Texture of nanocrystalline solids: atomic scale characterization and applications

2018 ◽  
Vol 51 (1) ◽  
pp. 124-132 ◽  
Author(s):  
J. C. E ◽  
Y. Cai ◽  
Z. Y. Zhong ◽  
M. X. Tang ◽  
X. R. Zhu ◽  
...  
Keyword(s):  
Shock Wave ◽  
Pole Figure ◽  
Inverse Pole Figure ◽  
Orientation Distribution ◽  
Fiber Texture ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
Wave Compression ◽  
Scale Characterization ◽  
Dynamics Simulations

A methodology is presented to characterize the crystallographic texture of atomic configurations on the basis of Euler angles. Texture information characterized by orientation map, orientation distribution function, texture index, pole figure and inverse pole figure is obtained. The paper reports the construction and characterization of the texture of nanocrystalline configurations with different grain numbers, grain sizes and percentages of preferred orientation. The minimum grain number for texture-free configurations is ∼2500. The effect of texture on deducing grain size from simulated X-ray diffraction curves is also explored as an application case of texture analysis. In addition, molecular dynamics simulations are performed on initially texture-free nanocrystalline Ta under shock-wave loading, which shows a 〈001〉 + 〈111〉 double fiber texture after shock-wave compression.

Shock Wave Compression of NaCl Single Crystals observed by Flash-X-Ray Diffraction

1978 ◽  
Vol 33 (8) ◽  
pp. 918-923 ◽  
Author(s):  
F. Müller ◽  
E. Schulte
Keyword(s):  
Shock Wave ◽  
Single Crystals ◽  
Observation Time ◽  
Plane Shock ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wave Compression ◽  
Shock Wave Compression ◽  
Diffraction Patterns ◽  
Set Up

Flash-x-ray-diffraction patterns (FXD) with an exposure time of 4 ns of NaCl single crystals compressed by plane shock waves are obtained at pressures of about 30 kbar. From the diffraction patterns the compression is determined and compared with Hugoniot data. During shock load the lattice shows an uniaxial compression. While in case of measurements at the free surface an observation time of only a few nanoseconds is available, this experimental set-up allows an observation time of two microseconds.

Effects of Nanoscale Voids on the Sensitivity of Model Energetic Materials

1995 ◽  
Vol 418 ◽  
Author(s):  
C. T Whitea ◽  
J. J. C. Barretta ◽  
J. W. Mintmirea ◽  
M. L. Elert ◽  
D. H. Robertson
Keyword(s):  
Shock Wave ◽  
Molecular Dynamics ◽  
Hot Spots ◽  
Energetic Materials ◽  
Theoretical Study ◽  
Atomic Scale ◽  
Nanometer Scale ◽  
Higher Temperature ◽  
Detonation Transition ◽  
Dynamics Simulations

AbstractBecause of its importance in designing safer, more reliable explosives the shock to detonation transition in condensed phase energetic materials has long been a subject of experimental and theoretical study. This transition is thought to involve local hot-spots which represent regions in the material which couple efficiently to the shock wave leading to a locally higher temperature and ultimately initiation. However, how at the atomic scale energy is transferred from the shock front into these local “hot spots” remains a key question to be answered in studies of the predetonation process. In this paper we report results of molecular dynamics simulations that suggest that even nanometer scale defects can play an important role in the shock to detonation transition.

X-Ray Diffraction During Shock-Wave Compression

1970 ◽  
Vol 25 (16) ◽  
pp. 1099-1101 ◽  
Author(s):  
Quintin Johnson ◽  
A. Mitchell ◽  
R. Norris Keeler ◽  
L. Evans
Keyword(s):  
Shock Wave ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wave Compression ◽  
Shock Wave Compression

Effect of Aluminum Content on Texture Formation Behaviors in Magnesium Alloy

2016 ◽  
Vol 879 ◽  
pp. 1449-1453 ◽  
Author(s):  
Min Soo Park ◽  
Hyung Gyun Park ◽  
Jun Ho Choi ◽  
Kwon Hoo Kim
Keyword(s):  
Magnesium Alloy ◽  
Aluminum Content ◽  
Orientation Distribution ◽  
Solute Concentration ◽  
Fiber Texture ◽  
Compression Tests ◽  
Basal Texture ◽  
X Ray Diffraction ◽  
X Ray ◽  
Main Components

In order to understand the effects of the solute element and its concentration on the formation of texture, uniaxial compression tests were carried out at various deformation conditions with different aluminum solute concentration in rolled AZ magnesium alloy (AZ31, AZ61, AZ91). To clarify the texture measurements and crystal orientation distribution, X-ray diffraction methods were conducted on mid plane section of the specimens. As a result in this study, the formation of fiber texture and occurrence of dynamic recrystallization were observed in all case of specimens. The main components and its sharpness of texture were varied depending on deformation conditions and Al concentrations. Especially, accumulation of basal texture was developed with an increasing of Al concentration.

Submicrosecond X-Ray Diffraction Studies

1972 ◽  
Vol 16 ◽  
pp. 242-250
Author(s):  
A. C. Mitchell ◽  
Quintin Johnson ◽  
L. Evans
Keyword(s):  
Shock Wave ◽  
Shock Front ◽  
Lithium Fluoride ◽  
X Ray Diffraction ◽  
Time Intervals ◽  
X Ray ◽  
Sensitive Film ◽  
Wave Compression ◽  
Sufficient Intensity ◽  
Shock Wave Compression

AbstractAs a result of interest stemming from shock wave studies carried out at Lawrence Livermore Laboratory, we have developed a capability to conduct x-ray diffraction studies in submicrosecond time intervals. This involves the use of a low impedance flash x-ray device. While there are many applications to which these techniques can be put, our first experiments deal with samples undergoing shock wave compression. These particular experiments are conducted by synchronizing a 40 to 50 nsec flash x-ray device to a shock front which is produced by the detonation of a high explosive placed in contact with a sample. Diffracted radiation is usually recorded on very sensitive film protected by a blast cassette. Thus far we have subjected lithium fluoride, aluminum, and carbon to pressures in the range of 100 to 300 kbar. Either powder or single crystal samples can be used. The principal difficulties of this experiment are the lack of sufficient intensity and the synchronization of the x-ray pulse to the shock front.

scholarly journals Atomic-scale characterization of mature HIV-1 capsid stabilization by inositol hexakisphosphate (IP6)

2020 ◽  
Vol 6 (38) ◽  
pp. eabc6465 ◽  
Author(s):  
Alvin Yu ◽  
Elizabeth M. Y. Lee ◽  
Jaehyeok Jin ◽  
Gregory A. Voth
Keyword(s):  
Kinetic Studies ◽  
Binding Pocket ◽  
Free Energy Calculations ◽  
Atomic Scale ◽  
Binding Modes ◽  
Ligand Density ◽  
Scale Characterization ◽  
Dynamics Simulations

Inositol hexakisphosphates (IP6) are cellular cofactors that promote the assembly of mature capsids of HIV. These negatively charged molecules coordinate an electropositive ring of arginines at the center of pores distributed throughout the capsid surface. Kinetic studies indicate that the binding of IP6 increases the stable lifetimes of the capsid by several orders of magnitude from minutes to hours. Using all-atom molecular dynamics simulations, we uncover the mechanisms that underlie the unusually high stability of mature capsids in complex with IP6. We find that capsid hexamers and pentamers have differential binding modes for IP6. Ligand density calculations show three sites of interaction with IP6 including at a known capsid inhibitor binding pocket. Free energy calculations demonstrate that IP6 preferentially stabilizes pentamers over hexamers to enhance fullerene modes of assembly. These results elucidate the molecular role of IP6 in stabilizing and assembling the retroviral capsid.

X‐ray diffraction study of single crystals undergoing shock‐wave compression

1972 ◽  
Vol 21 (1) ◽  
pp. 29-30 ◽  
Author(s):  
Quintin Johnson ◽  
Arthur C. Mitchell ◽  
L. Evans
Keyword(s):  
Shock Wave ◽  
Diffraction Study ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wave Compression ◽  
Shock Wave Compression

scholarly journals Atomic-scale Characterization of Mature HIV-1 Capsid Stabilization by Inositol Hexakisphosphate (IP6)

2020 ◽  
Author(s):  
Alvin Yu ◽  
Elizabeth M.Y. Lee ◽  
Jaehyeok Jin ◽  
Gregory A. Voth
Keyword(s):  
Kinetic Studies ◽  
Binding Pocket ◽  
Free Energy Calculations ◽  
Atomic Scale ◽  
Binding Modes ◽  
Ligand Density ◽  
Immunodeficiency Virus ◽  
Scale Characterization ◽  
Dynamics Simulations

AbstractInositol hexakisphosphates (IP6) are cellular cofactors that promote the assembly of mature capsids of the human immunodeficiency virus (HIV). These negatively charged molecules coordinate an electropositive ring of arginines at the center of pores distributed throughout the capsid surface. Kinetic studies indicate that the binding of IP6 increases the stable life times of the capsid by several orders of magnitude from minutes to hours. Using all-atom molecular dynamics simulations, we uncover the mechanisms that underlie the unusually high stability of mature capsids in complex with IP6. We find that capsid hexamers and pentamers have differential binding modes for IP6. Ligand density calculations show three sites of interaction with IP6 including at a known capsid-inhibitor binding pocket. Free energy calculations demonstrate that IP6 preferentially stabilizes pentamers over hexamers to enhance fullerene modes of assembly. These results elucidate the molecular role of IP6 in stabilizing and assembling the retroviral capsid.

Sign in / Sign up

Export Citation Format

Share Document