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Boundary Layer and Cooling Rate and Microstructure Formation on the Cooling Sloping Plate
Ren Guo Guan,Zhan Yong Zhao,Run Ze Chao,Lei Dong,이종수,Chun Ming Liu 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.5
During melt treatment by cooling sloping plate, laminar flow and turbulent flow exist on sloping plate surface commonly. The thickness of velocity boundary layer and the critical transfer distance from laminar flow to turbulent flow increase with the decrease of initial flow velocity. The thickness of temperature boundary layer increases with the increment of flow distance and the decrease of initial flow velocity. The melt cooling rate and melt thickness have an inverse proportion relationship. The melt cooling rate of cooling sloping plate process can reach 102-103 K/s and belongs to meta-rapid solidification scope. Uniform solute field and high cooling rate can lead to eruptive nucleation. In addition, a large quantity of heterogonous nuclei appears on the sloping plate surface, and vibrating flow can enable heterogonous nucleus to escape off the plate, which leads to nucleus multiplication. Under relative uniform solute field and high cooling rate, some grains can keep stable growth surface, go on growing with the round surface and finally maintain their globular structure. However, there are always some grains that grow along a certain preferred direction, but under vibrating flow their dendritic arms break and transform into near spherical structure.
Ren, Xiao-Yan,Niu, Chun-Yao,Chen, Wei-Guang,Tang, Ming-Sheng,Cho, Jun-Hyung The Royal Society of Chemistry 2016 Physical chemistry chemical physics Vol.18 No.27
<P>Exploring the properties of noble metal atoms and nano- or subnano-clusters on the semiconductor surface is of great importance in many surface catalytic reactions, self-assembly processes, crystal growth, and thin film epitaxy. Here, the energetics and kinetic properties of a single Cu atom and previously reported Cu magic clusters on the Si(111)-(7 x 7) surface are re-examined by the state-of-the-art first-principles calculations based on density functional theory. First of all, the diffusion path and high diffusion rate of a Cu atom on the Si(111)-(7 x 7) surface are identified by mapping out the total potential energy surface of the Cu atom as a function of its positions on the surface, supporting previous experimental hypothesis that the apparent triangular light spots observed by scanning tunneling microscopy (STM) are resulted from a single Cu atom frequently hopping among adjacent adsorption sites. Furthermore, our findings confirm that in the low coverage of 0.15 monolayer (ML) the previously proposed hexagonal ring-like Cu-6 cluster configuration assigned to the STM pattern is considerably unstable. Importantly, the most stable Cu-6/Si(111) complex also possesses a distinct simulated STM pattern with the experimentally observed ones. Instead, an energetically preferred solid-centered Cu-7 structure exhibits a reasonable agreement between the simulated STM patterns and the experimental images. Therefore, the present findings convincingly rule out the tentative six-atom model and provide new insights into the understanding of the well-defined Cu nanocluster arrays on the Si(111)-(7 x 7) surface.</P>
Yong Chun Li,Fan Rong Meng,Chun Yan Zhang,Ning Zhang,Ming Shan Sun,Jiang Ping Ren,Hong Bin Niu,Xiang Wang,Jun Yin 한국식물학회 2012 Journal of Plant Biology Vol.55 No.5
To understand better the mechanisms that regulate the water stress response in wheat, we conducted a comparative analysis of transcript profiles in roots from two wheat genotypes -- drought-tolerant ‘Luohan No. 2’ (LH)and drought-susceptible ‘Chinese Spring’ (CS). In LH roots,3831 transcripts displayed changes in expression of at least two-fold over the well-watered control when drought treatment was applied. Of these, 1593 were induced while 2238 were repressed. Relatively fewer transcripts were drought-responsive in CS; i.e., 1404 transcripts were induced and 1493 were repressed. In common between LH and CS,569 transcripts were induced and 424 transcripts were repressed. In all, 689 transcripts (757 probe sets) identified from LH and 537 transcripts (575 probe sets) from CS were annotated and classified into 10 functional categories. Among those annotated transcripts from LH and CS that had fold-change ratios of at least 4, 92 induced transcripts were common to both, while 23 transcripts were specifically induced in LH. Gene ontology analysis of these induced genes showed highly significant enrichment for multiple terms related to abiotic stimuli, organic acid biosynthesis,and lipid metabolism. This suggests that these gene groups play important roles during the stress response in LH and CS, and might also be responsible for differences in drought tolerance between those genotypes.
Anti-proliferation Effects of Isorhamnetin on Lung Cancer Cells in Vitro and in Vivo
Li, Qiong,Ren, Fu-Qiang,Yang, Chun-Lei,Zhou, Li-Ming,Liu, Yan-You,Xiao, Jing,Zhu, Ling,Wang, Zhen-Grong Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.7
Background: Isorhamnetin (Iso), a novel and essential monomer derived from total flavones of Hippophae rhamnoides that has long been used as a traditional Chinese medicine for angina pectoris and acute myocardial infarction, has also shown a spectrum of antitumor activity. However, little is known about the mechanisms of action Iso on cancer cells. Objectives: To investigate the effects of Iso on A549 lung cancer cells and underlying mechanisms. Materials and Methods: A549 cells were treated with $10{\sim}320{\mu}g/ml$ Iso. Their morphological and cellular characteristics were assessed by light and electronic microscopy. Growth inhibition was analyzed by MTT, clonogenic and growth curve assays. Apoptotic characteristics of cells were determined by flow cytometry (FCM), DNA fragmentation, single cell gel electrophoresis (comet) assay, immunocytochemistry and terminal deoxynucleotidyl transferase nick end labeling (TUNEL). Tumor models were setup by transplanting Lewis lung carcinoma cells into C57BL/6 mice, and the weights and sizes of tumors were measured. Results: Iso markedly inhibited the growth of A549 cells with induction of apoptotic changes. Iso at $20{\mu}g/ml$, could induce A549 cell apoptosis, up-regulate the expression of apoptosis genes Bax, Caspase-3 and P53, and down-regulate the expression of Bcl-2, cyclinD1 and PCNA protein. The tumors in tumor-bearing mice treated with Iso were significantly smaller than in the control group. The results of apoptosis-related genes, PCNA, cyclinD1 and other protein expression levels of transplanted Lewis cells were the same as those of A549 cells in vitro. Conclusions: Iso, a natural single compound isolated from total flavones, has antiproliferative activity against lung cancer in vitro and in vivo. Its mechanisms of action may involve apoptosis of cells induced by down-regulation of oncogenes and up-regulation of apoptotic genes.
Wang, Shao-Ming,Zhang, Shao-Kai,Pan, Xiong-Fei,Ren, Ze-Fang,Yang, Chun-Xia,Wang, Zeng-Zhen,Gao, Xiao-Hong,Li, Man,Zheng, Quan-Qing,Ma, Wei,Zhao, Fang-Hui,Qiao, You-Lin,Sivasubramaniam, Priya Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.7
Background: College students are recommended as the target groups for catch-up human papillomavirus (HPV) vaccination. Systematical exploration of awareness, acceptability, and decision-making factors of HPV vaccination among Chinese college students has been limited. Materials and Methods: A multi-center survey was conducted in mainland China between November 2011 and May 2012. College students aged 18-22 years were stratified by their grade, gender, and major for sampling. Socio-demographic and HPV-related information such as knowledge, perceptions, acceptability, and attitudes were collected through a questionnaire. Results: A total of 3,497 undergraduates completed the questionnaire, among which 1,686 were males. The acceptability of the HPV vaccine was high (70.8%). Undergraduates from high-level universities, at lower grade, or with greater prior knowledge of HPV vaccines showed higher acceptability of HPV vaccination ($p_{trend}$ <0.001). Additionally, undergraduates with vaccination experience outside the National Expanded Program on Immunization (OR=1.29; 95%CI: 1.10-1.51) or fear of HPV-related diseases (OR=2.79; 95%CI: 2.28-3.41) were more willing to accept HPV vaccination. General knowledge of HPV vaccine was low among undergraduates, and safety was a major concern (71.05%). The majority of students wished to pay less than 300RMB for HPV vaccine and chose the Chinese Center for Disease Control and Prevention as the most appropriate venue for vaccination. Conclusions: Although most undergraduates demonstrate positive attitudes towards HPV vaccination, challenges pertaining to introduction exist in China. Corresponding proactive education and governmental subsidy to do so are urgently needed by this age-group population. Suggestions and potential strategies indicated may help shape the future HPV vaccination program in China.
Xian-Li Gao,Chun Cui,Hai-Feng Zhao,Mou-Ming Zhao,Lan Yang,Jiao-Yan Ren 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.4
Considering the important influence of longtime (150 day) moromi fermentation and heat treatment on the aroma formation of traditional Chinese-type soy sauce (TCSS), volatile compounds in samples taken from different stages of moromi fermentation and heat treatment were analyzed by solid phase microextraction coupled with gas chromatography-mass spectrometry. Results showed that a total of 76 volatile compounds were identified in all the samples, and most of the volatile compounds were common. During 150 day of moromi fermentation, relative contents of acids, alcohols, aldehydes and ketones, esters,and furan(one)s along with all the sensory attributes of acidic, alcoholic, fruity, caramel-like, smoky, and malty changed greatly. Notably, relative contents of alcohols,aldehydes and ketones along with the sensory intensities of alcoholic, caramel-like, and smoky of heated sample (80℃/60 min) decreased markedly, whereas there were slight increases in relative contents of furan(one)s, phenols,and sulfur-containing compounds of it. Long-time moromi fermentation and heat treatment have significant influence on the formation and relative contents of volatile compounds in TCSS, whereas changes in volatile compounds and their relative contents of the samples were responsible for the differences in sensory attributes.
Zhan Yong Zhao,Ren Guo Guan,Xiang Wang,Yang Li,Lei Dong,이종수,Chun Ming Liu 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.5
A melt treatment with a vibrating cooling slope and a semisolid rolling process to produce an AZ61 alloy strip was proposed. The microstructure formation mechanism and the properties of the AZ61 alloy produced by the proposed process were investigated. Due to the high cooling rate and stirring action caused by the vibration cooling slope, the nucleation rate was greatly improved, which caused the formation of fine spherical or rosette primary grains. During the rolling process, the solid fraction increased from the entrance to the exit of the roll gap, and under the shearing action of the roller, the distribution of solute in the melt was homogenous, and the primary grains grew further. When the casting temperature was 680 °C,a strip with a cross section of 4 mm×160 mm was produced and a homogeneous microstructure was obtained. The ultimate tensile strength of the AZ61 alloy strip produced by the proposed method reached 242 MPa, and the corresponding elongation to failure was 4%, which were better than those achieved in previous similar studies.
Jing-Han Chen,Chi-Te Liang,Chun-Feng Huang,Da-Ren Hang,David A. Ritchie,J. C. Hsiao,Jyun-Ying Lin,Michelle Y. Simmons,Ming-Gu Lin,S. H. Lo,Tsai-Yu Huang 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3
By applying a magnetic field perpendicular to GaAs/AlGaAs two-dimensional electron systems (2DESs), we study the low-field Landau quantization when the thermal damping is reduced with decreasing temperature. Magneto-oscillations following the Shubnikov-de Haas (SdH) formula are observed even when their amplitudes are so large that the deviation to such a formula is expected. Our experimental results show the importance of the positive magneto-resistance to the extension of the SdH formula under the damping induced by the disorder.