Effect of Liquid Crystalline Host on Structural Changes in Magnetosomes Based Ferronematics

The effect of the liquid crystalline host on structural changes in magnetosomes based on ferronematics is studied using the surface acoustic wave (SAW) technique supported by some capacitance and light transmission measurements. The measurement of the attenuation response of SAW propagating along the interface between LC and the piezoelectric substrate is used to study processes of structural changes under magnetic field. The magnetosome nanoparticles of the same volume concentration were added to three different nematic LCs, 5CB, 6CB, and E7. Unlike to undoped LCs, the different responses of SAW attenuation under the influence of magnetic and electric fields in LCs doped with magnetosomes were observed due to characteristic structural changes. The decrease of the threshold field for doped LCs as compared with pure LCs and slight effects on structural changes were registered. The threshold magnetic fields of LCs and composites were determined from capacitance measurements, and the slight shift to lower values was registered for doped LCs. The shift of nematic-isotropic transition was registered from dependencies of SAW attenuation on temperature. The acoustic anisotropy measurement approved the previous supposition about the role of bulk viscosity in used SAW measurements. In addition, capacitance and light transmition investigations supported SAW results and pointed out conclusions about their magnetic field behavior. Obtained results are discussed and confronted with previous ones and coincide well with those observed using acoustic, optical, or dielectric techniques.

Study on Pipeline Spanning Detection Using Magnetic Anisotropy

Subsea pipelines often lose foundation soil support due to ocean current erosion and form spanning. Spanning greatly increases the risk of pipeline fracture. When a subsea pipeline has spanning, it is often accompanied by characteristic changes in its pipe wall stress, pipeline deflection, and pitch angle. In turn, we can analyze the three parameters to get the spanning state of the pipeline. Wherein, around using stress to detect pipeline spanning state, this paper carries out two parts of research work. (1) We conducted a stress analysis on the free-span pipeline. The results show that the stress distribution has a strong distinct relationship with the pipeline spanning state. (2) We proposed and developed a steel plate stress detection scheme based on the induced voltage method. The results show that the steel plate stress has a good linear relationship with the induced voltage of the receiving coil on its surface, and the sensitivity can reach 1mv/MPa. Therefore, the AC magnetic anisotropy measurement of stress can reliably identify the stress distribution of the spanning pipeline.

Effect of Sugars on Chlamydia trachomatis Infectivity

Background. Previous works suggest that sugars can have a beneficial effect on C. trachomatis (CT) survival and virulence. In this study, we investigated the effect of different sugars on CT infectivity, elucidating some of the molecular mechanisms behind CT-sugar interaction. Methods. CT infectivity was investigated on HeLa cells after 2 hour-incubation of elementary bodies (EBs) with glucose, sucrose, or mannitol solutions (0.5, 2.5, 5.0 mM). The effect of sugars on EB membrane fluidity was investigated by fluorescence anisotropy measurement, whereas the changes in lipopolysaccharide (LPS) exposure were examined by cytofluorimetric analysis. By means of a Western blot, we explored the phosphorylation state of Focal Adhesion Kinase (FAK) in HeLa cells infected with EBs pre-incubated with sugars. Results. All sugar solutions significantly increased CT infectivity on epithelial cells, acting directly on the EB structure. Sugars induced a significant increase of EB membrane fluidity, leading to changes in LPS membrane exposure. Especially after incubation with sucrose and mannitol, EBs led to a higher FAK phosphorylation, enhancing the activation of anti-apoptotic and proliferative signals in the host cells. Conclusions. Sugars can increase CT infectivity and virulence, by modulating the expression/exposure of chlamydial membrane ligands. Further in-depth studies are needed to better understand the molecular mechanisms involved.

Seismic shear wave anisotropy of an anisotropic rock containing aligned cracks: theory and applications to experiment and field data

SUMMARY Cracks universally exist in Earth's crustal rocks. Many rocks are intrinsically anisotropic, which, when coupled with crack-induced anisotropy, significantly affect seismic wave propagation through the rocks. Using the method of sphere equivalency of effective scattering, we have developed a technique to model the effective moduli of transversely isotropic (TI) media containing cracks. The modelling results show that the wave characteristics are significantly affected by the interaction of the two anisotropy mechanisms. To validate the validity and accuracy, the theory was applied to a recent experiment made with a vertical transverse isotropy (VTI) medium containing cracks and shows significantly better agreement with the data. For a more realistic situation, the new modelling was applied to interpret the borehole acoustic anisotropy measurement results from a fractured VTI formation, showing that the theory can adequately explain the anisotropic characteristics of the field data. With the validation and testing, the theoretical results advocated in this study can be used with confidence.