Search

The cross-well dynamic of the bi-stable laminates triggered by ambient vibration is a typical nonlinear dynamic, the larger deformation makes the bi-stable laminates attract much attention in vibration energy harvesting. To obtain the performance of cross-well dynamics and vibration energy harvesting of the bi-stable laminate theoretically, a 4-layer harmonic base-excited antisymmetric cross-ply bi-stable laminates with d31 type Marco fiber composite (MFC) for vibration energy harvesting is proposed. The bi-stable laminate is fixed at a chosen point where a base excitation is applied as displacement excitation. The first order shear deformation laminated plate theory (FSDT), geometric nonlinear, and the energy principle are employed to obtain the governing equation of the system in terms of the polynomial coefficients of configuration functions. Two stable configurations are calculated by the principle of minimum potential energy, which is used as the initial state for the energy harvesting analysis. The stable configurations are predicted, and evaluated by comparing them with ABAQUS. The cross-well nonlinear dynamic behaviors and the performance of energy harvesting are analyzed. The effects of excitation level, excitation frequency, and the position of the fixed point on the cross-well dynamics and energy harvest characteristics of the antisymmetric bi-stable laminates are investigated in-depth, and some new aspects are revealed. It demonstrates that the base displacement harmonic excitation can induce chaotic cross-well vibration in a high-frequency band when the fixed point is far away from the center point, the various cross-well vibration of the system is more likely to occur in the dominate-frequency resonant band. [ABSTRACT FROM AUTHOR]

To obtain position and size information about obstacles inside a reservoir culvert, and to make it convenient for pipeline robots to adjust their postures in real time to continue moving, we propose an obstacle detection method based on circular structured light suitable for the characteristics of reservoir culverts. Using a method of calibrating the circular structured light of a planar target, the equation of the circular structured light surface in the camera coordinate system is obtained. According to the measurement principle of structured light, the inner wall of the reservoir culvert is scanned by laser to obtain three-dimensional (3-D) information on the surface, and the position and size of the obstacles within the culvert are determined. The results show that the calibration error of circular structured light is less than 0.1 mm, which fulfils the requirements of obstacle detection in reservoir culverts. The obstacle detection method based on circular structured light can simultaneously detect the spatial position and size of obstacles inside the reservoir culvert, and the detection error rate is less than 5%, which is generally lower than that of other obstacle detection methods. Our results demonstrate that the proposed method can be applied to the detection of obstacles inside reservoir culverts. [ABSTRACT FROM AUTHOR]

We found that the exciton-phonon coupling in the Zn1-xMgxO powders (0.01 <= x <= 0.07) is greatly influenced by the crystalline-size. Two well-resolved photoluminescence (PL) bands due to recombination of free exciton and its longitudinal optical (LO)-phonon replicas enable us to analyze the relative intensities among free excitons, one-LO-phonon replicas, and two-LO-phonon replicas. As crystalline size increases, a larger enhancement of the PL-intensity ratio of a free exciton to its LO-phonon replicas was found compared to that of two LO-phonon replica to one-LO-phonon replica. [ABSTRACT FROM AUTHOR]

N6-methyladenosine (m6A) has been identified as a conserved epitranscriptomic modification of eukaryotic mRNAs, and plays important biological roles in the regulation of cellular metabolic processes. However, its role in myogenic differentiation is unclear. Here, we altered the m6A RNA methylation level by overexpression of METTL3, and explored the effect of m6A RNA methylation on myogenic differentiation of murine myoblasts in vitro. The m6A RNA methylation level is regulated by exogenous methylation inhibitor cycloleucine (Cyc) and methyl donor betaine (Bet). Therefore, chemical reagents of Cyc and Bet were used to test the regulatory effect of m6A RNA methylation on myogenic differentiation. Results showed that METTL3 and Bet positively regulated the m6A RNA methylation levels, and Cyc negatively regulated m6A RNA methylation levels. In addition, m6A methylation positively regulated myogenic differentiation in murine myoblasts. These findings provide insight in the mechanisms underlying the effect of m6A RNA methylation on myogenesis. [ABSTRACT FROM AUTHOR]

Time-of-flight (TOF) spectra of the scattered and recoiled particles resulting from 1–10 keV He+, Ne+, Ar+, Kr+, and Xe+ ions impingent on surfaces of LiF thin films have been obtained. Measurements of directly recoiled (DR) neutrals plus ions and neutrals alone are used to calculate positive and negative ion fractions Y+,- from DR events. The oppositely charged ion fractions have a distinctly different behavior as a function of kinetic energy. The Y+ values exhibit a threshold at low energy followed by a plateau region at higher energy while the Y- values are maximum in the low energy region followed by a decreasing yield as energy increases. The energy dependence of Y+,- is interpreted in terms of the recently developed model [J. Chem. Phys. 85, 3615 (1986)] for electronic charge exchange in keV ion/surface collisions which considers electron promotions in the close atomic encounter and resonant and Auger transitions along the outgoing trajectory. The ionization potential of the primary ion relative to the energy levels of the target atom is shown to have a large influence on charge exchange in the close encounter. The ratio of direct recoil to scattering particle flux increases by a factor of >102 from He to Xe; scattering and recoil cross sections are used to model this process. [ABSTRACT FROM AUTHOR]

Eph receptors and their cell-surface-bound ligands, the ephrins, are known to regulate axon guidance in the developing brain, modulate vascular remodeling and play an important role in somite formation. The eph/ephrin signaling system is proposed to mediate repulsive cell contact-dependent interactions that results in the proper maintenance of discrete domains essential for pattern formation in embryonic development. We are interested in the bi-directional signaling properties of the class B ephrins and their role in the developing zebrafish embryo. The ephrin B ligands are transmembrane proteins capable of transducing signals in the ligand cell, in addition to initiating a signal in the receptor cell. We found that zebrafish ephrin B proteins are tyrosine phosphorylated in vivo, as early as mid-gastulation, suggesting that bi-directional signaling is required for embryonic development. To investigate this further, we have identified 4 members of the class B ephrins in the zebrafish. Each ligand is expressed in discrete domains as the embryo develops. Ephrin B ligands are expressed in the early gastrula, in the germ ring and shield, suggesting essential roles in early development, perhaps in co-ordinating cellular movements during gastrulation. We examined the functional roles of these proteins by injection of mRNA, encoding dominant negative forms of ephrin B proteins. Interruption of eph signaling resulted in dramatic phenotypes indicative of gastrulation problems. Our analysis demonstrates that disruption of eph signaling perturbs prechordal plate movement during gastrulation. In addition to eph/ephrin roles in later developmental events, our study points to an important early role for eph signaling. This study provides further evidence to support an essential role for bi-directional signaling of ephrin B proteins.

Purpose: The aim was to evaluate the effectiveness of cervical screening when HPV DNA testing is implemented. Materials and Methods: Medline (PubMed) was searched and experts were contacted for references. Odds ratio (OR) and 95% confidence intervals (CI) were used as measures of effect sizes. Results: The rate of CIN3 and worse decreased about twofold, from 1.19% in round 1 to 0.67% in round 2, and CIN2 decreased from 1.70% in round 1 to 0.80% in round 2. When primary cervical screening with LBC was combined with HPV testing, there was a statistically significant reduction in the detection of CIN2 and CIN3+ at the next screening round compared with liquid-based cytology (LBC) alone. Conclusions: HPV DNA-based screening is more effective than cytology in CIN3 and invasive cervical cancers, by detecting persistent high-grade lesions earlier, and providing a longer low-risk period. However, in younger women, HPV screening leads to over-diagnosis of regressive CIN2. [ABSTRACT FROM AUTHOR]

Multi-LED colour mixing light sources are increasingly being used in lighting. The method used to set the dimming signal needs to accurately achieve and sustain the desired colour temperature and high colour rendering index (CRI). A pulse width modulation (PWM) signal is always used in LED colour mixing. But the PWM switch state creates a time delay in the multi-LED current regulator, resulting in a colour difference. A modified PWM signal to accurately maintain the desired colour temperature and a high CRI is derived from a parameterised LED current regulator switch state, using curve fitting. The modified PWM signal can be calculated from reconstructed coefficients of the illuminant spectrum. [ABSTRACT FROM PUBLISHER]