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crystal-diffusivity
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The Synthesis and Characterization of Nano Zeolitic Molecular Sieve for Separation of 133Xe from 85Kr
, Ph.D. Dissertation Sharif University of Technology ; Kazemeini, Mohammad (Supervisor) ; Ahmadi, Javad (Supervisor)
Abstract
In this study the feasibility of xenon separation from xenon-krypton mixture was investigated by utilizing of the chromatographic column filled with nano and micron sized NaY zeolite. For this purpose the nano NaY with the yield of 100% related to Al2O3 and the average size of 98.6 nm was synthesized through the clear solution method with the mid-adding of NaOH. Furthermore, a novel method for granulation of nano zeolite was developed by utilizing sodium alginate as an external template. In this method the production of uniform spherical granules with the different sizes in the range of several milimiteres to 100 µm was easily performed. Moreover, the results showed that the adding of...
Adsorption and diffusion of Xenon in a granulated nano-NaY zeolite
, Article Adsorption ; Volume 18, Issue 2 , 2012 , Pages 75-86 ; 09295607 (ISSN) ; Kazemeini, M ; Ahmadi, S. J ; Allahyar, S. A ; Sharif University of Technology
Springer
2012
Abstract
Henry's law constant and crystal diffusivity of xenon in the granulated nano-NaY zeolite were measured by the pulse gas chromatography method. For this purpose the moments of response peaks of xenon were analyzed. The effect of extra column parts of the utilized chromatographic system was also considered by analyzing the moments of the response peak which was obtained by pulse injection of inert gas of helium into the carrier gas of nitrogen. In addition, the measurement of average velocity of the carrier gas regarding the pressure drop in the extra column parts of the system attributed to precise results. By carrying out the experiments at various temperatures in the range of 30-110 °C the...
Effect of bonding temperature on microstructure development during TLP bonding of a nickel base superalloy
, Article Journal of Alloys and Compounds ; Volume 469, Issue 1-2 , 2009 , Pages 270-275 ; 09258388 (ISSN) ; Ekrami, A ; Kokabi, A. H ; Sharif University of Technology
2009
Abstract
The effect of bonding temperature on microstructure of a transient liquid phase (TLP)-bonded GTD-111 nickel base superalloy, using a Ni-Si-B interlayer, was investigated. At low bonding temperatures microstructure of the joint centerline is controlled by B diffusion. However, at high bonding temperature effect of base metal alloying elements on the joint microstructure development was more pronounced. Effects of bonding temperature on the formation of secondary precipitates in diffusion-affected zone and isothermal solidification time were also analyzed. It was found that above a critical temperature, formation of borides in diffusion-affected zone is suppressed and the time required for...
Complete steric exclusion of ions and proton transport through confined monolayer water
, Article Science ; Volume 363, Issue 6423 , 2019 , Pages 145-148 ; 00368075 (ISSN) ; Hu, S ; Esfandiar, A ; Lozada Hidalgo, M ; Wang, F. C ; Yang, Q ; Tyurnina, A. V ; Keerthi, A ; Radha, B ; Geim, A. K ; Sharif University of Technology
American Association for the Advancement of Science
2019
Abstract
It has long been an aspirational goal to create artificial structures that allow fast permeation of water but reject even the smallest hydrated ions, replicating the feat achieved by nature in protein channels (e.g., aquaporins). Despite recent progress in creating nanoscale pores and capillaries, these structures still remain distinctly larger than protein channels. We report capillaries made by effectively extracting one atomic plane from bulk crystals, which leaves a two-dimensional slit of a few angstroms in height. Water moves through these capillaries with little resistance, whereas no permeation could be detected even for such small ions as Na + and Cl − . Only protons (H + ) can...