On the Independence Number of Edge Chromatic Critical Graphs

In 1968, Vizing conjectured that for any edge chromatic critical graph G = (V,E) with maximum degree △ and independence number α (G), α (G) ≤. It is known that α (G) < |V |. In this paper we improve this bound when △≥ 4. Our precise result depends on the number n2 of 2-vertices in G, but in particular we prove that α (G) ≤|V | when △ ≥ 5 and n2 ≤ 2(△− 1

Preparation of hierarchical dandelion-like CuO microspheres with enhanced catalytic performance for dimethyldichlorosilane synthesis

Hierarchical dandelion-like CuO (HD-CuO) microspheres composed of nanoribbons were prepared via a facile hydrothermal method. The samples were characterized by nitrogen adsorption, X-ray diffraction, temperature-programmed reduction, thermogravimetric analysis, transmission electron microscopy and scanning electron microscopy. It was found that the reaction temperature, reaction time and reagent amounts had a significant effect on the morphology and structure of HD-CuO. The obtained HD-CuO microspheres possessed a surface area of 10.6-57.5 m(2) g(-1) and a diameter of 3-6 mu m. In the formation process, ethylene glycol was adsorbed on the surface of the CuO nanoribbons and it acted as the structure-directing agent and thereafter the CuO nanoribbons were self-assembled into HD-CuO. The investigation of the Rochow reaction showed that the HD-CuO catalyst had a better catalytic performance in dimethyldichlorosilane synthesis than the commercial CuO microparticles and commercial CuO-Cu2O-Cu catalyst, owing to its well-developed hierarchically porous structure and higher specific surface area, leading to the increased contact interface among reaction gas, solid catalyst and solid silicon, together with enhanced mass transportation

Synthesis of Superparamagnetic Iron Oxide Nanoparticles Modified with MPEG-PEI via Photochemistry as New MRI Contrast Agent

Novel method for synthesis of superparamagnetic iron oxide nanoparticles (SPIONs) coated with polyethylenimine (PEI) and modified with poly(ethylene glycol) methyl ether (MPEG), MPEG-PEI-SPIONs, was developed. PEI-SPIONs were successfully prepared in aqueous system via photochemistry, and their surface was modified with poly(ethylene glycol) methyl ether (MPEG). The so-obtained MPEG-PEI-SPIONs had a uniform hydrodynamic particle size of 34 nm. The successful coating of MPEG-PEI on the SPIONs was ascertained from FT-IR analysis, and the PEI and MPEG fractions in MPEG-PEI-SPIONs were calculated to account for 31% and 12%, respectively. Magnetic measurement revealed that the saturated magnetization of MPEG-PEI-SPIONs reached 46 emu/g and the nanoparticles showed the characteristic of being superparamagnetic. The stability experiment revealed that the MPEG-PEI modification improved the nanoparticles stability greatly. T2 relaxation measurements showed that MPEG-PEI-SPIONs show similar R2 value to the PEI-SPIONs. The T2-weighted magnetic resonance imaging (MRI) of MPEG-PEI-SPIONs showed that the magnetic resonance signal was enhanced significantly with increasing nanoparticle concentration in water. These results indicated that the MPEG-PEI-SPIONs had great potential for application in MRI

RSC Adv.

Urchin-like ZnO microspheres were successfully prepared by thermal decomposition of hydrozincite synthesized via homogeneous precipitation of zinc nitrate and urea in the presence of a nonionic surfactant polyethylene glycol. The synthesis conditions, such as reaction temperature and time, precursor concentration, and the amount of surfactant added, as well as the catalytic properties of urchin-like ZnO microspheres as promoters for a commercial copper catalyst in dimethyldichlorosilane synthesis were investigated. In addition, the formation mechanism of urchin-like microspheres from hydrozincite to ZnO was proposed. The ZnO samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and N-2 adsorption. It was found that zinc nitrate concentration and the amount of surfactant are the key factors that lead to the formation of urchin-like ZnO microspheres. These ZnO samples had BET surface areas of 16-30 m(2) g(-1) and an average diameter of 3-8 mu m. Compared with commercial Zn microspheres and ZnO nanoparticles, urchin-like ZnO microspheres showed a better performance in dimethyldichlorosilane synthesis via the Rochow reaction due to their larger surface area, which created more interfacial contacts with the copper catalyst and active Cu3Si species. The work is helpful for developing novel catalyst promoters and understanding the role of the promoter in the Rochow reaction.Urchin-like ZnO microspheres were successfully prepared by thermal decomposition of hydrozincite synthesized via homogeneous precipitation of zinc nitrate and urea in the presence of a nonionic surfactant polyethylene glycol. The synthesis conditions, such as reaction temperature and time, precursor concentration, and the amount of surfactant added, as well as the catalytic properties of urchin-like ZnO microspheres as promoters for a commercial copper catalyst in dimethyldichlorosilane synthesis were investigated. In addition, the formation mechanism of urchin-like microspheres from hydrozincite to ZnO was proposed. The ZnO samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and N-2 adsorption. It was found that zinc nitrate concentration and the amount of surfactant are the key factors that lead to the formation of urchin-like ZnO microspheres. These ZnO samples had BET surface areas of 16-30 m(2) g(-1) and an average diameter of 3-8 mu m. Compared with commercial Zn microspheres and ZnO nanoparticles, urchin-like ZnO microspheres showed a better performance in dimethyldichlorosilane synthesis via the Rochow reaction due to their larger surface area, which created more interfacial contacts with the copper catalyst and active Cu3Si species. The work is helpful for developing novel catalyst promoters and understanding the role of the promoter in the Rochow reaction

Partially Reduced CuO Nanoparticles as Multicomponent Cu-Based Catalysts for the Rochow Reaction

We report the application of partially reduced CuO nanoparticles as Cu-based catalysts for dimethyldichlorosilane (M2) synthesis via the Rochow reaction. The CuO nanoparticles (50-100 nm) were synthesized by a simple precipitation method and partially reduced in a H-2/N-2 mixture gas to obtain the Cu-based catalyst containing different Cu species of CuO, Cu2O, and Cu. It was found that the composition of the samples could be tailored by varying the volume ratio of H-2/N-2 at the given reduction temperature and time. Compared to the synthesized CuO and Cu nanoparticles, as well as the commercial CuO microparticles, these multicomponent Cu-based catalysts, particularly for the CuO-Cu2O-Cu catalyst, showed much higher M2 selectivity and Si conversion in the Rochow reaction. The enhanced catalytic performance is attributed to the smaller particle size and the synergistic effect among the different components. The work would help to develop novel ternary Cu-based catalysts for organosilane synthesis

Solvothermal synthesis of copper (I) chloride microcrystals with different morphologies as copper-based catalysts for dimethyldichlorosilane synthesis

CuCl microcrystals with different morphologies such as tetrahedra, etched tetrahedra, tripod dendrites, and tetrapods were synthesized using CuCl2.2H(2)0 as the copper precursor in the mixed solvent of acetylacetone and ethylene glycol. The samples were characterized with X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and transmission electron microscope. Cu(C5H7O2)(2) was identified as the key intermediate, and the morphology and structure of the CuCI microcrystals were highly dependent on the reaction time and temperature, as well as the volume of the solvents. The catalytic properties of these CuCI microcrystals were explored in the dimethyldichlorosilane synthesis via Rochow reaction. Compared to the commercial CuCl microparticles with irregular morphology and dense internal structure, the obtained CuCl microcrystals possessed regular morphology and different exposed crystal planes and showed much higher dimethyldichlorosilane selectivity and Si conversion via the Rochow reaction because of the enhanced formation of active CuxSi phase and gas transportation within the dendritic structure, demonstrating the significance of regular morphology of the copper-based catalysts in catalytic organosilane synthesis. (C) 2013 Elsevier Inc. All rights reserved

A folic acid-functionalized dual-emissive nanoprobe for “double-check” luminescence imaging of cancer cells

Development of luminescent probes for rapid and effective discrimination and detection of cancer cells has the potential to address the current challenges in early diagnosis and treatment monitoring of cancer diseases. In this work, we report the preparation of a unique folic acid (FA)-functionalized dual-emissive nanoprobe, CTMR@BHHBCB-Eu-FA, for steady-state and time-gated luminescence “double-check” imaging of cancer cells. The nanoprobe was engineered by covalently doping two luminescent dyes, 5-carboxytetramethylrhodamine (CTMR) and BHHBCB-Eu, in core and shell of silica nanoparticles, followed by surface modification of the nanoparticles with FA, a cancer cell-targeting molecule. As-prepared nanoprobe is monodisperse and highly stable in buffer displaying two strong emissions, short-lived emission from CTMR at 584 nm and long-lived emission from BHHBCB-Eu at 612 nm. The nanoprobe is biocompatible, and can specifically recognize folate receptor (FR)-overexpressed cancer cells through the FA-FR binding interaction. Using the nanoprobe, the “double-check” imaging of HeLa cells was successfully achieved at steady-state and time-gated luminescence modes, indicating the capability of the nanoprobe for cancer cell imaging

Flower-like ZnO grown on urchin-like CuO microspheres for catalytic synthesis of dimethyldichlorosilane

We report the rational growth of flower-like ZnO on urchin-like CuO (f-ZnO@u-CuO) microspheres via a facile solvothermal method using copper nitrate and zinc nitrate as precursors in the presence of sodium nitrate and ethanol. A formation mechanism was proposed based on the observation of a series of reaction intermediates. The samples were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma optical emission spectrometer, and temperature-programmed reduction. It was found that the morphology of the samples was highly dependent on the synthesis conditions, particularly the reaction time and the ammonia amount added. As a copper-based catalyst for dimethyldichlorosilane synthesis via the Rochow reaction, f-ZnO@u-CuO microspheres show better catalytic performance than the Cu-based catalysts physically mixed with ZnO promoter, probably because of the well-developed p-n heterojunction structures at the CuO and ZnO interfaces that generate a much strong synergistic effect. The work provides a simple method to synthesize hierarchical CuO/ZnO composites and would be helpful for understanding the catalytic mechanism of the Rochow reaction

Exploring the Underlying Mechanisms of Qingxing Granules Treating H1N1 Influenza Based on Network Pharmacology and Experimental Validation

Background: H1N1 is one of the major subtypes of influenza A virus (IAV) that causes seasonal influenza, posing a serious threat to human health. A traditional Chinese medicine combination called Qingxing granules (QX) is utilized clinically to treat epidemic influenza. However, its chemical components are complex, and the potential pharmacological mechanisms are still unknown. Methods: QX’s effective components were gathered from the TCMSP database based on two criteria: drug-likeness (DL ≥ 0.18) and oral bioavailability (OB ≥ 30%). SwissADME was used to predict potential targets of effective components, and Cytoscape was used to create a “Herb-Component-Target” network for QX. In addition, targets associated with H1N1 were gathered from the databases GeneCards, OMIM, and GEO. Targets associated with autophagy were retrieved from the KEGG, HAMdb, and HADb databases. Intersection targets for QX, H1N1 influenza, and autophagy were identified using Venn diagrams. Afterward, key targets were screened using Cytoscape’s protein–protein interaction networks built using the database STRING. Biological functions and signaling pathways of overlapping targets were observed through GO analysis and KEGG enrichment analysis. The main chemical components of QX were determined by high-performance liquid chromatography (HPLC), followed by molecular docking. Finally, the mechanism of QX in treating H1N1 was validated through animal experiments. Results: A total of 786 potential targets and 91 effective components of QX were identified. There were 5420 targets related to H1N1 and 821 autophagy-related targets. The intersection of all targets of QX, H1N1, and autophagy yielded 75 intersecting targets. Ultimately, 10 core targets were selected: BCL2, CASP3, NFKB1, MTOR, JUN, TNF, HSP90AA1, EGFR, HIF1A, and MAPK3. Identification of the main chemical components of QX by HPLC resulted in the separation of seven marker ingredients within 195 min, which are amygdalin, puerarin, baicalin, phillyrin, wogonoside, baicalein, and wogonin. Molecular docking results showed that BCL2, CASP3, NFKB1, and MTOR could bind well with the compounds. In animal studies, QX reduced the degenerative alterations in the lung tissue of H1N1-infected mice by upregulating the expression of p-mTOR/mTOR and p62 and downregulating the expression of LC3, which inhibited autophagy. Conclusions: According to this study’s network pharmacology analysis and experimental confirmation, QX may be able to treat H1N1 infection by regulating autophagy, lowering the expression of LC3, and increasing the expression of p62 and p-mTOR/mTOR