Acoustic diagnosis of elastic properties of human tooth by 320 MHz scanning acoustic microscopy after radiotherapy treatment for head and neck cancer

Determination of the significance of atomic concentration on surface properties of Ba x Mg1-x F2 alloy coatings via microscopic and spectroscopic techniques

Both BaF2 and MgF2 compounds and Ba x Mg1-x F2 alloy thin films were deposited on glass and silicon (Si) substrates in nanometric sizes (100 ± 10 nm) in a high vacuum environment by radio frequency (rf) magnetron sputtering. Using BaF2 (99% purity) and MgF2 (99% purity) target materials and adjusting the power levels applied to these targets, Ba x Mg1-x F2 alloy coatings at different atomic concentrations were formed under the same vacuum conditions. The microstructure and surface characteristics of the samples were analysed with the help of spectroscopic and microscopic methods. For the surface characterization, with scanning acoustic microscopy (SAM), 2-dimensional surface acoustic images of the samples were mapped, the surface acoustic impedance values were determined, and information about the micro hardness of the materials was obtained. Surface roughness values and grain sizes were obtained by taking 3-dimensional surface images of investigated materials using atomic force microscopy (AFM). Average nanometric particle sizes were determined for each sample with scanning electron microscopy (SEM), therefore, information about surface homogeneity was obtained. For the microstructural characterization, quantitative elemental analysis was performed using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS), and stoichiometric ratios of atomic compositions were identified. By evaluating the data obtained from the microscopic and spectroscopic measurements, the effect of the atomic concentration parameter on the morphological properties of the material was determined. The usability of the produced binary fluoride alloy thin film coatings is promising for emerging optoelectronic, ceramic industry, biomedical and surface acoustic wave applications.

Uncertainty analysis of Altantic salmon fish scale's acoustic impedance using 30 MHz C-Scan measurements

Understanding the biomechanics of fish scales is crucial for their survival and adaptation. Ultrasonic C-scan measurements offer a promising tool for non-invasive characterization, however, existing literature lacks uncertainty analysis while evaluating acoustic impedance. This article presents an innovative integration of uncertainty into the analytical framework for estimating stochastic specific acoustic impedance of salmon fish scale through ultrasonic C-scans. In this study, the various types of uncertainties arising due to variation in biological structures and aging, measurement errors, and analytical noises are combined together in the form of uncertain reflectance. This uncertain reflectance possesses a distribution which is derived using a theory of waves by assuming suitable stochasticity in wavenumber. This distribution helps in development of a stochastic-specific acoustic impedance map of the scales which demonstrates the possible deviations of impedance from mean value depending on uncertainties. Furthermore, maximal overlap discrete wavelet transform is employed for efficient time-frequency deconvolution and Kriging for spatial data interpolation to enhance the robustness of the impedance map, especially in scenarios with limited data. The framework is validated by accurately estimating the specific acoustic impedance of well-known materials like a pair of target medium (polyvinylidene fluoride) and reference medium (polyimide), achieving over 90% accuracy. Moreover, the accuracy of the framework is found superior when compared with an established approach in the literature. Applying the framework to salmon fish scales, we obtain an average specific acoustic impedance of 3.1 MRayl along with a stochastic map visualizing the potential variations arising from uncertainties. Overall, this work paves the way for more accurate and robust studies in fish scale biomechanics by incorporating a comprehensive uncertainty analysis framework.

Quantifying the influences of radiation therapy on deformability of human red blood cells by dual-beam optical tweezers

Radiation therapy is widely used as a treatment tool for malignancies. However, radiation-related complications are still unavoidable risks for off-target cells. Little is known about radiation therapy's possible effects on mechanical features of the off-target cells such as human red blood cells (RBCs). RBCs are nucleus-free circulating cells that can deform without losing functionality in healthy conditions. Thus, to evaluate in vitro effects of radiation therapy on the healthy plasma membrane of cells, RBCs were selected as a primary test model. RBCs were exposed to clinically prescribed radiotherapy doses of 2 Gy, 12 Gy and, 25 Gy, and each radiotherapy dose group was compared to a non-irradiated group. Cells were characterized by stretching using dual-beam optical tweezers and compared using the resulting deformability index. The group receiving the highest radiation dose was found statistically distinguishable from the control group (DI_0Gy = 0.33 ± 0.08), and revealed the highest deformability index (DI_25Gy = 0.38 ± 0.11, p = 0.0068), while no significant differences were found for 2 Gy (DI_2Gy = 0.33 ± 0.08, p = 0.9) and 12 Gy (DI_12Gy = 0.31 ± 0.09, p = 0.2) dose groups. Based on these findings, we conclude that radiotherapy exposure may alter the deformability of red blood cells depending on the dose amount, and measurement of deformability index by dual-beam optical tweezers can serve as a sensitive biomarker to probe responses of cells to the radiotherapy.

Little is known about radiation therapy's possible effects on mechanical features of off-target cells such as human red blood cells. Here, irradiated human red blood cells were stretched using dual-beam optical tweezers and compared using the resulting deformability index.

Scanning acoustic microscopy investigation of weld lines in injection-molded parts manufactured from industrial thermoplastic polymer

Scanning acoustic microscopy (SAM) is used to characterize welds in a thermoplastic polymer (ABS) manufactured by injection-molding, particularly at the locations of weld-lines known to form as unavoidable significant defects. Acoustic micrographs obtained at 420 MHz clearly resolve the weld lines with morphological deformations and microelastic heterogenity. This is also where terahertz (THz) measurements, carried out in support of the SAM study, reveal enhanced birefringence corresponding to the location of these lines enabling verification of the SAM results. Rayleigh surface acoustic waves (RSAW), quantified by V(z) curves (with defocusing distance of 85 μm), are found to propagate slower in regions close to the weld lines than in regions distant from these lines. The discrepancy of about 100 m/s in the velocity of RSAW indicates a large variation in the micro-elastic properties between areas close to and distant from the weld lines. The spatial variations in velocity (V_R) of RSAWs indicate anisotropic propagation of the differently polarized ultrasonic waves.