Research on the method for producing complex SiCP/Al composite disk brake castings

Han Jianmin,Sha Zhensong,Li Weijing,Cui Shihai,Wang Jinhua 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

The casting properties of a SiCP/Al composite are analyzed in this paper and the methods for producing complex castings of SiCP/Al composite disk brake together with their difficulty are discussed. An adjustable vacuum pressure casting method is established on the basis of a normal adjustable pressure casting method. The SiCP/Al composite disk brake casting is made with the established method. The results show that the adjustable vacuum pressure casting is a successful casting method for producing SiCP/Al composite castings of large dimensions and complex structures, which gives few defects as confirmed by Xray real- time image system. The casting properties of a SiCP/Al composite are analyzed in this paper and the methods for producing complex castings of SiCP/Al composite disk brake together with their difficulty are discussed. An adjustable vacuum pressure casting method is established on the basis of a normal adjustable pressure casting method. The SiCP/Al composite disk brake casting is made with the established method. The results show that the adjustable vacuum pressure casting is a successful casting method for producing SiCP/Al composite castings of large dimensions and complex structures, which gives few defects as confirmed by Xray real- time image system.

Comparative Study of Wear Resistance and Surface Roughness of the Nanofiller Containing Composites and Microhybrid Composites

Jianmin Han,Hong Lin,Gang Zheng,Akiyoshi Shinya,Harunori Gomi,Akikazu Shinya,Jie Lin 대한치과재료학회 2011 대한치과기재학회 학술대회 Vol.2011 No.5

Oxidation kinetics of nitrogen doped TiO_{2−<i>δ</i>} thin films

Shi, Jianmin,Lee, Doh-Kwon,Yoo, Han-Ill,Janek, Jü,rgen,Becker, Klaus-Dieter The Royal Society of Chemistry 2012 Physical chemistry chemical physics Vol.14 No.37

<P>The oxidation kinetics of nitrogen doped, oxygen deficient titanium dioxide thin films has been studied in atmospheres of pure oxygen or nitrogen at 500 °C, 550 °C, and 600 °C, respectively, by means of <I>in situ</I> optical spectroscopy. The thin films show high electronic absorbance in the visible and NIR region, accompanied by a red shift of the absorption edge of about 0.4 eV, <I>e.g.</I>, from about 2.9 to 2.5 eV at 600 °C. The time dependent decrease of absorbance due to oxidation is found to follow a parabolic rate law. An activation energy of about 1.96 eV can be obtained from the temperature dependence of the parabolic oxidation rate constant. In the framework of a microscopic oxidation model, this energy barrier is attributed to the diffusion of titanium interstitials in the re-oxidized part of the thin films as a rate-determining process. In addition, an attempt is made to evaluate the kinetics of nitrogen release from the time dependent blue shift of the absorption edge during re-oxidation.</P> <P>Graphic Abstract</P><P>Oxidation kinetics of N-doped TiO<SUB>2−<I>δ</I></SUB> thin film has been studied using optical spectroscopy under <I>in situ</I> conditions, revealing the dominance of Ti<SUP>4+</SUP>-interstitial diffusion. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cp42559a'> </P>

The microstructure and corrosion resistance of micro-arc oxidation coatings on SiCp/A356 composites

Shihai Cui,Jianmin Han,Weijing Li,강석봉,이정무 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

Micro-arc oxidation (MAO) coatings were prepared on a SiCp/A356 composite. The microstructure and phase composition of the coatings on the SiCp/A356 composite were examined by XRD and SEM methods. It was found that there were two layers in the coating, a dense layer which was mainly composed of crystalline α-Al2O3 and a loose layer which consisted of γ-Al2O3 and mullite. The coating was well bonded to the SiCp/A356 substrate. The corrosion behavior of the coated and uncoated SiCp/ A356 composites was evaluated with a salt spray test and a potentiodynamic polarization technique. The results of the salt spray test showed that the coating could improve the corrosion resistance of SiCp/A356 by 11 times. The corrosion potential was shifted significantly in the anodic direction and the corrosion current density of the coated SiCp/A356 composite was reduced.

A study of the corrosion resistance of a micro-arc oxidation coating on a cast aluminum-copper alloy

Shihai Cui,Jianmin Han,Weijing Li,Xiangyang Xu,Yuanfu Liu 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

Protective coatings have been successfully prepared on a high strength aluminum-copper alloy ZL205 using a micro-arc oxidation (MAO) method. The influence of the oxidation time and current density on the thickness and corrosion resistance of MAO coatings has been studied. The thickness of MAO coating increases linearly with an increase of oxidation time. When the oxidation time is shorter than 20 minutes, the coating improves the corrosion resistance of ZL205 alloy quickly with an increase of oxidation time, which is confirmed by 5% salt spray test. When the oxidation time is longer than 20 minutes, the corrosion resistance of the MAO coating increases slowly with an increase of oxidation time. For a fixed oxidation time, the thickness of the MAO coating increases with an increase of current density and the corrosion resistance can also be improved. SEM and XRD analysis show that the surface morphology and phase of the MAO coating change with an increase of the oxidation time, which results in different corrosion resistance of the MAO coating. Protective coatings have been successfully prepared on a high strength aluminum-copper alloy ZL205 using a micro-arc oxidation (MAO) method. The influence of the oxidation time and current density on the thickness and corrosion resistance of MAO coatings has been studied. The thickness of MAO coating increases linearly with an increase of oxidation time. When the oxidation time is shorter than 20 minutes, the coating improves the corrosion resistance of ZL205 alloy quickly with an increase of oxidation time, which is confirmed by 5% salt spray test. When the oxidation time is longer than 20 minutes, the corrosion resistance of the MAO coating increases slowly with an increase of oxidation time. For a fixed oxidation time, the thickness of the MAO coating increases with an increase of current density and the corrosion resistance can also be improved. SEM and XRD analysis show that the surface morphology and phase of the MAO coating change with an increase of the oxidation time, which results in different corrosion resistance of the MAO coating.

Solidification simulation of a SiCp/Al disk brake casting

Zhiyong Yang,Jianmin Han,Shihai Cui,강석봉,이정무 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

A SiCp/Al composite disk brake casting for a high-speed application is produced using an adjustable vacuum pressure casting method specially developed for the production of SiCp/Al composite castings with complex structure. Feeding path during the solidification process of the disk brake casting is investigated by solidification simulation with a ProCAST code and checked by measurement of cooling curves. The simulation results match well with the measured cooling curves, which shows that the results of solidification simulation can be well used for a SiCp/Al composite casting production. With the help of solidification simulation, it is easy to establish a suitable feeding path that is the key technology for producing sound castings with the adjustable vacuum pressure casting method. Different casting plans with gating systems and chills are simulated and an improved casting plan for the disk brake casting is proposed based on the research presented in this paper. The casting quality is checked and confirmed by X-ray inspection and destructive inspection, which shows that the casting has few internal defects.

Identification a novel de novo RUNX2 frameshift mutation associated with cleidocranial dysplasia

Gong Lei,Odilov Bekzod,Han Feng,Liu Fuqiang,Sun Yujing,Zhang Ningxin,Zuo Xiaolin,Yang Jiaojiao,Wang Shouyu,Hou Xinguo,Ren Jianmin 한국유전학회 2022 Genes & Genomics Vol.44 No.6

Background: Cleidocranial dysplasia (CCD) is a rare genetic disorder affecting bone and cartilage development. Clinical features of CCD comprise short stature, delayed ossification of craniofacial structures with numerous Wormian bones, underdeveloped or aplastic clavicles and multiple dental anomalies. Several studies have revealed that CCD development is strongly linked with different mutations in runt-related transcription factor 2 (RUNX2) gene. Objective: Identification and functional characterization of RUNX2 mutation associated with CCD. Methods: We performed genetic testing of a patient with CCD using whole exome sequencing and found a novel RUNX2 frameshift mutation: c.1550delT in a sporadic case. We also compared the functional activity of the mutant and wild-type RUNX2 through immunofluorescence microscopy and osteocalcin promoter luciferase assay. Results: We found a novel RUNX2 frameshift mutation, c.1550delT (p.Trp518Glyfs*60). Both mutant RUNX2 and wild-type RUNX2 protein were similarly confined in the nuclei. The novel mutation caused abrogative transactivation activity of RUNX2 on osteocalcin promoter. Conclusions: We explored a novel RUNX2 deletion/frameshift mutation in a sporadic CCD patient. This finding suggests that the VWRPY domain may play a key role in RUNX2 transactivation ability.

Identification of genes involved in inbreeding depression of reproduction in Langshan chickens

Xue Qian,Li Guohui,Cao Yuxia,Yin Jianmei,Zhu Yunfen,Zhang Huiyong,Zhou Chenghao,Shen Haiyu,Dou Xinhong,Su Yijun,Wang Kehua,Zou Jianmin,Han Wei 아세아·태평양축산학회 2021 Animal Bioscience Vol.34 No.6

Objective: Inbreeding depression of reproduction is a major concern in the conservation of native chicken genetic resources. Here, based on the successful development of strongly inbred (Sinb) and weakly inbred (Winb) Langshan chickens, we aimed to evaluate inbreeding effects on reproductive traits and identify candidate genes involved in inbreeding depression of reproduction in Langshan chickens. Methods: A two-sample t-test was performed to estimate the differences in phenotypic values of reproductive traits between Sinb and Winb chicken groups. Three healthy chickens with reproductive trait values around the group mean values were selected from each of the groups. Differences in ovarian and hypothalamus transcriptomes between the two groups of chickens were analyzed by RNA sequencing (RNA-Seq). Results: The Sinb chicken group showed an obvious inbreeding depression in reproduction, especially for traits of age at the first egg and egg number at 300 days (p<0.01). Furthermore, 68 and 618 differentially expressed genes (DEGs) were obtained in the hypothalamus and ovary between the two chicken groups, respectively. In the hypothalamus, DEGs were mainly enriched in the pathways related to vitamin metabolism, signal transduction and development of the reproductive system, such as the riboflavin metabolism, Wnt signaling pathway, extracellular matrix-receptor interaction and focal adhesion pathways, including stimulated by retinoic acid 6, serpin family F member 1, secreted frizzled related protein 2, Wnt family member 6, and frizzled class receptor 4 genes. In the ovary, DEGs were significantly enriched in pathways associated with basic metabolism, including amino acid metabolism, oxidative phosphorylation, and glycosaminoglycan degradation. A series of key DEGs involved in folate biosynthesis (gamma-glutamyl hydrolase, guanosine triphosphate cyclohydrolase 1), oocyte meiosis and ovarian function (cytoplasmic polyadenylation element binding protein 1, structural maintenance of chromosomes 1B, and speedy/RINGO cell cycle regulator family member A), spermatogenesis and male fertility (prostaglandin D2 synthase 21 kDa), Mov10 RISC complex RNA helicase like 1, and deuterosome assembly protein 1) were identified, and these may play important roles in inbreeding depression in reproduction. Conclusion: The results improve our understanding of the regulatory mechanisms underlying inbreeding depression in chicken reproduction and provide a theoretical basis for the conservation of species resources. Objective: Inbreeding depression of reproduction is a major concern in the conservation of native chicken genetic resources. Here, based on the successful development of strongly inbred (Sinb) and weakly inbred (Winb) Langshan chickens, we aimed to evaluate inbreeding effects on reproductive traits and identify candidate genes involved in inbreeding depression of reproduction in Langshan chickens.Methods: A two-sample t-test was performed to estimate the differences in phenotypic values of reproductive traits between Sinb and Winb chicken groups. Three healthy chickens with reproductive trait values around the group mean values were selected from each of the groups. Differences in ovarian and hypothalamus transcriptomes between the two groups of chickens were analyzed by RNA sequencing (RNA-Seq).Results: The Sinb chicken group showed an obvious inbreeding depression in reproduction, especially for traits of age at the first egg and egg number at 300 days (p<0.01). Furthermore, 68 and 618 differentially expressed genes (DEGs) were obtained in the hypothalamus and ovary between the two chicken groups, respectively. In the hypothalamus, DEGs were mainly enriched in the pathways related to vitamin metabolism, signal transduction and development of the reproductive system, such as the riboflavin metabolism, Wnt signaling pathway, extracellular matrix-receptor interaction and focal adhesion pathways, including stimulated by retinoic acid 6, serpin family F member 1, secreted frizzled related protein 2, Wnt family member 6, and frizzled class receptor 4 genes. In the ovary, DEGs were significantly enriched in pathways associated with basic metabolism, including amino acid metabolism, oxidative phosphorylation, and glycosaminoglycan degradation. A series of key DEGs involved in folate biosynthesis (gamma-glutamyl hydrolase, guanosine triphosphate cyclohydrolase 1), oocyte meiosis and ovarian function (cytoplasmic polyadenylation element binding protein 1, structural maintenance of chromosomes 1B, and speedy/RINGO cell cycle regulator family member A), spermatogenesis and male fertility (prostaglandin D2 synthase 21 kDa), Mov10 RISC complex RNA helicase like 1, and deuterosome assembly protein 1) were identified, and these may play important roles in inbreeding depression in reproduction.Conclusion: The results improve our understanding of the regulatory mechanisms underlying inbreeding depression in chicken reproduction and provide a theoretical basis for the conservation of species resources.