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Effect of Mg–Nb oxides on hydrogen sorption kinetics of ball-milled MgH2
Full text linkAddition of Mg–Nb oxides (e.g. MgNb2O6, Mg4Nb2O9, and Mg3Nb6O11) ameliorates H2 absorption/desorption kinetics of MgH2 as demonstrated in the current article. H2 desorption and absorption rates of the ball-milled MgH2 are evidently temperature-dependent, which points out that the prior rate increases with increasing temperature (593–673 K) and vice versa. Among the tested samples, MgH2 with Mg3Nb6O11 nanoparticles showed superior performance. The Johnson–Mehl–Avrami equation was employed to construct H2 desorption curves as well as find out reaction rate constants at different temperatures. The Arrhenius equation was fitted in the context to estimate the activation energy of the ball-milled MgH2 and MgH2/Mg3Nb6O11 mixtures; for example, the values obtained were 127 and 88 kJ·mol−1, respectively. In addition, a novel experimental setup combining a hydrogen detector with a differential scanning calorimeter was used to confirm the H2 desorption properties of the ball-milled nanoparticles discussed based on the kinetic argument
Characterization of BTEX species at Texas Commission on Environmental Quality (TCEQ) Continuous Ambient Monitoring Station (CAMS) sites in Houston, Texas, USA during 2018
Full text linkVolatile Organic Compounds (VOCs) in the atmosphere negatively impact human and environmental health. Various sources of VOCs include gasoline evaporation, solvent usage, traffic, etc. A dataset 1-year (2018) consisting of BTEX (benzene, toluene, ethylbenzene, and m, p, and o-xylenes) concentrations in Houston, Texas, was analyzed to understand the spatial trends and sources of BTEX in the region. This study assesses 24-hour data concentrations from the Continuous Ambient Monitoring Station (CAMS) operated by the TCEQ Texas Commission on Environmental Quality (TCEQ) in Houston. Spatial variations of the BTEX species across the various TCEQ CAMS sites were determined using multiple statistical analyses, including Coefficients of Divergence (COD), Spearman’s correlation coefficient, and ANOVA Tukey’s test, while the BTEX interspecies ratios were calculated for further inter- and intra-urban exposure characterization. Ozone Forming Potential (OFP) was also calculated to analyze the role of VOCs in the formation of tropospheric ozone and to understand the role of VOCs in OFP in multiple seasons. OFP was higher in colder months than in other seasons of the year. Toluene exhibited greater concentrations with emission sources related to vehicular traffic emissions. The sites near the cluster of refineries were observed to have higher BTEX concentrations than others in Houston, Texas. These findings could help formulate targeted emission reduction strategies, for overall VOC levels in Houston, Texas
The off-season of dental cementum investigations. A critical appraisal of season-of-death prediction in medico-legal investigations
Full text linkIt has been suggested that death seasonality could be estimated based on the dark/bright appearance of the outermost dental cementum deposit. The few existing studies show variable accuracy rates. The question whether estimating season-of-death based on dental cementum represents a realistic and achievable goal can arise. This work, based on a software-assisted procedure and direct human observation, aims to critically evaluate the applicability of dental cementum to estimate the season-of-death in forensic anthropology. The sample consists of 20 canines from individuals belonging to the 21st century Identified Skeletal Collection, University of Coimbra, Portugal, and with documented biodemographic data. Fifty percent of the individuals died during the summer and 50% during the winter. Five non-decalcified 100 μm cross-sections per tooth were prepared, using a standardized protocol. Images of the region of interest, with the acellular cementum, were captured, and imported into FIJI/ImageJ software. Performance of the season-of-death predictions was very low, with 50% accuracy, score of 0.0000 for Matthews Correlation Coefficient, and F1-score of 61.5% for Summer and 28.6% for Winter, were obtained for the observer assessment. For the software model, performance was equally poor, with 52.6% accuracy, score of 0.0272 for Matthews Correlation Coefficient, and F1-score of 30.8% for Summer and 64.0% for Winter. This work is of relevance to the forensic science community by demonstrating the prospects and limitations of dental cementum as a method for estimating seasonality of death
Bioactivity and Mechanical Performance of Centrifugally Spun Poly(D,L-Lactide)/Poly(3-Hydroxybutyrate) Submicrometric Fibers Containing Zinc Oxide and Hydroxyapatite Nanostructures
No full textThis study investigates the morphological, thermal, mechanical, and bioactive properties of centrifugally spun fibrous composites made from poly(D,L-lactide)/poly(3-hydroxybutyrate) (PLA/PHB) blends with zinc oxide (ZnO) and hydroxyapatite (Hap) nanoparticles. A 75/25 PLA/PHB weight ratio was chosen to balance mechanical and thermal properties. The precursor solution viscosities ranged from 0.25 to 0.50 Pa s, increasing with nanoparticle incorporation probably due to polymer-nanoparticle interactions. SEM revealed a uniform fibrous morphology, with diameters of 1.21 for PLA/PHB, 2.65 for PLA/ZnO/Hap, and 1.80 μm for PLA/PHB/ZnO/Hap. TGA showed two-step degradation for PLA/PHB fibers, while PLA/PHB/ZnO/Hap degraded in a single step at 249°C, leaving a residue of 9.95%. DSC indicated partial miscibility, with cold crystallization at 85°C (enthalpy: 7.72 J/g), slightly modified by nanoparticle addition. PLA/PHB fibers achieved a Young\u27s modulus of 24.96 ± 3.91 MPa, three times that of pure PLA, but adding ZnO and Hap reduced modulus and tensile strength to 6.03 and 0.29 MPa, retaining suitability for biomedical applications. PLA/PHB/ZnO/Hap fibers exhibited 90% Escherichia coli growth inhibition and enhanced MC3T3-E1 cell viability by 120% on day 7. These results highlight their potential for antimicrobial, biocompatible medical devices
A Second Candidate Magnetic Helium Core White Dwarf and 3 Other Variable White Dwarfs in the Globular Cluster NGC 6397
Full text linkUsing archival Hubble Space Telescope observations, we report the discovery of four variable low-mass white dwarfs (WDs; 0.18 M⊙ ≤ M ≤ 0.5 M⊙) in the globular cluster NGC 6397. One source exhibits a periodic optical modulation of 5.21 ± 0.02 hr, which we interpret as potentially due to the rotation of a magnetic helium core WD (He WD). This makes this candidate the second magnetic He WD in NGC 6397, and one of the few He WDs with a measured rotation period. The other three candidates show aperiodic variability, with a change in magnitude ranging from ∼0.11 to 0.6. These discoveries highlight the importance of high-cadence photometric surveys in dense stellar environments. Follow-up spectroscopic observations are needed to confirm the nature of the variability of these systems
Does Societal Trust Reduce Greenwashing? International Evidence
No full textI investigate the influence of societal trust on greenwashing. Utilizing the ESG controversies score as a proxy for greenwashing, this research finds that firms in high-trust societies engage in fewer greenwashing activities. The effect is less pronounced for firms in countries with strong formal institutions, consistent with the notion that societal trust works as a substitute for country-level formal institution. However, the effect is more pronounced for highly visible firms. This study highlights three potential mechanisms through which societal trust reduces greenwashing practices: enhanced firm reputation, improved accounting transparency, and stronger stakeholder engagement. Overall, these findings underscore the significant role of societal trust in mitigating corporate greenwashing and fostering sustainable business practices
Validation of a brief food parenting measure for fathers: A test of factorial validity, measurement invariance, internal reliability, and concurrent validity
Full text linkFathers are underrepresented in food parenting research partly due to the lack of succinct, theory-informed, and father-mother equivalent food parenting measurement tools. To address this, we 1) tested the factorial validity of a brief food parenting measure utilizing a subset of items from the Comprehensive Feeding Practices Questionnaire (CFPQ) to represent coercive control, structure, and autonomy support, 2) assessed the extent to which the brief tool works similarly in fathers and mothers (i.e., measurement invariance), and 3) evaluated its internal reliability and concurrent validity. Participants included 1071 fathers of children aged 2–6 years and 487 of their co-parents (mothers) from the Fathers & Families study. Fathers and mothers responded to 16 CFPQ items, and fathers reported on children\u27s diets. Confirmatory factor analysis (CFA) was used to test factorial validity. Multi-group CFA was used to examine measurement invariance across fathers and mothers. Internal reliability was examined using Cronbach\u27s alpha and the Spearman-Brown coefficient. Concurrent validity was assessed utilizing multiple logistic regressions to examine associations between the three food parenting factors and children\u27s intakes of fruit, vegetables, sugar-sweetened beverages (SSBs), and fast food. CFA confirmed a three-factor model with 11 items, including coercive control (four items), structure (five items), and autonomy support (two items). Multi-group CFA indicated measurement invariance across fathers and mothers. Internal reliability was established. Concurrent validity was strong for structure, but weaker for coercive control and autonomy support. Further refinements are encouraged to enhance items\u27 utility in characterizing fathers\u27 food parenting practices, including in different social and cultural contexts
China’s readiness for transitioning to a low-carbon economy: mitigant and catalyst factors for a geopolitical conflict
Full text linkThe transition from a carbon-intensive economy to a carbon-neutral one has become a critical global objective to address climate change. This study examines the relationship between Low-Carbon Economic Development (LCED) and Geopolitical Risk (GPR) in China by focusing on the challenges and opportunities they present. We use a qualitative analysis to identify that rising GPR, exacerbated by market instability, resource allocation conflicts, and trade disputes, significantly hinders LCED progress. However, these geopolitical tensions also act as a catalyst for accelerating the development of renewable energy, reducing reliance on traditional energy sources, and fostering low-carbon technologies. Furthermore, LCED can ameliorate GPR by decreasing dependence on energy imports, promoting international cooperation, and encouraging scientific innovation. These findings suggest actionable policy recommendations to support the global transition to a low-carbon economy. This research underscores the potential LCED has as a fundamental tool for resolving geopolitical tensions and uniting global efforts to combat climate change
Visualizing Methane-Cycling Microbial Dynamics in Coastal Wetlands
No full textCoastal wetlands are the largest biotic source of methane, where methanogens convert organic matter into methane and methanotrophs oxidize methane, thus playing a critical role in regulating the methane cycle. The wetlands in South Texas, which are subject to frequent weather events, fluctuating salinity levels, and anthropogenic activities due to climate change, influence methane cycling. Despite the ecological importance of these processes, methane cycling in South Texas coastal wetlands remains insufficiently explored. To address this gap, we developed and optimized a method for detecting genes related to methanogens and methanotrophs, including mcrA as a biomarker for methanogens and pmoA1, pmoA2, and mmoX as biomarkers for methanotrophs. Additionally, this study aimed to visualize the spatial and temporal distribution patterns of methanogen and methanotroph abundance utilizing the geographic information system (GIS) software ArcGIS Pro. The integration of these molecular techniques with advanced geospatial visualization provided critical insights into the spatial and temporal distribution of methanogen and methanotroph communities across South Texas wetlands. Thus, the methodology established in this study offers a robust framework for mapping microbial dynamics in wetlands, enhancing our understanding of methane cycling under varying environmental conditions, and supporting broader ecological and environmental change studies
Unveiling the nature of peer development groups: A systematic review, conceptual framework, and research pathways
Full text linkThis research provides a systematic review of the literature on peer development groups (PDGs), a promising yet underexplored tool for individual and leadership development. Despite the growing interest in PDGs from both scholars and practitioners, the field remains fragmented, with inconsistent terminologies and limited theoretical grounding. This review seeks to clarify the core components, boundary conditions, inputs, processes, and outcomes of effective PDGs in professional settings, addressing the confusion and gaps in existing research. By adopting an adjudication approach, we provide a comprehensive synthesis of the evidence regarding the defining characteristics of PDGs and their impacts on individual development. We propose a new, scholarly definition of PDGs as organized small groups consisting of members of perceived similar status and roles who regularly meet to foster mutual growth by providing a supportive environment and a flexible agenda. We develop a conceptual framework that links key variables influencing PDG effectiveness and offers actionable insights for both researchers and practitioners. Our findings highlight opportunities for future research and suggest practical implications for implementing PDGs in organizational settings, ultimately contributing to a more cohesive and theoretically informed understanding of this valuable developmental practice