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On specific railway lines, trains are faced with the challenge of low-temperature environments. However, it is still unclear how the low-temperature service environment affects the friction-induced wear and vibration behavior at the train braking interface. Similarly, the impact of the brake pad friction block shape under low temperatures on this behavior is not well understood. This lack of knowledge adversely affects the operation, maintenance, and use of brake pads in low-temperature environments. Therefore, test samples of friction blocks were designed and processed based on several commonly used friction block shapes for trains (ellipse, triangle, and pentagon). Parking brake tests were conducted on a self-developed test bench with controllable temperature, exploring how different shapes affect friction-induced wear, vibration, and noise at the train braking interface under low temperatures (− 20 °C). The results showed that under the effects of low-temperature environments, the shape of the friction block significantly affects the friction-induced wear and vibration noise of the braking interface. Among them, the elliptical friction block has a smaller eccentric wear angle, a smaller and evenly distributed contact plateau area, relatively minor surface wear, and produces low-intensity vibration noise with small fluctuations. In contrast, the triangular and pentagonal friction blocks have larger eccentric wear angles, larger and concentrated contact plateau areas, relatively severe surface wear, and generate high-intensity vibration noise with large fluctuations. Analyzing the reasons, it is found that under the combined effects of low-temperature conditions and different shapes, the friction-induced wear on the surface of the friction block changes, thus exciting different intensities of vibration and noise. [ABSTRACT FROM AUTHOR]

Ferroptosis is an iron-dependent and lipid peroxidation-driven cell death cascade, occurring when there is an imbalance of redox homeostasis in the cell. Nuclear factor erythroid 2-related factor 2 (NFE2L2, also known as NRF2) is key for cellular antioxidant responses, which promotes downstream genes transcription by binding to their antioxidant response elements (AREs). Numerous studies suggest that NRF2 assumes an extremely important role in the regulation of ferroptosis, for its various functions in iron, lipid, and amino acid metabolism, and so on. Many pathological states are relevant to ferroptosis. Abnormal suppression of ferroptosis is found in many cases of cancer, promoting their progression and metastasis. While during tissue damages, ferroptosis is recurrently promoted, resulting in a large number of cell deaths and even dysfunctions of the corresponding organs. Therefore, targeting NRF2-related signaling pathways, to induce or inhibit ferroptosis, has become a great potential therapy for combating cancers, as well as preventing neurodegenerative and ischemic diseases. In this review, a brief overview of the research process of ferroptosis over the past decade will be presented. In particular, the mechanisms of ferroptosis and a focus on the regulation of ferroptosis by NRF2 will be discussed. Finally, the review will briefly list some clinical applications of targeting the NRF2 signaling pathway in the treatment of diseases. [ABSTRACT FROM AUTHOR]

Inspired by the difference in the friction radii of the pads from the high-speed train brake system, stick–slip experiments for a disc–block friction system with different friction radii were carried out via a test device. Based on the test results, the stick–slip vibration characteristics of the disc–block friction system with variation in the friction radius were analyzed, and the corresponding Stribeck model parameters in exponential and fractional forms were identified. The experimental results show that with an increase in the friction radius the vibration amplitude first increased and then decreased and the frequency of stick–slip vibration increased. The identified Stribeck model parameters show that the decay factors increased, the static friction coefficient decreased, and the dynamic friction coefficient decreased first and then increased as the friction radius increased. Moreover, the identified Stribeck model in an exponential form can more accurately reflect the stick–slip characteristics of a disc–block friction system than the model in a fractional form. It can be further applied in the investigation of the dynamic behaviors of high-speed train brake systems. [ABSTRACT FROM AUTHOR]

We have developed a series of novel monolithic materials based on molecules previously explored as dopants in guest–host systems to study intrinsic structure–function relationships in organic electro-optic (EO) materials. In a library of EO molecules with varied bridge segments, molecular modification of the donor with bis(tert-butyldiphenylsilyl) groups led to improvement in formation of amorphous films and led to enhanced poling efficiency. Further modification to include a carbazole site-isolation group on the bridge effectively reduced intermolecular dipole–dipole interactions, led to a material with poling efficiency of approximately 3 (nm V−1)2, and an increased glass transition temperature to 20–40 °C higher than similar reported monolithic materials. This level of thermal stability is comparable to common guest/host systems, which incorporated poly(methyl methacrylate) (PMMA) as the host. Our research showed that π-bridge length and type impacted first molecular hyperpolarizability β of a chromophore, which is accordingly reflected in the EO response. These findings further promote the utility of monolithic materials for their increased EO behavior and improved thermal stability, making this material system a competitor of guest–host systems in commercial applications. [ABSTRACT FROM AUTHOR]