• Journal of the Korean Society of Safety
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• v.30 no.2
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• pp.21-26
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• 2015

For the safe handling of o-cresol, this study was investigated the explosion limits of o-cresol in the reference data. The flash points and AITs(auto-ignition temperatures) by ignition delay time were experimented. The lower flash points of o-cresol by using closed-cup tester were experimented in $77^{\circ}C$ and $80^{\circ}C$. The lower flash points of o-cresol by using open cup tester were experimented in $86^{\circ}C$ and $87^{\circ}C$. This study measured relationship between the AITs and the ignition delay times by using ASTM E659 tester for o-cresol. The AIT of o-cresol was experimented as $495^{\circ}C$. The lower explosion limit(LEL) by the measured the lower flash point for o-cresol was calculated as 1.27 Vol%.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.298-305
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• 2016

Previously our laboratory showed that Pseudomonas alkylphenolica KL28 possesses two different lap and pcu gene clusters for p-cresol catabolism. In this study, additional gene cluster (pchACXF-pcaHG-orf4-pcaBC) has been identified to encode enzymes necessary for catabolism of p-cresol to ${\beta}$-carboxy-cis,cis-muconate. This gene cluster showed almost identical nucleotide sequence homologies to those in the plasmid of Pseudomonas putida NCIMB 9866 and 9869, British origins, indicating the possibility of a horizontal gene transfer. Through mutagenesis of each gene cluster and gfp-based promoter reporter assays, it has been shown that the three gene clusters are functionally operated and pch genes are induced by p-cresol. Furthermore, the pcu gene cluster of the three was shown to be dominantly expressed in utilization of p-cresol. Mutation of the pcu gene was defective in aerial structure formation under p-cresol vapor, indicating the utilization rate of carbon source is one of key elements for the multicellular development of this strain.

• Biomolecules & Therapeutics
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• v.26 no.4
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• pp.389-398
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• 2018

p-Cresol, found at high concentrations in the serum of chronic kidney failure patients, is known to cause cell senescence and other complications in different parts of the body. p-Cresol is thought to mediate cytotoxic effects through the induction of autophagy response. However, toxic effects of p-cresol on mesenchymal stem cells have not been elucidated. Thus, we aimed to investigate whether p-cresol induces senescence of mesenchymal stem cells, and whether melatonin can ameliorate abnormal autophagy response caused by p-cresol. We found that p-cresol concentration-dependently reduced proliferation of mesenchymal stem cells. Pretreatment with melatonin prevented pro-senescence effects of p-cresol on mesenchymal stem cells. We found that by inducing phosphorylation of Akt and activating the Akt signaling pathway, melatonin enhanced catalase activity and thereby inhibited the accumulation of reactive oxygen species induced by p-cresol in mesenchymal stem cells, ultimately preventing abnormal activation of autophagy. Furthermore, preincubation with melatonin counteracted other pro-senescence changes caused by p-cresol, such as the increase in total 5'-AMP-activated protein kinase expression and decrease in the level of phosphorylated mechanistic target of rapamycin. Ultimately, we discovered that melatonin restored the expression of senescence marker protein 30, which is normally suppressed because of the induction of the autophagy pathway in chronic kidney failure patients by p-cresol. Our findings suggest that stem cell senescence in patients with chronic kidney failure could be potentially rescued by the administration of melatonin, which grants this hormone a novel therapeutic role.

• Applied Chemistry for Engineering
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• v.2 no.2
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• pp.108-118
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• 1991

Interactions between pyridine hydrodenitrogenation (HDN) and m-cresol hydrodeoxygenation(HDO), and the kinetic analysis were studied over sulfided $CoMo/{\gamma}-Al_2O_3$ catalyst at the range of temperatures between 473 K and 723 K, the total pressures between $10{\times}10^5Pa$ and $50{\times}10^5Pa$, and the contact times between 0.0125 g-cat. hr/ml-feed and 0.03g-cat. hr/ml-feed. HDN of pyridine and HDO of m-cresol were inhibited by each other and the inhibition effect of HDO by pyridine is higher than that of HDN by m-cresol. But reactivity of m-cresol is higher than that of pyridine. The rate equations of pyridine and m-cresol were given to be ${\gamma}_{HDN}=k_{HDN}{\cdot}K_pC_p/(1+K_cC_c+K_pC_p)$ and ${\gamma}_{HDO}=k_{HDO}{\cdot}K_cC_c/(1+K_cC_c+K_pC_p)$ in terms of Langmuir-Hinshellwood-Hougen-Watson model. At each temperature, reaction rate constants and adsorption equilibrium constants were determined and activation energies of pyridine HDN and m-cresol HDO are 13.83kcal/mol, respectively and the heat of adsorption are -6.458 and -5.045kcal/mol, respectively.

• Journal of the Korean Electrochemical Society
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• v.7 no.3
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• pp.138-142
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• 2004

The polyaniline films of emeraldine base (EB) and leucoemeraldine base (LEB) form doped with cam-phorsulfonic acid (CSA) were prepared by casting the mixed solution of chloroform and m-cresol on ITO (indium tin oxide) electrode. By analyzing UV-vis spectra of the mixed solutions, the effects of the secondary doping by m-cresol were obtained. And the conductivity of polyaniline film was increased with increasing m-cresol content. As the results of analyzing cyclic voltammograms, it was known that the redox peak currents of polyaniline electrode prepared from LEB were larger and more reversible than those of polyaniline eleclrodes prepared from EB. The charge transfer resistances $(R_{ct})$ of polyaniline electrodes were reduced with increasing m-cresol content, showing smaller Rct for LEB/CSA than EB/CSA.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1179-1183
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• 2011

In this study, the chromosome-encoded pcuRCAXB genes that are required for p-cresol degradation have been identified by using a newly constructed green fluorescent protein (GFP)-based promoter probe transposon in the long-chain alkylphenol degrader Pseudomonas alkylphenolia. The deduced amino acid sequences of the genes showed the highest identities at the levels of 65-93% compared with those in the databases. The transposon was identified to be inserted in the pcuA gene, with the promoterless gfp gene being under the control of the pcu catabolic gene promoter. The expression of GFP was positively induced by p-cresol and was about 10 times higher by cells grown on agar than those in liquid culture. In addition, p-hydroxybenzoic acid was detected during p-cresol degradation. These results indicate that P. alkylphenolia additionally possesses a protocatechuate ortho-cleavage route for p-cresol degradation that is dominantly expressed in colonies.

• Applied Chemistry for Engineering
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• v.2 no.3
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• pp.253-261
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• 1991

Polyamic acids, precursor polymers of polyimides have been obtained by the solution polycondensation of benzophenone tetracarboxylic dianhydride (BTDA) with 4, 4'-diamino diphenyl methane (MDA) and/or 3, 3'-dimethyl benzidine (OTB). The reaction was carried in two solvent systems such as m-cresol and m-cresol/xylene mixture. The results of TGA analysis showed that the polyimide films had good thermal stability with the initial decomposition temperature ranging from $540^{\circ}$ to $590^{\circ}$. According to DSC analysis of polymers, the glass transition temperature was over $340^{\circ}$. Polyimide film samples, showed good mechanical and electrical properties, had over $16Kg/mm^2$ of tensile strength and about 200 KV/mm of dielectric breakdown voltage. The properties of the copolymer from MAD/OTB were better than those of the homopolymer from MDA. And the polymer synthesized in m-cresol had lower properties than that obtained in m-cresol/xylene.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.618-623
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• 2020

Spherical phenolic resin beads were synthesized by suspension polymerization at 98 ℃ from phenol, ortho-cresol, formaldehyde, with triethylamine as a basic catalyst, and spherical phenol-cresol copolymer resin beads with relatively low crosslinking density as well. Phenol reacts with formaldehyde at two ortho- and one para- positions to form a crosslinked structure, but ortho-cresol instead of phenol reduces the crosslinking density during copolymerization due to the methyl group at a ortho- position. As a result, spherical phenol-cresol copolymer beads showed more shrinkage with decreasing apparent density compared to the spherical phenol beads when carbonized at 700 ℃ under nitrogen. As the molecular weight of the cresol oligomer increases, the pore radius of the carbonized copolymer beads decreases, which is consistent with the density and shrinkage results. It was confirmed that the characteristics such as density decrease, shrinkage, yield and so on during carbonization can be controlled by controlling the degree of crosslinking of the spherical phenolic resin particles with cresol.

• Journal of the Korean Society of Safety
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• v.13 no.2
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• pp.109-115
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• 1998

Tri-cresyl phosphate(TCP) was synthesized by reaction of phosphorus chloride with mixed cresol(mixture of m-cresol, p-cresol, and others) in the presence of $AlCl_3$. Some of unwanted products and unreactants colored TCP. In order to separate TCP from these, vaccume distillation was carried twice, but colorless TCP could not be producted. Separation of unwanted materials by 2% NaOH solution was introduced before first and second distillation and optimal separation conditions such as NaOH concentration, mixing volume ratio, mixing time, and rpm were investigated for new batch separation and production of colorless TCP Optimal conditions were 2% NaOH solution, 35% mixing volume ratio of 2% NaOH solution, 1.5 hours of mixing time, and 20 rpm.

• Journal of Environmental Science International
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• v.10 no.2
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• pp.99-103
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• 2001

Several microorganisms which degrade phenol and trichloroethylene(TCE) were isolated from the activated sludge of a wastewater treatment plant. Among them, one isolate EL-04J showed the highest degradability and was identified as a Pseudomonas species according to morphological, cultural and biochemical properties. The phenol-induced cells of Pseudomonas EL-04J, which were preincubated in the mineral salts medium containing phenol as a sole carbon source, degraded 90% of 25$\mu$M TCE within 20h. This strain could also utilize some of methylated phenol derivatives (o-cresol, m-cresol and p-cresol) as the sole source of carbon and energy. Cresol-induced cells of Pseudomonas EL-04J also cometabolized TCE.