National Institute Of Materials Physics - Romania

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860 articles found

411. INVESTIGATIONS ON THE PROPERTIES OF A TWO-DIMENSIONAL NANOPATTERNED METALLIC FILM

Authors: Breazu, C; Preda, N; Socol, M; Stanculescu, F; Matei, E; Stavarache, I; Iordache, G; Girtan, M; Rasoga, O; Stanculescu, A

Published: OCT-DEC 2016, Digest Journal of Nanomaterials and Biostructures, 11, 1229, DOI:

This paper presents some investigations of the effect of nanopatterning on the properties of aluminum layer deposited by sputtering. UV-Nanoimprint Lithography technique has been used for the realization of a 2D array of nanostructures (pillars) in aluminum film characterized by cylindrical shape and the following structural parameters: diameter between 400 nm and 490 nm, depth between 320 nm and 420 nm and periodicity of 1.1 mu m, which have been revealed by SEM and AFM measurements. The UV-Vis transmission, reflection and photoluminescence measurements have evidenced the effect of the nanopatterning on the optical properties of the A1 layer.

412. Structural and Biological Assessment of Zinc Doped Hydroxyapatite Nanoparticles

Authors: Popa, CL; Deniaud, A; Michaud-Soret, I; Guegan, R; Motelica-Heino, M; Predoi, D

Published: 2016, JOURNAL OF NANOMATERIALS, 2016, DOI: 10.1155/2016/1062878

The aim of the current research work was to study the physicochemical and biological properties of synthesized zinc doped hydroxyapatite (ZnHAp) nanoparticles with Zn concentrations x(Zn) = 0 (HAp), x(Zn) = 0.07 (7ZnHAp), and x(Zn) = 0.1 (10ZnHAp) for potential use in biological applications. The morphology, size, compositions, and incorporation of zinc into hydroxyapatite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Raman scattering, and X-Ray Photoelectron Spectroscopy (XPS). In addition, the cytotoxicity of ZnHAp nanoparticles was tested on both E. coli bacteria and human hepatocarcinoma cell line HepG2. The results showed that ZnHAp nanoparticles (HAp, 7ZnHAp, and 10ZnHAp) have slightly elongated morphologies with average diameters between 25 nm and 18 nm. On the other hand, a uniform and homogeneous distribution of the constituent elements (calcium, phosphorus, zinc, and oxygen) in the ZnHAp powder was noticed. Besides, FTIR and Raman analyses confirmed the proper hydroxyapatite structure of the synthesized ZnHAp nanoparticles with the signature of phosphate, carbonate, and hydroxyl groups. Moreover, it can be concluded that Zn doping at the tested concentrations is not inducing a specific prokaryote or eukaryote toxicity in HAp compounds.

413. STRUCTURAL AND MAGNETIC PROPERTIES OF Sr2FeMoO6 OBTAINED AT LOW TEMPERATURES

Authors: Bartha, C; Plapcianu, C; Crisan, A; Enculescu, M; Leca, A

Published: JUL-SEP 2016, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 11, 780, DOI:

The double-perovskite Sr2FeMoO6 has been obtained by solid state method at low temperature (1060 degrees C) and a very short time of synthesis (up to 4h). Both, X-ray diffraction and scanning electron microscopy (SEM) confirmed the formation of Sr2FeMoO6 oxide with grain sizes around 160 mm, and a small amount of SrMoO4 as an impurity. Mossbauer spectroscopy revealed a mixed site population with Fe and Mo ions generating a structure type with population inversion. This structure has a critical influence on the magnetic properties, as confirmed by the magnetization and TC values, i.e 3.56 mu(B)/f.u and 415 K, respectively. The Sr2FeMoO6 behavior was interpreted in terms of ferrimagnetic couplings generated by the various distributions of local interactions between Fe and Mo neighbors while comparing the ideal structure should show antiferromagnetic coupling between the two sublattices.

414. SYNTHESIS AND CHARACTERIZATION OF FLUORESCENT HYDROXYAPATITE

Authors: Popa, CL; Ciobanu, CS

Published: 2016, ROMANIAN REPORTS IN PHYSICS, 68, 1177, DOI:

This paper presents the synthesis of cerium doped hydroxyapatite using low concentrations of cerium (x(Ce) = 0.01, 0.03 and 0.05) by an adapted sol-gel method. The structural and optical properties of the obtained powders have been studied by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Photoluminescence (PL) measurements. The cerium ions successfully substituted the calcium ions from the hydroxyapatite structure without inflicting any structural alterations. With the increase of dopant concentration in the sample a decrease of the mean particle size was observed. Also, the vibrational peak intensities decreased while the intensity of the photoluminescence excitation bands increased in intensity when the cerium concentration increased from x(Ce) = 0.01 to x(Ce) = 0.05. Taken together, the results suggest that even low concentration of cerium influence the properties of hydroxyapatite but do not-cause any structural alterations.

415. STRUCTURAL AND MORPHOLOGICAL EVOLUTIONS INDUCED BY THE ANNEALING OF CaF2 NANOCRYSTALLINE POWDERS BY USING Eu3+ ION PROBE LUMINESCENCE

Authors: Polosan, S; Secu, M; Enculescu, M

Published: APR-JUN 2016, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 11, 624, DOI:

Eu-doped CaF(2)nanocrystalline powders have been prepared by using co-precipitation technique. Structural and morphological modifications induced by annealing are followed by using Eu3+-ion probe. Theluminescence properties are changing gradually together with the morphology of doped CaF2 nanoparticles accompanied by anEu(3+)-> Eu2+ conversion. Cathodoluminescence measurements show uniform distribution of the europium dopant ions in the annealed samples accompanied by a strong increase of the integral photoluminescence signal. During annealing the cubic structure of CaF2 nanoparticles is altered going to the spherical morphology due to the Eu3+ ions incorporation. In the annealed samples Eu3+ ions are incorporated as Eu3+-O dimer centres with the coordination symmetry (C-2 nu); in the sintered samples there are two non-equivalent Eu3+ sites. The thermoluminescence peaks have been assigned to the recombination of the Eu3+ related traps in these sites.

416. SOL-GEL TEMPLATE ASSISTED SYNTHESIS AND UP-CONVERSION PROPERTIES OF (Yb-Er) DOPED SiO2-LiYF4 GLASS CERAMIC RODS

Authors: Secu, CE; Matei, E

Published: APR-JUN 2016, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 11, 494, DOI:

Up-conversion properties of the glass-ceramics microrods containing (Er3+, Yb3+)-doped LiYF4 nanocrystals have been studied. Under 980 nm laser light pumping, both Yb3+/Er3+ co-doped LiYF4 samplesshow green ((H-2(11/2), S-4(3/2)) -> I-4(15/2)) and red (F-4(9/2) -> I-4(15/2)) up-conversion luminescences explained by a two-photon processes. The luminescence decay time of the green luminescence is much shorter in the glass-ceramics microrods (0.9 mu s) compared to the bulk powder (15 mu s) indicating the enhancement of the non-radiative relaxation rate due to the cross-relaxation effects between Er3+-ions. The quantum efficiencies were estimated for the green luminescence being much smaller in the glass-ceramic rods (eta = 0.15%) compared the bulk powder (eta = 2%) or pellet (eta = 46%).

417. BIOLOGICAL STUDIES ON DEXTRIN COATED IRON OXIDE NANOPARTICLES

Authors: Iconaru, SL; Turculet, C; Le Coustumer, P; Bleotu, C; Chifiriuc, MC; Lazar, V; Surugiu, A; Badea, M; Iordache, FM; Soare, M; Prodan, AM

Published: 2016, ROMANIAN REPORTS IN PHYSICS, 68, 1544, DOI:

In this study, dextrin coated iron oxide nanoparticles were obtained using an adapted chemical co-precipitation method. The size and morphology of the dextrin coated iron oxide nanoparticles (DIO-NPs) were analyzed by transmission electron microscopy (TEM). The scanning electron microscopy (SEM) analysis depicted information on the morphology of DIO-NPs. The elemental analysis was conducted by Energy-dispersive X-ray spectroscopy (EDAX). The iron oxide particles coated with dextrin have a spherical shape at nanometric scale with a narrow size distribution. The cytotoxicity assay was performed by quantification of HeLa cells viability, while the antimicrobial activities of the DIO-NPs were determined against ATCC reference and clinical microbial strains, i.e. Gram-positive bacteria (Staphylococcus aureus ATCC 6538) and yeast (Candida albicans 393). The obtained nanoparticles did not have cytotoxic effect on HeLa cells after a 24 h exposure to DIO-NPs and the morphology of the cells was not affected. A low toxic effect on HeLa cells was noticed after 48 h. The minimal inhibitory concentration of DIO-NPs was 1 mg/mL for both tested microbial strains.

418. POLYESTER FABRICS COVERED WITH AMORPHOUS TITANIUM DIOXIDE LAYERS: COMBINING WETTABILITY MEASUREMENTS AND PHOTOINDUCED HYDROPHILICITY TO ASSESS THEIR SURFACE PROPERTIES

Authors: Zgura, I; Frunza, S; Frunza, L; Enculescu, M; Florica, C; Cotorobai, VF; Ganea, CP

Published: 2016, ROMANIAN REPORTS IN PHYSICS, 68, 269, DOI:

Wettability properties of thin TiO2 amorphous layers obtained by sputtering or sol-gel onto polyester textile materials were investigated. Contact angle (CA) measurements by the sessile drop method were used to evaluate these properties. Comparison was performed with coated samples of related poly(lactic acid) material. The samples coated by sol gel have CAs a few degrees higher than those coated by sputtering. Wetting properties were conversely changed under alternate darkness/illumination conditions. Photoinduced hydrophilicity was observed even for these amorphous coating particles, being higher for sputtered samples than for sol gel ones.

419. Carbon Nanotubes-Hydroxyapatite Nanocomposites for an Improved Osteoblast Cell Response

Authors: Constanda, S; Stan, MS; Ciobanu, CS; Motelica-Heino, M; Guegan, R; Lafdi, K; Dinischiotu, A; Predoi, D

Published: 2016, JOURNAL OF NANOMATERIALS, 2016, DOI: 10.1155/2016/3941501

An alternative and simple coprecipitation method was developed to obtain carbon nanotube-hydroxyapatite (CNTs:HAp) based nanocomposites. The incorporation of CNTs (in a concentration of 5% and 10% of total weight of the nanocomposite) and their impact on both structural and biological properties were studied by using a set of standard complementary biological, microscopic, and spectroscopic techniques. The characteristic peaks of carbon structure in CNTs were not observed in the CNTs-HAp composites by X-ray diffraction analysis. Moreover, FTIR and Raman spectroscopies confirmed the presence of HAp as the main phase of the synthesized CNTs: HAp nanocomposites. The addition of CNTs considerably affected the nanocomposite morphology by increasing the average crystallite size from 18.7 nm (for raw HAp) to 28.6 nm (for CNTs:HAp-10), confirming their proper incorporation. The biocompatibility evaluation of CNTs:HAp-5 and CNTs:HAp-10 nanocomposites included the assessment of several parameters, such as cell viability, antioxidant response, and lipid peroxidation, on human G-292 osteoblast cell line. Our findings revealed good biocompatibility properties for CNTs: HAp nanocomposites prepared by the coprecipitation method supporting their potential uses in orthopedics and prosthetics.

420. Cerium-doped hydroxyapatite nanoparticles synthesized by the co-precipitation method

Authors: Ciobanu, CS; Popa, CL; Predoi, D

Published: 2016, JOURNAL OF THE SERBIAN CHEMICAL SOCIETY, 81, 446, DOI: 10.2298/JSC150824007C

The present work reports a simple adapted co-precipitation method for the synthesis of stable Ce-substituted Ca hydroxyapatite (HAp) nanoparticles. The structural and morphological properties of the Ce-doped hydroxyapatite (Ce:HAp) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). The optical properties of the Ce-doped hydroxyapatite were also investigated using Fourier transform infrared (FTIR) spectroscopy, Fourier transform Raman spectroscopy and photoluminescence analysis. The results of the XRD studies revealed the progressive increase in the a-and c-axes with increasing Ce concentration. In the FTIR studies of Ce: HAp powders, a structure similar to that of hydroxyapatite was observed. The IR and Raman wavenumbers and the peak strengths of the bands associated with the P-O and O-H bonds decreased progressively with increasing Ce concentration. All the emission maxima could be attributed to 5d-4f transitions of the Ce ions. The displacements of the maximum emission bands with increasing Cerium in the samples were in agreement with the results obtained by XRD studies. The Ce: HAp samples with x(Ce) = 0.03 and 0.05 exhibited significant antibacterial activity against Staphylococcus aureus and Escherichia coli bacterial strains compared to Ce: HAp samples with xCe = 0 (pure HAp) and 0.01.