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In this paper, a size-dependent Euler–Bernoulli beam model, which takes the flexoelectricity, piezoelectricity, and dielectricity as well as the surface elasticity into consideration, is established. Theoretical solutions for the static bending deflection of thin beams under different loading (uniformly distributed and concentrated load) and boundary conditions (cantilevered, both ends simply supported, clamped–clamped), are established. Moreover, an iterative finite element algorithm is developed for the analysis of thin flexoelectric beams under any load and boundary conditions. Our numerical results show the direct bulk flexoelectricity always play the role of stiffening the beams with various boundary conditions, while the residual surface stresses behave either stiffening or softening the nanobeams dependent on boundary conditions. The present investigation also demonstrates the size-dependent effects of flexoelectricity on the bending rigidity and piezoelectricity. [ABSTRACT FROM AUTHOR]

Background: Glutathione peroxidase (GPX) 4 and selenoprotein P (SELENOP) are abundant, and several variants are expressed in the testis.Objective: We determined the effects of dietary selenium deficiency or excess on sperm quality and expressions of GPX4 and SELENOP variants in rat testis and liver.Methods: After weaning, male Sprague-Dawley rats were fed a Se-deficient basal diet (BD) for 5 wk until they were 9 wk old [mean ± SEM body weight (BW) = 256 ± 5 g]. They were then fed the BD diet alone (deficient) or with 0.25 (adequate), 3 (excess), or 5 (excess) mg Se/kg for 4 wk. Testis, liver, blood, and semen were collected to assay for selenoprotein mRNA and protein abundances, selenium concentration, GPX activity, 8-hydroxy-deoxyguanosine concentration, and sperm quality.Results: Dietary selenium supplementations elevated (P < 0.05) tissue selenium concentrations and GPX activities. Compared with those fed BD + 0.25 mg Se/kg, rats fed BD showed lower (P < 0.05) BW gain (86%) and sperm density (57%) but higher (P < 0.05) plasma 8-hydroxy-deoxyguanosine concentrations (189%), and nonprogressive sperm motility (4.4-fold). Likewise, rats fed BD + 5 mg Se/kg had (P = 0.06) lower BW gain and higher (1.9-fold) sperm deformity rates than those in the selenium-adequate group. Compared with the selenium-adequate group, dietary selenium deficiency (BD) or excess (BD + 3 or 5 mg Se/kg) resulted in 45-77% lower (P < 0.05) nuclear Gpx4 (nGpx4) mRNA abundance in the testis. Rats fed BD had lower (P < 0.05) mRNA levels of 2 Selenop variants in both testis and liver than those in the other groups. Testicular SELENOP was 155-170% higher (P < 0.05) in rats fed BD + 5 mg Se/kg and hepatic c/mGPX4 was 13-15% lower (P < 0.05) in rats fed BD than in the other groups.Conclusions: The mRNA abundance of rat testicular nGPX4 responded to dietary selenium concentrations in similar ways to sperm parameters and may be used as a sensitive marker to assess appropriate Se status for male function. [ABSTRACT FROM AUTHOR]

The present paper derives a 3-D finite element formulation and an iterative algorithm for multiphysics analysis of coupled anomalous photovoltaic, photo-thermal and pyroelectric effects in PbLaZrTi (PLZT) ceramics. The distinction in the computation aspects of electrical potential, electrical field strength and electrical charge for 0-1 and 0-3 polarized PLZT wafers are discussed thoroughly. The element performance is improved by using an assumed natural strain approach and an enhanced assumed strain method. The transverse displacements of a bimorph 0-1 polarized PLZT actuator were predicted using the present finite element formulation and then verified with the existing analytical solution and experimental results. The static analysis of a cantilevered beam bonded with a 0-1 or 0-3 polarized PLZT actuators was also presented and compared with the theoretical solutions. The numerical simulations demonstrate that the present formulations and algorithm possess superior performance. [ABSTRACT FROM AUTHOR]

In order to solve for the mode intensity distributions in a photonic crystal fiber (PCF) cross section and the propagation constant for the design of fiber bandpass filters, we numerically analyze the modal distributions of the fundamental core mode and different cladding modes. Based on the simulation results, we also experimentally demonstrate a simple fabrication of bandpass filters inscribed on the PCF by inserting a π-phase shift in a 12-period long-period grating (LPG). Two rejection bands with greater than 18 dB isolation and an ultra-wide band of 85.3 nm are achieved. The phase-shifted PCF-LPGs are fabricated using a CO2 laser with point-by-point focused pulses. The proposed fiber bandpass filter is compact and is not influenced by temperature effects. [ABSTRACT FROM AUTHOR]

This study deals with a method to identify multiple cracks in a beam. The novelty of this study is the use of a hierarchical genetic algorithm to detect the number, location, and the extent of multiple cracks. To demonstrate the feasibility of the present method, this algorithm is applied to the identification of double or triple cracks in a beam as well as four cracks. The detected crack locations and sizes are in excellent agreement with the actual ones. The numerical simulation reveal the HGA substantially reduces the total number of FE computation required and they are many orders smaller compared to conventional GA. The results also demonstrate the advantages of HGA from the viewpoints of its ability to avoid premature convergence. [ABSTRACT FROM AUTHOR]

Abstract: The lanthanum-modified lead zirconate titanate (PLZT) actuator, which are capable of converting photonic energy to mechanical motion, have great potential in applications of remote structural vibration control of smart structures and machines. In this paper, a novel genetic algorithm based controlling algorithm for multi-modal vibration control of beam structures via photostrictive actuators is proposed. Two pairs of photostrictive actuators are laminated with the beams and the alternation of light irradiation is in accordance with the changing of the corresponding modal velocity direction. The modal force indexes for beams with different boundary conditions are derived and a binary-coded GA is used to optimize the locations and sizes of photostrictive actuators to maximize the modal force index and guarantee the overall modal force index induced by two pairs of photostrictive actuators is positive. The control effect of multiple vibration modes of beams under irradiation of set/variable light intensity is analyzed. Numerical results demonstrate that the method is robust and efficient, and the use of strategically positioned actuator patches can effectively control the first two bending modes that dominate the structural vibration. [Copyright &y& Elsevier]

Purpose: To compare the function and morphology of the meibomian glands and the ocular surface of individuals from highland and lowland. Methods: This was a randomized controlled trial. The study was performed with 104 individuals (51 individuals from the highland and 53 individuals from the lowland). Detailed eye examinations comprising tear meniscus height, lipid layer grading, non‑invasive Keratograph tear breakup time (NIKBUT), and scoring of the meibomian glands from the upper and lower eyelids of the individuals were performed by Keratograph 5M (OCULUS, Wetzlar, Germany). Symptoms related to dry eye disease were assessed using the Ocular Surface Disease Index (OSDI). Results: In the highland group, tear meniscus height was lower (P = 0.024), lipid layer grade, as well as all the meiboscores were higher (P < 0.05) than that in the lowland group. The OSDI (P = 0.018) and the percentage of dry eye disease were also higher as compared to that of the lowland group (P = 0.032). The first NIKBUT and average NIKBUT did not differ significantly between groups. The frequency of plugged meibomian gland orifices was greater in the lowland group compared to the highland group (P = 0.036). Conclusion: It was observed that dry eye disease was more common in the highland group. The morphological changes of meibomian gland dropout were significant in highlanders as demonstrated objectively with Keratograph 5M. Our study may raise a concern for environmental influences on ocular surface changes. [ABSTRACT FROM AUTHOR]

This paper presents a new interface technique called synchronous charge extraction and voltage inversion (SCEVI), which consists of a synchronous inductor and a buck-boost converter for vibration-based energy harvesting using piezoelectric elements. The theoretical calculation of the harvested power obtained by using such a technique are proposed and compared with the so-called Standard, SECE (Synchronous Electric Charge Extraction), Parallel-SSHI (Parallel Synchronized Switch Harvesting on Inductor) and Series-SSHI (Series Synchronized Switch Harvesting on Inductor) methods commonly used in piezoelectric vibration-powered generator considering both constant displacement amplitude and force amplitude. From the harvested power point of view, SCEVI and Parallel -- SSHI techniques are the better ones and each has its own merits. But the harvested power of SCEVI is independent of the load connected to the generator and Parallel -- SSHI depend on the load resistance. The harvested power of SECE is also independent of the load, but the further experimental results show that the proposed SCEVI interface technique dramatically increases the harvested power by almost up to 150% compared with the SECE method under the same amplitude of displacement excitation. [ABSTRACT FROM AUTHOR]

An innovative method based on dynamic particle swarm optimization (DPSO) algorithm is presented to demodulate the strain profile along a fiber Bragg grating (FBG) from its reflection spectrum, which is calculated by using the modified transfer matrix method. To improve the optimization performances of algorithm itself, the inertia weight of the DPSO algorithm is adjusted dynamically according to the distance between the individual particle and the global optimal particle in the current population. Then the numerical simulation and experimental verification of the reconstruction of nonuniform strain profiles are comprehensively carried out. Both the simulation examples and experimental results verify the feasibility and validity of the present method. [ABSTRACT FROM AUTHOR]

In order to study the deformation of the nuclei which belongs to the transitional region between strongly deformed and spherical nuclei, the calculations of the total Routhian surfaces by means of the pairing-deformation-frequency self-consistent cranked shell model were carried out in order to investigate shape evolution in even-mass Os and Pt isotopes (176–202Os and 182–204Pt) starting from the static nuclear ground states. It is found that some nuclear ground states such as in 196Os and 188–194Pt are neither oblate nor prolate. Instead, the ground-state minima in these nuclei are axially asymmetric in shape. In addition, a complementary approach is used to extract equilibrium γ0 value (nonaxially symmetric equilibrium shape parameter), which support our predictions. [ABSTRACT FROM AUTHOR]