• 한국응용과학기술학회지
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• 제8권2호
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• pp.115-122
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• 1991

Four novel amphoteric surfactants of N-(2-alkylamidoethyl)-N, N-dimethyl ammonioacetates were synthesized. The each reaction between four saturated fatty acids containing 10, 12, 14 and 16 carbon atoms and N, N-dimethylethylene diamine permitted to give the intermediate products, N-(2-alkylamidoethyl)-N, N-dimethylamines. Quaterinzation of these intermediates was permitted to form N-(2-alkylamidoethyl)-N, N-dimethyl, ammonioacetates, whose sturctures were identified by CC, TLC, elemental analysis, IR pectrophotometry and $^1$HNMR spectrometry. The products yielded from 48% to 58%. The isoelectric points were shown in the range of $4.30{\sim}6.64$. It showed a tendency to learn to the acidic site and its range was broadened as increase of the hydrophobic group length. Surface tensions of the aqueous solution in the $10^{-6}{\sim}10^{-1}$mol/l of amidobetaines were measured. and the critical micell concentration(cmc) were shown in the range of $8.37{\times}10^{-6}{\sim}8.96{\times}10^{-2}$mol/l, and ${\Gamma}_{cmc}$ were reduced to 32.3~38.2 dyne/cm. A linear relationship between log cmc and the number of carbon in the hydrophobic alkyl chain was presented by the formula of log cmc=2.38-0.5n, and the contribution-rate of n on the standard free energy change in micellization ${\partial}({\Delta}G^0$$_m)/{\partial}n$, was calulated as -0.5RT.

• Advances in environmental research
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• 제3권3호
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• pp.185-197
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• 2014

Efficient defluorination of perfluorooctanoic acid (PFOA) was achieved by integrating UV irradiation and $Fe^{2+}$ activation of persulfate ($S_2O{_8}^{2-}$). It was found that the UV-$Fe^{2+}$, $Fe^{2+}-S_2O{_8}^{2-}$, and UV-$S_2O{_8}^{2-}$ processes caused defluorination efficiency of 6.4%, 1.6% and 23.2% for PFOA at pH 5.0 within 5 h, respectively, but a combined system of UV-$Fe^{2+}-S_2O{_8}^{2-}$ dramatically promoted the defluorination efficiency up to 63.3%. The beneficial synergistic behavior between $Fe^{2+}-S_2O{_8}^{2-}$ and UV-$S_2O{_8}^{2-}$ was demonstrated to be dependent on $Fe^{2+}$ dosage, initial $S_2O{_8}^{2-}$ concentration, and solution pH. The decomposition of PFOA resulted in generation of shorter-chain perfluorinated carboxylic acids (PFCAs), formic acid and fluoride ions. The generated PFCAs intermediates could be further defluorinated by adding supplementary $Fe^{2+}$ and, $S_2O{_8}^{2-}$ and re-adjusting solution pH in later reaction stage. The much enhanced PFOA defluorination in the UV-$Fe^{2+}-S_2O{_8}^{2-}$ system was attributed to the fact that the simultaneous employment of UV light and $Fe^{2+}$ not only greatly enhanced the activation of $S_2O{_8}^{2-}$ to form strong oxidizing sulfate radicals ($SO{_4}^{\cdot-}$), but also provided an additional decarboxylation pathway caused by electron transfer from PFOA to in situ generated $Fe^{3+}$.

• Safety and Health at Work
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• 제2권4호
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• pp.365-374
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• 2011

Objectives: This study was designed to investigate whether long-term, low-level exposure to monocyclic aromatic hydrocarbons (MAHs) induced insulin resistance. Methods: The subjects were 110 male workers who were occupationally exposed to styrene, toluene, and xylene. One hundred and ten age-matched male workers who had never been occupationally exposed to organic solvents were selected as a control group. Cytokines, which have played a key role in the pathogenesis of insulin resistance, and oxidative stress indices were measured. Assessment of exposure to MAHs was performed by measuring their ambient levels and their urinary metabolites in exposed workers, and the resulting parameters between the exposed group and non-exposed control groups were compared. Results: There was no significant difference in general characteristics and anthropometric parameters between the two groups; however, total cholesterol, fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance levels were significantly higher in the exposed group. Phenylglyoxylic acid levels showed significant association with tumor necrosis factor-${\alpha}$, total oxidative status, and oxidative stress index via multiple linear regression analysis. Further, there was a negative correlation between methylhippuric acid levels and total anti-oxidative capacity, and there was a significant relationship between MAHs exposure and fasting glucose levels, as found by multiple logistic regression analysis (odds ratio = 3.95, 95% confidence interval = 1.074-14.530). Conclusion: This study indicated that MAHs increase fasting glucose level and insulin resistance. Furthermore, these results suggested that absorbing the organic solvent itself and active metabolic intermediates can increase oxidative stress and cytokine levels, resulting in the changes in glucose metabolism and the induction of insulin resistance.

• Korean Chemical Engineering Research
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• 제57권6호
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• pp.763-767
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• 2019

본 연구에서는 흐름형 반응기를 활용하여 단일 화합물로 구성된 연료인 exo-tetrahydrodicyclopentadiene (exo-THDCP)의 유량을 변화시킴에 따라 나타나는 열분해 특성에 대해 분석하였다. 실험은 $500^{\circ}C$, 50 bar의 온도와 압력 조건에서 수행하였으며, 각 유량 조건에서 반응을 통해 생성된 물질은 GC/MS를 사용하여 분석하였다. 그 결과, exo-THDCP는 열에 의해 주로 고리형 화합물로 분해됨과 동시에 일부는 이성질화 되는 것을 확인하였다. 또한, 유량이 증가할수록 분해 및 이성질화 반응을 통해 생성되는 화합물의 종류와 비율이 감소하였으며, 이에 따라 연료의 전환율과 분해 반응 시에 발생하는 흡열량도 함께 감소하였다. 열분해 반응 시에 비교적 빠르게 생성되는 화합물은 주로 1-cyclopentylcyclopentene (1-CPCP)의 radical 형태를 중간체로 하여 형성되는 것으로 분석되었는데, 이는 exo-THDCP로부터 생성될 수 있는 중간체 중에서도 특히 1-CPCP가 생성되는 데에 필요한 활성화 에너지가 약 42 kcal/mol로 가장 낮기 때문인 것으로 해석된다.

• 한국수소및신에너지학회논문집
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• 제32권5호
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• pp.388-400
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• 2021

Power to gas (P2G) is one of the energy storage technologies that can increase the storage period and storage capacity compared to the existing battery type. One of P2G technology produces hydrogen by decomposing water from renewable energy (electricity) and the other produces CH4 by reacting hydrogen with CO2. This study is an experimental study to produce CH4 by reacting CO2 of biogas with hydrogen using a 40 wt% Ni-Mg-Al catalyst and a commercial catalyst. Catalyst characteristics were analyzed through H2-TPR, XRD, and XPS instruments of 40% Ni catalyst and commercial catalyst. The effect on the CO2 conversion rate and CH4 selectivity was analyzed, and the activities of a 40% Ni catalyst and a commercial catalyst were compared. As a result of experiment, In the case of a 40 wt% catalyst, the maximum CO2 conversion rate showed 77% at the reaction temperature of 400℃. Meanwhile, the commercial catalyst showed a maximum CO2 conversion rate of 60% at 450℃. When 50% of CO was added to the CO2 methanation reaction, the CO2 conversion rate was increased by about 5%. This is considered to be due to the atmosphere in which the CO reaction can occur without the process of converting to CH4 after forming carbon and CO as intermediates in terms of the CO2 mechanism on the catalyst surface.

• Journal of Applied Biological Chemistry
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• 제64권3호
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• pp.225-236
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• 2021

The epipyrone (EPN) biosynthetic gene cluster of Epicoccum nigrum is composed of epnC, epnB, and epnA, which encode cytochrome P450 oxidase, glycosyltransferase, and highly reducing polyketide synthase, respectively. Gene inactivation mutants for epnA, epnB, and epnC were previously generated, and it was found that all of them were incapable of producing EPN and any of its related compounds. It was also reported that epnB inactivation abolished epnA transcription, generating ΔepnAB. This study shows that the introduction of native epnC readily restored EPN production in ΔepnC, suggesting that epnC is essential for polyketide release from EpnA and implies that EpnC works during the polyketide chain assembly of EpnA. Introduction of epnC promoter-epnA restored EPN production in ΔepnA. The ΔepnB genotype was prepared by introducing the epnA expression vector into ΔepnAB, and it was found that the resulting recombinant strain did not produce any EPN-related compounds. A canonical epnB inactivation strain was also generated by deleting its 5'-end. At the deletion point, an Aspergllus nidulans gpdA promoter was inserted to ensure the transcription of epnA, which is located downstream of epnB. Examination of the metabolite profile of the resulting ΔepnB mutant via LC-mass spectrometry verified that no EPN-related compound was produced in this strain. This substantiates that C-glycosylation by EpnB is a prerequisite for the release of EpnA-tethered product. In conclusion, it is proposed that cytochrome P450 oxidase and glycosyltransferase work in concert with polyketide synthase to generate EPN without the occurrence of any free intermediates.

• Nano
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• 제13권12호
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• pp.1850141.1-1850141.11
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• 2018

Sodium ion batteries based on the more sodium source reserve than that of lithium have been designed as promising alternatives to lithium ion batteries. However, several problems including unsatisfied specific capacity and serious cyclic stability must be solved before the reality. One of the effective approaches to solve the abovementioned problems is to search for suitable anode materials. In this work, we designed and prepared $FeSe_2$ nanoflakes via a simple hydrothermal method which can be adjusted in composition by Fe precursor. As a potential anode for sodium storage, the optimized $FeSe_2$ electrode was further evaluated in different electrolytes of $NaClO_4$ in propylene carbonate/fluoroethylene carbonate and $NaCF_3SO_3$ in diethylene glycol dimethyl ether. The capacity was about $470mAh\;g^{-1}$ and $535mAh\;g^{-1}$ at $0.5A\;g^{-1}$, respectively, in the voltage between 0.5 V and 2.9 V in the cycle of stabilization phase. Superior performance both in capacity and in stability was obtained in ether-based electrolyte, which affords the property without plugging the intermediates of transition metal dichalcogenides during charge/discharge processes.

• Advances in environmental research
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• 제7권3호
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• pp.213-223
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• 2018

Continuous input into the aquatic ecosystem and persistent structures have created concern of antibiotics, primarily due to the potential for the development of antimicrobial resistance. Degradation kinetics and mineralization of vancomycin B (VAN-B) by photocatalysis using $TiO_2$ and ZnO nanoparticles was monitored at natural pH conditions. Photocatalysis (PC) efficiency was followed by means of UV absorbance, total organic carbon (TOC), and HPLC results to better monitor degradation of VAN-B itself. Experiments were run for two initial VAN-B concentrations ($20-50mgL^{-1}$) and using two catalysts $TiO_2$ and ZnO at different concentrations (0.1 and $0.5gL^{-1}$) in a multi-lamp batch reactor system (200 mL water volume). Furthermore, a set of toxicity tests with Daphnia magna was performed to evaluate the potential toxicity of oxidation by-products of VAN-B. Formation of intermediates such as chlorides and nitrates were monitored. A rapid VAN-B degradation was observed in ZnO-PC system (85% to 70% at 10 min), while total mineralization was observed to be relatively slower than $TiO_2-PC$ system (59% to 73% at 90 min). Treatment efficiency and mechanism of degradation directly affected the rate of transformation and by-products formation that gave rise to toxicity in the treated samples.

• Journal of Microbiology and Biotechnology
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• 제31권7호
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• pp.967-977
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• 2021

A total of 37 bacterial isolates were obtained from dye-contaminated soil samples at a textile processing factory in Nakhon Ratchasima Province, Thailand, and the potential of the isolates to decolorize and biotransform azo dye Reactive Red 141 (RR141) was investigated. The most potent bacterium was identified as Paenibacillus terrigena KKW2-005, which showed the ability to decolorize 96.45% of RR141 (50 mg/l) within 20 h under static conditions at pH 8.0 and a broad temperature range of 30-40℃. The biotransformation products were analyzed by using UV-Vis spectrophotometry and Fourier-transform infrared spectroscopy. Gas chromatography-mass spectroscopy analysis revealed four metabolites generated from the reductive biodegradation, namely sodium 3-diazenylnaphthalene-1,5-disulfonate (I), sodium naphthalene-2-sufonate (II), 4-chloro-1,3,5-triazin-2-amine (III) and N¹-(1,3,5-triazin-2-yl) benzene-1,4-diamine (IV). Decolorization intermediates reduced phytotoxicity as compared with the untreated dye. However, they had phytotoxicity when compared with control, probably due to naphthalene and triazine derivatives. Moreover, genotoxicity testing by high annealing temperature-random amplified polymorphic DNA technique exhibited different DNA polymorphism bands in seedlings exposed to the metabolites. They compared to the bands found in seedlings subjected to the untreated dye or distilled water. The data from this study provide evidence that the biodegradation of Reactive Red 141 by P. terrigena KKW2-005 was genotoxic to the DNA seedlings.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.301-311
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• 2018

In this study, the ion-gelation method was applied to fabricate novel Fe-carbon-bentonite-alginate beads ($Fe^0$/C-BABs). $Fe^0$/C-BABs could effectively control Fe release during persulfate (PS) activation in N-acetyl-p-aminophenol (APAP) oxidation. A novel two-stage approach that combined $Fe^0$/C-BABs and an oyster-shell-filled bed (OSFB) column was developed to address the low pH and high Fe concentration of the effluent of the traditional PS process. The application of the $Fe^0$/C-BABs and OSFB column regulated pH levels and Fe release during the advanced oxidation of APAP. The characteristics of $Fe^0$/C-BABs were also investigated through scanning electron microscopy, energy dispersive spectrometry, and Fourier transform infrared spectroscopy. The long-term operation performance of $Fe^0$/C-BABs in a continuous fixed-bed reactor under simultaneous PS and APAP feeding was also evaluated. The effects of initial PS concentration, pH, fixed-bed weight, in-flow rate, and dissolved oxygen (DO) were investigated. Under selected conditions, 86.3% efficiency was achieved during the first stage of APAP degradation (effluent pH of 3.05, Fe contents: $106.25mgL^{-1}$). Water quality improved after the effluent was passed through the OSFB column (effluent pH of 6.32, Fe contents: $21.43mgL^{-1}$). Moreover, this study analyzed the free radicals and intermediates produced during APAP degradation to identify the possible routes of APAP degradation.