Investigation of the physicochemical properties of magnetic nanoparticles: size, magnetic properties, concentration

This work presents the results of studies of a series of samples of aqueous dispersions of magnetic nanoparticles. The particle sizes were measured for these samples by the dynamic scattering method. Using the method of ultramicroscopy, the number concentration of particles in the samples and the concentration of particles remaining in the volume of the samples after exposure to a magnetic field at various time intervals were measured.

Speckle-Based Sensing of Microscopic Dynamics in Expanding Polymer Foams: Application of the Stacked Speckle History Technique

Microscopic structural rearrangements in expanding polylactide foams were probed using multiple dynamic scattering of laser radiation in the foam volume. Formation and subsequent expansion of polylactide foams was provided by a rapid or slow depressurization of the “plasticized polylactide–supercritical carbon dioxide” system. Dynamic speckles induced by a multiple scattering of laser radiation in the expanding foam were analyzed using the stacked speckle history technique, which is based on a joint mapping of spatial–temporal dynamics of evolving speckle patterns. A significant decrease in the depressurization rate in the case of transition from a rapid to slow foaming (from 0.03 MPa/s to 0.006 MPa/s) causes dramatic changes in the texture of the synthesized stacked speckle history maps. These changes are associated with transition from the boiling dynamics of time-varying speckles to their pronounced translational motions and are manifested as significant slopes of individual speckle traces on the recovered stacked speckle history maps. This feature is interpreted in terms of the actual absence of a new cell nucleation effect in the expanding foam upon slow depressurization on the dynamic scattering of laser radiation.

Blunt hub affecting the radar cross section of rotor based on dynamic scattering method

In order to study the radar characteristics of blunt-hub rotor, a dynamic scattering method (DSM) based on physical optics and physical theory of diffraction is presented. Important influencing factors are analyzed and discussed, including rotor disk inclination, azimuth, elevation angle, and radar wave frequency. The radar cross section (RCS) of the blunt-hub rotor is used for comparison with conventional-hub rotor and sharp-hub rotor. The RCS performance of the blunt-hub rotor at different radar wave frequencies is close to that of the sharp-hub rotor. At larger positive elevation angles, the RCS∼azimuth performance of the blunt-hub rotor is not as good as the other two rotors, while the RCS performance of the blunt-hub rotor has an advantage under the larger negative elevation angle and the inclination of the rotor disk. The presented DSM is feasible and effective for learning the electromagnetic scattering characteristics of the blunt-hub rotor.

Non-invasive super-resolution imaging through dynamic scattering media

Super-resolution imaging has been revolutionizing technical analysis in various fields from biological to physical sciences. However, many objects are hidden by strongly scattering media such as biological tissues that scramble light paths, create speckle patterns and hinder object’s visualization, let alone super-resolution imaging. Here, we demonstrate non-invasive super-resolution imaging through scattering media based on a stochastic optical scattering localization imaging (SOSLI) technique. After capturing multiple speckle patterns of photo-switchable point sources, our computational approach utilizes the speckle correlation property of scattering media to retrieve an image with a 100-nm resolution, an eight-fold enhancement compared to the diffraction limit. More importantly, we demonstrate our SOSLI to do non-invasive super-resolution imaging through not only static scattering media, but also dynamic scattering media with strong decorrelation such as biological tissues. Our approach paves the way to non-invasively visualize various samples behind scattering media at nanometer levels of detail.