Search

As an olivine‐based cathode with high discharge platform and theoretical capacity, Li3V2(PO4)3's (LVP's) low conductivity and excessive grain size are the important factors hindering its development in the battery field. Halloysite nanotubes (HNTs) is a natural and cheap nanotube‐like material with large specific surface area and abundant surface nucleation sites, which can cooperate with conductive carbon layer to solve the deficiency of LVP. In this paper, we design a cathode material for in‐situ growth of LVP on HNTs (LVP@HNTs) and demonstrate that it has the appropriate particle size and the excellent specific surface area in the mass ratio of LVP to HNTs is 2:1. The capacity retention rate of LVP@HNTs‐2 reached almost 100% (97.0 mAh g−1) after 100 cycles at a low rate of 0.5 C. Moreover, its specific discharge capacity is 89.3 mAh g−1at a high rate of 20 C and its capacity retention rate is as high as 90.1% (80.5 mAh g−1) after 5,000 cycles, showing that the LVP@HNTs‐2 has marvelous rate capability and cycle stability. This study provides an innovative strategy for the development of the high‐performance cathode materials with low‐cost, excellent rate capability, and cycle stability of lithium ion batteries. In‐situ growth of LVP on HNTs (LVP@HNTs) as the cathode material for Li‐ion batteries were prepared by sol–gel method. Under the mass ratio of LVP to HNTs is 2:1, its capacity retention rate is as high as 90.1% after 5,000 cycles, showing that the LVP@HNTs‐2 has marvelous rate capability and cycle stability.

Fluctuations in gas emission or concentration at working face represent primary indicators of impending coal and gas outbursts, making them essential for monitoring processes. However, the direct use of original signals for predictive purposes may cause false warnings due to the inability to recognize valuable potential information. This can result in decreased prediction accuracy. Additionally, gas emission or concentration is affected by potential hazards such as sensor calibration, borehole spraying, and air duct damage, leading to complexity of their behavior and recognition process. This paper proposes an intelligent recognition method leveraging YOLOv8 neural network to discern coal and gas outburst precursors and potential hazards. By employing continuous wavelet transform (CWT) on the gas concentration signal processed by critical slowing down (CSD) method, a two-dimensional time–frequency representation is generated. This representation is then fed into YOLOv8 model to recognize the outburst precursor characteristics and potential hazards. The research results show that YOLOv8-based intelligent recognition adeptly identifies the relevant precursor characteristics and potential hazards, enhancing both coal mine safety protocols and the accuracy of early outburst warning mechanisms.

DOT1L mediates the methylation of histone H3 at lysine 79 and, in turn, the transcriptional activation or repression in a context-dependent manner, yet the regulatory mechanisms and functions of DOT1L/H3K79me remain to be fully explored. Following peptide affinity purification and proteomic analysis, we identified that DCAF1—a component of the E3 ligase complex involved in HIV regulation—is associated with H3K79me2 and DOT1L. Interestingly, blocking the expression or catalytic activity of DOT1L or repressing the expression of DCAF1 significantly enhances the tumor necrosis factor alpha (TNF-α)/nuclear factor κB (NF-κB)-induced reactivation of the latent HIV-1 genome. Mechanistically, upon TNF-α/NF-κB activation, DCAF1 is recruited to the HIV-1 long terminal repeat (LTR) by DOT1L and H3K79me2. Recruited DCAF1 subsequently induces the ubiquitination of NF-κB and restricts its accumulation at the HIV-1 LTR. Altogether, our findings reveal a feedback modulation of HIV reactivation by DOT1L-mediated histone modification regulation and highlight the potential of targeting the DOT1L/DCAF1 axis as a therapeutic strategy for HIV treatment.

The Fe‐doped LiVPO4F/C cathode material was synthesized by a one‐step solid‐state reaction method. The effects of Fe doping content on the structure and electrochemical performance of LiVPO4F/C were investigated. X‐ray diffraction (XRD) analyses demonstrated that the appropriate addition of Fe3+did not destroy the lattice structure of LiVPO4F/C. Scanning electron microscopy (SEM) showed that the surface of LiVPO4F/C is covered by a carbon film. The decreased grain size of the Fe‐doped LiVPO4F/C could shorten the ion transport path and thus improve the migration rate of lithium ions. X‐ray photoelectron spectroscopy (XPS) showed that the Fe ion exists in the Fe‐doped LiVPO4F/C as Fe3+ion. At the discharge rate of 1 C, the initial discharge capacity and capacity retention rate of the LiV0.98Fe0.02PO4F/C after 500 cycles were 123.5 mAh/g and 88.6%, respectively. Fe‐doped LiVPO4F/C as the cathode material for Li‐ion batteries were prepared by the one‐step solid‐state method. At 1C, the capacity retention rates after 500 cycles of LiVPO4F/C and LiV0.98Fe0.02PO4F/C samples were 59.4% and 88.6%, respectively.

AZ91D and 8.5vol.% SiCp/AZ91D magnesium matrix composites were fabricated by a semi-solid extruded processing method, and treated with solution and aging heat treatment. The effects of SiCpon the microstructures of the semi-solid extruded AZ91D magnesium alloy during recrystallization were studied by observing and analyzing the microstructure evolution during extrusions and heat treatments. The results show that the addition of SiCpinhibits the dynamic recrystallization of AZ91D during the semi-solid extrusion with only 26% of the volume fraction of recrystallization. Furthermore, the addition of SiCprefines the sizes of grains and second phases, and upgrades the volume fraction of second phase. After solution and aging treatment, the recrystallization continues, and the addition of SiCppromotes the recrystallization and the recrystallized microstructure is much more stable. Meanwhile, the sizes of grains and second phases continue to be refined, and the volume fraction of second phases continues to increase.

Semi-solid AZ91D magnesium alloy billets were prepared by near-liquidus heat holding. Semi-solid squeeze casting was conducted at 575, 585 and 595 °C, respectively, with 1 mm·s−1squeeze speed. The semisolid squeeze casting AZ91D samples were heat treated by T4 (solution at 415 °C for 24 h) and T6 (solution at 415 °C for 24 h + 220 °C for 8 h) processes, respectively. The microstructure and mechanical properties of the alloy in different states were investigated by means of OM, SEM and tensile testing machine. The results show that compared to as-cast alloy, the grain size of the semi-solid squeezed AZ91D decreased significantly, and with the increase of semi-solid squeeze temperature, the grain size of AZ91D increased. The grains of the alloy were refined by T4 treatment, and further refined by T6 treatment. T6 treatment greatly improved the tensile strength, elongation, and hardness, but did not significantly improve yield strength. After 575 °C squeeze casting and T6 treatment, the ultimate tensile strength (UTS) reached 285 MPa, the elongation reached 13.36%, and the hardness also reached the maximum (106.8 HV), but the yield strength (YS) was only 180 MPa. During the process of semi-solid squeeze casting and heat treatment, the matrix grain was refined and a large number of precipitated and secondary precipitated phases of Mg17Al12appeared. Both the average size of matrix grain and secondary precipitated phase decreased, while the volume fraction of secondary precipitated phase increased. All these resulted in high tensile strength, elongation and hardness.

Axially chiral carboxylic acids are important motifs in chiral catalysts and ligands. We herein reported the synthesis of axially chiral carboxylic acids via Pd(II)-catalyzed atroposelective C–H olefination using carboxylic acid as the native directing group. A broad range of axial chiral biaryl-2-carboxylic acids were synthesized in good yields with high enantioselectivities (up to 84% yield with 99% ee). Gram-scale reaction and further transformation reactions also provide a platform for synthetic applications of this method.

LiFePO4/C and LiFe1–xNbxPO4/C composites were synthesized using a sol–gel method. The influence of niobium doping on the constitution, morphology, and electrochemical properties of the samples was studied in detail. X‐Ray diffraction patterns indicate that appropriate Nb doping does not alter seriously the structure of LiFePO4. Electrochemical characterization of the electrodes showed that the Li‐ion batteries based on LiFe1–xNbxPO4/C electrode exhibited better charge/discharge performance than those based on LiFePO4/C. The LiFe0.95Nb0.05PO4/C‐based cell had the specific capacity of 157, 121, and 85 mAh/g at 0.2, 2, and 5 C, respectively, in comparison with 126, 94, and 52 mAh/g for the LiFePO4/C cell. The results show that the addition of niobium promotes the electrochemical performance of the materials especially at high charge/discharge rates of the battery. Niobium‐doped LiFePO4/C, which were prepared by the sol–gel method for the first time, exhibited good discharge performance and cycle stability at high rates (2 and 5 C) when used as the cathode material for Li‐ion batteries.

A mathematical physical model of microstructure evolution in Al-Si eutectic solidification process based on cellular automaton (CA) model was developed. Before the establishment of the model, the relevant near-eutectic experiments were carried out to analyze the effect of cooling rates measured by temperature curves on the eutectic structure which was observed through optical microscope (OM) and scanning electron microscope (SEM). Then a multiphase nucleation-growth CA model was applied to simulate the Al-Si irregular eutectic structure. The model adopted an alternative nucleation mechanism to investigate the influence of the critical nucleation value associated with solute concentration during solidification process. The growth kinetics took into account the solute and thermal field. According to the crystal structure of nonfaceted eutectic Al and faceted eutectic Si, different capturing rules were employed to calculate the growth of eutectic. In addition, the model was also used to research the irregular eutectic growth under different undercooling conditions. The results revealed that smaller critical nucleation value (absolute value) or higher eutectic undercooling tended to get a more refined eutectic microstructure. By compared with experimental results, it is indicated that the microstructure evolution of Al-Si eutectic growth can be reproduced quantitatively by numerical simulation with this model.