• Bulletin of the Korean Chemical Society
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• 제22권9호
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• pp.1023-1029
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• 2001

The positions of Kr atoms encapsulated in the molecular-dimensioned cavities of fully dehydrated zeolite A of unit-cell composition Cs3Na8HSi12Al12O48 (Cs3-A) have been determined. Cs3-A was exposed to 1025 atm of krypton gas at 400 $^{\circ}C$ for four days, followed by cooling at pressure to encapsulate Kr atoms. The resulting crystal structure of Cs3-A(6Kr) (a = $12.247(2)\AA$, R1 = 0.078, and R2 = 0.085) has been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m at $21(1)^{\circ}C$ and 1 atm. In the crystal structure of Cs3-A(6Kr), six Kr atoms per unit cell are distributed over three crystallographically distinct positions: each unit cell contains one Kr atom at Kr(1) on a threefold axis in the sodalite unit, three at Kr(2) opposite four-rings in the large cavity, and two at Kr(3) on threefold axes in the large cavity. Relatively strong interactions of Kr atoms at Kr(1) and Kr(3) with Na+ ions of six-rings are observed: Na-Kr(1) = 3.6(1) $\AA$ and Na-Kr(3) = $3.08(5)\AA.$ In each sodalite unit, one Kr atom at Kr(1) was displaced $0.74\AA$ from the center of the sodalite unit toward a Na+ ion, where it can be polarized by the electrostatic field of the zeolite, avoiding the center of the sodalite unit which by symmetry has no electrostatic field. In each large cavity, five Kr atoms were found, forming a trigonal-bipyramid arrangement with three Kr(2) atoms at equatorial positions and two Kr(3) atoms at axial positions. With various reasonable distances and angles, the existence of Kr5 cluster was proposed (Kr(2)-Kr(3) = $4.78(6)\AA$ and Kr(2)-Kr(2) = $5.94(7)\AA$, Kr(2)-Kr(3)-Kr(2) = 76.9(3), Kr(3)-Kr(2)-Kr(3) = 88(1), and Kr(2)-Kr(2)-Kr(2) = $60^{\circ}).$ These arrangements of the encapsulated Kr atoms in the large cavity are stabilized by alternating dipoles induced on Kr(2) by four-ring oxygens and Kr(3) by six-ring Na+ ions, respectively.

• 한국자원식물학회지
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• 제17권3호
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• pp.227-238
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• 2004

본 연구는 자생식물 유전자원의 체계적 보존 및 관리를 위한 유전자원 수집과 보존 전략에 유용한 정보를 제공할 목적으로 강원 및 경북 지역에 자생하고 있는 꼬리 진달래 의 수집 계통들에 대하여 분자마커를 이용한 유전적 다형성 및 유연관계 분석을 수행하였다. RAPD분석에 이용된 10개의 primer에서 총 48개의 band가 관찰되었으며 이중에서 15개(31.3%)가 다형화 band였고, 1개의 primer당 평균 1.5개의 다형화 band가 관찰되었다. 반면에 AFLP 분석에서는 4개의 primer조합으로부터 총 62개의 band가 관찰되었으며 이중에서 33개(53.2%)가 다형화 band였고, 1개의 Primer조합당 평균 8.3개의 다형화 band가 관찰되었다. RAPD 및 AFLP band들을 이용한 UPGMA방법에 따라 작성된 dendrogram작성에서는 유전적 유사성 73.3%수준에서 크게 3개의 그룹으로 분리되었는데, 첫 번째 그룹에는 강원도 및 경북지역에서 수집된 대부분의 계통들이, 두 번째 그룹에는 lIII번 지역에서 수집된 7계통 모두가 포함되어 있었고 그리고 세 번째 그룹에는 경북 봉화에서 수집된 IV지역의 계통들 중 2계통(35, 36)이 각각 포함되었다. 따라서III번 지역과 IV번 지역의 일부 계통들을 제외하면 DNA 수준에서 꼬리 진달래 대부분의 계통들은 수집 지역에 따른 유전적 유연 관계를 명확히 나타내지 못하였다. RAPD및 AFLP분석 결과를 기초로 한 수집된 집단들 사이에서의 다형성 빈도는 II지역과 IV지역의 계통들에서 각각 45%로 가장 높게 관찰되었고, 반면에 Ⅵ지역의 계통들이 33%로 가장 낮게 관찰되었다. 그리고 집단들 사이에서의 유전적 유사성은 Ⅵ지역의 계통들이 평균 0.87로 가장 높게 나타났고, 반면에 I지역의 계통들은 평균 0.78을 나타내어 가장 낮게 나타났다. 본 연구의 결과에 의하면, 비록 III번 지역과 IV번 지역에서 수집된 일부 계통들은 다른 지역에서 수집된 대부분의 계통들과는 유전적으로 명확하게 구별되었지만, 수집 지역의 집단들 사이에서의 유전적 다양성은 현저한 차이를 나타내지 못하였으므로, 꼬리진달래의 현지외 보존을 통한 유전자원 보존원 조성을 효율적으로 수행하기 위해서는 유전자원 수집은 III번 지역과 IV번 지역을 중심으로 각 지역별로 균등하고 가급적 광범위하게 수집하는 것이 가장 효과적일 것으로 판단되었다.

• 에너지공학
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• 제19권2호
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• pp.121-127
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• 2010

본 연구에서는 4,4'-bis[(4-chlorophenyl)sulfonyl]-1,1'-biphenyl(BCPSBP), 술폰화된 하이드로퀴논, 4,4'-sulfonyldiphenol를 이용하여 새로운 폴리(아릴렌 비페닐설폰 에테르) 공중합체를 합성하였고 이들의 특성을 평가하였다. 첨가한 술폰화된 하이드로퀴논의 몰분율에 따라 PBPSEH-HQ00, PBPSEH-HQ10, PBPSEH-HQ30의 고분자전해질막을 합성하였다. 제조한 공중합체의 구조분석은 NMR, IR, GPC를 사용하여 실시하였고, GPC에서 평균분자량은 62,000-213,000 g $mol^{-1}$이며, 이때 PDI는 1.66-4.04였다. TGA와 DSC를 통하여 열분석을 실시하였고, 고분자의 이온화정도가 많아짐에 따라 $T_{d5%}$와 $T_{d10%}$는 낮아 졌으며, $T_g$값은 점점 상승하였다. 함습율과 IEC, 이온전도도는 술폰화된 하이드로퀴논 몰분율이 증가함에 따라 증가하였다. 고분자전해질막에서 중요한 양이온 전도도는 $60^{\circ}C$ 및 100%상대습도에서 약 9.4 mS $cm^{-1}$이었다. 측정된 결과로부터 본 연구에서 제조한 탄화수소계 멤브레인은 연료전지용 고분자전해질막으로 사용될 수 있다.

• Journal of Microbiology and Biotechnology
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• 제22권4호
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• pp.501-509
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• 2012

A 990 bp full-length gene (xynAHJ2) encoding a 329-residue polypeptide (XynAHJ2) with a calculated mass of 38.4 kDa was cloned from Bacillus sp. HJ2 harbored in a saline soil. XynAHJ2 showed no signal peptide, distinct amino acid stretches of glycoside hydrolase (GH) family 10 intracellular endoxylanases, and the highest amino acid sequence identity of 65.3% with the identified GH 10 intracellular mesophilic endoxylanase iM-KRICT PX1-Ps from Paenibacillus sp. HPL-001 (ACJ06666). The recombinant enzyme (rXynAHJ2) was expressed in Escherichia coli and displayed the typical characteristics of low-temperature-active enzyme (exhibiting optimum activity at $35^{\circ}C$, 62% at $20^{\circ}C$, and 38% at $10^{\circ}C$; thermolability at ${\geq}45^{\circ}C$). Compared with the reported GH 10 low-temperature-active endoxylanases, which are all extracellular, rXynAHJ2 showed low amino acid sequence identities (<45%), low homology (different phylogenetic cluster), and difference of structure (decreased amount of total accessible surface area and exposed nonpolar accessible surface area). Compared with the reported GH 10 intracellular endoxylanases, which are all mesophilic and thermophilic, rXynAHJ2 has decreased numbers of arginine residues and salt bridges, and showed resistance to $Ni^{2+}$, $Ca^{2+}$, or EDTA at 10 mM final concentration. The above mechanism of structural adaptation for low-temperature activity of intracellular endoxylanase rXynAHJ2 is different from that of GH 10 extracellular low-temperature-active endoxylanases. This is the first report of the molecular and biochemical characterizations of a novel intracellular low-temperature-active xylanase.

• 생명과학회지
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• 제25권6호
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• pp.646-655
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• 2015

벽방산의 산림식생에 대한 식물사회학적 연구를 수행하였다. 연구결과 벽방산은 3개 상관형의 9개 단위식생이 분포하고 있는 것으로 확인되었다. 연구지역 단위식생은 상록침엽수림의 해송-사스레피나무군락, 소나무-자금우군락, 하록활엽수림의 졸참나무-홀아비꽃대군락, 신갈나무-우산나물군락, 상수리나무군락, 소사나무군락, 굴참나무-쇠물푸레나무군락, 비목-물참대군락, 인공조림식생의 사방오리나무식재림 등으로 구분되었다. 벽방산은 지역 최고봉임에도 불구하고 산지 전역이 숲 가꾸기사업, 등산객, 조림 및 육림 등에 의해 직/간접적으로 인위적 간섭을 받고 있는 것으로 확인되었다. 연구지역 내 식생형 가운데 상대적으로 자연성이 높은 단위식생은 산지대 사면 중부에서 출현하는 졸참나무-홀아비꽃대군락, 전석지에서 확인된 비목-물참대군락 등이며, 산지능선부의 암석노출지를 중심으로 위극상의 천이계열에 해당하는 특산식물군락인 소사나무군락이 분포하고 있었다. CCA분석 결과, 각 단위식생의 발달은 해발고도, 인간간섭, 낙엽부식층, 암석노출율, 경사도 등에 영향을 받는 것으로 확인되었다. 단위식생의 종조성에 대한 집괴분석 결과로부터 벽방산 산림식생은 인위식생, 이차식생, 근자연식생으로 구분되며, 식생의 발달정도, 토지적 특성, 인위적 식재 및 관리 유무 등에 의해 삼림이 구성되고 있는 것으로 확인되었다.

• Journal of Microbiology
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• 제44권3호
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• pp.301-310
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• 2006

Two pathways of ammonium assimilation and glutamate biosynthesis have been identified in microorganisms. One pathway involves the NADP-linked glutamate dehydrogenase, which catalyzes the amination of 2-oxoglutarate to form glutamate. An alternative pathway involves the combined activities of glutamine synthetase, which aminates glutamate to form glutamine, and glutamate synthase, which transfers the amide group of glutamine to 2-oxoglutarate to yield two molecules of glutamate. We have cloned the large subunit of the glutamate synthase (GOGAT) from Salmonella typhimurium by screening the expression of GOGAT and complementing the gene in E. coli GOGAT large subunit-deficient mutants. Three positive clones (named pUC19C12, pUC19C13 and pUC19C15) contained identical Sau3AI fragments, as determined by restriction mapping and Southern hybridization, and expressed GOGAT efficiently and constitutively using its own promoter in the heterologous host. The coding region expressed in Escherichia coli was about 170 kDa on SDS-PAGE. This gene spans 4,732 bases, contains an open reading frame of 4,458 nucleotides, and encodes a mature protein of 1,486 amino acid residues (Mr =166,208). The EMN-binding domain of GOGAT contains 12 glycine residues, and the 3Fe-4S cluster has 3 cysteine residues. The comparison of the translated amino acid sequence of the Salmonella GOGAT with sequences from other bacteria such as Escherichia coli, Salmonella enterica, Shigella flexneri, Yersinia pestis, Vibrio vulnificus and Pseudomonas aeruginosa shows sequence identity between 87 and 95%.

• Fisheries and Aquatic Sciences
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• 제2권1호
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• pp.66-77
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• 1999

The sequences coding for the 5.8S rDNA and the internal transcribed spacers (ITS1 and ITS 2) from the isolates of nine isolates of Gyrodinium impudicum and two isolates of Gymnodinium sanguineum species were amplified, sequenced and compared with the previously known Alexandrium species and Gymnodinium catenatum. The genetic distance analyses based on the sequence alignment indicated that Gymnodinium catenatum and Gyrodinium impudicum species were some related, Alexandrium species was distant. G. catenatum and G. sanguineum were quite separate, but these two species belonged to the same genus. G. impudicum and G. catenatum forming the closet cluster showed some variation in the alignment of ITS regions. The length of ITS1 varied more than that of ITS2 and the length of ITS1 and ITS2 was different for each G. impudicum, Gymnodinium and Alexandrium species. Also, the length of ITS1 was shorter than that of ITS2. However, on the sequences of G. sanguineum, the length of ITS1 was longer about 23 nucleotides than that of ITS2. The phylogenetic analysis and rDNA similarity of G. impudicum and G. catenatum $(59\%)$ is higher than the that of G. catenatum and G. sanguineum $(55\%)$. It was thought that the phylogenetic analysis and the genetic distance revealed that G. impudicum and G. catenatum were clearly different species and G. impudicum may belong to the genus of Gymnodinium.

• 한국재료학회지
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• 제12권11호
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• pp.860-864
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• 2002

$Li^{+}$ extraction reactions with ion-exchange type lithium manganese oxide in an aqueous phase were examined using chemical and x-ray diffraction (XRD) analysis. In the process of extraction reaction, the lithium manganese oxide showed a topotactic extraction of $Li^{+ }$ in the aqueous phase mainly through an ion-exchange mechanism, and the $Li^{+}$ extracted samples indicated a high selectivity and a large capacity for $Li^{+}$ . The electronic structures and chemical bonding properties were also studied using a discrete variational (DV)-X$\alpha$ molecular orbital method with cluster model of (Li$Mn_{12}$ $O_{40}$ )$^{27-}$ for tetrahedral sites and ($Li_{7}$ Mn $O_{38}$ )$^{3}$ for octahedral site in $Li_{1.33}$ $Mn_{1.67}$ / $O_{4}$ respectively. Li in the manganese oxides is highly ionized in both sites, but the net charge of Li was greater for tetrahedral sites than octahedral. These calculations suggest that the tetrahedral sites have higher $Li^{+}$ $H^{+}$ exchangeability than the octahedral sites, and are preferable for the selective adsorption for L $i^{+}$ ions.s.

• Parasites, Hosts and Diseases
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• 제54권2호
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• pp.197-200
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• 2016

Cryptosporidium, a protozoan parasite, can cause cryptosporidiosis which is a gastrointestinal disease that can infect humans and livestock. Cattle are the most common livestock that can be infected with this protozoan. This study was carried out to determine the prevalence of Cryptosporidium infection in cattle in Kuantan, Pahang, Malaysia and to find out the association between the occurrence of infection and 3 different ages of cattle (calves less than 1 year, yearling, and adult cattle). The samples were processed by using formol-ether concentration technique and stained by modified Ziehl Neelsen. The results showed that 15.9% (24/151) of cattle were positive for Cryptosporidium oocysts. The occurrence of Cryptosporidium in calves less than 1 year was the highest with the percentage of 20.0% (11/55) followed by yearling and adult cattle, with the percentage occurrence of 15.6 % (7/45) and 11.8% (6/51), respectively. There was no significant association between the occurrence and age of cattle and presence of diarrhea. Good management practices and proper hygiene management must be taken in order to reduce the infection. It is highly important to control the infection since infected cattle may serve as potential reservoirs of the infection to other animals and humans, especially animal handlers.

• Journal of Forest and Environmental Science
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• 제25권2호
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• pp.93-100
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• 2009

In Malaysia, Labisia pumila Benth & Hook f, popularly known as 'Kacip Fatimah' has been used traditionally to treat various elements of the woman's health in Malay community. The objective of this study was to develop randomly amplified polymorphic DNA (RAPD) based DNA markers for the identification of L. pumila and to distinguish its three varieties from each other. Total DNA from nine accessions of L. pumila was extracted by CTAB method and polymerase chain reactions (PCR) were carried out to amplify the segments of DNA using different primers to develop DNA barcode using RAPD technique. To find out variety-specific DNA marker/s, twenty different 10-mer primer sequences with annealing temperature from 36-$40^{\circ}C$ were evaluated in triplicate. Out of 20 random primers, two primers (OPA-1 and OPA-2/A10) were selected which produced reliable RAPD band patterns. To have DNA based handle, two RAPD amplification products were cloned and sequenced to determine the identity of the DNA. RAPD analysis using two random primers generated 72 discrete bands ranging in size 200 bp-3,000 bp. Fifty nine of these were polymorphic loci (82%) and thirteen were non-polymorphic loci (18%). A total of 32 bands polymorphic loci (72%) were amplified with primer OPA-1 and analyzed by cluster analysis and UPGMA (Unweighted Pair Group Method with Arithmetic) to present a dendogram depicting the degree of genetic relationship among nine accessions of L. pumila. Our results shows the reasonable genetic diversity among the L. pumila varieties and within varieties; and two RAPD marker sequences obtained could be used to identify L. pumila at species level.