• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.5
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• pp.149-155
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• 2024

Gallium, a key material in TFT (Thin-Film Transistor) targets and LED (Light Emitting Diode), is highly sought after due to its scarcity, making the recovering and recycling from waste resources. This study develops a process to recover high-purity gallium contained in an alkaline electrolyte and to produce gallium oxide nanopowder for IGZO (Indium Gallium Zinc Oxide) targets. Through an investigation of the electrowinning process conditions, the effects of various process factors and the optimal conditions are identified. It is found that the concentration of NaOH significantly affects purity. By employing two rounds of electrowinning followed by acid washing, gallium with a purity of over 99.995 % is successfully recovered. Using this recovered gallium as a starting material, gallium oxide is produced via a gas-phase synthesis. It is observed that while higher temperatures increase the yield, the purity decreases. Ultimately, at 1,260℃, gallium oxide nanopowder with a purity exceeding 99.995 % is obtained with a yield close to 90 %. The gallium oxide nanopowder predominantly exhibits a size of approximately 2 ㎛ and a spherical shape, suggesting favorable characteristics for subsequent processes such as sintering.

• Korean Journal of Food Science and Technology
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• v.32 no.4
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• pp.843-850
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• 2000

We have produced the microcapsule composed of ${\alpha}-tocopherol$ as a core material (Cm) and the gelatinized polysaccharide as a wall material (Wm). Firstly, we have developed a simple, sensitive, and quantitative analysis method of the microencapsulation product using 5% cupric acetate pyridine solution. We could then optimize all the conditions for the microencapsulation process such as the ratio of [Cm] to [Wm], the temperature of dispersion fluid, and the emulsifier concentration using response surface methodology (RSM). As for the microencapsulation of ${\alpha}-tocopherol$, the regression model equation for the yield of microencapsulation (YM, %) to the change of an independent variable could be predicted as follows : YM=99.77-1.76([Cm]:[Wm])-1.72$([Cm]\;:\;[Wm])^2$. From the ridge of maximum response, the optimum conditions for the microencapsulation of ${\alpha}-tocopherol$ were able to be determined as the ratio of [Cm] to [Wm] of 4.6:5.4(w/w), the emulsifier concentration of 0.49%, and dispersion fluid temperature of $25.5^{\circ}C$, respectively. Finally, the microcapsules produced under the optimal conditions were applied for the analysis of storage stability. The optimal conditions for the storage were found to be the values of pH 9.0 and $25{\sim}35^{\circ}C$. And the storage stability of the microcapsules containing ${\alpha}-tocopherol$ were higher than 99% for a week at pH 9.0 and $25^{\circ}C$.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.768-774
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• 2009

To improve the productivity of 1,3-propanediol(1,3-PD) with K. pneumoniae DSM4799 using pure glycerol and crude glycerol derived from the biodiesel process, optimizing fermentation conditions was performed by changing environmental factors such as anaerobic/aerobic condition, temperature, glycerol concentration, and pH. When anaerobic conditions were maintained, there was an improved 1,3-PD production compared with that from aerobic/anaerobic 2-stage fermentation. From the results with temperature $26{\sim}37^{\circ}C$, the higher 1,3-PD production yield was observed at $30{\sim}33^{\circ}C$. For an initial glycerol concentration higher than 60 g/L, cell growth and 1,3-PD production were inhibited. When crude glycerol was used, the initial 1,3-PD production appeared to be inhibited. After 48 hr of incubation, however, 1,3-PD production with crude glycerol was even higher than that with pure glycerol, demonstrating the feasibility of 1,3-PD production using crude glycerol as a substrate. Fed-batch fermentation was applied for the high concentration of 1,3-PD without substrate inhibition. By regulating pH at 7 during the fed-batch with glycerol lower than 40 g/L, the yield of 1,3-PD was 25% higher than that without pH regulation(0.56 g/g vs. 0.45 g/g). In conclusion, based on our results, anaerobic conditions, temperature at $30^{\circ}C$, pure or crude glycerol lower than 40 g/L, and pH regulation at 7 were the optimized conditions for 1,3-PD production using K. pneumoniae DSM4799, making it more feasible to produce 1,3-PD at higher concentration and a lower price.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.547-559
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• 1994

To effectively utilize fish skin wastes from marine manufactory, the optimal extraction conditions to prepare gelatin from fish skins of Alaska pollack, cod and yellowfin sole were investigated. In addition, the physical properties of the fish skin gelatins prepared under the optimal extraction conditions were compared with the commercial animal skin gelatin. The conditions for extraction of gelatins from fish skins were as follows ; The skins were limed with 1.0~1.5%(w/v) calcium hydroxide solution. The fish skin gelatins were extracted with 6~7 volumes of water(pH 6.0~7.0) for 5hrs at $40{\sim}50^{\circ}C$, and the yield of Alaska pollack skin gelatin extracted under the above conditions was higher than those of cod and yellowfin sole skins. The heavy metal contents, jelly strength and electric conductivities of fish skin gelatins were lower than those of a commercial gelatin(bovine skin), but the viscosity and isoelectric point were higher. The amount of amino acid in fish skin, such as gelatin, glutamic acid, serine, threonine, methionine and cysteine, were higher than those in pig and ox skin. However, the contents of hydroxyproline and proline were lower.

• Journal of Applied Biological Chemistry
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• v.63 no.1
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• pp.111-116
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• 2020

Total polyphenol contents, flavonoid contents, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activities of ethanol extracts of 20 herbal plants (sage, turmeric, mace, bayleaf, fenugreek, oregano, blackpepper, whitepepper, clove, marjoram, cinnamon, coriander, basil, dillseed, mustard, cadamon, thyme, celery, rosemary, cumin) were analyzed for the screening of high flavonoid-containing plant resource. Thyme extract, showing the highest flavonoid content and a high degree of antioxidant activity, was selected as a bioactive cosmetic material. The total polyphenols and flavonoids contents of thyme extracts were measured as 6.90 mg chlorogenic acid equivalent (CAE)/100 g and 1.71 mg naringin equivalent (NE)/100 g, respectively, and DPPH radical scavenging activities was 90%. Among the tested organic solvents, hexane gave the highest extraction yield. Thus hexane was selected as the most suitable solvent for the extraction of thyme. Response surface method was used to obtain optimized extraction conditions for thyme: reaction temperature of 35.9 ℃, raw material to hexane ratio of 1.63:25 (w/v), and reaction time of 192 min. These predicted extraction conditions was validated by a total flavonoid extraction experiment showing a value equivalent to 96.3% of the predicted total flavonoid content. It is expected that the optimized solvent extraction conditions could be used for the production of flavonoid using thyme.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.1-8
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• 2000

Fifty-seven extracts from flower, leaf and stem of Agastache rugosa O. Kuntze were prepared by varing extraction conditions: solvents (hot water, ethanol and NaCl solution); temp.$(60,\;80\;and\;100^{\circ}C)$ and solvent ratios (10 to 35 times per material). Lipid content of leaf was 9.54% and protein content of the flower where the essential amino acids were most abundant among all parts was 16.8%. Among six minerals (Na. Ca, Fe, P, K and Mg) detected from all parts of the plant, the content of K was the highest. Extraction yield rated higher in odor of water, ethanol and NaCl solution, respectively and the extractions reached eqilibrium in about 15 to 20 min, regardless of extraction conditions. pH values of all extracted solvents maintained neutral upon extraction and a few free sugars in forms of glucose and fructose were detected from ethanol extracts. Colors and organoleptic characteristics of the extracts which determine the properties of final products varied with extraction conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.246-268
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• 2019

Soybean [Glycine max (L.) Merr.] is a species of legume native to East Asia. The interactions between climatic conditions and genetic characteristics are known to affect the agricultural performance of soybean. Therefore, the present investigation was conducted to identify the main elements affecting the agricultural performances of 11 soybean varieties/lines from China [Harbin ($45^{\circ}12^{\prime}N$), Yanji ($42^{\circ}53^{\prime}N$), Dalian ($39^{\circ}30^{\prime}N$), Qingdao ($36^{\circ}26^{\prime}N$)] and the Republic of Korea [Suwon ($37^{\circ}16^{\prime}N$), and Jeonju ($35^{\circ}49^{\prime}N$)]. The days to flowering (DTF) of soybeans with the e1-nf and e1-as alleles and the E1e2e3e4 genotype, except in 'Keumgangkong', 'Tawonkong', and 'Duyoukong', were relatively short compared to those of soybeans with other alleles. Although DTF of the soybeans was highly correlated with all climatic conditions [negative: precipitation, average temperature (AVT), accumulated temperature; positive: day-length (DL)], days to maturity and 100-seed weight of the soybeans showed no significant correlation with any climatic conditions. The soybeans with a dominant Dt1 allele, except 'Tawonkong', had the longest stem length (STL). Moreover, STL of the soybeans grown in the test fields showed a positive correlation with only DL; however, the results of our chamber test that was conducted to complement the field tests showed that STL of soybean was positively affected by AVT and DL. Although soybean yield (YLD) showed positive correlations with latitude and DL (except L62-667, OT89-5, and OT89-6), the response of YLD to the climatic conditions was cultivar-specific. Our results show that DTF and STL of soybeans grown in six different latitudes are highly affected by DL, and AVT and genetic characteristic also affect DTF and STL.

• Korean Journal of Environmental Biology
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• v.42 no.3
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• pp.325-331
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• 2024

Among the different types of seaweed that are cultivated in Korea for food, Capsosiphon fulvescensis the filamentous green alga with the highest production value. However, its harvest yield varies significantly from year to year due to its dependence on the natural seeding method. The present study aimed to identify the conditions affecting the formation of cyst-zygotes that can be utilized as artificial seeds during the life cycle of C. fulvescens. Gametangia and zygotes of C. fulvescens were found to be highly developed at temperatures above 15℃, with a maximum gametangial development rate of about 35% observed after 7 days of culture. The formation of zygotes into cystzygotes was induced within 7 days in all temperature conditions, but after 30 days of culturing, cyst-zygotes germinated into filamentous thalli at temperatures above 20℃, while the most stable formation and stabilization were observed at 15℃. Cystzygotes formed at 15℃ showed high growth when they were transferred to 25℃ conditions, and zoospores matured inside the cells. The production of cyst-zygotes was mostly influenced by temperature, and a gradual increase in temperature was found to be necessary for the formation and growth of cyst-zygotes. The culture conditions facilitating the formation of cyst-zygotes reported in this study can be useful for the production of artificial seeds and breeding technology for the effective cultivation of seaweed.

• Journal of Animal Science and Technology
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• v.56 no.4
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• pp.13.1-13.5
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• 2014

The production performance of multiparous lactating Sahiwal cows (n = 24) was evaluated according to both milking frequency and method. Selected animals were randomly divided into four groups containing six animals each under a completely randomized design. Cows in groups A & B were milked by the hand milking method three times per day, respectively. Similarly, cows in groups C & D were milked by the machine milking method two and three times per day, respectively. All animals were maintained under uniform feeding and management conditions. Dry matter intake was high in animal groups milked three times per day, and it remained unchanged between the hand and machine milking methods. Milk yield was higher (P < 0.05) in cows milked three times compared to those milked twice per day, and it did not differ between hand and machine milking methods. Milk fat percentage was higher (P < 0.05) in cows milked twice per day compared to those milked three times using both machine and hand milking methods. The percentage of total solids showed a similar pattern as the fat percentage. However, percentages of protein, lactose, and non-fat solids in milk were not significantly different (P > 0.05) among the treatment groups. Collectively, the results show that milking three times per day instead of twice at 8-hour intervals can enhance milk yield in Sahiwal cows using both hand and machine milking methods.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.3
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• pp.340-346
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• 2010

Buffaloes usually maintain higher body condition and do not produce milk at the cost of their own body reserves under tropical conditions. The mobilization of body reserves for fulfilling the demands of lactation has been extensively studied in dairy cows while limited work is available on this aspect in dairy buffaloes. Therefore, the present study was conducted to examine variations in milk fatty acid profiles with body condition in Nili-Ravi buffaloes. A total of 24 Nili-Ravi buffaloes within 60 days after parturition, were selected from a private dairy farm in the district of Peshawar. All animals consumed the same diet during the experimental period. A total of 576 raw milk samples were collected for laboratory analysis. The study continued up to 6 months during 2008. Body condition score (BCS), milk yield and composition were recorded once a week. Means for milk fatty acid profile were compared for various levels of BCS. The mean milk yield and fat content were 9.28 kg/d and 5.36%, respectively. The total saturated fatty acids (SFA) were 64.22 g/100 g and the unsaturated fatty acids (UFA) were 35.79 g/100 g. Of the SFA the highest amount was recorded for $C_{16:0}$, followed by $C_{18:0}$, and $C_{14:0}$. The total sum of hypercholesterolemic fatty acids (HCFA, $C_{12:0}$, $C_{14:0}$ and $C_{16:0}$) was 43.33 g/100 g. The concentrations of UFA were greater for moderate BCS followed by poor and highest BCS while SFA showed the opposite trend. The correlation analysis showed that milk yield was negatively affected by BCS and milk fat positively affected, though non-significantly. The present study suggests that Nili-Ravi dairy buffaloes produce similar milk to dairy cows regarding availability of cardioprotective fatty acids, with the highest concentration of $C_{18:1\;cis-9}$. Two HCFA ($C_{12:0}$ and $C_{14:0}$) were associated with higher body condition. Buffaloes with moderate body condition yielded milk containing healthier fatty acids.