Maria Mihaly

Enhancement of linear and nonlinear optical properties of deoxyribonucleic acid-silica thin films doped with rhodamine

In this work, we present the linear and nonlinear optical properties of DNA as functional material, incorporated into a silica material matrix with rhodamine organic dye. We observed that even low concentration of DNA affects the aggregate behavior of the dyes in silica films. The samples with DNA showed higher transmittance and fluorescence efficiency. Moreover, the presence of DNA has been found to significantly enhance the nonlinear optical response of the systems. In this way, we prove that silica materials can provide suitable matrices for hybridization with functional molecules and can be utilized as active optical waveguide materials with enhanced nonlinear optical properties.

Nonionic Microemulsion Extraction of Ni (II) from Wastewater

Two W/O microemulsion systems, Water/iso-C3-ol/Brij 30/PO and Water/Brij 30/EtOAc, have been proved to have high yields in removal and recovery of metal ions (Ni (II)) from wastewater. The influence of some parameters, such as aqueous phases to microemulsion volumetric ratio, oil type, concentration of the surfactant and distribution coefficient of Ni (II) between aqueous and microemulsion phases, on separation of nickel ion from aqueous solution have been studied. The extraction of Ni (II) is very efficient for concentrations of nickel aqueous solutions less than 1000 mg/L, when the extraction efficiency is up to 85%.

Hybride Nanomaterials Based on Silica Coated C60 Clusters Obtained by Microemulsion Technique

Currently, there is a major trend to produce nanostructures of a wide variety of materials by understanding their properties and their functionality in order to develop future nanotechnologies. In this article the silica coated fullerene C60 clusters have been produced by microemulsion technique. Firstly, the ternary phase diagrams in water/TX-114/tetraethylorthosilicate (TEOS) system at different temperatures were constructed, followed by establishing the influence of clusterization and solubilization agents in choosing the pseudoternary system. By using the phase diagram specific working conditions have been selected, in order to facilitate nanostructured templates for preparation of the silica coated fullerene nanoclusters.

Novel materials based on DNA‐CTMA and lanthanide (Ce3+, Pr3+)

New, deoxyribonucleic acid (DNA) based compounds, functionalized with hexadecyltrimethylammonium chloride (CTMA) and lanthanide hydroxide nanoparticles were synthesized. The spectral measurements suggest that between the DNA-CTMA complex and the lanthanide (III) ions a chemical interaction takes place. The obtained materials exhibit an improved fluorescence efficiency, showing a potential interest for application in photonics, and more particularly, in light emitting devices.

Biomaterials based on DNA embedded in silica matrix

Ordered DNA - silica materials have been efficiently synthesized by using the microemulsion sol - gel procedure. Dynamic Light Scattering (DLS) spectra showed that the microemulsion systems applied for DNA - silica materials synthesis contain structural units similar in size and shape. The atomic force microscopy (AFM) analysis revealed that the obtained DNA - silica thin films exhibit an ordered units array pattern structure in micron scale and the structural units channels run parallel with each. The UV - VIS reflectance spectra performed for DNA/Rhodamine - silica materials proved that the structure and properties of native DNA are protected by incorporation. The obtained results assumed a globular shape of the DNA imposed by microemulsion template and the chromophore location into its double helix structure. An improvement of the thermal properties of DNA, incorporated into the DNA - silica material, was observed by the thermogravimetric-differential thermal analysis (TGA-DTA).

Fe2O3 Nanoparticles Coated in a SiO2 Shell by Microemulsion Method

Mixing elements at nanoscale range can offer exciting possibilities of novel materials with composition, structure and properties quite different from those in the bulk. Fe2O3 nanoparticles embedded in a surrounding silica shell were prepared via surfactant – assisted process by using dodecyl-4-lauryl ether (Brij 30) as oriented template, followed by thermal treatment. The nanoparticles are formed by the precipitation reaction of ferrous and ferric salts with ammonium hydroxide into water-in-oil microemulsion. The hydrodynamic radius of microemulsion droplets and coated nanoparticles were measured by dynamic light scattering. Their structural properties have been studied by FT-IR spectroscopy, thermogravimetric analysis and atomic force microscopy.

Tunning the Colour of Solar Absorbers by Changing Chromophore Nature and Nanoparticle Size

In this paper some metallic (Au) and oxide (NiO and Cr2O3) nanoparticle dispersions are proposed as optical enhancers for solar collectors. The metallic nanoparticles are synthesised by photoreduction technique whereas the oxide nanoparticles are obtained by precipitation method, their shape and size being confined in a template of water-in-oil microemulsion. By using the mentioned template, monodispersed nanoparticles could be prepared, which have been further characterized by dynamic light scattering, transmission electron microscopy, diffuse reflectance spectroscopy and chromatic analysis. Correlation of these results is useful to obtain criteria for the design of Au or metallic oxides nanoparticles based solar absorbers.

C 60 Monodisperse nanoclusters - silica based thin film obtained by microemulsion technique

Summary form only given. Monodisperse fullerene nanoclusters have been encapsulated into silica matrix conducting the clusterization by microemulsion technique which is an efficient route to template a variety of nanostructures. The preparing C60 clusters -silica based thin films is a necessary step in the exploitation of the unique properties of these materials. For further applications, the results of time and thermal stability studies of these thin films have been presented. The successful formation of C60 nanoclusters -silica based thin films has been demonstrated by different analytical techniques including UV -VIS spectroscopy, TEM and AFM. Keywords: C60 clusters, silica based thin film, microemulsion.