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High-speed railway tunnels, being critical components of transportation infrastructure, are subject to various aerodynamic effects that can impact train operations and passenger comfort. To address these challenges, the concept of tunnels with variable cross sections offers a promising solution, allowing for non-uniform adjustments to tunnel geometry along its length. By employing the notion of equivalent excavation volume, this paper aims to provide a comprehensive aerodynamic analysis of variable cross section tunnels, focusing on different rates of cross section variation (CR). The simulation of high-speed trains (HSTs) passing through tunnels is conducted using the compressible, unsteady Reynolds-Averaged Navier–Stokes model, and the accuracy is confirmed through experimental validation. The transient pressure and peak distribution, slipstream characteristics, micro-pressure waves, and aerodynamic loads acting on trains are fully evaluated. The results indicate that variable cross section tunnels can alleviate the negative pressure on train surface, particularly with streamlined heads and tails exhibiting superior effects, whereas its influence on positive pressure is minimal. The mitigation of both positive and negative pressures on the tunnels is promising, with the maximum peak-to-peak pressures exhibiting a quadratic decrease as the CR increases, resulting in a maximum relief of 17.7%. However, variable cross section tunnels have certain adverse effects on slipstreams and transient loads when HSTs passing through front junctions. Therefore, it is necessary to choose an appropriate CR to control these effects during design process. The findings of this research contribute novel insight for optimizing tunnel design and engineering practices to enhance operational efficiency and passenger comfort. [ABSTRACT FROM AUTHOR]

The microchannel heat sink (MCHS) has the advantages of small heat transfer resistance, high heat transfer efficiency and small size, which exhibits good heat transfer performance in the field of active heat dissipation of electronic devices integrated with high heat flux density. In this paper, the application of MCHS in thermal management is reviewed in recent years, and the research progress of microchannel topology on enhancing heat transfer performance is summarized. Firstly, the research progress on the cross-sectional shape of the microchannel shows that the heat transfer area and fluid flow dead zone of the microchannel is the keys to affecting the heat transfer performance; Secondly, the microchannel distribution and the bionic microchannel structure have a great role in enhancing heat transfer performance, especially in microchannel temperature uniformity; Thirdly, the disturbing effect caused by interrupted structures in microchannels such as ribs and concave cavities has become a hot topic of research because it can weaken the thermal boundary layer and increase heat dissipation. Finally, the commonly used MCHS materials and cooling media are summarized and introduced. Based on the above reviews of MCHS research and applications, the future trends of MCHS topologies are presented.

Paroxysmal nonkinesigenic dyskinesia (PNKD) is an autosomal dominant episodic movement disorder. Patients have episodes that last 1 to 4 hours and are precipitated by alcohol, coffee, and stress. Previous research has shown that mutations in an uncharacterized gene on chromosome 2q33-q35 (which is termed PNKD) are responsible for PNKD. Here, we report the generation of antibodies specific for the PNKD protein and show that it is widely expressed in the mouse brain, exclusively in neurons. One PNKD isoform is a membrane-associated protein. Transgenic mice carrying mutations in the mouse Pnkd locus equivalent to those found in patients with PNKD recapitulated the human PNKD phenotype. Staining for c-fos demonstrated that administration of alcohol or caffeine induced neuronal activity in the basal ganglia in these mice. They also showed nigrostriatal neurotransmission deficits that were manifested by reduced extracellular dopamine levels in the striatum and a proportional increase of dopamine release in response to caffeine and ethanol treatment. These findings support the hypothesis that the PNKD protein functions to modulate striatal neuro-transmitter release in response to stress and other precipitating factors.

To prevent the cable sheaths of Er’qi Yangtze River Bridge from freezing under bad weather in winter, which may lead to ice fall and bring traffic safety accidents, a theoretical model and technical scheme of hot air ice melt system for Er’qi Yangtze River Bridge has been proposed. Based on the established heat transfer model for cable sheaths, the characteristics of heat transfer between internal hot air and outdoor environment have been analyzed. Under the condition when the temperature of the end of cable sheath’s outwall is more than 3°C, the range of temperature and speed of input hot air were estimated, which provides a theoretical basis for hot air melt system for cable-stayed bridge sheaths.