• Computers and Concrete
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• 제11권6호
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• pp.493-513
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• 2013

Direct displacement-based design (DDBD) represents an innovative philosophy for seismic design of structures. When structural considerations are more critical, DDBD design should be carried on the basis of limiting material strains since structural damage is always strain related. In this case, the outcome of DDBD is strongly influenced by the displacement demand of the structural element for the target limit strains. Experimental studies have shown that anchorage slip may contribute significantly to the total displacement capacity of R/C column elements. However, in the previous studies, anchorage slip effect is either ignored or lumped into flexural deformations by applying the equivalent strain penetration length. In the light of the above, an attempt is made in this paper to include explicitly anchorage slip effect in DDBD of R/C column elements. For this purpose, a new computer program named RCCOLA-DBD is developed for the DDBD of single R/C elements for limiting material strains. By applying this program, more than 300 parametric designs are conducted to investigate the influence of anchorage slip effect as well as of numerous other parameters on the seismic design of R/C members according to this methodology.

• Structural Engineering and Mechanics
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• 제2권1호
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• pp.17-34
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• 1994

This paper proposes a new four node degenerated shell element. In the formulation of the new element, the assumed covariant shear strains are used to avoid the shear locking problem, and the assumed covariant membrane strains are applied to alleviate the membrane locking problem and also to improve the membrane bending performance. The assumed covariant strains are obtained from the covariant strain field defined with respect to the element natural coordinate system. This formulation enables us to obtain a shell element, which does not produce spurious singular modes, avoids locking phenomena, and excels in calculation efficiency. Several examples in this paper indicate that, despite its simplicity, the achieved accuracy and convergence are satisfactory.

• Food Science and Biotechnology
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• 제18권3호
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• pp.655-660
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• 2009

Biotechnological phytase preparations are commercially available and are currently used in animal feeding. However, thermostability constraints, low yields, and the high cost of the enzyme have limited its use. This study represents a new perspective for the food enzyme market. The research screened thermostable yeast strains for their ability to produce phytase. The screening was carried out with a gradual increase in temperature ($30-48^{\circ}C$). Sixteen strains (1 strain identified as Saccharomyces cerevisiae) maintained the ability to produce phytase at $48^{\circ}C$ and their phytase activity was confirmed using 2 phytase assay methodologies. The yeast strains tested in this study seem to be potential efficient producers of phytase, indicating a possible new source of thermostable phytase of commercial interest, particularly that from S. cerevisiae.

• ALGAE
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• 제36권2호
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• pp.111-121
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• 2021

Two cyanobacterial morphotypes isolated from Signy Island, South Orkney Islands, maritime Antarctica were characterised using a polyphasic approach combining morphological, cytological and molecular analyses. These analyses showed that the strains grouped with members of the genus Wilmottia. This genus currently includes three species, W. murrayi, W. stricta, and W. koreana. Both morphotypes analysed in this study were placed within the clade of W. murrayi. This clade showed a well-supported separation from Antarctic and New Zealand strains, as well as strains from other regions. W. murrayi was first described from Antarctica and is now known from several Antarctic regions. Confirmation of the occurrence of W. murrayi at Signy Island significantly extends its known distribution in Antarctica. In addition, a new combination, W. arthurensis, is suggested for Phormidium arthurensis.

• 대한임상검사과학회지
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• 제38권3호
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• pp.173-178
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• 2006

The production of extended-spectrum ${\beta}$-lactamases ($ESBL_S$) is the main mechanism of bacterial resistance to third-generation cephalosporins and monobactams, whose prevalence varies depending on the different geographical areas. In the last years it has increased notably to the point of being considered a health problem of great importance. The characterization of the ESBLs producing Klebsiella penumoniae strains present in clinical isolates is time-consuming. I describe here the development of a new system, which consists of a multiplex PCR. I found 51 K. pneumoniae strains to be presumptive strains ESBLs producers by clinical and laboratory standards institute (CLSI) guidelines. The double disc synergy test showed 47 positive K. pneumoniae, which were K. pneumoniae isolates. All ESBLs producing K. pneumoniae strains were resistant to antibiotic amikacin, gentamicin and ciprofloxacin. By multiplex PCR analysis, $bla_{TEM}$ gene in 17 strains 44 $bla_{SHV}$ genes and $bla_{CTX}$ genes in 33 strains were identified. In this study, the multiplex polymerase chain reaction (PCR) assay was a good method to detect and differentiate ESBLs producing K. penumoniae strains in clinical isolates.

• Archives of Pharmacal Research
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• 제21권3호
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• pp.310-314
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• 1998

DW-116 is a new fluoroquinolone antimicrobial agent with a broad spectrum. In order to elucidate the resistance mechanism to DW-116 in Acinetobacter spp. bacteria, total chromosomal DNA was isolated from 10 strains of Acinetobacter spp. resistant to DW-116. Quinolone resistance determinant region (QRDR) of DNA gyrase gene was amplified by PCR. The 345 bp nucleotide fragment yielded was inserted into pKF 3 which was used as the vector. Comparisons of the DNA sequences of 8 strains with that of the wild type strain revealed a Ser-83 to Leu mutation in mutants and all ten strains contained one silent mutation$(T{\rightarrow}G)$in QRDR. From Acinetobacter MB4-8 strain, DNA gyrase was isolated and purified, through novobiocin-sepharose, heparin-sepharose affinity column chromatography. The enzyme was composed of two subunits and the molecular mass of subunits A and B were 75.6 and 51.9 kDa, respectively. The supercoiling activity of the reconstituted DNA gyrase composed of subunit A from Acinetobacter MB4-8 and subunit B from E. coli was not inhibited by $128{\mu}\textrm{g}$ml of ciprofloxacin. It might be said that one of the resistance mechanisms to DW-116 in Acinetohacter MB4-8 was subunit A alteration of DNA gyrase.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.663-670
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• 2011

Under a daily photoperiod of 14h light and 10h dark synchronization of cell cycle in Korean Cyanothece spp. strains and $Synechococcus$ sp. strain Miami BG043511 was analyzed as to be applicable to enhanced hydrogen production. For all strains peaks of double cell were observed during the light period of a daily cycle. Peaks of maximal cell size measured by a coulter counter appeared at the peak of double cells observed under light microscope reconfirming the synchronization of daily cell cycle. The cell cycle synchronization became weakened within two days when treated with continuous illumination. Rapid detection of the peak time of double cell percentage by coulter counters may contribute to quasi-realtime feedback control for efficient production of photobiological hydrogen by unicellular cyanobacterial strains.

• Ocean and Polar Research
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• 제26권1호
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• pp.51-58
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• 2004

We isolated and identified culturable Arctic bacteria that had inhabited soils around the Korean Arctic Research Station Dasan located at Ny-Alsund, Svalbard, Norway $(79^{\circ}N,\;12^{\circ}E)$. The collected soils were diluted in distilled water; the diluted soil-water was spread on 3M petri-films at Dasan Station. The petri-films were transported to the laboratory at KORDI, and cultured at $4^{\circ}C$. Colonies grown on the petri-films were subsequently cultured on nutrient agar plates at $4^{\circ}C$ every 7 days. The pure colonies were inoculated into nutrient liquid media, genomic DNA was extracted, and phylogenetic analysis was performed on the basis of 165 rDNA sequences. A total of 227 strains of bacteria were isolated. Among them, 16S rDNA sequences of 185 strains were identical with those of known strains isolated in this study, and 42 strains were finally identified. Phylogenetic analysis using 16S rDNA indicated that the 30 strains belonged to Pseudomonas, 7 strains to Arthrobacter, two strains to Flavobacterium, and the remaining to Achromobacter, Pedobacter, and Psychrobacter. Among the 42 strains, 14 bacteria produced protease: they were 6 strains of Pseudomonax, 4 strains of Arthrobater, an Achromobacter strain, 2 strains of Flavobacterium, and a Pedohacter strain. We expect these Arctic bacteria can be used for screening to develop new industrial enzymes that are active at low temperatures.

• KSBB Journal
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• 제27권3호
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• pp.151-156
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• 2012

Lactic acid is an important product arising from the anaerobic fermentation by lactic acid bacteria (LAB). It is used in the pharmaceutical, cosmetic, chemical, and food industries as well as for biodegradable polymer and green solvent production. The poly lactic acid (PLA) is an important material for bio-plastic manufacturing process. For PLA production by new LAB, we screened LAB isolates from shellfish. A total of 28 LAB were isolated from various shellfishes. They were all Gram positive, oxidase and catalase negative. Based on API 50CHL kit, 7 strains among the 28 isolates were identified as Lactobacillus plantarum, 6 strains as Lactobacillus delbrueckii, 5 strains as Leuconostoc mesenteroides, 3 strains as Lactobacillus brevis, 2 strains as Lactococcus lactis, 1 strain as Lactobacillus salivarius, 1 strain as Lactobacillus paracasei, 1 strain as Lactobacillus pentosus, 1 strain as Lactobacillus fermentum and 1 strain as Pediococcus pentosaceu. Also, we examined the amount of total lactic acid produced by these new strains by HPLC analysis with Chiralpak MA column. One strain E-3 from Mytilus edulis was indentified as Lactobacillus plantarum and found to produce 20.0 g/L of D-form lactic acid from 20 g/L of dextrose. Further studies are underway to increase the D-lactic acid production by E-3.

• 한국응용곤충학회지
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• 제23권4호
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• pp.209-214
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• 1984

1980년도부터 우리나라 Burley 종 잎담배산지에서 엽맥에 녹대병상 또는 괴저증상을 나타내는 새로운 병징이 관찰되기 시작하였다. 기주범위조사, 항혈청반응, 물리적성질조사, 복숭아혹진딧물에 의한 전염여부 및 바이러스 입자 관찰을 통해 이들은 서로 병징을 달리하는 PYY의 두가지 계통으로 밝혀졌다. 이 계통들은 잎담배포장에서 자연감염에 의해 나타난 주요병징에 따라 엽맥연대계통 (PVY-VB)과 엽맥괴저계통 (PVY-VN) 으로 명명하였다. PVY 항혈청과 이 계통들의 이병즙액을 반응시킨 결과 양성반응을 나타냈으며 그 반응에서는 두계통간의 차가 없었다. 이들과 병징이 유사한 tobacco etch virus 및 tobacco vein mottling virus 항혈청과의 반응에서는 음성반응을 나타냈다. 전자현미경에 의해 약 730 nm의 사상형 바이러스 입자가 관찰되었으며 그 형태와 크기에는 두 계통간 차가 없었다.