Vascular endothelial and smooth muscle cell culture on NaOH-treated poly(epsilon-caprolactone) films: a preliminary study for vascular graft development

Tissue engineering offers the potential of providing vessels that can be used to replace diseased and damaged native blood vessels. The endothelization of a synthetic vascular graft minimizes the failures associated with blood clotting and platelet activation. The aim of this study was to culture vascular-derived endothelial and smooth muscle cells on both untreated and NaOH-treated poly(epsilon-caprolactone) (PCL) films, a biocompatible and bio-resorbable polymer, and to evaluate the behavior of both cell types as a preliminary study for vascular graft development. PCL films were prepared by hot pressing; characterized by DSC, IR, SEM, and scanning force microscopy; and treated with NaOH to increase the surface hydrophilicity before cell culture. Endothelial and smooth muscle cells, isolated from pig cava vein, were characterized by immunofluorescence and confocal microscopy studies of endothelial nitric oxide synthase and alpha-smooth muscle actin. Good adhesion, growth, viability and morphology of both the endothelial and smooth muscle cells on PCL films were obtained, but a light stimulation of mitochondrial activity was observed during short culture times. NaOH treatment improved the adhesion and enhanced the proliferation in both cell types. This verified the possible use of this modified polymer as a support in the preparation of a synthetic vascular graft. [Diagram: see text] SEM micrograph of smooth muscle cells cultured on NaOH-treated PCL film. (Original magnification: 1000x).     

Benzo[d]-1,2-oxaphospholes as precursors of stabilized C-centered radicals

[reaction: see text] Several benzo[d]-1,2-oxaphosphole 2-oxides were examined as potential precursors of stabilized C-centered radicals. The transient absorption spectra obtained after laser flash photolysis in the presence of di-tert-butyl peroxide showed the features of benzylic radicals with formation and decay kinetics not significantly influenced by the presence of oxygen. In the case of compounds with two possible diastereomeric forms, the C-H bond of the trans-isomers [corrected] is more reactive toward hydrogen abstraction.     

Density and Speed of Sound for Binary Mixtures of a Cyclic Ether with a Butanol Isomer

Densities and speeds of sound of the binary mixtures 1,3-dioxolane + 1-butanol, 1,3-dioxolane + 2-butanol, 1,4-dioxane + 1-butanol, and 1,4-dioxane + 2-butanol have been measured at 25 and 40°C. The excess molar volumes and excess isentropic compressibility coefficients were calculated from experimental data and fitted to a Redlich–Kister polynomial function. Results were analyzed in terms of molecular interactions and compared with literature data.     

Determination of ageing time of spirits in oak barrels using a headspace–mass spectrometry (HS-MS) electronic nose system and multivariate calibration

The aromatic composition of sugar cane spirits and, in general, of alcoholic beverages, is mainly influenced by the ageing process in wood barrels. There are several factors that affect the quality of the final aged product, but the time of the storage in the barrel is perhaps the most important one. Ageing time must therefore be controlled in order to detect counterfeits; however, this parameter is very difficult to control and, at present, there is no analytical method available to determine it. We propose a quantitative method for determining the ageing time of sugar cane spirits in oak barrels by using an electronic nose based on coupling directly a headspace sampler to a mass spectrometer (HS-MS), and multivariate calibration. The method developed is simple and provides, in 5 min, the ageing time of spirits with an accuracy of about 1 month.     

Intramolecular charge transfer in pyrromethene laser dyes: photophysical behaviour of PM650.

Absorption and fluorescence (steady-state and time-correlated) techniques are used to study the photophysical characteristics of the pyrromethene 650 (PM650) dye. The presence of the cyano group at the 8 position considerably shifts the absorption and fluorescence bands to lower energies with respect to other related pyrromethene dyes; this is attributed to the strong electron-acceptor character of the cyano group, as is theoretically confirmed by quantum mechanical methods. The fluorescence properties of PM650 are intensively solvent-dependent. The fluorescence band is shifted to lower energies in polar/protic solutions, and the evolution of the corresponding wavelength with the solvent is analysed by a multicomponent linear regression. The fluorescence quantum yield and the lifetime strongly decrease in polar/protic solvents, which can be ascribed to an extra nonradiative deactivation, via an intramolecular charge-transfer state (ICT state), favoured in polar media.     

The role of steric and electronic interactions in the stereocontrol of the asymmetric 1,3-dipolar reactions of 5-ethoxy-3-p-(S)-tolylsulfinylfuran-2(5H)-ones with diazoalkanes: theoretical calculations and experimental evidences

The addition of diazomethane and diazoethane to (5S,SS)- and (5R,SS)-5-ethoxy-3-p-tolylsulfinylfuran-2(5H)-ones (1a and 1b) and their 4-methylderivatives (2a and 2b) proceeded in almost quantitative yields and complete regioselectivity. The observed pi-facial selectivity is determined by the configurations at both C-5 and the sulfinyl group, the later being the most important. The syn adducts were almost exclusively obtained from 1a and 2a in apolar solvents but the pi-facial selectivity was strongly decreased in more polar solvents. On the other hand, the major adducts from 1b and 2b were the anti ones and such predominance was slightly increased with solvent polarity. The exo-selectivity was complete in all the cases except for the anti approach to compounds 2a (in polar solvents) and 2b. The role of the sulfinyl group in this behavior was inferred by comparison of these results with those obtained in reactions of diazoalkanes with 5-methoxyfuran-2(5H)-one (3). Steric interactions seem to be the main ones responsible for the observed exo selectivity of reactions with diazoethane, but electronic factors, which can be modulated by the solvent, are also significant in the pi-facial selectivity control. DFT computational methods are able to correctly predict the reactivity, regioselectivity, and pi-facial selectivity exhibited by 5-alkoxyfuranones as well as their changes with the solvent polarity. A C-H.O hydrogen bond, involving the oxygen atom of the 5-alkoxy group at dipolarophiles and the endo-hydrogen atom at dipoles, seems to play a key role in the electronic interactions influencing the stereochemical course of these reactions.     

Reaction of mercury(II) and xylenol orange-I Effect of the buffering media

The influence of the buffering medium on the reaction of Hg(II) with Xylenol Orange has been studied. Amine-type compounds are complexed by Hg(II)/Xylenol Orange with a sharp hyperchromic effect on the reagent itself, at 590 nm, but complex formation of Hg(II)/Xylenol Orange in non-amine-type buffer, such as citric acid-phosphate, gives a hypochromic effect on Xylenol Orange at 580 nm. Hg(II) is determined at pH 7.5 in two ranges of concentration, 2-9 ppm in citrate buffer, measured at 580 nm ( = 2.50 x 10(4)), and 6-11 ppm in hexamine buffer, at 590 nm ( = 4.18 x 10(4)).     

Application of ultra-low level liquid scintillation to the determination of 222Rn in groundwater

A procedure for the determination of ²²²Rn in environmental water samples using liquid scintillation counting (LSC) was applied. The extractive scintillator RADONS^Ò and an ultra-low background 1220 QuantulusÔ were used. A minimum detectable activity of 0.1 Bq·l^?1 in 20 ml was found with low-diffusion polyethylene vials and 200 minute measurement time. Quenching effects and possible interferences due to the existence of other radionuclides in the extraction process were studied. The procedure was controlled by gamma-ray spectrometry of the ²²²Rn daughters. Applications to environmental samples collected from spas, wells, and public springs in Extremadura (Spain) are presented.     

Setting up of recovery profiles: A tool to perform the compliance with recovery requirements for residue analysis

The use of the recovery term has presented some confusion in Analytical Chemistry. Recent IUPAC recommendations propose to distinguish between two terms: recovery or recovery factor, ℜ, and apparent recovery, ℜ*. Apparent recovery includes recovery factor and a new recovery term proposed in this paper, named calibration recovery, ℜ^C, which depends of the type of systematic error due to the matrix effect (constant and/or proportional) and is related to the applied calibration methodology. This paper highlights the dependence of the calibration recovery on the sample analyte concentration and, for extension, of the apparent recovery, defines the recovery profile, and makes evident the need to determine a “fit for purpose” analyte concentration interval to comply with a regulated recovery requirements. An approach to estimate the calibration recovery and its associated uncertainty in relation to the above-mentioned dependence is presented. The usefulness of the proposed methodology has been shown in the quantification of a pesticide by GC-ECD for assessing dermal exposure.     

Intercalation of 1,2-Alkanediols into α-Zirconium Hydrogenphosphate

Intercalation compounds of α-Zr(HPO₄)₂ · H₂O with 1,2-alkanediols (from C3 to C16) have been prepared by replacing 1-propanol in α-Zr(HPO₄)₂ · 2C₃H₇OH with the desired 1,2-alkanediols by a treatment in a microwave field. It was found that the intercalates contain 1.5 molecules of diol per formula unit. The diol molecules are placed between the host layers in a bimolecular way with their aliphatic chains tilted at an angle of 51°. The diol molecules are anchored in the interlayer space by H-bonds. A mixed intercalate, containing 1,2-butanediol and 1,2-decanediol in a roughly equimolar ratio, is formed when the α-Zr(HPO₄)₂ · 2C₃H₇OH intercalate, suspended in a mixture of 1,2-butanediol and 1,2-decanediol, is exposed to microwave radiation. No new phase containing both types of the guest molecules was observed when the 1-propanol intercalate, suspended in a mixture of 1-propanol and 1,2-octanediol, is exposed to microwave radiation.