National Institute Of Materials Physics - Romania

Publications

5714 articles found

1911. EFFECT OF CHOLESTEROL ON THE DEPOSITION OF BETA-AMYLOID 1-40 AND 1-42 FILMS

Authors: Breazu, C; Stanculescu, A; Socol, M; Rasoga, O

Published: JAN-MAR 2015, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 10, 313, DOI:

We report the pressure vs area isotherms of Langmuir films of pure and doped with cholesterol (Ch) amyloid beta, A beta (1-40) and (1-42) at the air-water interface and, scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies of A beta (1-40) and (1-42) layers deposited from solution by drop cast and/or dipping and/or Langmuir-Blodgett on substrates of quartz and Si. The particularity of the substrate surface morphology determines the adhesion forces and plays an important role in the formation and stability of the multilayer films which are deposited on these substrates. The effect of cholesterol on the morphology of amyloids films and appearance of fibril structures is also analysed. AFM investigations have revealed the particularities of the aggregation process of the strongly hydrophobic A beta (1-42) on cholesterol films deposited by Langmuir-Blodgett on solid support of quartz and Si.

1912. Physicochemical Analysis of the Polydimethylsiloxane Interlayer Influence on a Hydroxyapatite Doped with Silver Coating

Authors: Popa, CL; Groza, A; Chapon, P; Ciobanu, CS; Ghita, RV; Trusca, R; Ganciu, M; Predoi, D

Published: 2015, JOURNAL OF NANOMATERIALS, 2015, DOI: 10.1155/2015/250617

We investigate by different complementary methods the processes occurring when a polydimethylsiloxane film is used as interlayer for a silver doped hydroxyapatite coating. The X-ray diffraction and Fourier Transform Infrared Spectroscopy measurements show that the hydroxyapatite doped with silver is in a crystalline form and some SiO44- ions formation takes place at the surface and in the bulk of the new hydroxyapatite doped with silver/polydimethylsiloxane composite layer. The possibility of SiO44- ions incorporation in the structure of silver doped hydroxyapatite by the mechanism of SiO44-/PO43- ions substitution is analysed. The new formed silver doped hydroxyapatite/polydimethylsiloxane composite layer is compact, homogeneous, with no cracks as it was shown by Scanning Electron Microscopy and Glow Discharge Optical Emission Spectrometry.

1913. TIME-FREQUENCY DOMAIN RADAR CROSS SECTION EVALUATION OF AN IAR 99 SCALED MODEL AIRCRAFT

Authors: Tusa, L; Nicolaescu, I; Moni, M; Banciu, MG

Published: 2015, PROCEEDINGS OF THE 2015 7TH INTERNATIONAL CONFERENCE ON ELECTRONICS, COMPUTERS AND ARTIFICIAL INTELLIGENCE (ECAI), DOI:

Radar Cross Section (RCS) is a very important parameter of an aircraft. It is given by the overall signal reflected by the target when it is irradiated by electromagnetic waves in order to be detected and localized. The measurement of RCS for some aircrafts in real scenarios is a very complex and costly process because it needs a certain area for experiments, special equipment and a number of flights. Hence, in most cases the evaluation of RCS is made by measuring a scaled model aircraft in an anechoic chamber. This paper proposes a measurement scenario for IAR 99 and analysis the experimental data. This is the first evaluation of the IAR 99 radar cross section using measurements in time and frequency domain.

1914. INTRABAND RELAXATION OF p-SHELL EXCITONS IN DISK-SHAPED QUANTUM DOTS

Authors: Dragomir, R; Moldoveanu, V; Dinu, IV

Published: 2015, ROMANIAN JOURNAL OF PHYSICS, 60, 690, DOI:

We study the generation of p-shell excitons in optically active disk-shaped quantum dots subjected to ultrafast optical pulses. The single-particle spectral properties are obtained from the four-band kp theory, whereas the Coulomb interaction is taken into account within the configuration-interaction approach, particular attention being payed to configuration mixing due to electron-hole correlations. The effect of intraband relaxation processes is included in the non-unitary dynamics derived from the von-Neumann Lindblad equation. We find that the fast hole relaxation processes drive the p-shell excitons to intermediate states which eventually evolve to s-shell excitons via slower electron relaxation.

1915. A new class of thermotropic lanthanidomesogens: Eu(III) nitrate complexes with mesogenic 4-pyridone ligands

Authors: Pana, A; Chiriac, FL; Secu, M; Pasuk, I; Ferbinteanu, M; Micutz, M; Circu, V

Published: 2015, DALTON TRANSACTIONS, 44, 14199, DOI: 10.1039/c5dt01197c

A new class of thermotropic lanthanidomesogens has been designed and prepared. They are based on 4-pyridone ligands that possess mesogenic cyanobiphenyl groups attached to the 4-pyridone unit via a flexible long alkyl spacer and show a very high thermal stability (decomposition temperatures near 300 degrees C). Depending on the alkyl length spacer, these complexes exhibit a SmA phase with transition temperatures influenced by the number of mesogenic groups employed and the spacer length.

1916. Exotic Superconductivity in Correlated Electron Systems

Authors: Mu, G; Sandu, V; Li, W; Shen, B

Published: 2015, ADVANCES IN CONDENSED MATTER PHYSICS, 2015, DOI: 10.1155/2015/180195

1917. Evaluation of Samarium Doped Hydroxyapatite, Ceramics for Medical Application: Antimicrobial Activity

Authors: Ciobanu, CS; Iconaru, SL; Popa, CL; Motelica-Heino, M; Predoi, D

Published: 2015, JOURNAL OF NANOMATERIALS, 2015, DOI: 10.1155/2015/849216

Samarium doped hydroxyapatite (Sm:HAp), Ca10-xSmx(PO4)(6)(OH)(2) (HAp), bionanoparticles with different x(Sm) have been successfully synthesized by coprecipitation method. Detailed characterization of samarium doped hydroxyapatite nanoparticles (Sm: HAp-NPs) was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The biocompatibility of samarium doped hydroxyapatite was assessed by cell viability. The antibacterial activity of the Sm: HAp-NPs was tested against Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) andGram-positive bacteria (Enterococcus faecalis and Staphylococcus aureus). A linear increase of antimicrobial activity of P. aeruginosa has been observed when concentrations of Sm: HAp-NPs in the samples with x(Sm) = 0.02 were higher than 0.125 mg/mL. For Sm: HAp-NPs with x(Sm) = 0.05 a significant increase of antibacterial activity on E. coli was observed in the range 0.5-1 mg/mL. For low concentrations of Sm: HAp-NPs (x(Sm) = 0.05) from 0.031 to 0.125 mg/mL a high antibacterial activity on Enterococcus faecalis has been noticed. A growth of the inhibitory effect on S. aureus was observed for all concentrations of Sm: HAp-NPs with x(Sm) = 0.02.

1918. New antennas with dielectric resonators of axial symmetry

Authors: Geambasu, DC; Banciu, MG; Nedelcu, L; Ramer, R

Published: 2015, 2015 INTERNATIONAL SEMICONDUCTOR CONFERENCE (CAS), 142, DOI:

New type of dielectric resonator antennas (DRAs) with axial symmetry are proposed for frequencies around 5.8 GHz. Each element uses a high permittivity cylindrical resonator and a low permittivity resonator of a truncated cone shape. Two types of microstrip-fed DRAs were investigated. By coupling the resonance modes, the first type and the second type DRA exhibit fractional impedance bandwidth of 15.6% and 19.7%, respectively.

1919. Advances in Functionalized Materials Research

Authors: Predoi, D; Motelica-Heino, M; Le Coustumer, P

Published: 2015, JOURNAL OF NANOMATERIALS, 2015, DOI: 10.1155/2015/412690

1920. Cylindrical Dielectric Resonator Antenna for Wireless Applications

Authors: Moni, MV; Banciu, G; Tuta, L

Published: 2015, 2015 23RD TELECOMMUNICATIONS FORUM TELFOR (TELFOR), 264, DOI:

The paper presents a CDRA (Cylindrical Dielectric Resonator Antenna) designed for wireless military and commercial applications. The antenna has been designed to radiate at 6.7 GHz, with a 160 MHz bandwidth at -10 dB. The antenna is made from a dielectric material with high quality factor. The dielectric resonator is Ba1-xPbxNd2Ti5O14 (BNT) and its relative permittivity has a value of 55.2. The feed technique used is direct coupling to micro strip-line.