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Kai, X.Z.,Li, Z.Q.,Fan, G.L.,Guo, Q.,Xiong, D.B.,Zhang, W.L.,Su, Y.S.,Lu, W.J.,Moon, W.J.,Zhang, D. Elsevier Sequoia 2013 Materials science & engineering. properties, micro Vol.587 No.-
Reinforcement agglomeration always leads to severe stress concentration and porosity, which is detrimental to the deformation ability and mechanical properties of particulate-reinforced metal matrix composites. In this study, uniform distribution of 32vol%B<SUB>4</SUB>C has been achieved in B<SUB>4</SUB>C/Al composite by means of flake powder metallurgy (Flake PM), in which flake Al powder is used as the starting material. The flake Al powder exhibits higher apparent volume than spherical powders of the same mass, and thus can provide more space to accommodate the B<SUB>4</SUB>C particles. Therefore, compared with conventional PM, Flake PM can lead to more uniform distribution of B<SUB>4</SUB>C particles in the composite powder as well as in the consolidated composite. Meanwhile, the flake Al powder has a nano skin of Al<SUB>2</SUB>O<SUB>3</SUB>, which could be fractured and dispersed inside the fine matrix grains during consolidation, and were found to induce a higher normalized strain hardening rate for the composite during deformation. As a result, the Flake PM 32vol%B<SUB>4</SUB>C/Al composite exhibits an ultimate tensile strength of 305MPa and a uniform elongation of 6.6%, 63% stronger and 13% more ductile than its counterpart fabricated by conventional PM.
Effect of Austempering Treatment on Microstructure and Mechanical Properties of M50NiL Bearing Steel
Y. B. Li,W. Ren,X. F. Yu,Y. Su,S. J. Wang,Y. Liu,S. Yang,W. J. Liu 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11
By means of microstructure observation, microhardness, tensile and rotating bending fatigue tests, the effects of austemperingtreatment on the formation of lower bainite, carbide precipitation and mechanical properties of M50NiL bearing steel werestudied. Results showed that multi-layer composite microstructure was formed in the steel after austempering treatment. Themicrostructure of the surface layer was mainly consisted of lower bainite, martensite and carbides, that of the sub-surfacelayer contained granular carbides, a little lower bainite, lath martensite, twin martensite and thin film retained austenite, andthat of the core region mostly contained lath martensite. In contrast with the traditional martensite quenching treatment,there was more lower bainite formed in the surface layer after austempering treatment. The appearance of acicular bainitedramatically decreased the effective grain size by refining the microstructure, and there were more finer carbides precipitatedin the lath martensite. After austempering treatment and tempering, the average hardness in surface layer of the steel increasedfrom 746.5 HV0.5to 786.4 HV0.5,and the rotating bending fatigue limit of the steel increased from 870.9 to 1170.0 MPa, butthe tensile strength of the steel decreased slightly. The effects of austempering treatment on the mechanical properties hada close relationship with the carbide precipitation behavior and the formation of lower bainite.
Silica colloidal crystals with uni- and multi-photonic bandgaps and controlled reflective properties
Piret, F.,Kwon, Y.-U.,Su, B.-L. Elsevier 2009 Chemical physics letters Vol.472 No.4
<P><B>Graphical abstract</B></P><P>The present Letter introduces a new concept in the field of 3D photonic crystals, for the first time, we prepared the 3D silica colloidal crystals containing multi-photonic bandgaps. This is achieved by creating multiple layer structures of two (or more) colloidal crystals with different lattice parameters. Each layer will diffract lights of its characteristic wavelength and the reflectance spectra are expected to present as many reflectance peaks as the number of layers.</P><ce:figure></ce:figure> <P><B>Abstract</B></P><P>High quality silica colloidal crystals with one or multi-photonic bandgaps that can be controlled in the whole range of the visible and near infrared lights have been designed. A comprehensive set of parameters that can predetermine the particle sizes from 150 to 750nm of the resulting silica colloids and their polydispersities was established. Self-assembly of such silica spheres produced highly organized colloidal crystals, leading to the photonic crystals of which the reflectance wavelengths can cover the whole range of visible lights and parts of the ultraviolet and infrared lights. Multiple deposition of silica spheres of two or more different sizes produced a heterostructured with multiple photonic bandgaps.</P>
Mapping of Quantitative Trait Loci on Porcine Chromosome 7 Using Combined Data Analysis
Zuo, B.,Xiong, Y.Z.,Su, Y.H.,Deng, C.Y.,Lei, M.G.,Zheng, R.,Jiang, S.W.,Li, F.E. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.10
To further investigate the regions on porcine chromosome 7 that are responsible for economically important traits, phenotypic data from a total of 287 F2 individuals were collected and analyzed from 1998 to 2000. All animals were genotyped for eight microsatellite loci spanning the length of chromosome 7. QTL analysis was performed using interval mapping under the line-cross model. A permutation test was used to establish significance levels associated with QTL effects. Observed QTL effects were (chromosomewide significance, position of maximum significance in centimorgans): Birth weight (<0.01, 3); Carcass length (<0.05, 80); Longissimus muscle area (<0.01, 69); Skin percentage (<0.01, 69); Bone percentage (<0.01, 74); Fat depths at shoulder (<0.05, 54);Mean fat depth (<0.05, 81); Moisture in m. Longissimus Dorsi (<0.05, 88). Additional evidence was also found which suggested QTL for dressing percentage and fat depths at buttock. This study offers confirmation of several QTL affecting growth and carcass traits on SSC7 and provides an important step in the search for the actual major genes involved in the traits of economic interest.
Yim, Su Y,Chae, Kab R,Shim, Sun B,Hong, Jin T,Park, Jung Y,Lee, Chung Y,Son, Hong J,Sheen, Yhun Y,Hwang, Dae Y D.A. Spandidos 2009 INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE Vol.24 No.1
<P>Selenium reportedly contribute to the modulation process of protein phosphorylation to regulate various cellular functions including growth, differentiation, proliferation and development. The aim of this study was to investigate whether selenium and Selenoprotein M (SelM) affects the mechanism of Alzheimer's disease. To achieve this, we determined the change of the MAPK pathway, secretase activity, and Tau phosphorylation in the transgenic rat overexpressing human selenoprotein M. Based on these results, we concluded that, i) CMV/GFP-hSelM Tg rats showed a high activity level of antioxidant enzyme in the brain tissues, ii) in response to selenium treatment, the ERK signaling pathway was significantly increased in Tg rats, but did not change in wild-type rats, iii) the activation of the ERK pathway by selenium treatment and SelM overexpression induced the inhibition of the alpha/gamma-secretase activity related to the protection of Abeta-42 production, iv) the activation of the ERK pathway by selenium treatment and SelM overexpression inhibited the phosphorylation in several sites of Tau protein. Therefore, these results provide strong evidence that selenium treatment and SelM activate the ERK pathway to attenuate alpha/gamma-secretase-mediated proteolysis and Tau phosphorylation to protect brain function.</P>
Hwang, Dae Y,Cho, Jung S,Kim, Chuel K,Shim, Sun B,Jee, Seung W,Lee, Su H,Seo, Su J,Choi, Soo Y,Kim, Yong K Springer Science + Business Media 2006 NEUROMOLECULAR MEDICINE Vol. No.
<P>Nonregulatable promoters have been mainly used to produce transgenic mice that express the human genes for Alzheimer's disease (AD). The aim of this study was to produce doubly transgenic mice expressing the regulatable tet promoter-controlled transactivator (tTA) and human mutant presenilin 2 (N141I, hPS2m) genes in order to examine the AD-related phenotypes at the basal and inducible levels. To achieve this, the first lineage of the transgenic line, expressing Tet/tTA and the second lineage of transgenic mice, expressing Tet/hPS2m, were created, and the doubly transgenic mice were produced by crossing the Tet/tTA-transgenic mice with the Tet/hPS2m-transgenic mice. The doubly transgenic mice and nontransgenic littermates were then treated with or without doxycycline. The results showed that removing doxycycline from the transgenic mice resulted in the induction of the transgene, a Wnt signaling defect, behavioral impairment, elevated amyloid-beta-42 and gamma-secretase activity compared with in the group given doxycyline. Moreover, the expression levels of the hPS2m transgene decreased gradually in the transgenic males, with clear changes becoming apparent between 2 and 4 wk of age. Castrating these males resulted in an increased expression level of the hPS2m gene. This was restored to the normal levels by treatment with testosterone. Therefore, tetregulated transgenic mice can be used to examine the effect of the basal or inducible expression levels of hPS2m on the pathology of AD at the 'on/off' states at any stage of development.</P>
Cha, J.Y.,Ahn, G.,Kim, J.Y.,Kang, S.B.,Kim, M.R.,Su'udi, M.,Kim, W.Y.,Son, D. Gauthier-Villars ; Elsevier Science Ltd 2013 Plant physiology and biochemistry Vol.70 No.-
The seven members of the 90-kDa heat shock protein (Hsp90) family encode highly conserved molecular chaperones essential for cell survival in Arabidopsis thaliana. Hsp90 are abundant proteins, localized in different compartments with AtHsp90.1-4 in the cytosol and AtHsp90.5-7 in different organelles. Among the AtHsp90, AtHsp90.1, is stress-inducible and shares comparatively low sequence identity with the constitutively expressed AtHsp90.2-4. Even though abundant information is available on mammalian cytosolic Hsp90 proteins, it is unknown whether cytosolic Hsp90 proteins display different structural and functional properties. We have now analyzed two A. thalianas cytosolic Hsp90s, AtHsp90.1 and AtHsp90.3, for functional divergence. AtHsp90.3 showed higher holdase chaperone activity than AtHsp90.1, although both AtHsp90s exhibited effective chaperone activity. Size-exclusion chromatography revealed different oligomeric states distinguishing the two Hsp90 proteins. While AtHsp90.1 exists in several oligomeric states, including monomers, dimers and higher oligomers, AtHsp90.3 exists predominantly in a high oligomeric state. High oligomeric state of AtHsp90.1 showed higher holdase chaperone activity than the respective monomer or dimer states. When high oligomeric forms of AtHsp90.1 and AtHsp90.3 are reduced by DTT, activity was reduced compared to that found in the native high oligomeric state. In addition, ATP-dependent foldase chaperone activity of AtHsp90.3 was higher with strong intrinsic ATPase activity than that of AtHsp90.1. As a conclusion, the two A. thaliana cytosolic Hsp90 proteins display different functional activities depending on structural differences, implying functional divergence although the proteins are localized to the same sub-cellular organelle.