Assessing the influence of crystallographic orientation, stress and local deformation on magnetic domains using electron backscatter diffraction and forescatter electron imaging

The magnetic properties of non-oriented electrical steel (NOES) used in an electrical engine play an important role in the transformation process from electric to mechanic energy. In this process the NOES is subjected to cyclic loading and strong tensile forces. Until now the dependence of the magnetic properties with respect to a through stress changing microstructure is not fully understood. In this paper a setup for a quasi-static in situ deformation experiment with a SEM is presented in which the surface magnetic domains of a NOES were captured by revealing type 2 magnetic contrast with forescatter diodes, the crystallographic texture was mapped through EBSD and the local relative strains and rotations were calculated with CrossCourt. The magnetic domains were related to the angles between the easy axes and the surface as well as the angle differences between the easy axes of neighboring grains. For small differences wide boundary-crossing domain patterns occurred. In contrast, for high ones predominantly compensating domains emerged. Thus a distinct influence of neighboring grains was present. Reaching a certain stress level, a strong tendency of domain alignment along the easy axes closest to the stress direction could be observed. Locally exceeding the elastic limit, slip lines appeared but had no visible influence on the domains. After unloading, in those areas a clear hindrance of domain alignment was apparent, which was attributed to the dislocation accumulations. CrossCourt enables the estimation of GND accumulations, which can be used to detect domain wall pinning. In conclusion, the presented method provides a way to link the magnetic properties of NOES to the texture and a through stress changing microstructure.

Local analysis of strains and rotations for macromolecular electron microscopy maps

Macromolecular complexes perform their physiological functions by local rearrangements of their constituents and biochemically interacting with their reaction partners. These rearrangements may involve local rotations and the induction of local strains causing different mechanical efforts and stretches at the different areas of the protein. The analysis of these local deformations may reveal important insight into the way proteins perform their tasks. In this paper we introduce a method to perform this kind of local analysis using Electron Microscopy volumes in a fully objective and automatic manner. For doing so, we exploit the continuous nature of the result of an elastic image registration using B-splines as its basis functions. We show that the results obtained by the new automatic method are consistent with previous observations on these macromolecules.

Usage of Leptospira spp. local strains as antigens increases the sensitivity of the serodiagnosis of bovine leptospirosis

Leptospirosis is a zoonotic disease that occurs worldwide, particularly in tropical countries. In livestock the agent is responsible for reproductive problems such as infertility and abortion. Serogroup Sejroe, particularly serovar Hardjo, prevails in cattle in several regions. The microscopic agglutination test (MAT) is the current method for diagnosing leptospirosis. It has been proposed that the inclusion of local strains could detect a larger set of seroreactive animals. In that context, the aim of the present study was to evaluate if the usage of local strains as antigens increases the sensitivity of the serodiagnosis of bovine leptospirosis. Blood and urine samples were collected from 314 bovines from several herds randomly selected in a slaughterhouse in Rio de Janeiro, Brazil. Serological diagnosis was made with MAT using a 21 reference-strains panel (MAT21). Additionally, 12 local strains (MAT33) were included as antigens. PCR was performed with the urine samples and it was positive on 71 out of 222 samples (31.9%). MAT21 identified as seroreactive 173 (55.1%) out of the 314 animals studied, with Sejroe the most common (38.1%). In MAT33, 204 (65.0%) animals were seroreactive with a significant increase on seroreactivity (9.9%). In conclusion, MAT presented with a significant increase of sensitivity when local strains were used as antigens. Among the local strains, 2013_U152 (KP263062) (serogroup Shermani) and 2013_U280 (KP263069) (serogroup Grippotyphosa) showed to be more antigenic.