Search Results (391)

This study examined the within-session (same-day) test–retest reliability of heart rate (HR) and parasympathetic modulation, assessed using the root mean square of successive differences (RMSSD), across exercise and recovery phases in trained soccer players. Twenty-seven male soccer players (age: 24.9 ± 3.7 years) completed a standardized soccer training session. HR and RMSSD were recorded using an ECG-based chest-strap monitor at rest, pre-exercise, and at ~10–20 min, 1 h, and 3 h post-exercise. At each time point, two consecutive 5 min seated recordings were obtained under identical conditions. Test–retest reliability was evaluated using intraclass correlation coefficients (ICC_(3,1)), standard error of measurement (SEM), coefficient of variation (CV%), minimal detectable change (MDC₉₅), paired-samples t-tests, and Hedges’ g effect sizes. HR demonstrated excellent reliability across all time points (ICC = 0.980–0.994; SEM = 0.87–1.25 bpm; CV% = 1.33–3.70%). RMSSD showed excellent reliability at rest (ICC = 0.944) and pre-exercise (ICC = 0.918), moderate reliability during early recovery (~10–20 min; ICC = 0.551), and good reliability at 1 h (ICC = 0.826) and 3 h post-exercise (ICC = 0.873). No significant systematic differences were observed between test and retest measurements (all p > 0.05), and effect sizes were trivial. These findings indicate that within-session reliability of HR remains consistently high across exercise and recovery phases, whereas RMSSD reliability varies according to measurement timing, particularly during early recovery. Full article

In response to increasing demand for environmental sustainability, construction firms are progressively adopting green-oriented management approaches to enhance long-term project success. This study examines the relationship between Green Human Resource Management (GHRM), Green Human Capital (GHC) and Sustainable Project Success (SPS) within the construction sector, with Green Work Climate (GWC) as moderator and Green Construction Practices (GCP) as mediator. Drawing upon the Resource-Based View (RBV), Natural Resource-Based View (NRBV), and Ability-Motivation-Opportunity (AMO) theory, the study explains how green human competencies and HR systems are associated with project sustainability. Data were collected from 436 construction professionals in Bangkok, Thailand, through online questionnaires, and analyzed using SmartPLS 4 and Structural Equation Modeling (SEM) analysis. The findings indicate that GHRM is positively associated with SPS, while GHC demonstrates an indirect relationship with SPS through GCP. The moderating effect of GHC was not supported. These results contribute to sustainable construction management literature by clarifying the mechanisms through which green human resources are converted to sustainability, offering practical implications for construction firms seeking to institutionalize sustainability through structured HR policies and operational practices. Full article

Analyses of the oxidation characteristics of HR3C austenitic steel exposed to supercritical carbon dioxide were carried out at temperatures ranging from 600 to 650 °C under 25 MPa. It was observed that the weight gain increased with increases in temperature and time. The oxide morphology and phase were characterized using scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Furthermore, the three-dimensional morphology and chemical composition of the surface oxide were inspected using a secondary ion mass spectrometer (SIMS). The majority of the oxide formed on HR3C at 600–650 °C was Cr₂O₃. Carbon enrichment occurs on the surface of the oxide scale and the oxide–substrate interface due to a carbonization reaction. The corrosion mechanism is also discussed in this paper. Full article

Over the past two decades, organic semiconductors have attracted significant research interest due to their advantageous features, including low-cost fabrication, lightweight properties, and portability, for photonic device applications. In this study, nickel sulfide doped with cobalt $(\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o})$ nanocomposites were successfully synthesized via a wet-chemical processing technique and used as a dopant in the active layer of thin-film organic solar cells (TFOSCs). The poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) blend was used as the active layer in this investigation. The devices were fabricated with $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposites at 1 wt%, 2 wt%, and 3 wt% in the active layer to determine the optimal dopant concentration. However, the experimental evidence clearly showed that the solar cell’s performance depends on the concentration of the $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposites. As a result, the highest power conversion efficiency (PCE) recorded in this experimental work was 6.11% at a 1% doping concentration, compared with 2.48% for the pristine reference device under AM 1.5G illumination (100 mW/cm²) in ambient conditions. The optical and electrical properties of the active layers are found to be strongly influenced by the inclusion of $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposites in the medium. However, the device doped with 1 wt% $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposite exhibits the highest absorption intensity, consistent with the better performance observed in this study, which can be attributed to the localized surface plasmon resonance (LSPR) effect. The optical and morphological characteristics of the synthesized $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposites were comprehensively analyzed using high-resolution transmission electron microscopy (HRTEM), high-resolution scanning electron microscopy (HRSEM), and additional complementary techniques. Full article

Streptococcus sanguinis (S. sanguinis) is an oral commensal and early colonizer of the tooth surface that contributes to dental biofilm homeostasis. Zinc oxide nanoparticles (ZnO NPs) are often incorporated into dental restorative materials to enhance mechanical performance and confer antibacterial properties; however, their effects on S. sanguinis have not been thoroughly studied. Here, we investigated the antimicrobial and antibiofilm efficacy of ZnO NPs against this bacterial species. ZnO NPs exhibited a minimal inhibitory concentration (MIC) of 100 µg/mL and caused rapid, dose-dependent suppression of intracellular ATP levels and overall metabolic activity within 2–4 h of exposure. ZnO NPs induced reactive oxygen species (ROS) production in a dose-dependent manner. The free radical scavenger α-tocopherol partly prevented the antibacterial effect of ZnO NPs, suggesting that lipid peroxidation contributes to ZnO NP-mediated toxicity, although it is not the sole mechanism involved. Short-term exposure (2 h) to ZnO NPs did not significantly affect membrane integrity or cellular morphology, whereas prolonged treatment (24 h) resulted in pronounced membrane permeabilization, membrane hyperpolarization, and cellular swelling. Computational morphometric analyses of high-resolution scanning electron microscopy (HR-SEM) images of planktonic growing bacteria after a 24 h treatment confirmed a significant, dose-dependent increase in cell surface area and surface roughness. Importantly, ZnO NPs also reduced the metabolic activity and compromised the structural integrity of mature, preformed biofilms. Collectively, these findings demonstrate that ZnO NPs exert antimicrobial and antibiofilm effects against S. sanguinis through early metabolic inhibition associated with oxidative stress followed by progressive membrane dysfunction. Full article

In this study, the structural and electrochemical performance of Nb₂CT_x MXene-based composite electrodes modified with activated carbon (AC) derived from food waste was systematically investigated for supercapacitor applications. Three composites with Nb₂CT_x:AC mass ratios of 90:10 (MXAC1), 80:20 (MXAC2), and 70:30 (MXAC3) were prepared and comparatively evaluated. SEM/EDS, XRD, HR-TEM, XPS, and BET analyses revealed that, in the MXAC2 composite, activated carbon was homogeneously distributed between the MXene layers, effectively suppressing restacking and promoting the formation of a hierarchical micro/mesoporous structure. XPS results confirmed the preservation of the Nb–C framework and the enrichment of surface functional groups (–O, –OH, and –F). BET analysis demonstrated that MXAC2 possesses an optimized pore architecture that facilitates efficient ion diffusion. Electrochemical measurements revealed that the MXAC2 electrode exhibited the highest specific capacitance at all scan rates and current densities. At 5 mV·s⁻¹, MXAC2 achieved a specific capacitance of 651.84 F·g⁻¹ and maintained a substantial capacitance even at a high current density of 4 A·g⁻¹. EIS analysis confirmed the very low charge transfer resistance (0.023 Ω) and enhanced capacitive behavior for MXAC2. Additionally, MXAC2 has high cycle stability, demonstrating 82.15% capacitive retention and 92.45% coulombic efficiency after 10000 cycles. These results indicate that food waste-derived AC-optimized Nb₂CT_x MXene composite materials are a strong candidate for sustainable and high-performance supercapacitor electrodes. Full article

This study presents an efficient, environmentally benign approach for synthesizing chitosan-entrapped titanium dioxide (TiO₂) nanocomposites utilizing aqueous orange peel extract playing its role in reduction and stabilization of the nanoparticles and exploring its anticancer activity in vitro. TiO₂ nanoparticles were initially synthesized via a modified sol-gel method incorporating the orange peel extract. Subsequently, these nanoparticles were entrapped within a chitosan matrix. The orange peel extract was thoroughly characterized using analysis of phytochemicals present, and Gas Chromatography–Mass Spectrometry (GC–MS) analysis of a reconstructed methanolic extract to identify potential biomolecules responsible for the reduction and capping processes. The synthesized chitosan-entrapped TiO₂ nanoparticles were subjected to comprehensive characterization using various analytical techniques, like UV–visible spectroscopy, Dynamic Light Scattering (DLS) and Zeta Potential analysis, X-ray Diffraction (XRD), FTIR, High-Resolution Scanning Electron Microscopy (HR-SEM) and Energy-Dispersive X-ray Spectroscopy (EDAX). An absorption peak was observed at 296 nm, a hydrodynamic diameter of 400 nm, a+ 35.88 mV zeta potential, and an SEM image showing a diameter in the range of 300–645 nm, indicating polymer entrapment with enhanced size. Brine shrimp assay, MTT assay using normal fibroblasts, 3T3-L1, and zebrafish embryo assay were done to observe the biocompatibility of the synthesized nanostructure. The concentration of 50 μg/mL was found to be inert in both in vitro and in vivo. Furthermore, cervical cancer cells, SiHa, were treated with the nanoparticles to exhibit their cancer-killing capability with an IC₅₀ value of 30.74 μg/mL. The results demonstrate the effectiveness of orange peel extract as a sustainable agent for TiO₂ nanoparticle synthesis and the successful formation of a stable chitosan-entrapped nanocomposite. This approach offers a promising pathway for producing functional metal oxide nanomaterials with reduced environmental impact and enhanced properties for diverse biomedical applications. Future studies using other types of cancer cells and animal models for cancerous tumors need to be explored. Full article

In this study, in situ P-doping of Ge-based layers has been studied and compared with implanted layer profiles acting as absorbent top layer in PIN photodetectors. Several structures containing multilayers of n⁺-Ge/i-Ge, n⁺-GeSi/i-Ge, and n⁺-Ge/i-GeSi, were designed to regulate dopant out-diffusion and interface quality. The purpose of this study is to make an optimized n-type doping layer for PIN photodetectors with low dark current, high responsivity, and high quantum efficiency operating in short wavelength infrared (SWIR) region. The Ge-based structure on Si substrate was transferred to oxidized Si substrate and was finally back-etched from Si to form Ge-on-insulator (GOI) substrate. Comprehensive characterization using high-resolution X-ray diffraction (HR-XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and photoluminescence (PL) have been applied at the first stage of our work. The initial Ge layer contains tensile strain of 0.15–0.17%. PL measurements further indicate a redshift of the Γ-LH transition and carrier-concentration-induced quenching at high doping levels, highlighting the competing effects of band filling and non-radiative recombination in heavily n-doped Ge structures. To circumvent this fundamental trade-off, we devised a decoupled device strategy in which the active absorption region employs an intrinsic Ge/GeSi nanoscale multilayer structure to preserve crystal and interface quality. Although, the epitaxial growth parameters were on the optimized conditions, still out-diffusion (in form of segregation and auto-doping) of P could not be impeded. Our final n-type layer in PIN structure was formed by implantation. This approach yields high-performance photodetectors with a peak responsivity of 0.99 A/W at 1550 nm, a corresponding external quantum efficiency of 79%, and low specific contact resistivities of 2.66 × 10⁻⁶ Ω·cm² (n-type) and 1.38 × 10⁻⁸ Ω·cm² (p-type). This work demonstrates that the strategic combination of multilayer/interface engineering and ion-implantation-based doping is a highly effective strategy for tailoring the optoelectronic properties of Ge-based nanomaterials for high-performance SWIR photodetection. Full article

Background: The eco-friendly synthesis of silver nanoparticles (AgNPs) utilizing medicinal flora presents a viable strategy for the development of multifunctional agents exhibiting antimicrobial, antioxidant, anti-inflammatory, and anticancer properties. This investigation aims to elucidate the phytochemical composition of Calotropis gigantea and its contribution to the synthesis of CG-AgNPs that demonstrate efficacy against Helicobacter pylori and gastric cancer cell lines. Methods: The aqueous plant leaf extract of C. gigantea underwent comprehensive analysis via gas chromatography-mass spectrometry (GC-MS), identifying a total of 25 bioactive constituents, including oleic and oxalic acid derivatives. The fabrication and analysis of silver nanoparticles (AgNPs) were performed utilizing methodologies including ultraviolet-visible (UV–Vis) spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), and assessments of zeta potential. Antibacterial efficacy was evaluated through methods including agar well diffusion, time-kill kinetics, and biofilm assays. The cytotoxic impact on AGS gastric cancer cells was investigated using MTT assays, DAPI staining, and acridine orange/ethidium bromide (AO/EtBr) staining techniques. The assessment of antioxidant potential was performed utilizing DPPH and ABTS assays. The anti-inflammatory properties were analyzed through protein denaturation and membrane stabilization tests. Results: CG-AgNPs exhibited a spherical morphology (11–17 nm) with commendable stability, denoted by using zeta potential analysis measurement of −30.2 mV. The antibacterial activity showed a significant inhibition zone of 16.00 ± 0.17 mm at a concentration of 50 µg/mL against H. pylori, in addition to notable biofilm disruption. The viability of AGS cells was reduced by 61% at a concentration of 100 micrograms per milliliter, with apoptosis being confirmed through relevant assays. The antioxidant potential varied from 18% to 83% (DPPH) and reached 74% (ABTS) at a concentration of 100 µg/mL. The anti-inflammatory assays indicated a BSA denaturation inhibition ranging from 45% to 80% and a membrane stabilization effect between 54% and 85%. Conclusions: CG-AgNPs exhibit substantial antibacterial, antioxidant, anti-inflammatory, and anticancer activities, underscoring their pharmaceutical potential, particularly for combating antibiotic-resistant pathogens and gastric malignancies. Full article

The study examines the mechanisms through which Green Human Resource Management (GHRM) and Green Innovation (GI) are associated with Sustainable Business Performance (SBP), with a particular focus on the mediating role of Organizational Citizenship Behavior for the Environment (OCBE). Cross-sectional survey data were collected from 500 employees and managers working in organizations participating in the United Nations Global Compact (UNGC) in Lebanon. Structural Equation Modeling (SEM) was employed to test the proposed relationships. The findings suggest that GHRM is positively associated with OCBE and SBP. OCBE was found to be a partial mediator and a key behavioral mechanism linking GHRM systems to sustainability outcomes. While GI shows a positive association with SBP in the initial direct models, this relationship became non-significant in the full structural model, indicating that its contribution largely depends on employee involvement and the presence of GHRM initiatives. The study’s findings position OCBE as a central mechanism that links HRM and sustainability and clarify the conditions under which GI predicts performance. This study extends sustainability research in emerging economies and addresses the necessity of investing in HR practices that actively motivate voluntary OCBE and provides empirical evidence, along with practical and theoretical insights, from a crisis-affected institutional context. Full article

Background/Objectives: Chlorhexidine (CHX) and alcoholic (A+) mouthwashes are associated with adverse oral effects. Therefore, this study compared the efficacies of non-alcoholic mouthwashes, including fluoride (A−) and herbal (Hr) rinses, for preventing bacterial accumulation and enamel demineralization around metal brackets (MBs), ceramic brackets (CBs), and resin composite attachments (RCAs). Methods: Following the exposure to CHX, A+, A−, and Hr rinses for 1 min, the growth of Streptococcus mutans on MB, CB, and RCA was assessed using colony-forming units and scanning electron microscopy (SEM). Controls included attachments without intervention. In another setting, enamel with bonded attachments was exposed to mouthwashes for 1 min and subjected to cariogenic demineralization for 24 h. Enamel’s Vickers microhardness was measured before and after the demineralization challenge. Data were analyzed using paired t-tests and one-/two-way ANOVA with Tukey’s tests. Results: CHX mouthwash demonstrated superior antimicrobial efficacy against S. mutans biofilms across all orthodontic attachments (p < 0.05). On metallic brackets, CHX (0 ± 0 log₁₀) and A− (1.7 ± 0.4 log₁₀) significantly (p < 0.001) outperformed controls (6.9 ± 0.1 log₁₀), Hr (6.08 ± 0.2 log₁₀), and A+ (6.2 ± 0.6 log₁₀). Similar patterns emerged for ceramic brackets, with CHX (0 ± 0 log10) and A− (1.4 ± 0 log10) superior to controls (6.6 ± 0.4 log₁₀). On resin composite attachments, CHX (2.9 ± 0.05 log₁₀) and Hr (3.4 ± 0.08 log₁₀) exceeded controls (5.4 ± 0.09 log₁₀) in inhibiting the biofilm growth (p < 0.05). Enamel microhardness reduction was significantly influenced by attachment type (p < 0.0001) and mouthwash type (p = 0.0063), with significant interaction between variables (p = 0.0052). Conclusions: CHX and A− mouthwashes effectively inhibited S. mutans biofilms on orthodontic attachments, while attachment type and mouthwash significantly influenced enamel microhardness reduction. Full article

Water contamination from diverse chemical pollutants has become a major environmental concern, demanding innovative and efficient remediation strategies. In this study, a Mg/Fe-layered double hydroxide (LDH) silica-magnetite hybrid composite was synthesized using a laser-cut microfluidic device to achieve controlled mixing and uniform particle formation. The obtained hybrid composite was further characterized by XRD, SEM, FT-IR, RAMAN, and DLS, confirming a structurally integrated LDH-silica-Fe₃O₄ hybrid, stabilized by ionic interactions, hydrogen bonds, and Si-O-Mg interactions. Moreover, biological assays confirmed that the developed material does not exhibit significant cytotoxicity and is potentially safe for environmental applications. Further, the adsorption performance was determined by treating surface water samples containing a mixture of pesticides with the composite material. After magnetic separation, the samples were analyzed by FT-ICR HR-MS, which enabled the detection and discrimination of ions with very close m/z values. The obtained results demonstrate a significant water decontamination capacity for multiple pesticides and facile water removal via magnetic separation, suggesting that these materials and the fast FT-ICR screening method are prospective, practical solutions for environmental protection of water bodies. Full article

Water represents the fundamental source of life for all human and animal populations; however, its consumption has become increasingly hazardous due to high levels of pollution. Modern agricultural practices rely heavily on pesticides, which significantly contribute to water contamination and imbalances in aquatic ecosystems. Moreover, another critical category of pollutants consists of pathogenic bacteria that proliferate in aquatic environments, mainly originating from hospital and urban wastewater because of human activity. Considering these major environmental and health challenges, the present study aims to develop an optimized method for water treatment by synthesizing magnetic silica-based aerogels using a microfluidic vortex chip and systematically varying synthesis parameters to enhance material performance. The physicochemical properties of the aerogels were characterized using XRD, FTIR, SEM, EDS, and BET. The pesticide adsorption capacity of the materials was evaluated using FT-ICR HR-MS analysis, which demonstrated the high efficiency of the aerogels in removing a complex mixture of pesticides. In parallel, antimicrobial efficacy was assessed against E. faecalis, E. coli, and P. aeruginosa isolated from surface water, hospital wastewater, and the influent of a well-known wastewater treatment plant in Bucharest, as well as against ATCC reference strains. Additionally, the study investigated the biocompatibility and biological responses of magnetic aerogels using MTT assays, nitric oxide production, lactate dehydrogenase release, intracellular ROS levels, and quantification of total protein, malondialdehyde, and reduced glutathione in HaCaT and HEK293 cell lines. The results confirm the efficiency and application potential of the developed materials and emphasize the importance of optimizing synthesis to achieve high-performance aerogels for effective decontamination of polluted waters. Full article

In knowledge-intensive professions such as auditing, positive workplace relationships are essential to effective performance. Yet, the specific mechanisms through which ethical leadership encourages critical, collaborative behaviours, such as knowledge sharing, remain underexplored. This study addresses this gap by examining how organisational justice and interpersonal trust serve as dual pathways that translate ethical leadership into the sharing of knowledge within audit teams. Using a cross-sectional survey design, data were collected from 232 auditing professionals in Iran and analysed via Structural Equation Modelling (SEM). The results confirm that ethical leadership is significantly associated with promoting knowledge sharing. More importantly, this relationship is robustly mediated by both organisational justice and trust, revealing a dual-channel mechanism through which leadership exerts its influence. The primary contribution of this research lies in empirically demonstrating this integrated model, illustrating that ethical leaders foster collaboration not only through direct influence but by systematically cultivating a fair and trustworthy work environment. For audit firms and similar professional service organisations, these findings highlight the practical importance of developing leaders and HR policies that explicitly and consistently prioritise fairness and trust-building to strengthen team dynamics and enhance the flow of knowledge. Full article

Topaz is one of the most economically important fluorine-rich nesosilicates, which are predominantly colorless in natural crystals. Hence, the trade relies almost entirely on irradiated blue topaz with an unstable color center, which has been shown to fade over time. The cobalt (Co) diffusion treatment is a stable alternative process for converting colorless topaz to blue by a solid-state diffusion mechanism. To investigate the potential role of Co²⁺ substitution in the formation of the blue layer and the coupled behavior of F/OH dehydroxylation in facilitating this process, systematic diffusion treatments have been successfully conducted and compared. In this study, gem-quality topazes were annealed in air at 1000 °C for 20–40 h (hr) along with CoO, Fe₂O₃, Cr₂O₃, and CuO powders. The diffused products were characterized using Scanning Electron Microscope (SEM), Ultraviolet-Visible absorption spectroscopy (UV-Vis), Near-Mid Infrared spectroscopy (NMIR), and X-ray photoelectron spectroscopy (XPS). Parallel runs with CuO, Fe₂O₃, or Cr₂O₃ alone confirmed that none of these oxides produces a stable blue layer, underscoring the unique role of Co. The Co-diffused sample displays an intense blue layer characterized by a Co²⁺ octahedral isomorphism triplet at 540, 580, and 630 nm, which are absent from both untreated and heat-only controls. XPS analysis reveals the emergence of Co²⁺ (binding energy: 780.63 eV) and a concomitant depletion in F⁻, along with the disappearance of the OH overtone absorption at 7123 cm⁻¹. These observations confirm that defluorination generates octahedral vacancies accommodated by the coupled substitution: CoF₂ (solid reactant) + (AlO₂)⁻ (fragment of topaz structure) → AlOF (solid product) + (CoOF)⁻ (fragment of topaz structure). Prolonged annealing leads to decreased relative atomic percentages of K⁺ and F⁻ ions, consistent with volatilization losses during the high-temperature process, thereby directly correlating color intensity with cobalt valence state, which transfers from Co²⁺ to Co³⁺. These findings establish a Co-incorporation chronometer for F–rich aluminosilicate systems, with an optimal annealing time of approximately 20 hr at 1000 °C. Furthermore, the above results demonstrate that the color mechanism in nesosilicate gems is simultaneously governed by volatile release and cation availability. Full article