• Title, Summary, Keyword: Chemical Analyses

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An Experimental Study on Measurement of Chemical Kinetic Parameters of a Liquid Fuel with Various Components (혼합 액체 연료의 화학반응 인자 계측에 관한 실험적 연구)

  • Choi, Hyo-Hyun;Lim, Jun-Seok;Kim, Chul-Jin;Sohn, Chae-Hoon
    • Journal of the Korean Society of Combustion
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    • v.16 no.3
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    • pp.21-26
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    • 2011
  • Thermal analyses are conducted to measure chemical kinetic parameters of an unknown liquid fuel with various components. Thermal Analyses are divided into two different methods such as TGA(Thermo-Gravimetric Analysis) and DSC(Differential Scanning Calorimety). Non-isothermal experimental results are analyzed by adopting TGA and they are filtered by Freeman-Carroll method. As a results of the analysis, chemical parameters of the activation temperature and the reaction order are measured to be 6128.2 K and 1.4, respectively. Furthermore, the chemical kinetic parameters are obtained by a variety of mathematical processing methods. It has been found that they show a little difference depending on the processing method.

Characteristics of the Multi-Hydrogen Bonded Systems: DFT Description on the Solvated Electrons

  • Xu, Jun
    • Bulletin of the Korean Chemical Society
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    • v.34 no.11
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    • pp.3265-3268
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    • 2013
  • The multi-hydrogen bonded systems with the solvated electrons are investigated at the B3LYP/6-311++$G^{**}$ basis set level. The symmetrical linear geometrical characteristic is common for the dimer systems, while for the tetramer system, the tetrahedron configuration is generated. The NBO charge analyses demonstrate that the multi-hydrogen-multi-electron (mH-ne) coupling exist in these anion systems, as is supported by the electrostatic potential and the molecular orbital analyses. The positive chemical shift value of the central hydrogen ($H_c$) and the negative chemical shift value of the terminal hydrogen ($H_t$) indicate that the $H_c$ is electronegative while the $H_t$ is electropositive, respectively. Strong coupling between two central hydrogen atoms is demonstrated by the large spin-spin coupling constants. The solvated electron donates significant contributions for the stability of these systems.

Spatial Analyses of Soil Chemical Properties from a Remodeled Paddy Field as Affected by Wet Land Leveling

  • Jung, Ki-Yuol;Choi, Young-Dae;Lee, Sanghun;Chun, Hyen Chung;Kang, Hang-Won
    • Korean Journal of Soil Science and Fertilizer
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    • v.49 no.5
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    • pp.555-563
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    • 2016
  • Uniformity and leveled distributions of soil chemicals across paddy fields are critical to manage optimal crop yields, reduce environmental risks and efficiently use water in rice cultivation. In this study, an investigation of spatial distributions on soil chemical properties was conducted to evaluate the effect of land leveling on mitigation of soil chemical property heterogeneity from a remodeled paddy field. The spatial variabilities of chemical properties were analyzed by geostatistical analyses; semivariograms and kriged simulations. The soil samples were taken from a 1 ha paddy field before and after land leveling with sufficient water. The study site was located at Bon-ri site of Dalseong and river sediments were dredged from Nakdong river basins. The sediments were buried into the paddy field after 50 cm of top soils at the paddy field were removed. The top soils were recovered after the sediments were piled up. In order to obtain the most accurate spatial field information, the soil samples were taken at every 5 m by 5 m grid point and total number of samples was 100 before and after land leveling with sufficient water. Soil pH increased from 6.59 to 6.85. Geostatistical analyses showed that chemical distributions had a high spatial dependence within a paddy field. The parameters of semivariogram analysis showed similar trends across the properties except pH comparing results from before and after land leveling. These properties had smaller "sill" values and greater "range" values after land leveling than ones from before land leveling. These results can be interpreted as land leveling induced more homogeneous distributions of soil chemical properties. The homogeneous distributions were confirmed by kriged simulations and distribution maps. As a conclusion, land leveling with sufficient water may induce better managements of fertilizer and water use in rice cultivation at disturbed paddy fields.

Synthesis of N$^6$-Aminoalkyl-5'-adenylic Acid Derivatives

  • Kang, Jung-Bu
    • Bulletin of the Korean Chemical Society
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    • v.1 no.4
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    • pp.126-131
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    • 1980
  • Seventeen new $N^{6}$-aminoalkyl derivatives of 5'-adenylic acid and adenosine 5'-triphosphate (Compound I-XVII) were synthesized from 6-chloropurine ribonucleoside by reaction with appropriate diamines. This paper discusses the procedure of synthesis and the identification of the derivatives by ultraviolet spectra, high voltage electrophoresis, paper chromatography, elemental analyses, and other chemical methods.

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Structural Analyses of the Novel Phosphoglycolopids Containing the Unusual very Long Bifunctional Acyl Chain, α,ω-13,16-Dimethyloctacosanedioate in Thermoanaerobacter ethanolicus

  • Lee, Sang-Hoo;Kang, Se-Byung;Kim, Jai-Neung;Jung, Seun-Ho
    • Bulletin of the Korean Chemical Society
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    • v.23 no.12
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    • pp.1778-1784
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    • 2002
  • Novel membrane lipids containing the unusual very long chain fatty $acid{\alpha}{\omega}-1316-dimethyloctacosanedioate$, dimethyl. Ester (DME C30) was isolated and purified from thermophilic anaerobic eubacterium, Thermoanaerobacter ethanolicus. Structures of the lipids containing the bifunctional fatty acyl components were proposed by various analyses such as $^1H,\;^{13}C,\;^{31}P$ nuclear magnetic resonance (NMR), Fourier transform infrared(FTIR) spectroscopy, gas chromatography/mass spectrometry (GC/MS) and fast atom bombardment mass spectrometry (FAB/MS). Combined with the GC/MS, $^1H,\;and\;^{13}C$NMR data, we confirmed that the head groups of the lipids contained the glycerol and/or glucosamine molecules. $^{31}P$ NMR spectrum also showed that the lipids contained phosphate in a phosphodiester linkage. The proposed structures of these novel lipid components were the ones in which two head groups were linked by the membrane spanning fatty acyl component(DME C30)and regular chain fatty acids on glycerol moiety of each head group.

Clustering and Comparative Analyses of Complete Genomes for the Elucidation of Evolutionary Characteristics

  • Kim, Jin-Sik;Lee, Sang-Yup
    • Proceedings of the Korean Society for Bioinformatics Conference
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    • pp.78-82
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    • 2005
  • Three of the genus Pseudomonas (P. aeruginosa, P. putida, P. syringae) show highly different phenotypic characteristics among them. Two of the three members are pathogenic and the other is non-pathogenic. Comparative analyses of the complete genomes can elucidate the genomic similarities and differences among them. We analyzed the three genomes and the genes of them to reveal the degree of conservation of chromosomes and similarity of the genes. The 2-dimensional dot plot between the pathogenic P. aeruginosa and non-pathogenic P. putida shared higher portion of the nucleotide sequences than other two combinations. Comparison of the nucleotide compositions by calculating the genome-scale plot of G+C contents and GC skew showed the variation of location. Comparison of the metabolic capabilities using the functional classification of KEGG orthology revealed that the differences in the number of genes for the specific functional categories resulted in the phenotypic differences. Finally combination of the analyses using the protein homologs supported the evolutionary distance of the P. putida obtained from other genome-scale comparisons.

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Chemical Bonding Nature and Mesoporous Structure of Nickel Intercalated Montmorillonite Clay

  • Park, Hye-Mi;Kim, Tae-Woo;Hwang, Seong-Ju;Choy, Jin-Ho
    • Bulletin of the Korean Chemical Society
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    • v.27 no.9
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    • pp.1323-1328
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    • 2006
  • Mesoporous nickel intercalated aluminosilicate nanohybrid has been synthesized through a recombination reaction between the colloidal suspension of exfoliated montmorillonite nanosheets and aqueous nickel acetate solution. According to powder X-ray diffraction and field emission-scanning electron microscopic analyses, the intercalation of nickel species expands significantly the basal spacing of the host montmorillonite clay and the crystallites of the intercalation compound are assembled to form a house-of-card structure. $N_2$ adsorption-desorption isotherm measurements with BJH pore analyses clearly demonstrated that the porosity of the intercalate originates mainly from mesopores (diameter $\sim50\;\AA$) formed by the house-of-card type stacking of clay crystallites. From FT-IR and X-ray absorption spectroscopic analyses, it becomes certain that intercalated nickel ion is stabilized in an isolated $NiO_6$ octahedral unit. The present mesoporous intercalation compound is expected to be applicable as efficient catalysts or absorbents.

Tandem laser-induced breakdown spectroscopy laser-ablation inductively-coupled plasma mass spectrometry analysis of high-purity alumina powder

  • Lee, Yonghoon;Kim, Hyang
    • Analytical Science and Technology
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    • v.32 no.4
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    • pp.121-130
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    • 2019
  • Alumina is one of the most important ceramic materials because of its useful physical and chemical properties. Recently, high-purity alumina has been used in various industrial fields. This leads to increasing demand for reliable elemental analysis of impurities in alumina samples. However, the chemical inertness of alumina makes the sample preparation for conventional elemental analysis a tremendously difficult task. Herein, we demonstrated the feasibility of laser ablation for effective sampling of alumina powder. Laser ablation performs sampling rapidly without any chemical reagents and also allows simultaneous optical emission spectroscopy and mass spectrometry analyses. For six alumina samples including certified reference materials and commercial products, laser-induced breakdown spectroscopy (LIBS) and laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) analyses were performed simultaneously based on a common laser ablation sampling. LIBS was found to be useful to quantify alkali and alkaline earth metals with limits-of-detection (LODs) around 1 ppm. LA-ICP-MS could quantify transition metals such as Ti, Cu, Zn, and Zr with LODs in the range from a few tens to hundreds ppb.