DISTRIBUTION OF DI-SULFONATED ALUMINUM PHTHALOCYANINE AND PHOTOFRIN II IN LIVING CELLS: A COMPARATIVE FLUOROMETRIC STUDY

Microspectrofluorometric and fluorescence imaging techniques have been employed to study the internalization and intracellular distribution of both Photofrin II, an experimental drug used in photodynamic therapy, and di-sulfonated aluminum phthalocyanine, a very promising photosensitizer. The results obtained by microscopic techniques in living cells have been compared with those obtained in solution on cell extracts. Experimental results indicated that the complexity of the drug-cell interaction can be explained according to the chemico-physical nature of the drugs. In particular, the presence of both monomeric and aggregated fractions, which are supposed to be internalized through different mechanisms, accounts for the intracellular distributions observed for both drugs, depending on the treatment conditions. Equilibria among the drug fractions take place within the cells, resulting in the persistence of the intracellular fluorescence. On the whole, the behavior of the two drugs appears very similar, except for some aspects related to the intracellular distribution, which can be explained in terms of different degree of lipophilicity of the drugs.     

Minimising makespan in the two-machine flow-shop with release times

This paper considers the two-machine flow-shop problem with the objective of minimising the makespan subject to different release times. In view of the strongly NP-hard nature of this problem, five lower bounds and two new dominance criteria are proposed together with a decomposition procedure that reduces the problem size by setting jobs at the beginning of the sequence. Several branch and bound procedures are described by applying different lower bounds and branching schemes. A detailed computational campaign has been performed on different kinds of instances testing problems with size up to 200 jobs.     

Active methylene compounds in a very effective approach to 3-substituted isobenzofuranones through tandem aldol/lactonization reactions

In this article we describe a new accessible methodology for the synthesis of isobenzofuran-1(3H)-ones. In this process we exploited an effective, economic, useful and environmentally benign K₂CO₃ catalyzed, solvent-free one-pot tandem aldol-lactonization reaction between active methylene compounds and methyl 2-carboxy benzaldehyde. A particularly simple work-up and purification procedure are additional advantages addressed to a general green chemistry approach to this important class of heterocyclic compounds.     

Numerical simulation of bubble and droplet deformation by a level set approach with surface tension in three dimensions

In this paper we present a three‐dimensional Navier–Stokes solver for incompressible two‐phase flow problems with surface tension and apply the proposed scheme to the simulation of bubble and droplet deformation. One of the main concerns of this study is the impact of surface tension and its discretization on the overall convergence behavior and conservation properties. Our approach employs a standard finite difference/finite volume discretization on uniform Cartesian staggered grids and uses Chorin's projection approach. The free surface between the two fluid phases is tracked with a level set (LS) technique. Here, the interface conditions are implicitly incorporated into the momentum equations by the continuum surface force method. Surface tension is evaluated using a smoothed delta function and a third‐order interpolation. The problem of mass conservation for the two phases is treated by a reinitialization of the LS function employing a regularized signum function and a global fixed point iteration. All convective terms are discretized by a WENO scheme of fifth order. Altogether, our approach exhibits a second‐order convergence away from the free surface. The discretization of surface tension requires a smoothing scheme near the free surface, which leads to a first‐order convergence in the smoothing region. We discuss the details of the proposed numerical scheme and present the results of several numerical experiments concerning mass conservation, convergence of curvature, and the application of our solver to the simulation of two rising bubble problems, one with small and one with large jumps in material parameters, and the simulation of a droplet deformation due to a shear flow in three space dimensions. Furthermore, we compare our three‐dimensional results with those of quasi‐two‐dimensional and two‐dimensional simulations. This comparison clearly shows the need for full three‐dimensional simulations of droplet and bubble deformation to capture the correct physical behavior. Copyright © 2009 John Wiley & Sons, Ltd.     

The analytical resolution of parallel first‐ and second‐order reaction mechanisms

Given the species A₁ and A₂, the competition among the three different elementary processes (1) (2) (3) is frequently found in thermal and photochemical reaction systems. In the present paper, an analytical resolution of the system (1)–(3), performed under plausible contour conditions, namely, finite initial molar concentrations for both reactants, [A₂]₀ and [A₁]₀, and nonzero reaction rate coefficients k₁, k₂, and k₃, leads to the equation [A₁] = ((δ[A₂]^γ ? [A₂])/β) ? α, where α = k₁/2k₃, γ = β + 1 = 2k₃/k₂, and δ = ([A₂]₀ + β[A₁]₀ + β α))/[A₂]₀^γ. The comparison with a numerical integration employing the fourth‐order Runge–Kutta algorithm for the well‐known case of the oxidation of organic compounds by ferrate ion is performed. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 562–566, 2010     

Wormlike micelles mediated by polyelectrolyte

Aqueous solutions of the anionic surfactant potassium oleate (K-oleate) were studied using small-angle neutron scattering (SANS), steady-state rheology, and cryogenic transmission electron microscopy (cryo-TEM). The micellar structural changes induced by the addition of potassium chloride (KCl) and sodium polystyrenesulfonate (PSS) of different molecular weights were investigated. Upon addition of KCl, a transition from spherical to wormlike micelles was detected from the SANS data and confirmed by the cryo-TEM pictures. The rheological measurements revealed a strong dependence of the low-shear viscosity on the concentration of salt: a broad maximum in the viscosity curve was observed upon addition of KCl, characteristic of the growth of micelles into long worms, followed by branching. The addition of PSS to salt-free solutions of K-oleate had a significant effect on the scattering patterns, revealing partial growth of the spherical micelles into rodlike micelles. In contrast, in the presence of high salt concentrations, addition of PSS to solutions of wormlike micelles did not bring any noticeable modifications in the scattering. However, in the same salt conditions, a clear effect was observed on the low shear viscosity upon addition of PSS, which was found to depend significantly on molecular weight. This suggests a novel way of impacting the viscosity of solutions of wormlike micelles.     

Conductivities and transport properties of gelled electrolytes with and without an ionic liquid for Li and Li-ion batteries

Conductivity and transport properties have been determined for gelled polymer electrolytes of three compositions: a base PVdF-polymer gel with organic carbonate solvents as plasticizers and LiN(SO(2)C(2)F(5))(2) electrolyte, a second polymer electrolyte with 5 mass % 1-ethyl-3-methylimidazolium bisperfluoroethylsulfonyl imide (EMI-BETI) added to the base polymer electrolyte, and a third PVdF polymer electrolyte using only EMI-BETI as the plasticizer. Conductivities were studied over the temperature range +25 to -40 degrees C, and for all three gels, the temperature dependence of the conductivities was found to follow the VTF equation, which is consistent with the free volume model for ion transport. For the gel containing 5 mass % EMI-BETI, transport numbers were determined from +50 to -20 degrees C and were found to decrease as the temperature decreased. Although there are no theoretical models to treat and interpret the temperature dependence of transport numbers, we found that a modified VTF equation resulted in an excellent fit to the temperature dependence of the transport number, which is another confirmation of a free volume model for transport in these gelled polymer electrolytes.     

An improved approach for the determination of plasma-free catecholamines by HPLC-ED: Application to normal and hypertensive patients

Summary A dual-step procedure for the rapid, quantitative isolation of free catecholamines (norepinephrine, epinephrine and dopamine) from plasma, using a little column of CM-Sephadex and alumina adsorption, is described. Sensitive high performance liquid chromatography is also discussed, employing an amperometric detector for the quantitative determination. The recovery of the three catecholamines, and of N-methyldopamine used as the internal standard, was about 70–80%; the detection limits were 2pg for norepinephrine, 3pg for epinephrine and 3pg for dopamine. The combination of the rather specific and easy to handle two-step sample clean-up procedure, the high resolving power of the chromatography and the high sensitivity of electrochemical detection provided a simple method for the determination of free catecholamines in plasma samples of normal and essential hypertensive subjects under different conditions (supine position for 45 min, standing for 5 and 10 min). It was found that a significant increase in epinephrine levels (P<0.01) occurred in hypertensive patients under the three conditions studied.     

Improved worst-case complexity for the MIN 3-SET COVERING problem

We consider MIN SET COVERING when the subsets are constrained to have maximum cardinality 3. We propose an exact algorithm whose worst-case complexity is bounded above by O^*(1.3957^m), where m is the number of sets in the instance. This result improves upon the previously known bound of O^*(1.4391^m).