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Poinescu A.A.,University Valahia of Targoviste | Ion R.M.,University Valahia of Targoviste | Ion R.M.,Polytechnic University of Bucharest | Van Staden R.-I.,National Institute of R and D for Electrochemistry and Condensed Matter | And 2 more authors.
Journal of Optoelectronics and Advanced Materials | Year: 2011

The hydroxyapatite (HA) is one of the most used materials in medical applications, due to its similarity with human bones. A chemical synthesis method, and the characterization by atomic force microscopy (AFM) and scanning electron microscopy (SEM), has been chosen in this paper. The surface study on nm scale and the surface topography were evaluated by using AFM with tapping mode. The size distribution of the grown spherulite was carried out by AFM, operating in non-contact mode. The SEM pictures of the grown spherulite crystals shows many spherical agglomerations and few crystallites of 0.1 μm in size with pores.


Poinescu A.A.,University Valahia of Targoviste | Ion R.M.,University Valahia of Targoviste | Van Staden R.-I.,National Institute of R and D for Electrochemistry and Condensed Matter | Van Staden J.F.,National Institute of R and D for Electrochemistry and Condensed Matter | Ghiurea M.,ICECHIM Bucharest
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

It is well-known that hydroxyapatite have multiple applications in tissue engineering due to compositional similarities with bone tissue. In this work, hydroxyapatite powders obtained by modified chemical precipitation route, has been investigated by AMF and SEM analysis grain size, X-ray diffraction and infra-red spectroscopy. The particle size of hydroxyapatite was observed to be very fine, uniform, around 50-60 nm. SEM observation of the HA coatings showed the presence of nano-sized needles, with a significant level of agglomeration. The infrared analysis show the characteristic peaks of absorbed water, hydroxyl, phosphate and carbonate species. The XRD pattern clearly indicated the crystallites responsible for the Bragg reflection of the (002) and (003) planes are useful for size determination by Sherrer relationship (around 68 nm). © 2010 SPIE.


Pop R.O.,National Institute of R and D for Electrochemistry and Condensed Matter | Medeleanu M.,Polytechnic University of Timişoara | Mracec M.,Romanian Academy of Sciences
Studia Universitatis Babes-Bolyai Chemia | Year: 2010

The aromaticity of the heterobenzenes containing 15-group elements, namely the six-membered homocycles (λ 3-X) 6 (X = CH, N, P, As) and the six-membered alternant heterocycles (λ 3-X-λ 3-Y) 3 (X, Y = CH, N, P, As) is investigated using magnetic and geometric criteria at B3LYP/6-31G (d,p) level. The NMR isotropic shielding values of a molecule of H 2 placed at a distance of 2.5Å above the center of the heterobenzenes were computed using the GIAO method at 6-31G(d,p) level. The results are compared with the negative values of the absolute magnetic shielding, computed at the center of ring (NICS index), at B3LYP/6-31G (d,p) level. An angle-based index is used as geometric criterion for the evaluation of the aromatic character.


Saheli M.,University of Kashan | Pop R.O.,National Institute of R and D for Electrochemistry and Condensed Matter | Pop M.L.,Babes - Bolyai University | Diudea M.V.,Babes - Bolyai University
Studia Universitatis Babes-Bolyai Chemia | Year: 2010

Design of a hypothetical crystal network, by using Trs(P4(M)) sequence of map operations, is presented. It is shown that the octahedral monomer is the most stable, among the similar structures designed from the Platonic solids, as hydrogenated species, and all these have a moderate stability, between adamantane and C60 fullerene, as calculated at the PM3 level of theory. The topology of the network is described in terms of Omega polynomial, function of the net parameters. Close formulas for this polynomial and examples are tabulated.


Segneanu A.E.,National Institute of R and D for Electrochemistry and Condensed Matter | Vlazan P.,National Institute of R and D for Electrochemistry and Condensed Matter | Svera P.,National Institute of R and D for Electrochemistry and Condensed Matter | Grozescu I.,National Institute of R and D for Electrochemistry and Condensed Matter | Sfirloaga P.,National Institute of R and D for Electrochemistry and Condensed Matter
Digest Journal of Nanomaterials and Biostructures | Year: 2014

The aim of the present study was to prepare inorganic-organic hybrid material for biomedical potential application. The cobalt-ferrite (CoFe2O4) magnetic nanoparticles (MNPs) obtained by sol-gel method and treated at 200 °C were immobilized in a small peptide. Covalent and non-covalent attachment of proteins with MNPs provides access to functional hybrid systems with applications in biotechnology, medicine and catalysis. The crystalline phases, morphology and chemical composition of the particles were characterized by GC-MS, NMR, TEM/EDX, BET and FT-IR.

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