Effects of Electrode Off Centre on Trapped Thickness-Shear Modes in Contoured AT-Cut Quartz Resonators

We investigated thickness-shear vibrations of a contoured, AT-cut quartz resonator with a pair of electrodes displaced from the resonator centre. The scalar differential equations by Stevens and Tiersten for thickness-shear vibrations of electroded and unelectroded quartz plates were employed. Based on the variational formulation of the scalar differential equations established in a previous paper and the variation-based Ritz method with trigonometric functions as basis functions, free vibration resonance frequencies and trapped thickness-shear modes were obtained. The effects of the electrode off centre on resonance frequencies and mode shapes were examined. When the electrode off centre is about one hundredth of the electrode length, the relative frequency shift is of the order of one part per million, significant in certain resonator design and applications. The electrode off centre also causes the loss of symmetry of modes, which has an adverse effect on resonator frequency stability under a normal acceleration

Mechanics of shaft-loaded blister test for thin film suspended on compliant substrate

AbstractBased on the von Kármán plate theory, the mechanics of a shaft-loaded blister test for thin film/substrate systems is studied by considering elastic substrate deformations and residual stresses in these films. In testing, films are attached to a substrate provided with a circular hole, through which loading is applied to the film by a flat-ended shaft of circular cross-section. The effect of substrate deformation on the deflection of the loaded film is taken into account by using a line spring model. For small deflections, an analytical solution is derived, while for large deflections a numerical solution is obtained using the shooting method. The resulting load-shaft displacement relation, which is essential in blister tests, compares favorably with finite element analysis

Effects of electrostatic tractions on the interfacial fracture behavior of two-phase piezoelectric materials

A bilayer beam model constructed using two-phase piezoelectric materials is developed to study the fracture behavior of interfacial cracks under mechanical/electrical loading, in which the effects of electrostatic traction on the interfacial crack faces and the piezoelectricity of the materials are taken into account. An analytical solution is derived, and the energy release rate of the interfacial cracks is obtained. The electrostatic traction on the crack faces and the interfacial crack behavior are successfully simulated using the finite element method integrated with an iterative approach. The numerical and analytical solutions are compared and are found to agree with each other

Trapped thickness-shear modes in a contoured, partially electroded AT-cut quartz resonator

We perform a theoretical analysis of a contoured crystal plate resonator with nonuniform thickness. The resonator is made from AT-cut quartz and is partially electroded in the central region. Based on the variational formulation established in a previous paper and the Ritz method with trigonometric functions as basis functions, free vibration resonant frequencies and thickness-shear modes trapped in the central electroded region are obtained. The effect of the curvature of the contour is examined. It is also found that the classical frequency prediction given by Tiersten et al. in 1996 from an approximate analysis has an inaccuracy of the order of 40 parts per million for the fundamental mode, significant in resonator design and application

Dithionite promoted microbial dechlorination of hexachlorobenzene while goethite further accelerated abiotic degradation by sulfidation in paddy soil

It is of great scientific and practical importance to explore the mechanisms of accelerated degradation of Hexachlorobenzene (HCB) in soil. Both iron oxide and dithionite may promote the reductive dechlorination of HCB, but their effects on the microbial community and the biotic and abiotic mechanisms behind it remain unclear. This study investigated the effects of goethite, dithionite, and their interaction on microbial community composition and structure, and their potential contribution to HCB dechlorination in a paddy soil to reveal the underlying mechanism. The results showed that goethite addition alone did not significantly affect HCB dechlorination because the studied soil lacked iron-reducing bacteria. In contrast, dithionite addition significantly decreased the HCB contents by 44.0–54.9%, while the coexistence of dithionite and goethite further decreased the HCB content by 57.9–69.3%. Random Forest analysis suggested that indicator taxa (Paenibacillus, Acidothermus, Haliagium, G12-WMSP1, and Frankia), Pseudomonas, richness and Shannon’s index of microbial community, and immobilized Fe content were dominant driving factors for HCB dechlorination. The dithionite addition, either with or without goethite, accelerated HCB anaerobic dechlorination by increasing microbial diversity and richness as well as the relative abundance of the above specific bacterial genera. When goethite and dithionite coexist, sulfidation of goethite with dithionite could remarkably increase FeS formation and then further promote HCB dechlorination rates. Overall, our results suggested that the combined application of goethite and dithionite could be a practicable strategy for the remediation of HCB contaminated soil

Study on the Softening Mechanism and Control of Red-Bed Soft Rock under Seawater Conditions

Red-bed soft rock easily softens and disintegrates when it comes into contact with water, which is the main factor restricting the application of soft rock as an engineering filler. Therefore, research on the influence of seawater on soft rock softening has great significance for the application of soft rock in marine engineering. To examine the softening mechanism of soft rock under seawater conditions, two kinds of soft rock softening experiments, as well as ion inhibition tests of soft rock softening, were performed under seawater and pure water conditions, and the results were compared. The variation in the soft rock composition, the deformation and failure characteristics of soft rock under the influence of sea water, and the variation in main cations in the softening process of soft rock are examined successively; the influences of different ions on soft rock softening are further analysed. Based on the analyses, the softening mechanism and control method of soft rock under sea water conditions are expounded. The study showed that soft rock softening was inhibited by seawater, which decreased the softening degree of soft rock. The main cations in seawater had an inhibitory effect on soft rock softening, and the order of inhibition was Ca2+ > Mg2+ > Na+. According to the inhibitory effect of ions on soft rock softening, we propose that seawater or calcium salt should be added to reduce the softening of soft rock in soft rock engineering and improve the mechanical strength of soft rock; in addition, soft rock can be considered a raw material in marine engineering. The experimental results have great significance for studies of the disintegration mechanism and inhibitory rules of soft rock under the influence of seawater and provide a theoretical basis for the application of soft rock in marine engineering, such as in artificial reef engineering and coastal dike engineering

Analysis solution method for 3D planar crack problems of two-dimensional hexagonal quasicrystals with thermal effects

An analysis solution method (ASM) is proposed for analyzing arbitrarily shaped planar cracks in two-dimensional (2D) hexagonal quasicrystal (QC) media. The extended displacement discontinuity (EDD) boundary integral equations governing three-dimensional (3D) crack problems are transferred to simplified integral-differential forms by introducing some complex quantities. The proposed ASM is based on the analogy between these EDD boundary equations for 3D planar cracks problems of 2D hexagonal QCs and those in isotropic thermoelastic materials. Mixed model crack problems under combined normal, tangential and thermal loadings are considered in 2D hexagonal QC media. By virtue of ASM, the solutions to 3D planar crack problems under various types of loadings for 2D hexagonal QCs are formulated through comparison to the corresponding solutions of isotropic thermoelastic materials which have been studied intensively and extensively. As an application, analytical solutions of a penny-shaped crack subjected uniform distributed combined loadings are obtained. Especially, the analytical solutions to a penny-shaped crack subjected to the anti-symmetric uniform thermal loading are first derived for 2D hexagonal QCs. Numerical solutions obtained by EDD boundary element method provide a way to verify the validity of the presented formulation. The influences of phonon-phason coupling effect on fracture parameters of 2D hexagonal QCs are assessed.This work is supported by the National Natural Science Foundation of China (Grant nos. 11272290 and 11572289) and the State Scholarship Fund from the China Scholarship Council (Grant no. 201707040015

Ginsenoside Rh3 Inhibits Lung Cancer Metastasis by Targeting Extracellular Signal-Regulated Kinase: A Network Pharmacology Study

Lung cancer has a high mortality rate and is very common. One of the main reasons for the poor prognosis of patients with lung cancer is the high incidence of metastasis. Ginsenoside Rh3, a rare ginsenoside extracted from Panax notoginseng, exhibits excellent anti-inflammatory and anti-tumor effects. Nonetheless, the inhibitory potential of Rh3 against lung cancer remains unknown. The target genes of Rh3 were screened by the PharmMapper database; the proliferation of lung cancer cells was detected by MTT assay; the migration and invasion of cells were detected by the Transwell method; and the expression of extracellular signal-regulated kinase (ERK) and EMT-related proteins in vivo and in vitro were detected by Western blotting. In addition, we established a lung metastasis model in nude mice using A549 cells to assess the effect of Rh3 on NSCLC tumor metastasis in vivo. Our findings suggest that Rh3 significantly inhibited lung cancer metastasis both in vivo and in vitro. It was determined by flow cytometry analysis that Rh3 notably inhibited cell proliferation by blocking the G1 phase. In addition, Rh3 inhibited metastasis in lung cancer cells and regulated the expression of metastasis-related proteins under hypoxia. Mechanistic studies suggested that Rh3 targeted ERK to inhibit lung cancer metastasis. The ERK inhibitor U0126 or siRNA-mediated knockdown of ERK had an enhanced effect on Rh3’s ability to inhibit lung cancer metastasis. The studies revealed that the inhibitory effect of Rh3 on the metastatic ability of lung cancer cells may be supported by ERK-related signaling pathways

Indentation stress in multi-layer delaminated thin films induced by a microwedge indenter

Indentation stresses in single- and multi-layer delaminated thin films made of elastic-perfectly plastic materials in microwedge indentation delamination tests are analyzed via finite element calculations with different wedge angles and other geometrical and mechanical parameters. Based on the formula for a single-layer thin film under indentation loading [Zhao et al. J Mater Res 2009;24:1943] and by introducing the equivalent material parameters, we developed simple analytical formulae for the loading indentation stress (as well as the energy release rate) in each layer of the multi-layer thin film, in terms of the residual stress, elastic modulus, Poisson's ratio, yielding strength, and thickness of each layer. Our analytical solution is validated by the finite element calculations and should be useful to thin-film delamination tests. (c) 2012 Elsevier Ltd. All rights reserved

A nonlinear bilayer beam model for an interfacial crack in dielectric bimaterials under mechanical/electrical loading

A bilayer beam model is extended to study the fracture behavior of dielectric interfacial cracks. In this model, a semi-infinite crack with an original opening value is oriented along the interface between two dielectric layers which are under mechanical/electrical loading. Taking into account the effect of the electrostatic traction on the interfacial crack, a nonlinear analytical solution is derived, along with also a developed finite element analysis method where a special constitutive equation for the capacitor element in ANSYS is utilized to simulate the electrostatic tractions. Both the analytical and numerical solutions predict the same results which further show that the elastic and dielectric mismatches can play a significant role in the interfacial cracking behavior under mechanical and electrical loading. Furthermore, the electrostatic tractions may cause hysteresis loops in the curve of crack opening versus applied mechanical displacement or versus applied electric voltage. An applied mechanical load is the driving force for the interfacial cracking, while an applied electric field retards it