Search Results (687)

Ammonia decomposition represents a promising route for CO₂-free hydrogen production; however, the development of efficient and stable catalysts remains a critical challenge. In this work, a series of Al-based mixed-oxide catalysts (AlM, where M = Ni, Co, Ce) were synthesized via co-precipitation and systematically investigated to elucidate the relationship between physicochemical properties and catalytic performance in ammonia decomposition. Comprehensive characterization by X-ray diffraction (XRD), N₂ physisorption (BET), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and pyridine-adsorbed Fourier transform infrared spectroscopy (FTIR-Py) revealed significant variations in surface area, morphology, dispersion, and acidity as a function of the incorporated metal. Among the investigated catalysts, the AlNi system exhibited superior activity, achieving the highest ammonia conversion over the studied temperature range. This enhanced performance is attributed to its high specific surface area, homogeneous mesoporous structure, and a balanced distribution of Lewis/Brønsted acid sites, which promote effective ammonia adsorption, activation and decomposition. Kinetic analysis further confirmed the favorable reaction pathway on AlNi, as evidenced by its lower apparent activation energy and higher pre-exponential factor compared to the other materials. The results demonstrate a clear correlation between surface acidity, textural properties, and catalytic performance, highlighting the pivotal role of AlM interactions in governing ammonia decomposition. These findings provide valuable insights for the rational design of efficient catalysts for hydrogen production from ammonia. Full article

Boron (B) is increasingly recognized as more than a trace dietary element, emerging as a context-dependent organizer of molecular interactions at the host–microbiome interface. B exhibits reversible covalent chemistry driven by Lewis’ acidity and selective affinity for cis-diol-rich biomolecules, enabling dynamic complexation with polyols, glycans, and phenolic ligands that dominate the intestinal mucus environment and shape microbial ecology. We synthesize evidence supporting an architecture-based framework in which B modulates biological function by conditioning the physicochemical context of microbial communication rather than acting as a single-pathway effector. Central to this model is spatial bioavailability, distinguishing plasma-accessible boron from microbiota-accessible boron (MAB), species that persist in the lumen and mucus layer long enough to influence interface-level processes. We propose that insufficient or altered MAB availability may contribute to dysbiosis (DYS) by destabilizing quorum-associated coordination, signal persistence, and mucosal microstructure, thereby promoting barrier dysfunction and inflammaging. Particular attention is given to B-mediated symbiotaxis, a hypothesis-driven concept describing how B-containing molecular assemblies may bias microbial communities toward cooperative, barrier-supportive configurations and reduce ecological volatility. We identify key knowledge gaps and experimental priorities (speciation-aware measurements, signal-centric readouts) necessary to determine when, where, and how B-mediated molecular architecture may counteract DYS and support healthspan. Full article

Here, we report a highly efficient and stable catalytic system based on monometallic oxides supported on HY zeolites for the catalytic oxidation of chlorobenzene (CB). Among the transition and rare-earth metal oxides screened, the 30Cu/HY catalyst demonstrates exceptional performance, achieving near 100% CB conversion at 300 °C (500 ppm CB, 10,000 h⁻¹) alongside outstanding 24 h continuous stability without deactivation. Quantitative Py-IR analysis reveals that this superior activity is fundamentally driven by extensive solid-state ion exchange, forming robust Lewis acid centers (Cu-Y structures) that synergize with zeolitic Brønsted acid sites to efficiently polarize and cleave C-Cl bonds. Through an integrated approach combining in situ DRIFTS, real-time mass spectrometry, TGA, and NLDFT pore size analysis, we elucidate that the exceptional deep-oxidation capability of Cu/HY continuously mineralizes carbonaceous intermediates. This property minimizes coke deposition (2.91 wt%) and preserves the hierarchical pore architecture, preventing the coverage of active sites and severe pore blockage by partially oxidized intermediates (such as phenolic, aldehydic, and quinonic species) and stable carbonate species responsible for the deactivation of other metal oxides. These insights provide a mechanistic framework for the rational design of robust, chlorine-resistant catalysts for the sustainable abatement of persistent organic pollutants. Full article

The Lewis basic catalysts were susceptible to poisoning during the activation of peroxymonosulfate, resulting in their transformation into spent catalysts and subsequent secondary environmental contamination. In this work, the chemical constitution of the catalyst’s surface during both the deactivation and regeneration processes was intensively tracked. The mechanistic studies revealed that the reversible bonding of adsorbed hydroxyl groups generated from peroxymonosulfate activation with Lewis basic carbon atoms adjacent to pyridinic nitrogen was identified as the intrinsic mechanism responsible for the catalyst regeneration, accompanied by the reappearance of Lewis basic sites. Following high-temperature or sodium borohydride reduction, the activity of the catalysts was restored to over 90% of the initial activity, enabling the spent catalysts to be reused multiple times. Catalyst deactivation corresponded to an increase in the C–OH content from 24.3% to 35.2%, whereas regeneration reduced it to 25.16%. Furthermore, a strong inverse correlation was observed between the surface hydroxyl density and the catalytic activity. The study elucidates the deactivation and regeneration mechanisms of Lewis basic catalysts at the atomic scale, paving the way for durable applications in advanced oxidation processes. Full article

In this study, we prepare N–doped biochar loaded with β-CD, using cotton stalks as a carbon source, and evaluate its removal efficiency for tetracycline (TC) and methylene blue (MB) from aqueous solutions. This composite uniquely integrates molten salt activation, nitrogen doping, and β-CD grafting, resulting in an exceptionally high specific surface area of 1943 m²/g and abundant active sites. The findings reveal that β-CD-NKBC-1.5 (5 g of N–doped biochar loaded with 1.5 g of β-CD) demonstrates remarkable capabilities for both TC and MB removal across an extensive pH spectrum, reaching peak adsorption levels of 1269.8 and 969.4 mg/g at 308.15 K, respectively—outperforming most previously reported biochar-based adsorbents. The adsorption process is well described by the pseudo-second-order and Langmuir models, indicating that monolayer chemisorption is the dominant mechanism. β-CD-NKBC-1.5 exhibits preferential adsorption for TC and MB and maintains high adsorption efficiency even with coexisting ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, and SO₄²⁻) at concentrations up to 500 mg/L. The adsorption mechanism involves Lewis acid–base interactions, hydrogen bonding, π–π stacking, and pore filling. Full article

This paper presents a holistic development model for South African schools that aims to ensure inclusive and equitable quality education and promote lifelong learning opportunities for all, as defined by the United Nation’s Sustainable Development Goal 4: Quality Education, by 2030. It addresses critical gaps in private secondary schools, including unclear performance objectives, inadequate monitoring, and limited data-driven decision-making. To meet these needs, the study proposes a new performance management model based on Kaplan and Norton’s balanced scorecard framework, combining four perspectives: Students, Academic excellence, Learning and growth, and Resources. Using a positivist approach, the model was validated by confirmatory factor analysis of 244 respondents across 12 private schools in Durban. The Comparative Fit Index, Normed Fit Index, and Tucker–Lewis Index confirmed its structural validity, while the Root Mean Square of Error Approximation indicated excellent absolute fit. Several intercorrelations emerged within the Learning and growth perspective, particularly regarding staff respect for students and their value to students. Implementation revealed an overall satisfactory performance rating of 3.85 on a 5-point scale. The Student perspective scored lowest (3.39), highlighting inadequate student preparation as a key issue, with learners’ pre-class reading of material scoring just 2.81. These findings underscore the model’s utility in identifying areas for improvement, particularly in student engagement, academic excellence, and organisational culture within the Learning and Growth dimension. Full article

Ammonia decomposition represents a promising route for carbon-free hydrogen production, provided that efficient and cost-effective catalysts are developed. In this study, lanthanum-based mixed oxide catalysts (LaNi, LaCo, and LaCe) were synthesized via a controlled co-precipitation method and systematically evaluated for catalytic ammonia decomposition under atmospheric pressure in the temperature range of 350–500 °C. Comprehensive characterization combining N₂ physisorption, XRD, SEM–EDX, TGA–DTG, XPS, and FTIR-pyridine adsorption revealed pronounced structure–property relationships. LaNi exhibited the highest surface area (31.11 m²·g⁻¹), well-developed mesoporosity, and a balanced Lewis/Brønsted acidity (C_L/C_B ≈ 0.82), leading to superior catalytic performance with NH₃ conversion reaching ~48% at 500 °C (GHSV = 50 h⁻¹). LaCo showed intermediate activity (~30% conversion), while LaCe displayed limited performance (<13%), most likely due to its dense morphology and low surface accessibility. Increasing gas hourly space velocity resulted in decreased ammonia conversion for all catalysts, highlighting the critical role of residence time. These findings demonstrate that the catalytic efficiency of lanthanum-based systems is governed by the synergistic interplay between surface area, mesoporous architecture, and acidity distribution, with LaNi emerging as the most promising catalyst among the investigated materials. Full article

This study aims to systematically investigate the influence of substituent effects on the strength of Lewis acid–base interactions in frustrated Lewis pairs (FLPs). Specifically, -C₆F₅ groups of the classical Lewis acid B(C₆F₅)₃ are sequentially replaced with -C₆Cl₅, -C₆Br₅, and -C₆I₅ groups, and the Lewis acids are paired with the Lewis base 1,3-disubstituted imidazol-2-ylidene (ItBu) to form FLPs. Further energy decomposition analysis (sobEDA), orbital analysis, and molecular fragment density difference (MFDD) analysis reveal the nature of the substituent effect on the interaction energy (∆Eint) of the FLPs. The research findings indicate that the ∆Eint of B(C₆F₅)3-ItBu, B(C₆F₅)_x(C₆Y₅)_3−x-ItBu (x = 0, 1, 2; Y = Cl, Br, I) originates mainly from the interaction between the outermost halogen atom of the Lewis acid and the central carbon (C) atom of the Lewis base, rather than from the interaction between the central atoms boron (B) and carbon (C). This mechanism ultimately leads to a ∆Eint for B(C₆F₅)₂(C₆Y₅)-ItBu (Y = Cl, Br, I) that is comparable to that of B(C₆F₅)₃-ItBu. This indicates that modified B(C₆F₅)₂(C₆Y₅) (Y = Cl, Br, I) exhibits greater potential for the construction of novel FLPs. Full article

Titanosilicates are Lewis acid catalysts widely applied in liquid-phase olefin epoxidation; however, in the presence of water, their performance is often limited by structural instability, active-site deactivation, and competing side reactions. This review critically examines hydrophobization strategies—based on controlled reduction in silanol groups or incorporation of organic functionalities—and discusses the experimental approaches used to evaluate surface hydrophobicity, including water adsorption measurements, infrared spectroscopy of silanols, contact angle analysis, and complementary spectroscopic methods. Although direct quantitative comparison among studies is hindered by differences in reaction systems and the lack of standardized catalytic metrics, consistent trends emerge. Lower silanol densities are generally associated with improved preservation of isolated tetrahedral Ti (IV) sites, higher H₂O₂ utilization efficiency, and reduced secondary epoxide ring-opening, leading to enhanced activity and selectivity under comparable conditions. These improvements are attributed to decreased local water activity, suppression of non-productive oxidant decomposition, and stabilization of Ti-peroxo intermediates responsible for direct epoxidation. Incorporation of organic groups produces a similar beneficial effect when introduced in moderate amounts, increasing surface hydrophobicity without significantly perturbing Ti coordination. However, beyond an optimal loading, catalytic performance declines due to pore blockage, diffusion limitations, and partial masking of active sites, revealing a threshold behavior. Fluoride also plays a dual role: when used during synthesis, it influences the insertion and distribution of framework Ti, whereas as a post-treatment, it primarily regulates silanol density and surface polarity while preserving active sites. Finally, hydrophobicity cannot be considered independently, as its impact depends on the solvent, oxidant, olefin nature, and active-site location, which collectively govern activity, selectivity, and catalyst stability. Full article

Polysilicon is widely used in the photovoltaic and semiconductor industries. The presence of trace phosphorus impurities in the trichlorosilane feedstock can severely degrade the quality of polysilicon products. To address the urgent need for complete phosphorus removal of trichlorosilane, in this work, on the basis of the reducing ability of PCl₃ and the stronger Lewis base properties of its oxidation product, POCl₃, we developed an efficient material, xMo/Al₂O₃[y], using Al₂O₃ as the support and Mo species as active substances through a simple and straightforward method. Under the optimized preparation conditions of 7.8% Mo loading and a calcination temperature of 450 °C, the adsorbent exhibited optimal performance in an organic system simulating a trichlorosilane system with a P adsorption capacity of 53.52 mg g⁻¹, achieving near-complete elimination of phosphorus impurities. A series of characterization analyses suggested the following primary removal mechanism: initial oxidation of PCl₃ to POCl₃ by Mo⁶⁺ species, followed by its complexation with Mo sites via Lewis acid-base interactions. Furthermore, surface morphology damage during the removal process and the accumulation of reaction products on the spent adsorbent are the main factors contributing to its deactivation. This work presents an effective strategy for the deep dephosphorization of trichlorosilane. Full article

The short career of the Philadelphia-built transatlantic steamship S.S. Lewis (1851–1853) offers an instructive look at speculation, financing, and operating a steamer in the mid-19th century United States. S.S. Lewis was built as an American entry into the highly competitive arena of the transatlantic steam packet service. An early propeller steamer, it was heralded as an exemplar of American technology and shipbuilding prowess. It was also cleverly marketed, and named for Samuel Shaw (S.S.) Lewis, the Boston-based agent for Cunard. Following the failure of the transatlantic partnership that operated S.S. Lewis, the vessel entered the isthmian service from Nicaragua to San Francisco during the California Gold Rush. It wrecked, without loss of life, in April 1853 north of the Golden Gate. The wreck site, known to pioneering wreck divers for decades, is now archaeologically described and assessed for the first time. The post-wreck saga of the site is an important part of the story of the evolution of maritime archaeology in California. Full article

The emergence of large-scale models and machine learning has transformed the modeling of complex nonlinear systems, such as postseismic stress evolution. However, purely data-driven approaches often lack interpretability and numerical stability, leading to physically inconsistent long-term predictions. This study addresses these limitations by introducing a coupled Kolmogorov–Petrovsky–Piskunov–Rate-and-State (KPP–RS) reaction–diffusion system as a rigorous physical prior for large-scale modeling of stress-driven dynamics. Using analytic semigroup theory and Banach’s fixed-point theorem, we establish the global existence and uniqueness of solutions, ensuring that the governing dynamics are mathematically well posed—a necessary prerequisite for stable learning-based frameworks. We further prove the global dissipativity of the system and identify a bounded absorbing set in the H¹ phase space, which imposes intrinsic physical constraints and limits unphysical parameter exploration in large-scale optimization or black-box modeling. In addition, a Courant–Friedrichs–Lewy (CFL) stability condition is derived, providing a theoretical benchmark for time-step selection in numerical implementations, including physics-informed or hybrid neural architectures. This analytical framework supplies a mathematically controlled foundation for developing robust, interpretable, and stable pattern-recognition or time-series representations in complex geophysical systems. Full article

Architecture, as a profession, discipline and practice, has played a vital role in designing, constructing and maintaining modern culture. The creative work of imagining and building places, infrastructure and dwellings for the complex activities of contemporary life has contributed to the global world we now inhabit. There are, however, indications that this edifice of modernity is cracking because of external and internal forces that undermine our global society. Climate change, species extinction, and worldwide threats to democracy and governance, along with new technologies, converge and reveal the uncomfortable possibility that modern industrial global culture and civilization may collapse. As a response, an expanding body of ‘stories of collapse’ has emerged to interpret causes, processes, and scenarios. This essay engages with key voices (Rees, Bendell, Lewis, Hagens, de Oliveira, and Macy), to describe in what ways architecture is complicit in this moment, and suggests what ethical and place-based responsibilities may be required of architects and placemakers as collapse unfolds. Full article

Background/Objectives: Messenger RNA (mRNA) vaccine technology has shown great potential in the prevention of infectious diseases and treatment of cancers, but its full potential is limited by non-specific delivery mediated by the current lipid nanoparticle (LNP) platform. Methods: Here, we developed a dendritic cell (DC)-targeting LNP incorporated with an ultra-high-affinity CLEC9A-specific nanobody that facilitates enhanced DC uptake but reduced liver accumulation. We assessed the therapeutic efficacy of nanobody-functionalized lipid nanoparticles (Nb-LNPs) in a mouse Lewis lung carcinoma (LLC) model, alongside an evaluation of T cell-mediated immune responses and dendritic cell activation, facilitated by the delivery of mRNA-based neoantigen vaccines. Results: Compared with the use of an unfunctionalized LNP, personalized mRNA cancer vaccines encapsulated with this Nb-LNP demonstrated not only superior anti-tumor effects but also a favorable bio-safety profile in a mouse Lewis lung carcinoma model. The mRNA Nb-LNP neoantigen vaccines also induced substantially higher levels of DC maturation and more potent antigen-specific T cell responses, in particular CD4⁺ T cell responses, which are critical for initiation of anti-tumor immunity and immune memory. Conclusions: Taken together, these results suggest that precision-engineered LNPs conjugated with a CLEC9A-specific antibody or nanobody could be a promising platform for delivering mRNA vaccines specifically to dendritic cells, improving their prophylactic or therapeutic effects. Full article

Background/Objectives: Nutritional management is central to the care of patients with end-stage renal disease (ESRD), yet malnutrition often remains under-recognized due to gaps in nursing knowledge and competencies. This study aimed to develop and validate the Nursing Education and Competencies in Nutrition for Patients with CKD in ESRD (NECN-ESRD) questionnaire, designed to assess nephrology nurses’ competencies, attitudes, and practices in nutritional care. Methods: A methodological and cross-sectional design was adopted, following the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) recommendations for instrument development. The process comprised five phases: construct definition and item generation, expert consultation and revision, quantitative content validity analysis, pilot testing, and psychometric testing. Data were collected between August and September 2025 from 405 nephrology nurses across Italy. Exploratory Factor Analyses (EFAs) and Confirmatory Factor Analyses (CFAs) were conducted on split samples (60/40), and key psychometric properties were evaluated. Results: EFA identified a four-factor structure—Recommendations, Attitudes, Practice, and Advanced Competencies—which was confirmed through CFA with good fit indices [Comparative Fit Index (CFI) = 0.995, Tucker–Lewis Index (TLI) = 0.994, Root Mean Square Error of Approximation (RMSEA) = 0.07]. A higher-order model further improved fit (CFI = 0.994, RMSEA = 0.029), explaining 68.2% of variance. Internal consistency was excellent (ω = 0.89–0.96), test–retest reliability showed perfect agreement [Intraclass Correlation Coefficient (ICC) = 1.00], and invariance testing supported equivalence across educational and experience levels. Conclusions: The NECN-ESRD demonstrated strong validity, reliability, and stability, providing a robust and context-specific tool to assess and enhance nurses’ competencies in nutritional care for ESRD patients. Its application can support targeted educational interventions, improve clinical practice, and contribute to enhancing the quality of nutritional care for patients with ESRD within healthcare systems. Full article