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61.
The separation and measurement of actinides by ion chromatography (IC) coupled with on-line scintillation detection was investigated. Separation of (237)Np, (239)Pu, (241)Am, (244)Cm, (230)Th, and (233)U was accomplished using a Dionex CG5 guard column, CS5 separation column, and an elution program utilizing oxalic, diglycolic, and nitric acid eluents. Np(V) was eluted as a weak anionic oxalate complex or as free NpO(2)(+) cation, Am(III) and Cm(III) as anionic oxalate complexes, Pu(IV) and Th(IV) as nonionic diglycolate complexes, and U(VI) as a free uranyl cation. Response of the flow-cell detector was linear over the full range of activities tested (4-1500 Bq). The minimum detectable activities for the investigated analytes ranged from 3.6 Bq for (244)Cm to 5.4 Bq for (230)Th and (239)Pu. The corresponding minimum detectable concentrations based on a 1-L sample ranged from 3.6 to 5.4 KBq m(-3) (96 to 150 pCi L(-1)). 相似文献
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Raíssa Volpatto Marques Stefania Enza Sestito Frdric Bourgaud Sissi Miguel Frdric Cailotto Pascal Reboul Jean-Yves Jouzeau Sophie Rahuel-Clermont Sandrine Boschi-Muller Henrik Toft Simonsen David Moulin 《Molecules (Basel, Switzerland)》2022,27(6)
Bryophytes produce rare and bioactive compounds with a broad range of therapeutic potential, and many species are reported in ethnomedicinal uses. However, only a few studies have investigated their potential as natural anti-inflammatory drug candidate compounds. The present study investigates the anti-inflammatory effects of thirty-two species of bryophytes, including mosses and liverworts, on Raw 264.7 murine macrophages stimulated with lipopolysaccharide (LPS) or recombinant human peroxiredoxin (hPrx1). The 70% ethanol extracts of bryophytes were screened for their potential to reduce the production of nitric oxide (NO), an important pro-inflammatory mediator. Among the analyzed extracts, two moss species significantly inhibited LPS-induced NO production without cytotoxic effects. The bioactive extracts of Dicranum majus and Thuidium delicatulum inhibited NO production in a concentration-dependent manner with IC50 values of 1.04 and 1.54 µg/mL, respectively. The crude 70% ethanol and ethyl acetate extracts were then partitioned with different solvents in increasing order of polarity (n-hexane, diethyl ether, chloroform, ethyl acetate, and n-butanol). The fractions were screened for their inhibitory effects on NO production stimulated with LPS at 1 ng/mL or 10 ng/mL. The NO production levels were significantly affected by the fractions of decreasing polarity such as n-hexane and diethyl ether ones. Therefore, the potential of these extracts to inhibit the LPS-induced NO pathway suggests their effective properties in attenuating inflammation and could represent a perspective for the development of innovative therapeutic agents. 相似文献
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Grach G Santos JS Lohier JF Mojovic L Plé N Turck A Reboul V Metzner P 《The Journal of organic chemistry》2006,71(26):9572-9579
(S)-tert-Butylsulfinylferrocene was submitted to ortho-metalation, and the corresponding lithium derivative was trapped by alkyl or aryl imines bearing various electron-withdrawing groups on the nitrogen atom (Ts, Dpp, Boc). New aminosulfoxides were obtained with complete diastereocontrol when Dpp or Boc groups were used. The absolute configuration (SS,SFc,S) has been determined by single-crystal X-ray analysis and chemical correlation. An unusual pseudocyclic boatlike transition state has been proposed to explain the stereochemical course of this reaction. 相似文献
66.
Emeline AV Zhang X Jin M Murakami T Fujishima A 《The journal of physical chemistry. B》2006,110(14):7409-7413
We report for the first time an experimental application of the concept of a "black body" like reactor to measure quantum yields (Phi) of photochemical reactions in liquid-solid heterogeneous systems. A major advantage of this new method is its simplicity since the fractions of reflected and transmitted light are negligible due to reactor geometry and high optical density of the heterogeneous systems. The average quantum yield of a test reaction (phenol photodegradation) over TiO(2) (Degussa P25) as determined by this method was 0.14, identical to the quantum yield measured earlier for this same reaction under similar conditions by Salinaro and Serpone. We also report the quantum yield of phenol photodegradation over N-doped TiO(2) during photoexcitation at the fundamental absorption band (lambda = 365 nm; Phi = 0.12) and at the N-doping induced extrinsic absorption band (lambda = 436 nm; Phi = 0.08) of the photocatalyst. 相似文献
67.
Effect of bio‐based monomers on the scratch resistance of acrylate photopolymerizable coatings 下载免费PDF全文
Emeline Prandato Sébastien Livi Michel Melas Justine Auclair Vincent Verney Etienne Fleury Françoise Méchin 《Journal of Polymer Science.Polymer Physics》2015,53(5):379-388
Photopolymerizable clear coatings based on bio‐sourced acrylates, dedicated to the protection of polycarbonate substrates, were studied. The bio‐sourced compounds were not based on triglycerides but were smaller, industrially available molecules similar to classical petro‐based monomers. Their polymerization kinetics was studied by photo‐DSC and was shown to allow high acrylate conversions even at 25 °C. Closely related coatings enriched in alkyl segments, or in monoacrylates to decrease the crosslinking density, were compared. The material composition affects its nanomorphology deduced from X‐ray diffraction. Although these changes in composition can slightly shift the mechanical relaxation, it remains wide, and the elastic modulus remains high (>108 Pa) for all the tested materials. Microscratch experiments highlighted the efficiency of all the new coatings in terms of protection against scratches. Incorporating a monoacrylate, particularly isobornyl acrylate, can improve the scratch resistance especially in terms of critical load (up to 175% increase compared with a classical petro‐based coating). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 379–388 相似文献
68.
Two efficient syntheses of 1,4-benzothiazepines, substituted in the positions 2 and 5, have been achieved either by a ring expansion reaction of cyclic sulfenamides with methylpropiolate or tosylacetylene catalyzed by pyridine, via a postulated allenolate intermediate; or by an α-sulfenylation reaction promoted by diethylamine and a subsequent acid catalyzed condensation reaction. 相似文献
69.
Daniela Saviello Emeline Pouyet Lucia Toniolo Marine Cotte Austin Nevin 《Analytica chimica acta》2014
Synchrotron-based Fourier transform infrared micro-spectroscopy (SR-μFTIR) was used to map photo-oxidative degradation of acrylonitrile–butadiene–styrene (ABS) and to investigate the presence and the migration of additives in historical samples from important Italian design objects. High resolution (3 × 3 μm2) molecular maps were obtained by FTIR microspectroscopy in transmission mode, using a new method for the preparation of polymer thin sections. The depth of photo-oxidation in samples was evaluated and accompanied by the formation of ketones, aldehydes, esters, and unsaturated carbonyl compounds. This study demonstrates selective surface oxidation and a probable passivation of material against further degradation. In polymer fragments from design objects made of ABS from the 1960s, UV-stabilizers were detected and mapped, and microscopic inclusions of proteinaceous material were identified and mapped for the first time. 相似文献
70.
Emeline Bessard Olivier De Almeida Gérard Bernhart 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1669-1678
A differential generalized Avrami’s law is used to model crystallization kinetic of PEEK in considering that PEEK crystallization results from the contribution of two distinct mechanisms. The form of this equation allows to predict with good accuracy both isothermal and non-isothermal crystallization kinetics. Nevertheless, isothermal model parameters are not entirely satisfactory for predicting non-isothermal crystallization and the identification of kinetic parameters is needed for both isothermal and non-isothermal cases. The results show that the Avrami exponents and Arrhenius activation energies remain constant for both conditions and therefore suggest that these parameters are only material dependent. On the other hand, the other kinetic parameters depend on the crystallization condition and vary with temperature and/or cooling rate. 相似文献