Search Results (8)

Introduction: Stenotrophomonas maltophilia (S. maltophilia) has emerged as an important opportunistic pathogen. It is resistant to most available antibiotics due to its intrinsic resistance, leaving only some antibacterial agents as possible therapeutic options, which is further complicated by acquired mechanisms of antimicrobial resistance. This study aimed to provide a comprehensive genomic characterization of clinical S. maltophilia complex (Smc) isolates, focusing on molecular characterization of its resistance and virulence, since studies tackling this are scarce in Oman. Methods: This study is a prospective cross-sectional study, in which a total of 21 clinical isolates of Smc were collected from different clinical samples and further characterized using Whole Genome Sequencing. Results: Besides S. maltophilia, the isolates included S. hibiscicola, S. pavanii, and S. muris for the first time in Oman. All isolates were found to be susceptible to cefiderocol, levofloxacin, and minocycline. Sequence types (STs) were diverse among the isolates, with more than half of the isolates showing new STs with novel alleles. Additionally, blaOXA-2, sul1, and the recently described aac(6′)-Iap and aph(9)-Ic were detected among the isolates. Moreover, virulence-associated genes (smf-1, pilT, pilQ, gpmA, rmlA, spgM, stmPr1, plcN, clpP, and katE) were highly conserved across all isolates. Mobile genetic elements were detected in most of the isolates (76.20%). Conclusions: The collected isolates showed high ST diversity and showed no specific pattern in terms of antibiotic susceptibility and resistance genes. More studies are needed to establish relationships between the different members of the Smc and the different molecular resistome and virulome. Full article

Asymmetric Cascaded Multilevel Inverters (ACMLIs) have emerged as a prominent solution for medium- and high-power applications due to their ability to provide an increased number of output voltage levels with fewer power switches. However, maintaining low total harmonic distortion (THD) and ensuring robust stability under varying operating conditions remain significant challenges. This study experimentally validates a voltage-feedback Proportional-Resonant (PR) control strategy for a seven-level ACMLI. Unlike conventional current-feedback methods, the proposed approach directly regulates the output voltage, providing superior harmonic suppression and enhanced steady-state accuracy. The stability and dynamic performance of the controller were theoretically analyzed using Bode diagrams and root locus methods, and further verified through the MATLAB Curve Fitting Tool (CFT) with a high correlation (R² = 0.9989). Experimental results demonstrate that the integration of the PR controller significantly improves power quality, reducing the current THD from 6.55% to 3.68% and the voltage THD to 2.94%. These findings confirm that the system fully complies with IEEE 519 standards and outperforms several existing strategies in the literature. The results establish the voltage-feedback PR control as a robust, high-precision, and practical alternative for power quality-oriented multilevel inverter applications in modern energy systems. Full article

Spontaneous combustion in goaf areas poses a significant threat to coal mine safety. Traditional safety management systems, reliant on passive response and single-indicator thresholds, often suffer from delayed warnings and lack cognitive decision support. To address this challenge, this study proposes a big-data-driven cognitive computing framework for dynamic risk prediction of goaf spontaneous combustion, based on a “Cloud-Edge-End” collaborative architecture. The method leverages multi-sensor big data streams (CO, C₂H₄, O₂, etc.) and deploys a lightweight Radial Basis Function (RBF) neural network on underground edge computing nodes (STM32) for real-time analytics. The model demonstrates excellent predictive performance on imbalanced datasets, with a PR-AUC of 0.910 and a recall of 99.7%. The edge-deployed RBF model achieves a single-pass inference time of only 0.62 ms, enabling real-time cognitive risk mapping. Field application at Z Coal Mine validated the system’s effectiveness, providing an average pre-warning time of 48.5 h, achieving zero spontaneous combustion accidents, and reducing the Total Recordable Injury Rate (TRIR) by 15.2%. This work illustrates how edge-based cognitive computing can transform safety management from passive response to proactive prevention, offering a scalable and interpretable framework for intelligent mine safety. Full article

Neuroinflammatory diseases, such as Alzheimer’s disease (AD) and traumatic brain injury (TBI), are associated with the extravascular deposition of the fibrinogen (Fg) derivative fibrin and are accompanied with memory impairment. We found that during the hyperfibrinogenemia that typically occurs during AD and TBI, extravasated Fg was associated with amyloid beta and astrocytic cellular prion protein (PrP^C). These effects coincided with short-term memory (STM) reduction and neurodegeneration. However, the mechanisms of a direct Fg–neuron interaction and its functional role in neurodegeneration are still unclear. Cultured mouse brain neurons were treated with Fg in the presence or absence of function-blockers of its receptors, PrP^C or intercellular adhesion molecule-1 (ICAM-1). Associations of Fg with neuronal PrP^C and ICAM-1 were characterized. The expression of proinflammatory marker interleukin 6 (IL-6) and the generation of reactive oxygen species (ROS), mitochondrial superoxide, and nitrite in neurons were assessed. Fg-induced neuronal death was also evaluated. A strong association of Fg with neuronal PrP^C and ICAM-1, accompanied with overexpression of IL-6 and enhanced generation of ROS, mitochondrial superoxide, and nitrite as well as the resulting neuronal death, was found. These effects were reduced by blocking the function of neuronal PrP^C and ICAM-1, suggesting that the direct interaction of Fg with its neuronal receptors can induce overexpression of IL-6 and increase the generation of ROS, nitrite, and mitochondrial superoxide, ultimately leading to neuronal death. These effects can be a mechanism of neurodegeneration and the resultant memory reduction seen during TBI and AD. Full article

The low-temperature scanning tunneling microscope and spectroscopy (STM/STS) are used to visualize superconducting states in the cleaved single crystal of 9% praseodymium-doped CaFe₂As₂ (Pr-Ca122) with T_c ≈ 30 K. The spectroscopy shows strong spatial variations in the density of states (DOS), and the superconducting map constructed from spectroscopy discloses a localized superconducting phase, as small as a single unit cell. The comparison of the spectra taken at 4.2 K and 22 K (below vs. close to the bulk superconducting transition temperature) from the exact same area confirms the superconducting behavior. Nanoscale superconducting states have been found near Pr dopants, which can be identified using dI/dV conductance maps at +300 mV. There is no correlation of the local superconductivity to the surface reconstruction domain and surface defects, which reflects its intrinsic bulk behavior. We, therefore, suggest that the local strain of Pr dopants is competing with defects induced local magnetic moments; this competition is responsible for the local superconducting states observed in this Fe-based filamentary superconductor. Full article

Many neuroinflammatory diseases, like traumatic brain injury (TBI), are associated with an elevated level of fibrinogen and short-term memory (STM) impairment. We found that during TBI, extravasated fibrinogen deposited in vasculo-astrocyte interfaces, which was associated with neurodegeneration and STM reduction. The mechanisms of this fibrinogen-astrocyte interaction and its functional role in neurodegeneration are still unclear. Cultured mouse brain astrocytes were treated with fibrinogen in the presence or absence of function-blocking antibody or peptide against its astrocyte receptors intercellular adhesion molecule-1 (ICAM-1) or cellular prion protein (PrP^C), respectively. Fibrinogen interactions with astrocytic ICAM-1 and PrP^C were characterized. The expression of pro-inflammatory markers, generations of reactive oxygen species (ROS) and nitric oxide (NO) in astrocytes, and neuronal death caused by astrocyte-conditioned medium were assessed. Data showed a strong association between fibrinogen and astrocytic ICAM-1 or PrP^C, overexpression of pro-inflammatory cytokines and overproduction of ROS and NO, resulting in neuronal apoptosis and death. These effects were reduced by blocking the function of astrocytic ICAM-1 and PrP^C, suggesting that fibrinogen association with its astrocytic receptors induce the release of pro-inflammatory cytokines, resulting in oxidative stress, and ultimately neuronal death. This can be a mechanism of neurodegeneration and the resultant STM reduction seen during TBI. Full article

Stenotrophomonas maltophilia, an environmental Gram-negative bacterium, is an emerging nosocomial opportunistic pathogen that causes life-threatening infections in immunocompromised patients and chronic pulmonary infections in cystic fibrosis patients. Due to increasing resistance to multiple classes of antibiotics, S. maltophilia infections are difficult to treat successfully. This makes the search for new antimicrobial strategies mandatory. In this study, the antibacterial activity of the heterocyclic corticosteroid deflazacort and several of its synthetic precursors was tested against S. maltophilia. All compounds were not active against standard strain S. maltophilia K279a. The compound PYED-1 (pregnadiene-11-hydroxy-16α,17α-epoxy-3,20-dione-1) showed a weak effect against some S. maltophilia clinical isolates, but exhibited a synergistic effect with aminoglycosides. PYED-1 at sub-inhibitory concentrations decreased S. maltophilia biofilm formation. Quantitative real-time polymerase chain reaction (RT-qPCR) analysis demonstrated that the expression of biofilm- and virulence- associated genes (StmPr1, StmPr3, sphB, smeZ, bfmA, fsnR) was significantly suppressed after PYED-1 treatment. Interestingly, PYED-1 also repressed the expression of the genes aph (3′)-IIc, aac (6′)-Iz, and smeZ, involved in the resistance to aminoglycosides. Full article

Stenotrophomonas maltophilia is an emerging global opportunistic pathogen that has been appearing with increasing prevalence in cystic fibrosis (CF). A secreted protease from S. maltophilia has been reported as its chief potential virulence factor. Here, using the reference clinical strain S. maltophilia K279a, the major secreted proteases were identified. Protein biochemistry and mass spectrometry were carried out on K279a culture supernatant. The effect of K279a culture supernatant on cleavage and anti-neutrophil elastase activity of the three majors pulmonary antiproteases was quantified. A deletion mutant of S. maltophilia lacking expression of a protease was constructed. The serine proteases StmPR1, StmPR2 and StmPR3, in addition to chitinase A and an outer membrane esterase were identified in culture supernatants. Protease activity was incompletely abrogated in a K279a-ΔStmPR1: Erm mutant. Wild type K279a culture supernatant degraded alpha-1 antitrypsin (AAT), secretory leucoprotease inhibitor (SLPI) and elafin, important components of the lung’s innate immune defences. Meanwhile SLPI and elafin, but not AAT, retained their ability to inhibit neutrophil elastase. StmPR3 together with StmPR1 and StmPR2, is likely to contribute to protease-mediated innate immune dysfunction in CF. Full article