A new approach to the determination of crystallinity of polymers by X-ray diffraction

A new approach is proposed to determine unambiguously the location of four cations within the crystal structure of a naturalAB2O6columbite-type compound and derivatives, when submitted to order–disorder transitions caused by heat treatments. This method is based on the successive use of electron microprobe analysis to determine the cation concentration, Mössbauer spectroscopy to identify the Fe occupation, and a crystal structure determination of the samples combining Rietveld refinements of both neutron and X-ray diffraction. This approach is tested successfully to investigate (Fe, Mn, Nb, Ta) natural minerals as well as oxides obtained by heat treatment of the initialAB2O6columbite-type compound.

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Twenty Years of Progress in X-Ray Diffraction Techniques

Advances in X-ray Analysis ◽

10.1154/s0376030800001373 ◽

1961 ◽

Vol 5 ◽

pp. 1-12

Author(s):

Andre Guinier

Keyword(s):

Electron Microscopy ◽

List Type ◽

X Rays ◽

Type Number ◽

Rational Utilization ◽

X Ray Diffraction ◽

New Approach ◽

X Ray ◽

Near Future

AbstractAlthough no revolutionary advance has been achieved in the last two decades, X-ray diffraction is not to be considered as a quiescent field of physics. Actually many improvements, in theory as well as in experiment, slight by themselves but very numerous, have considerably increased the efficiency of techniques such as the determination of crystal structures, the analysis of crystalline phases, and the applications of X-rays to various problems of the physics of solids. Only the two last points will be dealt with here:1.Crystalline phase analysis. The development of a satisfactory atlas of powder patterns has been too slow, and the data are not yet complete and precise enough to permit a rational utilization of the modern diffractometers. A very interesting new approach is the systematic indexing of the powder patterns which would be possible with computers. In the near future, anyone should be able to analyze a powder at any temperature as an easy routine experiment.2.The study of lattice defects. X-ray techniques are now in competition with electron microscopy, the development of which has been very successful in recent years. Now we have a better understanding of the possibilities of both techniques. X-rays give better results to determine the statistics of an extended disorder even if it is slight (e.g., degrees of order in a solid solution), and the microscope is more powerful for the detection of large but rare defects (e.g., dislocations).

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Perutz and Kendrew: The Heroic Era of Structural Molecular Biology

Architects of Structural Biology ◽

10.1093/oso/9780198854500.003.0005 ◽

2020 ◽

pp. 90-109

Author(s):

John Meurig Thomas

Keyword(s):

Amino Acid ◽

Human Populations ◽

Amino Acid Residues ◽

Experimental Equipment ◽

X Ray Diffraction ◽

Hydrogen Atoms ◽

New Approach ◽

X Ray ◽

Diffraction Patterns

When Perutz and Kendrew embarked on their determination of the structures of haemoglobin and myoglobin, most scientists felt that they would never succeed. These molecules contain approximately thousands of non-hydrogen atoms, whereas those molecules that had yielded to X-ray analysis previously contained fewer than a hundred non-hydrogen atoms. For real progress to be made in solving the structures of the giant proteins, a fundamentally new approach had to be evolved, which inter alia required massive computer power to handle the data contained in hundreds of thousands of X-ray diffraction patterns, and new experimental equipment like ultra-stable X-ray sources were required to record the diffraction data. The first successes were registered by Kendrew, who was able to reveal, in unprecedented detail, the atomically resolved structure of myoglobin with its haem group (containing a central iron atom) and all the details of the amino acid residues that constituted the backbone chain of the protein. Likewise, haemoglobin revealed its secrets. This also led to the discovery of sickle-cell anaemia, the first ever recorded molecular disease. It also shed new light on the pathology of anomalous haemoglobins in human populations.

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A new approach to the problem of kaolinite interference in the determination of chrysotile asbestos by means of x-ray diffraction

Analytica Chimica Acta ◽

10.1016/0003-2670(80)87034-6 ◽

1980 ◽

Vol 117 ◽

pp. 337-342 ◽

Cited By ~ 3

Author(s):

Alessandro Mangia

Keyword(s):

Chrysotile Asbestos ◽

X Ray Diffraction ◽

New Approach ◽

X Ray

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Sem and X-Ray Analysis of Renal and Biliary Calculi

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100091512 ◽

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.

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Carbonaceous materials used in the production of aluminium. Calcined coke. Determination of crystallite size of calcined petroleum coke by X-ray diffraction

10.3403/30106379u ◽

2015 ◽

Keyword(s):

Crystallite Size ◽

Petroleum Coke ◽

Carbonaceous Materials ◽

X Ray Diffraction ◽

X Ray ◽

Calcined Petroleum Coke ◽

Materials Used

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New Coordination Compounds of Fe(III) with Organic Ligands

Revista de Chimie ◽

10.37358/rc.08.12.2055 ◽

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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