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Multi-material additive manufacturing-functionally graded materials by means of laser remelting during laser powder bed fusion

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Frontiers of Mechanical Engineering 2023年第4期18卷 183-193页

作者： Alexander schmidt Felix JENSCH Sebastian HÄRTEL Chair of Hybrid Manufacturing Brandenburg University of TechnologyCottbus 03046Germany

Many processes may be used for manufacturing functionally graded *** them,additive manufacturing seems to be predestined due to near-net shape manufacturing of complex geometries combined with the possibility of applying different materials in one *** adjusting the powder composition of the starting material layer by layer,a macroscopic and step-like gradient can be *** further improve the step-like gradient,an enhancement of the in-situ mixing degree,which is limited according to the state of the art,is *** this paper,a novel technique for an enhancement of the in-situ material mixing degree in the melt pool by applying laser remelting(LR)is *** effect of layer-wise LR on the formation of the interface was investigated using pure copper and low-alloy steel in a laser powder bed fusion *** cross-sectional selective electron microscopic analyses were carried *** applying LR,the mixing degree was enhanced,and the reaction zone thickness between the materials was ***,an additional copper and iron-based phase was formed in the interface,resulting in a smoother gradient of the chemical composition than the case without *** Marangoni convection flow and thermal diffusion are the driving forces for the observed effect.

关键词： multi-material additive manufacturing(MMAM) functionally graded materials(FGMs) laser powder bed fusion(L-PBF) laser remelting(LR) pure copper

Enhanced thermal transport across monolayer MoS2

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Nano Research 2018年第4期11卷 2173-2180页

作者： Miguel Goni Jia Yang Aaron J. schmidt 110 Cummington mall Mechanical Engineering Boston University Boston 02115 USA

Characterizing the thermal properties of MoS2 is important for the design of electronic devices based on this material. We used frequency domain thermoreflectance to study the cross-plane thermal transport in mechanically exfoliated MoS2 samples supported on SiO2 and muscovite mica substrates. The thickness of MoS2 ranged between one and five layers, and the MoS2 layers were sandwiched between a metal layer and the substrate. In the case of mica, heat transport into the substrate remained the same whether or not a monolayer of MoS2 was present, whereas, for SiO2, heat transport was reduced by surface roughness. We observed a significant improvement in heat transport across monolayer MoS2 as compared to few layer MoS2. For MoS2 on SiO2, the effective thermal interface conductance was improved by more than three times if a monolayer was used. For MoS2 on mica, the thermal interface conductance was approximately two times better for monolayer MoS2. This implies that monolayer MoS2 has superior thermal properties and can be used in electronic devices as an intermediate layer between two materials. Additionally, we also report on the measurement of anisotropic thermal conductivity in bulk MoS2 and mica.

关键词： MoS2 cross plane thermal transport,frequency domain thermoreflectance,muscovite mica,SiO2

Modelling of dust emissions induced by flow over stockpiles and through packed beds

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Particuology 2021年第6期19卷 55-63页

作者： Daniel Schulz Nadja Schwindt Eberhard schmidt Harald Kruggel-Emden Technische Universitat Berlin Chair of Mechanical Process Engineering and Solids ProcessingEmst-Reuter-Platz 1D-10587 BerlinGermany University of Wuppertal Institute of Particle TechnologyRainer-Gruenter-StrGeb.FFD-42119 WuppertalGermany

Dust emissions during storage of non-moving bulk materials are studied with a numerical *** model relies on a contact-model-free Discrete Element Method(DEM)to model the bulk particle-fluid interaction and the dust removal coupled with Computational Fluid Dynamics(CFD)to model the gas and the dust phase in a multiphase ***,two storage scenarios are considered:a flown through packed bed and a flown over *** the first,the performed simulations reveal that the dust discharge can be correlated with the passing fluid pressure *** the second,a parameter study of factors influencing the dust emissions is *** parameters discussed are the stockpile size,the gas velocity,the slope angle,the particle diameter and the shape of the stockpile,taking into account conical and truncated conical *** release correlations are obtained for both scenarios,which reflect very well the obtained numerical results.

关键词： Computational Fluid Dynamics(CFD) Discrete Element Method(DEM) Dust release correlations Stockpile emissions Packed bed emissions

Influence of non-Hermitian mode topology on refractive index sensing with plasmonic waveguides

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Photonics Research 2022年第3期10卷 719-730页

作者： Alessandro Tuniz Markus A.schmidt Boris T.Kuhlmey Institute of Photonics and Optical Science(IPOS) School of PhysicsThe University of SydneyNSW 2006Australia The University of Sydney Nano Institute(Sydney Nano) The University of SydneyNSW 2006Australia Leibniz Institute of Photonic Technology(IPHT Jena) 07745 JenaGermany Abbe Center of Photonics and Faculty of Physics Friedrich-Schiller-University Jena07743 JenaGermany

We evaluate the sensing properties of plasmonic waveguide sensors by calculating their resonant transmission spectra in different regions of the non-Hermitian eigenmode *** elucidate the pitfalls of using modal dispersion calculations in isolation to predict plasmonic sensor performance,which we address by using a simple model accounting for eigenmode excitation and *** transmission calculations show that resonant wavelength and spectral width crucially depend on the length of the sensing region,so that no single criterion obtained from modal dispersion calculations alone can be used as a proxy for ***,we find that the optimal detection limits occur where directional coupling is supported,where the narrowest spectra *** narrow spectral features can only be measured by filtering out all higher-order modes at the output,e.g.,via a single-mode *** calculations also confirm a characteristic square root dependence of the eigenmode splitting with respect to the permittivity perturbation at the exceptional point,which we show can be identified through the sensor beat length at *** work provides a convenient framework for designing and characterizing plasmonic waveguide sensors when comparing them with experimental measurements.

关键词： waveguide mode narrow

From gene editing to genome engineering: restructuring plant chromosomes via CRISPR/Cas

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aBIOTECH 2020年第1期1卷 21-31页

作者： Carla schmidt Patrick Schindele Holger Puchta Botanical Institute Karlsruhe Institute of TechnologyPOB 698076133 KarlsruheGermany

In the last years,tremendous progress has been achieved in the field of gene editing in *** the induction of single site-specific double-strand breaks(DSBs),the knockout of genes by non-homologous end joining has become routine in many plant ***,the efficiency of inducing pre-planned mutations by homologous recombination has also been improved ***,very little effort has been undertaken until now to achieve more complex changes in plant genomes by the simultaneous induction of several *** reports have been published on the efficient induction of ***,the induction of intrachromosomal inversions and interchromosomal recombination by the use of CRISPR/Cas has only recently been *** this review,we want to sum up these results and put them into context with regards to what is known about natural chromosome rearrangements in ***,we review the recent progress in CRISPR/Cas-based mammalian chromosomal rearrangements,which might be inspiring for plant *** the long run,the controlled restructuring of plant genomes should enable us to link or break linkage of traits at will,thus defining a new area of plant breeding.

关键词： Chromosomal rearrangements CRISPR/Cas Genome engineering Inversion Translocation

Dust in the Jupiter system outside the rings

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Astrodynamics 2019年第1期3卷 17-29页

作者： Xiaodong Liu Jürgen schmidt Astronomy Research Unit University of OuluOulu90014Finland

Jupiter is one of the major targets for planetary exploration,and dust in the Jovian system is of great interest to researchers in the field of planetary *** this paper,we review the five dust populations outside the ring system:grains in the region of the Galilean moons,potential dust from plumes on Europa,Jovian stream particles,particles in the outer region of the Jovian system ejected from the irregular satellites,and dust in the region of the Trojan *** physical environment for the dust dynamics is described,including the gravity,the magnetic field and the plasma *** each population,the dust sources are described,and the relevant perturbation forces are *** and results from modeling are reviewed,and the distributions of the individual dust populations are *** understanding of the Jovian dust environment allows to assess the dust hazard to spacecraft,and to characterize the material exchange between the Jovian moons,their surface properties and distribution of non-icy constituents.

关键词： cicumplanetary dust interplanetary dust stream particles planetary rings Europa plume Jupiter Galilean moons Trojan asteroids meteoroids space debris

BETWEEN BYZANTINE AND MUSLIM *** ECONOMIC RESOURCES FOR AN EMBRYONIC EMPIRE

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Journal of Ancient Civilizations 2020年第2期35卷 241-266,268页

作者： Stefanie schmidt University of Zurich/FU Berlin

Building an Empire involves more than just the occupation of foreign *** needs an economic strategy to sustainably exploit the resources of a country and to keep resistance among the inhabitants to a *** paper aims at exploring how,after the conquest of Egypt in 642,Muslims mobilized economic resources,to what extent they integrated former Byzantine levy systems,and what incentives they created in order to guarantee the economy's continued productivity.

关键词： occupation guarantee continued

The relaxin peptide family–potential future hope for neuroprotective therapy? A short review

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Neural Regeneration Research 2018年第3期13卷 402-405页

作者： Marius Nistor Martin schmidt René Schiffner Department of Neurology Jena University Hospital Friedrich Schiller University Jena Germany Orthopaedic Department Jena University Hospital Friedrich Schiller University Jena Germany Institute for Biochemistry II Jena University Hospital Friedrich Schiller University Jena Germany

Since its discovery in the 1920’s the relaxin peptide hormone family has not only grown in number to now seven members （relaxin-1, relaxin-2, relaxin-3, insulin-like peptide （INSL） 3, INSL4, INSL5 and INSL6）, but ever more effects, suchs as vasodilatory, angiogenic, anti-apoptopic, anti-fibriotic and anti-inflammatory, have been linked to them. While relaxin-2 has mainly been investigated in the context of cardiac protection, most comprehensively in the RELAX-AHF and RELAX AHF2 studies, a small number of studies have furthermore assessed the potential neuroprotective effects of especially relaxin-2 and other members of the relaxin family. In this short review we summarise and discuss recent efforts to utilize relaxin hormones for neuroprotection and point out potential future fields of research and translational applications. While many questions still need to be answered, the promising results of the available studies definitely warrant future well-designed studies on neuroprotection by relaxin peptides.

关键词： relaxin relaxin-2 neuroprotection stroke hemorrhagic shock cerebral

EARLY ROMAN SYENE(1ST TO 2ND CENTURY)–A GATE TO THE RED SEA?

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Journal of Ancient Civilizations 2021年第2期36卷 269-297,301页

作者： Stefanie schmidt FU Berlin

Due to its strategic position at the First Cataract,Syene(modern Aswān)obtained a central position in transregional trade at Egypt’s border to the Meroitic *** finds of Aswān pottery throughout Egypt and the Arabian Sea demonstrate,moreover,that Syene’s economic outreach went far beyond a mere cross-border *** on a new discussion of a well-known inscription by a paralēmptēs of the Red Sea and an ostracon from Pselkis,this paper aims at exploring to what extent early Roman Syene was also involved in trade carried out in the Red Sea and beyond.

关键词： border beyond Egypt