Search Results (175)

The global cement industry remains a significant contributor to carbon dioxide (CO₂) emissions, prompting substantial research efforts toward sustainable construction materials. Lithium slag (LS), a by-product of lithium extraction, has attracted attention as a supplementary cementitious material (SCM). This review synthesizes experimental findings on LS replacement levels, fresh-state behavior, mechanical performance (compressive, tensile, and flexural strengths), time-dependent deformation (shrinkage and creep), and durability (sulfate, acid, abrasion, and thermal) of LS-modified concretes. Statistical analysis identifies an optimal LS dosage of 20–30% (average 24%) for maximizing compressive strength and long-term durability, with 40% as a practical upper limit for tensile and flexural performance. Fresh-state tests show that workability losses at high LS content can be mitigated via superplasticizers. Drying shrinkage and creep strains decrease in a dose-dependent manner with up to 30% LS. High-volume (40%) LS blends achieve up to an 18% gain in 180-day compressive strength and >30% reduction in permeability metrics. Under elevated temperatures, 20% LS mixes retain up to 50% more residual strength than controls. In advanced systems—autoclaved aerated concrete (AAC), one-part geopolymers, and recycled aggregate composites—LS further enhances both microstructural densification and durability. In particular, LS emerges as a versatile SCM that optimizes mechanical and durability performance, supports material circularity, and reduces the carbon footprint. Full article

Room-temperature vulcanizing (RTV) silicone foams are used in many industrial applications that require the material to perform over long time periods. However, mechanical properties tend to deteriorate when these foams age under a compressive load. The chemical aging is attributed to the presence of unreacted functional groups of the prepolymers, residues from acid, and catalytically active tin (II) species. Here, an optimized thermal treatment of an RTV foam that achieves completion of curing reactions and deactivation of reactive species is proposed. Foams that were thermally aged for three months under compressive load showed no signs of compression set, indicative of the effectiveness of the implemented post-curing approach. In addition, the effects of fillers (diatomaceous earth, fumed silica, and carbon nanofibers) on thermomechanical properties were investigated. Tensile strength, tear strength, and thermal conductivity increased when these fillers were added to the unfilled RTV formulation, with carbon nanofibers (CNFs) being the most effective filler. Rheological studies of RTV formulations indicated that 2.5 wt.% of CNFs is the upper limit that can be added to the RTV formulation. Full article

Universities in severely cold regions face the dual challenge of adapting to seasonal climate variations while enhancing outdoor thermal comfort in outdoor leisure plazas. This study takes a university in Hohhot as a case study. Through field investigations conducted in summer and winter, thermal benchmarks were established. Based on this, an orthogonal experimental design was developed considering greenery layout, plant types, and surface albedo. ENVI-met was used to simulate and analyze the seasonal regulatory effects of landscape elements on the microclimate. The results show that: (1) the lower limit of the neutral PET range in Hohhot in winter is −11.3 °C, and the upper limit in summer is 31.3 °C; (2) the seasonal contribution of landscape elements to PET ranks as follows: plant types > greenery layout > surface albedo; and (3) the proposed optimization plan achieved a weighted increase of 6.0% in the proportion of activity area within the neutral PET range in both summer and winter. This study is the first to construct outdoor thermal sensation categories for both summer and winter in Hohhot and to establish a thermal comfort optimization evaluation mechanism that considers both diurnal and seasonal weightings. It systematically reveals the comprehensive regulatory effects of landscape elements on the thermal environment in severely cold regions and provides a nature-based solution for the climate-responsive design of campus plazas in such areas. Full article

Plant roots influence various soil physical properties by altering the soil structure and pore configuration; however, a detailed understanding of these effects remains limited. In this study, we applied a relatively simple approach for segmenting plant roots and soil constituents using X-ray computed tomography (CT) images to evaluate root-induced changes in soil structure. The method combines manual initialization with a layer-wise automated region-growing approach, enabling the extraction of the root systems of soybean, Italian ryegrass, and Guinea grass. The method utilizes freely available software with a simple interface and does not require advanced image analysis skills, making it accessible to a wide range of researchers. The soil particles, pore water, and pore air were segmented using a Kriging-based thresholding technique. The segmented four-phase images allowed for the quantification of the volume fractions of soil constituents, pore size distributions, and coordination numbers. Furthermore, by separating the rhizosphere and bulk soil, we found that the root presence significantly reduced solid fractions and increased water content, particularly in the upper soil layers. Macropores and fine pores were observed near the roots, highlighting the complex structural impacts of root growth. While further validation is needed to assess the method’s applicability across different soil types and imaging conditions, it provides a practical basis for visualizing and quantifying root–soil interactions, and could contribute to advancing our understanding of how plant roots influence key soil hydraulic and thermal properties. Full article

Local data about indoor thermal comfort are in short supply, which are always different from the predicted results produced by models shown in previous studies. Shopping malls that consume substantial energy need to save energy, provided that thermal comfort is maintained. Therefore, this research investigated indoor thermal comfort using field measurements and questionnaires in a typical shopping mall in Danyang, China, with a hot summer and cold winter climate in order to explore local demands and energy-saving potential. The findings are as follows: (1) The average air temperature ($T_a$) and operative temperature ($T_{op}$) are 26.7 °C and 26.4 °C, which implies a minor influence from radiation and other factors on $T_a$. Women are more sensitive to changes in outdoor temperature since clothing insulation ($I_{cl}$) varies by gender: 0.31 clo and 0.36 clo for male and female individuals, respectively. (2) The thermal neutral temperature (TNT) derived from the thermal sensation vote (TSV) is 25.26 °C, which is significantly higher than the 21.77 °C obtained from the predicted mean vote (PMV) model. (3) There is a wide range of acceptable temperatures for thermal comfort because the highest temperature was identified by the thermal comfort vote (TCV) at 27.55 °C, followed closely by 27.48 °C, 26.78 °C, and 25.32 °C, which were separately derived from the thermal acceptance vote (TAV), TSV, and predicted percentage of dissatisfied (PPD) people; these were based on an upper limit of the acceptable 80% range. (4) In total, 94.85% of respondents accepted the indoor air quality, although the median concentration of CO₂ was 772 ppm, and the neutral relative humidity level was 70.60%. Meanwhile, there is an important relationship between air quality satisfaction and operative temperature; thus, the temperature (26.93 °C) with peak satisfaction can enhance air quality perception and thermal comfort. (5) The energy savings that can be achieved are 25.77% and 9.12% at most based on acceptable thermal comfort compared with baseline energy consumption at 23 °C and 26 °C, respectively. Full article

Biomass is an energy source with variable physico-chemical properties. Thermal treatments lower moisture and volatile matter contents. They also raise the high heating value (HHV). This is especially desirable for agro-wastes with low-energy potential, like maize cobs. To make pellets from biomass, it is important to keep the lignin intact. It is responsible for particle adhesion. This paper presents a study focused on high-temperature drying of maize cobs. The process temperatures were selected from a range between 60 and 220 °C. The upper temperature limit prevents significant lignin breakdown. We also do not exceed the self-ignition temperature of the raw material. The study analyzed changes in basic technical parameters. These include moisture content, ash content, volatile matter, and HHV. We tested the grinding and densification process. We measured the raw material’s particle size distribution (PSD), specific density, and the mechanical durability (DU) of the agglomerates. The study showed a positive effect of high-temperature drying on the technical parameters. We found that the drying of corn cobs at a temperature of 180 °C gives the best results. Both PSD and DU values indicate that it is possible to create quality compacted biofuels from this material. Full article

Under high-rate charging and discharging conditions, the coupling of phase change materials (PCMs) with liquid cooling proves to be an effective approach for controlling battery pack operating temperature and performance. To address the inherent low thermal conductivity of PCM and enhance heat transfer from PCM to cooling plates, numerical simulations were conducted to investigate the effects of installing fins between the upper and lower cooling plates on temperature distribution. The results demonstrated that merely adding cooling plates on battery surfaces and filling PCM in inter-cell gaps had limited effectiveness in reducing maximum temperatures during 4C discharge (8A discharge current), achieving only a 1.8 K reduction in peak temperature while increasing the maximum temperature difference to over 10 K. Cooling plates incorporating optimized flow channel configurations in fins, alternating coolant inlet/outlet arrangements, appropriate increases in coolant flow rate (0.5 m/s), and reduced coolant inlet temperature (293.15 K) could maintain battery pack temperatures below 306 K while constraining maximum temperature differences to approximately 5 K during 4C discharge. Although increased flow rates enhanced cooling efficiency, improvements became negligible beyond 0.7 m/s due to inherent limitations in battery and PCM thermal conductivity. Excessively low coolant inlet temperatures (293.15 K) were found to adversely affect maximum temperature difference control during initial discharge phases. While reducing the inlet temperature from 300.65 K to 293.15 K decreased the maximum temperature by 10.1 K, it concurrently increased maximum temperature difference by 0.44 K. Full article

The Paleozoic strata in the Kongxi slope zone of the Dagang oilfield, Huanghua depression, exhibit significant hydrocarbon exploration potential. Although bitumen is widely present in the Paleozoic reservoirs, its formation process and genetic mechanism remain poorly understood. This study systematically investigates the occurrence, maturity, origin, and evolutionary processes of Paleozoic reservoir bitumen in the Kongxi zone through core observations, microscopic analyses, geochemical testing, and thermal simulation experiments. The results reveal that reservoir bitumen in the Kongxi slope zone is characteristically black with medium to medium-high maturity. In core samples, bitumen occurs as bands, veins, lines, and dispersions within partially filled fractures and breccia pores. Petrographic analysis shows bitumen partially occupying intergranular pores and intergranular pores of Lower Paleozoic carbonate rocks and Upper Paleozoic sandstones, either as complete or partial pore fills. Additional bitumen occurrences include strip-like deposits along microfractures and as bitumen inclusions. Dark brown bitumen fractions were also identified in crude oil separates. The formation and evolution of Paleozoic reservoir bitumen in the Kongxi slope zone occurred in two main stages. The first-stage bitumen originated from Ordovician marine hydrocarbon source rocks, subsequently undergoing oxidative water washing and biodegradation during tectonic uplift stage. This bitumen retains compositional affinity with crude oils from Lower Paleozoic carbonate rocks. Second-stage bitumen formed through the thermal evolution of Carboniferous crude oil during deeper burial, showing compositional similarities with Carboniferous source rocks and their oil. This two-stage bitumen evolution indicates charging events in the Paleozoic reservoirs. While early uplift and exposure destroyed some paleo-reservoirs, unexposed areas within the Dagang oilfield may still contain preserved primary accumulations. Furthermore, second-stage hydrocarbon, dominated condensates derived from Carboniferous coal-bearing sequences since the Eocene, experienced limited thermal evolution to form some bitumen. These condensate accumulations remain the primary exploration target in the Paleozoic Formations. Full article

The heat transfer mechanism of hollow glass microsphere/epoxy resin composites (HGM/ER) is intricate, and the formation of void structures during material preparation complicates the prediction of thermal conductivity. To investigate the microscopic heat transfer mechanisms of HGM/ER materials with void structures and analyze the impact of void variables on the overall thermal performance, this study addresses the issue of low packing density and poor uniformity in traditional cellular unit structures. An improved random sequential adsorption (RSA) algorithm is proposed, increasing the upper limit of particle fill rate by 25% relative to traditional RSA algorithms. The Benveniste equivalent microsphere thermal conductivity model is selected for thermal performance simulation, demonstrating its high correlation with the three-component model (air, glass, resin), with a maximum relative error of only 1.32%. A classification method for void types in HGM/ER materials is proposed, categorizing them into interfacial and free voids. The microscopic heat transfer mechanisms of HGM/ER materials are investigated under different voids levels and void types, and it was found that the effect of interfacial voids on thermal conductivity is 60% higher than that of free voids. Based on the measured voids of the material, this study provides a reference for the convenient prediction of thermal conductivity in practical engineering applications of HGM/ER composites. Full article

Vertically developing convective clouds (VDCCs), characterized by cloud-top ascent and cooling, are critical precursors to severe convective weather due to their association with intense updrafts. However, existing studies are constrained by limited spatiotemporal resolution of data and tracking methodologies, hindering real-time and pixel-level capture of VDCC evolution. Furthermore, large-scale statistical analyses of VDCC spatiotemporal distribution remain scarce compared with mature convective systems, particularly in topographically complex regions like the Tibetan Plateau (TP). To address these challenges, we integrated an optical flow algorithm (for dense atmospheric motion vector (AMV) retrieval) with cloud-top cooling rates (CTCRs, as indicators of vertical development), leveraging the high spatiotemporal resolution and multispectral capabilities of the GEO-KOMPSAT-2A (GK2A) satellite. This approach achieved pixel-level VDCC detection at 10 min intervals across diurnal cycles, enabling comprehensive statistical analysis. Based on this technical foundation, the most important finding in the study was the distinct convective spatiotemporal distribution over the TP and East Asia (EA) by analyzing VDCC detection data in three summers (2021–2023). Specifically, VDCC diurnal peaks preceded precipitation by 2–3 h, confirming their precursor roles in both study regions. Regional comparisons revealed that topographic and thermal forcing strongly influenced VDCC distribution patterns. The TP exhibited earlier and more frequent daytime convection at middle-to-low levels than EA, driven by intense thermal forcing, yet vertical development was limited by moisture scarcity. In contrast, EA’s monsoonal moisture sustained deeper convection, with more VDCCs penetrating the upper troposphere. The detection and statistical studies of VDCCs offer new insights into convective processes over the TP and surrounding regions, offering potential improvements in severe weather monitoring and early warning systems. Full article

This study investigates the tensile properties of granite subjected to cyclic thermal treatment under cyclic loading-unloading conditions, which is of great significance for the modification of hot dry rock reservoirs. Brazilian splitting tests under cyclic loading-unloading were conducted on granite samples exposed to 400 °C cyclic water-cooling shock (applied for 1, 3, 5, and 7 cycles) at different preset load upper limits (65%, 70%, 75%, and 80% of the peak load). The experimental results reveal the evolution of the tensile properties of granite under the combined effects of 400 °C cyclic water-cooling shock and cyclic loading-unloading. The findings indicate that the tensile strength of granite decreases with an increasing number of cyclic water-cooling shocks and further declines as the preset load upper limit decreases. Under typical conditions, the peak displacement of granite exhibits three distinct stages with increasing loading-unloading cycles: rapid increase, slow increase, and eventual failure. During the slow increase stage, peak displacement decreases due to an increase in elastic stiffness. Initially, elastic stiffness increases with the number of cycles, followed by a stabilization phase, and subsequently declines. After granite failure, macroscopic failure cracks gradually deviate from the center as additional cyclic water-cooling shocks are applied. In contrast, cyclic loading-unloading has a minimal effect on macroscopic cracks. Furthermore, as the number of cycles increases, microcrack evolution transitions from intergranular to transgranular cracking. Under cyclic loading-unloading conditions, these cracks continue to propagate, ultimately forming a fracture network. The findings of this study provide a theoretical foundation for the fracturing and modification of hot dry rock reservoirs. Full article

On 3 March 2024, a new effusive eruption began from a sub-circular fissure on the southeast upper flank of the Fernandina volcano (Galápagos archipelago, Ecuador). Although the eruption posed no threat to people, as the island is uninhabited, it provided an opportunity to test a rapid response system for effusive eruptions, based on satellite infrared (IR) data. In this work, we illustrate how the analysis of data from multiple IR sensors allowed us to monitor the eruption in near real-time (NRT), providing recurrent updates on key parameters, such as (i) lava discharge rate and trend, (ii) erupted lava volume, (iii) lava field area, (iv) active flow front position (v) flow velocity, (vi) location of active vents and breakouts, and (vii) emplacement style. Overall, the eruption lasted 68 days, during which 58.5 ± 29.2 Mm³ of lava was erupted and an area of 14.9 ± 0.5 km² was invaded. The eruption was characterized by a peak effusion rate of 206 ± 103 m³/s, an initial velocity of ~2.3 km/h, and by an almost exponential decline in the effusion rate, accompanied by a transition from channel- to tube-fed emplacement style. The advance of the lava flow was characterized by three lengthening phases that allowed the front to reach the coast (~12.5 km from the vent) after 36 days (at an average velocity of ~0.015 km/h). The results demonstrate the efficiency of satellite thermal data in responding to effusive eruptions and maintaining situational awareness at remote volcanoes where ground-based data are limited or completely unavailable. The requirements, limitations, and future perspectives for applying this rapid response protocol on a global scale are finally discussed. Full article

Laboratory evolution is an effective means of understanding microbial adaptation to the environment. We previously isolated four thermoadapted Zymomonas mobilis mutants, which showed a 2 °C rise in the critical high temperature (CHT), by performing multiple-parallel adaptation experiments. In the present study, the individual mutations in these mutants were intensively analyzed. Two mutations in each adapted mutant were found to primarily contribute to the increase in the upper temperature limit. RNA sequencing (RNA-seq) analysis revealed that the two mutations led to the upregulation of 79–185 genes and the downregulation of 242–311 genes. The findings from transcriptomic and physiological experiments suggest two common and primary mechanisms for thermal resistance: a decrease in the activity of diacylglycerol kinase, which may change the structure of lipopolysaccharide (LPS) probably to strengthen the membrane structure, and an increase in the expression of genes for GroEL/GroES or cell wall hydrolase to repair the protein or membrane damage that occurs at such critical temperatures. Additionally, transporters including efflux pumps may contribute to intracellular homeostasis by expelling toxic compounds such as ethanol and acetate or by maintaining the K⁺ concentration. The results of this study on four independently thermoadapted mutants led to the conclusion that the mutants have almost the same thermal adaptation strategies and thus their molecular diversity is limited. Full article

The globally increased severity and frequency of elevated temperatures are altering native species’ geographic distributions and local abundances while also increasing the invasion of new areas by exotic species. These distributional shifts have affected native species. Through two experiments, we investigated the effects of temperature on the survival and oviposition of the hairy maggot blow fly Chrysomya rufifacies (Macquart), a highly competitive and predatory invasive blow fly of ecological, economic, and forensic importance. In our first experiment, we exposed mixed-sex colonies of C. rufifacies to a given temperature (10–45.0 °C) for 24 h. High survival (≥90%) was observed from 10 to 40 °C, with moderate mortality at 42.5 °C (29.2%) and high mortality at 43.5 °C (75.4%). All flies died when exposed to 44.5 or 45.0 °C for 24 h. Oviposition occurred from 22.5 to 42.5 °C, with the greatest occurrences (100%) at 30 and 35 °C and the greatest number of eggs (2035) occurring at 30 °C. Although oviposition occurred from 22.5 to 42.5 °C, egg viability was only observed from 22.5 to 37.5 °C. Thus, C. rufifacies has distinct thermal limits for survival, and oviposition may exhibit a bet-hedging strategy in response to temperature exposure. In our second experiment, we assessed the effects of an acute heat shock on C. rufifacies oviposition performance. Adult virgins (males and females) were exposed to 25.0 °C, 42.0 °C, or 44.0 °C for 1 h, and then maintained at ~25 °C in mixed-sex colonies for 14 d. Pre-breeding heat exposure had no effect on male or female reproductive success, except for females exposed to 44.0 °C. Females exposed to this temperature before breeding oviposited sooner (2.5 ± 0.0 d, 37.5% decrease), more frequently (0.5 ± 0.4, 33.3% increase), and produced more eggs (10,772.9 ± 2258.6 eggs, 73.3% increase) than female flies exposed to 25 °C. The combined results show that C. rufifacies survives exposures up to 43.5 °C, successfully oviposits up to 37.5 °C, and accelerates both oviposition timing and intensity following brief exposure to near upper lethal temperatures (44.0 °C), potentially provides C. rufifacies a competitive advantage over native calliphorids in warming environments. Full article

Refill friction stir spot welding (RFSSW) is an effective technique for achieving high-quality joints in metallic materials, with rotational speed being a critical parameter influencing joint quality. Current research on RFSSW has primarily focused on low-melting-point materials such as aluminum alloys, while limited attention has been given to pure copper, a material characterized by its high-melting-point and high-thermal-conductivity. This study aims to investigate the effects of rotational speed on the microstructure and mechanical properties of RFSSW joints in pure copper. To achieve this goal, welding experiments were conducted at five rotational speeds. The welding defects, microstructure, and hook morphology of the welded joints were analyzed, while the variations in axial force and torque during welding were studied. The influence of rotational speed on the microhardness and tensile-shear failure load of the welded joints was explored, and the fracture modes of the welded joints at different rotational speeds were discussed. The results indicated that the primary welding defects were incomplete refill and surface unevenness. Higher rotational speeds resulted in coarser microstructures in the stir zones. As the rotational speed increased, the hook height progressively rose, the peak axial force showed an increasing trend, and the peak torque continuously decreased. The high microhardness points in the welded joints were predominantly located at the top of the sleeve stir zone (S-Zone), while the low microhardness points were observed at the center of the pin stir zone (P-Zone) and in the heat-affected zone (HAZ). The tensile-shear failure load of the welded joints initially increased and then decreased on the whole with the rising rotational speed, peaking at 5229 N at a rotational speed of 1200 rpm. At lower rotational speeds, the fracture type of the welded joints was characterized as plug fracture. Within the rotational speed range of 1200 rpm to 1600 rpm, the fracture type transitioned to upper sheet fracture. The initial fractures under different rotational speeds exhibited ductile fracture. This study contributes to advancing the understanding of RFSSW characteristics in high-melting-point and high-thermal-conductivity materials. Full article