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A frequency-tunable patch antenna with reduced radar cross section (RCS) based on absorbing metamaterial is proposed. By controlling the external voltage of the varactor diodes, the working frequency of the patch can be adjusted. Through an investigation of the composite structure of the patch and absorbing metamaterial, RCS reduction is achieved over the entire wide tunable frequency range of the antenna. Measured results illustrate that the proposed patch antenna can dynamically operate in the range from 2.28 to 3.6 GHz with a gain variation of 7.1–8.7 dBi. Meanwhile, the RCS can be reduced by at least 7 dB and up to 20 dB in a fractional bandwidth of 44.9% of the antenna under a normal incidence. In comparison to conventional RCS-reduced antennas, the proposed one features a broader frequency tuning range and has potential value in wideband radar systems under complex electromagnetic interference environments. [ABSTRACT FROM AUTHOR]

The traditional design method for terahertz metasurface biosensors is cumbersome and time-consuming, requires expertise, and often leads to significant discrepancies between expected and actual values. This paper presents a novel approach for the fast, efficient, and convenient inverse design of THz metasurface sensors, leveraging convolutional neural network techniques based on deep learning. During the model training process, the magnitude data of the scattering parameters collected from the numerical simulation of the THz metasurface served as features, paired with corresponding surface structure matrices as labels to form the training dataset. During the validation process, the thoroughly trained model precisely predicted the expected surface structure matrix of a THz metasurface. The results demonstrate that the proposed algorithm realizes time-saving, high-efficiency, and high-precision inversion methods without complicated data preprocessing and additional optimization algorithms. Therefore, deep learning algorithms offer a novel approach for swiftly designing and optimizing THz metasurface sensors in biomedical detection, bypassing the complex and specialized design process of electromagnetic devices, and promising extensive prospects for their application in the biomedical field. [ABSTRACT FROM AUTHOR]

A simple scheme for the realization of the terahertz (THz) fundamental-mode closed-stopband composite right/left-handed leaky-wave antennas (CRLH LWAs) is presented. The proposed CRLH LWAs are reconstructed by graphene-based coplanar waveguide (CPW) transmission line supercells. Their shunt inductances achieved by narrow graphene strips of two unit cell structures are halved. The CRLH LWAs are designed and confirmed by numerical simulations. They also exhibit frequency-scannable behaviors at THz with narrower bandwidth than that of the conventional graphene-based fundamental-mode CPW unit cell CRLH LWAs at THz without stopbands. Therefore, the proposed supercell CRLH LWAs could further improve the performance of the beam-steering antennas at THz.

With the development of large gradient wells and horizontal wells, resistivity anisotropy has become an important concern. Most of the inversion problems encountered in geophysical applications are time-consuming. In this letter, we propose a novel approach based on deep learning (DL) to solve the time-consuming problem of the inversion of induction logging data in layered anisotropic formation. A deep neural network (DNN) architecture combined with an adaptive moment estimation (Adam) optimization algorithm is utilized. Batch normalization is used to accelerate the training convergence. Data sets are obtained from forward modeling in different anisotropic formations, by which the DNN is trained, validated, and tested. A series of experiments are carried out to test the accuracy, robustness, and speed of the inversion based on DL in the anisotropic formation. The experimental results indicate that the approach based on DL can achieve the inversion with high accuracy. Furthermore, the trained DNN model for the inversion is two orders of magnitude faster than the most commonly used nonlinear iterative algorithm that achieves the same inversion precision. The trained DNN model considerably reduces the inversion computation time without compromising accuracy. Moreover, the approach overcomes the defect of the dependence of the nonlinear iterative algorithm on the initial values. Our study has shown the promising potential of the approach based on DL for inverting the logging data in anisotropic formations that are difficult to quickly invert by the conventional method. [ABSTRACT FROM AUTHOR]

TP53 is the most frequently mutated tumor suppressor gene in human cancer. The majority of mutations of p53 are missense mutations, leading to the expression of the full length p53 mutant proteins. Mutant p53 (Mutp53) proteins not only lose wild-type p53-dependent tumor suppressive functions, but also frequently acquire oncogenic gain-of-functions (GOF) that promote tumorigenesis. In this review, we summarize the recent advances in our understanding of the oncogenic GOF of mutp53 and the potential therapies targeting mutp53 in human cancers. In particular, we discuss the promising drugs that are currently under clinical trials as well as the emerging therapeutic strategies, including CRISPR/Cas9 based genome edition of mutant TP53 allele, small peptide mediated restoration of wild-type p53 function, and immunotherapies that directly eliminate mutp53 expressing tumor cells. [ABSTRACT FROM AUTHOR]

In this paper, a simple terahertz (THz) leaky-wave antenna (LWA) composed of periodic gapped graphene ribbons and a silicon substrate is presented. The graphene sheets of the antenna operate in an electric field with a resonance distribution of transverse electric (TE) surface plasmon polaritons (SPPs). The THz LWA has both negative and positive propagation constant with the variation of frequencies. Thus, the LWA performs as a composite right/left-handed (CRLH) LWA with backfire-to-endfire beam steering capability in the THz band. The working principle of the THz LWA is analyzed in detail using the theory of dispersion relation formulae and the equivalent CRLH circuit model. The THz LWA is verified by numerical simulations, and the frequency scannable capability of the THz LWA is confirmed. The proposed antenna has great potential applications for the THz LWA of the radiation capability in the entire upper quadrants. [ABSTRACT FROM AUTHOR]

Logging while drilling (LWD) plays a crucial role in geo-steering, which can determine the formation boundary and resistivity in real time. In this study, an efficient inversion, which can accurately invert formation information in real time on the basis of fast-forward modeling, is presented. In forward modeling, the Gauss–Legendre quadrature combined with the continued fraction method is used to calculate the response of the LWD instrument in a layered formation. In inversion modeling, the Levenberg–Marquardt (LM) algorithm, combined with the line search method of the Armijo criterion, are used to minimize the cost function, and a constraint algorithm is added to ensure the stability of the inversion. A positive and negative sign is added to the distance parameter to determine whether the LWD instrument is located above or below the formation boundary. We have carried out a series of experiments to verify the accuracy of the inversion. The experimental results suggest that the forward algorithm can make the infinite integral of the Bessel function rapidly converge, and accurately obtain the response of the LWD instrument in a layered formation. The inversion can accurately determine the formation resistivity and boundary in real time. This is significant for geological exploration. [ABSTRACT FROM AUTHOR]

Metabolism plays critical roles in maintaining the homeostasis of cells. Metabolic abnormalities are often considered as one of the main driving forces for cancer progression, providing energy and substrates of biosynthesis to support neoplastic proliferation effectively. The tumor suppressor p53 is well known for its roles in inducing cell cycle arrest, apoptosis, senescence and ferroptosis. Recently, emerging evidence has shown that p53 is also actively involved in the reprogramming of cellular metabolism. In this review, we focus on recent advances in our understanding of the interplay between p53 and metabolism of glucose, fatty acid as well as amino acid, and discuss how the deregulation of p53 in these processes could lead to cancer., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Yu, Wu, Zhu and Xu.)

Differentiation of human embryonic stem cells into mesendoderm (ME) is directed by extrinsic signals and intrinsic epigenetic modifications. However, the dynamics of these epigenetic modifications and the mechanisms by which extrinsic signals regulate the epigenetic modifications during the initiation of ME differentiation remain elusive. In this study, we report that levels of histone H3 Lys-27 trimethylation (H3K27me3) decrease during ME initiation, which is essential for subsequent differentiation induced by the combined effects of activin and Wnt signaling. Furthermore, we demonstrate that activin mediates the H3K27me3 decrease via the Smad2-mediated reduction of EZH2 protein level. Our results suggest a two-step process of ME initiation: first, epigenetic priming via removal of H3K27me3 marks and, second, transcription activation. Our findings demonstrate a critical role of H3K27me3 priming and a direct interaction between extrinsic signals and epigenetic modifications during ME initiation., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)

The development of a functional placenta is largely dependent upon proper proliferation and differentiation of trophoblast stem cells (TSCs). Activin signaling has long been regarded to play important roles during this process, but the exact mechanism is largely unknown. Here, we demonstrate that the X chromosome gene BCL-6 corepressor (Bcor) is a critical downstream effector of activin to fine-tune mouse TSC fate decision. Bcor was specifically down-regulated by activin A in TSCs in a dose-dependent manner, and immediately up-regulated upon TSC differentiation. Knockdown of Bcor partially compensated for the absence of activin A in maintaining the self-renewal of TSCs together with FGF4, while promoting syncytiotrophoblast differentiation in the absence of FGF4. Moreover, the impaired trophoblast giant cell and spongiotrophoblast differentiation upon Bcor knockdown also resembled the function of activin. Reporter analysis showed that BCOR inhibited the expression of the key trophoblast regulator genes Eomes and Cebpa by binding to their promoter regions. Our findings provide us with a better understanding of placental development and placenta-related diseases., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)

BMP4 maintains self-renewal of mouse embryonic stem cells (ESCs) in collaboration with LIF. Here, we report the identification of a novel key BMP target gene, cochlin (Coch) in mouse ESCs. Coch can be significantly up-regulated by BMP4 specifically in ESCs but not in somatic differentiated cells, and this up-regulation is dependent on the BMP signaling mediators Smad1/5 and Smad4. Overexpression of Coch can partially substitute BMP4 to promote self-renewal of mouse ESCs together with LIF, whereas knockdown of Coch impairs self-renewal marker gene expression even in the presence of both BMP4 and LIF. Further studies showed that COCH could mimic BMP4 in repressing neural differentiation of mouse ESCs upon LIF withdrawal and the inhibitory effect of BMP4 on neural differentiation is compromised by Coch knockdown. Taken together, our data suggest that COCH is a part of the downstream target network of BMP signaling and serves as another important effector to fine-tune mouse ESC fates.

Extrinsic BMP and LIF signaling collaboratively maintain mouse embryonic stem cell (ESC) pluripotency, whereas appropriate ERK activity is essential for ESC fate commitment. However, how the extrinsic signals restrain appropriate ERK activity remains elusive. Here, we show that, whereas LIF sustains relatively high ERK activity, BMP4 can steadily attenuate ERK activity by upregulating ERK-specific dual-specificity phosphatase 9 (DUSP9). This upregulation requires Smad1/5 and Smad4 and specifically occurs to DUSP9, but not other DUSPs, and only in ESCs. Through DUSP9-mediated inhibition of ERK activity, BMP signaling reinforces the self-renewal status of mouse ESCs together with LIF. Upon LIF withdrawal, ESCs spontaneously undergo neural differentiation, during which process DUSP9 can partially mediate BMP inhibition on neural commitment. Collectively, our findings identify DUSP9 as a critical mediator of BMP signaling to control appropriate ERK activity critical for ESC fate determination., (Copyright © 2012 Elsevier Inc. All rights reserved.)