ACS Omega最新文献

The development of functional porous carbon materials has attracted great attention in various fields. In this work, N-doped algal biochar (NABc) materials were successfully prepared by an impregnation and calcination methods using Dicyandiamide as a modifier. The specific surface area, average pore volume, and average pore diameter of NABc1%, were 693.92 m²·g^–1, 0.162 cm³·g^–1 and 6.76 nm, respectively. The high efficiency of NABc1% in adsorbing the cationic dyes rhodamine B and methylene blue from water may be attributed to the rich pore structure of NABc1%. The adsorption experiments show that the removal rates of rhodamine B and methylene blue by NABc1% in 90 min are 99.4 and 96.2%, respectively, which are obviously higher than those before modification. The experimental results of adsorption kinetics show that the adsorption process is more consistent with the quasi-second-order kinetic fitting equation (R² = 0.961, 0.998). The results of isothermal adsorption experiments show that the adsorption process is more consistent with the Langmuir equation (R² = 0.919, 0.916), indicating that the adsorption of rhodamine B and methylene blue by NABc1% is dominated by a monolayer adsorption process. In addition, the fitting of the intraparticle diffusion model shows that internal diffusion is not the only rate-limiting step. Hence, NABc1% has great potential for practical application as an efficient adsorbent in the field of cationic dye wastewater treatment.

This study presents an innovative approach to optimizing perpendicular magnetic anisotropy (PMA) in CoFeB/MgO structures through the strategic insertion of an ultrathin CoFeB layer between the top capping layer (Ta or Mo) and the CoFeB/MgO stack. Adding a 0.43 nm CoFeB insertion layer significantly enhances PMA by improving Fe–O hybridization, suppressing interfacial diffusion, and stabilizing MgO crystallinity. Postannealing at 400 °C, the CoFeB (free)/MgO (capping)/CoFeB (0.43 nm insertion layer)/Ta (top capping) configuration demonstrates superior performance, achieving an interfacial anisotropy constant (K_i) of 3.8 erg/cm², the highest reported for similar structures under these conditions. Advanced analyses using high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy reveal that the ultrathin CoFeB insertion effectively mitigates diffusion from the top capping layer, maintaining optimal oxidation and structural integrity at the interface. These findings not only deepen the understanding of PMA enhancement mechanisms but also provide a thermally stable, high-performance solution compatible with CMOS back-end-of-line processing. This work underscores the potential of interfacial engineering for advancing next-generation spintronic technologies.

Neglected tropical diseases as Chagas disease (CD) affect more than eight million people, mainly in the Americas, causing fatal cardiovascular outcomes. Relying on two old, toxic, and low efficacy drugs for treatment, there is an urgent need for new candidates. Comprising a high chemodiversity, marine bacteria are a rich source of small molecules with potential against human pathogens. Cultivation-based strategies of bacteria, such as the one strain many compounds (OSMAC) approach, have proven to be a simple and promising tool for drug discovery, with the ability to stimulate the expression of cryptic genes in microorganisms. In this study, using the OSMAC, we evaluated the potential of the marine bacteria Metabacillus indicus to produce anti-Trypanosoma cruzi compounds with higher potency. The M. indicus was cultivated under different conditions, subdivided into four groups, as nutritional, physical, biological, and chemical alterations. For comparisons, the extract obtained from the bacteria in Marine Broth (static) at 25 °C was used as a control and resulted in an EC₅₀ value of 28 μg/mL against the trypomastigotes. The physical alterations proved to be the most effective approach to improve the potency of M. indicus metabolites, resulting in EC₅₀ values between 3 and 26 μg/mL. The cultivation in Marine Agar potentiated the antitrypanosomal metabolites by 8.4-fold. When exposed to cobalt-60 γ radiation (0.5 kGy), the bacteria produced metabolites with 2-fold higher antitrypanosomal potency. The nutritional alterations resulted in potent metabolites, with EC₅₀ values between 11 and 18 μg/mL, while biological alterations resulted in EC₅₀ values between 11 and 28 μg/mL. Addition of T. cruzi and Leishmania infantum antigens and co-cultivation with Acinetobacter baumannii, enhanced by 2-fold the potency. Chemical elicitors such as DMSO and EtOH demonstrated no improvements for M. indicus cultivation. The chemical profile of M. indicus was analyzed using NMR and UHPLC-ESI-HR-MS/MS and processed using the GNPS platform, which led to the annotation of nucleosides, dipeptides, steroids, and fatty acid derivatives. These findings confirmed that the OSMAC approach yielded not only distinct antitrypanosomal activities but also distinct metabolomic profiles in M. indicus that could be exploited for drug discovery studies for Chagas disease.

Deep coal reservoirs in the Daji region of China have achieved high industrial gas production rates through large-scale volumetric fracturing. However, severe proppant flowback has significantly undermined coalbed methane recovery. Choke size management presents a practical and cost-effective approach to controlling proppant flowback. To quantify the relationship between proppant flowback and flow rate, this study conducted flowback experiments on actual coal fracture surfaces under both single-phase water production and gas–water two-phase coproduction conditions. The experiments examined the time-varying characteristics of flowback under constant flow rate, and a semitheoretical model for predicting cumulative proppant flowback was developed based on dimensional analysis. The results showed that flow velocity variations at the boundaries of flowback channels significantly influence proppant flowback rates. Under equivalent total flow conditions, the cumulative proppant flowback during the gas–liquid two-phase stage increased by 98.19% compared to the single-phase water production stage. When the fracture width increased to 6 mm, compression from the fracture walls significantly intensified proppant flowback, though the increase in flowback ratio tended to level off. When closure stress exceeded 15–20 MPa, the differences in cumulative proppant flowback became less pronounced. These findings provide theoretical guidance for choke size management, aiding in the optimization of production strategies while effectively controlling proppant flowback.

Plastic pollution has become a pressing global crisis that threatens biodiversity and reduces the adaptability of the ecosystem to climate change. Additive manufacturing technologies hold promise in the context of distributed recycling and sustainability. The present work elaborates on developing low-cost, robust feedstocks with improved toughness based on postconsumer polyethylene terephthalate, rPET, and micronized scrap tire rubber powder (MRP) for additive manufacturing. The effects of a series of nonreactive (polystyrene-block-polybutadiene-block-polystyrene (SBS) and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS)) and reactive compatibilizers (polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-g-maleic anhydride (SEBS-g-MA), poly(ethylene-co-glycidyl methacrylate) (EGMA), and poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (EMAGMA)) on the mechanical and rheological properties of rPET/MRP composites were investigated. rPET/MRP composites comprising compatibilizers with glycidyl moieties showed relatively higher impact strength and elongation at break. Rheological measurements revealed that incorporating MRP into rPET in the presence of compatibilizers remarkably increases melt viscosity, making the composite formulation suitable for extrusion processing. Differential scanning calorimetry results disclosed that reactive compatibilizers favorably reduce composite crystallinity compared to non-reactive ones, which are ascribed to the formation of long-chain branches. The potential of rPET/MRP filaments for fused deposition modeling was screened by using a low-budget desktop 3D printer. It is envisioned that the findings of this study will improve resource efficiency and the supply chain to achieve a waste-free economy and sustainability.

Fuel properties (viscosity, density, surface tension, ignition delay times) of binary mixtures containing a highly reactive fuel (n-heptane) and a low-reactive fuel (ethanol or ethyl acetate) are investigated in this study. For certain mixing ratios, the ethanol blend is found to exhibit longer ignition delay times after injection than the ethyl acetate blend, particularly noting that pure ethanol shows shorter ignition delay times than pure ethyl acetate. To explore the underlying causes, a comprehensive analysis is conducted, focusing on injection dynamics, mixture formation, and the chemical mechanisms leading up to ignition. Experiments on physical fluid properties, including viscosity, density, and surface tension, are performed to assess potential fluid mechanical effects on ignition delay times, with these properties fitted to existing mixing rules. Theoretical ignition delay times for different mixing ratios are calculated using a kinetic model, while experiments using a rapid compression machine provide insights into the purely chemical ignition delay for specific mixture ratios across various temperatures. Additionally, a rate-of-production analysis is conducted to offer a deeper understanding of the changes in reactivity observed in these fuel blends. Through this analysis, it becomes apparent that the change in reactivity is due to a change in the reaction pathways for ethyl acetate.

Single-use plastics are a major contributor to the generation of plastic waste. Biodegradable polymers provide some hope of curbing this emerging waste issue, with polylactic acid being a promising example. This study examined the biodegradation of l-poly(lactic acid)─PLLA, d-poly(lactic acid)─PDLA, various blends of PLLA and PDLA, as well as a sample of sc-PLLA/PDLA-50–50-A annealed for 30 min to induce crystallization. A simulated study in a lab-scale direct measurement respirometer compared the abiotic and biotic degradations of the various films in compost. The films’ crystallinity increased at the beginning of degradation before plateauing. The molecular weight (M_W) decreased first due to hydrolysis from about days 30 to 60, depending on the film, and then due to biodegradation when the microorganisms were able to assimilate the oligomers after it was broken down sufficiently by hydrolysis. By 120 days, the percent biodegradation of the annealed sc-PLLA/PDLA-50–50-A was greatest, at 97%, followed closely by the PLLA/PDLA 50–50 blend at 86%, while PDLA biodegraded the least, at only 40%. Scanning electron microscopy micrographs obtained for all films from day 0 up to day 60 clearly show the erosion of the films over the experiment’s progression. These findings showcase the potential of stereocomplex PLA as a biodegradable plastic alternative and support the pursuit of complementing or replacing traditional petrochemical-based plastic options.

Lead (Pb²⁺) contamination in drinking water remains a critical public health concern, particularly for children, due to lead pipes and plumbing in many water systems. Conventional Pb²⁺ detection methods, such as ICP-MS and AAS, are costly, time-intensive, and require specialized personnel. In this study, we developed and utilized a portable voltammetric Pb²⁺ detection system, the E-Tongue, which features a mercury-free, gold nanostar-modified screen-printed carbon electrode, and nontoxic buffer reagents (0.1 M sodium acetate, 0.1 mM potassium ferrocyanide, pH 4.5). The E-Tongue provides Pb²⁺ detection within 5 min with a method detection limit of 1.6 ppb and a wide linear range of 5–200 ppb. Results demonstrated the E-Tongue’s ability to detect Pb²⁺ above the EPA action level (10 ppb), even in high Cu²⁺ conditions (up to 1.3 ppm), with Pb²⁺ recovery of 84–105% and RSD < 10%. The E-Tongue’s color-coded and quantitative feedback enables nonexperts to test tap water and share data, facilitating community-driven monitoring and intervention strategies. Additionally, spatial analysis revealed that Andover had the most alkaline and conductive tap water, while Lawrence exhibited neutral water on average. The E-Tongue empowers communities, demonstrating the potential of participatory approaches for lead detection and mitigation in water networks.

Plastic pollution in agricultural soil is a major concern, affecting soil biodiversity and functionality. In this context, studies of agricultural soil plastic pollution that consider its use across different regions are essential. Considering land use (forest, grassland, and agriculture), this study aimed to identify, quantify, and characterize plastic debris in various agroecosystems within a Southeast Brazil sub-basin. Additionally, the sampled plastic debris was georeferenced, allowing its characteristics to be correlated with terrain features, such as the LS factor and vegetation cover. Based on size, the plastic debris was categorized into macroplastics, mesoplastics, and coarse microplastics. The results revealed that agricultural areas accounted for 91.2% of the total plastic waste collected. The most common polymer types identified were polypropylene, polyethylene, and poly(vinyl chloride), comprising 82.6% of the total. The accumulation of plastic debris in this region was primarily linked to intensive human activity and agricultural practices. Moreover, its distribution strongly correlated with terrain characteristics, particularly the LS factor and vegetation cover, with higher concentrations observed in smooth and moderately undulating terrain. These findings highlight the importance of monitoring plastic debris in the microwatershed terrain and identifying pollution sources to provide valuable insights for mitigating its environmental impact.

Cellular communication is a critical process that relies on exocytosis, during which cells release stored chemical messengers contained within intracellular nanoscale vesicles (50–500 nm in diameter). Before this occurs, the vesicle membrane must open and form a fusion pore, allowing its contents to be released into the extracellular space. This subcellular process involves various biomolecules, such as lipids and proteins, within the membrane, and any changes in their levels can impact dynamic pore formation and, consequently, the exocytosis process. Due to their small size, intracellular location, and sensitivity, direct studies of vesicles are challenging yet highly valuable. One of these crucial biomolecules is phosphatidylinositol-4,5-bisphosphate (PIP2), a lipid involved in membrane dynamics and related processes including exocytosis. In this study, we employed a combination of sensitive confocal microscopy and vesicle impact electrochemical cytometry (VIEC)─a novel amperometric technique using microelectrodes (D, 33 μm)─to test the hypothesis that elevated PIP2 levels regulate vesicle membrane properties and indirectly influence the exocytosis process. To investigate this, we used nanoscale vesicles isolated from neural cells as a biological model system. First, imaging analysis revealed that high PIP2 levels led to its accumulation in both cell and vesicle membranes, where it also participates in exocytosis. Next, direct analysis of PIP2-treated and untreated single nanoscale vesicles using VIEC demonstrated that while the vesicle content (i.e., the number of stored catecholamines) remained unchanged after PIP2 treatment, the vesicle opening dynamics were altered compared to the control. Specifically, our results showed that the vesicle opening rate increased by 1 ms, and the duration of vesicle opening extended from 5.7 to 6.9 ms in PIP2-treated vesicles compared to the control. In addition to the recognized roles of PIP2, these findings indicate that an extra level of PIP2 modulates the vesicle opening rate and suggest that PIP2 enhances membrane stability while delaying the vesicle opening process. Interestingly, this observation aligns with previous experimental and computational studies, which reported that abnormally high levels of PIP2 or other lipids can modify membrane properties and then exocytosis too. In our study, we observed this effect for PIP2 at abnormal levels through single vesicle electroanalysis. Furthermore, these results open a new way of investigating similar membrane components and their roles in disease mechanisms and cellular processes.