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A discrete contact model for complex arbitrary-shaped convex geometries

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Particuology 2023年第9期80卷 180-191页

作者： Jan e.Marquardt Ulrich J.Römer Hermann Nirschl Mathias J.Krause Lattice Boltzmann Research Group Karlsruhe Institute of TechnologyStraße am Forum 8Karlsruhe76131Germany Institute for Mechanical Process engineering and Mechanics Karlsruhe Institute of TechnologyStraße am Forum 8Karlsruhe76131Germany Institute of engineering Mechanics Karlsruhe Institute of TechnologyKaiserstraße 10Karlsruhe76131Germany Institute for Applied and Numerical Mathematics Karlsruhe Institute of TechnologyEnglerstraße 2Karlsruhe76131Germany

The shape of particles has a significant influence on the behavior of suspensions,as the particle-fluid,particle-particle,and particle-wall interactions depend on ***,the simultaneous consideration of complex particle shapes and four-way coupling remains a major *** is mainly due to a lack of suitable contact *** models for complex shapes have been proposed in literature,and most limit the accuracy of the particle-fluid *** this reason,this paper presents a novel contact model for complex convex particle shapes for use with partially saturated methods,in which we propose to obtain necessary contact properties,such as the indentation depth,by a discretization of the contact *** goal of the proposed model is to enable comprehensive and accurate studies of particulate flows,especially with high volume fractions,that lead to new insights and contribute to the improvement of existing industrial *** ensure correctness and sustainability,we validate the model extensively by studying cases with and without *** the latter case,we use the homogenized lattice Boltzmann *** provided investigations show a great agreement of the proposed discrete contact model with analytical solutions and the literature.

关键词： Partially saturated cells method Homogenized lattice Boltzmann method Arbitrarily shaped particle Discrete contact model Particle-resolved simulation OpenLB

starving out brain tumors: a reprogrammed lysine catabolism serves as a novel target for glioblastoma treatment

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signal Transduction and Targeted Therapy 2023年第11期8卷 5136-5138页

作者： Désirée Gül Oliver H.Krämer Christoph Reinhardt Molecular and Cellular Oncology Department of Otorhinolaryngology Head and Neck SurgeryUniversity Medical CenterJohannes Gutenberg-University Mainz55131MainzGermany Department of Toxicology University Medical CenterJohannes Gutenberg-University Mainz55131 MainzGermany Center for Thrombosis and Hemostasis(CTH) University Medical CenterJohannes Gutenberg-University MainzLangenbeckstrasse 155131 MainzGermany German Center for Cardiovascular Research(DZHK) Partner Site Rhine-MainUniversity Medical CenterJohannes Gutenberg-University Mainz55131 MainzGermany

In their recent study published in Nature,Yuan and colleagues enlighten the role of histone lysine crotonylation(Kcr)in brain tumor *** report a novel lysine-dependent mechanism through which glioblastoma stem cells m... 详细信息

关键词： glioblastoma interferon treatment

Proteome analysis of human mesenchymal stem cells undergoing chondrogenesis when exposed to the products of various magnesium-based materials degradation

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Bioactive Materials 2019年第1期4卷 168-188页

作者： Adela Helvia Martínez sánchez Maryam Omidi Marcus Wurlitzer Marceline Manka Fuh Frank Feyerabend Hartmut schlüter Regine Willumeit-Römer Bérengère J.C.Luthringer Division of Metallic Biomaterials Institute of Material ResearchHelmholtz-Zentrum GeesthachtMax Planck Strasse 121502GeesthachtGermany Institute of Clinical Chemistry and Laboratory Medicine Mass Spectrometric ProteomicsUniversity Medical Center Hamburg-EppendorfMartinistraße 5220246HamburgGermany

Treatment of physeal fractures(15%–30%of all paediatric fractures)remains a challenge as in approximately 10%of the cases,significant growth disturbance may *** Magnesium-based implants represent a strategy to minimize damage(i.e.,load support until bone healing without second surgery).Nevertheless,the absence of harmful effects of magnesium-implants and their degradation products on the growth plate should be ***,the proteome of human mesenchymal stem cells undergoing chondrogenesis was evaluated when exposed to the products of various Magnesium-based materials *** results of this study indicate that the materials induced regulation of proteins associated with cell chondrogenesis and cartilage formation,which should be beneficial for cartilage regeneration.

关键词： stem cells differentiation Chondrogenesis Proteomics Magnesium biomaterial Biodegradable implant

Zinc in plants:Integrating homeostasis and biofortification

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Molecular Plant 2022年第1期15卷 65-85页

作者： Camilla stanton Dale sanders Ute Krämer Dorina Podar John Innes Centre Colney LaneNorwichNR47UHUK Molecular Genetics and Physiology of Plants Ruhr University Bochum44801 BochumGermany Department of Molecular Biology and Biotechnology and Centre for systems Biology Biodiversity and BioresourcesBabes-Bolyai University400084 Cluj-NapocaRomania

Zinc plays many essential roles in *** a strong Lewis acid that lacks redox activity under environ-mental and cellular conditions,the Zn2+cation is central in determining protein structure and catalytic function of nearly 10%of most eukaryotic *** specific functions of zinc have been elucidated at a molecular level in a number of plant proteins,wider issues abound with respect to the acquisition and distribution of zinc by *** important challenge is to understand how plants balance between Zn supply in soil and their own nutritional requirement for zinc,particularly where edaphic factors lead to a lack of bioavailable zinc or,conversely,an excess of zinc that bears a major risk of *** are the ultimate source of zinc in the human diet,and human Zn deficiency accounts for over 400000 deaths ***,we review the current understanding of zinc homeostasis in plants from the molecular and physiological *** provide an overview of approaches pursued so far in Zn biofortification of ***,we outline a"push-pull"model of zinc nutrition in plants as a simplifying *** summary,this review discusses avenues that can potentially deliver wider bene-fits for both plant and human Zn nutrition.

关键词： zinc biofortification Zn homeostasis cereals Arabidopsis barley wheat rice

Computational modelling of magnesium degradation in simulated body fluid under physiological conditions

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Journal of Magnesium and Alloys 2022年第4期10卷 965-978页

作者： Berit Zeller-Plumhoff Tamadur AlBaraghtheh Daniel Höche Regine Willumeit-Römer Helmholtz-Zentrum hereon GmbH Institute of Metallic BiomaterialsMax-Planck-Straße 1Geesthacht21502Germany Helmholtz-Zentrum hereon GmbH Institute of Surface ScienceMax-Planck-Straße 1Geesthacht21502Germany

Magnesium alloys are highly attractive for the use as temporary implant materials, due to their high biocompatibility and ***, the prediction of the degradation rate of the implants is difficult, therefore, a large number of experiments are required. Computational modelling can aid in enabling the predictability, if sufficiently accurate models can be established. This work presents a generalized model of the degradation of pure magnesium in simulated body fluid over the course of 28 days considering uncertainty aspects. The model includes the computation of the metallic material thinning and is calibrated using the mean degradation depth of several experimental datasets simultaneously. Additionally, the formation and precipitation of relevant degradation products on the sample surface is modelled, based on the ionic composition of simulated body fluid. The computed mean degradation depth is in good agreement with the experimental data(NRMse=0.07). However, the quality of the depth profile curves of the determined elemental weight percentage of the degradation products differs between elements(such as NRMse=0.40 for phosphorus vs. NRMse=1.03 for magnesium). This indicates that the implementation of precipitate formation may need further developments. The sensitivity analysis showed that the model parameters are correlated and which is related to the complexity and the high computational costs of the model. Overall, the model provides a correlating fit to the experimental data of pure Mg samples of different geometries degrading in simulated body fluid with reliable error estimation.

关键词： Biodegradation Magnesium Computational modelling Corrosion Uncertainty quantification Kriging

extrusion-based additive manufacturing of Mg-Zn alloy scaffolds

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Journal of Magnesium and Alloys 2022年第9期10卷 2491-2509页

作者： J.Dong N.Tümer M.A.Leeflang P.Taheri L.e.Fratila-Apachitei J.M.C.Mol A.A.Zadpoor J.Zhou Department of Biomechanical engineering Delft University of TechnologyDelft 2628 CDthe Netherlands Department of Materials science and engineering Delft University of TechnologyDelft 2628 CDthe Netherlands

Porous biodegradable Mg and its alloys are considered to have a great potential to serve as ideal bone *** recent progress in additive manufacturing(AM) has prompted its application to fabricate Mg scaffolds with geometrically ordered porous *** AM,followed by debinding and sintering,has been recently demonstrated as a powerful approach to fabricating such Mg scaffolds,which can avoid some crucial problems encountered when applying powder bed fusion AM ***,such pure Mg scaffolds exhibit a too high rate of in vitro *** the present research,alloying through a pre-alloyed Mg-Zn powder was ultilized to enhance the corrosion resistance and mechanical properties of AM geometrically ordered Mg-Zn scaffolds *** in vitro biodegradation behavior,mechanical properties,and electrochemical response of the fabricated Mg-Zn scaffolds were ***,the response of preosteoblasts to these scaffolds was systematically evaluated and compared with their response to pure Mg *** Mg-Zn scaffolds with a porosity of 50.3% and strut density of 93.1% were composed of the Mg matrix and MgZn2second phase *** in vitro biodegradation rate of the Mg-Zn scaffolds decreased by 81% at day 1,as compared to pure Mg *** 28 days of static immersion in modified simulated body fluid,the corrosion rate of the Mg-Zn scaffolds decreased from 2.3± 0.9 mm/y to 0.7±0.1 mm/*** yield strength and Young’s modulus of the Mg-Zn scaffolds were about 3 times as high as those of pure Mg scaffolds and remained within the range of those of trabecular bone throughout the biodegradation *** culture of MC3T3-e1 preosteoblasts in Mg-Zn extracts indicated favorable *** direct cell culture,some cells could spread and form filopodia on the surface of the Mg-Zn ***,this study demonstrates the great potential of the extrusion-based AM Mg-Zn scaffolds to be further develo

关键词： Additive manufacturing Material extrusion Magnesium-zinc alloy Porous scaffold Biodegradation

synergistic effect of hybrid Himalayan Nettle/Bauhinia-vahlii fibers on physico-mechanical and sliding wear properties of epoxy composites

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Defence Technology（防务技术） 2020年第4期16卷 762-776页

作者： sandeep Kumar KKsmer Brijesh Gangil Vinay Kumar Patel Department of Mechanical engineering S.O.E.T.H.N.B.Garhwal UniversitySrinagar-Garhwal246174UttarakhandIndia Department of Mechanical engineering Govind Ballabh Pant Institute of Engineering and Technology GhurdauriPauri Garhwal246001UttarakhandIndia

The cellulosic bast fibers are recognized as a justifiable and biodegradable substitute for producing moderate strength polymer composite materials because of their characteristics of renewability,ecofriendliness,and higher specific *** the aim of this research work is to fabricate Himalayan bast fibers(Nettle fiber(NF)/bauhinia vahlii fiber(BF)) based mono/hybrid epoxy composites at varying weight percentage of 2-6 wt% and evaluate the physical(void fraction and water absorption),mechanical(tensile strength,flexural strength,hardness) and sliding wear properties of as-fabricated *** 6 wt% NBF reinforced composites exhibited higher mechanical properties as compared to NF and BF composites with tensile strength of 34.04 MPa,flexural strength of 42.45 MPa,and hardness of 37.01 Hv *** influence of various control factors(sliding velocity,NF/BF/NBF contents,normal load and sliding distance) on specific sliding wear rate of composites was evaluated by Taguchi(three factors at three levels) experimental design and the percentage contribution of these selected parameters on sliding wear performance was examined by Analysis of variance(ANOVA).The sliding wear property of as-developed composites was found to be greatly influenced by sliding velocity and the wear resistance was observed to be improved with the NF/BF/NBF *** wear mechanism of the as-fabricated composites has been elucidated by scanning electron microscopy *** research outcomes demonstrated that the hybridization of Bauhinia vahlii fiber with Nettle fiber led to improve the mechanical and wear properties of epoxy composites.

关键词： Natural fiber Physical properties Mechanical properties Wear properties Taguchi analysis

Microstructural evolution of Mg-14Gd-0.4Zr alloy during compressive creep

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Journal of Magnesium and Alloys 2023年第9期11卷 3161-3173页

作者： Hui shi Yuanding Huang Lixiang Yang Chunquan Liu Hajo Dieringa Chong Lu Lv Xiao Regine Willumeit-Römer Norbert Hort Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Research and Development Center Shanghai Spaceflight Precision Machinery Research InstituteShanghai 201600China school of Mechanical engineering Guizhou UniversityGuiyang 550025China Institute of Material and Process Design Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany The Instrument Analysis Center Shanghai Jiaotong UniversityShanghai 200240China Institute of Product Technology and systems Leuphana University LüneburgUniversitätsallee 1Lüneburg D 21335Germany

The present work reports the creep behavior and microstructural evolution of the sand-cast Mg-14Gd-0.4Zr alloy(wt.%) prepared by the differential pressure casting machine. Their compressive creep tests at 250 ℃ were performed under various applied stresses(i.e., 60, 80 and100 MPa). Among them, the sand-cast Mg-14Gd-0.4Zr samples examined under 250 ℃/80 MPa for 39 and 95 h, respectively, were chosen to systemically analyze their creep mechanisms using high-angle annular dark field-scanning transmission electron microscopy(HAADF-sTeM).The obtained results showed that the enhancement of creep resistance can be mainly attributed to the coherent β' and β'_F phases with an alternate distribution, effectively impeding the basal dislocations movement. However, with the creep time increasing, the fine β'+β'_F precipitate chains coarsened and transformed to semi-coherent β_1 phase and even to large incoherent β phase(surrounded by precipitate-free areas) in grain interiors. The precipitate-free zones(PFZs) at grain boundaries(GBs) were formed, and they could expand during creep deformation. Apart from the main cross-slip of basal and prismatic dislocations, type dislocations were activated and tended to distribute near the GBs. The aforementioned phenomena induced the stress concentrations, consequently leading to the increment of the creep strain.

关键词： Magnesium alloys Creep property Microstructures Precipitate chains Dislocation

CTX-M producing escherichia coli isolated from cattle feces in Bogor slaughterhouse,Indonesia

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Asian Pacific Journal of Tropical Biomedicine 2016年第7期6卷 605-608页

作者： Mirnawati Bachrum sudarwanto Denny Widaya Lukman Hadri Latif Herwin Pisestyani eddy sukmawinata mer Akineden ewald Usleber Laboratory of Veterinary Public Health Faculty of Veterinary MedicineBogor Agricultural University Veterinary Public Health Programme Veterinary Public HealthGraduate SchoolBogor Agricultural University Dairy sciences Institute of Veterinary Food ScienceJustus-Liebig University Giessen

Objective: To determine the occurrence of CTX-M producing escherichia coli(e. coli)from cattle feces in Bogor slaughterhouse, ***: A total of 220 cattle feces samples were collected from Bogor slaughterhouse from March to April 2015. Presence of extended-spectrum beta-lactamase(esBL) producing e. coli was detected by disc diffusion test based on the recommendation from Clinical and Laboratory standards Institute(2014). Bacterial strains which were confirmed as producing esBLs were further analyzed for the presence of bla genes of the esBL by ***: The results showed that CTX-M producing e. coli isolates were detected in 19 samples from 220 samples(8.6%). The b-lactamase genes detected were CTX-M-1(n = 10) and CTX-M-9(n = 9). All of the CTX-M producing e. coli isolates showed multidrug resistance phenotypes to at least four antibiotics. The highest incidence of antibiotics resistance was showed to ampicillin(100.0%), cefotaxime(100.0%), and cefpodoxime(100.0%), followed by streptomycin(84.3%), trimethoprim-sulfamethoxazole(73.7%), erythromycin(52.6%), kanamycin(26.3%), doxycycline(10.5%), and ceftazidime(0.0%).Conclusions: Detection of CTX-M-producing e. coli in cattle feces raises important questions as they can represent a potential risk factor to public health.

关键词： Cattle feces CTX-M escherichia coli slaughterhouse