• Journal of Microbiology and Biotechnology
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• v.7 no.6
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• pp.378-385
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• 1997

Cation motive ATPases on cell membranes of Helicobacter pylori were investigated using everted membrane vesicles. Latent ATPases could be ascertained from aggregated vesicle using N, N-dimethylformamide (DMF) and Triton X-100. By contrast, ultrasonication or chloroform treatments caused membranes to be disrupted, resulting in an alteration of sensitivities against azide or vanadate. Considerable amounts of vanadate-sensitive enzymes were identified from vesicle micelles, prepared by the dilution method. These were activated in the presence of either $Ni^{2+}\;or\;NH_4^+$. From studies employing H. pylori intact cell systems, we found that ATPase expression of this bacterium was markedly dependent upon air composition. It was interesting that cellular expression of $Ni^{2+}$- or $NH_4^{+}$-motive ATPases was significantly affected by extracellular pH, suggesting that these unique enzymes may physiologically be involved in cellular $Ni^2$ import and $NH_4^+$ export, respectively.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.181-186
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• 2008

2,5-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (3) was prepared and polycondensed with terephthaloyl chloride, adipoyl chloride, and sebacoyl chloride to yield novel T-type polyesters (4-6) containing the NLO-chromophores dioxynitrostilbenyl groups, which constituted parts of the polymer backbones. Polymers 4-6 are soluble in common organic solvents such as acetone and N,N-dimethylformamide. They showed thermal stability up to 260 oC in thermogravimetric analysis with glass-transition temperatures obtained from differential scanning calorimetry in the range 90-95 oC. The second harmonic generation (SHG) coefficients (d33) of poled polymer films at the 1064 nm fundamental wavelength were around 1.42 ´ 10-9 esu. The dipole alignment exhibited high thermal stability up to 5 oC higher than glass-transition temperature (Tg), and there was no SHG decay below 100 oC due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.592-601
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• 2013

This work, which was about the synthesis of 3-(1,8-Naphthalimido) propyl methacrylate and GMA copolymers and their physical properties, investigated the compositions of the copolymer, the reactivity ratios of the monomer, resonance effect(Q), polar effect(e) and fluorescence effect of 1,8-naphthalicanhydride. Azobisisobutyronitronitryl(AIBN) as an initiator was employed at $60^{\circ}C$ with dimethylformamide(DMF) of solvent for the copolymerization of NIPM. $r_1$ was found to be higher than $r_2$ from the reactivity ratios of the monomer obtained from F-R and K-T methods. NIPM was found to be more copolymerized than GMA. The fluorescence spectrums of these polymers showed a weak monomer fluorescence band at 380 nm and a strong excimer fluorescence band at about 460 nm.

• Analytical Science and Technology
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• v.26 no.5
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• pp.315-325
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• 2013

The possibility of acute hepatotoxicity caused by dimethylformamide (DMF) requires regular monitoring of the workers who are using DMF to prevent the occupational disease. The authors performed ambient and biological monitoring of workers involved in synthetic leather manufacturing processes using DMF to assess the correlation between the markers of ambient and biological monitoring of DMF. The authors monitored 142 workers occupationally exposed to DMF from 19 workshops in the synthetic leather and ink manufacturing industries located in northern region of Gyeonggi-do. The subjects answered questionnaire on work procedure and use of personal protective equipment to be classified by exposure type. DMF in air samples collected using personal air samplers, diffusive and active sampler, was analysed using gas chromatograph-flame ionization detector (GC-FID) with DB-FFAP column (length 30 m, i.d. 0.25 mm, film thickness 0.25 ${\mu}m$). Urinary N-methylformamide (NMF) was analysed using gas chromatograph-mass selective detector (GC-MSD) at selected ion monitoring (SIM) mode with DB-624 column (length 60 m, i.d. 0.25 mm, film thickness 1.40 ${\mu}m$). Geometric mean (GM) and geometric standard deviation (GSD) of the ambient DMF was $6.85{\pm}3.43$ ppm, and GM and GSD of urinary NMF was $42.3{\pm}2.7$ mg/L. The ratio of subjects with DMF level over 10 ppm was 44%, and those with urinary NMF over 15 mg/L was 87%. NMF in urine adjusted by DMF in air was $4.61{\pm}2.57$ mg/L/ppm and $9.50{\pm}2.41$ mg/L/ppm, respectively, with or without respirator. There was seasonal differences of NMF in urine adjusted by DMF in air, $7.63{\pm}2.74$ mg/L/ppm in summer and $4.53{\pm}2.29$ mg/L/ppm in winter. The urinary NMF concentration which corresponds to 10 ppm of ambient DMF was 52.7 mg/L (r=0.650, n=128). Considering the difference of the route of exposure which resulted from the compliance of wearing personal protective equipment, the estimated contribution of respiratory and dermal exposure route for DMF was 48.5% vs. 51.5%.

• Macromolecular Research
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• v.15 no.3
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• pp.234-237
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• 2007

3,4-Bis-(3,4-dicarboxyphenylcarboxyethoxy)-4'-nitrostilbene dianhydride was prepared and reacted with 4,4'-(hexafluoroisopropylidene)dianiline to yield a novel Y-type polyimide containing the 3,4-dioxynitrostilbenyl group as an NLO-chromophore, which constituted part of the polymer backbone. The resulting polyimide was soluble in polar solvents such as acetone and N,N-dimethylformamide. The polymer exhibited good thermal stability up to $370^{\circ}C$ in the thermogravimetric analysis. The glass-transition temperature ($T_g$) obtained from the differential scanning calorimetry thermogram was near to $153^{\circ}C$. The second harmonic generation (SHG) coefficient ($d_{33}$) of the poled polymer film at the fundamental wavelength of $1064\;cm^{-1}$ was around $2.15\;{\times}\;10^{-8}\;esu$ (9.01 pm/V). The dipole alignment exhibited exceptionally high thermal stability even at a temperature $30^{\circ}C$ above the $T_g$, and there was no SHG decay below $180^{\circ}C$ because of the partial main chain character of the polymer structure.

• YAKHAK HOEJI
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• v.48 no.2
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• pp.135-140
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• 2004

For the development of new COX-2 inhibitors, 1,5-diarylhydantoins 5a∼5c and 1,5-diaryl-2-thiohydantoin 6a∼6c were synthesized from commercially available phenylacetic acids through esterification, bromination, C-N bond formation and cyclization. Esters 2a∼c were efficiently synthesized from the starting materials 1a∼c by refluxing in absolute methanol for 3 hours with catalytic concentrated sulfuric acid. Bromination of 2a∼c was carried out with use of N-bomosuccinimide at rt in dichloromethane. The bromine of 3a∼c was substituted with aniline in ethanol or N,N-dimethylformamide to provide 4a∼c. Hydantoins and 2-thiohydantoins were synthesized from 4a∼c by treatment of potassium isocyanate or potassium thiocyanate in dil-ethanol with triethylamine.

• Microbiology and Biotechnology Letters
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• v.24 no.2
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• pp.222-226
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• 1996

The enzymatic synthesis of 3, 4-dihydroxyphenyl-L-alanine (L-DOPA) was examined for the effects of the reaction additives such as sodium borate, alcohol, and organic solvents. The enzyme used was tyrosine phenol-lyase of Citrobacter freundii KCTC 2006 produced in Escherichia coli. The amounts of tyrosine phenol-lyase and pyridoxal-5-phosphate were optimized to 2.0 units/ml and 0.1 mM, respectively, for the synthetic reaction. Sodium borate, a substance that forms a complex with pyrocatechol, reduced the enzyme deactivation by pyrocatechol although it seriously inhibited the enzyme activity. Among the organic solvents tested, dimethylsulfoxide, dimethylformamide, and alcohol increased the productivity of the L-DOPA synthesis. In a reaction system with 5% methanol, L-DOPA concentration increased up to 210 mM after 24 hours, and 77.1% of which was separated as precipitates. The L-DOPA was purified to 99.96% by solubilizing and recrystallyzing the precipitates.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.777-781
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• 2008

In this work, silver nanoparticles-containing polyacrylonitrile (PAN) solutions in N,N-dimethylformamide (DMF) were electrospun to be webs consisting of nanofibers. The inputted voltage and PAN content in the solution were fixed at 15 kV and 10 wt.% in DMF with 10 cm of tip-to-collector distance (TCD). The PAN/Ag nanofiber webs were stabilized by oxidation at 250 ${^{\circ}C}$ for 2 h in air and carbonized at 1000 ${^{\circ}C}$ for 2 h in $N_2$. The resultant diameter distribution and morphologies of the nanofibers were evaluated by scanning electron microscope analysis. The electrochemical behaviors of the nanofiber webs were also observed by cyclic voltammetry tests. It was found that the presence of silver nanoparticles in carbon nanofiber webs led to the increase of specific capacitance and the decrease of fiber diameters.

• Macromolecular Research
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• v.13 no.1
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• pp.14-18
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• 2005

Under irradiation in a microwave oven, six novel poly(amide-imide)s containing tetrahydropyrimidinone, tetrahydro-2-thioxopyrimidine moieties and trimellitic rings in their main chains were synthesized through the polycondensation reaction of N,N'-(4,4'-diphenylether)bis(trimellitimide) diacid chloride with six different derivatives of tetrahydropyrimidinone and tetrahydro-2-thioxopyrimidine in the presence of a small amount of a polar organic medium, such as o-cresol. The polycondensation proceeded rapidly and completed within 7-9 min, producing a series of new poly(amide-imide)s in high yield that showed inherent viscosities in the range 0.33-0.52 dL/g. These poly(amide-imide)s were characterized by elemental analysis, viscosity measurement, thermal gravimetric analysis, solubility test, and FT-IR spectroscopy. All of the polymers were soluble at room temperature in polar solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, tetrahydrofuran, and N-methyl-2-pyrrolidone.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1329-1332
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• 2003

Stepwise dechlorination of 1,2,4-trichlorobenzene was observed at a glassy carbon electrode in dimethylformamide containing 0.1 M tetraethylammonium perchlorate. Especially, dechlorination to dichlorobenzene and further to monochlorobenzene or benzene was successfully demonstrated with a porous reticulated vitreous carbon electrode. Electrochemical dechlorination of polychlorobenzenes employing a flow cell with a reticulated vitreous carbon working electrode is also described. Preliminary experiments with a flow cell showed that dechlorination of trichlorobenzene to dichlorobenzene was partially completed while dechlorination to benzene or monochlorobenzene was not successful, suggesting that a flow rate and electrolysis time should be further optimized for the complete electrolysis.