Synthesis of well-aligned carbon nanotubes with open tips

Liu, B.C.,Lee, T.J.,Jung, S.I.,Park, C.Y.,Choa, Y.H.,Lee, C.J. Elsevier 2005 Carbon Vol.43 No.7

<P><B>Abstract</B></P><P>Large amounts of well-aligned carbon nanotubes (CNTs) with open tips have been produced by pyrolysis of iron(II) phthalocyanine. The aligned CNTs have an average length about 10μm and diameters ranging from 92 to 229nm. Some of produced CNTs showed Y-junction structure due to the self-joint growth of two neighboring CNTs. The well-aligned CNTs indicated a bamboo-shaped multiwalled structure and fairly good crystallinity. The aligned CNTs follow tip growth mechanism.</P>

Hardness Prediction and First Principle Study of Re-123(Re = Y, Eu, Pr, Gd) Superconductors

Liu, Weiwei,Zhou, Y.P.,Feng, X.L. Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.12

The chemical bond parameters of Y-123, Eu-123, Pr-123 and Gd-123 compounds have calculated using the chemical bond theory of complex crystals. Their hardness have been predicted by the chemical bond definition of hardness. The calculated results indicate that the Ba-O and RE-O types of bond have a lower covalent character and the Cu-O types of bond have greater covalency. The hardness values increase as the unit cell volume of the rare earth superconductor structures decrease.

Hardness Prediction and First Principle Study of Re-123(Re = Y, Eu, Pr, Gd) Superconductors

Weiwei Liu,Y. P. Zhou,X. L. Feng 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.12

The chemical bond parameters of Y-123, Eu-123, Pr-123 and Gd-123 compounds have calculated using the chemical bond theory of complex crystals. Their hardness have been predicted by the chemical bond definition of hardness. The calculated results indicate that the Ba-O and RE-O types of bond have a lower covalent character and the Cu-O types of bond have greater covalency. The hardness values increase as the unit cell volume of the rare earth superconductor structures decrease.

3-Dimensional stress analysis of O-ring under uniform squeeze rate and internal pressure by photoelastic experimental hybrid method

남정환,황재석,Y. Liu,신동철 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.9

Until now, studies have shown that stresses on the plane (y-z plane) perpendicular to the circumferential direction (x-axis) of an O-ring do exist. Stresses on the planes (x-y plane and x-z plane) parallel to the circumferential direction of the O-ring have not been reported to exist. In this study however, it is demonstrated through a 3-dimensional stress analysis that stresses on the x-y plane and x-z plane of the O-ring under uniform squeeze rate and internal pressure do exist. Therefore, to study effectively 3-dimensional stress distributions of an O-ring under these loadings, stress distributions of every plane should be analyzed. This study develops a photoelastic experimental hybrid method to analyze 3-dimensional stress distributions of an O-ring under uniform squeeze rate and internal pressure, and uses it to determine the stress distributions in every plane, including the Von Mises equivalent stresses, at any arbitrary point of the O-ring under uniform squeeze rate and internal pressure.

Thermoelectric properties of Gd, Y co-doped Ca3Co4O9+δ

H.Q. Liu,X.B. Zhao,T.J. Zhu,Y. Song,F.P. Wang 한국물리학회 2009 Current Applied Physics Vol.9 No.3

The Ca3-x-yGdxYyCo4O9+δ precursor powders were synthesized by the polyacrylamide gel method. The powders were sintered by the spark plasma sintering (SPS). The DTA analysis showed that the synthesis temperature of Ca3Co4O9+δ was about 933 K, which is lower than that of the conventional citric acid method. The resistivities, the Seebeck coefficients and the thermal conductivities of the samples were measured from room temperature to 973 K. The Seebeck coefficients and the resistivities of the doped samples were remarkably enhanced due to the decrease of the carrier concentration, whereas the thermal conductivities of them were decreased due to the impurity scattering effect. The maximal ZT value of 0.26 was obtained at 973 K for Ca2.7 Gd0.15 Y0.15Co4O9+δ. The Ca3-x-yGdxYyCo4O9+δ precursor powders were synthesized by the polyacrylamide gel method. The powders were sintered by the spark plasma sintering (SPS). The DTA analysis showed that the synthesis temperature of Ca3Co4O9+δ was about 933 K, which is lower than that of the conventional citric acid method. The resistivities, the Seebeck coefficients and the thermal conductivities of the samples were measured from room temperature to 973 K. The Seebeck coefficients and the resistivities of the doped samples were remarkably enhanced due to the decrease of the carrier concentration, whereas the thermal conductivities of them were decreased due to the impurity scattering effect. The maximal ZT value of 0.26 was obtained at 973 K for Ca2.7 Gd0.15 Y0.15Co4O9+δ.

Increase of critical current density with doping carbon nano-tubes in YBa₂Cu₃O₇₋<i>_δ</i>

Dadras, S.,Liu, Y.,Chai, Y.S.,Daadmehr, V.,Kim, K.H. Elsevier 2009 Physica. C, Superconductivity Vol.469 No.1

<P><B>Abstract</B></P><P>The effects of carbon nano-tubes (CNTs) on the crystal structure and superconducting properties of YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7−</SUB><I><SUB>δ</SUB></I> (Y-123) compound were studied. Samples were synthesized using standard solid-state reaction technique by adding CNT up to 1wt% and X-ray diffraction data confirm the single phase orthorhombic structure for all the samples. Current–voltage measurements in magnetic fields up to 9T were used to study the pinning energy <I>U<SUB>J</SUB></I> and critical current density <I>J</I><SUB>c</SUB> as a function of magnetic field at fixed temperature. We find that while <I>T</I><SUB>c</SUB> does not change much with the CNT doping (91–92K), both <I>U<SUB>J</SUB></I> and <I>J</I><SUB>c</SUB> increase systematically up to 0.7wt% CNT doping in a broad magnetic field ranges between 0.1 and 9T and <I>J</I><SUB>c</SUB> in the 0.7wt% CNT doped sample is at least 10 times larger than that of the pure Y-123. The scanning electron microscope image shows that CNTs are forming an electrical-network between grains. These observations suggest that the CNT addition to the Y-123-compounds improve the electrical connection between superconducting grains to result in the <I>J</I><SUB>c</SUB> increase.</P>

New Species and New Records of Buellia (Lichenized Ascomycetes) from Jeju Province, South Korea

Wang, Xin Yu,Liu, Dong,Lokos, Laszlo,Kondratyuk, Sergey Y.,Oh, Soon-Ok,Park, Jung Shin,Hur, Jae-Seoun The Korean Society of Mycology 2016 Mycobiology Vol.44 No.1

A new species and 2 new records of lichen genus Buellia were discovered from Chuja-do Island in Jeju Province during a recent floristic survey: B. chujana X. Y. Wang, S. Y. Kondr., L. $L\ddot{o}k\ddot{o}s$ & J.-S. Hur sp. nov., B. halonia (Ach.) Tuck., and B. mamillana (Tuck.) W. A. Weber. The new species is characterized by a brown, areolate thallus, the presence of perlatolic acid, and a saxicolous habitat. Together with previously recorded species, 10 Buellia species were confirmed from Jeju-do Island. Among these species, 3 growing in the exposed rocky area contained xanthone (yellowish lichen thallus, UV + orange), indicating that production of xanthone in this genus might be a defense strategy against the harm of UV light. Although the genus Buellia has been thoroughly studied in Korea before, novel species have been discovered continuously, and large species diversity has been found in this crustose genus, even from a small rocky island. This study indicates that the coastal area harbors a vast number of crustose lichen species, and there is great potential to discover unknown lichens in the coastal rocky area in Korea.

Further Study on Infectivity of Zoophilic and Anthropophilic Strains of Schistosoma Japanicum to Different Races of Oncomelania hupensis Snails

Lee, K.M.,Fan, P.C.,Wu, C.C.,Liu, C.Y. INSTITUTE OF TROPICAL MEDICINE YONSEI UNIVERSITY 1994 YONSEI REPORTS ON TROPICAL MEDICINE Vol.25 No.1

In the present study, Oncomelnia snails were collected from Chen-shan District of I-lan County, Pu-yen District of Chang-hua County, Chang-hu District of Yun-lin County, Pali District and A-li-lao of Taipei County, and Liu-kuei District of Kao-hsiung County. The Oncomelania snails from A-li-lao were infected with Hupei/China strain of Schistosoma japonicum (anthropophilic type). The remaining five races of Oncomelania snails were infected with Han-pao/Taiwan strain of S. japonicum (zoophilic type). Each snail was infected with five miracidia and examined six times after infection. Except for the snails from Liu-Kuei, those from the other five areas were found positive. The infection rate of the snails infected with the zoophilic strain of S. japonicum was the highest in those from Pa-li (42.9%), followed by Chang-Hu (38.4%), Pu-Yen (17.1%). and Chen-Shan (10%). The Oncomelania snails from A-li-lao infected with the anthropophilic strain of S. japonicum gave an infection rate of 53%. The snails from A-il-lao and Pa-li were O. hupensis chiui and those from the other four areas were O. hypensis formosana. In contrast to the order of infection rate. the size of the Chang-hua strain of O. h. formosana was the largest (6.3×2.9mm ) and the A-li-lao strain of O. h. chiui was the smallest (4.2×2.3mm). The Pa-li strain of O. h. chiui snails was middle size (4.8×2.7mm). The infection rate and the size of snails were turned out to be negatively correlated.

中國詩學

劉若愚 단국대학교 중어중문학과 1974 中國文學報 Vol.- No.1

요약해서 말하면, 직관파의 비평가들은 시에 대하여 공통되는 기본 개념을 갖고 있다. 그들이 그것을 ‘신운’이라고 하든, ‘정경’이라고 하든, ‘경계’라고 하든 그들은 시의 정수는 감정의 내면세계의 묵시인 동시에 시인의 마음을 통해서 반영된 외부세계의 구체화에 있음에 동의 하였다. 그들은 모두 현학모방과 기교에 사로잡히는 것을 비난하고 직관과 영감의 중요성을 강조하였다. 어떤 면에 있어서 그들은 개성주의자들과도 일맥이 통하나, 그의 기본태도는 그들은 시인 자신의 개성을 표현하는데 만족하는 게 아니라, 세계에 대한 통제를 부각하는 것을 추구하는데 있다.

Inelastic Light Scattering Studies of Overdoped Y1-xCaxBa₂Cu₃O₇ Film

J. H. Lin,S. M. Weng,H. L. Liu,P. C. Chung,J.-Y. Lin 한국자기학회 2007 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-