Search results for "ether"
showing 10 items of 986 documents
Identification and quantification of carotenoids including geometrical isomers in fruit and vegetable juices by liquid chromatography with ultraviole…
2004
A method was established for the identification and quantification of carotenoids including geometrical isomers in fruit and vegetable juices by liquid chromatography with an ultraviolet−diode array detector, using a C18 Vydac 201TP54 column. The mobile phase used was the ternary methanol mixture (0.1 M ammonium acetate), tert-butyl methyl ether and water, in a concentration gradient, and a temperature gradient was applied. Retinol palmitate was added as an internal standard. An extraction process (ethanol/hexane, 4:3, v/v) was performed, followed by saponification with diethyl ether/methanolic KOH (0.1%, w/v, BHT) (1:1, v/v) for 0.5 h at room temperature. Seventeen different (cis and trans…
Resorcinarene bis-crown silver complexes and their application as antibacterial Langmuir-Blodgett films
2012
Silver complexes of a cation binding supramolecular host, resorcinarene bis-crown (CNBC5) with propyl, nonyl, decyl and undecyl alkyl chains were investigated by NMR titration, picrate extraction and single crystal X-ray diffraction. Binding studies showed that both 1 : 1 and 1 : 2 (host-Ag(+)) complexes are present in solution with only a slight effect of the lower rim alkyl chain length on the binding constants (log K 4.0-4.2 for 1 : 2 complexes). Solid state complexes of the resorcinarene bis-crowns bearing either C(3) or C(11) chains were obtained. Single crystal X-ray analyses showed that both derivatives bind silver ions by metal-arene and Ag···O coordination from the crown ether brid…
Oxidative Stress, Induced by Sub-Lethal Doses of BDE 209, Promotes Energy Management and Cell Cycle Modulation in the Marine Fish Cell Line SAF-1
2019
The effects of sub-lethal doses of polybrominated diphenyl ether (PBDE)-209 in terms of toxicity, oxidative stress, and biomarkers were evaluated in the Sparus aurata fibroblast cell line (SAF-1). Vitality and oxidative stress status were studied after incubation with PBDE for 72 h. Concomitantly, the quantification of proteins related to cell cycle and DNA repair (p53), cell proliferation (extracellular signal&ndash
Sub-lethal doses of polybrominated diphenyl ethers affect some biomarkers involved in energy balance and cell cycle, via oxidative stress in the mari…
2019
Abstract Polybrominated diphenyl ethers (PBDEs) are a class of persistent contaminants which are found all over the world in the marine environment. Sparus aurata fibroblast cell line (SAF-1) was exposed to increasing concentrations of PBDEs 47 and 99, until 72 h to evaluate the cytotoxicity, reactive oxygen species (ROS) production and the expression of some selected molecular markers related to cell cycle, cell signaling, energetic balance and oxidative stress (p53, erk-1, hif-1α and nrf-2), by real-time PCR. Furthermore, SAF-1 cells were exposed for 7 and 15 days to sub-lethal concentrations, in order to evaluate the response of some biomarkers by immunoblotting (p53, ERK-1, AMPK, HIF-1α…
Modification of the rate of formation and surface area of ettringite by polycarboxylate ether superplasticizers during early C3A–CaSO4 hydration
2015
Abstract Early C3A–CaSO4 hydration was studied in the presence of various amounts of two polycarboxylate ether superplasticizers differing in their grafting degree. Hydration and surface area developments were investigated by in-situ NMR relaxometry coupled with BET and DSC during the first 2 h after mixing. This study enables a quantitative comparison of the amount and the specific surface area of the ettringite precipitated along the C3A–CaSO4 hydration with or without PCE. The main effect of PCE is to strongly increase ettringite specific area for a variable period. These effects are clearly dependent on the PCE charge and dosage and are reduced when using delayed addition. In this conte…
Preferential solvation of poly(methyl methacrylate) and a bisphenol A diglycidyl ether by size-exclusion chromatography
2004
The preferential adsorption coefficient, lambda, of poly(methyl methacrylate), PMMA, in solutions formed by an epoxy resin in tetrahydrofuran (THF), was studied by size-exclusion chromatography (SEC). Only PMMA of lowest molar mass was preferentially solvated by epoxy but at low concentrations of epoxy in the mixture. At higher epoxy content PMMA was preferentially solvated by THF. A simultaneous and competitive solvation between the specific interactions PMMA-epoxy and the self association of epoxy at high concentrations would be the responsible of this inversion point. The more compacted coil of PMMA of higher molecular weights in solution could explain the lack of interaction of these po…
Determination of bisphenol diglycidyl ether residues in canned foods by pressurized liquid extraction and liquid chromatography–tandem mass spectrome…
2005
Abstract A new confirmatory method for simultaneous determination of bisphenol diglycidyl ether residues (BADGE, BADGE·H2O, BADGE·2H2O, BADGE·H2O·HCl, BADGE·HCl, BADGE·2HCl, BFDGE and BFDGE·2HCl) from canned food has been developed. The proposed method includes extraction by pressurized liquid extraction (PLE) followed by liquid–liquid partition and purification by solid phase extraction (SPE). Several solvent systems and different operating conditions (time, temperature) have been investigated for PLE optimization. A reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to atmospheric pressure chemical ionisation tandem mass spectrometry (APCI-MS–MS) method was developed …
1,3-Dipolar cycloaddition of diaryldiazomethanes across N-ethoxy-carbonyl-N-(2,2,2-trichloroethylidene)amine and reactivity of the resulting 2-azabut…
2016
Abstract 1,3-dipolar cycloaddition of diaryldiazomethanes Ar2C N2 across Cl3C–CH N–CO2Et 1 yields Δ3-1,2,4-triazolines 2. Thermolysis of 2 leads, via transient azomethine ylides 3, to diaryldichloroazabutadienes [Ar(Ar')C N–CH CCl2] 4. Treatment of 4a (Ar = Ar' = C6H5) and 4c (Ar = Ar' = p-ClC6H4) with NaSR in DMF yields 2-azabutadienes [Ar2C N–C(H) C(SR)2] 5. In contrast, nucleophilic attack of NaStBu on 4 affords azadienic dithioethers [Ar2C N–C(StBu) C(H)(StBu)] (7a Ar = C6H5; 7b Ar' = p-ClC6H4). The reaction of 4a with NaSEt conducted in neat EtSH produces [Ph2C N–C(H)(SEt)–CCl2H] 8, which after dehydrochloration by NaOMe and subsequent addition of NaSEt is converted to [Ph2C N–C(SEt) C…
17O NMR study of chlorinated anisoles
1988
The 17O NMR chemical shifts of anisole and all 19 chlorinated anisoles measured in CDCI3 at ambient temperature show a dispersion of approximately 40 ppm. The substituent chemical shifts (SCS) of di- or more highly chlorinated compounds cannot be reproduced by addition of single substituent effects. Theoretical calculations of the 17O NMR chemical shifts have been attempted by molecular mechanical and semi-empirical molecular orbital methods at the INDO level, but the results are not satisfactory.
Mass spectra of chlorinated aromatics formed in pulp bleaching: I—chlorinated catechols
1983
The fragmentation of chlorinated guaiacols (2-methoxyphenols) on electron impact has been studied. The most common fragmentation processes are interpreted and in some cases the small differences between spectra of positional isomers are explained. In addition to the well-known alkyl-oxygen fission (loss of methyl radical), metastable ion studies and deuterium labelling have indicated several new fragmentation pathways. The most characteristic are the formation of [MCH3HCl]+ and [MCH3Cl]+· ions. In general, however, the spectra of positional isomers are shown to be very similar.