• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.597-604
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• 2004

This work involves quantitatively investigating the correlation between reductions in strength and variations in pore structure under high temperature that can be utilized as estimation for predicting the inner temperature of member damaged by fire. The experimental results were remarkedly affected by micro-filling effect of silica fume and the different water-binder ratios. The increase of the exposure temperature caused the increase of porosity, which resulted from the reason that evaporable water in gel pore or capillary pores as well as chemically bound water was eliminated from hardened cement paste due to the dehydration of C-S-H and $Ca(OH)_2$. Thermal shrinkage of hardened cement paste gives rise to micro-crack, which cause the increase of porosity. Based on the experimental result that the increase of porosity is in charge of exposure temperature, how porosity is distributed can predict temperature-time history and assess the performance of concrete damaged by fire.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.832-842
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• 1996

TAME synthesis was studied in a fixed bed reactor with 3 different types of exchanged resins i.e, Amberlyst-15, Amberlyst-15(wet) and Amberlyst XN-1010. Amberlyst-15 has highest activity, presumably due to the higher reaction participation of the inner active sites of gel shape microparticular resin structure. The optimum reaction conditions for TAME synthesis were found as follows ; reaction temperature of $135^{\circ}C$, molar ratio(MeOH/I.A.A) of 1.0~4.0 and W/F of 2.0~4.0 gr.-cat. hr/gr.-mole. The cross-linking bond of styrene divinyl benzene was observed at $2{\theta}=20$ in XRD pattern. The DSC analysis showed that the thermal stability was in order of Amberlyst-15>Amberlyst-15(wet)>Amberlyst XN-1010. The apparent activation energies of TAME synthesis reaction with Amberlyst-15, Amberlyst-15(wet) and Amberlyst XN-1010 were 12.36, 12.46 and 14.72 kcal/mole, respectively.

• The Plant Pathology Journal
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• v.22 no.1
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• pp.51-62
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• 2006

Three strains of Cucumber mosaic virus (CMV) have been found to cause a lethal disease, referred to as fern leaf syndromes and mild mosaic symptoms in tomato (Lycopersicon esculentum Mill.) crops grown in Kuwait. CMV strains were detected and identified based on host range, symptomatology, serology, electron microscopy, and ribonucleic acid (RNA) electrophoresis in polyacrylamide gels. A high degree of viral genomic heterogeneity was detected among CMV strains isolated in Kuwait, with no apparent correlation to symptomatology in tomato host plants. Two different virus satellites of 'CMV associated RNA 5', designated CARNA 5, were detected in two virus strains that caused both lethal disease and mild symptoms, designated CMV-D1 and CMV-S1 respectively. CARNA5 was not detected in the third CMV strain that caused fern leaf syndromes designated CMV-F. All the three isolated strains were serologically indistinguishable from each other and may belong to one serotype according to Ouchterlony gel diffusion tests. These strains transmitted via aphids (Myzus persicae Sulz) in a non-persistent manner. Physical properties of the virus strains were very similar where thermal inactivation test showed that virus withstood heating for 10 min at $70^{/circ}$, dilution end point was $10^{-4}$, and the longevity in vitro at room temperature was less than 5 days for all virus strains. CMV-D1 and CMV-F were the most devastating diseases spreading in both greenhouse and field-grown tomato where aborted flower buds failed on fruit setting due to the viral infection. This is the first report to isolate three different strains of CMV in Kuwait.

• Parasites, Hosts and Diseases
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• v.55 no.6
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• pp.643-652
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• 2017

Calreticulin (CALR), a multifunctional protein thoroughly researched in mammals, comprises N-, P-, and C-domain and has roles in calcium homeostasis, chaperoning, clearance of apoptotic cells, cell adhesion, and also angiogenesis. In this study, the spatial and temporal expression patterns of the Opisthorchis viverrini CALR gene were analyzed, and calcium-binding and chaperoning properties of recombinant O. viverrini CALR (OvCALR) investigated. OvCALR mRNA was detected from the newly excysted juvenile to the mature parasite by RT-PCR while specific antibodies showed a wide distribution of the protein. OvCALR was localized in tegumental cell bodies, testes, ovary, eggs, Mehlis' gland, prostate gland, and vitelline cells of the mature parasite. Recombinant OvCALR showed an in vitro suppressive effect on the thermal aggregation of citrate synthase. The recombinant OvCALR C-domain showed a mobility shift in native gel electrophoresis in the presence of calcium. The results imply that OvCALR has comparable function to the mammalian homolog as a calcium-binding molecular chaperone. Inferred from the observed strong immunostaining of the reproductive tissues, OvCALR should be important for reproduction and might be an interesting target to disrupt parasite fecundity. Transacetylase activity of OvCALR as reported for calreticulin of Haemonchus contortus could not be observed.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.35.1-35.1
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• 2011

New photovoltaic (PV) materials and manufacturing approaches are needed for meeting the demand for lower-cost solar cells. The prototypal thin-film photovoltaic absorbers (CdTe and $Cu(In,Ga)Se_2$) can achieve solar conversion efficiencies of up to 20% and are now commercially available, but the presence of toxic (Cd,Se) and expensive elemental components (In, Te) is a real issue as the demand for photovoltaics rapidly increases. To overcome these limitations, there has been substantial interest in developing viable alternative materials, such as $Cu_2ZnSnS_4$ (CZTS) is an emerging solar absorber that is structurally similar to CIGS, but contains only earth abundant, non-toxic elements and has a near optimal direct band gap energy of 1.4~1.6 ev and a large absorption coefficient of ${\sim}10^4\;cm^{-1}$. The CZTS absorber layers are grown and investigated by various fabrication methods, such as thermal evaporation, e-beam evaporation with a post sulfurization, sputtering, non-vacuum sol-gel, pulsed laser, spray-pyrolysis method and electrodeposition technique. In the present work, we report an alternative method for large area deposition of CZTS thin films that is potentially high throughput and inexpensive when used to produce monolithically integrated solar panel modules. Specifically, we have developed an aqueous chemical approach based on chemical bath deposition (CBD) with a subsequent sulfurization heat treatment. Samples produced by our method were analyzed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, absorbance and photoluminescence. The results show that this inexpensive and relatively benign process produces thin films of CZTS exhibiting uniform composition, kesterite crystal structure, and good optical properties. A preliminary solar cell device was fabricated to demonstrate rectifying and photovoltaic behavior.

• Polymer(Korea)
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• v.27 no.3
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• pp.195-200
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• 2003

Alginate is a natural ionic polymer including numerous anionic groups and can be actuated by the ionic group under the electric field. The crosslinked alginate films were fabricated with CaCl$_2$. The thermal, mechanical and electroresponse properties of the films were investigated by thermogravimetric analysis, tensile and bending tests. The initial degradation and tensile strength increased according to the degree of crosslinking. Also, the swelling ratio of the films increased with decreasing degree of crosslinking and increasing pH due to free volume and electrostatic repulsion. The films actuated by an electric stimulus exhibited gentle and flexible action like a pendulum. In the electric field, the electric stimuli such as the applied voltage, ionic strength and kind of electrolyte solution had an effect on the electroresponse of the films. Alginate films with 5 wt% crosslinking agent showed the highest bending angle and reversible bending behavior. When the ionic strength of NaCl and KCl electrolyte solution was 0.1 M, the films showed the highest electroresponse. The bending behavior of the films increased with the applied voltage.

• Journal of Powder Materials
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• v.23 no.1
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• pp.38-42
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• 2016

$BaTiO_3$-coated Fe nanofibers are synthesized via a three-step process. ${\alpha}-Fe_2O_3$ nanofibers with an average diameter of approximately 200 nm are first prepared using an electrospinning process followed by a calcination step. The $BaTiO_3$ coating layer on the nanofiber is formed by a sol-gel process, and a thermal reduction process is then applied to the core-shell nanofiber to selectively reduce the ${\alpha}-Fe_2O_3$ to Fe. The thickness of the $BaTiO_3$ shell is controlled by varying the reaction time. To evaluate the electromagnetic (EM) wave-absorbing abilities of the $BaTiO_3@Fe$ nanofiber, epoxy-based composites containing the nanofibers are fabricated. The composites show excellent EM wave absorption properties where the power loss increases to the high frequency region without any degradation. Our results demonstrate that the $BaTiO_3@Fe$ nanofibers obtained in this work are attractive candidates for electromagnetic wave absorption applications.

• Korean Journal of Food Science and Technology
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• v.14 no.2
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• pp.125-129
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• 1982

Four peroxidase isozymes from horseradish roots (isozymes A, B, C and D) were isolated by chromatography and were thermally inactivated at $70{\sim}97^{\circ}C$ and pH 7.0. The four isozymes had different inactivation rates and the inactivation of each isozymes did not follow first order kinetics. D values of isozymes A, B, C, D and crude enzyme were 594s, 1850s, 2050s, 78s, 130s and z values were $24.0^{\circ}C$, $12.5^{\circ}C$, $18.0^{\circ}C$, $23.7^{\circ}C$ and $24.0^{\circ}C$, respectively. Sephadex gel chromatogram of the thermally treated isozyme C indicated that the shape and molecular weight of the native isozyme changed during inactivation.

• Journal of Microbiology and Biotechnology
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• v.24 no.8
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• pp.1096-1104
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• 2014

$\small{L}$-Asparaginase from gram-positive bacteria has been poorly explored. We conducted recombinant overexpression and purification of $\small{L}$-asparaginase from Staphylococcus sp. OJ82 (SoAsn) isolated from Korean fermented seafood to evaluate its biotechnological potential as an antileukemic agent. SoAsn was expressed in Escherichia coli BL21 (DE3) with an estimated molecular mass of 37.5 kDa, determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Consistent with asparaginases in gram-negative bacteria, size-exclusion chromatography determined SoAsn as a homodimer. Interestingly, the optimal temperature of SoAsn was $37^{\circ}C$ and over 90% of activity was retained between $37^{\circ}C$ and $50^{\circ}C$, and its thermal stability range was narrower than that of commercial E. coli $\small{L}$-asparaginase (EcAsn). Both SoAsn and EcAsn were active between pH 9 and 10, although their overall pH-dependent enzyme activities were slightly different. The $K_m$ value of SoAsn was 2.2 mM, which is higher than that of EcAsn. Among eight metals tested for enzyme activity, cobalt and magnesium greatly enhanced the SoAsn and EcAsn activity, respectively. Interestingly, SoAsn retained more than 60% of its activity under 2 M NaCl condition, but the activity of EcAsn was reduced to 48%. Overall, the biochemical characteristics of SoAsn were similar to those of EcAsn, but its kinetics, cofactor requirements, and NaCl tolerance differed from those of EcAsn.

• Archives of Pharmacal Research
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• v.28 no.6
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• pp.736-742
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• 2005

Xyloglucan (XG), which exhibits thermal sol to gel transition, non-toxicity, and low gelation concentration, is of interest in the development of sustained release carriers for drug delivery. Drug-loaded XG beads were prepared by extruding dropwise a dispersion of indomethacin in aqueous XG solution (2 wt.-$\%$) through a syringe into corn oil. Enteric coating of XG bead was performed using Eudragit L 100 to improve the stability of XG bead in gastrointestinal (GI) track and to achieve gastroresistant drug release. Release behavior of indomethacin from XG beads in vitro was investigated as a function of loading content of drug, pH of release medium, and concentration of coating agent. Adhesive force of XG was also measured using the tensile test. Uniform-sized spherical beads with particle diameters ranging from 692 $\pm$ 30 to 819 $\pm$ 50 $\mu$m were obtained. The effect of drug content on the release of indomethacin from XG beads depended on the medium pH. Release of indomethacin from XG beads was retarded by coating with Eudragit and increased rapidly with the change in medium pH from 1.2 to 7.4. Adhesive force of XG was stronger than that of Carbopol 943 P, a well-known commercial mucoadhesive polymer, in wet state. Results indicate the enteric-coated XG beads may be suitable as a carrier for oral drug delivery of irritant drug in the stomach.