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91.
Ovidiu Chiscan Ioan Dumitru Vasile Tura Alexandru Stancu 《Journal of Materials Science》2012,47(5):2322-2327
In this article, we present a study on the microwave frequency properties of poly(vinyl chloride)/Fe composite nanofibers,
with different concentrations of iron particles incorporated in poly(vinyl chloride) matrix. Using electrospinning, composite
nanofibers were obtained with size ranging between 100 and 500 nm. The absorption properties of synthesized nanofibers were
measured between two open-end rectangular waveguides in the 8–12 GHz frequency domain. The transmission loss measurements
for poly(vinyl chloride)/Fe composite nanofibers demonstrated that this material can be used as protection material in X-band
frequency domain. The applied magnetic field significantly modifies the measured scattering parameters in our samples case
in a rather large domain of values for the field. 相似文献
92.
Ovidiu Cârjă Manuel D.P. Monteiro Marques 《Journal of Dynamical and Control Systems》2002,8(4):445-461
New results on weak invariance in Hilbert spaces, both in autonomous and nonautonomous case, are given. Applications to weakly decreasing systems and to strong invariance are presented. 相似文献
93.
94.
Ovidiu Ghita Paul F. Whelan David Vernon John Mallon 《Machine Vision and Applications》2007,18(6):355-365
In this paper we present a novel method for estimating the object pose for 3D objects with well-defined planar surfaces. Specifically,
we investigate the feasibility of estimating the object pose using an approach that combines the standard eigenspace analysis
technique with range data analysis. In this sense, eigenspace analysis was employed to constrain one object rotation and reject
surfaces that are not compatible with a model object. The remaining two object rotations are estimated by computing the normal
to the surface from the range data. The proposed pose estimation scheme has been successfully applied to scenes defined by
polyhedral objects and experimental results are reported. 相似文献
95.
Andreea Iren Serban Loredana Stanca Ovidiu Ionut Geicu Anca Dinischiotu 《International journal of molecular sciences》2015,16(9):20100-20117
Advanced glycation end products (AGEs) can activate the inflammatory pathways involved in diabetic nephropathy. Understanding these molecular pathways could contribute to therapeutic strategies for diabetes complications. We evaluated the modulation of inflammatory and oxidative markers, as well as the protective mechanisms employed by human embryonic kidney cells (HEK 293) upon exposure to 200 μg/mL bovine serum albumine (BSA) or AGEs–BSA for 12, 24 and 48 h. The mRNA and protein expression levels of AGEs receptor (RAGE) and heat shock proteins (HSPs) 27, 60 and 70, the activity of antioxidant enzymes and the expression levels of eight cytokines were analysed. Cell damage via oxidative mechanisms was evaluated by glutathione and malondialdehyde levels. The data revealed two different time scale responses. First, the up-regulation of interleukin-6 (IL-6), HSP 27 and high catalase activity were detected as early as 12 h after exposure to AGEs–BSA, while the second response, after 24 h, consisted of NF-κB p65, RAGE, HSP 70 and inflammatory cytokine up-regulation, glutathione depletion, malondialdehyde increase and the activation of antioxidant enzymes. IL-6 might be important in the early ignition of inflammatory responses, while the cellular redox imbalance, RAGE activation and NF-κB p65 increased expression further enhance inflammatory signals in HEK 293 cells. 相似文献
96.
97.
Tamara Slatineanu Alexandra Raluca Iordan Victor Oancea Mircea Nicolae Palamaru Ioan Dumitru Cristin Petrica Constantin Ovidiu Florin Caltun 《Materials Science and Engineering: B》2013,178(16):1040-1047
Nanocrystalline powders of Co substituted Zn ferrite with the chemical formula CoxZn1−xFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) were synthesized by sol–gel autocombustion method using tartaric acid as fuel agent. The samples were sintered in static air atmosphere for 7 h at 773 K, 7 h at 973 K and 10 h at 1173 K. The organic phase extinction and the spinel phase formation were monitored by means of Fourier transform infrared spectroscopy. The X-ray diffraction patterns analysis confirmed the spinel single phase accomplishment. Crystallite size, average grains size, lattice parameter and cation distribution were estimated. Magnetic behavior of the as-obtained samples by means of M-H hysteresis measurements was studied at room temperature. Permeability and dielectric permittivity at room temperature versus frequency was the subject of a comparative study for the CoxZn1−xFe2O4 series. In agreement with the proposed cation distribution the sample with Co0.8Zn0.2Fe2O4 formula exhibits the optimal magnetic and dielectric properties. 相似文献
98.
This work reports on the morphology of individual platinum nanocrystals with sizes of about 5 nm. By using the electron tomography technique that gives 3D spatial selectivity, access to quantitative information in the real space was obtained. The morphology of individual nanoparticles was characterized using HAADF-STEM tomography and it was shown to be close to a truncated octahedron. Using molecular dynamics simulations, this geometrical shape was found to be the one minimizing the nanocrystal energy. Starting from the tomographic reconstruction, 3D crystallographic representations of the studied Pt nanocrystals were obtained at the nanometer scale, allowing the quantification of the relative amount of the crystallographic facets present on the particle surface. 相似文献
99.
The morphologies of Au and Au@Ag nanobipyramids were investigated using electron tomography. The 3D reconstruction reveals that the Au bipyramids have an irregular six-fold twinning structure with highly stepped dominant {151} facets. These short steps/edges stabilized via surface adsorbed CTAB favor the growth of silver on the lateral facets leading to strong blue shifts in longitudinal plasmon surface resonance. 相似文献
100.
Felicia Gheorghiu Cristina Elena Ciomaga Mantas Simenas Mirela Airimioaei Shan Qiao Sorin Tascu Vidmantas Kalendra Juras Banys Ovidiu G. Avadanei Liliana Mitoseriu 《Ceramics International》2018,44(17):20862-20870
Diluted magnetic oxides attracted a great interest in the last years as materials for spintronics and magnetoelectric devices. We propose in the present paper such a magnetoelectric ceramic system for an application as miniaturized resonator antenna in GHz range. BaTi1-xFexO3-x/2 (0?≤?x?≤?0.02) polycrystalline ceramics have been produced by solid state reaction. X-ray diffraction analysis and Rietveld refinement have shown that Fe doping of BaTiO3 lattice produces a transition from tetragonal crystalline symmetry (for x?≤?0.01) to a superposition of tetragonal and hexagonal phases for the compositions x?=?0.015 and 0.02. As result of Fe addition, the Curie temperature of BaTi1-xFexO3-x/2 ceramics exhibit a shift from 127?°C towards lower values and reaches 85?°C for x?=?0.02. A competition between weak ferromagnetic and antiferromagnetic character as a function of composition and temperature is determined both by the presence of transition metal ion and of the oxygen vacancies. Due to its electromagnetic properties, an optimized composition x?=?0.01 was used for producing a miniaturized antenna which was found to show a frequency dependent S11 response similar to the simulated one. 相似文献