Performance Assessment of Optical Burst Switching Ring and Chordal Ring Networks

This paper presents a performance analysis of optical burst switching (OBS) networks with ring and chordal ring topologies. The performance analysis considers signaling protocols with one-way reservation schemes, being focused on the following protocols: just-in-time (JIT), Jumpstart, JIT⁺, just-enough-time (JET) and Horizon. It is shown that for a network with 20 nodes, the nodal degree gain due to the increase of nodal degree from two (ring) to three (chordal ring) is about three orders of magnitude in the first hop of both topologies, and is between two and three orders of magnitude in the last hop of each topology. It is also shown that the largest chord length gain, in a 20-node OBS network with a chordal ring topology, is slightly less than two orders of magnitude.     

Atomic force microscopy study of comb-like vs. arborescent graft copolymers in thin films

This work deals with the study of comb-like vs. arborescent grafted copolymers made of poly(chloroethyl vinyl ether)-g-polystyrene (PCEVE-g-PS). We describe how the molecular architecture of the branched polymers affects their nanoscale organization in thin films, as observed using atomic force microscopy. The results indicate that modifying the molecular architecture from a ‘generation-zero’ comb-like (PCEVE-g-PS) to a ‘first-generation’ hyperbranched (PCEVE-g-(PS-b-PCEVE-g-PS)) architecture strongly modifies the observed geometrical parameters of the molecules, in good agreement with the expected evolution of the molecular dimensions and the corresponding data obtained in solution.The surface organization of the (PCEVE-g-PS) copolymer molecules is also strongly conditioned by the interplay between the molecule-substrate interactions and the molecule-molecule interactions, leading to different possible orientations of the lateral branches with respect to the surface and thus to different final morphologies.     

Nanocrystalline Titanium Oxide Electrodes for Photovoltaic Applications

During the past five years, we have developed in our laboratory a new type of solar cell that is based on a photoelectrochemical process. The light absorption is performed by a monolayer of dye (i.e., a Ruthenium complex) that is adsorbed chemically at the surface of a semiconductor (i.e., titanium oxide (TiO₂)). When excited by a photon, the dye has the ability to transfer an electron to the semiconductor. The electric field that is inside the material allows extraction of the electron, and the positive charge is transferred from the dye to a redox mediator that is present in solution. A respectable photovoltaic efficiency (i.e., 10%) is obtained by the use of mesoporous, nanostructured films of anatase particles. We will show how the TiO₂ electrode microstructure influences the photovoltaic response of the cell. More specifically, we will focus on how processing parameters such as precursor chemistry, temperature for hydrothermal growth, binder addition, and sintering conditions influence the film porosity, pore-size distribution, light scattering, and electron percolation and consequently affect the solar-cell efficiency.     

Design of a gaussian optic lens antenna and effective parameters study

The optimization of a Gaussian optic lens antenna design is considered using a previously exposed model. After discussing the global task, results with a few varying geometrical parameters are presented which study their effects on certain radiation characteristics such as the half pattern aperture angles 3 dB and 10 dB below the axial maximum, the sidelobes level or the beam efficiency. Finally, we are able to conclude on the complexity and the difficulty of optimizing such an antenna.     

Eye movements, prematurity and developmental co-ordination disorder

Horizontal pursuit eye movements were investigated in two separate groups of children: One group exhibited developmental co-ordination disorder (n = 8) whilst another group of children were born prematurely (n = 8). Both studies found a reduced gain in pursuit eye movements when the respective populations were compared with control groups (n = 32). A difference was also found in the ability of some children to temporally synchronize their tracking response to the stimulus, which was indicative of poor predictive control rather than lags in the control system. We suggest that horizontal eye movements may be a sensitive indicator of more general motor deficits during childhood development.     

Nitrogen and phosphorus benefits from faba bean (Vicia faba L.) residues to subsequent wheat crop in the humid highlands of Ethiopia

Faba bean–wheat rotation is one of the traditional cropping systems in most parts of the temperate, Mediterranean and tropical highland areas. However, the net contribution of legumes to soil nutrient balance is determined by the extent to which crop residue is removed from the field. Therefore, we assessed two possible faba bean residue management scenarios and their role in the faba bean–wheat rotation system in a two-phase field experiment. We further tested to what extent high N₂-fixing and P efficient faba bean varieties could benefit subsequently grown wheat. In the first phase, three improved faba bean varieties (Degaga, Moti, Obse) were grown at four levels of P fertilization (0, 10, 20 and 30 kg P ha^?1) along with local faba bean and reference wheat but without any fertilization. N₂-fixation, soil N balance and P uptake were determined for the faba beans. The N balance was determined via two possible residue management scenarios: scenario-I assumed that all the aboveground biomass is exported from the fields; scenario-II assumed that all the above ground biomass except grains and empty pods is incorporated to the soil. In the second phase, the N and P benefits of faba beans to rotational wheat were assessed. Scenario-I gave a negative net N balance (kg N ha^?1) in the range of ?86.5 ± 5.8 (Degaga) to ?9.4 ± 8.7 (Moti) with significant differences between varieties. Scenario-II showed that all balances were significantly (P < 0.01) improved and the varieties were positively contributing N to the system in the range of 50.6 ± 13.4 (Degaga) to 168.3 ± 13.7 (Moti) kg N ha^?1, which is equivalent to 110–365 kg N ha^?1 in the form of urea (46 % N). In the second crop phase, biomass and grain yield of wheat grown after the faba beans improved significantly (P < 0.05) by 112 and 82 %, respectively compared to the yield of wheat after wheat. Phosphorus application to the preceding faba bean varieties significantly improved total biomass and grain yield of the succeeding wheat (R² = 0.97). The incorporated legume root, nodule and straw clearly played a role in improving wheat yield through N addition via BNF and straw P. The study demonstrates the prospects and importance of improved faba bean germplasm and management as a key component for sustainable wheat based cropping systems in the humid tropical highlands.     

Photoresponsive Cucurbit[8]uril‐Mediated Adhesion of Bacteria on Supported Lipid Bilayers

In this work, the development of a photoresponsive platform for the presentation of bioactive ligands to study receptor–ligand interactions has been described. For this purpose, supramolecular host–guest chemistry and supported lipid bilayers (SLBs) have been combined in a microfluidic device. Quartz crystal microbalance with dissipation monitoring (QCM‐D) studies on methyl viologen (MV)‐functionalized oligo ethylene glycol‐based self‐assembled monolayers, gel and liquid‐state SLBs have been compared for their nonfouling properties in the case of ConA and bacteria. In combination with bacterial adhesion test, negligible nonspecific bacterial adhesion is observed only in the case of methyl‐viologen‐modified liquid‐state SLBs. Therefore, liquid‐state SLBs have been identified as most suitable for studying specific cell interactions when MV is incorporated as a guest on the surface. The photoswitchable supramolecular ternary complex is formed by assembling cucurbit[8]uril (CB[8]) and an azobenzene–mannose conjugate (Azo–Man) onto MV‐functionalized liquid‐state SLBs and the assembly process has been characterized using QCM‐D and fluorescence techniques. Mannose has been found to enable binding of E. coli via cell‐surface receptors on the nonfouling supramolecular SLBs. Optical switching of the azobenzene moiety allows us to “erase” the bioactive surface after bacterial binding, providing the potential to develop reusable sensors. Localized photorelease of bacterial cells has also been shown indicating the possibility of optically guiding cellular growth, migration, and intercellular interactions.     

Real‐Time Analysis of Magnetic Hyperthermia Experiments on Living Cells under a Confocal Microscope

Combining high‐frequency alternating magnetic fields (AMF) and magnetic nanoparticles (MNPs) is an efficient way to induce biological responses through several approaches: magnetic hyperthermia, drug release, controls of gene expression and neurons, or activation of chemical reactions. So far, these experiments cannot be analyzed in real‐time during the AMF application. A miniaturized electromagnet fitting under a confocal microscope is built, which produces an AMF of frequency and amplitude similar to the ones used in magnetic hyperthermia. AMF application induces massive damages to tumoral cells having incorporated nanoparticles into their lysosomes without affecting the others. Using this setup, real‐time analyses of molecular events occurring during AMF application are performed. Lysosome membrane permeabilization and reactive oxygen species production are detected after only 30 min of AMF application, demonstrating they occur at an early stage in the cascade of events leading eventually to cell death. Additionally, lysosomes self‐assembling into needle‐shaped organization under the influence of AMF is observed in real‐time. This experimental approach will permit to get a deeper insight into the physical, molecular, and biological process occurring in several innovative techniques used in nanomedecine based on the combined use of MNPs and high‐frequency magnetic fields.     

Effect of Zirconium on the Structure and Congruent Crystallization of a Supercooled Calcium Aluminosilicate Melt

The influence of zirconium as a nucleating agent on the congruent crystallization and relevant physical properties of a supercooled calcium aluminosilicate melt of a composition close to CaAl₂SiO₆ has been investigated up to 6 mol% ZrO₂. Zirconium marginally affects rheological and structural properties, decreasing the viscosity of the Zr‐free melt by no more than 0.25 log unit and, as observed by Raman spectroscopy, not changing significantly the polymerization state of the material. Whereas the Zr‐free melt crystallizes congruently and heterogeneously from the sample surface to yield yoshiokaite, a stuffed derivative of the nepheline structure, addition of zirconia promotes instead bulk crystallization of tetragonal ZrO₂ and then of yoshiokaite. The latter process takes place in two stages: dissolved Zr first promotes homogeneous precipitation of zirconia before yoshiokaite crystallizes congruently from a Zr‐depleted volume of melt around zirconia precipitates. This process makes zirconium, and probably other poorly soluble oxides, valuable to control congruent crystallization in silicate glass‐ceramics. From the recorded thermograms, an enthalpy of crystallization of 40 and 46 kJ/mol has been determined at 1060 and 1140 K, respectively, for CaAl₂SiO₆ yoshiokaite, a very low value that is likely due to the extensive atomic disorder of crystals precipitating at high degrees of supercooling.