• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.54-59
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• 2009

It was difficult for the existing rotary kiln to fabricate the fine aggregates under 3 mm due to the sticking phenomenon between specimens. In this study, the vertical type fluidizing furnace was designed and manufactured by which the lightweight fine aggregates of specific gravity $1.1{\sim}1.7$, water absorption $11{\sim}19%$ could be fabricated from the green body of clay: stone sludge: spent bleaching clay = 60 : 30 : 10 (wt%) without sticking-together happening. The minimum sintering temperature for bloating of aggregates was $1130^{\circ}C$. The specimens sintered over $1140^{\circ}C$ showed the typical bloating characteristics of lightweight aggregates and an inner layer was discovered due to widened cracks on a surface. But the crack on a surface did not propagate into a black core area so had no effect on a water absorption of aggregates. The sintering temperature made the thickness of shell and the black core area thin and expanded respectively but the sintering time did not affect the microsturcture of aggregates. The water absorption of aggregates decreased with increasing temperature owing to increased amount of liquid formed on a surface. Also sintering time affected a lot on a water absorption because it takes a time to form a liquid, which change the open pores to closed pores by blocking.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.3
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• pp.59-68
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• 2013

The cotton contains various impurities such as protein, wax, pectins, coloring matter, even though cotton has been a major source of pure cellulose. The purification processes have been commonly applied to obtain the pure cellulose. However the excessive purification treatments could lead to the damage in the cellulose structure which could result in the degradation of cellulose and the limited application of cotton cellulose. In this study, the changes in cellulose structural properties such as crystallinity and DP(degree of polymerization) by the various conditions of the purification processes were investigated. The less toxic agents such as hydrogen peroxide and sodium silicate were applied for the purification treatment in this study. The increase in the process times, the temperature and the applied amount of chemical agents resulted in the more purified cellulose. The DP of cotton cellulose was increased at the first weak conditions by the reduction of small molecules such as pectin, wax, and so on. Especially the 2 % addition amount of $H_2O_2$ with $Na_2SiO_3$ resulted in the higher value in the DP and the brightness compared to the 1.5 % addition amount of $H_2O_2$. However, the 4 % addition amount of $H_2O_2$ with $Na_2SiO_3$ showed the decreased value because of excessive treatment. In case of the changes in the crystallinity (Gjk), the highest value of the crystallinity was obtained by the 2% addition amount of $H_2O_2$ on the cotton cellulose, which showed similar with the change in the DP.

• Journal of Microbiology and Biotechnology
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• v.27 no.10
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• pp.1783-1789
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• 2017

Thermostability is an important property of xylanase because high temperature is required for its applications, such as wood pulp bleaching, baking, and animal feedstuff processing. In this study, XynB from Thermobacillus composti, a moderately thermophilic gram-negative bacterium, was modified via site-directed mutagenesis (based on its 3D structure) to obtain thermostable xylanase, and the properties of this enzyme were analyzed. Results revealed that the half-life of xylanase at $65^{\circ}C$ increased from 10 to 50 min after a disulfide bridge was introduced between the ${\alpha}$-helix and its adjacent ${\beta}$-sheet at S98 and N145. Further mutation at the side of A153E named XynB-CE in the C-terminal of this ${\alpha}$-helix enhanced the half-life of xylanase for 60 min at $65^{\circ}C$. Therefore, the mutant may be utilized for industrial applications.

• Journal of Microbiology and Biotechnology
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• v.25 no.9
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• pp.1476-1484
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• 2015

Three endoxylanase-encoding genes from the moderately themophilic chemoorganotrophic bacterium Melioribacter roseus were cloned and expressed in Escherichia coli. Genes xyl2091 (Mros_2091) and xyl2495 (Mros_2495) encode GH10 family hydrolases, whereas xyl2090 (Mros_2090) represents the GH30 family. In addition to catalytic domains, Xyl2090 and Xyl2091 contain carbohydrate-binding modules that could facilitate their binding to xylans and Por sorting domains associated with the sorting of proteins from the periplasm to the outer membrane, where they are covalently attached. Recombinant endoxylanase Xyl2495 exhibited a high specific activity of 1,920 U/mg on birchwood xylan at 40℃. It is active at low temperatures, exhibiting more than 30% of the maximal activity even at 0℃. Endoxylanases Xyl2090 and Xyl2091 have lower specific activities but higher temperature optima at 80℃ and 65℃, respectively. Analysis of xylan hydrolysis products revealed that Xyl2090 generates xylo-oligosaccharides longer than xylopentaose. Xylose and xylobiose are the major products of xylan hydrolysis by the recombinant Xyl2091 and Xyl2495. No activity against cellulose was observed for all enzymes. The presence of three xylanases ensures efficient xylan hydrolysis by M. roseus. The highly processive "free" endoxylanase Xyl2495 could hydrolyze xylan under moderate temperatures. Xylan hydrolysis at elevated temperatures could be accomplished by concerted action of two cell-bound xylanases; Xyl2090 that probably degrades xylans to long xylo-oligosaccharides, and Xyl2091 hydrolyzing them to xylose and xylobiose. The new endoxylanases could be useful for saccharification of lignocellulosic biomass in biofuels production, bleaching of paper pulp, and obtaining low molecular weight xylooligosaccharides.

• Applied Microscopy
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• v.38 no.1
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• pp.35-41
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• 2008

Onions are commonly available and easily processed, and since their skins are thrown away they could be very useful materials from the viewpoint of environmental preservation. This study aimed to process onion skins into the state of powder and look into the optimum condition for hair dyeing by decoloring virgin hair four times and observing the hair dyeing quality and its mechanical and morphologic changes by the different condition of onion skins in duration, temperature, density, pH, and mordant treatment. The observations of hair surface through scanning microscopy showed the formation of cuticle layer, though in a little blown-up state in the case of the hair dyed with onion skin application, when compared with bleaching hair with the completely dissolved cuticle layer. According to the above findings of experiments, the dyeing quality of the hair dyes with onion skin application was excellent, the dyeing was also feasible without mordants, and the use of Fe as the mordant increased dyeing exhaustion more, which would make it an effective hair dye. These results of the experiments indicate that the natural pigment extracted from onion skins can be actually used for hair dyeing from the viewpoints of the dyeing quality and the skin treatment.

• Journal of Environmental Health Sciences
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• v.36 no.4
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• pp.337-341
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• 2010

The modified simultaneous differential staining technique, which enables double staining of cartilage and bones, needs to be improved to prevent soft tissues from being damaged during the staining process. Key factors influencing the extent to which soft tissues are damaged include the fixative used, macerating time, potassium hydroxide concentration, incubation temperature and the removal of skin from specimens. Here we describe a protocol that enables the hardening of tissues during bleaching and maceration. We also describe a method for objectively measuring rates of cartilage and bone growth. The use of formalin as a fixative rendered soft tissues more rigid due to the resulting chemical bonds formed between proteins. Blotted specimens were immersed in 1% potassium hydroxide (KOH) and incubated at $37^{\circ}C$ for 1 day (smaller specimens) or 2-3 days (larger specimens). The 1% KOH solution was also used as the diluent solution for the subsequent immersion in a graded series of 30%, 50%, 70%, 90%, 100% glycerol solutions, a procedure that made soft tissues even more transparent and hardened. It was not necessary to remove the skin of specimens shorter than 2 cm, since the macerating solution could easily penetrate their thin skin layer and continuously remove those pigments hindering visibility. Since excessive osmosis is another factor that can damage soft tissues in the macerating process by causing the rupture of those cells not able to withstand the osmotic pressure, here it was minimized by balancing the salt concentration between the interior and exterior of cells with the addition of 0.9% sodium chloride (NaCl) in the macerating solution. Finally, to determine the proportions of cartilage and bone growth, photographs of the stained specimens were taken with a dissecting microscope and sections corresponding to the cartilage and bones were cut out from the printed pictures and weighed. Our results show that this method is suitable for the objective evaluation of bone and cartilage growth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.4
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• pp.225-231
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• 1988

As the studies on effective utilization of polyunsaturated lipids in sardine (Sardinops melanosticta), the conditions of deacidification, decoloring, and deodorization for processing of refined sardine oil were investigated In the process of refining, phosphoric acid treatment was not effective in removing phosphatides, and optimal condition to neutralize the crude sardine ill was treating for 30min at $40^{\circ}C$. with $0.5\%$ excess of 3M NaOH solution. Decoloring was optimized by adding $5\%$ bleaching earth and treating for 20min at $50^{\circ}C$ under vacuum, and deodorizing was done by steam destillation at $180^{\circ}C$ under 3 torr of vacuum. When deodorizing temperature exceeded $200^{\circ}C$, some changes occured in fatty acid composition and artifacts were appeared on GLC chromatogram.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.715-721
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• 2004

Many food protein hydrolysates have been shown to have antioxidant activities, and recent research focuses on low molecular peptides produced during hydrolysis of food protein. Korean rice wine contains about 60-70% of protein at dry base and originates from raw materials. It has been suggested that the protein is transformed into low molecular weight peptides, and have antioxidant activity during fermentation. The objectives of this study were to evaluate the antioxidant activity of the pre-purified and purified peptides found in Korean rice wine and to identify the responsible peptides. The wine extract of Samhaeju, a traditional Korean rice wine made by low temperature fermentation, was evaporated at $35^{\circ}C$. The two methods employed in the evaluation of antioxidant activity were the DPPH radical scavenging method and the beta-carotene bleaching test. The pre-purified samples showed 808 AAC (Antioxidant Activity Coefficient) and 56.5% AOA (Antioxidant Activity), which were higher than $\alpha$-tocopherol (572 AAC and 78% AOA). The rice wine extract was separated by reversed-phase HPLC. The protective effect of the four most antioxidant active fractions were tested for t-butyl hydroperoxide induced oxidation of healthy human erythrocytes and the byproduct was determined by malondialdehyde formation. Fraction No.5 showed 35% lower MDA concentration as compared to the control. The peptides were further purified using consecutive chromatographic methods and 4 antioxidant peptides were isolated. The amino acid sequences of the peptides were identified as Ile-His-His, Val- Val-His(Asn), Leu-Val-Pro, and Leu(Val)-Lys-Arg-Pro. The AAC value of the synthetic form of the identified peptides was the highest for Ile-His-His.

• Journal of the Korean Wood Science and Technology
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• v.16 no.4
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• pp.70-78
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• 1988

To separate and utilize the main components of hardwood (Quercus mongolica) by organosov pulping (ester pulping), chips were cooked at various conditions such as; the solvent ratio (acetic acid: ethylacetate: water, 50:25:25; 33:33:34; 25:50:25), maximum temperature (165, 170, $175^{\circ}C$), and cooking times (2, 2.5, 3 hr). The pulps were bleached by the sequences of CEDED, C/DEDED, PEDED. Lignin, sugars, and acetic acid were separated from black liquor and washing liquors. 1. The selective delignification at optimal pulp yield (43-45%) was obtained by cooking at acetic acid: ethylace tate: water ratio of 33:34:34 for 3 hr at $170^{\circ}C$. But in this case, kappa no. of the pulp was not reduced under 60 points. 2. Kappa no. of the pulp could be dropped by an acetone wash to remove reprecipitated lignin a t cooked pulp. 3. The unbleached pulps had a brightness of 45-50%, whereas the bleached pulps gave at 88-93% brightness. Tensile, burst, and tear strengths of the bleached pulps were lower than those of kraft pulp, especially in tear strength. The pulps which were bleached with CEDED sequence were higher in strengths than another bleaching sequences. 4. Lignin of 90-95%(lignin base on wood)was separated from black liquor and washing liquors, while the purified sugars and recovery of acetic acid were a low. An organic phase composed of acetic acid, ethylacetate, and water was separated to a two-phase system by proper adjustment of the solvent ratios.

• Korean Journal of Food Science and Technology
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• v.19 no.5
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• pp.420-425
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• 1987

For use of sardine oil as an ingredient of food and feed, crude sardine oil obtained by rendering was processed to RBD sardine oil. Alkali deacidification was found to be most efficient with a concentration of 2.5N NaOH and 0.5% excess level at $75^{\circ}C$. Treatment with activated clay alone at $105^{\circ}C$ for 20 min without air admission was effective in reduction of the color intensity of the oil without any formation of the conjugated dienes and trienes of polyunsaturated fatty acids. In deodorization process, as the temperature was increased, color of the oil was to become lighter. The amount of conjugated compounds was, however, increased drastically at higher temperatures above $180^{\circ}C$ for 1hr. and content of polyunsaturated fatty acids was significantly decreased.