Search Results (107)

Semi-flexible pavement (SFP) relies primarily on the properties of cementitious grouting material (CGM), which plays a crucial role in providing durability and crack resistance. This paper investigates the performance of CGMs containing recycled waste glass (RWG) as a replacement to fine granite aggregate (FGA) and their effect on SFP mixtures. Two high-fluidity glass-cementitious grouts (Glcement grouts) were developed and tested at five RWG replacement levels (0%, 30%, 50%, 70%, and 100%). The results indicated that CGM with 70% RWG provided the most balanced performance, with a flowability of 11.8 s, low drying shrinkage (0.04%), and water absorption not exceeding 1.9%. The mechanical properties were significantly enhanced, achieving a high compressive strength of 121.9 MPa and a high flexural strength of 13.9 MPa. Microstructural analysis confirmed a refined interfacial transition zone with low porosity (5.36%), contributing to superior durability. Furthermore, the SFP mixture injected with Glcement exhibited high mechanical performance, attributed to improved interlocking within voids. In conclusion, replacing FGA with RWG in CGM optimizes both mechanical and durability properties, promoting sustainable and low-carbon pavement construction. Full article

The reverse water gas shift reaction (RWGS) is a key step in the valorization of CO₂ to value-added products such as fuel. Metal carbides, particularly molybdenum carbide (Mo₂C), supported on transition metal oxide supports have been reported as promising materials to be used as catalysts for the low-temperature RWGS reaction. A deeper understanding of catalyst support interactions can be greatly beneficial for the development of better and more efficient catalysts in the future. To this end, this study computationally investigated the effect of the interaction between the Mo₂C(001) surface and the MgO(001) surface on the RWGS mechanism. The RWGS mechanisms were explored at the Mo₂C/MgO interface, as well as on the bare surface of Mo₂C. While the pathway at the interface went through an associative-type mechanism and a carboxylate intermediate, the Mo₂C surface was found to go through a redox-type mechanism. Interestingly, both the kinetics and thermodynamics of each pathway were similar, suggesting that the observed differences in the CO₂ hydrogenation pathways were primarily limited by the diffusion of CO₂ across the MgO surface rather than inhibitory energetics resulting from the interplay of the Mo₂C material and MgO support. Full article

The SARS-CoV-2 spike (S1) protein facilitates viral entry through binding to angiotensin-converting enzyme 2 (ACE2), but it also contains an Arg–Gly–Asp (RGD) motif that may enable interactions with RGD-binding integrins on ACE2-negative cells. Here, we provide quantitative evidence for this alternative binding pathway using a live-cell, label-free resonant waveguide grating (RWG) biosensor. RWG technology allowed us to monitor real-time adhesion kinetics of live cells to RGD-displaying substrates, as well as cell adhesion to S1-coated surfaces. To characterize the strength of the integrin–S1 interaction, we determined the dissociation constant using two complementary approaches. First, we performed a live-cell competitive binding assay on RGD-displaying surfaces, where varying concentrations of soluble S1 were added to cell suspensions. Second, we recorded the adhesion kinetics of cells on S1-coated surfaces and fitted the data using a kinetic model based on coupled ordinary differential equations. By comparing the results from both methods, we estimate that approximately 33% of the S1 molecules immobilized on the Nb₂O₅ biosensor surface are capable of initiating integrin-mediated adhesion. These findings support the existence of an alternative integrin-dependent entry route for SARS-CoV-2 and highlight the effectiveness of label-free RWG biosensing for quantitatively probing virus–host interactions under physiologically relevant conditions without the need of the isolation of the interaction partners from the cells. Full article

Propylene production through the CO₂-assisted oxidative dehydrogenation of propane (CO₂-ODP) is an effective route able to address the ever-increasing demand for propylene and simultaneously utilize CO₂. In this study, a series of alumina-supported gallium oxide catalysts of variable Ga₂O₃ loading was synthesized, characterized, and evaluated with respect to their activity for the CO₂-ODP reaction. It was found that both the catalysts’ physicochemical characteristics and performance were strongly affected by the amount of Ga₂O₃ dispersed on Al₂O₃. Surface basicity was maximized for the sample containing 20 wt.% Ga₂O₃, whereas surface acidity was monotonically increased with increasing Ga₂O₃ loading. A volcano-type correlation was found between catalytic performance and acid/base properties, according to which propane conversion and propylene yield exhibited optimum values for intermediate surface basicity and acidity, which both correspond to the sample containing 30 wt.% Ga₂O₃. The dispersion of a suitable amount of Ga₂O₃ on the Al₂O₃ surface not only enhances the conversion of propane to propylene but also suppresses the formation of side products (C₂H₄, CH₄, and C₂H₆) at temperatures of practical interest. The 30%Ga₂O₃-Al₂O₃ catalyst exhibited very good stability at 550 °C, where byproduct formation and carbon deposition were limited. Mechanistic studies indicated that the reaction proceeds through a two-step oxidative route with the participation of CO₂ in the abstraction of H₂, originating from propane dehydrogenation, through the reverse water–gas reaction (RWGS) reaction, shifting the thermodynamic equilibrium towards propylene generation. Full article

Internal Dry Reforming of Methane (IDRM) in biogas fed Solid Oxide Fuel Cells (SOFCs) was investigated on Fe-Au modified Ni/GDC electrolyte-supported cells at 900 and 850 °C. The aim was to clarify the synergistic interaction between Fe and Au, focusing on the effect of X wt.% of Au loading (where X = 1 or 3 wt.%) in binary Au-Ni/GDC and ternary 0.5 wt.% Fe-Au-Ni/GDC fuel electrodes. The investigation combined i-V, Impedance Spectroscopy and Gas Chromatography electrocatalytic measurements. It was found that modification with 0.5Fe-Au enhanced significantly the electrocatalytic activity of Ni/GDC for the IDRM reaction, whereas the low wt.% Au content had the most promoting effect. The positive interaction of 0.5 wt.% Fe with 1 wt.% Au increased the conductivity of Ni/GDC and enhanced the corresponding IDRM charge transfer electrochemical processes, especially those in the intermediate frequency region. Comparative long-term measurements, between cells comprising Ni/GDC and 0.5Fe-1Au-Ni/GDC, highlighted the significantly higher IDRM electrocatalytic activity of the modified electrode. The latter operated for almost twice the time (280 h instead of 160 h for Ni/GDC) with a lower degradation rate (0.44 mV/h instead of 0.51 mV/h). Ni/GDC degradation was ascribed to inhibited charge transfer processes in the intermediate frequencies region and to deteriorated ohmic resistance. Stoichiometric analysis on the (post-mortem) surface state of each fuel electrode showed that the wt.% content of reduced nickel on Ni/GDC was lower, compared to 0.5Fe-1Au-Ni/GDC, verifying the lower re-oxidation degree of the latter. This was further correlated to the hindered H₂O production during IDRM operation, due to the lower selectivity of the modified electrode for the non-desired RWGS reaction. Full article

Sorption-enhanced reverse water–gas shift (SE-RWGS), designated as COMAX, was studied using a Pt4A bifunctional catalyst (reactive adsorbent). The bifunctional Pt4A catalyst integrates CO₂ activation and reaction with water adsorption functionality, where the active phase is loaded onto a carrier that provides a surface area for Pt dispersion as well as H₂O adsorption capacity. The 0.3 wt% Pt-4A molecular sieve reactive sorbent was tested at a kg scale in a pressure swing (reactive) adsorption–regeneration process. More than 400 cycles over 50 days of operation were successfully demonstrated without significant decay. Cyclic stability was achieved, provided that the regeneration temperature was sufficiently high to ensure near-complete dehydration. The single-bead structure withstood the pressure swing operation effectively, with only a maximum of 2% of the total recovered reactive sorbent turning to fines (<500 μm). The successful integration of catalytic activity and water adsorption capacity into a single particle presents opportunities for the further intensification of sorption-enhanced reactions for CO₂ conversion. Full article

The CO₂ (Dry) Reforming of Methane (DRM) is a key process for reducing CO₂ and CH₄ emissions while producing syngas with an H₂/CO ratio of 1, ideal for Fischer–Tropsch synthesis. This study explores DRM and the Reverse Water Gas Shift (RWGS) reaction under mild conditions using Ru-based catalysts supported on CeO₂, YSZ, TiO₂, and SiO₂, with three reactant ratios: (i) stoichiometric, PCO₂ = 1 kPa, PCH₄ = 1 kPa, (ii) oxidizing, PCO₂ = 2 kPa, PCH₄ = 1 kPa, and (iii) reducing, PCO₂ = 1 kPa, PCH₄ = 4 kPa. The results highlight the importance of redox support for catalyst stability, with mobile lattice oxygen aiding carbon gasification. While Ru/CeO₂ is stable at high temperatures, it rapidly deactivates at low temperatures, emphasizing the need for precise metal particle size control. This work demonstrates the necessity of fine-tuning catalyst properties for more sustainable DRM, offering insights for next-generation CO₂ utilization catalysts. Full article

This study focuses on optimizing the Reverse Water Gas Shift (RWGS) reaction system using a membrane reactor to improve CO₂ conversion efficiency. A one-dimensional simulation model was developed using FlexPDE Professional Version 8.01/W64 software to analyze the performance of ZSM-5 membranes integrated with 0.5 wt% Ru-Cu/ZnO/Al₂O₃ catalysts. The results show that the membrane reactor significantly outperforms the conventional Packed Bed Reactor by achieving higher CO₂ conversion (0.61 vs. 0.99 with optimized parameters), especially at lower temperatures, due to its ability to remove H₂O and shift the reaction equilibrium selectively. Key operational parameters, including temperature, pressure, and sweep gas flow rate, were optimized to maximize membrane reactor performance. The ZSM-5 membrane showed strong H₂O selectivity, with an optimum operating temperature of around 400–600 °C. The problem is that many reactants permeate at higher temperatures. Subsequently, a Half-MPBR design was introduced. This design was able to overcome the reactant permeation problem and increase the conversion. The conversion ratios for PBR, MPBR, and Half-MPBR are 0.71, 0.75, and 0.86, respectively. This work highlights the potential of membrane reactors to overcome the thermodynamic limitations of RWGS reactions and provides valuable insights to advance Carbon Capture and Utilization technologies. Full article

The completion of the Human Genome Project in 2003 has led to significant advances in patient care in medicine, particularly in diagnosing and managing genetic diseases and cancer. In the realm of genetic diseases, approximately 15% of critically ill infants born in the U.S.A. are diagnosed with genetic disorders, which comprise a significant cause of mortality in neonatal and pediatric intensive care units. The introduction of rapid whole-genome sequencing (rWGS) as a first-tier test in critically ill children with suspected, undiagnosed genetic diseases is a breakthrough in the diagnosis and subsequent clinical management of such infants and older children in intensive care units. Rapid genome sequencing is currently being used clinically in the USA, the UK, the Netherlands, Sweden, and Australia, among other countries. This review is intended for students and clinical practitioners, including non-experts in genetics, for whom it provides a historical background and a chronological review of the relevant published literature for the progression of pediatric diagnostic genomic sequencing leading to the development of pediatric rWGS in critically ill infants and older children with suspected but undiagnosed genetic diseases. Factors that will help to develop rWGS as a clinical test in critically ill infants and the limitations are briefly discussed, including an evaluation of the clinical utility and accessibility of genetic testing, education for parents and providers, cost-effectiveness, ethical challenges, consent issues, secondary findings, data privacy concerns, false-positive and false-negative results, challenges in variant interpretation, costs and reimbursement, the limited availability of genetic counselors, and the development of evidence-based guidelines, which would all need to be addressed to facilitate the implementation of pediatric genomic sequencing in an effective widespread manner in the era of precision medicine. Full article

This study reports the synthesis, characterization, and catalytic performance of a series of catalysts of Ru supported on CeO₂-Y₂O₃ composites (Ru/CeYX; X = 0, 33, 66, and 100 wt.% Y₂O₃) for CO₂ hydrogenation. Supported material modification (Y₂O₃-CeO₂), by the Y₂O₃ incorporation, allowed a change in selectivity from methane to RWGS of the CO₂ hydrogenation reaction. This change in selectivity is correlated with the variation in the physicochemical properties caused by Y₂O₃ addition. X-ray diffraction (XRD) analysis confirmed the formation of crystalline fluorite-phase CeO₂ and α-Y₂O₃. High-resolution transmission electron microscopy (HR-TEM) and energy-dispersive X-ray spectroscopy (EDS) elemental mapping revealed the formation of a homogeneous CeO₂-Y₂O₃ nanocomposite. As the Y₂O₃ content increased, the specific surface area, measured by BET, showed a decreasing trend from 106.3 to 51.7 m² g⁻¹. X-ray photoelectron spectroscopy (XPS) of Ce3d indicated a similar Ce³⁺/Ce⁴⁺ ratio across all CeO₂-containing materials, while the O1s spectra showed a reduction in oxygen vacancies with increasing Y₂O₃ content, which is attributed to the decreased surface area upon composite formation. Catalytically, the addition of Y₂O₃ influenced both conversion and selectivity. CO₂ conversion decreased with increasing Y₂O₃ content, with the lowest conversion observed for Ru/CeY100. Regarding selectivity, methane was the dominant product for Ru/CeY0 (pure CeO₂), while CO was the main product for Ru/CeY33, Ru/CeY66, and Ru/CeY100, indicating a shift towards the reverse water–gas shift (RWGS) reaction. The highest RWGS reaction rate was observed with the Ru/CeY33 catalyst under all tested conditions. The observed differences in conversion and selectivity are attributed to a reduction in active sites due to the decrease in surface area and oxygen vacancies, both of which are important for CO₂ adsorption. In order to verify the surface species catalytically active for RWGS, the samples were characterized by FTIR spectroscopy under reaction conditions. Full article

Background: Rapid weight gain in early infancy increases the risk of childhood obesity, while exclusive breastfeeding can protect against it, depending on breastmilk composition, maternal diet, and infant gut microbiota. Objective: The objective of this study was to analyze the association between maternal diet, breastmilk components, infant gut microbiota, and weight gain in the first year of life of Mexican breastfed infants. Methods: This longitudinal study included 27 mothers with exclusively breastfed infants (≥5 months of age). We evaluated maternal diet and breastmilk composition at 5 months postpartum (pp), the infant fecal microbiota at 5 and 12 months pp using 16S rRNA gene sequencing, and weight gain as normal, rapid or slow weight gain (NWG, RWG or SWG) in periods 1 (0–5.5 months) and 2 (5.5–12 months). Results: Infants with NWG in periods 1 and 2 made up 51% and 56%, respectively. In period 1, ingested breastmilk protein content was higher for NWG infants than for infants with SWG (p = 0.01), and the protein content was negatively correlated with maternal BMI (r = −0.42, p = 0.02). The genera Veillonella (19.5%), Bifidobacterium (19.5%), and Escherichia-Shigella (16.8%) dominated the microbiota at 5 months. At 12 months, Bacteroides predominated, and the first two genera remained. Breastmilk fat correlated with Veillonella abundance (r = −0.50, p = 0.02) and oligosaccharides with Lachnospiraceae (r = 0.73, p = 0.03) at 5 months. There was a trend of a higher abundance of Bifidobacterium in NWG infants than in other infants in period 1, while infants with RWG and SWG had a higher abundance of Ruminococcus gnavus (p = 0.03) in period 1 and Alistipes in period 2 (p = 0.01), respectively. Conclusions: Breastfeeding shaped the gut microbiota of exclusively breastfed infants, and its structure was associated with infant weight gain trajectories. Full article

Excessive (carbon dioxide) CO₂ emissions are a primary factor contributing to climate change. As one of the crucial technologies for alleviating CO₂ emissions, carbon capture and utilization (CCU) technology has attracted considerable global attention. Technologies for capturing CO₂ in extreme circumstances are indispensable for regulating CO₂ levels in industrial processes. The unique separation characteristics of the ceramic–carbonate dual-phase (CCDP) membranes are increasingly employed for CO₂ separation at high temperatures due to their outstanding chemical, thermal durability, and mechanical strength. This paper presents an overview of CO₂ capture approaches and materials. It also elaborates on the research progress of three types of CCDP membranes with distinct permeation mechanisms, concentrating on their principles, materials, and structures. Additionally, several typical membrane reactors, such as the dry reforming of methane (DRM) and reverse water–gas shift (RWGS), are discussed to demonstrate how captured CO₂ can function as a soft oxidant, converting feedstocks into valuable products through oxidation pathways designed within a single reactor. Finally, the future challenges and prospects of high-temperature CCDP membrane technologies and their related reactors are proposed. Full article

The rise of artificial intelligence (AI) necessitates ultra-fast computing, with on-chip terahertz (THz) communication emerging as a key enabler. It offers high bandwidth, low power consumption, dense interconnects, support for multi-core architectures, and 3D circuit integration. However, transitioning between different waveguides remains a major challenge in THz systems. In this paper, we propose a THz band mode converter that converts from a rectangular waveguide (RWG) (WR-0.43) in ${\mathrm{TE}}_{10}$ mode to a substrate-integrated waveguide (SIW) in ${\mathrm{TE}}_{20}$ mode. The converter comprises a tapered waveguide, a widened waveguide, a zigzag antenna, and an aperture coupling slot. The zigzag antenna effectively captures the electromagnetic (EM) energy from the RWG, which is then coupled to the aperture slot. This coupling generates a quasi-slotline mode for the electric field (E-field) along the longitudinal side of the aperture, exhibiting odd symmetry akin to the SIW’s ${\mathrm{TE}}_{20}$ mode. Consequently, the ${\mathrm{TE}}_{20}$ mode is excited in the symmetrical plane of the SIW and propagates transversely. Our work details the mode transition principle through simulations of the EM field distribution and model optimization. A back-to-back RWG ${\mathrm{TE}}_{10}{\mathrm{-to-TE}}_{10}$ mode converter is designed, demonstrating an insertion loss of approximately 5 dB over the wide frequency range band of 2.15–2.36 THz, showing a return loss of 10 dB. An on-chip antenna is proposed which is fed by a single higher-order mode of the SIW, achieving a maximum gain of 4.49 dB. Furthermore, a balun based on the proposed converter is designed, confirming the presence of the ${\mathrm{TE}}_{20}$ mode in the SIW. The proposed mode converter demonstrates its feasibility for integration into a THz-band high-speed circuit due to its efficient mode conversion and compact planar design. Full article

The catalytic conversion of carbon dioxide (CO₂) into carbon monoxide (CO) via the reverse water–gas shift (RWGS) reaction offers a promising pathway toward a sustainable carbon cycle. However, the competing Sabatier reaction presents a significant challenge, underscoring the need for highly efficient catalysts. In this study, we developed a novel catalyst comprising cobalt-oxide-supported nickel-hydroxide nanoparticles (denoted as Co@Ni). This catalyst achieved a remarkable CO production yield of ~5144 μmol g⁻¹ at 573 K, with a CO selectivity of 77%. These values represent 30% and 70% improvements over carbon-supported Ni(OH)₂ (Ni-AC) and CoO (Co-AC) nanoparticles, respectively. Comprehensive physical characterizations and electrochemical analyses reveal that the exceptional CO yield of the Co@Ni catalyst stems from the synergistic electronic interactions between adjacent active sites. Specifically, cobalt-oxide domains act as electron donors to Ni sites, facilitating efficient H₂ splitting. Additionally, the oxygen vacancies in cobalt oxide enhance CO₂ adsorption and promote subsequent dissociation. These findings provide critical insights into the design of highly efficient and selective catalysts for the RWGS reaction, paving the way for advancements in sustainable carbon utilization technologies. Full article

This study examines the factors influencing the formation and structure of ZnPd-ZnO active sites supported on TiO₂ by comparing their genesis from Pd/TiO₂ base catalysts prepared by impregnation using different Pd precursors (Pd(NH₃)₄(NO₃)₂ and Pd(acac)₂). The experimental results demonstrated that, in contrast to the production of CO over Pd/TiO₂ base catalysts, the selectivity of methanol over ZnPd-ZnO/TiO₂ catalysts was significantly affected by the dispersion of ZnPd intermetallic particles and the development of ZnPd-ZnO interfaces. These are determined by the characteristics of Pd particles supported on TiO₂ and their contact with the ZnO particles deposited on them. The Pd/TiO₂ base catalyst prepared by impregnation with neutral Pd precursor (Pd(acac)₂) produces a higher concentration and more effective dispersion of the ZnPd intermetallic phase as well as a wider ZnO-ZnPd interface region in comparison to the Pd/TiO₂ counterpart synthetized using the cationic Pd precursor (Pd(NH₃)₄(NO₃)₂). These differences in the ZnPd-ZnO active sites resulted in notable variations in the methanol yield, achieving the catalysts prepared with the neutral precursor about twice higher methanol selectivity from CO₂ hydrogenation at low temperatures. Full article