Phase mode analysis of directional elements in a circular array
A technique for analyzing the directional elements of a circular array is presented. The technique is based on phase mode decomposition of measured element patterns. It can be used to calibrate the array and may help identify sources of measurement errors. It is illustrated with patterns from a 108-element circular array.
A FOURIER PHASE MODE APPROACH FOR CHEBYSHEV PATTERN SYNTHESIS IN CIRCULAR ANTENNA ARRAY
In this article, a novel phase mode analysis for a circular antenna array is discussed. This proposition experiments on the synthesis of Dolph-Chebyshev pattern for circular geometry employing directional element 1 + cos(φ). Here, for pattern synthesis a modified uniform sampling method is proposed, and for investigation of continuous current excitation in a circular array, a Fourier phasemode approach is proposed. The synthesis process permits generation of complex weights for each element to produce the Chebyshev pattern with a desired beamwidth or Side Lobe Level (SLL). The radius is a key factor for a circular geometry and also decides the pattern synthesis, which is determined by using the phase mode concept. Also, this article contributes to the formulation of a mathematical relationship between the number of phase modes (P ) and the number of antenna elements in the array (N) such as N = 2(P − 1).
Cross talk between redox signalling and metabolic activity of osteoblasts and fibroblasts in the presence of hydroxyapatite-based biomaterials influences bone regeneration
Regeneration of bone tissue defects that result from metabolic disorders, including periodontal diseases, can be supported by biomaterials based on hydroxyapatite. Despite of good biocompatibility of biomaterials they can cause oxidative stress and inflammatory processes as a result of mechanical interaction with surrounding tissues. Because osteoblasts are responsible for bone regeneration process in which gingival fibroblasts may also participate, the aim of the work was to investigate the influence of hydroxyapatite-based biomaterials (allogeneic and xenogeneic) and biomaterials combined with enamel matrix derivative (Emdogain) on osteoblast and fibroblast redox balance in the context of osteoblast proliferation and differentiation.
The results showed that examined substitutes were not cytotoxic in vitro, but affected redox balance of osteoblasts and fibroblasts (ROS level increase and GSH level decrease) which led to oxidative stress (MDA and protein carbonyl groups level increase) resulting in an increase of the Nrf2 and NFκB expression. The consequence of these changes was partial inhibition of proliferation and osteoblast differentiation. Emdogain alone and combined with biomaterials decreased ROS generation and increased GSH level in both osteoblasts and fibroblasts leading to reduction of transcription factors expression especially proinflammatory NFκB, which promoted osteoblast differentiation and mineralization process.