scholarly journals X-ray diffraction reveals the mechanical load tolerance of mammalian neuronal tissues in traumatically induced injury

2020 ◽  
Vol 76 (a1) ◽  
pp. a6-a6
Author(s):  
Joseph Orgel
2011 ◽  
Vol 681 ◽  
pp. 97-102 ◽  
Author(s):  
Sylvain Fréour ◽  
Emmanuel Lacoste ◽  
Manuel François ◽  
Ronald Guillén

The scope of this work is the determination of single-crystals elastic constants (SEC) from X-ray diffraction lattice strains measurements performed on multi-phase polycrystals submitted to mechanical load through a bending device. An explicit three scales inverse self-consistent model is developed in order to express the SEC of a cubic phase, embedded in a multi-phase polycrystal, as a function of its X-ray Elasticity Constants. Finally, it is applied to a two-phases (α+β) titanium based alloy (Ti-17), in order to estimate Ti-17 β-phase unknown SEC. The purpose of the present work is to account the proper microstructure of the material. In particular, the morphologic texture of Ti-17 a-phase, i.e. the relative disorientation of the needle-shaped grains constituting this phase, is considered owing to the so-called Generalized Self-Consistent model.


2017 ◽  
Vol 8 (10) ◽  
pp. 4331 ◽  
Author(s):  
Eleonora Carboni ◽  
Jan-David Nicolas ◽  
Mareike Töpperwien ◽  
Christine Stadelmann-Nessler ◽  
Paul Lingor ◽  
...  

2009 ◽  
Vol 88 (12) ◽  
pp. 1107-1112 ◽  
Author(s):  
Y. Suzuki ◽  
S. Kamakura ◽  
Y. Honda ◽  
T. Anada ◽  
K. Hatori ◽  
...  

Synthetic octacalcium phosphate (OCP) has been shown to enhance bone formation and to biodegrade if implanted into bone defects. Here, we hypothesized that an OCP-atelocollagen complex (OCP/Col) is biodegradable and can induce bone formation in a thickness-dependent manner when implanted into the calvaria. OCP/Col disks (diameter, 9 mm; thickness, 1 or 3 mm) were implanted into a subperiosteal pocket in the calvaria of 12-week-old Wistar rats for 4, 8, and 12 weeks and subsequent bone formation was monitored. X-ray diffraction analysis and Fourier transform infrared spectroscopy showed that OCP in the OCP/Col implants was converted into a carbonate-rich apatite after 4 weeks. Although thinner disks tended to be replaced by new bone, thicker disks were progressively resorbed by osteoclast-like cells until 12 weeks, possibly via the increased mechanical load in the subperiosteal pocket. Therefore, OCP/Col can increase appositional intra-membranous bone formation if the appropriate size of the implant is applied.


2020 ◽  
Vol 53 (3) ◽  
pp. 734-740
Author(s):  
P. V. Gureva ◽  
N. V. Marchenkov ◽  
A. N. Artemev ◽  
N. A. Artemiev ◽  
A. D. Belyaev ◽  
...  

This article presents measurements of the piezoelectric modulus d 11 of a single crystal of lanthanum gallium silicate (LGS, La3Ga5SiO14). The piezoelectric modulus was measured by X-ray diffraction at angles close to backscattering. Experiments in such schemes are very sensitive to relative changes in the lattice constant in crystals caused by external influences (constant or alternating electric field, mechanical load, temperature change etc.). The development opportunity of the technique is shown, its applicability is evaluated and results of measurement of the LGS single-crystal piezo modulus by the method of diffraction of synchrotron radiation at angles near π are discussed.


2019 ◽  
Vol 26 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Joseph Orgel ◽  
Rama S. Madhurapantula ◽  
Ashley Eidsmore ◽  
Meng Wang ◽  
Pavel Dutov ◽  
...  

An ex vivo blunt-force loading experiment is reported that may, in the future, provide insight into the molecular structural changes occurring in load-induced conditions such as traumatic brain injury (TBI). TBI appears to manifest in changes in multiple structures and elements within the brain and nervous system. Individuals with a TBI may suffer from cognitive and/or behavioral impairments which can adversely affect their quality of life. Information on the injury threshold of tissue loading for mammalian neurons is critical in the development of a quantified neuronal-level dose-response model. Such a model could aid in the discovery of enhanced methods for TBI detection, treatment and prevention. Currently, thresholds of mechanical load leading to direct force-coupled nanostructural changes in neurons are unknown. In this study, we make use of the fact that changes in the structure and periodicity of myelin may indicate neurological damage and can be detected with X-ray diffraction (XRD). XRD allows access to a nanoscopic resolution range not readily achieved by alternative methods, nor does the experimental methodology require chemical sample fixation. In this study, XRD was used to evaluate the affects of controlled mechanical loading on myelin packing structure in ex vivo optic nerve samples. By using a series of crush tests on isolated optic nerves a quantified baseline for mechanical load was found to induce changes in the packing structure of myelin. To the authors' knowledge, this is the first report of its kind.


Author(s):  
R. E. Herfert

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.


Author(s):  
James A. Lake

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.


Author(s):  
C. Wolpers ◽  
R. Blaschke

Scanning microscopy was used to study the surface of human gallstones and the surface of fractures. The specimens were obtained by operation, washed with water, dried at room temperature and shadowcasted with carbon and aluminum. Most of the specimens belong to patients from a series of X-ray follow-up study, examined during the last twenty years. So it was possible to evaluate approximately the age of these gallstones and to get information on the intensity of growing and solving.Cholesterol, a group of bile pigment substances and different salts of calcium, are the main components of human gallstones. By X-ray diffraction technique, infra-red spectroscopy and by chemical analysis it was demonstrated that all three components can be found in any gallstone. In the presence of water cholesterol crystallizes in pane-like plates of the triclinic crystal system.


Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.


Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.


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