Using Fuzzy C-Means Clustering to Determine First Arrival of Microseismic Recordings.

Accurate and automatic first-arrival picking is one of the most crucial steps in microseismic monitoring. We propose a method based on fuzzy c-means clustering (FCC) to accurately divide microseismic data into useful waveform and noise sections. The microseismic recordings' polarization linearity, variance, and energy are employed as inputs for the fuzzy clustering algorithm. The FCC produces a membership degree matrix that calculates the membership degree of each feature belonging to each cluster. The data section with the higher membership degree is identified as the useful waveform section, whose first point is determined as the first arrival. The extracted polarization linearity improves the classification performance of the fuzzy clustering algorithm, thereby enhancing the accuracy of first-arrival picking. Comparison tests using synthetic data with different signal-to-noise ratios (SNRs) demonstrate that the proposed method ensures that 94.3% of the first arrivals picked have an error within 2 ms when SNR = -5 dB, surpassing the residual U-Net, Akaike information criterion, and short/long time average ratio approaches. In addition, the proposed method achieves a picking accuracy of over 95% in the real dataset tests without requiring labelled data.

Modifying the Power and Performance of 2-Dimensional MoS2 Field Effect Transistors.

Over the past 60 years, the semiconductor industry has been the core driver for the development of information technology, contributing to the birth of integrated circuits, Internet, artificial intelligence, and Internet of Things. Semiconductor technology has been evolving in structure and material with co-optimization of performance-power-area-cost until the state-of-the-art sub-5-nm node. Two-dimensional (2D) semiconductors are recognized by the industry and academia as a hopeful solution to break through the quantum confinement for the future technology nodes. In the recent 10 years, the key issues on 2D semiconductors regarding material, processing, and integration have been overcome in sequence, making 2D semiconductors already on the verge of application. In this paper, the evolution of transistors is reviewed by outlining the potential of 2D semiconductors as a technological option beyond the scaled metal oxide semiconductor field-effect transistors. We mainly focus on the optimization strategies of mobility (µ), equivalent oxide thickness (EOT), and contact resistance (RC ), which enables high ON current (Ion ) with reduced driving voltage (Vdd ). Finally, we prospect the semiconductor technology roadmap by summarizing the technological development of 2D semiconductors over the past decade.

Study on the Thermal Conductivity Characteristics for Ultra-Thin Body FD SOI MOSFETs Based on Phonon Scattering Mechanisms.

The silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) suffer intensive self-heating effects due to the reduced thermal conductivity of the silicon layer while the feature sizes of devices scale down to the nanometer regime. In this work, analytical models of thermal conductivity considering the self-heating effect (SHE) in ultra-thin body fully depleted (UTB-FD) SOI MOSFETs are presented to investigate the influences of impurity, free and bound electrons, and boundary reflection effects on heat diffusion mechanisms. The thermal conductivities of thin silicon films with different parameters, including temperature, depth, thickness and doping concentration, are discussed in detail. The results show that the thermal dissipation associated with the impurity, the free and bound electrons, and especially the boundary reflection effects varying with position due to phonon scattering, greatly suppressed the heat loss ability of the nanoscale ultra-thin silicon film. The predictive power of the thermal conductivity model is enhanced for devices with sub-10-nm thickness and a heavily doped silicon layer while considering the boundary scattering contribution. The absence of the impurity, the electron or the boundary scattering leads to the unreliability in the model prediction with a small coefficient of determination.

Interaction of Wnt/ß-catenin and notch signaling in the early stage of cardiac differentiation of P19CL6 cells.

Notch and Wnt/ß-catenin signaling both play essential roles and interact closely in cardiomyocyte differentiation but the mechanism of interaction is largely unknown. Here we show that activation of Notch signaling in undifferentiated P19CL6 cells promoted cardiac differentiation, indicated by upregulated expression of early cardiac markers and activated the canonical Wnt pathway, suggested by augmented nuclear translocation of ß-catenin. Further activation of the Notch pathway in early differentiating cells (at day 3) inhibited expression of a specific cardiac progenitor marker Islet1 but had no influence on ß-catenin translocation. Notch signaling thus played biphasic roles in the early stage of cardiomyocyte differentiation and Wnt/ß-catenin signaling. Unlike Notch signaling, Wnt signaling promoted cardiomyocyte differentiation and activated the Notch pathway in either undifferentiated or early differentiating cells. Additionally, ß-catenin, recombination signal sequence binding protein-Jkappa (RBP-Jκ), and Notch1 intracellular domain (NICD-1) formed a transcriptional complex which was recruited to the Hes1 promoter region, indicating direct transcriptional regulation of Hes1. We thus document a specific reciprocal interaction between these two signaling pathways during early stage cardiac differentiation of P19CL6 cells.

Inhibitor of DNA binding 1 (Id1) induces differentiation and proliferation of mouse embryonic carcinoma P19CL6 cells.

The inhibitor of DNA binding (Id) family of genes encodes negative regulators of basic helix-loop-helix transcription factors and has been implicated in such diverse cellular processes as differentiation, proliferation, apoptosis and migration. Id knockout mouse embryos display multiple cardiac defects but the specific role of Id1 in cardiac differentiation is unclear. In the present study, we investigated the function of Id1 in DMSO-induced P19CL6 cells, a widely-accepted cell model of cardiac differentiation. We found that Id1 was upregulated during the cardiac differentiation of P19CL6 cells. The expression of cardiac specific marker genes, Gata4, α-MHC and ISL1, was upregulated in P19CL6 cells stably transfected with Id1 (P19CL6-Id1) during cardiac differentiation. The overexpression of Id1 reduced the number of cells in G1 phase and increased the cell population in G2, M and S phases, while knockdown of Id1 increased the number of cells in G1 phase from 48.6 ± 2.51% to 62.2 ± 1.52% at day 0 of cardiac induction, and from 52.5 ± 3.41% to 63.7 ± 1.02% at day 3 after cardiac induction, indicating that Id1 promoted proliferation of P19CL6 cells. Luciferase assays showed that the activity of TOP flash was higher in P19CL6-Id1 cells than wildtype P19CL6 cells, while Id1 expression was also upregulated in P19CL6 cells treated with Wnt3a or LiCl. This indicates that there may be positive feedback between Id1 and Wnt signaling which plays an important role in cardiac differentiation.

beta-Catenin/TCF/LEF1 can directly regulate phenylephrine-induced cell hypertrophy and Anf transcription in cardiomyocytes.

beta-Catenin/TCF/LEF1 signaling is implicated in cardiac hypertrophy. We demonstrate that knockdown of beta-catenin attenuates phenylephrine (PE)-induced cardiomyocyte hypertrophy and the up-regulation of the fetal gene Anf. We explore the mechanism through which beta-catenin regulates Anf expression and find a consensus binding sequence on the Anf promoter for TCF/LEF1 family members. LEF1 binds directly to the Anf promoter via this sequence, which shows functional significance, and PE stimulation enhances recruitment of beta-catenin onto the Anf promoter. Thus, we document a direct positive role of beta-catenin on PE-induced cardiomyocyte hypertrophy and identify a new target gene for beta-catenin/TCF/LEF1.