Antenna properties

After this overview of photonic antenna properties, we now turn to some intriguing optical properties we have recently observed in different dye-zeolite guest-host composites. 

The dye-zeolite composites reported so far show fascinating photonic antenna properties which are perhaps comparable to some extent to those of natural systems. Tuning their chemical and photochemical behavior, organizing information exchange between their inside and the external world, but also organizing individual crystals on a surface in order to realize, for example, monodirectional functionalities remain a challenge which we address in this section. 

Method C and Method D are again similar to that described above. In each case the antenna is structurally modified to accommodate a receptor allowing for the inclusion of a guest. This guest inclusion results in changes in the antenna properties, such as alterations in the effectiveness of the sensitisation process, the intensity/quantum yield, as well as to the lifetime of the metal-centred luminescence. 

According to modern taxonomy, four divisions of photosynthetic bacteria are discerned (1) the purple bacteria, the green sulfur bacteria (Chlorobiaceae), the green filamentous (or gliding) bacteria (Chloroflexaceae) and the heliobacteria. This contribution concerns the antenna properties of the last three groups groups which have been studied less extensively than the purple bacteria, but which are not less interesting from the scientific point of view. 

Semiconductor nano element devices show great promise, potentially outperforming standard electrical, opt-electrical, and sensor- etc. semiconductor devices. These devices can use certain nano element specific properties, 2-D, 1-D, or 0-D quantum confinement, flexibility in axial material variation due to less lattice match restrictions, antenna properties, ballistic transport, wave guiding properties etc. Furthermore, in order to design first rate semiconductor devices from nanoelements, transistors, light emitting diodes, semiconductor lasers, and sensors, and to fabricate efficient contacts, particularly with low access resistance, to such devices, the ability to dope and fabricate doped regions is cracial [66, 67]. 

A microstrip patch is a representative candidate for a wearable integration, because it can be thin, lightweight, low maintenance, robust, and easily integrated into a garment and coupled with RF circuits (Wang et al., 2012). Moreover, the conductive textile used for antenna purposes has to have a low and stable electrical resistivity (<10/sq.) to minimize losses (Locher et al., 2006). Several properties of the materials can influence the behavior of the antenna properties. For instance, the permittivity and the thickness of the substrate change the bandwidth and the efficiency of a planar microstrip antenna (Liu et al., 2011). In general, fabrics present a complex structure, in term of density of fibers and hence air volume and size of the pores, which allow a very low dielectric constant with a reduction of the surface wave losses and an increase of the impedance bandwidth. 

Boron has high neutron absorption and the boron-aluminum composites are being investigated for nuclear applications. Single-ply boron-epoxy composites have microwave polarization properties with potential applications in antenna and radome designs. 01... 

The properties of these rotaxane dendrimers are quite different from those of the individual rotaxanes or dendrimers and often a blend of both. In view of the versatile characteristics that a dendron or dendrimer can manifest, several new properties can be imparted to the rotaxanes. For example, the solubility of rotaxanes in organic solvents as well as in water can be significantly improved when large dendrimer units are appended enhancing the prospects of their use as molecular machines. The dendritic units can also influence the photo/electro-chemical properties of the rotaxanes. Employing photo-receptive dendron units, photo chemically driven molecular machines may be developed, where the dendrons act as antenna for photo-harvesting [62]. 

Square-planar zinc compounds predominate with these ligand types as would be predicted. This is in contrast to the prevalence of tetrahedral or distorted tetrahedral geometries for four-coordinate species that have been discussed thus far. Zinc porphyrin complexes are frequently used as building blocks in the formation of supramolecular structures. Zinc porphyrins can also act as electron donors and antenna in the formation of photoexcited states. Although the coordination of zinc to the porphyrin shows little variation, the properties of the zinc-coordinated compounds are extremely important and form the most extensively structurally characterized multidentate ligand class in the CSD. The examples presented here reflect only a fraction of these compounds but have been selected as recent and representative examples. Expanded ring porphyrins have also... 

The photoactive properties and potential for use of some of these compounds as photoactive antennas have been explored. Electron transfer studies between C60 fullerene and zinc porphyrins... 

It is therefore important to bear in mind the dependency of the carotenoid spectrum upon properties of the environment for in vivo analysis, which is based on the application of optical spectroscopies. This approach is often the only way to study the composition, structure, and biological functions of carotenoids. Spectral sensitivity of xanthophylls to the medium could be a property to use for gaining vital information on their binding sites and dynamics. The next sections will provide a brief introduction to the structure of the environment with which photosynthetic xanthophylls interact—light harvesting antenna complexes (LHC). 

Absorption and Raman analysis of LHCII complexes from xanthophyll biosynthesis mutants and plants containing unusual carotenoids (e.g., lactucoxanthin and lutein-epoxide) should also be interesting, since the role of these pigments and their binding properties are unknown. Understanding the specificity of binding can help to understand the reasons for xanthophyll variety in photosynthetic antennae and aid in the discovery of yet unknown functions for these molecules. 

Metal dendrimers containing photoactive units exhibit very interesting properties, both from a fundamental and applicative viewpoint. For example, well-designed photoactive dendrimers can play the role of artificial antennae in supra-molecular structures devoted to solar energy conversion [37,47]. Photophysical... 

Kawa, M., and Frechet, J.M.J. (1998) Self-assembled lanthanide-cored dendrimer complexes enhancement of the luminescence properties of lanthanide ions through site-isolation and antenna effects. Chem. Mater. 10, 286-296. 

The dimensions and properties of the lamp envelope are based on the discovery that the volume of Hg is critical for the effective UV operation [43]. Higher Hg pressures result in the need to use higher MW power levels. To focus the MW field efficiently into the EDL a special Cd low-pressure lamp with a metal antenna (a molybdenum foil) was developed by Florian and Knapp [44],... 

Since the properties of the modular components are known and different modules can be located in the desired positions of the dendrimer array, synthetic control of the various properties can be obtained. It is therefore possible, as schematically shown in Figure 2, to construct arrays where the electronic energy migration pattern can be predetermined, so as to channel the energy created by light absorption on the various components towards a selected module (antenna effect). 

Our neurophysiological studies have focused on three important properties of the sex-pheromonal signal its quality (chemical composition of the blend), quantity (concentrations of components), and intermit-tency [owing to the fact that the pheromone in the plume downwind from the source exists in filaments and blobs of odor-bearing air interspersed with clean air (47, 48)]. Each of these properties of the pheromonal message is important, as the male moth gives his characteristic behavioral responses only when the necessary and sufficient pheromone components A and B are present in the blend (44), when the concentrations and blend proportions of the components fall within acceptable ranges (49), and when the pheromone blend stimulates his antennae intermittently (39, 50). In our studies, we examine how each of these important aspects of the odor stimulus affects the activity of neurons at various levels in the olfactory pathway. 

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