• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1177-1180
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• 2003

Thallium is quantitatively retained by 1,10-phenanthroline and tetraphenylborate onto benzophenone in the pH range 0-11 from a large volumes of aqueous solutions of various samples. After filtration, the solid mass consisting of thallium complex and benzophenone is dissolved with 5 mL of dimethylformamide and the metal was determined by flame atomic absorption spectrometric. About 0.4 ㎍ of thallium can be concentrated from 400 mL of aqueous sample, where its concentration is as low as 1.0 ng/mL. Eight replicate determinations of 8.0 ㎍/mL of thallium in final dimethylformamide solution gave a mean absorbance of 0.160 with a relative standard deviation of 1.7%. The sensitivity for 1% absorption was 0.22 ㎍/mL. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the trace determination of thallium in various alloys and biological samples.

• KSBB Journal
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• v.11 no.2
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• pp.186-192
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• 1996

The effects of chemical modification on the enzymes' stability in polar organic solvents were studied with subtilisin Carlsberg in dimethylformamide-water mixtures as a model system. Three out of nine lysine residues of subtilisin Carlsberg were coupled to either trimellilic or pyromellitic anhydrides thereby, for each lysine residue modified, resulting in the net replacement of one basic amino group by two or three acidic carboxyl groups, respectively. In water at 60$^{\circ}C$, both trimellitic and pyromellitic anhydride-modified subtilisin Carlsberg showed increased thermostability by 2.6 times and 1.6 times, respectively, as compared to that of unmodified enzyme. In 70% dimethylformamide at 25$^{\circ}C$, however, only pyromellitic acrid was shown to enhance the stability of subtilisin Carlsberg by 5.5 times increasing the half life time of irreversible inactivation from 4.9hr for unmodified enzyme to 27.8hr for modified enzyme.

• Polymer(Korea)
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• v.25 no.6
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• pp.803-810
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• 2001

A nonlinear optical hyperbranched polyester (PE-Azo/Hyper) was synthesized from 4-[N,N-bis(hydroxyethyl)amino-4'-formyl] azobenzene and cyanoacetic acid by a Knoevenagel polycondensation using 4-(dimethylamino) pyridine as a base. The resulting polymer was soluble in polar aprotic solvents such as N,N-dimethylformamide and 1-methyl-2-pyrrolidinone and could be processed into optical quality films by spin coating. The molecular weight was determined to be $M_w$=61,800 ($M_W/M_n{=1.86}$) by gel permeation chromatography using polystyrene as a standard. No melting point was detected by differential scanning Calorimeter, indicating that this polymer presents an amorphous state. It shows a glass transition temperature of $121^{\circ}C$. The second-order nonlinear optical coefficient $d_{33}$ of the poled polymer determined by the second harmonic generation at 1064 nm was 25.4 pm/V.

• Molecular & Cellular Toxicology
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• v.5 no.1
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• pp.58-66
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• 2009

The 2-year rodent carcinogenicity test involves long-term, repetitive dosing of animals that is both time consuming and expensive. Alternative approaches have been attempted using specific transgenic or knockout mice or toxicogenomics to predict carcinogenicity without conducting a 2-year rodent test. In addition, toxicogenomic analysis of carcinogen-treated animals could also enhance our understanding of molecular mechanisms and aid in the diagnosis of acute toxicity induced by carcinogens. Therefore, we investigated transcription profiles after administering the carcinogens 4,4-dimethylformamide (DMF) and 4-biphenylamine (ABP). BALB/c male mice were treated once with DMF (650 mg/kg i.p.) or ABP (120 mg/kg p.o.). Standard blood biochemistry and histological changes were observed. Gene expression profiles in the livers of mice treated with either vehicle or the carcinogens were analyzed using the Affymetrix $GeneChip^{(R)}$ assay. In all, 1,474 differentially expressed genes in DMF- or ABP-treated mice were identified as being either up- or down-regulated over 1.5-fold (P< 0.01), and these genes were analyzed using hierarchical clustering and Ingenuity Pathways Analysis. Of these, 107 genes were consistently regulated in both carcinogen-treated groups. Genes associated with cancer were upregulated (Por, S100a10, Tes, Ctcf, Ddx21, Eapp, Nel, and Pa2g4) or downregulated (Cbs and Gch1). Toxicological function analysis also identified genes involved in organ toxicity, including hepatotoxicity. These data may help to identify molecular markers for acute hepatotoxicity induced by carcinogens.

• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.95-99
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• 1992

A spectrophotometric method for the determination of copper using N,N'-Oxalylbis(salicylaldehyde hydrazone) as a chromogenic reagent has been developed. Determination has been performed by measuring the absorbances of the copper complexes in solutions containing 60% dimethylformamide (pH 2) at 422 nm. The method allows the determination of 0.4${\sim}$1.8 ${\mu}$g/ml of copper and has been applied to its determination in synthetic mixtures and alloy samples.

• Membrane Journal
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• v.31 no.4
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• pp.282-292
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• 2021

In this work, we tested commercial organic solvent nanofiltration (OSN) membranes using both in-house dead-end and crossflow systems. Four different crosslinked polyimide Duramem (DM) OSN membranes with various MWCO (molecular weight cut off) values were tested in organic solvents such as ethanol, N,N-dimethylformamide, acetone and acetonitrile. The membranes exhibited more reliable and reproducible performance in the crossflow system, and the performance changed significantly depending in the physical properties of the testing solvent. This is due to the initial stabilization period via pressure-induced compaction phenomenon, which can be vastly different between membrane samples. Hence, to obtain reliable and reproducible results, crossflow system is the preferred choice.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.322-327
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• 2023

A design of experiments was evaluated in optimizing MOF-5 synthesis for acetylene adsorption. At first, mixture design was used to optimize precursor concentration, terephthalic acid, zinc acetate dihydrate and N,N-dimethylformamide. More specifically, 13 conditions with various molar ratios were designed by extreme vertices design method. After preparing the samples, XRD, N₂ physisorption and SEM analysis were performed for their characterization. Moreover, acetylene adsorption experiments were carried out over the samples under identical conditions. The optimal precursor composition for MOF-5 synthesis was predicted on a molar basis as follows: terephthalic acid : acetate dihydrate : dimethylformamide = 0.1 : 0.4 : 0.5. Thereafter, multi-level factorial design was designated to investigate the effect of synthesis reaction conditions such as temperature, time and stirring speed. By the statistical analysis of 18 samples designed, 4 reaction parameters were determined for additional adsorption experiments. Therefore, MOF-5 prepared under the synthesis time and temperature of 100 ℃ and 12 h, respectively, showed the maximum adsorption capacity of 15.1 mmol/g.

• Journal of Convergence for Information Technology
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• v.11 no.9
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• pp.109-114
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• 2021

Cr(VI)-quinoline compound[(C₉H₇NH)₂Cr₂O₇] was synthesized by the reaction between of quinoline and chromium(VI) trioxide, and structure was FT-IR, elemental analysis. The oxidation ability of benzyl alcohol greatly depends upon the dielectric constant of the used organic solvent, where carbon tetrachloride was worst and N,N'-dimethylformamide was best solvent. Noticeably, in N,N'-dimethylformamide solvent, Cr(VI)-quinoline compound oxidized substituted benzyl alcohols. The Hammett reaction constant(ρ)=-0.69(303K). As a resuit, Cr(VI)-quinoline compound was found as efficicent oxidizing agent that converted benzyl alcohol, allyl alcohol, primary alcohol and secondary alcohols to the corresponding aldehydes or ketones. Cr(VI)-quinoline compound was selective oxidizing agent of benzyl alcohol, allyl alcohol and primary alcohol in the presence of secondary alcohol ones.

• Journal of the Korean Chemical Society
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• v.9 no.1
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• pp.1-7
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• 1965

Reaction of monochloroacetic acid with zinc in presence of toluene, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, acetonitrile, and dioxane solvents showed the solvent effect in order of dimethylformamide, dioxane, dimethyl sulfoxide, toluene, acetonitrile, and tetrahydrofuran. The increasing reactivity of the reagents was observed in order of the polarity and hydrophilicity of the solvent. The same reaction of ethyl monochloroacetate in the same series of solvents showed also the solvent effect, but the difference was not large as compared to that of the acid. The reaction of the acid, ester, zinc, and carbonyl precursors such as benzaldehyde and 4-heptanone gave the Reformatsky reaction product in the case of the aldehyde, but the reactivity with 4-heptanone was slight. The yield of the product was varied by the method of addition of reagents. The best yield observed in case of the acid reaction was 38.5% of the hydroxy acid and 0.8g of the salt in presence of acetonitrile and in case of the ester reaction 19.3% of ethyl cinnamate and 21.6% of polymer. The variation of the reactivity of reagents due to the reaction temperature was observed in case of carbonyl reaction. The result was discussed in terms of the solvent effect and the procedures were described.

• Toxicological Research
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• v.29 no.3
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• pp.187-193
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• 2013

The effects of toluene in dimethylformamide (DMF)-induced hepatotoxicity were investigated with respect to the induction of cytochrome P-450 (CYP) and the activities of related enzymes. The rats were treated intraperitoneally with the organic solvents in olive oil (Single treatment groups: 450 [D1], 900 [D2], 1,800 [D3] mg DMF, and 346 mg toluene [T] per kg of body weight; Combined treatment groups: D1+T, D2+T, and D3+T) once a day for three days, while the control group received just the olive oil. Each group consisted of 4 rats. The activities of the xenobiotic metabolic enzymes and the hepatic morphology were assessed. The immunoblots indicated that the expression of CYP2E1 was considerably enhanced depending on the dosage of DMF and the CYP2E1 blot densities were significantly increased after treatment with both DMF and toluene, compared to treatment with DMF alone. The activities of glutathione-S-transferase and glutathione peroxidase were either decreased or remained unaltered after treatment with DMF and toluene, whereas the lipid peroxide levels were increased with increasing dosage of DMF and toluene. The liver tissue in the D3 group (1,800 mg/kg of DMF) showed signs of microvacuolation in the central vein region and a large necrotic zone around the central vein, in rats treated with both DMF (1,800 mg/kg) and toluene (D3T). These results suggest that the expression of CYP2E1 is induced by DMF and enhanced by toluene. These changes may have facilitated the accelerated formation of N-methylformamide (NMF) from toluene, and the generated NMF may directly induce liver damage.