ACS Omega最新文献

Polycarbonate is a widely used engineering plastic. However, synthesis procedures using phosgene produce toxic gases that cause environmental pollution. It is important to improve the performance of polycarbonate by using a green and safe process. Here, we synthesized tetramethylbisphenol A and bisphenol A copolymers by a green, nonphotogas melt-transesterification process using bisphenol A, diphenyl carbonate, and tetramethylbisphenol A as reaction materials. The catalysts required for the synthesis were screened. The chemical structures of the polymerization products were confirmed by an infrared spectrometer and a nuclear magnetic resonance spectrometer. The thermal and mechanical properties of polycarbonate materials were measured through differential scanning calorimetry, thermogravimetry, and an electronic Universal Testing Machine. The results showed that tetramethylbisphenol A copolycarbonate was successfully synthesized by a melt-transesterification process. Moreover, the addition of tetramethylbisphenol A significantly improved the thermal and mechanical properties of polycarbonate. The effects of catalyst dosage, diphenyl carbonate/diphenol molar ratio, polycondensation reaction temperature, and time on the molecular weight of tetramethylbisphenol A and bisphenol A copolymer were investigated, and the optimal conditions were obtained.

In recent years, gas leakage from buried pipelines has been an inevitable issue worldwide. The leaked gas can diffuse through the soil into adjacent underground confined spaces, such as sewage pipelines, thereby posing significant risks to human lives and property in the event of a fire. To investigate the diffusion characteristics of leaked natural gas in underground semiconfined spaces, this paper establishes a mathematical model for natural gas diffusion in sewage pipelines. The study examines the impact of the gas inlet velocity, sewage flow velocity, water level height, and vent hole size on the characteristics of gas diffusion within sewage pipelines. The concentration of natural gas in the manhole increases as the natural gas inlet velocity, sewage flow velocity (up to 0.6 m/s), and water level height rise, with the magnitude of the increase gradually diminishing. Additionally, it was observed that the size of the vent hole significantly affects the concentration at upstream test points. In contrast, its effect on the concentration variations of downstream test points gradually weakens. This paper also puts forward a three-level early warning mechanism and analyzes and discusses the influence of the above factors on the early warning time of natural gas in the manhole.

We report the isolation and complete NMR characterization of four new ecdysteroids and LC-MS/MS fingerprinting of ecdysteroids in two native and two industrially processed Cyanotis arachnoidea extracts along with an autoxidized product mixture of 20-hydroxyecdysone (20E). The autoxidation of 20-hydroxyecdysone leads to the formation of various unknown or uncharacterized ecdysteroid compounds, which can significantly impact the quality and efficacy of commercial ecdysteroid-containing supplements, potentially affecting their regulatory status and consumer safety. A total of 146 ecdysteroids were detected. Among these, 20 were identified using authentic and fully characterized reference standards, including the newly reported compounds. The autoxidative origin of many process-related artifacts was confirmed in the two commercial ecdysteroid extracts. Considering the pharmacological versatility of ecdysteroids and the major pharmacological differences between these compounds and their autoxidized derivatives, our results are of importance regarding the efficacy and safety of commercially available ecdysteroid-containing food supplements.

Surface-enhanced Raman scattering (SERS) has become an advanced spectroscopic analysis method in the fields of chemistry, biomedical sensing, and imaging, owing to its excellent vibrational signal recognition and sensitivity for single-molecule detection. The effectiveness of SERS technology relies on the development of high-performance substrates, which must possess high sensitivity, uniformity, and repeatability. In this study, the enhanced substrates with high Raman activity were successfully prepared by adopting the three-phase self-assembly method to assemble gold nanorods (AuNRs) into nanopores of ultrathin porous alumina (AAO) films. By precisely controlling the pore size of AAO and the dimensions of AuNRs, the ability of the substrates and the Raman detection limits are enhanced significantly. Probe molecules, including Rhodamine 6G (R6G), Crystal Violet (CV), and Aspartame (APM), were selected to test the substrates sensitivity and uniformity, with detection limits of 10^–13, 10^–12 M, and 7.8 mg/L, respectively. Random sampling was conducted on the substrate surface to analyze the spectral characteristics of the characteristic peaks of R6G and CV molecules, and the relative standard deviations (RSD) were 4.3 and 3.18% at characteristic peaks 612 and 1619 cm^–1, respectively, demonstrating the enhanced uniformity of the prepared substrates. This research indicates that assembling AuNRs onto AAO substrates results in significant Raman activity, providing a more reliable platform for the application of SERS technology.

Rare earths are of significant benefit to the electrochemical performance, reliability, and safety of batteries. The integration of rare earth elements into MoS₂ anode materials holds promise for enhancing the cycling stability of batteries during charging and discharging cycles. In this work, a nanoflower-like composite of Ce₂Mo₃O₁₂/MoS₂/C was synthesized as an anode material by an enhanced hydrothermal method. The experimental results showed that the incorporation of carbon resulted in a more sophisticated flower-like structure of the material. The annealing process has little effect on the morphology and crystal structure of the Ce₂Mo₃O₁₂/MoS₂/C composite. After being annealed at 500 °C for 2 h, the Ce₂Mo₃O₁₂/MoS₂/C composite exhibited remarkable cycling stability as an anode material for lithium-ion batteries (LIBs). The initial discharge capacity at a current density of 500 mA g^–1 was 747.98 mAh g^–1, while the discharge capacity after 200 cycles exhibited a capacity retention rate of 77.34%. The results demonstrate the potential of this material for energy storage applications and provide an alternative to the rational design of related materials.

In a petroliferous basin with multiple sets of source rocks, determining the origins of hydrocarbons and their mixed ratios is a crucial aspect of hydrocarbon accumulation mechanisms. Focusing on the Mesozoic-Paleozoic reservoirs within the Cangdong Depression, this study began with source–source comparisons to identify key distinguishing parameters. This was followed by oil–oil correlations using the cluster analysis method. And then, oil source correlations were performed to determine the origins of each type of crude oil. On this basis, a quantitative method for predicting the proportion of mixed crude oil sources was proposed. The results show that the Ek₂ and C–P source rocks are both rich in organic matter. However, the Ek₂ source rocks are predominantly sapropelic and humic-sapropelic and favorable for oil generation. However, the C–P source rocks are primarily humic-sapropelic and more conducive for gas generation. Using cluster analysis, the Meso-Paleozoic crude oils in the Cangdong Depression are classified into two main types. Type I crude oil is primarily derived from C–P coaly mesure source rocks, while Type II crude oil is mainly sourced from the Ek₂ source rocks. Additionally, the oil source index (OSI) was proposed, involving physical property, carbon isotope, Ts/Tm, C₃₀–/C₂₉–Hopane, C₂₇–/C₂₉–regular sterane, and tricyclic terpene/C₃₀–Hopane. An OSI greater than 1.20 indicates a source of Ek₂, while an OSI less than or equal to 0.40 suggests humic oils derived from C–P source rocks. When the OSI falls between 0.40 and 1.20, crude oil is classified as a mixed-source oil. The proportion of mixed sources can be determined by the OSI value’s proximity to the two end-point values. This study provides a valuable reference for analyzing the origin of crude oil in similar basins.

When microliter drops of salt solutions dry on nonporous surfaces, they form erratic yet characteristic deposit patterns influenced by complex crystallization dynamics and fluid motion. Using OpenAI’s image-enabled language models, we analyzed deposits from 12 salts with 200 images per salt and per model. GPT-4o classified 57% of the salts accurately, significantly outperforming random chance and GPT-4o mini. This study underscores the promise of general-use AI tools for reliably identifying salts from their drying patterns.

In developing hydrogel scaffolds for the soft tissue regeneration, a number of inorganic or carbonaceous fillers are embedded in alginate/gelatin-based hydrogel while manufacturing shape fidelity compliant constructs using three-dimensional (3D) extrusion printing. Among the spectrum of nanofillers, nanohydroxyapatite (nHAP), due to its intrinsic bioactivity, could promote mineralization and interaction with host tissues while conferring superior mechanical properties (strength and elastic modulus). Against this backdrop, this study demonstrates the effectiveness of nHAP reinforcement in tuning several clinically relevant properties such as rheological properties, mechanical properties, swelling, degradation, and antimicrobial properties. At higher concentrations of nHAP (0.75%) in the hydrogel matrix (3A5G0.75H), a 3.13-fold increment in the compressive strength was observed, with the gel stability window and the thermal stability of the cross-linked graft being extended to greater than 40 and 143 °C, respectively. This study demonstrated the printability of the nHAP-reinforced hydrogel ink by fabricating the matrix-shaped graft of dimension 20 mm in diameter and 10 mm in thickness, and the buildability was established by making the bulk-sized construct up to 62 layers (20 mm in height) with a well-maintained pore interconnectivity, as demonstrated using micro-CT analysis. Interestingly, the CFU study revealed a 2.9- and 1.5-fold improvement in the reduction of bacterial adhesion for 3A5G0.75H with respect to Escherichia coli and Staphylococcus aureus bacteria. Cell culture studies on the 3D printed scaffolds w.r.to NIH 3T3 fibroblast cell line demonstrated a consistent increase in cell viability and pronounced filopodial extensions, confirming the cytocompatibility of 3A5G0.75H scaffolds and their ability to support cellular growth during an in vitro culture. Taken together, the present study uncovers a process science-based understanding of the 3D buildability and biophysical properties of different concentrations of nHAP-reinforced hydrogel inks with clinically relevant properties.

Chagas disease (CD) is a neglected tropical disease for which novel and improved treatments are needed. The cysteine protease Cruzipain is one of the main targets for the development of novel drugs for the treatment of CD. Recent bioinformatics analyses have revealed four Cruzipain subtypes whose active sites differ in key positions for ligand recognition. These analyses suggest a possible effect on the substrate specificity and affinity for ligands. To better investigate the impact of substitutions in Cruzipain subtypes, we employed molecular dynamics simulations and varied structural analyses on representatives of each Cruzipain subtype. Our results indicated that the substitutions did not significantly affect the overall flexibility and conformation of these proteases. In contrast, we observed differences in their active site characteristics, including different electrostatic potentials, cavity volumes, and patterns of interactions with the virtual probes. The distinct alterations in the active site subsites, especially in the S2 subsite, suggest unique functional changes that could affect substrate binding, ligand recognition, and possibly enzymatic effectiveness in various biological situations.

The separation of water from crude oil has long posed a critical challenge in the oil industry, where stable water-in-oil emulsions hinder efficiency and environmental safety. Traditionally, chemical demulsifiers have been employed in this process. However, most of these demulsifiers are petroleum-based, toxic, and environmentally harmful, highlighting the need for sustainable alternatives. Castor oil maleate (COM) oligomers are suitable biobased demulsifiers for water-in-oil separation because they are biodegradable, nontoxic, and environmentally friendly, offering an option toward greener solutions in oil processing. This study synthesized COM oligomers by reacting castor oil and maleic anhydride using six distinct initiators: di-tert-butyl peroxide (DTBP), tert-butyl peroxy benzoate (TBPB), benzoyl peroxide (BPO), dicumyl peroxide (DCP), potassium persulfate (PSK), and sodium persulfate (PSNa). The findings revealed that DTBP, TBPB, and DCP produced COM oligomers with a higher proportion of longer chain lengths compared to persulfate initiators. COM synthesized using BPO continued polymerizing during storage, increasing the weight-average molecular mass and a higher content of long-chain-length oligomers. In contrast, the other COMs demonstrated typical biodegradation processes, characterized by a reduced weight-average molecular mass and diminished long-chain-length oligomer content. This study highlights the potential of COM oligomers to address longstanding challenges in the oil industry, providing an ecofriendly and efficient alternative to conventional chemical demulsifiers.