• 제목/요약/키워드: Reaction parameter

검색결과 477건 처리시간 0.026초

만성 속발성 신질환 모델동물에서 콜라젠 변화의 지표 (Markers of Collagen Change in Chronic Secondary Renal Disease Model in Rat)

  • 남정석;김기영;이영순
    • Toxicological Research
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    • 제12권2호
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    • pp.213-221
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    • 1996
  • In order to develop a suitable secondary renal disease model and diagnostic markers of renal disease in the rat, the change of PIIIP (aminoterminal procollagen III peptide) in serum and hydroxyproline levels in the renal tissue that reflect the synthesis of extracellular matrix (ECM) during development of experimental renal diseases were observed. Two types of experimental primary diseases, diabetes mellitus administrated by streptozotocin (STZ, 75 mg/kg, i.p.) and liver cirrhosis produced by bile duct ligation/scission (BDL/s) operation, were induced. The hydroxyproline level increased according to the high PIIIP and NCl(carboxyterminal procollagen IV peptide) in Western blot analysis as early as 1 week in the STZ treated-rat kidney. Increased renal ECM was observed at 15 weeks in STZ and BDL/s model under the microscopic examination. High PAS positive reaction was found in capillary basement membrane in STZ treated-rats and mesangium in BDL/s operated rats at this time, showing the histological characteristics of diabetic nephropathy and cirrhotic glomerulonephritis in human, respectively. Such secondary renal failure were supported by additional tests including urinalysis and renal function test. The serum PIIIP detected by ELISA was a useful parameter to estimate synthesis rate of renal ECM during development of renal disease without extrarenal fibrosis i.e. liver cirrhosis in rats. This study is proposed that STZ treatment or BDL/s operation may be a suitable experimental animal model for the induction and development of chronic secondary renal diseases. Morover, it was found that hydroxyproline level in renal tissues was a good parameter of the change of renal ECM at the early stage of the diseases without apparent histological changes. Especially, serum PIIIP could be a choice as a diagnostic or prognostic marker during the development of renal diseases in rats.

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Effects of Synthesis Method, Melamine Content and GPC Parameter on the Molecular Weight of Melamine-Urea-Formaldehyde Resins

  • KIM, Minjeong;PARK, Byung-Dae
    • Journal of the Korean Wood Science and Technology
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    • 제49권1호
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    • pp.1-13
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    • 2021
  • This study was conducted to investigate the effects of the synthesis method, melamine content, and GPC parameters (such as flow rate, column-detector temperature, and sample injection temperature) on the molecular weight of melamine-urea-formaldehyde (MUF) resins. Two different synthesis methods were employed. In the first method, MUF-A resins were synthesized by simultaneously reacting urea, formaldehyde, and melamine (5%, 10%, and 20%) using the reaction of alkaline-acid-alkaline steps under controlled temperature and viscosity. In the second method, MUF-B resins were synthesized by first reacting melamine at the same levels with formaldehyde and then by adding urea. The highest weight average molecular weight (Mw) of MUF-A resins was found at 10% melamine content when the flow rate was 0.3 and 0.8 ml/min; Mw decreased slightly at 20% melamine content. The results showed that Mw increased with an increase in the melamine content when the flow rate was 0.5 and 1.0 ml/min. In addition, Mw was the highest when the flow rate, column-detector temperature, and injection temperature were 0.3 ml/min, 50℃, and 25℃, respectively. On the contrary, MUF-B resins had greater Mw and number average molecular weight (Mn) than MUF-A resins. Overall, Mw and Mn increased as the melamine content increased. The optimal GPC parameter for MUF resins was determined as follows: a flow rate of 0.5 ml/min, a column-detector temperature of 50℃, and a sample injection temperature of 50℃.

Electrochemical treatment of cefalexin with Sb-doped SnO2 anode: Anode characterization and parameter effects

  • Ayse, Kurt;Hande, Helvacıoglu;Taner, Yonar
    • Advances in nano research
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    • 제13권6호
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    • pp.513-525
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    • 2022
  • In this study, it was aimed to evaluate direct oxidation of aqueous solution containing cefalexin antibiotic with new generation Sn/Sb/Ni: 500/8/1 anode. The fact that there is no such a study on treatment of cefalexin with these new anode made this study unique. According to the operating parameters evaluation COD graphs showed clearer results compared to TOC and CLX and thus, it was it was chosen as major parameter. Furthermore, pseudo-first degree kd values were calculated from CLX results to show more accurate and specific results. Experimental results showed that after 60 min of electrochemical oxidation, complete removal of COD and TOC was accomplished with 750 mg L-1 KCl, at pH 7, 50 mA cm-2 current density and 1 cm anode-cathode distance. Also, the stability of the Sn/Sb/Ni anode was evaluated by taking SEM and AFM images and XRD analysis before and after of electrochemical oxidation processes. According to the results, it was not occurred too much change on the anode surface even after 300 h of electrolysis. Thus, it was thought that the anode material was not corroded to a large extent. Furthermore, the removal efficiencies were very high for almost all the time and conditions. According to the results of the study, electrochemical oxidation with new generation Sn/Sb/Ni anodes for the removal of cefalexin antibiotic was found very successful and applicable due to require less reaction time complete mineralization and doesn't require pH adjustment step compared to other studies in literature. In future studies, different antibiotic types should be studied with this anode and maybe with real wastewaters to test applicability of the process in treatment of pharmaceutical wastewaters containing antibiotics, in a better way.

Glass Dissolution Rates From MCC-1 and Flow-Through Tests

  • Jeong, Seung-Young
    • 한국방사성폐기물학회:학술대회논문집
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    • 한국방사성폐기물학회 2004년도 학술논문집
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    • pp.257-258
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    • 2004
  • The dose from radionuclides released from high-level radioactive waste (HLW) glasses as they corrode must be taken into account when assessing the performance of a disposal system. In the performance assessment (PA) calculations conducted for the proposed Yucca Mountain, Nevada, disposal system, the release of radionuclides is conservatively assumed to occur at the same rate the glass matrix dissolves. A simple model was developed to calculate the glass dissolution rate of HLW glasses in these PA calculations [1]. For the PA calculations that were conducted for Site Recommendation, it was necessary to identify ranges of parameter values that bounded the dissolution rates of the wide range of HLW glass compositions that will be disposed. The values and ranges of the model parameters for the pH and temperature dependencies were extracted from the results of SPFT, static leach tests, and Soxhlet tests available in the literature. Static leach tests were conducted with a range of glass compositions to measure values for the glass composition parameter. The glass dissolution rate depends on temperature, pH, and the compositions of the glass and solution, The dissolution rate is calculated using Eq. 1: $rate{\;}={\;}k_{o}10^{(ph){\eta})}{\cdot}e^{(-Ea/RT)}{\cdot}(1-Q/K){\;}+{\;}k_{long}$ where $k_{0},\;{\eta}$ and Eaare the parameters for glass composition, pH, $\eta$ and temperature dependence, respectively, and R is the gas constant. The term (1-Q/K) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_{0},\;{\eta}\;and\;E_{a}$ are the parameters for glass composition, pH, and temperature dependence, respectively, and R is the gas constant. The term (1-Q/C) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_0$, and Ea are determined under test conditions where the value of Q is maintained near zero, so that the value of the affinity term remains near 1. The dissolution rate under conditions in which the value of the affinity term is near 1 is referred to as the forward rate. This is the highest dissolution rate that can occur at a particular pH and temperature. The value of the parameter K is determined from experiments in which the value of the ion activity product approaches the value of K. This results in a decrease in the value of the affinity term and the dissolution rate. The highly dilute solutions required to measure the forward rate and extract values for $k_0$, $\eta$, and Ea can be maintained by conducting dynamic tests in which the test solution is removed from the reaction cell and replaced with fresh solution. In the single-pass flow-through (PFT) test method, this is done by continuously pumping the test solution through the reaction cell. Alternatively, static tests can be conducted with sufficient solution volume that the solution concentrations of dissolved glass components do not increase significantly during the test. Both the SPFT and static tests can ve conducted for a wide range of pH values and temperatures. Both static and SPFt tests have short-comings. the SPFT test requires analysis of several solutions (typically 6-10) at each of several flow rates to determine the glass dissolution rate at each pH and temperature. As will be shown, the rate measured in an SPFt test depends on the solution flow rate. The solutions in static tests will eventually become concentrated enough to affect the dissolution rate. In both the SPFt and static test methods. a compromise is required between the need to minimize the effects of dissolved components on the dissolution rate and the need to attain solution concentrations that are high enough to analyze. In the paper, we compare the results of static leach tests and SPFT tests conducted with simple 5-component glass to confirm the equivalence of SPFT tests and static tests conducted with pH buffer solutions. Tests were conducted over the range pH values that are most relevant for waste glass disssolution in a disposal system. The glass and temperature used in the tests were selected to allow direct comparison with SPFT tests conducted previously. The ability to measure parameter values with more than one test method and an understanding of how the rate measured in each test is affected by various test parameters provides added confidence to the measured values. The dissolution rate of a simple 5-component glass was measured at pH values of 6.2, 8.3, and 9.6 and $70^{\circ}C$ using static tests and single-pass flow-through (SPFT) tests. Similar rates were measured with the two methods. However, the measured rates are about 10X higher than the rates measured previously for a glass having the same composition using an SPFT test method. Differences are attributed to effects of the solution flow rate on the glass dissolution reate and how the specific surface area of crushed glass is estimated. This comparison indicates the need to standardize the SPFT test procedure.

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석탄 가스화 반응의 동적 거동 전산 모사 (Dynamic Modeling of Gasification Reactions in Entrained Coal Gasifier)

  • 지준화;오민;김시문;김미영;이중원;김의식
    • 한국수소및신에너지학회논문집
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    • 제22권3호
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    • pp.386-401
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    • 2011
  • Mathematical models for various steps in coal gasification reactions were developed and applied to investigate the effects of operation parameters on dynamic behavior of gasification process. Chemical reactions considered in these models were pyrolysis, volatile combustion, water shift reaction, steam-methane reformation, and char gasification. Kinetics of heterogeneous reactions between char and gaseous agents was based on Random pore model. Momentum balance and Stokes' law were used to estimate the residence time of solid particles (char) in an up-flow reactor. The effects of operation parameters on syngas composition, reaction temperature, carbon conversion were verified. Parameters considered here for this purpose were $O_2$-to-coal mass ratio, pressure of reactor, composition of coal, diameter of char particle. On the basis of these parametric studies some quantitative parameter-response relationships were established from both dynamic and steady-state point of view. Without depending on steady state approximation, the present model can describe both transient and long-time limit behavior of the gasification system and accordingly serve as a proto-type dynamic simulator of coal gasification process. Incorporation of heat transfer through heterogenous boundaries, slag formation and steam generation is under progress and additional refinement of mathematical models to reflect the actual design of commercial gasifiers will be made in the near futureK.

Electrochemical Properties of LiNiyMn2-yO4 Prepared by the Solid-state Reaction

  • Song, Myoung-Youp;Kwon, Ik-Hyun;Shon, Mi-Suk
    • 한국세라믹학회지
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    • 제40권5호
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    • pp.401-404
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    • 2003
  • LiN $i_{y}$M $n_{2-y}$ $O_4$were synthesized by calcining a mixture of LiOH, Mn $O_2$(CMD), and NiO at 40$0^{\circ}C$ for 10 h and then calcining at 85$0^{\circ}C$ for 48 h in air with intermediate grinding. The voltage vs. discharge capacity curves at a current density 300 $\mu$A/c $m^2$ between 3.5 V and 4.3 V showed two plateaus, but the plateaus became ambiguous as the y value increases. The sample with y=0.02 had the largest first discharge capacity, 118.1 mAh/g. As the value y increases from 0.02 up to 0.2, on the whole, the cycling performance became better. The LiN $i_{0.10}$M $n_{1.90}$ $O_4$sample had a relatively large first discharge capacity 95.0 mAh/g and showed an excellent cycling performance. The samples with larger lattice parameter have, in general, larger discharge capacities. The reduction curves in the cyclic voltammograms for the y=0.05-0.20 samples exhibit three peak showing that the reduction may proceed in three stages in these samples. For the samples with relatively large discharge capacity, the lattice destruction induced by strain causes the capacity fading of LiN $i_{y}$M $n_{2-y}$ $O_4$ with cycling.cling.ing.

이중동축 메탄/공기 층류 부분 예혼합화염에서의 화염구조와 자발광 배출 특성;안쪽관 연료주입의 영향 (Flame Structure and Light Emission Characteristics in Coaxial Laminar Partially Premixed $CH_{4}/Air$ Flames;Effect of Central Fuel Injection)

  • 오정석;정용기;전충환;장영준
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 추계학술대회
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    • pp.1116-1121
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    • 2004
  • In this study, the effect of central fuel injection on a coaxial laminar $CH_{4}/air$ flame was experimented at the defined premixing condition(${\Phi}=1.90$, ${\sigma}=50/75/100%$, x/D=10). The partial premixing parameter are the equivalence ratio that total fuel is fixed at 200cc/min, the fuel split degree which means the percentage of fuel entering the outer tube to the total amount, and the mixing distance indicating the nonreactant mixture's homogeneity between inner tube top and burner exit. The object is to investigate the flame structure and chemiluminescence characteristics of laminar partial premixed flame as changing mixing parameters. The radical signal was acquired from ICCD camera and PMT. Each intensity was compared with Abel inverted value for measuring the effect of background light on the peak signal location and the intensity at central preheat zone. The results show that the peak location of each radical was broaden as the fuel split degree increasing because the mixing quality was enhanced. and $OH^{\ast}$ is a good indicator for flame front between reaction and preheat zone. At last $CH_{2}^{\ast}$ has the same tendency with $CH^{\ast}$ but a thinner reaction zone than $CH^{\ast}$ due to a rapid decay on the burned gas side.

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GPS-X 시뮬레이션을 이용한 2단탈질 공정에서 외부탄소원 적용성 평가 (Evaluation of External Carbon Source on the 2 Stage Denitrification Process by Simulation of GPS-X)

  • 정창화;심유섭;김태형;박철휘
    • 상하수도학회지
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    • 제18권1호
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    • pp.37-48
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    • 2004
  • The purpose of this study was to evaluate adaptability of external carbon source using GPS-X program in pilot plant composed with 2-stage denitrification process. The result from analysis of pilot plant operation and GPS-X simulation showed that effluent concentration could be simulated similarly by modifying operation conditions, such as DO concentration, C/N ratio and other calibrated parameter. In order to satisfy the standard of the effluent water quality on T-N of 20mg/L, it required approximately 3.1 of C/N ratio and 50% of nitrogen removal efficiency when influent T-N is 36.9mg/L. To maintain the stable water quality of the receiving water, the effluent T-N concentration should be less than 10-15mg/L and the appropriate C/N ratio to remove nitrogen was 4.27-6.82. The analysis of sensitivity to kinetic coefficient and reaction constant showed that $Y_H$ and ${\mu}_{mAUT}$ were most sensitive to nitrate and ammonia nitrogen, relatively and sensitivity coefficient of their were 1.32, 1.98. It was concluded that as $Y_H$ decreased and ${\mu}_{mAUT}$ increased, the reaction rates of denitrification and nitrification increased and the removal efficiencies of $NO_3{^-}-N$ and $NH_4{^+}-N$ improved.

소성 및 산소농도 조건에 대한 Mn-Cu-TiO2 촉매의 탈질 특성 (NOx removal of Mn-Cu-TiO2 catalyst for the calcination and oxygen concentration conditions)

  • 장현태;차왕석
    • 한국산학기술학회논문지
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    • 제16권1호
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    • pp.900-905
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    • 2015
  • 본 Mn-Cu-$TiO_2$ Civil 촉매를 이용하여 질소산화물을 제거하는 $NH_3$-SCR 공정에서 소성조건 및 산소농도에 대한 영향을 연구하였다. 소성된 촉매시료를 사용하여 $H_2$-TPR 시스템에서 반응온도에 따른 수소전환특성을 조사하였으며, 소성조건에 대한 비표면적변화도 측정하였다. 실험결과 적합한 소성온도는 약 $300^{\circ}C$이며, 소성온도가 $500^{\circ}C$이상일 경우 Mn, Cu 성분의 저온활성이 크게 감소함을 알 수 있었다. SCR반응에서 기상산소는 중요한 반응변수이며 반응에 적합한 농도는 약 8vol%이었다.

전기산화공법을 이용한 고농도폐수 처리공정의 모델링 및 최적화 (Modeling and Optimization of High Strength Wastewater Treatment Using the Electro Oxidation Process)

  • 이홍민;이상선;황성원;진동복
    • Korean Chemical Engineering Research
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    • 제54권3호
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    • pp.340-349
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    • 2016
  • 본 연구에서는 정유산업의 유지 및 보수기간에 배출되는 고농도폐수의 COD (Chemical Oxygen Demand)를 효과적으로 제거하기 위해 전기산화공법을 적용하였다. 우선 산업에서 배출되는 실제 폐수를 처리하기 위하여 BDD전극을 개발하고, 개발된 전극을 이용하여 전류밀도, pH, 전해질농도, 반응시간 등과 같은 다양한 운전조건하에 실험을 진행하였다. 둘째, 이러한 실험결과를 이용하여 전기분해의 kinetic parameter를 산출한 후에, 이를 토대로 전기산화 처리설비를 수학적으로 모델링 하였다. 마지막으로, 기존에 정상운전 조건 시 사용하던 저 농도 폐수를 처리하는 공정의 유입조건에 맞추기 위하여 전기산화 처리설비의 설계 및 운전의 다양한 변수들을 최적화함으로써 보다 효율적인 폐수 전처리 시스템을 개발하였다. 본 연구를 통해 개발된 모델의 결정계수($R^2$)는 0.982로 상당히 작은 오차범위를 보여줌으로써 모델의 높은 정확도를 입증하였다.