A radical cascade decarboxylation/cyclization of 2-isocyanobiphenyls with aliphatic carboxylic acids as well as aromatic carboxylic acids under the transition metal-free conditions was reported. This ...process, which included formation of two new C–C bonds and cleavage of C–COOH bonds, afforded a novel and environmentally friendly approach to producing 6-alkyl/aryl phenanthridines with moderate to good yields.
In this work, the effect of doubly functionalized montmorillonite (MMT) on the structure, morphology, thermal, and tribological characteristics of the resulting polystyrene (PS) nanocomposites was ...investigated. The modification of the MMT was performed using a cationic surfactant and an anionic surfactant or a silane coupling agent to increase the compatibility with PS matrix. The polystyrene/organo-montmorillonite (PS/OMMT) nanocomposite particles were prepared by soap-free emulsion polymerization. The OMMT was studied using Fourier-transform infrared (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The structural and morphological changes of PS/OMMT nanocomposites were further characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The thermal stability of all the PS/OMMT nanocomposites was higher than that of the pure PS. The anti-wear properties of the polyalphaolefin (PAO) were significantly improved due to the introduction of the PS/OMMT nanocomposite particles. The nanocomposites prepared by a cationic surfactant and a silane coupling agent exhibited the best thermal stability and tribological performance. Our results provide the valuable insights needed to guide the design of lubrication and friction reducing materials.
The system of gas-liquid two-phase bubbly flows is widely found in many industrial fields, such as nuclear energy, chemical, petroleum, and refrigeration. Bubbly two-phase flows measuring including ...detection and tracking affects the specific engineering problem solving to a great extent. The particle tracking velocity (PTV) algorithm is generally used for the tracking of the particles in the flow field. However, it does not take the shape change of particles into account in the process of flow. In this paper, a kind of bubble feature matching method based on ORB algorithm is proposed, and the edge detection method of findContours in OpenCV is used to extract the bubble contour in the image. The proposed algorithm implements the trajectory tracking of the bubbles with shape change when moving up in liquid. The feasibility of bubble trajectory tracking is shown by displaying of different bubble tracks in the plan, 3D plots and contour changing plots.
In this research, a novel amphiphilic hydrophobically associative polymer nanocomposite (ADOS/OMMT) was prepared using acrylamide (AM), sodium 4-vinylbenzenesulfonate (SSS), N, N′-dimethyl octadeyl ...allyl ammonium bromide (DOAAB) and organo-modified montmorillonite (OMMT) through
in situ
polymerization. Both X-ray diffraction patterns and transmission electron microscopy images verified the dispersion morphology of OMMT in the copolymer matrix. Then, the effect of the introduction of OMMT layers on the copolymer properties was studied by comparing with pure copolymer AM/SSS/DOAAB (ADOS). The thermal degradation results demonstrated that the thermal stability of the ADOS/OMMT were better than pure copolymer ADOS. During the solution properties tests, ADOS/OMMT nanocomposite was superior to ADOS in viscosifying ability, temperature resistance, salt tolerance, shear resistance and viscoelasticity, which was because OMMT contributed to enhance the hydrophobic association structure formed between polymer molecules. Additionally, the ADOS/OMMT nanocomposite exhibited more excellent interfacial activity and crude oil emulsifiability in comparison to pure copolymer ADOS. These performances indicated ADOS/OMMT nanocomposite had good application prospects in tertiary recovery.
The objective of this study was to investigate the effect of three different treatments on the morphology, microstructure, and the thermal characteristics of a montmorillonite (Mt) sample, by using ...hydrochloric acid (HCl), tributyl tetradecyl phosphonium chloride (TTPC) surfactant, and γ-methacryloxypropyltrimethoxysilane (γ-MPS). The resultant nanofillers were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption analysis, X-ray fluorescence spectrometry (XRF), and thermogravimetric analysis (TGA). The results showed that the amount of chemical grafting of the γ-MPS was increased after the acid treatment, whereas the amount of intercalation of the TTPC surfactant was decreased. The preintercalation of TTPC or silylation of γ-MPS, for the Mt sample, had a certain hindrance effect on its subsequent silylation or intercalation treatments. Furthermore, the effect of four different nanofillers on the thermal stability properties of the polystyrene (PS) matrix were also investigated. The results showed an increase in thermal stability for the triple-functionalized Mt, compared with the double-functionalized samples. The onset decomposition temperatures and the maximum mass loss temperatures of the PS nanocomposites were increased by 27 °C and 32 °C, respectively, by the incorporation of triple-modified Mt, as a result of the good exfoliation and dispersion of the nanolayers, more favorable polymer–nanofiller interaction, as well as the formation of a more remarkable tortuous pathway in the continuous matrix.
Polystyrene-organo-montmorillonite (PS-OMMT) nanocomposite particles were prepared via emulsion polymerization of styrene in the presence of montmorillonite modified with an anionic surfactant, ...sodium lauryl sulfonate (SLS), and its tribological properties as an additive to polyalphaolefin (PAO) were tested. The results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) showed that SLS molecules resided in the montmorillonite (MMT) interlayer space. The effects of OMMT on the morphology and properties of the nanocomposites were also investigated. Gel permeation chromatography (GPC) and dynamic light scattering (DLS) demonstrate that the presence of OMMT can effectively reduce the average molecular weight and average particle size of PS. XRD and transmission electron microscopy (TEM) of the PS-OMMT nanocomposites indicate that exfoliated and intercalated structures form and that the MMT layers either are partly embedded inside the PS particles or remain on their surface. Compared with pure PS, the PS-OMMT nanocomposites possessed higher stability to thermal decomposition and higher glass transition temperatures. Adding nanocomposite particles reduces the friction coefficient, and thus, the antiwear properties of the PAO are significantly improved. The PS-OMMT-3 (3 wt % of OMMT based on styrene) particles have the best tribological performance and maintained a stable, very low coefficient of friction of 0.09.
An efficient and practical synthetic route toward chiral matsutakeol and analogs was developed by asymmetric addition of terminal alkyne to aldehydes. (
)-matsutakeol and other flavored substances ...were feasibly synthesized from various alkylaldehydes in high yield (up to 49.5%, in three steps) and excellent enantiomeric excess (up to >99%). The protocols may serve as an alternative asymmetric synthetic method for active small-molecule library of natural fatty acid metabolites and analogs. These chiral allyl alcohols are prepared for food analysis and screening insect attractants.
Viral myocarditis in children (VMCC) is a severe condition that requires effective treatment options. Astragalus membranaceus Injection (AMI) has been widely used for the treatment of VMCC and has ...shown promising results. In light of this, we conducted an overview of systematic reviews (OoSRs) and meta-analyses of randomized controlled trials (RCTs) to provide a comprehensive summary of the available evidence regarding the efficacy and safety of AMI in treating VMCC.
We conducted a thorough search of 8 databases up until November 18th, 2022 to identify all systematic reviews (SRs) pertaining to the use of AMI for VMCC. We assessed the methodology quality, report quality, and evidence quality of the retrieved SRs using the AMSTAR-2, PRISMA, and GRADE frameworks. For meta-analysis, we used either a fixed-effects or a random-effects model to calculate effect sizes and 95% confidence intervals (CI) with Stata version 12.0, based on the number of original trials. We presented general results in evidence maps utilizing bubble plots.
A total of 4 SRs, comprising 115 RCTs and 9048 patients, were determined to be eligible for inclusion in OoSRs. Our findings revealed moderate-certainty evidence that combining AMI with western medicine (WM) improved the effective rate, cure rate and electrocardiogram results, while reducing creatine kinase, creatine kinase-MB, and lactate dehydrogenase levels for VMCC compared to the WM group. Furthermore, combination therapy did not increase adverse drug reactionsRR=0.79, 95%CI (0.44, 1.40), P>0.05 for VMCC. Evidence maps demonstrated that combining AMI with WM was more advantageous for treating VMCC.
AMI is a valuable therapeutic option for VMCC, demonstrating remarkable efficacy and a favorable safety profile. However, to confirm these findings and determine the optimal dosing and administration regimens, further prospective studies are necessary. Our work provides a foundation for future research on this topic. While our findings support the effectiveness and safety of combining AMI with WM for treating VMCC, caution should be exercised in interpreting these results due to the quality of the current literature. Larger-scale, well-designed studies are necessary to confirm the results and provide high-quality evidence.
To advance the management and outcomes of VMCC within the context of Chinese medicine, our study highlights the need for ongoing research efforts in this area. We believe that additional research will expand our understanding of the mechanisms underlying the effects of AMI and WM on VMCC, and ultimately benefit patients with this condition.
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Separation of the enantiomers of new chiral alkynes in strategic syntheses and bioorthogonal studies is always problematic. The chiral column high-performance liquid chromatography (HPLC) method in ...general could not be directly used to resolve such substrates, since the differentiation of the alkyne segment with the other alkane/alkene segment is not significant in the stationary phase, and the alkyne group is not a good UV chromophore. Usually, a pre-column derivatization reaction with a tedious workup procedure is needed. Making use of easily-prepared stable alkyne-cobalt-complexes, we developed a simple and general method by analyzing the in situ generated cobalt-complex of chiral alkynes using chiral column HPLC. This new method is especially suitable for the alkynes without chromophores and other derivable groups.
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