X-ray Structural Modeling and Gas Adsorption Analysis of Cagelike SBA-16 Silica Mesophases Prepared in a F127/Butanol/H2O System

This article deals with the study of direct current (DC), ultrasonic, and of electrolyte of the influence on the change of titanium dioxide sorption properties. The TiO2 prepared by the TiCl4 hydrolysis method. Attention is drawn to charging exchange processes the surface of titanium dioxide particles after they pass through a layer of counter ions in an aqueous medium under the influence of a DC. The stages of the end product’s formation using methods of the X-ray diffraction, the differential thermal and the infrared spectrometric and the gas adsorption analysis were proposed. Dependence of redistribution sorption active centers at the surface of TiO2 was proved.

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Nanoporosity in Ceramics from Polymeric Precursors

MRS Proceedings ◽

10.1557/proc-346-843 ◽

1994 ◽

Vol 346 ◽

Cited By ~ 4

Author(s):

A.W. Reid ◽

B. Rand ◽

R.J.P. Emsley

Keyword(s):

Heat Treatment ◽

Pore Volume ◽

Heat Treatment Temperature ◽

Gas Adsorption ◽

Treatment Temperature ◽

X Ray Diffraction ◽

Carbon Phase ◽

Volume Increase ◽

X Ray ◽

Adsorption Analysis

ABSTRACTIt is shown that ceramics derived from polycarbosilane polymers may develop an open nanoporous network after heat treatment to a temperatures between 1300 and 1550°C in argon. The resulting SiC-based ceramics were characterised by N2 gas adsorption analysis and X-ray diffraction. The apparent surface area, and pore volume increase with increasing heat treatment temperature, reaching values of 170 m2g-1 and 0.12 cm3-1 respectively. The pore network develops as the SiC crystals grow and as carbon is ejected from the structure. It is thought that the porosity may reside within the carbon phase, but this remains to be confirmed.

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Syntheses, X-ray structures, gas adsorption and luminescent properties of three coordination polymers of Zn(ii) dicarboxylates mixed with a linear, neutral, and rigid N,N′-donor ligand

CrystEngComm ◽

10.1039/c3ce42441c ◽

2014 ◽

Vol 16 (22) ◽

pp. 4783-4795 ◽

Cited By ~ 33

Author(s):

Biswajit Bhattacharya ◽

Debraj Saha ◽

Dilip Kumar Maity ◽

Rajdip Dey ◽

Debajyoti Ghoshal

Keyword(s):

Coordination Polymers ◽

Gas Adsorption ◽

Luminescent Properties ◽

Donor Ligand ◽

X Ray

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Hydrothermal Treatment of Coprecipitated YSZ Powders

Materials Science Forum ◽

10.4028/www.scientific.net/msf.660-661.983 ◽

2010 ◽

Vol 660-661 ◽

pp. 983-988 ◽

Cited By ~ 2

Author(s):

Alexander Rodrigo Arakaki ◽

Walter Kenji Yoshito ◽

Valter Ussui ◽

Dolores Ribeiro Ricci Lazar

Keyword(s):

Surface Area ◽

Hydrothermal Treatment ◽

Gas Adsorption ◽

X Ray Diffraction ◽

Electronic Microscopy ◽

Immersion Method ◽

Cubic Symmetry ◽

X Ray ◽

Granulometric Analysis ◽

Symmetry Surface

Zirconia stabilized with 8.5 mol% yttria (YSZ) were synthesized by coprecipitation and resulting gels were hydrothermallly treated at 200°C and 220 PSI for 4, 8 and 16 hours. Products were oven dried at 70°C for 24 hours, isostatically pressed as pellets and sintered at 1500 °C for 1 hour. Powders were characterized for surface area with N2 gas adsorption, X-ray diffraction, laser diffraction granulometric analysis and scanning and transmission electronic microscopy. Density of ceramics was measured by an immersion method based on the Archimedes principle. Results showed that powders dried at 70°C are amorphous and after treatment has tetragonal/cubic symmetry. Surface area of powders presented a significant reduction after hydrothermal treatment. Ceramics prepared from hydrothermally treated powders have higher green density but sintered pellets are less dense when compared to that made with powders calcined at 800°C for 1 hour due to the agglomerate state of powders. Solvothermal treatment is a promising procedure to enhance density.

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A New X-Ray Scattering Method for Determining Pore-Size Distribution in Low-k Thin Films

MRS Proceedings ◽

10.1557/proc-714-l12.10.1 ◽

2001 ◽

Vol 714 ◽

Cited By ~ 1

Author(s):

Kazuhiko Omote ◽

Shigeru Kawamura

Keyword(s):

Thin Films ◽

Pore Size Distribution ◽

Pore Size ◽

Gas Adsorption ◽

Size Distributions ◽

X Ray ◽

X Ray Scattering ◽

Pore Size Distributions ◽

Scattering Technique ◽

Ray Scattering

ABSTRACTWe have successively developed a new x-ray scattering technique for a non-destructive determination of pore-size distributions in porous low-κ thin films formed on thick substrates. The pore size distribution in a film is derived from x-ray diffuse scattering data, which are measured using offset θ/2θ scans to avoid strong specular reflections from the film surface and its substrate. Γ-distribution mode for the pores in the film is used in the calculation. The average diameter and the dispersion parameter of the Γ-distribution function are varied and refined by computer so that the calculated scattering pattern best matches to the experimental pattern. The technique has been used to analyze porous methyl silsesquioxane (MSQ) films. The pore size distributions determined by the x-ray scattering technique agree with that of the commonly used gas adsorption technique. The x-ray technique has been also used successfully determine small pores less than one nanometer in diameter, which is well below the lowest limit of the gas adsorption technique.

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Structural Modeling of Glutathiones Containing Selenium and Tellurium

International Journal of Chemistry ◽

10.5539/ijc.v8n1p102 ◽

2016 ◽

Vol 8 (1) ◽

pp. 102

Author(s):

Valter A. Nascimento ◽

Petr Melnikov ◽

André V. D. Lanoa ◽

Anderson F. Silva ◽

Lourdes Z. Z. Consolo

Keyword(s):

Molecular Mechanics ◽

Structural Characteristics ◽

Structural Modeling ◽

Structural Description ◽

Ionic Radii ◽

X Ray ◽

Bond Angles ◽

Bond Lengths ◽

Available Information ◽

Related Compounds

<p>The comparative structural modeling of reduced and oxidized glutathiones, as well as their derivatives containing selenium and tellurium in chalcogen sites (Ch = Se, Te) has provided detailed information about the bond lengths and bond angles, filling the gap in the structural characteristics of these tri-peptides. The investigation using the molecular mechanics technique with good approximation confirmed the available information on X-ray refinements for the related compounds. It was shown that Ch-H and Ch-C bond lengths grow in parallel with the increasing chalcogen ionic radii. Although the distances C-C, C-O, and C-N are very similar, the geometry of GChChG glutathiones is rich in conformers owing to the possibility of rotation about the bridge Ch-Ch. It is confirmed that the distances Ch-Ch are essentially independent of substituents in most of chalcogen compounds from elemental chalcogens to oxydized glutathiones. The standard program Hyperchem 7.5 has proved to be an appropriate tool for the structural description of less-common bioactive compositions when direct X-ray data are missing.</p>

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The Adsorption and Chemistry of Tripropyl phosphate (TPP) into Microporous and Mesoporous NaX Zeolites

MRS Proceedings ◽

10.1557/opl.2011.431 ◽

2011 ◽

Vol 1304 ◽

Author(s):

Qingguo Meng ◽

David C. Doetschman ◽

Apostolos K. Rizos ◽

Min-Hong Lee ◽

Jürgen T. Schulte ◽

...

Keyword(s):

Solid State ◽

Structural Properties ◽

Nmr Spectra ◽

Nitrogen Adsorption ◽

X Ray Diffraction ◽

X Ray ◽

Nax Zeolite ◽

Stoichiometric Amount ◽

Polydiallyldimethylammonium Chloride ◽

Adsorption Analysis

ABSTRACTAdsorption and chemistry of tripropylphosphate (TPP) in mesoporous NaX zeolite, which was templated by cationic templated polymer (polydiallyldimethylammonium chloride, PDADMAC) with two different length chains, was investigated. The structural properties of the zeolites were characterized by X-ray diffraction (XRD) and nitrogen adsorption analysis. The chemical activities of different zeolites toward the decomposition of TPP were determined with solid state 31P NMR spectra. After exposure of zeolites to TPP was sufficient and equilibrium was reached, a stoichiometric amount of water was also adsorbed and hydrolysis was observed. The TPP decomposition yields in different NaX zeolites were compared.

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Automated and optimally FRET-assisted structural modeling

Nature Communications ◽

10.1038/s41467-020-19023-1 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 2

Author(s):

Mykola Dimura ◽

Thomas-Otavio Peulen ◽

Hugo Sanabria ◽

Dmitro Rodnin ◽

Katherina Hemmen ◽

...

Keyword(s):

Open Source Software ◽

Structural Information ◽

Structural Modeling ◽

Automated Design ◽

Design Tool ◽

Coarse Grained ◽

Complex Dynamic ◽

X Ray ◽

Link Type ◽

Dynamics Simulations

Abstract FRET experiments can provide state-specific structural information of complex dynamic biomolecular assemblies. However, to overcome the sparsity of FRET experiments, they need to be combined with computer simulations. We introduce a program suite with (i) an automated design tool for FRET experiments, which determines how many and which FRET pairs should be used to minimize the uncertainty and maximize the accuracy of an integrative structure, (ii) an efficient approach for FRET-assisted coarse-grained structural modeling, and all-atom molecular dynamics simulations-based refinement, and (iii) a quantitative quality estimate for judging the accuracy of FRET-derived structures as opposed to precision. We benchmark our tools against simulated and experimental data of proteins with multiple conformational states and demonstrate an accuracy of ~3 Å RMSDCα against X-ray structures for sets of 15 to 23 FRET pairs. Free and open-source software for the introduced workflow is available at https://github.com/Fluorescence-Tools. A web server for FRET-assisted structural modeling of proteins is available at http://nmsim.de.

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Preparation of Zirconia Nanofibers by Electrospinning and Calcination with Zirconium Acetylacetonate as Precursor

Polymers ◽

10.3390/polym11061067 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1067 ◽

Cited By ~ 5

Author(s):

Vyacheslav V. Rodaev ◽

Svetlana S. Razlivalova ◽

Andrey O. Zhigachev ◽

Vladimir M. Vasyukov ◽

Yuri I. Golovin

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Heterogeneous Catalysts ◽

Tetragonal Zirconia ◽

Nitrogen Adsorption ◽

Average Diameter ◽

High Specific Surface Area ◽

X Ray ◽

Adsorption Analysis

For the first time, zirconia nanofibers with an average diameter of about 75 nm have been fabricated by calcination of electrospun zirconium acetylacetonate/polyacrylonitrile fibers in the range of 500–1100 °C. Composite and ceramic filaments have been characterized by scanning electron microscopy, thermogravimetric analysis, nitrogen adsorption analysis, energy-dispersive X-ray spectroscopy, and X-ray diffractometry. The stages of the transition of zirconium acetylacetonate to zirconia have been revealed. It has been found out that a rise in calcination temperature from 500 to 1100 °C induces transformation of mesoporous tetragonal zirconia nanofibers with a high specific surface area (102.3 m2/g) to non-porous monoclinic zirconia nanofibers of almost the same diameter with a low value of specific surface area (8.3 m2/g). The tetragonal zirconia nanofibers with high specific surface area prepared at 500 °C can be considered, for instance, as promising supports for heterogeneous catalysts, enhancing their activity.

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Gas adsorption and X-ray studies of internal mated splits in Ge and Si

Surface Science ◽

10.1016/0039-6028(69)90241-6 ◽

1969 ◽

Vol 13 (1) ◽

pp. 119-129 ◽

Cited By ~ 12

Author(s):

D. Haneman ◽

J.T.P. Grant ◽

R.U. Khokhar

Keyword(s):

Gas Adsorption ◽

X Ray

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