• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.628-631
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• 2000

The timing of poly(3-Hydroxybutyrate) (PHB) biosynthesis was controlled by varying the agitation speed of a stirred tank fermentor during the pH-stat fed-batch culture of recombinant Escherichia coli strain GCSC 6576 harboring pSYL107. Using a concentrated whey solution containing ca. 200 g/l lactose as the nutrient feed, the PHB content was only 57% after 35h due to volumetric limitation of the fermentor. However, by limiting the oxygen by maintaining the agitation speed at 300 rpm, the final PHB content increased to 70% after 70h with a cell concentration of 15 g/l. When the agitation speed was increased up to 500 rpm, a cell concentration of 31 g/l with 80% PHB was obtained after 52h. A further increase in the maximum agitation speed increased the cell concentration, PHB concentration, and PHB productivity, however, the PHB content decreased to 56-58%.

• Journal of Preventive Medicine and Public Health
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• v.13 no.1
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• pp.13-18
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• 1980

The ultimate goal of treatment of carton monoxide poisoning is to promote dissociation of carboxyhemoglobin and to maintain arterial $PO_2$ above 50mmHg throughout the course of treatment to protect vital organs from damage caused by hypoxia. The hyperbaric chamber designed and manufactured for this purpose has obviousely made an enormous contribution and yet has several handicaps to be overcome by any means. These handicaps are: the financial impact to purchase the chamber (especially in a small, remote community), an extra manpower requirement to operate the device, limitation in the capacity of the chamber (one man type), and the possible hazard of oxygen intoxication and dysbarism. The primary objective of this study is to develope a new therapeutic measure as an alternative to the hyperbaric chamber when it is not available or contraindicated. The effect of intestinal perfusion with hydrogen peroxide has been studied by many investigators and was known to be an excellent way of extrapulmonary oxygen supply. the advantage of this method will include; 1) much more amount of oxygen is delivered to the tissue than one would expect from 100% saturation with oxygen at 1 ata, 2) the procedure is simple and most economical, 3) neither sophisticated equipment nor extra manpower is required. As a study preliminary to the clinical application, authors conducted a series of experiment to observe the effect of hydrogen peroxide enema on dissociation of carboxyhemoglobin in intoxicated rabbit blood. Using an animal gas chamber, 20 rabbits were exposed to CO gas of 6,000 ppm for 60 minutes. Ten rabbits of control group were given 10cc of warmed normal saline solution by reactal perfusion and for the other 10 of the experimental group, the same amount of 1% $H_{2}O_{2}$ solution was given by the same way. Two blood specimens were drawn from each rabbit: the first one immediately following the exposure and the second one after rectal perfusion, about 30 minutes after the first sampling. The result was as follows; 1) The decrease in carboxyhemoglobin concentration during the first 30 minutes in the control and experimental group were $18.18{\pm}4.49%\;and\;23.03{\pm}4.13%$ respectively shelving the significant difference (p<0.05) between the two groups. 2) Hemoglobin and hematocrit value showed no significant difference between two groups and not altered significantly by intestinal perfusion with $H_{2}O_{2}$.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.59-69
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• 2014

One of the major challenges in metabolic engineering for enhanced synthesis of value-added chemicals is to design and develop new strains that can be translated into well-controlled fermentation processes using bioreactors. The aim of this study was to assess the influence of various fed-batch strategies in the performance of metabolically engineered Pseudomonas putida strains, ${\Delta}gcd$ and ${\Delta}gcd-pgl$, for improving production of medium-chain-length polyhydroxyalkanoates (mcl-PHAs) using glucose as the only carbon source. First we developed a fed-batch process that comprised an initial phase of biomass accumulation based on an exponential feeding carbon-limited strategy. For the mcl-PHA accumulation stage, three induction techniques were tested under nitrogen limitation. The substrate-pulse feeding was more efficient than the constant-feeding approach to promote the accumulation of the desirable product. Nonetheless, the most efficient approach for maximum PHA synthesis was the application of a dissolved-oxygen-stat feeding strategy (DO-stat), where P. putida ${\Delta}gcd$ mutant strain showed a final PHA content and specific PHA productivity of 67% and $0.83g{\cdot}l^{-1}{\cdot}h^{-1}$, respectively. To our knowledge, this mcl-PHA titer is the highest value that has been ever reported using glucose as the sole carbon and energy source. Our results also highlighted the effect of different fed-batch strategies upon the extent of realization of the intended metabolic modification of the mutant strains.

• KSBB Journal
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• v.16 no.4
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• pp.415-419
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• 2001

To produce staphylokinase (SAK) in B. subtilis WB700, media optimization was carried out and the operation of batch and fed-batch fermentation were compared. Tryptone is a good nitrogen source and its optimum concentration in modified super rich(MSR) media is 15 g/L. When glucose is used as a limiting carbon source in the MSR media, 5 g/L of an optimum glucose concentration was identified for the SAK production under the control of P43 promoter. As the expression of P43 promoter is controlled by the limitation of oxygen, the SAK production was controlled at the 30% DO level in the fed-batch fermentation. Unexpectedly, batch fermentation using MSR media showed 1.5 times higher yield of SAK than that of the fed-batch fermentation. The main cause of the results comes from not achieving higher cell concentration in the fed-batch fermentation and the optimum expression level of P43 promoter under oxygen or nutrient limitations. We could not achieve the increase in cell concentration by any means in batch culture as well as fed-batch culture. The highest yield in the batch culture was 2880 units of SAK activity and 455 mg/L of secreted SAK.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4001-4007
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• 2011

In this study, we selected ten normal women in their 20's and 4 weeks measured Exercise Intensity, Voluntary Ventilation, Respiratory Exchange Ratio, Oxygen and Calorie Consumption and Ventilation Equivalent of them during Normal Gait, Splint-equipped Gait and Crutch Gait With Splint in order to find out whether the movement limitation and the weight of orthosis could have an effect on energy consumption. Each gait was conducted at a comfortable speed, 2.74 km/h for 30 minutes equipped with splint whose average weight is 1.2 kg. In the result of the study, The Crutch Gait With Splint showed high Exercise Intensity compaired to Normal Gait and Splint-equipped Gait. In addtion, in The Voluntary Ventilation and Oxygen Consumption, The Crutch Gait showed higher figures than two the others and the difference was significant as well(p<0.05). As for The Calorie Consumption, it also showed higher figures than two the others but the difference was not statistically significant. Finally, in The Respiratory Exchange Ratio and The Ventilation Equivalent, there was no significant difference among three conditional variables.

• Ocean and Polar Research
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• v.43 no.2
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• pp.65-72
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• 2021

In order to evaluate the dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM), as indicators of organic matter in the coastal environments, we measured the concentrations of DOC, FDOM, and chemical oxygen demand (COD) in saline groundwater (Woljeong, Pyoseon, and Hwasun beaches) and coastal seawater (Haengwon, Gwideok, Pyoseon, and Yeongnak) in Jeju, Korea. The highest concentrations of DOC and COD in groundwater were found in Woljeong and Pyoseon, and those in coastal water were observed in Haengwon and Pyoseon, indicating that the higher concentrations of DOC and COD seem to be associated with saline groundwater-driven dissolved organic matter (DOM) and/or biogeochemical processes. According to origin and optical properties of DOM using FDOM as a tracer, proportion of humic-like FDOM, more refractory DOM, was relatively greater in the groundwater than in the coastal water. With regard to this result, there was no relationship between DOC and COD in groundwater, while DOC showed a good positive correlation (r² = 0.66) with COD in coastal water. This result indicates that COD as an indicator of assessment of DOM has a limitation in which it is difficult to quantify refractory DOM. Although DOC is a potential alternative to COD in the coastal environments, particulate organic carbon cannot be negligible due to relatively higher concentration compared to the open ocean. Therefore, the use of total organic carbon (TOC) as a replacement of COD in the coastal ocean is important, and the evaluation criterion of the TOC is necessary in order to evaluate of organic matter indicator in the various coastal environments.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.100-101
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• 2012

The plasma damage free and room temperature processedthin film deposition technology is essential for realization of various next generation organic microelectronic devices such as flexible AMOLED display, flexible OLED lighting, and organic photovoltaic cells because characteristics of fragile organic materials in the plasma process and low glass transition temperatures (Tg) of polymer substrate. In case of directly deposition of metal oxide thin films (including transparent conductive oxide (TCO) and amorphous oxide semiconductor (AOS)) on the organic layers, plasma damages against to the organic materials is fatal. This damage is believed to be originated mainly from high energy energetic particles during the sputtering process such as negative oxygen ions, reflected neutrals by reflection of plasma background gas at the target surface, sputtered atoms, bulk plasma ions, and secondary electrons. To solve this problem, we developed the NBAS (Neutral Beam Assisted Sputtering) process as a plasma damage free and room temperature processed sputtering technology. As a result, electro-optical properties of NBAS processed ITO thin film showed resistivity of $4.0{\times}10^{-4}{\Omega}{\cdot}m$ and high transmittance (>90% at 550 nm) with nano- crystalline structure at room temperature process. Furthermore, in the experiment result of directly deposition of TCO top anode on the inverted structure OLED cell, it is verified that NBAS TCO deposition process does not damages to the underlying organic layers. In case of deposition of transparent conductive oxide (TCO) thin film on the plastic polymer substrate, the room temperature processed sputtering coating of high quality TCO thin film is required. During the sputtering process with higher density plasma, the energetic particles contribute self supplying of activation & crystallization energy without any additional heating and post-annealing and forminga high quality TCO thin film. However, negative oxygen ions which generated from sputteringtarget surface by electron attachment are accelerated to high energy by induced cathode self-bias. Thus the high energy negative oxygen ions can lead to critical physical bombardment damages to forming oxide thin film and this effect does not recover in room temperature process without post thermal annealing. To salve the inherent limitation of plasma sputtering, we have been developed the Magnetic Field Shielded Sputtering (MFSS) process as the high quality oxide thin film deposition process at room temperature. The MFSS process is effectively eliminate or suppress the negative oxygen ions bombardment damage by the plasma limiter which composed permanent magnet array. As a result, electro-optical properties of MFSS processed ITO thin film (resistivity $3.9{\times}10^{-4}{\Omega}{\cdot}cm$, transmittance 95% at 550 nm) have approachedthose of a high temperature DC magnetron sputtering (DMS) ITO thin film were. Also, AOS (a-IGZO) TFTs fabricated by MFSS process without higher temperature post annealing showed very comparable electrical performance with those by DMS process with $400^{\circ}C$ post annealing. They are important to note that the bombardment of a negative oxygen ion which is accelerated by dc self-bias during rf sputtering could degrade the electrical performance of ITO electrodes and a-IGZO TFTs. Finally, we found that reduction of damage from the high energy negative oxygen ions bombardment drives improvement of crystalline structure in the ITO thin film and suppression of the sub-gab states in a-IGZO semiconductor thin film. For realization of organic flexible electronic devices based on plastic substrates, gas barrier coatings are required to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency flexible AMOLEDs needs an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}gm^{-2}day^{-1}$. The key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required (under ${\sim}10^{-6}gm^{-2}day^{-1}$) is the suppression of nano-sized defect sites and gas diffusion pathways among the grain boundaries. For formation of high quality single inorganic gas barrier layer, we developed high density nano-structured Al2O3 single gas barrier layer usinga NBAS process. The NBAS process can continuously change crystalline structures from an amorphous phase to a nano- crystalline phase with various grain sizes in a single inorganic thin film. As a result, the water vapor transmission rates (WVTR) of the NBAS processed $Al_2O_3$ gas barrier film have improved order of magnitude compared with that of conventional $Al_2O_3$ layers made by the RF magnetron sputteringprocess under the same sputtering conditions; the WVTR of the NBAS processed $Al_2O_3$ gas barrier film was about $5{\times}10^{-6}g/m^2/day$ by just single layer.

• Journal of Microbiology and Biotechnology
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• v.21 no.6
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• pp.604-612
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• 2011

Beauveria bassiana SFB-205 supernatant can effectively control cotton aphid populations, which is closely associated with its chitinase activity. The present work extends to optimizing a culture medium to produce more efficacious supernatant in flask conditions, followed by scale-up in 7 L, 300 L and 1.2 KL fermentors with the parameter of chitinase. In flask conditions, a combination of soluble starch and yeast extract produced the greatest amount of chitinase (5.1 units/ml) and its supernatant had the highest aphicidal activity. An optimal quantitative combination of the two substrates, estimated by a response surface method, enabled the supernatant to have 15.7 units/ml of chitinase activity and 3.7 ml/l of median lethal concentration ($LC_{50}$) of toxicity against cotton aphid adults in laboratory conditions. In the scale-up conditions, overall supernatant had 25-28 units/ml of chitinase activity. Decrease in pH and limitation of dissolved oxygen (DO) during cultures were significantly related to the yield of chitinase. These results suggest that the substrate-dependent chitinase production can be background information for optimizing a culture medium, and pH and DO are critical factors in maximizing the production in scale-up conditions.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.22-27
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• 2002

The composting practice has been recognized as the most popular way of controlling food waste and many attempt have been made in the field to establish more efficient and economical process. Some of the efforts are mixing cured compost with sawdust as alternative bulking agent, seeding commercially produced microorganism and/or combination of above. However, verification of such efforts is often restricted because of either the lack of engineering consideration on the limitation of composting facility scales. In this study, the effect of mixing materials in food waste composting was investigated by controlling the combination and the mixing ratio of them. When the cured compost was mixed with saw dust. the decomposition of organic material was proven to be more active by observing the compost temperature, the oxygen (O$_2$) consumption, and the cumulative carbon dioxide ($CO_2$) profile. However, the quantity of compost mix-ing seemed not to influence the reaction as long as the minimum required amount was mixed. The feeding of com-mercially produced microorganism had a tendency to prolong the thermophilic stage, which helped to increase the decomposition but it resulted in composting period. Regardless of the composting condition, bacteria and actinomycetes increased in population as the reaction approached to the end. The population of bacteria and actinomycetes were rel-atively higher than those of fungi and yeast throughout the reaction.

• Journal of Biomedical Engineering Research
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• v.3 no.2
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• pp.95-100
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• 1982

Glucose oxidase from A. niger was entrapped in polyacrylamide gel which was used in the enzyme electrode for glucose analysis. The electrode was assembled by placing the gel between the membranes on the surface of a Clark type electrode. In order to make it possible to analyze the experimental results later, the stagnation flow was adopted wheree the governing fluid mechanics were well known. The current increased with the increase concentration in the bulk below a certain level of glucose concentration beyond which no more current increase was observed. This is probably due to the diffusion limitation of oxygen from the bulk solution. Also the current increased witll the enzyme loading in the gel, but the linearity between the current and the glucose concentration was rather limited to a narrow range. Flow rate was found to be very important, which means that film diffusion is very important under the flow rate of 5cm/sec. As a conclusion, enzyme loading, gel layer thickness, stirring speed and bulk concentration of glucose were found to be most improtant parameters in yielding a linar current reponse with respect to the bulk glucose concentration.