• Korean journal of food and cookery science
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• v.18 no.1
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• pp.57-62
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• 2002

The purpose of this study was to investigate the antibacterial activity of green tea in mayonnaise against pathogenic bacteria (Escherichia coli O157:H7 and Salmonella typhimurium). Mayonnaise was prepared with salad oil, egg yolk, sugar, salt and vinegar, and green tea powder was added to the mayonnaise at 0.1, 0.3 and 0.5% for the experiment. Then, the mayonnaise samples with various levels of green tea were inoculated with about 10$\^$6/ cells/g of E. coli and S. typhimurium per 1 gram of mayonnaise and stored at 5$^{\circ}C$, 15$^{\circ}C$ and 25$^{\circ}C$ for 3∼9 days. Antibacterial activity of green tea was tested by the colony counting method for E. coli on violet red bile agar(VRBA) and S. typhimurium on xylose lysine desoxycholate agar(XLDA). The D-values of E. coli controls were 2.89, 2.73 and 2.13 days while those of S. typhimurium controls were 0.58, 0.53 and 0.52 days at 5$^{\circ}C$, 15$^{\circ}C$ and 25$^{\circ}C$, respectively Inhibitory effect of green tea in mayonnaise on the survival of E. coli and S. typhimurium was increased with increasing concentration of green tea and/or increasing storage temperature. The most effective antibacterial activity of green tea was shown against E. coli in mayonnaise during storage at 25$^{\circ}C$.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.89-96
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• 1982

The purpose of this study is to identify the phases of four different types, low-copper lathe cut (Type II, class 1) and spherical (Type II, class 2) amalgam alloys which are made by Caulk company and high copper Dispersalloy (Type II, class 3) made by Johnson & Johnson and Tytin (Type I, class 2) made by S.S. White and to determine the Vickers hardness number on the individual phase and four different types of dental amalgam. After each amalgam alloy and Hg measured exactly by the balance was triturated by the mechanical amalgamator (De Trey), the triturated mass was inserted into the cylindrical metal mold which was 4 mm in diameter and 12mm in height and was pressed by the Instron Universal Testing machine (Model 1125) at the speed of 1mm/minute with 143$kg/cm^2$ according to the A.D.A. Specification No. 1. The Specimen removed from the mold, mounted and stored in the room temperature for 7 days. The speciman was polished with the emery paper from #220 to #1200 and finally on the polishing cloth with 0.3 and 0.05 um $Al_2O_3$ powder suspended in water. And then each specimen was etched by Allan's method and washed with Sodium Bisulfinite for 30 seconds. Finally differentiation and metallography on each phase were obtained by using metallographical microscope (Versamet, Union) and microhardness was obtained by using microhardness tester (MVH-2, Torsee). The results were as follows: 1. In the low-copper amalgam, the ${\gamma}$, ${\gamma}_1$ and ${\gamma}_2$ phase were observed and in the high-copper amalgam, the ${\gamma}$, ${\gamma}_1$. ${\epsilon}$ and ${\eta}$ phases were observed but ${\gamma}_2$ phase was not observed. 2. Among the microhardness of each amalgam phase measured under pressing a vickers diamond indenter with 2.0gm load for 30 seconds, e phase has the highest V.H.N (314 ${\pm}$ 20), and in low-copper amalgam 12 phase has the lowest V.H.N. (29${\pm}$1) and ${\eta}$ phase which was observed in high-copper amalgam has 230${\pm}$13 V.H.N and this phase is considerd to contribute to strengthen the handness in amalgam. 3. The V.H.N. measured under pressing a Vickers diamond indenter with 300.0gm load for 30 seconds in low-copper amalgam was lower than that of high-copper amalgam.

• Korean Journal of Food Science and Technology
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• v.26 no.2
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• pp.147-151
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• 1994

Hydrogen donating activities(HDA) of solvent extracts of Hololeion maximowiczii roots which were treated with freeze drying, hot air drying and hot air drying after steam blanching were investigated by the method of ${\alpha},{\alpha}'$-diphenyl-${\beta}$-picrylhydrazyl(DPPH). Hydrogen donating activity of hot air drying after steam blanching group showed the highest activity among three drying methods. Among the extracts of freeze dried root extracted with various solvents, color intensity at 420 nm of aqueous extract was highest, but hydrogen donating activity was shown in order of 50%, ethyl alcohol, methyl alcohol, water extracts. By heating the powder of freeze dried root at $100^{\circ}C$, color intensity of its water extract was decreased until 20 min, thereafter it was increased slowly but hydrogen donating activity was rapidly increased until 30 min. Hydrogen donating activity at the concentration of 6.05 mg/ml of 50% alcohol extract was similar to that of ${\alpha}-tocopherol$ at the concentration of $2{\times}10^{-4}M$. Comparison of hydrogen donating activity of the inner and outer solution after dialysis of water extract showed that the outer solution had a stronger hydrogen donating activity than those of the inner one.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.1-5
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• 2012

$Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ hollow fiber with o.d. 1.02 mm and i.d. 0.437 mm were fabricated by a phase-inversion spinning technique.The starting $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ precursor was synthesized by the polymerized complex method and then calcined at $900^{\circ}C$. As-prepared powder was dispersed in a polymer solution, and extruded as form of hollow fiber through a spinneret. Finallydense $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ hollow fiber membrane was obtained by sintering for 2 h at $1,080^{\circ}C$ for the application of oxygen separation. In addition, despite a very thin membrane with 0.58 mm, the BSCF hollow fiber membrane possessed a proper mechanical strength of 602.5 MPa.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.11-17
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• 2012

Disinfection of Escherichia coli (E. coli) in drinking water was investigated by using $TiO_2$ and $TiO_2-SiO_2$ based photocatalyst prepared by sol-gel method. The disinfection test was carried out in an annular flow reactor with circulating sterile water containing the photocatalysts powder under UV-A irradiation. The disinfection activity was proportional to the anatase`s intensity of crystalline peak of the $TiO_2$ photocatalysts. 100% disinfection of E.coli without endotoxin was achieved with $TiO_2$ coated photocatalytic system under UV-A irradiation within 2 h. However, toxic endotoxine was exist in the disinfection of E.colithe under UV-C irradiation even though 100% disinfection of E.colithe within 30 min, which suggest that $TiO_2$ coated photocatalytic system with UV-A is useful tool for the disinfection of E.coli in drinking water.

• Archives of Pharmacal Research
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• v.28 no.5
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• pp.604-611
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• 2005

Polyethylene glycol (PEG) 6000-based solid dispersions (SDs), by incorporating various pharmaceutical excipients or microemulsion systems, were prepared using a fusion method, t o compare the dissolution rates and bioavailabilities in rats. The amorphous structure of the drug in SDs was also characterized by powder X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The ketoconazole (KT), as an antifungal agent, was selected as a model drug. The dissolution rate of KT increased when solubilizing excipients were incorporated into the PEG-based SDs. When hydrophilic and lipophilic excipients were combined and incorporated into PEG-based SDs, a remarkable enhancement of the dissolution rate was observed. The PEG-based SDs, incorporating a self microemulsifying drug delivery system (SMEDDS) or microemulsion (ME), were also useful at improving the dissolution rate by forming a microemulsion or dispersible particles within the aqueous medium. However, due to the limited solubilization capacity, these PEG-based SDs showed dissolution rates, below 50% in this study, under sink conditions. The PEG-based SD, with no pharmaceutical excipients incorporated, increased the maximum plasma concentration (C$_{max}$) and area under the plasma concentration curve (AUC$_{0-6h}$) two-fold compared to the drug only. The bioavailability was more pronounced in the cases of solubilizing and microemulsifying PEG-based SDs. The thermograms of the PEG-based SDs showed the characteristic peak of the carrier matrix around 60$^{\circ}C$, without a drug peak, indicating that the drug had changed into an amorphous structure. The diffraction pattern of the pure drug showed the drug to be highly crystalline in nature, as indicated by numerous distinctive peaks. The lack of the numerous distinctive peaks of the drug in the PEG-based SDs demonstrated that a high concentration of the drug molecules was dissolved in the solid-state carrier matrix of the amorphous structure. The utilization of oils, fatty acid and surfactant, or their mixtures, in PEG-based SD could be a useful tool to enhance the dissolution and bioavailability of poorly water-soluble drugs by forming solubilizing and microemulsifying systems when exposed to gastrointestinal fluid.

• Journal of the Korean Chemical Society
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• v.35 no.3
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• pp.211-218
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• 1991

A series of samples in the $Nd_{-x}Sr_{x}CoO_{3-y}$ system (x = 0.00, 0.25, 0.50, 0.75 and 1.00) have been produced by heating the reactants at 1200${\circ}$C under atmospheric pressure. The solid solutions were analysed by X-ray diffraction spectra, thermal analysis, and SEM micrographs. X-ray powder diffraction assigns the compositions of x = 0.00, 0.25, 0.50 and 0.75 to the cubic system and the composition of x = 1.00 to the orthorhombic system. The reduced lattice volume is increased with increasing x values in the system. The mole ratio of $Co^{4+}$ or ${\tau}$ values are determined by the Iodometric titration method and are maximum at the composition of x = 0.50. The magnetic measurement shows that a ferromagnetism is appeared in the compositions of x = 0.00, 0.25, 0.50 and 0.75 and then an antiferromagnetism in the composition of x = 1.00. The measurement of the electrical conductivity shows that the semiconductivity is appeared in the composition of x = 0.00, 0.25 and 1.00 and the metallic conductivity in the composition of x = 0.50 and 0.75. The magnetic and electrical properties of the samples are discussed with the nonstoichiometric chemical formulas.

• Food Science and Preservation
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• v.11 no.4
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• pp.478-484
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• 2004

Freshness maintenance of polyethylene packaging film containing surface-modified zeolite was investigated depending on the nature of substituted cations and cationic surfactants. Freshness maintenance was designed to work by cation or cationic surfactant adsorbed onto the zeolite surface by ion-exchange method. Cationic surfactants such as DODAB (n-dodecyltrimethylammonium bromide), CTAB (n-cetyltrimethylammonium bromide), and DHAB (n-dihexadecyldime-thylammonium bromide), and cations ($Ce^{3+},\;Al^{3+},\;Mg^{2+},\;Ca^{2+},\;Ag^{3+},\;Na^{1+}\;and\;Cu^{3+}$) were used. Surface-modified zeolite powder was compounded with LDPE to produce $20\;wt\%$ zeolite masterbatch (M/B), and the M/B was again blended with LDPE to get zeolite-containing LDPE films with 3, 5, $10\;wt\%$ of zeolite (width: 40 cm, thickness: $40\;{\mu}m$). Mechanical properties of zeolite-containing LDPE films generally decreased with increasing zeolite content. However, cationic surfactant-modified zeolite film showed the better mechanical properties compared to cation-modified zeolite film. As for the freshness maintenance, the zeolite-containing films modified with cationic surfactants or cations ($Al^{3+},\;Ag^{3+}$) showed the best performance.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.34-39
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• 2006

Pure and Fe-doped CuO thin-film and powder samples were prepared using a sol-gel method. Undoped CuO films exhibited monoclinic structure and p-type electrical conductivity $(\~10^{-2}\;{\Omega^{-1}\;cm^{-1}$ due to copper deficiency. On the other hand, CuO: Fe films were found to be insulating and Li doping on the films led to a restoration of p-type conductivity and a ferromagnetic hysteresis behaviour at room temperature. The observed properties far the CuO : Fe, Li films can be explained in terms of hole creation by substitution of $Li^+$ for $Cu^{2+}$ sites and mediation of long-range interactions between $Fe^{3+}$ ions by the $Li^+$-induced defect states. CuO: Fe powders exhibited a ferromagnetism at room temperature with its strength being dependent on post-annealing temperature. Mossbauer measurements on the CuO: Fe films and powders revealed that the octahedral $Cu^{2+}$ sites are mostly substituted by $Fe^{3+}$ ions.

• Applied Biological Chemistry
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• v.21 no.3
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• pp.144-149
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• 1978

Fermented soy sauce was dehydrated by spray drying to form powder, and moisture sorption properties of powdered soy sauce with or without cover of the flexible films were examined on different relative humidity by using saturated salt solutions at $30^{\circ}$. The results obtained were summarized as follows: The equilibrium moisture content of spray-dried soy sauce containing 18.3% moisture was determined to 52% by graphical interpolation method, and E.M.C. of powdered soy sauce covered with plastic films decreased at low relative humidity whereas sharply increased curves were seen at high relative humidity. The rate constant of moisture adsortion K for the power covered with films were $66.2{\times}10^{-5}\;to\;225{\times}10^{-5}/hr$., and K' became greater when film having higher water vapor transmission rate was used. The shelf-life of powdered soy sauce covered with Al. foil/P.E. film by Brown formula at the accelerated condition of $38^{\circ}$, 92% R. H. was the longest period, 164 days compared with any other films used, and the shortest period, 18 days in P.V.C. film.