• Journal of Life Science
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• v.13 no.3
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• pp.308-313
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• 2003

The collagenase gene from Vibrio parahaemolyticus 04 was subcloned into an expression vector pET-29b. The recombinant collagenase was expressed in Escherichia coli BL2l(DE3) and partially purified by Hi-Trap affinity and Sephacryl S-100 size exclusion chromatographies. The recombinant enzyme was purified by 43.7-fold and the yield was 73%. SDS-PAGE revealed that the molecular weight of the enzyme was approximately 35 kDa. Substrate specificity study of the enzyme displayed that the enzyme showed the highest activity with the type I collagen and the synthetic peptide, Z-GPGGPA, indicating that the enzyme was indeed a collagenase. The enzyme showed broad pH optimum around pH 6-12 and was stable between pH 5.5 and 11.5. The optimum temperature for the type I collagen degradation was $35^{\circ}C$. The thermostability measurement of the enzyme indicated that the enzyme was stable up to $55^{\circ}C$, but the activity was diminished quickly above $60^{\circ}C.$

• Journal of Microbiology
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• v.33 no.4
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• pp.307-314
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• 1995

Trypsin like protease (TLP) and metalloprotease (MTP) were induced in associated with the mycelium differentiation in Streptomyces albidoflavus SMF301. TLP and MTP were purified and characterized from the culture. The molecular mass of TLP and MTP were estimated to be 32 kDa and 18 kDa, respectively. The molecular mass of TLP and MTP were estimated to be 32 kDa and 18 kDa, respectively. The optimum pH and temperature of TLP were 10 and 40.$^{\circ}C$ Those of MTP were 8 and 55 $^{\circ}C$ TLP was stable at alkaline pH (6-9) and unstable above 45.$^{\circ}C$and MTP was stable at alkaline pH and unstable above 80.$^{\circ}C$ Km and Vmax values with benzoyl-arginyl p-nitroanilide of TLP were 139 $\mu$M, and 10 nmole of nitroanilide released per min per$\mu\textrm{g}$ protein, respectively. Km, and Vmax values with a synthetic substrate, leucine p-nitroanilide, or MTP were 58.9 $\mu$M, 3.47 nmol of nitroanilide released per min per$\mu\textrm{g}$protein, respectively. TLP was inhibited competitively by leupeptin; the inhibition constant was 0.0031 $\mu$M. MTP was inhibited by EDTA, phenonthroline and bestatin.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.387-392
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• 2005

Recently, dimethyl carbonate (DMC) is considered as an alternative of MTBE (methyl tert-butyl ether), additive for non-leaded gasoline with their fast biodegradation rate and low toxicity. DMC is usually synthesized so far by oxidative carbonylation of methanol, and recently developed synthetic process is also started with methanol. Since the phase equilibria of the system, consisted of DMC and methanol or other reaction products on different temperature and pressure is necessary for the optimum separation process design and operation. However the reported phase equilibria and physical properties for DMC mixtures in the Dortmund Data Bank (DDB; thermodynamic property data bank) are quite rare. Besides, infinitely dilute properties are not found. In this work, isothermal vapor-liquid equilibria at 333.15 K for methanol+DMC binary system and mixing properties, excess molar volume and viscosity deviation at 298.15 K are directly measured and correlated. Additionally, infinitely dilute activity coefficient of methanol in the DMC solvent at three different temperatures are measured and compared with predicted values using modified UNIFAC (Dortmund).

• Journal of the Korean Ceramic Society
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• v.20 no.1
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• pp.37-42
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• 1983

An attempt was made to derive a possible synthetic mechanism of Fluoro-phlogopite (Mica, 4Mg.$Al_2O_3$.$6SiO_2$.$K_2O$.$2MgF_2$) The pevention of fluorine vaporization turned out to be the key in the synthesis of Mica in question.l Consequently the quinary system of Mica was seperately synthesized ; frist 4MgO.$Al_2O_3-6SiO_2$(ternary system) was sintered at 135$0^{\circ}C$ and $K_2O$ and $MgF_2$ were added and second 4MgO.$Al_2O_3-6SiO_2$.$K_2O$ (quarternary system) was heat-treated at 135$0^{\circ}C$ and $MgF_2$ was added. The ternary system resulted in Proto-enstatite Cordierite and Spinel phases while Forsterite and Leucite were shown in the quarternay system . In both methods Fluoro-phlogopite was systhesized but the solid state reactions to form Mica from the ternary system and the quarternary system were different. High temperature reactions in the formation of Mica were investigated employing XRD, DTA and SEM The study of the synthesis of Mica indirectly suggested a method of phase analysis of quinary system(MgO-$Al_2O_3-SiO_2-K_2O-MgF_2$) and quarternary system(MgO-$Al_2O_3-SiO_2-K_2O-MgF_2$) at various temperatures.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.544-548
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• 2014

Aluminum nitride was synthesized using a carbothermal method from mesoporous alumina having a high surface area (> $1,000m^2/g$) as an aluminum source and CNTs (carbon nano tubes) as a carbon source. In this case the mesoporous alumina was used as the starting material instead of ${\alpha}-Al_2O_3$ with the expectation that the mesopores in mesoporous alumina act as channels for N2 gas and elimination of CO generated as by-product. It is also expected that the synthetic temperature should be lower compared to the use of ${\alpha}-Al_2O_3$ as a starting material due to its high surface area. The crystallinity of the produced aluminum nitride was studied by XRD and FT-IR, and the microstructure was investigated by FE-SEM. Also the purity of the aluminum nitride was analyzed through N/O determinator and ICP analysis.

• Applied Biological Chemistry
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• v.35 no.5
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• pp.339-345
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• 1992

In order to enhance the processing quality and utility of alaska-pollack meat, the optimum conditions for the preparation of pronase hydrolysate and the synthesis of plastein were investigated. The optimum temperature and pH for the hydrolysis of alaska-pollack by pronase were $40^{\circ}C$ and pH 7.0. The reaction time and enzyme concentration were 4 hr and 1,000 units per g of substrate. Under the above optimum conditions alaska-pollack was hydrolyzed by pronase yielding a hydrolytic degree of about 89%. Pronase hydrolysate was employed as substrate for plastein synthesis. The 30% pronase hydrolysates were adjusted to pH 7 for fruit-bromelain and pH 5 for stem-bromelain, and then plastein were synthesized by 1% bromelain at $40^{\circ}C$ for 24 hr. The plasteins synthesized by fruit- and stem-bromelain were consisted of peptides having average peptide length of 22.6 and 20.8 under the optimum synthetic conditions. The plastein synthesis reaction reduced considerably the bitterness of pronase hydrolysate.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.311-314
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• 2004

Toxicity test fur various synthetic lubricant oil bases derived from biodiesel was carried out. The earthworms(Eisenia fetida) were maintanied in artificial soil consisting of sand for 14 days. Eisenia fetida was cultivated at temperature of $20{\pm}2^{\circ}C$, pH 6.0 $\pm$ 0.5 and moisture of $31\~37\%$. Pentaerythritol(PE) lubricant oil base was tested for acute toxicities to Eisenia fetida. The earthworms were exposed to each lubricant oil with various concentrations of lubricant oil base. After 14 days, the number of surviving earthworms and thier weight alteration during the test period was determined. $LC_{50}$(lethal concentration when $50\%$ of the population were killed) pentaerythritol was determined to be 1,555 mg/kg soil dry weight.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.307-308
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• 2007

This work shows the experimental results obtained from ageing at a temperature of 100 C for 48, 70 and 312 h, although the application of AC electrical tension in samples and the measuring of current leakage are presented. The measurements in samples were carried out with samples prepared from the deformulated commercial materials and respectively reformulated into thin films. The obtained results showed the mechanisms of conduction of samples in low and high electric fields. It was also identified an electric tension transition showing that in low fields it prevails the Ohm's law conduction, and in high electric fields it prevails the conduction of space charge limited current (SCLC). These results can support the natural rubber formulation process having as their main objective the reducing of the mechanisms that occur under high conduction current in high electric fields, which leads the material to a dielectric breakdown. Raw Natural rubber in Brazil is extracted from rubber trees (Hevea brasiliensis) in farms in So Paulo State by using some new plantation technology in smaller spaces, with trees placed a few meters from each other. In the Amazon rain forest the rubber trees are found naturally and their spacing may be of hundreds of meters or even kilometers between them. It is necessary to research this raw material from different internationally standard clones to characterize dielectric and electric properties for industrial applications. Moreover, this natural material has a low commercial price when compared to the synthetic ones.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1970-1971
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• 2007

The efficiency of such work highly depend on the worker's safety, who is protected by tools such as gloves, sleeves, blankets and flexible coverings among other manufactured natural-rubber goods. Use, storage and maintenance of these tools guarantee the quality and durability of the material. However, it might be observed that good tools made of such material are disapproved of when received from manufacturers or when they are removed from the warehouse for replacement. This work shows the experimental results obtained from ageing at a temperature of $100^{\circ}C$ for 48, 70 and 312 h, although the application of AC electrical tension in samples and the measuring of current leakage are presented. The measurements in samples were carried out with samples prepared from the deformulated commercial materials and respectively reformulated into thin films. The obtained results showed the mechanisms of conduction of samples in low and high electric fields. It was also identified an electric tension transition showing that in low fields it prevails the Ohm's law conduction, and in high electric fields it prevails the conduction of space charge limited current (SCLC). These results can support the natural rubber formulation process having as their main objective the reducing of the mechanisms that occur under high conduction current in high electric fields, which leads the material to a dielectric breakdown. It is necessary to research this raw material from different internationally standard clones to characterize dielectric and electric properties for industrial applications. Moreover, this natural material has a low commercial price when compared to the synthetic ones.

• Journal of the Korean Wood Science and Technology
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• v.26 no.4
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• pp.43-49
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• 1998

The availability of large quantities of waste woods provides an impetus for investigating woody biomass potential uses. Polyurethane (PU) foams are prepared with reacting isocyanates and polyols, and are used. in various industry fields. Thus, lignocellulosic waste raw-materials are proposed as replacement for synthetic polyol to PU foam formulation. In this study PU foams were manufactured from liquefied woods, methanediisocyanate(MDI), catalyst, foaming stabilizer, and viscosity aids. The polyol content, isocyanate.hydroxyl group (NCO/OH) ratio, and water content were varied to evaluate their effects on the foaming and water absorption of the PU foams. Less than 400 Molecular weight. of polyethylene glycol(PEG) and 1 to 3 solvent to woody raw-material ratio were desirable for liquefying woody materials. Liquefying rate was increased with more than 3 % addition of inorganic and organic catalysts and raising reaction temperature more than $150^{\circ}C$. Addition of starch enhanced liquefying of woody materials. Fourty percents of starch resulted in about 90% liquefying rates. Foaming rates were increased with increasing moisture contents of liquefied wood. Moisture contents of 0.6% resulted in 5 time-foaming rates, and seven percents of moisture contents more than 30 time-foaming rates. But, an increase in water content may result in a decrease in cross-links between wood polyol and isocyanate, because the NCO/OH ratio is constant. Increasing moisture contents have significantly decreased density of PU foams. The optimum water content should be about 2.5% or less in this adopted condition.