• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.161-170
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• 2012

There are many factors to consider when attempting to improve the efficiency of fuel cell operation, such as the operation temperature, humidity, stoichiometry, operation pressure, geometric features, etc. In this paper, the effects of the operation pressure were investigated to find the current density and water saturation behavior on a cross section designated by the design geometry. A two-dimensional geometric model was established with a gas channel that can provide $H_2$ to the anode and $O_2$ and water vapor to the cathode gas diffusion layer (GDL). The results from this numerical modeling revealed that higher operation pressures would produce a higher current density than lower ones, and the water saturation behavior was different at operation pressures of 2 atm and 3 atm in the cathode GDL. In particular, the water saturation ratios are higher directly below the collector than in other areas. In addition, this paper presents the dependence of the velocity behavior in the cathode on pressure changes, and the velocity fluctuations through the GDL are higher in the output area than in inlet area. This conclusion will be utilized to design more efficient fuel cell modeling of real fuel cell operation.

• Journal of fish pathology
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• v.27 no.1
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• pp.17-24
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• 2014

To study the possible use of probiotics in fish farming, The in vitro and in vivo antibacterial effects of Pseudomonas aeruginosa MB I-3 (MB I-3) against the fish pathogenic bacterium Listonella anguillarum were evaluated. The inhibitory effects of MB I-3 against vibrios were investigated by the double layer method and the co-culture. The results showed that MB I-3 inhibited the growth of pathogenic vibrios including Listonella anguillarum, Vibrio alginolyticus, Vibrio cholerae, Vibrio fluvialis, Vibrio furnissii, Vibrio harveyi, Vibrio parahaemolyticus and Vibrio vulnificus. Extracellular substances obtained from the cultural supernatant of MB I-3 by ethyl acetate extraction showed inhibitory effects on L. anguillarum. The antibacterial substance of MB I-3 was evaluated to destroy the cell membrane of L. anguillarum in electron micrographs. The probiotic effects of MB I-3 was tested by exposing olive flounder (Paralichthys olivaceus) fry to L. anguillarum with or without MB I-3. The cumulative mortality of olive flounder fry infected with L. anguillarum was 24% in the group with MB I-3, while it was 46% in the control group without MB I-3. These results indicate that MB I-3 has potential applications as a probiotic for the control of fish pathogenic vibrios in fish rearing system.

• Clinical and Experimental Reproductive Medicine
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• v.29 no.2
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• pp.105-115
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• 2002

Objective : To evaluate the effects of the reactive oxygen species (ROS) generated with a xanthine (X) and xanthine oxidase (XO) system on sperm function, the change of sperm characteristics, lipid peroxidation, and DNA fragmentation in bovine spermatozoa. Materials and Methods: ROS were produced using a combination of 1000 uM X and 50 mU/ml XO. The ROS scavengers: superoxide dismu tase (SOD) (200 U/ml) and catalase (500 U/ml) were also tested. Spermatozoa were incubated for 2 hours in BWW medium with a combination of X-XO supplemented with or without ROS scavengers at $37^{circ}C$ under 5% $CO_2$ incubator. Sperm movement characteristics by CASA (computer-aided sperm analysis), HOST (hypoosmotic swelling test), Caionophore induced acrosome reaction, malondialdehyde formation for the analysis of lipid peroxidation, the percentage of DNA fragmentation using the method of TdT-mediated nick end labelling (TUNEL) by flow cytometry were determined after 2 hours incubation. Results: The action of ROS on bovine spermatozoa resulted in a decreased in capacity for sperm motility, Ca-ionophore induced acrosome reaction and membrane integrity, an increased in malondialdehyde formation and the percentage of sperm with DNA fragmentation. In the effects of antioxidant, catalase completely alleviated the toxic effects induced by the ROS in terms of sperm function and characteristics, however SOD exhibited no capacity to reduce the toxic effects. Conclusion: The ROS can induce significant damages to sperm functions and characteristics. The useful ROS scavengers can minimized the defects of sperm function and various damages of spermatozoa.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.153-157
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• 2017

Gel type internal electrolytes were synthesized by varying hydroxyethyl-cellulose (HEC) amounts and their durability and conductivity were measured. The ionic conductivity decreased as the content of HEC increased thus the internal electrolyte containing more than 12% of HEC could not be used as a reference electrode. Based on durability test results, as the HEC amount decreased carrier density resulting in increasing of the amount of KCl coming out of the porous membrane. Therefore in order to use long time at ballast water treatment systems, we selected 10% HEC for gel type internal electrolyte. The resolution test for total residual oxidants (TRO) was carried out using the TRO sensor and the gel type reference electrode made of 10% HEC. A 50 mV potential was applied to the TRO sensor for 30 sec and changes in the current were measured. It was confirmed that the TRO concentrations ranging from 0 to 15 mg/L could be separated at salinity conditions of 0.2~30 PSU. The results indicated that the TRO concentration at sea water and at fresh water was successfully measured by the TRO sensor constructed with the reference electrode using gel-type internal electrolyte of HEC.

• Applied Microscopy
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• v.25 no.4
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• pp.52-61
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• 1995

Ultrastructural characteristics were examined with leaves of three species, O. japonicus A. Berger, O. malacophyllus Fisch., and O. sikokianus Owhi that probably have CAM mode. The mesophyll cells of these Orostachys possessed vacuoles with precipitates, myelin-like figures, and plasmalemmasomes, along with typical chloroplasts, microbodies and darkly stained bodies in their thin peripheral cytoplasm. Separation of the plasmalemma from the cell wall, leaving a space between them, was a common phenomenon in these species. A complex array of small to large vacuoles which contain small, membrane-bounded vesicles or vacuole-like structures were frequently found. A well-developed thylakoid system was observed in the chloroplasts and this indicates that the photosynthetic capacity of these mesophyll cells is probably active. A peculiar configuration of cytoplasm, especially around the chloroplasts, was also encountered. The variety of cytoplasmic constituents and vacuoles suggest the water-storing mesophyll cells may be complex in function. Some cellular features detected in this study strongly suggest the possible occurrence of CAM mode in Orostachys species.

• Tuberculosis and Respiratory Diseases
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• v.75 no.4
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• pp.140-149
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• 2013

Background: Plasminogen activator inhibitor type 1 (PAI-1), an important regulator of plasminogen activator system which controls degradation of extracellular membrane and progression of tumor cells, and PAI-1 gene polymorphic variants have been known as the prognostic biomarkers of non-small cell lung cancer patients. Recently, experimental in vitro study revealed that transforming growth factor-${\beta}1$ initiated PAI-1 transcription through epithelial growth factor receptor (EGFR) signaling pathway. However, there is little clinical evidence on the association between PAI-1 A15T gene polymorphism and prognosis of Korean population with pulmonary adenocarcinoma and the influence of activating mutation of EGFR kinase domain. Methods: We retrospectively reviewed the medical records of 171 patients who were diagnosed with pulmonary adenocarcinoma and undergone EGFR mutation analysis from 1995 through 2009. Results: In all patients with pulmonary adenocarcinoma, there was no significant association between PAI-1 A15T polymorphic variants and prognosis for overall survival. However, further subgroup analysis showed that the group with AG/AA genotype had a shorter 3-year survival time than the group with GG genotype in patients with EGFR mutant-type pulmonary adenocarcinoma (mean survival time, 24.9 months vs. 32.5 months, respectively; p=0.015). In multivariate analysis of 3-year survival for patients with pulmonary adenocarcinoma harboring mutant-type EGFR, the AG/AA genotype carriers had poorer prognosis than the GG genotype carriers (hazard ratio, 7.729; 95% confidence interval, 1.414-42.250; p=0.018). Conclusion: According to our study of Korean population with pulmonary adenocarcinoma, AG/AA genotype of PAI-1 A15T would be a significant predictor of poor short-term survival in patients with pulmonary adenocarcinoma harboring mutant-type EGFR.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.11
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• pp.1824-1836
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• 2020

Objective: On the hypothesis that grazing of cattle prompts organs to secrete or internalize circulating microRNAs (c-miRNAs) in parallel with changes in energy metabolism, we aimed to clarify biological events in adipose, skeletal muscle, and liver tissues in grazing Japanese Shorthorn (JSH) steers by a transcriptomic approach. Methods: The subcutaneous fat (SCF), biceps femoris muscle (BFM), and liver in JSH steers after three months of grazing or housing were analyzed using microarray and quantitative polymerase chain reaction (qPCR), followed by gene ontology (GO) and functional annotation analyses. Results: The results of transcriptomics indicated that SCF was highly responsive to grazing compared to BFM and liver tissues. The 'Exosome', 'Carbohydrate metabolism' and 'Lipid metabolism' were extracted as the relevant GO terms in SCF and BFM, and/or liver from the >1.5-fold-altered mRNAs in grazing steers. The qPCR analyses showed a trend of upregulated gene expression related to exosome secretion and internalization (charged multivesicular body protein 4A, vacuolar protein sorting-associated protein 4B, vesicle associated membrane protein 7, caveolin 1) in the BFM and SCF, as well as upregulation of lipolysis-associated mRNAs (carnitine palmitoyltransferase 1A, hormone-sensitive lipase, perilipin 1, adipose triglyceride lipase, fatty acid binding protein 4) and most of the microRNAs (miRNAs) in SCF. Moreover, gene expression related to fatty acid uptake and inter-organ signaling (solute carrier family 27 member 4 and angiopoietin-like 4) was upregulated in BFM, suggesting activation of SCF-BFM organ crosstalk for energy metabolism. Meanwhile, expression of plasma exosomal miR-16a, miR-19b, miR-21-5p, and miR-142-5p was reduced. According to bioinformatic analyses, the c-miRNA target genes are associated with the terms 'Endosome', 'Caveola', 'Endocytosis', 'Carbohydrate metabolism', and with pathways related to environmental information processing and the endocrine system. Conclusion: Exosome and fatty acid metabolism-related gene expression was altered in SCF of grazing cattle, which could be regulated by miRNA such as miR-142-5p. These changes occurred coordinately in both the SCF and BFM, suggesting involvement of exosome in the SCF-BFM organ crosstalk to modulate energy metabolism.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.56-61
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• 2011

Alkyl vinyl ethers such as methyl vinyl ether, propyl vinyl ether, isopropyl vinyl ether, butyl vinyl ether and isobutyl vinyl ether are usually used as industrial solvents and chemical intermediates in the chemical or pharmaceutical industry. Recently, they are popularly used as raw materials for polymer electrolyte membrane fuel cells and as cellulose dyeing assistants. However, very few investigations about process design and operation data were reported for alkyl vinyl ether compounds and there are no data for propyl vinyl ether(PVE) systems as far as we know. In this work, the isothermal VLE data are reported at 333.15 K for the ternary systems of {PVE + ethanol + benzene} by using headspace gas chromatography(HSGC) and these VLE data were correlated using Wilson, NRTL and UNIQUAC equations. The excess volumes($V^E$) and deviations in molar refractivity(${\Delta}R$) data are also reported for the sub binary systems {PVE + ethanol}, {ethanol + benzene} and {PVE + benzene} at 303.15 K. These data were correlated with Redlich-Kister equation. In addition, isoclines of $V^E$ and DR for ternary system {PVE + ethanol + benzene} were also calculated from Radojkovi equation.

• The Korean Journal of Pain
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• v.7 no.2
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• pp.162-169
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• 1994

Blockade of cervicothoracic sympathetic ganglion (stellate ganglion controls pain on face, head, neck, shoulder, upper limbs, and upper chest, including their viscera and sympathetically maintained pain. This procedure also increases blood flow to the above areas and relieves hyperreactivity of sympathetic nervous system. Clinically, repeated stellate ganglion blocks with local anesthetic agent may become difficult with complications such as accidental intravascular or subdural injection, recurrent laryngeal nerve or bracheal plexus paralysis, pneumothorax and edema on injection site. Therefore, at times long-term cervicothoracic ganglion block with neurolytics is necessitated but its applications are prohibited by the critical structures surrounding ganglion. There are also few reports of neurolytic stellate ganglion block. This study was performed to observe the complications, gross changes of surrounding structures, and microscopic findings of ganglion cells after neurolytic block and to certify the possibility of clinical use of neruolytic stellate ganglion block. The unilateral superior cervical sympathetic ganglion of rabbit was blocked with absolute ethyl alcohol 0.4 ml at the level of cricoid cartilage. Normal ganglion was used as a control and 5 animals were sacrificed at each intervals of 7, 15 and 50 days after block. The results were as follows; 1) All experimental animals showed no specific changes of behavior, motor function. No necrotic tissues were present in the block area during the observation period. There were some gross scar tissues along the fascia of muscles surrounding the needle injection site, but gross atrophy of muscles or injured major vessels were not found. 2) Microscopically, structures of normal ganglion of rabbit were very similar to those of humans. Seven days after absolute ethyl achohol injection there were marked edema of ganglion cells and nuclei with irregular nuclear membrane. Some of the ganglion cells lost their nuclei and showed degenerative changes. Fifteen days after block, cell edema were decreased and loss of the Nissl's body was prominant. The ganglion cell structures looked close to normal but the cytoplasm and nucleus were generally contracted 50 days after block. These results suggest absolute ethyl alcohol injection on cervical sympathetic ganglion with above method mainly blocks pre- and post-synaptic fibers and the long-term neurolytic blockade of this ganglion may be possible in rabbits.

• Journal of Biomedical Engineering Research
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• v.23 no.6
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• pp.467-475
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• 2002

Hyperthermia using transrectal thermal probes has been used for a noninvasive treatment of prostate diseases. However it is known that heating the rectal wall at excessively high temperature can lead to destruction of the rectal mucous membrane. and it is difficult to maintain an optimum temperature over the entire prostate. Thus, a more accurate understanding of the heat transfer mechanism between prostate and hyperthermia system is needed Numerical analysis was performed to investigate how the cold/warm stimulations on the prostate surface affect the temperature distribution in the prostate model. The general purpose software "FLUENT" was used for obtaining a finite volume solution to the unsteady conduction equation and to calculate the time-varying temperature in the prostate. Effects of the warm/cold stimulations and the stimulation frequency on the temperature distribution were simulated. and we visualized how hyperthermia affected the inside of the prostate. It was found that the effect of hyperthermia by using a typical heating method is limited due to the low thermal conductivity of the prostate. Consecutive repetitions of warm and cold stimulations were considered to provide the thermal irritations inside a prostate. The effects of temperature difference and duration of warm/cold stimulations were investigated, and basic data for the optimum period and effective patterns of stimulations were obtained. A simplified bioheat equation was also solved to describe effects of the blood flow on the blood-tissue heat transfer. The effect of blood flow was not dominant compared to that of warm/cold stimulations. These results might be used as data for design of prostate treating probe, prostatic therapy and thermal stimulation effects on the prostate.