Search results for "Small-angle scattering"
showing 10 items of 66 documents
Laser light scattering and polydispersity of polymers
1977
The application of lasers to light scattering improves the potentials of elastic scattering, especially in the high molecular weight range and enables the technique of inelastic scattering to be used. For elastic light scattering an experimental arrangement and an evaluation method is described which allows, within appropriate molecular weight ranges, the determination of the ratio Mw/Mn from the experimental scattering function with an accuracy down to 0.02. The newer technique of inelastic light scattering yields the coefficient of translational diffusion D. Besides D, the friction coefficient f is also directly accessible. The basic equations are reported, as well as an application to mi…
Light scattering in opal heterojunctions
2006
Light propagation in photonic hetero-crystals, consisting of two opal films with different lattice constants, has been investigated in the realistic regime of weak scattering, when the main light flux is transported by ballistic photons. The light scattering at the photonic bandgap interface is studied in combination with transmission data. The spectra and directionality diagrams of scattered light of single- and hetero-opal films are compared. The rate of decrease of the scattering intensity as a function of the scattering angle has been used to quantify the scattering strength. The anisotropy of the interface scattering is identified by deducing the trajectories of single scattered photon…
Scaling in colloidal crystallization
1994
The process of colloidal crystallization has already been separately investigated by light scattering mearurements of the crystalline order (Bragg peaks) and of long-ranged density fluctuations (small-angle scattering). We present the firstsimultaneous small- and large-angle light scattering experiment. Our measurements have been performed on hard-sphere colloids of different particle densities. We show results for the temporal evolution of crystallization and find two distinct regimes: homogeneous nucleation and diffusion- or reaction-limited growth at early times, followed by ripening of the Lifshitz-Slyozov or Lifshitz-Allen-Cahn type. To our preliminary experience, we can already state …
Hiding in plain view: Colloidal self-assembly from polydisperse populations.
2016
We report small-angle x-ray scattering (SAXS) experiments on aqueous dispersions of colloidal silica with a broad monomodal size distribution (polydispersity 18%, size 8 nm). Over a range of volume fractions the silica particles segregate to build first one, then two distinct sets of colloidal crystals. These dispersions thus demonstrate fractional crystallization and multiple-phase (bcc, Laves AB$_2$, liquid) coexistence. Their remarkable ability to build complex crystal structures from a polydisperse population originates from the intermediate-range nature of interparticle forces, and suggests routes for designing self-assembling colloidal crystals from the bottom-up.
Small angle neutron scattering on periodically deformed polymers
1984
Small angle neutron scattering from periodically deformed samples is a useful extension of the methods presently available for the study of molecular dynamics of polymers. In this paper we describe apparatus that has been used to produce large cyclic deformations at frequencies upto 10 Hz and the principles by which data is collected to give spectra corresponding to different states of strain of the sample. Some data on model polydimethylsiloxane networks is given as an illustration of the value of this technique.
Small-Angle Scattering from Phase-Separated Metallic Alloys: From Experiment to Phase Diagrams
1994
In this paper, phase-separated metallic alloys are described in terms of concentration fluctuations. As a consequence, Small Angle Scattering equations which allow to calculate the entire scattering curve by incorporating particle-particle interference effects on the basis of the Percus-Yevick formalism, are obtained. It is shown that, for Aluminium-Lithium alloys, satisfactory fits of the experimental data can be obtained if it is assumed that Li rich elliptical monodisperse precipitate particles approach each other at average distances which are larger than the sum of the hard-sphere particle radii. It is also shown that a possible ambiguity of this model, within the Percus-Yevick formali…
Flexible Structure of Peptide-Bound Filamin A Mechanosensor Domain Pair 20-21.
2015
Filamins (FLNs) are large, multidomain actin cross-linking proteins with diverse functions. Besides regulating the actin cytoskeleton, they serve as important links between the extracellular matrix and the cytoskeleton by binding cell surface receptors, functioning as scaffolds for signaling proteins, and binding several other cytoskeletal proteins that regulate cell adhesion dynamics. Structurally, FLNs are formed of an amino terminal actin-binding domain followed by 24 immunoglobulin-like domains (IgFLNs). Recent studies have demonstrated that myosin-mediated contractile forces can reveal hidden protein binding sites in the domain pairs IgFLNa18-19 and 20-21, enabling FLNs to transduce me…
Crystal Structure of Human Filamin C Domain 23 and Small Angle Scattering Model for Filamin C 23–24 Dimer
2007
Filamin C is a dimeric, actin-binding protein involved in organization of cortical cytoskeleton and of the sarcomere. We performed crystallographic, small-angle X-ray scattering and analytical ultracentrifugation experiments on the constructs containing carboxy-terminal domains of the protein (domains 23-24 and 19-21). The crystal structure of domain 23 of filamin C showed that the protein adopts the expected immunoglobulin (Ig)-like fold. Small-angle X-ray scattering experiments performed on filamin C tandem Ig-like domains 23 and 24 reveal a dimer that is formed by domain 24 and that domain 23 has little interactions with itself or with domain 24, while the analytical ultracentrifugation …
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…
Low angle neutron scattering of ferritin studied by contrast variation.
1976
Ferritins containing different amounts of iron have been studied by neutron small angle scattering in H 2 O/D 2 O mixtures. Apoferritin has also been studied in solutions of small organic molecules. There is a larger contrast variation in the solutions of small organic molecules than in the corresponding H 2 O/D 2 O experiments from which it may be calculated that I g of apoferritin contains 0·3 g of H 2 O. The solvent composition at zero contrast varies regularly with the iron content of the protein: there is evidence for polydispersity in the iron content of the ferritin used. From analysis of the scattering curves it is concluded that the iron is probably not homogeneously distributed in…