Search Results (5,033)

The load transfer mechanism of piles in karst cavity areas was investigated through field tests, and an orthogonal test was carried out to establish a calculation method for negative skin friction induced by backfilling. The results indicate that the negative skin friction of piles is strongly influenced by the type of cavity. When cavities were completely filled with limestone breccia mixed with silty clay and the applied load reached 3628 kN, the unit side friction ranged from 15 to 22 kPa. In contrast, when cavities remained unfilled, soil settlement occurred around the pile after backfilling, leading to the development of negative skin friction. For cavities with heights of 3–12 m, it is recommended that the bearing capacity of piles be calculated by considering negative skin friction at depths of 0H, 0.106H, 0.214H, and 0.271H (where H denotes the cavity height). Based on 21 orthogonal tests, the sensitivity ranking of factors affecting negative skin friction was determined as follows: cavity height > elastic modulus of backfill > pile diameter > cavity span > pile length > cavity position. The calculated values of negative skin friction were further validated against engineering data, showing a variation trend consistent with the test results, with a relative error of only 7.4%. Full article

An efficient cooling configuration is critical for ensuring the safe operation of electrical machines and is key for optimizing the iterative design of motors. To improve the heat dissipation performance of high-power, explosion-proof, integrated variable-frequency permanent magnet motors used in mining and reduce the risk of permanent magnet demagnetization, this study considers a 1600 kW mining explosion-proof variable-frequency permanent magnet motor as its research object. Based on the zigzag-type water channel structure of the frame, a novel rotor-cooling scheme integrating axial–radial ventilation structures and axial flow fans was proposed. The temperature field of the motor was simulated and analyzed using a fluid–thermal coupling method. Under rated operating conditions, the flow characteristics of the frame water channel and the temperature distribution law inside the motor were compared when the water supply flow rates were 5.4, 4.8, 4.2, 3.6, 3, 2.4, and 1.8 m³/h, respectively, and the relationship between the motor temperature rise and the variation in water flow rate was revealed. A production prototype was developed, and temperature rise tests were conducted for verification. The test results were in good agreement with the simulation calculation results, thereby confirming the accuracy of the simulation calculation method. The results provide an important reference for enterprises in the design optimization and upgrading of high-power explosion-proof integrated variable-frequency permanent-magnet motors. Full article

Background: The emergence of pan-drug-resistant (PDR) Klebsiella pneumoniae has compromised the efficacy of last-line agents, leaving few therapeutic options. Repurposing zidovudine, an FDA-approved thymidine analog with antibacterial activity, may enhance existing therapies, but pharmacodynamic data under clinically relevant conditions are scarce. This study addresses this gap using static and dynamic in vitro models. Materials/methods: A PDR strain of Klebsiella pneumoniae harboring bla_NDM-1, bla_CMY-6, bla_CTX-M-15, bla_SHV-2, and disrupted mgrB was used in this study. Minimum inhibitory concentrations (MICs) followed by static time-kills were performed to investigate the synergistic interplay between zidovudine and last-line antibiotics (ceftazidime/avibactam, polymyxin B). To simulate human pharmacokinetics, a hollow-fiber infection model (HFIM) was employed using steady-state concentrations of zidovudine (4 mg/L), polymyxin B (4 mg/L), and avibactam (22 mg/L). Structural and morphological effects on bacterial cells were examined via fluorescence microscopy following glutaraldehyde fixation. Results: In this study, the PDR K. pneumoniae showed a ~5-fold reduction in polymyxin MIC when combined with zidovudine (from >4 µg/mL to 0.25 µg/mL). Time-kill assays demonstrated ≥2.5 log₁₀ CFU/mL bacterial reduction with zidovudine-based combinations, whereas monotherapies failed to inhibit bacterial growth. In the HFIM, the triple combination achieved rapid bactericidal activity (>3 log₁₀ CFU/mL reduction within 4 h) and sustained killing (>5–6 log₁₀ reduction maintained through 216 h), with bacterial counts remaining below 1 CFU/mL. In contrast, dual combinations initially reduced bacterial burden (1–3 log₁₀ reduction) but failed to maintain suppression, with significant regrowth (>10¹⁰ CFU/mL) observed by 168 h. Microscopy corroborated these findings, revealing extensive cellular damage in the zidovudine-containing treatment arms. These HFIM results underscore the potential of zidovudine-based triple therapy in overcoming resistance to last-line antibiotics in K. pneumoniae. Conclusions: Our results provide promising unprecedented insight into novel zidovudine-based combination therapies against difficult-to-treat MBL Gram-negatives. The observed synergy in MIC reduction, rapid killing in time-kill assays, and near-complete eradication in the HFIM underscore the therapeutic potential of this triple combination. Future studies will focus on broadening the application of these novel combinations to other ‘superbugs’, such as highly resistant strains of Acinetobacter baumannii and Pseudomonas aeruginosa. Full article

Fungal laccases oxidize a wide range of substrates with a diverse spectrum of subsequent non-specific free radical reactions, leading to the production of unwanted byproducts. This work describes a unique recombinant alkaliphilic laccase from Paramyrothecium roridum VKM F-3565 capable of performing specific oligomerization of phenylpropanoids (precursors of natural lignin and lignans) in a neutral environment, thus preventing the reverse reaction of depolymerization which occurs in an acidic environment. The recombinant alkaliphilic laccase from P. roridum VKM F-3565 with a specific enzyme activity of about 154.0 U/mg (in the reaction with 1 mM ABTS) was obtained using a Komagataella phaffii transformant with a yield of 20 ± 1.5 mg/L. The recombinant laccase had an increased degree of N-glycosylation (MW = 97 kDa), higher pH optimum in reaction with phenylpropanoids and a decreased temperature optimum, compared to the wild-type laccase. The enzyme exhibited great resistance to surfactants and the EDTA in the neutral conditions rather than the acidic ones, whereas its tolerance to mono- and divalent-metal ions was high at acidic conditions. This work demonstrates the important role of N-glycosylation of the alkaliphilic laccase of P. roridum VKM F-3565 in its functional activity. The presence of pH-dependent reactions makes the studied laccase attractive for the phenylpropanoid oligomerization with the production of novel oligomeric phenylpropanoid derivatives for industrial and pharmacological purposes. Full article

In Abidjan, the treatment of pig waste is becoming a priority given the continued growth of pig farms, which readily reuse manure as organic fertilizer. This study evaluated the effectiveness of anaerobic digestion for simultaneous biogas production and pathogen reduction from pig farm residues. Two 1600 L biodigesters were installed at pig farms in Port Bouët (PBk) and Abobo (Ab). They were fed with pig manure and water (1:4 ratio) and monitored over 56 days. The total biogas production was 22.63 m³ and 16.31 m³ for the PBk and Ab digesters, respectively, with peak production occurring between days 14 and 28. Following biofilter treatment, the methane content increased to 80–82%, yielding potential energy outputs of 2.32–3.29 kWh/d, with optimal production occurring at a pH of 7.28–7.76. The COD, BOD₅, organic acid, and total nitrogen levels decreased progressively in the biodigesters, while the mineral element content remained almost unchanged. Complete elimination was achieved for most of the bacteria tested (E. coli, Enterococcus, Salmonella, etc.). However, Bacillus and Clostridium were able to persist, albeit with significant reductions of between 3.11 and 5.79 log₁₀. Anaerobic digestion is an effective method of combining waste treatment and energy recovery. It eliminates major pathogens while producing valuable biogas. This makes it a sustainable waste management solution for urban agricultural systems. Full article

The integration of high-pressure grinding roller (HPGR) with pre-concentration techniques and stirred mills is recognized for its energy efficiency. Studies have suggested that the feed with a P₈₀ around 1 mm is acceptable for stirred mills or coarse particle flotation. Nonetheless, published experimental data characterizing the comminution behavior of single-stage HPGR circuits configured with a 1 mm screen aperture remain scarce. Moreover, extant research remains confined to laboratory scale. Consequently, critical performance metrics, including production capacity, screening efficiency, and process continuity, have not been substantively documented in the literature. In this paper, the HPGR performance in an industrial-scale HPGR/tower mill comminution circuit was assessed and optimized by laboratory and industrial tests. The research meticulously analyzed the impact of feed rate on the industrial-scale flip-flow screen and HPGR performance and found that the HPGR featuring two studded rolls with a diameter of 800 mm and a width of 400 mm, operating in a reverse classification circuit with a scalped feed by a 14.64 m² flip-flow screen while running continuously 24 h per day, is capable of producing a −1 mm comminution product suitable for tower mill feed. Under the optimal operating conditions identified, it achieved a specific energy consumption of 4.57 kWh/t with a feed rate of 27.08 t/h. Full article

This study reports on the synthesis, structural characterization and gas sorption studies of a homometallic 2D Cd²⁺ MOF and two heterometallic 3D Cd²⁺/Ca²⁺ and Cd²⁺/Sr²⁺ -MOFs based on the angular tetracarboxylic ligand 3,3′,4,4′-sulfonyltetracarboxylic acid (H₄STBA). The homometallic 2D Cd²⁺ MOF with the formula [NH₂(CH₃)₂]⁺₂[Cd(STBA)]²⁻_n·nDMF·1.5nH₂O—(1)_n·nDMF·1.5nH₂O was synthesized from the reaction of CdCl₂·H₂O and 3,3′,4,4′-diphthalic sulfonyl dianhydride (3,3′,4,4′-DPSDA) with stoichiometric ratio of 1:1.3 in DMF/H₂O (5/2 mL) at 100 °C. The two heterometallic Cd²⁺/Ca²⁺ and Cd²⁺/Sr²⁺ compounds were prepared from analogous reactions to this afforded (1)_n·nDMF·1.5nH₂O with the difference that the reaction mixture also contained AE(NO₃)₂ (AE²⁺ = Ca²⁺ or Sr²⁺) and, in particular, from the reaction of AE(NO₃)₂, CdCl₂·H₂O and 3,3′,4,4′-DPSDA with stoichiometric ratio 1:1.1:1.4 in DMF/H₂O (5/2 mL) at 100 °C. Notably, compounds [CdCa(STBA)(H₂O)₂]_n·0.5nDMF—(2)_n·0.5nDMF and [CdSr(STBA)(H₂O)₂]_n·0.5nDMF—(3)_n·0.5nDMF are the first heterometallic compounds Mⁿ⁺/AE²⁺ (M = any metal ion) reported containing ligand H₄STBA. The structure of (1)_n·nDMF·1.5nH₂O comprises a 2D network based on helical 1D chain secondary building unit (SBU) [Cd²⁺(STBA)⁴⁻)]²⁻. The 2D sheets are linked through hydrogen bonding interactions, giving rise to a pseudo-3D structure. On the other hand, compounds (2)_n·1.5nH₂O and (3)_n·1.5nH₂O display 3D microporous structures consisting of a helical 1D chain SBU [Cd²⁺AE²⁺(STBA)⁴⁻)]. All three compounds contain rhombic channels along c axes. The three MOFs exhibit an appreciable thermal stability, up to 350–400 °C. Gas sorption measurements on activated materials (2)_n and (3)_n revealed moderate BET surface areas of 370 m²/g and 343 m²/g, respectively, along with CO₂ uptake capacity of 2.58 mmol/g at 273 K. Full article

The study presents the potential of milkfish frame, a by-product of milkfish processing, as a source of dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant peptides with potential applications in type 2 diabetes management. Proteomic analysis identified key proteins, including 65 kDa warm temperature acclimation protein 1 and myosin heavy chain. In silico prediction (BIOPEP-UWM) guided the selection of proteases for generating DPP-IV inhibitory peptides. Enzymatic hydrolysates were produced and evaluated for bioactivity. Among the treatments, pepsin hydrolysis (2% v/v, 8 h) yielded the highest peptide content (283.64 mg/g), soluble protein (86.46%), and DPP-IV inhibitory activity (68.47%). The resulting milkfish frame pepsin hydrolysate (MFH) was further enhanced through ultrafiltration and simulated gastrointestinal digestion, which improved the DPP-IV inhibitory and antioxidant capacities. Cytotoxicity assays confirmed that MFH (0–100 μg/mL) was non-toxic to FL83B hepatocytes after 24 h. Moreover, treating TNF-α-induced FL83B cells with 10 μg/mL MFHs improved cell viability, reducing the toxicity induced by TNF-α in cells. These findings show that MFHs exhibit promising antidiabetic potential and could serve as natural alternatives to synthetic drugs for type 2 diabetes management. This also demonstrates the valorization of fish processing by-products into functional food ingredients, advancing sustainable approaches in food innovation. Full article

This study investigates the air filtration capabilities of fibrous membranes fabricated via electrospinning, with a focus on optimizing processing parameters. Specifically, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a well-characterized biodegradable polyester, was electrospun to produce membranes exhibiting precisely controlled surface microstructures. The optimal fiber morphology was attained under conditions of a 20 kV applied electric field, a solution flow rate of 0.5 mL·h⁻¹, a polymer concentration of 13 wt.%, and a needle inner diameter of 0.21 mm. The microstructural features of the electrospun PHBV membranes were characterized using scanning electron microscopy (SEM). Complementary analysis via ¹³C nuclear magnetic resonance (NMR) spectroscopy confirmed that the membranes comprised pure 3-hydroxyvalerate (3HV) copolymerized with 3-hydroxybutyrate (3HB) terminal units, with 3HV mole fractions ranging from 17% to 50%. The incorporation of different molar percentages of 3HV in PHBV membrane significantly enhances its durability, as evidenced by Ball Burst Strength (BBS) measurements, with an elongation at burst that is 65–86% greater than that of ASTM F2100 level 3 mask. The nanofibrous membranes exhibited a controlled pore size distribution, indicating their potential suitability for air filtration applications. Particle filtration efficiency (PFE) assessments under standard atmospheric pressure conditions showed that the optimized electrospun PHBV membranes achieved filtration efficiencies exceeding 98%. Additionally, the influence of 3HV content on biodegradation behavior was evaluated through soil burial tests conducted over 90 days. Results indicated that membranes with lower 3HV content (17 mol.%) experienced the greatest weight loss, suggesting accelerated degradation in natural soil environments. Full article

Integration of renewable energy into modern power grids remains limited by intermittency and the need for reliable energy storage. Redox flow batteries (RFBs) are promising for large-scale energy storage, yet their widespread adoption is hindered by the high cost. In this study, we investigate isopropanol as a redox-active species with Pt-Cu alloy electrocatalysts for aqueous-organic RFBs. A series of Pt_xCu catalysts with varying Pt:Cu ratios were synthesized and studied for isopropanol electro-oxidation reaction (IPAOR) performance. Among them, PtCu demonstrated the best performance, achieving a low activation energy of 14.4 kJ/mol at 0.45 V vs. RHE and excellent stability at 1 M isopropanol (IPA) concentration. Kinetic analysis and in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy revealed significantly reduced acetone accumulation on PtCu compared to pure Pt, indicating enhanced resistance to catalyst poisoning. Density functional theory (DFT) calculations further identified the first proton-coupled electron transfer (PCET) as the rate-determining step (RDS) with C-H bond scission as the preferred pathway on PtCu. A proof-of-concept PtCu-catalyzed H-cell demonstrated stable cycling over 200 cycles, validating the feasibility of IPA as a low-cost, regenerable redox couple. These findings highlight PtCu-catalyzed IPA/acetone(ACE) chemistry as a promising platform for next-generation aqueous-organic RFBs. Full article

 The strengthening technique by external cable prestressing, until now limited to columns with circular hollow sections (CHSs), is here extended to H-shaped steel columns. To provide an innovative general treatment, an initial imperfection, obtained from the analytical equivalence between Eurocode 3 and Ayrton–Perry formulations, is introduced. By this, a geometrically and materially nonlinear imperfection analysis (GMNIA) is performed by the finite element commercial code Abaqus. A parametric analysis identifies the deviator length, cable tension, and slenderness ratio as key parameters. Results confirm that, on the one hand, cable prestressing yields a critical load that is approximately twice that for non-prestressed elements (680 kN against 340 kN for a beam 8 m long); this effect grows with the column length. On the other hand, a simulation on a two-story frame supported by 12 columns, each 4 m long, spaced by 4 and 6 m in the two directions, under vertical ‘dead’ load shows that prestressed HEA200 columns perform as non-prestressed larger HEA220 profiles; thus, their use in this case leads to saving approximately 1.18 tons of steel; both these results are of practical interest in design of steel structures. Full article

The utilization of carbon dioxide (CO₂) offers an effective approach for alleviating the carbon-reduction pressures associated with fossil energy consumption. However, studies on the use of CO₂ as an auxiliary agent in water treatment to enhance the removal of emerging contaminants are limited. In this study, the photodegradation of ciprofloxacin (CIP) was investigated using ultraviolet (UV) irradiation combined with CO₂ dosing (UV/CO₂). The results demonstrated that the UV/CO₂ system effectively degraded CIP, with CO₂ concentration and solution pH exerting a critical influence. Inorganic anions and metal cations had negligible effects on CIP degradation efficiency, whereas natural organic matter (NOM) had a pronounced inhibitory effect. Mechanistic analysis revealed that superoxide radicals ($·{\mathrm{O}}_2^{-}$) and carbonate radicals (${\mathrm{CO}}_3^{•-}$) were the primary oxidizing species, whereas the excited triplet state of CIP (³CIP*) and singlet oxygen played crucial roles in initiating radical generation. LC–MS analysis and density functional theory calculations indicated that the main degradation routes involved defluorination, decarboxylation, and epoxidation of the piperazine ring. Toxicity assessment indicated that the transformation products generated by UV/CO₂ were less toxic than the parent compound. Furthermore, the UV/CO₂ process demonstrated high energy efficiency, with a low electrical energy per order (EEO) value of 0.4193 kWh·m⁻³·order⁻¹. These findings suggest that the UV/CO₂ system is a promising alternative for the treatment of photosensitive organic pollutants and provides a beneficial pathway for CO₂ utilization. Full article

Deep learning models for atmospheric pattern recognition require spatially consistent training labels that align precisely with input meteorological fields. This study introduces an automatic cold front detection method using the ERA5 reanalysis dataset from the European Centre for Medium-Range Weather Forecasts (ECMWF) at 850 hPa, specifically designed to generate physically consistent labels for machine learning applications. The approach combines the Thermal Front Parameter (TFP) with temperature advection (AdvT), applying optimized thresholds (TFP < 5 × 10⁻¹¹ K m⁻²; AdvT < −1 × 10⁻⁴ K s⁻¹), morphological filtering, and polynomial smoothing. Comparison against 1426 manual charts from 2009 revealed systematic spatial displacement, with mean offsets of ~502 km. Although pixel-level overlap was low, with Intersection over Union (IoU) = 0.013 and Dice coefficient (Dice) = 0.034, spatial concordance exceeded 99%, confirming both methods identify the same synoptic systems. The automatic method detects 58% more fronts over the South Atlantic and 44% fewer over the Andes compared to manual charts. Seasonal variability shows maximum activity in austral winter (31.3%) and minimum in summer (20.1%). This is the first automatic front detection system calibrated for South America that maintains direct correspondence between training labels and reanalysis input fields, addressing the spatial misalignment problem that limits deep learning applications in atmospheric sciences. Full article

Coal blending has become a common practice in large-scale boilers due to fluctuations in fuel supply, and it has an important impact on combustion and nitric oxide (NO) formation. To clarify these effects, this study numerically investigates the combustion characteristics and NO generation in a 130 t/h tangentially fired pulverized-coal boiler under boiler maximum continuous rating (BMCR) conditions. A three-dimensional furnace model was developed based on the actual boiler geometry, and combustion was simulated using coal combustion sub-models coupled with the discrete phase model (DPM). The results indicate that increasing the proportion of bituminous coal raises the peak furnace temperature from 1856 K under unblended firing to 1959 K at 80% blending and increases the outlet NO concentration from 357 mg/m³ to 457 mg/m³. Furthermore, coal blending shifts flame intensity toward the furnace wall, enhances carbon monoxide (CO) formation in oxygen-deficient near-wall regions, and promotes NO generation in wall-adjacent high-temperature zones. These findings demonstrate that coal blending significantly influences combustion performance and pollutant emissions, highlighting the need for optimized air distribution and blending strategies in tangentially fired boilers. Full article

EsBax (bcl-2 Associated X protein), a member of the bcl-2 family involved in the mitochondrial apoptosis pathway, plays a crucial role in immune response and defense in invertebrates. In this study, we successfully cloned the full-length cDNA of EsBax from the Chinese mitten crab (Eriocheir sinensis) and investigated its immune-related functions. The EsBax cDNA is 3374 bp in length, including a 1563 bp open reading frame (ORF) encoding 521 amino acids, a 142 bp 5′ untranslated region (UTR), and a 1699 bp 3′ UTR. The predicted EsBax protein has a molecular weight of 58.0786 kD, a theoretical isoelectric point of 7.28, and contains three conserved BH domains (BH1-BH3), and a transmembrane domain (TM). Amino acid sequence analysis revealed the highest sequence identity (99.42%) with E. sinensis. For the expression analysis, three biological replicates were performed for each tissue and treatment group. Real-time quantitative PCR showed that EsBax mRNA was ubiquitously expressed in all examined tissues, with the highest expression in the hepatopancreas, followed by hemocytes, intestine, gill, and the lowest in muscle. Upon stimulation with lipopolysaccharide (LPS), Aeromonas hydrophila (AH), or cycloheximide (CHX), EsBax expression increased and peaked at 24 h (LPS and CHX) or 48 h (A. hydrophila), then decreased. These results suggest that EsBax expression is dynamically responsive to exogenous stimulants (LPS, A. hydrophila, and CHX) in E. sinensis, implying a potential role of EsBax in the molecular events associated with pathogen-induced apoptosis in this species. Full article