ACS Omega最新文献

The catalytic hydrocracking of crude soybean oil wasinvestigatedusing ZSM-5 and NaY zeolites modified by ammonium ion exchange andwet impregnation with 5 wt % niobium pentoxide (Nb₂O₅). The aim was to correlate changes in acidity, structuralproperties, and product selectivity for biofuel production. Catalystswere characterized by XRD, FTIR, SEM, N₂ physisorption,NH₃-TPD, and atomic absorption spectroscopy. Ion exchangesignificantly increased total acidity, particularly for HY (241% increase)and HZSM-5 (59% increase), while Nb₂O₅ impregnationmodified the acidity profiles and influenced the distribution of acidsites without affecting the zeolites’ framework stability.The observed changes in acidity following Nb₂O₅ impregnation were not uniform, suggesting a redistribution of acidsite strength rather than simple neutralization. Hydrocracking reactionswere carried out at 450 °C under hydrogen flow in a fixed-bedreactor. ZSM-5-based catalysts exhibited higher selectivity towardgaseous hydrocarbons (C₁–C₅), whereasNaY-based catalysts favored light liquid hydrocarbons (C₆–C₈), reflecting their weaker acid sites and largerpores. Proton-exchanged HZSM-5 enhanced gasoline-range product formationand improved deoxygenation efficiency. Niobium-impregnated catalystspromoted aromatization and shifted the deoxygenation pathway fromhydrodeoxygenation toward decarboxylation over time. The results demonstratethat acidity tuning through ion exchange and Nb₂O₅ addition effectively controls cracking pathways and hydrocarbondistribution, offering a viable strategy for biofuel production fromvegetable oils.

Paper-based colorimetricsensors offer a low cost and accessibleplatform for point-of-care (POC) analysis, but enzyme activity lossduring coating and drying can weaken analytical signals and requirehigh enzyme loadings or complex immobilization procedures. Althoughsurfactants are widely used to improve wettability in paper-basedassays, their potential contribution to colorimetric performance beyondthese effects remains unclear. Here, we investigated surfactant-assistedcolorimetric signal enhancement in a glucose assay implemented ona 96-puddle paper plate (96-PPP) and identified Tween 20 as the mosteffective surfactant. Its effect on detection performance became morepronounced as glucose oxidase (GOx) loading decreased; at 0.1 mg/mLGOx, Tween 20 lowered the limit of detection (LoD) from 0.113 to 0.034mg/mL (approximately 3.3-fold) over a working range of 0–5mg/mL, despite no statistically significant change in the measuredcontact angle at this loading. Tween 20 had no appreciable effecton the reaction in solution but preserved 95% of the apparent reactionrate constant after drying, compared with 11% without it, and atomicforce microscopy (AFM) revealed a more dispersed dried enzyme morphologyon mica. Tween 20-containing sensors also showed slower signal decayduring repeated wetting–drying cycles and thermal stress, retained77% (vs 26%) of the response at 400 mM NaCl, and exhibited within-PPPand between-batch coefficients of variation (CVs) below 10% (vs 12.3–19.5%),while maintaining glucose selectivity over potentially interferingmolecules. These results indicate that Tween 20 enhances paper-basedglucose sensing through mechanisms beyond simple wettability effects,in part by retaining enzyme cascade activity during drying, althoughthe contributions of the individual enzymes and the underlying mechanismremain to be established.

This study evaluated the potential of Enterococcus faecium E297 as a functional dietary supplement for broilerchickens, assessingits effects on zootechnical performance, immune response, and meatquality. A total of 224 chicks were allocated to four treatments:a control diet, a diet containing an antibiotic growth promoter, adiet supplemented with E. faecium E297, and a commercialprobiotic diet. Probiotic supplementation improved feed conversionand weight gain and increased leukocyte counts compared with the controlgroup. Birds fed E. faecium E297 showed a highervillus-to-crypt ratio, suggesting greater nutrient absorption efficiency.Meat from probiotic-supplemented groups exhibited lower fat contentand higher protein levels. No significant differences (P > 0.05) were observed in microbial counts of the litter, cloaca,or feces throughout the experimental period. The results indicatethat E. faecium E297 has potential as an effectiveprobiotic alternative to antibiotic growth promoters in poultry production.

Si and Ge are technologically important semiconductorsfor electronic,photovoltaic, and optoelectronic applications. Herein, we report mixed-sourcehydride vapor phase epitaxial growth of (Ge, Si_1–xGe_x)–AlN core–shellcrystals on Al-based nanoabsorbers. Nano-CT and microscopy resolvehollow, partially filled, and filled morphologies that together supporta Plateau–Rayleigh-instability-mediated shell-first model inwhich an Al-derived shell-like structure precedes filling by Ge-containingor Si–Ge-containing material. Electron microscopy, energy-dispersiveX-ray spectroscopy, and Raman measurements provide complementary structuraland compositional context, including local observations consistentwith 2H-like Si domains. Four room-temperature photoluminescence spectrarecorded under 532 nm excitation show telecom E-band features withsampled maxima at approximately 1371.9, 1377.0, 1381.1, and 1391.8nm. Additional archived nominal-setting records for four spectralwindows are presented as qualitative excitation-setting comparisons.Audited HSE Δ-self-consistent-field end points and PBE scalingcalculations evaluate neutral C_Si–O_i asa candidate model, while newly added formation, association, k-point,and cell-size sensitivity tests define the scope of that comparison.The optical data are therefore reported without a peak-specific microscopicor single-emitter assignment. The combined results establish the shell-firstgrowth morphology and document room-temperature E-band photoluminescencein group-IV/III-nitride core–shell material.

Producing green hydrogen via water electrolysis offersa potentialpathway for achieving a sustainable energy transition. Despite itspotential, it is limited by the sluggish kinetics of OER, which motivatesthe development of efficient catalysts. In addition, the field stilllacks standardized and reproducible approaches for evaluating catalystfaradaic efficiency (FE) and monitoring the oxygen production. Therefore,we present a 3D-printed electrochemical cell coupled with a Clarksensor for in situ oxygen quantification during OER,while measurement uncertainties were examined to confirm the precisionand reproducibility of the methodology. The effects of electrolyteconcentration (0.1, 0.5, and 1.0 mol L^–1 KNO₃), different electrolytes (KNO₃ and PBS), electrodesurface area (0.071 and 0.195 cm²), and applied constantcurrent (1, 5, and 10 mA) were investigated. Statistical validationdemonstrated high reproducibility and robustness. At 10 mA in 0.1mol L^–1 KNO₃ using a 0.071 cm² electrode area, Pt exhibited higher oxygen evolution and FE (4.55± 0.5 mg L^–1, 85.6 ± 10.8%) than GC (2.32± 0.3 mg L^–1, 43.6 ± 6.1%). The methodologywas subsequently applied to Prussian blue (FePBA), and its respectivecobalt and nickel Prussian blue analogues (CoPBA and NiPBA, respectively).Among the investigated materials, NiPBA exhibited the highest OERactivity (0.40 ± 0.03 mg L^–1 with 76.5 ±5.7% FE), and was comparable to CoPBA, while both outperformed FePBAat 1 mA. A trend in the NOP was observed among the PBAs, followingthe order NiPBA ≥ CoPBA > FePBA. This approach providesa reproducibleplatform for dissolved oxygen quantification and the standardizedbenchmarking of OER electrocatalysts.

Methicillin-resistantStaphylococcus aureus(MRSA) is a bacterial pathogen that relies on expression of a widerange of virulence factors. Hemolysins are a diverse collection ofcytolytic toxins that promote virulence by being excreted and lysinghost blood cells. We previously reported on novel antivirulence compoundsthat modulate hemolysis in vitro, including a brominated carbazole(compound 8) and the active ingredient in Claritin (loratadine). Weanalyzed expression and activity of MRSA hemolysins in two hospital-acquiredstrains. Even with the same staphylococcal cassette chromosome mec (SCCmec) type, the strains displayedunique responses to loratadine where both repression and elevationof hemolysis occurred. These compounds are potentially binding andregulating the master regulatory protein, Stk1, which has known tiesto hemolysis inS. aureus. We hypothesizedthat the modulation of hemolysis by these putative Stk1 inhibitorswould extend to community-acquired strains of MRSA. Furthermore, wewanted to determine if Stk1 was the only hemolysis regulatory proteinbeing engaged by these compounds. To test this, we examined compound8 and loratadine effects on two different USA300 strains, in additionto transposon mutants for a range of hemolysis regulatory genes. Weobserved strain-specific regulation of hemolysis by Stk1. Loratadinecontinued to downregulate both alpha and beta hemolytic activity inUSA300 JE2 in both Stk1-dependent and independent pathways. Additionally,we report that this antivirulence compound effectively disrupts hemolysisby modulating both agr and vraSR global regulators, contributing to widespread cytotoxin repression.Both alpha hemolysin (hla) and RNAIII/delta hemolysin(hld) mRNA reductions occurred in vitro and in ahuman cell line model of MRSA infection. Together, these results expandour knowledge of loratadine’s mode of action as a virulencemodulator.

This study systematically investigates the molecularstructuralcharacteristics of different rank coals (anthracite, bituminous, lignite)and their adsorption properties and mechanisms toward hydrogen sulfide(H₂S). By combining X-ray photoelectron spectroscopy (XPS)and solid-state 13C NMR spectroscopy, it was found that aromatic carboncontent increases remarkably from 55.91 to 91.75% with coal rank increasing,whereas aliphatic carbon and oxygen-bearing functional groups decreaseaccordingly. Macromolecular model representatives corresponding toeach coal rank were constructed based on experimental data, and molecularsimulation and adsorption analysis were performed using MaterialsStudio software. Pore structures vary markedly with coal rank: ligniteshows the greatest total pore volume but limited connectivity, whereasanthracite develops a well-connected micropore network. H₂S adsorption follows the Langmuir–Freundlich model, with capacitiesdecreasing in the order: anthracite > bituminous > lignite.Althoughthe adsorption capacity decreases with increasing temperature, theeffect of temperature on the adsorption capacity of different coalgrades shows a non monotonic variation. Oxygen-bearing functionalgroups─particularly carboxyl, hydroxyl, and carbonyl─dominateH₂S adsorption via hydrogen bonding, whereas π-electronsof aromatic rings contribute weakly. Molecular dynamics simulationsshow that the diffusion coefficient of H₂S increases withtemperature and is highest in anthracite. This study elucidates theinfluence mechanism of coal rank structure on H₂S adsorptionbehavior at the molecular level, providing a theoretical basis forthe treatment of H₂S in coal seams.

Secondary injuryfollowing ischemic traumatic brain injury(TBI)is heavily driven by neurovascular dysfunction involving endothelialdamage, astrocyte reactivity, inflammation, and hypoxic stress, amongother contributing pathophysiological processes. Here, we establisha mechanistically informative in vitro ischemic TBI model that isolatesendothelial-astrocyte crosstalk using human brain microvascular endothelialcells (HBMECs) and astrocytes. Using this platform, we evaluated melatoninand oxygen nanobubbles (ONBs) as a combinatorial therapeutic strategy.Fabricated ONBs exhibited a mean hydrodynamic diameter of 78.35 ±0.42 nm, a negative surface charge of −37.86 ± 1.32 mV,and sustained oxygen retention (56.38 ± 0.86 mg/L initially).Mechanical needle-scratch injury combined with hypoxia induced primaryendothelial injury characterized by reduced viability and increasedexpression of inflammatory and hypoxia-associated markers, quantifiedby quantitative real-time PCR (qRT-PCR). Injured HBMECs subsequentlytriggered astrocyte reactivity marked by elevated GFAP (1.93-fold; p < 0.0001), NLRP3 (3.21-fold; p <0.0001), NF-κβ signaling (1.62-fold; p < 0.0001), and HIF-1α (2.28-fold; p <0.0001), while reactive astrocytes propagated a secondary wave ofendothelial degeneration, establishing a bidirectional injury loop.Melatonin alone only partially mitigated injury-associated signaling,whereas the melatonin-ONBs combination restored astrocytic and endothelialgene expression to near-baseline levels. These findings highlighta multimodal therapeutic approach that effectively suppresses inflammatory,apoptotic, and hypoxic signaling in ischemic TBI.

6-Aminopenicillanicacid (6-APA) is a β-lactam intermediateof major industrial relevance and a key precursor for producing semisyntheticantibiotics. This study presents the development and analysis of amathematical model describing 6-APA production via heterogeneous enzymatichydrolysis of penicillin G in a batch reactor catalyzed by penicillinG acylase (PGA) immobilized on spherical supports. The model is formulatedusing coupled mass balances in the liquid and solid phases, explicitlyconsidering diffusive and convective transport effects on the reactionkinetics. The resulting system of differential equations is solvedusing three independent approaches: the method of lines (MOL), adoptedas the reference solution with explicit spatial dependence, the classicalapproximation, and the coupled integral equation approach with H_1,1 approximation, the latter two being consideredapproximate solutions. A convergence analysis defines the spatialdiscretization required for the MOL solution. Comparison among thethree methodologies shows excellent agreement, demonstrating the consistencyof the solutions obtained. The results indicate that the mass Biotnumber (Bi_m) plays a critical role inreactor performance, with complete conversion being achieved at reducedreaction times for Bi_m equal to 10. Theresults demonstrate the validity of the proposed model and the effectivenessof the solution methods used, contributing to the analysis and optimizationof heterogeneous enzymatic processes at the industrial scale.

Anaerobic fermentationof biomass feedstocks using open culturesis a promising technology to produce platform carboxylates. Syngas,a mixture of H₂, CO₂, and CO, can be sourcedsustainably and used to supplement biomass feedstocks as a sourceof acetyl-CoA, an intermediate for carboxylate chain elongation. Totest this, syngas and corn silage were provided to a 10-L semicontinuousfermenter for 208 days of operation in a first-of-a-kind study atthis scale. After acclimation to syngas, a 2-fold reduction in averageCO₂ production rate (0.097 vs 0.21 g L^–1 d^–1) was observed over a period of 42 days incomparison to a control. Syngas cofeeding also increased average productionrates of n-butyrate (C4) and n-caproate(C6) by 74 and 27%, respectively, although these effects were observedat relatively low C6 concentrations up to 4 g L^–1. Abundances of Megasphaera and Dialister showed significant correlation (p < 0.05) toconsumption of H₂, CO₂, and CO as well as productionof C3, C4, C5, or C7, suggesting involvement of these genera in mixotrophicmetabolism. A feasibility analysis showed that syngas recirculationcould return additional 1.54 USD m_broth^–3 while costing 1.26 USD m_broth^–3 andavoiding 1.81 kg CO_2 eq. m_broth^–3 in emissions compared to heterotrophic fermentation. With stillmuch room to increase syngas consumption and carboxylate production,we propose mixotrophic fermentation as a “low-tech”technology to turn fermenters into decentralized industrial carbonsinks.