Search

For studying the effect of nitriding treatment on the microstructure and wear properties of HVOF sprayed Al1-xCoCrFeNiTix(x＝0，0.125，0.250) high-entropy alloy coatings，the HVOF technology was employed to prepare Al1-xCoCrFeNiTix(x＝0，0.125，0.250) highentropy alloy coating on 35CrMo steel substrate，which were further nitrided.The effects of nitriding treatment on the microstructure and wear properties of Al1-xCoCrFeNiTix(x＝0，0.125，0.250) high-entropy alloy coating prepared by HVOF were studied via characterization methods such as SEM，XRD，3D white light interferometer and EDS.Results showed that the high-entropy alloy coating of Al1-xCoCrFeNiTix(x＝0，0.125，0.250) after nitriding treatment had a dense microstructure with a typical thermal spray coating-like structure.The coating thickness was about 300～350 μm，the nitriding layer thickness was about 10 μm，and the nitriding layer phase structure was FCC phase and AlN，CrN and other nitriding phases.Meanwhile，the microhardness of the nitriding layer was 981 HV2N(x＝0)，1 090 HV2N(x＝0.125) and 1 194 HV2N(x＝0.250)，respectively，which was significantly improved compared with the microhardness of 479 HV2N(x＝0)，506 HV2N(x＝0.125) and 548 HV2N(x＝0.250) of the unnitrided high-entropy alloy coating.With the increase of Ti content，the wear resistance of the nitriding layer increased，and Al0.750CoCrFeNiTi0.250nitriding layer possessed the best wear resistance [(2.17×10-6mm3/(N·m)].Besides，the wear failure mechanism of Al1-xCoCrFeNiTix(x＝0，0.125，0.250) nitriding layer was mainly abrasive wear，oxidation wear and adhesive wear.

Plasma dynamics are essential in high-power electron beam diodes, as they influence the current density and can even cause gap closure because of fast expansion velocity during operation. In this study, the formation and expansion of the cathode plasma in a high-power planar diode has been investigated by particle-in-cell simulations. The results indicate that the expansion velocity of the cathode plasma in the planar diode is ∼2.5 cm/μs operating with a 340 kV peak voltage and 1.5 kA current, which possesses a maximum pressure of 1 Torr pressure and a gas desorption rate of 38 molecules per electron. Moreover, the enhanced emission on the edge causes a faster growth rate of the gas pressure and formation of plasma, which possesses a higher plasma density than other regions. A higher gas desorption rate and total amount of outgoing gas can cause a larger velocity of plasma expansion, and the expansion velocity is proportional to the logarithm of the rising speed of the diode voltage, while the amplitude of diode voltage did not show a clear correlation with plasma velocity. Finally, a combined dependence of the plasma velocity on the gas desorption rate, total gas volume, rising speed of the diode voltage, and diode voltage is concluded. This work provides new insights into the dynamics of cathode plasma in high-power diodes and may be helpful for engineering design. [ABSTRACT FROM AUTHOR]

Frequency‐sweeping laser sources play a critical role in the accurate 3D mapping of frequency‐modulated continuous‐wave (FMCW) LiDAR systems, whose chirp linearity greatly impacts the measurement precision. Although various pre‐distortion algorithms have been proposed to reduce chirp nonlinearity, these open‐loop methods can rapidly suppress the chirp nonlinearity but they are susceptible to environmental variations and often exhibit subpar performance in long‐range detection scenarios. In contrast, the electro–optical phase‐locked loop (EO‐PLL) serves as a real‐time linearizing solution for FMCW LiDAR, enabling high‐precision, high‐resolution, and long‐distance measurement capabilities. In this study, a III/V‐Si3N4 hybrid‐integrated external cavity laser (ECL) is used to generate an FMCW signal over a large wavelength tuning range of 68 nm. The maximum output optical power is 15.8 mW, and the intrinsic linewidth is 0.9 kHz. By modulating the phase shifter, an FMCW signal with a chirp bandwidth of 0.7 GHz is generated at a repetition rate of 1 kHz. The pre‐distortion algorithm is combined with the gain‐tunable EO‐PLL system to suppress the chirp nonlinearity and frequency noise across multiple wavelengths, leading to a remarkable improvement in range precision from 202 to 4.2 cm when targeting a distance of 200 m. [ABSTRACT FROM AUTHOR]

Due to the inability to restore the original performance, a significant portion of retired mechanical products is often replaced with new ones and discarded or recycled as low-value materials. This practice leads to energy waste and a decline in their residual value. The generalized growth remanufacturing model (GGRM) presents opportunities to enhance the residual value of retired products and parts. It achieves this by incorporating a broader range of growth modes compared to traditional restorative remanufacturing approaches. The selection of the growth mode is a crucial step to achieve GGRM. However, there is a limited number of growth mode selection methods that are specifically suitable for GGRM. The capacity and efficiency of the method are also significant factors to consider. Therefore, we propose a growth mode selection method based on association rule mining. This method consists of three main steps: Firstly, the ReliefF method is used to select the core failure characteristics of retired parts. Secondly, a genetic algorithm (GA) is employed to identify the association between core failure characteristics, repair technology, and maximum recoverability. Finally, based on the maximum recoverability, the appropriate growth mode is selected for each retired part. We conduct a case study on retired automobile universal transmission, and the results demonstrate the feasibility, efficiency, and accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

Cancer-associated fibroblasts (CAFs) are considered one of the most critical stromal cells that interact with pancreatic ductal adenocarcinoma (PDAC) and promote tumor growth, metastasis, and treatment resistance. Previous studies illustrated macroautophagy/autophagy contributes to CAF activation during tumor progression. Here in our study, we found that autophagy deficiency in CAFs impedes CAF activation by inhibiting proline biosynthesis and collagen production. Furthermore, we uncovered that autophagy promotes proline biosynthesis through mitophagy-mediated regulation of NADK2 (NAD kinase 2, mitochondrial), an enzyme responsible for production of mitochondrial NADP(H). Using an orthotopic mouse model of PDAC, we found that inhibiting mitophagy by targeting PRKN (parkin RBR E3 ubiquitin protein ligase) in the stroma reduced tumor weight. Thus, inhibition of CAFs mitophagy might be an attractive strategy for stroma-focused anti-cancer intervention. Abbreviations: ACTA2/α-SMA: actin alpha 2, smooth muscle, aorta; ACTB/β-actin: actin, beta; ALDH18A1/P5CS: aldehyde dehydrogenase 18 family, member A1; ATG3: autophagy related 3; ATG5: autophagy related 5; BNIP3L: BCL2/adenovirus E1B interacting protein 3-like; CAFs:cancer-associated fibroblasts; COL1A1: collagen, type I, alpha 1; DES: desmin; ECM: extracellular matrix; FABP4: fatty acid binding protein 4, adipocyte; FAP/FAPα: fibroblast activation protein; IHC: immunohistochemical staining; LAMP1: lysosomal-associated membrane protein 1; NADK2: NAD kinase 2, mitochondrial; PC1: pro-collagen 1; PDAC: pancreatic ductal adenocarcinoma; PDGFR: platelet derived growth factor receptor; PDPN: podoplanin; PRKN: parkin RBR E3 ubiquitin protein ligase; PSCs: pancreatic stellate cells; VIM: vimentin; WT: wild-type [ABSTRACT FROM AUTHOR]