• Bulletin of the Korean Chemical Society
• /
• 제13권2호
• /
• pp.131-135
• /
• 1992

High-Tc superconducting materials, $HoBa_2Cu_3O_{7-x}F_y$ with $0.0{\leq}y{\leq}0.5$, were synthesized by ceramic method and studied by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, scanning electron microscopy and resistivity measurement. From the X-ray diffraction data, it was found that the samples had only single phase of which lattice volumes were decreased in proportional to the amount of fluorine, which indicated that the relatively small fluorine atoms are effectively substituted for the oxygen sites. Also, an anomalous phenomenon appeared that the peak intensities of (001) planes were greatly increased as fluorine contents increased. SEM photographs revealed that the grain sizes were enlarged progressively with fluorine contents. This fact could be explained along with DTA & TGA data that the incorporation of fluorine gave rise to lowering the melting point. Tc decreased as the incorporation of fluorine content increased. This implies that the superconducting electrons are perturbed due to the substitution of electronegative fluorine atom.

• Bulletin of the Korean Chemical Society
• /
• 제33권2호
• /
• pp.473-482
• /
• 2012

A novel malemide epoxy containing Co(II), Ni(II) and Cu(II) ions have been synthesized by curing malemide epoxy resin (MIEB-13) and Co(II), Ni(II) and Cu(II) complexes of macrocyclic bis-hydrazone Schiff base. The Schiff base was synthesized by reacting 1,4-dicarbnyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol. The Schiff base and its Co(II), Ni(II) and Cu(II) complexes have been characterized by elemental analyses, spectral (IR, $^1H$ NMR, UV-vis., FAB mass, ESR), thermal and magnetic data. The curing reaction of maleimide epoxy compound with metal complexes was studied as curing agents. The stability of cured samples was studied by thermo-gravimetric analyses and which have excellent chemical (acid/alkali/solvent) and water absorption resistance. Further, the scanning electron microscopy (SEM) and definitional scanning colorimetric (DSC) techniques were confirmed the phase homogeneity of the cured systems.

• 대한화학회지
• /
• 제55권5호
• /
• pp.794-804
• /
• 2011

3-Chloro-1-benzothiophene-2-carbonylchloride (1) was allowed to react with glycine to give 3-chloro-1-benzothiophen-2-yl-carbonylaminoacetic acid (2). Various aldehydes were treated with compound (2) in acetic anhydride to get 1,3-oxazol-5-ones (3a-d). These oxazolones were treated with aromatic amines or hydrazides to get various imidazol-4-ones (4a-h or 5al) separately. Oxazolones was also treated with aromatic hydrazine, through which expansion of five membered oxazole ring to six member triazine ring occurs to yield 1,2,4-triazin-6-ones (6a-h). The structures of all the synthesized compounds were confirmed by spectral data and were screened for antibacterial and antifungal activities.

• Bulletin of the Korean Chemical Society
• /
• 제34권6호
• /
• pp.1643-1650
• /
• 2013

A non linear QSAR model was constructed on a series of 57 xanthone and curcuminoide derivatives as ${\alpha}$-glucosidase inhibitors by back-propagation neural network method. The neural network architecture was optimized to obtain a three-layer neural network, composed of five descriptors, nine hidden neurons and one output neuron. A good predictive determination coefficient was obtained (${R^2}_{Pset}$ = 86.7%), the statistical results being better than those obtained with the same data set using a multiple regression analysis (MLR). As in the MLR model, the descriptor MATS7v weighted by Van der Waals volume was found as the most important independent variable on the ${\alpha}$-glucosidase inhibitory.

• Natural Product Sciences
• /
• 제10권5호
• /
• pp.220-222
• /
• 2004

A new prenylated pyranoxanthone, inophyllin B (1), was isolated from the roots of Calophyllum inophyllum (Guttiferae). Together with this compound was also isolated the known pyranoxanthone brasilixanthone B (2) and two common triterpenes friedelin (3) and sitosterol (4). Structural elucidations of these compounds were achieved through $^1H,\;^{13}C$, DEPT, COSY, HSQC and HMBC experiments. The molecular mass was determined using MS techniques. The crude extract indicated weak toxicity to the larvae of Aedes aegypti. We report here the isolation, structural elucidation and bioassay data for Inophyllin B and brasilixanthone B.

• Journal of Microbiology and Biotechnology
• /
• 제20권6호
• /
• pp.985-987
• /
• 2010

The biological transformation of the bioactive dihydroisocoumarin, (-)-mellein, isolated from the marinederived fungus Cladosporium sp., was studied. The preparativescale culture of (-)-mellein with a marine isolate of a bacterium Stappia sp. resulted in the isolation of its oxidized metabolite, (3R,4S)-4-hydroxymellein. The stereostructure of the metabolite obtained was assigned on the basis of detailed physicochemical data analyses.

• Applied Biological Chemistry
• /
• 제41권6호
• /
• pp.477-482
• /
• 1998

새로운 Leukotriene $D_4$ antagonists를 찾기 위해 구조-활성간 연구를 수행하였다. 이미 알려진 chalcone 유도체의 구조와 생물학적 활성 자료를 이용하여 구조-활성간 계산을 수행한 결과 새로운 화합물을 발견하였고, 이를 합성하여 효과를 측정한 결과를 보고하고자 한다.

• Applied Science and Convergence Technology
• /
• 제25권6호
• /
• pp.103-107
• /
• 2016

The use of nanovesicles (NVs) has contributed to nanotechnology in the development of new concept medicine to compete with diseases of deleterious and infectious to human health. Due to their properties of size, morphology, and biocompatibility NVs have great impact on public health especially in the development of new therapeutic and prophylaxis approaches in addition to the device for biosensors to diagnose human diseases. Recent data also strongly suggest that NVs are regarded as innovative materials in developing for vaccines and diagnostic tools. In this review, we focus on the basic concepts and recent applications of NVs to utilize or engineer them as therapeutic materials.

• Journal of Applied Biological Chemistry
• /
• 제43권3호
• /
• pp.165-169
• /
• 2000

Regarding to maturity evaluation of pig manure compost mixed with saw dust, change of constituents of organic matter influenced by microbial activities were investigated. Throughout the two stages of active composting period, we obtained a lot of data related to compost stabilization. However, we found out that only a couple of parameters could be used for adequate evaluation of compost. We, therefore, decided that total sugar and reducing sugar could be used for the reasonable standard criteria of maturity during composting process, even though some enzyme activities by phosphates and cellulase reactions were obtained and compared. Because the other parameters such as contents of lignin, cellulose, and organic acids were difficult to be used for maturity evaluation of pig manure compost.

• Bulletin of the Korean Chemical Society
• /
• 제12권6호
• /
• pp.652-658
• /
• 1991

The effect of intermolecular collisions in the infrared multiphoton dissociation (IRMPD) of difluorochloromethane was investigated using He, Ar, and $N_2$ as buffer gases. The reaction probability for IRMPD of difluorochloromethane was measured as a function of laser fluence and the buffer gas pressure under unfocused beam geometry. It was observed that the reaction probability was initially enhanced with the increase of buffer gas pressure up to about 20 torr, but showed a decline at higher pressures. The reaction probability increases monotonically with the laser fluence, but the rate of increase diminishes at higher fluences. An attempt was made to simulate the experimental results by the method of energy grained master equation (EGME). From the parameters that fit the experimental data, the average energy loss per collision, $<{\Delta}E>_d$, was estimated for the He, Ar, and $N_2$ buffer gases.