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급냉응고 처리된 초내열 합금 A-286 의 기계적 성질 및 강화기구
이성학,신기삼,Kelly, Thomas F,Flinn, John E 대한금속재료학회(대한금속학회) 1996 대한금속·재료학회지 Vol.34 No.3
Mechanical test data of superalloy A-286 show that there is a significant increase in tensile strength after rapid solidification processing (RSP). The mechanism of mechanical property improvement upon RSP was studied by TEM quantitative defect analysis and the data analysis using strengthening models. The most prominent microstructural alterations by RSP are found in the precipitates and in the grain growth behavior. On average, the precipitates in RSP samples are smaller, have higher volume fractions, and are much more stable than their conventionally processed counterparts. The increased tensile strength of the RSP samples is found to be the result of the increased volume fraction and number density of second phase particles. However, the strengthening came mostly through grain growth inhibition by the second phase particles, which in turn increased the strength via Hall-Petch relationship. This study shows the importance of recrystallization and thus the method of consolidation for effective strengthening.
At Death's Door: Alternaria Pathogenicity Mechanisms
Lawrence, Christopher B.,Mitchell, Thomas K.,Craven, Kelly D.,Cho, Yang-Rae,Cramer, Robert A.,Kim, Kwang-Hyung The Korean Society of Plant Pathology 2008 Plant Pathology Journal Vol.24 No.2
The fungal genus Alternaria is comprised of many saprophytic and endophytic species, but is most well known as containing many notoriously destructive plant pathogens. There are over 4,000 Alternaria/host associations recorded in the USDA Fungal Host Index ranking the genus 10th among nearly 2,000 fungal genera based on the total number of host records. While few Alternaria species appear to have a sexual stage to their life cycles, the majority lack sexuality altogether. Many pathogenic species of Alternaria are prolific toxin producers, which facilitates their necrotrophic lifestyle. Necrotrophs must kill host cells prior to colonization, and thus these toxins are secreted to facilitate host cell death often by triggering genetically programmed apoptotic pathways or by directly causing cell damage resulting in necrosis. While many species of Alternaria produce toxins with rather broad host ranges, a closely-related group of agronomically important Alternaria species produce selective toxins with a very narrow range often to the cultivar level. Genes that code for and direct the biosynthesis of these host-specific toxins for the Alternaria alternata sensu lato lineages are often contained on small, mostly conditionally dispensable, chromosomes. Besides the role of toxins in Alternaria pathogenesis, relatively few genes and/or gene products have been identified that contribute to or are required for pathogenicity. Recently, the completion of the A. brassicicola genome sequencing project has facilitated the examination of a substantial subset of genes for their role in pathogenicity. In this review, we will highlight the role of toxins in Alternaria pathogenesis and the use of A. brassicicola as a model representative for basic virulence studies for the genus as a whole. The current status of these research efforts will be discussed.
At Death’s Door: Alternaria Pathogenicity Mechanisms
Christopher B. Lawrence,Thomas K. Mitchell,Kelly D. Craven,Yangrae Cho,Robert A. Cramer Jr,김광형 한국식물병리학회 2008 Plant Pathology Journal Vol.24 No.2
The fungal genus Alternaria is comprised of many saprophytic and endophytic species, but is most well known as containing many notoriously destructive plant pathogens. There are over 4,000 Alternaria/host associations recorded in the USDA Fungal Host Index ranking the genus 10th among nearly 2,000 fungal genera based on the total number of host records. While few Alternaria species appear to have a sexual stage to their life cycles, the majority lack sexuality altogether. Many pathogenic species of Alternaria are prolific toxin producers, which facilitates their necrotrophic lifestyle. Necrotrophs must kill host cells prior to colonization, and thus these toxins are secreted to facilitate host cell death often by triggering genetically programmed apoptotic pathways or by directly causing cell damage resulting in necrosis. While many species of Alternaria produce toxins with rather broad host ranges, a closelyrelated group of agronomically important Alternaria species produce selective toxins with a very narrow range often to the cultivar level. Genes that code for and direct the biosynthesis of these host-specific toxins for the Alternaria alternata sensu lato lineages are often contained on small, mostly conditionally dispensable, chromosomes. Besides the role of toxins in Alternaria pathogenesis, relatively few genes and/or gene products have been identified that contribute to or are required for pathogenicity. Recently, the completion of the A. brassicicola genome sequencing project has facilitated the examination of a substantial subset of genes for their role in pathogenicity. In this review, we will highlight the role of toxins in Alternaria pathogenesis and the use of A. brassicicola as a model representative for basic virulence studies for the genus as a whole. The current status of these research efforts will be discussed.
Conducting polymer composites with cellulose and protein fibres
James H. Johnston,John Moraes,Thomas Borrmann,David Flynn,Fern M. Kelly 한국물리학회 2006 Current Applied Physics Vol.6 No.3
Conducting polymer–fibre composites with polypyrrole cellulose (paper) and protein (wool) fibres have been produced by polymerizing pyrrole with ferric chloride as the oxidant around separated individual cellulose (wood) fibres from bleached Pinus radiata Kraft pulp, and merino wool fibres respectively to generate new composite materials that retain the inherent properties of the polymer and individual fibres. For the polypyrrole–cellulose composite, the polypyrrole consisted of spheres of about 100 nm in size fused together to form a continuous coating that fully encapsulates the cellulose fibre and associated finer fibrils. For the polypyrrole–wool composite the polypyrrole formed a similar coating of about 200 nm spheres. Electrical conductivities of the composites were substantially increased over those of the precursor fibres.
Ben Tordoff,Cheryl Hartfield,Andrew J. Holwell,Stephan Hiller,Marcus Kaestner,Stephen Kelly,Jaehan Lee,Sascha Müller,Fabian Perez-Willard,Tobias Volkenandt,Robin White,Thomas Rodgers 한국현미경학회 2020 Applied microscopy Vol.50 No.1
The development of the femtosecond laser (fs laser) with its ability to provide extremely rapid athermal ablation of materials has initiated a renaissance in materials science. Sample milling rates for the fs laser are orders of magnitude greater than that of traditional focused ion beam (FIB) sources currently used. In combination with minimal surface post-processing requirements, this technology is proving to be a game changer for materials research. The development of a femtosecond laser attached to a focused ion beam scanning electron microscope (LaserFIB) enables numerous new capabilities, including access to deeply buried structures as well as the production of extremely large trenches, cross sections, pillars and TEM H-bars, all while preserving microstructure and avoiding or reducing FIB polishing. Several high impact applications are now possible due to this technology in the fields of crystallography, electronics, mechanical engineering, battery research and materials sample preparation. This review article summarizes the current opportunities for this new technology focusing on the materials science megatrends of engineering materials, energy materials and electronics.
Choi, Eun Yong,Jeong, Jeongyun,Kang, Dong Il,Johnson, Kelly,Ercolani, Matt,Jang, Thomas,Lee, Dong Hyeon,Kim, Wun‐,Jae,Kim, Isaac Yi Blackwell Publishing Asia 2011 International journal of urology Vol.18 No.4
<P><B>Objective: </B> Lower urinary tract symptoms (LUTS) are a common complaint in patients with prostate cancer. We attempted to elucidate the effect of robot‐assisted radical prostatectomy (RARP) on patients having different preoperative LUTS severity through analysis of postoperative health‐related quality of life.</P><P><B>Methods: </B> From 1/2006 to 9/2009, over 500 patients underwent RARP at our institution. Preoperative American Urologic Association Symptom Score (AUA‐SS), preoperative Sexual Health Inventory for Men, and postoperative Expanded Prostate Cancer Index Composite were available in 183 of them. These patients were divided into three subgroups based on their AUA‐SS as follows: mild AUA‐SS (score 0–7) group, moderate AUA‐SS (8–19) group, and severe AUA‐SS (20–35) group.</P><P><B>Results: </B> Of the 183 men, 94 (51.4%), 70 (38.2%), and 19 (10.4%) were in the mild, moderate, and severe group, respectively. In the comparison of Expanded Prostate Cancer Index Composite domain subscales with mean score, only urinary domain had significant differences among subgroups. Patients with high preoperative LUTS persistently showed a statistical trend for decreased urinary function (<I>P</I> = 0.056) and suffered more from urinary bother postoperatively (<I>P</I> < 0.01). In the analysis of urinary bother items, all items except “bleeding with urination” showed statistically significant differences among the subgroups (<I>P</I> < 0.05).</P><P><B>Conclusions: </B> Even after RARP, patients with severe preoperative LUTS continue to have significant symptoms postoperatively. In analyzing urinary bother items, all LUTS items, including dysuria, storage symptoms, and postmicturition or voiding symptoms, were higher in patients with high preoperative AUA‐SS.</P>
Validation of Numerical Methods to Calculate Bypass Flow in a Prismatic Gas-Cooled Reactor Core
탁남일,김민환,임홍식,노재만,Timothy J. Drzewiecki,Volkan Seker,Thomas J. Downar,JOSEPH KELLY 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.6
For thermo-fluid and safety analyses of a High Temperature Gas-cooled Reactor (HTGR), intensive efforts are in progress in the developments of the GAMMA+ code of Korea Atomic Energy Research Institute (KAERI) and the AGREE code of the University of Michigan (U of M). One of the important requirements for GAMMA+ and AGREE is an accurate modeling capability of a bypass flow in a prismatic core. Recently, a series of air experiments were performed at Seoul National University (SNU) in order to understand bypass flow behavior and generate an experimental database for the validation of computer codes. The main objective of the present work is to validate the GAMMA+ and AGREE codes using the experimental data published by SNU. The numerical results of the two codes were compared with the measured data. A good agreement was found between the calculations and the measurement. It was concluded that GAMMA+ and AGREE can reliably simulate the bypass flow behavior in a prismatic core.