• Title/Summary/Keyword: 3-D Mechanism

Search Result 1,725, Processing Time 0.031 seconds

Comparative study on Corrosion Inhibition of Vietnam Orange Peel Essential Oil with Urotropine and Insight of Corrosion Inhibition Mechanism for Mild Steel in Hydrochloric Solution

  • Bui, Huyen T.T.;Dang, Trung-Dung;Le, Hang T.T.;Hoang, Thuy T.B.
    • Journal of Electrochemical Science and Technology
    • /
    • v.10 no.1
    • /
    • pp.69-81
    • /
    • 2019
  • The corrosion inhibiting mechanism of Vietnam orange peel essential oil (OPEO) for mild steel in 1 N HCl solution was investigated elaborately. Corrosion inhibition ability of OPEO was characterized by electrochemical polarization, electrochemical impedance spectroscopy (EIS), and weight loss method. In the corrosive solution, OPEO worked as a mixed inhibitor and the inhibition efficiency of OPEO increased with the increase of its concentration. High inhibition efficiencies over 90% were achieved for the concentration of 3 - 4 g/L OPEO, comparable to that of 3.5 g/L urotropine (URO), a commercial corrosion inhibitor for acid media used in industry. By using adsorption isotherm models (Langmuir, Temkin and Frumkin), thermodynamic parameters of adsorption were calculated. The obtained results indicated physical adsorption mechanism of OPEO on the steel surface. The components responsible for the corrosion inhibition activity of OPEO were not only D-limonene, but also other compounds, which contain C=O, C=C, O-H, C-O-C, -C=CH and C-H bonding groups in the molecules.

Nano-Scale Cu Direct Bonding Technology Using Ultra-High Density, Fine Size Cu Nano-Pillar (CNP) for Exascale 2.5D/3D Integrated System

  • Lee, Kang-Wook
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.23 no.4
    • /
    • pp.69-77
    • /
    • 2016
  • We propose nano-scale Cu direct bonding technology using ultra-high density Cu nano-pillar (CNP) with for high stacking yield exascale 2.5D/3D integration. We clarified the joining mechanism of nano-scale Cu direct bonding using CNP. Nano-scale Cu pillar easily bond with Cu electrode by re-crystallization of CNP due to the solid phase diffusion and by morphology change of CNP to minimize interfacial energy at relatively lower temperature and pressure compared to conventional micro-scale Cu direct bonding. We confirmed for the first time that 4.3 million electrodes per die are successfully connected in series with the joining yield of 100%. The joining resistance of CNP bundle with $80{\mu}m$ height is around 30 m for each pair of $10{\mu}m$ dia. electrode. Capacitance value of CNP bundle with $3{\mu}m$ length and $80{\mu}m$ height is around 0.6fF. Eye-diagram pattern shows no degradation even at 10Gbps data rate after the lamination of anisotropic conductive film.

Estimation of 3D active earth pressure under nonlinear strength condition

  • Zhang, D.B.;Jiang, Y.;Yang, X.L.
    • Geomechanics and Engineering
    • /
    • v.17 no.6
    • /
    • pp.515-525
    • /
    • 2019
  • The calculation of active earth pressure behind retaining wall is a typical three-dimensional (3D) problem with spatial effects. With the help of limit analysis, this paper firstly deduces the internal energy dissipation power equations and various external forces power equations of the 3D retaining wall under the nonlinear strength condition, such as to establish the work-energy balance equation. The pseudo-static method is used to consider the effect of earthquake on active earth pressure in horizontal state. The failure mode is a 3D curvilinear cone failure mechanism. For the different width of the retaining wall, the plane strain block is inserted in the symmetric plane. By optimizing all parameters, the maximum value of active earth pressure is calculated. In order to verify the validity of the new expressions obtained by the paper, the solutions are compared with previously published solutions. Agreement shows that the new expressions are effective. The results of different parameters are given in the forms of figures to analysis the influence caused by nonlinear strength parameters.

Characterization of valacyclovir transport mechanism across the intestinal epithelium

  • Han, H.;Covitz, M.;Surendran, N.;Stewart, B.;Amidon, G.L.
    • Proceedings of the Korean Society of Applied Pharmacology
    • /
    • 1997.04a
    • /
    • pp.119-119
    • /
    • 1997
  • Valacyclovir is a L-valyl ester prodrug of acyclovir which is a highly effective and selective antiviral agent in the treatment of herpes virus diseases. Valacyclovir is rapidly and almost completely converted to acyclovir and increases the oral bioavailability of acyclovir three to five fold. However, the intestinal absorption mechanism of valacyclovir is not clear. If the improved absorption mechanism of valacyclovir is fully understood, it will provide a rationale of designing the amino acid ester prodrugs of polar drugs containing hydroxyl group. The main objective of our present study is to characterize the membrane transport mechanism of valacyclovir. Methods : Intestinal absorption of valacyclovir was investigated by using in-situ rat perfusion study and its wall permeability was estimated by modified boundary layer model. The membrane transport mechanism was also investigated through the uptake study in Caco-2 cells and in CHO-hPepTl cells. Results : In the rat perfusion study, the wall permeability of valacyclovir was ten times higher than acyclovir and showed concentration dependency, Valacyclovir also demonstrated a D,L stereo-selectivity with L-isomer having an approximately five-fold higher permeability than D-isomer. Mixed dipeptides and cephalexin, which are transported by dipeptide carriers, strongly competed with valacyclovir for the intestinal absorption, while L-valine did not show any competition with valacyclovir. This indicated that the intestinal absorption of valacyclovir could be dipeptide carrier-mediated. In addition, the competitive uptake study in Caco-2 cells presented that dipeptides reduced the valacyclovir uptake but valine did not. Also, in IC$\sub$50/ study, valacyclovir showed strong inhibition on the $^3$H-gly-sar uptake in CHO-hPepTl cells over-expressing a human intestinal peptide transporter. Taken together, the result from our present study indicated that valacyclovir utilized the peptide transporter for the intestinal absorption.

  • PDF

The Cofactors Role on Chemical Mechanism of Recombinant Acetohydroxy Acid Synthase from Tobacco

  • Kim, Joung-Mok;Kim, Jung-Rim;Kim, Young-Tae;Choi, Jung-Do;Yoon, Moon-Young
    • Bulletin of the Korean Chemical Society
    • /
    • v.25 no.5
    • /
    • pp.721-725
    • /
    • 2004
  • Acetohydroxy acid synthase (AHAS) is one of several enzymes that require thiamine diphosphate and a divalent cation as essential cofactors. The active site contains several conserved ionizable groups and all of these appear to be important as judged by the fact that mutation diminishes or abolishes catalytic activity. Recently, we have shown [Yoon, M.-Y., Hwang, J.-H., Choi, M.-K., Baek, D.-K., Kim, J., Kim, Y.-T., Choi, J.-D. FEBS Letters 555 (2003), 185-191] that the activity is pH-dependent due to changes in $V_{max}$ and V/$K_m$. Data were consistent with a mechanism in which substrate was selectively catalyzed by the enzyme with an unprotonated base having a pK 6.48, and a protonated group having a pK of 8.25 for catalysis. Here, we have in detail studied the pH dependence of the kinetic parameters of the cofactors (ThDP, FAD, $Mg^{2+}$) in order to obtain information about the chemical mechanism in the active site. The $V_{max}$ of kinetic parameters for all cofactors was pH-dependent on the basic side. The pK of ThDP, FAD and $Mg^{2+}$ was 9.5, 9.3 and 10.1, respectively. The V/$K_m$ of kinetic parameters for all cofactors was pH-dependent on the acidic and on the basic side. The pK of ThDP, FAD and $Mg^{2+}$ was 6.2-6.4 on the acidic side and 9.0-9.1 on the basic side. The well-conserved histidine mutant (H392) did not affect the pH-dependence of the kinetic parameters. The data are discussed in terms of the acid-base chemical mechanism.

3-D Numerical Analysis for the Verification of Bearing Mechanism and Bearing Capacity Enhancement Effect on the Base Expansion Micropile (선단 확장형 마이크로파일의 3차원 수치해석을 통한 지지 메커니즘 및 지지력 증대효과 검증)

  • Lee, Seokhyung;Han, Jin-Tae;Jin, Hyun-Sik;Kim, Seok-Jung
    • Journal of the Korean Geotechnical Society
    • /
    • v.37 no.2
    • /
    • pp.19-31
    • /
    • 2021
  • Micropiles are cast-in-place piles with small diameters. The advantage of micropile is low construction expense and simple procedures, so it is widely applied to existing buildings and structures for the reinforcement of foundation and seismic performances. The base expansion structure has been developed following the original mechanism of horizontal expansion steps under compressive loading. This kind of structure can be installed at the pile end to improve the bearing capacity by tip area enlargement and horizontal force increment to the pile surface area. However, 'Micropile with base expansion structure' cannot be put into practical use, because detailed verification for the developed technique has not been conducted so far. In this research, 3-D numerical analysis was conducted to figure out the bearing mechanism of base expansion micropile and to verify the bearing capacity improvement compared to the general micropiles. 3-D modelling of micropile with base expansion structure was carried out and input parameter was determined. Bearing mechanism induced by base expansion structure was analyzed by lab-scale modelling, and bearing capacity improvement was verified by field-scale analysis.

An Analysis on the Failure Mechanism of Slope behind a Plant Complex of Gimhae due to Typhoon Rusa (태풍 루사에 의한 김해 OO단지 사면붕괴 발생원인 분석)

  • Kang, In-Kyu;Ryu, Jeong-Soo;Kim, Hong-Taek;Baek, Seung-Cheol
    • 한국방재학회:학술대회논문집
    • /
    • 2007.02a
    • /
    • pp.263-266
    • /
    • 2007
  • In this paper, analysis results on the failure of slope behind a Plant Complex of Gimhae due to typhoon Rusa in 2002 are introduced. The left side of the slope was reinforced by soil nails and the right side of the slope was going to construct slope reinforcement works. In the slope failure, the damage area is about $34,000m^2$, the lower width of slope failure is about 230m, the upper width of slope failure is about 50m, and the height of slope failure is about 120m. The elevation of a bedrock in the right side of the slope was lower than the left side of the slope. Due to the depth of weathered soils and weathered rocks in right side of the slope was thick, it will be expected that the effects of pore-water pressure during the rainfalls are large. For the analysis of the failure mechanism, 3-dimensional numerical analysis was carried out by FLAC-3D.

  • PDF

Large Eddy Simulation for the investigation of Roll Development Process in a Solid Rocket Motor (고체로켓 내부에서의 Roll 발생 현상 3D LES)

  • Kim, Jong-Chan;Hong, Ji-Seok;Yeom, Hyo-Won;Moon, Hee-Jang;Kim, Jin-Kon;Sung, Hong-Gye
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2011.04a
    • /
    • pp.253-257
    • /
    • 2011
  • Vortex generation mechanism by inhibitor in a solid rocket motor have been investigated by 3D Large Eddy Simulation turbulent model. Most of the result of the present study are in good agreement with experimental data and previous numerical calculation. Vortex generation and breakdown behind inhibitor are periodically observed between inhibitor and nozzle head by flow-acoustic coupling mechanism. Vortex generation frequency is the same as the second-mode frequency in the motor. The roll shape vortex generation behind inhibitor induces non-uniform flow field at the nozzle entrance and its throat.

  • PDF

Theoretical Studies on the Addition Reactions of Ketene with NH3 in the Gas Phase and in Non-Aqueous Solutions

  • Kim, Chang-Kon;Lee, Kyung A;Chen, Junxian;Lee, Hai-Whang;Lee, Bon-Su;Kim, Chan-Kyung
    • Bulletin of the Korean Chemical Society
    • /
    • v.29 no.7
    • /
    • pp.1335-1343
    • /
    • 2008
  • Theoretical studies on the un-catalyzed and catalyzed aminations of ketene with $NH_3$ and $(NH_3)_2$, respectively, were studied using MP2 and hybrid density functional theory of B3LYP at the 6-31+G(d,p) and 6- 311+G(3df,2p) basis sets in the gas phase and in benzene and acetonitrile solvents. In the gas phase reaction, the un-catalyzed mechanism was the same as those previously reported by others. The catalyzed mechanism, however, was more complicated than expected requiring three transition states for the complete description of the C=O addition pathways. In the un-catalyzed amination, rate determining step was the breakdown of enol amide but in the catalyzed reaction, it was changed to the formation of enol amide, which was contradictory to the previous findings. Starting from the gas-phase structures, all structures were re-optimized using the CPCM method in solvent medium. In a high dielectric medium, acetonitrile, a zwitterions formed from the reaction of $CH_2$=C=O with $(NH_3)_2$, I(d), exists as a genuine minimum but other zwitterions, I(m) in acetonitrile and I(d) in benzene become unstable when ZPE corrected energies are used. Structural and energetic changes induced by solvation were considered in detail. Lowering of the activation energy by introducing additional $NH_3$ molecule amounted to ca. −20 $\sim$ −25 kcal/mol, which made catalyzed reaction more facile than un-catalyzed one.

Initial investigation of 3D free form fabrication Using Contour Crafting with the pivoting side trowel (적층조형설비(CC)을 이용한 3차원모형 제작에 대한 연구)

  • Kwon, Hong-Kyu;Hong, Jung-Eui;Chung, Soo-Suk
    • Proceedings of the Safety Management and Science Conference
    • /
    • 2006.11a
    • /
    • pp.437-450
    • /
    • 2006
  • The Contour Crafting(CC) process, which has been developed at the University of Southern California, aims at automated construction of whole houses as well as sub-components. For this purpose, new trowel mechanism is basically needed in order to fabricate the true 3D shape. This paper presents our concepts and initial investigation of 3D free form fabrication using the pivoting side trowel. Specifically, the status of research and development of the processand experiments with ceramics materials, and its potential application areas are detailed.

  • PDF