Structural factor analysis of small angle X-Ray and neutron scattering curves for apoferritin

• Yury Ryzhykau (MIPT)

The problem of studying protein molecules in a solution by small-angle scattering is comparatively simple if the protein interaction is not taken into account and the solution is monodisperse. In this case it is possible to solve a structure of an object with a low resolution with the help of ATSAS program package[1]. In this work the comparative analysis of small-angle X-Ray and neutron scattering curves in small angle region for the set of concentrations of a protein apoferritin in a heavy water was done. Measurements were performed at spectrometer Rigaku, MIPT, Dolgoprudny; synchrotron BM-29, ESRF, Grenoble [2] and a small-angle neutron spectrometer YuMO [3,4]. However, the interaction between proteins has been detected even at low concentrations. By the approximation at zero concentration level and obtaining the form-factor the structural factor curve has been obtained. The type of interaction has been defined and the distances between the protein molecules in aggregates have been calculated. The results are being discussed.

Study of the aging behavior of materials important in nuclear energy field - Incoloy 800 HT and 304L steel- using neutron scattering techniques

• ION IONITA (Institute of Nuclear Research, Pitesti, Romania)

The 800 HT Incoloy is widely used in power generation for steam generators tubing and high temperature heat exchangers for gas cooled nuclear reactors and as a candidate material for fuel cladding in GEN IV reactors. The 304L steel has a high ductibility. Low yield stress and high tensile strength and is used widely in nuclear power plant. There were manufactured 4 samples of Incoloy 800HTand 4 samples of 304L steel, all of 2x15x25mm dimensions and standing a heat treatment of 60 days at 450, 500, 550 and 600 degrees respectively. The samples were investigated by neutron diffraction and small angle neutron scattering at the FSD, HRFD and MEREDIT diffractometers, YuMO-SANS and KFKI SANS spectrometers (in function at IBR-2 reactor, Dubna, respectively Budapest). Lattice cell and peak width parameters changes for both sample series (using neutron diffraction measurements) together with information on heat treatment effects concerning precipitate size and volume distribution of alloying elements (using SANS measurements) were found. Structural properties of the above mentioned materials of significant importance in nuclear energy field, revealed through high temperature heat treatment are described. Key words: neutron scattering techniques, neutron diffraction, SANS, , Incoloy 800 HT, 304L steel