Fractal aggregates of lanthanide-doped Y2O3 nanoparticles obtained by propellant synthesis

2001 ◽  
Vol 16 (1) ◽  
pp. 146-154 ◽  
Author(s):  
Stefano Polizzi ◽  
Giuliano Fagherazzi ◽  
Marino Battagliarin ◽  
Marco Bettinelli ◽  
Adolfo Speghini
Keyword(s):  
Building Blocks ◽  
Compositional Gradient ◽  
Fractal Aggregates ◽  
Scaling Properties ◽  
X Ray ◽  
Lattice Disorder ◽  
Average Value ◽  
X Ray Scattering ◽  
20 Nm ◽  
Ray Scattering

Y2-xLnxO3 (Ln 4 Ce, Pr, Nd, Eu, Gd, Ho, and Er) powders obtained by propellant synthesis have been characterized using small-angle x-ray scattering, wide-angle x-ray scattering, and transmission and scanning electron microscopy. All the samples showed a very porous, open microstructure with fractal scaling properties. The building blocks of the fractal aggregates are nanocrystallites of lanthanide-doped Y2O3, with variations in the cubic lattice constant proportional to the composition of the solid solution and to the lanthanide ionic radius. The particles had a narrow distribution of sizes with an average value in the 20–50 nm range. They are made of a core of 10–20 nm, consisting of almost perfectly ordered crystals and a “fuzzy” layer, characterized by either a growing lattice disorder or by a compositional gradient. From this dimension, up to at least 200 nm, the particle aggregate is a mass fractal with a fractal dimension, DMf, in the 1.6–2.0 range.

scholarly journals In situanomalous small-angle X-ray scattering from metal particles in supported-metal catalysts. II. Results

2005 ◽  
Vol 38 (2) ◽  
pp. 324-332 ◽  
Author(s):  
H. Brumberger ◽  
D. Hagrman ◽  
J. Goodisman ◽  
K. D. Finkelstein
Keyword(s):  
Small Angle ◽  
Platinum Metal ◽  
Metal Particles ◽  
Metal Catalyst ◽  
Supported Metal Catalysts ◽  
X Ray ◽  
Average Value ◽  
X Ray Scattering ◽  
Supported Metal ◽  
Ray Scattering

Information about the metal phase in a supported-metal catalyst can be obtained using anomalous small-angle X-ray scattering (ASAXS). The difference between the scattering profiles for SAXS at two different wavelengths near the metal's absorption edge is essentially the scattering of the metal alone. Novelin situASAXS measurements are made on mordenite impregnated with platinum metal while the temperature and composition of gas in the sample cell are changed. Measurements are made 62 times during treatment of the catalyst. The metal particles are assumed to be randomly distributed spheres withN(R)dR= number of spheres with radii betweenRandR+ dR. It is found thatN(R) is always a monotonically decreasing function ofR, and that the average value ofR, obtained fromN(R), decreases by a factor of two over the time (approximately 6 h) for which the system is observed.

Small-Angle X-ray Scattering Study of the Morphology of Carbon Black Mass Fractal Aggregates in Polymeric Composites

Langmuir ◽  
2000 ◽  
Vol 16 (13) ◽  
pp. 5588-5592 ◽  
Author(s):  
Thomas P. Rieker ◽  
Manuela Hindermann-Bischoff ◽  
Françoise Ehrburger-Dolle
Keyword(s):  
Carbon Black ◽  
Small Angle ◽  
Polymeric Composites ◽  
Fractal Aggregates ◽  
X Ray ◽  
X Ray Scattering ◽  
Mass Fractal ◽  
Scattering Study ◽  
Ray Scattering

A superbright X-ray laboratory microsource empowered by a novel restoration algorithm

2012 ◽  
Vol 45 (6) ◽  
pp. 1228-1235 ◽  
Author(s):  
Liberato De Caro ◽  
Davide Altamura ◽  
Fabio Alessio Vittoria ◽  
Gerardina Carbone ◽  
Fen Qiao ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Grazing Incidence ◽  
Building Blocks ◽  
Signal To Noise ◽  
Fringe Visibility ◽  
X Ray ◽  
X Ray Scattering ◽  
Restoration Algorithm ◽  
Noise Ratio ◽  
Ray Scattering

The properties of nanoscale materials vary with the size and shape of the building blocks, which can be measured by (grazing-incidence) small-angle X-ray scattering along with the mutual positions of the nanoparticles. The accuracy in the determination of such parameters is dependent on the signal-to-noise ratio of the X-ray scattering pattern and on the visibility of the interference fringes. Here, a first-generation-synchrotron-class X-ray laboratory microsource was used in combination with a new restoration algorithm to probe nanoscale-assembled superstructures. The proposed algorithm, based on a maximum likelihood approach, allows one to deconvolve the beam-divergence effects from data and to restore, at least partially, missing data cut away by the beam stopper. It is shown that the combination of a superbright X-ray laboratory microsource with the data-restoring method allows a virtual enhancement of the instrument brilliance, improving signal-to-noise ratio and fringe visibility and reaching levels of performance comparable to third-generation synchrotron radiation beamlines.

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.

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 In situanomalous small-angle X-ray scattering from metal particles in supported-metal catalysts. I. Theory

2005 ◽  
Vol 38 (1) ◽  
pp. 147-151 ◽  
Author(s):  
H. Brumberger ◽  
D. Hagrman ◽  
J. Goodisman ◽  
K. D. Finkelstein
Keyword(s):  
Small Angle ◽  
Platinum Metal ◽  
Metal Particles ◽  
Metal Catalyst ◽  
Supported Metal Catalysts ◽  
X Ray ◽  
Average Value ◽  
X Ray Scattering ◽  
Supported Metal ◽  
Ray Scattering

A supported-metal catalyst can be considered as a mixture of three homogeneous phases: support, void and metal. Information about the metal phase alone can be obtained using anomalous small-angle X-ray scattering (ASAXS), which requires measuring the SAXS for two different wavelengths near the metal's absorption edge. Herein, the conditions that must be obtained so that the difference between the two scattering profiles gives the scattering of the metal alone are presented. In a following contribution, the analysis will be applied toin situASAXS measurements made on mordenite impregnated with platinum metal while the temperature and composition of gas in the sample cell are changed. The metal particles are assumed to be randomly distributed spheres withN(R)dRbeing the number of spheres with radii betweenRandR+ dR. FromN(R) one can obtain the average value ofR.

scholarly journals Hierarchical Assembly Pathways of Spermine Induced Tubulin Conical-Spiral Architectures

2019 ◽  
Author(s):  
Raviv Dharan ◽  
Asaf Shemesh ◽  
Abigail Millgram ◽  
Yael Levi-Kalisman ◽  
Israel Ringel ◽  
...  
Keyword(s):  
Self Assembly ◽  
Hexagonal Lattice ◽  
Building Blocks ◽  
Time Resolved ◽  
X Ray ◽  
Hierarchical Assembly ◽  
Research Fields ◽  
X Ray Scattering ◽  
Assembly Pathways ◽  
Ray Scattering

<p>Tubulin dimers are flexible entities serving as building blocks for construction of cellular polymers essential for the cytoskeleton. The conformational state of the dimer dictates the exact formation of assembly and can be regulated by cellular factors including spermine. Using solution X-ray scattering and cryo-TEM measurements we studied the behavior of tubulin assembly in the presence of millimolar spermine concentrations. The results discovered novel structural architectures of tubulin polymers and revealing fascinating hierarchical self-associations based on unique tubulin conical-spiral (TCS) subunits.</p> <p> </p> <p>We followed the assembly pathways of tubulin dimers with different spermine concentrations, from milliseconds to days, and discovered multiple phase transitions with increasing spermine concentration. At 1 mM spermine, tubulin assembled into tubulin helical-pitch (THP) structures, resembling tubulin-rings. Above 1.5 mM spermine, tubulin assembled into TCS architectures. TCS is a unique tubulin assembly, serving as a new building block subunit. TCS assembled into different architectures . The predominant structure was TCS-tube (TCST) that further assembled in a remarkable antiparallel orientation which formed bundles with 2D-cubic and unique quasi-2D hexagonal lattices. Each TCST in the quasi-2D hexagonal lattice was surrounded by four antiparallel TCSTs and two parallel TCSTs. All the above assemblies have never been observed before. At higher spermine concentrations, tubulin assembled into twisted inverted tubulin tubules (ITTs).</p> <p>Here we also show for the first time, the hierarchical assembly pathways from tubulin dimer to each of the above structures, using time-resolved experiments with millisecond temporal resolution. We discovered that the structures that formed at low spermine concentrations were transient precursors of the structures formed at higher spermine concentrations. </p> <p> </p> <p>The results are based on high quality cryo-TEM images, cutting edge synchrotron solution X-ray scattering measurements and state-of-the-art data analysis, using our home developed groundbreaking analysis software, D+. </p> <p>The findings can be relevant to a broad research fields including studies which explore different arrangements of the cytoskeletal network, or studies exploring the attraction forces between proteins that dictate their mode of assembly and molecular designed self-assembly of natural and/or synthetic analogous.</p>

scholarly journals Wide Angle X-Ray Scattering to Study the Atomic Structure of Polymeric Fibers

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 274 ◽  
Author(s):  
Teresa Sibillano ◽  
Alberta Terzi ◽  
Liberato De Caro ◽  
Massimo Ladisa ◽  
Davide Altamura ◽  
...  
Keyword(s):  
Textile Industry ◽  
Type I Collagen ◽  
Functional Materials ◽  
Building Blocks ◽  
Type I ◽  
Wide Angle ◽  
X Ray ◽  
Fiber Assembly ◽  
X Ray Scattering ◽  
Ray Scattering

Natural fibrillar-like macromolecules find applications in several fields, thanks to their peculiar features, and are considered perfect building blocks for natural and artificial functional materials. Indeed, fibrous proteins (such as collagen or fibroin) are commonly used in scaffold fabrication for biomedical applications, due to the high biophysical similarity with the extracellular matrix (ECM) which stimulates tissue regeneration. In the textile industry, cellulose-based fabrics are widely used in place of cotton and viscose, which both have sustainability issues related to their fabrication. With this in mind, the structural characterization of the materials at molecular scale plays a fundamental role in gaining insight into the fiber assembly process. In this work, we report on three fibers of research interest (i.e., type I collagen, silk fibroin extracted from Bombyx mori, and cellulose) to show the power of wide-angle X-ray scattering to characterize both intra- and intermolecular parameters of fibrous polymers. The latest possibilities offered in the X-ray scattering field allow one to study fibers at solid state or dispersed in solutions as well as to perform quantitative scanning X-ray microscopy of tissues entirely or partially made by fibers.

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

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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