A Small-Angle X-ray Scattering Study of the Lyotropic Nematic Phase of Vanadium Pentoxide Gels

1997 ◽  
Vol 30 (5) ◽  
pp. 727-732 ◽  
Author(s):  
P. Davidson ◽  
C. Bourgaux ◽  
P. Sergot ◽  
J. Livage
Keyword(s):  
Vanadium Pentoxide ◽  
Small Angle ◽  
Nematic Phase ◽  
Average Distance ◽  
Building Blocks ◽  
X Ray ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Nematic Phases ◽  
Ray Scattering

Aqueous suspensions of vanadium pentoxide (V2O5) ribbons, also called Zocher phases, are known to display a lyotropic nematic phase. In this paper, it is shown how the small-angle X-ray scattering (SAXS) technique can provide useful information on the building blocks and their organization in this phase. SAXS experiments were performed either on unoriented samples or on samples aligned by a magnetic field or by shear flow. The scattering is comparable to that of the other classic lyotropic nematic phases displayed by stiff organic rod-like particles such as the tobacco mosaic virus. Scattering studies show that the building blocks have a ribbon shape, that their thickness is 9 (1) Å and indirectly that their width is several 100 Å. Their length is known to be around a few thousand Å and therefore could not be measured by SAXS. By following the average distance between the ribbons as a function of concentration, it is shown that the swelling of the phase is one-dimensional at large concentrations and two-dimensional at low concentrations. Finally, estimates of the nematic order parameter of a single domain sample and of samples sheared in a Couette cell have been obtained.

scholarly journals Structural characterization using the multiple scattering effects in grazing-incidence small-angle X-ray scattering

2008 ◽  
Vol 41 (1) ◽  
pp. 134-142 ◽  
Author(s):  
Byeongdu Lee ◽  
Chieh-Tsung Lo ◽  
P. Thiyagarajan ◽  
Dong R. Lee ◽  
Zhongwei Niu ◽  
...  
Keyword(s):  
Multiple Scattering ◽  
Small Angle ◽  
Incident Angle ◽  
Average Distance ◽  
Grazing Incidence ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Effects ◽  
Multiple Scattering Effects ◽  
Ray Scattering

The multiple scattering effects present in grazing-incidence small-angle X-ray scattering (GISAXS) data and interference between them are addressed theoretically as well as experimentally with measurement of a series of patterns at different incident angles, referred to as `incident-angle-resolved GISAXS' (IAR-GISAXS). X-ray reflectivity (XR), GISAXS and IAR-GISAXS of virus particles on Si-substrate supported-polystyrene films have been measured and all the data have been analyzed with appropriate formalisms. It was found that under certain conditions it is possible to extract the correct structural features of the materials from the GISAXS/IAR-GISAXS data using the kinematic SAXS formalisms, without the need to use the distorted-wave Born approximation. Furthermore, the Kiessig fringes in GISAXS enable the measurement of the average distance between the particle and the substrate, similar to the measurement of film thickness using the fringes in the XR data. It is believed that the methods developed here will expand the application of GISAXS as they enable the application of model-independent and kinematic SAXS theories to nanostructured two-dimensional ordered films.

Collagen Fibril Orientation in Tissue Specimens from Atherosclerotic Plaque Explored Using Small Angle X-Ray Scattering

2021 ◽  
Author(s):  
Herbert Silva ◽  
Christopher Tassone ◽  
Elsie Gyang Ross ◽  
Jason T Lee ◽  
Wei Zhou ◽  
...  
Keyword(s):  
Atherosclerotic Plaque ◽  
Small Angle ◽  
Collagen Fibril ◽  
Soft Tissues ◽  
Plaque Rupture ◽  
Fibrous Tissue ◽  
Building Blocks ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Abstract Atherosclerotic plaques can gradually develop in certain arteries. Disruption of fibrous tissue in plaques can result in plaque rupture and thromboembolism, leading to heart attacks and strokes. Collagen fibrils are important tissue building blocks and tissue strength depends on how fibrils are oriented. Fibril orientation in plaque tissue may potentially influence vulnerability to disruption. While X-ray scattering has previously been used to characterize fibril orientations in soft tissues and bones, it has never been used for characterization of human atherosclerotic plaque tissue. This study served to explore fibril orientation in specimens from human plaques using small angle X-ray scattering. Plaque tissue was extracted from human femoral and carotid arteries, and each tissue specimen contained a region of calcified material. 3D collagen fibril orientation was determined along scan lines that started away from and then extended towards a given calcification. At locations several millimeters or more from a calcification, fibrils were found to be oriented predominantly in the circumferential direction of the plaque tissue. However, in a number of cases, the dominant fibril direction changed markedly near a calcification, from circumferential to longitudinal. Further study is needed to elucidate how these fibril patterns may change plaque tissue behavior.

scholarly journals Grazing-incidence small-angle X-ray scattering study of correlated lateral density fluctuations in W/Si multilayers

2019 ◽  
Vol 75 (2) ◽  
pp. 342-351 ◽  
Author(s):  
K. V. Nikolaev ◽  
S. N. Yakunin ◽  
I. A. Makhotkin ◽  
J. de la Rie ◽  
R. V. Medvedev ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Small Angle ◽  
Average Distance ◽  
Grazing Incidence ◽  
Density Fluctuations ◽  
X Ray ◽  
X Ray Scattering ◽  
Scanning Transmission ◽  
Average Size ◽  
Ray Scattering

A structural characterization of W/Si multilayers using X-ray reflectivity (XRR), scanning transmission electron microscopy (STEM) and grazing-incidence small-angle X-ray scattering (GISAXS) is presented. STEM images revealed lateral, periodic density fluctuations in the Si layers, which were further analysed using GISAXS. Characteristic parameters of the fluctuations such as average distance between neighbouring fluctuations, average size and lateral distribution of their position were obtained by fitting numerical simulations to the measured scattering images, and these parameters are in good agreement with the STEM observations. For the numerical simulations the density fluctuations were approximated as a set of spheroids distributed inside the Si layers as a 3D paracrystal (a lattice of spheroids with short-range ordering but lacking any long-range order). From GISAXS, the density of the material inside the density fluctuations is calculated to be 2.07 g cm−3 which is 89% of the bulk value of the deposited layer (2.33 g cm−3).

Structural Evolution of Ag–Co and Ag–Ni Alloys Studied by Anomalous Small-Angle X-ray Scattering

1998 ◽  
Vol 31 (5) ◽  
pp. 783-788 ◽  
Author(s):  
C. Revenant-Brizard ◽  
J. P. Simon ◽  
J. R. Regnard ◽  
I. Manzini ◽  
B. Rodmacq
Keyword(s):  
Small Angle ◽  
Magnetic Particles ◽  
Average Distance ◽  
Three Dimensional ◽  
Structural Evolution ◽  
Anomalous Scattering ◽  
Magnetic Element ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

The structural evolution of co-sputtered Ag–20 (and 35) at.% Co and Ag–20 (and 35) at.% Ni was studied by anomalous small-angle X-ray scattering in the as-deposited state and after different anneals for 10 min at 573, 623 and 723 K. Anomalous scattering was used to separate the part of the scattering signal due to the transition metal particles from the signal of other heterogeneities. Strong segregation, involving about two-thirds of the Co (or Ni) atoms, already exists for the as-deposited state. After a 573 K anneal, the phases (Ag matrix and Co or Ni well defined particles) have almost reached equilibrium,i.e.complete immiscibility. Most of the magnetic particles are three dimensional with an average radius of 5–25 Å and the average distance between the particles varies from 17 to 110 Å, depending on the magnetic element and its concentration, and on the annealing conditions. The size distribution does not correspond to that of usual coarsening, but becomes broader after extended annealing. This is probably due to heterogeneous precipitation at grain boundaries of the Ag matrix.

A small-angle X-ray scattering study of the isotropic and nematic phases of V

2000 ◽  
Vol 2 (2) ◽  
pp. 191 ◽  
Author(s):  
O. Pelletier ◽  
C. Bourgaux ◽  
O. Diat ◽  
P. Davidson ◽  
J. Livage
Keyword(s):  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Nematic Phases ◽  
Ray Scattering

Small-Angle X-Ray Scattering Study on PVA/Fe3O4 Magnetic Hydrogels

NANO ◽  
2016 ◽  
Vol 11 (03) ◽  
pp. 1650027 ◽  
Author(s):  
Sunaryono ◽  
Ahmad Taufiq ◽  
Edy Giri Rahman Putra ◽  
Atsushi Okazawa ◽  
Isao Watanabe ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Small Angle ◽  
Lognormal Distribution ◽  
Quantum Interference ◽  
Average Distance ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Structural Dimensions ◽  
Ray Scattering

A synchrotron small-angle X-ray scattering (SAXS) study on PVA/Fe3O4 magnetic hydrogels has been performed to investigate the effect of clustering on their magnetic properties. The hydrogels were prepared through freezing–thawing (F–T) processes. The structure, morphology and magnetic properties of magnetite (Fe3O4) nanoparticles (NPs) were investigated using X-ray diffractometry (XRD), transmission electron microscopy (TEM) and a superconducting quantum interference device (SQUID) magnetometer, respectively. In this study, SAXS data were used to reveal the structural dimensions of the magnetite and its distribution in the polymer-rich PVA and magnetic hydrogels. As calculated using the Beaucage and Teubner–Strey models, the average of the structural dimensions of the PVA hydrogels was 3.9[Formula: see text]nm (crystallites), while the average distance between crystallites was approximately 18[Formula: see text]nm. Further analysis by applying a two-lognormal distribution showed that the magnetite NPs comprised secondary particles with a diameter of 9.6[Formula: see text]nm that were structured by primary particles ([Formula: see text][Formula: see text]3.2[Formula: see text]nm). A two-lognormal distribution function has also been used in describing the size distributions of magnetite NPs in magnetic hydrogels. The clusters of magnetite NPs in the magnetic hydrogels are significantly reduced from 30.4[Formula: see text]nm to 12.8[Formula: see text]nm with decreasing concentration of the NPs magnetite from 15[Formula: see text]wt.% to 1[Formula: see text]wt.%. The saturation magnetization values of the magnetite NPs, the 15% and 1% magnetic hydrogels were 34.67[Formula: see text]emu/g, 6.52[Formula: see text]emu/g and 0.37[Formula: see text]emu/g, respectively.

A small-angle X-ray scattering study of the isotropic and nematic phases of V2O5 suspensions

2000 ◽  
Vol 2 (2) ◽  
pp. 191-198 ◽  
Author(s):  
O. Pelletier ◽  
C. Bourgaux ◽  
O. Diat ◽  
P. Davidson ◽  
J. Livage
Keyword(s):  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Nematic Phases ◽  
Ray Scattering

scholarly journals Structural Investigation of Oat Protein Isolate in Aqueous Medium by using Synchrotron Small-angle X-ray Scattering

2020 ◽  
Author(s):  
Ji Li ◽  
Qingrong Huang
Keyword(s):  
Aqueous Medium ◽  
Small Angle ◽  
Second Virial Coefficient ◽  
Pair Potential ◽  
Protein Isolate ◽  
Small Scale ◽  
X Ray ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Ray Scattering

AbstractOat protein isolate (OPI) is among the plant proteins with valuable functionalities (e.g. emulsification) during daily supplement intake. Understanding their structures helps to manipulate oat proteins at small scale, which enables the appropriate deployment of their functions. Based upon such understanding, the molecular structure of oat protein isolate (OPI) in aqueous medium was investigated by synchrotron small-angle X-ray scattering (SAXS), and this study allows a structural reconstitution of OPI in aqueous medium. Besides, this SAXS study is complimentary to the previous study (Liu et al. J. Agric. Food Chem. 2009, 57, 4552–4558)1. From form factor fitting, we confirmed that OPI aqueous solutions at low concentrations (0.3~2 mg/mL) obtained a disk conformation (41.4×41.4×10.2 Å3). Once protein concentration increased to 5 mg/mL and 10 mg/mL, the individual disk proteins formed large-dimensional rodlike aggregates, which was evidenced by the analyses of effective structure factor and pair distribution function (PDF). Based on the PDF results, the ab initio models of OPI particles at low concentrations (0.3 mg/mL to 2.0 mg/mL) were restored by using GASBOR algorithm. Finally, we found that weak attraction between OPI particles occurred, which was verified by second virial coefficient and pair potential.

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