检索结果-南通市图书馆

IR-transparent MgO-Gd_(2)O_(3) composite ceramics produced by self-propagating high-temperature synthesis and spark plasma sintering

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2021年第2期10卷 237-246页

作者： Dmitry A.Permin Maksim s.Boldin Alexander V.Belyaev stanislav s.balabanov Vitaly A.Koshkin Atrem A.Murashov Igor V.Ladenkov Evgeny A.Lantsev Ksenia E.smetanina Nadia M.Khamaletdinova G.G.Devyatykh institute of chemistry of high-purity substances of the ras nizhny novgorod603137russia Lobachevsky state university of nizhny novgorod nizhny novgorod603950russia “Joint-stock company”research and production enterprise“salut” nizhny novgorod603950russia G.A.Razuvaev institute of organometallic chemistry of the ras nizhny novgorod603137russia

A glycine–nitrate self-propagating high-temperature synthesis(sHs)was developed to produce composite MgO-Gd_(2)O_(3) *** X-ray powder diffraction(XRD)analysis confirmed the sHs-product consists of cubic MgO and Gd_(2)O_(3) phases with nanometer crystallite size and retains this structure after annealing at temperatures up to 1200℃.Near full dense high IR-transparent composite ceramics were fabricated by spark plasma sintering(sPs)at 1140℃and 60 *** in-line transmittance of 1 mm thick MgO-Gd_(2)O_(3) ceramics exceeded 70%in the range of 4–5 mm and reached a maximum of 77%at a wavelength of 5.3 *** measured microhardness HV0.5 of the MgO-Gd2O3 ceramics is 9.5±0.4 GPa,while the fracture toughness(KIC)amounted to 2.0±0.5МPa·m1/*** characteristics demonstrate that obtained composite MgO-Gd_(2)O_(3) ceramic is a promising material for protective infra-red(IR)windows.

关键词： MgO-Gd_(2)O_(3) self-propagating high-temperature synthesis(sHs) spark plasma sintering(sPs) optical properties infra-red(IR)ceramics

On the critical behavior of a homopolymer model

在线全文

学校读者我要写书评

暂无评论

science China Mathematics 2019年第8期62卷 1463-1476页

作者： Michael Cranston stanislav Molchanov Department of Mathematics University of California at Irvine Irvine CA 92697-3875 USA Department of Mathematics The University of North Carolina Charlotte NC 28223 USA

We begin with the reference measure P0 induced by simple, symmetric nearest neighbor continuous time random walk on Zd starting at 0 with jump rate 2d and then define, for β≥0, t > 0, the Gibbs probability measure Pβ,t by specifying its density with respect to P0 as dPβ,t/dP0= Zβ,t（0）(-1eβ∫0tδ0（xs）ds),（0.1）where Zβ,t（0）≡E0[eβ∫sup>t0δ0（xs）ds]. This Gibbs probability measure provides a simple model for a homopolymer with an attractive potential at the origin. In a previous paper（Cranston and Molchanov, 2007）, we showed that for dimensions d≥3 there is a phase transition in the behavior of these paths from the diffusive behavior for β below a critical parameter to the positive recurrent behavior for β above this critical value. The critical value was determined by means of the spectral properties of the operator ? + βδ0, where ? is the discrete Laplacian on Zd. This corresponds to a transition from a diffusive or stretched-out phase to a globular phase for the polymer. In this paper we give a description of the polymer at the critical value where the phase transition takes place. The behavior at the critical parameter is dimension-dependent.

关键词： Gibbs measure homopolymer phase transition globular phase diffusive phase

Retinal ganglion cell neuroprotection by growth factors and exosomes:lessons from mesenchymal stem cells

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2018年第2期13卷 228-229页

作者： Ben Mead stanislav Tomarev section of retinal ganglion cell biology laboratory of retinal cell and molecular biologynational eye institutenational institutes of healthBethesdaMDUSA

Retinal ganglions cells （RGCs） are responsible for propagating electrochemical information from the eye to the brain along their axons which make up the optic nerve. The loss of RGCs is characteristic in several conditions such as glaucoma and trau- matic optic neuropathy and leads to visual loss and blindness. While no therapy exists to directly treat RGCs, the use of bone marrow-derived mesenchymal stem cells （BMsCs） has shown promise in eliciting significant RGC neuroprotection.

关键词： BMsCs Retinal ganglion cell neuroprotection by growth factors and exosomes lessons from mesenchymal stem cells PDGFR

Tribological properties of the beetle leg joints

在线全文

学校读者我要写书评

暂无评论

Friction 2024年第12期12卷 2791-2807页

作者： Konstantin NADEIN Alexander KOVALEV stanislav N.GORB Functional Morphology and Biomechanics Zoological InstituteChristian-Albrechts University of KielAm Botanischen Garten 1-924118 KielGermany

Tribological properties of femoro-tibial leg joints in two beetles,darkling beetle Zophobas morio and Congo rose chafer Pachnoda marginata were *** low friction of 0.004 was revealed by the direct measurements in the *** is assumed that semi-solid lubricant functioning as in technical bearings is one of the leading factors of the friction *** of the surface texture and physical chemical properties(hydrophobicity)on the cuticle friction was *** of the surface texture to the tribological properties of contacting surfaces was examined by the measurement in the tribosystem“contacting surface/glass”.It is supposed that coefficient of friction(COF)decreases with decrease of surface *** the same time,no statistically significant correlation was found between the hydrophobicity of the surface and the value of the friction coefficient.

关键词： biotribology friction articulation contact angle surface texture lubrication

Contact mechanics of pad of grasshopper (Insecta:ORTHOPTERA) by finite element methods

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese science Bulletin 2009年第4期54卷 549-555页

作者： DAI ZhenDong GORB stanislav Institute of Bio-inspired structure and surface Engineering Nanjing University of Aeronautics and Astronautics Nanjing Jiangsu China 210016 Evolutionary Biomaterials Group Max-Planck-lnstitute for Metals Research Germany 70569

During locomotion, insect feet endure dramatic impact force and generate adhesive force which is controlled by the architecture of the foot. The patterns of smooth attachment pads in insect feet vary widely among insect orders and families. The functional significance of the micro-structure and geometric design of insect feet remains largely unknown. In this study, we developed a two-dimensional finite element model of a grasshopper's attachment pad. Realistic geometric microstructure and material properties are applied in the biomechanical analysis of the structural behavior during contact. Here we use scanning electronic microscopy to study the microstructure of the grasshopper's pad, and then use the finite element method to calculate the deformation vector fields, contact stiffness, contact area, function of the airbag and strain fields during the contact process. The results reveal that the geometric design and material topology of a grasshopper's pads are very effective in reducing contact stiffness, increasing contact area and generating high friction force during the contact procedure. The rod-containing structure supporting the soft exocuticle makes the pads highly adaptive to various surfaces and decreases the stress inside the pads.

关键词：蚱蜢接触机理昆虫脚接触表面生物模拟有限元分析

Fe-si particles on the surface of blast furnace coke

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2015年第7期22卷 697-703页

作者： stanislav s.Gornostayev Eetu-Pekka Heikkinen Jyrki J.Heino Timo M.J.Fabritius Process Metallurgy Group University of Oulu

This study investigates the surface of unpolished samples of blast furnace （BF） coke drilled from the tuyere zone, which hosts Fe-si particles （mostly Fe3si） that vary in size, shape, depth of submersion （penetration） into the coke matrix, and contact features with the surface. Based on the shape of the particles and the extent of their contact with the coke matrix, they have been grouped into three major types：（I） sphere-like droplets with limited contact area, （II） semi-spheres with a larger contact area, and （III） irregular segregations with a spherical surface, which exhibit the largest contact area among the three types of particles. Considering the ratio between the height （h） of the particles and half of their length at the surface level （/） along the cross-section, these three types can be characterized as follows：（I） h 〉/, （II） h ~/, and （1II） h 〈/. All the three types of particles can be found near each other. The shape and the extent of the contact depend on the de- gree of penetration of the material into the matrix, which is a function of the composition of the particles. Type （I） particles were initially saturated with si at an earlier stage and, for that reason, they can react less with carbon in the coke matrix than type （II） and （III）, thereby moving faster through the coke cone. Thermodynamic calculations have shown that the temperature interval of 1250-1300~C can be consid- ered the starting point for si entering into molten iron under quartz-dominated coke ash. Accordingly, the initial pick-up of si by molten iron can be assumed to be mineral-related. In terms of BF practice, better conditions for sliding Fe-si droplets through the coke cone are available when they come into contact with free siO2 concentrated into small grains, and when the siO2/∑MexOy mass ratio in the coke ash is high.

关键词： blast furnace practice metallurgical coke molten iron iron silicide

Plasma activated water prepared by different plasma sources:physicochemical properties and decontamination effect on lentils sprouts

在线全文

学校读者我要写书评

暂无评论

Plasma science and Technology 2022年第1期24卷 108-117页

作者： Veronika MEDVECKA samuel OMAsTA Matej KLAs silvia MOsOVsKA stanislav KYZEK Anna ZAHORANOVA Department of Experimental Physics Faculty of MathematicsPhysics and InformaticsComenius UniversityMlynska Dolina FI84248 BratislavaSlovakia Department of Nutrition and Food Quality Assessment Faculty of Chemical and Food TechnologySlovak University of TechnologyRadlinskeho 981107 BratislavaSlovakia Department of Genetics Faculty of Natural SciencesComenius UniversityIlkovicova 6Mlynska dolina84215 BratislavaSlovakia

The pulsed corona discharge(CD)generated in contact with water and directly in water,and high-power air plasma jet(APJ)were studied for production of plasma activated water(PAW).The changes of physical(pH,redox potential,conductivity,temperature)and chemical(peroxides,nitrites,nitrates concentrations)properties of treated water were *** comparison of CD generated in gas/water interface and underwater configuration in the same system showed that the interaction of reactive oxygen and nitrogen species formed in ambient air in gas/water system induces different chemical processes,leading to lower pH,higher oxidation-reduction potential(ORP)and higher conductivity of PAW than in underwater *** yield of peroxide was observed in both *** PAW prepared by APJ exhibits high concentration of nitrites and nitrates according to supplied energy,and related significant decrease of pH and increase of ORP and conductivity after *** antimicrobial effect of PAW prepared by CD and plasma jet on lentils sprouts was studied in different treatment and washing *** APJ appears to have great efficacy on water activation resulted in strong decontamination *** PAW treated by APJ for 10 min led to bacterial reduction from initial 8.3 to 5.9 and 4.0 log10 CFU g^(-1)after 10 and 30 min of washing,respectively.

关键词： plasma activated water physicochemical properties air plasma jet underwater plasma decontamination effect

Fe-si droplets associated with graphite on blast furnace coke

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2012年第6期19卷 478-482页

作者： stanislav s.Gornostayev Timo M.J.Fabritius Olavi Kerkkonen Jouko J.Hrkki Laboratory of Process Metallurgy University of OuluOulu 90014Finland Ruukki Metals Oy Raahe 92102Finland

Fe-si droplets on the surface of blast furnace （BF） coke from 25 to 50 cm at the tuyere level are mostly composed of Fe3si, which has various shapes （round, elongated, and irregular） and penetration degrees into the BF coke matrix. The shapes and penetration degrees may depend on the saturation of molten iron by silicon during interaction with the coke matrix. The droplets are covered by a tiny shell of carbon. Graphite observed inside the droplets can be divided into two categories： well-formed tabular crystals with relatively large size and flakes with structures similar as those in cast iron. The textures of the droplets reflect composition, interaction with the coke matrix, and cooling conditions.

关键词： metallurgical coke graphite iron blast furnaces

The forecast of fire impact on Pinus sylvestris renewal in southwestern siberia

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2021年第5期32卷 1911-1919页

作者： stanislav Nsannikov Nelly ssannikova Irina VPetrova Olga E.Cherepanova Botanical Garden of the Ural Branch of Russian Academy of science 202a8 Marta St.Yekaterinburg 620144Russia

simulation of fire impact on forest floor renewal in pine forests was based on predictions for 2100 by the Canadian Climate Centre for increase in temperatures of by4.5℃and total precipitation by 14%in the West siberian pre-forest-steppes and empirical regression relationships between them and the degree of burnt forest floor,as well as amount of Pinus sylvestris *** was predicted that by 2100,pine regeneration on fire prone sites under the canopy of the dominant forest type will increase by 29-54%compared to the 1980 s but on adjacent open sites,regeneration will decrease twice as *** means that the regeneration potential and pine population stability in pre-forest-steppes will become as poor as it is today.

关键词： Fire Forecast stability Population Mathematical model seeds Imitation model Undergrowth