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Pressureless sintering of ZrC with variable stoichiometry

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Journal of Advanced Ceramics 2017年第2期6卷 165-175页

作者： Katrin SCH(O)NFELD hans-Peter MARTIN Alexander MICHAELIS Fraunhofer Institute for Ceramic Technologies and Systems IKTS Dresden Germany

This paper presents the experiments on the synthesis of zirconium carbide (ZrC) using carbothermal reduction of zirconia (ZrO2).The ratio of ZrO2∶C is used to adapt ZrCxOy with x＜ 1 or ZrC + *** modification of ZrCxOy and the total carbon amount allows the use of pressureless sintering method in combination with sintering temperatures ≤ 2000 ℃.Fully densified ZrC products are *** relevant details of ZrC formation are investigated by X-ray diffraction (XRD).The sintered products are characterized by XRD,field emission scanning electron microscopy (FESEM),as well as mechanical and electrical *** and FESEM investigations show that ZrCxOy is formed during the manufacturing *** grain size and additional zirconia or carbon are related to the ZrO2∶C ratio of the starting powder *** strength up to 300 MPa,Young's modulus up to 400 GPa,fracture toughness up to 4.1 MPa·m1/2,and electrical resistance at room temperature around 10-4 Ω.cm are reached by the pressureless sintered ZrC.

关键词： zirconium carbide (ZrC) carbothermal reduction sintering mechanical properties electrical properties

Necrosis zone depth after bipolar plasma vaporization and resection in the human prostate

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Asian Journal of Urology 2023年第2期10卷 144-150页

作者： Clara Breitling hans Nenning Jorg Rassler Department of Urology St.Elisabeth HospitalLeipzigGermany Institute for Pathology“Am Elsapark” LeipzigGermany

Objectives:To compare the depth of thermal necrosis after use of bipolar resection and vaporization technique comparing intra-individually bipolar loop and bipolar button ***:Transurethral resection and vaporization of the prostate was performed in 55 male patients(260 specimens in total).In a standardized procedure,a bipolar resection loop was used for resection,and a bipolar button electrode was used for *** electrodes were applied in each patient,either in the left or in the right lateral *** depth of necrotic zones in the resected or vaporized tissue of each patient was measured in a standardized way by light ***:The mean depth with standard deviation of thermal injury caused by the loop electrode was 0.0495±0.0274 *** vaporization electrode caused a mean thermal depth with standard deviation of 0.0477±0.0276 *** mean difference of necrosis zone depths between the two types of electrodes(PlasmaButtoneresection loop)was 0.0018 mm(p=0.691).Conclusion:For the first time,we present directly measured values of the absolute necrosis zone depth after application of plasma in the transurethral treatment of benign prostatic *** measured values were lower than in all other transurethral *** procedures of measurement and evaluation allow a statistically significant statement that the low necrosis depth in bipolar procedures is independent of the applied electrodes.

关键词： Transurethral resection of prostate Bipolar enucleation Plasma resection Plasma vaporization Necrosis depth

Rational maps as Schwarzian primitives

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Science China Mathematics 2016年第7期59卷 1267-1284页

作者： CUI GuiZhen GAO Yan RUGH hans Henrik TAN Lei Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China Department of Mathematics Sichuan University Chengdu 610065 China Faculté des Sciences d'Orsay Université Paris-Sud Paris 91405 France Faculté des Sciences Laboratoire Angevin de Recherche en Mathematiques Université d'Angers Angers 49045 France

We examine when a meromorphic quadratic differential φ with prescribed poles is the Schwarzian derivative of a rational map. We give a necessary and sufficient condition: In the Laurent series of φ around each pole c, the most singular term should take the form(1- d2)/(2(z- c)2), where d is an integer, and then a certain determinant in the next d coefficients should vanish. This condition can be optimized by neglecting some information on one of the poles(i.e., by only requiring it to be a double pole). The case d = 2 was treated by Eremenko(2012). We show that a geometric interpretation of our condition is that the complex projective structure induced by φ outside the poles has a trivial holonomy group. This statement was suggested to us by Thurston in a private communication. Our work is related to the problem of finding a rational map f with a prescribed set of critical points, since the critical points of f are precisely the poles of its Schwarzian ***, we study the pole-dependency of these Schwarzian derivatives. We show that, in the cubic case with simple critical points, an analytic dependency fails precisely when the poles are displaced at the vertices of a regular ideal tetrahedron of the hyperbolic 3-ball.

关键词： Schwarzian derivatives rational maps critical points meromorphic quadratic differentials

In the beginning,there was only bare regolith-then some plants arrived and changed the regolith

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Journal of Plant Ecology 2020年第5期13卷 511-516页

作者： Jun Zhou Alejandra Zúñiga-Feest hans Lambers Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China Laboratorio de Biología Vegetal Instituto de Ciencias Ambientales y EvolutivasFacultad de CienciasUniversidad Austral de ChileValdiviaChile School of Biological Sciences The University of Western Australia35 Stirling HighwayCrawley(Perth)WA 6009Australia College of Resources and Environmental Sciences National Academy of Agriculture Green DevelopmentKey Laboratory of Plant-Soil InteractionsMinistry of EducationChina Agricultural University100193 BeijingChina

Pedogenesis along chronosequences has received attention from soil scientists for decades,following the pioneering work of Walker and Syers(1976),who showed a general pattern of the availability of nitrogen(N)and phosphorus(P)subsequently confirmed for a range of chronosequences(Huggett 1998;Turner and Condron 2013;Vitousek and Farrington 1997).Much more recently,changes of plant nutrient-acquisition strategies with soil development have drawn attention,first with a conceptual model(Lambers et al.2008),which was subsequently confirmed with solid experimental data collected along the Jurien Bay chronosequence in south-western Australia(Zemunik et al.2015).The original conceptual model has since been amended,to explain why presumably less-effective mycorrhizal P-acquisition strategies coexist with more-effective strategies based on the release carboxylates(organic anions)(Lambers et al.2018).Mycorrhizas may not be effective at acquiring P from severely P-impoverished soils,but they do boost the defence against pathogens,which strongly affect the growth of non-mycorrhizal carboxylate-releasing Proteaceae(Albornoz et al.2017;Lalibertéet al.2015).What has received little or no attention is the P-acquisition strategies of species that are the first to colonize the bare regolith of the earliest stage of chronosequences(Figs 1 and 2).When the soil P availability is relatively high such as along the Jurien Bay chronosequence(Turner et al.2018),there is little point searching for specialized strategies,but along many chronosequences,*** the case(Egli et al.2012;Richardson et al.2004;Zhou et al.2019).

关键词： soil fir Richardson

Arsenic in Rice Soils and Potential Agronomic Mitigation Strategies to Reduce Arsenic Bioavailability： A Review

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Pedosphere 2018年第3期28卷 363-382页

作者： Lalith D.B.SURIYAGODA Klaus DITTERT hans LAMBERS Faculty of Agriculture University of Peradeniya Peradeniya 20400( Sri Lanka) Department of Crop Science Section of Plant Nutrition and Crop Physiology University of Gottingen Gottingen 37075( Germany) School of Biological Sciences and Institute of Agriculture The University of Western Australia Perth WA 6009( Australia)

Soils used for rice （Oryza sativa L.） cultivation in some areas contain high concentrations of arsenic （As）due to irrigation with groundwater containing As and intensive use of agrochemicals or industrial residues containing As. To restrict rice uptake of As in these soils, approaches to reduce As input and bioavailability must be considered. One approach to reduce As input into rice soils or uptake by rice is cultivating rice under aerobic, intermittent flooding, or alternate wetting and drying （AWD） conditions, rather than in submerged soils, or use of irrigation water low in As. For reducing As bioavailability in soil, aerobic or AWD rice culture and application of biochar, sulfur （S）, and/or rice polish to soil are promising. Moreover, use of As-hyperaecumulating plant species （e.g., Pteris vittata L.） in rotation or combinations with favourable plant species （e.g., Azolla, Chlorella, or Nannochloropsis species） can also be promoted, in addition to using rice cultivars that are tolerant to As. Though applications of high doses of phosphorus （P）, iron （Fe）, and silicon （Si） fertilizers have shown promise in many instances, these methods have to be practiced carefully, because negative effects have also been reported, although such incidents are rare. Major factors affecting As speciation and bioavailability in soil are chemical properties such as redox status, pH, and Fe, P, Si, and S concentrations, physical properties such as texture and organic matter, and biological properties such as methylation activity by soil microorganisms. However, as many of these factors interact, long-term examination under field conditions is needed before measures are recommended for and implemented in farmers＇ fields.

关键词： amendment contaminated soils health risk hyperaccumulating plant remediation tolerant cultivar toxicity water management

Single and multiple stressor effect of road deicers and Cu on Atlantic salmon (Salmo salar) alevins from hatching till swim-up

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Journal of Environmental Sciences 2018年第4期30卷 368-378页

作者： Urma Mahrosh BjФrn Olav Rosseland Brit Salbu hans-Christian Teien Nortuegian Uniuersity of Life Sciences Department of Environmental Sciences N-1432 As Norway National University of Sciences and Technology H-12 Islamabad Pakistan Norwegian University of Life Sciences Department of Ecology and Natural Resource Management N-1432 As Norway

Road salts are frequently used for deicing of roads in the Nordic countries. During snow-melt, the road run-off containing high concentrations of road salt and various metals such as Cu remobilized from sand, silt and dust may negatively influence organisms in downstream receiving water bodies. The present work focuses on the impact of road salt（NaCl） and Cu, separately and in mixtures on Atlantic salmon alevins from hatching till swim-up. The results showed that high road salt concentrations could induce a series of negative effects in alevins such as reduced growth, deformities, delayed swim-up and mortality. For alevins exposed to all tested road salt concentrations（100–1000 mg/L）,mortality was significantly higher compared to control. In exposure to Cu solutions（5–20 μg Cu/L）, no effects on growth, morphology, swim-up or mortality of alevins compared to control were observed. In mixture solutions（road salt and Cu）, ultrafiltration of the exposure water demonstrated that only 20%–40% of Cu was present as positively charged low molecular mass（LMM） Cu species assumed to be bioavailable. When exposed to road salt and Cu mixtures, negative effects in alevins such as reduced growth, deformities,delayed swim-up and mortality were observed. The overall results indicated that the road salt application could seriously affect sensitive life stages of Atlantic salmon, and application of road salt should be avoided during the late winter–early spring period.

关键词： Road deicers Copper Atlantic salmon Alevins Biological effects

Novel stable isotope concepts to track antibiotics in wetland systems

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Journal of Environmental Sciences 2024年第12期146卷 298-303页

作者： Xiao Liu Junya Zhang hans Hermann Richnow Gwenaël Imfeld Institut Terre et Environnement de Strasbourg(ITES) Universitéde Strasbourg/EOST/ENGEESCNRS UMR 7063F-67084 StrasbourgFrance State Key Joint Laboratory of Environmental Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Department of Technical Biogeochemistry Helmholtz Centre for Environmental Research-UFZPermoserstraße 1504318 LeipzigGermany Isodetect GmbH Deutscher Platz 5b04103 LeipzigGermany

Antibiotics,their transformation products,and the translocation of antibiotic-resistant genes in the environment pose significant health risks to humans,animals,and ecosystems,aligning with the One Health *** wetlands hold substantial yet underutilized potential for treating wastewater from agricultural,domestic sewage,or contaminated effluents from wastewater treatment plants,with the goal of eliminating ***,the comprehensive understanding of the distribution,persistence,and dissipation processes of antibiotics within constructed wetlands remains largely *** this context,we provide an overview of the current application of stable isotope analysis at natural abundance to *** explore the opportunities of an advanced multiple stable isotope approach,where isotope concepts could be effectively applied to examine the fate of antibiotics in *** development of a conceptual framework to study antibiotics in wetlands using multi-element stable isotopes introduces a new paradigm,offering enhanced insights into the identification and quantification of natural attenuation of antibiotics within wetland *** perspective has the potential to inspire the general public,governmental bodies,and the broader research community,fostering an emphasis on the utilization of stable isotope analysis for studying antibiotics and other emerging micropollutants in wetland systems.

关键词： Constructed wetlands Micropolluants Antibiotics Degradation,CSIA

Differential modulation of crown allometry and stem growth at gap edges in five European tree species by drought conditions

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Forest Ecosystems 2024年第5期11卷 618-631页

作者： Luke Bohnhorst Peter Biber Torben Hilmers Enno Uhl hans Pretzsch Chair of Forest Growth and Yield Science TUM School of Life SciencesTechnical University of MunichHans-Carl-von-Carlowitz-Platz 285354FreisingGermany Bavarian State Institute of Forestry Hans-Carl-von-Carlowitz-Platz 185354FreisingGermany

Background In Central Europe,forests are increasingly affected by various disturbances,resulting in an increasing gap formation in the *** order to support goal-oriented management,more knowledge is required about the acclimation of the crown and its effects on the basal area growth of trees at the edge of a *** This work compared trees'growth and crown structure at the edge of a transient gap,with a gap size of more than 80m^(2),with trees in the stand that were at least 30m away from the gap.A total of 249 European beeches(Fagus sylvatica L.),Norway spruces(Picea abies ***),Scots pines(Pinus sylvestris L.),oaks(Quercus spp.;Quercus petraea(Matt.)Liebl.,Quercus robur L.),and silver firs(Abies alba Mill.)were examined on long-term experimental plots in southern *** crown measures were developed and calculated using high-resolution terrestrial laser scanning(TLiDAR)to capture the three-dimensional crown *** responses to edge conditions were measured based on tree *** linear mixed models,we predict the basal area increment of edge trees relative to trees in the stand under wet and dry soil moisture conditions after the gap *** We identified i)species-specific acclimation of the crown of edge trees after the gap formation,ii)under wet soil moisture conditions a growth increase of 25%–45%for beech,pine,and oak edge trees and growth losses of 5%–60%for spruce and fir and iii)coniferous tree species benefited from the edge position regarding their basal area increment under dry soil moisture conditions and deciduous tree species grew regardless of the soil moisture conditions at the edge of a *** Gaps have a species-specific effect on the habitus and growth of edge trees and can have both positive and negative impacts on silviculture.

关键词： Canopy gaps Disturbance Growth TLiDAR Drought stress Crown structure Acclimation

Intestinal organoids as tools for enriching and studying specific and rare cell types:advances and future directions

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Journal of Molecular Cell Biology 2020年第8期12卷 562-568页

作者： Kim E.Boonekamp Talya L.Dayton hans Clevers Oncode Institute Hubrecht InstituteRoyal Netherlands Academy of Arts and Sciences(KNAW)and University Medical Centre(UMC)Utrecht358A CT UtrechtThe Netherlands Princess Maxima Centre for Paediatric Oncology 358A CS UtrechtThe Netherlands

Adult tissue-derived organoids allow for the expansion and maintenance of primary epithelial cells in a near-native *** 3D and self-organizing organotypic cultures derived from adult tissues have been increasingly used in fundamental and translational research.A key feature of this organoid system is that it recapitulates the stem cell lineage and thus,the differentiated cell-type heterogeneity of the in vivo tissue of origin.

关键词： directions organo rare