• Title/Summary/Keyword: High-Frequency isolated

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Cadmium removal by Anabaena doliolum Ind1 isolated from a coal mining area in Meghalaya, India: associated structural and physiological alterations

  • Goswami, Smita;Syiem, Mayashree B.;Pakshirajan, Kannan
    • Environmental Engineering Research
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    • v.20 no.1
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    • pp.41-50
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    • 2015
  • The cyanobacterium Anabaena doliolum Ind1 isolated from a coal mining site was tested for removal of cadmium at optimum pH 7.0 and temperature $25^{\circ}C$. The organism recorded high percentage of metal removal (92-69%) within seven days of exposure to 0.5-2.0 ppm cadmium. Biosorption onto the cell surface was the primary mode of metal removal. Fourier transform infrared spectroscopy (FTIR) established hydroxyl, amides, carboxyl, sulphate and carbonyl groups to be the major functional groups on the cell surface involved in cadmium binding. Cellular ultrastructure and a range of vital physiological processes (i.e., photosynthetic pigments, respiration, photosynthesis, heterocyst frequency and nitrogenase activity) remained unaffected upon 0.5 ppm treatment; higher concentrations of cadmium exerted visible adverse effects. Amongst the five photosynthetic pigments tested, phycocyanin was the most targeted pigment (inhibition was 15-89%). Both respiration and photosynthetic activities were inhibited by cadmium with more severe effect seen on respiration. 2.0 ppm cadmium exposure also had drastic negative effect on nitrogenase activity (87% decreased).

Molecular typing of epidemiologically unrelated Staphylococcus epidermidis recovered from dogs by pulsed-field gel electrophoresis

  • Pak, Son-il
    • Korean Journal of Veterinary Research
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    • v.39 no.4
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    • pp.811-818
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    • 1999
  • A total of 16 Staphylococcus epidermidis isolates collected from 14 dogs admitted to the Veterinary Medicial Teaching Hospital in Seoul National University over eleven months were examined for in vitro antibiotic susceptibility pattern with minimum inhibitory concentration (MIC) and slime production, a virulence-associated phenotype, and were genetically characterized by pulsed-field gel electrophoresis (PFGE). The frequency of resistance to antimicrobial agents tested was not high, with a susceptibility ranging from 56.3% to 100%. Three strains exhibited multiple drug resistance against amikacin (MIC, $32-64{\mu}g/ml$), ampicillin ($32{\mu}g/ml$), fosfomycin ($32-128{\mu}g/ml$) and gentamicin ($16{\mu}g/ml$). Vancomycin, ciprofloxacin and rifampin were effective antibiotics against the isolates. All isolates were slime producers ; strains isolated from dogs which died of bacteremia were more likely to produce slime than those isolated from dogs which survived. Chromosomal DNA fingerprinting of the isolates yielded 16 different genomic types with few common bands, indicating a variety of clones of S epidermidis were prevalent in the hospital. This study revealed that PFGE is an useful method for the genotype characterization of S epidermidis strains and this organism could probably be pathogenic in some dogs with severe disorders. Further works on a larger number of epidemiologically defined strains are required to assess these results.

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Effect of nitroglycerin on isolated rabbit cardiac muscle and coronary strip (적출심근 및 관상동맥에 대한 Nitroglycerin 의 작용)

  • Hong, Jang-Su;Seo, Gyeong-Pil;Kim, Gi-Hwan
    • Journal of Chest Surgery
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    • v.16 no.3
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    • pp.272-280
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    • 1983
  • With respect to controversial opinions concerning the nitroglycerin effects on cardiac muscle the direct nitroglycerin actions were thoroughly studied in isolated papillary muscles, atrial preparations and coronary strips of rabbits. Isometric active tension of papillary muscles developed at $35^{\circ}C$ upon electric stimulation at a rate of 60/min, was not affected by nitroglycerin up to a concentration of 10mg/L Higher concentrations of nitroglycerin, however, reduced action tension progressively. This depression of mechanical activity is accompanied by a decrease in oxygen consumption as measured by means of a flow respirometer. Resting oxygen uptake, on the other hand, remained unchanged. Similarly active tension of spontaneously beating atrial preparations also declined at a nitroglycerin concentration of more than 10 mg/L, whereas the sinus frequency did not change up to 40 mg/L. In contrast, rabbit coronary strips are much more sensitive to nitroglycerin and relax in a range of 10-100 ug/L of nitroglycerin concentration. The results indicate that the pharmacologic effects of nitroglycerin in coronary disease are due to vascular actions, because the plasma levels of nitroglycerin attainable in human therapy are not sufficiently high to directly influence the myocardium.

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Diversity of Endophytic Fungi Associated with Roots of Calanthe discolor and Cephalanthera longibracteata in Korea (새우난초와 은대난초 뿌리에서 분리한 내생균의 다양성)

  • Lee, Bong-Hyung;Eom, Ahn-Heum
    • The Korean Journal of Mycology
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    • v.46 no.4
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    • pp.427-435
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    • 2018
  • In this study, endophytic fungi were isolated from the surface-sterilized roots of Calanthe discolor and Cephalanthera longibracteata collected from the Chungnam, Jeju, Kyungnam and Chungbuk provinces in Korea. The morphological characteristics of the obtained isolates were examined and their sequences of the internal transcribed spacer (ITS) rDNA region were analyzed using the ITS1F and ITS4 primers for species identification. Leptodontidium orchidcola showed the highest species abundance and frequency among the isolated endophytic fungi. Additionally, the community analysis revealed a high specificity between the host plants and the endophytic fungal species.

Genetic Variation of Strawberry Fusarium Wilt Pathogen Population in Korea

  • Cho, Gyeongjun;Kwak, Youn-Sig
    • Mycobiology
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    • v.50 no.1
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    • pp.79-85
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    • 2022
  • Strawberries are a popular economic crop, and one of the major plantations and exporting countries is Korea in the world. The Fusarium oxysporum species complex (FOSC) is a soil-borne pathogen with genetic diversity, resulting in wilt disease in various crops. In Korea, strawberries wilt disease was first reported in the 1980s due to the infection of FOSC, causing significant economic damage every year. The causal agent, F. oxysporum f. sp. fragariae, is a soil-borne pathogen with a characteristic of FOSC that is difficult to control chemically and mutates easily. This study obtained genetic polymorphism information that was based on AFLP, of F. oxysporum f. sp. fragariae 91 strains, which were isolated from strawberry cultivation sites in Gyeongsangnam-do and Chungcheongnam-do, and compared strains information, which was the isolated location, host variety, response to chemical fungicide, and antagonistic bacteria, and mycelium phenotype. As a result, AFLP phylogeny found that two groups were mainly present, and group B was present at a high frequency in Gyeongsangnam-do. Group B proved less sensitive to tebuconazole than group A through Student's t-test. In addition, the fractions pattern of AFLP was calculated by comparing the strain information using PCA and PERMANOVA, and the main criteria were separated localization and strawberry varieties (PERMANOVA; p< 0.05). And tebuconazole was different with weak confidence (PERMANOVA; p< 0.10). This study suggests that the F. oxysporum f. sp. fragariae should be continuously monitored and managed, including group B, which is less chemically effective.

Uncooled Pyroelectric Thin-film $(Ba,Sr)TiO_3$ Infrared Detector Thermally Isolated by Dielectric Membrane (유전체 멤브레인에 의해 열차단된 비냉각 초전형 박막 $(Ba,Sr)TiO_3$적외선 검지기)

  • Go, Seong-Yong;Jang, Cheol-Yeong;Kim, Dong-Jeon;Kim, Jin-Seop;Lee, Jae-Sin;Lee, Jeong-Hui;Han, Seok-Yong;Lee, Yong-Hyeon
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.38 no.3
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    • pp.229-235
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    • 2001
  • Uncooled pyroelectric thin-film (Ba,Sr)TiO$_3$ infrared detectors thermally isolated from Si-substrate by Si$_3$N$_4$/SiO$_2$/Si$_3$N$_4$-membrane have been fabricated, and figures of merit for detectors were examined. The detector at $25^{\circ}C$ in air showed relatively high voltage responsivity of about 168.8 V/W and low specific detectivity of about 2.6$\times$10$^4$cm.Hz$^{1}$2//W at 1 Hz-chopping frequency because of very small signal-to-noise voltage ratio. It could be found that both thermal noise voltage and thermal time constant of the detector were very large by analyzing dependences of output waveforms on chopping frequency and temperature.

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Incorporation preference for rubber-steel bearing isolation in retrofitting existing multi storied building

  • Islam, A.B.M. Saiful;Jumaat, Mohd Zamin;Hussain, Raja Rizwan;Hosen, Md. Akter;Huda, Md. Nazmul
    • Computers and Concrete
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    • v.16 no.4
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    • pp.503-529
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    • 2015
  • Traditionally, multi-story buildings are designed to provide stiffer structural support to withstand lateral earthquake loading. Introducing flexible elements at the base of a structure and providing sufficient damping is an alternative way to mitigate seismic hazards. These features can be achieved with a device known as an isolator. This paper covers the design of base isolators for multi-story buildings in medium-risk seismicity regions and evaluates the structural responses of such isolators. The well-known tower building for police personnel built in Dhaka, Bangladesh by the Public Works Department (PWD) has been used as a case study to justify the viability of incorporating base isolators. The objective of this research was to establish a simplified model of the building that can be effectively used for dynamic analysis, to evaluate the structural status, and to suggest an alternative option to handle the lateral seismic load. A finite element model was incorporated to understand the structural responses. Rubber-steel bearing (RSB) isolators such as Lead rubber bearing (LRB) and high damping rubber bearing (HDRB) were used in the model to insert an isolator link element in the structural base. The nonlinearities of rubber-steel bearings were considered in detail. Linear static, linear dynamic, and nonlinear dynamic analyses were performed for both fixed-based (FB) and base isolated (BI) buildings considering the earthquake accelerograms, histories, and response spectra of the geological sites. Both the time-domain and frequency-domain approaches were used for dynamic solutions. The results indicated that for existing multi-story buildings, RSB diminishes the muscular amount of structural response compared to conventional non-isolated structures. The device also allows for higher horizontal displacement and greater structural flexibility. The suggested isolation technique is able to mitigate the structural hazard under even strong earthquake vulnerability.

EMI Noise Source Reduction of Single-Ended Isolated Converters Using Secondary Resonance Technique

  • Chen, Zhangyong;Chen, Yong;Chen, Qiang;Jiang, Wei;Zhong, Rongqiang
    • Journal of Power Electronics
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    • v.19 no.2
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    • pp.403-412
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    • 2019
  • Aiming at the problems of large dv/dt and di/dt in traditional single-ended converters and high electromagnetic interference (EMI) noise levels, a single-ended isolated converter using the secondary resonance technique is proposed in this paper. In the proposed converter, the voltage stress of the main power switch can be reduced and the voltage across the output diode is clamped to the output voltage when compared to the conventional flyback converter. In addition, the peak current stress through the main power switch can be decreased and zero current switching (ZCS) of the output diode can be achieved through the resonance technique. Moreover, the EMI noise coupling path and an equivalent model of the proposed converter topology are presented through the operational principle of the proposed converter. Analysis results indicate that the common mode (CM) EMI noise and the differential mode (DM) EMI noise of such a converter are deduced since the frequency spectra of the equivalent controlled voltage sources and controlled current source are decreased when compared with the traditional flyback converter. Furthermore, appropriate parameter selection of the resonant circuit network can increase the equivalent impedance in the EMI coupling path in the low frequency range, which further reduces the common mode interference. Finally, a simulation model and a 60W experimental prototype of the proposed converter are built and tested. Experimental results verify the theoretical analysis.

Seismic Response of Seismically-Isolated Nuclear Power Plants considering Age-related Degradation of High Damping Rubber Bearing (고감쇠고무 적층받침의 경년열화를 고려한 원전구조물의 지진응답)

  • Park, Junhee;Choun, Young-Sun;Choi, In-Kil
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.26 no.2
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    • pp.131-138
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    • 2013
  • The high damping rubber bearings contributed to reduce a seismic force transmitted to upper structures, the material properties of rubber changes with time and the rubber with age-related degradation can affect the seismic response of structures and equipments. Therefore the seismic response of structure considering age-related degradation of isolators should be evaluated. In this paper, the stiffness and damping for isolators were defined using the aging data proposed by other researchers. The reactor containment building and the auxiliary building were selected to conduct the nonlinear analysis and the natural frequency, maximum responses, floor response spectrum(FRS) were evaluated with time using the four earthquakes with different frequency contents. According to the analysis results, the seismic responses are increased by the age-related degradation of isolators and the detail inspections should be conducted up to 20 years because it was presented that the change of FRS was high during this period.

Characteristic Analysis of Inductive Power Transfer System for PRT (소형궤도 열차용 유도 전력 전송 시스템 특성해석)

  • Min, Byung-Hun;Lee, Byung-Song
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.3
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    • pp.35-43
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    • 2007
  • In this paper, the inductive power collector using electromagnetic induction for vehicle such as the PRT(Personal Rapid Transit) system is suggested and son ideas for power collector design to improve tile power transfer performance are presented. And also, the analysis of the inductive power transfer system in conjunction with series resonant converter operating variable high frequency is shown. Of particular interest is the sensitivity of the complete system to variations in operational frequency and parameters. In inductive power transfer system electrical power is transferred from a primary winding in the form of a coil or tract to one or more isolated pick-up coils that my relative to the primary. The ability to transmit power without contact enables high reliability and easy maintenance that allows inductive power transfer system to be implemented in hostile environments. This technology has found application in many fields such as electric vehicles, PRT(Personal Rapid Transit) etc. But, low output power is generated due to a loosely coupled characteristic of the large air-gap. Therefore, we will show you various characteristic of inductive power transfer system as double layer construction of secondary winding, which was divided in half to increase both output current and output voltage, a model of power collector and parallel winding structure, a model of concentration/ decentralization winding and the effects of parameter and operational frequency variation.