Search Results (919)

It is a challenge in experimental studies today to accurately predict the trapping mechanisms in saline aquifers that influence the long-term CO₂ storage capacities. The inability in current experimental studies to quantify the effects of combined processes of solubility, hysteresis, and mineralization as a means of affecting saline aquifer properties that influence CO₂ trapping mechanisms makes this topic interesting. A systematic framework in CMG-GEM compositional simulation studies is proposed in this article to assess the effects of gradually modelled trapping mechanisms on CO₂ storage performance. Simulation studies are conducted under identical constraints, trapping mechanisms, as well as operational factors in a sequential process that activates (i) solubility, (ii) solubility + hysteresis, and (iii) solubility + hysteresis + mineralization. The findings demonstrate distinct differences in trapping process behaviors as well as simulation stability under various modes: hysteresis effects largely improve immobile reserves as well as decrease plume migration, and, on the other hand, mineralization adds long-term dynamics of capacity increase as well as porosity-permeability alterations, especially in carbonate reservoirs. Through long-term post-injection simulations (up to 1000 years), the findings demonstrate that various trapping processes trigger over distinct time periods—years for immobile reserves, decades for dissolution, and centuries in the case of mineralization. This contribution is able to point out the computational efficiency as well as defective model behavior of concern to various physics levels, providing a practical guide to modelers in making a well-informed decision on what constitutes a minimum set of physics in long-term trustworthy CO₂ storage. Full article

Utilizing saline aquifers for carbon mineralization has proven to be a reliable approach for CO₂ storage. However, less attention has been given to CO₂ mineralization and geomechanical response at engineering durations and spatial scales. The objective of the study is to evaluate the feasibility of a potential CO₂ sequestration site in the Ordos Basin, located at a depth of approximately 1100 m, using the CMG-GEM numerical simulator. A coupled hydraulic–mechanical–chemical model was formulated, accounting for multiphase fluid flow, geochemical reactions, and geomechanical response. The simulation results indicated the following: (1) When CO₂ is injected into a saline formation, it can react with minerals. These chemical reactions may lead to the precipitation of certain minerals (e.g., calcite, kaolinite) and the dissolution of others (e.g., anorthite), potentially affecting the porosity and permeability of the storage formation; however, the study found that the effect on porosity is negligible, with only a 1.2% reduction observed. (2) The extent of ground uplift caused by CO₂ injection is strongly influenced by the injection rate. The maximum vertical ground displacements after 25 years is 6.1 cm at an injection rate of 16,000 kg/day; when the rate is increased to 24,000 kg/day, the maximum displacement rises to 9.4 cm, indicating a 54% increase. Full article

Numerical simulation of the electrical conductivity of carbon fiber-reinforced asphalt concrete is essential for understanding its electrical behavior, yet research in this area remains limited. This study prepared six groups of Marshall specimens with carbon fiber (CF) contents of 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, and 0.6 wt%. The resistivity and asphalt concrete (AC) impedance spectra were measured to analyze the effect of fiber content on electrical performance. Nyquist diagrams were fitted to establish an equivalent circuit model, and a representative volume element (RVE) finite element model was developed. The Generalized Effective Medium (GEM) equation was employed to fit the resistivity data. The results show that the resistivity exhibits a two-stage characteristic—an abrupt decrease followed by stabilization, with an optimal CF content range of 0.2–0.4 wt%. Among the equivalent circuit parameters, the contact resistance (R₁) and tunneling resistance (R₂) significantly decreased, the growth of interface capacitance (C₁) slowed, the constant phase element Z_Q increased, and the non-monotonic change of volume resistance (R₃) reflected the heterogeneity of the internal void distribution of the material. The finite element numerical solution for resistivity, derived from the GEM equation, aligns well with experimental values, validating the proposed simulation approach. Full article

The Sar-e-Sang lapis lazuli deposit has a mining history exceeding 5000 years, producing the world’s finest lapis lazuli. Recently, gem-quality forsterite has been discovered in the marble containing spinel, dolomite, and phlogopite at the periphery of the lapis lazuli ore body at the Pitawak mine, located east of the Sar-e-Sang deposit. The mineral assemblage indicates that the protolith of this marble is dolomite with aluminous and siliceous components. These forsterite crystals occur as colorless, transparent anhedral grains, exhibiting distinct red fluorescence under 365 nm ultraviolet light. To investigate the gemological and spectroscopic characteristics of the Pitawak mine forsterite, this study conducted and analyzed data from basic gemological analysis, electron probe microanalysis (EPMA), Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), ultraviolet–visible absorption spectroscopy (UV-VIS), Fourier-transform infrared spectroscopy (FTIR), laser Raman spectroscopy (RAMAN), and photoluminescence spectroscopy (PL) on four forsterite samples from the Pitawak mine. The analysis results reveal that the samples indicate a composition close to ideal forsterite with a crystal chemical formula of (Mg_2.00Fe_0.02)_Σ2.02Si_0.99O₄. The trace elements present include Fe, Mn, Ca, and minor amounts of Cr and Ni. The UV-VIS spectroscopy results show that the samples possess high transmittance across the visible light range with very weak absorption bands, contributing to the colorless and transparent appearance of Pitawak mine forsterite. This phenomenon is attributed to the extremely low content of chromophoric elements, which have a negligible effect on the forsterite’s color. PL spectroscopy indicates that the red fluorescence of the samples is caused by an emission peak near 642 nm. This emission peak arises from the spin-forbidden ⁴T₁ → ⁶A₁ transition of Mn²⁺ ions situated in octahedral sites within the forsterite structure. Full article

Background: Colorectal cancer (CRC) is a malignancy that ranks among the top three in terms of both global mortality and incidence. Although numerous studies have demonstrated that gut microbes are implicated in CRC pathogenesis, the precise mechanisms underlying host–microbiota metabolic crosstalk remain poorly understood. Objective: This study aims to identify and delineate key co-metabolites and their associated metabolic pathways that modulate the biomass of CRC-related gut bacteria within healthy individuals, through the construction of host–gut microbiota co-metabolic network models. We seek to elucidate the underlying mechanisms of metabolic interplay between the host and CRC-related gut microbiota, thereby offering novel perspectives on the microbial involvement in the initiation and progression of CRC. Methods: We coupled a colon tissue-specific host Genome-Scale Metabolic Model (GEM), which utilized transcriptomic data from healthy human colon tissues, with 12 CRC-associated pro-/anti-carcinogenic gut bacterial GEMs to construct a co-metabolic network. Through a comparative analysis of the network structure and systemic methods (including Flux Sampling and metabolic difference analysis), we simulated scenarios of constrained host co-metabolite supply. Finally, metabolic subsystem enrichment analysis was employed to elucidate the specific molecular mechanisms by which key co-metabolites affect microbial function. Results: The 17 key co-metabolites identified include chloride ions, zinc ions, and acetate. Among these, thirteen metabolites (e.g., ferric iron, succinate, and acetate) were confirmed by literature to be associated with CRC. All 17 key co-metabolites were found to significantly modulate the biomass of CRC-associated gut bacteria. These regulatory effects primarily influence microbial function through core pathways such as glycerophospholipid metabolism and folate metabolism. Conclusion: This research provides a systemic perspective for elucidating the mechanisms of host–gut microbiota metabolic interplay in CRC, thereby complementing the existing theoretical framework concerning microbial regulation by the host genetic background. Full article

Quercetin (Q), a bioactive flavonoid, exerts potent antioxidant and redox-modulating effects by activating the nuclear factor erythroid 2-related factor 2/antioxidant response Element (Nrf2/ARE) pathway and upregulating endogenous antioxidant defenses, including enzymatic antioxidants such as superoxide dismutase (SOD) and catalase (CAT), as well as non-enzymatic glutathione (GSH) and lipid peroxidation (MDA). Gemcitabine (Gem), a widely used antimetabolite chemotherapeutic, often shows limited efficacy under hypoxic and oxidative stress conditions driven by hypoxia-inducible factor 1-alpha (HIF-1α) and vascular endothelial growth factor (VEGF)-mediated angiogenesis. This study investigated the redox-mediated synergistic effects of Q and Gem in MDA-MB-231 human breast cancer cells. Combination treatment significantly reduced cell viability beyond the expected Bliss value, indicating a synergistic interaction and enhanced apoptosis compared with single-agent treatments. Increased reactive oxygen species (ROS) production was accompanied by depletion of GSH and accumulation of MDA, establishing a pro-apoptotic oxidative stress environment. Q alone enhanced SOD and CAT activities, whereas the combination induced exhaustion of antioxidant defenses under oxidative load, reflecting a redox-adaptive response. Molecular analyses revealed downregulation of HIF-1α and VEGF, alongside upregulation of Bax and Caspase-3, confirming suppression of hypoxia-driven survival and activation of the intrinsic apoptotic pathway. Transcriptomic and enrichment analyses further identified modulation of oxidative stress- and apoptosis-related pathways, including phosphoinositide-3-kinase–protein kinase B/Akt (PI3K/Akt), HIF-1 and VEGF signaling. Collectively, these results indicate that Q potentiates Gem cytotoxicity via redox modulation, promoting controlled ROS elevation and apoptosis while suppressing hypoxia-induced survival mechanisms, highlighting the therapeutic potential of redox-based combination strategies against chemoresistant breast cancer. Full article

Background/Objectives: Lactate, traditionally considered a byproduct of anaerobic metabolism, is increasingly recognized as a biomarker of tissue perfusion and systemic stress. While hyperlactatemia is frequent after pediatric cardiac surgery, evidence regarding its prognostic role remains controversial. This study aimed to evaluate whether serial lactate measurements predict mortality in children undergoing surgery for congenital heart disease in Southeast Mexico. Methods: We conducted a retrospective cohort study including children aged 0–210 weeks with confirmed congenital heart disease who underwent first-time cardiac surgery between January 2022 and December 2024. Serum lactate was measured intraoperatively, at intensive care unit (ICU) admission, and at 12 and 24 h postoperatively using a Gem^® Premier™ 3500 analyzer. Sociodemographic, clinical, and surgical data were recorded. Associations between lactate levels and mortality were analyzed with Cox regression, adjusting for RACHS-2 category and intraoperative complications. Predictive performance was assessed with ROC curves and Harrell’s C-index. Results: 103 patients were included (median age 49.2 weeks; 60% female). Lactate levels overlapped intraoperatively but significantly discriminated against survivors from non-survivors thereafter. ICU admission lactate ≥ 4.2 mmol/L predicted mortality with 100% sensitivity and 60% specificity (AUC = 0.84). Hazard ratios confirmed that lactate at ICU admission (HR 2.17, 95% CI 1.16–4.06; p = 0.015), 12 h (HR 6.37, 95% CI 1.02–39.6; p = 0.047), and 24 h (HR 1.81, 95% CI 1.07–3.09; p = 0.028) were significant predictors of mortality. The model showed excellent discrimination (Harrell’s C = 0.986), though optimism due to the limited number of deaths should be considered. Conclusions: Serial lactate monitoring, particularly upon ICU admission, provides strong prognostic information for in-hospital mortality in pediatric cardiac surgery patients. Incorporating early postoperative lactate into routine monitoring may allow timely therapeutic adjustments. Preoperative lactate assessment warrants further evaluation as a potential risk stratification tool. Full article

Grounding Systems (GS) play a critical role in electrical safety, lightning protection, and the reliable operation of power and renewable energy infrastructures, particularly in high-resistivity soils. In this context, Ground Enhancement Materials (GEM) are widely used to reduce soil resistivity and improve grounding performance. This systematic review analyzes and synthesizes recent advances (2018–2025) in GEM applied to GS, with emphasis on their electrical performance, durability, and environmental sustainability. The review covers conventional GEM, industrial waste-derived materials, and hybrid formulations, evaluating their effectiveness under different soil types and moisture conditions. Comparative analysis of the literature indicates that GEM derived from industrial byproducts and hybrid composites often exhibit superior long-term resistivity reduction due to enhanced moisture retention and material-soil interactions, especially in clay-rich and heterogeneous soils. Sustainability considerations such as environmental impact, material availability, and long-term stability are increasingly influencing GEM selection and design. Overall, this review provides a structured framework for understanding the factors governing GEM performance while highlighting current trends, challenges, and future research directions in the development of sustainable grounding solutions. Full article

This study examines the relationship between Wasta—a social network based on family, lineage, tribe, and extended family ties—as practiced by senior HRM employees, and its effects on entrepreneurial creativity, innovation, and sustainable development in the MENA region. The study also explores why entrepreneurs and countries in the MENA region are not ranked among the top 100 innovators in the Global Innovation Index. Additionally, it addresses why Wasta, as practiced by HRM employees, can impede sustainable development. The author drew on Amabile’s Componential Theory of Organizational Creativity and Model of Creativity and Innovation in Organizations. Evidence was gathered from articles on Wasta, secondary data from the Global Innovation Index (GII) for 2023, and the Global Entrepreneurship Monitor (GEM NECI) in 2024. Secondary datasets were analyzed using constant comparative analysis of documents. These datasets included accessible online indices, the Global Innovation Index in 2023, the World’s Most Innovative Companies Index by Forbes, and the Top 100 Global Innovators 2024 Rankings by Clarivate. The study develops a theoretical framework for the link between Wasta and sustainable development. It concludes that Wasta, when practiced by senior HRM employees, is likely a reason why MENA entrepreneurs fall short in achieving sustainable development and why the region’s countries are not among the top 100 innovative countries globally. The study answers why Wasta hinders sustainable development among MENA entrepreneurs. This study recommends that entrepreneurs recognize the importance of fair HRM practices in hiring, supervisor selection, candidate selection, and promotions to foster innovation and sustainable development. The conclusions may also encourage policymakers to create and enforce new rules to reduce Wasta if they aim to stimulate innovation, sustainable development, and economic advantage in the MENA region. Full article

Background/Objectives: Discriminating bacterial from mammalian membranes remains a central challenge in antibiotic design. Bacterial membranes are enriched in phosphatidylethanolamine (PE), a lipid normally absent from the outer leaflet of mammalian cells, providing a signature for selective molecular engagement. We report a compact covalent ligand, 6-dimethylamino-4-ketohexanoic acid (DMAX), which targets PE via Schiff base formation, leveraging its tertiary amine to facilitate the reaction and strengthen ionic binding with the phosphate group. Methods: The reactivity of DMAX and PE was evaluated by computational simulations, and their interaction was examined by spectroscopic analyses (NMR and FT-IR) and an artificial membrane assay. The targeting ability of DMAX for live bacteria was determined by microscopy study, and its applicability to therapeutic system was tested in vitro under washed conditions that mimic rapid in vivo clearance. Results: Spectrometric analyses revealed the selective covalent interaction of DMAX and PE, consistent with the simulated results. Fluorescently labeled DMAX selectively binds PE-enriched model membranes and efficiently recognizes Gram-negative bacteria while sparing mammalian cells. Conjugation of DMAX to Gemifloxacin (Gem) significantly enhanced antibiotic efficacy by 10-fold compared with free Gem, even after rapid drug clearance, while maintaining safety in mammalian cells. Conclusions: These results identify DMAX as an efficient and versatile PE-targeting platform, enabling selective membrane anchoring to advance precision antibiotic strategies. Full article

Institutional quality and globalization are crucial in influencing both the prevalence and quality of sustainable entrepreneurial ecosystems within an economy. This study examines the relationship between Opportunity-Driven Entrepreneurship (ODE); entrepreneurial quality, as measured by the Motivational Index (MI), and institutional quality, assessed through economic freedom and governance, in high- and middle-income countries. It also examines how globalization impacts both ODE and MI in these country groups. Using data from the Global Entrepreneurship Monitor (GEM) and combined indices of economic freedom, governance, and globalization, the study analyzes an unbalanced panel dataset comprising 64 countries from 2004 to 2018. Estimation is performed using the Robust Least Squares (RLS) method. The findings show that economic freedom has a positive and significant effect on both ODE and MI across high- and middle-income countries. In contrast, governance has a significant impact on ODE and MI only in high-income countries. Globalization exerts a negative influence on ODE across both income groups, with the adverse effect being more pronounced in middle-income countries. Conversely, its effect on MI is positive in middle-income countries but shows no significant influence in high-income economies. The study offers valuable insights for economists, policymakers, and scholars interested in the forces that shape ODE. Full article

This article provides a comparative examination of two AI-assisted museums in Africa, the Dar Gnawa Museum (Marrakech) and the Grand Egyptian Museum (Cairo). It analyzes the AI functions and the strategies these institutions adopt to pursue techno-cultural empowerment in a field long shaped by power asymmetries in Africa. The literature review highlights how technological transfers in museum cooperation remain an overlooked vector of coloniality which the convergence of AI and heritage practices now brings sharply into view. This article develops the notion of clouded coloniality—a dual phenomenon in which heritage data is literally managed in the cloud, often from abroad, while diffracted layers of actors and processes obscure the identification of new imbalances in and around AI-assisted museums. This article designs a two-pronged analytical framework which first assesses AI functions within the Dar Gnawa Museum and the GEM, and then evaluates sustainable synergies between these institutions and their broader AI ecosystem. The results indicate that whereas the GEM prioritizes youth empowerment, the tourism industry, and partnerships with foreign stakeholders that could potentially expose Egypt’s cultural sovereignty, the Dar Gnawa Museum independently developed an AI tool, Kouyou, that could offer a transferable model for advancing Pan-African techno-cultural empowerment. Full article

As artificial intelligence (AI) becomes embedded in entrepreneurial practice, an unresolved question is whether age shapes founders’ perceptions of its opportunities and risks. Drawing on diffusion-of-innovations and technology adoption theories, this study examines whether age cohorts differ in their perceived benefits of AI, perceived risks, and short-term expectations regarding AI’s business impact. Using data from the 2024 Global Entrepreneurship Monitor (GEM) survey for Slovenia, we analyze ordinal indicators across all three domains. Bivariate comparisons using Mann–Whitney U tests with effect sizes are complemented by multivariate ordinal logistic regression models controlling for sector, education, and gender. The analysis reveals an asymmetrical age gap in AI perceptions. Younger entrepreneurs report higher perceived benefits and more positive impact expectations, while AI-related risk perceptions do not vary by age. Multivariate analyses show that age effects on perceived benefits are context-dependent, whereas age remains a robust predictor of future-oriented impact expectations. The study offers a theoretically grounded and methodologically transparent analysis integrating technology adoption frameworks with entrepreneurial psychology. Practically, it underscores the need for differentiated AI-readiness initiatives that address age-related differences in strategic orientation and preparedness. Future research could further explore the roles of capabilities, industry context, and entrepreneurial experience. Full article

The use of recycled aggregate provides clear environmental advantages but may introduce chemical interactions that influence cement hydration, particularly when the material originates from mining by-products containing heavy metals. This study examines cementitious composites containing different volume fractions of recycled aggregate derived from Pb–Zn mine tailings and identifies the mechanisms responsible for the observed early-age hydration delay. The recycled aggregate was characterized using XRD, hydration was monitored through ultrasonic pulse velocity (UPV) and temperature evolution, mechanical performance was assessed at 1, 3, and 7 days, and phase evolution was interpreted using SEM-EDS and thermodynamic equilibrium modeling (GEMS/Cemdata18). The results show that heavy-metal-bearing phases (Zn-, Pb-, and Fe-sulfides/sulfates) promote the formation of metastable metal–silicate complexes, temporarily lowering the oxidation potential and delaying setting by up to 28 h in mixtures containing 100% recycled aggregate. Early-age strength was substantially reduced; however, by day 7, all mixtures except that with 100% recycled aggregate approached the strength of the reference mixtures with natural aggregate. Despite these effects, recycled aggregate can be safely incorporated at replacement levels up to 25 vol.%, which preserves acceptable fresh and hardened properties. Nevertheless, the presence of persistent sulfate-bearing phases (e.g., epsomite, anglesite) indicates a potential for long-term sulfate release and associated durability risks, warranting further investigation. Full article

Landfill disposal continues to be the most economically viable municipal solid waste (MSW) management practice in many countries, including Mexico. Landfills are the third-largest source of methane emissions from human activity, a fact that has significant implications for the environment and human health. Due to the difficulty in experimentally quantifying methane emissions, mathematical models have been employed to predict gas emissions. In this work, three first-order decay models were implemented to estimate methane emissions in a landfill located in the metropolitan area of Oaxaca City, Mexico. Each model incorporated a Van’t Hoff–Arrhenius-type approach for calculating the reaction rate constant. Additionally, an uncertainty analysis of the models was presented, applying Monte Carlo simulations with triangular and log-normal distributions. The results show that the simple model exhibited the best predictive performance. For 2020, the simple model estimated 3,488,392.1 m³ of methane at a temperature of 46 °C, 3,509,625.1 m³ of methane at 47 °C, and 3,530,850.2 m³ of methane at 48 °C. The Monte Carlo simulation with a log-normal distribution exhibited more robust and natural process behavior. For the simple model, the mean was 3,486,946.03, the median was 3,487,154.73, and the standard deviation was 212,095.95. The LandGEM model exhibited more linear methane generation behavior, and the uncertainty analysis confirmed that this model had the lowest predictive capability of the three proposed models. Full article