• Title/Summary/Keyword: Chemical density

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Structures and Spectroscopic Properties of $OC_nO$ (n=2-6): Density Functional Theory Study

  • 김경환;이보순;이성열
    • Bulletin of the Korean Chemical Society
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    • v.19 no.5
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    • pp.553-557
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    • 1998
  • Density functional theory calculations are reported for the carbon clusters bonded with two oxygen atoms $OC_No$ (n=2-6). The structures, vibrational frequencies and dipole moments are computed by BLYP theory with the 6-311G* basis set. Good agreement is obtained between the computed and experimentally observed properties. The ground states of these molecules are shown to be linear. Cyclic structures with higher energy are also predicted.

A Green's-Matrix Approach to Chemisorption

  • Jang, Yun-Hee;Kim, Ho-Jing
    • Bulletin of the Korean Chemical Society
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    • v.14 no.2
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    • pp.238-243
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    • 1993
  • A self-consistent-field Green's matrix method for the calculation of electronic properties of chemisorbed system is devised and applied to the methanol on copper(110) surface. The method is based on CNDO Hartree-Fock approximation. Contour integration in the complex energy plane is used for an efficient calculation of the charge-density bond-order matrix. The information on each fragment prior to chemisorption is efficiently used and a small number of iterations are needed to reach the self-consistency. The changes of density of states and other quantities of methanol due to chemisorption are consistent with reported experimental results.

Anodic Oxidation of Iodate to Periodate by Lead Peroxide Anode (전착과산화납양극에 의한 옥소산염 전해산화)

  • Chong Woo Nam;Hak Joon Kim
    • Journal of the Korean Chemical Society
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    • v.15 no.6
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    • pp.324-329
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    • 1971
  • In order to evaluate the mechanism of electrolytic oxidation of iodate and to determine the optimum conditions for the electrolysis, studies were made using the cells without diaphragm and the lead peroxide anode. Results are summarized as followings: 1) Current density vs. anode potential curve by lead peroxide electrode had the different limiting current densities from platinum electrode and was more positive than platinum electrode. 2) Additions of potassium bichromate in the electrolyte contribute to maintain high current efficiency. 3) In the acid and alkaline regions, the current efficiencies decreased by reduction of iodate and discharge of hydroxyl ion, so maximum current efficiency was shown at pH 7. 4) Higher current density lowered the current efficiency in the region of 60-80% conversion of iodate. 5) Influence of the conversion on current efficiency in the region of 60-80% conversion of iodate.

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Physico-chemical characteristics of mangrove soil in Gulf of Kachchh, Gujarat, India

  • Rajal, Patel;Lamb, Christian;Roshan, Bhagat;Kamboj, R.D.;Harshad, Salvi
    • Advances in environmental research
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    • v.8 no.1
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    • pp.39-54
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    • 2019
  • This paper presents comprehensive scientific details about mangrove soil in Gulf of Kachchh, Gujarat. A total of ten sites were studied during November, 2011 to December, 2014 in order to know the physico-chemical characteristics of mangrove soil. The results indicated that the soil in GoK had silty loam texture. Other physico-chemical parameters ranged as; pH: 7.39-7.61, Bulk Density: 0.30 g/㎤-0.54 g/㎤, Particle Density: 1.26 g/㎤-1.76 g/㎤, Organic Carbon: 0.70%-1.13%, Organic Matter: 1.01%-1.74% and Moisture Content: 33.45%-56.38%. The paper would be useful to the stakeholders, coastal managers and scientific communities to know the mangrove soil conditions of Gulf of Kachchh for management and planning for conservation of mangrove ecosystem.

Effects of Planting Densities on the Major Characters, Forage Yield and Chemical Composition of Jeju Italian Millet (제주 조의 재식밀도에 따른 주요형질, 사초수량 및 조성분 변화)

  • 조남기;강영길;김인식;조영일;오은경
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.21 no.2
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    • pp.53-58
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    • 2001
  • Jeju Italian millet was grown at five planting densities(5$\times$5, 15$\times$15, 20$\times$20, 25cm) form May 13 to Aug. 14, 2000 at jeju island to determine influence of planting density on agronomic characters, forage yield and quality. Days to heading increased from 87 to 89 days as planting density was decreased. In 5$\times$5cm planting density plot, plant height was 185.4cm and it was gradually decreased as planting density was increased. So in 30$\times$30cm planting density plot, plant height was 173cm. As planting density increased, stem diameter, the number of nodes per plant, the umber of leaves, leaf width and SPAD reading values was increased, the longer leaf length as the broader planting density. Fresh forage yield increased from 29.99 to 55.01MT/ha, dry matter(DM) yield from 8.04 to 15.59MT/ha, crude protein(CP) yield from 0.78 to 2.26MT/ha and total digestible nutrients(TDN) yield from 3.65 to 7.93MT/ha as planting density was decreased. Crude protein content increased from 9.8 to 14.5% ether extract comtent from 1.4 to 1.9%, nitrogen free extract content from 38.4% to 38.9% and TDN content from 45.4 to 50.9%, but crude fiber content decreased from 34.5 to 30.1% and crude ash content from 9.1 to 8.0% as planting density was decreased.

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DFT Studies on Two Novel Explosives Based on the Guanidine-Fused Bicyclic Structure

  • Jin, Xing-Hui;Hu, Bing-Cheng;Jia, Huan-Qing;Liu, Zu-Liang;Lu, Chun-Xu
    • Bulletin of the Korean Chemical Society
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    • v.35 no.4
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    • pp.1043-1049
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    • 2014
  • Density functional theory (DFT) calculations at the B3LYP/6-31G(d,p) theoretical level were performed for two novel explosives (compounds B and C) based on the guanidine-fused bicyclic skeleton $C_4N_6H_8$ (A). The heats of formation (HOFs) were calculated via isodesmic reaction. The detonation properties were evaluated by using the Kamlet-Jacobs equations. The bond dissociation energies (BDEs) for the thermolysis initiation bond were also analyzed to investigate the thermal stability. The results show that the compounds have high positive HOF values (B, 1064.68 $kJ{\cdot}mol^{-1}$; C, 724.02 $kJ{\cdot}mol^{-1}$), high detonation properties (${\rho}$, D and P values of 2.04 $g{\cdot}cm^{-3}$ and 2.21 $g{\cdot}cm^{-3}$, 9.98 $km{\cdot}s^{-1}$ and 10.99 $km{\cdot}s^{-1}$, 46.44 GPa and 59.91 Gpa, respectively) and meet the basic stability requirement. Additionally, feasible synthetic routes of the these high energy density compounds (HEDCs) were also proposed via retrosynthetic analysis.