Self-assembled multilayers of transition-metal-terpyridinyl complexes; formation, and characterization

Layer-by-layer (LBL) growth of terpyridinyl ligands with a range of metal ions is reported. Monolayers of mercaptophenyl terpyridine on gold were used to initiate LBL assembly by complexing the first layer of metal ions. Tetra-2-pyridinylpyrazine was used as a linking ligand between subsequent metal ion layers. The assembly of the terpyridines with 21 different metals was evaluated using UV absorbance spectroscopy, variable-angle spectroscopic ellipsometry, and atomic force microscopy. Successful LBL growth appears to depend on the ionic radius of the metal ion. Metals that formed multilayered LBL structures were primarily limited to a small range of effective ionic radii between 66 and 73 pm. Metal ions with smaller ionic radii usually formed initial layers but seldom exhibited consistent LBL growth, while ions with radii larger than 73 nm generally did not demonstrate any evidence of LBL growth.     

Étude expérimentale de la dispersion active d'un polluant hydrocarboné en milieu poreux hétérogèneActive dispersion of a hydrocarbon pollutant in heterogeneous porous media: experimental study

This study deals with Non Aqueous Phase Liquid (NAPL) dissolution in subsurface water in order to predict the pollutant plume development and to optimize remediation processes. An experimental study of NAPL dissolution in porous media is presented. Local water saturation and effluent pollutant concentration measurements are presented for several kinds of porous media. Experimental results show clearly the influence of microscopic and/or macroscopic heterogeneities of the porous media and the distribution of the pollutant on the active dispersion of the NAPL. The NAPL dissolution occurs in several steps which highlights the existence of non-local equilibrium related to the heterogeneity of the porous media. To cite this article: A. Yra et al., C. R. Mecanique 334 (2006).     

Lattice sub-tilings and frames in LCA groups

Given a lattice Λ in a locally compact Abelian group G and a measurable subset Ω with finite and positive measure, then the set of characters associated with the dual lattice form a frame for $L^2(\mathrm{\Omega })$ if and only if the distinct translates by Λ of Ω have almost empty intersections. Some consequences of this results are the well-known Fuglede theorem for lattices, as well as a simple characterization for frames of modulates.     

Absence of biological damage from prolonged exposure to intravascular ultrasound: a swine model

Ultrasound (US) has been used in IMS II (intravascular US) and CLOTBUST (transcranial US) clinical trials for thrombolysis. During the treatment, in addition to the targeted thrombus, other biological components, such as blood and vessel walls are subjected to long durations of US exposure. In this study we explored evidence of biological damage due to mechanical forces or thermal effects of US exposure at the frequency, intensity and duration employed for thrombolysis treatment. Biological effects were investigated by exposing swine ilio-femoral arteries bilaterally to an intravascular US generating catheter and a conventional catheter. A total of 12 animals each underwent 8h of exposure to intravascular pulsed US with a frequency of 2.2MHz and spatial peak time average intensity (I(SPTA)) of 6W/cm(2) per transducer (a total of six transducers per catheter) while the ultrasonic device surface temperature was maintained at 43 degrees C. The animals were euthanized either 24+/-3h or 28+/-3 days post treatment. A range of physiological and hematological parameters were evaluated pre-, post-, and during US exposure. The vascular diameter was determined pre- and post-US exposure using angiograms. Following euthanasia, each animal underwent a gross pathological examination, and the treated vessels and an unexposed vessel were excised for comparative histopathological evaluation. No evidence of biological damage was found at the end of 8h exposure to intravascular US.     

Environmentally Friendly Preparation of Amidoalkyl Naphthols

A new, facile, and cost-effective process involving the solvent-free synthesis of amidoalkyl naphthols using a three-component, one-pot condensation reaction of β-naphthol, aromatic aldehyde, and amides in the presence of Al(H₂PO₄)₃ as heterogeneous catalyst under thermal conditions and microwave irradiation has been described. This new approach has the advantage of consistently excellent yields and short reaction times. The catalyst has shown a very stable catalytic activity in the reaction conditions and also can be recovered and recycled.     

Alumina Perchloric Acid (Al 2 O 3 -HClO 4 ) as an Efficient Heterogeneous Catalyst for Modified Preparation of Trimethylsilyl Ethers

A highly efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, benzylic, secondary, hindered secondary, tertiary, phenols, and oximes with hexamethyldisilazane (HMDS) using alumina perchloric acid (Al ₂ O ₃ -HClO ₄ ) as recyclable heterogeneous catalyst in excellent yields with short reaction times (3?65 min) under ambient conditions is described.     

Selective extraction and preconcentration of ultra-trace amounts of arsenic(V) ions using carbon nanotubes as a novel sorbent

In the present study, multiwalled carbon nanotubes (MWCNTs) as solid phase extraction sorbent were developed for preconcentration of arsenic(V) species prior to graphite furnace atomic absorption spectrometry (GFAAS) determination. Arsenic(V) was selectively sorbed on the packed column with MWCNTs within a pH 9.5 in the presence of 2-(5-bromo-2-pyridylazo)-5-diethyl amino phenol (5-Br-PADAP). The adsorbed species was then desorbed with 1 mL of 2.0 M HNO₃. Experimental parameters including pH, sample volume and flow rate, type, volume and concentration of eluent that influence the recovery of the arsenic(V) species were optimised. Under the optimised conditions, the calibration curve was linear in the range of 0.2–10.0 µg L^?1 with detection limit of 0.016 µg L^?1. The relative standard deviations (RSD) for seven replicate determinations at 1.0 µg L^?1 level of arsenic was 6.69%. The proposed method was successfully applied to the determination of arsenic in water samples and certified reference material (NIST RSM 1643e).     

Electrospun Pd nanoparticles loaded on Vulcan carbon/ conductive polymeric ionic liquid nanofibers for selective and sensitive determination of tramadol

In the present work a sensitive and selective electrochemical sensor was fabricated based on a glassy carbon electrode which has been modified with Pd nanoparticles loaded on Vulcan carbon/conductive polymeric ionic liquid composite nanofibers. The nanostructures were characterized by UV–Vis, FT-IR, FESEM, EDX and XRD techniques. The electrochemical study of the modified electrode, as well as its efficiency for the electrooxidation of tramadol was described in 0.1 M phosphate buffered solution (PBS) (pH 7.0) using cyclic voltammetry, linear sweep voltammetry, chronoamperometry and square wave voltammetry as diagnostic techniques. It has been found that application of the composite nanofibers result in a sensitivity enhancement and a considerable decrease in the anodic overpotential, leading to negative shifts about 200 mV in peak potential. The results exhibit a linear dynamic range from 0.05 μM to 200 μM and a detection limit of 0.015 μM for tramadol. Finally, the modified electrode was used for the determination of tramadol in pharmaceutical and biological samples.     

Homogenization of Solute Transport in Unsaturated Double-Porosity Media: Model and Numerical Validation

Transport in Porous Media - The development of a macroscopic model for solute transport coupled with unsaturated water flow in double-porosity media is presented in this work, by using the...