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991.
Giovanni D'Orazio Javier Hernández‐Borges María Asensio‐Ramos Miguel Ángel Rodríguez‐Delgado Salvatore Fanali 《Electrophoresis》2016,37(2):356-362
Nano‐LC and CEC were coupled to MS through a nanospray or a pressurized liquid‐junction interface for the simultaneous separation and determination of 11 estrogenic compounds. Different stationary phases, that is, phenyl, C18, and C18 bidentate silica hydrate, were studied. For both techniques, the phenyl stationary phase was the best option, considering separation efficiency, selectivity, and resolution. Under the optimized conditions, the baseline separation of the target compounds (including estradiol and zearalanol epimers) was achieved in less than 20 min in nano‐LC‐MS and less than 13 min in CEC‐MS. Molecular imprinted polymer SPE was used for extracting the target compounds from mineral water samples with the analysis of nano‐LC‐MS. The whole molecular imprinted polymer SPE nano‐LC‐MS method was validated through a recovery study at two levels of concentration. Sensitivity was improved by on‐column focusing technique obtaining LODs in the range 1.4–55.4 ng/L. 相似文献
992.
Najeeb Ur Rehman Hidayat Hussain Samia Ahmed Al‐Riyami René Csuk Mohammed Khiat Ghulam Abbas Ahmed Al‐Rawahi Ivan R. Green Ishtiaq Ahmed Ahmed Al‐Harrasi 《Helvetica chimica acta》2016,99(8):632-635
One new diacylglycoside named lyciumaside ( 1 ) and a new sesquiterpene lactone named lyciumate ( 2 ) were isolated from Lycium shawii Roem . & Schult . The structures of the two new compounds were elucidated based on 1D‐ (1H‐ and 13C‐NMR and NOE) and 2D‐NMR (COSY, HSQC, and HMBC) spectroscopic techniques, and mass spectrometry (ESI‐MS). Preliminary evaluations demonstrated lyciumaside ( 1 ) possesses strong antioxidant activity with an IC50 = 30 μg/ml (80% inhibition) while it was inactive in α‐glucosidase and urease enzymes assays. 相似文献
993.
Miguel A. F. de Souza Elizete Ventura Silmar A. do Monte José M. Riveros Ricardo L. Longo 《Journal of computational chemistry》2016,37(8):701-711
A number of model Diels‐Alder (D‐A) cycloaddition reactions (H2C?CH2 + cyclopentadiene and H2C?CHX + 1,3‐butadiene, with X = H, F, CH3, OH, CN, NH2, and NO) were studied by static (transition state ‐ TS and IRC) and dynamics (quasiclassical trajectories) approaches to establish the (a)synchronous character of the concerted mechanism. The use of static criteria, such as the asymmetry of the TS geometry, for classifying and quantifying the (a)synchronicity of the concerted D‐A reaction mechanism is shown to be severely limited and to provide contradictory results and conclusions when compared to the dynamics approach. The time elapsed between the events is shown to be a more reliable and unbiased criterion and all the studied D‐A reactions, except for the case of H2C?CHNO, are classified as synchronous, despite the gradual and quite distinct degrees of (a)symmetry of the TS structures. © 2015 Wiley Periodicals, Inc. 相似文献
994.
Ferrocenyl,Alkyl, and Aryl‐Pyrido[2,3‐d]Pyrimidines as Vasorelaxant of Smooth Muscle of Rat Aorta via cAMP Conservation Through Phosphodiesterase Inhibition 下载免费PDF全文
Ivonne Arellano Fernando Rodríguez‐Ramos Martín González‐Andrade Andrés Navarrete Manju Sharma Noé Rosas Pankaj Sharma 《Journal of heterocyclic chemistry》2016,53(4):1147-1154
New pyrido[2,3‐d]pyrimidines 11 , 12 , 13 , and 21 have been synthesized. The vasorelaxant effect on smooth muscle isolated from rat aorta, via PDEs inhibition, of these compounds along with other pyrido[2,3‐d]pyrimidines 14 , 15 , 16 , 17 , 18 , 19 , 20 reported earlier by our group, has also been determined. These pyrido[2,3‐d]pyrimidines 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 were synthesized by the reaction of ferrocenyl‐ethynyl ketones ( 1 , 2 , 3 , 4 ) or α‐alkynyl ketones ( 5 , 6 , 7 , 8 , 9 , 10 ) with 6‐amino‐1,3‐dimethyluracil using [Ni(CN)4]?4 as an active catalytic species, formed in situ in a Ni(CN)2/NaOH/H2O/CO/KCN aqueous system. Evaluation of the vasorelaxant effect of compounds 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 demonstrated that all compounds relax the tissue in a concentration‐dependent manner. The structural changes do not alter the effectiveness; however, there are differences related to potency expressed as EC50. Compounds 12 (7‐ferrocenyl‐1,3‐dimethyl‐5‐(m‐tolyl)‐pyrido[2,3‐d]pyrimidine) and 13 (7‐ferrocenyl‐1,3‐dipropyl‐5‐(4‐metoxyphenyl)‐pyrido[2,3‐d]pyrimidine) were the most potent compounds, even more than rolipram, reference drug; the EC50 was 0.41 ± 0.02 μM and 0.81 ± 0.11 μM for 12 and 13 , correspondingly. The EC50 of compounds 15 (7‐ferrocenyl‐1,3‐dimethyl‐5‐phenyl‐pyrido[2,3‐d]pyrimidine), 14 (7‐ferrocenyl‐5‐(3,5‐dimethoxyphenyl)‐1,3‐dimethylpyrido[2,3‐d]pyrimidine), and 19 (5‐n‐butyl‐7‐ethyl‐1,3‐dimethylpyrido[2,3‐d]pyrimidine) was similar to EC50 of rolipram. Compounds 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 significantly induce concentration‐dependent vasorelaxation in endothelium‐intact aortic rings. In addition, the relaxation responses to each compound in either endothelium‐intact or endothelium denuded aortic rings were comparable, suggesting that removal of the functional endothelium has no significant influence on its intrinsic vasorelaxant activity. In vitro capability of conserving cyclic‐AMP or cyclic‐GMP (adenosine and guanosine 3′, 5′‐cyclic monophosphate) via PDE inhibition for compounds 12 , 13 , 14 , 15 and 19 was evaluated. Compounds 15 and 19 show the highest percent inhibition effect (94.83% and 83.98%, respectively) for the decomposition of c‐AMP. Docking studies showed that the compound 15 was selective for the inhibition of PDE‐4. 相似文献
995.
Perin Gelson Silva Cristian M. Borges Elton L. Duarte José E. G. Goulart Helen A. Silva Rafaela B. Schumacher Ricardo F. 《Research on Chemical Intermediates》2016,42(6):5873-5885
Research on Chemical Intermediates - We describe a simple and rapid method for selective synthesis of 4-thiomethyl-1,3-dioxolan-2-ones promoted by KF/Al2O3 using PEG-400 as solvent under microwave... 相似文献
996.
Maria N. Tamaño‐Machiavello Benjamin Bracke Carlos M. Costa Senentxu Lanceros‐Mendez Roser Sabater i Serra José Luis Gómez Ribelles 《Journal of Polymer Science.Polymer Physics》2016,54(6):672-679
Polymer blend membranes have been obtained consisting of a hydrophilic and a hydrophobic polymers distributed in co‐continuous phases. In order to obtain stable membranes in aqueous environments, the hydrophilic phase is formed by a poly(hydrohyethyl acrylate), PHEA, network while the hydrophobic phase is formed by poly(vinylidene fluoride‐co‐trifluoroethylene) P(VDF‐TrFE). To obtain the composites, in a first stage, P(VDF‐TrFE) is blended with poly(ethylene oxyde) (PEO), the latter used as sacrificial porogen. P(VDF‐TrFE)/PEO blend membranes were prepared by solvent casting at 70°C followed by cooling to room temperature. Then PEO is removed from the membrane by immersion in water obtaining a P(VDF‐TrFE) porous membrane. After removing of the PEO polymer, a P(VDF‐TrFE) membrane results in which pores are collapsed. Nevertheless the pores reopen when a mixture of hydroxethyl acrylate (HEA) monomer, ethyleneglycol dimethacrylate (as crosslinker) and ethanol (as diluent) is absorbed in the membrane and subsequent polymerization yields hybrid hydrophilic/hydrophobic membranes with controlled porosity. The membranes are thus suitable for lithium‐ion battery separator membranes and/or biostable supports for cell culture in biomedical applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 672–679 相似文献
997.
André Arnebold Florian Plander Karsten Thiel Stefanie Wellmann Andreas Hartwig 《Journal of Polymer Science.Polymer Physics》2016,54(21):2188-2199
Structure–property relations of cationically polymerized epoxy thermosets with different morphologies are examined. The morphology adjustment of amorphous epoxy based copolymers and partially crystalline polymer alloys is carried out with star‐shaped poly(ε‐caprolactone) (SPCL) bearing various numbers of hydroxyl end groups. These hydroxyl groups are known for their reactivity toward epoxides following the activated monomer (AM) mechanism. For this reason, four‐armed SPCL was synthesized with four hydroxyl end groups (SPCL‐tetraol) and, in addition, with successively esterified ones down to a SPCL with four ester end groups (SPCL‐tetraester). SPCL species bearing fewer or no hydroxyl end groups segregate into needle‐like nanodomains within the epoxy networks and, if the concentration is high enough, also into crystalline domains. The stronger phase separation of SPCL‐tetraester within the epoxy network compared with SPCL‐tetraol is due to a reduction of the AM mechanism. The mechanical properties resulting from different morphologies lead to a trade‐off between higher storage moduli and Tg values in the case of the more phase separated (and partially crystalline) polymer alloys and higher strain at break in the case of the amorphous copolymers. Nevertheless, in both cases toughness is improved or at least kept on the same level as for the pure epoxy resin. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2188–2199 相似文献
998.
Juan M. Álvarez Álvaro Raya‐Barón Pedro M. Nieto Luis E. Cuca Alberto Fernández‐Gutiérrez Ignacio Fernández 《Magnetic resonance in chemistry : MRC》2016,54(9):718-728
Two flavonoid glycosides derived from rhamnopyranoside ( 1 ) and arabinofuranoside ( 2 ) have been isolated from leaves of Persea caerulea for the first time. The structures of 1 and 2 have been established by 1H NMR, 13C NMR, and IR spectroscopy, together with LC–ESI–TOF and LC–ESI–IT MS spectrometry. From the MS and MS/MS data, the molecular weights of the intact molecules as well as those of quercetin and kaempferol together with their sugar moieties were deduced. The NMR data provided information on the identity of the compounds, as well as the α and β configurations and the position of the glycosides on quercetin and kaempferol. We have also explored the application of sodium dodecyl sulfate (SDS) normal micelles in binary aqueous solution, at a range of concentrations, to the diffusion resolution of these two glycosides, by the application of matrix‐assisted diffusion ordered spectroscopy (DOSY) and pulse field gradient spin echo (PGSE) methodologies, showing that SDS micelles offer a significant resolution which can, in part, be rationalized in terms of differing degrees of hydrophobicity, amphiphilicity, and steric effects. In addition, intra‐residue and inter‐residue proton–proton distances using nuclear Overhauser effect build‐up curves were used to elucidate the conformational preferences of these two flavonoid glycosides when interacting with the micelles. By the combination of both diffusion and nuclear Overhauser spectroscopy techniques, the average location site of kaempferol and quercetin glycosides has been postulated, with the former exhibiting a clear insertion into the interior of the SDS‐micelle, whereas the latter is placed closer to the surface. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
999.
Dressings Loaded with Cyclodextrin–Hamamelitannin Complexes Increase Staphylococcus aureus Susceptibility Toward Antibiotics Both in Single as well as in Mixed Biofilm Communities 下载免费PDF全文
Gilles Brackman Maria José Garcia‐Fernandez Joke Lenoir Laurens De Meyer Jean‐Paul Remon Thomas De Beer Angel Concheiro Carmen Alvarez‐Lorenzo Tom Coenye 《Macromolecular bioscience》2016,16(6):859-869
Bacteria reside within biofilms at the infection site, making them extremely difficult to eradicate with conventional wound care products. Bacteria use quorum sensing (QS) systems to regulate biofilm formation, and QS inhibitors (QSIs) have been proposed as promising antibiofilm agents. Despite this, few antimicrobial therapies that interfere with QS exist. Nontoxic hydroxypropyl‐β‐cyclodextrin‐functionalized cellulose gauzes releasing a burst of the antibiotic vancomycin and the QSI hamamelitannin are developed, followed by a sustained release of both. The gauzes affect QS and biofilm formation of Pseudomonas aeruginosa and Staphylococcus aureus in an in vitro model of chronic wound infection and can be considered as candidates to be used to prevent wound infection as well as treat infected wounds.
1000.
Amilton Martins dos Santos Jordan Pohn Muriel Lansalot Franck D'Agosto 《Macromolecular rapid communications》2007,28(12):1325-1332
Hydrophilic (co)polymers carrying a thiocarbonyl thio end group such as poly(dimethylaminoethyl methacrylate), poly(ethylene oxide), and poly(ethylene oxide)‐block‐poly(dimethylaminoethyl methacrylate) have been evaluated as precursors of stabilizers in batch ab initio emulsion polymerization of styrene under acidic conditions to form electrosterically stabilized polystyrene latex particles. As a mixture of P(DMAEMA/H+Cl−)‐RAFT and PEO‐RAFT failed to give satisfactory results, PEO‐RAFT was used as a control agent for the RAFT polymerization of DMAEMA, and the resulting block copolymer was successfully used in ab initio styrene emulsion polymerization.