Ana-Maria Manea

Lithium-AluminIum Hydroxide Hydrate thin Layers on Al Based Substrates - New Ecological Process for Corrosion Resistance Increase

Some preliminary experimental results on development of non-conventional, environmentally friendly procedures to form new corrosion protective thin films on Al, based on lithium-aluminium hydroxides known as hydrotalcite coatings, are presented. Chemical conversion films on pure Al and AU4G1 Al alloy have been formed involving LiNO3-KNO3-LiOH based solutions, with/without a second step involving Ce(III)and Mn(VII)compounds. SEM pictures revealed a uniform layer, formed by crystallites with 200–300 nm walls length. Corrosion experiments showed their excellent performances, materialised in corrosion currents of 0.1–0.2 μA/cm2and at least 168 hours of salt mist exposure with no aspect modification.

Chitosan an eco-friendly biomaterial from marine invertebrates

Marine organisms are formed by bio compounds with a lot of properties and characteristics that may justify their potential applications within the biomedical field. Assuring the exploitation of natural marine resources and the valorization of residues from marine origin, like those obtained from food processing, represent a highly interesting platform for development of novel eco-friendly biomaterials, with higher benefits due to the fact that the source is practically inexhaustible. This study involves the extraction and identification of chitosan from samples of invertebrates organisms by chemical extraction method. The samples of aquatic organisms consist of exoskeleton of crab and spawning of gastropoda. This paper presents the possible raw materials for production of chitosan extracted from marine organisms and the characterization of the chitosan extract.

DNA- and DNA-CTMA: novel bio-nanomaterials for application in photonics and in electronics

Functionalization of deoxyribonucleic acid (DNA) with surfactants, photosensitive and conductivity increasing molecules as well as thin film processing is reviewed and discussed. The comparative spectroscopic studies of chemical and photothermal stability of several chromophores show a better stability in DNA-cetyltrimethylammonium (CTMA) surfactant complexes than in polycarbonate (PC) or poly(ethylene glycol) (PEG) matrices. Also the optical damage threshold in nanosecond pulsed laser illumination is higher in thin films of bio-macromolecules such as DNA, DNACTMA, collagen than in PC. The electrical conductivity of doped DNA based systems exhibits a typical ionic character and can be improved by an appropriate doping. Practical applications of DNA based complexes are reviewed and discussed.

Preparation, linear and NLO properties of DNA-CTMA-SBE complexes

Synthesis of deoxyribonucleic acid (DNA) - was cetyltrimethylammonium (CTMA) - sea buckthorn extract (SBE) at different concentrations is decribed. The complexes were processed into good optical quality thin films by spin coating on different substrates such as: glass, silica and ITO covered glass substrates. SBE contains many bioactive substances that can be used in the treatment of several diseases, such as cardiovascular disease, cancer, and acute mountain sickness. The obtained thin films were characterized for their spectroscopic, fluorescent, linear and nonlinear optical properties as function of SBE concentration. The third-order nonlinear optical (NLO) properties of thin films were determined by the optical third-harmonic generation technique at 1 064.2 nm fundamental wavelength.

Linear and nonlinear optical properties of new materials based on DNA-CTMA and aromatic compounds (Conference Presentation)

In order to find eco-friendly materials for different applications an important research effort was devoted to the materials science in the last decade. A particular attention attracted the deoxyribonucleic acid (DNA). The interest is due to its versatility, biodegradability, abundance and their origin from renewable sources. DNA based new materials, functionalized with hexadecyltrimethylammonium chloride (CTMA) and aromatic compounds were prepared. Solutions with two different concentrations of aromatic compounds were obtained in butanol. The obtained, new complexes were processed into good optical quality thin films by spin coating method. Films were deposited on glass substrates and characterized for their spectroscopic, linear and nonlinear optical properties. The third-order nonlinear optical (NLO) properties of thin films were determined by the optical third-harmonic generation technique at 1 064.2 nm fundamental wavelength. The obtained materials, with improved fluorescence efficiency, present a potential interest for application in photonics.