• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.725-736
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• 2000

It is becoming increasingly apparent that periodontitis consists of mixture of diseases, most of which respond favorably to traditional mechanical therapy. Among these variants of the disease, some appear to be associated with unusual microbial infections and defective host defenses. Many of these fail to respond to conventional treatment. The recognition that some forms of periodontitis are refractory to standard periodontal therapy has given rise to a new classification of peridontitis. A series of 1692 subgingival microbial samples sent to a diagnostic microbiology laboratory included 738 samples that could be identified as compatible with a clinical diagnosis of refractory or recurrent periodontitis. In descending order of prevalence the associated microbiota included Bacteroides forsythus(85%) ,Fusobacterium species(78%), Spirochetes(67%), Campylobacter rectus(64%), Porphyromonas gingivalis(59%), Peptostreptococcus micros(58%), motile rods(46%), Prevotella intermedia(33%), Eikenella corrodens(13%), Capnocytophaga species(12%) ,and Actinobacillus actinomycetemcomitans(6%). Antibiotic resistance to tetracycline, penicillin G, or metronidazole was particularly noticeable for Fusobacterium species, Capnocytophaga species, and Actinobacillus actinomycetemcomitans. It was largely absent for Campylobacter rectus. No antibiotic data were obtained for Porphyromonas gingivalis or Bacteroides forsythus, as these species were detected by immunofluorescence. The results indicate that a substantial number of microorganisms associated with refractory periodontitis are variably resistant to commonly-used antibiotics. Diagnostic microbiology must be considered an essential adjunct to the therapist faced with periodontal lesions refractory to conventional treatment.

• The Korean Journal of Ceramics
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• v.1 no.1
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• pp.29-34
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• 1995

Theoretical predictions were made for thermodynamically stable phases which formed when alkali(sodium and Potassium) vapors reacted with the 90% $Al_2O_3$-10% $Cr_2O_3$ refractory under coal gasifying atmosphere using the computer program of SOLGASMIX-PV. The calculation results showed that the stable compounds that formed were $X_2O$.$Al_2O_3$ and $X_2O$.$llAl_2O_3$(X=$Na^+$ or $K^+$), depending upon the alkali concentration. The presence of sulfur in gasifying atmospheres did not appear to affect the species of alkali reaction products. Alkali attack at high temperatures is likely to cause serious degradation at the hot face of the refractory, indicating that the alkali concentration is an important factor to affect the degradation of the refroctory.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.15-21
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• 2003

Two microbial communities of activated sludge in the same municipal wastewater, but treated with different systems, were studied and compared using molecular microbiological approaches. The bacterial 16S rDNA sequences from 124 clones were analyzed, however, the majority of them were not closely related to any known species, and found to belong to 8 different phylogenetic groups and 3 different unidentified groups. The relative frequencies of each group were similar between the two microbial communities. Fingerprinting using terminal restriction fragment length polymorphism (T-RFLP) showed that the putative Nitrospira-related populations were more diverse and quantitatively higher in the KNR process system than in the other system using a conventional activated sludge process. The relationship between the bacterial community composition and the higher removal efficiency of nitrogen and phosphorus in the KNR process is discussed.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.544-558
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• 2017

The objective of this research is to investigate preservative efficacy for refractory species in field tests. The field tests were set up to evaluate the preservative performance of western hemlock and white spruce preservative-treated to the residential products group C and D of Canadian standard (CSA O80 Series-08) that have been developed for residential use in above-ground and ground-contact conditions, respectively. They were incised and pressure-treated with alkaline copper quaternary (ACQ) or copper azole (CA). Treated samples for the ground contact stake test and ground proximity test were installed in Jinju, Korea on November 2010 according to AWPA E7-09 and AWPA E18-06, respectively. Each sample has been annually assigned ratings for decay and termite attack, based on AWPA E7 grading system. After six years and five months of exposure, the untreated samples showed decay and particularly severe damage by termite attack but all the preservative-treated samples showed no decay. The results showed that the 5-mm penetration depths may be applicable for the treatment of refractory species. This paper discusses what to consider for the use of refractory species in Korean wood preservation industry from the penetration and retention points of view.

• Horticulture, Environment, and Biotechnology : HEB
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• v.59 no.6
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• pp.865-873
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• 2018

Allium ochotense and Allium microdictyon are commonly known as 'Mountain garlic' and are popular, economically important species in many countries such as Korea, China, and Mongolia. Their leaves are used as culinary side dishes and in traditional medicines. In Korea, these two species are at risk of extinction due to damage to their natural habitat and thus, conservation and breeding programs are needed. However, their identification relies mostly on morphological data, which is limited and until recently, led to classifying these two species under A. victorialis. In the present study, a simple and reliable method of molecular identification was developed to distinguish A. ochotense from A. microdictyon that targets four barcoding regions: the internal transcribed spacer (ITS), the maturase K gene (matK), the chloroplast psbA-trnH intergenic region, and the ribulose-bisphosphate carboxylase large subunit gene (rbcL). Single nucleotide polymorphisms (SNPs) were found in ITS and matK regions, and species-specific primers were designed based solely on the SNP at position 680 of the ITS region that could differentiate A. ochotense from A. microdictyon. Using these primers in amplification refractory mutation system (ARMS)-PCR, A. ochotense, and A. microdictyon could be simultaneously and efficiently distinguished. This study is the first to report a simple, rapid, and efficient method for discriminating A. ochotense and A. microdictyon, indicating the utility of species-specific markers in the development of conservation and breeding programs.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.1
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• pp.79-85
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• 2006

Innovated technique to oxidize pollutants has been developed. The technique for this study uses plasma discharge in 2-phase (Air-Water) and is called Discharged Water Generating (DWG) system. It produces electric arc which generates not only the physical decomposing power against the pollutants but also oxidants to sterilize pollutants depending on the inlet gas species. These physical and chemical products play an important role in COD decrease and biodegradability enhancement. The enhancement of biodegradability for the refractory organic substances in aqueous solution was estimated in this study. Argon discharge reduced NBDCOD of EDTA from 58.7mg/L to 38.8mg/L, but oxygen discharge and ozonation reduced it to 37.74mg/L and 38.73mg/L respectively. Furthermore, Argon discharge changed 1181mg/L of NBDCOD of dye effluent into 606mg/L but oxygen discharge and ozonation changed it into 888mg/L and 790mg/L respectively.

• Journal of the Korean Wood Science and Technology
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• v.47 no.6
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• pp.667-673
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• 2019

The performance of a wooden deck made of refractory materials that have difficulties in achieving target penetrations as stipulated in the specification and quality standards for treated wood in Korea, was assessed via a case study in this research. A wooden deck built in Jinju in 2009 was selected for this study because of its fabrication method using pressure and treated refractory materials. The penetration and retention analysis did not satisfy the domestic standard for treated wood. Inspection of the deck in 2019 revealed that the deck had been attacked by decay fungi. Cap rails showed much deeper and wider checking on their surface compared with the top and base rails, resulting in a severe fungal attack. The decking boards exhibited severe fungal decay primarily in the end parts. However, the rails and balusters without checks and posts were virtually free of fungal attack irrespective of the preservative penetration measures. Copper content in the soil 5 cm away from the deck was less than 150 mg/kg, implying that copper movement in the soil was very limited. These results suggest that the inhibition of surface propagation and the protection of end surfaces are essential factors in increasing the longevity of treated wooden decks; further, the results also showed that the deck was within an acceptable range from the point of copper contamination.

• Journal of Ginseng Research
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• v.34 no.1
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• pp.41-46
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• 2010

Expensive herbs such as ginseng are always a possible target for fraudulent labeling. New mountain ginseng strains have occasionally been found deep within mountain areas and commercially traded at exorbitant prices. However, until now, no scientific basis has existed to distinguish such ginseng from commonly cultivated ginseng species other than by virtue of being found within deep mountain areas. Polymerase chain reaction (PCR) analysis of the internal transcribed spacer has been shown to be an appropriate method for the identification of the most popular species (Panax ginseng) in the Panax ginseng genus. A single nucleotide polymorphism (SNP) has been identified between three newly found mountain ginseng (KGD4, KGD5, and KW1) and already established Panax species. Specific PCR primers were designed from this SNP site within the sequence data and used to detect the mountain ginseng strains via multiplex PCR. The established multiplex-PCR method for the simultaneous detection of newly found mountain ginseng strains, Korean ginseng, and foreign ginseng in a single reaction was determined to be effective. This study is the first report of scientific discrimination of "mountain ginsengs" and describes an effective method of identification for fraud prevention and for uncovering the possible presence of other, cheaper ginseng species on the market.

• Animal cells and systems
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• v.2 no.3
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• pp.333-339
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• 1998

Litter decomposition is a key process in energy flow and nutrient cycling in the freshwater littoral zone, and is regulated by physicochemical properties of litters. Using a litterbag method, we compared the decomposition rates of 16 different litter types from 10 plant species of the emergent macrophytes for one year in the littoral zone of the Paltangho Reservoir, Korea. The regression analysis fitted to the various decomposition models showed that mass loss of the litters with time best fitted an asymptotic function. The litters of the emergent macrophytes were composed of two compartments, labile and refractory. The macrophytic litters showed a great variety in decomposition dynamics depending on sources of litters. The labile compartment of the initial litter mass was in a wide range between 18% and 99%, and their decomposition rates varied from 0.0037 to 0.0131 day-1. The decomposition processes of the emergent macrophytes were determined by the relative amounts of the labile and refractory compartments and by the decomposition rate of the habile one in the littoral zone.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.41-41
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• 2019

The genus Ficus L., containing approximately 850 species, is by far the largest genus in the Moraceae. They are mainly distributed worldwide, mainly in tropical countries. In South Korea, there are three native Ficus (including F. erecta Thunb, F. sarmentosa var. nipponica (Franch. & Sav.) Corner, and F. thunbergii Maxim.). Among them, F. erecta is effectively natural resources for the improvement of senile cognitive impairment. However, the chloroplast (cp) genome sequences and information of F. erecta have not been addressed. Therefore, in this study, we provide the complete cp genome of F. erecta and its allied species using next-generation sequencing technology. The chloroplast of Ficus species has typical structure which includes large and small single copy regions and a pair of inverted repeats (IRs). The sizes of cp genomes range from 160,276 bp to 160,603 bp. To determine the phylogenetic positions of these species, we conducted a maximum likelihood analysis using common protein-coding genes in chloroplast sequences. Also, we describe a newly developed single nucleotide polymorphism (SNP) markers using multiplex PCR to identify F. erecta based on amplification-refractory mutation system (ARMS) technique. We analyzed matK, atpB of the chloroplast genes and ITS from F. erecta and three related taxa, F. carica, F. sarmentosa var. nipponica and F. thunbergii. It provides useful information for molecular identification between F. erecta and related Korean native species.