• Bulletin of the Korean Chemical Society
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• v.21 no.4
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• pp.393-400
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• 2000

2,2￠-Dihydroxyazobenzene (DHAB) was attached to poly(ethylenimine) (PEI) to obtain DHAB-PEI. Spectral titration revealed that uranyl, Fe(III), Cu(II), and Zn(II) ion form 1 : 1-type complexes with DHAB attached to PEI. Formation constants for the metal complexes formed by the DHAB moieties of DHAB-PEI were mea-sured by using various competing ligands. The results indicated thatthe concentrations of uranyl, Fe(III), and Cu(II) ions can be reduced to 10 -16 -10 -23 M at p 8 with DHAB-PEI when the concentration of the DHAB moiety is 1 residue M. By using cyanuric chloride as the coupling reagent, DHAB-PEI was immobilized on Sephadex G-25 resin to obtain DHAB-PEI-Seph. Binding of uranyl,Fe(III), Cu(II), and Zn(II) ion by DHAB-PEI-Seph was characterized by using competing ligands. A new method has been developed for characteriza-tion of metal sequestering ability of a chelating resin. Formation constants and metal-binding capacity of two sets of binding sites on the resin were estimated for each metal ion. DHAB-PI-Seph was applied to recovery of metals such as uranium,Fe, Cu, Zn, Pb, V, Mn, and W from seawater. The uranium recovery from seawaterby DHAB-PEI-Seph does not meet the criterion for economical feasibility partlydue to interference by Fe and Zn ions. The seawater used in the experiment was contaminated by Fe and Zn and, therefore, the efficiency of uranium extractionfrom seawater with DHAB-PEI-Seph could be improved if the experiment is carried out in a cleaner sea.

• Analytical Science and Technology
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• v.35 no.5
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• pp.218-227
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• 2022

A simple and fast throughput flow injection (FI) system with a merging-zone technique was designed to determine ferrous and ferric in an aqueous solution. The method is based on the direct reaction of ferrous with a Bathophenanthroline reagent (Bphen) in acidic media. The forming red complex absorbs light at 533 nm. All conditions of the flow injection system were investigated. The analytical curve of ferrous was linear in the range of 0.07 to 4 mg/L with an r² value of 0.9968. The detection and quantification limits were 0.02 and 0.04 mg/L, respectively. The molar absorptivity and Sandell's sensitivity were 4.0577 × 10⁶ L/mol cm and 25 × 10^-5 ㎍/cm², respectively. The homemade valve was low-cost with high repeatability (n = 7) at an RSD of 1.26 % and zero dead volume. The values of the dispersion coefficient were 2.318, 2.022, and 1.636 for the concentrations of 0.2, 1, and 3 mg/L, respectively. The analysis throughput of the designed flow injection unit was 57 sample per hour.

• Korean Journal of Veterinary Research
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• v.33 no.1
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• pp.61-69
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• 1993

In order to search for new antibiotics from anaerobic bacteria, a large number of samples from domestic soil were collected and processed by apropriate methods. A potential strain, Streptococcus sp. An-21-1, was found to produce antimicrobial compounds. The Results were as follows; 1. During fermentation, the bacteria grew rapidly up to 20hr, thereafter entered the death phase. The optimal temperature and pH for the bacterial growth were $37^{\circ}C$ and pH 7.0, respectively. 2. Antibiotics were purified from culture broth by solvent extraction, silica gel column chromatography and Sepadex L.H 20 column. 3. Physicochemical properties of Ap-1 and Ap-2 were similar ; Their melting points were between $234-237^{\circ}C$. Color reactions of ninhydrin, 2,7-dichlorofluorescein, 4-dimethylaminobenzaldehyde, Dragendroffs reagent and 20% $H_2SO_4$, were positive. Therefore, we assumed that these antibiotics have amine group, immine group, alkaloid, and lipid components. These were stable to heat. UV spectrophotometry showed two peaks at 210 nm and 260 nm. From above results, we assumed these antibiotics are belong to the peptide antibiotic family.

• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1849-1855
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• 2015

Staphylococcus aureus plays an important role in sepsis, septic shock, pneumonia, and wound infections. Here, we demonstrate that Lactobacillus plantarum extracts inhibited S. aureus-induced cell death of a human epithelial cell line, HT-29. In particular, we have shown that S. aureus-induced cell death was abolished by neutralization of α-toxin, indicating that α-toxin is the major mediator of S. aureus-induced cell death. DNA fragmentation experiment and caspase assay revealed that the S. aureus-induced cell death was apoptosis. L. plantarum extracts inhibited the generation of effector caspase-3 and the initiator caspase-9 in S. aureus- or α-toxin-induced cell death. Moreover, expression of Bcl-2, an anti-apoptotic protein, was activated in L. plantarum extract-treated cells as compared with the S. aureus- or α-toxin-treated only cells. Furthermore, S. aureus-induced apoptosis was efficiently inhibited by lipoteichoic acid and peptidoglycan of L. plantarum. Together, our results suggest that L. plantarum extracts can inhibit the S. aureus-mediated apoptosis, which is associated with S. aureus spreading, in intestinal epithelial cells, and may provide a new therapeutic reagent to treat bacterial infections.

• Journal of Microbiology and Biotechnology
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• v.30 no.1
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• pp.146-154
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• 2020

With the advantages of biocatalytic method, enzymes have been excavated for the synthesis of chiral amino acids by the reductive amination of ketones, offering a promising way of producing pharmaceutical intermediates. In this work, a robust phenylalanine dehydrogenase (PheDH) with wide substrate spectrum and high catalytic efficiency was constructed through rational design and active-site-targeted, site-specific mutagenesis by using the parent enzyme from Bacillus halodurans. Active sites with bonding substrate and amino acid residues surrounding the substrate binding pocket, 49L-50G-51G, 74M,77K, 122G-123T-124D-125M, 275N, 305L and 308V of the PheDH, were identified. Noticeably, the new mutant PheDH (E113D-N276L) showed approximately 6.06-fold increment of k_cat/Km in the oxidative deamination and more than 1.58-fold in the reductive amination compared to that of the wide type. Meanwhile, the PheDHs exhibit high capacity of accepting benzylic and aliphatic ketone substrates. The broad specificity, high catalytic efficiency and selectivity, along with excellent thermal stability, render these broad-spectrum enzymes ideal targets for further development with potential diagnostic reagent and pharmaceutical compounds applications.

• Journal of Biosystems Engineering
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• v.30 no.4 s.111
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• pp.242-248
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• 2005

There was no useful milling standard to produce high quality milled rice efficiently and adequately in Rice Processing Complex. Therefore, the whiteness of milled rice produced Rice Processing Complexes were different according to Rice Processing Complexes and milling periods at the same Rice Processing Complex. This research was carried out to contribute the production and distribution of high quality milled rice through determination of whiteness condition of milled rice as a milling stndard based on degree of bran removal using New $May-Gr\ddot{u}wald$ reagent dyeing method and taste of cooked rice. The optimum whiteness value of milled rice for efficient milling in Rice Processing Complex was found to be from 40 to 41, while the degree of milling was from $8.9\%\;to\;9.2\%.$ At this whiteness condition, the first derivative of whiteness value according to degree of milling was higher than the average value from brown rice to well milled rice, and the broken kernel ratio was from $3.0\%\;to\;3.4\%.$ This whiteness condition ($40\~41$) could be considered as a milling condition in Rice Processing Complex.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.453-463
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• 1996

The chlorination of reagent PbS and natural ore galena with $NH_4Cl$ was investigated to find a new extraction metallurgical process of lead. The proper conditions for the chlorination of galena were that reaction temperature ; $425^{\circ}C$, $NH_4Cl$ weight ratio to galena ; 4.0 and reaction time ; 2hrs. Under these conditions, PbS was successfully chlorinated to $PbCl_2$ and the conversion was 90%. And also $NH_4Cl$ was effectively decomposed and was separated $NH_3$ and HCl. HCl was a chlorinating agent and 90% of $NH_3$ was recovered through this chlorination reaction.

• YAKHAK HOEJI
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• v.41 no.6
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• pp.698-703
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• 1997

Recently, l-deprenyl (selegiline), a relative new antiparkinson`s drug, has been marketed in Korea. As its metabolites, l-methamphetamine and l-amphetamine, are the enantiomers of illicit drugs,d-methamphetamine and d-amphetamine, a method for analysis of enantiomers of methamphetamine and amphetamine in rat urine was investigated. The optical isomers of methamphetamine and amphetamine were analyzed with the chiral derivatizing reagent (S)-(-)-N-(trifluoroacetyl)-prolyl chloride (l-TFP), which was used to form the diastereomers of methamphetamine and amphetamine. And all diastereomers (l-TFP -l-AM, lTFP-d-AM, l-TFP-l-MA & l-TFP-d-MA) were well resolved by capillary gas chromatography. After administration of 10mg/kg l-deprenyl to rat, l-methamphetamine and l-amphetamine were detected without autoracemization to the d form in all urine samples collected during 24hrs, and the ratios of l-amphetamine/l-methamphetamine were 1.1~3.3. l-Amphetamine was detected in only 3 out of 8 urine samples collected during 24~48hrs where as no l-methamphetamine was detected in all cases.

• Journal of the Korean Chemical Society
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• v.34 no.1
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• pp.98-101
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• 1990

A new spectrophotometric determination method of scandium in the tin slag solution has been investigated using methyl thymol blue as a colorimetric reagent. Scandium is recovered by the anion exchange resin, Amberlite IRA 400, using the mixture solution of ammonium sulfate and sulfuric acid and an eluent. The mole ratio of complex of scandium and MTB at pH 6 is 1 to 1 and the wave length of the maximum absorbance is 585 nm and the molar absorptivity at this wave length is $2.0 {\times} 10^4\;\iota{\cdot}mol^{-1}{\cdot}cm^{-1}$. When tin slag solution is loaded into anion exchange resin and eluted, ions in the solution except scandium ion are eluted rapidly and scandium is eluted lately. So scandium is recovered easily.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.447-452
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• 2013

In this study we report a new method for the synthesis of a silica monolithic column bed with bimodal pores (throughpores and mesopores). The template induced synthesis method was used to direct bimodal pores simultaneously instead of the usual post base-treating method. Block polymer Pluronic F127 was chosen as a dual-function template to form hierarchically porous silica monolith with both macropores and mesopores. This is a simplification of the method of monolithic column preparation. Poly(ethylene glycol) was used as a partial substitute for F127 can effectively prevent shrinkage during the monolith aging process without losing much surface area (944 $m^2/g$ to 807 $m^2/g$). More importantly, the resultant material showed a much narrower mesopore size (centered at 6 nm) distribution than that made using only F127 as the template reagent, which helps the mass transfer process. The solvent washing method was used to remove the remaining organic template, and it was proved to be effective enough. The new synthesis method makes the fabrication of the silica monolithic column (especially capillary column) much easier. All the structure parameters indicate that monolith PFA05 prepared by the above method is a good material for separation, with the merits of much higher surface area than usual commercial HPLC silica particles, suitable mesopore volume, narrow mesopore size distribution, low shrinkage and it is easily prepared.