• Clinical and Experimental Reproductive Medicine
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• v.49 no.1
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• pp.33-39
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• 2022

Objective: Male genital tract infections have been associated with infertility, and Escherichia coli has drawn increasing attention as an important bacterium in this context. This investigation aimed to characterize and compare the distributions of O-antigen serogroups of E. coli in the semen samples of fertile and infertile men. Methods: In this case-control study, semen samples were collected from 618 fertile and 1,535 infertile men. The E. coli-positive samples were evaluated in terms of concentration, morphology, viability, and motility parameters according to the World Health Organization 2010 guidelines. Finally, different serogroups of E. coli were identified by multiplex polymerase chain reaction targeting the O-antigen variations of the bacterium. Results: The prevalence of E. coli among fertile men was significantly higher than among infertile men (p<0.001). The sperm morphology, viability, and motility in the E. coli-positive fertile group were significantly higher than in the E. coli-positive infertile group (p<0.001). E. coli O6 was the most prevalent serogroup found in both groups. However, there was no significant difference in the frequency of different serogroups of E. coil between the two groups (p=0.55). Conclusion: Despite the higher prevalence of E. coli among fertile men, E. coli had more detrimental effects on semen parameters in infertile men. There was no significant difference in E. coli serogroups between the fertile and infertile groups.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.502-507
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• 2016

This study was conducted to develop novel antimicrobial nano-composites, with the aim of fully utilizing antimicrobial properties of multi-walled carbon nanotubes (MWCNTs), nickel (Ni) and zinc oxide (ZnO). Ni coated-MWCNTs (Ni-CNT) were prepared and evaluated for their potential application as an antimicrobial material for inactivating bacteria. Field emission scanning electron microscopy (FE-SEM), and X-ray energy dispersive spectroscopy (EDS) were used to characterize the Ni coating and morphology of Ni-CNT. Staphylococcus aureus (S. aureus) and Escherichia coil (E. coil) were employed as the target bacterium on antimicrobial activities. Comparing with the nitric acid treated MWCNTs and Ni-CNT which have been previously reported to possess antimicrobial activity towards S. aureus and E. coil, Ni-CNT/ZnO exhibited a stronger antimicrobial ability. The nickel coating was confirmed to play an important role in the bactericidal action of Ni-CNTs/ZnO composites. Also, the addition of ZnO to the developed nanocomposite is suggested to improve the antimicrobial property.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.84-91
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• 2001

In in vitro cell experiments for the biological assessment of electromagnetic (EM) field, exposure system (ES) must be analyzed in terms of current density (J) and induced electric field intensity (E). Although in uniform B field, E and J in the sample medium are not distributed uniformly because of conductivity in sample dish. Thus, the precise estimation for E and J induced by uniform ELF within sample media is very important keys for successful in in vitro experiments. In this paper, we designed in vitro ELF ES with electromagnetic analysis using MATLAB simulator. Then we calculated from the measured B field to verify induced E & J distribution for random locations of cells within media in two cases of samples existence or not. ES with B field ranging from 0 to 20G consists of Helmholz coil and current generator based on the microprocessor. Also, we developed ELFES for each B field generation as uniform and non-uniform modes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.9
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• pp.883-891
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• 2013

In wireless smart phone charging scenario, the transmitter pad is larger than the size of the receiver pad. Thus, it is important to supply a constant power to the receiver regardless of its location. In this paper, we propose a new method to regulate the receiver's power by adjusting a drain bias of class E power amplifier. The proposed LF-band wireless power transfer system is as follows: a buck converter power supply which is controlled by a pulse width modulation(PWM) IC TL494, a class E amplifier using a low cost IRF510 power MOSFET, a transmitter coil whose dimension is $16cm{\times}18cm$, a receiver coil whose dimension is $6cm{\times}8cm$, and a full bridge rectifier using Schottky diodes. A measured performance show a maximum output power of 4 W and system efficiency of 67 % if we fix the bias voltage. If we adjust the bias voltage, the received power can be maintained at a constant power of 2 W regardless of receiver pad location.

• Journal of Microbiology
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• v.43 no.5
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• pp.391-397
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• 2005

Escherichia coli is a common inhabitant of the intestinal tracts of animals and humans. The intestines of animals also represent an ideal environment for the selection and transfer of antimicrobial resistance genes. The aim of this study was to investigate the resistance of E. coli isolated from chicken fecal samples to fluoroquinolones and to analyze the characterization of mutations in its gyrA and parC gene related resistance. One hundred and twenty-eight E. coil isolates showed a high resistance to ciprofloxacin (CIP; $60.2\%$), enrofloxacin (ENO; $73.4\%$) and norfloxacin (NOR; $60.2\%$). Missense mutation in gyrA was only found in the amino acid codons of Ser-83 or Asp-87. A high percentage of isolates ($60.2\%$) showed mutations at both amino acid codons. Missense mutation in parC was found in the amino acid codon of Ser-80 or Glu-84, and seven isolates showed mutations at both amino acid codons. Isolates with a single mutation in gyrA showed minimal inhibitory concentrations (MIC) for CIP (${\le}0.5\;to\;0.75{\mu}g/ml$), ENO (1 to $4{\mu}g/ml$) and NOR (0.75 to $4{\mu}g/ml$). These MIC were level compared to isolates with two mutations, one in gyrA and one in parC, and three mutations, one in gyrA and two in parC (CIP, ${\le}0.5\;to\;3{\mu}g/ml;\;ENO,\;2\;to\;32<{\mu}g/ml;\;NOR,\;1.5\;to\;6\;{\mu}g/ml$). However, the isolates with two mutation in gyrA regardless of whether there was a mutation in parC showed high MIC for the three fluoroquinolones (CIP, 0.75 to $32{\le}{\mu}g/ml;\;ENO,\;3\;to\;32{\le}{\mu}g/ml;\;NOR,\;3\;to\;32{\le}{\mu}g/ml$). Interestingly, although the E. coil used in this study was isolated from normal flora of chicken, not clinical specimens, a high percentage of isolates showed resistance to fluoroquinolones and possessed mutations at gyrA and parC associated with fluoroquinolone resistance.

• The korean journal of orthodontics
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• v.19 no.2
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• pp.25-34
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• 1989

This experiment was performed to study the effect of prostaglandin $E_2$ on tooth movement and root resorption in orthodontically treated cats. Twenty five cats were divided into five groups and closed coil springs delivered 80gm were stretched between upper canine and 3rd premolar. $10{\mu}g$ of $PGE_2$ was injected locally in the submucosal area of the upper right canine, while the left side served as a control and was injected saline 0.1ml. The distance between canine tip and central cusp tip of the 3rd premolar was measured. Scanning electron photomicrographs were made of the coronal half of the distal root surface of canines and cemental craterings were observed and quantified using point-counting volumetry. Data were analyzed by 2-way ANOVA and paired t-test. The results were as follows: 1. The rate of tooth movement of the $PGE_2$ side was increased, particularly at 1 day, compared with the control side. 2. The rate of tooth movement was minimum from 7 days to 10 days. 3. The resorption of root surface of the $PGE_2$ side was decreased from 4 days to 10 days, compared with the control side.

• Journal of Fisheries and Marine Sciences Education
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• v.15 no.2
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• pp.135-144
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• 2003

1. The appearance of fisheries animals and plants of investigation areas were fishes, 20 species; algae, 9 species; molluska, 6 species; arthropod, 12 species; echinoderm, 5 species by confirmed appearance species. 2. The C.P.U.E by trap(1pcs of trap) were 3.95 species and weight of 2,098g, mainly catching species are greenling and jacopever(94.16%). The C.P.U.E by long liner(long liner 1coil, 100pcs) were 11.7species and weight of 6,418g, It occupied jacopever(35.63%) greenling(20.78%), bastard halibut(20.31%). The C.P.U.E of appearance species gill net(ipcs of gill net) were 5.05species and weight of 3,050g, It occupied jacopever(39.63%) greenling(29.83%), bastard halibut(17.47%). 3. The results of comparative analysis and natural species and stocked species, in case of bastard halibut, jacopever species were occupied species(83.33~92%), weight(86.86~96%). The stocked species were occupied species of 8.00~16.67%, weight of 4.00~13.14%. Provided the stocked projets were enacted effectively in future. The density of dwelling of stocked species were increase. Also, it will be contribute to the increase of fishermens income.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.394-400
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• 1990

Maximization of productivity of recombinant cell fermentations requires consideration of the inverse relationship between the host cell growth rate and product formation rate. The problem of maximizing a weighted performance index was solved by using optimal control theory for recombinant E. coli fermentation. Concentration of a growth inhibitor was used as a control variable to manipulate the specific growth rate, and consequently the cloned-gene expression rate. Using a simple unstructured model to describe the main characteristics of this system, theoretical analysis showed that the optimal control profile results in an initial high growth rate phase followed by a low growth rate and high product formation rate phase. Numerical calculations were done to determine optimal switching times from the growth to the production stage for two representative cases corresponding to different dependency of the product formation rate on the growth rate. For the case when product formation rate is sensitive to the specific growth rate, the optimized operation yields about 60% increase in the final product concentration compared with a simple batch fermentation.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.851-855
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• 2006

The aim of this study was to investigate characteristics of formation of mixed oxidants and some aspects of the performance of electrochemical process as an alternative disinfection strategy for water purification. The study of electrochemical process has shown free chlorine to be produced, but smaller amounts of stronger oxidants, such as ozone, hydrogen peroxide and OH radicals, were also generated. The formation of ozone and hydrogen peroxide increased with increasing electric conductivity, but was limited at conductivities greater than 0.6 mS/cm. Also, formation of OH radical was enhanced as electric conductivity was increased to 0.9 mS/cm and The stead-state concentrations of OH radical were calculated at $1.1{\sim}6.4{\times}10^{-14}M$. Using E. coti, inactivation kinetic studies were performed. With the exception of free chlorine, the role of mixed oxidants, especially OH radical, was investigated for enhancement of the inactivation rate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.2
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• pp.156-164
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• 2005

A comparative analysis of an ice storage system has been performed on the operation cost for the four control strategies, i.e., chiller priority and chiller downstream, chiller priority and chiller upstream, storage priority and chiller upstream, storage priority and chiller downstream. Main components of the ice storage system are an ice-on-coil storage tank and a screw compressor chiller. With the simulation program, the operation cost has been evaluated from the economics of an ice storage system. It is found that the operation cost of the ice storage system is strongly dependent on the control strategy, i.e., chiller priority or storage priority, but less affected by the arrangement method, i.e., chiller upstream or chiller downstream. In case of the maximum load day, the control strategy with chiller priority and chiller upstream is supposed to obtain the reduction of operation cost. However, it is found that the control strategy with storage priority and chiller downstream is the best economical operation for most summer seasons except the maximum load day.