Determination of porous structure parameters and selectivity of acetylcellulose membranes with respect to dextrans

1986 ◽  
Vol 20 (8) ◽  
pp. 564-567
Author(s):  
M. M. Selin
Keyword(s):  
Porous Structure ◽  
Structure Parameters

scholarly journals Determination of porous structure parameters of coal particles to describe thermal conversion processes

2019 ◽  
Vol 109 ◽  
pp. 00101
Author(s):  
Oleksandr Topal ◽  
Iryna Holenko ◽  
Inna Diakun
Keyword(s):  
Porous Structure ◽  
Gas Adsorption ◽  
Thermal Conversion ◽  
Structure Parameters ◽  
Adsorption Method ◽  
Coal Particles ◽  
Different Temperatures ◽  
Char Reactivity ◽  
Determination Of Parameters

The results of determination of parameters of porous structure of coal and char particles are presented. They were determined using gas adsorption method and thermal decomposition of particles in air oxygen. The porous structure parameters allow predicting char reactivity change at different temperatures as well as during conversion in accordance with Random Pore Model (RPM-model).

scholarly journals METHOD FOR DETERMINATION OF POROUS STRUCTURE PARAMETERS FOR FOSSIL COALS OF METAMORPHISM SERIES

2019 ◽  
Vol 134 (4) ◽  
pp. 55-63
Author(s):  
Yuliya N. Dudnikova ◽  
◽  
Sergey A. Sozinov ◽  
Natalia I. Fedorova ◽  
Zinfer R. Ismagilov ◽  
...  
Keyword(s):  
Porous Structure ◽  
Structure Parameters ◽  
Fossil Coals

scholarly journals Analysis of the Effect of Conditions of Preparation of Nitrogen-Doped Activated Carbons Derived from Lotus Leaves by Activation with Sodium Amide on the Formation of Their Porous Structure

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1540
Author(s):  
Mirosław Kwiatkowski ◽  
Xin Hu
Keyword(s):  
Porous Structure ◽  
Activated Carbons ◽  
Structure Parameters ◽  
Mass Ratio ◽  
Nitrogen Doped ◽  
Adsorption Analysis ◽  
Lotus Leaves ◽  
The Impact ◽  
Sodium Amide ◽  
Numerical Clustering

This paper presents results of the analysis of the impact of activation temperature and mass ratio of activator to carbonized precursor R on the porous structure of nitrogen-doped activated carbons derived from lotus leaves by carbonization and chemical activation with sodium amide NaNH2. The analyses were carried out via the new numerical clustering-based adsorption analysis (LBET) method applied to nitrogen adsorption isotherms at −195.8 °C. On the basis of the results obtained it was shown that the amount of activator, as compared to activation temperatures, has a significantly greater influence on the formation of the porous structure of activated carbons. As shown in the study, the optimum values of the porous structure parameters are obtained for a mass ratio of R = 2. At a mass ratio of R = 3, a significant decrease in the values of the porous structure parameters was observed, indicating uncontrolled wall firing between adjacent micropores. The conducted analyses confirmed the validity of the new numerical clustering-based adsorption analysis (LBET) method, as it turned out that nitrogen-doped activated carbons prepared from lotus leaves are characterized by a high share of micropores and a significant degree of surface heterogeneity in most of the samples studied, which may, to some extent, undermine the reliability of the results obtained using classical methods of structure analysis that assume only a homogeneous pore structure.

VESTA 3for three-dimensional visualization of crystal, volumetric and morphology data

2011 ◽  
Vol 44 (6) ◽  
pp. 1272-1276 ◽  
Author(s):  
Koichi Momma ◽  
Fujio Izumi
Keyword(s):  
Search Algorithm ◽  
Voronoi Tessellation ◽  
Three Dimensional ◽  
Structure Parameters ◽  
Volumetric Data ◽  
Complex Molecules ◽  
Visualization System ◽  
Performance Improvements ◽  
Significant Performance

VESTAis a three-dimensional visualization system for crystallographic studies and electronic state calculations. It has been upgraded to the latest version,VESTA 3, implementing new features including drawing the external morphology of crystals; superimposing multiple structural models, volumetric data and crystal faces; calculation of electron and nuclear densities from structure parameters; calculation of Patterson functions from structure parameters or volumetric data; integration of electron and nuclear densities by Voronoi tessellation; visualization of isosurfaces with multiple levels; determination of the best plane for selected atoms; an extended bond-search algorithm to enable more sophisticated searches in complex molecules and cage-like structures; undo and redo in graphical user interface operations; and significant performance improvements in rendering isosurfaces and calculating slices.

Laboratory Stopped-Flow XAFS Apparatus. Structure Determination of the Short-Lived Peroxochromium Intermediate Formed during Reduction Process of Chromate(VI) Ion by Hydrogen Peroxide

1997 ◽  
Vol 52 (6) ◽  
pp. 711-718 ◽  
Author(s):  
Y. Inada ◽  
S. Funahashi
Keyword(s):  
Hydrogen Peroxide ◽  
Fine Structure ◽  
Water Molecule ◽  
Reduction Process ◽  
Stopped Flow ◽  
Structure Parameters ◽  
X Ray ◽  
Reaction Intermediate ◽  
X Ray Absorption

In order to determine the structure parameters of the reaction intermediate formed during the reduction process of chromate(VI) ion by hydrogen peroxide, a laboratory stopped-flow X-ray absorption fine structure (XAFS ) apparatus, which was constructed by a rotating anode X-ray generator, an energy scanning spectrometer, a stopped-flow assembly, and X-ray detectors, was newly developed. Using the apparatus, the Cr K -edge XAFS spectrum of the reaction intermediate was measured. One oxo group, two peroxo groups, and one water molecule are coordinated to the Cr(VI) center in the intermediate, CrO(O2)2(H2O ) , with Cr - O bond lengths of 157, 168, and 193 pm, respectively. The geometry around the Cr(VI) center is probably 6-coordinate pentagonal pyramidal.

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