ACS Omega最新文献

The transportation of paraffinic oils, particularly from Kazakhstan, is hindered by the formation of asphalt–resin–paraffin deposits (ARPDs), which complicate production and transport processes. While chemical treatments using inhibitors and depressants are commonly used, they are often less effective for oils with high paraffin contents and unique compositions, such as those found in Kazakhstan. This study presents a novel approach to synthesizing a depressor additive (PTE) tailored specifically for paraffinic oils, addressing the limitations of existing commercial additives. The PTE additive, derived from pyromellitic acid dianhydride (PMDA), polyoxyethylene sorbitan trioleate (Tween-85), and arachidyl alcohol (1-eicosanol), was tested on paraffinic oil blends from West Kazakhstan (WKOM) and Kumkol-Akshabulak (KAOM) under combined thermal treatment conditions at 60 and 90 °C. Rheological analyses indicated that heat treatment alone improved cold-flow properties, but these effects were transient. However, the introduction of PTE at concentrations of 500–1000 ppm produced a significant, sustained reduction in yield loss temperature (from 18 to 3 °C in WKOM and from 12 to 0 °C in KAOM) and decreased effective viscosity to 0.167 Pa s for WKOM and 0.245 Pa s for KAOM at 0 °C. Microscopic analysis confirmed that PTE alters paraffin crystallization, forming large lamellar structures that prevent network formation and maintain oil fluidity. The PTE additive demonstrated consistent effectiveness over 10 days, surpassing the stability and impact of commercial additives. These findings highlight PTE as a tailored, effective solution for enhancing cold-flow properties in high-paraffin oils.

We report the synthesis of cobalt nanoparticles (Co NPs) via a DMF-protecting method and their use as catalysts in hydrosilylation reactions. Various types of cobalt nanoparticles were synthesized from different precursors, namely, cobalt(II) acetate, cobalt(III) acetylacetonate, and cobalt(II) bromide, to give Co NPs-OAc, Co NPs-acac, and Co NPs-Br, respectively. A range of methods, e.g., annular dark-field scanning transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption fine structure, were used to investigate their chemical properties. The results indicated that these cobalt nanoparticles involved a structure of Co₃O₄ regardless of the type of metal precursor. Alternatively, the particle size distribution and their cohesion with each particle strongly depended on the metal precursor, resulting in different catalytic activity for alkene hydrosilylation. The Co NPs-OAc exhibited the highest activity for the transformation with at least 0.005 mol % catalyst loading in the Co NPs, where the turnover number was 13 800. In addition, we succeeded in catalyst recycling by using a convenient liquid–liquid extraction method. The recycled catalysts retained their catalytic activity for alkene hydrosilylation, comparable to that of the pristine catalysts.

The direct dissolution of voloxidized used nuclear fuel (UNF) into an organic solution─comprised of diluent and specialized extractants─poses a promising alternative to the traditional liquid–liquid solvent extraction approach to reprocessing UNF. However, moving to direct dissolution removes the presence of a concentrated nitric acid aqueous phase, which has been shown to significantly influence the radiolytic longevity of extractants in conventional extraction flowsheets. Given the limited knowledge of radiation effects under direct dissolution conditions, here we present a time-resolved and dose-accumulation study on the impact of direct dissolution conditions on the radiolytic longevity of two candidate butyramide extractants, N,N-di(2-ethylhexyl) butyramide (DEHBA) and N,N-di(2-ethylhexyl)isobutyramide (DEHiBA), in pre-equilibrated n-dodecane solvent in the presence and absence of process-relevant metal ions, specifically, uranium and rhenium. Loss G(DEHBA) and G(DEHiBA) values were found to be comparable to each other, with an average of 0.37 ± 0.02 μmol J^–1, and to previous data from the γ irradiation of DEHBA and DEHiBA under conventional solvent extraction conditions. Rhenium, and by extension technetium, extraction had a modest decrease (∼10%) in the overall radiolytic stability of DEHiBA only, despite >2× observed increases in chemical kinetic reactivity of the corresponding complexes with the n-dodecane radical cation. Uranium loading, on the other hand, significantly improved the lifetime of both ligands (>30%) under γ irradiation, with a greater stabilization observed for DEHBA over DEHiBA. The observed radioprotective effect afforded by uranium loading is fortuitous for the longevity of direct dissolution solvent.

Herein, we report a rapid and mild esterification method using 5-nitro-4,6-dithiocyanatopyrimidine (NDTP) as a coupling reagent, which is effective in alcoholic and nonalcoholic solvents. The esterification process mediated by NDTP allows for the good yield synthesis of esters within just 1 min. A wide range of alcohols and carboxylic acids were effectively esterified under these optimized conditions. The method’s rapid execution, high efficiency, and adaptability across diverse substrates make it advantageous for ester synthesis.

We report the synthesis of a luminescent Pt(II) complex, PtL², based on a “two-wall” aryl-extended calix[4]pyrrole (C[4]P). We characterize its binding properties as a receptor of methyl trioctyl ammonium chloride (MTOA·Cl) in a dichloromethane solution. To this end, we performed ¹H NMR and UV–vis spectroscopic titrations. The singular luminescent properties of PtL² allowed the use of highly sensitive emission spectroscopy to monitor the binding. The binding affinity of PtL² for MTOA·Cl is 2-fold smaller than that of the C[4]P precursor. This difference is attributed to dissimilar anion−π interactions and binding geometries in the ion-paired complexes of the two receptors, (Cl⊂PtL²/C[4]P)@MTOA. Isothermal titration calorimetry (ITC) experiments revealed subtle differences in enthalpy and entropy. The entropic term, although negative, was very small, suggesting the relevance of the dissociation/association processes of the salt and the ion-paired complexes. We investigated the binding selectivity of PtL² toward a series of halides in acetone solution favoring ion-pair dissociation. PtL² binds chloride selectively and with a high affinity, producing mainly an anionic complex.

A dye-decolorizing peroxidase (DyP)-based electrochemical biosensor for hydrogen peroxide (H₂O₂) is developed in miniaturized, disposable, and user-friendly configuration. Wild type and variant DyPs are immobilized on self-assembled monolayer (SAM)-coated and nanostructure-modified screen-printed electrodes (SPEs) to ensure biocompatibility and increase the enzyme loading and hence the biosensor sensitivity. The structure of the enzymes attached to gold and silver nanoparticle (AuNP and AgNP)-modified carbon- and gold-based SPEs (C-SPE and Au-SPE) is monitored by resonance Raman spectroscopy and their electrocatalytic performance toward H₂O₂ by electrochemistry. Among the tested configurations, the wild type DyP/SAM/AuNP/C-SPE construct shows a superior performance, with a linear response range to H₂O₂ from 30 to 475 μM, a sensitivity of 234 ± 9 mA·M^–1·cm^–2, and a limit of detection (LOD) of 3.5 μM, measured in open air conditions. The device is suitable for single-use, on-site measurements of H₂O₂ in air-exposed samples such as physiological fluids. The herein developed biosensor shows a high potential for customization for the detection of other small hydroperoxide substrates and additional improvement of selected traits (e.g., sensitivity, thermal stability, and substrate inhibition properties) due to the easy and well-established production and genetic manipulation of the employed biocatalyst, DyP.

Oil production entails the generation of large volumes of complex effluents that contain emulsified oil in water. Difficult to manage, the use of membrane separation processes (MSP) is an interesting option for the treatment of oily effluents, separating oil-in-water (o/w) emulsions with high efficiency. Modifying the surface of membranes with metals minimizes fouling, which is the main drawback of MSP. Through a survey of scientific papers and patent applications, this review demonstrates the technological development of membranes containing metals or metallic nanoparticles (MNP) for separating o/w emulsions. In total, 314 articles and 339 patent filings were retrieved by July 2023. The beginning of growth in the number of documents retrieved was more significant in 2018 for articles and in 2017 for patents. Asia was the largest highlight, with emphasis on China, which had 76.97% of the production of articles and 98.31% of patent applications on the continent, justified by investment in Research and Development (R&D). Metals, such as Fe, Zn, Cu, and Ti have been used to modify membranes and substrates. Polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polypropylene (PP) membranes and carbon-based primary substrates were used for their preparation. Advancements in membranes containing metals or MNP for the separation of o/w emulsions can have a positive impact on Sustainable Development Goals (SDG). This developing field anticipates increased involvement in nanotechnology, the development of systems that enable both the separation and oxidation of organic compounds, and a variety of methods or combinations of approaches to synthesize increasingly efficient membranes.

Artificial three-dimensional (3D) skin models have been used as an alternative tool for toxicity testing, skin disease studying, and skin tissue engineering. The 3D skin model can be fabricated using a porous scaffold that provides 3D cellular construction that supports cell attachment and promotes nutrient and air permeation. In this study, fish gelatin (FG) and hyaluronic acid (HA) were selected for scaffold fabrication because they carry no risk of zoonotic disease transmission and are major components of the extracellular matrix (ECM), which may functionally mimic the ECM of native human skin. The FG-HA scaffolds prepared by using a freeze-drying technique were characterized for their porosity, swelling ratio, and mechanical properties. The scaffolds were seeded with dermal fibroblasts and epidermal keratinocytes followed by culturing in air–liquid interface conditions to allow for cell differentiation to form the dermis and epidermis layer, respectively. Histological analysis of the fabricated 3D skin using the FG-HA scaffold clearly exhibited a bilayer of the dermis and epidermis. Additionally, immunochemical staining of the epidermis layer demonstrated the expression of keratin 5, loricrin, and filaggrin, confirming the proliferation and differentiation of keratinocytes. This research evidently suggests that the FG-HA porous scaffold can serve as a potential material for constructing a 3D skin model with characteristics that closely resemble native human skin.

Pyrolysis of used tires is a promising method for recovering valuable chemicals. However, the conventional high-temperature pyrolysis of natural rubber (polyisoprene)-based tires suffers from a low-selective isoprene recovery, heavy carbon black (CB) damage, and coke formation on the CB. In this paper, we report on characteristics of the low-temperature pyrolysis of CB-containing polyisoprene-based tire rubber that is vulcanized with sulfur. The low-temperature pyrolysis of the tire rubber cleaves the main chain and cross-linking bonds, which allows for the recovery of low-molecular-weight tire rubbers, tire rubber dissolution into the solvent, and CB isolation from the rubber matrix. The maximum liquid rubber recovery rate was 76.7% after 1 h of heating at 282 °C. In addition, the molecular weight of the thermally treated rubber substantially decreased from M_w 340,000 to approximately 20,000 after 1 h of heating at 282 °C. Furthermore, the maximum isoprene skeleton retention rate of the recovered rubber was 83% at 267 °C after 1 h of heating. The remaining rubber matrix on the recovered CB surface was nearly eliminated at temperatures above 320 °C. In conclusion, we believe that the low-temperature pyrolysis of tire rubber is a promising pretreatment method for recovering CB without thermal damage and reducing the molecular weight of tire rubber, which will improve the recovery of isoprene.

Developing sensitive sensors to trimethylamine (TMA) remains a topic of great interest in areas such as food quality analysis and disease biomarkers. To address this issue, chemiresistive sensors were proposed using graphene quantum dots (GQDs) with different proportions of hydroxyl (GQDs-OH), epoxy (GQDs-epoxy), and carboxyl (GQDs-COOH) groups. These materials exhibited different sensitivities to TMA, with GQDs-OH being the most sensitive, presenting a detection limit of 0.3 ppm and a response of about 4 and 2.5 times higher than those of GQDs-COOH and GQDs-Epoxy, respectively. This difference in sensitivity was elucidated by building, based on density functional theory calculations, potential energy curves of the interaction between TMA and three GQD models. Noncovalent interaction and atoms in molecular analysis were also used to explain the difference in interaction in each model. Our results highlight that the proportion of the oxygen functional groups has a major role in modulating the sensitivity against TMA, with the hydroxyl group providing the greater sensitivity. This was elucidated through computational simulations, which also explained the lower sensitivity of the other materials. Our work serves as a practical guide, demonstrating the importance of coupling computational and experimental methods to achieve a deeper understanding of sensing results.