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Tribological mechanisms of slurry abrasive wear

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Friction 2023年第6期11卷 1079-1093页

作者： Yulong LI Paul sCHREIBER Johannes sCHNEIDER christian GREINER Institute for Applied Material(IAM) Karlsruhe Institute of Technology(KIT)Karlsruhe76131Germany KIT IAM-ZM MicroTribology Center(μTC) Karlsruhe76131Germany

Abrasive wear mechanisms—including two-body and three-body abrasion—dominate the performance and lifespan of tribological systems in many engineering fields,even of those operating in lubricated *** steel(100Cr6)pins and discs in a flat-on-flat contact were utilized in experiments together with 5 and 13 μm Al_(2)O_(3)-based slurries as interfacial media to shed light on the acting *** results indicate that a speed-induced hydrodynamic effect occurred and significantly altered the systems'frictional behavior in tests that were performed using the 5 μm *** experiments revealed that a speed-dependent hydrodynamic effect can lead to a 14% increase in film thickness and a decrease in friction of around 2/3,accompanied by a transition from two-body abrasion to three-body abrasion and a change in wear mechanism from microcutting and microploughing to fatigue ***,no correlation could be found between the total amount of wear and the operating state of the system during the experiment;however,the wear distribution over pin and disc was observed to change *** paper studies the influence of the hydrodynamic effect on the tribological mechanism of lubricated abrasive wear and also highlights the importance to not only consider a tribological systems'global amount of wear.

关键词： abrasive wear two-body abrasion three-body abrasion hydrodynamic effect steel

Effect of particle Froude number on sub-grid effective drag,filtered and residual stresses in fluidized gas-particle flows

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Particuology 2024年第12期95卷 36-48页

作者： christian C.Milioli Fernando E.Milioli Department of Mechanical Engineering School of Engineering of São CarlosUniversity of São Paulo13566-590São CarlosSPBrazil

sub-grid effective drag,filtered and residual stresses in the meso-scale of gas-particle fluidized flows are intrinsically affected by underlying micro-scale conditions as well as non-local effects related to macro-scale *** this work we applied microscopic two-fluid modeling to experiment with particle Froude number in order to evaluate the impact of this micro-scale condition over the concerning meso-scale derived sub-grid *** performed highly resolved simulations in periodic domains for particle Froude numbers from 12.21 to 799.22,for a wide range of macro-scale *** were filtered and classified by ranges of meso-scale markers for the various particle Froude *** particle Froude number was found to considerably affect the structural refinement of the heterogeneous flow fields thereby directly impacting effective drag,filtered and residual *** of those parameters showed systematic behaviors in relation to particle Froude number,thereby providing sound data for new sub-grid modeling propositions.

关键词： Fluidization Gas-particle flows Two-fluid model sub-grid analysis Multiscale analysis

Pho-view of Auxin:Reversible Protein Phosphorylation in Auxin Biosynthesis,Transport and signaling

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Molecular Plant 2021年第1期14卷 151-165页

作者： shutang Tan christian Luschnig Jiri Friml Institute of science and Technology Austria(1sT Austria) Am Campus 13400 KlosterneuburgAustria Department of Applied Genetics and Cell Biology University of Natural Resources and Life SciencesVienna(BOKU)Muthgasse 181190 WienAustria

The phytohormone auxin plays a central role in shaping plant growth and *** decades of genetic and biochemical studies,numerous core molecular components and their networks,underlying auxin biosynthesis,transport,and signaling,have been ***,protein phosphorylation,catalyzed by kinases and oppositely hydrolyzed by phosphatases,has been emerging to be a crucial type of post-translational modification,regulating physiological and developmental auxin output at all *** this review,we comprehensively discuss earlier and recent advances in our understanding of genetics,biochemistry,and cell biology of the kinases and phosphatases participating in auxin *** provide insights into the mechanisms by which reversible protein phosphorylation defines developmental auxin responses,discuss current challenges,and provide our perspectives on future directions involving the integration of the control of protein phosphorylation into the molecular auxin network.

关键词： Arabidopsis auxin protein kinase phosphatase phosphorylation

Morrey smoothness spaces:A new approach

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science China Mathematics 2023年第6期66卷 1301-1358页

作者： Dorothee D.Haroske hans Triebel Institute of Mathematics Faculty of Mathematics and Computer ScienceFriedrich Schiller University JenaJena 07743Germany

In the recent years,the so-called Morrey smoothness spaces attracted a lot of *** can(also)be understood as generalisations of the classical spaces A_(p,q)^(s)(R^(n))with A∈{B,F}in R^(n),where the parameters satisfy s∈R(smoothness),0summability).In the case of Morrey smoothness spaces,additional parameters are *** our opinion,among the various approaches at least two scales enjoy special attention,also in view of applications:the scales A_(p,q)^(s)(R^(n))with A∈{N,E}and u≥p,and A_(p,q)^(s),τ(R^(n))with A∈{B,F}andτ≥*** reorganise these two prominent types of Morrey smoothness spaces by adding to(s,p,q)the so-called slope parameter e,preferably(but not exclusively)with-n es out that|e|replaces n,and min(|e|,1)replaces 1 in slopes of(broken)lines in the(1/p,s)-diagram characterising distinguished properties of the spaces A_(p,q)^(s)(R^(n))and their Morrey *** attention will be paid to low-slope spaces with-1sponding properties are quite often independent of n∈*** aim is *** the one hand,we reformulate some assertions already available in the literature(many of which are quite recent).On the other hand,we establish on this basis new properties,a few of which become visible only in the context of the offered new approach,governed,now,by the four parameters(s,p,q,e).

关键词： Morrey space smoothness space of Morrey type Besov-Morrey space Triebel-Lizorkin-Morrey space Besov-type space Triebel-Lizorkin-type space

氧化铝负载的银纳米颗粒高选择性催化合成亚胺(英)

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催化学报 2014年第5期35卷 670-676页

作者： Jerrik Mielby Raju Poreddy christian Engelbrekt sΦren Kegns DTU Chemistry Technical University of Denmark

The oxidative dehydrogenation of alcohols to aldehydes catalyzed by Ag nanoparticles supported on Al_2O_3 was *** catalyst promoted the direct formation of imines by tandem oxidative dehydrogenation and condensation of alcohols and *** reactions were performed under mild conditions and afforded the imines in high yield(up to 99%) without any byproducts other than H_*** highest activity was obtained over 5 wt%Ag/Al_2O_3 in toluene with air as *** reactions were also performed under oxidant-free conditions where the reaction was driven to the product side by the production of H_2 in the gas *** use of an efficient and selective Ag catalyst for the oxidative dehydrogenation of alcohol in the presence of amines gives a new green reaction protocol for imine synthesis.

关键词：银纳米颗粒银催化亚胺氧化铝负载氧化脱氢 Al2O3 直接生成

Toward managing mixed-species stands： from parametrization to prescription

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Forest Ecosystems 2017年第4期4卷 286-302页

作者： hans Pretzsch Eric K. Zenner Chair for Forest Growth and Yield science Center of Life and Food Sciences Weihenstephan Technical University of Munich Hans-Carl-von Carlowitz-Platz 2 85354 Freising Germany

A better understanding and a more quantitative design of mixed-species stands will contribute to more integrative and goal-oriented research in mixed-species forests. Much recent work has indicated that the structure and growth of mixed species forests may fundamentally differ from monocultures. Here we suggest how to progress from the present accumulation of phenomenological findings to a design of mixed-species stands and advanced silvicultural prescriptions by means of modelling. First, the knowledge of mixing effects on the structure and growth at the stand, species, and individual tree level is reviewed, with a focus on those findings that are most essential for suitable modelling and silvicultural designs and the regulation of mixed stands as opposed to monocultures. Then, the key role of growth models, stand simulators, and scenario assessments for designing mixed species stands is discussed The next section illustrates that existing forest stand growth models require some fundamental modifications to become suitable for both monocultures and mixed-species stands. We then explore how silvicultural prescriptions derived from scenario runs would need to be both quantified and simplified for transfer to forest management and demonstrated in training plots. Finally, we address the main remaining knowledge gaps that could be remedied through empirical research.

关键词： Multiplicative mixing effects Overyielding Overdensity Modelling mixing effects scenario analysis,silvicultural prescriptions Practical guidelines

Drought can favour the growth of small in relation to tall trees in mature stands of Norway spruce and European beech

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Forest Ecosystems 2018年第3期5卷 258-276页

作者： hans Pretzsch Gerhard schutze Peter Biber Center of Life and Food sciences Weihenstephan Technical University of MunichHans-Carl-von-Carlowitz-Platz 285354 FreisingGermany

Background: Climate change triggered many studies showing that trends and events of environmental conditions can reduce but also accelerate growth at the stand and individual tree level. However, it is still rather unknown how climate change modifies the growth partitioning between the trees in forest ***: Based on long-term girth-tape measurements in mature monospecific and mixed-species stands of Norway spruce(Picea abies(L.) Karst.) and European beech(Fagus sylvatica L.) we traced the effect of the severe droughts in 2003 and 2015 from the stand down to the tree ***: stand growth of Norway spruce decreased by about 30% in the once-in-a-century drought 2015, while European beech was much more drought resistant. Water availability generally amplified size-asymmetric growth partitioning. Especially in case of Norway spruce water availability primarily fostered the growth of predominant trees, whereas drought favoured the growth of small trees at the expense of the predominant ones. We could not detect significant differences between mixed and monospecific stands in this ***: The drought-induced reallocation of growth in favour of small trees in case of spruce may result from its isohydric character. We hypothesize that as small trees are shaded, they can benefit from the reduced water consumption of their sun-exposed taller neighbours. In case of beech, as an anisohydric species, tall trees suffer less and smaller trees benefit less under drought. The discussion elaborates the consequences of the water dependent growth allocation for forest monitoring, growth modelling, and silviculture.

关键词： Growth partitioning Drought Competition symmetry Climate change Norway spruce European beech

A novel photographic approach for monitoring the structural heterogeneity and diversity of grassland ecosystems

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Journal of Plant Ecology 2014年第6期7卷 518-525页

作者： Raphaël Proulx Irene T.Roca Felipe s.Cuadra Ian seiferling christian Wirth Chaire UQTR en Biologie systémique de la Conservation Universitédu QuébecàTrois-Rivières3351 Des ForgesTrois-RivièresQuebec G9A 5H7Canada Department of special Botany and Functional Biodiversity Research Institute of Biology IUniversity of LeipzigJohannisallee 21-2304103 LeipzigGermany

Aims studies that investigate the space-filling heterogeneity of biological struc-tures in plant communities remain *** main objective of this study was to evaluate the relationship between newly developed photo-graphic measures of structural heterogeneity in digital images and plant species composition in the context of a long-term grassland *** We tested a close-range photographic protocol using measures of structural heterogeneity in gray-tone images,namely mean infor-mation gain(MIG)and spatial anisotropy,to assess differences in the compositional(species richness)and functional characteristics(plant height and flowering)of 78 managed grassland *** also implemented a random placement model of community assembly to explore the links between our measures of structural complexity and the geometric pattern of plant *** Findings MIG and spatial anisotropy correlated with the growth and species richness of grassland *** showed that struc-tural heterogeneity in gray-tone digital images is a function of the size distribution and orientation pattern of plant *** easy,fast and non-destructive methodological approach could eventually serve to monitor the diversity and integrity of various ecosystems at different resolutions across space and time.

关键词： biodiversity photography ecosystem integrity texture random placement model

Anticancer Properties of Lobetyolin,an Essential Component of Radix Codonopsis(Dangshen)

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Natural Products and Bioprospecting 2021年第2期11卷 143-153页

作者： christian Bailly OncoWitan 59290 Lille(Wasquehal)France

Lobetyolin(LBT)is a polyacetylene glycoside found in diverse medicinal plants but mainly isolated from the roots of Codo-nopsis pilosula,known as Radix Codonopsis or *** traditional Chinese medicinal preparations containing Radix Codonopsis were identified;they are generally used to tonify spleen and lung Qi and occasionally to treat *** we have reviewed the anticancer properties of Codonopsis extracts,LBT and structural *** and lobetyolinin are the mono-and bis-glucosylated forms of the polyacetylenic compound *** and LBT have shown activi-ties against several types of cancer(notably gastric cancer)and we examined the molecular basis of their activity.A down-regulation of glutamine metabolism by LBT has been evidenced,contributing to drug-induced apoptosis and tumor growth *** markedly reduces both mRNA and protein expression of the amino acid transporter Alanine-serine-Cysteine Transporter 2(AsCT2).Other potential targets are proposed here,based on the structural analogy with other anticancer *** and related polyacetylene glycosides should be further considered as potential anticancer agents,but more work is needed to evaluate their efficacy,toxicity,and risk-benefit ratio.

关键词： Cancer therapy Natural products Mechanism of action Molecular target Terpenoids Lobetyolin Polyacetylene glycoside Glutamine metabolism