• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.584-590
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• 2011

This study aimed to demonstrate the bioadhesive characteristics of gelatin biofilm to rat skin. The biofilm was manufactured from gelatin extracted from the acetic acid treated-skin of the yellowfin tuna Thunnus albacares. The bioadhesive strength of tuna gelatin biofilm was compared to that of porcine gelatin biofilm. The tuna gelatin biofilm exhibited a higher bioadhesive strength than the porcine gelatin biofilm. Gelatin biofilm was subjected to glutaraldehyde treatment at different concentrations, temperatures and pH in order to improve its bioadhesive strength. Glutaraldehyde treatment improved the bioadhesive strength of gelatin biofilm up to three-fold. The bioadhesive strength of glutaraldehyde treated-biofilm was significantly decreased by application of sodium borohydride.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.379-385
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• 2005

Effects of Co and Co-P catalysts on the hydrolysis of alkaline $NaBH_4$ solution were investigated. Co and Co-P catalysts were prepared on Cu substrate by electroplating. Hydrogen generation rate of Co-P catalyst was much faster than that of Co catalyst, demonstrating that Co-P had higher intrinsic catalytic activity for the hydrolysis of $NaBH_4$ than Co. Hydrogen generation properties of Co-P catalysts largely depended on cathodic current density and electroplating time because they influenced on the P concentration of the Co-P catalysts. Maximum hydrogen generation rate of Co-P catalyst was 1066 ml/min.g-catalyst in 1 wt.% NaOH + 10 wt.% $NaBH_4$ solution at $20^{\circ}C$, which was obtained at cathodic current density of $0.01\;A/cm^2$ for 130 s.

• Journal of Microbiology
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• v.43 no.1
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• pp.28-33
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• 2005

The purpose of this study was to develop a multipurpose incubator, without the gas cylinders (bottles) which are required for $H_2$ and $CO_2$ supplementation. In our bottle-free multipurpose incubator, the $H_2$ and $CO_2$ were generated by chemical reactions induced within the chamber. The reaction between sodium borohydride and acetic acid at a molar ratio of 1:1 was used to generate $H_2$, according to the following formula: $4NaBH_4+2CH_3COOH+7H_2O{\rightarrow} 2CH_3COONa+Na_2B_4O_7+16H_2$, whereas the other reaction, citric acid and sodium bicarbonate at a 1:1 molar ratio, was used to generate $CO_2$, according to the following formula: $C_6H_8O_7+3NaHCO_3{\rightarrow}Na_3(C_6H_5O_7)+3H_2O+3CO_2$. Five species of obligate anaerobic bacteria, one strain of capnophilic bacterium, and one strain of microaerophilic bacterium were successfully cultured in the presence of their respective suitable conditions, all of which were successfully generated by our bottle-free multipurpose incubator. We conclude that, due to its greater safety, versatility, and significantly lower operating costs, this bottle-free multipurpose incubator can be used for the production of fastidious bacterial cultures, and constitutes a favorable step above existing anaerobic incubators.

• Bulletin of the Korean Chemical Society
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• v.16 no.5
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• pp.416-421
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• 1995

The approximate rates and stoichiometry of the reaction of excess lithium gallium hydride with selected organic compounds containing representative functional groups were examined under the standard conditions (diethyl ether, 0 $^{\circ}C)$ in order to compare its reducing characteristics with lithium aluminum hydride and lithium borohydride previously reported, and enlarge the scope of its applicability as a reducing agent. Alcohols, phenol, and amines evolve hydrogen rapidly and quantitatively. However lithium gallium hydride reacts with only one active hydrogen of primary amine. Aldehydes and ketones of diverse structure are rapidly reduced to the corresponding alcohols. Conjugated aldehyde and ketone such as cinnamaldehyde and methyl vinyl ketone are rapidly reduced to the corresponding saturated alcohols. p-Benzoquinone is mainly reduces to hydroquinone. Caproic acid and benzoic acid liberate hydrogen rapidly and quantitatively, but reduction proceeds slowly. The acid chlorides and esters tested are all rapidly reduced to the corresponding alcohols. Alkyl halides and epoxides are reduced rapidly with an uptake of 1 equiv of hydride. Styrene oxide is reduced to give 1-phenylethanol quantitatively. Primary amides are reduced slowly. Benzonitrile consumes 2.0 equiv of hydride rapidly, whereas capronitrile is reduced slowly. Nitro compounds consumed 2.9 equiv of hydride, of which 1.9 equiv is for reduction, whereas azobenzene, and azoxybenzene are inert toward this reagent. Cyclohexanone oxime is reduced consuming 2.0 equiv of hydride for reduction at a moderate rate. Pyridine is inert toward this reagent. Disulfides and sulfoxides are reduced slowly, whereas sulfide, sulfone, and sulfonate are inert under these reaction conditions. Sulfonic acid evolves 1 equiv of hydrogen instantly, but reduction is not proceeded.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.257-260
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• 1987

The asymmetric reduction of representative prochiral ${\alpha},{\beta}$-acetylenic ketones with a new chiral borohydride reducing agent, potassium 9-0-(1,2: 5,6-Di-O-isopropylidene-${\alpha}$ -D-glucofuranosyl)-9-boratabicyclo[3.3.1]nonane, 1, in THF at $-78^{\circ}C$ was studied. Structurally different acetylenic ketones such as internal ${\alpha},{\beta}$-acetylenic ketones $RC {\equiv} CCOCH_3$ and terminal ${\alpha},{\beta}$-acetylenic ketones $HC {\equiv} CCOR$ were chosen. Thus, the reduction of internal ${\alpha},{\beta}$-acetylenic ketones yields the corresponding propargyl alcohols, such as 67% ee for 3-hexyn-2-one, 75% ee for 5-methyl-3-hexyn-2-one, 86% ee for 5,5-dimethyl-3-hexyn-2-one, 74% ee for 3-nonyn-2-one and 61% ee for 4-phenyl-3-butyn-2-one. Terminal ${\alpha},{\beta}$-acetylenic ketones, such as 3-butyn-2-one, 1-pentyn-3-one, 4-methyl-1-pentyn-3-one and 1-octyn-3-one, are reduced to the corresponding alcohols with 59% ee, 17% ee, 44% ee and 12% ee of optical induction respectively. With one exception (4-methyl-1-pentyn-3-one), all propargyl alcohols obtained are enriched in R-enantiomers.

• Journal of Soil and Groundwater Environment
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• v.25 no.4
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• pp.28-34
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• 2020

Nitrate released from chemical fertilizer, animal wastes, and synthetic detergents can cause methemoglobinemia to infants, thus the standard in drinking water is set to 10 mg/L as World Health Organization recommended. In this study, zero-valent iron-modified rice straw biochar was used to reduce and remove nitrate in the aqueous phase. The rice straw biochar was prepared by pyrolyzing the biomass at 700℃ for 3 hours, and the biochar was modified using 1 M Fe(III), and the Fe(III) on the biochar was reduced to zero-valent iron using sodium borohydride. The modified biochar removed nitrate effectively, which removed more than 91% of nitrate. For the synthetic groundwater, the nitrate removal was lowered to 82% due to the presence of other anions.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.6
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• pp.465-470
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• 2004

Optimal conditions for the in situ immobilization of lipase in aldehyde-silica packed columns, via reductive amination, were investigated. A reactant mixture, containing lipase and sodium borohydride (NaCBH), was recirculated through an aldehyde-silica packed column, such that the covalent bonding of the lipase, via amination between the amine group of the enzyme and the aldehyde terminal of the silica, and the reduction of the resulting imine group by NaCBH, could occur inside the bed, in situ. Mobile phase conditions in the ranges of pH $7.0{\~}7.8$, temperatures between $22{\~}28^{circ}C$ and flow rates from $0.8{\~}1.5\;BV/min$ were found to be optimal for the in situ immobilization, which routinely resulted in an immobilization of more than 70 mg­lipase/g-silica. Also, the optimal ratio and concentration for feed reactants in the in situ immobilization: mass ratio [NaCBH]/[lipase] of 0.3, at NaCBH and lipase concentrations of 0.75 and 2.5 g/L, respectively, were found to display the best immobilization characteristics for concentrations of up to 80 mg-lipase/g-silica, which was more than a 2-fold increase in immobilization compared to that obtained by batch immobilization. For tributyrin hydrolysis, the in situ immobilized lipase displayed lower activity per unit mass of enzyme than the batch-immobilized or free lipase, while allowing more than a $45\%$ increase in lipase activity per unit mass of silica compared to batch immobilization, because the quantity of the immobilization on silica was aug­mented by the in situ immobilization methodology used in this study.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.194-201
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• 2009

The e1ectrocatalytic properties of heteropolyacids(HPAs) entrapped in covalently cross-linked sulfonated polyetheretherketone(CL-SPEEK/HPA) membranes have been studied for water electrolysis. The HPAs, including tungstophosphoric acid(TPA), molybdophosphoric acid(MoPA), and tungstosilicic acid(TSiA) were used as additives in the composite membranes. The MEA was prepared by a non-equilibrium impregnation-reduction(I-R) method, using reducing agent, sodium borohydride(NaBH4) and tetraamineplatinum(II) chloride(pt(NH$_3$)$_4$Cl$_2$). The electrocatalytic properties of composite membranes such as the cell voltage were in the order of magnitude CL-SPEEKlMoPA40 (wt%) > /TPA30 > /TSiA40. In the optimum cell applications for water electrolysis, the cell voltage of PtlPEM/Pt-Ru MEA with CL-SPEEKlTPA30 membrane was 1.75 V at 80$^{\circ}$C and I A/cm$^2$ and this voltage carried lower than that of 1.81 V of Nafion 117. Consequently, in regards of electrochemical and mechanical characteristics and oxidation durability, the newly developed CL-SPEEKITPA30 composite membrane exhibited a better performance than the others, but CLSPEEKlMoPA40 showed the best electrocatalytic activity (1.71 Vat 80$^{\circ}$C and 1 A/cm$^2$) among the composite membranes.

• Journal of Microbiology and Biotechnology
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• v.20 no.7
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• pp.1061-1068
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• 2010

The biological synthesis of nanoparticles has gained considerable attention in view of their excellent biocompatibility and low toxicity. We isolated and purified rhamnolipids from Pseudomonas aeruginosa strain BS-161R, and these purified rhamnolipids were used to synthesize silver nanoparticles. The purified rhamnolipids were further characterized and the structure was elucidated based on one- and two-dimensional $^1H$ and $^{13}C$ NMR, FT-IR, and HR-MS spectral data. Purified rhamnolipids in a pseudoternary system of n-heptane and water system along with n-butanol as a cosurfactant were added to the aqueous solutions of silver nitrate and sodium borohydride to form reverse micelles. When these micelles were mixed, they resulted in the rapid formation of silver nanoparticles. The synthesized nanoparticles were characterized by UV-Visible spectroscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy (EDS). The nanoparticles formed had a sharp adsorption peak at 410 nm, which is characteristic of surface plasmon resonance of the silver nanoparticles. The nanoparticles were monodispersed, with an average particle size of 15.1 nm (${\sigma}={\pm}5.82$ nm), and spherical in shape. The EDS analysis revealed the presence of elemental silver signal in the synthesized nanoparticles. The formed silver nanoparticles exhibited good antibiotic activity against both Grampositive and Gram-negative pathogens and Candida albicans, suggesting their broad-spectrum antimicrobial activity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.627-633
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• 2011

Performance of a hydrogen generator for a fuel cell unmanned aircraft was evaluated as the change of temperature environment. Sodium borohydride ($NaBH_4$) was used as a hydrogen source due to its high hydrogen content and good storability. The hydrogen gas was generated by the hydrolysis reaction using a catalytic reactor. Reaction chambers were set up with the range of temperatures from -20 to $60^{\circ}C$. The hydrogen generation rate and temperatures changes of reactor and separator were measured at the $NaBH_4$ concentrations of 20 and 25wt.%. As a result, the hydrogen generation rate was decreased as the repeated reaction cycles. It showed that the hydrogen generation rate was stable at low temperature, while at high temperature the hydrogen generation rate was rapidly decreased. The performance degradation was mainly caused by the catalyst loss and $NaBO_2$ deposition on the catalyst surface.