• Polymer(Korea)
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• v.27 no.6
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• pp.603-608
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• 2003

Syndiotactic polystyrene (s-PS) presents a very complex polymorphic behavior depending on the sample preparation history and exhibits a solid-solid phase transition. Each different polymorphic structures of the s-PS sample were prepared by annealing the samples from room temperature to 220 $^{\circ}C$. The structural changes induced by annealing were investigated using FTIR and FT-Raman spectroscopy. Although the crystallization kinetics of s-PS are difficult to investigate with DSC due to its fast crystallization rate, it was possible to determine crystallinity changes in the s-PS sample using infrared characteristic peaks with Beer-Lambert's law.

• Korean Journal of Veterinary Research
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• v.45 no.3
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• pp.359-367
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• 2005

This study was carried out to understand the contamination patterns of Listeria in pork processing plants. A total of 402 samples were collected from carcass, pork during processing, surfaces of equipment and environment, and 238 isolates of Listeria species were identified. L. innocua was found in 64.7% of the isolates, L. monocytogenes in 33.2%, and L. welshimeri in 2.1%. Random amplified polymorphic DNA (RAPD) analysis performed to investigate the origin and routes of Listeria contamination, showed 21 composite types of L. monocytogenes and 26 composite types of L. innocua. It was confirmed that Listeria contamination begins with contaminated incoming carcass and ever-present contaminants in the processing environments. The persistence and dissemination of the same strain of L. monocytogenes and L. innocua throughout the processing line revealed that the sanitation standard operating procedure should be implemented to minimize the risk of colonization in the workplace. Molecular subtyping of L. innocua allowed us to tracing the possibility of cross-contamination during processing.

• Korean Journal of Medicinal Crop Science
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• v.13 no.2
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• pp.69-74
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• 2005

Kalopanax pictus is a long-lived woody species mostly distributed in East Asia. K. pictus has been regarded as medically and ecologically important species in Korea. Thornless castor aralia variant, local name 'Cheongsong' is an endemic to Cheongsong province in Korea. Random amplified polymorphic DNA (RAPD) was used to investigate the genetic variation and structure of Korean populations of two species. A high level of genetic variation was found in six K. pictus populations. Twelve primers revealed 49 loci, of which 29 were polymorphic (59.2%). Nei's gene diversity for K.pictus and K. pictus variant were 0.119 and 0.098, respectively. Mean of genetic diversity in K. pictus was higher than average values for species with similar life history traits. The asexual and sexual reproduction, perennial habitat, and longevity are proposed as possible factors contributing to high genetic diversity. An indirect estimate of the number of migrants per generation (Nm=0.857) indicated that gene flow was not extensive among Korean populations of K.pictus. It is suggested that the isolation of geographical distance and reproductive isolation between K.pictus and K.pictus variant populations may have played roles in shaping the population structure of this species.

• Journal of Korean Society of Forest Science
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• v.98 no.5
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• pp.568-575
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• 2009

Korean wild and forest cultivated ginseng has long been accepted as high medicinal values compared to field cultivated ginseng. Owing to the high price of Korean wild ginseng, Chinese wild and forest cultivated ginseng were smuggled and sold as Korean wild and forest cultivated ginseng. Therefore, an efficient method is required to distinguish Korean ginseng from Chinese ginseng. Microsatellites, simple sequence repeats (SSRs), are highly polymorphic loci present in DNA that consist of repeating units of base pairs. Thus SSR markers are highly advantageous for detection of small genetic variances of intra-species. In the present study, we constructed a microsatellite-enriched genomic library from South Korean wild Panax ginseng. After sequence analysis of 992 randomly picked positive colonies, 126 (12.7%) of the colonies were found to contain microsatellite sequences, and 38 primer pairs were designed. By polymorphism assessment using 36 primer pairs, 4 primers (PG409, PG450, PG491, and PG582) were shown to be polymorphic to distinguish the South Korean ginseng from the Chinese ginseng. These 4 microsatellite markers will provide powerful tools to authenticate South Korean ginseng from Chinese ginseng.

• Archives of Pharmacal Research
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• v.23 no.4
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• pp.381-384
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• 2000

It is well recognized that physicochemical properties of drugs are affected by the type of polymorphic crystalline form of drugs. Clarithromycin is known to exist in at least three polymorphic crystalline forms. Since conventional means to obtain the most thermodynamically stable form (Form II) for the antibiotics is known to be associated with a low purity of the stable form, we developed a novel method to improve the purity of the crystalline form by a modification of the preparation process. The new method involved a simple recrystallization of clarithromycin in solvents having 5-12 carbon atoms (e.g., hexane and heptane) or ethers with 4-10 carbon atoms (e.g., isopropyl ether) and, thus, less likely to be associated with the problem in purity of resulting crystal. Differential scanning calorimetry and powder X-ray diffraction were used to compare the crystalline form of the resultant powder with Form IIcrystal prepared by the conventional method. The crystal prepared by the new method was identical to Form IIcrystal of the conventional method as evidenced by the lack of the exothermic peak near 11$0^{\circ}C$ in differential calorimetry scan, indicating that Form IIcrystal could be readily prepared by the new process. Therefore, these data indicated that the improvement in the purity of the Form IIcrystal for clarithromycin as well as a significant cost reduction is likely by the novel method.

• The Korean Journal of Zoology
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• v.19 no.3
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• pp.123-138
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• 1976

Isozymes and chromosomes of Bufo bufo and B. kangii were studied by starch gel electrohporesis and bone marrow air-drying method. Twently-three enzymes and nonenzymatic proteins in Bufo species collected in Korea provided a basis for the estimating the proportion of polymorphic loci in the genum. Of 23 loci controlling the proteins examined, 26% and 17$% were polymorphic in B. bufo and B. kangii, respectively. In B. bufo, 4 loci had 3 alleles and no loci had more than 2 alleles in B. kangii. Both species had same karyotypes with 22 chromosomes except one pair of chromosome which had sat-chromosomes in B. bufo karyotypes. The genetic similarity was approximately 0.5.

• Korean Journal of Plant Resources
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• v.24 no.6
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• pp.666-674
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• 2011

To elucidate genetic diversity of common reed in Korea, we collected a total of 674 common reed plants from 27 regions in South Korea. Hierarchical clustering using 7 morphological traits divided the 27 common reed populations into 7 groups. Random amplified polymorphic DNA (RAPD) results identified three distinct groups of common reed. Common reed accessions in group I mostly inhabit coastal areas. Group II includes reeds mostly collected from inland areas. Group III consists of common reed accessions collected from inland and coastal areas, suggesting that this group might contain hybrids. In summary, we suggest that parapatric speciation might be an important factor in the genetic diversity of common reed and geographical speciation of common reed that might be also affected by environmental gradients.

• Korean Journal of Plant Resources
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• v.24 no.6
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• pp.675-687
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• 2011

Mulberries have importance in the sericulture industry as food for Bombyx mori, silkworm reared for its silk. Korean Morus alba have many cultivars and, for the protection of these cultivars and for utilization in plant-breeding programs, genetic information and the diversity among cultivars are essential. This study with 14 mulberry genotypes was undertaken using RAPD and ISSR fingerprinting to discover the genetic divergences between cultivars. Polymorphism rate among the cultivars produced by RAPD primer was found to be 64.48% and 66.29% relative to ISSR primer. The genetic relationships among the cultivars were identified using a dendrogram constructed with the UPGMA clustering method. Nei's method was used to calculate the genetic dissimilarity coefficients between each pair of genotypes, and the highest dissimilarity coefficient of 0.246 was exhibited between Suwon and Hwanggum cultivars. To determine the efficiency of each primer, a polymorphic index was calculated, and the robustness of the dendrogram was checked using cophenetic correlation coefficient. The results of this study can be utilized for the improvement of mulberry varieties in plant-breeding programs.

• Korean Journal of Plant Taxonomy
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• v.48 no.3
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• pp.195-200
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• 2018

Genetic assessments of rare and endangered species are among the first steps necessary to establish the proper management of natural populations. Transcriptome-derived single-sequence repeat markers were developed for the Korean endangered species Astilboides tabularis (Saxifragaceae) to assess its genetic diversity. A total of 96 candidate microsatellite loci were isolated based on transcriptome data using Illumina pair end sequencing. Of these, 26 were polymorphic, with one to five alleles per locus in 60 individuals from three populations of A. tabularis. The observed and expected heterozygosity per locus ranged from 0.000 to 0.950 and from 0.000 to 0.741, respectively. These polymorphic transcriptome-derived simple sequence repeat markers would be invaluable for future studies of population genetics and for ecological conservation of the endangered species A. tabularis.

• Journal of Pharmaceutical Investigation
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• v.27 no.3
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• pp.233-239
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• 1997

Glibenclamide is a second generation sulfonylurea that is orally active as a hypoglycemic drug. It exists as a crystalline powder which is sparingly soluble in water. It was investigated that the potential of glibenclamide to exhibit polymorphism. Three polymorphic modifications (form 1, form 2 and form 3) and three pseudopolymorphic modifications (form 4, form 5 and form 6) were obtained by crystallization from different organic solvents. The isolated crystal forms were characterized by differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and X-ray crystallography powder diffraction studies. Form 1 was the most stable and melt at $175.4^{\circ}C$. Form 2 was metastable and melt at $151.0^{\circ}C$. Form 3 was a new polymorphic modification because it was different from form 1 and form 2 in X-ray crystallography powder diffraction data. Form 4 was a 1 : 7(toluene : glibenclamide) toluene solvate; form 5 was a 1 : 5(toluene : glibenclamide) toluene solvate; form 6 was a 3 : 8(pentanol : glibenclamide) pentanol solvate. All forms were stable in 3-month storage under 0% or 100% humidity condition. The dissolution rate of form 4 was highest; those of form 2, form 3, form 1, form 5 and form 6 followed.