Setting the Foundations of Aqueous Three-Phase Systems (A3PS) in the Quest for a Rational Design

This work presents the first in-depth study of Aqueous Three-Phase Systems (A3PS) with the main purpose of unveiling their behaviour, hence contributing to the development of this new field. Thus, a complete definition of a quaternary system was carried through by describing all the regions in detail to represent them later on in a regular-tetrahedral diagram. The three aqueous faces of the tetrahedron demonstrated an undeviating influence in the segregation capacity. Furthermore, a method for comparing Aqueous Biphasis Systems (ABS) immiscibilities was set up in order to allow the evaluation and detection of the “limiting ABS” for the three-phase region. Finally, all this information was compiled and utilised to obtain a new strategy for an A3PS rational design, which can be applied with ABS libraries or in an experimental approach. In this sense, this strategy represents an undoubted advance towards future studies and development of A3PS, as this sequential application of the constructed knowledge is assumed to save time and resources.     

A Light-Triggerable Nanoparticle Library for the Controlled Release of Non-Coding RNAs

RNA-based therapies offer a wide range of therapeutic interventions including the treatment of skin diseases; however, the strategies to efficiently deliver these biomolecules are still limited due to obstacles related to the cellular uptake and cytoplasmic delivery. Herein, we report the synthesis of a triggerable polymeric nanoparticle (NP) library composed of 160 formulations, presenting physico-chemical diversity and differential responsiveness to light. Six formulations were more efficient (up to 500 %) than commercially available lipofectamine in gene-knockdown activity. These formulations showed differential internalization by skin cells and the endosomal escape was rapid (minutes range). The NPs were effective in the release of siRNA and miRNA. Acute skin wounds treated with the top hit NP complexed with miRNA-150-5p healed faster than wounds treated with scrambled miRNA. Light-activatable NPs offer a new strategy to topically deliver non-coding RNAs.     

Acetylene decomposition on Rh(100): theory and experiment.

The decomposition of acetylene on a Rh(100) single crystal was studied by a combination of experimental techniques [static secondary ion mass spectrometry (SSIMS), temperature-programmed desorption (TPD), and low-energy electron diffraction (LEED)] to gain insight into the reaction pathway and the nature of the reaction intermediates. The experimental techniques were combined with a computational approach using density functional theory (DFT). Acetylene adsorbs irreversibly on the Rh(100) surface and eventually decomposes to atomic carbon and gas-phase hydrogen. The combination of experimental and computational results enabled us to determine the most likely reaction pathway for the decomposition process.     

Intramolecular energy transfer in naphthalene-containing polyesters: Experiment and simulation for model compounds derived from five aliphatic dicarboxylic acids and 2-hydroxynaphthalene

Steady-state fluorescence depolarization measurements and molecular dynamics simulations have been used to study the efficiency of nonradiative intramolecular singlet energy transfer between 2-naphthoxy groups, denoted N, in model compounds for polyesters derived from 2,6-dihydroxy-naphthalene and aliphatic dicarboxylic acids. The five bichromophoric compounds studied are the diesters abbreviated as N-OOC-(CH₂)_n-COO-N;n = 2–6, which are condensation products obtained from 2-naphthol and aliphatic dicarboxylic acids. The anisotropy of the fluorescence of these compounds dispersed in a solid matrix of glassy poly(methyl methacrylate) indicates that there is nonradiative singlet energy transfer between naphthoxy groups. The efficiency of this transfer depends onn. A theoretical treatment using molecular dynamics simulations for the conformations of the five model compounds has been performed in order to evaluate the parameters related to the efficiency of the transfer. The experimental and theoretical variation of such parameters withn is consistent with the estimated Förster radius of 9–10 Å for this system.     

Effect of chromium substitution in Ca4Mn3O10

Ca₄Mn_3−xCr_xO₁₀ compounds were synthesized in order to investigate the role of an isoelectronic substitution in the layered manganite. Induced structural changes are mainly described as a distortion of the two types of octahedra in the n=3 RP structure. The results indicate that Cr³⁺ is not the only significant valence state for chromium ions. Electrical and magnetic characterization allow to conclude that chromium does not favour the double exchange mechanism in these compounds.     

Behaviour of Ca2Fe2O5 with Nb substitution and sintering temperatures seen by Mössbauer spectroscopy

Mössbauer spectroscopy of samples of Ca₂Fe_2?xNb_xO_5+x with x values ranging from 0 to 0.8 and sintering temperatures of 1200°C and 1300°C shows the presence of two magnetic fields and a paramagnetic signal. The behaviour of the parameters as a function of x and of the sintering temperatures are discussed and compared with XRD results.     

Reliability of MEP and MEP-derived properties computed from DFT methods for molecules containing P, S and CL

We present a systematic study on the reliability of different theoretical methods to represent the molecular electrostatic potential (MEP), and MEP-derived properties of prototypical compounds containing phosphorus, sulfur and chlorine. Calculations at the Hartree-Fock and M?ller-Plesset up to fourth-order level of theory, as well as local, non-local and hybrid density functional computations were performed for a representative set of neutral molecules. The study was carried out using different basis sets ranging from the medium-sized 6-31G(d ) to the large 6-31G(2d,2p) basis set, but in some test calculations more extended basis sets were also considered. The analysis of the results was performed discussing separately the effect of the basis set and of the level of theory used to determine the molecular wavefunction on the reliability of the MEP and MEP-derived properties. Received: 4 March 1997 / Accepted: 27 June 1997     

Analysis of a new BEM‐FEM coupling for two‐dimensional fluid‐solid interaction

In this work we present a new numerical method, based on a coupling of finite and boundary elements, to solve a fluid‐solid interaction problem in the plane. The discrete method uses classical Lagrange finite elements adapted to curved boundaries for the field variable and spectral approximation of the unknowns on the artificial boundary. We provide error estimates for this Galerkin scheme and propose a full discretization based on elementary quadrature formulae, showing that the perturbation due to numerical integration preserves the optimal rate of convergence. We also suggest an iterative method to solve the complicated linear systems arising from this type of schemes. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005     

Specific interactions in reversed micelles: Oxidation of Fe(bpy)32+ by S2O82− in AOT-oil-water microemulsions

The oxidation of Fe(bpy)₂²⁺ by peroxodisulphate (bpy = 2,2′-bipyridine) has been studied in a variety of sodium bis(2-ethylhexyl)sulfosuccinate(aerosol-OT or AOT)-oil-water microemulsions by changing the nature of the oil phase, the surfactant concentration, and the molar ratio w = [H₂O]/[AOT]. Kinetic results show that the influence of surfactant concentration is due to a dilution effect. On the other hand, the comparison between the reaction rate in conventional aqueous solution with that in AOT w/o microemulsions seems to indicate that the iron(II) species is distributed between the aqueous phase and the interphase. © 1995 John Wiley & Sons, Inc.