Search Results (147)

The deformation behavior of polymers is influenced not only by service conditions such as temperature and the strain rate but also significantly by the formation process. However, existing simulation frameworks typically treat injection molding and the in-service mechanical response separately, making it difficult to capture the impact of the thermal history on large deformation behavior. In this study, the deformation behavior of injection-molded polycarbonate (PC) was investigated by accounting for its thermal history during formation, achieved through combined experimental characterization and constitutive modeling. PC specimens were prepared via injection molding followed by annealing at different molding/annealing temperatures and durations. Uniaxial tensile tests were conducted using a Zwick universal testing machine at strain rates of 10⁻³–10⁻¹ s⁻¹ and temperatures ranging from 293 K to 353 K to obtain stress–strain curves. The effects of the strain rate, testing temperature, and annealing conditions were thoroughly examined. Building upon a previously proposed phenomenological model, a new constitutive framework incorporating thermal history effects during formation was developed to characterize the large deformation behavior of PC. This model was implemented in ABAQUS/Explicit using a user-defined material subroutine. Predicted stress–strain curves exhibit excellent agreement with the experimental data, accurately reproducing elastic behavior, yield phenomena, and strain-softening and strain-hardening stages. Full article

Breeding programs often overlook the use of root traits. Therefore, we investigated the relevance of sorghum root traits in explaining its adaptation to combined drought and heat stress (CDHS). Six (i.e., three pre-release lines + three checks) sorghum genotypes were established at two low-altitude (i.e., <600 masl) locations with a long-term history of averagely very high temperatures in the beginning of the summer season, under two management (i.e., CDHS and well-watered (WW)) regimes. At each location, the genotypes were laid out in the field using a randomized complete block design (RCBD) replicated two times. Root trait data, namely root diameter (RD), number of roots (NR), number of root tips (NRT), total root length (TRL), root depth (RDP), root width (RW), width–depth ratio (WDR), root network area (RNA), root solidity (RS), lower root area (LRA), root perimeter (RP), root volume (RV), surface area (SA), root holes (RH) and root angle (RA) were gathered using the RhizoVision Explorer software during the pre- and post-flowering stage of growth. RSA traits differentially showed significant (p < 0.05) correlations with grain yield (GY) at pre- and post-flowering growth stages and under CDHS and WW conditions also revealing genotypic variation estimates exceeding 50% for all the traits. Regression models varied between pre-flowering (p = 0.013, R² = 47.15%, R² Predicted = 29.32%) and post-flowering (p = 0.000, R² = 85.64%, R² Predicted = 73.30%) growth stages, indicating post-flowering as the optimal stage to relate root traits to yield performance. RD contributed most to the regression model at post-flowering, explaining 51.79% of the 85.64% total variation. The Smith–Hazel index identified ICSV111IN and ASAREACA12-3-1 as superior pre-release lines, suitable for commercialization as new varieties. The study demonstrated that root traits (in particular, RD, RW, and RP) are linked to crop performance under CDHS conditions and should be incorporated in breeding programs. This approach may accelerate genetic gains not only in sorghum breeding programs, but for other crops, while offering a nature-based breeding strategy for stress adaptation in crops. Full article

This work investigated the structural response and phase transformation dynamics of silica-bearing cherts subjected to high-temperature processing (up to 1400 °C) and prolonged mechanochemical activation. Through a combination of X-ray diffraction (XRD) with Rietveld refinement, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and transmission electron microscopy (HRTEM), we trace the crystallographic pathways of quartz, moganite, tridymite, and cristobalite under controlled thermal and mechanical stress regimes. The experimental results demonstrated that phase behavior is highly dependent on intrinsic properties such as initial phase composition, impurity presence, and crystallinity. Heating at 1400 °C induced irreversible conversion of quartz, moganite, and tridymite into cristobalite. Samples enriched in cristobalite and tridymite exhibited notable increases in crystallinity, whereas quartz-dominant samples showed either stability or a decline in structural order. Rietveld analyses underscored the critical influence of microstrain and crystallite size on thermal resilience and phase persistence. Thermal profiles revealed by DSC and TGA expose overlapping processes including polymorphic transitions, minor phase dehydration, and redox-driven changes, likely associated with trace components. Mechanochemical processing resulted in partial amorphization and the emergence of phases such as opal and feldspar minerals (microcline, albite, anorthite), interpreted as the product of lattice collapse and subsequent reprecipitation. Heat treatment of chert leads to a progressive rearrangement and recrystallization of its silica phases: quartz collapses around 1000 °C before recovering, tridymite emerges as an intermediate phase, and cristobalite shows the greatest crystallite size growth and least deformation at 1400 °C. These phase changes serve as markers of high-temperature exposure, guiding the identification of heat-altered lithic artefacts, reconstructing geological and diagenetic histories, and allowing engineers to adjust the thermal expansion of ceramic materials. Mechanochemical results provide new insights into the physicochemical evolution of metastable silica systems and offer valuable implications for the design and thermal conditioning of silica-based functional materials used in high-temperature ceramics, glasses, and refractory applications. From a geoarchaeological standpoint, the mechanochemically treated material could simulate natural weathering of prehistoric chert tools, providing insights into diagenetic pathways and lithic degradation processes. Full article

In this article, we consider the roles of transcrustal magma- and fluid-conducting faults (TCMFCFs) in the formation of mineral deposits, showing the importance of deep sources of heat and hydrothermal solutions in the genesis and history of deposit formation. As a result of the impact on the lithosphere of mantle plumes rising along TCMFCFs, intense block deformations and tectonic movements are generated; rift systems, and volcanic–plutonic belts spatially combined with them, are formed; and intrusive bodies are introduced. These processes cause epithermal ore formation as a consequence of the impact of mantle plumes rising along TCMFCF to the lithosphere. At hydrocarbon fields, they play extremely important roles in conductive and convective heat, as well as in mass transfer to the area of hydrocarbon generation, determining the relationship between the processes of lithogenesis and tectogenesis, and activating the generation of hydrocarbons from oil and gas source rock. Detection of TCMFCFs was carried out using MMSS (the method of microseismic sounding) and MTSM (the magnetotelluric sounding method), in combination with other geological and geophysical data. Practical examples are provided for mineral deposits where subvertical transcrustal columns of increased permeability, traced to considerable depths, have been found; the nature of these unique structures is related to faults of pre-Paleozoic emplacement, which determined the fragmentation of the sub-crystalline structure of the Earth and later, while developing, inherited the conditions of volumetric fluid dynamics, where the residual forms of functioning of fluid-conducting thermohydrocolumns are granitoid batholiths and other magmatic bodies. Experimental modeling of deep processes allowed us to identify the quantum character of crystal structure interactions of minerals with “inert” gases under elevated thermobaric conditions. The roles of helium, nitrogen, and hydrogen in changing the physical properties of rocks, in accordance with their intrastructural diffusion, has been clarified; as a result of low-energy impact, stress fields are formed in the solid rock skeleton, the structures and textures of rocks are rearranged, and general porosity develops. As the pressure increases, energetic interactions intensify, leading to deformations, phase transitions, and the formation of chemical bonds under the conditions of an unstable geological environment, instability which grows with increasing gas saturation, pressure, and temperature. The processes of heat and mass transfer through TCMFCFs to the Earth’s surface occur in stages, accompanied by a release of energy that can manifest as explosions on the surface, in coal and ore mines, and during earthquakes and volcanic eruptions. Full article

The load spectrum serves as the foundation for the life analysis of aero-engine turbine disks. To enhance the accuracy of life assessments for turbine disks, this study compiles a time-varying load spectrum for turbine disks. Firstly, a surrogate model for transient processes at the critical points of turbine disks is established, enabling the rapid evaluation of the transient temperature and thermal stress at these points under complex loading histories. Secondly, a performance degradation model is established based on real engine test data, explicitly describing the general trend of performance degradation characteristics with respect to the cycle number and engine power. Finally, a time-varying load spectrum for turbine disks is compiled, considering both short-term transient processes and long-term performance degradation. The life of turbine disks at the fir-tree slot root and disk bore is assessed using the Manson–Coffin equation, Wilshire equation, and linear damage accumulation rule. The results indicate that neglecting transient processes leads to conservative life assessment results while neglecting performance degradation leads to dangerous life assessment results. Compared with traditional methods, the time-varying load spectrum significantly improves the accuracy and scientific nature of turbine disk life assessment. Full article

Plant U-box E3 ubiquitin ligases (PUBs) serve as crucial regulators of protein degradation and are fundamentally involved in plant developmental processes and stress response mechanisms. Despite their well-characterized roles in model plant species, the PUB gene family in the hybrid poplar (Populus alba × P. tremula var. glandulosa) remains poorly understood. By conducting a comprehensive genome-wide analysis, we identified 152 PUB genes in poplar and phylogenetically classified them into five distinct clades based on a comparative analysis with Arabidopsis thaliana and tomato PUB homologs. The structural characterization revealed that numerous PagPUB proteins possess additional functional domains, including ARM and WD40 repeats, which are indicative of potential functional diversification. Genomic distribution and synteny analyses demonstrated that the expansion of the PUB gene family predominantly resulted from whole-genome duplication (WGD) events, with evolutionary constraint analyses (Ka/Ks ratios < 1) suggesting strong purifying selection. An examination of the promoter region uncovered an abundance of stress-responsive cis-elements, particularly ABRE and MYB binding sites associated with abiotic stress and hormonal regulation. Transcriptome profiling demonstrated both tissue-specific expression patterns and dynamic regulation under diverse stress conditions, including drought, salinity, temperature extremes, and pathogen infection. Our findings provide the first systematic characterization of the PUB gene family in poplar and establish a valuable framework for elucidating their evolutionary history and functional significance in environmental stress adaptation. Full article

Temperature is a key environmental factor that influences mosquito phenotypic traits and the effectiveness of vector control strategies. Bacillus velezensis (Bv) has shown promise as a microbial biocontrol agent due to its insecticidal properties; however, its effects on mosquitoes under different environmental conditions are still unexplored. This study investigated the effects of Bv (strain WHk23) exposure on the life history traits of Culex quinquefasciatus at two temperature conditions (20 °C and 30 °C), focusing on development, longevity, and reproductive fitness. Results showed that temperature significantly affected mosquito development and longevity, with faster development and shorter adult longevity observed at 30 °C compared to 20 °C. Exposure to Bv further accelerated larval development and reduced adult emergence, with the effects being more pronounced at 30 °C than at 20 °C. Exposure to Bv reduced adult longevity regardless of temperature. In addition, Bv-exposed females had larger body sizes but lower fecundity and fertility, suggesting that Bv exposure may cause physiological stress that disrupts reproductive processes. These findings highlight the importance of considering environmental factors in mosquito control programs while reinforcing the efficacy of Bv as a sustainable biocontrol agent under a variety of environmental conditions. Full article

High-redshift active galactic nuclei (AGN) provide key insights into early supermassive black hole growth and cosmic evolution. This study investigates the parsec-scale properties of 86 radio-loud quasars at z ≥ 3 using very long baseline interferometry (VLBI) observations. Our results show predominantly compact core and core-jet morphologies, with 35% having unresolved cores, 59% with core–jet structures, and only 6% with core–double jet morphology. Brightness temperatures are generally lower than expected for highly radiative sources. The jets’ proper motions are surprisingly slow compared to those of lower-redshift samples. We observe a high fraction of young and/or confined peak-spectrum sources, providing insights into early AGN evolution in dense environments during early cosmic epochs. The observed trends may reflect genuine evolutionary changes in AGN structure over cosmic time, or selection effects favoring more compact sources at higher redshifts. These results stress the complexity of high-redshift radio-loud AGN populations and emphasize the need for multi-wavelength, high-resolution observations to fully characterize their properties and evolution through cosmic history. Full article

This paper investigates the effect of fiber-reinforced composites (FRPs) on the mechanical properties of concrete under ambient conditions. It begins with an examination of the various types of FRP and their advantages, followed by a review of isostructural models for passively restrained concrete under ambient conditions. These models are categorized into two main groups: those assuming constant confining stresses and those that incorporate stress constraints related to the loading history. Recent studies have highlighted the significant role of stress paths in determining the stress–strain behavior of concrete. Traditional methods for predicting the FRP-constrained concrete reinforcement bond at room temperature are increasingly being replaced by machine learning techniques, such as Artificial Neural Networks (ANNs) and Genetic Expression Programming (GEP), which offer superior accuracy in predicting the FRP-constrained concrete bond strength and the compressive properties of FRP-confined concrete columns. In particular, experimental results show that the compressive strength of FRP-confined concrete columns can increase by up to 30–250%. This review offers valuable insights into the effects of FRP on concrete and contributes to the advancement of engineering design practices. Full article

Powder bed fusion–laser beam (PBF-LB) additive manufacturing enables the production of intricate, lightweight metal components aligned with Industry 4.0 and sustainable principles. However, residual stresses and distortions challenge the dimensional accuracy and reliability of parts. Inherent strain methods (ISMs) provide a computationally efficient approach to predicting these issues but often overlook transient thermal histories, limiting their accuracy. This paper introduces an enhanced inherent strain method (EISM) for PBF-LB, integrating macro-scale temperature histories into the inherent strain framework. By incorporating temperature-dependent adjustments to the precomputed inherent strain tensor, EISM improves the prediction of residual stresses and distortions, addressing the limitations of the original ISM. Validation was conducted on two Ti-6Al-4V geometries—a non-symmetric bridge and a complex structure (steady blowing actuator)—through comparisons with experimental measurements of temperature, distortion, and residual stress. Results demonstrate improved accuracy, particularly in capturing localized thermal and mechanical effects. Sensitivity analyses emphasize the need for adaptive layer lumping and mesh refinement in regions with abrupt stiffness changes, such as shrink lines. While EISM slightly increases computational cost, it remains feasible for industrial-scale applications. This work bridges the gap between simplified inherent strain models and high-fidelity simulations, offering a robust tool for simulation-driven optimisation. Full article

The operation of floating nuclear power plants is subject to a number of environmental factors in addition to the typical working temperature and pressure loads. These include marine environmental loads, which can cause fatigue damage and therefore must be taken into account. The fatigue analysis of marine structures frequently employs frequency domain methods, whereas the fatigue analysis of pressure equipment predominantly utilizes time-domain methods. At present, there is no comprehensive and accessible approach for conducting a fatigue analysis of pressure equipment in floating nuclear power plants. In light of the aforementioned considerations, this paper puts forth a novel approach to evaluating fatigue damage based on the principle of damage combination. This article presents a finite element model of pressure equipment and a methodology for calculating the transfer function of such equipment under wave loads. The frequency domain method is employed to calculate the fatigue damage caused by wave loads, with consideration given to both the working temperature and pressure load. The stress time history curve of pressure-bearing equipment is then calculated using the time-domain method. Subsequently, the fatigue damage caused by thermal pressure loads is obtained through a combination of the rainflow counting method and cumulative damage theory, with verification conducted using time-domain calculations. In comparison to alternative damage combination methodologies, the novel approach offers more precise and straightforward damage calculations, with promising potential for integration into engineering design. Full article

The performance of the selective electron beam melting (SEBM) products depends on the SEBM-induced temperature and stress. Here, the thermomechanical finite element simulations are conducted to investigate the dynamic evolution of temperature and the thermal stress of melt pool during the SEBM process of Ti6Al4V alloys under various processing parameters and scanning strategies. The results show that the melt pool undergoes three stages of preheating, melting, and remelting under the influence of adjacent scanning tracks. This complex thermal history drives significant changes in thermal stress within the melt pool. After adjusting the processing parameters, it is found that a low scanning speed and high electron beam energy result in a high temperature gradient and stress in the molten pool. Compared to the electron beam energy, the scanning speed has a more significant impact on temperature and residual stress. For the dual-electron-beam scanning strategy, the coupling thermal effect between electron beams can reduce the temperature gradient of the melt pool, thereby suppressing the formation of columnar crystals. The electron beam energy of 300 W and the scanning speed of 1.5 m/s can be selected under various scanning strategies, which are expected to suppress the formation of coarse and columnar β grains and achieve relatively low residual stress. These results contribute to providing a theoretical basis for selecting optimized process parameters and scanning strategies. Full article

The utilization of reclaimed asphalt pavement (RAP) in asphalt mixtures not only reduces production costs and resource consumption but also provides significant environmental benefits. Consequently, technology and methodologies used for asphalt pavement recycling, aimed at enhancing the utilization rate of RAPs, have emerged as prominent topics in both academic research and engineering practice. Given the complex thermal history and poor low-temperature performance (LTP) of RAP, investigating the effects of varying thermal histories of RAPs on the LTP of a mixture holds substantial practical significance for increasing the utilization rate of RAP in seasonally frozen regions. In this study, scanning electron microscopy (SEM), the thermal stress restrained specimen test (TSRST), the trabecular bending test, and the bending beam creep test (BBCT) are utilized to examine the effects of the indoor simulation methods that produce RAPs with varying thermal histories and contents on a recycled asphalt mixture (RAM) from both microscopic and phenomenological perspectives. Additionally, this research investigates the accuracy of predicting the LTP of RAMs using the Burgers model. The test results indicate that the LTP of an RAM is influenced not only by the RAP content and its thermal history but also by the ambient temperature. Regardless of the thermal history of the RAP, the LTP of an RAM tends to decrease as the RAP content increases. Different thermal histories of RAPs exert varying effects on the low-temperature viscoelastic behavior of an RAM. The UVRAP reduces the viscoelastic temperature range of an RAM by an average of 10.79%, whereas the THRAP increases it by an average of 2.16%. These effects can be attributed to the distinct micromorphology of the asphalt on the surfaces of RAPs with a varying thermal history. Specifically, a greater number of micropores and microcracks on the asphalt surface leads to a poorer LTP of RAMs. Additionally, the residuals of the Burgers model for predicting the LTP of an RAM with THRAP exceeded −2. However, the Burgers model demonstrates predictive capabilities for evaluating the LTP of an RAM filled with RAP from the same source or with a similar thermal history. Full article

Gynostemma pentaphyllum is a traditional Chinese medicinal plant of considerable application value and commercial potential, primarily due to its production of various bioactive compounds, particularly dammarane-type triterpenoid saponins that are structurally analogous to ginsenosides. Oxidosqualene cyclase (OSC), a pivotal enzyme in the biosynthesis of triterpenoid metabolites in plants, catalyzes the conversion of oxidosqualene into triterpenoid precursors, which are essential components of the secondary metabolites found in G. pentaphyllum. To elucidate the role of OSC gene family members in the synthesis of gypenosides within G. pentaphyllum, this study undertook a comprehensive genome-wide identification and characterization of OSC genes within G. pentaphyllum and compared their expression levels across populations distributed over different geographical regions by both transcriptome sequencing and qRT-PCR experimental validation. The results identified a total of 11 members of the OSC gene family within the genome of G. pentaphyllum. These genes encode proteins ranging from 356 to 767 amino acids, exhibiting minor variations in their physicochemical properties, and are localized in peroxisomes, cytoplasm, plasma membranes, and lysosomes. All GpOSCs contain highly conserved DCTAE and QW sequences that are characteristic of the OSC gene family. A phylogenetic analysis categorized the GpOSCs into four distinct subfamilies. A cis-element analysis of the GpOSC promoters revealed a substantial number of abiotic stress-related elements, indicating that these genes may respond to drought conditions, low temperatures, and anaerobic environments, thus potentially contributing to the stress resistance observed in G. pentaphyllum. Expression analyses across different G. pentaphyllum populations demonstrated significant variability in OSC gene expression among geographically diverse samples of G. pentaphyllum, likely attributable to genetic variation or external factors such as environmental conditions and soil composition. These differences may lead to the synthesis of various types of gypenosides within geographically distinct G. pentaphyllum populations. The findings from this study enhance our understanding of both the evolutionary history of the OSC gene family in G. pentaphyllum and the biosynthetic mechanisms underlying triterpenoid compounds. This knowledge is essential for investigating molecular mechanisms involved in forming dammarane-type triterpenoid saponins as well as comprehending geographical variations within G. pentaphyllum populations. Furthermore, this research lays a foundation for employing plant genetic engineering techniques aimed at increasing gypenoside content. Full article

Basal metabolic rates (BMRs) increase with temperature and body mass. Environmental temperatures rapidly change in tropical mountains due to elevation (macro scale) and vegetation structure (micro scale). Thus, tropical mountains are good settings for testing the effects of temperature on BMRs. We measured the BMRs at four temperature ranges on six territorial and closely related species of Rubyspot damselflies (Hetaerina, Calopterygidae), which also share very similar behavior and morphology and are segregated by habitat and elevation across the Western Colombian Andes. We analyzed the effects of body mass, habitat, elevation, temperature, and sex on their BMRs, using a phylogenetic framework. We found that the main factors regulating their niche partition seemed to be environmental temperature, body size, and BMR. We found differences in their BMRs related to elevation when the temperatures were close to those experienced by the damselflies at their elevational range. As predicted, the larger species associated with colder habitats, forests, and highlands had higher BMRs. However, at high stressful temperatures, only the body mass was positively related to the BMR, showing that smaller individuals can keep their BMRs lower under high temperatures compared to bigger ones. Habitat use was not associated with changes in the BMR. Finally, phylogenetic reconstruction showed all species clustered in three clades. Each clade in the phylogenetic tree shares similar habitat preferences, pointing to a mixture of evolutionary history, thermal adaptations, and body mass differences as a possible explanation for the great diversity of these damselflies in a small area. Under the global warming scenario, we expect Rubyspots with smaller body sizes to be favored since they will tolerate higher temperatures, which would ultimately lead to populations with smaller body sizes overall, which could negatively affect their fitness. Full article