Application of Bragg Light Diffraction for Determination of Acoustic Wave Frequency

The possibility of determining the frequency of an acoustically active acoustic wave has been studied. The studies were carried out using the Bragg diffraction method of light on a high-frequency acoustic wave in a lanthanum gallosilicate crystal oriented with high accuracy along the third-order crystallographic axis. Transverse acoustic waves were excited in the range of 0.8-1.6 GHz using lithium niobate piezoelectric transducers. The attenuation coefficient of acoustic waves was previously determined by the pulse ultrasonic method. An expression is obtained for the magnitude of the specific rotation of the plane of polarization of an acoustic wave depending on the effective constant of the acoustic activity tensor and the effective elastic constant. It has been established that specific acoustic activity depends on the frequency of the acoustic wave according to a quadratic law. The results of the study showed that the proposed method makes it possible to determine the frequency of an acoustically active acoustic wave in a dynamic mode with an accuracy of up to 1 %

Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications

Superparamagnetic iron oxide nanoparticles can providemultiple benefits for biomedical applications in aqueous environments such asmagnetic separation or magnetic resonance imaging. To increase the colloidal stability and allow subsequent reactions, the introduction of hydrophilic functional groups onto the particles’ surface is essential. During this process, the original coating is exchanged by preferably covalently bonded ligands such as trialkoxysilanes. The duration of the silane exchange reaction, which commonly takes more than 24 h, is an important drawback for this approach. In this paper, we present a novel method, which introduces ultrasonication as an energy source to dramatically accelerate this process, resulting in high-quality waterdispersible nanoparticles around 10 nmin size. To prove the generic character, different functional groups were introduced on the surface including polyethylene glycol chains, carboxylic acid, amine, and thiol groups. Their colloidal stability in various aqueous buffer solutions as well as human plasma and serum was investigated to allow implementation in biomedical and sensing applications.status: publishe