepatic uptake(*** oxidation)of Lys,Thr,Ile,Leu and Phe peaked at 0.5 to 2.5 h after feeding,whereas uptake of Trp,Val,and His was constant,while that of Met was close to ***:The net portal recovery was substantially lower for Met,Thr,and His than the remaining essential *** AA oxidation peaks 0.5 to 2.5 h after *** heat production in PDV and liver was approximately two-fold higher at peak lactation compared to other *** study suggests that lysine was the limiting AA in peak lactation but not in early lactation.

关键词： Gestation Heat production Lactation Net hepatic flux Net portal flux Sow

A geometric interpretation of the transition density of a symmetric Lévy process

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Science China Mathematics 2012年第6期55卷 1099-1126页

作者： JACOB niels KNOPOVA Victorya LANDWEHR Sandra SCHILLING RenéL. Department of Mathematics Swansea UniversitySingleton ParkSwansea SA28PPUK V.M.Glushkov Institute of Cybernetics NAS of Ukraine 03187KievUkraine Heinrich Heine University Düsseldorf German Diabetes Center at the Heinrich Heine University DüsseldorfLeibniz Center for Diabetes ResearchInstitute of Biometrics and EpidemiologyAuf'm Hennekamp 6540225 DüsseldorfGermany Institut für Mathematische Stochastik Technische Universität Dresden01062 DresdenGermany

We study for a class of symmetric Levy processes with state space R^n the transition density pt（x） in terms of two one-parameter families of metrics, （dt）t〉o and （δt）t〉o. The first family of metrics describes the diagonal term pt （0）; it is induced by the characteristic exponent ψ of the Levy process by dr（x, y） = √tψ（x - y）. The second and new family of metrics 6t relates to √tψ through the formula exp（-δ^2t（x,y））=F[e^-tψ/pt（0）]（x-y）,where Y denotes the Fourier transform. Thus we obtain the following ＂Gaussian＂ representation of the tran- sition density： pt（x） = pt（O）e^-δ^2t（x,0） where pt（O） corresponds to a volume term related to √tψ and where an ＂exponential＂ decay is governed by 5t2. This gives a complete and new geometric, intrinsic interpretation of pt（x）.

关键词： transition function estimates Levy processes metric measure spaces heat kernel bounds in-finitely divisible distributions self-reciprocal distributions

Influence of rolling friction on single spout fluidized bed simulation

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Particuology 2012年第5期10卷 582-591页

作者： Christoph Goniva Christoph Kloss niels G. Deen Johannes A.M.Kuipers Stefan Pirker Christian-Doppler Laboratory on Particulate Flow Modelling Johannes Kepler UniversityLinz Austria DCS Computing GmbH Linz Austria Christian-Doppler Laboratory on Particulate Flow Modelling Johannes Kepler UniversityLinz Austria Department of Chemical Engineering and Chemistry Eindhoven University of TechnologyEindhovenThe Netherlands Department of Chemical Engineering and Chemistry Eindhoven University of TechnologyEindhovenThe Netherlands Christian-Doppler Laboratory on Particulate Flow Modelling Johannes Kepler UniversityLinzAustria Institute of Fluid Mechanics and Heat Transfer Johannes Kepler UniversityLinzAustria

In this paper we study the effect of rolling friction on the dynamics in a single spout fluidized bed using Discrete Element Method （DEM） coupled to Computational Fluid Dynamics （CFD）. In a first step we neglect rolling friction and show that the results delivered by the open source CFD-DEM framework applied in this study agree with previous simulations documented in literature. In a second step we include a rolling friction sub-model in order to investigate the effect of particle non-sphericity. The influence of particle-particle as well as particle-wall rolling friction on the flow in single spout fluidized bed is studied separately. Adequate rolling friction model parameters are obtained using first principle DEM simulations and data from literature. Finally, we demonstrate the importance of correct modelling of rolling friction for coupled CFD-DEM simulations of spout fluidized beds. We show that simulation results can be improved significantly when applying a rolling friction model, and that experimental data from literature obtained with Positron Emission Particle Trackin~ fPEPT） technique can be satisfactorily reoroduced.

关键词： CFD-DEMOpen sourceRolling frictionSpout fluidized bedNon-sphericity

Upper gastrointestinal sensory-motor dysfunction in diabetes mellitus

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World Journal of Gastroenterology 2006年第18期12卷 2846-2857页

作者： Jingbo Zhao Jens Brφndum Frφkjaer Asbjφrn Mohr Drewes niels Ejskjaer Center of Excellence in Visceral Biomechanics and Pain Aalborg Hospital Sφndre Skovvej 15 DK-9000 Aalborg Denmark & Center for Sensory-Motor Interactions Department of Health Science Aalborg University Fredrik Bajers Vej 7 D-3 DK-9220 Aalborg Denmark Department of Medicine M (Diabetes & Endocrinology) Aarhus University Hospital Norrebrogade 44 DK 8000 Aarhus C Denmark

Gastrointestinal （GI） sensory-motor abnormalities are common in patients with diabetes mellitus and may involve any part of the GI tract. Abnormalities are frequently sub-clinical, and fortunately only rarely do severe and life-threatening problems occur. The pathogenesis of abnormal upper GI sensory-motor function in diabetes is incompletely understood and is most likely multi-factorial of origin. Diabetic autonomic neuropathy as well as acute suboptimal control of diabetes has been shown to impair GI motor and sensory function. Morphological and biomechanical remodeling of the GI wall develops during the duration of diabetes, and may contribute to motor and sensory dysfunction. In this review sensory and motility disorders of the upper GI tract in diabetes is discussed; and the morphological changes and biomechanical remodeling related to the sensory-motor dysfunction is also addressed.

关键词： Diabetes Esophagus Stomach Intestine Motility Pain Diabetic neuropathy Hyperglycemia Remodeling

Strategies for combating bacterial biofilm infections

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International Journal of Oral Science 2015年第1期7卷 1-7页

作者： Hong Wu Claus Moser Heng-Zhuang Wang niels Hφiby Zhi-Jun Song Department of Clinical Microbiology Rigshospitalet University Hospital of Copenhagen Department of International Health Immunology &Microbiology University of Copenhagen Department of Clinical Microbiology Slagelse Hospital

Formation of biofilm is a survival strategy for bacteria and fungi to adapt to their living environment, especially in the hostile environment. Under the protection of biofilm, microbial cells in biofilm become tolerant and resistant to antibiotics and the immune responses, which increases the difficulties for the clinical treatment of biofilm infections. Clinical and laboratory investigations demonstrated a perspicuous correlation between biofilm infection and medical foreign bodies or indwelling devices. Clinical observations and experimental studies indicated clearly that antibiotic treatment alone is in most cases insufficient to eradicate biofilm infections. Therefore, to effectively treat biofilm infections with currently available antibiotics and evaluate the outcomes become important and urgent for clinicians. The review summarizes the latest progress in treatment of clinical biofilm infections and scientific investigations, discusses the diagnosis and treatment of different biofilm infections and introduces the promising laboratory progress, which may contribute to prevention or cure of biofilm infections. We conclude that, an efficient treatment of biofilm infections needs a well-established multidisciplinary collaboration, which includes removal of the infected foreign bodies, selection of biofilm-active, sensitive and well-penetrating antibiotics, systemic or topical antibiotic administration in high dosage and combinations, and administration of anti-quorum sensing or biofilm dispersal agents.

关键词： antibiotic resistance antimicrobial treatments bacterial biofilm chronic infection

Engineering modes in optical fibers with metamaterial

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Frontiers of Optoelectronics 2009年第2期2卷 153-158页

作者： Min YAN niels Asger MORTENSEN Min QIU Department of Photonics Engineering Technical University of Denmark Department of Microelectronics and Applied Physics Royal Institute of Technology

In this paper, we report a preliminary theoretical study on optical fibers with fine material inclusions whose geometrical inhomogeneity is almost indistinguishable by the operating wavelength. We refer to such fibers as metamaterial optical fibers, which can conceptually be considered as an extension from the previously much publicized microstructured optical fibers. Metamaterials can have optical properties not obtainable in naturally existing materials, including artificial anisotropy as well as graded material properties. Therefore, incorporation of metamaterial in optical fiber designs can produce a new range of fiber properties. With a particular example, we will show how mode discrimination can be achieved in a multimode Bragg fiber with the help of metamaterial. We also look into the mean field theory as well as MaxwellGarnett theory for homogenizing a fine metamaterial structure to a homogeneous one. The accuracies of the two homogenization approaches are compared with fullstructure calculation.

关键词： optical fiber metamaterial Bragg fiber mode discrimination