Search Results (3,124)

The molecular mechanisms governing the efficient packaging of the large SARS-CoV-2 RNA genome into progeny virions remain incompletely understood, with the role of untranslated regions (UTRs) being particularly enigmatic. Leveraging proximity ligation sequencing data, we identified direct, high-frequency interactions between the viral packaging signal PS9 and both the 5′ and 3′ UTRs during intracellular replication stages. Functional validation using an infectious virus-like particle (iVLP) system demonstrated that genomes incorporating SARS-CoV-2 UTRs exhibited significantly enhanced packaging efficiency, yielding an increase in both packaged RNA copies and reporter gene expression post-infection. Competitive packaging assays confirmed the UTRs confer a selective advantage during particle assembly. Mechanistically, Western blot and digital Western analysis revealed that UTR-containing iVLPs incorporated approximately 2-fold more nucleocapsid (N) proteins, suggesting enhanced N recruitment or retention. The deletion of specific core sequences within the UTRs predicted to form a base pair with PS9 abrogated this enhancement, suggesting the functional significance of the UTR-PS9 interaction interface. Collectively, these results establish that the 5′ and 3′ UTRs act synergistically through direct RNA-RNA interactions with PS9 to promote N protein recruitment and enhance packaging efficiency in a PS9-dependent iVLPs system. This UTR-PS9 regulatory axis presents a novel target for therapeutic intervention against SARS-CoV-2 and related coronaviruses. Full article

Water scarcity in semi-arid regions threatens seed germination and early crop establishment, driving the development of biodegradable Nature-based Solutions to replace synthetic plastic mulches. Porous cellulose membranes were fabricated from rice husk (RH), banana pseudostem (BP), and sugarcane bagasse (SB) by thermo-chemical extraction and high-shear homogenization (n = 5 replicates per membrane type). Membranes were characterized by ATR-FTIR and scanning electron microscopy, confirming removal of non-cellulosic components and biogenic silica preservation in RH, and revealing biomass-dependent porous architectures linked to mechanical and transport behavior. RH produced the most compact fibrillar matrix (compressive strength: 8.16 ± 0.24 MPa; WVT: 170 ± 60 g m⁻² day⁻¹), BP an open interconnected network with superior deformability (9.83 ± 0.25% elongation) and moisture transport (WVT: 400 ± 100 g m⁻² day⁻¹), and SB the highest moisture-retention capacity (215.7 ± 15.8%). Germination assays with Brassica oleracea var. botrytis under water stress showed SB achieved the highest germination rate (90.5 ± 0.99%), confirming that sustained moisture availability governs germination more decisively than transport rate alone. Soil burial tests confirmed biodegradable behavior across all membranes (R² ≥ 0.995; k = 0.043–0.046 day⁻¹). These findings establish a hydrogen-bond-mediated structure–property–function framework for designing biomass-specific cellulose membranes as biodegradable solutions for water-limited agricultural systems. Full article

Green roofs are used as nature-based solutions for urban stormwater management and for improving the thermal performance of buildings. Their hydrological performance depends on structural properties and rainfall characteristics, but the relative importance of these factors has not been fully quantified. Therefore, this study aimed to identify the key variables controlling the hydrological effectiveness of a green roof. A conceptual model of a flat roof representing a typical single-family building in south-eastern Poland was developed in the Storm Water Management Model (SWMM), with a modeled roof area of 232 m² and 100% of the roof surface covered by the green roof LID system. A total of 24,576 simulation cases were analyzed, considering different values of soil thickness, berm height, initial saturation, vegetation-related storage, rainfall duration, rainfall probability, and rainfall temporal distribution. The hydrological response was evaluated using peak runoff reduction and cumulative runoff volume ratio determined at selected times after rainfall. Predictive models based on the eXtreme Gradient Boosting (XGBoost) algorithm were developed, and their interpretation was performed using the SHapley Additive exPlanations (SHAP) method. The main novelty of the study is its application-oriented framework combining SWMM simulations, XGBoost modeling, and SHAP explainability to distinguish the factors controlling peak runoff reduction and delayed runoff release from a green roof. The results showed that peak runoff reduction ranged from 10.97% to 100.00%, with a median of 99.91%, indicating a generally high capacity of the analyzed system to attenuate peak flow. In contrast, the cumulative runoff volume ratio increased over time, with median values rising from 0.05% immediately after rainfall to 7.91% after 24 h, confirming the significant retention and detention potential of the green roof. SHAP analysis revealed that peak runoff reduction was governed primarily by berm height, whereas cumulative runoff volume was controlled mainly by initial substrate saturation. The results confirm that different mechanisms control short-term and long-term green roof performance. Full article

High-resolution CTD profiles, with SVP cross-validation of the sound speed field, were recorded at a single station in the outer roadstead of the Port of Constanța (northwest Black Sea; 44°07′41″ N, 28°53′15″ E; depth ≈ 25 m; June 2024), revealing a strongly stratified, five-layer water column driven by three combined forcing mechanisms: seasonal thermal stratification with an abnormally shallow Cold Intermediate Water layer (7.3–15.6 m), Danube-sourced freshwater input, and anthropogenic disturbances consistent with port and anchorage activity. A contextual hypothesis is proposed that conflict-related marine traffic intensification may contribute to observed signals, but physical measurements cannot establish causation. At the main pycnocline (7.31–15.62 m), a density difference of Δρ = 4.02 kg m⁻³ yields a maximum Brunt–Väisälä frequency of N² = 2.37 × 10⁻³ s⁻², reducing vertical eddy diffusivity by two orders of magnitude (Kz ≈ 10⁻⁶ m² s⁻¹). Physical conditions—a shallow mixed layer (~0.7–1.2 m) and strong pycnocline—support the theoretical expectation of surface-layer contaminant accumulation; however, no chemical measurements were carried out to confirm contaminant presence. All contamination inferences rely exclusively on physical proxies (turbidity, dissolved oxygen, and density gradients), and contaminant retention remains untested for lack of direct chemical evidence. A dimensional Stratification-Controlled Retention Index (SCRI = N²/Kz; units: m⁻² s⁻¹) is introduced, and its consistency with the observed hydrographic structure is demonstrated. Full article

University orientation programmes are a primary mechanism through which new students become familiar with campus facilities, academic spaces, and institutional procedures. However, many orientation activities are delivered as single in-person sessions, limiting opportunities for students to revisit spatial and procedural information after the event. To help address this constraint, a digital twin-inspired metaverse orientation application, the Digital Twin Metaverse Orientation (DTMO), was designed in Unity and hosted on Spatial.io as a spatially faithful virtual replica of a faculty environment. An exploratory pilot evaluation was conducted with 30 university students from multiple faculties after a facilitator-guided orientation session. The System Usability Scale (SUS), Net Promoter Score (NPS), and two open-ended questions were used to examine perceived usability, recommendation intention, and the reasons underpinning recommendation decisions. The application obtained a mean SUS score of 86.83, corresponding to an excellent perceived-usability rating, and an NPS of 53.33, indicating positive immediate recommendation intention. Qualitative responses suggested that participants valued the DTMO for engagement, accessibility, ease of navigation, and support for spatial familiarisation, while some participants emphasised that it should complement rather than replace physical orientation. These pilot findings indicate promising user reception in a small, guided-session sample, but they do not establish orientation effectiveness, learning transfer, wayfinding performance, retention, belonging, institutional integration, or sustained use. Further research with broader samples and outcome-based measures is therefore needed. Full article

The transient heat-transfer behavior of hybrid natural-fiber-reinforced epoxy composites containing 0–5 wt% conch shell filler and 20–35 wt% combined banana–bagasse fiber reinforcement was evaluated using active infrared thermography. A standardized protocol comprising 30 s of convective heating with 100 °C hot air followed by 60 s of natural cooling was applied to seven composite configurations tested in triplicate. The transient response was analyzed in three phases: active heating (0–30 s), thermal lag (30–57 s), and natural cooling (57–90 s). Maximum temperature ($T_{max}$), heating rate ($R_h$), cooling rate ($R_c$), and a thermal retention ratio ($TR$) were extracted and statistically validated by one-way ANOVA with Bonferroni correction. For specimens exhibiting zero within-group variance at the camera display resolution, significance was confirmed using exact permutation tests. Filler incorporation (3–5 wt%) was the dominant factor governing peak-temperature reduction; F5B15S10 (5 wt% filler, 25 wt% total fiber) achieved the lowest $T_{max}$ (33.80 °C, 4.57 °C below neat epoxy). Cooling efficiency was primarily governed by fiber content; F3B15S20 (3 wt% filler, 35 wt% total fiber) demonstrated the most efficient heat dissipation ($TR=0.721$). These findings demonstrate that heating resistance and cooling efficiency are governed by partially independent mechanisms, enabling tailored material design. This study indicates that the proposed transient thermographic protocol provides a valuable reference to thermal management design of hybrid biocomposites in automotive interior and building envelope applications. Full article

Small and medium-sized enterprises (SMEs) are particularly vulnerable when crisis support systems are delayed, unreliable, or difficult to access. This study examines how South African SMEs maintained strategic continuity during COVID-19 by developing the concept of relational substitution, defined as a process in which owner-managers compensate for weak formal support by internalizing continuity work within the employment relationship. The study is based on a secondary qualitative analysis of 16 semi-structured interviews with SME owners in the Western Cape, South Africa, complemented by a targeted evidence review to inform boundary-condition assessment. The findings show that owner-managers assembled relational continuity bundles that combined labor flexibility, retention intent, transparent communication, and visible well-being support. Owners presented these bundles as efforts to sustain cooperation, trust, and operational functioning when enacted through fairness logics such as voice, transparency, equal sacrifice, and relational care. The study contributes to SME resilience and management and organization studies by distinguishing relational substitution from sustainable human resource management, organizational justice, relational leadership, and institutional fragility, and by specifying the firm-level and institutional conditions under which this mechanism is more likely to support strategic continuity. Full article

Polyploidy is increasingly recognized as a mechanism enhancing physiological resilience in woody fruit crops, yet its functional consequences remain poorly understood in mangoes (Mangifera indica L.), a major tropical species expanding into water-limited environments. Because leaf structure underpins plant water relations and gas exchange, this study evaluated how genome duplication alters foliar traits by comparing diploid and autotetraploid individuals of three polyembryonic cultivars (Gomera-1, Gomera-3, and Kensington Pride). Morphological and anatomical analyses revealed consistent ploidy-related modifications. Autotetraploids exhibited enlarged stomatal guard cells, increased leaf thickness, and changes in mesophyll organization, indicating greater structural investment in leaf tissues. These features are commonly associated with structural strategies that may contribute to water retention and hydraulic regulation, although their direct physiological consequences were not evaluated in the present study. Overall, our results indicate that genome duplication substantially modifies leaf structural traits in mangoes, although the magnitude and direction of these responses were cultivar-dependent. This study provides new insights into how polyploidy reshapes leaf morphology and anatomy in mangoes and advances our understanding of polyploid-induced structural variation in perennial fruit crops. Full article

Multidrug resistance (MDR) remains a major obstacle in cancer therapy, driving treatment failure and disease progression across diverse malignancies. A key determinant of MDR is the overexpression of ATP-binding cassette (ABC) transporters, particularly P-glycoprotein (P-gp/ABCB1), which actively effluxes structurally diverse chemotherapeutic agents and reduces their intracellular accumulation. Despite extensive investigation, clinically effective strategies to overcome P-gp-mediated resistance remain limited. This review provides a comprehensive analysis of the molecular mechanisms underlying P-gp function, including its structural organization, regulation of expression, and role in cellular drug disposition. We highlight the interplay between P-gp activity, oxidative stress, metabolic reprogramming and the tumor microenvironment, emphasizing the complexity of MDR as a dynamic and adaptive process. Emerging therapeutic approaches targeting P-gp-mediated resistance are also discussed, including natural bioactive compounds, nanotechnology-based drug delivery systems, polymeric carriers and novel anticancer agents designed to evade efflux mechanisms. Integrating mechanistic insights with advanced pharmacological strategies may improve intracellular drug retention and therapeutic efficacy. A deeper understanding of P-gp-driven MDR is essential for the development of effective interventions aimed at overcoming drug resistance and improving clinical outcomes in cancer patients. Full article

Geopolymer EPS concrete (GEPSC) is a promising low-carbon lightweight material for building envelope and thermal insulation applications. In order to investigate the effects of expanded polystyrene (EPS) content on the lightweight characteristics and mechanical properties of geopolymer EPS concrete (GEPSC), specimens with EPS volume contents of 30%, 35%, 40%, 45%, 50%, and 55% were prepared. Dry density, cube compressive strength, axial compressive strength, splitting tensile strength, flexural strength, and elastic modulus were tested, and empirical relationships among the main mechanical parameters were established. The results show that dry density, cube compressive strength, axial compressive strength, splitting tensile strength, and elastic modulus decrease with increasing EPS content, indicating a clear lightweighting–strength reduction effect. The low strength and low stiffness of EPS particles weaken the continuity and load-bearing skeleton of the geopolymer matrix, while promoting more dispersed crack propagation and a more gradual failure process. The correlation coefficients of the proposed empirical models are all greater than 0.90. Lightweighting efficiency analysis indicates that an EPS content of 40–45% provides a favorable balance among weight reduction, strength retention, and stiffness retention. Compared with EPS concrete, GEPSC exhibited 23.5–49.5% higher strength at the same density grade, indicating its good strength retention capacity and potential engineering applicability. These findings support mix optimization, mechanical parameter selection, and engineering application of low-carbon lightweight envelope materials. Full article

Heat transport in heterogeneous materials can deviate markedly from classical Fourier behavior when microstructural disorder, trapping effects, nonlinear mobility, and long-range temporal correlations interact across multiple spatial and temporal scales. These mechanisms may produce delayed relaxation, persistent thermal footprints, front deformation, and non-classical spreading patterns that are not adequately represented by conventional integer-order diffusion models. In this study, a modeling and simulation framework is developed for anomalous heat transport in heterogeneous media using a two-dimensional time-fractional porous medium equation. The model combines a Caputo fractional time derivative, which represents thermal memory, with nonlinear degenerate porous-medium diffusion, spatially heterogeneous conductivity, localized volumetric heating, and Robin-type convective boundary exchange. A conservative fully discrete numerical scheme is constructed using flux-based finite differences for the heterogeneous nonlinear diffusion operator and an $L1$ approximation for the Caputo derivative. The nonlinear algebraic system at each time level is solved using an under-relaxed Picard frozen-coefficient iteration with non-negativity enforcement and sparse direct solution of the resulting linear systems. The numerical implementation is verified through a manufactured-solution convergence study, and additional analyses are performed to examine computational cost, Picard iteration behavior, coefficient-regularization sensitivity, strong-source effects, heterogeneous conductivity structures, and long-time thermal-footprint persistence. The results show that heterogeneous conductivity mainly redirects heat through preferential pathways and enlarges the spatial footprint while producing negligible changes in global heat content. Stronger fractional memory, represented by smaller fractional order, increases the persistence and spatial reach of moderate heating, whereas larger porous-medium exponents confine heat near the source and preserve higher local peaks. Source amplitude increases the thermal burden and footprint monotonically over the tested range, including strong forcing, without producing an abrupt localization-spreading transition. Boundary exchange remains secondary in the short-time interior-heating regime considered. These findings demonstrate that the proposed two-dimensional time-fractional porous medium framework provides a verified and physically interpretable model for non-Fourier heat transport in heterogeneous materials, where local intensity, global heat retention, and spatial thermal exposure must be assessed jointly. Full article

Objectives: Skeletal muscle architecture (SMA) defines the mechanical limits of force production. However, its associations with force–time strategy under externally loaded conditions have received little research attention. This exploratory study examined associations between vastus lateralis (VL) and lateral gastrocnemius (LG) architecture and force–time strategy, jump-height retention, and stretch–shortening cycle (SSC) transfer-efficiency in collegiate basketball players. Methods: Seventeen collegiate male basketball players completed B-mode ultrasonographic assessment of VL and LG architecture, including muscle thickness, pennation angle (PA), and fascicle length. Athletes performed the squat jump (SJ), loaded squat jump (LSJ), countermovement jump (CMJ), and loaded countermovement jump (LCMJ) on force platforms, with a 20 kg external load applied for loaded conditions. Loaded retention, defined as the percentage of jump height preserved under load, was proposed as a unified construct. Pearson’s correlations were calculated, with Benjamini–Hochberg false discovery rate (FDR) corrections applied within predefined functional groups and pooled across morphology-sensitive correlations. Results: LG PA showed a large negative association with LCMJ rate of force development (r = −0.68 [−0.87, −0.30]) and a large positive association with LCMJ time to peak force (r = 0.68 [0.29, 0.87]), both surviving within-group FDR correction. VL PA was associated with eccentric acceleration time and concentric time across jump conditions (r = 0.52 to 0.61), interpreted as exploratory. Transfer-efficiency indices showed no significant associations with SMA, except for the LCMJ/LSJ concentric time ratio, which showed a moderate negative association with LG PA (r = −0.49 [−0.79, −0.01]). Conclusions: Resting muscle architecture was associated with the temporal and rate characteristics of force expression under load, rather than with the gross preservation of jump height. Integrating architectural assessment with loaded force–time profiling warrants further investigation as a means of characterizing individual force-development strategies. Full article

Background: Public healthcare systems face persistent workforce retention challenges that undermine service continuity, organizational resilience, and public value creation. Although leadership is frequently identified as a relevant lever, the literature remains theoretically fragmented and often treats leadership effects as direct and context-free. Methods: This review adopts a PRISMA-guided systematic literature review as a theory-building strategy. Searches were conducted in Web of Science, Scopus, and PubMed using combinations of terms related to leadership, organizational commitment, job satisfaction, turnover intention, and retention in healthcare settings. The review identified 640 records, removed 372 duplicates, screened 268 titles and abstracts, assessed 90 full-text records for eligibility, and retained 30 peer-reviewed studies for configurative synthesis. The analysis combined thematic synthesis with configurative mapping to identify mechanisms, recurring patterns, and contextual contingencies. Results: The review shows three consistent patterns. First, leadership is linked to retention predominantly through organizational commitment, especially affective and normative commitment, rather than through direct effects. Second, institutional and organizational conditions—particularly red tape and working conditions—shape the strength of leadership–commitment relationships. Third, workforce heterogeneity, including generational differences, affects how leadership practices and organizational environments are interpreted, although these dynamics are rarely theorized explicitly in the literature. Conclusions: The article develops a governance-sensitive integrative framework in which people-centered leadership influences turnover intentions indirectly through organizational commitment, while red tape and working conditions operate as contextual moderators. By embedding leadership within Public Administration and governance theory, the review clarifies the literature’s main explanatory gap and provides a foundation for comparative empirical testing and for more sustainable workforce strategies in public healthcare systems. Full article

This study evaluated the retention force between milled polyetheretherketone (PEEK) posts with different surface treatments and resin composites for core build-up, and the effect of thermal cycling on the retention force. Four groups of PEEK posts were prepared: untreated group (NT), mechanically treated group with sandblasting (SB), chemically treated group with primer application (AD), and a group combining mechanical and chemical treatments (SB+AD). Pull-out tests were conducted on these groups. The specimens were divided into two subgroups: one stored in a humid environment at 37 °C for one week (TC0) and the other subjected to 10,000 cycles of thermal cycling between 5 °C and 55 °C (TC10,000). Data were analyzed using two-way ANOVA and Tukey’s test. Additionally, the effect of thermal cycling on each group was examined using Student’s t-test. Both surface treatment and thermal cycling factors had statistically significant effects on retention force (p < 0.05). The interaction between these factors was also statistically significant (p < 0.05). The results showed that the retention force of the treated groups was significantly improved compared to the untreated group, with the SB+AD group exhibiting the highest retention force, followed by the SB group and then the AD group. Thermal cycling did not affect the retention force in the NT, SB, and SB+AD groups. These findings suggest that the combination of mechanical and chemical surface treatments is the most effective method for improving the retention force between PEEK posts and resin composites for core build-up. Furthermore, appropriate surface treatment of PEEK posts may influence their long-term durability. Full article

Employee attrition is a significant organizational challenge associated with substantial financial costs and the erosion of institutional knowledge. This study presents an AI-based Management Information System (MIS) that integrates machine learning (ML) models to forecast employee turnover and support technical interpretability for HR decision-making. Using the IBM HR Analytics Dataset comprising 1480 employee records with 38 features, we implemented a rigorous preprocessing pipeline—including Synthetic Minority Over-sampling Technique (SMOTE) applied exclusively within training folds to prevent data leakage, one-hot encoding, Z-score normalization, and mean-value imputation. Four ML classifiers—Logistic Regression (LR), Random Forest (RF), Multi-Layer Perceptron (MLP), and XGBoost—were evaluated under a stratified 80/20 split with 5-fold cross-validation. XGBoost achieved the highest performance, attaining an accuracy of 87.83%, a ROC-AUC of 0.94, a PR-AUC of 0.96, and an F1-score of 93.04%, attributed to its sequential boosting mechanism and built-in L1/L2 regularization. Beyond predictive performance, the system incorporates SHapley Additive exPlanations (SHAP) to deliver feature-level transparency, enabling HR professionals to engage in proactive, informed retention interventions while retaining full decision-making authority. Within-dataset comparisons confirm that the proposed framework outperforms prior methods evaluated on the same benchmark; cross-study accuracy comparisons are reported as contextual reference only, given differences in datasets and experimental protocols. The system facilitates human oversight by positioning AI as a decision-support collaborator rather than an autonomous replacement in workforce management. Future work will address real-time deployment, controlled user studies with HR practitioners, and validation with actual organizational HR data. Full article