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The phase balance, interface boundaries, and grain types were characterized in the local dry underwater welded DSS metals. The results showed that the austenite content of the weld ...metals decreased first, then increased and then decreased with the increase in the simulated water depth from 0.1 m to 75 m. The fractions of Σ3 austenite twin grain boundaries and recrystallized ferrite and austenite grains had a similar trend with the austenite content, while the change in the proportion of special ferrite-austenite interphase boundaries showed an opposite trend. The microstructure changes in the weld metal from 15 m to 45 m were more dramatic than those from 45 m to 75 m. The resultant mechanical performance was in good agreement with the microstructure evolution. More austenite content, Σ3 austenite twin grain boundaries and recrystallized grains made the plasticity and toughness of the weld metals better at 45 m and 75 m. The best plasticity and toughness performance was obtained in the weld metal at 45 m.
In the present study, a new turbomolecular pump (TMP) performance prediction algorithm is proposed according to the variable surface combined blade row (VSCBR) geometric model. The simulation ...calculation program is designed to perform structural optimization and flow field analysis. Research on the pumping performance of the traditional straight blade row (TSBR) indicates that when the blade velocity ratio is greater than 1, the increase in the pumping speed and compression ratio of the TMP gradually tends to stabilize. Response surface methodology is used to optimize the structural parameters of the first four stages of the combined blade row. The optimized VSCBR increases the pumping speed by 18.2% compared to that of the TSBR. The flow field analysis based on the optimized VSCBR shows that gas molecules reaching the rear blades are likely to approach the outlet, and the proportion of gas molecules in this region exceeds 50%. Therefore, the blades we designed should be conducive to additional gas molecules reaching the outlet.
Triboelectric nanogenerator (TENG) is regarded as a revolutionary technology for harvesting clean and sustainable energy with low cost. Here, sliding-mode TENGs based on both graphene sheets embedded ...carbon (GSEC) and amorphous carbon (a-C) films were designed and their friction-electrification coupling properties were studied. The GSEC and a-C films were fabricated by electron irradiation assisted physical vapor deposition in an electron cyclotron resonance (ECR) plasma system. A novel testing platform that can simultaneously measure friction force, output voltage and output current was designed and assembled for studying the friction-electrification coupling of sliding-mode TENG. In the case of GSEC and a-C films slid against Polytetrafluoroethylene (PTFE) film, the open-circuit output voltage, the short-circuit output current density, the peak power density and the maximum instantaneous energy conversion efficiency were 13.5 V, 0.35 μA/cm2, 0.63 mW/cm2 and 8.61% for the GSEC film based TENG, and 8.5 V, 0.24 μA/cm2, 0.5 mW/cm2 and 7.71% for the a-C film based TENG, respectively. The results implied that the GSEC film exhibited a higher electric output performance compared with the a-C film. The origin of high electric output performance of the GSEC film based TENG was ascribed to the edge and channel effects of graphene sheets. These findings shed light on the application of carbon films in friction-induced nanoenergy field.
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•A novel platform was developed for evaluating friction-electrification performances.•The friction-electrification performances of GSEC film based TENG were explored.•High performance of GSEC based TENG was ascribed to the edge and channel effects.•GSEC film exhibited potential application in eco-friendly and high performance TENG.
Graphical Abstract
The mechanisms of antioxidant peptides EP4 and EP5 on protecting HUVECs from oxidative damage.
To screen, prepare, identify, and evaluate the activities of natural antioxidants for ...treating chronic diseases caused by oxidative stress. Two algal proteins, namely ZD10 and ZD60, precipitated with 10 and 60% (NH
4
)
2
SO
4
were extracted from red algae
Eucheuma cottonii
(
E. cottonii
) and hydrolyzed using five proteolytic enzymes. The results showed that ZD60 played the most significant role in the enhancement of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH⋅) scavenging activity (25.91 ± 0.24%) among all protein hydrolysates. Subsequently, six antioxidant peptides (EP1-EP6) were isolated from the papain hydrolysate of ZD60 by ultrafiltration and chromatography methods. Their amino acid sequences were identified as Thr-Ala (EP1), Met-Asn (EP2), Tyr-Ser-Lys-Thr (EP3), Tyr-Ala-Val-Thr (EP4), Tyr-Leu-Leu (EP5), and Phe-Tyr-Lys-Ala (EP6) with molecular weights of 190.21, 263.33, 497.55, 452.51, 407.51, and 527.62 Da, respectively. Of which, EP3, EP4, EP5, and EP6 showed strong scavenging activities on DPPH⋅, hydroxyl radical (HO⋅), and superoxide anion radical (O- 2⋅). Moreover, EP4 and EP5 could significantly protect human umbilical vein endothelial cells (HUVECs) from H
2
O
2
-induced oxidative damage by increasing the levels of antioxidant enzyme systems including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) to reduce the levels of reactive oxygen species (ROS) (60.51 and 51.74% of model group) and malondialdehyde (MDA) (75.36 and 64.45% of model group). In addition, EP4 and EP5 could effectively inhibit H
2
O
2
-induced apoptosis by preventing HUVECs from early apoptosis to late apoptosis. These results indicated that the antioxidant peptides derived from
E. cottonii
, especially EP4 and EP5, could serve as the natural antioxidants applied in pharmaceutical products to treat chronic cardiovascular diseases caused by oxidative damage, such as coronary heart disease, atherosclerosis, etc.
The recovery of blood supply after a period of myocardial ischaemia does not restore the heart function and instead results in a serious dysfunction called myocardial ischaemia‐reperfusion injury ...(IRI), which involves several complex pathophysiological processes. Mitochondria have a wide range of functions in maintaining the cellular energy supply, cell signalling and programmed cell death. When mitochondrial function is insufficient or disordered, it may have adverse effects on myocardial ischaemia‐reperfusion and therefore mitochondrial dysfunction caused by oxidative stress a core molecular mechanism of IRI. Peroxisome proliferator‐activated receptor gamma co‐activator 1α (PGC‐1α) is an important antioxidant molecule found in mitochondria. However, its role in IRI has not yet been systematically summarized. In this review, we speculate the role of PGC‐1α as a key regulator of mitonuclear communication, which may interacts with nuclear factor, erythroid 2 like ‐1 and ‐2 (NRF‐1/2) to inhibit mitochondrial oxidative stress, promote the clearance of damaged mitochondria, enhance mitochondrial biogenesis, and reduce the burden of IRI.
Based on the finite element theory, a joint-plane modeling method is employed to connect the corresponding nodes at the joint surface of the woodworking computer numerical control (CNC) machining ...center bed with a 2-node 12-degree-of-freedom unit. A spatial element model is established, which can show the state of the nodes between joint surfaces when they are stretched, compressed, or twisted; and it can help build a woodworking CNC machining center on a finite element model of bed with the characteristics of the joint surface. The simulated analysis is performed on the model and is compared with the result of simulated analysis on the bed model that ignores the characteristics of the joint surface and modal experiment. The comparison verifies the effectiveness of the modeling method based on the characteristics of the joint surface. The weak link of the machine bed structure is analyzed and optimized. The natural frequency of the bed is improved by2.55% ~ 11.3%. The displacement is reduced by a maximum of 19.4%, and dynamic performance of the bed is improved.
Building three-dimensional models effectively and accurately is an important issue. In this letter, a new image set partition method for efficient structure from motion (SfM) from a set of unevenly ...distributed images is proposed. Given the largest connected component in the image matching graph, we first reconstruct a base model from a set of images with large overlap and sufficient feature correspondences. Then, a novel constrained radial agglomerative clustering algorithm is proposed to divide the remaining images, so that each image cluster could be independently added to the base model in parallel. Finally, all the partial models are merged into a complete scene. Experiment results show that the proposed method works better than the popular normalized-cuts-based SfM method.
COVID-19 might have long-term mental health impacts. We aim to investigate the longitudinal changes in mental problems from initial COVID-19 peak to its aftermath among general public in China. ...Depression, anxiety and insomnia were assessed among a large-sample nationwide cohort of 10,492 adults during the initial COVID-19 peak (28 February 2020 to 11 March 2020) and its aftermath (8 July 2020 to 8 August 2020) using the Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, and Insomnia Severity Index. We used generalized estimating equations and linear mixed models to explore factors associated with long-term mental health symptoms during COVID-19. During the five months, mental health symptoms remained consistently elevated (baseline 46.4%; follow-up 45.1%). Long-term depression, anxiety and insomnia were associated with several personal and work-related factors including quarantine (adjusted OR for any mental health symptoms 1.31, 95%CI 1.22–1.41, p < 0.001), increases in work burden after resuming work (1.77, 1.65–1.90, p < 0.001), occupational exposure risk to COVID-19 (1.26, 1.14–1.40, p < 0.001) and living in places severely affected by initial COVID-19 peak (1.21, 1.04–1.41, p = 0.01) or by a COVID-19 resurgence (1.38, 1.26–1.50, p < 0.001). Compliance with self-protection measures, such as wearing face masks (0.74, 0.61–0.90, p = 0.003), was associated with lower long-term risk of mental problems. The findings reveal a pronounced and prolonged mental health burden from the initial COVID-19 peak through to its aftermath in China. We should regularly monitor the mental health status of vulnerable populations throughout COVID-19.
Volatile solids with symmetric π‐backbone are intensively implemented on manipulating the nanomorphology for improving the operability and stability of organic solar cells. However, due to the ...isotropic stacking, the announced solids with symmetric geometry cannot modify the microscopic phase separation and component distribution collaboratively, which will constrain the promotion of exciton splitting and charge collection efficiency. Inspired by the superiorities of asymmetric configuration, a novel process‐aid solid (PAS) engineering is proposed. By coupling with BTP core unit in Y‐series molecule, an asymmetric, volatile 1,3‐dibromo‐5‐chlorobenzene solid can induce the anisotropic dipole direction, elevated dipole moment, and interlaminar interaction spontaneously. Due to the synergetic effects on the favorable phase separation and desired component distribution, the PAS‐treated devices feature the evident improvement of exciton splitting, charge transport, and collection, accompanied by the suppressed trap‐assisted recombination. Consequently, an impressive fill factor of 80.2% with maximum power conversion efficiency (PCE) of 18.5% in the PAS‐treated device is achieved. More strikingly, the PAS‐treated devices demonstrate a promising thickness‐tolerance character, where a record PCE of 17.0% is yielded in PAS devices with a 300 nm thickness photoactive layer, which represents the highest PCE for thick‐film organic solar cells.
A low‐cost, high volatile, and asymmetric halogen benzene derivate, 1,3‐dibromo‐5‐chlorobenzene, is applied as process‐aid solid to manipulate the blend nanomorphology and enhance the crystallinity in Y‐series small molecule‐based photoactive layer system. A champion power conversion efficiency of 17.0% is yielded, which is one of the highest performances for thick‐film organic solar cells.
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