• Title, Summary, Keyword: Chemical Analyses

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Geochemical investigation of stream sediment and water of the Anyang river: Environmental implication (안양천 하천수 및 퇴적물의 지구화학 예비조사와 환경적 의미)

  • 이상훈;문지원
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.151-155
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    • 1998
  • The Anyang river drains a highly polluted industrial area and enters the lower part of Han river. In this preliminary study for the comprehensive understanding of geochemical behaviour of elements in the stream sediments and its implications on the river chemistry and ecology, major and trace elements in stream sediments, suspended solids and stream water were analysed to look into elemental enrichments and elemental behaviour with distance from upper part of the stream. Chemical analyses of the stream sediments show enrichements of heavy metals including Cr, Zn, Ni, Co between 10 to 100 times. Other trace elements, Cd, Pb and As are also enriched between several to 10 times, based on relative ratio with Al in fresh rock. Chemical analyses of the sediments, suspended solids and water show indications of anthroporgenic impact for the heavy metal accumulation. It was nortworth Hg is detected between 2 and 4 ppb in the water.

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Thermodynamical and Experimental Analyses of Chemical Vapor Deposition of ATO from SnCl4-SbCl5-H2O Gas Mixture ($SnCl_4-SbCl_5-H_2O$ 기체혼합물로부터 ATO(Antimony Tin Oxide) 박막의 화학증착에 관한 열역학 및 실험분석)

  • 김광호;강용관;이수원
    • Journal of the Korean Ceramic Society
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    • v.29 no.12
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    • pp.990-996
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    • 1992
  • Chemical vapor deposition of ATO from SnCl4-SbCl5-H2O gas mixture was investigated with thermodynamic and experimental analyses. Electrical conductivity of the ATO film was much improved under deposition conditions of low input-gas ratio, Psbcl5/Psbcl4. This increase of the conductivity was attributed to donor electrons produced mainly by the pentavalent Sb ions in SnO2 lattice. However high input-gas ratio conditions produced an ATO film consisting of a mixture of SnO2 and very fine Sb2O5 phase. It was found that the deterioration of electrical conductivity and optical transmission of the film was caused by the deposition of fine Sb2O5 phase in the SnO2 matrix.

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Synthesis of Ultrafine Powders for Aluminum Nitride by DC Thermal Plasma (직류 열플라즈마를 이용한 질화알루미늄 초미세분말의 합성)

  • 안현;허민;홍상희
    • Journal of the Korean institute of surface engineering
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    • v.29 no.1
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    • pp.45-59
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    • 1996
  • Ultrafine powders(UFPs) of aluminum nitride(AlN) have been synthesized by chemical reactions in the nitrogen atmosphere and the gaseous aluminum evaporated from Al powders in thermal plasmas produced by a DC plasma torch. A synthesis system consisting of a plasma torch, a finely-controllable powder feeder, a reaction chamber, and a quenching-collection chamber have been designed and manufactured, and a filter for gathering AlN UFPs produced by the quenching process subsequent to the synthesis is set up. The synthesis process is interpreted by numerical analyses of the plasma-particle interaction and the chemical equilibrium state, respectively, and a fully-saturated fractional factorial test is used to find the optimum process conditions. The degrees and ultrafineness of synthesis are evaluated by means of SEM, TEM, XRD, and ESCA analyses. AlN UFPs synthesized in the optimum process conditions have polygonal shapes of the size of 5-100 nm, and their purities differ depending on collecting positions and filter types, and the maximum purity obtained is 72 wt% at the filter.

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Metal Complexes of Enrofloxacin Part I: Preparation, Spectroscopic, Thermal Analyses Studies and Antimicrobial Evaluation

  • El-Shwiniy, Walaa H.;El-Attar, Mohamed S.;Sadeek, Sadeek A.
    • Journal of the Korean Chemical Society
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    • v.57 no.1
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    • pp.52-62
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    • 2013
  • The interaction of titanium (IV), yttrium (III), zirconium (IV), palladium (II) and cerium (IV) with deprotonated enrofloxacin leads to the formation of the neutral or cationic mononuclear complexes. The isolated solid complexes have been characterized with physicochemical and spectroscopic techniques and thermogravimeteric analyses. The spectroscopic data indicate that the enrofloxacin ligand is on the deprotonated mode acting as bidentate ligand coordinated to the metal ions through the ketone oxygen and a carboxylato oxygen and the metal ions completed the coordination number with water molecules. The thermal decomposition mechanisms proposed for enrofloxacin and their metal complexes were discussed. The activation energies, $E^*$, enthalpies, ${\Delta}H^*$, entropies, ${\Delta}S^*$ and Gibbs free energies, ${\Delta}G^*$, of the thermal decomposition reactions have been derived from thermogravimetric (TG) and differential thermogravimetric (DTG) curves, using Coats-Redfern (CR) and Horowitz-Metzeger (HM) methods. The antimicrobial activity has been evaluated against six different microorganisms.

Design, Synthesis, and Antimicrobial Activity, of New 1,4-disubstituted Octahydroquinoxaline-2,3-dione Derivatives

  • Hussein, Mostafa A.
    • Bulletin of the Korean Chemical Society
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    • v.32 no.5
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    • pp.1511-1518
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    • 2011
  • A series of 1,4-disubstituted octahydroquinoxaline-2,3-dione derivatives was prepared through two steps reaction. The latter involves the formation of N,N-disubstituted cyclohexane-1,2-diamine derivatives (la-j) through reductive alkylation of 1,2-cyclohexanediamine with different aldehydes in presence of sodium cyanoborohydride. Fusion of compounds (1a-j) with diethyl oxalate affording the target compounds (2a-j). Elucidation of structures of compounds (2a-j) was based upon different spectral data as well as the elemental methods of analyses. In addition, mass spectrometry and X-ray diffraction analyses were carried out. Moreover, the lipophilicity of the target compounds as expressed from the Clog P. Most of the test compounds (2a-j) showed weak to moderate antibacterial and antifungal activities against most of the used bacterial and fungal strains in comparison to chloramphenicol and clotrimazole as reference drugs respectively.

Discrimination of Bacillus anthracis Spores by Direct in-situ Analysis of Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry

  • Jeong, Young-Su;Lee, Jonghee;Kim, Seong-Joo
    • Bulletin of the Korean Chemical Society
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    • v.34 no.9
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    • pp.2635-2639
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    • 2013
  • The rapid and accurate identification of biological agents is a critical step in the case of bio-terror and biological warfare attacks. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been widely used for the identification of microorganisms. In this study, we describe a method for the rapid and accurate discrimination of Bacillus anthracis spores using MALDI-TOF MS. Our direct in-situ analysis of MALDI-TOF MS does not involve subsequent high-resolution mass analyses and sample preparation steps. This method allowed the detection of species-specific biomarkers from each Bacillus spores. Especially, B. anthracis spores had specific biomarker peaks at 2503, 3089, 3376, 6684, 6698, 6753, and 6840 m/z. Cluster and PCA analyses of the mass spectra of Bacillus spores revealed distinctively separated clusters and within-groups similarity. Therefore, we believe that this method is effective in the real-time identification of biological warfare agents such as B. anthracis as well as other microorganisms in the field.

Feasibility of Phosphorus Recovery from Biological Livestock Wastewater Treatment Plant (생물학적 축산분뇨처리시설에서 인 회수의 가능성 평가)

  • Ahn, Johwan;Kim, Jangho;Min, Sungjae
    • Journal of Korean Society on Water Environment
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    • v.32 no.4
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    • pp.343-348
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    • 2016
  • A chemical sequencing batch reactor was operated to test the feasibility of nutrient recovery from a biological livestock wastewater treatment plant. Both phosphate and ammonia could be successfully recovered as magnesium ammonium phosphate (MAP) crystals. The contents of TP and TN in the recovered MAP crystals were 26.2% and 4.0%, respectively. Zn, Cr and Ti were identified in the crystals, but the contents remained below the Korean standard for an organic fertilizer. Chemical analyses confirmed that the MAP crystals could be useful phosphate fertilizers. On the other hand, the results of physical analyses using an X-ray diffractometer and an energy dispersive X-ray spectrometer strongly suggested that crystalline materials like magnesium potassium phosphate (KMP) and hydroxyapatite (HAP) were also formed during the MAP crystallization, depending on the availability of K+ and Ca2+.

Thermochemical Performance Analysis of Liquid Rocket Nozzle (액체로켓 노즐의 열화학적 성능 해석)

  • Choe,Jeong-Yeol;Choe,Hwan-Seok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.1
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    • pp.85-96
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    • 2003
  • For a design of rocket engine nozzle, chemical equilibrium analysis which shares the same numerical characteristics with frozen flow analysis can be used as an efficient design tool for predicting maximum thermodynamic performance of the nozzle. 10 this study, a chemical equilibrium flow analysis code was developed for the design of hydrocarbon fueled rocket engines. 10 oder to understand the thermochemical characteristics occurring in a nozzle through the expansion process, such as recombination of chemical components and the accompanying energy recovery, chemical equilibrium flow analysis was carried out for the KSR-III rocket engine nozzles together with frozen flow and non-equilibrium flow analyses. The performance evaluation based on the present KSR-III nozzle flow analyses has provided an understanding of the thermochemical process in the nozzle and additionally, it has confirmed that the newly designed nozzle shape modified to have a reduced exit area ratio is an adequate design for obtaining an increased ground thrust.

PLGA Microspheres in Hyaluronic Acid Gel as a Potential Bulking Agent for Urologic and Dermatologic Injection Therapies

  • KANG SUN-WOONG;CHO EUI RI;KIM BYUNG-SOO
    • Journal of Microbiology and Biotechnology
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    • v.15 no.3
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    • pp.510-518
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    • 2005
  • In this study, we investigated whether PLGA microspheres in combination with hyaluronic acid (HA) gel have appropriate properties as a bulking agent for urologic injection therapies and whether the implantation of PLGA microspheres and HA gel induces angiogenesis in the newly formed tissues. In order to investigate whether this bulking agent is injectable, this material was injected through 24-gauge needles into the subcutaneous dorsum of the mouse. The bulking agent was easily injected without needle obstruction. Histological analyses of the hybrid tissues at 2 weeks showed that host cells at the surrounding tissues migrated into the spaces between the implanted PLGA microspheres and formed tissue-like structures. An inflammatory response to the implants was mild at 2 weeks and diminished at 8 weeks. Importantly, extensive ingrowth of blood vessels was observed in the hybrid tissues formed by the injection of PLGA microspheres and HA, whereas blood vessels rarely formed in the hybrid tissues formed by the injection of PLGA microspheres only. The implant volume was conserved for almost the entire implantation period. Histological analyses of the distant organs of the bulking agent-implanted animals, such as the lungs, liver, heart, brain, kidney, and spleen, showed no evidence of the injected microsphere migration. These results show that PLGA microspheres in combination with HA possess the appropriate characteristics for a bulking agent for urologic injection therapies and induce extensive blood vessel formation in the hybrid tissues.

Performance and antifouling properties of PVDF/PVP and PSf membranes in MBR: A comparative study

  • Hazrati, Hossein;Karimi, Naser;Jafarzadeh, Yoones
    • Membrane Water Treatment
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    • v.11 no.2
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    • pp.159-166
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    • 2020
  • In this study, the performance and antifouling properties of polysulfone (PSf) and polyvinylidene fluoride/polyvinylpyrrolidone (PVDF/PVP) membranes in a membrane bioreactor (MBR) were investigated. The membranes were prepared via phase inversion method, and then characterized by a set of analyses including contact angle, porosity and water flux and applied in a lab-scale MBR system. Soluble microbial product (SMP), extracellular polymeric substance (EPS), FTIR, gel permission chromatography (GPC) and particle size distribution (PSD) analyses were also carried out for MBR system. The results showed that the MBR with PSf membrane had higher hydrophobic organic compounds which resulted in formation of larger flocs in MBR. However, in this MBR had high compressibility coefficient of cake layer was higher (n=0.91) compared to MBR with PVDF/PVP membrane (n=0.8); hence, the fouling was more profound. GPC analysis revealed that compounds with molecular weight lower than 2 kDa are more formed on PSf membrane more than PVDF/PVP membrane. The results of FTIR analysis confirmed the presence of polysaccharide and protein compounds on the cake layer of both membranes which was in good agreement with EPS analysis. In addition, the results showed that their concentration was higher for the cake on PSf membrane.