• Environmental Analysis Health and Toxicology
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• v.21 no.3 s.54
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• pp.239-244
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• 2006

Caenorhabditis elegans(C. elegans) is a free-living soil nematode that commonly used as a biological model and recently, much work has been done using C. elegans as a toxicity model. To evaluate the acute toxicity of phenols to C. elegans, worms were subsequently exposed to nine different xenobiotics. This study described lethal toxicity, reproductive toxicity and movement inhibition using 2-propylphenol, 4-propylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-phenylphenol, 4-phenylphenol, nonylphenol and 4-dodecylphenol to C. elegans for 24 hr or 72 hr. We found that phenols used in this study were very toxic to C. elegans. The order of lethal toxicity, reproductive toxicity and movement inhibition is as follows. 4-propylphenol > 2-phenylphenol > 2-tert-butylphenol > 2-propylphenol > nonylphenol > B-tert-butylphenol > 4-dodefylphenol > 4-tert-butylphenol > 4-phenylphenol.

• Journal of Powder Materials
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• v.20 no.3
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• pp.215-220
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• 2013

In the present work, 6061 Al-$B_4C$ sintered composites containing different $B_4C$ contents were fabricated and their characteristic were investigated as a function of sintering temperature. For this, composite powders and their compacts with $B_4C$ various contents from 0 to 40 wt.% were fabricated using a planetary ball milling equipment and cold isostatic pressing, respectively, and then they were sintered in the temperature ranges of 580 to $660^{\circ}C$. Above sintering temperature of $640^{\circ}C$, real density was decreased due to the occurrence of sweat phenomena. In addition, it was realized that sinterability of 6061Al-$B_4C$ composite material was lowered with increasing $B_4C$ content, resulting in the decrease in its real density and at the same time in the increment of porosity.

• Current Applied Physics
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• v.18 no.11
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• pp.1458-1464
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• 2018

An improved method for the preparation of g-$C_3N_4$ is described. Currently, heating (> $400^{\circ}C$) of urea is the common method used for preparing the g-$C_3N_4$. We have found that sonication of melamine in $HNO_3$ solution, followed by washing with anhydrous ethanol, not only reduce the crystallite size of g-$C_3N_4$ but also facilitate intriguing electronic structure and photoluminescence (PL) properties. Moreover, loading of metal (Pt and Ag) nanoparticles, by applying the borohydride reduction method, has resulted in multicolor-emission from g-$C_3N_4$. With the help of PL spectra and local electronic structure study, at C K-edge, N K-edge, Pt L-edge and Ag K-edge by X-ray absorption spectroscopy (XAS), a precise mechanism of tunable luminescence is established. The PL mechanism ascribes the amendments in the transitions, via defect and/or metal states assimilation, between the ${\pi}^*$ states of tris-triazine ring of g-$C_3N_4$ and lone pair states of nitride. It is evidenced that interaction between the C/N 2p and metal 4d/5d orbitals of Ag/Pt has manifested a net detraction in the ${\delta}^*{\rightarrow}LP$ transitions and enhancement in the ${\pi}^*{\rightarrow}LP$ and ${\pi}^*{\rightarrow}{\pi}$ transitions, leading to broad PL spectra from g-$C_3N_4$ organic semiconductor compound.

• IE interfaces
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• v.12 no.2
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• pp.193-204
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• 1999

Development of high technology especially in telecommunication and precise weapon systems will impact the future battle field environment. So it is not difficult to anticipate the environment of military command and control system will be changed rapidly. Considering these future battle field environment, military needs automated C4I (Command, Control, Communication, Computer and Intelligence) system, namely real time decision support system which is combined high technologies. Most of advanced countries have been studied and developed these kinds of systems and already applied these systems in real military operations. In order to take a military initiative in Korea peninsula it is essential to catch up with this trend and procure C4I system. The purpose of this research is to present the method and the direction of optimal C4I system development model. First we survey the related theory about C4I systems. Second we present the conceptual framework for C4I system concept development. Third we model the system using Timed Petri-Net and perform simulation. Finally we analyze the through-put time and suggest alternatives. If we model using the real organization structure, operational tasks and various situations then optimal C4I system would be developed.

• Korean Journal of Crystallography
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• v.11 no.1
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• pp.46-51
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• 2000

The molecular structures of 2-SC₄H₃CH=NN(H)C/sub 6/H/sub 5/(C/sub 11/H/sub 10/N₂S) and (GaMe₂)₂(2-SC₄H₃CH=NNC/sub 6/H/sub 5/)₂(C/sub 26/H/sub 30/Ga₂N₄S₂) have been determined by X-ray diffraction. Crystallographic data for 2-SC₄H₃CH=NN(H)C/sub 6/H/sub 5/:orthorhombic space group P2₁2₁2₁, a=6.108(1)Å, b=7.593(1)Å, c=22.356(2)Å, V=1037.1(3)ų, Z=4, R=0.0613. Crystallographic data for (GaMe₂)₂(2-SC₄H₃CH=NNC/sub 6/H/sub 5/)₂:monoclinic space group P2₁/n, a=15.996(2) Å, c=9.879(3)Å, β=100.07.(2)°, V=2764.599)ų, Z=4, R=0.0503.

• Journal of the Korea Society of Computer and Information
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• v.18 no.5
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• pp.113-120
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• 2013

This paper proposes an algorithm that proves an NP-complete 4-color theorem by employing a linear time complexity where $O(n)$. The proposed algorithm accurately halves the vertex set V of the graph $G=(V_1,E_1)$ into the Maximum Independent Set (MIS) $\bar{C_1}$ and the Minimum Vertex Cover Set $C_1$. It then assigns the first color to $\bar{C_1}$ and the second to $\bar{C_2}$, which, along with $C_2$, is halved from the connected graph $G=(V_2,E_2)$, a reduced set of the remaining vertices. Subsequently, the third color is assigned to $\bar{C_3}$, which, along with $C_3$, is halved from the connected graph $G=(V_3,E_3)$, a further reduced set of the remaining vertices. Lastly, denoting $C_3$ as $\bar{C_4}$, the algorithm assigns the forth color to $\bar{C_4}$. The algorithm has successfully obtained the chromatic number ${\chi}(G)=4$ with 100% probability, when applied to two actual map and two planar graphs. The proposed "four color algorithm", therefore, could be employed as a general algorithm to determine four-color for planar graphs.

• Journal of Sericultural and Entomological Science
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• v.15 no.1
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• pp.1-7
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• 1973

his study has been carried out to investigate amylase activity of digestive juice in the 5th day of the 5th instar influenced by the dietary composition (quantitative ratio between carbohydrate and protein) and the rearing temperature during the 4th moulting period. The larvae grew on three kinds of semi-synthetic diets. The A-diet has more carbohydrate than the others, the B-diet has carbohydrate in 1 : 2 with protein, and the C-diet has more protein than the others. All the diets were kept at 16$^{\circ}C$, 25$^{\circ}C$ and 32$^{\circ}C$ during the 4th moulting period. Amylase activity of digestive juice at the 5th day of the 5th instar was analyzed by Fuwa's method. The results were as follows. 1. Both A and C-diets were worse than B-diet in the larval growth and development. 2. The dietary composition influencing amylase activity of digestive juice was not related to the rearing temperature during the 4th moulting period. Amylase activity was stronger in C-diet, B-diet and A-diet order. 3. It was found that amylase activity at 32$^{\circ}C$ was stronger than that at 16$^{\circ}C$ in all kinds of diets. 4. There was an inter-action in amylase activity of male larval digestive juice between the dietary composition and the rearing temperature during 4th the moulting period.

• Microbiology and Biotechnology Letters
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• v.43 no.4
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• pp.314-321
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• 2015

Agar-hydrolyzing bacteria were isolated from the coastal sea water of Jeju Island. One isolate, designated as S4, was selected for further study. The S4 cells were Gram-negative and rod-shaped with smooth beige surfaces and single polar flagellum. Cells were grown at $15-42^{\circ}C$, 0.5-5% (w/v) NaCl, between pH 6.0 and 9.0, and in media containing 0.5-5% (w/v) NaCl. The G+C content was 49.93 mol%. The major fatty acids (>15%) were $C_{18:1}{\omega}7c$, $C_{16:0}$ and Summed feature 3 (comprising $C_{16:1}{\omega}7c/iso-C_{15:0}$ 2-OH). Based on 16S rRNA sequencing and biochemical and chemotaxonomic characteristics, the strain was designated as Vibrio sp. S4. In liquid culture supplemented with 0.1% agar the cell density and agarase activity reached a maximum level in 72 h, while agarase activity in the culture without agar was negligible, implying agarose expression is induced by agar. The optimum pH and temperature for the extracellular crude agarase of S4 were 7.0 and $45^{\circ}C$, respectively. However, it also exhibited 98.6% and 87.6% at $40^{\circ}C$ and $50^{\circ}C$, respectively, of the maximum activity seen at $45^{\circ}C$. The crude agarase hydrolyzed agarose into (neo)agarotetraose and (neo)agarohexaose.

• Journal of the Korean Chemical Society
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• v.53 no.3
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• pp.266-271
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• 2009

In the recently synthesized rare earth transition metal carbide $La_7O_{s4}C_9$ one finds one-dimensional organometallic $[O_{s4}C_9]^{21-}$ polymers embedded in a $La^{3+}$ ionic matrix. The electronic structure of the polymeric $[O_{s4}C_9]^{21-}$ chain was investigated by density of states (DOS) and crystal orbital overlap population (COOP), using the extended Huckel algorithm. A fragment molecular orbital analysis is used to study the bonding characteristics of the $C_2$ units in $La_7O_{s4}C_9$ containing $C_2$ units and single C atoms as well. The title compound contains partially filled Os and carbon bands leading to metallic conductivity. As the observed distances already indicated, the calculations show extensive Os-C interactions. The C-C bond distance in the diatomic $C_2$ units ($d_{C-C}$=131 pm) in the solid is significantly increased relative to $${C_2}^{2-}$$ or acetylene, because antibonding $1{\pi}_g$ orbitals are partially filled by the Os-$C_2(1\;{\pi}_g)$ bonding contribution found at and below the Fermi level.

• Bulletin of the Korean Chemical Society
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• v.20 no.4
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• pp.427-430
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• 1999

The Grignard coupling reaction of bis(chloromethyl)diorganosilanes [(ClCH2)2SiR1R2: R1 = R2 = Me, la; R1 = Me, R2 = Ph, lb; R1 = R2 = Ph, lc] with diorganodichlorosilanes [(Cl2SiR3R4: R3 = R4 = Me, 2a; R3 = Me, R4 = Ph, 2b; R3 = R4 = Ph, 2c] at THE reflux temperature gave the intermolecular C-Si coupling product of 1,1,3,3-tetraorgano-1,3-disilacyclobutanes 3a-f in poor to moderate yields ranging from 7% to 50% along with polydiorganosilapropanes. The cyclization reaction of la-c with methyl-substituted dichlorosilanes 2a, b gave 1,3-disilacyclobutanes 3a-c, e, d in moderate yields (42-50%), while the same reaction with dichlorodiphenylsilane (2c) to 1,3-disilacyclobutanes 3d, f resulted in low yield (7-18%) probably due to the steric hindrance of two-phenyl groups on the silicon of 2c.