• Journal of Life Science
• /
• v.27 no.11
• /
• pp.1381-1392
• /
• 2017

This review described solvent-tolerant lipases and their potential industrial, biotechnological and environmental impacts. Although organic solvent-tolerant lipase was first reported in organic solvent-tolerant bacterium, many organic solvent-tolerant lipases are in not only solvent-tolerant bacteria but also solvent-intolerant bacterial and fungal strains, such as the well-known Bacillus, Pseudomonas, Streptomyces and Aspergillus strains. As these lipases are not easily inactivated in organic solvents, there is no need to immobilize them in order to prevent an enzyme inactivation by solvents. Therefore, the solvent-tolerant lipases have the potential to be used in many biotechnological and biotransformation processes. With the solvent-tolerant lipases, a large number insoluble substrates become soluble, various chemical reactions that are initially impossible in water systems become practical, synthesis reactions (instead of hydrolysis) are possible, side reactions caused by water are suppressed, and the possibility of chemoselective, regioselective and enantioselective transformations in solvent and non-aqueous systems is increased. Furthermore, the recovery and reuse of enzymes is possible without immobilization, and the stabilities of the lipases improve in solvent and non-aqueous systems. Therefore, lipases with organic-solvent tolerances have attracted much attention in regards to applying them as biocatalysts to biotransformation processes using solvent and non-aqueous systems.

• Journal of Life Science
• /
• v.19 no.11
• /
• pp.1568-1574
• /
• 2009

The purpose of this study was to investigate whether group III muscle afferents play an important role eliciting abnormal blood pressure response mediated during passive muscle stretch in prehypertensive individuals. Eleven middle-aged prehypertensive men (average BP 133/80 mmHg) and nine middle-aged normotensive men (average BP 119/74 mmHg) participated in this study. After 1 min rest baseline data collection, the subject's foot was flexed (dorsiflexion) by an automated cybex for one minute. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), heart rate, stroke volume, cardiac output, and total peripheral resistance were continuously measured on a beat-by-beat basis from a finger via a Finapres device for 1 minute. To evaluate the role of mechanoreflex, a component of exercise pressor reflex, SBP, DBP, and MAP responses over the course of time were examined. The results showed that the pressor response mediated by the muscle mechanoreflex was faster in prehypertensive individuals compared to the normotensive individuals. The substantial pressor response was observed within mean 20 sec of the onset of passive stretch in prehypertension, while mean 45 sec in normotension (p<0.05). It is concluded that excessive pressor response produced during exercise in prehypertension may be due to the dysfunction of the mechano-receptors.

• Clean Technology
• /
• v.14 no.3
• /
• pp.176-183
• /
• 2008

The purpose of this study is to upgrade the catalysts for synthesizing mixed octenes using normal butene and the catalysts for synthesizing $C_9$-aldehyde through hydroformylation of mixed octenes with syngas. The in-line activation method with circulating activating solution was effective for activation of the $NiO/A1_{2}O_3$ catalyst. The reason for catalyst deactivation may be ascribed to physi-sorbed materials or oligomers which block pore entrance and then prevent active sites from participating a reaction. Continuous distillation apparatus was used for separating mixed octenes from dimerization products. When reflux ratio was above 3 : 1, mixed octene fraction of which purity was above 99.57% was obtained. In $C_9$-aldehyde synthesis through hydroformylation of mixed octenes, we investigated a performance of ligand which increased catalyst stability as well as activity of Co catalyst. The results indicated that TPPO, NMP, NDMA, and succinonitrile were suitable ligand for increasing initial activity and reducing loss of Co during catalyst recovery.

• Clean Technology
• /
• v.24 no.4
• /
• pp.307-314
• /
• 2018

In this study, NMO (Natural Manganese Ore), $MnO_2$, and $Mn_2O_3$ catalysts were used in the selective catalytic reduction process to remove nitrogen oxides (NOx) using $NH_3$ as a reducing agent at low temperatures in the presence of oxygen. In the case of the NMO (Natural Manganese Ore), it was confirmed that the conversion of nitrogen oxides in the stability test did not change even after 100 hours at 423 K. The Kinetics experiments were carried out within the range where heat and mass transfer were not factors. From a steady-state Kinetics study, it was found that the low-temperature SCR reaction was zero order with the respect to $NH_3$ and 0.41 ~ 0.57 order with the respect to NO and 0.13 ~ 0.26 order with the respect to $O_2$. As temperature increases, the reaction order decreases as a result of $NH_3$ and oxygen concentration. It was confirmed that the reaction between the $NH_3$ dissociated and adsorbedon the catalyst surface and the gaseous nitrogen monoxide (E-R model) and the reaction with the adsorbed nitrogen monoxide (L-H model) occur.

• Journal of fish pathology
• /
• v.22 no.3
• /
• pp.335-342
• /
• 2009

The stability of immunoglobulin M (IgM) on different serum storage conditions and specific antibody response were tested using the serum collected from sevenband grouper Epinephelus septemfasciatus by enzyme-linked immunosorbent assay (ELISA). To test the effect of storage temperature and duration, sevenband grouper antiserum against bovine serum albumin (BSA) was stored at -80, -20 or 4${^{\circ}C}$ for 1, 34, 61 or 119 days. In addition, to test the effect of repeated freeze-thawing condition, the anti-BSA fish serum was frozen at -20 and -80${^{\circ}C}$ and then thawn and frozen for 1, 5 or 10 times repeatedly. Consequently, no significant difference was found in ELISA optical density (O.D.) values of sera for the above mentioned storage conditions: different temperatures (-80, -20 and 4${^{\circ}C}$), durations of storage (1, 34, 61 and 119 days), and repeated thaw-freeze cycles (1, 5, and 10 times), indicating that IgMs of test fish were stable. The specific antibody response of sevenband grouper was observed after BSA-immunization of the test fish reared at 20 ${^{\circ}C}$ or 25${^{\circ}C}$. At the rearing temperature of 20${^{\circ}C}$, the specific antibody against BSA first appeared at 14 days and maximum antibody titer was observed between 21 and 28 days, while at the rearing temperature of 25 ${^{\circ}C}$, specific antibody appeared at 7 days and maximum antibody titer was observed between 14 and 21 days. In conclusion, the rearing temperature at 25${^{\circ}C}$ gave a faster and higher specific antibody response than at 20${^{\circ}C}$ and the specific antibody response maintained for approximately 2 months at 20℃ and 25${^{\circ}C}$.

• Journal of the Korean Institute of Gas
• /
• v.27 no.1
• /
• pp.23-32
• /
• 2023

In this study, the Al₂O₃ nanofluid was synthesized as an additive for improving the injection efficiency and storage capacity of carbon dioxide (CO₂) in a depleted sandstone reservoir or deep saline aquifer. As the base fluid, deionized water (DIW) and saline prepared by referring to the composition of API Brine were used, and the fluid was synthesized by using Al₂O₃ nanofluid with CTAB (cetyltrimethyl-ammonium bromide), a cationic surfactant. After that, the dispersion stability was evaluated by using visual observation, dynamic light scattering (DLS), transmission electron microscope (TEM), and miscibility test. As a result, it was presented that stable nanofluid without agglomeration and precipitation after reaction with 70,000 ppm of brine could be synthesized when the nanoparticle concentration was 0.05 wt% or less.

• Applied Chemistry for Engineering
• /
• v.31 no.4
• /
• pp.404-410
• /
• 2020

In this study, the stability criteria of cosmeceuticals emulsion containing Flos Sophorae Immaturus extracts was established using the Box-Behnken design model (BBD-RSM). As optimization conditions of the emulsification using the BBD-RSM, the amount of surfactant and additive, and emulsification time and speed were used as quantitative factors while mean droplet size (MDS), viscosity and emulsion stability index (ESI) were used as reaction values. According to the result of BBD-RSM, optimum conditions for the emulsification were as follows; the emulsification time and speed of 17.8 min and 5505 rpm, respectively and amounts of the emulsifier and additive of 2.28 and 1.05 wt.%, respectively. Under these conditions, the MDS, viscosity, and ESI after 7 days from the reaction were estimated as 1875.5 nm, 1789.7 cP, and 93.8%, respectively. The average error value from our actual experiments for verifying the conclusions was below 5%, which is mainly due to the fact that the BBD-RSM was applied to the optimized cosmeceuticals emulsification.

• Science of Emotion and Sensibility
• /
• v.18 no.3
• /
• pp.63-70
• /
• 2015

This study identified heart response of participants while listening to sounds which have 1/f fluctuations with exponent ${\alpha}$ gradient. The participants were engaged in emotional stress work. Prior studies related to 1/f fluctuation sound have reported that sound source can alleviate psychological and physiological state of users. Subjects of this study were exposed to sound with three levels of ${\alpha}$ gradient. Heart response of subjects were measured with Photoplethysmography(PPG) sensor simultaneously. The dependent variables of this study were beat per minute(BPM), very low frequency percent of pulse rate variability (VLF percent), the standard deviation of all normal RR intervals (SDNN), and high frequency power(HF power). Subject showed arousal response when exposed to sound with exponent ${\alpha}$ gradient of 3 whereas the sound with exponent ${\alpha}$ gradient of 1 and 2 resulted in relax effect. The characteristic of 1/f fluctuation sounds can be applied to alleviate stress for employers under emotional labor.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.7 no.1
• /
• pp.181-190
• /
• 2003

The convergence-confinement method is an attempt to evaluate tunnel stability conditions by means of a mathematical model and a ground response curve. In this study, the convergence-confinement method by numerical model was examined. This method don't need the basic assumptions for a mathematical model. Also This is applicable to general tunnel. According to the results of this study, the change of shotcrete stiffness and the load-distribution ratio used for 2-Dimension numerical analysis are not signficant factors. The ground response curve and the support reaction curve are mutually dependent. Especially the support reaction curve depends upon the ground response curve. The mechanism of tunnel must be analyzed by the interaction between support and ground. Consequently the stability of tunnel must be qualitatively investigated by a ground response curve and quantitatively adjudged by a numerical analysis for the reasonable design of tunnel.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.4
• /
• pp.265-269
• /
• 2007

The effects of experimental variables for the electrochemical reduction of carbon dioxide by Carbon Monoxide Dehydrogenase (CODH) were investigated. It shows the pH optimum at 6.3 where the feasibility of electro-chemical reduction and the stability of CODH compromise each other. The optimum temperature for the reduction was at $60^{\circ}C$ where the enzyme shows the optimum activity although the solubility of carbon dioxide decreases as increasing temperature.