Search results for " X-ray scattering"
showing 10 items of 154 documents
On the Role of Extensional Flow in Morphology and Property Modifications of MWCNT/Polyamide-Based Fibers
2011
Unfilled and MWCNT-filled PA fibers are prepared and the effect of the extensional flow on their mechanical performance and morphological variations is investigated. Morphological analyses using SEM, TEM, and SAXS suggest a stronger orientation of the MWCNTs along the fiber direction with increasing extensional flow. A particular MWCNT bundle formation in the PA drawn nanocomposite fibers is observed for the first time, and a pull-out of the central nanotube in some bundles is noted. The maintenance of the "shish-kebab" structure upon extensional flow is responsible for the mechanical improvements and dimensional stability in MWCNT-filled PA fibers.
Combination of acoustic levitation with small angle scattering techniques and synchrotron radiation circular dichroism. Application to the study of p…
2016
Abstract Background The acoustic levitation technique is a useful sample handling method for small solid and liquids samples, suspended in air by means of an ultrasonic field. This method was previously used at synchrotron sources for studying pharmaceutical liquids and protein solutions using x-ray diffraction and small angle x-ray scattering (SAXS). Methods In this work we combined for the first time this containerless method with small angle neutron scattering (SANS) and synchrotron radiation circular dichroism (SRCD) to study the structural behavior of proteins in solutions during the water evaporation. SANS results are also compared with SAXS experiments. Results The aggregation behavi…
Recent developments in ultra–small angle neutron scattering techniques
1998
Abstract There is growing interest in the (nano−) scale structural analysis of condensed matter to study synthetic and biological polymers, colloids, porous materials, etc. Over the past two decades, small–angle neutron scattering (SANS), based on the availability of high fluxes of cold neutrons (wavelengths 4−20 A), has proven to be one of the most important tools for such investigations. This success is due to a fortuitous combination of several factors of cold neutrons: high bulk penetrating power, the ability to manipulate local scattering amplitudes via isotopic labeling or an appropriate choice of solvent (contrast variation), minimal radiation damage, and small absorption for most el…
On the use of grazing-incidence small-angle X-ray scattering (GISAXS) in the morphological study of ion-implanted materials.
2004
Grazing-incidence small-angle X-ray scattering has become a widely used technique for the morphological analysis of surface systems. Here it is show how this technique can be applied to a buried system, like metallic clusters in glass obtained by ion implantation. The optimization of the data-collection geometry is described as well as the details of the quantitative data analysis. An experimental example on Cu + Au-implanted glasses shows the potentiality of the technique.
Nucleation and crystal growth in a suspension of charged colloidal silica spheres with bi-modal size distribution studied by time-resolved ultra-smal…
2014
A suspension of charged colloidal silica spheres exhibiting a bi-modal size distribution of particles, thereby mimicking a binary mixture, was studied using time-resolved ultra-small-angle synchrotron X-ray scattering (USAXS). The sample, consisting of particles of diameters d(A) = (104.7 ± 9.0) nm and d(B) = (88.1 ± 7.8) nm (d(A)/d(B) ≈ 1.2), and with an estimated composition A(0.6(1))B(0.4(1)), was studied with respect to its phase behaviour in dependance of particle number density and interaction, of which the latter was modulated by varying amounts of added base (NaOH). Moreover, its short-range order in the fluid state and its eventual solidification into a long-range ordered colloidal…
The structural properties of soda–silicate sols and of the lime–soda–silicate gel formation
1999
Abstract Alkaline silicate solutions were prepared with varying SiO 2 –Na 2 O ratios, Rm=[SiO 2 ]/[Na 2 O]=2 or 3, with a constant silica concentration equal to 1.5 M. The structure and the number fraction of different silicate molecular species present in the solutions were classically determined for molar ratio Rm=2 using 29 Si nuclear magnetic resonance ( 29 Si NMR). In the case of the sample with Rm=3, for which no NMR data was available, we used small-angle X-ray scattering (SAXS) experiments to get this information. The SAXS model was previously tested with Rm=2 silicate solution. When Ca ++ is added to alkaline silicate solutions, a gel is obtained under well-defined conditions. The …
Structural and electrochemical investigation on re-cast Nafion membranes for polymer electrolyte fuel cells (PEFCs) application
2006
Abstract Starting from a 5 wt% ion power Nafion® solution and dissolving the dry residue in a suitable solvent (10 wt% solution in dimethylacetammide), re-cast Nafion films were developed for polymer electrolyte fuel cells (PEFCs) application. The used Doctor-Blade casting technique allowed to prepare scaled-up membranes comparable to the commercial Nafion ones with good mechanical resistance, thickness homogeneity and an excellent reproducibility. The differences between the re-cast membrane nanostructure and that of the commercial Nafion were investigated by synchrotron small-angle X-ray scattering. The obtained re-cast membrane shows at ambient conditions a semi-crystalline structure wit…
Phase Transitions in Prequenched Mesomorphic Isotactic Polypropylene during Heating and Annealing Processes As Revealed by Simultaneous Synchrotron S…
2011
Time-resolved simultaneous synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) technique was used to investigate the phase transitions in prequenched mesomorphic isotactic polypropylene (iPP) samples during heating and annealing processes, respectively. For the heating process, it is shown that the mesomorphic-to-monoclinic phase transition is relatively faster for the mesomorphic iPP sample obtained with the high quenching rate than that with the low quenching rate. For the former, the stability of α-monoclinic crystals formed during heating is relatively higher. As for the annealing process, WAXD and SAXS data illustrate that the higher the annealing te…
Optimization of Innovative Three-Dimensionally-Structured Hybrid Vesicles to Improve the Cutaneous Delivery of Clotrimazole for the Treatment of Topi…
2019
New three-dimensionally-structured hybrid phospholipid vesicles, able to load clotrimazole in a high amount (10 mg/mL), were obtained for the first time in this work by significantly reducing the amount of water (&le
Myoglobin embedded in saccharide amorphous matrices: water-dependent domains evidenced by small angle X-ray scattering
2010
We report Small Angle X-ray Scattering (SAXS) measurements performed on samples of carboxy-myoglobin (MbCO) embedded in low-water trehalose glasses. Results showed that, in such samples, "low-protein" trehalose-water domains are present, surrounded by a protein-trehalose-water background; such finding is supported by Infrared Spectroscopy (FTIR) measurements. These domains, which do not appear in the absence of the protein and in analogous sucrose systems, preferentially incorporate the incoming water at the onset of rehydration, and disappear following large hydration. This observation suggests that, in organisms under anhydrobiosis, analogous domains could play a buffering role against th…