Search results for "small-angle"
showing 10 items of 258 documents
Small angle neutron scattering study of the quaternary structure of haemocyanin of Rapana thomasiana
1996
Abstract Small angle neutron scattering (SANS) experiments were performed on a series of solutions of haemocyanin (Hc) of Rapana thomasiana . In a first series of solutions, by changing the external contrast a model of the molecule that is apparently in disagreement with electron microscopy (EM) measurements was obtained. The apparent disagreement was resolved by performing experiments on a series of variable protein concentration solutions in D 2 O. The physical parameters of the model, extrapolated to zero concentration, are in excellent agreement with the EM results obtained on samples more dilute than those examined with SANS.
The interaction of deoxyribonucleic acid with methyltin(IV) moieties in solution studied by small-angle X-ray scattering, circular dichroism and UV s…
2000
The nature of calf thymus DNA in aqueous solution, in the presence of the organotin(IV) species Sn IV Me 3 , Sn IV Me 2 and Sn IV Me, possibly partly hydrolysed and/or hydrated, was investigated by small-angle X-ray scattering (SAXS), ultraviolet spectroscopy (UV) at different temperatures and circular dichroism (CD). The results are compared with those of previous 119 Sn Mossbauer studies on condensed DNA phases. The effects of tin-phosphate oxygen bonding on the DNA melting profile in DNA-Sn IV Me systems are in agreement with previous reports on DNA-Main Group metal ion interactions. The structure and conformation of the DNA double helix are not influenced by Sn IV Me n species, even in …
Morphology evolution in mesoporous titania block copolymer composite films with increasing Sol-Gel reaction time
2013
A morphology evolution of thin films of titania from spherical mesopores to worm-shaped mesopores was realized by simply varying the sol–gel reaction time from 46 min to 25 h in the quadruple system consisting of polystyrene–block-poly(ethylene oxide) (PS–b-PEO), 1,4-dioxane, concentrated HCl, and titanium tetraisopropoxide (TTIP). Imaging techniques including scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied to investigate the local structure change of the as-prepared, calcined, and UV-degraded composite films. Grazing incidence small angle X-ray scattering (GISAXS) experiments prove that the structure change in local areas is representative of that over the…
Synthesis of a Fullerene[60] Cryptate and Systematic Langmuir-Blodgett and Thin-Film Investigations of Amphiphilic Fullerene Derivatives
1995
The synthesis of the first fullerene cryptate 7 with a sodium ion bound to a benzo[2.2.2]cryptand covalently attached to a methanofullerene[60] is described. The amphiphilic properties of 7 as well as of a variety of other covalent fullerene derivatives with polar functional groups and the ability of these compounds to form Langmuir monolayers at the air-water interface were investigated in a systematic study. Among these derivatives are Diels-Alder adducts of C60 and methanofullerenes, four of which are fullerene C-glycosides. The films at the water surface were characterized by their surface pressure versus molecular area isotherms, compression and expansion cycles, and optical light micr…
The cage elasticity and under-field structure of concentrated magnetic colloids probed by small angle X-ray scattering
2013
International audience; In the present study we probe the bulk modulus and the structure of concentrated magnetic fluids by small angle X-ray scattering. The electrostatically stabilized nanoparticles experience a repulsive interparticle potential modulated by dipolar magnetic interactions. On the interparticle distance length scale, we show that nanoparticles are trapped under-field in oblate cages formed by their first neighbours. We propose a theoretical model of magnetostriction for the field-induced deformation of the cage. This model captures the anisotropic features of the experimentally observed scattering pattern on the local scale in these strongly interacting colloidal dispersions
X-ray scattering studies of the structure of aqueous hydroxy-propylcellulose solutions
1991
X-ray diffraction studies have been undertaken on aqueous solutions of hydroxy propylcellulose (HPC) over a wide range of the scattering vector Q. The experiments revealed only modest differences in local structure on a distance scale ca. 5–300 A despite the fact that they covered concentrations generally interpreted as ranging from the isotropic (35.1 wt %) to the anisotropic liquid crystalline (LC) phase (53.5 wt %). Several models were used to interpret the small-angle scattering data, and each gave similar structural parameters and extrapolated intensities (Q → 0) for both solutions. Peaks were observed with d-spacings ca. 12–17 A in both materials. Wide-angle x-ray scattering (WAXS) sh…
Aggregation and Gel Formation in Basic Silico−Calco−Alkaline Solutions Studied: A SAXS, SANS, and ELS Study
1999
Gelation of strongly basic silico−alkaline solutions was promoted by appropriate additions of calcium ions. The structure of the aggregates formed in the precursor sols and the resulting gels were studied, within a wide length scale, using small-angle X-ray, small-angle neutron, and elastic light scattering. The study of the kinetics of aggregation was performed in situ. The experimental results demonstrate that gels are composed of aggregates exhibiting a fractal structure, large particles formed in the solutions just after calcium addition and, in some cases, small primary particles remaining in the solution phase. The structural features of the gels are strongly dependent on the concentr…
Structural investigation of hybrid nanocomposites
2002
Ultra small (USANS) and small angle neutron scattering (SANS) techniques were employed to study an elastomer styrene–butadiene, where two kinds of silica fillers have been added in different amounts. Small silica-particle fillers are expected to modify morphological and mechanical properties when dispersed in the copolymer matrix. The USANS and SANS techniques can span a wide range of momentum transfer, investigating morphological properties of the filled elastomer over a number of decades in length scale. Surface and mass fractal behavior has been observed over different length scales.
Small Angle Neutron Scattering, X-ray Diffraction, Differential Scanning Calorimetry, and Thermogravimetry Studies to Characterize the Properties of …
2009
Nanocomposites based on laponite RD and (ethylene oxide)98(propylene oxide)67(ethylene oxide)98 (F127)triblock copolymer or poly(ethylene) glycol 2000 (PEG2000) were prepared by using the melting method. Small-angle neutron scattering and the X-ray diffraction experiments provided insights into the organization of the laponite RD dispersed in the macromolecular matrix over a wide length scale. SANS data analysis by means of a fractal law evidenced the formation of clusters of laponite RD at long correlation distance. The single laponite RD particles and the lamellar structure of F127 were described in the shorter length scale. Finally, the crystalline structure of the macromolecule was obse…
Structural Organization of Poly(vinyl alcohol) Hydrogels Obtained by Freezing and Thawing Techniques: A SANS Study
2005
The structural organization of matter in poly(vinyl alcohol) (PVA) hydrogels obtained by repeatedly freezing and thawing dilute solutions of PVA in D2O is investigated by use of small-angle neutron scattering measurements (SANS). This study is the first systematic and quantitative investigation in the medium range of length scales on PVA hydrogels obtained by freezing and thawing techniques. The studied gels have a complex hierarchical structure, extending over a wide range of length scales. The structural organization on the micron length scale originates from the presence of two separated phases constituted by polymer-rich and polymer-poor regions. The network structure may be interpreted…