广西建设职业技术学院

The development and utilization of underground spaces effectively alleviate social problems such as energy scarcity and environmental pollution. However, the harmful gases produced during construction period of underground spaces posed a serious impact on the health of workers. To efficiently discharge the harmful gases and improve the construction efficiency, a combination of field measurement and numerical simulation was conducted on the spatiotemporal diffusion characteristics of the harmful gases and the safe re-entry time in a T-shaped blasting tunnel with short straight section. The field measurement results indicated that CO was the main target for harmful gas prevention and control. The numerical simulation results showed that the harmful gases produced by the short blasting metro tunnel posed pollution to the non-blasting metro tunnel, and the distribution characteristics of the supply air volume were significantly different from those in long straight tunnels. Furthermore, the relationship between CO diffusion distance in construction channel and ventilation time exhibited a quadratic polynomial function. While the safe re-entry time presented a power function relationship with the average cross-sectional air velocity. The increase of supply air volume can shorten the safe re-entry time, however the shortening effect gradually weakened, accompanied by an increase in ventilation energy consumption. The research can provide valuable insights into the healthy and efficient control of underground construction environments.

This study presents an empirical modeling approach to estimate the abatement of ozone-resistant micropollutants in a pilot-scale ozonation system. The model specifically addresses the unique challenge of these compounds by treating the two distinct phases of ozone decomposition separately. The initial rapid ozone decomposition generates a high concentration of hydroxyl radicals (•OH), which play a dominant role in micropollutant removal. Due to challenges in measuring •OH exposure in this phase, this study proposes an empirical model to predict hydroxyl radical exposure (HT) based on water quality parameters and ozone dosage. In the second phase, micropollutant abatement is modeled based on ozone exposure and the ratio of hydroxyl radical exposure over ozone exposure (R ct). The combined contributions of both phases provide the total abatement efficiency. Key water quality and operational variables are statistically screened and integrated into multivariate regression models to estimate initial ozone demand (IOD), ozone decay rate (k), HT, and R ct. Chlorobenzene, an ozone-resistant compound and common concern in water treatment utilities, serves as a probe compound for model establishment and validation. The modeling results demonstrate strong predictive accuracy (R 2 = 0.89).

Golden camellia (Camellia sect. Chrysantha Chang) is a subgroup of the Camellia subgenus of Theaceae. It is a world-class rare ornamental plant with high medicinal and research value, mainly distributed in southern and southwestern Guangxi province, China and northern Vietnam (Liang, 2007; Nguyen et al., 2019). Leaf spot is the most important fungal disease of golden camellia, which seriously restricts the high-quality production of tea leaf and scented tea. In December 2023, leaf blight were observed on golden camellia in Nanning, Guangxi, with disease incidence ranging from 3% to 10%. The pathogen damaged from margin and the center of leaf, and the lesion in the center of leaf was nearly elliptical. Initial spots were pinhead-sized with a reddish-brown halo margin, then developed into light brown necrotic spots. The necrotic leaf tissue was grayish white with scattered black granules, which were the fruiting bodies of the pathogen, and there was a reddish-brown halo at the junction of disease and health. Infected tissues usually cause leaf blight without shedding. To isolate pathogens from infected leaves, small sections of leaf tissue (5 to 5 mm2) were excised from lesion margins. Five fungi were isolated from five symptomatic trees, respectively. Representative isolate C1 was further characterized. After 5 days of culture on potato dextrose agar (PDA) medium, the fungi produced lush white villous aerial hyphae. After 10 days, a black acervuli containing slimy spore masses formed over the mycelial mats, the back of the petri dish produces a grayish black pigment. Conidia were slightly curved, fusiform to clavate, 5 to 7-celled (mainly 5) with constricted septa. Dimensions were 17.2 to 21.1 × 4.8 to 7.7 µm (n=50), with hyaline apical and basal cells. Apical cells had 1 to 3 (mainly 3) appendages 9.8 to 21.3 µm long . The median cells were brown to olive green. Aerial hyphae of isolate C1 with vigorous growth were collected for molecular identification, partial sequences of the mitochondrial small subunit (SSU), ribosomal DNA internal transcribed spacer (ITS), and nuclear ribosomal large subunit (LSU) genes were amplified and sequenced using the primers pairs of ITS-Fu-F/ITS-Fu-R, ITS1/ITS4 (White et al. 1990) and SRLSU1//SRLSU2 (Kumar et al., 2016), respectively. BLASTn comparison results showed that the SSU (PX048871), ITS (PX048869) and LSU (PX048872) sequences of isolate C1 shared highest similarities with 99.93% (AF346554), 100% (AF377292) and 100% (PQ299649) sequence identity to Pestalotiopsis microspora, respectively. Phylogenetic analysis revealed that C1 shared a common clade with the other strains of P. microspora in GenBank Data Library. Pathogenicity tests were carried out with the following procedure. Plants were maintained in a greenhouse at 28 ± 2°C. After two weeks of inoculation, symptoms identical to those in the field developed on the plants inoculated. In contrast, no symptoms developed on the control. P. microspora has been isolated from tea plants as a endophytic fungus in China (Wei et al, 2007). However, this is the first report of P. microspora infecting golden camellia in China. This work provides crucial information for epidemiologic studies and appropriate control strategies for this newly emerging disease.

Abstract Low-temperature radiant temperatures below the dew point can now be used in hot and humid areas thanks to decoupled radiant cooling technology. In high-temperature, high-humidity air settings, condensation-free low-temperature radiant cooling has been made possible by the materials with high infrared transmittance. It is yet unknown how the human body transfers heat dynamically in low-temperature radiant cooling environments. Thus, a transient heat transport model of the human body in three dimensions was created and validated. In a thermal setting with low-temperature radiation, the dynamic process of the human body was examined. Under low-temperature radiant conditions, the variations in the body’s heat flux and skin temperature were examined. According to the findings, the radiant heat flux on the human body’s upper torso can reach 49 W/m² and the ratio of radiant heat flux can approach 70% once steady-state conditions are met. The human body can reach thermal equilibrium through radiant heat transfer using a low-temperature radiant panel when the initial air temperature is 32 °C and the radiant cooling panel’s temperature is 5 °C. This is possible when the human body’s surface heat flux density is 70 W/m².

Investigating the effects of corrosion on the mechanical and fatigue properties of steel wires is critical for the safety assessment of bridge cable structures.This study focuses on high-strength galvanized steel wires used for bridge cables, with a diameter of 7 mm and a strength grade of 1770 MPa. Specimens with varying mass loss rates η were prepared by electrochemical corrosion method, and systematic tensile and fatigue tests were conducted to study the effects of corrosion on the fundamental mechanical properties and fatigue life of the steel wires. The results indicate that the elastic modulus of the steel wires decreases slightly with the increase of η but still meets the requirements of relevant standards. In contrast, the yield strength and tensile strength degrade significantly, while ductility is particularly susceptible to corrosion, showing more severe deterioration. When η is less than 2.75%, the corroded steel wires still maintain favorable fatigue resistance at a nominal stress amplitude of 360 MPa. Once η exceeds this threshold, their fatigue life decreases significantly in a nonlinear manner with increasing η. The fatigue life predicted by a finite element model (FEM) reconstructed based on the 3D scanning geometry of corroded steel wires and combined with the Abaqus/fe-safe module shows good agreement with the experimental results, indicating that this approach can provide a valuable reference for the durability assessment of bridge cables.