The petrology of the Mount Padbury mesosiderite and its achondrite enclaves

1966 ◽  
Vol 36 (276) ◽  
pp. 1029-1060 ◽  
Author(s):  
G. J. H. McCall
Keyword(s):  
Microscopic Analysis ◽  
Host Material ◽  
Refractive Indices ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
X Ray ◽  
Wide Range ◽  
Varied Range ◽  
Optical Determination

SummaryThe petrography of the Mount Padbury meteorite, previously briefly recorded, is described in some detail. Both the metalliferous host material of the mesosiderite and the varied range of silicate-rich, virtually metal-free enclaves (including both familiar achondrite material and unfamiliar achondrite material) are described. Eucrite, brecciated eucrite, and a peculiar ‘shocked’ form of eucrite (resembling some terrestrial flaser-gabbros) are the calcium-rich achondrite types represented; hypersthene achondrite (including typical diogenite material and unfamiliar material) and olivine achondrite (granular aggregates of olivine not entirely similar to the unique chassignite and single crystals up to 4 in. in length) are the calcium-poor achondrite types represented. The eucrite displays more or less uniform mineralogy, but the mineral constituents are present in varying proportions, and there is a wide range of textural variations recognized. The silicate grain fragments enclosed in the metallic reticulation to form the mesosiderite host material are, significantly, entirely of minerals seen within the achondrite enclaves—plagioclase, hypersthene, pigeonite, olivine, and tridymite.These results include microscopic analysis of thin sections and polished sections, X-ray diffraction studies, optical determination of refractive indices using mineral grain mounts, and chemical analyses.The wider implications of this new and unique meteorite find are briefly considered.

LauePt, a graphical-user-interface program for simulating and analyzing white-beam X-ray diffraction Laue patterns

2010 ◽  
Vol 43 (4) ◽  
pp. 926-928 ◽  
Author(s):  
X. R. Huang
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Crystallography ◽  
White Beam ◽  
Diffraction Geometry ◽  
Wide Range ◽  
User Friendly ◽  
Beam Diffraction ◽  
Laue Method

LauePtis a robust and extremely easy-to-use Windows application for accurately simulating, indexing and analyzing white-beam X-ray diffraction Laue patterns of any crystals under arbitrary diffraction geometry. This program has a user-friendly graphic interface and can be conveniently used by nonspecialists with little X-ray diffraction or crystallography knowledge. Its wide range of applications include (1) determination of single-crystal orientation with the Laue method, (2) white-beam topography, (3) white-beam microdiffraction, (4) X-ray studies of twinning, domains and heterostructures, (5) verification or determination of crystal structures from white-beam diffraction, and (6) teaching of X-ray crystallography.

Quantitative X-Ray Structure Determination of Superlattices and Interfaces

1991 ◽  
Vol 229 ◽  
Author(s):  
Ivan K. Schuller ◽  
Eric E. Fullerton ◽  
H. Vanderstraeten ◽  
Y. Bruynseraede
Keyword(s):  
General Procedure ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
Diffraction Profile ◽  
X Ray ◽  
Superlattice Structure ◽  
Wide Range ◽  
Fitting Algorithm ◽  
Superlattice Structures

AbstractWe present a general procedure for quantitative structural refinement of superlattice structures. To analyze a wide range of superlattices, we have derived a general kinematical diffraction formula that includes random, continuous and discrete fluctuations from the average structure. By implementing a non-linear fitting algorithm to fit the entire x-ray diffraction profile, refined parameters that describe the average superlattice structure, and deviations from this average are obtained. The structural refinement procedure is applied to a crystalline/crystalline Mo/Ni superlattices and crystalline/amorphous Pb/Ge superlattices. Roughness introduced artificially during growth in Mo/Ni superlattices is shown to be accurately reproduced by the refinement.

scholarly journals A simple pressure-assisted method for MicroED specimen preparation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jingjing Zhao ◽  
Hongyi Xu ◽  
Hugo Lebrette ◽  
Marta Carroni ◽  
Helena Taberman ◽  
...  
Keyword(s):  
High Viscosity ◽  
Specimen Preparation ◽  
Universal Method ◽  
X Ray Diffraction ◽  
Simple Method ◽  
X Ray ◽  
Wide Range ◽  
Major Bottleneck ◽  
Crystal Electron

AbstractMicro-crystal electron diffraction (MicroED) has shown great potential for structure determination of macromolecular crystals too small for X-ray diffraction. However, specimen preparation remains a major bottleneck. Here, we report a simple method for preparing MicroED specimens, named Preassis, in which excess liquid is removed through an EM grid with the assistance of pressure. We show the ice thicknesses can be controlled by tuning the pressure in combination with EM grids with appropriate carbon hole sizes. Importantly, Preassis can handle a wide range of protein crystals grown in various buffer conditions including those with high viscosity, as well as samples with low crystal concentrations. Preassis is a simple and universal method for MicroED specimen preparation, and will significantly broaden the applications of MicroED.

Micro X-ray diffraction (µXRD): a versatile technique for characterization of Earth and planetary materials

2007 ◽  
Vol 44 (9) ◽  
pp. 1333-1346 ◽  
Author(s):  
Roberta L Flemming
Keyword(s):  
Ccd Camera ◽  
Optical Microscope ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
X Ray ◽  
Area Detector ◽  
Wide Range ◽  
Individual Grains ◽  
Planetary Materials

Recent developments in laboratory-based micro X-ray diffraction (µXRD) have extended X-ray examination of geomaterials to the microscopic level (50–500 µm), greatly expanding the applicability of XRD to mineralogy, petrology, materials, environmental, and planetary sciences. Laboratory-based µXRD has been accomplished using a Bruker™ D8 Discover diffractometer, having a sealed-tube Cu source, theta–theta geometry, Gobel mirror parallel optics with 50–500 µm collimation, and general area detector diffraction system (GADDS). A wide range of samples, including polished thin sections, electron probe microanalysis (EPMA) mounts, rock slabs, whole rocks, and powders have been examined with µXRD using a remote-controlled XYZ sample stage, with imaging by optical microscope monitor and charge-coupled device (CCD) camera. Individual grains in heterogeneous samples have been examined in situ, with little or no sample preparation. The two-dimensional GADDS preserves textural and crystallinity information (e.g., bioapatite) and easily discriminates between multiple phases of utility for synthetic or natural samples (e.g., mine tailings). In situ µXRD of minerals preserves spatial relationships, enabling study of orientational phenomena, such as strain-related mosaicity (giving “streaked” diffraction lines). Examples include strained quartz (La Malbaie quartzite, Quebec) and shocked clinopyroxenes (Shergottite NWA 3171). Mineral mapping has been demonstrated by reproducing exsolution textures of kamacite from taenite (Widmanstätten pattern) in the Toluca iron meteorite. Diffraction data obtained from single crystals (by the omega scan method) have enabled grain-by-grain correlation between unit cell (µXRD) and chemical composition (EPMA), as demonstrated by kimberlite indicator garnets. The examples shown herein demonstrate the breadth of information that can be obtained by µXRD of Earth and planetary materials.

scholarly journals A simple pressure-assisted method for MicroED specimen preparation

2021 ◽  
Author(s):  
Jingjing Zhao ◽  
Hongyi Xu ◽  
Hugo Lebrette ◽  
Marta Carroni ◽  
Helena Taberman ◽  
...  
Keyword(s):  
High Viscosity ◽  
Specimen Preparation ◽  
Universal Method ◽  
X Ray Diffraction ◽  
Simple Method ◽  
X Ray ◽  
Wide Range ◽  
Major Bottleneck ◽  
Crystal Electron

Abstract Micro-crystal electron diffraction (MicroED) has shown great potential for structure determination of macromolecular crystals too small for X-ray diffraction. However, specimen preparation remains a major bottleneck. Here, we report a simple method for preparing MicroED specimens, named Preassis, in which excess liquid is removed through an EM grid with the assistance of pressure. We show the ice thicknesses can be controlled by tuning the pressure in combination with EM grids with appropriate hole sizes. Importantly, Preassis can handle a wide range of protein crystals grown in various buffer conditions including those with high viscosity, as well as samples with low crystal contents. Preassis is a simple and universal method for MicroED specimen preparation, and will significantly broaden the applications of MicroED.

scholarly journals Crystallization and X-ray structure determination of a thermoalkalophilic lipase fromGeobacillusSBS-4S

2013 ◽  
Vol 69 (4) ◽  
pp. 355-357
Author(s):  
Muhammad Tayyab ◽  
Naeem Rashid ◽  
Clement Angkawidjaja ◽  
Shigenori Kanaya ◽  
Muhammad Akhtar
Keyword(s):  
Diffusion Method ◽  
Molecular Replacement ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Replacement Method ◽  
Wide Range ◽  
Molecular Replacement Method

A thermoalkalophilic lipase (LIPSBS) from the newly isolatedGeobacillusstrain SBS-4S which hydrolyzes a wide range of fatty acids has been characterized. In the present study, the crystallization of purified LIPSBSusing the sitting-drop vapour-diffusion method and its X-ray diffraction studies are described. The crystals belonged to the orthorhombic space groupP212121, with unit-cell parametersa= 55.13,b= 71.75,c= 126.26 Å. The structure was determined at 1.6 Å resolution by the molecular-replacement method using the lipase fromG. stearothermophilusL1 as a model.

Chemical modification of the bacterial wall to determine sites of metal deposition

1978 ◽  
Vol 36 (2) ◽  
pp. 350-351
Author(s):  
T. J. Beveridge
Keyword(s):  
Electron Scattering ◽  
Metal Salt ◽  
Metal Deposition ◽  
Suitable Model ◽  
X Ray Diffraction ◽  
Subtilis Cell ◽  
Thin Sections ◽  
X Ray ◽  
Section Data ◽  
Metal Impregnation

The Bacillus subtilis cell wall provides a protective sacculus about the vital constituents of the bacterium and consists of a collection of anionic hetero- and homopolymers which are mainly polysaccharidic. We recently demonstrated that unfixed walls were able to trap and retain substantial amounts of metal when suspended in aqueous metal salt solutions. These walls were briefly mixed with low concentration metal solutions (5mM for 10 min at 22°C), were well washed with deionized distilled water, and the quantity of metal uptake (atomic absorption and X-ray fluorescence), the type of staining response (electron scattering profile of thin-sections), and the crystallinity of the deposition product (X-ray diffraction of embedded specimens) determined.Since most biological material possesses little electron scattering ability electron microscopists have been forced to depend on heavy metal impregnation of the specimen before obtaining thin-section data. Our experience with these walls suggested that they may provide a suitable model system with which to study the sites of reaction for this metal deposition.

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

New Coordination Compounds of Fe(III) with Organic Ligands

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihaela Flondor ◽  
Ioan Rosca ◽  
Doina Sibiescu ◽  
Mihaela-Aurelia Vizitiu ◽  
Daniel-Mircea Sutiman ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Complex Compounds ◽  
Organic Ligands ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Chemical Analysis ◽  
Structural Formulae ◽  
Paramagnetic Properties

In this paper the synthesis and the study of some complex compounds of Fe(III) with ligands derived from: 2-(4-chloro-phenylsulfanyl)-1-(2-hydroxy-3,5-diiodo-phenyl)-ethanone (HL1), 1-(3,5-dibromo-2-hydroxy-phenyl)-2-phenylsulfanyl-ethanone(HL2), and 2-(4-chloro-phenylsulfanyl)-1-(3,5-dibromo-2-hydroxy-phenyl)-ethanone (HL3) is presented. The characterization of these complexes is based on method as: the elemental chemical analysis, IR and ESR spectroscopy, M�ssbauer, the thermogravimetric analysis and X-ray diffraction. Study of the IR and chemical analysis has evidenced that the precipitates form are a complexes and the combination ratio of M:L is 1:2. The central atoms of Fe(III) presented paramagnetic properties and a octaedric hybridization. Starting from this precipitation reactions, a method for the gravimetric determination of Fe(III) with this organic ligands has been possible. Based on the experimental data on literature indications, the structural formulae of the complex compounds are assigned.

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