• Korean Journal of Microbiology
• /
• v.17 no.3
• /
• pp.152-159
• /
• 1979

Using Micromonospora strain, gentamicin was produced by fermentation. The increase in gentamicin productivity was studied by strain improvement and systematic optimization of fermentation process variables. The productivity of parent strain of M.purpurea (ATCC15835) was improved by selection of superior mutant after U.V. irradiation and induction of genetamicin resistance. Potato starch and soy bean meal were the best carbon and nitrogen sources for gentamicin fermentation, respectively. The optimum stimulating concentration of Co ion for gentamicin production was 0.006g $CoCl_2$ per liter of broth. Oxygen ws found to be an important factor for gentamicin yield. The optimum pH for the cell growth and gentamicin production were 7.2 and 6.8 respectively. By controlling the pH, oxygen, and other conditions found in this study at the optimal conditions for cell growth and gentamicin production, the total productivity of gentamicin was increased significantly.

• Journal of the Korean Ceramic Society
• /
• v.31 no.2
• /
• pp.227-233
• /
• 1994

The Bi-Sr-Ca-Cu-O thin films were deposited by RF-magnetron sputtering method on Si(P-111) wafer without a buffer layer and annealed at various temperatures in oxygen atmosphere. The temperature dependence of electrical resistance, the microstructure of intermediate phase, and the surface morphology of films were examined by four probe method, XRD, and SEM, respectively. The chemical composition and the depth profile of the films were determined by ESCA spectra. Thin films annealed at $600^{\circ}C$ and $700^{\circ}C$ in oxygen atmosphere showed onset temperatures of 90 K and 85K, and Tc(zero) of 22K and 31K, respectively. The sample annealed at $700^{\circ}C$ had the highest volume fraction of superconducting phase and showed smooth microsturcture. In ESCA spectra, the thin films were homogeneous with depth.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1779-1783
• /
• 2006

The hybrid thin-film (HTF) passivation layer composed of the UV curable acrylate layer and MS-31 (MgO:SiO2=3:1wt%) layer was adopted in organic light emitting diode (OLED) to protect organic light emitting materials from penetrations of oxygen and water vapors. The moisture resistance of the deposited HTF layer was measured by the water vapor transmission rate (WVTR). The results showed that the HTF layer possessed a very low WVTR value of lower than $0.007g/m^2$ per day at $37.8^{\circ}C$ and 100% RH. Therefore, the HTF on the OLED was found to be very effective in protect what from the penetrations of oxygen and moisture.

• Journal of the Korean Ceramic Society
• /
• v.31 no.6
• /
• pp.601-608
• /
• 1994

Aluminum oxide thin films were deposited on p-type(100) silicon substrates by electron cyclotron resonance plasma enhanced CVD(ECR-PECVD) using TMA[Al(CH3)3] and oxygen as reactant gases at 16$0^{\circ}C$ or lower temperatures. The aluminum oxide films deposited by ECR-PECVD have the amorphous structure with the refractive index of 1.62~1.64 and the O/Al ratio of 1.6~1.7. Oxygen flow rate necessary for the stable deposition of the aluminum oxide films increases as the deposition temperature increases. It was found from the OES analysis that the ECR plasma had les cooling effect by introducing the TMA reactant gas in comparison with the RF plasma. The properties of aluminum oxide films prepared by ECR-PECVD were compared with those prepared by RF-PECVD. The ECR-PECVD aluminum oxide films have the higher refractive indices, the lower contents of impurities (H and C) and the stronger wet etch resistance than those deposited by RF-PECVD.

• Journal of the Korean Society of Safety
• /
• v.1 no.1
• /
• pp.21-26
• /
• 1986

Gas sensing materials for detecting inflammable gas such as alcohol, propane, acetic acid, carbon monoxide, hydrogen were developed by utiliting $MgO-Cr_2O_3-TiO_2$ system. Between 30$0^{\circ}C$ and 50$0^{\circ}C$, reversible chemisorption becomes dominant and the electrical canduction of P-type semiconductive with the gas chemisorption. The ceramic sensor exhibits a high sensitivity to particular reducing gas such as alcohol, whereas propane and butane have little effect on the resistivity. The time response of adsorption is estimated to be about 20 sec. On the other hand, the desorption process, which corresponds to oxidation due to oxygen adsorption, take more than 60 sec. Thus the ceramic sensor can be used as a alcohol sensor in an ambient aunosphere. As the oxygen concentration is increased from 0.1 to 10 precent($10^3-10^6ppm$), the resistance decreases rapidly but stabilizes at higher concentration.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 1979.10a
• /
• pp.245.2-246
• /
• 1979

Heat treated whole cell of Aspergillus niger containing glucose oxidase-catalase system was entrapped in gelatin matrix crosslinked by glutaral-dehyde. The reaction characteristics of immobilized enzyme was studied in a fludized reactor. Heat treatment enhanced the stability and improved the properties of micellium for the immobilized process. The immobilized enzyme system showed the maximum activity at $35^{\circ}C$ and at pH 5.5. The optimum substrate concentration was 0.04M glucose. The activity of immobilized glucose oxidase was in proportion to the concentration of dissolved oxygen in reaction mixture as other reaction conditions were fixed. It was also demonstrated that the limiting factor for the activity of the immobilized glucose oxidase was the oxygen diffusion resistance which increases proportionally to the glucose concentration.

• Korean Journal of Microbiology
• /
• v.11 no.2
• /
• pp.79-88
• /
• 1973

In order to investigate the effect of gamma radiation on Salmonella typhi, Ty2, the components of amino acids, proteins, carbohydrates and lipids in irradiated cells were compared with those in unirradiated control cells respectively. The results obtained were as follows ; 1) The inactivation curves of Salmonella typhi with $Co^{60}$ .gamma.-ray irradiation were exponential over a wide range to the irradiated doses. 2) Dose for the inactivation factor of $10^8$ was 94.0 Krad in physiological saline or in phosphate buffered saline, 104.2 Krad in nutrient broth, 220.4Krad in frozen state, 552.0 Krad in dried state, 88.3 Krad in the abundance of oxygen and 188.0 Krad in the deficience of oxygen, respectively. 3) Five consecutive irradiation of Salmonella typhi suspension at the dose of 90 Krad gave no additional increase in resistance. 4) Even at the smallest dose of 500 Krad, compositions of amino acids, proteins, carbohydrates, and lipids were more or less decreased and the distinct banding patterns were also lost possibly due to degradation of the protein molecules.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07a
• /
• pp.614-615
• /
• 2005

The use of plastic substrates enables new applications, such as flexible display devices, and other flexible electronic devices, using low cost, roll-to-roll (R2R) fabrication technologies. One of the limitations of polymeric substrate in these applications is that oxygen and moisture rapidly diffuse through the material and subsequently degrade the electro-optical devices. GE Global Research (GEGR) has developed a plastic substrate technology comprised of a superior high-heat polycarbonate ($LEXAN^{(R)}$) substrate film and a unique transparent coating package that provides the ultrahigh barrier (UHB) to moisture and oxygen,chemical resistance to solvents used in device fabrications, and a high performance transparent conductor. This article describes the coating solutions for polycarbonate ($LEXAN^{(R)}$) films and its compatibility with OLED device fabrication processes.

• Clinical and Experimental Pediatrics
• /
• v.63 no.1
• /
• pp.3-7
• /
• 2020

High-flow nasal cannula (HFNC) is a relatively safe and effective noninvasive ventilation method that was recently accepted as a treatment option for acute respiratory support before endotracheal intubation or invasive ventilation. The action mechanism of HFNC includes a decrease in nasopharyngeal resistance, washout of dead space, reduction in inflow of ambient air, and an increase in airway pressure. In preterm infants, HFNC can be used to prevent reintubation and initial noninvasive respiratory support after birth. In children, flow level adjustments are crucial considering their maximal efficacy and complications. Randomized controlled studies suggest that HFNC can be used in cases of moderate to severe bronchiolitis upon initial low-flow oxygen failure. HFNC can also reduce intubation and mechanical ventilation in children with respiratory failure. Several observational studies have shown that HFNC can be beneficial in acute asthma and other respiratory distress. Multicenter randomized studies are warranted to determine the feasibility and adherence of HFNC and continuous positive airway pressure in pediatric intensive care units. The development of clinical guidelines for HFNC, including flow settings, indications, and contraindications, device management, efficacy identification, and safety issues are needed, particularly in children.

• Korean Journal of Microbiology
• /
• v.24 no.3
• /
• pp.263-269
• /
• 1986

Membrane proteins of facultatively anaerobic Escherichia coli K12 which was logarithmically grown in aerobiosis and anaerobiosis were compared on 5 to 10% liner gradient gel electrophoresis (Na Dod $SO_4 -PAGE$). Membrane proteins were formed as different patterns between aerobiosis and anaerobiosis. Among them, 91Kdal protein (pbp1a) was not synthesized in aerobiosis and 60Kdal protein (fts cluster), in anaerobiosis. Thereby cells cultured aerobically were differenciated as diversiform cell shape, comparing cells cultured anaerobically and the latter were resistant to penicillin G. Thus it is believed that in facultative anaerobes atmospheric oxygen regulated the synthesis of membrane proteins and even the expression of equivalent genes, and moreover alleviated the resistance to an antibiotic penicillin.