In this study, a flexible ultrasonic transducer (FUT) was applied in a laser ultrasonic technique (LUT) for non-destructive characterization of metallic pipes at high temperatures of up to 176 °C. Compared with normal ultrasound transducers, a FUT is a piezoelectric film made of a PZT/PZT sol-gel composite which has advantages due to its high sensitivity, curved surface adaptability and high temperature durability. By operating a pulsed laser in B-scan mode along with the integration of FUT and LUT, a multi-mode dispersion spectrum of a stainless steel pipe at high temperature can be measured. In addition, dynamic wave propagation behaviors are experimentally visualized with two dimensional scanning. The images directly interpret the reflections from the interior defects and also can locate their positions. This hybrid technique shows great potential for non-destructive evaluation of structures with complex geometry, especially in high temperature environments.

Proinflammatory cytokines and reactive oxygen species (ROS) are known to be involved in the initiation and progression of osteoarthritis (OA). New evidence clarifying the correlation between ROS and inflammation has indicated that oxidative stress can up-regulate inflammatory cytokines. l-Ascorbic acid (AA), an antioxidant, has been shown to have anti-inflammatory effects and improve matrix deposition in chondrocytes. The purpose of this study was to examine the effects of hyaluronic acid (HA; 100 μg/mL) supplemented with AA (50 μg/mL) on human normal and interleukin-1 beta-stimulated (IL-1β, 10 ng/mL) chondrocytes. HA, AA, and HA + AA treatment did not change cell morphology, viability, proliferation, and glycosaminoglycan production in normal chondrocytes. HA, AA, and HA + AA, by contrast, partially restored viability and morphology of hypertrophic chondrocytes, and HA and HA + AA further decreased the cytotoxicity of IL-1β. Real-time PCR revealed that AA and HA + AA had no substantial effects on unstimulated chondrocytes, except for down-regulation of matrix metalloproteinase (MMP)-9 mRNA levels. For IL-1β-stimulated chondrocytes, significant down-regulation of IL-1β, tumor necrosis factor-alpha (TNF-α), MMP-3, and MMP-9 mRNA expression was found when cells were cultured in HA-supplemented media. Moreover, HA + AA supplementation further significantly decreased MMP-3 and MMP-9 mRNA expression. The protein production of MMP-3 was decreased, with a significant difference between the HA + AA group and HA group. The antioxidant capacity and superoxide dismutases activity were also partially restored in stimulated chondrocytes. HA supplemented with AA modulates MMPs expression and antioxidant fuction in chondrocytes. AA may enhance the anticatabolic effects of HA on OA chondrocytes. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1809-1817, 2018.

A laser ultrasound technique (LUT) is reported for nondestructive characterization of hydrogen concentration (HC) in Zr-4 cladding tubes. With the LUT, ultrasonic waves propagating in the Zircaloy tubes with different HC are generated and detected remotely by optical means. By measuring the dispersion spectra with the LUT, relations between the dispersion spectra and the HC of the Zircaloy tubes are established. HC ranging from 0 to 1200 ppm in the Zircaloy tubes are successfully discriminated by the LUT with a resolution of 200 ppm.

Detailed ultrasonic reflection measurements in piezoelectric LiNbO3 are reported which are compared to the results of the theoretical analysis of the previous paper, part I. Differences in mode coupling and behavior are illustrated in several calculated examples. The calculated numerical results are demonstrated in a full image format. It is shown how dielectric fluid loading influences the reflection behavior and how strong piezoelectric coupling can lead to unexpected dispersion in the fundamental symmetric mode. The data confirms in each case the predictions of an exact partial-wave analysis of the problem, including the dielectric influence of the fluid. These phenomena play a role in the design and performance of piezoelectric sensing devices.

An ultrasound nondestructive (NDE) technique is used to characterize hydrogen concentration (HC) in Zircaloy tubes. This ultrasound-based NDE technique employs a low-frequency PVDF/LFB transducer operated in a z-scan mode to obtain the dispersion relation of guided acoustic waves propagation in the Zircaloy tubes. A Fourier-based signal processing technique is used to obtain the dispersion curves. With this ultrasound technique, the determined dispersion relations are used to determine the HC in Zircaloy tubes with a resolution better than 300 ppm.