Fatigue characteristics of concrete subjected to compressive cyclic loading: laboratory testing and numerical simulation

The fatigue characteristics of concrete are studied based on laboratory tests and numerical simulations. A series of compressive cyclic loading tests have been carried out on concrete samples. The effects of maximum and minimum load level on the evolution strain rate, energy dissipation, acoustic emissions (AE) and P-wave speed are analysed. Based on particle based numerical simulations, damage models corresponding to single-level and multi-level cyclic loading tests are proposed. The damage variable in the numerical model is time- and stress-dependent and is characterized by the progressive reduction of the bond diameter. The mechanical behaviour of concrete during cyclic loading tests is well reproduced in the numerical simulation. A real time fatigue failure prediction method is proposed based on the hysteresis occurrence ratio and hysteresis energy ratio. The AE characteristics during the laboratory tests are reproduced by the numerical simulations. AE counts and energy are characterized by broken bonds and released bond strain energy, respectively

SwinGNN: Rethinking Permutation Invariance in Diffusion Models for Graph Generation

Diffusion models based on permutation-equivariant networks can learn permutation-invariant distributions for graph data. However, in comparison to their non-invariant counterparts, we have found that these invariant models encounter greater learning challenges since 1) their effective target distributions exhibit more modes; 2) their optimal one-step denoising scores are the score functions of Gaussian mixtures with more components. Motivated by this analysis, we propose a non-invariant diffusion model, called $\textit{SwinGNN}$, which employs an efficient edge-to-edge 2-WL message passing network and utilizes shifted window based self-attention inspired by SwinTransformers. Further, through systematic ablations, we identify several critical training and sampling techniques that significantly improve the sample quality of graph generation. At last, we introduce a simple post-processing trick, $\textit{i.e.}$, randomly permuting the generated graphs, which provably converts any graph generative model to a permutation-invariant one. Extensive experiments on synthetic and real-world protein and molecule datasets show that our SwinGNN achieves state-of-the-art performances. Our code is released at https://github.com/qiyan98/SwinGNN

Ischemia/reperfusion-activated ferroptosis in the early stage triggers excessive inflammation to aggregate lung injury in rats

ObjectiveLung ischemia/reperfusion injury (LIRI) is a clinical syndrome of acute lung injury that occurs after lung transplantation or remote organ ischemia. Ferroptosis and inflammation are involved in the pathogenesis of LIRI according to the results of several studies on animal models. However, the interactive mechanisms between ferroptosis and inflammation contributing to LIRI remain unclear.MethodsHE staining and indicators of oxidative stress were used to evaluated the lung injury. The reactive oxygen species (ROS) level was examined by DHE staining. The quantitative Real-time PCR (qRT-PCR) and western blot analysis were employed to detect the level of inflammation and ferroptosis, and deferoxamine (DFO) was used to assess the importance of ferroptosis in LIRI and its effect on inflammation.ResultsIn the present study, the link of ferroptosis with inflammation was evaluated at reperfusion 30-, 60- and 180-minute time points, respectively. As the results at reperfusion 30-minute point shown, the pro-ferroptotic indicators, especially cyclooxygenase (COX)-2 and acyl-CoA synthetase long-chain family member 4 (ACSL4), were upregulated while the anti-ferroptotic factors glutathione peroxidase 4 (GPX4), cystine-glumate antiporter (XCT) and ferritin heavy chain (FTH1) were downregulated. Meanwhile, the increased level of interleukin (IL)-6, tumor necrosis factor alpha (TNF-α) and IL-1β were observed beginning at reperfusion 60-minute point but mostly activated at reperfusion 180-minute point. Furthermore, deferoxamine (DFO) was employed to block ferroptosis, which can alleviate lung injury. Expectedly, the survival rate of rats was increased and the lung injury was mitigated containing the improvement of type II alveolar cells ultrastructure and ROS production. In addition, at the reperfusion 180-minute point, the inflammation was observed to be dramatically inhibited after DFO administration as verified by IL-6, TNF-α and IL-1β detection.ConclusionThese findings suggest that ischemia/reperfusion-activated ferroptosis plays an important role as the trigger for inflammation to further deteriorate lung damages. Inhibiting ferroptosis may have therapeutic potential for LIRI in clinical practice

Chemical Constituents and Digestion-Promoting Effect of Maojian Green Tea

In this study, the digestion-promoting function of an aqueous extract from Maojian green tea extract (MJ-GTE) was evaluated by small intestinal motility in mice as well as body mass, body mass gain, food intake, food utilization rate, gastric pepsin activity, and gastric pepsin excretion in rats. The chemical composition of MJ-GTE was then systematically analyzed using metabolomics based on ultra-high performance liquid chromatography-quadrupole electrostatic orbitrap mass spectrometry (UPLC-Q-Exactive/MS). The results of animal experiments showed that the intestinal propulsion ratio of ink in the high-dose MJ-GTE group (0.83 g/(kg·d)) was significantly increased compared with the model group (P < 0.05), and gastric pepsin excretion in the medium-dose MJ-GTE group (0.21 g/(kg·d)) was significantly increased compared with the negative control group (deionized water) (P < 0.05), which collectively indicated that MJ-GTE has a digestion-promoting effect. The metabolomics analysis identified 98 compounds, among which, flavones (apigenin and luteolin, 0.14–0.77 mg/g), flavanones (naringenin and eriodictyol, 0.49–1.49 mg/g), flavone-7-O-glycosides (0.57–9.07 mg/g), and flavanone-7-O-glycosides (4.49–38.98 mg/g) were the major components in MJ-GTE. This study will provide a theoretical basis for the promotion and development of Maojian green tea and related products in the future

Fatigue characteristics of concrete subjected to compressive cyclic loading: laboratory testing and numerical simulation

The fatigue characteristics of concrete are studied based on laboratory tests and numerical simulations. A series of compressive cyclic loading tests have been carried out on concrete samples. The effects of maximum and minimum load level on the evolution strain rate, energy dissipation, acoustic emissions (AE) and P-wave speed are analysed. Based on particle based numerical simulations, damage models corresponding to single-level and multi-level cyclic loading tests are proposed. The damage variable in the numerical model is time- and stress-dependent and is characterized by the progressive reduction of the bond diameter. The mechanical behaviour of concrete during cyclic loading tests is well reproduced in the numerical simulation. A real time fatigue failure prediction method is proposed based on the hysteresis occurrence ratio and hysteresis energy ratio. The AE characteristics during the laboratory tests are reproduced by the numerical simulations. AE counts and energy are characterized by broken bonds and released bond strain energy, respectively