Search Results (250)

Calcium aluminate cement (CAC) offers rapid strength development, chemical durability in harsh environments, and high-temperature resistance, but its long-term performance may be compromised by the conversion of metastable hexagonal hydrates into stable cubic phases. Concurrently, recycling spent fluorescent lamp glass (SFLG) is limited because of its residual mercury content. This study investigates the use of manually (MAN) and mechanically (MEC) processed SFLG as partial CAC replacements (up to 50 wt.%). Both SFLG types had irregular morphologies with mean particle sizes of ~20 µm and mercury concentrations of 3140 ± 61 ppb (MAN) and 2133 ± 119 ppb (MEC). Moreover, the addition of SFLG reduced the initial and final setting times, whilst MEC waste notably extended the plastic state duration from 20 min (reference) to 69 min (50 wt.% MEC). Furthermore, strength development was accelerated, with SFLG/CAC mortars reaching peak strengths at 7–10 days versus 28 days as in the CAC reference. CAC and 15 wt.% SFLG mortars showed strength loss over time by reason of their phase conversion, whereas mortars with 25–50 wt.% SFLG experienced significant long-term strength gains, reaching ~60 MPa (25 wt.%) and ~45 MPa (35 wt.%), respectively, after 365 days, with strength activity indexes (SAI) near 90% and 70%, respectively. These improvements are attributed to the formation of strätlingite (C₂ASH₈), which stabilized hexagonal CAH₁₀ and mitigated conversion to cubic katoite (C₃AH₆). Mercury leaching remained below 0.01 mg/kg dry matter for all mixes and curing ages, classifying the mortars as non-hazardous and inert under Spanish Royal Decree 646/2020. The results suggest that SFLG can be safely reused as a sustainable admixture in CAC systems, enhancing long-term mechanical performance while minimizing environmental impact. Full article

Reduced chemical kinetic mechanisms are essential for enabling the use of complex fuels in 3D CFD combustion simulations. This study presents the development and optimization of a compact mechanism capable of accurately modeling ethanol–gasoline blends, including Brazilian Type-C gasoline (27% ethanol by volume) and up to pure ethanol (E100). An initial mechanism was constructed using the Directed Relation Graph with Error Propagation (DRGEP) method applied to detailed mechanisms selected for each surrogate component. The resulting mechanism was then refined through three global iterations of a genetic algorithm targeting ignition delay time (IDT) and laminar flame speed (LFS) performance. Five candidate versions (Mec1 to Mec5), each containing 179 species and 771 reactions, were generated. Mec4 was identified as the optimal configuration based on quantitative error analysis across all tested conditions and blend ratios. The final mechanism offers a balance between predictive accuracy and computational feasibility, making it well-suited for high-fidelity simulations in complex geometries involving multi-component ethanol–gasoline fuels. Full article

In complex urban wireless environments, unmanned aerial vehicle–mobile edge computing (UAV-MEC) systems face challenges like link blockage and single-antenna eavesdropping threats. The traditional single reconfigurable intelligent surface (RIS), limited in collaboration, struggles to address these issues. This paper proposes a double-RIS cooperative UAV-MEC optimization scheme, leveraging their joint reflection to build multi-dimensional signal paths, boosting legitimate link gains while suppressing eavesdropping channels. It considers double-RIS phase shifts, ground user (GU) transmission power, UAV trajectories, resource allocation, and receiving beamforming, aiming to maximize secure energy efficiency (EE) while ensuring long-term stability of GU and UAV task queues. Given random task arrivals and high-dimensional variable coupling, a dynamic model integrating queue stability and secure transmission constraints is built using Lyapunov optimization, transforming long-term stochastic optimization into slot-by-slot deterministic decisions via the drift-plus-penalty method. To handle high-dimensional continuous spaces, an end-to-end proximal policy optimization (PPO) framework is designed for online learning of multi-dimensional resource allocation and direct acquisition of joint optimization strategies. Simulation results show that compared with benchmark schemes (e.g., single RIS, non-cooperative double RIS) and reinforcement learning algorithms (e.g., advantage actor–critic (A2C), deep deterministic policy gradient (DDPG), deep Q-network (DQN)), the proposed scheme achieves significant improvements in secure EE and queue stability, with faster convergence and better optimization effects, fully verifying its superiority and robustness in complex scenarios. Full article

Methicillin-resistant Staphylococcus aureus (MRSA), characterized by high-level β-lactam resistance and increasing multi-drug resistance, poses a severe and growing global threat to human health and public safety. This review examines MRSA’s complex resistance mechanisms, including mecA/mecC-mediated expression of low-affinity PBP2a, regulatory roles of auxiliary genes like fem and vanA, enzymatic inactivation by β-lactamases and modifying enzymes, efflux pump activity, and biofilm formation. We also systematically review novel therapeutic strategies, such as combination therapies, phage-derived biofilm disruptors, membrane-targeting silver nanoparticles, cell-penetrating antimicrobial peptides, colonization-competitive probiotics, and antibiotic-synergizing phytochemicals. These advances provide critical insights for developing effective countermeasures against MRSA, while highlighting the urgent need for global collaboration, antibiotic stewardship, and innovative drug development to combat antimicrobial resistance. Full article

Toxic shock syndrome (TSS) is a serious, often fatal disease, rarely occurring in dogs via infection with Staphylococcus and Streptococcus. The development of TSS is mainly dependent on the presence of bacterial toxins recognized to be potent superantigens causing the release of massive amounts of host inflammatory cytokines, notably TNF-α, progressing to high fever, hypotension, haemoconcentration, thrombosis and neutrophil and endothelial activation with multiple organ failure. Rarely, TSS is associated with erythematous and exfoliative dermatitis progressing to ulceration with extremely extensive dermo-epidermal detachment, which is often very painful. Like in humans, very little is known about the transmission and prevention of this condition. In our paper, a case of TSS-like caused by a mixed bacterial infection with Staphylococcus aureus, Streptococcus halichoeri and Dermatophilus spp. has been described in an 11 year-old, cross-breed male dog, most probably following injury due to biting and fighting. Lesions consisted of severe and diffuse ulceration on the dorsum, and bacterial culture/cytology led to the isolation and identification of Gram-positive staphylococci and streptococci associated with an intense neutrophil reaction. Dermatophilus spp. was presumed morphologically based on cytological preps, not by culture or molecular analysis. PCR demonstrated the presence of the nuc thermonucleaze gene (for S. aureus confirmation) together with the genes encoding enterotoxin H (seh), protein A (spa), toxic shock syndrome toxin TSST-1 (tst) and methicillin resistance (mecC); the exfoliative toxins (eta, etb) were detected. Clinical signs, cytology, bacterial culture and the response to systemic antibiotic therapy were compatible with a TSS-like diagnosis. The patient has completely recovered after 1 year of treatment. Full article

The term chromosomal imprinting was introduced to denote the parent-of-origin-dependent behavior of chromosomes in the fungus gnat originally named Sciara coprophila (current taxonomic name is Bradysia coprophila). Such behavior is observed in Sciara coprophila embryos, where paternal X chromosomes (X_p) are specifically eliminated during the 7th–8th cleavage divisions. Elimination is regulated by a controlling element (CE) that has been mapped to heterochromomere II (H2) within the sub-telomeric short arm of polytene X chromosomes. Here, using a combination of a new Sciara genome assembly, along with ChIP-Seq and MeDIP analyses, we show that a 1.2 Mb region within the CE locus has a repressive epigenetic signature that is characterised by enrichments of H3K9me3, H4K20me3 and 5′-methyl cytosine (5meC). These data provide evidence for a model where the H3K9me3/HP1/H4K20me3 pathway operates to assemble a heterochromatin-like complex at the CE that renders it silent on X_p chromosomes that are not eliminated. In this regard, our findings support the idea that the H3K9me3/HP1/H4K20me3 pathway represents the most evolutionarily conserved mechanism linked to chromosomal imprinting in animals. Full article

To meet the escalating demands of massive data transmission, the next generation of wireless networks will leverage the multi-access edge computing (MEC) architecture coupled with multi-access transmission technologies to enhance communication resource utilization. This paper presents queue stability-constrained reinforcement learning algorithms designed to optimize the transmission control mechanism in MEC systems to improve both throughput and reliability. We propose an analytical framework to model the queue stability. To increase transmission performance while maintaining queue stability, queueing delay model is designed to analyze the packet scheduling process by using the M/M/c queueing model and estimate the expected packet queueing delay. To handle the time-varying network environment, we introduce a queue stability constraint into the reinforcement learning reward function to jointly optimize latency and queue stability. The reinforcement learning algorithm is deployed at the MEC server to reduce the workload of central cloud servers. Simulation results validate that the proposed algorithm effectively controls queueing delay and average queue length while improving packet transmission success rates in dynamic MEC environments. Full article

Staphylococcus saprophyticus (S. saprophyticus) is an opportunistic coagulase-negative staphylococcus (CoNS) known to cause urinary tract infections in humans and is increasingly recognized in veterinary medicine. The aim of this study was to provide an epidemiological characterization of S. saprophyticus strains and to identify potential virulence factors that may contribute to interspecies transmission. This research is particularly important, as companion animals represent an understudied reservoir of this microorganism, and their role in the spread of resistant pathogens remains insufficiently understood. A total of 61 S. saprophyticus strains isolated from humans, dogs, and cats were analyzed. Identification was performed using MALDI-TOF MS and confirmed by PCR targeting the hrcA gene. Antimicrobial susceptibility was assessed using the disk diffusion and broth microdilution methods, while resistance genes were detected by PCR. The blaZ and mecA genes were present in all strains; additionally, the majority harbored the resistance genes ermA, ermB, tetM, and tetK. Multidrug resistance (MDR) was identified in 21/61 strains (34.4%). Biofilm-forming capacity was temperature-dependent, with the strongest biofilm production observed at 37 °C (70.5%). At 38 °C and 39 °C, the proportion of strong biofilm producers decreased to 50.8% and 52.5%, respectively. All tested strains demonstrated pathogenic potential in the Galleria mellonella larvae infection model, with the highest mortality recorded for selected feline and canine strains. These findings indicate that S. saprophyticus strains from both humans and companion animals possess notable virulence and multidrug resistance. The detection of genotypically and phenotypically resistant strains in animals highlights their potential role as reservoir for zoonotic transmission. Full article

Antibiotic resistance and biofilm formation complicate Staphylococcus aureus infections, raising concerns for global health. Understanding antimicrobial resistance and biofilm formation in these pathogens is essential for effective infection management. The current research aimed to assess antibiotic resistance patterns, biofilm formation, and the occurrence of integron classes 1, 2, and 3 in clinical S. aureus isolates. The disc diffusion method tested antibiotic susceptibility. MRSA strains were identified by cefoxitin disc diffusion, and the mecA gene by PCR. The D-test also assessed macrolide–lincosamide–streptogramin B. A microtiter plate assay assessed biofilm formation. By PCR, integron classes were examined. Of the 63 S. aureus isolates, 25 were MSSA and 38 were MRSA. Pus (39.5%) was the most prevalent clinical source of MRSA isolates, while blood (24%) was the predominant source of MSSA isolates. MRSA isolates were more resistant to clindamycin, ciprofloxacin, ofloxacin, levofloxacin, tetracycline, and doxycycline than MSSA isolates. In total, 76.2% of the isolates produced biofilm. Biofilm-producing isolates were more resistant to cefoxitin and clindamycin. The isolates had 33.3% cMLSB resistance. The intI1 gene was found in 21 S. aureus isolates (33.3%), whereas the intI2 or intI3 genes were not detected. Our findings demonstrate the need for strict infection control to prevent the spread of resistant bacteria. Full article

A series of para-trifluoromethoxy-substituted and fluorobenzhydryl-functionalized 1,2-bis(imine)acenaphthene ligands: 1-[2,6-{(4-F-C₆H₄)₂CH}₂-4-F₃COC₆H₂N]-2-(ArN)C₂C₁₀H₆ (Ar = 2,6-Me₂C₆H₃ L1, 2,6-Et₂C₆H₃ L2, 2,6-iPr₂C₆H₃ L3, 2,4,6-Me₃C₆H₂ L4, 2,6-Et₂-4-MeC₆H₂ L5), were synthesized and used to generate their corresponding nickel(II) bromide complexes (Ni1–Ni5). Elemental analysis, ¹⁹F NMR, and FT-IR spectroscopy were employed to characterize these five nickel complexes. Single-crystal X-ray diffraction of Ni2 and Ni4 confirmed distorted tetrahedral geometries. Upon activation with either EtAlCl₂ (ethylaluminum dichloride) or EASC (ethyl aluminum sesquichloride), these complexes showed exceptional high activities (up to 22.0 × 10⁶ g PE mol⁻¹ (Ni) h⁻¹) and remarkable thermal stability (4.82 × 10⁶ g PE mol⁻¹(Ni) h⁻¹ at 80 °C) towards ethylene polymerization. The resulting polyethylenes are highly branched, with the type and extent of branches tunable by temperature, solvent, and co-catalyst choice. Moreover, these polymers demonstrated excellent tensile strength (σ_b up to 20.7 MPa) and elastic recovery (up to 58%), characteristic of thermoplastic elastomers (TPEs). These results highlight the dual role of trifluoromethoxy and fluorobenzhydryl groups in enhancing catalytic performance and polymer properties. Full article

Background/Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) represent important antimicrobial resistance threats related to companion animals, which can directly or indirectly lead to adverse health effects in humans and animals living in close contact. Characterizing the phenotypic resistance of MRSA and MRSP to a panel of antimicrobials relevant to both veterinary and human medicine is crucial within a “One Health” framework. Methods: In this study, a total of 79 presumptive MRSA isolates (34 from cats, 45 from dogs) and 110 presumptive MRSP isolates (105 from dogs, 5 from cats) from clinical cases were analysed. Real-time PCR was used to detect the presence of mecA and mecC genes, and susceptibility testing was performed using the Sensititre EUST2 panel. Results: Most of the isolates (88.9%, 168/189) were positive for the mecA gene, while a minority (1.1%, 2/189) were mecC-positive (2 MRSA, 1 dog, 1 cat). MRSP isolates exhibited acquired resistance to a broader range of antibiotics compared to MRSA strains. Furthermore, several isolates demonstrated acquired resistance to antibiotics considered critically important for human medicine. Resistance to vancomycin was found in an MRSP isolate from a dog, and resistance to linezolid in an MRSP isolate from a cat. This study reveals that 83.3% (30/36) of MRSA isolates from dogs and 89.3% (25/28) from cats were multidrug-resistant organisms, while MRSP isolates exhibited multidrug resistance in 99% (101/102) of cases for dogs and 100% (4/4) for cats. Conclusions: The extremely high level of multidrug resistance, with some isolates resistant to critically important antibiotics used in human medicine, highlight the importance of monitoring antimicrobial susceptibility in MRSA and MRSP isolates collected from cats and dogs in a One Health perspective. Full article

Blast furnace slag, a high-temperature molten by-product generated during the ironmaking process in the metallurgical industry, has garnered significant attention for its resource utilization technologies. Compared to the traditional water-quenching method, dry granulation offers notable advantages. This paper systematically compares and analyzes the performance parameters of three typical dry treatment processes: mechanical crushing, air-quenching granulation, and centrifugal granulation. It reveals that the centrifugal granulation process demonstrates substantial technical superiority in key metrics, such as particle size distribution uniformity, particle morphology optimization, and heat recovery efficiency. Building on this, this study provides a comprehensive review of the current state of centrifugal granulation technology, from both experimental and simulation perspectives. Additionally, the combined processes of centrifugal granulation and air quenching can fully exploit the synergistic benefits of each technology, thereby enhancing overall efficiency. However, the wind’s cooling effect can lead to the premature solidification of molten slag when it splits into liquid filaments, resulting in slag wool. To address this, this paper proposes a centrifugal granulation device equipped with a windbreak board, which facilitates temperature zoning. This approach prevents premature solidification in the liquid filament region while ensuring the timely cooling and solidification of slag particles, offering a novel technical solution for optimizing centrifugal granulation in metallurgical solid waste resource utilization. Full article

Three diaryliodonium dicyanoargentates(I), [MesIAr][Ag(CN)₂] (Ar = Ph 1, Mes 2, 4-MeC₆H₄ 3; Mes = 2,4,6-Me₃C₆H₂), were prepared by anion metathesis. The X-ray structural analyses for these crystals revealed C–I^III∙∙∙N≡C halogen bonds (abbreviated as XB) between I atoms of diaryliodonium cations and N atoms of cyano groups, which provide different supramolecular organization. The noncovalent nature of these interactions was studied by density functional theory (DFT) calculations and topological analysis of the electron density distribution in the framework of the quantum theory of atoms in molecules (QTAIM) at the PBE-D3/jorge-DZP-DKH level of theory both in gas phase and crystal models. The philicities of partners in these contacts were confirmed by electron localization function (ELF) projections, electron density/electrostatic potential (ED/ESP) profiles, and Hirshfeld surfaces analysis. An analysis of the available crystallographic data from the literature allows us to find other examples of σ-hole interactions including the dicyanoargentate(I) anion, and the C–X∙∙∙N≡C (X = Br, I, Te) bonding were also confirmed theoretically. Full article

Mobile edge computing (MEC) systems empowered by energy harvesting (EH) significantly enhance sustainable computing capabilities for mobile devices (MDs). This paper investigates a multi-user multi-server MEC network, in which energy-constrained users dynamically harvest ambient energy to flexibly allocate resources among local computation, task offloading, or intentional task discarding. We formulate a stochastic optimization problem aiming to minimize the time-averaged weighted sum of execution delay, energy consumption, and task discard penalty. To address the energy causality constraints and temporal coupling effects, we develop a Lyapunov optimization-based drift-plus-penalty framework that decomposes the long-term optimization into sequential per-time-slot subproblems. Furthermore, to overcome the curse of dimensionality in high-dimensional action, we propose hierarchical deep reinforcement learning (DRL) solutions incorporating both Q-learning with experience replay and asynchronous advantage actor–critic (A3C) architectures. Extensive simulations demonstrate that our DRL-driven approach achieves lower costs compared with conventional model predictive control methods, while maintaining robust performance under stochastic energy arrivals and channel variations. Full article

Hydrogen energy has emerged as a pivotal clean energy solution due to its sustainability and zero-emission potential. Microbial electrolysis cells are a promising technology for renewable hydrogen production, typically relying on expensive and unstable Pt/C catalysts for the hydrogen evolution reaction (HER). To address these limitations, this study develops a cost-effective and durable alternative approach. A cobalt–molybdenum (Co-Mo) alloy catalyst (denoted as CoMo/SS) was synthesized via a one-step electrodeposition method on 1000-mesh 316L stainless steel at a current density of 30 mA·cm⁻² for 80 min, using an electrolyte with a Co-to-Mo ratio of 1:1. The electrochemical properties and hydrogen evolution performance of this catalyst in a microbial electrolysis cell were evaluated. Key results demonstrate that the CoMo/SS catalyst achieves a good catalytic performance of hydrogen evolution. The CoMo/SS cathode catalyst only requires an overpotential of 91.70 mV (vs. RHE) to reach a current density of 10 mA·cm⁻² in 1 mol·L⁻¹ KOH, with favorable kinetics, evidenced by a reduced Tafel slope of 104.10 mV·dec⁻¹, enhanced charge transfer with a charge transfer resistance of 4.56 Ω, and a double-layer capacitance of 34.73 mF·cm⁻². Under an applied voltage of 0.90 V, the CoMo/SS cathode exhibited a hydrogen production rate of 1.12 m³·m⁻³·d⁻¹, representing a 33.33% improvement over bare SS mesh. This performance highlights the catalyst’s potential as a viable Pt/C substitute for scalable MEC applications. Full article