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Sintering, thermal stability and mechanical properties of ZrO2-WC composites obtained by pulsed electric current sintering

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Frontiers of Materials Science 2011年第1期5卷 50-56页

作者： Shuigen HUANG Kim VANMEENSEL Omer VAN DER BLEST jozef vleugels Department of Metallurgy and Materials Engineering Katholieke Universiteit Leuven Kasteelpark Arenberg 44 B-3001 Heverlee Belgium

ZrO2-WC composites exhibit comparable mechanical properties as traditional WC-Co materials, which provides an opportunity to partially replace WC-Co for some applications. In this study, 2 mol.% Y2O3 stabilized ZrO2 composites with 40 vol.% WC were consolidated in the 1150℃-1850℃ range under a pressure of 60 MPa by pulsed electric current sintering （PECS）. The densification behavior, microstructure and phase constitution of the composites were investigated to clarify the role of the sintering temperature on the grain growth, mechanical properties and thermal stability of ZrO2 and WC components. Analysis results indicated that the composites sintered at 1350℃ and 1450℃ exhibited the highest tetragonal ZrO2 phase transformability, maximum toughness, and hardness and an optimal flexural strength. Chemical reaction of ZrO2 and C, originating from the graphite die, was detected in the composite PECS for 20 min at 1850℃ in vacuum.

关键词： ceramic composite pulsed electric current sintering (PECS) grain size,mechanical property

Developmental- and food-dependent foraging transcript levels in the desert locust

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Insect Science 2013年第6期20卷 679-688页

作者： Julie Tobback Heleen Verlinden Kristel Vuerinckx Rut vleugels jozef Vanden Broeck Roger Huybrechts Department of Biology K.U.Leuven Naamsestraat 59 3000 Leuven Belgium

Drastic changes in the environment during a lifetime require developmental and physiological flexibility to ensure animal survival. Desert locusts, Schistocerca gregaria, live in an extremely changeable environment, which alternates between periods of rainfall and abundant food and periods of drought and starvation. In order to survive, locusts display an extreme form ofphenotypic plasticity that allows them to rapidly cope with these changing conditions by converting from a cryptic solitarious phase to a swarming, voracious gregarious phase. To accomplish this, locusts possess different conserved mediators of phenotypic plasticity. Recently, attention has been drawn to the possible roles of protein kinases in this process. In addition to cyclic AMP-dependent protein kinase （PKA）, also cyclic GMP-dependent protein kinase （PKG）, which was shown to be involved in changes of food-related behavior in a variety of insects, has been associated with locust phenotypic plasticity. In this article, we study the transcript levels of the S. gregaria orthologue of the foraging gene that encodes a PKG in different food-related, developmental and crowding conditions. Transcript levels of the S. gregariaforaging orthologue are highest in different parts of the gut and differ between isolated and crowd-reared locusts. They change when the availability of food is altered, display a distinct pattern with higher levels after a moult and decrease with age during postembryonic development.

关键词： cyclic GMP-dependent protein kinase feeding neuronal plasticity nutri- tional state Schistocerca gregaria

In-situ Synthesis and Densification of B4C-（Zr,Ti）B2 Composites by Pulsed Electric Current Sintering

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Journal of the Chinese Ceramic Society 2014年第2期 113-121页

作者： HUANG Shuigen VANMEENSEL Kim vleugels jozef Department of Materials Engineering KU LeuvenKasteelpark Arenberg 44-Bus 2450B-3001 HeverleeBelgium

B4C composites with 30 vol.%dispersed ultrafine grains of ZrB2,TiB2and(Zr0.5Ti0.5)B2were prepared via pulsed electric current sintering of B4C,ZrO2,TiO2and carbon black as mixed starting powders in vacuum at 2 000 ℃.The full-densification was obtained when an optimized synthesizing and sintering cycle at the maximum pressure of 30 MPa was applied after the completion of the in-situ powder synthesis,allowing the degasification of volatile *** influence of sintering temperature on the phase constitution and microstructure during in-situ synthesis and densification was investigated in the interrupted sintering cycles at 1 400 and 2 000℃.According to the analysis by electron probe microanalysis and X-ray diffraction,the in-situ conversion of TiO2/ZrO2to TiB2/ZrB2is a complex process in which TiO2/ZrO2is initially converted to TiB2/ZrB2with the formation of B2O3as an intermediate product at a low *** 2 000 ℃,B2O3reacts completely with C to form B4C and CO.A solid solution boride phase of(Zr0.5Ti0.5)B2is formed when two oxides are used in a 50/50 molar ratio.

关键词： boride ceramic composite in-situ synthesis spark plasma sintering grain size

烧结温度和添加碳化物对NbC-Ni基金属陶瓷显微组织和力学性能的影响

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硬质合金 2018年第2期35卷 69-78页

作者：黄水根 vleugels jozef Cannizza Eduardo Woydt Mathias 刘中柱 Mohrbacher Hardy KU Leuven Department of Materials Engineering(MTM)HeverleeBelgium EHT-Engineering Consulting Ltd. Sao PauloBrazil BAM Federal Institute for Materials Research and Testing Division 63 Tribology&Wear ProtectionBerlinGermany 中信金属有限公司北京100004 NiobelCon SehildeBelgium

本文报道了烧结温度和添加碳化物(VC、Mo_2C和TiC)以及Mo金属对一种新型NbC-Ni基金属陶瓷的致密化、NbC晶粒生长、显微组织演变以及维氏硬度(HV30)和断裂韧性的影响。所有的金属陶瓷均采用真空无压烧结制备,使用电子探针显微分析(EPMA)... 详细信息

本文报道了烧结温度和添加碳化物(VC、Mo_2C和TiC)以及Mo金属对一种新型NbC-Ni基金属陶瓷的致密化、NbC晶粒生长、显微组织演变以及维氏硬度(HV30)和断裂韧性的影响。所有的金属陶瓷均采用真空无压烧结制备,使用电子探针显微分析(EPMA)以及X射线衍射(XRD)来分析试样的微观组织、相组成及晶格常数的变化。结果表明,烧结温度,特别是添加碳化物的含量对NbC-Ni金属陶瓷的性能有显著的影响。当烧结温度低于1 340°C时,试样内存在Ni池和残余孔隙。温度高于1 380℃时,添加VC或Mo/Mo_2C的NbC-Ni基金属陶瓷达到完全致密,呈现出类似于WC-Co的两相组织结构。同时添加TiC+VC或TiC+Mo_2C的材料则形成一种含有芯环结构的NbC晶粒。相对于无添加的NbC-Ni金属陶瓷,添加体积分数5%~10%VC/Mo_2C和10%TiC能够明显提高材料的硬度和断裂韧性。

关键词：金属陶瓷碳化铌镍烧结力学性能

Synthesis and crystal structure study of 2′-Se-adenosine-derivatized DNA

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Science China Chemistry 2010年第1期53卷 78-85页

作者： SALON jozef Department of Chemistry Georgia State University

The selenium derivatization of nucleic acids is a novel and promising strategy for 3D structure determination of nucleic *** can serve as an excellent anomalous scattering center to solve the phase problem,which is one of the two major bottlenecks in macromolecule X-ray *** other major bottleneck is *** has been demonstrated that the incorporated selenium functionality at the 2′-positions of the nucleosides and nucleotides is stable and does not cause significant structure ***,it was observed that the 2′-Se-derivatization could facilitate crystallization of oligonucleotides with fast crystal growth and high diffraction ***,we describe a convenient synthesis of the 2′-Se-adenosine phosphoramidite,and report the first synthesis and X-ray crystal structure determination of the DNA containing the 2′-Se-A *** 3D structure of 2′-Se-A-DNA decamer 5′-GTACGCGT(2′-Se-A)C-3′2 was determined at 1.75 ? resolution,the 2′-Se-functionality points to the minor groove,and the Se-modified and native structures are virtually ***,we have observed that the 2′-Se-A modification can greatly facilitate the crystal growth with high diffraction *** conjunction with the crystallization facilitation by the 2′-Se-U and 2′-Se-T,this novel observation on the 2′-Se-A functionality suggests that the 2′-Se moiety is sole responsible for the crystallization facilitation and the identity of nucleobases does not influence the crystal growth significantly.

关键词： selenium derivatization nucleic acid adenosine X-ray crystallography structure determination

Basic theorem as representation of heterogeneous concept lattices

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Frontiers of Computer Science 2015年第4期9卷 636-642页

作者： jozef POCS Jana POCSOVA Palacky University Olomouc Department of Algebra and Geometry Olomouc 779 00 Czech Republic Mathematical Institute Slovak Academy of Sciences Kosice 040 01 Slovakia Technical University of Kosice BERG Faculty Institute of Control and Informatization of Production Processes Ko~ice 043 84 Slovakia

We propose a method for representing heteroge- neous concept lattices as classical concept lattices. Particu- larly, we describe a transformation of heterogeneous formal context into a binary one, such that corresponding concept lattices will be isomorphic. We prove the correctness of this transformation by the basic theorem for heterogeneous as well as classical concept lattices.

关键词： basic theorem heterogeneous concept lattice,representation

Corrosion Resistance of AZ91 Magnesium Alloy after Laser Remelting Treatment

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Journal of Wuhan University of Technology(Materials Science) 2016年第5期31卷 1075-1080页

作者： STRZELECKA Monika IWASZKO jozef MALIK Marcin A Czestochowa University of Technology 42-200 Czestochowa Poland

The main objective of the study was the modification of the surface layer of magnesium alloy by the COlaser. The studied material was the commercial AZ91 magnesium alloy. The effectiveness of the alternations caused by the remelting process was verified on the basis of microscopic observation and corrosion investigations, i e, recording of potentiodynamic polarization curves, electrochemical noise measurements and hydrogen evolution rate measurements. For the adopted range of the treatment parameters, favourable changes were observed in the surface layer such as the refinement of structure and more uniform arrangement of individual phases. As a consequence of those favourable structural changes the improvement of the corrosion resistance of the alloy was achieved in comparison to its non-remelted equivalent. For the treated material corrosion rates expressed as corrosion current densities were at least three times lower than the appropriate values for the untreated alloy comparing them for the same period of samples immersion in the test solution. The obtained results have confirmed the effectiveness of the applied surface treatment resulting in favourable changes in the structure and corrosion properties of the AZ91 magnesium alloy.

关键词： magnesium alloy CO_2 laser surface layer modification corrosion

Impact of Informatics on QIPC

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南京邮电大学学报（自然科学版） 2011年第2期31卷 40-48页

作者： jozef Gruska Faculty of Informatics Masaryk University Botanická 68a

Quantum information processing and communication(QIPC) is an area of science that has two main goals: On one side,it tries to explore(still not well known) potential of quantum phenomena for(efficient and reliable) information processing and(efficient,reliable and secure) *** the other side,it tries to use quantum information storing,processing and transmitting paradigms,principles,laws,limitations,concepts,models and tools to get deeper insights into the phenomena of quantum world and to find efficient ways to describe and handle/simulate various complex physical *** order to do that QIPC has to use concepts,models,theories,methods and tools of both physics and *** main role of physics at that is to discover primitive physical phenomena that can be used to design and maintain complex and reliable information storing,processing and transmitting *** main role of informatics is,one one side,to explore,from the information processing and communication point of view,limitations and potentials of the potential quantum information processing and communication technology,and to prepare information processing methods that could utilise potential of quantum information processing and communication *** the other side,the main role of informatics is to guide and support,by theoretical tools and outcomes,physics oriented research in *** paper is to describe and analyse a variety of ways and potential informatics contributes and should/could contribute to the development of QIPC--see also Gruska(1999,2006,2008).

关键词： Informatics quantum complexity theory quantum cryptography quantum algorithm

Heavy Metal Adsorption Properties of Marine Algae Durvilliea Potatorum,Ecklonia Radiata and Laminaria Japonica

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Chinese Journal of Chemical Engineering 1998年第1期6卷 72-76页

作者：虞启明 Jose T.Matheickal jozef Latten School of Environmental Engineering Griffith University

1 INTRODUCTIONBiosorption of heavy metals using biosorbents derived from suitable biomass is a new tech-nology for the removal and recovery of heavy metals from industrial waste *** ad-vantages of the biosorption technology include rapid reduction of dissolved heavy metal ionsconcentration to 10-6and 10-9levels,use of inexpensive and non-hazardous biosorbents,useof existing adsorption process equipment and therefore low operating costs,high uptake ca-pacity and specificity for selective heavy metal removals,and low interference from

关键词： biosorption heavy metal removal marine algae