No abstract

Structural health monitoring (SHM) has become more and more important in modern industries as it can monitor the safety of structures during the full service life and prevent possible losses of life and economics. Shear horizontal wave in plate-like structures is very useful for long distance inspection since its fundamental mode (SH) is totally non-dispersive. However, all the currently available SH wave transducers are not suitable for practical SHM because of their complicated structures. In this work, we firstly investigated via finite element (FEM) simulations the performances of thickness-poled d PZT ring based omni-directional SH wave piezoelectric transducers (OSH-PT) consisting of different number of elements. Results show that the two-half-ring based OSH-PT can have perfect omni-directivity and acceptable performances in excitation/reception of SH waves. Then, experimental testing on a 21 mm outer-diameter (OD), 9 mm inner-diameter (ID) two-half-ring OSH-PT shows that it exhibits acceptable but not desirable performances in both excitation and reception of SH wave. Finally, size optimization was conducted on the two-half-ring based OSH-PT using FEM simulations and results showed that its performances can be fairly enhanced by reducing the outer diameter of the half-ring. Testing results on a 12 mm-OD, 6 mm-ID OSH-PT show that the SH-to-Lamb waves ratio in the case of self-excitation and self-reception can be over 20 dB from 115 kHz to 250 kHz, which is good enough for practical applications. The proposed two-half-ring OSH-PT is expected to be widely used in SH wave based SHM due to its simple structure, easy fabrication/assembling, low cost and good performances.

Clarithromycin resistance is the main reason for the failure of 7-d triple therapy. In populations with low levels of resistance, a 7-d triple therapy is a viable choice. The choice of therapy should not be influenced by conditions in high antibiotic resistance regions.

as a member of the integrin family, integrin α3β1 (iTGa3) has been linked to intercellular communication and serves an important role in the signaling among cells and the extracellular matrix. Microrna (mir)-199a-5p has been demonstrated to be related to the pathogenesis and progression of multiple malignant diseases. However, the biological functions of mir-199a-5p and iTGa3 in colorectal cancer (crc) have rarely been reported. The aim of the present study was to explore the roles of mir-199a-5p and iTGa3 in crc. immunohistochemistry staining and western blotting were applied to detect the protein expression of iTGa3 in crc tissues and cells. reverse transcription-quantitative Pcr was performed to investigate the expression of mir-199a-5p and iTGa3 mrna. HcT-116 cells were transfected with mir-199a-5p mimics, mimics control, short hairpin rna targeting iTGa3, or pcdna-iTGa3 for the functional experiments. dual luciferase reporter assay was applied to confirm whether mir-199a-5p targeted the 3' untranslated region (3'uTr) of iTGa3. The MTT, Transwell and wound healing assays were used to evaluate the proliferation, invasion and migration of CRC cells. Immunofluorescence assay was used to monitor the epithelial-mesenchymal transition (eMT) biomarker expression. The results demonstrated downregulation of mir-199a-5p and upregulation of iTGa3 in crc tissues and cell lines. mir-199a-5p mimics and knockdown of iTGa3 suppressed the proliferation, invasion and migration of crc cells. Bioinformatics analysis and luciferase reporter assay indicated that mir-199a-5p targeted the 3'uTr of the iTGa3 transcript, and overexpression of iTGa3 reversed the tumor-suppressive effects of mir-199a-5p elevation. In addition, the immunofluorescence assay suggested that mir-199a-5p mimics suppressed the eMT of crc cells, whereas the overexpression of iTGa3 restored this effect. in conclusion, mir-199a-5p may act as a tumor suppressor by targeting and negatively regulating iTGa3 in crc.

No abstract

We proposed a metasurface consisting of multiple parallel strips with varied widths which can steer and focus the fundamental shear horizontal (SH0) wave in plates. Firstly, the group velocity of the quasi-SH0 wave in different-width strips was calculated. Then, a multiple-strip metasurface was designed which was realized by through-thickness grooving in an aluminum plate. Finite-element simulations show that this metasurface can steer the SH0 wave to a prescribed angle. Later, experiments were conducted in which thickness-shear (d15) piezoelectric strips were used as SH0 wave exciters and receivers, and experimental results well reproduced the simulation results. Finally, another multiple-strip metasurface was designed to focus the SH0 wave at a designated point. Both simulations and experiments were conducted, and results validated the proposed design. This work may provide guidance for the design of SH wave metasurfaces.

No abstract

Guided wave-based inspection has emerged as a promising tool to evaluate the reliability of key components in modern industries. The fundamental shear horizontal (SH0) wave is always of great interests for plate-like structures because of its non-dispersion characteristics. However, the generation and reception of SH0 wave using piezoelectric wafers is not straightforward. In this paper, we firstly define three types shear mode piezoelectric wafers, i.e., the conventional in-plane poled thickness-shear (d15) mode, the thickness-poled thickness-shear (d15) mode, and the face-shear (d24) mode. Then, finite element simulations were conducted to demonstrate their performance in SH wave generation and reception. The results indicated that the face shear d24 wafer can generate almost single mode SH0 wave, while both types of d15 wafers would generate Lamb waves and SH0 wave simultaneously. Finally, experiments were carried out to check the efficiency of different shear mode piezoelectric wafers in SH0 wave generation and reception. The results indicated that the d24 wafer can generate and receive SH0 wave of high signal to noise ratio (SNR) with high energy conversion efficiency, while the in-plane poled d15 wafer would generate SH0 wave of high amplitude and acceptable SNR but with relatively low energy conversion efficiency. The performances of thickness-poled d15 wafer was not as good as the other two in both SH wave generation and reception. This work will be helpful for the applications of SH waves in plate-like structures.