The internal temperature variation of ballastless track is very complicated under the effect of a sunlit environment, and there are serious transverse and vertical temperature gradients, which will cause cracking and deformation of the structure. In this paper, an ANSYS temperature effect analysis model for ballastless track, considering box girder structure, is established based on the environmental information of the bridge and the characteristics of the structural system. The model considers the influence of solar radiation intensity, wind speed, air temperature, geographical location, bridge orientation, material parameters, and other factors on the boundary conditions, and can meet the needs of the daylight temperature response analysis and calculation of any complex bridge structure. On this basis, the effect and applicability of a solar reflective coating on ballastless track cooling are studied. The results showed that the calculated results of the finite element model agree well with the measured results. Under the high-temperature conditions in summer, sunlight and ambient temperature mainly have significant effects on the temperature and temperature gradient of the track slab, and the maximum vertical temperature gradient reaches 74.48 °C/m. The reflective coating can significantly reduce the track slab’s temperature and vertical temperature gradient, with a maximum temperature gradient reduction of 34%. The transverse temperature gradient of the track slab can be reduced by up to 54% by further application of the side reflective coating. This study can promote the application of reflective coatings on high-speed railway track structures.

In recent years, the use of new and unique building materials to achieve green building goals has attracted a lot of attention. Optical fiber light-transmitting concrete (LTC) makes it possible for light to pass through concrete. Its ornamental value and excellent light transmission have received much attention from scholars. However, the application of optical fiber LTC in the construction industry has not yet been promoted due to the tedious preparation process and insufficient research on its mechanical properties and durability. This paper reviews the research results of optical fiber LTC in terms of product preparation, light transmission, mechanical properties, durability, and microstructures. The light transmission of optical fiber LTCs is positively correlated with fiber content and negatively correlated with fiber diameter and fiber spacing. However, how the combination of these factors affects LTC transmittance remains to be investigated. In addition to fiber parameters, cement matrix properties and other environmental factors (light intensity, incidence angle, and aging) should also be considered to explore the suitability of LTC. The fiber–matrix interface bond strength needs further investigation and efforts should be made to improve it. This paper also summarizes the future challenges and research directions of optical fiber LTC, which is expected to provide guidance for the application of optical fiber LTC. It is anticipated that fiber-optic LTC will be promoted as a new building material.

Cemented carbide used in the rotor of a mud pulser is subjected to the scouring action of solid particles and corrosive mud media for a long time, which causes abrasive wear and electrochemical corrosion. To improve the wear and corrosive resistance of cemented carbide, samples with different cobalt content (WC-5Co, WC-8Co, and WC-10Co) receive deep cryogenic treatment (DCT) at −196 °C for 2.5 h. An optical metalloscope (OM) and X-ray diffractometer (XRD) are used to observe the phase changes of cemented carbides, and the XRD is also used to observe the change in residual stress on the cemented carbide’s surface. A scanning electron microscope (SEM) is used to characterize the wear and electrochemical corrosion surface microstructure of cemented carbides (untreated and DCT). The results show that the DCT promotes the precipitation of the η phase, and the diffraction peak of $\mathsf{\epsilon }$-Co tends to intensify. Compared with the untreated, the wear rates of WC-5Co, WC-8Co, and WC-10Co can be reduced by 14.71%, 37.25%, and 41.01% by DCT, respectively. The wear form of the cemented carbides is mainly the extrusion deformation of Co and WC shedding. The precipitation of the η phase and the increase in WC residual compressive stress by DCT are the main reasons for the improvement of wear resistance. The electrochemical corrosion characteristic is the dissolution of the Co phase. DCT causes the corrosion potential of cemented carbide to shift forward and the corrosion current density to decrease. The enhancement of the corrosion resistance of cemented carbide caused by DCT is due to the Co phase transition, η phase precipitation, and the increase in the compressive stress of cemented carbide.

Microbial syntrophy is a central organizing principle in anoxic soils, where the degradation of organic matter and the cycling of nitrogen, sulfur, and iron are constrained by electron availability and thermodynamics. Among soil anaerobes, Geobacter species occupy a distinctive ecological anoxic niche in which they form syntrophy relationship with partner cells to exchange electrons for anaerobic carbon mineralization, methane production, nitrate reduction, sulfur and Fe(III) reduction. Here, we review how Geobacter -based syntrophy contributes to C/N/S/Fe cycling in anoxic soils. We first summarize the mechanisms of Geobacter -based syntrophy through interspecies electron transfer (IET), then detailedly evaluate how Geobacter -based syntrophy regulates C/N/S/Fe cycling respectively in soils with specific metabolic pathways, enzymes, and ecological outputs. We propose that Geobacter -based syntrophy should be viewed as a redox-partitioning mechanism that determines whether electrons from organic carbon are routed toward methane, ammonium, gaseous nitrogen, minerals, or microbial biomass.