Interactions and spatial arrangement of spin-labeled NAD+ bound to glyceraldehyde-3-phosphate dehydrogenase. Comparison of EPR and X-ray modeling data.

The synthesis of a new CF3-containing stereogenic atropisomeric pair of ortho-disubstituted biphenyl scaffold is presented. The atropisomers are surprisingly conformationally stable for isolation. X-ray structures show that their stability comes from an intramolecular hydrogen bond formation from their two hydroxyl groups and renders the spatial arrangement of their peripheral CF3 and CH3 groups very different. The synthesized stereogenic scaffold proved to be effective in catalyzing the asymmetric N-nitroso aldol reaction of enamine and nitrosobenzene. Compared to similar scaffolds without CF3 groups, one of our atropisomer exhibits an increase in enantioselectivity in this reaction.

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Non-Destructive and Micro-Invasive Techniques for Characterizing the Ancient Roman Mosaic Fragments

Applied Sciences ◽

10.3390/app10113781 ◽

2020 ◽

Vol 10 (11) ◽

pp. 3781 ◽

Cited By ~ 2

Author(s):

Rodica Mariana Ion ◽

Bulat A. Bakirov ◽

Sergey E. Kichanov ◽

Denis P. Kozlenko ◽

Alexander V. Belushkin ◽

...

Keyword(s):

Neutron Diffraction ◽

Spatial Arrangement ◽

Diffraction Field ◽

Neutron Tomography ◽

Three Dimension ◽

Iron Hydroxides ◽

X Ray ◽

Polluted Atmosphere ◽

Invasive Techniques ◽

Non Destructive

The color characteristics, vibration spectra, phase and mineral composition, internal structural organization of several fragments of the ancient Roman mosaics from the Roman Mosaic Museum, Constanta, Romania were studied by non-destructive (Chromatic analysis, Neutron Diffraction, Neutron Tomography) and micro-invasive techniques (Optical Microscopy, X-ray Diffraction, Field Emission Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy, Raman Spectroscopy, Wavelength Dispersion X-ray Fluorescence). These investigations were performed in order to characterize the original Roman mosaic fragments. The major and minor phase components of the studied mosaic fragments were determined, the crystal structure of the main phases was analyzed, and their three-dimension spatial arrangement was reconstructed. The similar composition of the major phases of all mosaic fragments can indicate a generic recipe for making mosaic elements, but minor phases were presumably added for coloring of mosaic pieces. Some degradation areas inside the volume of the mosaic fragments were found by means of neutron diffraction and neutron tomography methods. These degradation areas are probably related to the formation of iron hydroxides during chemical interactions of mosaic fragments with the sea and urban polluted atmosphere.

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X-ray topographic studies of dislocations in iron-silicon alloy single crystals

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1965.0105 ◽

1965 ◽

Vol 285 (1401) ◽

pp. 297-311 ◽

Cited By ~ 35

Keyword(s):

Single Crystals ◽

Bulk Material ◽

Spatial Arrangement ◽

Atomic Weight ◽

Thin Plates ◽

Etch Pits ◽

Etching Technique ◽

Dislocation Configuration ◽

X Ray ◽

Dislocation Etching

Thin plates cut from melt-grown single crystals of iron +3.5% silicon were examined by an X-ray transmission topographic method and the spatial arrangement of individual dislocations and of dislocation arrays was investigated. The directions (including the sense in some cases) of dislocation Burgers vectors were identified. It was confirmed that Burgers vectors lie along <111>. Reactions such as ½[1̄11] + ½[111̄] = [010] were not observed among the individually resolved dislocations. The minimum separation of dislocations for easy individual resolution was 3 μ m with Co Kα radiation and 5 μ m with Ag Kα . It was demonstrated that a one-to-one correspondence exists between dislocation outcrops and the etch pits produced by the dislocation-etching technique of Šesták (1959). The experiments showed that transmission X-ray topography when applied to metals of moderately heavy atomic weight can give a clear picture of the dislocation configuration in specimens sufficiently thick to be fully representative of the bulk material.

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THE MICROCRYSTALLINE STRUCTURE OF CELLULOSE IN CELL WALLS OF COTTON, RAMIE, AND JUTE FIBERS AS REVEALED BY NEGATIVE STAINING OF SECTIONS

The Journal of Cell Biology ◽

10.1083/jcb.29.2.181 ◽

1966 ◽

Vol 29 (2) ◽

pp. 181-197 ◽

Cited By ~ 65

Author(s):

A. N. J. Heyn

Keyword(s):

Cell Walls ◽

Spatial Arrangement ◽

Negative Staining ◽

X Ray Diffraction ◽

Indirect Methods ◽

X Ray ◽

Jute Fibers ◽

Ultrathin Sections ◽

A New Technique ◽

Microfibrillar Structure

With a new technique of negative staining of sections, it has been possible to observe directly, in ultrathin sections under the electron microscope, the original microcrystalline and microfibrillar structure of cellulose as it occurs in living cells. This method has advantages over the study of isolated fibers used so far by others, in that the original arrangement of microfibrils is better preserved, and their collapse into larger fibrillar units is prevented. With this method, the cell walls of ramie, jute, and cotton fibers have been studied. The size (diameter, 25 to 40 A) and the longitudinal periodicity observed in the single microfibrils and the orientation and spatial arrangement of the microcrystallite within the microfibrils are found to correspond with the latest models derived by others from data obtained by indirect methods such as X-ray diffraction. The microfibril size of about 35 A, found by measuring these structures in sections, agrees with the latest conclusions reached by others in recent work with isolated fibrils.

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Research on the Influence of Diffluent Salt Microstructural Variation in the Course of Recrystallization on the Strength of Salty Soil

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.170-173.1226 ◽

2012 ◽

Vol 170-173 ◽

pp. 1226-1229

Author(s):

Chun Lei Wang ◽

Chong Xi Jiang ◽

Feng Ju Guan

Keyword(s):

Mechanical Property ◽

Spatial Arrangement ◽

Soil Strength ◽

X Ray ◽

Soil Microstructure ◽

Additional Equipment ◽

Before And After ◽

The Relationship ◽

Engineering Characteristic ◽

Salty Soil

Salty soil distributed widely and the engineering characteristic was complicated. The mechanical property had the relationship with spatial arrangement of soil grains, mineral component and occurrence condition of diffluent salt. The soil microstructure was an important factor to engineering characteristics. The influence of diffluent salt recrystallization on soil strength was learned according to the microstructure analysis by using environment scanning electron microscope and additional equipment X-ray energy spectrum (EDX). The influence of microstructure variation on salt soil strength was obtained by direct shear test on the salty soil before and after dehydrating. The results showed that diffluent salt recrystallization affected soil internal structure. The salty soil microstructure character was different before and after dehydrating, which changed the soil- mechanical property of salty soil.

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Comparison between the Observed Density of Crystalline Rubber and the Density Calculated from X-Ray Data

Rubber Chemistry and Technology ◽

10.5254/1.3546606 ◽

1942 ◽

Vol 15 (2) ◽

pp. 265-271

Author(s):

W. Harold Smith ◽

Nancy P. Hanna

Keyword(s):

Crystal Structure ◽

Diffraction Pattern ◽

Spatial Arrangement ◽

Crystal Form ◽

Unit Cell ◽

X Ray Diffraction ◽

X Ray ◽

Simultaneous Production ◽

Accurate Knowledge ◽

Degree Of Crystallization

Abstract When unvulcanized rubber is stretched quickly, an orientation of structure occurs parallel to the direction of extension. This orientation is usually regarded as a form of crystallization, because of the optical and other phenomena which accompany it. It is also accompanied by a change of volume. When unstretched rubber is subjected to suitable temperatures below about 10° C, it too becomes crystalline. The crystallization of rubber is accompanied by an increase of density, and the simultaneous production of an x-ray diffraction pattern is usually interpreted as evidence that crystallization has occurred. A diffraction pattern of this kind results from regular repetition, within the crystal structure, of groups of atoms or molecules in a definite spatial arrangement. The smallest group from which the structure can be built up in this way is called the unit cell; and the dimensions can be computed from measurements of the pattern, provided it is possible to determine the crystal form. The pattern of stretched rubber consists of interference spots, and that of frozen rubber consists of rings, but both of their measurements have been shown to indicate the same unit cell. If, in addition, the number of atoms in the unit cell is known, the density of the material can be computed. If the computed density agrees with that found by direct measurement, the fact is a valuable indication of the correctness of the assumed structure on which the calculation of density was based. Accurate knowledge of the density of completely crystallized rubber would therefore serve both as a guide in studies of structure and as a measure of the degree of crystallization of any material under consideration. In the experimental work described in this paper, the rubber was crystallized as completely as possible. Its density was determined by recognized methods, and compared with the densities calculated from x-ray measurements.

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Supramolecular Chirogenesis in Bis-Porphyrin: Crystallographic Structure and CD Spectra for a Complex with a Chiral Guanidine Derivative

Symmetry ◽

10.3390/sym13020275 ◽

2021 ◽

Vol 13 (2) ◽

pp. 275

Author(s):

Irina Osadchuk ◽

Nele Konrad ◽

Khai-Nghi Truong ◽

Kari Rissanen ◽

Eric Clot ◽

...

Keyword(s):

Solid State ◽

Computational Simulation ◽

Spatial Arrangement ◽

Crystallographic Structure ◽

Supramolecular Organization ◽

Cd Spectra ◽

X Ray Diffraction ◽

Guest Complex ◽

X Ray ◽

Host Guest Complex

The complexation of (3aR,7aR)-N-(3,5-bis(trifluoromethyl)phenyl)octahydro-2H-benzo[d]imidazol-2-imine (BTI), as a guest, to ethane-bridged bis(zinc octaethylporphyrin), bis(ZnOEP), as a host, has been studied by means of ultraviolet-visible (UV-Vis) and circular dichroism (CD) absorption spectroscopies, single crystal X-ray diffraction, and computational simulation. The formation of 1:2 host-guest complex was established by X-ray diffraction and UV-Vis titration studies. Two guest BTI molecules are located at the opposite sides of two porphyrin subunits of bis(ZnOEP) host, which is resting in the anti-conformation. The complexation of BTI molecules proceed via coordination of the imine nitrogens to the zinc ions of each porphyrin subunit of the host. Such supramolecular organization of the complex results in a screw arrangement of the two porphyrin subunits, inducing a strong CD signal in the Soret (B) band region. The corresponding DFT computational studies are in a good agreement with the experimental results and prove the presence of 1:2 host-guest complex as the major component in the solution (97.7%), but its optimized geometry differs from that observed in the solid-state. The UV-Vis and CD spectra simulated by using the solution-state geometry and the TD-DFT/ωB97X-D/cc-pVDZ + SMD (CH2Cl2) level of theory reproduced the experimentally obtained UV-Vis and CD spectra and confirmed the difference between the solid-state and solution structures. Moreover, it was shown that CD spectrum is very sensitive to the spatial arrangement of porphyrin subunits.

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An Open Soil Structure Library based on X-ray CT data

10.5194/soil-2021-96 ◽

2021 ◽

Author(s):

Ulrich Weller ◽

Lukas Albrecht ◽

Steffen Schlüter ◽

Hans-Jörg Vogel

Keyword(s):

Soil Structure ◽

Wide Spectrum ◽

Structural Characteristics ◽

Open Data ◽

Spatial Arrangement ◽

Pedotransfer Functions ◽

Organic Carbon Content ◽

Undisturbed Soil ◽

X Ray ◽

Ct Data

Abstract. Soil structure in terms of the spatial arrangement of pores and solid is highly relevant for most physical, biochemical processes in soil. While this is known for long a scientific approach to quantify soil structural characteristics was also missing for long. This was due to its buried nature but also due to the three-dimensional complexity. During the last two decades, tools to acquire full 3D images of undisturbed soil became more and more available and a number of powerful software tools were developed to reduce the complexity to a set of meaningful numbers. However, the standardization of soil structure analysis for a better comparability of the results is not well developed and the accessibility of required computing facilities and software is still limited. At this stage we introduce an open access Soil Structure Library (https://structurelib.ufz.de/) which offers well-defined soil structure analyses for X-ray CT data sets uploaded by interested scientists. At the same time, the aim of this library is to serve as an open data source for real pore structures as developed in a wide spectrum of different soil types under different site conditions all over the globe. By combining pore structure metrics with essential soil information requested during upload (e.g. bulk density, texture, organic carbon content\\ldots), this Soil Structure Library can be harnessed towards data mining and development of soil structure based pedotransfer functions. In this paper we describe the architecture of the Soil Structure Library and the provided metrics. This is complemented by an example how the data base can be used to address new research questions.

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X-ray casting finite-element-modeling data

10.1117/12.235548 ◽

1996 ◽

Author(s):

Feng Dong ◽

Wenli Cai ◽

Jiaoying Shi

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Ray Casting ◽

X Ray ◽

Title X ◽

Element Modeling ◽

Modeling Data

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Decoding Rocks: An Assessment of Geomaterial Microstructure Using X-ray Microtomography, Image Analysis and Multivariate Statistics

Materials ◽

10.3390/ma14123266 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3266

Author(s):

Piotr Jan Strzelecki ◽

Anna Świerczewska ◽

Katarzyna Kopczewska ◽

Adam Fheed ◽

Jacek Tarasiuk ◽

...

Keyword(s):

Image Analysis ◽

Statistical Approach ◽

Methodological Approach ◽

Spatial Arrangement ◽

Sandstone Sample ◽

X Ray ◽

Spatial Properties ◽

Geometrical Features ◽

Directional Trend

An understanding of the microstructure of geomaterials such as rocks is fundamental in the evaluation of their functional properties, as well as the decryption of their geological history. We present a semi-automated statistical protocol for a complex 3D characterization of the microstructure of granular materials, including the clustering of grains and a description of their chemical composition, size, shape, and spatial properties with 44 unique parameters. The approach consists of an X-ray microtomographic image processing procedure, followed by measurements using image analysis and statistical multivariate analysis of its results utilizing freeware and widely available software. The statistical approach proposed was tested out on a sandstone sample with hidden and localized deformational microstructures. The grains were clustered into distinctive groups covering different compositional and geometrical features of the sample’s granular framework. The grains are pervasively and evenly distributed within the analysed sample. The spatial arrangement of grains in particular clusters is well organized and shows a directional trend referring to both microstructures. The methodological approach can be applied to any other rock type and enables the tracking of microstructural trends in grains arrangement.

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