• Journal of the Korean Wood Science and Technology
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• 제48권3호
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• pp.303-314
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• 2020

Gambir is a non-wood forest product with a potential of being used as wood adhesive, due to about 33% catechin in it. Meanwhile, catechins and sucrose have not been studied as adhesives. Therefore, basic characteristics of gambir-sucrose adhesives were investigated. In this research, adhesives were prepared by dissolving gambir and sucrose in distilled water, at different blending ratios of the gambir/sucrose such as 100/0, 75/25, 50/50, and 25/75 wt%. Furthermore, gas chromatography-mass spectrometry (GC-MS) was employed to determine the gambir chemical compositions, and Fourier transform-infrared (FTIR) spectroscopy was carried out to identify chemical bonds. Particleboards with a target density of 0.8 g/㎤ were then manufactured by hot-pressing for 10 min at 200℃. The internal bond (IB) strength of particleboard was subsequently measured. Based on the GC-MS analysis, 31.11% of catechin was identified. In addition, the viscosity, density, solid content, and gelation time of the adhesives, and insoluble matter content (IMC) in boiling water were 7.30~33.24 mPa.s, 1.2~1.3 g/㎤, 25.56~28.44%, 73~420 min, and 29.75~62.10%, respectively. Adding sucrose to the adhesive was observed to raise the IMC from 49.05 to 62.10%, at 180℃ and 200℃. FT-IR analysis showed that the gambir absorption peaks occurred at approximately 1620 cm^-1, assigned to the C=O stretching of 5-hydroxymethylfurfural, which tended to increase with the addition of sucrose. The reaction between gambir and sucrose was observed in the form of the dimethylene ether bridge. The 25/75 wt% gambir-sucrose adhesives and 200℃ hot-pressed temperature resulted in the highest IB strength (0.89 MPa), and met the requirement of JIS A5908-2003 type 18. Consequently, the gambir-sucrose adhesive could be used as a particleboard adhesive.

• 한국환경보건학회지
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• 제40권2호
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• pp.147-156
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• 2014

Objectives: This study was carried out to examine whether the apparent photolysis with or without sensitizers [NaOH and humic acid (HA)] was prompted photodegradation of polychlorinated biphenyl (PCB) in aqueous solution. Methods: PCBs photodegradation occurred using fluorescence black lamps at ${\lambda}_{max}=300nm$. PCB congeners were exposed in 10 ppm HA or 0.05N NaOH solutions, to investigate the decreasing profile of PCB concentration with time. The PCBs were then analyzed by gas chromatography/mass spectrometry (GC-MS). Reductive degradation profile of PCB congeners in the presence of both sensitizers under oxygen-saturated protic conditions was described using the wind-rose diagrams. Results: Use of HA or NaOH decreased PCB concentration with time in the dark and on irradiation, indicating that photolysis underwent through reductive dechlorination through energy transfer and possibly with reactive oxygens. The dechlorination was marked by a chromatographic shift, observed in the GC-MS plots. Therefore it is logical to assume that increasing the dose of sensitizers would increase the photodegradation rates of PCBs. The half-lives of pentachloro-PCB (penta-3) in 0.05N NaOH and 10 ppm HA were estimated at about 47 hours and 39 hours, respectively, under the same experimental conditions of photolysis. It was found that the rate of photolysis of pentachloro-PCB in aqueous solution followed apparent first-order kinetics compared to other congeners. Conclusion: Photochemical degradation (using 328 nm UV light) of penta- and hexa-PCBs in HA or alkaline solution is a viable method for pretreatment method. The results are helpful for the further comprehension of the reaction mechanism for photolytic dechlorination of PCBs in aquatic system.

• Journal of Crop Science and Biotechnology
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• 제10권3호
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• pp.163-166
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• 2007

Diurnal changes in levels of endogenous gibberellins(GAs) were investigated in three rice cultivars i.e. Sangjubyeo, Shingeumobyeo(photo-neutral) and Chucheongbyeo(photosensitive). The rice cultivars were grown under a 12-hr photoperiod and endogenous GA levels were assayed by gas chromatography-mass spectrometry(GC-MS-SIM) every 3 h for 24 h. The endogenous bioactive $GA_1$ and its immediate precursor $GA_{20}$ contents were significantly different in both photosensitive and photo-neutral rice cultivars, though less pronounced differences were observed for endogenous $GA_{12},\;GA_{53},\;GA_{19}$, and $GA_8$ levels with in the three rice cultivars. The levels of bioactive $GA_1$ and its immediate precursor $GA_{20}$ were significantly higher in Chucheongbyeo than in the other two cultivars. In Chucheongbyeo, the $GA_1$ contents increased significantly from 11.00 to 17.00 o'clock, thus indicating a correlation with light. In Shingeumobyeo, $GA_1$ contents slightly increased during morning hours, while a similar hike in $GA_1$ contents was observed for Sangjubyeo during evening hours. $GA_{19}$ was found to be the most abundant GA form in the three rice cultivars. Our results suggested that GA production in rice depends upon the response potential of rice cultivars and that light positively correlated to GA production in photosensitive rice cultivar.

• 에너지공학
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• 제25권3호
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• pp.9-17
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• 2016

본 연구에서는 바이오매스 조연제인 리그닌과 글리세린을 이용하여 일산화탄소(CO) 저감형 착화탄을 개발, 연소시 발생하는 일산화탄소 측정을 통해 조연제가 일산화탄소 발생에 미치는 영향을 관찰하였다. 연료의 완전연소를 위해 저온에서 높은 연소성을 보이는 글리세린을 높은 비표면적 값을 가진 리그닌에 함침시켜 연소 특성이 나타날 수 있도록 하였다. 열중량분석기(TGA) 및 가스분석기(GC/MS)를 이용하여 연소성, 탈휘발성 평가 및 일산화탄소 발생량을 측정하였다. 본 연구 결과에서 조연제 함유량에 따른 일산화탄소 발생량을 통해 전체 중량 대비 20% 조연제를 혼합 시 최적의 일산화탄소 저감률을 확인할 수 있었다. 최종적으로 일반 착화탄의 일산화탄소 농도 대비 20~30% 가량 감소한 값을 도출하였다.

• Journal of the Korean Wood Science and Technology
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• 제26권3호
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• pp.63-72
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• 1998

In order to evaluate the biodegradability and mechanism of 4,5,6-trichloroguaiacol (TCG) produced from bleaching process in pulp mill by Phanerochaete chrysosporium, Trametes versicolor, and Inonotus cuticularis, changes in TCG and its metabolites during biodegradation were analyzed by HPLC, and GC/MS spectrometry. By three fungi, the maximum biodegradability against TCG were very quickly reached, compared with other chlorinated aromatic compounds such as PCP. Within 24 hrs, T versicolor indicated up to 95% of TCG removal rate, and P. chrysosporium and I. cuticularis also showed more than 80%, and 90%, respectively. Particularly, in case of T. versicolor, the removal rate of TCG after 1 hr. incubation was reached to approximately 90%, implying very rapid metabolization of TCG. However, by analyzing the filtrates extracted from TCG containing culture by GC/MS, the major metabolites at initial stage of biodegradation were dimers, indicating that the added TCG monomers were quickly polymerized. The others were trichloroveratrole, dichloroguaiacol, and trichlorobenzoic acid, suggesting that TCG may be biodegraded by several sequential reactions such as polymerization, oxidation, methylation, dechlorination, and hydroxylation. In other experiments, the extracellular fluid which did not contain any fungal mycelia was used to evaluate the effect of mycelia on TCG biodegradation. The extracellular fluid of T. versicolor also biodegraded TCG up to 90% within 24hrs, but those of P. chrysosporium and I. cuticularis did not show any good biodegradability. T versicolor showed the highest value of laccase, and other two fungi indicated a little activity of lignin peroxidase (LiP) and manganese peroxidase (MnP). In addition, the laccase activity of T. versicolor was very linearly proportional to the removal rate of TCG during incubation, in other words, showing the induction effect against TCG. Consequently, the biodegradation of TCG was very dependent upon the activity of laccase.

• Journal of Applied Biological Chemistry
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• 제50권3호
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• pp.148-154
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• 2007

Volatile components of the essential oils of Satsuma mandarin (C. unshiu), Dangyuza (C. grandis), Yuza (C. junos), Byungkyul (C. playtymamma), Jinkyul (C. sunki), and Hakyul (C. natsudaidai) grown in Jeju Island were isolated from the fruit peels by hydro distillation and determined by GC-MS. GC-MS analysis identified 58 compounds, with main components being d-limonene $(64.01{\sim}79.34%),\;{\beta}-myrcene\;(3.01{\sim}26.53%),\;{\gamma}-terpinene\;(0.11{\sim}12.88%),\;{\beta}-pinene\;(0.78{\sim}4.74%),\;and\;{\alpha}-pinene\;(1.01{\sim}2.55%)$. Differences in compositions and contents of the essential oils were observed among citrus varieties. Effects of citrus oils on growth inhibitions of Escherchia coli, Staphyllococcus epidermidis, and Candida albicans were investigated using disc diffusion assay and minimal inhibitory concentration (MIC) assay. The essential oils inhibited growths of the test organisms, exhibiting higher levels of activity against Gram-positive S. epidermidis (MIC values $0.04{\sim}0.17mg/mL$), whereas Gram-negative E. coli was moderately resistant (MIC values $1.66{\sim}20.30mg/mL$). MIC of citrus essential oils ranged from $0.82{\sim}23.69mg/mL$ against C. albicans. The essential oils obtained from C. sunki, C. grandis, and C. playtymamma showed the highest antimicrobial activities against S. epidermidis and C. albicans, indicating their potential as natural antimicrobial agents.

• Applied Biological Chemistry
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• 제33권2호
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• pp.120-124
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• 1990

산형과 식물인 방풍, 천궁, 회향, 사상자, 시호, 당귀, 미나리 및 당근을 대상으로 GC/MS를 이용하여 falcarinol의 존재를 검색한 결과 방풍의 뿌리, 미나리의 줄기와 뿌리 및 당근의 뿌리로부터 이 화합물을 동정하였는데 그 함량은 각각 $1,055\;{\mu}g/g$, $289\;{\mu}g/g$, $179\;{\mu}g/g$ 및 $212\;{\mu}g/g$이었다. 미나리에서 falcarinol이 발견된 것은 이번이 처음이며 뿌리보다도 줄기에 더 많은 양이 함유되어 있으므로 앞으로 이 화합물의 생리활성 및 생합성 연구에 미나리가 널리 활용될 수 있을 것으로 사료된다.

• 분석과학
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• 제33권2호
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• pp.98-107
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• 2020

Methamphetamine (MA) is currently the most abused illicit drug in Korea. MA is produced by chemical synthesis, and the final target drug that is produced contains small amounts of the precursor chemicals, intermediates, and by-products. To identify and quantify these trace compounds in MA seizures, a practical and feasible approach for conducting chromatographic fingerprinting with a suite of traditional chemometric methods and recently introduced machine learning approaches was examined. This was achieved using gas chromatography (GC) coupled with a flame ionization detector (FID) and mass spectrometry (MS). Following appropriate examination of all the peaks in 71 samples, 166 impurities were selected as the characteristic components. Unsupervised (principal component analysis (PCA), hierarchical cluster analysis (HCA), and K-means clustering) and supervised (partial least squares-discriminant analysis (PLS-DA), orthogonal partial least squares-discriminant analysis (OPLS-DA), support vector machines (SVM), and deep neural network (DNN) with Keras) chemometric techniques were employed for classifying the 71 MA seizures. The results of the PCA, HCA, K-means clustering, PLS-DA, OPLS-DA, SVM, and DNN methods for quality evaluation were in good agreement. However, the tested MA seizures possessed distinct features, such as chirality, cutting agents, and boiling points. The study indicated that the established qualitative and semi-quantitative methods will be practical and useful analytical tools for characterizing trace compounds in illicit MA seizures. Moreover, they will provide a statistical basis for identifying the synthesis route, sources of supply, trafficking routes, and connections between seizures, which will support drug law enforcement agencies in their effort to eliminate organized MA crime.

• Weed & Turfgrass Science
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• 제4권4호
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• pp.321-329
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• 2015

The present study aimed to evaluate the phytotoxic potential of essential oils. For this purpose, 18 essential oil samples extracted from Korean plants and 64 commercial essential oils were screened for their phytotoxic potential against the seedling growth of Brassica napus L. (rapeseed). Among the 82 samples, 11 commercial oils (cinnamon, citronella, clove, cumin seed, geranium, jasmine, lemongrass, palmarosa, pimento, rose otto and spearmint) strongly inhibited the seedling growth with $GR_{50}$ value < $150{\mu}g\;mL^{-1}$. Major components from these effective essential oils were identified by solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). GC-MS analyses revealed that the effective samples mainly consist of benzyl benzoate, carvone, citral, citronellol, eugenol, geraniol, D-limonene and terpinene. Subsequently, bioactivity of these individual components was evaluated against the seedling growth of B. napus, Echinochloa crus-galli and Aeschynomene indica. The components from different chemical groups exhibited different potency in inhibiting the seedling growth with varied $GR_{50}$ values ranged from $29{\mu}g\;mL^{-1}$ to > $1000{\mu}g\;mL^{-1}$. In the greenhouse experiment, citral and geraniol completely suppressed the growth of all the tested 10 plants at $100kg\;ha^{-1}$. In conclusion, the individual essential oil components geraniol and citral could be used as natural herbicides for weed management.

• Elastomers and Composites
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• 제47권3호
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• pp.210-215
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• 2012

무기첨가제의 조성이 다른 EPDM 복합체를 준비하여 $90^{\circ}C$ 공기와 수돗물에서 각각 7일간 노화시켜 백화현상을 관찰하였다. 공기 중에서 노화시킨 시험편들은 모두 백화가 발생하지 않았으나, 수돗물에서 노화시킨 시험편들 중 스테아린산이 함유된 시험편들은 백화가 심하게 발생하였다. 무기첨가제의 조성에 따른 백화 현상의 차이는 없었다. 백화 물질을 가스 크로마토그래피/질량분석법(GC/MS), 영상 분석(image analysis), 에너지 분산 X-선 분광법(EDX), 감쇠 전반사-후리에 변환 적외선 분광법(ATR-FTIR)을 이용하여 분석하였다. 백화 물질은 스테아린산의 금속염이라는 것을 확인하였다. 스테아린산의 금속염은 수돗물에 존재하는 금속 이온과 시험편 내에 존재하는 스테아린산과의 반응에 의해 형성된다.