Papers by Keyword: Small Angle X-Ray Scattering

Abstract: We study stable stable transparent monolithic nanocomposites based on the silica matrix doped with CdS nanoparticles (NPs) of different nature. The first kind of nanocomposite was obtained by nucleation and growth of nanoparticles in glass matrix during heat treatment. The second nanocomposite was obtained by immobilization of pre-made nanoparticles into silica gel matrix. This work is focused on characterization of the nanocomposites in the submicron scale by using electron microscopy and small angle x-ray scattering techniques. Experimental results show that both types of nanocomposites have homogeneous distribution of quantum dots. Form-factor and average size of CdS NPs depend on the synthesis technique

Abstract: Lipid-based formulations (LBF) including self-emulsifying drug delivery system have been used to improve drug dissolution and bioavailability by avoiding rate-limiting step during dissolution of poorly water-soluble drugs. This study was aimed to investigate the behavior of lipid-based formulations upon dilution in aqueous media by using small angle X-ray scattering (SAXS). LBF is composed of oil (caprylic/capric glyceride), surfactants (polyoxyl 35 castor oil or polyoxyl 40 hydrogenated castor oil), and co-solvent (diethylene glycol monoethyl ether) at a weight ratio of 1:1:8. Nifedipine, a poorly water-soluble drug, was used as a model drug. A 100-fold dilution of the LBF in aqueous media (i.e., simulated gastric fluid USP without pepsin (SGF) and distilled water) resulted in nanosized emulsion (less than 200 nm). The selected formulations were diluted in aqueous media at various ratios (e.g., 0.01, 0.02, 0.04, 0.06, 0.09, 0.11, 0.18, 0.25, 0.67, 1.5, 4, 99, 199 and 300 folds) and then, after equilibrium, monitored by SAXS in order to observe the surfactant rearrangement. The results from SAXS scattering curves (q of 0.027-0.980 Å^-1) demonstrated that a lamellar phase or liquid crystalline was not formed upon dilution. The emulsions were formed without the ordered structure.

Abstract: Pure TiO₂, Ce-doped and Ce/Si-codoped TiO₂ nanoparticles with different Ce contents were synthesized by using a sol-gel-hydrothermal method. The as-synthesized samples were annealed at 400 °C. Their crystallization was investigated by Raman spectroscope. The result showed that Ce-doping and Ce-Si codoping decreased the crystallization. The interfacial and fractal properties were investigated by synchrotron radiation small angle X-ray scattering (SAXS). The results indicated that Ce-doping induced the Porod negative deviation, and the fractal properties showed TiO₂ nanoparticles codoped by Ce-Si were rougher than these of the pure TiO₂ and Ce-doped TiO₂. This rough surface of the nanoparticles was helpful to improve the photocatalytic activity.

Abstract: A small angle X-ray scattering experiment was performed on ferrihydrite nanoparticles produced by bacterium Klebsiella oxytoca. Structural investigations of ultrasonicated samples of different concentrations of water-dispersed particles were performed. Model calculations and fitting procedures revealed scattering objects of an elongated shape of 6.73±0.16 nm radius of gyration.

Abstract: An investigation has been carried out on the CSP low carbon steel after cold-rolling and annealing of the same thin slab was investigated by chemical phase analysis and SAXS method that as well as high resolution TEM analysis. It was found that the amount of nano-scaled MC particles is less than that of nano-scaled M3C particles by 160 times after the annealing, reduces is 26 times under two conditions, its grain-size distribution frequency highest is the 10~18nm size. But in the annealing process, the particles accumulated to grow up. Further analysis also indicated that particles distribution uniformity of cold-rolling is better than that of annealing condition. This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Abstract: Composites have achieved much attention because of their excellent qualities. Core-shell γ-Fe₂O₃/Au nanoparticles were prepared by chemical reduction. Their optical properties and morphology were characterized by UV-visible spectrum (UV-vis), X-ray diffraction (XRD) and Transmission Electronic Microscopy (TEM). Furthermore, the average particle size and interface structure were also analyzed using small angle X-ray scattering (SAXS).

Abstract: The precipitation sequences in two Al-Li-Cu alloys with similar Cu concentration and different Li concentration have been studied by small-angle X-ray scattering using synchrotron light, in combination with transmission electron microscopy. The sequence ranges from phases formed during natural ageing to the hardening ones obtained by artificial ageing at 155°C. It is found that the low Li-containing alloy shows first Cu-rich clusters at room temperature followed by T₁ precipitates, while the high Li-containing alloy shows first δ’-Al₃Li precipitates and then formation of T1 phase in coexistence with the δ’. The influence of alloy composition on T₁ nucleation and growth kinetics is discussed in light of the experimental results.

Abstract: Partially crystalline cellulose microfibrils are wound helically around the longitudinal axis of the wood cell. A method is presented for the measurement, using small-angle X-ray scattering (SAXS), of the microfibril angle, (MFA) and the associated standard deviation for the cellulose microfibrils in the S2 layer of the cell walls of Acacia mangium wood. The length and orientation of the microfibrils of the cell walls in the irradiated volume of the thin samples are measured using SAXS and scanning electron microscope, (SEM). The undetermined parameters in the analysis are the MFA, (M) and the standard deviation (σФ) of the intensity distribution arising from the wandering of the fibril orientation about the mean value. Nine separate pairs of values are determined for nine different values of the angle of the incidence of the X-ray beam relative to the normal to the radial direction in the sample. The results show good agreement. The curve distribution of scattered intensity for the real cell wall structure is compared with that calculated with that assembly of rectangular cells with the same ratio of transverse to radial cell wall length. It is demonstrated that for β = 45°, the peaks in the curve intensity distribution for the real and the rectangular cells coincide. If this peak position is Ф45, Then the MFA can be determined from the relation M = tan-1 (tan Ф45 / cos 45°), which is precise for rectangular cells.

Abstract: Structure of nonionic surfactant diglycerol monolaurate (C12G2) reverse micelles in squalene at different surfactant concentrations and temperatures is presented. For the structural characterization of the micelles, small-angle X-ray scattering (SAXS) technique is used. The scattering data is evaluated by virtually model free generalized indirect Fourier transformation (GIFT) method. GIFT analysis of the SAXS data has shown the clear evidence on the formation of rod-like micelles in the C12G2/squalene system at higher temperatures. At fixed temperature, increasing surfactant concentration induces one-dimensional micellar growth; the maximum length of the micelles increases with concentration, but the micellar cross-section remains essentially the same. On the other hand, at fixed concentration, the maximum length of the micelles decreases with the rise of temperature. It is found that the length of micelles decreases by ~ 35% keeping cross-section diameter unchanged with the rise of temperature from 60 to 80 °C in 5 wt% wt% C12G2/squalene system.

Abstract: GKSS is currently investing heavily into new beamlines at DESY in Hamburg, Germany. After the completed installation of the wiggler beamline HARWI II at DORIS III GKSS is now building two new undulator beamlines at the new PETRA III storage ring. The High Energy Materials Science Beamline (HEMS) will allow high resolution diffraction experiments using samples and sample environments with masses up to 1 t, 3DXRD measurements, and high-energy micro-tomography experiments. The Imaging Beamline (IBL) will provide a nano-tomography as well as a micro-tomography station for X-ray energies up to 50 keV. Examples of typical experiments in the field of residual stress analysis, micro-tomography, and high-energy small-angle X-ray scattering will be given.