Investigation of particle size distribution and aggregate structure of various ferrofluids by small-angle scattering experiments

1999 ◽  
Vol 32 (2) ◽  
pp. 273-280 ◽  
Author(s):  
Dietmar Eberbeck ◽  
Jürgen Bläsing
Keyword(s):  
Surface Layer ◽  
Small Angle ◽  
Scattering Data ◽  
Two Phase ◽  
Carrier Liquid ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Angle Scattering ◽  
Size Dispersion ◽  
Surface Layer Thickness

The size and the size dispersion of the composite particles of ferrofluids were determined assuming a lognormal distribution of core radii. Small-angle X-ray scattering data were fitted by the theoretical scattering function of two-phase spheres. Reliable results were obtained, because the scattering share of the surface layer can be taken into account. The particles aggregate at high as well as very low concentrations. After freezing of the carrier liquid, the particles within the clusters come together tightly. The measured minimal particle distance gives information about the effective surface-layer thickness. Two types of aggregates, namely compact clusters and extended net-like aggregates, were distinct in middle length scales.

scholarly journals Hierarchically organized materials with ordered mesopores: adsorption isotherm and adsorption-induced deformation from small-angle scattering

2020 ◽  
Vol 22 (22) ◽  
pp. 12713-12723 ◽  
Author(s):  
Lukas Ludescher ◽  
Roland Morak ◽  
Stephan Braxmeier ◽  
Florian Putz ◽  
Nicola Hüsing ◽  
...  
Keyword(s):  
Adsorption Isotherm ◽  
Small Angle ◽  
Small Angle Scattering ◽  
Scattering Data ◽  
X Ray ◽  
Hierarchical Porosity ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
Apparent Strain ◽  
Ordered Mesopores

Apparent strain artifacts resulting from the evaluation of small-angle X-ray scattering data superimpose the actual adsorption induced deformation in silica with hierarchical porosity. These artifacts can be corrected for by detailed modelling.

scholarly journals Two practical Java software tools for small-angle X-ray scattering analysis of biomolecules

2014 ◽  
Vol 47 (2) ◽  
pp. 810-815 ◽  
Author(s):  
Andreas Hofmann ◽  
Andrew E. Whitten
Keyword(s):  
Small Angle ◽  
Three Dimensional ◽  
Small Angle Scattering ◽  
Ease Of Use ◽  
Scattering Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
Three Dimensional Models ◽  
Ray Scattering

Small-angle X-ray scattering has established itself as a common technique in structural biology research. Here, two novel Java applications to aid modelling of three-dimensional macromolecular structures based on small-angle scattering data are described.MolScatis an application that computes small-angle scattering intensities from user-provided three-dimensional models. The program can fit the theoretical scattering intensities to experimental X-ray scattering data.SAFIRis a program for interactive rigid-body modelling into low-resolution shapes restored from small-angle scattering data. The program has been designed with an emphasis on ease of use and intuitive handling. An embedded version ofMolScatis used to enable quick evaluation of the fit between the model and experimental scattering data.SAFIRalso provides options to refine macromolecular complexes with optional user-specified restraints against scattering data by means of a Monte Carlo approach.

An iterative method to extract the size distribution of non-interacting polydisperse spherical particles from small-angle scattering data

2014 ◽  
Vol 47 (2) ◽  
pp. 712-718 ◽  
Author(s):  
D. Sen ◽  
Avik Das ◽  
S. Mazumder
Keyword(s):  
Iterative Method ◽  
Size Distribution ◽  
Small Angle ◽  
Real Space ◽  
Colloidal Dispersions ◽  
Small Angle Scattering ◽  
Spherical Particles ◽  
Scattering Data ◽  
X Ray Scattering ◽  
Angle Scattering

In this article, an iterative method for estimating the size distribution of non-interacting polydisperse spherical particles from small-angle scattering data is presented. It utilizes the iterative addition of relevant contributions to an instantaneous size distribution, as obtained from the fractional difference between the experimental data and the simulated profile. An inverse relation between scattering vector and real space is assumed. This method does not demand the consideration of any basis function set together with an imposed constraint such as a Lagrange multiplier, nor does it depend on the Titchmarsh transform. It is demonstrated that the method works quite well in extracting several forms of distribution. The robustness of the present method is examined through the successful retrieval of several forms of distribution, namely monomodal, bimodal, trimodal, triangular and bitriangular distributions. Finally, the method has also been employed to extract the particle size distribution from experimental small-angle X-ray scattering data obtained from colloidal dispersions of silica.

scholarly journals Small-angle scattering model for efficient characterization of wood nanostructure and moisture behaviour

2019 ◽  
Vol 52 (2) ◽  
pp. 369-377 ◽  
Author(s):  
Paavo A. Penttilä ◽  
Lauri Rautkari ◽  
Monika Österberg ◽  
Ralf Schweins
Keyword(s):  
Small Angle ◽  
Small Angle Scattering ◽  
Cellulose Microfibrils ◽  
Scattering Data ◽  
Scattering Model ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
The Hierarchical Structure ◽  
Full Utilization

Small-angle scattering methods allow an efficient characterization of the hierarchical structure of wood and other cellulosic materials. However, their full utilization would require an analytical model to fit the experimental data. This contribution presents a small-angle scattering model tailored to the analysis of wood samples. The model is based on infinitely long cylinders packed in a hexagonal array with paracrystalline distortion, adapted to the particular purpose of modelling the packing of cellulose microfibrils in the secondary cell wall of wood. The new model has been validated with small-angle neutron and X-ray scattering data from real wood samples at various moisture contents. The model yields reasonable numerical values for the microfibril diameter (2.1–2.5 nm) and packing distance (4 and 3 nm in wet and dry states, respectively) and comparable results between the two methods. It is particularly applicable to wet wood samples and allows changes in the packing of cellulose microfibrils to be followed as a function of moisture content.

PRINSAS– a Windows-based computer program for the processing and interpretation of small-angle scattering data tailored to the analysis of sedimentary rocks

2004 ◽  
Vol 37 (6) ◽  
pp. 1020-1024 ◽  
Author(s):  
Alan L. Hinde
Keyword(s):  
Small Angle ◽  
Scattering Length ◽  
Fractal Model ◽  
Scattering Data ◽  
Arbitrary Distribution ◽  
Geological Samples ◽  
Saxs Data ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
Sample Structure

PRINSASis a Windows program that takes as input raw (post-reduction) small-angle neutron and small-angle X-ray scattering (SANS and SAXS) data obtained from various worldwide facilities, displays the raw curves in interactive log–log plots, and allows processing of the raw curves. Separate raw SANS and ultra-small-angle neutron scattering (USANS) curves can be combined into complete scattering curves for an individual sample. The combined curves can be interpreted and information inferred about sample structure, using built-in functions. These have been tailored for geological samples and other porous media, and include the ability to obtain an arbitrary distribution of scatterer sizes, the corresponding specific surface area of scatterers, and porosity (when the scatterers are pores), assuming spherical scatterers. A fractal model may also be assumed and the fractal dimension obtained. A utility for calculating scattering length density from the component oxides is included in the program.

Small-angle scattering contrast calculator for protein and nucleic acid complexes in solution

2013 ◽  
Vol 46 (6) ◽  
pp. 1889-1893 ◽  
Author(s):  
Kathryn L. Sarachan ◽  
Joseph E. Curtis ◽  
Susan Krueger
Keyword(s):  
Nucleic Acid ◽  
Small Angle ◽  
Scattering Length ◽  
Software Tool ◽  
Scattering Data ◽  
Atomistic Modeling ◽  
Contrast Variation ◽  
X Ray ◽  
X Ray Scattering ◽  
Angle Scattering

Small-angle neutron scattering (SANS) with contrast variation can provide useful information about the structure and disposition of two or more chemically distinct components within a complex. TheSASSIE Contrast Calculator(SCC) is a new software tool designed to assist in planning SANS experiments with contrast variation on protein and nucleic acid complexes. On the basis of the primary sequence and deuteration level of each protein or nucleic acid component, theSCCcalculates and plotsI(0), contrast and scattering length densities; since SANS experiments often complement small-angle X-ray scattering studies, the program provides both neutron and X-ray parameters. TheSCCis run as an integrated component ofSASSIE[Curtis, Raghunandan, Nanda & Krueger (2012).Comput. Phys. Commun.183, 382–389], a software suite for atomistic modeling of ensembles of structures consistent with scattering data.

scholarly journals SCT: a suite of programs for comparing atomistic models with small-angle scattering data

2015 ◽  
Vol 48 (3) ◽  
pp. 953-961 ◽  
Author(s):  
David W. Wright ◽  
Stephen J. Perkins
Keyword(s):  
Small Angle ◽  
Data Bank ◽  
Scattering Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
Atomistic Models ◽  
First Time ◽  
Best Fit ◽  
Theoretical Scattering

Small-angle X-ray and neutron scattering techniques characterize proteins in solution and complement high-resolution structural studies. They are of particular utility when large proteins cannot be crystallized or when the structure is altered by solution conditions. Atomistic models of the averaged structure can be generated through constrained modelling, a technique in which known domain or subunit structures are combined with linker models to produce candidate global conformations. By randomizing the configuration adopted by the different elements of the model, thousands of candidate structures are produced. Next, theoretical scattering curves are generated for each model for trial-and-error fits to the experimental data. From these, a small family of best-fit models is identified. In order to facilitate both the computation of theoretical scattering curves from atomistic models and their comparison with experiment, theSCTsuite of tools was developed.SCTalso includes programs that provide sequence-based estimates of protein volume (either incorporating hydration or not) and add a hydration layer to models for X-ray scattering modelling. The originalSCTsoftware, written in Fortran, resulted in the first atomistic scattering structures to be deposited in the Protein Data Bank, and 77 structures for antibodies, complement proteins and anionic oligosaccharides were determined between 1998 and 2014. For the first time, this software is publicly available, alongside an easier-to-use reimplementation of the same algorithms in Python. Both versions ofSCThave been released as open-source software under the Apache 2 license and are available for download from https://github.com/dww100/sct.

Critical region and metal–nonmetal transition in expanded fluid mercury: advanced evaluation of small-angle X-ray scattering data

2010 ◽  
Vol 43 (2) ◽  
pp. 244-249 ◽  
Author(s):  
Wilhelm Ruland ◽  
Friedrich Hensel
Keyword(s):  
Small Angle ◽  
Critical Region ◽  
Structural Model ◽  
Volume Fraction ◽  
Critical Density ◽  
Scattering Data ◽  
Two Phase ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

The small-angle X-ray scattering data of expanded fluid mercury published in the literature were evaluated using a modified form of the Teubner–Strey equation for microemulsions together with the general treatment of two-phase systems according to Porod. The parameters obtained in the critical region and the metal–nonmetal (M–NM) transition are evidence of a nanoemulsion composed of M and NM domains. The structure of this emulsion is characterized by density, volume fraction and size parameters (average chord length, polydispersity) of the domains. On the basis of these parameters, a structural model for fluid mercury in the liquid–vapour critical region and the M–NM transition is developed. Analysis of the relationship between the volume fraction of the M domains and the electrical conductivity reveals that a percolation transition occurs, with a threshold located near the liquid–vapour critical density. This observation is consistent with recent theoretical developments.

scholarly journals Stable DOPG/Glycyrrhizin Vesicles with a Wide Range of Mixing Ratios: Structure and Stability as Seen by Scattering Experiments and Cryo-TEM

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4959
Author(s):  
Carina Dargel ◽  
Friederike Gräbitz-Bräuer ◽  
Ramsia Geisler ◽  
Pascal Fandrich ◽  
Yvonne Hannappel ◽  
...  
Keyword(s):  
Small Angle ◽  
Small Angle Scattering ◽  
Scattering Data ◽  
X Rays ◽  
Additional Information ◽  
Mixing Ratios ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
Wide Range ◽  
Complete Miscibility

Phosphatidylglycerols represent a large share of the lipids in the plasmamembrane of procaryotes. Therefore, this study investigates the role of charged lipids in the plasma membrane with respect to the interaction of the antiviral saponin glycyrrhizin with such membranes. Glycyrrhizin is a natural triterpenic-based surfactant found in licorice. Vesicles made of 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1’-glycerol) (DOPG)/glycyrrhizin are characterized by small-angle scattering with neutrons and X-rays (SANS and SAXS). Small-angle scattering data are first evaluated by the model-independent modified Kratky–Porod method and afterwards fitted by a model describing the shape of small unilamellar vesicles (SUV) with an internal head-tail contrast. Complete miscibility of DOPG and glycyrrhizin was revealed even at a ratio of lipid:saponin of 1:1. Additional information about the chain-chain correlation distance of the lipid/saponin mixtures in the SUV structures is obtained from wide-angle X-ray scattering (WAXS).

DADIMODO: a program for refining the structure of multidomain proteins and complexes against small-angle scattering data and NMR-derived restraints

2011 ◽  
Vol 44 (6) ◽  
pp. 1264-1271 ◽  
Author(s):  
Guillaume Evrard ◽  
Fabien Mareuil ◽  
Francois Bontems ◽  
Christina Sizun ◽  
Javier Perez
Keyword(s):  
Conformational Changes ◽  
Small Angle ◽  
Scattering Data ◽  
Multidomain Proteins ◽  
Domain Structures ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
Stochastic Optimization Algorithm ◽  
User Friendly ◽  
Orientational Restraints

DADIMODOis a program for refining atomic models of multidomain proteins or complexes against small-angle X-ray scattering data. Interdomain distance and orientational restraints, such as those derived from NMR measurements, can be included in the optimization process. While domain structures are mainly kept rigid, flexible regions can be user defined. Stepwise generic conformational changes, specified by the user, are applied cyclically in a stochastic optimization algorithm that performs a search in the protein conformation space. The convergence for this genetic algorithm is driven by an adaptable selection pressure. The algorithmic structure guarantees that a physically acceptable full atomic model of the structure is present at all stages of the optimization. A graphical user interface ensures user-friendly handling.

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