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Towards implementation of alloy-specific thermo-fluid modelling for laser powder-bed fusion of mg alloys

Journal of magnesium and Alloys 2024年第6期12卷 2327-2344页

作者： mohammad Hoseini-Athar mikael Ersson peter Hedström Department of material Science and Engineering KTH Royal Institute of TechnologyStockholmSE-10044 Sweden

multi-physics thermo-fluid modeling has been extensively used as an approach to understand melt pool dynamics and defect formation as well as optimizing the process-related parameters of laser powder-bed fusion(L-PBf).However,its capabilities for being implemented as a reliable tool for material design,where minor changes in material-related parameters must be accurately captured,is still in *** the present research,first,a thermo-fluid computational fluid dynamics(CfD)model is developed and validated against experimental *** the predicted material properties of the pure mg and commercial ZK60 and WE43 mg alloys,parametric studies are done attempting to elucidate how the difference in some of the material properties,i.e.,saturated vapor pressure,viscosity,and solidification range,can influence the melt pool *** is found that a higher saturated vapor pressure,associated with the ZK60 alloy,leads to a deeper unstable keyhole,increasing the keyhole-induced porosity and evaporation mass *** viscosity and wider solidification range can increase the non-uniformity of temperature and velocity distribution on the keyhole walls,resulting in increased keyhole instability and formation of ***,the WE43 alloy showed the best behavior in terms of defect formation and evaporation mass loss,providing theoretical support to the extensive use of this alloy in *** summary,this study suggests an approach to investigate the effect of materials-related parameters on L-PBf melting and solidification,which can be extremely helpful for future design of new alloys suitable for L-PBf.

关键词： mg alloys Laser powder-bed fusion(L-PBf) melt pool dynamics Computational fluid dynamics fluid flow

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High-Performance and Large-Area Inverted Perovskite Solar Cells Based on NiO_(x) films Enabled with A Novel microstructure-Control Technology

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Energy & Environmental materials 2024年第1期7卷 153-159页

作者： Guibin Shen Xin Li Yuqin Zou Hongye Dong Dongping Zhu Yanglin Jiang Xin Ren Ng fen Lin peter müller-Buschbaum Cheng mu Key Laboratory of Advanced Light Conversion materials and Biophotonics Department of ChemistryRenmin University of ChinaBeijing 100872China Solar Energy Research Institute of Singapore(SERIS) National University of SingaporeSingapore 117574Singapore Physik-Department Lehrstuhl für Funktionelle MaterialienTechnische Universität MünchenJames-Franck-Straße 185748Garching Germany Heinz maier-Leibnitz Zentrum(mLZ) Technische Universität MünchenLichtenbergstr.185748Garching Germany

The improvement in the efficiency of inverted perovskite solar cells(PSCs)is significantly limited by undesirable contact at the NiO_(x)/perovskite *** this study,a novel microstructure-control technology is proposed for fabrication of porous NiO_(x)films using Pluronic P123 as the structure-directing agent and acetylacetone(AcAc)as the coordination *** synthesized porous NiO_(x)films enhanced the hole extraction efficiency and reduced recombination defects at the NiO_(x)/perovskite ***,without any modification,the power conversion efficiency(PCE)of the PSC with mAPbl_(3)as the absorber layer improved from 16.50%to 19.08%.moreover,the PCE of the device composed of perovskite Cs0.05(mA_(0.15)fA_(0.85))_(0.95)Pb(I_(0.85)Br_(0.15))_(3)improved from 17.49%to 21.42%.furthermore,the application of the fabricated porous NiO_(x)on fluorine-doped tin oxide(fTO)substrates enabled the fabrication of large-area PSCs(1.2 cm^(2))with a PCE of 19.63%.This study provides a novel strategy for improving the contact at the NiO_(x)/perovskite interface for the fabrication of high-performance large-area perovskite solar cells.

关键词： interfacial contact inverted and large-area perovskite solar cells photovoltaic materials porous NiO_(x)films renewable energy

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Identific tion of quantitative trait loci and associated candidate genes for pregnancy success in Angus–Brahman crossbred heifers

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Journal of Animal Science and Biotechnology 2024年第1期15卷 162-170页

作者： Quinn A.Hoorn Gabriel A.Zayas Eduardo E.Rodriguez Laura m.Jensen Raluca G.mateescu peter J.Hansen Department of Animal Sciences Donald Henry Barron Reproductive and Perinatal Biology Research Programand the Genetics InstituteUniversity of FloridaGainesvilleFLUSA School of Applied Systems Biology La Trobe UniversityBundooraVIC 3083Australia

Background In beef cattle, more than 50% of the energy input to produce a unit of beef is consumed by the female that produced the calf. Development of genomic tools to identify females with high genetic merit for reproductive function could increase the profitability and sustainability of beef *** Genome-wide association studies(GWAS) were performed using a single-step genomic best linear unbiased prediction approach on pregnancy outcome traits from a population of Angus–Brahman crossbred heifers. furthermore, a validation GWAS was performed using data from another farm. Heifers were genotyped with the Bovine GGP f250 array that contains 221,077 SNPs. In the discovery population, heifers were bred in winter breeding seasons involving a single round of timed artificial insemination(AI) followed by natural mating for 3 months. Two phenotypes were analyzed: pregnancy outcome to first-service AI(PAI;n = 1,481) and pregnancy status at the end of the breeding season(PEBS;n = 1,725). The heritability was estimated as 0.149 and 0.122 for PAI and PEBS, respectively. In the PAI model, one quantitative trait locus(QTL), located between 52.3 and 52.5 mb on BTA7, explained about 3% of the genetic variation, in a region containing a cluster of γ-protocadherin genes and SLC25A2. Other QTLs explaining between 0.5% and 1% of the genetic variation were found on BTA12 and 25. In the PEBS model, a large QTL on BTA7 was synonymous with the QTL for PAI, with minor QTLs located on BTA5, 9, 10, 11, 19, and 20. The validation population for pregnancy status at the end of the breeding season were Angus–Brahman crossbred heifers bred by natural mating. In concordance with the discovery population, the large QTL on BTA7 and QTLs on BTA10 and 12 were *** In summary, QTLs and candidate SNPs identified were associated with pregnancy outcomes in beef heifers, including a large QTL associated with a group of protocadherin genes. Confirmation of these associations

关键词： Beef cattle fertility GWAS QTL

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Generation of polarized electron beams through self-injection in the interaction of a laser with a pre-polarized plasma

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High Power Laser Science and Engineering 2024年第3期12卷 62-68页

作者： L.R.Yin X.f.Li Y.J.Gu N.Cao Q.Kong m.Büscher S.m.Weng m.Chen Z.m.Sheng Key Laboratory of Nuclear Physics and Ion-beam Application(moE) Institute of Modern PhysicsDepartment of Nuclear Science and TechnologyFudan UniversityShanghaiChina State Key Laboratory of High field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghaiChina SANKEN(Institute of Scientific and Industrial Research) Osaka UniversityOsakaJapan Sichuan Research Institute Shanghai Jiao Tong UniversityChengduChina peter Grünberg Institut(PGI-6) Forschungszentrum JülichJülichGermany Institut für Laser-und Plasmaphysik Heinrich-Heine-Universität DüsseldorfDüsseldorfGermany Key Laboratory for Laser Plasmas(moE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina Collaborative Innovation Center of IfSA Shanghai Jiao Tong UniversityShanghaiChina Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghaiChina

Polarized electron beam production via laser wakefield acceleration in pre-polarized plasma is investigated by particlein-cell *** evolution of the electron beam polarization is studied based on the Thomas±Bargmann±michel±Telegdi equation for the transverse and longitudinal self-injection,and the depolarization process is found to be influenced by the injection *** the case of transverse self-injection,as found typically in the bubble regime,the spin precession of the accelerated electrons is mainly influenced by the ***,in the case of longitudinal injection in the quasi-1D regime(for example,*** et al.,***.110,135002(2013)),the direction of electron spin oscillates in the laser *** the electrons move around the laser axis,the net influence of the laser field is nearly zero and the contribution of the wakefield can be ***,an ultra-short electron beam with polarization of 99%can be obtained using longitudinal self-injection.

关键词： laser wakefield acceleration longitudinal self-injection particle-in-cell simulation polarized electron beam

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The Origin of the flat Rotation Curves in Spiral Galaxies: The Hidden Roles of Glitching SmDEOs and Emission of Gravitational Waves

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Journal of modern Physics 2024年第10期15卷 1523-1542页

作者： Ahmad A. Hujeirat peter Berczik Interdisciplinary Center for Scientific Computing Faculty of Physics and Astronomy University of Heidelberg Heidelberg Germany main Astronomical Observatory Kyiv Ukraine

Supermassive DEOs (SmDEOs) are cosmologically evolved objects made of irreducible incompressible supranuclear dense superfluids: The state we consider to govern the matter inside the cores of massive neutron stars. These cores are practically trapped in false vacua, rendering their detection by outside observers impossible. Based on massive parallel computations and theoretical investigations, we show that SmDEOs at the centres of spiral galaxies that are surrounded by massive rotating torii of normal matter may serve as powerful sources for gravitational waves carrying away roughly 1042 erg/s. Due to the extensive cooling by GWs, the SmDEO-Torus systems undergo glitching, through which both rotational and gravitational energies are abruptly ejected into the ambient media, during which the topologies of the embedding spacetimes change from curved into flatter ones, thereby triggering a burst gravitational energy of order 1059 erg. Also, the effects of glitches found to alter the force balance of objects in the Lagrangian-L1 region between the central SmDEO-Torus system and the bulge, enforcing the enclosed objects to develop violent motions, that may explain the origin of the rotational curve irregularities observed in the innermost part of spiral galaxies. Our study shows that the generated GWs at the centres of galaxies, which traverse billions of objects during their outward propagations throughout the entire galaxy, lose energy due to repeatedly squeezing and stretching the objects. Here, we find that these interactions may serve as damping processes that give rise to the formation of collective forces f∝m(r)/r, that point outward, endowing the objects with the observed flat rotation curves. Our approach predicts a correlation between the baryonic mass and the rotation velocities in galaxies, which is in line with the Tully-fisher relation. The here-presented self-consistent approach explains nicely the observed rotation curves without invoking dark matter or mo

关键词： General Relativity: Black Holes Neutron Stars Quantum fields: QCD Condensed matter Incompressibility Superfluidity Cosmology: Galaxy formation Spiral Galaxies Dark matter Rotation Curves

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Niche differentiation among facultative filter feeders: Insights from invasive Ponto-Caspian mysids

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Current Zoology 2024年第4期70卷 513-521页

作者： Péter Borza Varsha Rani Csaba f.Vada Institute of Aquatic Ecology Centre for Ecological ResearchKarolina ut 29.1113 BudapestHungary Doctoral School of Biology Institute of BiologyEotvos Lorand UniversityPazmany Péter sétany 1/C1117 BudapestHungary

The degree of dietary specialization has a fundamental impact on the ecological function and interactions of suspension *** niche differentiation by food particle size is common among obligate suspension feeders,its role is not evident in facultative *** this study,we aimed at providing new insights on the matter by focusing on sympatric mysid *** mysids use different mechanisms for raptorial and filter-feeding,they represent a more adequate model system than for example,the more extensively studied *** made morpholog-ical measurements on the 4 coexisting invasive Ponto-Caspian mysid species to determine the areas and mesh sizes of their *** also quantified their clearance rates on the microalga Cryptomonas *** a laboratory experiment to reveal how morphological differences manifest in their overall filtering *** found relatively small but consistent differences in the primary filter area among the species,indicating that morphological constraints due to the enclosed position of the setae might limit the possibility for *** primary filter mesh sizes were small in all 4 species(0.69-2.73μm)with moderate but consistent intraspecific differences,suggesting that the benefit of being able to capture small particles might outweigh the pressure for *** observed clearance rates were in accordance with the morphological characteristics of the species,highlighting that auxiliary filters(present in one of the species,Limnomysis benedeni)are needed to increase filtering capacity *** study confirmed that food particle size can contribute to the niche differentiation of facultative filter feeders,but also indicated that they can tolerate a higher overlap than obligate *** observed differences were related to the habitat preferences and predatory potentials of the species,suggesting that complementarity among the different niche axes might further facilitate theircoexistence.

关键词： clearance rate coexistence filter area filtermesh size.

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Volcanic Risk Perception and Coping Strategies from mounts Cameroon and Nyiragongo Eruptions, Central Africa: A Comparative Analysis

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Journal of Geoscience and Environment Protection 2024年第6期12卷 161-189页

作者： mabel N. Wantim Innocent Bradriyo Asong f. Zisuh Louis m. Balgawa mero Yannah Katcho Karume Nde-fon peter Bih Amban Nchini L. Wayih Emmanuel V. Yenshu Samuel N. Ayonghe Unit of Disaster Risk management Department of Environmental Science University of Buea Buea Cameroon Observatoire Volcanologique de Goma (OVG) Goma Democratic Republic of the Congo Institute of Geological and mining Research (IRGm) Yaounde Cameroon faculty of Health Sciences University of Buea Buea Cameroon faculty of Social and management Sciences University of Buea Buea Cameroon

Approximately 2,000,000 people are exposed to volcanic risks in communities situated at the flanks of mounts Cameroon (mC) and Nyiragongo (mN) volcanoes in Central Africa. This study therefore sought to investigate risk perception from four previous eruptions of mC, namely the 1959, 1982, 1999, and 2000 eruptions;and two previous eruptions of mN: 1977 and 2002. The study was initiated with co-design workshops held with major stakeholders in the cities of Buea and Goma at the flanks of mC and mN, respectively, in 2017, to develop the research objectives for the study. A non-random questionnaire survey was later conducted within 14 and 15 communities in Buea and Goma respectively, on the effects, perceived risks, and coping strategies for the chosen eruptions. Three age groups (18 - 30, 31 - 45 and >45 years) and gender (male and female) were considered. The population at the flanks of both volcanoes cited scientific and indigenous factors to be responsible for eruptions from these volcanoes. At mC and mN, ≥45% of the sampled participants (with a higher female population) perceived that the sampled eruptions posed a very high risk to the population. In terms of the effects, the age group of 18 - 30 was the least knowledgeable. In terms of direct effect on persons, over 90% of participants at mC and mN attested that they were overcome by fear/panic. On measures to cope with any likely eruption, the following order was established at the flanks of both volcanoes: sensitization of population, use of religious (prayers) and of traditional/indigenous strategies. In terms of future coping strategies, while the males at mC maintained sensitization as the favourite option, 62% of the males at mN opted for traditional/indigenous strategies. The female population at both mC and mN showed a higher preference for religious strategies like prayers.

关键词： Risk Perception mount Cameroon mount Nyiragongo Indigenous Buea Goma

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Light metal compound casting

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Science China(Technological Sciences) 2009年第1期52卷 46-51页

作者： Konrad J. m. PAPIS Joerg f. LOEffLER peter J. UGGOWITZER ETH Zurich Laboratory of Metal Physics and Technology Wolfgang-Pauli-Str. 10

‘Compound casting’simplifies joining processes by directly casting a metallic melt onto a solid metal substrate. A continuously metallurgic transition is very important for industrial applications, such as joint structures of spaceframe constructions in transport industry. In this project, ‘compound casting’ of light metals is investigated, aiming at weight-saving. The substrate used is a wrought aluminium alloy of type AA5xxx, containing magnesium as main alloying element. The melts are aluminium alloys, containing various alloying elements (Cu, Si, Zn), and magnesium. By replacing the natural oxygen layer with a zinc layer, the inherent wetting difficulties were avoided, and compounds with flawless interfaces were successfully produced (no contraction defects, cracks or oxides). Electron microscopy and EDX investigations as well as optical micrographs of the interfacial areas revealed their continu- ously metallic constitution. Diffusion of alloying elements leads to heat-treatable microstructures in the vicinity of the joining interfaces in Al-Al couples. This permits significant variability of mechanical properties. Without significantly cutting down on wettability, the formation of low-melting intermetallic phases (Al3mg2 and Al12mg17 ImPs) at the interface of Al-mg couples was avoided by applying a protective coating to the substrate.

关键词： compound casting aluminium alloys magnesium alloys interface structure

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Control of stem cell fate by engineering their micro and nanoenvironment

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World Journal of Stem Cells 2015年第1期7卷 37-50页

作者： michelle f Griffin peter E Butler Alexander m Seifalian Deepak m Kalaskar UCL Division of Surgery and Interventional Science Centre for Nanotechnology and Regenerative Medicine University College London London NW3 2PF United Kingdom Department of Plastic and Reconstructive Surgery Royal Free Hampstead NHS Trust Hospital London NW3 2PF United Kingdom

Stem cells are capable of long-term self-renewal and differentiation into specialised cell types, making them an ideal candidate for a cell source for regenerative medicine. The control of stem cell fate has become a major area of interest in the field of regenerative medicine and therapeutic intervention. Conventional methods of chemically inducing stem cells into specific lineages is being challenged by the advances in biomaterial technology, with evidence highlighting that material properties are capable of driving stem cell fate. materials are being designed to mimic the clues stem cells receive in their in vivo stem cell niche including topographical and chemical instructions. Nanotopographical clues that mimic the extracellular matrix(ECm) in vivo have shown to regulate stem cell differentiation. The delivery of ECm components on biomaterials in the form of short peptides sequences has also proved successful in directing stem cell lineage. Growth factors responsible for controlling stem cell fate in vivo have also been delivered via biomaterials to provide clues to determine stem cell differentiation. An alternative approach to guide stem cells fate is to provide genetic clues including delivering DNA plasmids and small interfering RNAs via scaffolds. This review, aims to provide an overview of the topographical, chemical and molecular clues that biomaterials can provide to guide stem cell fate. The promising features and challenges of such approaches will be highlighted, to provide directions for future advancements in this exciting area of stem cell translation for regenerative medicine.

关键词： Biomaterials Scaffold Stem cells Surfacetopography Tissue engineering

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Using potential distributions to explore environmental correlates of bat species richness in southern Africa： Effects of model selection and taxonomy

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Current Zoology 2013年第3期59卷 279-293页

作者： m. Corrie SCHOEmAN f. P. D. (Woody) COTTERILL peter J. TAYLOR Ara mONADJEm School of Life Sciences University of KwaZulu-Natal Westville Campus Durban 4000 South Africa Africa Earth Observatory Network (AEON) Geoecodynamics Research Hub c/o Department of Botany and Zoology University of Stellenbosch Stellenbosch 7602 South Africa Department of Ecology and Resource management School of Environmental Sciences University of Venda Thohoyandou 0950 South Africa All Out Africa Research Unit Department of Biological Sciences University of Swaziland Private Bag 4 Kwaluseni Swaziland mammal Research Institute Department of Zoology & Entomology University of Pretoria Private Bag 20 Hatfield 0028 Pretoria South Africa

We tested the prediction that at coarse spatial scales, variables associated with climate, energy, and productivity hy- potheses should be better predictor（s） of bat species richness than those associated with environmental heterogeneity. Distribution ranges of 64 bat species were estimated with niche-based models informed by 3629 verified museum specimens. The influence of environmental correlates on bat richness was assessed using ordinary least squares regression （OLS）, simultaneous autoregressive models （SAR）, conditional autoregressive models （CAR）, spatial eigenvector-based filtering models （SEVm）, and Classification and Regression Trees （CART）. To test the assumption of stationarity, Geographically Weighted Regression （GWR） was used. Bat species richness was highest in the eastern parts of southern Africa, particularly in central Zimbabwe and along the western border of mozambique. We found support for the predictions of both the habitat heterogeneity and climate/productivity/energy hypothe- ses, and as we expected, support varied among bat families and model selection. Richness patterns and predictors of miniopteridae and Pteropodidae clearly differed from those of other bat families. Altitude range was the only independent variable that was sig- nificant in all models and it was most often the best predictor of bat richness. Standard coefficients of SAR and CAR models were similar to those of OLS models, while those of SEVm models differed. Although GWR indicated that the assumption of stationa- rity was violated, the CART analysis corroborated the findings of the curve-fitting models. Our results identify where additional data on current species ranges, and future conservation action and ecological work are needed.

关键词： Chiroptera macroecology Niche-based models Spatial models Species richness

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