• Journal of Powder Materials
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• v.28 no.2
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• pp.143-149
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• 2021

In this study, (GaN)_1-x(ZnO)_x solid solution nanoparticles with a high zinc content are prepared by ultrasonic spray pyrolysis and subsequent nitridation. The structure and morphology of the samples are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The characterization results show a phase transition from the Zn and Ga-based oxides (ZnO or ZnGa₂O₄) to a (GaN)_1-x(ZnO)_x solid solution under an NH3 atmosphere. The effect of the precursor solution concentration and nitridation temperature on the final products are systematically investigated to obtain (GaN)_1-x(ZnO)_x nanoparticles with a high Zn concentration. It is confirmed that the powder synthesized from the solution in which the ratio of Zn and Ga was set to 0.8:0.2, as the initial precursor composition was composed of about 0.8-mole fraction of Zn, similar to the initially set one, through nitriding treatment at 700℃. Besides, the synthesized nanoparticles exhibited the typical XRD pattern of (GaN)_1-x(ZnO)_x, and a strong absorption of visible light with a bandgap energy of approximately 2.78 eV, confirming their potential use as a hydrogen production photocatalyst.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.2
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• pp.37-47
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• 2022

Purpose : We aimed to investigate the effects of nutritional foods on sarcopenia prevention and physical function among the elderly living in rural communities during the COVID-19 pandemic by providing customized nutrition. Methods : This study was conducted in the rural community of SCC. Participants (n=24, over age 65) were randomly assigned into a Protein group (n=12) and a Vitamin group (n=12). The protein group was given 23 g/d of protein (whey, soybean, BCAA) for 8 weeks and the Vitamin group 23 g/d of vitamin (B, C, D, E and mixed minerals such as calcium, magnesium, zinc) for 8 weeks. All participants had their body composition such as height, weight, skeletal muscle mass, body mass index, and body fat percentage, measured using bioelectrical impedance analysis (BIA) and physical function assessed using grip strength and the short physical performance battery (SPPB). Results : At the end of the intervention, there was a significant increase in skeletal muscle mass (p<.01) in the Protein group (p=.002, 4.92 %) compared to the baseline: it increased by 2.33 %. The Vitamin group had a significant increase in body fat percentage after the intervention (p=.001, 15.35 %) compared to the baseline: body fat percentage decreased by 4.49 %. There were no significant differences in left and right Grip strength/Weight, SPPB, 4-m gait speed, chair stand test, and sense of balance in both groups. Conclusion : The findings from this study suggest that 8 weeks of protein intake have a significant effect on skeletal muscle mass and body fat percentage. Protein intake helped promoting the health of the elderly in rural community during the COVID-19 pandemic. It will assist creating a foundation for providing customized nutrition for the elderly in rural community in the future.

• Composites Research
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• v.34 no.6
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• pp.357-372
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• 2021

The energy harvesting device is known to be promising as an alternative to solve the resource shortage caused by the depletion of petroleum resources. In order to overcome the limitations (environmental pollution and low mechanical properties) of piezoelectric elements capable of converting mechanical motion into electrical energy, many studies have been conducted on a polymer matrix-based composite piezoelectric energy harvesting device. In this paper, the output performance and related applications of the reported piezoelectric composites are reviewed based on the applied materials and processes. As for the piezoelectric fillers, zinc oxide, which is advantageous in terms of eco-friendliness, biocompatibility, and flexibility, as well as ceramic fillers based on lead zirconate titanate and barium titanate, were reviewed. The polymer matrix was classified into piezoelectric polymers composed of polyvinylidene fluoride and copolymers, and flexible polymers based on epoxy and polydimethylsiloxane, to discuss piezoelectric synergy of composite materials and improvement of piezoelectric output by high external force application, respectively. In addition, the effect of improving the conductivity or the mechanical properties of composite material by the application of a metal or carbon-based secondary filler on the output performance of the piezoelectric harvesting device was explained in terms of the structure of the composite material. Composite material-based piezoelectric harvesting devices, which can be applied to small electronic devices, smart sensors, and medicine with improved performance, can provide potential insights as a power source for wireless electronic devices expected to be encountered in future daily life.

• Journal of Environmental Health Sciences
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• v.48 no.4
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• pp.236-243
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• 2022

Background: In the case of multiple exposures to different types of heavy metals, such as the conditions faced by residents living near a smelter, it would be preferable to group hazardous substances with similar characteristics rather than individually related substances and evaluate the effects of each group on the human body. Objectives: The purpose of this study is to evaluate the utility of factor analysis in the assessment of health effects caused by exposure to two or more hazardous substances with similar characteristics, such as in the case of residents living near a smelter. Methods: Heavy metal concentration data for 572 people living in the vicinity of the Janghang smelter area were grouped based on several subfactors according to their characteristics using factor analysis. Using these factor scores as an independent variable, multiple regression analysis was performed on health effect markers. Results: Through factor analysis, three subfactors were extracted. Factor 1 contained copper and zinc in serum and revealed a common characteristic of the enzyme co-factor in the human body. Factor 2 involved urinary cadmium and arsenic, which are harmful metals related to kidney damage. Factor 3 encompassed blood mercury and lead, which are classified as related to cardiovascular disease. As a result of multiple linear regression analysis, it was found that using the factor index derived through factor analysis as an independent variable is more advantageous in assessing the relevance to health effects than when analyzing the two heavy metals by including them in a single regression model. Conclusions: The results of this study suggest that regression analysis linked with factor analysis is a good alternative in that it can simultaneously identify the effects of heavy metals with similar properties while overcoming multicollinearity that may occur in environmental epidemiologic studies on exposure to various types of heavy metals.

• Journal of Life Science
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• v.32 no.8
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• pp.611-621
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• 2022

Dimethyl sulfoxide (DMSO) is commonly used as control or vehicle solvent in preclinical research of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) due to its ability to dissolve lipophilic compounds and cross the blood brain barrier. However, the biochemical effects of DMSO on the outcomes of preclinical research are often overlooked. In the present study, we investigated whether the long-term oral administration of 5% DMSO affects the neurological, functional, and histological disease phenotype of the copper/zinc superoxide dismutase glycine 93 to alanine mutation (SOD1-G93A) mouse model of amyotrophic lateral sclerosis. SOD1-G93A transgenic mice showed shortened survival time and reduced motor function. We found that administration with DMSO led to increased mean survival time, reduced neurological scores, and improved motor performance tested using the rotarod and grip strength tests. On the other hand, DMSO treatment did not attenuate motor neuron loss in the spinal cord and denervation of neuromuscular junctions in the skeletal muscle. These results suggest that DMSO administration could improve the quality of life of the SOD1-G93A mouse model of ALS without affecting motor neuron denervation. In conclusion, the use of DMSO as control or vehicle solvent in preclinical research may affect the behavioral outcomes in the SOD1-G93A mouse model. The effect of the vehicle should be thoroughly considered when interpreting therapeutic efficacy of candidate drugs in preclinical research.

• Journal of Industrial Convergence
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• v.20 no.12
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• pp.79-85
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• 2022

Recently, a smartphone manufactured on a flexible substrate has been released as an electronic device, and research on a stretchable electronic device is in progress. In this paper, a silicon-based stretchable material is made and used as a substrate to implement and evaluate an optical sensor device using oxide semiconductor. To this end, a substrate that stretches well at room temperature was made using a silicone-based solution rubber, and the elongation of 350% of the material was confirmed, and optical properties such as reflectivity, transmittance, and absorbance were measured. Next, since the surface of these materials is hydrophobic, oxygen-based plasma surface treatment was performed to clean the surface and change the surface to hydrophilicity. After depositing an AZO-based oxide film with vacuum equipment, an Ag electrode was formed using a cotton swab or a metal mast to complete the photosensor. The optoelectronic device analyzed the change in current according to the voltage when light was irradiated and when it was not, and the photocurrent caused by light was observed. In addition, the effect of the optical sensor according to the folding was additionally tested using a bending machine. In the future, we plan to intensively study folding (bending) and stretching optical devices by forming stretchable semiconductor materials and electrodes on stretchable substrates.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.94-101
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• 2023

Zinc oxide(ZnO) is a semiconductor material with a bandgap of 3.37 eV and an exciton binding energy of 60 meV for various applications. Recently ZnO has been proven to enhance its electrical properties for utilization as an alternative for transparent conducting oxide (TCO) materials. In this study, cation(Al, Ga)-anion(F) single and double doped ZnO thin films were grown by atomic layer deposition (ALD) to enhance the electrical properties. The structural and optical properties of doped ZnO thin films were analyzed, and doping effects were confirmed to electrical characteristics. In single doped ZnO, it was observed that the carrier concentration was increased after doping, acting as a donor to ZnO. Among the single doping elements, F doped ZnO(FZO) showed the highest mobility and conductivity due to the passivation effect of oxygen vacancies. In the case of double doping, higher electrical characteristics were observed compared to single doping. Among the samples, Al-F doped ZnO(AFZO) exhibited the lowest resistance value. This results can be attributed to an increase in delocalized electron states and a decrease in lattice distortion resulting from the differences in ionic radius. The partial density of states(PDOS) was also analyzed and observed to be consistent with the experimental results.

• Journal of Nutrition and Health
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• v.57 no.2
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• pp.171-184
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• 2024

Purpose: Although activating thermogenic adipocytes is a promising strategy to reduce the risk of obesity and related metabolic disorders, emerging evidence suggests that it is difficult to induce adipocyte thermogenesis in obesity. Therefore, this study aimed to investigate the regulation of adipocyte thermogenesis in diet-induced obesity. Methods: Adipose progenitor cells were isolated from the white and brown adipose tissues of control diet (CD) or high-fat diet (HFD) fed mice, and fully differentiated white and brown adipocytes were treated with β-agonists or 18-carbon fatty acids for β-adrenergic activation or peroxisome proliferator-activated receptor (PPAR) activation. Results: Compared to the CD-fed mice, the expression of uncoupling protein 1 (Ucp1) was lower in the white adipose tissue of the HFD-fed mice; however, this was not observed in the brown adipose tissue. The expression of peroxisome proliferator-activated receptor gamma (Pparg) was lower in the brown adipose progenitor cells isolated from HFD-fed mice than in those isolated from the CD-fed mice. Norepinephrine (NE) treatment exerted lesser effect on peroxisome proliferator-activated receptor-γ coactivator (Pgc1a) upregulation in white adipocytes derived from HFD-fed mice than those derived from CD-fed mice. Regardless which 18-carbon fatty acids were treated, the expression levels of thermogenic genes including Ucp1, Pgc1a, and positive regulatory domain zinc finger region protein 16 (Prdm16) were higher in the white adipocytes derived from HFD-fed mice. Oleic acid (OLA) and γ-linolenic acid (GLA) upregulated Pgc1a expression in white adipocytes derived from HFD-fed mice. Brown adipocytes derived from HFD-fed mice had higher expression levels of Pgc1a and Prdm16 compared to their counterparts. Conclusion: These results indicate that diet-induced obesity may downregulate brown adipogenesis and NE-induced thermogenesis in white adipocytes. Also, HFD feeding may induce thermogenic gene expression in white and brown primary adipocytes, and OLA and GLA could augment the expression levels.

• The Korean Journal of Pharmacology
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• v.17 no.1 s.28
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• pp.17-25
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• 1981

No evidence has accumulated that lead compound is an essential component for biological function in animals. Lead is absorbed primarily through the epithelial mucosal cells in duodenum and the absorption can be enhanced by the substances which bind lead and increase its solubility. Iron, zinc and calcium ions, however, decrease the absorption of lead without affecting its solubility, probably by competing for shared absorptive receptors in the intestinal mucosa. Therefore, the absorption of lead is increased in iron deficient animals. Lead shows a strong affinity for ligands such as phosphate, cysteinyl and histidyl side chains of proteins, pterins and porphyrins. Hence lead can act on various active sites of enzymes, inhibiting the enzymes which has functional sulfhydryl groups. lead inhibits the activity of ${\delta}$-aminolevulinic acid dehydratase for the biosynthesis of hemoproteins and cytochrome, which catalyzed the synthesis of monopyrrole prophobilinogen from ${\delta}$-aminolevulinic acid. Accordingly lead decrease hepatic cytochrome p-450 content, resulting an inhibition of the activity of demethylase and hydroxylase in liver. Little informations are available on the effect of lead on digestive system although the catastrophic effects of lead intoxication are well documented. The present study was, therefore, attempted to investigate the effect of lead on pancreaticobiliary secretion in rats. Albino rats of both sexes weighing $170{\sim}230g$ were used for this study. The animals were divided into one control and three treated groups, i.e., control (physiologic saline 1.5ml/kg i.p.), lead acetate $(l0{\mu}mole/kg/day\;i.p.)$, $Pb(Ac)_2$ and EDTA$(each\;10{\mu}mole/kg/day\;i.p.)$, $Pb(Ac)_2$ and $FeSO_4(each\;l0{\mu}mole/kg/day\;hp)$. The pancreatico-biliary juice was collected under urethane anesthesia, and activities of amylase and lipase were determined by employing Sumner's and Cherry and Crandall's methods. The summarized results are follows. 1) In the experiment for acute toxicity of lead acetate, 20% of mortality was observed in rat treated with lead acetate as well as inhibition of the activity of amylase in the juice at the 3 rd day of the treatment. 2) No increases in body weight were observed in rats treated with lead acetate, while in control group the significant increases were observed. However, the body weights of animals were increased in the group lead acetate plus EDTA or $FeSO_4$. 3) Lead acetate decreased significantly the volume of pancreatico-biliary juice whereas additional treatment of EDTA and $FeSO_4$ prevented it. 4) Total activity of amylase was markedly reduced due to lead acetate treatment, but no change was showed following additional treatment with EDTA and $FeSO_4$. 5) No changes in the cholate and lipase output were observed in rats treated with lead acetate as compared with that of control rats. 6) Increase in bilirubin output in rats treated with lead acetate was shown on the 2nd and 3rd weeks treatment. 7) In the case of in vitro experiment, lead acetate also markedly inhibited release of amylase from pancreatic fragment. 8) Histologic finding indicated that acini vacuolation was induced in the pancreatic tissue of rat treated with lead acete. From the above results, it might be concluded that lead acetate decreases the volume of pancreatico-biliary secretion and inhibits the amylase activity, by acting directly on pancreatic cells.

• Korean Journal of Poultry Science
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• v.35 no.3
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• pp.303-311
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• 2008

This study was conducted to investigate the effect of dietary supplementation of Cu-methionine chelate(Cu-Met) and Cu-soy proteinate(Cu-SP) on the performance, small intestinal microflora and immune response in laying hens. A total of 960 Hy-line $Brown^{(R)}$ laying hens of 39 wks old were assigned to one of the following 6 dietary treatment: control(C), antibiotic(Avilamycine 6 ppm), Cu-Met 50 and Cu-Met 100(50 and 100 ppm Cu as Cu-methionine chelate), Cu-SP 50 and Cu-SP 100(50 and 100ppm Cu as Cu-soy proteinate). Each treatment was replicated 4 times with forty birds per replication, housed in 2 birds per cages. Forty birds units were arranged according to randomized block design. Feeding trial lasted 6 wks under 16 hours lighting regimen. Hen-day and hen-house egg production of groups treated with Antibiotic and Cu supplements tended to be higher than the control with significant difference (P<0.05) shown between Cu-Me 100 and control. Egg weight was significantly (P<0.05) heavier in antibiotic and Cu-SP treatments than Cu-Met treatments but they were not significantly different from the control. Eggshell strength, egg shell thickness, egg yolk color and Haugh unit were not significantly different among treatments. There were no significant differences in leukocytes and erythrocytes in the chicken blood. But mean corpuscular hemoglobin value(MCH) was significantly (P<0.05) higher in Cu-SP 100 than antibiotic treatment. The concentrations of serum IgG and IgA were not significantly different among treatments. Copper concentration in the liver tended to increase as the level of copper supplementation increased, that of Cu-SP 100 being significantly (P<0.05) higher than those of the control and antibiotic treatment. Concentrations of iron and zinc of the liver were not significantly influenced by treatments. Populations of Cl. perfringens and Lactobacilli in the small intestinal content were significantly (P<0.05) influenced by treatments. Population of Cl. perfringens decreased and that of Lactobacilli increased in the copper supplemented groups. The result of this experiment showed that Cu-Met and Cu-SP are comparable to antibiotic in improving egg production in laying hens. Birds fed diets supplemented with Cu-SP produced heavier eggs than those fed diets with Cu-Met. There were no significant differences in the performances between 50 ppm and 100 ppm copper supplementation as organic forms.