• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.265-270
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• 2010

Two major endoglucanase genes (cel7B and cel5A) were cloned from Penicillium decumbens 114-2 using the method of modified thermal asymmetric interlaced polymerase chain reaction (TAIL-PCR). The result of Southern blotting suggested that P. decumbens has a single copy of the cel5A gene and a single copy of the cel7B gene in its chromosomal DNA. The expression levels of cel5A and cel7B were determined by means of real-time quantitative PCR, suggesting that the two genes were coordinately expressed, and repressed by glucose and induced by cellulose. Both endoglucanase genes were expressed in Saccharomyces cerevisiae and the recombinant proteins were purified. The recombinant Cel7B and Cel5A were both optimally active at $60^{\circ}C$ and pH 4.0. The recombinant Cel7B showed more than 8-fold, 30-fold, and 5-fold higher enzyme activities toward carboxymethyl cellulose, barley $\beta$-glucan, and PASC, respectively, in comparison with that of Cel5A. However, their activities toward pNPC and Avicel showed minor differences. The results suggested that Cel7B is a strict endoglucanase, whereas Cel5A showed processivity because of its relative higher ability to hydrolyze the crystal cellulose.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.80-84
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• 1993

In this research, we studied the variation of the dielectric loss absorption of the dielectric loss absorption of the sample according with the change to $\^$60/Co-${\gamma}$-ray irradiation dose of the influence of temperature and applied voltage. In order to investigate the effect of irradiation oriented polypropylene film, we have observed dissipation factor within the temperature range of 30∼130 [$^{\circ}C$] and voltage range of 100∼250$^{\circ}C$ [V]. As for the dependency of temperature by dissipation factor, the ${\alpha}$-peak which appears at high temperature increases accordingly to the increasement of irradiation dose which is contributed by the crystal region and moves towards the high temperature. The ${\beta}$-peak which appears at low temperature is origined from dipoles and molecular motions in the amorphous region. As for the dependency of voltage by tan$\delta$, at low temperature the peak of the tan$\delta$, at low temperature the peak of the tan$\delta$ shifts accordingly to the increasement of irradiation dose towards the high temperature region.

• Journal of the Korean Vacuum Society
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• v.20 no.4
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• pp.276-279
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• 2011

Polymer electrostrictor materials can exhibit high electroactive strain and hold increasing promise for a variety of actuator applications. The size of available actuators has been limited, however, by the solution-based casting and annealing process generally required to prepare electrostrictor actuator materials. We report on a high throughput melt and stretch extrusion process capable of creating large sheets of an electrostructive terpolymer, poly (vinylidene fluoride-trifluoroethylene-1, 1-chlorofluoroethlene) while producing a suitable crystallinity and crystal phase for high strain electrostrictor performance such as artificial muscle systems.

• Korean Journal of Crystallography
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• v.15 no.1
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• pp.40-43
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• 2004

The peptide deformylase from the pathogenic bacterium Staphylococcus aureus has been over-expressed in Escherichia coli and crystallized in the presence of the inhibitor actinonin at 297 K using polyethylene glycol 20000 as a precipitant. X-ray diffraction data have been collected to 2.2 ${\AA}$ resolution. The crystal is trigonal, belonging to the space group $P3_121$ (or its enantiomorph $P3_221$), with unit cell parameters of a = b = 62.70 ${\AA}$ c = 108.23 ${\AA}$, ${\alpha}\;=\;{\beta}\;=\;90^{\circ},\;and\;{\gamma}\;=\;120^{\circ}$. An asymmetric unit contains a monomer of the recombinant enzyme, giving a $V_M$ of 2.84 ${\AA}^3\;Da^_{-1}$ and a solvent content of 56.7%.

• Fibers and Polymers
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• v.5 no.3
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• pp.245-251
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• 2004

Poly(trimethylene terephthalate-co-trimethylene 2,6-naphthalate)s (P(TT-co-TN)s) with various copolymer composition were synthesized, and their chain structure, thermal property and crystalline structure were investigated by using $^1$H-NMR spectroscopy, differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD), respectively. It was found from sequence analysis that all the P(TT-co-TN) copolymers synthesized have a statistical random distribution of TT and TN units. It was also observed from DSC thermograms that the glass transition temperature increases linearly with increasing the TN comonomer content, whereas the melting temperature of copolymer decreases with increasing the corresponding comonomer content in respective PTT- and PTN-based copolymer, showing pseudo-eutectic melting behavior. All the samples melt-crystallized isothermally except for P(TT-co-66 mol % TN) exhibit multiple melting endotherms and clear X-ray diffraction patterns. The multiple melting behavior originates from the dual lamellar population and/or the melting-recrystallization-remelting. The X-ray diffraction patterns are largely divided into two classes depending on the copolymer composition, i.e., PTT and PTN $\beta$-form diffraction patterns, without exhibiting cocrystallization.

• Journal of Technologic Dentistry
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• v.26 no.1
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• pp.77-88
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• 2004

Glass ceramics for dental crown prosthesis were prepared by crystallization of CaO-MgO-SiO2-P2O5-TiO2 glasses. Their crystallization behaviors have been investigated as a function of heattreatment temperature and holding time in relation to mechanical properties. The results are as follows: Vickers hardness and bending strength of glass ceramics increased due to the precipitation of apatite, whitlockite, $\beta$-wollastonite, magnesium titanate, and diopside crystal phases within glass matrix. The final crystalline phase assemblages and the microstructures of the glass ceramics were found to be dependent on heat-treatment temperature and holding time. Vickers hardnes and bending strength of glass ceramics increased with increasing heat-treatment temperature and holding time.

• Journal of the Korean Ceramic Society
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• v.23 no.3
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• pp.67-77
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• 1986

various properties and manufacturing conditions were investigated in order to synthesize the glass-ceramics of $CaO-P_2O_5$ system for bioceramics. Compositions of easy unidirectional crystallization were between 47.5 and 50, 0mol% CaO For the glass rods prepared by pulling them to about 3 times the original rod length unidirectional crystallization was easier than original glass rods. These samples were crystallized in the axial direction at 15${\mu}{\textrm}{m}$/min in an electric furnace with a temperature gradient of about 3$0^{\circ}C$/cm at 57$0^{\circ}C$. Bending strengths of surface and unidirectionally crystallized samples were investigated with various CaO/$P_2O_5$ molar ratios. The bending strengths of unidirectionally crystallized samples were larger than those of surface -crystallized samples and the value of 47.5CaO.52.5 $P_2O_5$ was 1650kg/$cm^2$. XRD patterns showed that major phase is $\beta$-Ca(PO3) with minor phase 2CaO.$P_2O_5$ Relative crystal-linity of surface-crystallized sample was inversely propertional to the bending strenth. SEM of fracture surface of unidirectionally crystallized samples revealed an unidirectionally aligned structures.

• Transactions of Materials Processing
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• v.18 no.6
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• pp.500-507
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• 2009

Tensile deformation behavior with different strain rate was investigated. $Zr_{56.2}Ti_{13.8}Nb_{5.0}Cu_{6.9}Ni_{5.6}Be_{12.5}$(bulk metallic glass alloy possessed crystal phase which was called $\beta$-phase of dendrite shape, mean size of $20{\sim}30{\mu}m$ and occupied 25% of the total volume) was used in this study. Maximum tensile strength was obtained as 1.74GPa at strain rate $10^2s^{-1}$ and minimum strength was found to be 1.6GPa at $10^{-1}s^{-1}$. And then, maximum plastic deformation occurred at the strain rate of $5{\times}10^{-2}s^{-1}$ and represented 1.75%, though minimum plastic deformation showed 0%. In the specific range of strain rate, relatively higher plastic deformation and lower ultimate tensile strength were found with lots of shear bands. The fractographical observation after tensile test indicated that vein like pattern on the fracture surface was well developed especially in the above range of strain rate.

• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.559-567
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• 1989

Bioglasses have been known to be as one of the promising biomateials, which can be used for replacing defective hard and soft tissue. There have been many reports on biological results for this type of glass, but no systematic work has carried out on the structures and properties of the bioglass itself. In the present study, the effect of P2O5 in bioglasses on their structures and properties was examined. Infrared and Raman spectroscopy for the glass structural analysis, differential thermal and X-ray diffraction analysis for the crystallization of the bioglass were performed, and several physical properties were measured. When the glasses were heat-treated, Na2O.2CaO.3SiO2 was the major crystalline phase and $\beta$-NaCaPO4 crystal was found for the glass with high P2O5 content. The added P2O5 in the glasses enhanced the polymerization of silicate glass structure and it changed the chain-like glass structure to a sheet-like structure, and some P2O5 may stay as phosphate monomer. With addition of P2O5 in the glass the density of the glasses decreased, but not much changes in their thermal expansion coefficient, softening point and microhardness were observed.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3093-3097
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• 2013

The synthesis, X-ray crystallography, spectroscopic (IR, UV-vis), and electrochemical properties of the title compound, $[H_3O][Cr(dipic)_2][H_3O^+.Cl^-]$ (1), ($H_2dipic$ = 2,6-pyridinedicarboxylic acid), are reported. This complex crystallizes in the monoclinic space group Cc with a = 14.9006(10) ${\AA}$, b = 12.2114(8) ${\AA}$, c = 8.6337(6) ${\AA}$, ${\alpha}=90.00^{\circ}$, ${\beta}=92.7460(10)^{\circ}$, ${\gamma}=90.00^{\circ}$, and V = 1569.16(18) ${\AA}^3$ with Z = 4. The hydrogen bonding and noncovalent interactions play roles in the stabilization of the structure. In order to gain a better understanding of the most important geometrical parameters in the structure of the complex, atoms in molecules (AIM) method at B3LYP/6-31G level of theory has been employed.