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Comparing two IBM implementations for the simulation of uniform packed beds

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Particuology 2024年第3期86卷 1-12页

作者： Christian Gorges maximilian brommer Christin Velten Siegmar Wirtz Enric Illana Mahiques Viktor Scherer Katharina Zahringer Berend van Wachem Mechanical Process Engineering Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany Department of Energy Plant Technology Ruhr-Universitat BochumUniversitatsstraBe 15044780BochumGermany Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany

Nowadays,the design of fixed packed bed reactors still relies on empirical correlations,which,especially for small tube to particle diameter ratios,are mostly too inaccurate because of the presence of wall ***,the simulation of fixed packed bed reactors plays an important role to predict and control the flow and process parameters in such,nowadays and in the *** of its straightforward applicability to non-uniform packings with particles of arbitrary shapes,the immersed boundary method(IBM)has advantages over other numerical methods and is used more and more *** paper compares two approaches of IBMs for the simulation of fixed bed reactors with spherical shaped *** classic,smooth approach is compared to the straightforward to implement blocked-off method for velocity fields above the fixed bed for particle Reynolds numbers of 300 and *** from experimental inline PIV-measurements of the reactor to be simulated serve as a basis for *** good agreement with the experiment is found for both simulation methodologies with higher resolutions,considering the more stable flow at a particle Reynolds number of *** in the different IBM approaches occurred for the more unsteady flow at a particle Reynolds number of *** to the blocked-off method,the smooth IBM reflects the formation of additional jets and recirculation zones better right above the bed,though increasing the fluid mesh resolution improves the accuracy of the blocked-off ***,a more diffusive behaviour is found for the blocked-off simulations due to the stairstep representation,which is avoided by using interpolation stencils as in the smooth *** higher mesh refinement in the blocked-off IBM this effect can be reduced,but this also increases the computational effort.

关键词： Immersed boundary method Packed bed reactor Uniform particle packing

Phenotypic plasticity of labile traits in the wild

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Current Zoology 2013年第4期59卷 485-505页

作者： Jon E. brommer Department of Biology University Hill 20014 University of Turku Finland ARONIA Research and Development Institute Novia Applied University and Abo Akademi University Raseborgsvaigen 9 10600 Ekenas Finland

Individual-based studies allow quantification ofphenotypic plasticity in behavioural, life-history and other labile traits The study of phenotypic plasticity in the wild can shed new light on the ultimate objectives （1） whether plasticity itself can evolve or is constrained by its genetic architecture, and （2） whether plasticity is associated to other traits, including fitness （selection）. I describe the main statistical approach for how repeated records of individuals and a description of the environment （E） allow quantification of variation in plasticity across individuals （IxE） and genotypes （GxE） in wild populations. Based on a literature review of life-history and behavioural studies on plasticity in the wild, I discuss the present state of the two objectives listed above. Few studies have quantified GxE of labile traits in wild populations, and it is likely that power to detect statistically sig- nificant GxE is lacking. Apart from the issue of whether it is heritable, plasticity tends to correlate with average trait expression （not fully supported by the few genetic estimates available） and may thus be evolutionary constrained in this way. Individ- ual-specific estimates of plasticity tend to be related to other traits of the individual （including fitness）, but these analyses may be anti-conservative because they predominantly concern stats-on-stats. Despite the increased interest in plasticity in wild popula- tions, the putative lack of power to detect GxE in such populations hinders achieving general insights. I discuss possible steps to invigorate the field by moving away from simply testing for presence of GxE to analyses that ＇scale up＇ to population level proce-sses and by the development of new behavioural theory to identify quantitative genetic parameters which can be estimated

关键词： Individual-level plasticity Life history Animal personality Linear mixed model Animal model Wild population Longitudinal study

Reducing the loss of genetic diversity associated with assisted colonization-like introductions of animals

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Current Zoology 2015年第5期61卷 827-834页

作者： Jaana KEKKONEN Jon E. brommer Department of Biosciences University of Helsinki Helsinki Finland Department of Biology University of Turku Turku Finland

Translocations, especially assisted colonizations, of animals are increasingly used as a conservation management tool. In many cases, however, limited funding and other logistic challenges limit the number of individuals available for transloeation. In conservation genetics, small populations are predicted to rapidly lose genetic diversity which can deteriorate population survival. Thus, how worried should we be about the loss of genetic diversity when introducing small, isolated populations？ Historical species introductions provide a means to assess these issues. Here we review 13 studies of ＂assisted colonization-like＂ introductions of animals, where only a small known number of founders established an isolated population without secondary contact to the source population. We test which factors could be important in retaining genetic diversity in these cases. In many cases, loss in heterozygosity （-12.1%） was detected, and more seriously the loss in allelic richness （-27.8 %）. Number of founders seemed to have an effect but it also indicated that high population growth rate could help to retain genetic diversity, i.e. future management actions could be effective even with a limited number of founders if population growth would be enhanced. On the contrary, translocated organisms with longer generation times did not seem to retain more genetic diversity. We advocate that, where possible, future studies on translocated animals should report the loss of genetic diversity （both heterozygosity and allelic richness）, which is essential for meta-analyses like this one for deepening our understanding of the genetic consequences of assisted colonization, and justifying management decisions [Current Zoology 61 （5）： 827-834, 2015].

关键词： Introduced species Loss of genetic diversity Number of founders Conservation management Population growth rate Generation time

NUMERICAL APPROXIMATION OF THE SMOLUCHOWSKI EQUATION USING RADIAL BASIS FUNCTIONS

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Journal of Computational Mathematics 2020年第1期38卷 176-194页

作者： Christiane Helzel maximilian Schneiders Institut of Mathematics Heinrich-Heine-Universitat DusseldorfGermany formerly Institut of Mathematics Heinrich-Heine-Universitat DusseldorfGermany

The goal of this paper is to present a numerical method for the Smoluchowski equation,a drift-diffusion equation on the sphere,arising in the modelling of particle *** numerical method uses radial basis functions(RBF).This is a relatively new approach,which has recently mainly been used for geophysical *** a simplified model problem we compare the RBF approach with a spectral method,*** standard approach used in related physical *** comparison as well as our other accuracy studies show that RBF methods are an attractive alternative for these kind of models.

关键词： Smoluchowski equation Spectral method Radial basis function method

Self-supervised optimization of random material microstructures in the small-data regime

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npj Computational Materials 2022年第1期8卷 435-445页

作者： maximilian Rixner Phaedon-Stelios Koutsourelakis Professorship of Data-driven Materials Modeling Department of Engineering Physics and ComputationTechnical University of MunichBoltzmannstr.15D-85748Garching bei MünchenGermany Munich Data Science Institute(MDSI-Core Member) Garching bei MünchenGermany

While the forward and backward modeling of the process-structure-property chain has received a lot of attention from the materials’ community,fewer efforts have taken into consideration *** arise from a multitude of sources and their quantification and integration in the inversion process are essential in meeting the materials design *** first contribution of this paper is a flexible,fully probabilistic formulation of materials’ optimization problems that accounts for the uncertainty in the process-structure and structure-property linkages and enables the identification of optimal,high-dimensional,process *** employ a probabilistic,data-driven surrogate for the structure-property link which expedites computations and enables handling of non-differential *** couple this with a problem-tailored active learning strategy,i.e.,a self-supervised selection of training data,which significantly improves accuracy while reducing the number of expensive model *** demonstrate its efficacy in optimizing the mechanical and thermal properties of two-phase,random media but envision that its applicability encompasses a wide variety of microstructure-sensitive design problems.

关键词： microstructure property optimization

Genome Editing with CRISPR-Cas9:Can It Get Any Better?

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Journal of Genetics and Genomics 2016年第5期43卷 239-250页

作者： maximilian Haeussler Jean-Paul Concordet Santa Cruz Genomics Institute MS CBSE1156 High StreetUniversity of California Laboratoire Structure et Instabilite des Genomes Inserm U1154CNRS UMR7196Museum national d'Histoire naturelle

The CRISPR-Cas revolution is taking place in virtually all fields of life *** DNA cleavage with the CRISPR-Cas9 system of Streptococcus pyogenes has proven to be extraordinarily simple and efficient,relying only on the design of a synthetic single guide RNA（sgRNA） and its co-expression with ***,we review the progress in the design of sgRNA from the original dual RNA guide for *** and Staphylococcus aureus Cas9（SpCas9 and SaCas9）.New assays for genome-wide identification of offtargets have provided important insights into the issue of cleavage specificity in *** the same time,the on-target activity of thousands of guides has been *** data have led to numerous online tools that facilitate the selection of guide RNAs in target *** appears that for most basic research applications,cleavage activity can be maximized and off-targets minimized by carefully choosing guide RNAs based on computational ***,recent studies of Cas proteins have further improved the flexibility and precision of the CRISPR-Cas toolkit for genome *** by the crystal structure of the complex of sgRNA-SpCas9 bound to target DNA,several variants of SpCas9 have recently been engineered,either with novel protospacer adjacent motifs（PAMs） or with drastically reduced *** Cas9 and Cas9-like proteins called Cpf 1 have also been characterized from other bacteria and will benefit from die insights obtained from *** editing with CRISPR-Cas9 may also progress with better understanding and control of cellular DNA repair pathways activated after Cas9-induced DNA cleavage.

关键词： Genome editing CRISPR-Cas9 system Guide RNA

Novel pathomechanistic insights into lysosomal storage disorders:how neuron-intrinsic cGAS-STING signaling drives disease progression

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Signal Transduction and Targeted Therapy 2024年第9期9卷 3548-3549页

作者： maximilian Frosch Marco Prinz Institute of Neuropathology University of FreiburgFaculty of MedicineFreiburgGermany Signalling Research Centres BIOSS and CIBSS University of FreiburgFreiburgGermany

In their recent paper published in Nature Cell Biology,1 Wang and colleagues defined a pathogenetic mechanism among a variety of lysosomal storage disorders(LSDs)mediating neuronal death and disease *** authors observed neuron-intrinsic activated cGAS-STING signaling triggered by accumulating cytosolic dsDNA,and thus,they provide a valuable target for directed therapies.

关键词： disorders intrinsic death

“Wood-nacre”:Development of a Bio-inspired Wood-Based Composite for Beam and 3D-Surface Elements with Improved Failure Mechanisms

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Journal of Bionic Engineering 2023年第4期20卷 1701-1711页

作者： Ulrich Müller Peter Halbauer Alexander Stadlmann maximilian Grabner Hajir Al-musawi Bernhard Ungerer maximilian Pramreiter Department of Material Science and Process Engineering Institute of Wood Technology and Renewable MaterialsUniversity of Natural Resources and Life SciencesKonrad-Lorenz-Straße 243430Tulln an der DonauAustria Hycobility Engineering&Technologies GmbH Stadiongasse 6-8/Top281010ViennaAustria

Following the natural structure of the nacre,the material studied consists of a multitude of hexagonal tiles that are glued together in an offset manner with a ductile *** so-called“wood nacre”consists of macroscopic tiles of birch wood veneer with a thickness of 0.8 mm and a size of 20 or 10 mm in diameter in order to mimic the aragonite tiles and the ductile PUR-adhesive corresponds to the layers of collagen in between.E-modulus(MOE),bending strength(MOR)and impact bending strength of the samples were determined and compared with reference samples of birch laminated *** hierarchical layered structure of the tiles does not cause any relevant loss in *** nacre,“wood nacre”also shows tough fracture behaviour and a high homogenization ***,strain hardening and high fracture toughness of the natural model could not be fully *** reason for this is the insufficient ratio between the strength and stiffness of the veneer layers and the *** adjusting the size of the tiles,increasing the strength and surface roughness of the veneers,*** densification,and using more ductile adhesives that can be applied in smaller layer thicknesses,it should be possible to better reproduce the natural ratios of nacre and thus achieve a significant improvement in the material properties of“wood nacre”.In addition to the mechanical properties,the high potential of the new material lies in the possibility of producing 3D shell-shaped elements for lightweight wood hybrid construction.

关键词： Bio-inspired Damage tolerance Failure behaviour Hierarchical structure Nacre Work of fracture

Concentrations of organophosphate flame retardants in dust from cars, homes, and offices: An international comparison

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Emerging Contaminants 2016年第2期2卷 66-72页

作者： Stuart Harrad Sandra brommer Jochen F.Mueller School of Geography Earth&Environmental SciencesUniversity of BirminghamBirminghamB152TTUnited Kingdom National Centre for Environmental Toxicology The University of QueenslandKessels RoadBrisbaneQueenslandAustralia

Concentrations of a number of organophosphate flame retardants(PFRs)were measured in floor dust collected from living rooms in Australia(n=42),Canada(n=14),Germany(n=22),and Kazakhstan(n=9);cars from Australia(n=39)and Germany(n=19);and offices from Germany(n=25)and Kazahkstan(n=8).PFR concentrations in these samples were compared with each other and with previously reported data for PFRs in dust from similar microenvironments in the *** data reveal significant between-country differences in both absolute concentrations and the relative abundance of specific PFRs in each of the microenvironments *** notably,concentrations of TCIPP in UK living room dust(median=21 μg g^-1)exceeded significantly(p<0.05)those in all other countries studied here;a substantial number of car dust samples contained elevated concentrations of TDCIPP,and German samples generally contained lower levels of PFRs in all microenvironments *** addition,PFRs were determined in dust samples collected from living room couches in both Australia(n=41)and the UK(n=10).The elevated concentrations of TCIPP in UK living room dust are likely attributable to the favoured use of this PFR in UK couch *** is indicated by concentrations of TCIPP in UK couch dust(median=610 μg g^-1)exceeding significantly those in Australian couch dust(median=2.9 μg g^-1).Moreover,concentrations of TCIPP in UK couch dust originating from couches 15 years old or less,display a marked relationship with the age of the couch,with concentrations in such samples increasing significantly(p<0.01)with couch age.

关键词： PFRs Indoor dust Australia Germany Canada Kazakhstan