Time Resolved, Three Dimensional Mass Distribution of Diesel Sprays Measured with X-Ray Radiography

2009 ◽  
Author(s):  
Alan Kastengren ◽  
Christopher F. Powell ◽  
Zunping Liu ◽  
Jin Wang
Keyword(s):  
Mass Distribution ◽  
Three Dimensional ◽  
Diesel Sprays ◽  
Time Resolved ◽  
X Ray

End-of-Injection Behavior of Diesel Sprays Measured With X-Ray Radiography

2010 ◽  
Author(s):  
Alan Kastengren ◽  
Christopher F. Powell ◽  
Zunping Liu ◽  
Seoksu Moon ◽  
Jian Gao ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Contrast Imaging ◽  
Diesel Sprays ◽  
Engine Emissions ◽  
X Ray ◽  
Spray Density ◽  
Spray Plume ◽  
Spray Distribution ◽  
Unburned Fuel ◽  
Spray Velocity

The behavior of diesel fuel sprays at the end of injection is poorly understood, yet has important implications regarding diesel engine emissions. Recent research has shown that at the end of injection, an entrainment wave is created, causing the fuel spray to rapidly entrain ambient gas. This rapid entrainment creates a dilute mixture of fuel that may be a source of unburned fuel emissions. In this study, x-ray radiography is used to examine the end-of-injection behavior of diesel sprays. X-ray radiography permits quantitative mass distribution measurements in dense sprays, providing data that cannot be obtained with optical techniques. Analysis of the spray velocity at steady-state suggests an entrainment wave speed of several hundred m/s, which is supported by the appearance of a travelling entrainment wave at low ambient density. The spray density declines most rapidly near the nozzle, behavior that matches the expected entrainment wave behavior. In several cases, the spray distribution in a cross-section across the nozzle axis becomes smoother at the end of injection. Three-dimensional reconstructions of the spray density at the end of injection show that the spray plume widens considerably, enhancing the dilution caused by the reduction in spray mass in the flowfield. Measurements of injector needle motion with x-ray phase contrast imaging show that throttling across the needle seat may cause a smearing of the ideally sharp entrainment wave.

Globule-Globule Interactions during Deformation in Semi-Solid Al-Cu Using Time-Resolved X-Ray Tomography

2012 ◽  
Vol 192-193 ◽  
pp. 179-184
Author(s):  
Kristina Maria Kareh ◽  
Peter D. Lee ◽  
Christopher M. Gourlay
Keyword(s):  
Solid Fraction ◽  
Three Dimensional ◽  
Solid Alloy ◽  
Three Dimensional Imaging ◽  
Time Resolved ◽  
X Ray ◽  
Analysis Techniques ◽  
Solid Deformation ◽  
Fundamental Understanding ◽  
Semi Solid

Optimising semi-solid processing and accurately modelling semi-solid deformation requires a fundamental understanding of the globule-scale mechanisms that cause the macroscopic rheological response. In this work, apparatus and analysis techniques are being developed for the time-resolved, three-dimensional imaging of semi-solid alloy deformation. This paper overviews synchrotron X-ray tomography results on globular Al-15wt%Cu deformed at 0.7 solid fraction using extrusion. The globule-globule interactions in response to load were quantified in terms of the response of individual globules with respect to globule translation, rotation, and deformation. The potential of time-resolved X-ray tomography in the study of semi-solid alloy deformation is then discussed.

Static Laue Diffraction Studies on Acetylcholinesterase

1998 ◽  
Vol 54 (6) ◽  
pp. 1359-1366 ◽  
Author(s):  
Raimond B. G. Ravelli ◽  
Mia L. Raves ◽  
Zhong Ren ◽  
Dominique Bourgeois ◽  
Michel Roth ◽  
...  
Keyword(s):  
Structural Change ◽  
Exposure Time ◽  
Active Site ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Reversible Inhibitor ◽  
Data Set ◽  
Time Resolved ◽  
X Ray ◽  
Density Maps

Acetylcholinesterase (AChE) is one of nature's fastest enzymes, despite the fact that its three-dimensional structure reveals its active site to be deeply sequestered within the molecule. This raises questions with respect to traffic of substrate to, and products from, the active site, which may be investigated by time-resolved crystallography. In order to address one aspect of the feasibility of performing time-resolved studies on AChE, a data set has been collected using the Laue technique on a trigonal crystal of Torpedo californica AChE soaked with the reversible inhibitor edrophonium, using a total X-ray exposure time of 24 ms. Electron-density maps obtained from the Laue data, which are of surprisingly good quality compared with similar maps from monochromatic data, show essentially the same features. They clearly reveal the bound ligand, as well as a structural change in the conformation of the active-site Ser200 induced upon binding.

scholarly journals Unveiling the spatial distribution of molecular coherences at conical intersections by covariance X-ray diffraction signals

2021 ◽  
Vol 118 (22) ◽  
pp. e2105046118
Author(s):  
Stefano M. Cavaletto ◽  
Daniel Keefer ◽  
Jérémy R. Rouxel ◽  
Flavia Aleotti ◽  
Francesco Segatta ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Three Dimensional ◽  
Laser Pulses ◽  
Conical Intersection ◽  
Conical Intersections ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Diffraction Imaging ◽  
The Rich

The outcomes and timescales of molecular nonadiabatic dynamics are decisively impacted by the quantum coherences generated at localized molecular regions. In time-resolved X-ray diffraction imaging, these coherences create distinct signatures via inelastic photon scattering, but they are buried under much stronger background elastic features. Here, we exploit the rich dynamical information encoded in the inelastic patterns, which we reveal by frequency-dispersed covariance ultrafast powder X-ray diffraction of stochastic X-ray free-electron laser pulses. This is demonstrated for the photoisomerization of azobenzene involving the passage through a conical intersection, where the nuclear wave packet branches and explores different quantum pathways. Snapshots of the coherence dynamics are obtained at high frequency shifts, not accessible with conventional diffraction measurements. These provide access to the timing and to the confined spatial distribution of the valence electrons directly involved in the conical intersection passage. This study can be extended to full three-dimensional imaging of conical intersections with ultrafast X-ray and electron diffraction.

scholarly journals Time-resolved in situ visualization of the structural response of zeolites during catalysis

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jinback Kang ◽  
Jerome Carnis ◽  
Dongjin Kim ◽  
Myungwoo Chung ◽  
Jaeseung Kim ◽  
...  
Keyword(s):  
Active Sites ◽  
Density Functional ◽  
Three Dimensional ◽  
Structural Response ◽  
Active Regions ◽  
Structural Deformation ◽  
Time Resolved ◽  
X Ray ◽  
Future Design

AbstractZeolites are three-dimensional aluminosilicates having unique properties from the size and connectivity of their sub-nanometer pores, the Si/Al ratio of the anionic framework, and the charge-balancing cations. The inhomogeneous distribution of the cations affects their catalytic performances because it influences the intra-crystalline diffusion rates of the reactants and products. However, the structural deformation regarding inhomogeneous active regions during the catalysis is not yet observed by conventional analytical tools. Here we employ in situ X-ray free electron laser-based time-resolved coherent X-ray diffraction imaging to investigate the internal deformations originating from the inhomogeneous Cu ion distributions in Cu-exchanged ZSM-5 zeolite crystals during the deoxygenation of nitrogen oxides with propene. We show that the interactions between the reactants and the active sites lead to an unusual strain distribution, confirmed by density functional theory simulations. These observations provide insights into the role of structural inhomogeneity in zeolites during catalysis and will assist the future design of zeolites for their applications.

Study of The Hydrothermal Synthesis of Gallium Phosphates Using in Situ Time-Resolved X-Ray Diffraction

1998 ◽  
Vol 547 ◽  
Author(s):  
R.I. Walton ◽  
T. Loiseau ◽  
R.J. Francis ◽  
D. O'Hare ◽  
G. Férey
Keyword(s):  
Kinetic Data ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Effect Of Temperature ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
Time Resolved ◽  
X Ray ◽  
Phosphorus Source

AbstractThe hydrothermal crystallisation (130-180 °C) of three-dimensional open-framework gallium and aluminium oxyfluoro-phosphates with the ULM-3 and ULM-4 structures have been studied in situ for the first time. The in situ energy-dispersive X-ray diffraction method has allowed the formation of the crystalline products to be observed under hydrothermal conditions The integrated areas of the strongest Bragg reflections has allowed quantitative kinetic data to be extracted. The effect of temperature, phosphorus source, templating agent have been investigated. The nature of phosphorus source in the reaction mixture has been found to affect dramatically the course of reaction for certain combinations of amine and temperature. Previously unobserved transient crystalline phases have been seen during the production of ULM-3 gallium phosphates when P2O5 or polyphosphoric acid are used. The formation of these intermediates affects the kinetics of product growth. In the case of the aluminium ULM-3 materials reaction always proceeds via a crystalline intermediate whatever phosphorus source is used. The ULM-4 framework materials are found to always crystallise directly with no evidence for any intermediates. Kinetic data for each system have been modelled using standard solid-state chemistry expressions, and these calculations indicate the reactions to be diffusion controlled.

scholarly journals Time-resolved structural studies of protein reaction dynamics: a smorgasbord of X-ray approaches

2010 ◽  
Vol 66 (2) ◽  
pp. 207-219 ◽  
Author(s):  
Sebastian Westenhoff ◽  
Elena Nazarenko ◽  
Erik Malmerberg ◽  
Jan Davidsson ◽  
Gergely Katona ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Conformational Dynamics ◽  
Three Dimensional ◽  
Superoxide Reductase ◽  
Time Resolved ◽  
X Ray ◽  
Starting Point ◽  
Absorption Studies ◽  
High Resolution Structure ◽  
Experimental Approaches

Proteins undergo conformational changes during their biological function. As such, a high-resolution structure of a protein's resting conformation provides a starting point for elucidating its reaction mechanism, but provides no direct information concerning the protein's conformational dynamics. Several X-ray methods have been developed to elucidate those conformational changes that occur during a protein's reaction, including time-resolved Laue diffraction and intermediate trapping studies on three-dimensional protein crystals, and time-resolved wide-angle X-ray scattering and X-ray absorption studies on proteins in the solution phase. This review emphasizes the scope and limitations of these complementary experimental approaches when seeking to understand protein conformational dynamics. These methods are illustrated using a limited set of examples including myoglobin and haemoglobin in complex with carbon monoxide, the simple light-driven proton pump bacteriorhodopsin, and the superoxide scavenger superoxide reductase. In conclusion, likely future developments of these methods at synchrotron X-ray sources and the potential impact of emerging X-ray free-electron laser facilities are speculated upon.

scholarly journals Beyond a phenomenological description of magnetostriction

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
A. H. Reid ◽  
X. Shen ◽  
P. Maldonado ◽  
T. Chase ◽  
E. Jal ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Magnetic Order ◽  
Three Dimensional ◽  
Fept Nanoparticles ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Fs Laser ◽  
The Time Domain ◽  
Microscopic Origin

Abstract Magnetostriction, the strain induced by a change in magnetization, is a universal effect in magnetic materials. Owing to the difficulty in unraveling its microscopic origin, it has been largely treated phenomenologically. Here, we show how the source of magnetostriction—the underlying magnetoelastic stress—can be separated in the time domain, opening the door for an atomistic understanding. X-ray and electron diffraction are used to separate the sub-picosecond spin and lattice responses of FePt nanoparticles. Following excitation with a 50-fs laser pulse, time-resolved X-ray diffraction demonstrates that magnetic order is lost within the nanoparticles with a time constant of 146 fs. Ultrafast electron diffraction reveals that this demagnetization is followed by an anisotropic, three-dimensional lattice motion. Analysis of the size, speed, and symmetry of the lattice motion, together with ab initio calculations accounting for the stresses due to electrons and phonons, allow us to reveal the magnetoelastic stress generated by demagnetization.

The hydrolytic water molecule in trypsin, revealed by time-resolved Laue crystallography

Science ◽  
1993 ◽  
Vol 259 (5095) ◽  
pp. 669-673 ◽  
Author(s):  
PT Singer ◽  
A Smalas ◽  
RP Carty ◽  
WF Mangel ◽  
RM Sweet
Keyword(s):  
Water Molecule ◽  
Three Dimensional ◽  
Initial Step ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Density Maps ◽  
Before And After ◽  
Ph Jump ◽  
Hydrolysis Of

Crystals of bovine trypsin were acylated at the reactive residue, serine 195, to form the transiently stable p-guanidinobenzoate. Hydrolysis of this species was triggered in the crystals by a jump in pH. The hydrolysis was monitored by three-dimensional Laue crystallography, resulting in three x-ray diffraction structures, all from the same crystal and each representing approximately 5 seconds of x-ray exposure. The structures were analyzed at a nominal resolution of 1.8 angstroms and were of sufficient quality to reproduce subtle features in the electron-density maps for each of the structures. Comparison of the structures before and after the pH jump reveals that a water molecule has positioned itself to attack the acyl group in the initial step of the hydrolysis of this transient intermediate.

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