• Title/Summary/Keyword: Theoretical chemistry

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Residues of New Fungicide, Isopyrazam on Cucumber and Oriental Melon (Pyrazolecarboxamide계 살균제 Isopyrazam의 오이 및 참외 중 잔류특성)

  • Han, Ye-Hoon;Lee, Cheol-Yong;Park, Kwee-Doo;Park, Kwang-Wook;Lee, Kyu-Seung
    • The Korean Journal of Pesticide Science
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    • v.17 no.1
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    • pp.13-19
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    • 2013
  • Isopyrazam, a new pyrazolecarboxamide fungicide developed by Syngenta, was highly active against foliar powdery mildew pathogens on cucumber, oriental melon and various vegetables. Following foliar applications on cucumber and oriental melon, crop residues were determined using high performance liquid chromatography. For all studies, limit of quantification was 0.02 mg/kg and minimum detection level was 2.0 ng and recoveries were 83.0-88.0% on cucumber, 92.4-104.5% on oriental melon. Isopyrazam was detected 0.07-0.72 mg/kg on cucumber and < 0.02-0.68 mg/kg on oriental melon, respectively. The TMDI (Theoretical Maximum Dailly Intake) of isopyrazam on cucumber and oriental melon was estimated to less than 1.765% of ADI.

Effect of Lithium Bis(Oxalato)Borate Additive on Thermal Stability of Si Nanoparticle-based Anode (리튬 이차 전지용 실리콘 나노입자 음극의 고온 열안정성에 대한 Lithium bis(oxalato)borate첨가제의 효과)

  • Kim, Min-Jeong;Choi, Nam-Soon;Kim, Sung-Soo
    • Journal of the Korean Electrochemical Society
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    • v.17 no.2
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    • pp.79-85
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    • 2014
  • Silicon (Si) has been investigated as promising negative-electrode (anode) materials because its theoretical specific capacity of 4200 mAh/g for $Li_{4.4}Si$ is far higher than that of carbonaceous anodes in current commercial products. However, in practice, the application of Si to Li-ion batteries is still quite challenging because Si suffers from severe volume expansion and contraction and lead to a continuous solid electrolyte interphase (SEI)-filming process by cracking of Si. This process consumes the limited $Li^+$ source, builds up thick and unstable SEI layer on the Si active materials, and will eventually disable the cell. Since unstable SEI reduces electrochemical performance and thermal stability of the Si anode, the surface chemistry of the anode should be modified by using a functional additive. It is found that lithium bis(oxalato)borate (LiBOB) as an additive effectively protected the Si anode surface, improved capacity retention when stored at $60^{\circ}C$, and alleviated exothermic thermal reactions of fully lithiated Si anode.

Development of a Novel Process to produce Biodiesel and its use as fuel in CI Engine performance study

  • Mishra, Prasheet;Lakshmi, D.V.N.;Sahu, D.K.;Das, Ratnakar
    • International journal of advanced smart convergence
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    • v.4 no.1
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    • pp.154-161
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    • 2015
  • A novel process has successfully been developed by overcoming major difficulties through the elimination of number of process steps involved in the Classical Transesterification reaction during the preparation of Fatty Acid Methyl/Ethyl Ester (FAME.FAEE) called biodiesel. The Classical process with cost intensive process steps such as the utilization of excess alcohol, needing downstream distillation for the recovery and reutilization of excess alcohol/cosolvent, unrecoverable homogenous catalyst which consumes vast quantity of fresh distilled water during the purification of the product and downstream waste water treatment before its safe disposal to the surface water body. The Novel Process FAME/FAEE is produced from any vegetable oil irrespective of edible or inedible variety using sonication energy. The novelty of the finding is the use of only theoretical quantity of alcohol along with a co-solvent and reduced quantity of homogeneous catalyst. Under this condition neither the homogeneous catalyst goes to the FAME layer nor is the distillation needed. The same ester also has been prepared in high pressure high temperature reactor without using catalyst at sub critical temperature. The quality of prepared biodiesel without involving any purification step meets the ASTM standards. Blended Biodiesel with Common Diesel Fuel (CDF) and FAME is prepared, characterized and used as fuel in the Kirloskar make CI Engines. The evaluation of the engine performance result of pure CDF, B05 biodiesel, B10 biodiesel of all types of biodiesel prepared by using the feedstock of Soybean (Glycine max) and Karanja (Pongamia pinnate) oil along with their mixed oil provides useful information such as brake power, brake thermal efficiency, brake specific fuel consumption, etc, and established it as ideal fuel for unmodified CI engine.

EDISON Platform to Supporting Education and Integration Research in Computational Science (계산과학 분야의 교육 및 융합연구 지원을 위한 EDISON 플랫폼)

  • Jin, Du-Seok;Jung, Young-Jin;Jung, Hoe-Kyung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.1
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    • pp.176-182
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    • 2012
  • Recently, a new theoretical and methodological approach for computational science is becoming more and more popular for analyzing and solving scientific problems in various scientific disciplines and applied research. Computational science is a field of study concerned with constructing mathematical models and quantitative analysis techniques and using large computing resources to solve the problems which are difficult to approach in a physical experimentally. In this paper, we present R&D of EDISON open integration platform that allows anyone like professors, researchers, industrial workers, students etc to upload their advanced research result such as simulation SW to use and share based on the cyber infrastructure of supercomputer and network. EDISON platform, which consists of 3 tiers (EDISON application framework, EDISON middleware, and EDISON infra resources) provides Web portal for education and research in 5 areas (CFD, Chemistry, Physics, Structural Dynamics, Computational Design) and user service.

Determination of Reactivities by MO Theory (XV). Theoretical Studies on Conformations and Acid Catalysis of Acetamides (MO 理論에 依한 反應性의 決定 (第15報). 아세트아미드류의 형태와 산촉매반응에 관한 이론적 연구)

  • Ikchoon Lee;Dong Whan Park
    • Journal of the Korean Chemical Society
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    • v.23 no.6
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    • pp.358-367
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    • 1979
  • EHT and CNDO/2 calculations have been performed to determine conformations of acetamides and diacetamides, and of their protonated forms. Results show that: protonation is always favored on the cis position with respect to N due to greater attractive potential between $H^+$ and N; the trans-trans conformer of diacetamides gives the most preferred protonated form although the cis-trans conformer is the most stable one for the unprotonated diacetamides. Protonation on a carbonyl oxygen is predicted to increase both charge and orbital controlled $S_N$SN reactivities of the protonated carbonyl carbon due to increases in positive charge and AO coefficient of ${\pi}$-LUMO of the carbon atom. In the acid catalyzed hydrolysis of diacetamides therefore it appears highly probable that the rate determining attack by a water molecule occurs at the carbon of the protonated carbonyl group and the carbonyl carbon-nitrogen bond scission follows subsequently. This mechanism is consistent with that generally accepted for the hydrolysis of amides in dilute acid solution but disagrees with that proposed by Laureut et al., for acid hydrolysis of N-acetyl-lactams.

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A study on the apparent and partial molal volumes of n-Alkyl amine hydrochloride in water (n-Alkyl amine 鹽酸鹽의 水溶液 中에서의 apparent 및 partial molal volumes에 관한 硏究)

  • Yoon Sang Ki
    • Journal of the Korean Chemical Society
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    • v.13 no.2
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    • pp.121-129
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    • 1969
  • The apparent and partial molal volumes({\phi}\nu$and $V^{\circ}$) of a series of homologous n-alkylamine hydrochlorides $C_nH_{2n+1}NH_3^+Cl^-$, where n varies from zero to four, have been determined by means of a float method at 30$^{\circ}C$ to the fifth decimal place down to 0.01M in aqueous solutions. The experimental results indicate that the partial molal volumes of the salts are almost additive for successive homologues depending on the increment of molecular weight ($CH_2$). It has been observed that the concentration dependence of the ${\Phi}v$ are linear in general and limiting slopes are positive and relatively close to the theoretical values. Anionic partial molal volume of chlorides anion $V^{\circ}_{Cl^-}$ is found to be 18.6 ml $mole^{-1}$, which is in good agreement with the results of other workers. {\phi}\nu$ data also show that in solution the hydrophobic effect of ions are in competition with the charge effect, but the latter, that is, electrostriction seemed to be considerably predominant.

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A Study on the Measures for Activating the Fire Fighting Safety Education of Elementary School Students - Focusing on the Fire Fighting Science Class of Gyeonggi-do Goyang Fire Station - (초등학생 소방안전교육의 활성화 방안에 관한 연구 - 경기도 고양소방서 소방과학교실을 중심으로 -)

  • Hyun, Seong-Ho;Cha, Jeong-Min;Song, Yun-Suk;Park, Kyung-Hyo
    • Fire Science and Engineering
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    • v.23 no.2
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    • pp.67-77
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    • 2009
  • The purpose of this study is to deal with fire fighting safety education primarily among the fields of child safety education. So, first of all, this study considered the theoretical background of fire fighting safety education. And this study analyzed the present state and cases of safety accidents in elementary schools. And by focusing on the fire fighting science class for elementary schools which Gyeonggi-do Goyang fire station is executing now, this study analyzed the educational outline, present state, educational goal, and content of fire fighting science class, and conducted the satisfaction survey through questionnaire over the elementary school students participating in fire fighting science class and the fire fighting officers in charge of fire fighting science class. On basis of this research, by developing the new field of fire fighting education and publicity into the program which can diffuse the fire fighting-related chemical experiment based on the science of chemistry and physics in the future and so provide the pleasure and surprise of experiencing directly not only natural fire fighting education and publicity but also learning and the common sense of fire fighting, this study tried to present the alternatives about the measures for activating the fire fighting safety education in elementary schools.

Practical Use of Flux Gradient Similarity Theory for Forest Soil NO Flux at Mt. Taewha (Flux-gradient similarity theory 적용에 따른 태화산 산림지표 토양NO플럭스 분석)

  • Kim, Deug-Soo
    • Journal of Korean Society for Atmospheric Environment
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    • v.30 no.6
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    • pp.531-537
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    • 2014
  • Terrestrial vegetation has been known as a main source of biogenic volatile organic compounds (BVOCs). Isoprene and monoterpene among the BVOCs are most abundant species emitted by forests, and have a significant impact on atmospheric chemistry. Abundancy of these species could lead to an increase or decrease in the production of natural tropospheric ozone in forests, depending on the nitric oxide (NO) concentration. Soil is the most significant source of natural NO. Understanding of NO emission from forest soil could be critical in evaluation of air quality in the forest area. Flux-gradient similarity theory (FGST) was applied for practical use to estimate forest soil NO emission at Mt. Taewha where is available micro-meteorological data near surface monitoring from flux tower. NO fluxes calculated by FGST were compared to flux results by flow-through dynamic chamber (FDC) measurement. Surface NO emission trends were shown between two different techniques, however their magnitudes were found to be different. NO emissions measured from FDC technique were relatively higher than those from theoretical results. Daily mean NO emissions resulted from FGST during Aug. 13, 14 and 15 were $0.28{\pm}8.45$, $2.17{\pm}15.55$, and $-3.18{\pm}13.65{\mu}gm^{-2}hr^{-1}$, respectively, while results from FDC were $2.26{\pm}1.44$, $5.11{\pm}3.85$, and $2.23{\pm}6.45{\mu}gm^{-2}hr^{-1}$. Trends of daily means were shown in similar pattern, which NO emissions were increasing during late afternoon ($r^2$=0.04). These emission trends could be because soil temperature and moisture influence importantly soil microbiology.

Modification of Substrate Inhibition of Synaptosomal Acetylcholinesterase by Cardiotoxins

  • Ranaei-Siadat, Seyed-Omid;Riazi, Gholam-Hosein;Sadeghi, Mehdi;Chang, Long-Sen;Lin, Shinne-Ren;Eghtesadi-Araghi, Peyman;Hakimelahi, Gholam Hossein;Moosavi-Movahedi, Ali Akbar
    • BMB Reports
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    • v.37 no.3
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    • pp.330-338
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    • 2004
  • Different types of cardiotoxin (I-V and n) were isolated and purified from the venom of the Taiwan cobra (Naja naja atra). The effects of these cardiotoxins were studied on membrane-bound acetylcholinesterase, which was isolated from a sheep's brain cortex. The results showed that cardiotoxins I-III, V, and n activated the enzyme by modification of substrate inhibition, but cardiotoxin IV's reaction was different. The inhibition and activation of acetylcholinesterase were linked to the functions of the hydrophobicity index, presence of a cationic cluster, and the accessible arginine residue. Our results indicate that Cardiotoxins have neither a cationic cluster nor an arginine residue in their surface area of loop I; therefore, in contrast to fasciculin, cardiotoxins are attached by loop II to the peripheral site of the enzyme. As a result, fasciculin seems to stabilize nonfunctional conformation, but cardiotoxins seem to stabilize the functional conformation of the enzyme. Based on our experimental and theoretical findings, similar secondary and tertiary structures of cardiotoxins and fasciculin seem to have an opposite function once they interact with acetylcholinesterase.

A New Analytical Method for the $Dy^{3+}$ Ion Using the Luminescence Enhancement by the Treatment of o-Phenanthroline on the TLC Plate (TLC Plate에서의 발광증폭 및 o-Phenanthroline에 의한 Energy Transfer를 이용한 $Dy^{3+}$ 이온의 미량 분석법)

  • Jeong, Hyuk
    • Analytical Science and Technology
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    • v.11 no.5
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    • pp.386-393
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    • 1998
  • A new analytical luminescence method for the $Dy^{3+}$ ion was studied using the luminescence enhancement by the treatment of the o-phenanthroline on the TLC plate. Compared to the specific emission intensities of the ion in water solution, if the ion solution is spotted on the TLC plate, the luminescence intensities were extremely enhanced. There was additional enhancement effect of the luminescence intensities of the ions on the TLC plate, if the ion on the TLC plate is treated with o-phenanthroline. Based on the luminescence enhancement, the detection limit was improved by more than 4 order of magnitude compared to that of solution sample. The dynamic ranges and correlation coefficients of the calibration curves near the detection limit were 102 order and ~0.99, respectively. The energy-transfer mechanism was explained for the theoretical back ground of the luminescence enhancement.

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