• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1229-1243
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• 2013

In this paper, an air isolate (NITT6L) has been screened based on hemolytic activity, emulsification activity, drop collapsing test, and oil displacement test, as well as lipase activity. It was found that strain NITT6L was able to reduce the surface tension of the medium from 61.5 to 39.83 mN/m and could form stable emulsions with tested vegetable oils. Morphological, biochemical, 16S rRNA sequencing analyses, and fatty acid methyl ester analysis using gas chromatography confirmed that the air isolate under study was Pseudomonas aeruginosa. Characterization of the biosurfactant using agar double diffusion assay revealed that the biosurfactant was anionic in nature, and CTAB-methylene blue assay and Molisch test revealed its glycolipid nature. The FT-IR spectrum confirmed that the crude biosurfactant was a rhamnolipid. Using unoptimized medium containing sucrose as the carbon source, the isolate was found to produce 0.3 mg/ml of rhamnolipid in batch cultivation (shake flask) at $37^{\circ}C$ and pH 7. Optimization of the medium components was carried out using design of experiments and the yield of rhamnolipid has been enhanced to 4.6 mg/ml in 72 h of fermentation.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3405-3410
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• 2011

We have investigated the cytotoxic potential of tellurium (Te) nanowires in BALB/3T3 fibroblast cells. Te nanowires were synthesized through an aqueous phase surfactant assisted method. Toxicological experiments, such as analysis of morphological changes, MTT assay, DAPI staining, and estimation of intracellular reactive oxygen species, were carried out to reveal the cytotoxic effects of Te nanowires. Te nanowires were found to be cytotoxic at all concentrations tested, in a dose-dependent manner. The UV/Vis spectra of Te nanowires suspended in a culture medium showed drastic changes and disappearance of two broad absorption peaks. The physicochemical properties such as, surface charge, size, and shape of Te nanowires were found to be altered during exposure of cells, due to the instability and agglomeration of nanowires in the culture medium. These results suggest that the chemical components of the DMEM medium significantly affect the stability of Te nanowires. In addition, TEM images revealed that necrosis was the basic pattern of cell death, which might stem from the formation of toxic moieties of tellurium, released from nanowire structures, in the bioenvironment. These observations thus suggest that Te nanomaterials may pose potential risks to environmental and human health.

• Korean Chemical Engineering Research
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• 제45권1호
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• pp.103-108
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• 2007

HAZOP 기법은 전문가의 경험과 지식을 기초로 브레인스토밍(brainstorming) 방식을 적용함으로써 체계적으로 잠재 위험을 분석, 평가하는 방법으로 검토 시 누락의 가능성을 배제하고 비교적 객관화된 평가서를 작성할 수 있는 장점으로 인하여 널리 이용되고 있다. 그러나 대규모 화학공장에서는 HAZOP 기법을 이용한 위험성 평가의 실시 및 그 결과의 활용이 잘 이루어지고 있으나, 중 소 화학공장들의 경우 기법 적용이 용이하지 못하여 현실적으로 많은 어려움을 겪고 있다. 이에 본 연구에서는 기존에 많이 사용되고 있는 위험성 평가 기법들의 장 단점을 분석 검토하여 중 소 화학공장의 현장에 적용하기 쉬운 위험성 평가 기법을 제시함으로써 사업장 위험 관리 수준의 향상에 기여하고자 하였다.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3539-3543
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• 2012

Butacaine sulfate is an ester of p-aminobenzoic acid which has been widely used as a local anaesthetic and it is a long standing agent particularly for spinal anaesthesia. For this reason, a kinetic study of oxidation of butacaine sulfate by sodium N-chlorobenzenesulfonamide (chloramine-B or CAB) has been carried out in $HClO_4$ medium at 303 K in order to explore this redox system mechanistic chemistry. The rate shows a first-order dependence on both $[CAB]_o$, and $[substrate]_o$, and a fractional-order dependence on acid concentration. Decrease of dielectric constant of the medium, by adding methanol, increases the rate of the reaction. Variation of ionic strength and addition of benzenesulfonamide or NaCl have no significant effect on the rate. The reaction was studied at different temperatures and the activation parameters have been evaluated. The stoichiometry of the reaction has been found to be 1:2 and the oxidation products have been identified by spectral analysis. The observed results have been explained by plausible mechanism and the related rate law has been deduced.

• International Journal of Quality Innovation
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• 제8권1호
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• pp.99-119
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• 2007

This research probes into the execution of small and medium-sized enterprises' value creativities by a difference analysis with different classifications, different capital, different turnover, different employees, and different established years. This study develop a questionnaire about value creativity with five dimensions and thirty-five items according to "Valuation" by McKinsey and Company, Inc. and Copeland et al., such as: "Aspiration and target," "Portfolio management," "Organization design," "Process management," and "Business and individual performance management." The results are as follows: (1) Most small and medium-sized enterprises (SMEs) have executed value creativities; (2) There is a difference in the execution of value creativities between the livelihood industry and the chemical industry; the execution of value creativities by livelihood industry is better than the chemical industry; (3) For value creativities of the execution of different capital and turnover for SMEs, bigger entities are better than smaller ones; (4) For the value creativities of the execution of different numbers of staff in SMEs, those with more staff are better than those with fewer staff; (5) For the value creativities of the execution of different established years for SMEs, those established longer are better than those established shorter.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2011년도 추계학술발표회 논문집
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• pp.43-47
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• 2011

In woody waste separated from municipal solid waste, medium density fiberboard was major contributors with particleboard, paper, plywood and log, with different composition based on collected period. In chemical compositional analysis of woody waste, it was similar to softwood based on carbohydrate composition analysis. Based on the carbohydrate composition, saccharified solution from MWW could be good resource for biorefinery.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권2호
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• pp.150-155
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• 2001

It has been observed that water, which is absolutely essential for enzyme activity, can induce the agglomeration of enzyme particles in organic media. Although enzyme agglomeration is significant in that it usually reduces enzyme activity and stability, little attention has been paid to the quantitative analysis of enzyme agglomeration behavior in nonaqueous biocatalytic systems. In this study, the effect of water and silica gel on enzyme agglomeration were investigated using Candida rugosa lipase and cyclohexane as a model enzyme and an organic medium. The extent of enzyme agglomeration was quantified by sieve analysis of freeze-dried agglomerates. Increasing the water content of the medium increased the size of the enzyme agglomerates, and it was found that water produced during the esterification reaction could also promote the agglomeration of enzyme particles suspended in organic media. On the other hand, the size of the enzyme agglomerates was remarkably reduced in the presence of silica gel at the same water content. We also show that this increase in the size of enzyme agglomerates results in lower reaction rates in organic solvents.

• Korean Chemical Engineering Research
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• 제59권1호
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• pp.138-151
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• 2021

The effect of a reactant ratio on the growth of a buoyancy-driven instability in an irreversible A+B→C reaction system is analyzed theoretically and numerically. Taking a non-stoichiometric reactant ratio into account, new linear stability equations are derived without the quasi-steady state assumption (QSSA) and solved analytically. It is found that the main parameters to explain the present system are the Damköhler number, the dimensionless density difference of chemical species and the ratio of reactants. The present initial grow rate analysis without QSSA shows that the system is initially unconditionally stable regardless of the parameter values; however, the previous initial growth rate analysis based on the QSSA predicted the system is unstable if the system is physically unstable. For time evolving cases, the present growth rates obtained from the spectral analysis and pseudo-spectral method support each other, but quite differently from that obtained under the conventional QSSA. Adopting the result of the linear stability analysis as an initial condition, fully nonlinear direct numerical simulations are conducted. Both the linear analysis and the nonlinear simulation show that the reactant ratio plays an important role in the onset and the growth of the instability motion.

• 한국미생물·생명공학회지
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• 제47권4호
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• pp.614-620
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• 2019

Microalgae have been explored as potential host species for biofuel production. Environmental factors affect algal growth and cellular composition. The effects of several key environmental factors, such as temperature, light, and pH of the medium on the growth and biochemical composition of Scenedesmus obliquus were investigated in this study. The highest growth rate of microalgae was observed at an optimal temperature of 25℃, 150 μmol/(m²·s) light intensity, and pH 10.0. The biochemical composition analysis revealed that the carbohydrate content decreased at lower (20℃) or higher temperature (35℃), whereas the protein and lipid contents increase at these temperatures. The fluctuation of light intensity significantly affected the contents of protein, carbohydrate, and lipid. The protein levels varied greatly when the pH of the medium was below 7.0. The carbohydrate and lipid contents significantly increased at pH above 7.0.

• 기술사
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• 제34권3호
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• pp.22-27
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• 2001

About 70% -80% of the serious injury that occure in the chemical product small manufacturing industries is caused by human error. but technical development for analysis and inspection to preestimate and exclude such human error is still insufficient. Small - to - medium sited enterprises are economically vulnerable and technical foundations for safety management is week Under such circumstances development of easy to use computerized support programs that can be operated without the help of professioanals are keenly needed.