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Elisabete M.S. Castanheira Ana S. Abreu Maria-Joo R.P. Queiroz Paula M.T. Ferreira Paulo J.G. Coutinho Nair Nazareth M. So-Jos Nascimento 《Journal of photochemistry and photobiology. A, Chemistry》2009,206(2-3):220-226
Fluorescence properties of the antitumoral methyl 3-(benzo[b]thien-2-yl)-benzothieno[3,2-b]pyrrole-2-carboxylate (BTP) were studied in solution and in lipid bilayers of dipalmitoyl phosphatidylcholine (DPPC), dioleoyl phosphatidylethanolamine (DOPE) and egg yolk phosphatidylcholine (Egg-PC). BTP presents good fluorescence quantum yields in all solvents studied (0.20 ≤ ΦF ≤ 0.32) and a bathochromic shift in polar solvents. The results indicate an ICT character of the excited state, with an estimated dipole moment of μe = 7.38 D.Fluorescence (steady-state) anisotropy measurements of BTP incorporated in lipid membranes of DPPC, DOPE and Egg-PC indicate that this compound is deeply located in the lipid bilayer, feeling the difference between the rigid gel phase and fluid phases.BTP inhibits the growth of three human tumour cell lines, MCF-7 (breast adenocarcinoma), SF-268 (glioma) and NCI-H460 (non-small cell lung cancer), being significantly more potent against the NCI-H460 tumour cells. 相似文献
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Numerous organic and inorganic laboratory standards were gathered from nine European and North American laboratories and were analyzed for their delta(18)O values with a new on-line high temperature pyrolysis system that was calibrated using Vienna standard mean ocean water (VSMOW) and standard light Antartic precipitation (SLAP) internationally distributed reference water samples. Especially for organic materials, discrepancies between reported and measured values were high, ranging up to 2 per thousand. The reasons for these discrepancies are discussed and the need for an exact and reliable calibration of existing reference materials, as well as for the establishment of additional organic and inorganic reference materials is stressed. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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A review is presented of the calculation of photoionization spectra, particularly in the spectral range where electron autoionization of diatomic molecules takes place. In addition to some interesting results obtained over years that compare favourably with experiment, the emphasis here is put on the relation between the methods developed for the calculation of observables associated with the continuum energy spectrum of the electrons and the Alchemy system of programs. This system of programs serves as a basis for initial and intermediate calculations. The examples presented show that diatomic molecules not only in gas phase but also oriented in space or physisorbed at surfaces may be studied readily. 相似文献
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Larry Nazareth 《Mathematical Programming》1984,30(1):99-104
We describe a variational principle based upon minimizing the extent to which the inverse hessian approximation, sayH, violates the quasi-Newton relation, on the step immediately prior to the step used to constructH. Its application to the case when line searches are exact suggests use of the BFGS update.
This paper is based upon results first presented at the 1979 Mathematical Programming Symposium. Montreal, Canada. 相似文献
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The Lagrangian globalization (LG) method for non-linear equation-solving proposed in [10] is developed through theoretical analysis, the formulation of a particular LG algorithm, and a numerical illustration. New merit functions (termed detour potentials) for non-linear equation-solving, which broaden the LG concept, are also defined. 相似文献
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K H?kansson RA Zubarev RV Coorey VL Talrose P H?kansson 《Rapid communications in mass spectrometry : RCM》1999,13(12):1169-1174
An HMX/insulin two-layer system was chosen as a model for further investigation of the matrix properties of explosive materials for protein analytes in plasma desorption mass spectrometry. The dependencies of the molecular ion yield and average charge state as a function of the analyte thickness were studied. An increase in the charge state of multiply protonated molecular species was confirmed as the major matrix effect, with the average charge state z at the smallest thickness studied being higher than in matrix-assisted laser desorption/ionization and closer to the value obtained in electrospray ionization under standard acidic conditions. Observed charge state distributions are significantly narrower than the corresponding Poisson distributions, which suggests that the protonation of insulin is limited in plasma desorption by the number of basic sites in the molecule, similar to electrospray ionization. Both the curve displaying total molecular ion yield and the one showing the total charge (proton) yield as a function of the insulin thickness have maxima at a thickness different from an insulin monolayer. These observations diminish the significance of a matrix/analyte interface mechanism for the explosive matrix assistance. Instead, a mechanism related to the chemical energy release during conversion of the explosive after the ion impact is proposed. As additional mechanisms, enhanced protonation of the analyte through collisions with products of the explosive decay is considered, as well as electron scavenging by other products, which leads to a higher survival probability of positively charged protein molecular ions. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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Surface‐initiated nitroxide‐mediated polymerization of sodium 4‐styrene sulfonate from latex particles
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Claude St Thomas Judith Nazareth Cabello‐Romero Omar Garcia‐Valdez Enrique Javier Jiménez‐Regalado Hortensia Maldonado‐Textle Ramiro Guerrero‐Santos 《Journal of polymer science. Part A, Polymer chemistry》2017,55(3):437-444
In this study, we report the use of a double‐headed dialkoxyamine trithiocarbonate ( I ) capable of acting as chain transfer agent via reversible addition‐fragmentation chain transfer polymerization or as initiator via nitroxide‐mediated polymerization. It is worth mentioning that I was revealed as an effective dual chain transfer agent in the synthesis of multiblock copolymers via bulk and emulsion processes. In this article, we report the employing of I in dispersed systems to obtain amphiphilic multiblock copolymers and latexes. In this case, a water soluble macroagent of PAA previously synthetized was used in disperse media using a mixture of methanol/water (70:30, w/w). Stable latexes were obtained via polymerization‐induced self‐assembly and surface‐initiated polymerization of SSNa from alkoxyamine‐functionalized latex PAA‐b‐PS‐b‐PAA was also obtained © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 437–444 相似文献
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H. İBRAHİM UĞRAŞ ÜMİT ÇAKIR AKIN AZİZOĞLU TURGUT KILIÇ ÇAKIL ERK 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(1-2):159-165
Hexadecanoyl, dihexadecanoyl, dioctadecaneoyl, di-10-undecenoyl, and dicis-9-octadecenoyl derivatives of benzo[18]crown-6, dibenzo[18]crown-6 and dibenzo[24]-8 were synthesized by the condensation of carboxylic acids (palmitic, stearic, oleic and undecenoic acid) with benzo and dibenzo crown ethers in the presence of zinc chloride. The extraction equilibrium constants of such macrocyclic ethers with long side chains were estimated using chloroform/water and dichloromethane/water membranes transfer of Na-PAR (4-(2-pyridylazo)-resorcinol mono sodium monohydrate) with UV–Vis spectroscopy. It was found that they were in the range of 10.88–11.71 in dichloromethane and 8.04–11.77 in chloroform. These results actually show that the Na+ binding effect of macrocyclic ethers depends on the type and the length of side chains. The geometrical properties of the molecules were studied employing semi-empirical calculations by simulated annealing technique. The frontier molecular orbital energies and dipole moments were also examined. The biological activity results showed that the synthesized crown ethers have no activity against the studied microorganisms. 相似文献