scholarly journals Structural Analysis of Melt-Spun Polymer-Optical Poly(Methyl Methacrylate) Fibres by Small-Angle X-ray Scattering and Monte-Carlo Simulation

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 779
Author(s):  
Jan Kallweit ◽  
Thomas Vad ◽  
Felix Krooß ◽  
Thomas Gries ◽  
Mohmmed Houri ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Structural Properties ◽  
Small Angle ◽  
Processing Parameters ◽  
Distribution Functions ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Melt Spun ◽  
Ray Scattering

The structural properties, mainly the spatial variation of density and chain interaction, of melt-spun polymer optical fibres (POFs) are investigated by small-angle X-ray scattering (SAXS) and compared to Monte-Carlo polymer simulations. The amorphous PMMA POFs had been subjected to a rapid cooling in a water quench right after extrusion in order to obtain a radial refractive-index profile. Four fibre samples with different processing parameters are investigated and the SAXS data analysed via Guinier approach. Distance-distribution functions from the respective equatorial and meridional SAXS data are computed to extract the fibres’ nanostructures in the equatorial plane and along the fibre axis, respectively. Temperature profiles of the cooling process are simulated for different locations within the fibre and taken as input for Monte-Carlo simulations of the polymer structure. The simulation results agree with the SAXS measurements in terms of the cooling profile’s strong influence on the structural properties of the fibre: slower cooling in the centre of the fibre leads to stronger interchain interaction, but also results in a higher density and more homogenous materials with less optical scattering.

Exploring the Structural Properties of Simple Aldehydes: A Monte Carlo and Small-Angle X-ray Scattering Study

2009 ◽  
Vol 113 (28) ◽  
pp. 9429-9435 ◽  
Author(s):  
Andrej Lajovic ◽  
Matija Tomšič ◽  
Gerhard Fritz-Popovski ◽  
Lukáš Vlček ◽  
Andrej Jamnik
Keyword(s):  
Monte Carlo ◽  
Structural Properties ◽  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Ray Scattering

Structural refinement by restrained molecular-dynamics algorithm with small-angle X-ray scattering constraints for a biomolecule

2004 ◽  
Vol 37 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Masaki Kojima ◽  
Alexander A. Timchenko ◽  
Junichi Higo ◽  
Kazuki Ito ◽  
Hiroshi Kihara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Small Angle ◽  
Protein Structures ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Saxs Curve ◽  
Restrained Molecular Dynamics ◽  
Ray Scattering

A new algorithm to refine protein structures in solution from small-angle X-ray scattering (SAXS) data was developed based on restrained molecular dynamics (MD). In the method, the sum of squared differences between calculated and observed SAXS intensities was used as a constraint energy function, and the calculation was started from given atomic coordinates, such as those of the crystal. In order to reduce the contribution of the hydration effect to the deviation from the experimental (objective) curve during the dynamics, and purely as an estimate of the efficiency of the algorithm, the calculation was first performed assuming the SAXS curve corresponding to the crystal structure as the objective curve. Next, the calculation was carried out with `real' experimental data, which yielded a structure that satisfied the experimental SAXS curve well. The SAXS data for ribonuclease T1, a single-chain globular protein, were used for the calculation, along with its crystal structure. The results showed that the present algorithm was very effective in the refinement and adjustment of the initial structure so that it could satisfy the objective SAXS data.

scholarly journals Dispersion of Silica Particles in Rubber During Elongation Revealed by Ultra Small Angle X-ray Scattering and Reverse Monte Carlo Modelling

2019 ◽  
Vol 92 (4) ◽  
pp. 152-157
Author(s):  
Tomotaka NAKATANI ◽  
Shinji KOHARA ◽  
Taiki HOSHINO ◽  
So FUJINAMI ◽  
Masaki TAKATA
Keyword(s):  
Monte Carlo ◽  
Small Angle ◽  
Silica Particles ◽  
Reverse Monte Carlo ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Quality control of protein standards for molecular mass determinations by small-angle X-ray scattering

2010 ◽  
Vol 43 (2) ◽  
pp. 237-243 ◽  
Author(s):  
Shuji Akiyama
Keyword(s):  
Quality Control ◽  
Molecular Mass ◽  
Small Angle ◽  
Biological Macromolecules ◽  
Average Deviation ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Standard Quality ◽  
Ray Scattering

Small-angle X-ray scattering (SAXS) is a powerful technique with which to evaluate the size and shape of biological macromolecules in solution. Forward scattering intensity normalized relative to the particle concentration,I(0)/c, is useful as a good measure of molecular mass. A general method for deducing the molecular mass from SAXS data is to determine the ratio ofI(0)/cof a target protein to that of a standard protein with known molecular mass. The accuracy of this interprotein calibration is affected considerably by the monodispersity of the prepared standard, as well as by the precision in estimating its concentration. In the present study, chromatographic fractionation followed by hydrodynamic characterization is proposed as an effective procedure by which to prepare a series of monodispersed protein standards. The estimation of molecular mass within an average deviation of 8% is demonstrated using monodispersed bovine serum albumin as a standard. The present results demonstrate the importance of protein standard quality control in order to take full advantage of interprotein calibration.

Small-Angle X-Ray Scattering for the Discerning Macromolecular Crystallographer

2014 ◽  
Vol 67 (12) ◽  
pp. 1786 ◽  
Author(s):  
Lachlan W. Casey ◽  
Alan E. Mark ◽  
Bostjan Kobe
Keyword(s):  
Structural Biology ◽  
Small Angle ◽  
Significant Risk ◽  
Macromolecular Crystallography ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

The role of small-angle X-ray scattering (SAXS) in structural biology is now well established, and its usefulness in combination with macromolecular crystallography is clear. However, the highly averaged SAXS data present a significant risk of over-interpretation to the unwary practitioner, and it can be challenging to frame SAXS results in a manner that maximises the reliability of the conclusions drawn. In this review, a series of recent examples are used to illustrate both the challenges for interpretation and approaches through which these can be overcome.

Influence of polychromaticity on particle structure determination in small-angle X-ray scattering

2015 ◽  
Vol 48 (6) ◽  
pp. 1935-1942 ◽  
Author(s):  
Wenjia Wang ◽  
Eleonora V. Shtykova ◽  
Vladimir V. Volkov ◽  
Guangcai Chang ◽  
Lianhui Zhang ◽  
...  
Keyword(s):  
Small Angle ◽  
Structural Parameters ◽  
Shape Reconstruction ◽  
The Body ◽  
Particle Structure ◽  
Saxs Data ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Pink beams are now widely used for small-angle X-ray scattering (SAXS) data collection owing to their high intensity. However, the wavelength spread of a pink beam is a factor of 100 higher than that of a monochromatic beam, thus causing the experimental data to be smeared. To reveal the influence of polychromaticity on shape reconstruction, four geometric bodies (sphere, cube, helix and long cylinder) were used for SAXS data analysis. The results reveal that the influence of polychromaticity on the process of shape reconstruction is significantly more dependent on the geometry of the body than on its size. Scattering objects with smoothed scattering curves can tolerate a higher wavelength spread than those with tortuous curves. It is further demonstrated that the structural parameters calculated from the smeared data sets have little deviation from the ideal ones, which indicates the possibility of using a light source with a greater wavelength spread than a conventional pink beam for special time-resolved SAXS experiments. Finally, it is concluded that SAXS data collected in pink-beam mode can be used directly for structural calculations and model reconstructions without a desmearing procedure.

Silicon photodiode detector for small-angle X-ray scattering

1990 ◽  
Vol 23 (5) ◽  
pp. 430-432 ◽  
Author(s):  
P. R. Jemian ◽  
G. G. Long
Keyword(s):  
Small Angle ◽  
Signal To Noise Ratio ◽  
Scintillation Counter ◽  
Detector Response ◽  
Silicon Photodiode ◽  
Double Crystal ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

A photodiode X-ray detector was built to measure small-angle X-ray scattering (SAXS) at a synchrotron-radiation source in conjunction with a double-crystal diffractometer SAXS camera at photon energies between 5 and 11 keV. The photodiode detector response in this energy range is linear at photon counting rates up to 1012 photons s−1 and thus it was not necessary to attenuate the monochromatic X-ray beam with calibrated foils. SAXS data taken with a scintillation counter and the photodiode detector are compared, demonstrating marked improvement in counting statistics, rate of data acquisition and signal-to-noise ratio.

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