Combined Electrospray-Scanning Mobility Particle Sizer (ES-SMPS) and Time-Resolved Synchrotron Radiation-Small-Angle X-ray Scattering (SR-SAXS) Investigation of Colloidal Silica Aggregation. Part II. Influence of Aggregation Initiator on Gel Stability

2011 ◽  
Vol 115 (31) ◽  
pp. 9547-9555 ◽  
Author(s):  
Ann-Cathrin J. H. Johnsson ◽  
M. Caterina Camerani ◽  
Zareen Abbas
1990 ◽  
Vol 205 ◽  
Author(s):  
Haydn Chen ◽  
M.S. Yu ◽  
H. Okuda ◽  
M. Tanaka ◽  
K. Osamura

AbstractStructure change during the reversion process in an Al−12at.%Li alloy above the metastable δ′ solvus was investigated using a time-resolved small-angle x-ray scattering technique with synchrotron radiation. Results showed that the reversion process started after a short incubation time and that the growth of the stable δ phase began before completion of the δ′ dissolution. The radius of gyration of the second phase particles showed little change in the initial stage of reversion, then increased with time, suggesting the presence of diffuse interfaces between the dissolving δ′ particles and the matrix. It is suggested that the undissolved δ′ particles serve as the nuclei of the more stable δ precipitates, which continue to grow with their radii of gyration showing a parabolic power law in the early stage of growth followed by the familiar coarsening kinetics.


1997 ◽  
Vol 30 (5) ◽  
pp. 816-821 ◽  
Author(s):  
W. Bras ◽  
A. J. Ryan

The high X-ray intensity of synchrotron radiation (SR) beamlines makes it possible to perform time-resolved small-angle X-ray scattering (SAXS) experiments. The information that can be obtained by collecting the wide-angle diffraction pattern simultaneously not only increases the information content of an experiment but also increases the reliability of the time-correlations between SAXS and WAXS (wide-angle X-ray scattering) patterns. This is a great advantage for experiments with a time resolution below the level of 1 s per frame. With appropriate instrumentation, this is a time domain that is routinely accessible for a large group of research fields. This has had a considerable impact upon the understanding of fundamental aspects of phase transformations. Not only fundamental processes but also more applied fields have benefited from these developments. In polymer research this has led to a situation in which it has become possible to simulate materials processing techniques on-line. With the advent of third-generation synchrotron-radiation sources (e.g. ESRF, APS, Spring8), it has become possible to develop SAXS/WAXS beamlines that will open up new research opportunities by utilizing the higher intensity, the tuneability and the higher collimation offered by these SR sources. However, some of the instrumentation limits in detector and sample environments that have become apparent in research on second-generation synchrotron-radiation sources still have not been appropriately addressed, which means that in some fields it will not be possible to take full advantage of the superior X-ray beam quality that third-generation synchrotrons can offer. A way in which these instrumentation limits can be overcome is discussed, and the instrumentation for a new bending-magnet beamline at the ESRF is used as an example.


2019 ◽  
Author(s):  
Hao Wu ◽  
Jeffrey Ting ◽  
Siqi Meng ◽  
Matthew Tirrell

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.


2014 ◽  
Vol 47 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Zoltán Varga ◽  
András Wacha ◽  
Attila Bóta

Time-resolved synchrotron small-angle X-ray scattering (SAXS) was used to study the structural changes during the osmotic shrinkage of a pharmacologically relevant liposomal drug delivery system. Sterically stabilized liposomes (SSLs) with a diameter of 100 nm and composed of hydrogenated soy phosphocholine, cholesterol and distearoyl-phosphoethanolamine-PEG 2000 prepared in a salt-free buffer were mixed with a buffered 0.3 MNaCl solution using a stopped flow apparatus. The changes in the liposome size and the bilayer structure were followed by using SAXS with a time resolution of 20 ms. A linear decrease in liposome size is observed during the first ∼4 s of the osmotic shrinkage, which reveals a water permeability value of 0.215 (15) µm s−1. The change in the size of the liposomes upon the osmotic shrinkage is also confirmed by dynamic light scattering. After this initial step, broad correlation peaks appear on the SAXS curves in theqrange of the bilayer form factor, which indicates the formation of bi- or oligolamellar structures. Freeze-fracture combined with transmission electron microscopy revealed that lens-shaped liposomes are formed during the shrinkage, which account for the appearance of the quasi-Bragg peaks superimposed on the bilayer form factor. On the basis of these observations, it is proposed that the osmotic shrinkage of SSLs is a two-step process: in the initial step, the liposome shrinks in size, while the area/lipid adapts to the decreased surface area, which is then followed by the deformation of the spherical liposomes into lens-shaped vesicles.


Polymer ◽  
2001 ◽  
Vol 42 (21) ◽  
pp. 8965-8973 ◽  
Author(s):  
Zhi-Gang Wang ◽  
Xuehui Wang ◽  
Benjamin S. Hsiao ◽  
Saša Andjelić ◽  
Dennis Jamiolkowski ◽  
...  

2012 ◽  
Vol 45 (3) ◽  
pp. 307-312 ◽  
Author(s):  
Takamichi Shinohara ◽  
Tomoko Shirahase ◽  
Daiki Murakami ◽  
Taiki Hoshino ◽  
Moriya Kikuchi ◽  
...  

2011 ◽  
Vol 405 (5) ◽  
pp. 1284-1294 ◽  
Author(s):  
Tsuyoshi Konuma ◽  
Tetsunari Kimura ◽  
Shuzo Matsumoto ◽  
Yuji Goto ◽  
Tetsuro Fujisawa ◽  
...  

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