Hardening of Bi-Te based alloys by dispersing B₄C nanoparticles

Jung, S.J.,Park, S.Y.,Kim, B.K.,Kwon, B.,Kim, S.K.,Park, H.H.,Kim, D.I.,Kim, J.Y.,Hyun, D.B.,Kim, J.S.,Baek, S.H. Elsevier Science 2015 Acta materialia Vol.97 No.-

Thermoelectric devices have attracted a great attention for renewable energy harvesters and solid-state coolers. For practical applications, the mechanical properties of thermoelectric materials become critical for the device reliability, a persistent performance with a long time and high operation cycles. Bi-Te based single-crystals, mostly used in commercial thermoelectric devices, are intrinsically brittle with weak van der Waals bonding, often leading to device failures such as crack and debonding during fabrication and operation. Thus, it is highly desirable to enhance the mechanical property of Bi-Te based alloys as well as the thermoelectric property. Here, we investigate the effect of B<SUB>4</SUB>C nanoparticles (less than 0.5wt%) dispersed in p-type Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> matrix on the mechanical properties. X-ray diffraction (XRD) result confirms that B<SUB>4</SUB>C-dispersed Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> has a single phase. We observe that the grain size of Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> becomes decreased with the B<SUB>4</SUB>C nanoparticle concentration by electron backscatter diffraction (EBSD) technique. Hardness, Young's modulus, and flexural strength of B<SUB>4</SUB>C-dispersed Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> are enhanced, compared to the B<SUB>4</SUB>C-free Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> polycrystals. On the other hand, the thermoelectric figure-of-merit of B<SUB>4</SUB>C-dispersed Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> is almost identical to that of the pure Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB>. Such enhancements of the mechanical properties of the B<SUB>4</SUB>C-dispersed Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> are attributed to the grain boundary hardening and second-phase hardening. Beyond thermoelectric materials, our result implies that the grain refinement by nanoparticle dispersion is a simple and promising way to strengthen the mechanical properties of other brittle materials with layered structure.

기계학습을 이용한 H-형강 물성 예측 기초 연구

남재혁(J. H. Nam),홍정범(J. B. Hong),이창선(C. S. Lee),현승균(S. K. Hyun) 한국생산제조학회 2023 한국생산제조시스템학회 학술발표대회 논문집 Vol.2023 No.12

Zn^II coordination polymers constructed with malonate and bipyridyl ligands: Photoluminescence and heterogeneous catalytic reactivity

Hyun, M.Y.,Hwang, I.H.,Lee, M.M.,Kim, H.,Kim, K.B.,Kim, C.,Kim, H.Y.,Kim, Y.,Kim, S.J. Pergamon Press 2013 Polyhedron Vol.53 No.-

Four three-dimensional Zn<SUP>II</SUP> frameworks containing malonates and various bipyridyl pillars (4,4'-bipyridine (1), 1,2-bis(4-pyridyl)ethane (2), 1,2-bis(4-pyridyl)ethylene (3) and 1,3-bis(4-pyridyl)propane (4)) have been prepared, and their structures were determined by X-ray crystallography. In all four frameworks, malonate ligands bridge three Zn ions to form two-dimensional layers, and these layers are connected by bipyridyl pillars to form three-dimensional frameworks with the general formula [{Zn(H<SUB>2</SUB>O)(μ-malonate)}<SUB>2</SUB>(μ-bipyridyl)] and which also contain water or acetonitrile solvates. Reactivity studies of compounds 1-4 showed that they catalyzed a heterogeneous transesterification reaction of phenyl acetate and could be reused without any significant loss of activity through five runs. Emissions were observed at 347-365nm (λ<SUB>ex</SUB>=313nm) for 2 and 363nm (λ<SUB>ex</SUB>=328nm) for 3, while compounds 1 and 4 showed no luminescence properties. The thermal stabilities of these complexes were also examined.

Molecular evidence of a teleomorph-anamorph connection between Cordyceps scarabaeicola and Beauveria sungii and its implication for the systematics of Cordyceps sensu stricto

Shrestha, B.,Hyun, M.W.,Oh, J.,Han, J.G.,Lee, T.H.,Cho, J.Y.,Kang, H.,Kim, S.H.,Sung, G.H. Mycological Society of Japan 2014 Mycoscience Vol.55 No.3

A teleomorph of Beauveria sungii S.A. Rehner & Humber is identified as Cordyceps scarabaeicola Y. Kobayasi based on the teleomorphic material of the B. sungii isolate used in the recent phylogenetic study. Cordyceps Fr. 1818 is an older generic name than Beauveria Vuill. 1912 in Cordyceps sensu stricto. Here, C. scarabaeicola is suggested to be adopted for B. sungii on the priority basis of both generic name and species epithet in compliance with the recent revision of Article 59 of the Melbourne Code (recently changed to the 'International Code of Nomenclature for algae, fungi, and plant' or ICN). The pros and cons of a unified nomenclature for pleomorphic fungi are briefly discussed with reference to Beauveria.

Characterization and in Vitro Inhibition Studies of Bacillus anthracis FtsZ: A Potential Antibacterial Target

Park, H. C.,Gedi, V.,Cho, J. H.,Hyun, J. W.,Lee, K. J.,Kang, J.,So, B.,Yoon, M. Y. HUMANA PRESS INC 2014 Applied biochemistry and biotechnology Vol.172 No.6

FtsZ is an essential bacterial cell division protein that is an attractive target for the development of antibacterial agents. FtsZ is a homologue of eukaryotic tubulin, has GTPase activity, and forms a ring-type structure to initiate cell division. In this study, the FtsZ of Bacillus anthracis was cloned into a bacterial expression vector and overexpressed into Escherichia coli BL21 (DE3) cells. The overexpressed B. anthracis FtsZ was soluble and purified to homogeneity using Ni-His-tag affinity chromatography. Like other known FtsZs, the recombinant B. anthracis FtsZ also showed GTP-dependent polymerization, which was analyzed using both spectrophotometric and Transmission Electronic Microscopic (TEM) analysis. Using the purified FtsZ, we screened a naturally extracted chemical library to identify potent and novel inhibitors. The screening yielded three chemicals, SA-011, SA-059, and SA-069, that inhibited the in vitro polymerization activity of FtsZ in the micromolar range (IC50 of 55-168 mu M). The inhibition potency was significantly comparable with that of berberine, a known potential inhibitor of FtsZ. Understanding the biochemical basis of the effect of these inhibitors on B. anthracis growth would provide a promising path for the development of new antianthracis drugs.

Design of the RAON Accelerator Systems

전동오,I. S. Hong,H. J. Kim,J. W. Kim,R. M. Bodenstein,차혁진,S. J. Choi,최숙,O. R. Choi,H. Do,B. H. Choi,C. J. Choi,J. Han,W. K. Han,M. O. Hyun,H. Jang,J. D. Joo,M. J. Joung,H. C. Jung,Y. C. Jung,김도균,E. Kim 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.7

The RAON is the name of the heavy ion accelerator facility under construction in Korea thatincludes the In-flight Fragment (IF) and Isotope Separation On-Line (ISOL) facilities to supportcutting-edge research in various science fields. The superconducting linac is the driver for the IFfacility that can accelerate beams from proton to uranium with 200 MeV/u, 400 kW (for uraniumbeam). A 70-MeV, 1-mA H− cyclotron is the driver for the ISOL facility and is followed by apost-accelerator consisting of s superconducting linac that can accelerate rare-isotope (RI) beamsand deliver them to experimental halls. These facilities provide high-intensity stable ion and rareisotope (RI) beams for domestic and international users. In this paper, design and prototypingefforts for the RAON accelerator systems are presented.

제주재래흑돼지 자돈의 성장에 관한 연구

강민수,고봉석,조성환,현종훈,김현호,현승구,고기정,박미혜 濟州大學校 農科大學 動物科學硏究所 1999 動物科學論叢 Vol.14 No.1

This study was conducted to the suckling behavior on the growth of Cheju native black piglet during the suckling period. The data for this study were obtained from 24 heads of Cheju native black piglet(fema1e 15 and male 9). The traits studied were composition of milk, body weight and comformation of piglets. The results obtained in this study are summaried as follows; 1. The composition of clostrum were 80.11 % water, 19.89 % solids, 7.46 fat, 8.95 % protein, 3.29 % lactose, 0.29% minerals, pH value was 6.42. The composition of normal milk were 83.81 % water, 16.19 solids, 5.79 % fat, 5.34 % protein, 4.28 % lactose, 0.77 % minerals, pH value was 5.49. 2. The body weight in female and male piglets, respectively was 1.01 and 1.17 kg at birth, 4.64 and 5.36 kg at 3 wk, 9.49 and 11.04 kg at 6 wk of age. There difference between male and female was significant(p<O.&). 3. The withers height in female and male was 15.47 and 16.43 cm at birth, 23.91 and 24.86cm for 3 wk, 30.47 and 32.14 cm for 6 wk old piglets, respectively. There difference between male and female was significant(p<0.05). The back height in female and male was 16.19 and 16.93 cm at birth, 25.34 and 26.36 an 16.50 after 3 wk, 32.06 and 33.71 cm after 6 wk, respectively. There dfference between male and female was significant(p<O.B). The croup height of female and male was 15.78 and 16.50cm at birth, 32.16 and 3 . 1 4 cm after 6 wk, respectively. There dfference between male and female ivas significant(p<O.05). 4. The body length in female and male piglets was 18.69 and 19.79 cm at birth, 32.22 and 33.86 cm after 3 wk, 42.59 and 43.07 cm after 6 wk, respectively. There dfference betiveen male and female ignificant(p<0.05). The chest girth in female and male piglets was 22.28 and 23.43 cm at birth, 38.31 and 39.6.1 cm after 3 wk. 37.81 and 50.00 cm after 6 wk, respectively. There dfference between male and female was significant(p<0.05). 5. The chest width in female and male was 513 and 5.36 cm at birth, 8.93 and 10.07 cm after 3 wk, 12.09 and 13.00 cm after 6 wk, respectively. There dfference between male and female was not significant(p<0.05). The pine width in female and male was 2.03 and 2.71 cm at birth, 3.97 and 4.93 cm after 3 wk, 5.88 and 6.57 cm after 6 wk, respectively. There dfference between male and female was significant(p<0.05). 6. The shin circumference in female and male was 5.03 and 5.64 cm at birth, 7.34 and 7.79 cm after 3 wk, 8.86 and 9.36 cm after 6 wk, respectively. There difference between male and female was significant(p<0.05). The head length in female and male was 6.84 and 7.43 cm at birth, 9.87 and 10.21 cm after 3 wk, 12.41 and 13.00 cm after 6 wk, respectively. There dfference between male and female was not significant(p<0.05). The head width in female and male was 4.16 and 4.57 cm at birth, 5.97 and 6.14 cm after 3 wk, 7.09 and 7.71 cm after 6 wk, respectively. There dfference between male and female was not significant(p<0.05). 7. The ear length in female and male was 5.56 and 5.86 cm at birth, 8.47 and 9.14 after 3 wk, 10.78 and 11.50 cm after 6 wk, respectively. There dfference between male and female was significant(p<0.05). The ear width in female and male was 4.19 and 4.64 cm at birth, 6.03 and 6.43 cm after 3 wk, 8.09 and 8.64 cm after 6 wk, respectively. There dfference between male and female was significant(p<0.05). The tail length in female and male was 7.25 and 7.29cm at birth, 10.38 and 10.50 cm after 3 wk, 13.88 and 14.43 cm after 6 wk, respectively. There dfference between male and female was not significant(p<0.05).

Cardiovascular effects of a novel selective Rho kinase inhibitor, 2-(1H-indazole-5-yl)amino-4-methoxy-6-piperazino triazine (DW1865)

Oh, K.S.,Oh, B.K.,Ho Park, C.,Won Seo, H.,Sook Kang, N.,Hyun Lee, J.,Soo Lee, J.,Ho Lee, B. North-Holland ; Elsevier Science Ltd 2013 european journal of pharmacology Vol.702 No.1

The arising critical implications of Rho kinase signaling in cardiovascular diseases have been attracting attention in the pharmacological potential of Rho kinase inhibitors. We identified a novel inhibitor of Rho kinase (2-(1H-indazole-5-yl)amino-4-methoxy-6-piperazino triazine; DW 1865) and characterized its effects in biochemical, cellular, tissue and animal based assays. DW 1865 potently inhibited the kinase activity of both Rho kinase 1 and Rho kinase 2 in vitro, and behaved as an ATP-competitive inhibitor. Interestingly, DW1865 was 10 times more potent in inhibiting Rho kinase activities than fasudil as a selective Rho kinase inhibitor. The activity of DW1865 was shown to be highly selective for Rho kinase in the panel assay of 13 other kinases. In the isolated vascular tissue study, DW1865 exerted vasorelaxation in phenylephrine- or 5-hydroxytriptamine-induced contraction in a concentration-dependent manner manner. In spontaneously hypertensive rats, administration of DW1865 caused a significant and dose-related reduction in blood pressure. Furthermore, DW1865 blocked angiotensin II-induced stress fiber formation and cellular hypertrophy in rat heart-derived H9c2 cells. Taken together, these results suggest that DW1865 is a highly selective and potent Rho kinase inhibitor that will alleviate the pathophysiological actions of Rho kinase such as stress fiber formation, cellular hypertrophy, and hypertension.

제주재래흑돼지 자돈의 수유행동에 관한 연구

강민수,고봉석,조성환,현종훈,김현호,현승구,고기정,박미혜 濟州大學校 農科大學 動物科學硏究所 1999 動物科學論叢 Vol.14 No.1

This study was conducted to the suckling behavior on the growth of Cheju native black piglet during the suckling period. The data for this study were obtained from 24 heads of Cheju native black piglet(female 15 and male 9). The traits studied were composition of milk and suckling behaviour of piglets. The results obtained in this study are summaried as follows; 1. The suckling duration of piglets were 126.4 min. after 1 wk, 93.2 min. after 3 wk, 72.4 min. after 6 wk, respectively. There were significant difference between weeks(p<0.05). The suckling interval of piglets were 32.7 min. after 1 wk, 44.6 min. after 3 wk, 47.3 min. after 6 wk, respectively. There were significant difference between weeks(p<O.O5). The suckling frequency of piglets were 19.6 times after 1 wk, 14.5 times after 3 wk, 13.9 times after 6 wk, respectively. There were significant difference between weeks(p<O.O5). 2. The resting duration of piglets were 963 min. after 1 wk, 1023 min. after 3 wk, 966 min. after 6 wk, respectively. There were not significant difference between weeks(p<0.05). The playing duration of piglets were wk, 191 min. after 3 wk, 215 min. after 6 wk, respectively. There were not were 20 min. after 3 wk, 48 min. after 5wk, 62 min. after 6 wk, respectively There were significant difference between weeks(p<0.05). 3. The urination frequent). of piglets were 13.9 times after 1 ivk, 8.0 times after 3 wk, 1.7 times after 6 wk, respectively. There were significant dfference between weeks(p(O.01). The defecation frequency of piglets were 0.9 times after 1 wk, 1.8 times after 3 wk, 3.4 times after 6 wk, respectively. There tvere significant dfference between weeks(p<0.0l). The drinking water frequency of piglets were 3.3 times after 1wk, 48 times after 3 wk, 10.7 times after 6 wk. respectively. There were significant dfference between weeks(p<0.0l). 4. Protein content of native sows milk was considerablely higher than that of the introduced sows milk but the fat and sugar content in the milk were lower than those of introduced sows milk. The results of suckling behaviour and litter performance study of Cheju native piglets may contribute to the effective breeding and feedmg management of Cheju native black swine production.

Characteristic of (La_0.8Sr_0.2)_0.98MnO₃ coating on Crofer22APU used as metallic interconnects for solid oxide fuel cell

Pyo, S.S.,Lee, S.B.,Lim, T.H.,Song, R.H.,Shin, D.R.,Hyun, S.H.,Yoo, Y.S. Pergamon Press ; Elsevier Science Ltd 2011 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.36 No.2

This study reports the high temperature oxidation kinetics, area specific resistance (ASR), and interfacial microstructure of metallic interconnects coated by (La<SUB>0.8</SUB>Sr<SUB>0.2</SUB>)<SUB>0.98</SUB>MnO<SUB>3</SUB> (LSM) in air atmosphere at 800<SUP>o</SUP>C. An efficient LSM conductive layer was fabricated on metallic interconnects for solid oxide fuel cells (SOFCs) by using a wet spray coating method. The optimum conditions for slurries used in the wet spray coating were determined by the measurement of slurry viscosity and coated surface morphology. The surface roughnesses of the substrates were increased through sandblast treatment. The adhesive strength of the interface between the coated layer and the metal substrate increased with increased surface roughness of the metallic interconnects. The electrical conductivities of the coated substrates were measured by using a DC two-point and four-wire method under air atmosphere at 800<SUP>o</SUP>C. Of note, the Crofer22APU treated at 1100<SUP>o</SUP>C in N<SUB>2</SUB> with 10vol.% H<SUB>2</SUB> showed long-term stability and a lower ASR value than other samples(heat-treated at 800<SUP>o</SUP>C and 900<SUP>o</SUP>C). After an 8000-h oxidation experiment the coated Crofer22APU substrate, the ASR showed a low value of 23m@?cm<SUP>2</SUP>. The thickness of the coated conductive oxide layer was about 10-20μm. These results show that a coated oxide layer prevents the formation and the growth of scale (Cr<SUB>2</SUB>O<SUB>3</SUB> and (Mn, Cr, Fe)<SUB>3</SUB>O<SUB>4</SUB> layer) and enhances the long-term stability and electrical performance of metallic interconnects for SOFCs.