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81.
实验表明,采用可关断可控硅(GTO)开关元件在明渠水流中产生氢泡线,这一技术可以用在水质较差的大型水槽中进行流场显示. 相似文献
82.
83.
Sung Hwan Hong Jeong Tae Kim Jin Man Park Gian Song Wei-Min Wang Ki Buem Kim 《自然科学进展(英文版)》2018,28(6):704-710
Ti_(45)Cu_(40)Ni_7Zr_5Sn_(2.5)Si_(0.5) alloys were prepared under various cooling rate conditions during solidification.The alloys exhibited different volume fractions of B2 particles with 0~40 vol%in an amorphous matrix.Monolithic bulk metallic glass of 1 mm diameter showed no macroscopic plasticity and exhibited the typical vein patterns in a maximum shear stress plane on the fracture surface.However,a bulk metallic glass composite containing the B2 particles revealed obvious plasticity(~5.6%)with a remarkable work-hardening behavior that resulted from a stress-induced martensitic transformation of the B2 particles.Moreover,the composite displayed the complicated fracture morphologies containing of three types of fracture features.Through detailed investigations on the microstructural evolution,mechanical,deformation and fracture characteristics,the influence of B2 particle on overall behavior of the TiCu-based bulk metallic glass composites was elucidated. 相似文献
84.
Hongsheng Chen Sung Hwan Kim Chongsheng Long Chaewon Kim Changheui Jang 《自然科学进展(英文版)》2018,28(6):731-739
The oxidation behavior of three high-strength FeCrAl alloys was investigated in supercritical carbon dioxide environment at 650 ℃. After exposure for 500 h, the weight gains of the FeCrAl alloys gradually decreased with increasing Al content. The oxide scales are primarily composed of α-Al_2O_3 and spinel oxides. With increasing Al content, the amount of α-Al_2O_3 increases and the C content decreased in the oxide scale and sub-scale matrix.Moreover, larger(Nb,Mo)C carbides formed in the sub-scale matrix and their number decreased with the increase of Al content. 相似文献
85.
John J. Sung 《Foundations of Science》2008,13(2):177-193
Scientific anomalies are observations and facts that contradict current scientific theories and they are instrumental in scientific
theory change. Philosophers of science have approached scientific theory change from different perspectives as Darden (Theory
change in science: Strategies from Mendelian genetics, 1991) observes: Lakatos (In: Lakatos, Musgrave (eds) Criticism and
the growth of knowledge, 1970) approaches it as a progressive “research programmes” consisting of incremental improvements
(“monster barring” in Lakatos, Proofs and refutations: The logic of mathematical discovery, 1976), Kuhn (The structure of
scientific revolutions, 1996) observes that changes in “paradigms” are instigated by a crisis from some anomaly, and Hanson
(In: Feigl, Maxwell (eds) Current issues in the philosophy of science, 1961) proposes that discovery does not begin with hypothesis
but with some “problematic phenomena requiring explanation”. Even though anomalies are important in all of these approaches
to scientific theory change, there have been only few investigations into the specific role anomalies play in scientific theory
change. Furthermore, much of these approaches focus on the theories themselves and not on how the scientists and their experiments
bring about scientific change (Gooding, Experiment and the making of meaning: Human agency in scientific observation and experiment,
1990). To address these issues, this paper approaches scientific anomaly resolution from a meaning construction point of view.
Conceptual integration theory (Fauconnier and Turner, Cogn Sci 22:133–187, 1996; The way we think: Conceptual blending and
mind’s hidden complexities, 2002) from cognitive linguistics describes how one constructs meaning from various stimuli, such
as text and diagrams, through conceptual integration or blending. The conceptual integration networks that describe the conceptual
integration process characterize cognition that occurs unconsciously during meaning construction. These same networks are
used to describe some of the cognition while resolving an anomaly in molecular genetics called RNA interference (RNAi) in
a case study. The RNAi case study is a cognitive-historical reconstruction (Nersessian, In: Giere (ed) Cognitive models of
science, 1992) that reconstructs how the RNAi anomaly was resolved. This reconstruction traces four relevant molecular genetics
publications in describing the cognition necessary in accounting for how RNAi was resolved through strategies (Darden 1991),
abductive reasoning (Peirce, In: Hartshorne, Weiss (eds) Collected papers, 1958), and experimental reasoning (Gooding 1990).
The results of the case study show that experiments play a crucial role in formulating an explanation of the RNAi anomaly
and the integration networks describe the experiments’ role. Furthermore, these results suggest that RNAi anomaly resolution
is embodied. It is embodied in a sense that cognition described in the cognitive-historical reconstruction is experientially
based.
相似文献
John J. SungEmail: |
86.
Seung-Jae Lee In Hwan Lee Jeong Hun Park So-Jung Gwak Jong-Won Rhie Dong-Woo Cho Tae Jo Ko Dong Sung Kim 《科学通报(英文版)》2009,54(19):3608-3612
We developed a hybrid scaffold and a bioreactor for cartilage regeneration. The hybrid scaffold was developed as combination of two components: a biodegradable framework and hydrogel-containing chondrocytes. We performed the MTT cell proliferation assay to compare the proliferation and viability of chondrocytes on three types of scaffolds: an aiginate gel, the hybrid scaffold, and an alginate sponge. Cells were encapsulated in 2% agarose gel. The bioreactor consisted of a circulation system and a compression system. We performed dynamic cell culture on these agarose gels in the bioreactor for 3 days. 相似文献
87.
Sung WK Zheng H Li S Chen R Liu X Li Y Lee NP Lee WH Ariyaratne PN Tennakoon C Mulawadi FH Wong KF Liu AM Poon RT Fan ST Chan KL Gong Z Hu Y Lin Z Wang G Zhang Q Barber TD Chou WC Aggarwal A Hao K Zhou W Zhang C Hardwick J Buser C Xu J Kan Z Dai H Mao M Reinhard C Wang J Luk JM 《Nature genetics》2012,44(7):765-769
To survey hepatitis B virus (HBV) integration in liver cancer genomes, we conducted massively parallel sequencing of 81 HBV-positive and 7 HBV-negative hepatocellular carcinomas (HCCs) and adjacent normal tissues. We found that HBV integration is observed more frequently in the tumors (86.4%) than in adjacent liver tissues (30.7%). Copy-number variations (CNVs) were significantly increased at HBV breakpoint locations where chromosomal instability was likely induced. Approximately 40% of HBV breakpoints within the HBV genome were located within a 1,800-bp region where the viral enhancer, X gene and core gene are located. We also identified recurrent HBV integration events (in ≥ 4 HCCs) that were validated by RNA sequencing (RNA-seq) and Sanger sequencing at the known and putative cancer-related TERT, MLL4 and CCNE1 genes, which showed upregulated gene expression in tumor versus normal tissue. We also report evidence that suggests that the number of HBV integrations is associated with patient survival. 相似文献
88.
通过软件缺陷预测可以有效地提高软件测试效率,保证软件产品的质量。针对新开发的项目面临训练数据不足,标注代价高以及源项目与目标项目的缺陷模式难以匹配的问题,提出了基于主动学习的跨项目软件缺陷预测方法。首先使用主动学习方法对目标项目进行筛选标注,其次将得到的标签集与跨项目数据进行数据融合和模式匹配,最后构建跨项目软件缺陷预测模型。采用真实的软件缺陷数据进行实验,在保证预测率的前提下,曲线下面积(area under curve, AUC)能够达到0.692,与传统方法相比综合性能均有显著提升。结果表明:所提方法可以通过模式匹配有效提高跨项目软件缺陷预测模型的性能。 相似文献
89.
Won-Je Kim Woo Sung Son Kyoung-Seok Ryu Seung-Kyu Lee Kwang-Hyun Choi Jong-Sun Lee Bong-Jin Lee 《科学通报(英文版)》2014,59(32):4274-4282
Potent inhibitors of human peptide deformylase (HsPDF) were screened using known PMT analog inhibi- tors of bacterial peptide deformylase. Forty-three species of PMT analogs that are non-peptidyl bacterial PDF inhibitors like actinonin were selected using virtual screening GOLD. Ten species out of 43 that could bind to HsPDF were selected and their antitumor activities were tested. Among them, four species (PMT-172, PMT-173, PMT-199, and PMT-201) showed excellent growth inhibition of cancer cell in the MTT assay. HsPDF-PMT binding was confirmed through a 1H-CPMG-T2 filter NMR experiment leading to a significant change in peak intensity for PMT-172 and PMT-199. These results suggest that PMT analogs could possibly interact with HsPDF and be a novel anticancer drug candidate. 相似文献
90.
Differential use of an in-frame translation initiation codon regulates human mu opioid receptor (OPRM1) 总被引:1,自引:1,他引:0
Kyu Young Song Hack Sun Choi Cheol Kyu Hwang Chun Sung Kim Ping-Yee Law Li-Na Wei Horace H. Loh 《Cellular and molecular life sciences : CMLS》2009,66(17):2933-2942
The pharmacological effects of morphine and morphine-like drugs are mediated primarily through the μ opioid receptor. Here
we show that differential use of an in-frame translational start codon in the 5′-untranslated region of the OPRM1 generates
different translational products in vivo and in vitro. The 5′-end of the OPRM1 gene is necessary for initiating the alternate
form and for subsequent degradation of the protein. Initiation of OPRM1 at the upstream site decreases the initiation at the
main AUG site. However, alternative initiation of the long form of OPRM1 produces a protein with a short half-life, resulting
from degradation mediated by the ubiquitin–proteasome pathway. Reporter and degradation assays showed that mutations of this
long form at the second and third lysines reduce ubiquitin-dependent proteasome degradation, stabilizing the protein. The
data suggest that MOP expression is controlled in part by initiation of the long form of MOP at the alternate site. 相似文献