High Temperature Season Research Articles

Observed Impacts of Ground-Mounted Photovoltaic Systems on the Microclimate and Soil in an Arid Area of Gansu, China

Ground-mounted photovoltaic (GMPV) systems are a crucial component of photovoltaic (PV) applications, and their environmental impacts during large-scale development require thorough attention. This study conducted continuous observations at a GMPV plant in an arid region, employing a three-site comparative monitoring system to assess the environmental impact of both shaded and non-shaded areas within GMPV systems. The parameters measured included atmospheric temperature (AT), relative humidity (RH), soil temperature (ST), soil water content (SWC), and wind speed. The results revealed significant diurnal and seasonal variations in AT, with daytime warming and nighttime cooling ranging from 0.1 to 0.7 °C, with particularly large variations observed during high-temperature seasons. Shaded areas under the PV panels exhibited increased RH at night and decreased RH during the day, along with a cooling effect on ST, with a maximum reduction of 7 °C. SWC was higher in shaded areas during dry seasons but exhibited complex redistribution patterns during rainy seasons. Wind speed and direction were notably altered, demonstrating a corridor effect. These findings contrast with previous studies that only focused on the environmental assessment of non-shaded areas within PV systems and external areas using two-site monitoring. This study highlights the critical role of shaded areas in understanding the local environmental impacts of PV systems. This comprehensive approach offers deeper insights into how PV systems influence local meteorological and environmental conditions, suggesting that optimized design and placement of PV systems can enhance their ecological benefits and mitigate adverse environmental impacts in arid regions.

Distribution widening of a ground-nesting social bee across Europe favored by climate change and urban setting

Climate change and/or land use change were repeatedly reported as important for both range expansion of alien bee species and range shrinking for native bee species. However, environmental changes may also positively affect native species that may expand across contiguous areas to their native ones. Here, we focused on Halictus scabiosae (Rossi, 1790) (Hymenoptera: Halictidae), a ground-nesting, primitively eusocial wild bee that has its primary distribution in Western-Southern Europe but that was recently recorded in Eastern-Central Europe. In particular, we studied the range expansion patterns of H. scabiosae, and we hypothesized that previously unsuitable areas may be currently colonized because of environmental changes. In the last 5 years, H. scabiosae moved its densest record areas to North-Eastern Europe, but its ecological niche remained almost unchanged from 1970 to date, suggesting that this bee species is following its preferred conditions (high temperature, high temperature seasonality, and low precipitation seasonality). Potential distribution models revealed high suitability in still unoccupied North-Eastern areas, with urbanization increasingly important as potential stepping stones towards the expansion. The relevant role of urbanization is confirmed by the increase in the number of urban records through time and by the fact that cities with greater population density and greater fragmentation are more likely associated with this species’ occurrence. Halictus scabiosae is thus expanding its range because climate change is producing—and urban environment is offering—suitable conditions in areas previously inadequate for its establishment.

Preparation and indoor virulence determination of a temperature-sensitive insecticide against Zeugodacus cucurbitae (Coquillett).

Zeugodacus cucurbitae (Coquillett) is an important fruit and vegetable pest, especially in high-temperature seasons. In our previous research, we developed a temperature-sensitive sustained-release attractant for Z. cucurbitae, that not only can control the release rate of cuelure according to the temperature change, but also shows an excellent trapping effect on Z. cucurbitae. To further enhance the killing effect of the temperature-sensitive attractant on Z. cucurbitae, this study proposed using it in combination with an insecticide to prepare a temperature-sensitive insecticide for Z. cucurbitae. Based on the controlled release technology of pesticides, a temperature-sensitive Z. cucurbitae insecticide was developed by using PNIPAM gel as a temperature-sensitive switch to carry both cuelure and insecticide at the same time. In addition, the lethal effect of different pesticides on Z. cucurbitae were tested by indoor toxicity test, and the best pesticide combination was screened out. The temperature-sensitive insecticide prepared in this study not only had excellent thermal response and controlled release ability, but also enhanced its toxicological effects on Z. cucurbitae because it contained insecticides. Among them, combining thiamethoxam and clothianidin with the temperature-sensitive attractants was the most effective, and their lethality reached more than 97% against Z. cucurbitae. This study is not only of great practical significance for the monitoring and controlling Z. cucurbitae, but also provides theoretical basis and reference value for the combination of temperature-sensitive attractant and insecticide.

Using ecological niche modelling to prioritise areas for conservation of the critically endangered Buffy-Headed marmoset (Callithrix flaviceps).

Endemic to the Atlantic Forest in Southeastern Brazil, the critically endangered Buffy-Headed marmoset (Callithrix flaviceps) is lacking the required attention for effective conservation. We modelled its ecological niche with the main objectives of (1) defining suitable habitat and (2) prioritising areas for conservation and/or restoration. The current geographical range of Callithrix flaviceps in the Atlantic Forest of Southeast Brazil. We used Ensemble Species Distribution Modelling to define current habitat suitability considering four climate and two landscape variables. To identify areas to prioritise for conservation and/or restoration, we predicted future habitat suitability considering the intermediate (RCP4.5) and extreme (RCP8.5) climate change scenarios for the years 2050 and 2070. Among the variables included to predict current species distribution, tree canopy cover, precipitation seasonality and temperature seasonality were the most important whereas digital elevation model and precipitation during the wettest month were the least important. Callithrix flaviceps was most likely to occur in areas with tree canopy cover >80%, high precipitation seasonality and temperature seasonality between 21 and 23°C. From the future suitability prediction maps, the Caparaó National Park stands out as a likely key area for the preservation of the species. Furthermore, high climatic suitability but low landscape suitability suggests that habitat restoration in 'Serra das Torres' (South of the current distribution area) might be a useful strategy. However, creating ecological corridors on the west side of Caparaó would be necessary to improve connectivity. More surveys within and beyond the current geographical range are required to define more precisely the distribution of the species. Our results support the notion that seasonality is important for Callithrix flaviceps and that as a montane species, it prefers colder environments and higher altitudes. Within both climate change scenarios, Caparaó National Park was predicted to be highly suitable, with a high probability of presence.

Effect of basalt fiber and carbon fiber on the evolution of water evaporation and cracking characteristics of silt soil

Cultivated land is prone to cracking during the high-temperature season, resulting in accelerated water evaporation, incomplete soil structure, and waste of resources caused by pollutants entering the soil. In this study, image analysis technology was used to compare the effects of two kinds of fibers on the drying and shrinkage characteristics of silt under the same volume. The results show that during cracking process, water evaporation can be divided into three phases: constant rate stage, deceleration rate stage, and residual stage. The crack rate of 0.08% basalt fiber-treated soil and 0.06% carbon fiber-treated soil is reduced by 27.66% and 27.98%, respectively. The addition of fibers acts like a bridge, narrowing the concentration of crack width from 0.2–0.8 to 0–0.6 mm, increasing short cracks of 0–5 mm and decreasing long cracks larger than 5 mm, thus reducing the soil cracking rate. With rough surface and high elastic modulus of fibers, the addition of fibers enhances the friction between soil particles to limit the movement of soil mass, and bears part of the tensile stress when cracking. It increases the tensile strength between the soil mass and effectively reduces the crack rate. It is found that the improvement effect of basalt fiber is relatively better and the economic benefit is higher under the same volume.

Temperature monitoring and simulation analysis of the bottom orifices of Baihetan arch dam when outflowing

For flood control, outlet structure is generally installed in the body of the dam. After pouring, the import and export of the orifice will be covered with thermal insulation materials for insulation. When the dam body is used for water storage and diversion, it is necessary to remove the heat preservation quilt. At this time, the lower temperature water will cause a effect called ‘cold shock’ on the surface concrete of the bottom orifices, in addition, under the influence of a combination of external factors such as air and water temperatures, a large temperature gradient will appear on the surface of the concrete, which will easily lead to temperature cracks. In this paper, external environment temperature, water temperature, real-time concrete surface heat exchange coefficient and the effect of solar radiation fever in the high temperature season are considered in the temperature field simulation calculation of single bottom orifice during outflowing. The calculation result indicates the simulation model is highly accurate, and the inaccuracy between the calculated and the measured temperature is within 1 °C, which provides theoretical reference for deep orifices and surface orifices in water discharge, temperature control and crack prevention.

Temperature Response of Double-Layer Steel Truss Bridge Girders

Double-layer steel truss continuous girders are prone to significant temperature stress, deviation, torsion, and warping, thus causing adverse temperature structural responses, and also affecting the safety and durability of bridge structures. This paper presents an investigation on time-dependent characteristics in the temperature field and temperature response of double-layer steel truss continuous bridge girders, fully considering the shielding effect subjected to different solar radiation angles during the high-temperature season. The time-dependent thermal boundary conditions and support conditions provided for the steel truss bridge structure were determined. Subsequently, a thermal analysis model for the entire structure of double-layer steel truss continuous girders was established to attain the temperature distribution law. The research results show that significant differences occur in the position and temperature difference of temperature gradients exhibited in the vertical, horizontal, and longitudinal directions in the double-layer steel truss bridge structure. The temperature distribution pattern within the chord section is mainly influenced by the environmental temperature and solar radiation intensity, along with the heat exchange between different panels. Thereafter, a validated temperature gradient formula for the component section has been proposed. The time-dependent laws in structural displacement, stress, and rotation angle under daily temperature cycling conditions have been revealed, thereby providing a theoretical basis for the life cycle construction and safety maintenance of double-layer steel truss structure bridges.

Mechanistic understanding of how temperature and its variability shape body size composition in moth assemblages

Abstract Understanding how climate affects trait composition within a biological assemblage is critical for assessing and eventually mitigating climate change impacts on the assemblage and its ecological functioning. While body size is a fundamental trait of animals as it affects many aspects of species' biology and ecology, it remains unclear through what mechanisms temperature and its variability influence within‐assemblage body size variation. This study aims to understand how temperature and its variability shape body size variations in animal assemblages and potentially affect assemblages' vulnerability to climate change. Using >5300 individuals of 680 macromoth species collected from 13 assemblages along a ca. 3000 m elevational gradient in Taiwan, we examined (1) the strength of environmental filtering and niche partitioning in determining the intra‐ and inter‐specific size variations within an assemblage, and (2) the effects of mean temperature and the daily and seasonal temperature variabilities on the strength of the two processes. We found that the body size composition was strongly affected by temperature and its seasonality via both processes. High temperature seasonality enhanced niche partitioning, causing within‐population size convergence. In contrast, low mean temperature and low seasonality both enhanced environmental filtering, causing within‐assemblage size convergence. However, while low temperature restricted the lower size limit within an assemblage, low seasonality restricted both lower and upper size limits. This study indicates an overlooked but important role of temperature seasonality in shaping intra‐ and inter‐specific size variations in moth assemblages through both environmental filtering and niche partitioning. With rising temperatures and amplifying seasonality around the globe, potentially weakened filtering forces may increase the size variation within assemblages, reinforcing the assemblage‐level resilience. Nevertheless, enhanced niche partitioning may limit size variation within populations, which may increase the population‐level vulnerability to environmental changes. This study improves the mechanistic understanding of the climatic effects on trait composition in animal assemblages and provides essential information for biodiversity conservation under climate change. Read the free Plain Language Summary for this article on the Journal blog.

Transcriptome Analysis of Gill Tissues from Neptunea cumingii in Different Seasons

Neptunea cumingii is an economically important marine shellfish found in the Yellow and Bohai Seas areas of China. In this study, samples of Neptunea cumingii were collected in Zhangzidao and Yantai during spring, summer, autumn, and winter to clarify the gene expression patterns and regulatory mechanisms in their gills in different seasons. Transcriptome analysis was conducted using Neptunea cumingii gill tissues, and genes with significantly different expression levels were extracted for functional verification. The most genes with differences in expression (DEGs) were found in comparisons of the winter and summer samples. Gene enrichment analysis based on Gene Ontology and Kyoto Encyclopedia of Genes and Genomes terms showed that these DEGs were mainly involved in immune and metabolic pathways, and they had significant effects on oxidative stress, body metabolism, and protein synthesis in Neptunea cumingii. Further screening of DEGs identified thirty-four genes related to temperature regulation, comprising thirteen genes with roles in innate immunity in shellfish, twelve genes related to oxidative stress, and nine genes related to protein synthesis and energy metabolism. Eleven DEGs were randomly selected for qPCR verification, and the results were consistent with the transcriptome analysis results. In summary, the transcriptome results differed significantly between seasons in the gill tissues of Neptunea cumingii. The expression levels of immune regulatory genes could be promoted in Neptunea cumingii during the high temperature season, whereas the expression of these genes may be inhibited in the low temperature season. The results obtained in this study provide insights into the molecular defense mechanisms that might allow Neptunea cumingii to adapt to climate change.

Dengue and climate changes: Increase of DENV-1 in São Paulo/Brazil – 2023

Dengue is a vector borne disease caused by virus serotypes DENV-1, DENV-2, DENV-3, and DENV-4, representing a significant public health concern in the Region of the Americas (2,997,097 cases in 2023). This study explores the relationship between dengue incidence and climate changes in the city of São Paulo-Brazil. During the first semester of 2023, Brazil reported the highest number of dengue cases in Americas’ Region. Our data reveals a correlation between the high temperature and rainfall season persistence and the extension of dengue incidence into the winter season. The findings highlight the importance of understanding the relationship between climate change and disease transmission patterns to develop effective strategies for prevention and control.

Testing concordance and conflict in spatial replication of landscape genetics inferences.

The degree to which landscape genetics findings can be extrapolated to different areas of a species range is poorly understood. Here, we used a broadly distributed ectothermic lizard (Sceloporus occidentalis, Western Fence lizard) as a model species to evaluate the full role of topography, climate, vegetation, and roads on dispersal and genetic differentiation. We conducted landscape genetics analyses with a total of 119 individuals in five areas within the Sierra Nevada mountain range. Genetic distances calculated from thousands of ddRAD markers were used to optimize landscape resistance surfaces and infer the effects of landscape and topographic features on genetic connectivity. Across study areas, we found a great deal of consistency in the primary environmental gradients impacting genetic connectivity, along with some site-specific differences, and a range in the proportion of genetic variance explained by environmental factors across study sites. High-elevation colder areas were consistently found to be barriers to gene flow, as were areas of high ruggedness and slope. High temperature seasonality and high precipitation during the winter wet season also presented a substantial barrier to gene flow in a majority of study areas. The effect of other landscape variables on genetic differentiation was more idiosyncratic and depended on specific attributes at each site. Across study areas, canyon valleys were always implicated as facilitators to dispersal and key features linking populations and maintaining genetic connectivity, though the relative importance varied in different areas. We emphasize that spatial data layers are complex and multidimensional, and careful consideration of spatial data correlation structure and robust analytic frameworks will be critical to our continued understanding of spatial genetics processes.

Global seed dormancy patterns are driven by macroclimate but not fire regime.

Seed dormancy maximizes plant recruitment in habitats with variation in environmental suitability for seedling establishment. Yet, we still lack a comprehensive synthesis of the macroecological drivers of nondormancy and the different classes of seed dormancy: physiological dormancy, morphophysiological dormancy and physical dormancy. We examined current geographic patterns and environmental correlates of global seed dormancy variation. Combining the most updated data set on seed dormancy classes for > 10 000 species with > 4 million georeferenced species occurrences covering all of the world's biomes, we test how this distribution is driven by climate and fire regime. Seed dormancy is prevalent in seasonally cold and dry climates. Physiological dormancy occurs in relatively dry climates with high temperature seasonality (e.g. temperate grasslands). Morphophysiological dormancy is more common in forest-dominated, cold biomes with comparatively high and evenly distributed precipitation. Physical dormancy is associated with dry climates with strong seasonal temperature and precipitation fluctuations (e.g. deserts and savannas). Nondormancy is associated with stable, warm and wetter climates (e.g. tropical rain forest). Pyroclimate had no significant effect on the distribution of seed dormancy. The environmental drivers considered in this study had a comparatively low predictive power, suggesting that macroclimate is just one of several global drivers of seed dormancy.

Can Drip Irrigation without Film Mulching Be Favorable for Potato Growth in Eastern China?

The main measures to improve potato cultivation in eastern China are film mulching and drip irrigation. However, the film can cause soil pollution and inhibit plant growth because of non-degradable polyethylene, which is the main component of the film. Whether drip irrigation without mulching can improve potato yield needs to be fully explored. Field experiments were conducted at the Special Potato Experimental Station, China Agricultural University, Rizhao City, Shandong Province, China, in 2019 and 2020 to investigate the effects of mulching and soil wetted percentage on soil water and temperature distribution, as well as potato growth. In 2019, three treatments with soil wetted percentage of 50% were set up: black plastic film mulching (BMP2), transparent plastic film mulching (TMP2), and no mulching (NMP2). In 2020, soil wetted percentage treatments were added to the existing mulching treatments: no mulching without irrigation (NMP0) and no mulching with soil wetted percentage of 25% (NMP1), 50% (NMP2), and 75% (NMP3); black plastic film mulching without irrigation (BMP0) and black plastic mulching with 50% soil wetted percentage (BMP2); and transparent plastic film mulching with no irrigation (TMP0) and transparent plastic film mulching with 50% soil wetted percentage (TMP2). The results indicated that mulching did not have a significant effect (p < 0.05) on soil temperature, potato growth, and yield. Irrigation reduced soil temperature by a range of 0.4 to 3.0 °C during the high air temperature season. Irrigation significantly increased potato plant height, stem thickness, and yield. The potato yield under the irrigation treatment could be 16.0–24.9% greater than that under the non-irrigation treatment. The highest irrigation water use efficiency (IWUE) was achieved at soil wetted percentage P1 and P2, which were beneficial for water saving. The NMP1 and NMP2 treatments had 83.4% and 81.0% significantly higher IWUE than NMP3 treatment. Considering environmental protection, resource conservation, and economic efficiency, drip irrigation without mulching under soil wetted percentage P2 was suitable for potato cultivation in eastern China.

Permanent Deformation Monitoring and Remaining Life Prediction of Asphalt Pavement Combining Full-Scale Accelerated Pavement Testing and FEM

Permanent deformation (rutting) is one of the typical failure modes of asphalt pavement with a semirigid base in high-temperature areas. To address issues of pavement structure deformation and remaining life prediction, a method of combining accelerated pavement testing and finite element (FE) simulation was proposed. A modified Burgers model considering creep parameter damage was obtained using strain monitoring data and laboratory test values, which was performed in the FE model to analyze rutting development. The results showed that high temperature and heavy axle loads greatly influenced rutting development: the tested road was loaded 360,000 times at high temperature, contributing 50% to accumulated rutting; rutting increased by 90.7% under the condition of 50% overload under high-temperature seasons from the simulated results. Then, the ratio of the bulge area to the depression area (KR) was proposed to define the rutting deformation mechanism. The KR analysis results illustrated that rutting development was a transition process from compaction rutting to flow rutting. Finally, the relationship between the action times of axle load in the tested and in-service roads was established based on the rutting equivalence principle. When the action times of axle load reach approximately 25 million times (insufficient remaining life) for the investigated Hu-Ning highway, necessary maintenance measures should be taken to treat rutting deformation.

Photosynthesis by Leaf Age and Fruit Characteristics by Fruiting Nodes in Vertical and Hydroponic Cultivation of Oriental Melon Applied with Air Duct for High-temperature Season

This study was conducted to apply with an air duct for the cooling and a utilizing cultivating method that uses the fruiting node and the defoliation to the high-temperature vertical and hydroponic cultivation of the oriental melon. The lower fruiting node (LF) was to remove all third vines generated from 5 nodes of a secondary vine. The higher fruiting node (HF) was fruiting on the third vine generated from a first node of the third vine. The direction of the stem string; upward (UW), downward (DW). Four treatment conditions were applied with the LF-UW, LF-DW, HF-UW (control), and HF-DW. The leaf age of melon leaves was measured for photosynthesis at 3 days intervals, and the fruit characteristic was conducted on 79 fruits in each treatment. The photosynthesis rate steadily increased after leaf development, reaching 20.8 µmol CO2·m-2·s-1 on the 10 days, gradually increasing to 21.3 µmol CO2·m-2·s-1 on the 19 days, and reaching 23.4 µmol CO2·m-2·s-1 on the 32 days. After that, it lowered to 16.8 µmol CO2·m-2·s-1 on the 38 days and dropped significantly to 7.6 µmol CO2·m-2·s-1 on the 47 days. As a result of the fruit characteristics by fruiting nodes, the treatments of the fruit length was 12.6-13.4 cm, respectively, which was significant, and the fruit width was 7.9- 8.6 cm, respectively, was not significant. The soluble content ranged from 12.9 to 15.7°Brix, and the significance of all treatments, and higher than of LF-DW and HF-UW. The photosynthesis rate of melon leaves was good until 32 days after leaf development, but after that, the rate decreased. As for fruit quality, it was conformed that melons can be cultivated at the LF because the fruit enlargement and soluble content dose not decrease even when set at the LF. Results indicated that those can be used for LF and defoliation in the development of vertical and hydroponic cultivation method in high-temperature season.

Salicylic acid treatment delayed the browning development in the pericarp of fresh longan by regulating the metabolisms of ROS and membrane lipid

Longans is popular among consumers because of its rich nutritional value, but it is prone to pericarp browning as it is harvested in the high-temperature season. This work was to investigate the effects of salicylic acid (SA) on the metabolisms of reactive oxygen species (ROS) and membrane lipid and their relationship with pericarp browning of postharvest longans. ‘Fuyan’ longans were soaked in the solution of 0.3 g L-1 SA for 5 min, then stockpiled at 28 °C. The results showed that, the pericarp browning index in SA-treated fruit was 42% lower than that in the control fruit at day 5 of storage. Meanwhile, SA treatment reduced the damage severity of cell membrane structure, and maintained a low level of cell membrane permeability, which was 25% lower than that in the control fruit at day 5 of storage. Additionally, compared to the control fruit, SA-treated longans displayed higher levels of pericarp L*, flavonoid, chlorophyll, carotenoid, total phenolics, and anthocyanin, higher activities of pericarp superoxide dismutase, catalase, and ascorbate peroxidase, higher values of pericarp reducing power and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, and higher amounts of pericarp ascorbic acid and glutathione, but lower levels of pericarp ROS and malondialdehyde. Moreover, SA-treated samples exhibited lower activities of pericarp phospholipase, lipase, and lipoxygenase, lower levels of pericarp phosphatidic acid and saturated fatty acids (SFA), but higher values of pericarp phosphatidylcholine, phosphatidylinositol, and unsaturated fatty acids (USFA), higher index of USFA, and higher ratio of USFA to SFA. These findings corroborated that SA delayed-browning occurrence in the pericarp of fresh longans was because SA enhanced the capacity to remove ROS, and reduced ROS accumulation and the membrane lipid degradation, thus maintaining the cellular membrane structure, reducing the degradation of pigments, and allowing the fresh longans to maintain a better appearance. Consequently, SA could be an effective means for suppressing pericarp browning and improving the commercial value of fresh longans.

Effects of far-red light and photoperiod during early growth stages on flower bud development of seed-propagated strawberry seedlings

The effects of far-red (FR) light and photoperiod on flower bud development in seed-propagated strawberry (Fragaria ×ananassa) ‘Elan’ and ‘Yotsuboshi’ cultivars seedlings were investigated to determine lighting conditions that would ensure high-quality strawberry plugs in a controlled environment. The strawberry seedlings were grown for 25 days in a growth chamber under LED illumination with or without FR light. Photoperiod was set at 16 h or 24 h After the light treatment, the seedlings were transplanted into the greenhouse to determine the emergence of their flower buds. In ‘Elan’, FR light and longer photoperiod both promoted flower bud development. However, in ‘Yotsuboshi’, the effect of the light treatment was weaker than in ‘Elan’: only FR light plus a longer photoperiod promoted flower bud development. This difference may be due to cultivar differences in the juvenile period. The percentage of seedlings that had developed flower buds at the end of the light treatment was similar to that of seedlings that emerged flower buds after transplanting in most treatment groups. However, in ‘Yotsuboshi’ seedlings transplanted during the relatively high-temperature season, the percentage of seedlings with an emerged bud after transplanting was much smaller than that of seedlings that developed flower buds by the end of the light treatment. This may be because exposure to high temperatures after transplanting suppressed the development of immature flower buds, which in turn suppressed bud emergence.

Feature extraction of natural gas leakage for an intelligent warning model: A data-driven analysis and modeling

Online monitoring of natural gas in urban underground space has proven to be an effective method for resolving minor leakage and explosion accidents in urban low-pressure natural gas pipelines. However, the harsh environment of urban underground space is often accompanied by the generation of biogas, whose components are more similar to those of natural gas, causing great disturbance to early warning of natural gas leakage. This study correlates the biogas generation principle and its transport law with human activities and environmental changes, analyzes and extracts the characteristics of the natural-gas-biogas CH4 concentration using big data analysis technology, and establishes a natural-gas-biogas sample database. The imbalance between positive and negative samples in the database is addressed by two oversampling techniques. The models trained by two different machine learning algorithms were then evaluated. The results of the study are summarized as follows: (1) There are daily and annual cycles in the CH4 concentration in biogas. The daily trend of biogas in the same manhole is similar, and the biogas in different manholes shows various changes periodically with human activities. Biogas early warnings often occur during the high temperature season (April-September). (2) Features such as period, temperature of alarm, and average concentration over 24 h are positive for improving model accuracy. (3) The combined model of XGBoost and the borderlineSMOTE algorithm has an f-score of 72.7 %, an accuracy of 71.2 %, and a recall of 73.4 %. Compared with the traditional manual classification method, the model proposed in this study can identify natural gas and biogas in a more real-time and accurate manner, reduce the workload of on-site confirmation, and effectively shorten the emergency response time.

Study on Mechanical Characteristics of BRT Asphalt Pavement Structures Based on Temperature Field and Traffic Load

To reveal the mechanical characteristics of BRT asphalt pavement structures under the combined effects of the temperature field and load of buses, a series of finite element analysis models were established in the software application ABAQUS to simulate the Lanzhou BRT asphalt pavement project. The actual BRT road temperature field in summer and loads of buses at different speeds were introduced in the model with user subroutines before conducting a sequentially coupled thermal-mechanical analysis. The results indicated that the BRT asphalt pavement structure readily experienced permanent deformation, mainly comprising unstable rutting during the high-temperature season, and the possibility of cracking was higher for the subbase bottom than for the base. Temperature imposed a greater influence than BRT vehicle frequency. To delay fatigue cracking of the base and subbase and the shear failure of asphalt pavement structures, BRT operating speed should be controlled within 30–40 km/h. In actual BRT asphalt pavement engineering, special attention should be given to the deformation resistance of the intermediate surface layer.

Seasonal differences in intestinal flora are related to rats' intestinal water metabolism.

Many studies have reported obvious seasonal differences in the intestinal flora of rats, and this stable distribution of the seasonal flora helps in maintaining the normal physiological function of the host. However, the mechanism underlying these seasonal differences in intestinal flora remains unclear. To explore the correlation among seasonal factors and intestinal water metabolism and intestinal flora, 20 Sprague Dawley (SD) rats were divided into spring, summer, autumn, and winter groups. The environment for the four seasons was simulated using the Balanced Temperature and Humidity Control system. The intestinal water metabolism was evaluated by determining the intestinal transmission function, fecal water content, water content of colonic tissue, and the colonic expression levels of AQP3, AQP4, and AQP8. The composition and relative abundance of intestinal microflora in rats in each season were assessed through 16S rDNA amplifier sequencing, and the relationship between the dominant flora and intestinal water metabolism in each season was analyzed using Spearman correlation analysis. The high temperature and humidity season could lead to an increase in intestinal water metabolism and intestinal water content in rats, whereas the low temperature and humidity season could lead to a decrease, which was closely related to the change in microflora. To explore the molecular mechanism of seasonal changes in intestinal water metabolism, the concentration of colonic 5-HT, VIP, cAMP, and PKA associated with intestinal water metabolism in rats were also examined. Seasonal changes could affect the concentration of colonic 5-HT and VIP in rats, and then regulate AQPs through cAMP/PKA pathway to affect the intestinal water metabolism. These results suggest that seasonal factors affect the level of intestinal water metabolism in rats and result in seasonal differences in intestinal flora.