A Review of Asphalt Binders Characterized by X-ray Diffraction

Author(s):  
John Shirokoff ◽  
Leonard Lye

Asphalt binder research papers characterized by X-ray diffraction are reviewed. The Xray results reveal the aromaticity and crystallite size parameters of asphaltene in asphalt binders as reported in the research literature. The research data is discussed in terms of asphalt molecular structure on a length scale, methodology, and petroleum oil fields. Box plots and summary statistics created for each parameter are compared and discussed as they relate to eleven data sets from various asphaltene-crude-oil-geological-regions.

2010 ◽  
Vol 297-301 ◽  
pp. 579-583 ◽  
Author(s):  
A. Zare-Shahabadi ◽  
Ali Shokuhfar ◽  
S. Ebrahimi-Nejad

In this paper, sodium bentonite (BT) and organically modified sodium bentonite (OBT) are used to reinforce and modify asphalt binder. The microstructures of the reinforced asphalt binders are investigated using transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD). Two models for the microstructure of the BT and OBT modified asphalts are suggested considering the colloidal structure of the base asphalt binder. The physical properties of the modified asphalt binders were studied.


Author(s):  
Fang Lu ◽  
Bei Zhang ◽  
Yong Liu ◽  
Ying Song ◽  
Gangxing Guo ◽  
...  

Phytases are phosphatases that hydrolyze phytates to less phosphorylatedmyo-inositol derivatives and inorganic phosphate. β-Propeller phytases, which are very diverse phytases with improved thermostability that are active at neutral and alkaline pH and have absolute substrate specificity, are ideal substitutes for other commercial phytases. PhyH-DI, a β-propeller phytase fromBacillussp. HJB17, was found to act synergistically with other single-domain phytases and can increase their efficiency in the hydrolysis of phytate. Crystals of native and selenomethionine-substituted PhyH-DI were obtained using the vapour-diffusion method in a condition consisting of 0.2 Msodium chloride, 0.1 MTris pH 8.5, 25%(w/v) PEG 3350 at 289 K. X-ray diffraction data were collected to 3.00 and 2.70 Å resolution, respectively, at 100 K. Native PhyH-DI crystals belonged to space groupC121, with unit-cell parametersa = 156.84,b = 45.54,c = 97.64 Å, α = 90.00, β = 125.86, γ = 90.00°. The asymmetric unit contained two molecules of PhyH-DI, with a corresponding Matthews coefficient of 2.17 Å3 Da−1and a solvent content of 43.26%. Crystals of selenomethionine-substituted PhyH-DI belonged to space groupC2221, with unit-cell parametersa = 94.71,b= 97.03,c= 69.16 Å, α = β = γ = 90.00°. The asymmetric unit contained one molecule of the protein, with a corresponding Matthews coefficient of 2.44 Å3 Da−1and a solvent content of 49.64%. Initial phases for PhyH-DI were obtained from SeMet SAD data sets. These data will be useful for further studies of the structure–function relationship of PhyH-DI.


2017 ◽  
Vol 73 (9) ◽  
pp. 729-737 ◽  
Author(s):  
Andrea Thorn ◽  
James Parkhurst ◽  
Paul Emsley ◽  
Robert A. Nicholls ◽  
Melanie Vollmar ◽  
...  

In this paper,AUSPEX, a new software tool for experimental X-ray data analysis, is presented. Exploring the behaviour of diffraction intensities and the associated estimated uncertainties facilitates the discovery of underlying problems and can help users to improve their data acquisition and processing in order to obtain better structural models. The program enables users to inspect the distribution of observed intensities (or amplitudes) against resolution as well as the associated estimated uncertainties (sigmas). It is demonstrated howAUSPEXcan be used to visually and automatically detect ice-ring artefacts in integrated X-ray diffraction data. Such artefacts can hamper structure determination, but may be difficult to identify from the raw diffraction images produced by modern pixel detectors. The analysis suggests that a significant portion of the data sets deposited in the PDB contain ice-ring artefacts. Furthermore, it is demonstrated how other problems in experimental X-ray data caused, for example, by scaling and data-conversion procedures can be detected byAUSPEX.


2014 ◽  
Vol 47 (3) ◽  
pp. 1042-1053 ◽  
Author(s):  
Andras Borbely ◽  
Loic Renversade ◽  
Peter Kenesei ◽  
Jonathan Wright

The geometry of high-energy X-ray diffraction setups using an area detector and a rotation axis is analysed. The present paper (part 1) describes the methodology for determining continuously varying spatial distortions and tilt of the area detector based on the reference diffraction rings of a certified powder. Analytical expressions describing the degeneration of Debye rings into ellipses are presented and a robust calibration procedure is introduced. It is emphasized that accurate detector calibration requires the introduction of spatial distortion into the equation describing the tilt. The method is applied to data sets measured at the Advanced Photon Source and at the European Synchrotron Radiation Facility using detectors with different physical characteristics, the GE 41RT flat-panel and the FReLoN4M detector, respectively. The spatial distortion of the detectors is compared with regard to their use in structural and strain tensor analysis, a subject treated in part 2 of the calibration work [Borbély, Renversade & Kenesei (2014).J. Appl. Cryst.Submitted].


2019 ◽  
Vol 75 (9) ◽  
pp. 804-816 ◽  
Author(s):  
Konstantin M. Polyakov ◽  
Sergei Gavryushov ◽  
Tatiana V. Fedorova ◽  
Olga A. Glazunova ◽  
Alexander N. Popov

Laccases are enzymes that catalyze the oxidation of a wide range of organic and inorganic substrates accompanied by the reduction of molecular oxygen to water. Here, a subatomic resolution X-ray crystallographic study of the mechanism of inhibition of the laccase from the basidiomycete fungus Steccherinum murashkinskyi by chloride and fluoride ions is presented. Three series of X-ray diffraction data sets were collected with increasing doses of absorbed X-ray radiation from a native S. murashkinskyi laccase crystal and from crystals of complexes of the laccase with chloride and fluoride ions. The data for the native laccase crystal confirmed the previously deduced enzymatic mechanism of molecular oxygen reduction. The structures of the complexes allowed the localization of chloride and fluoride ions in the channel near the T2 copper ion. These ions replace the oxygen ligand of the T2 copper ion in this channel and can play the role of this ligand in the enzymatic reaction. As follows from analysis of the structures from the increasing dose series, the inhibition of laccases by chloride and fluoride anions can be explained by the fact that the binding of these negatively charged ions at the position of the oxygen ligand of the T2 copper ion impedes the reduction of the T2 copper ion.


2010 ◽  
Vol 651 ◽  
pp. 37-64 ◽  
Author(s):  
Ian C. Madsen ◽  
Ian E. Grey ◽  
Stuart J. Mills

A study of the thermal decomposition sequence of a sample of natural arsenian plumbojarosite has been undertaken using in situ X-ray diffraction. The sample was heated to 900°C using an Anton-Paar heating stage fitted to an INEL CPS120 diffractometer. The data were analysed using a whole-pattern, Rietveld based approach for the extraction of quantitative phase abundances. The instrument configuration used required the development and application of algorithms to correct for aberrations in the (i) peak intensities due to differing path lengths of incident and diffracted beams in the sample and (ii) peak positions due to sample displacement. Details of the structural models used were refined at selected steps in the pattern and then fixed for subsequent analysis. The data sequence consists of some 110 individual data sets which were analysed sequentially with the output of each run forming the input for analysis of the next data set. The results of the analysis show a complex breakdown and recrystallisation sequence including the formation of a major amount of amorphous material after initial breakdown of the plumbojarosite.


1999 ◽  
Vol 55 (5) ◽  
pp. 726-735 ◽  
Author(s):  
N. Ishizawa ◽  
Y. Matsushima ◽  
M. Hayashi ◽  
M. Ueki

The fluorite-related cubic structure of yttria-stabilized zirconia, Zr0.75 8Y0.24 2O1.87 9, has been studied by single-crystal X-ray diffraction using synchrotron radiation and by EXAFS. Two diffraction data sets obtained at X-ray energies of 512 and 10 eV below the Y K edge revealed that in the average structure Zr atoms are displaced from the origin of the space group Fm3¯m along 〈111〉 by 0.19 Å, while Y atoms reside at the origin. Approximately 48% of the O atoms occupy the ideal position in the fluorite-type structure, while 43% of O atoms are displaced from the ideal position along 〈001〉 by 0.31 Å. The remaining 9% of O atoms are presumably sited at interstitial positions. Local structures around Zr and Y are investigated by combining the results of single-crystal X-ray diffraction and EXAFS studies.


2015 ◽  
Vol 48 (6) ◽  
pp. 1943-1955 ◽  
Author(s):  
Antonios Vamvakeros ◽  
Simon D. M. Jacques ◽  
Marco Di Michiel ◽  
Vesna Middelkoop ◽  
Christopher K. Egan ◽  
...  

This paper reports a simple but effective filtering approach to deal with single-crystal artefacts in X-ray diffraction computed tomography (XRD-CT). In XRD-CT, large crystallites can produce spots on top of the powder diffraction rings, which, after azimuthal integration and tomographic reconstruction, lead to line/streak artefacts in the tomograms. In the simple approach presented here, the polar transform is taken of collected two-dimensional diffraction patterns followed by directional median/mean filtering prior to integration. Reconstruction of one-dimensional diffraction projection data sets treated in such a way leads to a very significant improvement in reconstructed image quality for systems that exhibit powder spottiness arising from large crystallites. This approach is not computationally heavy which is an important consideration with big data sets such as is the case with XRD-CT. The method should have application to two-dimensional X-ray diffraction data in general where such spottiness arises.


2014 ◽  
Vol 1611 ◽  
pp. 81-87
Author(s):  
Valeria Strokova ◽  
Mikhail Lebedev ◽  
Irina Potapova ◽  
Konstantin Sobolev

ABSTRACTAsphalt concrete is the most common material for highway and motorway construction. The quality of asphalt is determined, to a large extent, by properties of asphalt binder. Fillers, which are mineral powders from carbonate rocks and aggregates fines, such as limestone and dolomite, are often used in the composition of bitumen mastics affecting the performance of asphalt.This article explores the feasibility of using the fines of aluminosilicate sedimentary rocks as fillers. These materials are composed of clay minerals, which change their properties upon the contact with water. Normally, the use of such fillers is restricted because of poor water resistance and swelling of asphalt concrete. In order to improve the performance of these fillers, the thermal modification at moderate temperatures of 500–600 °C has been proposed. Such treatment provides sufficient structural stability of obtained materials and results in the reduction of water absorption of asphalt, improved water resistance (up to 2.5 times) and also, in reduced swelling (up to 9 times).It has been demonstrated that improvement in the filler performance can be achieved by a heat treatment. Such treatment induces changes in the mineral composition and converts the structure of clay minerals into the frame structure of zeolite, as confirmed by X-ray diffraction and infrared spectroscopy. Due to thermal treatment, there is a change in the acid-base properties of the surface of the filler, which is reflected in the profiles of the main adsorption centers. As a result, due to chemisorption, the modified aluminosilicate fillers are able to interact with bitumen. The application of new filler materials in asphalt concrete enables to enhance the performance.


2012 ◽  
Vol 46 (1) ◽  
pp. 108-119 ◽  
Author(s):  
Simon W. M. Tanley ◽  
Antoine M. M. Schreurs ◽  
John R. Helliwell ◽  
Loes M. J. Kroon-Batenburg

The International Union of Crystallography has for many years been advocating archiving of raw data to accompany structural papers. Recently, it initiated the formation of the Diffraction Data Deposition Working Group with the aim of developing standards for the representation of these data. A means of studying this issue is to submit exemplar publications with associated raw data and metadata. A recent study on the effects of dimethyl sulfoxide on the binding of cisplatin and carboplatin to histidine in 11 different lysozyme crystals from two diffractometers led to an investigation of the possible effects of the equipment and X-ray diffraction data processing software on the calculated occupancies andBfactors of the bound Pt compounds. 35.3 Gb of data were transferred from Manchester to Utrecht to be processed withEVAL. A systematic comparison shows that the largest differences in the occupancies andBfactors of the bound Pt compounds are due to the software, but the equipment also has a noticeable effect. A detailed description of and discussion on the availability of metadata is given. By making these raw diffraction data sets availableviaa local depository, it is possible for the diffraction community to make their own evaluation as they may wish.


Sign in / Sign up

Export Citation Format

Share Document