National Institute Of Materials Physics - Romania

The phase of the electronic wave function is not directly measurable but, quite remarkably, it becomes accessible in pairs of isospectral shapes, as recently proposed in the experiment by Moon et al. [Science 319, 782 (2008)]. The method is based on a special property, called transplantation, which relates the eigenfunctions of the isospectral pairs, and allows us to extract the phase distributions, if the amplitude distributions are known. We numerically simulate such a phase extraction procedure in the presence of disorder, which is introduced both as Anderson disorder and as roughness at edges. With disorder, the transplantation can no longer lead to a perfect fit of the wave functions, however we show that a phase can still be extracted-defined as the phase that minimizes the misfit. Interestingly, this extracted phase coincides with (or differs negligibly from) the phase of the disorder-free system, up to a certain disorder amplitude, and a misfit of the wave functions as high as similar to 5%, proving a robustness of the phase extraction method against disorder. However, if the disorder is increased further, the extracted phase shows a puzzle structure, no longer correlated with the phase of the disorder-free system. A discrete model is used, which is the natural approach for disorder analysis. We provide a proof that discretization preserves isospectrality and the transplantation can be adapted to the discrete systems.

Background: In this work the chemical structure of dextran-iron oxide thin films was reported. The films were obtained by MAPLE technique from composite targets containing 10 wt. % dextran with 1 and 5 wt.% iron oxide nanoparticles (IONPs). The IONPs were synthesized by co-precipitation method. A KrF* excimer laser source (lambda = 248 nm, tau(FWHM)congruent to 25 ns, nu = 10 Hz) was used for the growth of the hybrid, iron oxide NPs-dextran thin films. Results: Dextran coated iron oxide nanoparticles thin films were indexed into the spinel cubic lattice with a lattice parameter of 8.36 angstrom. The particle sized calculated was estimated at around 7.7 nm. The XPS shows that the binding energy of the Fe 2p(3/2) of two thin films of dextran coated iron oxide is consistent with Fe3+ oxides. The atomic percentage of the C, O and Fe are 66.71, 32.76 and 0.53 for the films deposited from composite targets containing 1 wt.% maghemite and 64.36, 33.92 and 1.72 respectively for the films deposited from composite targets containing 5 wt.% maghemite. In the case of cells cultivated on dextran coated 5% maghemite gamma-Fe2O3, the number of cells and the level of F-actin were lower compared to the other two types of thin films and control. Conclusions: The dextran-iron oxide continuous thin films obtained by MAPLE technique from composite targets containing 10 wt.% dextran as well as 1 and 5 wt.% iron oxide nanoparticles synthesized by co-precipitation method presented granular surface morphology. Our data proved a good viability of Hep G2 cells grown on dextran coated maghemite thin films. Also, no changes in cells morphology were noticed under phase contrast microscopy. The data strongly suggest the potential use of iron oxide-dextran nanocomposites as a potential marker for biomedical applications.

Iron oxide oxide nanoparticles were prepared by chemical co-precipitation method. The nanoparticles were mixed with dextran in distilled water. The obtained solutions were frozen in liquid nitrogen and used as targets during matrix assisted pulsed laser evaporation for the growth of hybrid, iron oxide nanoparticles-dextran thin films. Fourier Transform Infrared Spectroscopy and X-ray diffraction investigations revealed that the obtained films preserve the structure and composition of the initial, non-irradiated iron oxide-dextran composite material. The biocompatibility of the iron oxide-dextran thin films was demonstrated by 3-(4.5 dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide-based colorimetric assay, using human liver hepatocellular carcinoma cells. (C) 2011 Elsevier B.V. All rights reserved.

This paper discusses the properties of two arylenevinylene oligomers thin films deposited by vacuum evaporation on different substrates. The morphology of the thin films was investigated by scanning electron microscopy and atomic force microscopy, and the optical properties by UV-Vis and fluorescence spectroscopy. The optical nonlinear phenomenon of two-photon absorption induced fluorescence has been evidenced in the thin films of these compounds. We have also investigated the electrical properties of semiconductor/insulator/semiconductor (ITO/oligomer/Si) heterostructures in correlation with the contact energetic barriers, morphological and structural properties of the layers. (C) 2011 Elsevier B.V. All rights reserved.

The article reports on the tilted growth of textured aluminium nitride thin films obtained by radio-frequency magnetron sputtering onto 50 mm diameter Si (111) wafers, in reactive atmosphere, in a planar sputtering system without tilting the substrate and with no additional sputtering geometry alterations. The films were investigated using, X-ray diffraction, spectroscopic ellipsometry and scanning electronic microscopy, done by local measurements on the wafer surface, at different distances from the centre. A progressive increase of the tilt angle when moving away from the sample centre has been found. The maximum tilt angle of the columnar AlN crystallites, obtained near the edges of the wafer, is about 7 degrees. The results showed also that tilting is associated with smaller thickness and larger dispersion of the c axis orientation. Synthesizing inclined c axis AlN films should allow the fabrication of surface acoustic wave devices based on shear waves for liquid sensor applications.

The present study is dedicated to the investigation of self-adhesive cements, based on resin composites (RBC). Reported cases of dental restorations decays, are influenced by interface/surface quality and marginal adaptation to dentin and enamel. The influence is given by organic and inorganic (filler) phase as well. Regarding the organic phase, this is involved in bonding with dentin remains and enamel. Differences were noticed between the investigated materials; results from EDX patterns reveal major differences between inorganic phase (filler) in specimens and a non homogenous state for all samples. Results are confirmed by the mapping patterns. Low discontinuity areas for samples specimen were remarked for Biscem and RelyXU100 samples, then for MaxcemElite dental cement. Regarding mechanical properties, those are dramatically influenced by the filler. The major determination is given by the particles size and state of homogeneity for a given specimens composition. SEM results revealed a textured structure with a small filler particles size for RelyX U100 than other samples (less than, d - 1 mu m). A stirring method is recommended for all samples before application for an improved homogeneity.

We report on the coating with ZnO adherent thin films of cotton woven fabrics by Pulsed laser deposition technique in order to obtain innovative textile materials, presenting protective effects against UV radiations and antifungal action.

Embedding silver (Ag) into CaPs one could expect the enhancement of the antimicrobial performances of coatings for load bearing implants. The aim of this research was to evaluate whether the cellular morphology is influenced by the variation of Ag content, as well as by the solubility and morphological features of Ag-containing CaP coatings obtained by combinatorial pulsed laser deposition technique. In this view, we developed compositional libraries of either Ag and hydroxyapatite (HA) or Ag and beta-tricalcium phosphate (beta-TCP). The Ag content along the length of the combinatorial CaP coatings increased up to a maximum of similar to 1 at.%. SEM and AFM images evidenced the abundant presence of particulates typical for CaP coatings deposited by PLD. AFM histograms showed that the samples were rough with RMS values within 61-209 nm range. Ag content values up to 0.6 at. % into HA coatings were found nontoxic for mesenchymal stem cell (MSC) growth.

This paper presents a new technique for investigating the modifications induced by high-density green light [GL] on water in NaCl solutions. Solutions of 0,45 g% and 0,9 g%, irradiated with green light (lambda = 527 nm, intensity 3.10(5) Lx) were used. As a receptor for measuring the irradiation effect we used red blood cell (RBC) permeability in hypotonic media, the so-called osmotic shock. After RBC lysis in hypotonic medium, the released hemoglobin was spectrophotometrically determined at lambda = 550 nm. The values of the osmotic shock for the samples obtained with GL-irradiated NaCl solutions were significantly lower than the values obtained with non-irradiated controls. This may indicate that the penetration of water inside the membranes canaliculi is hindered. This new type of result was complemented by chronoamperometry and impedance spectroscopy determinations. The current density of the irradiated solution decreases from the value of 29.5 mu A.cm(-2) in the control to 17.74 mu A.cm(-2) in the irradiated sample with a corresponding decrease of ionic mobility. The impedance value of the GL irradiated NaCl solutions were significantly lower than the control values, thus correlating well with the data recorded by chronoamperometry. All these data may indicate large water cluster formation through GL irradiation which are beyond the cellular aquaporine channels capacity. A similar process is identified by using red light, as well as blue light, though with a much smaller output.

Caesalpinia pulcherrima (Linn) popularly known as Peacock flower in India belongs to family Caesalpiniace. In this work, we describe environment friendly technique for green synthesis of gold nanoparticles from AuCl4 solution using the Caesalpinia pulcherrima (Peacock flower) flower extract as reducing agent. The gold nanoparticles were characterized using UV-visible spectroscopy and transmission electron microscopy (TEM). The UV-visible spectra indicate a strong Plasmon resonance that is located at similar to 450 nm. The TEM analysis shows that products have spherical morphology with size ranging between 10-50 nm. The study also indicates that gold nanoparticles show good antimicrobial activities when compared to the standard antibiotics.