ACS Omega最新文献

A series of new monocationic Ru complexes containing phenanthroline derivatives were developed. The monometallic complexes [Ru(κ²-OAc)(dppb)(N,N)]OAc derivatives were synthesized in high yield via the reaction between [Ru(κ²-OAc)₂dppb] and the corresponding N,N ligand. Additionally, dinuclear [(dppb)(κ²-OAc)(Ru(μ-N,N--C,N)Ru(κ²-OAc)(dppb)]OAc complexes were synthesized from equimolar amounts of the appropriate monometallic complex and [Ru(κ²-OAc)₂dppb]. All complexes were characterized by NMR, FTIR, UV–vis spectroscopy, and cyclic voltammetry. These precatalysts display selective catalytic activity toward dehydrogenation of formic acid for H₂ production, with the dinuclear systems demonstrating superior performance, achieving up to 100% conversion under optimized conditions. The dinuclear system maintained consistent TOF₅₀ values through several catalytic cycles, demonstrating excellent stability. Mechanism investigations revealed the formation of two Ru-monohydride species, showing a fac-RuHP₂ and a mer-RuHP₂ arrangement, respectively, formed via substitution of a κ²-OAc by a κ²-O₂CH followed by a β-elimination, where both are involved in the mechanisms. DFT calculations of the species involved in the mechanism showed that fac-RuHP₂ is lower in energy than mer-RuHP₂. The complexes were additionally applied in the transfer hydrogenation of CO₂ to produce formic acid with 2-propanol.

Heterogeneous conglomerate reservoirs are highly complex in petroleum engineering, with varying rock properties and distributions that significantly affect oil and gas extraction. This study investigates the conglomerate oil reservoir of the Lower Wuerhe Formation in Block 8 of the Karamay Oilfield. Physical simulation experiments were conducted to evaluate various development methods, including planar depletion, vertical depletion, water injection, and gas injection. The fluid migration patterns and recovery efficiencies in horizontal wells within these heterogeneous conglomerate reservoirs were analyzed. The results show that the gas injection rate plays a crucial role in stabilizing the gravity-driven front in fractured reservoirs. Lower injection rates slow the front’s migration and delay gas breakthrough, thereby reducing the oil-carrying capacity. High-angle fractures were found to enhance the effectiveness of gas injection. Continuous gas injection with intermittent pauses helps stabilize the gas–liquid interface, promotes pressure diffusion, and expands the affected volume. Gas flooding offers a wider sweep area and higher mobilization compared to water flooding and depletion, improving the recovery efficiency by 36.2% and 50%, respectively. Furthermore, gravity drive significantly enhances sweep efficiency and recovery rates, achieving improvements of 60.9% and 32.8% compared to depletion and water flooding. These findings provide valuable experimental data that can be used to optimize recovery efficiency in heterogeneous conglomerate reservoirs.

Metal–organic frameworks (MOFs) have received widespread attention in various energy related applications due to their unique structural characteristics. Nevertheless, the inherent low electronic conductivity of MOFs is a major limitation for their competitive activity. Herein, we synthesized a self-standing NiFe MOF@Ni₃S₂ core–shell hierarchical heterostructure through using Ni₃S₂ grown on nickel foam (NF) as a semisacrificial template, in which the highly conductive Ni₃S₂ nanosheets core endows the hybrid with rapid charge transfer capability, and the bimetallic NiFe MOF nanosheets provide abundant exposed active sites. Benefiting from the structural and compositional advantages, the enhanced electrocatalytic activity of the as-obtained NiFe MOF@Ni₃S₂/NF has been achieved toward alkaline oxygen evolution reaction (OER). As a result, the NiFe MOF@Ni₃S₂/NF only requires overpotentials of 177 and 219 mV to yield OER current densities of 10 and 100 mA cm^–2, respectively, and exhibits a very small Tafel slope of 24.1 mV dec^–1 and high durability, making it among the most efficient earth-abundant OER catalysts. This study will inspire further construction of MOF-based nanocomposites for applications in electrochemical renewable energy systems.

The development of efficient analytical procedures for environmental applications increasingly relies on electrochemical techniques and their associated systems, which are prized for their high sensitivity, moderate cost, and portability. To overcome the limitations of conventional electrochemical setups, this study introduces an alternative lab-made electrochemical cell design incorporating a flexible reduced graphene oxide/polyaniline (rGO/PAni) composite electrode. The free-standing nanocomposite electrodes based on rGO/PAni, characterized by their high electrical conductivity, thermal stability, and large surface area, were strategically chosen to enhance the electrode performance. This thick, malleable, and easy-to-handle film provides a satisfactory fit with an alternative lab-made electrochemical cell. As a proof-of-concept, this system was successfully applied to the simultaneous detection of multiclass pharmaceutical contaminants─acetaminophen, salicylic acid, and norfloxacin─recognized as emerging environmental pollutants in groundwater samples. The adaptable nature and advantageous properties of the rGO/PAni-based working electrode, coupled with the optimized lab-made cell configuration, demonstrate the potential of this alternative electrochemical system for selective environmental electroanalysis.

The synthesis of cannabidiol (CBD) from limonene derivatives involves a key β-elimination step that remains challenging to reproduce efficiently. In this work, we revisited a known racemic synthetic route to CBD and investigated the mechanistic origin of the low yield associated with the β-hydrogen elimination step. Alternative synthetic approaches were tested experimentally by comparing the traditional selenoxide-mediated pathway with a direct elimination attempt from bromohydrin intermediates. Despite optimization of reaction and workup conditions, β-elimination consistently failed, regenerating epoxide 1 instead of olefin 3. Density functional theory (DFT) calculations revealed that conformational constraints and electronic effects disfavor the reactive rotamer required for β-hydrogen elimination, explaining the experimentally observed lack of reactivity. The results clarify why the selenoxide pathway remains the only viable route to p-mentha-2,8-dien-1-ol (3) and provide mechanistic insight that may guide the development of future selenium-free synthetic methods.

Aflatoxin B1 (AFB1), a highly carcinogenic mycotoxin, poses significant threats to feed safety and human health, even at trace levels. To address the demand for trace detection of AFB1, we proposed a surface-enhanced Raman scattering (SERS) sensor based on photonic crystal microspheres (PCMs) for a wide-range and ultrasensitive quantitative detection of AFB1. This sensor employed SERS nanotags of gold–silver core–shell nanostars embedded with Raman reporter molecules as the enhancement substrate. Its surface protrusions can generate strong plasmon resonance, which further forms extremely intense “hot spots”─a structural feature that renders it significantly superior to spherical nanoparticles in trace detection. Experimental results demonstrate that the developed sensor exhibits an excellent detection performance. Furthermore, benefiting from the unique structural color of PCMs, the sensor is capable of detecting trace amounts of AFB1 in complex matrices. The limit of detection (LOD) reached 0.988 pg/mL, and the linear dynamic range (LDR) was from 1 pg/mL to 100 ng/mL. Additionally, the sensor exhibits excellent specificity, reproducibility, and stability. After 14 days of storage, the sample retained 89.2% of its initial performance. In practical applications, it showed good consistency with commercial enzyme-linked immunosorbent assay (ELISA) kits. All of these results demonstrate that the proposed method has great potential for trace detection and is expected to provide a novel integrated analytical platform with low background, high sensitivity, and a wide detection range for feed safety monitoring.

Physical parameters such as membrane elasticity and solution viscosity in a liquid medium play crucial roles in the effectiveness of drug delivery. Liposome formulations, used in both research and clinical contexts, are usually designed to achieve desired chemical stability, particle size, and drug encapsulation efficiency. However, meeting such requirements may not suffice in order to succeed in in vivo tests, which can be frustrated due to poor evaluation of biomechanical conditions. In this work, we introduce simple biomechanical evaluation protocols that make use of conventional pressure-based liposome extrusion as well as dynamic light scattering results to extract elastic (mechanical) and hydrodynamic (viscosity) properties of colloidal solutions of liposomes. We describe a sequence of analytical steps that need to be carried out in order to obtain macroscopic results that are directly comparable to those of other methods. Two distinct and complementary procedures are presented: the first uses a systematic variation of extrusion pressure, giving access to the viscosity of the solution, and the second being a statistical evaluation of the particle size distribution obtained by dynamic light scattering, providing elasticity constants for liposomal systems. Both methods carry the advantage of generating results for the liposome suspension that will be applied to real systems, thereby offering a more realistic and integrative characterization compared with microscopic techniques that usually present incomplete statistical coverage.

Polymer-derived ceramics (PDCs) technology provides a versatile approach to fabricating ceramics with tailored compositions, microstructures, and properties, wherein pyrolysis methods critically influence the crystallization behavior and microstructure of the derived ceramics. Herein, an ultrafast Joule thermal shock technique was employed for the pyrolysis of a SiC polymeric precursor. This approach enables the accomplishment of ceramization within one second. Compared with conventional tube furnace pyrolysis, Joule thermal shock reduces the free carbon content while increasing the defective carbon content in the resulting ceramics and weakens the limiting effect of free carbon on the growth of ceramic grains, thereby enhancing crystallinity. The crystallite size of the sample treated by Joule thermal shock at 1400 °C reaches 6.6 nm, much larger than the 4.1 nm of the sample pyrolyzed at the same temperature in tube furnace. In addition, the localized hot spot effect during Joule thermal shock leads to a nonuniform grain size distribution in the pyrolysis products, with the presence of a small number of large-sized SiC crystals in the resulting samples. This study reveals the impact of Joule thermal shock technology on the crystallization behavior of SiC ceramics fabricated via PDCs, and further confirms its effectiveness in enhancing the efficiency of PDCs process.