• Journal of Powder Materials
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• v.30 no.5
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• pp.436-441
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• 2023

Molybdenum-tungsten (Mo-W) alloy sputtering targets are widely utilized in fields like electronics, nanotechnology, sensors, and as gate electrodes for TFT-LCDs, owing to their superior properties such as high-temperature stability, low thermal expansion coefficient, electrical conductivity, and corrosion resistance. To achieve optimal performance in application, these targets' purity, relative density, and grain size of these targets must becarefully controlled. We utilized nanopowders, prepared via the Pechini method, to obtain uniform and fine powders, then carried out spark plasma sintering (SPS) to densify these powders. Our studies revealed that the sintered compacts made from these nanopowders exhibited outstanding features, such as a high relative density of more than 99%, consistent grain size of 3.43 ㎛, and shape, absence of preferred orientation.

• The Korean Journal of Food And Nutrition
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• v.28 no.3
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• pp.478-485
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• 2015

This study was conducted to investigate the effects of ramie leaf powder on the quality characteristics of pork patties. The moisture, crude protein, crude fat, and crude ash in freeze-dried ramie leaf powder were found to be 4.67% (w/w), 25.61% (w/w), 6.66% (w/w), and 16.88% (w/w), respectively. Pork patties were prepared by adding varying amounts of ramie leaf powders up to 1.5% (w/w) of the pork patty formulation. The moisture contents of meat patties containing ramie leaf powder were lower than that of the control patty, but there was no significant difference in pH values between the patties. With increasing amounts of ramie leaf powder, chromaticity decreased in brightness ($L^*$) and redness ($a^*$), but increased in yellowness ($b^*$) in the raw patties. In texture analysis, hardness, springiness, cohesiveness, and chewiness of the pork patties increased as more ramie leaf powder was added to the pork patties. Thiobarbituric acid reactive substances (TBARS) values increased during storage in pork patties without ramie leaf powder, but those formulated with ramie leaf powder showed lower TBARS values than those in the control groups. Sensory panels determined that pork patties containing 0.5% ramie leaf powder had higher scores for overall acceptability.

• Journal of Nutrition and Health
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• v.34 no.3
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• pp.271-284
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• 2001

This study was performed to investigate the effects of dried powders and water extracts of Paecilomyces tenuipes(P. tenuipes) and Cordyceps militaris(C. militaris) on lipid metabolism, lipid peroxidation and antioxidative capacity and immune status in rats. Thirty-five male Sprague-Dawley rats weighting 195$\pm$21g were grouped into five according to body weight. Ratw were raised for four weeks with diet containing either 4%, 2%(w/w) of dried P. tenuipes powders(TP-4, TP-2) or water extracts from equal amounts of each 4% P. tenuipes and C. militaris powder(TE-4, ME-4). Food intake, weight gain of all groups were not significantly different from those of control group. Lipid metabolism in general was not significantly different among all the groups. However both dried P. tenuipes powder lowered plasma cholesterol level slightly, water extract groups showed tendency of higher plasma HDL-cholesterol and lower liver cholesterol levels than control. Plasma and liver thiobarbituric acid reactive substance(TBARS) concentrations of all the experimental groups were lower than control group. Red blood cell(RBC) and liver superoxide dismutase(SOD) activities were not generally different among all groups. Liver xanthine oxidase(XOD) activities of all groups were tended to be lower than control group. Proliferation of aplenocytes induced by mitogens, concanavalin A and lipopolysaccharide, were increased in TP-2 group. The TP-4 group showed increased CD8 T cells and MHC class II expression without changes in CD4 T cells, B cells and G/M ratio, suggesting activated cytotoxic T cell activity in vivo. Increase of G/M ratio but not of MHC class II in TP-2 group indicated the possible acute inflammatory reaction by the ingested substances in gastrointestinal tract. ME-4 group showed enhanced cellular immunity without vigorous changes of immune parameters in brief periods. In conclusion, both P. tenuipes and C. militaris stimulated antioxidant capacity and immune status in rats. Among groups, water extract of C. militaris was most effective in both capacities, though dried powder of P. tenuipes at 2% dietary level was more effective in antioxidant activity, as various results by different strains were observed.(Korean J Nutrition 34(3) : 271~284, 2001)

• Journal of Nutrition and Health
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• v.37 no.8
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• pp.633-644
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• 2004

This study was performed to investigate effect of dried powders and ethanol extracts of garlic flesh and peel on antioxidative capacity in 16-month- old rats. Forty Sprague-Dawley male rats weighing 618.1$\pm$6.5g were blocked into five groups according to body weight and raised for 3 months with experimental diets containing 5% (w/w) of dried powders of garlic flesh or peel, or ethanol extracts from equal amount of each dried powder. Total polyphenols, flavonoids, /3 -carotene, vitamin C, vitamin E, and total antioxidant status (TAS) levels were determined in garlic preparations. Thiobarbituric acid reactive substances (TBARS) levels in plasma, liver and VLDL + LDL fraction, oxidative DNA damage (8-hydroxy-2' -deoxyguanosine, 80HdG) in kidney, xanthine oxidase (XO) activities in plasma and liver, superoxide dismutase (SOD) activities in erythrocyte and liver, and carotenoid concentration, and total antioxidant status (TAS) in plasma were measured. Total polyphenols and flavonoids contents in garlic preparations were highest in peel ethanol extract. Vitamin C content was not different significantly among preparations, but peel powder contains slightly more vitamin C. The content of $\beta$-carotene was highest in peel ethanol extract and vitmain E content was highest in flesh ethanol extract. The highest level of TAS was observed in peel ethanol extract. Plasma TBARS levels in all the experimental groups were found to be significantly lower than control group, and TBARS concentration in VLDL + LDL fraction was decreased in all the experimental groups in comparison to control group. Also levels of 80HdG in kidney in experimental groups were lower than that of control group. Plasma and liver XO activities were. decreased in all experimental groups, and erythrocyte and liver SOD activities were higher in experimental groups compared to control group. All experimental groups also showed higher plasma TAS levels than control group. Especially, garlic flesh powder group was significantly lower in plasma and liver XO activities, and significantly higher in erythrocyte and liver SOD activities than control group. Moreover, plasma TBARS level and kidney 8OHdG level were decreased in flesh powder group. In conclusion, garlic diets showed effect of improving antioxidative capacity in 16-month old rats, especially, garlic flesh powder was prominent in inhibiting XO activity, promoting SOD activity and decreasing kidney 8OHdG level among experimental groups.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1051-1053
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• 1995

Nowadays perovskite $La_{1-x}Sr_xMnO_3$ is preferred cathode material in Solid Oxide Fuel cell(SOFC). The $La_{1-x}Sr_xMnO_3$ with Sr contents ranging $x=0{\sim}1.0$ were prepared by a citrate method. These powders were characterized by usual means like TG/DTA, X-ray diffraction analysis. The samples used for measuring thermal expansion were prepared as pellets by cold pressing and subsequent sintering in air at $1200^{\circ}C$ for 5 hours. To measure the by-product of $La_{1-x}Sr_xMnO_3$ reacted with 8mol% YSZ, that samples were sintered at $1200^{\circ}C$ for 5 hours.

• Tribology and Lubricants
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• v.13 no.4
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• pp.60-65
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• 1997

The tungsten disulfide $(WS_2)$ solid lubricant was synthesized by two different reaction processes, i.e., the reaction between $CS_2$ gas phase and solid $WO_3$powder, and the vapour phase transport method of tungsten and sulfur in a high vacuum. The chemical and physical characteristics of synthesized $WS_2$powder were analyzed in terms of the average particle size, morphology, crystalline phase etc. in comparison with those of commercial $WS_2$powder. The solid $WO_3$ powder with the average size of 0.2 ${\mu}{\textrm}{m}$ was reacted with $CS_2$gas flowed with$N_2$or 96%$N_2{\times}4%H_2$forming gas for 36 h and 24 h at 90$0^{\circ}C$ respectively. $WS_2$ crystalline phase was then formed through the intermediate phase of .$W_{20}O_{58}$ In the case of vapour phase transport method, the 3.5 wt% iodine was added as a vapour transport reagent into the composition of tungsten and sulfur powders maintaining a constant molar ratio of W:S=1:2.2. The mixture was then heat treated at 85$0^{\circ}C$ for 2 weeks in vacuum. The reaction product obtained showed the average size of 12 ${\mu}{\textrm}{m}$ and the hexagonal plate shape of typical solid lubricant with 2H-$WS_2$crystalline phase.

• Korean journal of food and cookery science
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• v.26 no.6
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• pp.821-830
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• 2010

This study was carried out to investigate the quality characteristics and storage of wet noodle with added Cheonnyuncho powder. Wet noodles were prepared at concentration of 1, 3, and 5%(w/w) of the fruit based on flour weight. Moisture content of the noodles with or without Cheonnyuncho powder was 34~36%. Ca, K, Mg, Fe, Mn and Zn contents of Cheonnyuncho noodle were increased at increasing concentrations of Cheonnyuncho powder. Cooked weight, volume, and water absorption decreased with increased fruit powder, whereas turbidity increased. For hunter's color values of noodles, L(lightness) and b(yellowness) values decreased with increasing concentration of Cheonnyuncho powder, whereas a(redness) value increased. For mechanical characteristics of the noodles, adhesiveness, cohesiveness, chewiness, elasticity, and brittleness of cooked noodle with Cheonnyuncho powder were lower than those of control. The pH of Cheonnyuncho noodle was lower than that of control during storage. Bacterial counts of wet noodle with 1% and 3% fruit powders were lower than those of the control and 5% fruit powder on the 8th day of storage at $5^{\circ}C$. From the sensory evaluation, texture, taste, and overall preference were not significantly different between the control and fruit group, but the color of 5% Cheonnyuncho noodle was significantly higher than that of control (p<0.05). In conclusion, the results of this study suggest that the addition of 1% and 3% Cheonnyuncho powder in combination with flour tended to improve antimicrobial effects during storage when compared to control.

• Macromolecular Research
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• v.8 no.5
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• pp.231-237
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• 2000

The polymerization of 3-ethynylphenol, phenylacetylene having hydroxy functionality, was carried out by tungsten and molybdenum-based transition metal catalysts. The polymerization proceeded to give a moderate yield of polymer. The effects on the mole ratio of monomer to catalyst (M/C), initial monomer concentration ((Mb), and the polymerization temperature for the polymerization of 3-ethynylphenol were investigated. The catalytic activity of W-based catalysts was found to be greater than that of Mo-based catalysts. The resulting polymers were brown or black powders and mostly insoluble in organic solvents. Structural analysis of the polymer by instrumental methods revealed the conjugated polymer backbone structure carrying hydroxyphenyl moieties. Thermal and morphological properties of the resulting poly(3-ethynylphenol) were also discussed.

• Korean Journal of Materials Research
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• v.21 no.9
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• pp.520-524
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• 2011

Porous W with controlled pore characteristics was fabricated by a freeze-drying process. $WO_3$ powder and camphene were used as the source materials of W and sublimable vehicles, respectively. Camphene slurries with $WO_3$ contents of 10 and 15 vol% were prepared by milling at $50^{\circ}C$ with a small amount of oligomeric polyester dispersant. Freezing of a slurry was done in a Teflon cylinder attached to a copper bottom plate cooled at $-25^{\circ}C$ while the growth direction of the camphene was unidirectionally controlled. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at $800^{\circ}C$ for 30 min and sintered in a furnace at $900^{\circ}C$ for 1 h under a hydrogen atmosphere. Microstructural observation revealed that all of the sintered samples were composed of only W phase and showed large pores which were aligned parallel to the camphene growth direction. The porosity and pore size increased with increasing camphene content. The difference in the pore characteristics depending on the slurry concentration may be explained by the degree of powder rearrangement in the slurry. The results strongly suggest that a porous metal with the required pore characteristics can be successfully fabricated by a freeze-drying process using metal oxide powders.

• Journal of Powder Materials
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• v.19 no.6
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• pp.446-450
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• 2012

In order to fabricate the porous Mo with controlled pore characteristics, unique processing by using $MoO_3$ powder as the source and camphene as the sublimable material is introduced. Camphene-based 15 vol% $MoO_3$ slurries, prepared by milling at $50^{\circ}C$ with a small amount of dispersant, were frozen at $-25^{\circ}C$. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at $750^{\circ}C$, and sintered at $1000-1100^{\circ}C$ for 1 h. After heat treatment in hydrogen atmosphere, $MoO_3$ powders were completely converted to metallic W without any reaction phases. The sintered samples showed large pores with the size of about $150{\mu}m$ which were aligned parallel to the camphene growth direction. Also, the internal wall of large pores and near bottom part of specimen had relatively small pores due to the difference in the camphene growth rate during freezing process. The size of small pores was decreased with increase in sintering temperature, while that of large pores was unchanged. The results are strongly suggested that the porous metal with required pore characteristics can be successfully fabricated by freeze-drying process using metal oxide powders.