• Food Science of Animal Resources
• /
• v.38 no.1
• /
• pp.172-179
• /
• 2018

One of the critical limitations to use of bacteriocins produced by lactic acid bacteria as a substitute for chemical antibiotics is the narrow spectrum of their antibacterial activity. The aim of present study was isolation and molecular identification of bacteriocin-producing enterococci with broad antibacterial spectrum. Bacteriocin-producing bacteria were isolated from native dairies in Kerman. Bacteriocins were purified by ammonium sulfate method and the effects of them were investigated on different strains of bacteria. Also, the effects of pH and heat on produced bacteriocins were investigated. High level bacteriocin-producing isolates were identified based on molecular tests. A total of 15 strains of bacteriocin-producing Enterococcus were isolated initially. Enterococcus faecium C-2 and Y-1 strains produced bacteriocins with the highest antibacterial effect. The bacteriocins were stable in pH ranges from 2 to 12 and their antibacterial activity was maintained after autoclave treatment. The maximum bactericidal effect was observed against Listeria monocytogenes and Pseudomonas aeruginosa. In conclusion, use of these bacteriocins as a substitute for chemical antibiotics is recommended.

• Earthquakes and Structures
• /
• v.12 no.1
• /
• pp.35-45
• /
• 2017

The current paper investigates the effect of the seismic pounding of neighboring buildings on the response of structures isolated by Triple Friction Pendulum Bearing (TFPB). To this end, a symmetric three-dimensional single story building is modeled for analysis with two specified levels of top deck and base deck, to capture the seismic response of the base isolators and building's roof. Linear elastic springs with different level of gaps are employed to calculate the impact between the buildings. Nonlinear Dynamic Time History Analyses (NDTHA) are conducted for seismic evaluation. Also, five different sizes with four different sets of friction coefficients are assumed for base isolators to cover a whole range of base isolation systems with various geometry configurations and fundamental period. The results are investigated in terms of base shear, buildings' drift and top deck acceleration of the superstructure. The results also indicate the profound effect of the stiffness of the adjacent buildings on the value of the impact they impose to the superstructure. Also, in situations of potential pounding, the increment of the fundamental period of the TFPB base isolator could intensify the impact force up to nearly five-fold.

• Earthquakes and Structures
• /
• v.10 no.6
• /
• pp.1451-1465
• /
• 2016

The effectiveness of base isolation (BI) systems for mitigation of seismic vibration of bridges have been extensively studied in the past. It is well established in those studies that the performance of BI system is largely dependent on the characteristics of isolator yield strength. For optimum design of such systems, normally a standard nonlinear optimization problem is formulated to minimize the maximum response of the structure, referred as Stochastic Structural Optimization (SSO). The SSO of BI system is usually performed with reference to a problem of unconstrained optimization without imposing any restriction on the maximum isolator displacement. In this regard it is important to note that the isolator displacement should not be arbitrarily large to fulfil the serviceability requirements and to avoid the possibility of pounding to the adjacent units. The present study is intended to incorporate the effect of excessive isolator displacement in optimizing BI system to control seismic vibration effect of bridges. In doing so, the necessary stochastic response of the isolated bridge needs to be optimized is obtained in the framework of statistical linearization of the related nonlinear random vibration problem. A simply supported bridge is taken up to elucidate the effect of constraint condition on optimum design and overall performance of the isolated bridge compared to that of obtained by the conventional unconstrained optimization approach.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.25 no.3
• /
• pp.519-522
• /
• 1996

From the leaves of Lindera sericea Bl., kaempferol-3,7-0-di-a-L-rhamnopyranoside was isolated and characterized by spectral data and acid hydrolysis. This compound is reported for the first time from this plant. The content of kaempferol glycoside was high in May and June, and low in the fall. And the methoanolic extract of title plant showed the inhibitory effect on carrageenin-induced edema.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.908-912
• /
• 2008

Structure-borne noise is known to dominate internal running noise levels in open field. In this paper vibration isolation characteristics of floors are investigated to see their effect on the internal running noise. By using the analysis and test results of test specimen of small size, internal running noise level of complete train is estimated. Analysis results show that soft rubber as a vibration isolator has the most favorable effect on the inside running noise.

• Journal of Life Science
• /
• v.22 no.9
• /
• pp.1180-1186
• /
• 2012

The purpose of this study was to investigate the effect of exercise preconditioning (EPC) on nerve growth factor (NGF), synapsin I, and choline acetyltransferase (ChAT) in the hippocampus of rats subjected to social isolation (SI). We randomly assigned four groups of male Sprague-Dawley (SD) rats (n=32) to the following treatments: GC: group housing control; IC: isolation control; GE: group housing exercise; IE: isolation exercise (n=8 each group). The rats underwent EPC 5 days a week for 8 weeks, and the speed of the treadmill was gradually increased (grade $0^{\circ}C$). After EPC, they were immediately subjected to SI for 8 weeks. The results showed that the protein levels of NGF, synapsin I, and ChAT in the hippocampus were significantly decreased in the IC group (p<0.05) compared with the GC group. However, these protein levels were significantly higher in the IE group (p<0.05). These results show that EPC may buffer the decline of function in the hippocampus by ameliorating the reduction in NGF, synapsin I, and ChAT induced by SI.

• Journal of Korean Society of Forest Science
• /
• v.73 no.1
• /
• pp.33-42
• /
• 1986

This study was carried out to investigate the optimum conditions for isolation and culture of mesophyll protoplasts from Populus alba ${\times}$ P. glandulosa. The results obtained from the experiments are as follows; 1) The suitable concentration of BAP for shoot multiplication was 0.4 mg/l. 2) High yield and viability of isolated protoplasts were obtained by our high enzyme-short time incubation method. 3) Optimum enzyme concentrations for mesophyll protoplast isolation were Cellulase 2%, Macerozyme 0.8%, Hemicellulase 1.2%, Driselase 2%, and Pectolyase Y-23 0.05%. 4) 0.6M mannitol in enzyme solution was the most effective for protoplast isolation and viability. 5) The most adequate pH level of enzyme solution was pH 5.6. 6) The effect of DTT and MES buffer was significant. 7) For protoplast purification, 0.6M sucrose was the most proper concentration. 8) The adding effect of Dextran T40 in floating solution was important. 9) The mesophyll protoplasts isolated through our high enzyme-short time incubation method revealed successful response to culture condition over 3 weeks of culture.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2010.10a
• /
• pp.65-70
• /
• 2010

This paper presents experimental performance evaluation of a magnetorheological (MR) damper for integrated isolation mount for ultra-precision manufacturing system. The vibration sources of the ultra-precision manufacturing system can be classified as follows: the one is the environmental vibration from the floor and the other is the transient vibration occurred from stage moving. The transient vibration occurred from the stage moving has serious adverse effect to the process because the vibration scale is quite larger than other vibrations. Therefore in this research, a semi-active MR damper, which can control the transient vibration, is adopted. Also the stage needs to be isolated from tiny vibrations from the floor. For this purpose, a dry-frictionless MR damper is required. In order to achieve this goal, a novel type of MR damper is originally designed and manufactured in this work. Subsequently, the damping force characteristics of MR damper are evaluated by simulation and experiment. In addition, the vibration control performance of the MR damper associated with the stage mass is evaluated.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.21 no.5
• /
• pp.434-441
• /
• 2016

This paper deals with transformer turns ratio design with the consideration of loss minimization in isolated bidirectional DC-DC converter. Generally, the rms value of current, magnitude of current at switching instance, and duty ratio of a converter vary according to the turns ratio of an isolation transformer in the converter under the same voltages and output power level. Therefore, the transformer turns ratio has an effect on the total loss in a converter. The switching and conduction losses of IGBTs and MOSFETs consisting of dual-active bridge converter are analyzed, and iron and copper losses in an isolation transformer and inductor are calculated. Total losses are calculated and measured in cases of four different transformer turns ratios through simulation and experiment with 3-kW converter, and an optimum turns ratio that provides minimum losses is found. The usefulness of the proposed transformer turns ratio design approach is verified through simulation and experimental results.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.30 no.7 s.250
• /
• pp.707-714
• /
• 2006

A numerical analysis study has performed in terms of fluid dynamics to identify the wall thinning generated in the main feedwater isolation valve body of a nuclear power plant. To review the relations between flow characteristics and the wall thinning induced by flow accelerated corrosion (FAC), numerical analysis using FLUENT code and ultrasonic tests (UT) were performed. The local velocities according to the analysis results were compared with the distribution of the measured wall thickness by ultrasonic tests. The comparison results show that the local velocity in the x-direction had no correlation with the wall thinning but the local velocity in the y-direction and turbulence intensity had a great influence on that. These results provide a good match to those of the previous studies - locations colliding vertically against components undergo severe wall thinning. These results may be utilized to the design modification and the wall thinning management for main feedwater isolation valves for preventing the wall thinning degradation.