The macroscopic mechanical properties of granular systems largely depend on the complex mechanical responses of force chains at the mesoscopic level. This study offers an alternative to rapidly identify and predict force chain distributions under different stress states. 100 sets of gradation curves that effectively represent four typical continuous gradation distributions are constructed. Numerical specimens corresponding to these gradation curves are generated using the discrete element method (DEM), and a dataset for deep neural network training is established via biaxial compression numerical simulations. The relationship between particle distribution characteristics and force chain structure is captured by the Pix2Pix conditional generative adversarial network (cGAN). The effectiveness of the generated force chain images in reproducing both particle gradation and spatial distribution characteristics is verified through the extraction and analysis of pixel probability distributions across different color channels, along with the computation of texture feature metrics. In addition, a GoogLeNet-based prediction model is constructed to demonstrate the accuracy with which the generated force chain images characterize the macroscopic mechanical properties of granular assemblies. The results indicate that the Pix2Pix network effectively predicts and identifies force chain distributions at peak stress for different gradation
Application of organic mulches has repeatedly been shown to reduce infestation with Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), the Colorado potato beetle (CPB). In order to determine if the nutritional status of potatoes as affected by mulch could explain the mulch effects in potatoes against CPB, we determined potato leaf nutrient composition in unmulched control plots and plots mulched with grass-clover or triticale-vetch and assessed mulch effects on CPB damage and development in the field during 3 years and under controlled conditions. In mulched plots, foliar Mo, Cl, and K contents were consistently higher than those without mulch, and leaf damage by CPB was reduced significantly. In addition, increased B contents were associated with undamaged plant material, while higher Zn contents were associated with leaves damaged by CPB. Under controlled conditions, CPB fitness was not affected by mulch application. Overall, reduced CPB damage could not be clearly attributed to altered foliar nutrient contents due to mulching. It is thus more likely that CPB reductions in mulched systems are due to mechanisms other than an altered nutrient balance.
Jadomycin B, produced by the soil bacterium Streptomyces venezuelae ISP5230, induces cytotoxicity in human breast cancer cells in vitro and has antitumoral effects in animal models. In models of multidrugresistant, triple-negative breast cancer, jadomycin B has shown promise as it is not a substrate of ABCB1 and ABCG2 drug efflux transporters. The generation of reactive oxygen species and inhibition of topoisomerases are potential mechanisms of jadomycin B-mediated DNA damage and apoptosis. However, the mechanisms of jadomycin B's anticancer activity have not been fully elucidated. By gradually exposing MDA-MB-231 triple-negative human breast cancer cells to jadomycin B, we hypothesized that resistance could be selected to further understand jadomycin B's pharmacological mechanisms. A 3-fold increase in the jadomycin B IC50 was observed in MDA-MB-231 cells exposed to increasing jadomycin B concentrations (0-3 mu M) over 7 months, herein 231-JB cells. The 231-JB cells were cross-resistant to jadomycin F and S but not to the comparator drugs mitoxantrone, doxorubicin, and SN-38. The 231-JB cells did not have increased mRNA expression of topoisomerase-2 nor ABCB1 and ABCG2. Cyclooxygenase-2 (COX-2) increased by 25-fold, but expression of prostaglandin E2 receptor 4 did not significantly change. Cotreatment with celecoxib (15-45 mu M), a COX-2 inhibitor, resensitized the 231-JB cells to jadomycin B (IC50 1/4 1.41 +/- 0.24 to 0.75 +/- 0.31 mu M vs 2.28 +/- 0.54 with 0 mu M celecoxib). To our knowledge, this work represents the first report of the involvement of COX-2 in jadomycin B activity in vitro, proving to be an exciting new target for the exploration of jadomycin B anticancer activity. Significance Statement: Cyclooxygenase-2 (COX-2), the rate-limiting enzyme in prostaglandin production, is associated with procancer signaling. COX-2, ABCB1, and ABCG2 overexpression are typically correlated in cancer, contributing to chemotherapy resistance. We observed increased COX-2, but not ABCG2 or
In the loess-filling project, the original structural loess under the filling will produce creep deformation under the isometric consolidation stress state, affecting the upper building's safe construction and later operation. Therefore, studying the creep deformation characteristics of structural loess under different consolidation coefficients is significant. In this paper, the following results are obtained by combining test and theoretical analysis. In view of the structural loess under the filling, the triaxial creep test of undisturbed loess under different isometric consolidation coefficients, confining pressures and shear stress levels was completed, and the creep deformation law of structural loess was obtained. The creep characteristics of undisturbed loess are found to be diversified under different coefficients, confining pressures, and shear stresses, including initial instantaneous deformation, subsequent creep attenuation deformation, and final stable creep deformation. The damage creep constitutive model of undisturbed loess is established, taking the binary medium model as the framework, the cementation element adopts the Nishihara model, the friction element introduces the overstress model and considers the isometric consolidation effect, and the damage creep constitutive model of undisturbed loess is established. The theoretical model is obtained by determining the relevant parameters of the constitutive model. The theoretical curve is compared with the experimental curve and shows that the damage creep model established in this paper can better reflect the creep of structural loess under isometric consolidation conditions well. The research results can provide systematic theoretical support and an experimental basis for the deformation problems involved in the filling project in the loess area.
Dinotefuran, a third-generation neonicotinoid insecticide, is widely used in agriculture production due to its excellent insecticidal efficacy. Considering its persistence and high toxicity in soil, it is essential to evaluate its low-dose toxic effects on non-target soil organisms such as the springtail (Folsomia candida). The results revealed that the 7-day half lethal concentration (7d-LC50) of dinotefuran contact toxicity to springtails was 0.029 mu g cm(-2). Its chronic toxicity in 4 soil types was ranked as: red soil (0.021 mg kg(-1)) > fluvo-aquic soil (0.040 mg kg(-1)) > artificial soil (0.049 mg kg(-1)) > black soil (0.085 mg kg(-1)). Soil organic matter (SOC), pH, and total nitrogen (TN) were identified as critical factors affecting dinotefuran toxicity. Biochemical assay results showed that environmental concentrations (0.2-1.6 mg kg(-1)) of dinotefuran induced oxidative stress and oxidative damage in springtails. Oxidative stress-related enzymes (including superoxide dismutase (SOD) and catalase (CAT)) and detoxification enzymes were subjected to initial activation at low dinotefuran concentrations, inhibition and re-activation at high concentration. Target enzyme acetylcholinesterase (AChE), malondialdehyde (MDA) content, and total protein content were inhibited with prolonged exposure time and increasing concentrations of dinotefuran. Molecular docking analysis showed that dinotefuran bound to the active sites of related enzymes, thus disrupting their structure and functions, eventually resulting in damages to physiological functions of springtails. In summary, this study deciphers the dinotefuran toxicological mechanism on soil springtails at environmental concentrations. Our findings lay theoretical basis for further assessing its pollution risk and managing its application.
The application of uranium (U) in the nuclear energy and defense industry has driven U mining activities, leading to subsequent U contamination. Understanding the toxicity and detoxification mechanism of U in plants is crucial for enhancing the efficiency of phytoremediation efforts in U-contaminated soils. The present study investigated the toxicity of uranium (U) in radish and its impact on physiological and molecular responses. The application of U (5-25 mu M) for 3 days significantly inhibited the elongation of radish lateral roots, and the lateral root length decreased by 35.6%-60.7% compared with the control. Under U stress, radish root tip meristem cells suffered DNA damage, fortunately the cells remained viable. To repair damaged DNA, the expression of genes involved in DNA repair (e.g. RAD2, XPC, BLM) was up-regulated, and the expression of genes involved in cell cycle was down-regulated (e.g. CYCB, CDKB). Under U stress, the expression of respiratory burst oxidase homologs (RBOHs) genes in radish roots up-regulated, which caused ROS burst, and then enhanced autophagy by promoting the expression of autophagy related genes (ATGs). Simultaneously, the glutathione (GSH) content increased, and the gene expression levels and activities of antioxidant enzymes (e.g. catalase) were increased, which enhanced the antioxidant capacity of root cells. Moreover, ubiquitin-proteasome system (UPS) (e.g. E3 ligase genes NEDD4) was involved in the activation of DNA repair, GSH synthesis and autophagy. In summary, DNA repair, autophagy, and antioxidant systems were activated in radish roots, which promoted the survival of apical meristem cells under U stress.
The research focused on enhancing the preservation and flowability of palm date powder using isomalt-incorporated polyvinyl alcohol (PVAC/ISO) films for food storage applications. Various concentrations of isomalt (ISO) were integrated into PVAC films, and their properties were thoroughly analyzed. The incorporation of ISO led to significant changes in the films' characteristics, including increased thickness (from 0.09 mm for pure PVAC to 0.31 mm for PVAC/ISO3) and moisture content (from 10.15% in PVAC to 16.36% in PVAC/ISO3). Mechanical properties also improved, with tensile strength reaching 84.95 MPa and elongation at break increasing to 79.38% for PVAC/ISO2. Additionally, antioxidant properties were enhanced, as evidenced by the total phenolic content of 128.09 mu g/g, DPPH radical scavenging activity of 21.55%, and ABTS radical scavenging activity of 38.21% for PVAC/ISO3. The films showed a significant reduction in water vapor permeability (2.756 x 10-10 g. m-1 s-1 pa-1 for PVAC/ISO3) and increased solubility in water (32.68% for PVAC/ISO3). Furthermore, the biodegradability of the films in moist soil conditions improved with the addition of ISO. The storage tests with palm date powder demonstrated that PVAC/ISO films effectively maintained the powder's flowability and prevented moisture-induced caking, confirming their potential as an effective food packaging material for powdered food products. This study highlights the benefits of using PVAC/ISO films in extending the shelf life and preserving the quality of palm date powder while also offering a sustainable solution for the packaging industry. However, further studies are needed to explore the long-term stability and applicability to other hygroscopic food products.
As the demand for fish increases, the amount of wastewater generated from fishponds is also increasing with potential environmental and public health effects from their indiscriminate disposal. This study aimed at comparative analyses of the physicochemical and heavy metal constituents and potential DNA damage by wastewaters from natural and artificial fishponds using Allium cepa assay. A. cepa were grown on 3.13, 6.25, 12.5, 25.0, and 50.0% (v/v; wastewater/tap water) concentrations of each wastewater. At 48 and 72 h, respectively, genotoxic and root growth inhibition analyses were carried out on the exposed onions. The onion root tips exposed to wastewaters showed a significant (P < 0.05) inhibition of root growth and cell division in a concentration-dependent manner. Additionally, chromosomal abnormalities like spindle disturbances, sticky chromosomes, micronucleus, bridges, and binucleated cells were observed in the exposed onions and their induction was higher significantly relative to the negative control. Generally, wastewater from the natural fishpond caused higher chromosomal aberrations than the wastewater from artificial fishpond. It is our belief that the cytotoxicity and genotoxicity observed in the onions were primarily caused by heavy metals like Cr, Cd, Fe, Pb, Cu, and Zn found in the wastewaters. These metals also showed a significant carcinogenic and non-carcinogenic risks in children and adults with Cd as the highest contributor to these detrimental risks. Ingestion route was the major exposure route to the toxic metals in these wastewaters. Wastewater from the natural fishpond showed a higher health risk than the wastewater from the artificial fishpond. These findings suggest that the wastewaters from natural and artificial fishpond contain compounds that might induce cytogenotoxicity in exposed organisms.
Postfire management actions are used to mitigate damage caused by wildfires. Salvage logging, often employed to restore ecosystem functions in burnt stands, plays an essential role in reducing economic losses and the burn severity of future wildfires. However, its ecological implications for soil functionality still need to be understood, especially in the Mediterranean basin, which is prone to erosion and desertification. This study aimed to investigate the effects of fire on (i) soil organic matter (SOM) quality and composition using differential scanning calorimetry-thermogravimetry (DSC-TG) and solid-state nuclear magnetic resonance (C-13 CPMAS NMR) and (ii) phosphorus (P) forms using solid-state( 31) P NMR spectroscopy in a wildfire that affected 3200 ha in southeastern Spain in July 2017. One year after the fire, we monitored four Pinus halepensis Mill. stand categories based on soil burn severity (SBS): unburnt, low SBS, high SBS and high SBS areas with salvage logging (n=36, nine plots per SBS level). We collected soil samples and analysed soil pH, SOM content and SOM quality, along with biological activity indicators (carbon biomass, basal respiration, beta-glucosidase, phosphatase activities) and P forms. We ran ANOVA statistical tests to identify significant differences in soil properties among SBS levels. We also established general linear regressions of thermo-recalcitrance values and aromaticity with biological soil quality indices to compare both techniques for detecting changes in SOM quality and composition. The results indicated that fire increased soil pH (up to 0.3), particularly in the plots with higher SBS levels. SOM decreased significantly with increasing SBS level (down to < 5 % at the high SBS level), with a shift from labile compounds (carbohydrates) to more recalcitrant ones (aromatics). Organic P forms were depleted, while orthophosphate levels rose, increasing the risk of irreversible fixation. This study also highlights that DSC-TG is a cost-effective technique for assessing SOM quality changes. Understanding these effects is essential for developing policies to conserve and restore fire- affected areas and to promote practices that enhance soil functionality and resilience.
Space rockets are regularly launched from the Baikonur Cosmodrome in Kazakhstan. The ecological impact of territories affected by the consequences of space rocket activities on the environment is a significant concern. On July 27, 2006, the Dnepr rocket was launched from the Baikonur Cosmodrome, resulting in an abnormal situation and its emergency fall. The rocket fuel components, heptyl, and amyl, led to decontamination and reclamation activities. However, the self-restoration of soil and vegetation cover is currently in the earliest stages. Consequently, an assessment of the remote consequences of the accidental fall of the Dnepr launch vehicle for environmental objects was conducted. The study involved eco-toxicological characterization of habitat conditions, assessment of species diversity, determination of key morphophenetic indicators, and the genetic status of indicator species as the main parameters. The results revealed an increased level of genotoxicity in soils at the accident site. While there were deviations from the norm in some morphophenetic and cytogenetic parameters in indicator animals, they were not critical for their existence in this territory. Possibly, at the physiological level, they exhibit a high enough adaptation potential and compensatory mechanism.