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Enhanced visible-light-driven photocatalytic activity of F doped reduced graphene oxide - Bi <sub/>2</sub> WO <sub/>6</sub> photocatalyst
摘要： The reduced graphene oxide‐Bi2WO6 (rGO‐BWO) photocatalysts with the different RF/O values (molar ratio of the F molar mass and the O's molar mass of Bi2WO6) had been successfully synthesized via one‐step hydrothermal method. The F‐doped rGO‐BWO samples were characterized by X‐ray diffraction patterns (XRD), field‐emission scanning electron microscopy (FE‐ESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller surface area (BET), X‐ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectra (DRS). The results indicate that F ions had been successfully doped into rGO‐BWO samples. With the increasing of the RF/O values from 0 to 2%, the evident change of the morphology and the absorption edges of F‐doped rGO‐BWO samples and the photocatalytic activities had been enhanced. Moreover, the photocatalytic activity of F‐doped rGO‐BWO with RF/O = 0.05 were better than rGO‐BWO and the other F‐doped rGO‐BWO under 500 W Xe lamp light irradiation. The enhanced photocatalytic activity can be attributed to the morphology of the intact microsphere that signify the bigger specific surface area for providing more possible reaction sites for the adsorption–desorption equilibrium of photocatalytic reaction, the introduction of F ions that may cause the enhancement of surface acidity and creation of oxygen vacancies under visible light irradiation, the narrower band gap which means needing less energy for the electron hole pair transition.
关键词： photocatalytic activity,rGO‐Bi2WO6,fluorine doping,hydrothermal method
更新于2025-09-10 09:29:36
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2-(4-Methylsulfonylphenyl)pyrimidines as Prospective Radioligands for Imaging Cyclooxygenase-2 with PET—Synthesis, Triage, and Radiolabeling
摘要： Cyclooxygenase 2 (COX-2) is an inducible enzyme responsible for the conversion of arachidonic acid into the prostaglandins, PGG2 and PGH2. Expression of this enzyme increases in inflammation. Therefore, the development of probes for imaging COX-2 with positron emission tomography (PET) has gained interest because they could be useful for the study of inflammation in vivo, and for aiding anti-inflammatory drug development targeting COX-2. Nonetheless, effective PET radioligands are still lacking. We synthesized eleven COX-2 inhibitors based on a 2(4-methylsulfonylphenyl)pyrimidine core from which we selected three as prospective PET radioligands based on desirable factors, such as high inhibitory potency for COX-2, very low inhibitory potency for COX-1, moderate lipophilicity, and amenability to labeling with a positron-emitter. These inhibitors, namely 6-methoxy-2-(4-(methylsulfonyl)phenyl-N-(thiophen-2ylmethyl)pyrimidin-4-amine (17), the 6-fluoromethyl analogue (20), and the 6-(2-fluoroethoxy) analogue (27), were labeled in useful yields and with high molar activities by treating the 6-hydroxy analogue (26) with [11C]iodomethane, [18F]2-fluorobromoethane, and [d2-18F]fluorobromomethane, respectively. [11C]17, [18F]20, and [d2-18F]27 were readily purified with HPLC and formulated for intravenous injection. These methods allow these radioligands to be produced for comparative evaluation as PET radioligands for measuring COX-2 in healthy rhesus monkey and for assessing their abilities to detect inflammation.
关键词： fluorine-18,COX-2,carbon-11,radioligand
更新于2025-09-09 09:28:46
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Preparation and Surface Properties Study of Novel Fluorine-Containing Methacrylate Polymers for Coating
摘要： A new structural fluorine-containing methacrylate monomer CH2=C(CH3)COOC–(CF3)2CF2CF2CF3 (5) was synthesized derived from perfluoro-2-methyl-2-pentene (D2). A homopolymer of 5 and copolymers of 5 and methacrylate with different alkyl chain length (chain length n = 1, 2, 4, 6, 8, 12, 18) were obtained. These new fluorinated acrylate polymers showed excellent water and oil repellency. The contact angle of the films of the homopolymer and part of the copolymers were similar with the corresponding polymers prepared from CH2=CHC(O)OCH(C3F7)(CF(CF3)2), but greater than that of the C6F13(CF3)CHOC(O)CH=CH2 homopolymer. The structure-property relationship research indicated that the copolymers’ hydrophobicity decreased first and then increased with the increase of alkyl chain length. Td of all the polymers were greater than 220 ?C and Tg fluctuated within the range of ?51~103.8 ?C. Contact angle and Tg could be adjusted by controlling the feed ratio of monomer to meet the requirements of technical indicators in the practical applications. The outstanding liquid repellency and thermal stability make monomer 5 a promising alternative to perfluorinated long-chain fluorosurfactants.
关键词： free radical copolymerization,fluorine-containing methacrylate,thermal property,repellency,fluorocarbon coating
更新于2025-09-09 09:28:46
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Influence of Ba <sup>2+</sup> Consumption and Intermediate Dwelling during Processing of YBa <sub/>2</sub> Cu <sub/>3</sub> O <sub/>7</sub> Nanocomposite Films
摘要： Achieving high critical current densities (Jc) with small artificial pinning centers is a crucial challenge for YBa2Cu3O7-δ (YBCO) nanocomposite thin films fabricated using chemical solution deposition methods. In this work, the YBCO texture, structure purity and its Jc properties were improved by understanding the influence of preformed ZrO2 nanocrystals (Ba2+ consumption) during the nucleation and growth mechanism. This comprehensive study leads to an additional intermediate dwelling step during thermal process to increase the YBCO nuclei density before the YBCO growth, resulting to a self-field Jc of 5-6 MA cm-2 at 77 K for undoped and ZrO2-doped YBCO films. Counter-intuitively, the space and size distribution of the ZrO2 nanocrystals in the YBCO matrix are independent of this intermediate dwelling step.
关键词： vortex pinning,nanocomposite,nanoparticles,low-fluorine YBCO,chemical solution deposition
更新于2025-09-09 09:28:46
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Numerical Investigation for Scale-Up of an Electron Cyclotron Resonance Plasma for Fluorine-Doped Tin Oxide Thin Film Production
摘要： A low-temperature process is required to deposit ?uorine doped tin oxide (FTO) as a transparent conductive oxide on polyethylene terephthalate (PET) substrate, as the latter is polymeric and has a low melting point. An electron cyclotron resonance (ECR) plasma system is the best way to deposit metal oxide with high transparency and electrical conductivity at temperatures below 100 (cid:2)C. Characteristics of an ECR plasma include its high ionization energy and electron density; however, its use is limited in large-scale deposition. In order to overcome this limitation, a large-scale ECR plasma system with a dual microwave generator was designed by numerical investigation of a laboratory-scale ECR plasma system. FTO ?lms prepared in the laboratory-scale and large-scale systems were compared. The change in electrical resistivity and optical transmittance with deposition pressure in the large-scale ECR plasma system with dual linear microwave generator is similar to that observed in the laboratory-scale ECR plasma system. The velocity distribution of active species near the substrate in the large-scale ECR plasma system showed a very similar pattern to that in the laboratory-scale ECR plasma system over a range of 1.5 × 10?2 to 0.8 × 10?2 m/s. The electrical resistivity and optical transmittance of FTO ?lms deposited by a large-scale ECR plasma system using a dual microwave generator had respective values of 4.3 × 10?3 ～ 9.18 × 10?3 (cid:2) · cm and 86.5～88.2%.
关键词： Dual Microwave,ECR Plasma,Electrical Resistivity,Optical Transmittance,Fluorine-Doped Tin Oxide
更新于2025-09-04 15:30:14
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Semi-fluorinated p-terphenyl liquid crystals
摘要： p-Terphenyls carrying two or four fluorine atoms in the central ring were synthesized via Suzuki-Miyaura cross-coupling reaction using phenylboronic acids and fluorinated dibromobenzenes. By calorimetric and X-ray diffraction analyses it was found that the p-terphenyls carrying two fluorine atoms develop nematic and/or smectic (A and C) phases. On the contrary, the p-terphenyls substituted with four fluorine atoms are not liquid crystals. Differences found in the thermal behavior are explained in terms π – πF interactions arising from the electron withdrawing ability of the fluorine atom. Such π – πF interactions let the p-terphenyls stack in a staggered configuration that explains the stability of the smectic C phase. On the other hand, the semi-fluorinated p-terphenyls absorb and emit in the blue region of the electromagnetic spectrum; a measured large Stokes shift indicates that these compounds are nearly transparent to their own emitted light. This optical characteristic, combined with liquid crystals properties of low order, makes these new p-terphenyls potential candidates for linearly polarized blue-emitting layers in electroluminescent devices.
关键词： Fluorescence,Liquid crystal,p-terphenyl,Fluorine
更新于2025-09-04 15:30:14
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Quantitative Determination of Fluorine Content in Blends of Polylactide (PLA)–Talc Using Near Infrared Spectroscopy
摘要： Near-infrared spectroscopy (NIRS) has been widely used for quantitative and/or qualitative determination of a wide range of matrices. The objective of this study was to develop a NIRS method for the quantitative determination of fluorine content in polylactide (PLA)-talc blends. A blending profile was obtained by mixing different amounts of PLA granules and talc powder. The calibration model was built correlating wet chemical data (alkali digestion method) and NIR spectra. Using FT (Fourier Transform)-NIR technique, a Partial Least Squares (PLS) regression model was set-up, in a concentration interval of 0 ppm of pure PLA to 800 ppm of pure talc. Fluorine content prediction (R2 cal = 0.9498; standard error of calibration, SEC = 34.77; standard error of cross-validation, SECV = 46.94) was then externally validated by means of a further 15 independent samples (R2 EX.V = 0.8955; root mean standard error of prediction, RMSEP = 61.08). A positive relationship between an inorganic component as fluorine and NIR signal has been evidenced, and used to obtain quantitative analytical information from the spectra.
关键词： quantitative calibration,fluorine,PLA,polylactide,blends,talc,near infrared spectroscopy
更新于2025-09-04 15:30:14
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Perfluorocarbon‐Based <sup>19</sup> F?MRI Nanoprobes for In?Vivo Multicolor Imaging
摘要： In vivo multicolor imaging is important for monitoring multiple biomolecular or cellular processes in biology. 19F magnetic resonance imaging (MRI) is an emerging in vivo imaging technique because it can non-invasively visualize 19F nuclei without endogenous background signals. Therefore, 19F MRI probes capable of multicolor imaging are in high demand. Herein, we report five types of perfluorocarbon-encapsulated silica nanoparticles that show 19F NMR peaks with different chemical shifts. Three of the nanoprobes, which show spectrally distinct 19F NMR peaks with sufficient sensitivity, were selected for in vivo multicolor 19F MRI. The nanoprobes exhibited 19F MRI signals with three colors in a living mouse. Our in vivo multicolor system could be utilized for evaluating the effect of surface functional groups on the hepatic uptake in a mouse. This novel multicolor imaging technology will be a practical tool for elucidating in vivo biomolecular networks by 19F MRI.
关键词： multicolor imaging,fluorine,magnetic resonance imaging,nanoparticles,imaging agents
更新于2025-09-04 15:30:14
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XPS investigation of F-doped MnO <sub/>2</sub> nanosystems fabricated by plasma assisted-CVD
摘要： Supported Mn(IV) oxide nanomaterials were prepared by plasma assisted-chemical vapor deposition from Ar/O2 plasmas starting from a fluorinated Mn(II) β-diketonate diamine adduct. Under the adopted conditions, the target compound served as a single-source molecular precursor for the obtainment of MnO2 nanosystems uniformly doped with fluorine. The overall F content in the target materials, composed of phase-pure β-MnO2, could be tailored as a function of the deposition temperature from 100 to 400 °C, a result of particular importance in view of photocatalytic and gas sensing applications. In the present study, attention is specifically devoted to the investigation of a representative specimen by means of x-ray photoelectron spectroscopy. Besides the wide scan spectrum, a detailed analysis of C 1s, O 1s, Mn 2p, Mn 3s, and F 1s photoelectron peaks is presented and discussed. The analyses reveal the formation of MnO2 free from other manganese oxides, with fluorine present in different chemical states, i.e., lattice F plus traces of precursor residuals at the system surface.
关键词： fluorine doping,x-ray photoelectron spectroscopy,PA-CVD,manganese oxide
更新于2025-09-04 15:30:14