Search Results (2,529)

Brassinosteroids (BRs) are recognized for their ability to enhance plant salt tolerance. While considerable research has focused on their effects under neutral salt conditions, the mechanisms through which BRs regulate photosynthesis under alkaline salt stress are less well understood. This study investigates these mechanisms, examining plant growth, photosynthetic electron transport, gas exchange parameters, Calvin cycle dynamics, and the expression of key antioxidant and Calvin cycle genes under alkaline stress conditions induced by NaHCO₃. The findings indicate that NaHCO₃ stress substantially impairs cucumber growth and photosynthesis, significantly reducing chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII), antenna conversion efficiency (Fv′/Fm′), and photochemical quenching coefficient (qP). This disruption suggests a severe dysregulation of the photosynthetic electron transport system, impairing electron transfer from photosystem II (PSII) to photosystem I (PSI) and subsequently the Calvin cycle. Application of exogenous 24-epibrassinolide (EBR) alleviated these effects, reducing leaf chlorosis and growth inhibition and significantly enhancing the expression of key genes within the antioxidant system (AsA-GSH cycle) and the Calvin cycle. This intervention also led to a reduction in reactive oxygen species (ROS) accumulation and improved photosynthetic performance, as evidenced by enhancements in Pn, Gs, E, Fv/Fm, ΦPSII, Fv′/Fm′, and qP. Moreover, NaHCO₃ stress hindered chlorophyll synthesis, primarily by blocking the conversion from porphobilinogen (PBG) to uroporphyrinogen III (UroIII) and by increasing chlorophyllase (Chlase) and decreasing porphobilinogen deaminase (PBGD) activity. Exogenous EBR countered these effects by enhancing PBGD activity and reducing Chlase activity, thereby increasing chlorophyll content under stress conditions. In summary, EBR markedly mitigated the adverse effects of alkaline stress on cucumber leaf photosynthesis by stabilizing the photosynthetic electron transport system, accelerating photosynthetic electron transport, and promoting the Calvin cycle. This study provides valuable insights into the regulatory roles of BRs in enhancing plant resilience to alkaline stress. Full article

Millions of tonnes of plastic and glass waste are generated worldwide, with only a marginal amount fed back into recycling with the majority ending at landfills and stockpiles. Excessive waste production calls for additional recycling pathways. The technology being investigated in this study is based on recycled glass fines encapsulated in a high-density polyethylene (HDPE) matrix. Laboratory tests are performed on specimens at different manufacturing conditions using compression moulding, determining an optimised manufacturing method. The performance of composites prepared under different formulations is tested to identify an optimised mix design by means of statistical analysis. At this optimum ratio, flexural, tensile, and compressive strengths of 33.3 MPa, 19.6 MPa, and 12.8 MPa, are, respectively, recorded. Upon identifying the optimum dosage levels, the potential for employing HDPE from diverse origins are investigated. The microstructure, pore structure, and chemistry of optimised composite specimens are analysed to interpret the composite performance. The effective stress transfer in the composite is attributed to strong hydrogen bonds created by maleic anhydride leading to 37.6% and 8.5% improvements in compressive and flexural strengths, respectively. These research findings can facilitate the pathway for utilising plastic and glass waste in landfills/stockpiles for sustainable polymeric composites towards structural applications. Full article

To sustain agricultural productivity and safeguard global food security, and confront the escalating challenges posed by climate change and water scarcity, it is essential to enhance the growth and productivity of rice under water stress. This study investigated the effects of lanthanum chloride on the chlorophyll fluorescence characteristics and grain yield of rice under different irrigation modes. The rice cultivar H You 518 was selected and sprayed 20, 100, or 200 mg·L⁻¹ lanthanum chloride at the booting and heading stages under deficit irrigation (where no rewatering was applied after the initiation of stress, allowing the water layer to evaporate naturally under high temperatures) or conventional irrigation (with daily rewatering to maintain a consistent water level). The results showed that the application of low concentrations lanthanum chloride promoted the chlorophyll content, whereas high concentrations decreased the chlorophyll content, under deficit irrigation, the effect of lanthanum chloride on the green fluorescence parameters of rice leaves at the booting stage was greater than that at the heading stage, and the booting stage was more sensitive to water deficit. The application of 100 mg·L⁻¹ lanthanum chloride reduced the initial fluorescence (F0) and the non-photochemical quenching coefficient (qN); promoted the activity of leaf photosynthetic system II (PSII); and maximized the photochemical quantum yield (Fv/Fm), photochemical quenching coefficient (qP), and PSII relative electron transfer efficiency (ETR). Under deficit irrigation, this treatment significantly enhanced grain yield by increasing the thousand-grain weight, spikelet filling rate, and number of grains per panicle. These results suggest that spraying 100 mg·L⁻¹ lanthanum chloride at the booting stage under deficit irrigation can effectively increase the chlorophyll content, thereby increasing the light energy conversion efficiency of the PS II reaction center, ultimately resulting in increased spikelet filling rate and grain yields. Full article

In recent years, steel-fiber-reinforced concrete (SFRC) has been increasingly applied in shield tunnel engineering. However, most research on SFRC segments focuses on the load-bearing capacity, while the tunnel deformation is an equally critical indicator that decides if the tunnel can operate safely during service conditions. Therefore, it is essential to also study the stiffness variations in SFRC segments, which is closely connected to the serviceability limit state (SLS). To investigate the influence of SFRC on segment stiffness, full-scale four-point bending tests and analytical calculations are carried out on both traditional reinforced concrete (RC) segments and SFRC segments with rebars. A C55 plain concrete is used in the RC segment, and for SFRC, 30 kg/m³ steel fibers are added. The segment stiffnesses are calculated and analyzed, and compared between test and analytical results. This study shows that the addition of steel fibers to traditional reinforced concrete segments can enhance the bending stiffness. This effect becomes apparent only after the segments crack. Initially, the effect is strong but then becomes weaker, with increasing load. The added 30 kg/m³ steel fibers generate a maximum of 33% in stiffness increment for a segment with 2.1% reinforcement. Further analysis indicates that the transfer of stresses in the cracked SFRC results in a stiffness improvement, but after cracking, the contribution of the reinforcement to the flexural resistance increases while the contribution of the SFRC gradually decreases. Thus, the effect is weak at high load levels. This paper contributes to a better understanding of the effect of SFRC on the stiffness of segments, as relevant for SLS requirements. Full article

This study presents analytical solutions grounded in three-dimensional (3D) thermo-elasticity theory to predict the bending behavior of cross-laminated timber (CLT) panels under thermo-mechanical conditions, incorporating the orthotropic and temperature-dependent properties of wood. The model initially utilizes Fourier series expansion based on heat transfer theory to address non-uniform temperature distributions. By restructuring the governing equations into eigenvalue equations, the general solutions for stresses and displacements in the CLT panel are derived, with coefficients determined through the transfer matrix method. A comparative analysis shows that the proposed solution aligns well with finite element results while offering superior computational efficiency. The solution based on the plane section assumption closely matches the proposed solution for thinner panels; however, discrepancies increase as panel thickness rises. Finally, this study explores the thermo-mechanical bending behavior of the CLT panel and proposes a modified superposition principle. The parameter study indicates that the normal stress is mainly affected by modulus and thermal expansion coefficients, while the deflection of the panel is largely dependent on thermal expansion coefficients but less affected by modulus. Full article

The paulownia tree belongs to the Paulowniaceae family. Paulownia has strong vitality; has strong adaptability to harsh environmental conditions; and can be used as building raw material, as well as processing drugs and having other purposes. In the research field of MYB transcription factors of the paulownia tree, it is rare to discuss the resistance to abiotic stress. The research in this area has not received sufficient attention and depth, which also indicates an important potential direction for future research. In this study, we performed bioinformatics analysis of the stress-related gene PfMYB90, a potential transcription factor, and investigated its mechanism of action under salt and cold stresses. PfMYB90 was strongly expressed in the fully unfolded leaf and root of plants in both stress treatments. Transgenic PfMYB90 Arabidopsis plants had a greater survival rate under salt and cold stresses, and the degree of leaf damage was comparatively smaller, according to phenotypic observation and survival rate calculations. By measuring the corresponding physiological indexes after stress and detecting the expression levels of corresponding stress genes (AtNHX1, AtSOS1, AtSOS2, AtSOS3, AtCBF1, AtCBF3, AtCOR15a, AtRD29a), it was found that after PfMYB90 gene transfer, Arabidopsis showed strong tolerance to salt and cold stresses. This is consistent with the results mentioned above. This transgenic technology enables Arabidopsis to survive under adverse environmental conditions, allowing it to maintain a relatively stable growth state despite salt accumulation and cold stress. Therefore, PfMYB90 may be a key gene in the regulatory network of salt damage and cold damage, as well as one of the key transcription factors for Paulownia fortunei environmental conditions. Full article

The black garden ant (Lasius niger) is a widely distributed species across Europe, North America, and North Africa, playing a pivotal role in ecological processes within its diverse habitats. However, the microbiome associated with L. niger remains poorly investigated. In the present study, we isolated a novel species, Paenarthrobacter lasiusi, from the soil of the L. niger anthill. The genome of P. lasiusi S21 was sequenced, annotated, and searched for groups of genes of physiological, medical, and biotechnological importance. Subsequently, a series of microbiological, physiological, and biochemical experiments were conducted to characterize P. lasiusi S21 with respect to its sugar metabolism, antibiotic resistance profile, lipidome, and capacity for atmospheric nitrogen fixation, among others. A notable feature of the P. lasiusi S21 genome is the presence of two prophages, which may have horizontally transferred host genes involved in stress responses. P. lasiusi S21 synthesizes a number of lipids, including mono- and digalactosyldiacylglycerol, as well as steroid compounds that are typically found in eukaryotic organisms rather than prokaryotes. P. lasiusi S21 exhibits resistance to penicillins, lincosamides, fusidins, and oxazolidinones, despite the absence of specific genes conferring resistance to these antibiotics. Genomic data and physiological tests indicate that P. lasiusi S21 is nonpathogenic to humans. The genome of P. lasiusi S21 contains multiple operons involved in heavy metal metabolism and organic compound inactivation. Consequently, P. lasiusi represents a novel species with an intriguing evolutionary history, manifesting in distinctive genomic, metabolomic, and physiological characteristics. This species may have potential applications in the bioaugmentation of contaminated soils. Full article

In the last decade, microplastics (MPs) have become a significant environmental pollutant with potential negative effects on aquatic biodiversity and ecosystems. This mesocosm study examined the effect of MPs on the growth and physiology of two common aquatic macrophytes (Myriophyllum spicatum and Phragmites australis), focusing on changes in biomass allocation and nutrient contents. We evaluated oxidative stress responses by measuring superoxide dismutase, malondialdehyde, soluble sugars, free amino acids, and glutamate synthetase activities for M. spicatum, and we assessed photosynthetic processes through metrics including Fv/Fm, electron transfer rate, and Y(II) for P. australis. Unlike most previous studies in plants, we found that the growth and all functional traits of these two plants were not significantly affected by the common MP type (polyethylene) at either low or high concentrations. Additionally, we have examined the impact of another type of MP (polystyrene) on P. australis, and no significant effect was observed. In conjunction with prior case studies, the majority of which demonstrated the toxic impacts of MPs, our research indicates that plants exhibit a species-specific response to MPs. In addition to the strong adaptation of widespread plants used in this study, the large experimental system and relative long-term treatment may also explain our negative results. Our study highlights the need to further investigate species-specific tolerances and adaptive responses to MPs to better understand their ecological impacts. Full article

Bioconvection phenomena play a pivotal role in diverse applications, including the synthesis of biological polymers and advancements in renewable energy technologies. This study develops a comprehensive mathematical model to examine the effects of key parameters, such as the Lewis number (Lb), Peclet number (Pe), volume fraction ($\phi$), and angle of inclination $\left(\alpha \right)$, on the flow and heat transfer characteristics of a nanofluid over an inclined cylinder embedded in a non-Darcy porous medium. The investigated nanofluid comprises nano-encapsulated phase-change materials (NEPCMs) dispersed in water, offering enhanced thermal performance. The governing non-linear partial differential equations are transformed into dimensionless ordinary differential equations using similarity transformations and solved numerically via the Network Simulation Method (NSM) and an implicit Runge–Kutta method implemented through the bvp4c routine in MATLAB R2021a. Validation against the existing literature confirms the accuracy and reliability of the numerical approach, with strong convergence observed. Quantitative analysis reveals that an increase in the Peclet number reduces the shear stress at the cylinder wall by up to 18% while simultaneously enhancing heat transfer by approximately 12%. Similarly, the angle of inclination ($\alpha$) significantly boosts heat transmission rates. Additionally, higher Peclet and Lewis numbers, along with greater nanoparticle volume fractions, amplify the density gradient of microorganisms, intensifying the bioconvection process by nearly 15%. These findings underscore the critical interplay between bioconvection and transport phenomena, providing a framework for optimizing bioconvection-driven heat and mass transfer systems. The insights from this investigation hold substantial implications for industrial processes and renewable energy technologies, paving the way for improved efficiency in applications such as thermal energy storage and advanced cooling systems. Full article

Insulated gate bipolar transistors (IGBTs), as an important power semiconductor device, are susceptible to thermal stress, thermal fatigue, and mechanical stresses under high-voltage, high-current, and high-power conditions. Elevated heat dissipation within the module leads to fluctuating rises in temperature that accelerate its own degradation and failure, ultimately causing damage to the module as a whole and posing a threat to operator safety. Through ANSYS Workbench simulation analysis, it is possible to accurately predict the temperature distribution, equivalent stress, and equivalent strain of solder materials under actual working conditions, thus revealing the changing laws of the heat–mechanical interaction in solder materials. Simulation analysis results show that, under steady-state operating conditions, the highest point of the IGBT module’s overall junction temperature occurs in the center of the chip. Nanogold exhibited the best performance in terms of temperature and equivalent stress-strain among the five solders studied in this paper; defects near the edges caused greater harm to the module compared to those closer to the solder layer’s center. In terms of stress, defects located near the edge corners produced larger strains. Crazing damage in joints allows for a faster transfer of heat sources away from the center; in terms of stress, crazing has fewer detrimental effects on the integrity of the module as compared to through cracks. Simulation analysis can model the interaction of heat and equipment under realistic work conditions, comparing and evaluating different types of solder materials to select the most suitable solder material for product design and material selection. This aids in enhancing design precision and reliability. Full article

The Hindu Kush Himalayan (HKH) region, known as the “water tower of the world,” is experiencing severe water scarcity due to declining discharge of spring water across the HKH region. This decline is driven by climate change, unsustainable human activities, and rising water demand, leading to significant impacts on rural agriculture, urban migration, and socio-economic stability. This expansive review judiciously combines both the researchers’ experiences and a traditional literature review. This review investigates the factors behind reduced spring discharge and advocates for a transdisciplinary approach to address the issue. It stresses integrating scientific knowledge with community-based interventions, recognizing that water management involves not just technical solutions but also human values, behaviors, and political considerations. The paper explores the benefits of public–private partnerships (PPPs) and participatory approaches for large-scale spring rejuvenation. By combining the strengths of both sectors and engaging local communities, sustainable spring water management can be achieved through collaborative and inclusive strategies. It also highlights the need for capacity development and knowledge transfer, including training local hydrogeologists, mapping recharge areas, and implementing sustainable land use practices. In summary, the review offers insights and recommendations for tackling declining spring discharge in the HKH region. By promoting a transdisciplinary, community-centric approach, it aims to support policymakers, researchers, and practitioners in ensuring the sustainable management of water resources and contributing to the United Nations Sustainable Development Goals (SDGs). Full article

The growth and development of plants are closely tied to growth stages, such as germination, flower bud differentiation, photosynthesis, water and fertilizer use efficiency, stress resistance, etc. Previous studies on the stress resistance of plants with different leaf stages have primarily focused on single-factor environmental conditions. However, there has been a lack of systematic research on the physiology of plant seedlings under combined high-temperature and high-humidity (HH) stress, and the relationship between cucumber growth stages and HH tolerance remains unclear. In this study, we analyzed the phenotype, photosynthetic characteristics, reactive oxygen species content, and antioxidant enzyme activity of cucumber seedlings at 1-, 2-, 3-, and 4-leaf stages under control (25 °C + 80%RH, CK) and HH (42 °C + 95%RH) stress, aiming to clarify the relationship between growth stage and cucumber HH tolerance. The results indicated that the HH tolerance of cucumber seedlings increases with leaf stage. Seedlings at 1-leaf and 2-leaf stages were most sensitive to HH, whereas 4-leaf seedlings showed the greatest tolerance. Under HH stress, the biomass, chlorophyll content, net photosynthetic rate, and photosynthetic electron transfer rate were significantly reduced compared to CK. Simultaneously, there was an increase in reactive oxygen species content and antioxidant enzyme activity. The relative values for dry weight, total chlorophyll content, net photosynthetic rate, Fv/Fm, qP, ETR, and Y (II) in 1-leaf and 2-leaf seedlings were significantly lower, while ROS accumulation and changes in antioxidant enzyme activity were significantly higher compared to 4-leaf seedlings. This lays a foundation for future studies on the growth and physiological response of cucumber plants at different growth stages under varying temperature and humidity combined stresses. Full article

This study aimed to investigate the effect of antihypertensive drugs on reproductive function in Rattus norvegicus and demonstrate the potential role of oxidative stress in reproductive dysfunction. Rattus norvegicus were selected as the experimental animals and divided into the following groups: healthy (control group), clonidine (CL), rilmenidine (RLD), methyldopa (MTL), amlodipine (ALD), and ramipril (RML). Each individual in each group was marked from one to six. Doses of clonidine (0.075 mg/kg), rilmenidine (0.5 mg/kg), methyldopa (100 mg/kg), amlodipine (2 mg/kg), and ramipril (2 mg/kg) were administered orally via gavage to each Rattus norvegicus. Using blood obtained from Rattus norvegicus, the absorbance of the pink-colored complex formed by thiobarbituric acid (TBA) and malondialdehyde (MDA) was measured spectrophotometrically at the 532 nm wavelength. Blood samples were collected from the tail veins to analyze serum malondialdehyde (MDA) and total glutathione levels in the serum of all Rattus norvegicus. After sampling, two mature male Rattus norvegicus were introduced to every group of six female Rattus norvegicus and accommodated in a controlled laboratory environment for two months. Any female Rattus norvegicus that became pregnant during this time was transferred to a solitary cage within a controlled setting. Rattus norvegicus that did not become pregnant and did not give birth during this period were considered infertile. The results were compared among the groups. Total glutathione (tGSH) levels were determined using a spectrophotometer. According to our study, the increase in MDA levels observed was not statistically significant in the CL and RLD groups compared to that in the control group. MDA levels were significantly increased in the methyldopa, amlodipine, and RML groups. While total glutathione levels in the CL group were similar to those in the control group, the RLD, MTL, ALD, and RML groups showed a statistically significant decrease. While the animals in the CL and RLD groups were not infertile, infertility was apparent in the groups treated with MTL, ALD, and RML. Thus, it was determined that the antihypertensive drugs MTL, ALD, and RML had different effects on fertility, and that the use of such drugs could cause infertility by increasing oxidative stress and decreasing antioxidant levels. Full article

Water distribution in the structure of vein quartz formed as a result of successive plastic deformations associated with dislocation slip and subsequent recrystallization was estimated using infrared microspectroscopic (μFTIR) mapping. Water contained in quartz demonstrates a broad absorption band in the IR range at 2800–3750 cm⁻¹, which indicates its molecular state and suggests the presence of water bearing water inclusions. In addition to water, the presence of an absorption band located at 2341 cm⁻¹ seems to be due to the presence of carbon dioxide in a molecular state. A necessary step before assessing the distribution of volatile components in the quartz structure was to calibrate the boundaries obtained by calculating the intensity ratios of the peaks at 1118 and 1160 cm⁻¹ in the reflectance spectrum and using electron back scatter diffraction (EBSD). A variety of fluid distributions in different elements of the structure was observed. At medium temperatures and medium strain rates, dislocation mass transfer is effective during dislocation slip. At low strain rates and elevated temperatures, the contribution of diffusion creep gradually increases, which facilitates the interaction of volatile components with migrating boundaries. It was found that in the process of successive rearrangements, migration of fluid components occurs within the main elements of the structure due to the redistribution of dislocations between defects of different scale levels. Redistribution of fluid from fluid inclusions as a result of plastic deformations in the quartz structure is one of the ways of relaxing intracrystalline stresses during strengthening of the structure. Full article

Heavy metal pollution from industrial activities and poor waste disposal poses significant environmental and health threats to humans and animals. This calls for sustainable approaches to the cleanup of heavy metals. This review explores metal tolerance mechanisms of bacteria such as the formation of biofilms, efflux systems, and enzymatic detoxification. These mechanisms allow bacteria communities to adapt and survive in contaminated environments. These adaptations are enhanced by mutations in the bacteria genes and by horizontal gene transfers, enabling bacteria species to survive under environmental stress while simultaneously contributing to nutrient cycling and the decomposition of organic matter. This review further explores the symbiotic interactions between bacteria, plants, and animals. These relationships enhance the metal tolerance ability of the different living organisms involved and are also very important in the bioremediation and phytoremediation of heavy metals. Plant growth-promoting rhizobacteria, Rhizobium, and Bacillus species are very important contributors to phytoremediation; they improve heavy metal uptake, improve the growth of roots, and plants resilience to stress. Moreover, this review highlights the importance of genetically engineered bacteria in closed-loop systems for optimized metal recovery. This offers environmentally friendly and sustainable options to the traditional remediation methods. Engineered Cupriavidus metallidurans CH34 and Pseudomonas putida strain 15420352 overexpressing metallothioneins have shown enhanced metal-binding capabilities, which makes them very effective in the treatment of industrial wastewaters and in biosorption applications. The use of engineered bacteria for the cleanup of heavy metals in closed-loop systems promotes the idea of a circular economy by recycling metals, thus reducing environmental waste. Multidisciplinary research that integrates synthetic biology, microbial ecology, and environmental science is very important for the advancement of metal bioremediation technologies. This review’s analysis on bacterial metal tolerance, symbiosis, and bioengineering strategies offers a pathway to effective bioremediation options, for the reclamation of heavy metal-polluted environments while promoting sustainable environmental practices. Full article