Beam orientation optimization for coherent X-ray scattering from distributed deep targets

Abstract Background Amyloid deposits in the temporal and frontal lobes in patients with Alzheimer’s disease make them potential targets to aid in early diagnosis. Recently, spectral small-angle X-ray scattering techniques have been proposed for interrogating deep targets such as amyloid plaques. Results We describe an optimization approach for the orientation of beams for deep target characterization. The model predicts the main features of scattering profiles from targets with varying shape, size and location. We found that increasing target size introduced additional smearing due to location uncertainty, and incidence angle affected the scattering profile by altering the path length or effective target size. For temporal and frontal lobe targets, beam effectiveness varied up to 2 orders of magnitude. Conclusions Beam orientation optimization might allow for patient-specific optimal paths for improved signal characterization.

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Beam Orientation Optimization for Coherent X-Ray Scattering From Distributed Deep Targets

10.21203/rs.3.rs-542996/v1 ◽

2021 ◽

Author(s):

Sophya Breedlove ◽

Aldo Badano

Keyword(s):

Incidence Angle ◽

Target Size ◽

Patient Specific ◽

Optimization Approach ◽

X Ray ◽

X Ray Scattering ◽

Location Uncertainty ◽

Beam Orientation Optimization ◽

Orientation Optimization ◽

Ray Scattering

Abstract BackgroundAmyloid deposits in the temporal and frontal lobes in patients with Alzheimer's disease make them potential targets to aid in early diagnosis. Recently, spectral small-angle x-ray scattering techniques have been proposed for interrogating deep targets such as amyloid plaques. ResultsWe describe an optimization approach for the orientation of beams for deep target characterization. The model predicts the main features of scattering profiles from targets with varying shape, size and location. We found that increasing target size introduced additional smearing due to location uncertainty, and incidence angle affected the scattering profile by altering the path length or effective target size. For temporal and frontal lobe targets, beam effectiveness varied up to 2 orders of magnitude. ConclusionBeam orientation optimization might allow for patient-specific optimal paths for improved signal characterization.

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Optimization approach to 3D reconstruction from solution x-ray scattering data

10.1117/12.255076 ◽

1996 ◽

Author(s):

Yibin Zheng ◽

Peter C. Doerschuk

Keyword(s):

3D Reconstruction ◽

Scattering Data ◽

Optimization Approach ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

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Grazing-incidence small-angle X-ray scattering of soft and hard nanofabricated gratings

Journal of Applied Crystallography ◽

10.1107/s0021889812030415 ◽

2012 ◽

Vol 45 (5) ◽

pp. 1038-1045 ◽

Cited By ~ 42

Author(s):

D. R. Rueda ◽

I. Martín-Fabiani ◽

M. Soccio ◽

N. Alayo ◽

F. Pérez-Murano ◽

...

Keyword(s):

Small Angle ◽

Nanoimprint Lithography ◽

Incidence Angle ◽

Critical Length ◽

Grazing Incidence ◽

One Dimensional ◽

X Ray ◽

X Ray Scattering ◽

Characteristic Features ◽

Ray Scattering

Grazing-incidence small-angle X-ray scattering (GISAXS) has been used to structurally characterize model hard and soft gratings of nanotechnological interest. The different gratings exhibit GISAXS patterns with characteristic features that can be associated with their level of order along the direction of periodicity and the length of the lines. Highly ordered gratings, made out of silicon by electron beam lithography, and those nanofabricated on spin-coated polymer films by nanoimprint lithography, exhibit characteristic semicircle-like GISAXS patterns with intensity spots periodically distributed on a semicircle whose radius is related to the incidence angle used. These gratings can be considered as one-dimensional crystalline lattices as provided by computer simulations. Less ordered polymer gratings prepared by the laser-induced periodic surface structuring method exhibit a GISAXS pattern characterized by periodic rod-like scattering maxima whose intensity decreases with increasing horizontal scattering angle. In this case the gratings can be considered as one-dimensional paracrystals. The transition from a rod-like to a semicircle-like GISAXS pattern has been simulated and attributed to the contribution of the form factor by changing the length of the line (ripple). A critical length value for the transition is located at around a few micrometres.

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Generalized grazing-incidence-angle x-ray scattering analysis of quantum dots

Journal of Applied Physics ◽

10.1063/1.1539285 ◽

2003 ◽

Vol 93 (4) ◽

pp. 2034-2040 ◽

Cited By ~ 8

Author(s):

Masao Kimura ◽

Ana Acosta ◽

Hiroshi Fujioka ◽

Masaharu Oshima

Keyword(s):

Quantum Dots ◽

Incidence Angle ◽

Grazing Incidence ◽

X Ray ◽

X Ray Scattering ◽

Grazing Incidence Angle ◽

Ray Scattering

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Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077402 ◽

1983 ◽

Vol 41 ◽

pp. 766-767

Author(s):

Eva-Maria Mandelkow ◽

Eckhard Mandelkow ◽

Joan Bordas

Keyword(s):

Electron Microscopy ◽

Dynamic Equilibrium ◽

Time Resolved ◽

X Ray ◽

Additional Information ◽

X Ray Scattering ◽

Low Concentrations ◽

Microtubule Growth ◽

Ray Patterns ◽

Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

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Time-Resolved Cryo-Electron Microscopy of Oscillating Microtubules

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100181269 ◽

1990 ◽

Vol 48 (1) ◽

pp. 502-503

Author(s):

Eva-Maria Mandelkow ◽

Ron Milligan

Keyword(s):

Electron Microscopy ◽

Dynamic Instability ◽

Entire Solution ◽

Reaction Scheme ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

A Chain ◽

Ray Scattering

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?

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