Constitutive Equations of Piezoelectric Layered Beams With Interdigitated Electrodes.

This paper establishes the constitutive equations, or linear two-port models, of piezoelectric layered beams with interdigital electrodes (IDEs). The effect of the nontrivial field on the transduction is analyzed. Based on conformal mapping techniques, we derive new analytic expressions for the capacitance, the electric field, and the electromechanical coupling factor of an anisotropic dielectric with the IDE configuration on top. The IDE capacitance with an anisotropic permittivity can be treated as the one with an isotropic permittivity. The complex expression for the nonuniform field is simplified to a quadratic form. A correction is required for the transducer's coupling constant. All modifications are expressed analytically. The analytic models are verified against the finite element method. Finally, the two-port models help to compare the devices with other electrode configurations, such as beams with a top and bottom electrode.

Actuation of Piezoelectric Layered Beams With and Coupling.

In this paper, we derive and compare the linear static bending of piezoelectric actuators with transversal ( ) and longitudinal ( ) coupling. The transducers are, respectively, structures utilizing top and bottom electrodes (TBEs) and interdigitated electrodes (IDEs). While the theory is well developed for the TBE beam, governing equations for the bending of the piezoelectric beams with IDEs are far less developed. We improve on this by deriving the governing equation for the IDE beam with an arbitrary number of layers and with coupling consistently included. In addition, we introduce a phenomenological quadratic form for the nonuniform field that lets us derive a deflection formula with nontrivial effects of the field accounted for. The theory is applied to derive deflection formulas for both cantilever and clamped-clamped beams. All analytic results are validated with numerical simulations. From the analytic models, two different figures of merit (FOMs) are derived. We show that these FOMs are the same for cantilevers and doubly clamped beams. The analysis indicates the optimal transducer length for clamped-clamped beams and gives a criterion that can be used to determine which design concept ( or ) gives the largest deflection.

A functional polymorphism in the NKG2D gene modulates NK-cell cytotoxicity and is associated with susceptibility to Human Papilloma Virus-related cancers.

Human papillomavirus (HPV) is the most common sexually transmitted agent worldwide and is etiologically linked to several cancers, including cervical and genital cancers. NKG2D, an activating receptor expressed by NK cells, plays an important role in cancer immune-surveillance. We analyzed the impact of a NKG2D gene variant, rs1049174, on the incidence of HPV-related cancers in Vietnamese patients and utilized various molecular approaches to elucidate the mechanisms of NKG2D receptor regulation by rs1049174. In a group of 123 patients with HPV+ anogenital cancers, the low cytotoxicity allele LNK was significantly associated with increased cancer susceptibility (p = 0.016). Similar results were also observed in a group of 153 women with cervical cancer (p = 0.05). In functional studies, NK cells from individuals with LNK genotype showed a lower NKG2D expression and displayed less efficient NKG2D-mediated functions than NK cells with HNK genotype. Notably, the rs1049174 variant occurs within a targeting site for miR-1245, a negative regulator of NKG2D expression. Compared with the higher cytotoxicity allele HNK, the LNK allele was more efficiently targeted by miR-1245 and thus determined lower NKG2D expression in NK cells with the LNK genotype. The NKG2D variants may influence cancer immunosurveillance and thus determine susceptibility to various malignancies, including HPV-induced cancers.