Mechanistic Insights into the Hydrazine-induced Chemical Reduction Pathway of Graphene Oxide

Hydrazine stands out as the most generally used chemical-reducing agent for reducing graphene oxide. Despite numerous experimental and theoretical investigations into the reduction reaction, the reduction mechanism remains unclear. In this study, we propose that, in aqueous hydrazine solutions, both hydrazine and hydroxide ions could initiate the reduction of graphene oxide. We introduce a chemical reaction pathway involving C-H cleavage and a dehydroxylation process for the reduction of graphene oxide. By utilizing density functional theory calculations, the reduction reactions mediated by hydrazine and hydroxide ions are separately investigated. The reaction routes on the basal plane and edge regions of graphene oxide are discussed independently. The density functional theory calculations demonstrate that the proposed mechanism is both thermodynamically and dynamically feasible. This work might contribute to an atomic-level comprehension of a longstanding challenge in the field of graphene oxide

Characterization and modeling of ductile rupture with relationship to microstructures in 2198 Al-Li alloy for aeronautic application

International audienceDamage and fracture mechanisms of two 2198 Al-Li thin sheet alloys having different thicknesses (2 and 6 mm) are investigated. Two heat treatments are studied: T3 and T8. Mechanical tests are carried out on flat specimens including smooth tensile samples and U-notched specimens (with various notch radii). Test data are used to identify the parameters of constitutive equations describing plastic anisotropy. Crack initiation and stable propagation is studied using Kahn tear tests. The microscopic fracture surface of the different specimens is observed using SEM (Scanning Electron Microscopy). Smooth and notched samples exhibit a slant fracture surface. With increasing notch severity, the fracture mode changes significantly. Failure initiates at the notch root in a small triangular region, outside this zone, slant fracture is observed. Observations show two different failure mechanisms with respect to triangular and slant zones

Optical Properties and Excitation Dynamics in 3d and 2d Systems

Ph.DDOCTOR OF PHILOSOPH

Improved Decoding of Staircase Codes: The Soft-aided Bit-marking (SABM) Algorithm

Staircase codes (SCCs) are typically decoded using iterative bounded-distance decoding (BDD) and hard decisions. In this paper, a novel decoding algorithm is proposed, which partially uses soft information from the channel. The proposed algorithm is based on marking certain number of highly reliable and highly unreliable bits. These marked bits are used to improve the miscorrection-detection capability of the SCC decoder and the error-correcting capability of BDD. For SCCs with $2$-error-correcting Bose-Chaudhuri-Hocquenghem component codes, our algorithm improves upon standard SCC decoding by up to $0.30$~dB at a bit-error rate (BER) of $10^{-7}$. The proposed algorithm is shown to achieve almost half of the gain achievable by an idealized decoder with this structure. A complexity analysis based on the number of additional calls to the component BDD decoder shows that the relative complexity increase is only around $4\%$ at a BER of $10^{-4}$. This additional complexity is shown to decrease as the channel quality improves. Our algorithm is also extended (with minor modifications) to product codes. The simulation results show that in this case, the algorithm offers gains of up to $0.44$~dB at a BER of $10^{-8}$.Comment: 10 pages, 12 figure

Shift-ConvNets: Small Convolutional Kernel with Large Kernel Effects

Recent studies reveal that the remarkable performance of Vision transformers (ViTs) benefits from large receptive fields. For this reason, the large convolutional kernel design becomes an ideal solution to make Convolutional Neural Networks (CNNs) great again. However, the typical large convolutional kernels turn out to be hardware-unfriendly operators, resulting in discount compatibility of various hardware platforms. Thus, it is unwise to simply enlarge the convolutional kernel size. In this paper, we reveal that small convolutional kernels and convolution operations can achieve the closing effects of large kernel sizes. Then, we propose a shift-wise operator that ensures the CNNs capture long-range dependencies with the help of the sparse mechanism, while remaining hardware-friendly. Experimental results show that our shift-wise operator significantly improves the accuracy of a regular CNN while markedly reducing computational requirements. On the ImageNet-1k, our shift-wise enhanced CNN model outperforms the state-of-the-art models. Code & models at https://github.com/lidc54/shift-wiseConv

Nonlinear analysis of stress and strain for a clay core rock-fill dam with FEM

AbstractBased on the Duncan-Chang hyperbolic nonlinear elastic material model, this paper carried out the stress and strain numerical analysis of a clay core rock-fill dam, which is a certain building reservoir dam in Yunnan province. By loading on each layer step by step and with the static nonlinear finite element simulation of deposition, it obtained the results of the stress and deformation of the clay core rock-fill dam. The calculation showed that the great difference in deformation modulus causes non-smooth variations in deformation, stress and strain between the transition area and the rock-debris fill. From the analysis it can be seen that the present design of the dam is reasonable since no any abnormal stresses and deformations occurred in the dam. Moreover, this also indicated a feasible and provided a valuable evident for the optimization of cross-section zones in a project

MicroRNA-184 downregulates nuclear receptor corepressor 2 in mouse spermatogenesis

<p>Abstract</p> <p>Background</p> <p>There have been increasing attentions on the role of small RNAs, especially microRNAs in post-transcriptional gene regulation during spermatogenesis. MicroRNA-184 (miR-184) has been shown to be mainly expressed in the testis and brain, and that its expression levels are by far the highest in the testis. However, the role of miR-184 in mammalian spermatogenesis remains unclear.</p> <p>Results</p> <p>In this study, we demonstrated that miR-184 levels were increased during mouse postnatal testis development. Specifically, miR-184 expression was restricted to the germ cells from spermatogonia to round spermatids. Overexpression of miR-184 promoted the proliferation of a germ cell line, GC-1spg. Moreover, miR-184 downregulated <it>nuclear receptor corepressor 2 </it>(<it>Ncor2</it>) by targeting its 3' untranslated region through inhibiting NCOR2 protein translation.</p> <p>Conclusions</p> <p>MiR-184 may be involved in the post-transcription regulation of mRNAs such as <it>Ncor2 </it>in mammalian spermatogenesis.</p