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Inspired by biological channels, achieving precise separation of ion/water and ion/ion requires finely tuned pore sizes at molecular dimensions and deliberate exposure of charged groups. Covalent organic frameworks (COFs), a class of porous crystalline materials, offer well-defined nanoscale pores and diverse structures, making them excellent candidates for nanofluidic channels that facilitate ion and water transport. In this study, we perform molecular simulations to investigate the structure and kinetics of water and ions confined within the typical COFs with varied exposure of charged groups. The COFs exhibit vertically arrayed nanochannels, enabling diffusion coefficients of water molecules within COFs to remain within the same order of magnitude as in the bulk. The motion of water molecules manifests in two distinct modes, creating a mobile hydration layer around acid groups. The ion diffusion within COFs displays a notable disparity between monovalent (M+) and divalent (M2+) cations. As a result, the selectivity of M+/M2+ can exceed 100, while differentiation among M+ is less pronounced. In addition, our simulations indicate a high rejection (R > 98%) in COFs, indicating their potential as ideal materials for desalination. The chemical flexibility of COFs indicates that would hold significant promise as candidates for advanced artificial ion channels and separation membranes. [ABSTRACT FROM AUTHOR]

Underground coal gasification (UCG) is a promising option for the recovery of low-rank and inaccessible coal resources. Detailed mineralogical information is essential to understand underground reaction conditions far from the surface and optimize the operation parameters during the UCG process. It is also significant in identifying the environmental effects of UCG residue. In this paper, with regard to the underground gasification of lignite, UCG slag was prepared through simulation tests of oxygen-enriched gasification under different atmospheric conditions, and the minerals were identified by X-Ray diffraction (XRD) and a scanning electron microscope coupled to an energy-dispersive spectrometer (SEM-EDS). Thermodynamic calculations performed using FactSage 6.4 were used to help to understand the transformation of minerals. The results indicate that an increased oxygen concentration is beneficial to the reformation of mineral crystal after ash fusion and the resulting crystal structures of minerals also tend to be more orderly. The dominant minerals in 60%-O2 and 80%-O2 UCG slag include anorthite, pyroxene, and gehlenite, while amorphous substances almost disappear. In addition, with increasing oxygen content, mullite might react with the calcium oxide existed in the slag to generate anorthite, which could then serve as a calcium source for the formation of gehlenite. In 80%-O2 UCG slag, the iron-bearing mineral is transformed from sekaninaite to pyroxene.

Essential oil of Chinese medicinal herb, Chenopodium ambrosioides aerial parts was found to possess nematicidal activity against the root-knot nematodes, Meloidogyne incognita. The essential oil of C. ambrosioides was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 27 components of the essential oil were identified. The principal compounds in C. ambrosioides essential oil were (Z)-ascaridole (27.27%), ρ-cymene (19.05%), isoascaridole (14.75%), α-pinene (6.33%) and α-terpinene (5.12%). Bioactivity-guided chromatographic separation of the essential oil on repeated silica gel columns led to isolate three volatile components ((Z)-ascaridole, ρ-cymene and isoascaridole) from the essential oil. The essential oil and (Z)-ascaridole exhibited strong nematicidal activity against M. incognita with LC50 values of 49.55 μg/mL and 32.79 μg/mL, respectively. ρ-Cymene and isoascaridole also possessed nematicidal activity against M. incognita with LC50 values of 435.89 μg/mL and 1323.51 μg/mL, respectively but weaker than the crude essential oil.

Developing n-butanol gas sensors that are simple, stable, sensitive, and humidity-resistant is very important. WO2.72 nanomaterials have the potential to detect volatile organic compounds (VOCs) due to the abundance of oxygen vacancies and excellent thermal stability. Unfortunately, gas sensors prepared with only WO2.72 nanomaterials have the disadvantages of low sensitivity, poor humidity resistance ability, and slower response–recovery rate. In this study, CeO2 nanoparticle-modified WO2.72 nanoflowers (WO2.72–x wt% CeO2) with unique morphologies were synthesized by the solvothermal method and ultrasonic stirring treatment. Characterization results show that the WO2.72–10 wt% CeO2 sample was found to possess a larger specific surface area (SBET) and considerably more oxygen vacancies as compared to the other samples. Then, the n-butanol gas sensors were fabricated using WO2.72–x wt% CeO2 samples. As compared with other sensors, it was found that the WO2.72–10 wt% CeO2 sensor responded to as high as 103.9 to 50 ppm concentration of n-butanol at 160 °C. Due to the special electronic structure of the rare earth element Ce, the humidity resistance of the WO2.72–10 wt% CeO2 sensor was much improved. Additionally, the WO2.72–10 wt% CeO2 sensor exhibited a fast response/recovery time (31/78 s) for n-butanol, and the response values remained virtually the same in 5 repetitions and in 15 days stability tests. [ABSTRACT FROM AUTHOR]

A highly efficient carbonylation of aryl halides using half‐sandwich iridium catalysis was developed, providing a new avenue for synthesizing carboxylic ester derivatives and yielding consistently impressive results. These iridium complexes demonstrated remarkable catalytic performance in the coupling reaction using phenyl formate derivatives as the source of CO, phenol, and aryl halides as the starting material in the presence of air and possessed good air and moisture stability properties. Ester products with different substituents were synthesized at low reaction temperatures without the need for an inert atmosphere, leading to high yields. The broad substrate scope, impressive catalytic activity, and mild reaction conditions suggest promising industrial applications for this catalytic system. The desired metal complexes 1–4 have been well proven by attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR), nuclear magnetic resonance (NMR), and elemental analysis (EA). The molecular structure of the cyclometalated iridium complexes 2 and 3 was proven through X‐ray crystallography. Additionally, the possible mechanism of this Ir‐catalyzed process is further supported by the density functional theory (DFT) study. [ABSTRACT FROM AUTHOR]

In order to study the extraction process by ethanol with the ultrasonic-assisted method of chlorogenic acid in Senecio scandens Buch-Ham. With the content of chlorogenic acid as the index, the effects of ethanol concentration, ultrasonic extraction temperature, extraction time, and material liquid ratio on the extraction rate of chlorogenic acid from Senecio scandens Buch-Ham. were investigated through a single factor experiment. On this basis, the process parameters of chlorogenic acid extraction were optimized by response surface methodology. The results showed that the optimal process parameters were as follows: Ethanol concentration of 50%, ultrasonic temperature of 47 °C, extraction time of 50 min, and liquid material ratio of 20 mL/g. Under these conditions, the extraction rate of chlorogenic acid could reach 1.01%. The study shows that the extraction process determined by the experiment is simple and efficient, which can provide a reference for further purification and extraction of chlorogenic acid in Senecio scandens Buch-Ham. [ABSTRACT FROM AUTHOR]

Utilizing ambient pressure X-ray photoelectron spectroscopy (AP-XPS), the surface segregation and oxidation of Pt3Ni(1 1 1) alloys are investigated as a function of temperature and oxygen pressure. The in situ AP-XPS measurements of oxygen oxidation process show that the Pt "skin" surface is not stable under the exposure of oxygen pressure of 100 mTorr at room temperature. As the temperature and pressure are elevated, the formations of Ni2O3, NiOx, and NiO are observed on surface while Pt atom starts to reduce its adsorbed oxygen, which is a clear sign of surface segregation of Ni to surface. Upon the evacuation of oxygen gas, i.e. ultrahigh vacuum condition, both of NiOx and NiO oxide get reduced and Ni2O3 remains on the surface. The DFT calculation is employed to explain the formation of surface oxides under oxidation condition.