Are Diamonds a MEMS' Best Friend?

Next-generation military and civilian communication systems will require technologies capable of handling data/ audio, and video simultaneously while supporting multiple RF systems operating in several different frequency bands from the MHz to the GHz range [1]. RF microelectromechani-cal/nanoelectromechanical (MEMS/NEMS) devices, such as resonators and switches, are attractive to industry as they offer a means by which performance can be greatly improved for wireless applications while at the same time potentially reducing overall size and weight as well as manufacturing costs.     

Benzotriazole as inhibitor for copper with and without corrosion products in aqueous polyethylene glycol

Electrochemical methods, including polarization experiments and impedance spectroscopy, were used to evaluate the effectiveness of benzotriazole (BTA) in an aqueous solution of polyethylene glycol (PEG) in protecting polished archaeological copper or archaeological copper covered with corrosion products. The adsorption of PEG on the polished copper significantly limited the corrosion current. The presence of benzotriazole enhanced the protection of the polished copper, giving maximum protection at a concentration of 10^–2moll^–1 of BTA in 20 vol% PEG 400 solution. On the other hand, PEG solutions caused degradation of the corrosion products of the copper. This degradation increased with time. When BTA was added, the corrosion products were preserved and, the higher the BTA concentration, the more the corrosion current decreased. In PEG 400 solution protection of the corrosion products of the copper by BTA improved over time.     

Near fields of microstrip antennas

The paper presents an iterative method for the computation of the near fields of single layer microstrip patch antennas. A judicious combination of the advantages of the MPIE (mixed potential integral equation) method, the FFT algorithm and the biconjugate gradient leads to an efficient numerical solution. The scheme can deal with patches of arbitrary shapes and is capable of dealing with a very large number of unknowns. Near field computation is done in a straightforward manner by computing the weighted near fields. For illustration, three patches belonging to the family of generalized annular sector have been chosen. Computed results of input impedances with a coaxial probe excitation have been compared with measurements. Computed near field amplitudes have also been compared with measured results where possible. Computed far field characteristics have been correlated with the near field information     

Dielectric measurements of tropical wood

The aim of this paper is to determine the dielectric characteristics of tropical wood species at microwaves frequency in order to use them as planar antenna substrate. The measurements have been done on dried wood in the frequency range 8.2–12.4 GHz. The suitability of wood as a microwave printed antenna substrate will be determined by the values taken by the complex parameters “permittivity” ε$\epsilon$ and “permeability” μ$\mu$ and the loss tangent tanδ$\tan \delta$. The measurement methods were based on the waveguide method and the open resonator technique. The first method gave us the reference values while the second one confirmed the previous measurements. Values obtained in the three principal axis of each species confirm the anisotropic nature of wood. These measurements will also confirm that the losses which are the main criteria of selecting wood as substrate grow with the density of the wood.     

Near-field diagnostics of small printed antennas using theequivalent magnetic current approach

A near-field to far-field transformation based on the antenna representation by equivalent magnetic current (EMC) sources has been proposed and validated experimentally on large high-directivity antenna arrays. In this paper, the use of EMC is extended to the diagnostics of low-directivity printed antennas. The limitation of the near-field to far-field transformation applied to EMC models of low-directivity antennas, caused by the finite dimensions of the antenna ground plane, is demonstrated. A method to partially overcome this limitation by including the contribution of diffracted rays is implemented, and its effectiveness is demonstrated with antenna prototypes. It is shown that the agreement between the far-field patterns measured in an anechoic chamber and the patterns computed from the EMC model obtained from the near-field measurements is significantly improved upon, within a sector of ±90° with respect to the antenna boresight in the E plane. The influence of the near-field sampling density and topology of the EMC model on the accuracy of the predicted far-field pattern is examined     

Aerosol-mediated delivery of recombinant adenovirus to the airways of nonhuman primates

At present, it is conceivable that gene therapy of the cystic fibrosis airway epithelium is possible using the direct transfer of a functional human cystic fibrosis transmembrane conductance regulator (CFTR) gene to a wide variety of patients' tracheo-bronchial cells. Here we describe a novel approach (aerosolization) to deliver a replication-deficient adenovirus carrying the CFTR gene (Ad.CFTR) to the airways. Results obtained in vitro and in Rhesus monkeys suggest that the delivery of recombinant adenovirus as an aerosol is feasible and is not associated with severe toxicity after single or double administration depending on the Ad.CFTR dose. This study supports the concept of aerosolization as a delivery method for adenovirus-mediated lung gene therapy.     

Separation of the reservoir and wave pressure and velocity from measurements at an arbitrary location in arteries

Previous studies based on measurements made in the ascending aorta have demonstrated that it can be useful to separate the arterial pressure P into a reservoir pressure P* generated by the windkessel effect and a wave pressure p generated by the arterial waves: P = P*+p. The separation in these studies was relatively straightforward since the flow into the arterial system was measured. In this study the idea is extended to measurements of pressure and velocity at sites distal to the aortic root where flow into the arterial system is not known. P* is calculated from P at an arbitrary location in a large artery by fitting the pressure fall-off in diastole to an exponential function and assuming that p is proportional to the flow into the arterial system. A local reservoir velocity U* that is proportional to P* is also defined. The separation algorithm is applied to in vivo human and canine data and to numerical data generated using a one-dimensional model of pulse wave propagation in the larger conduit arteries. The results show that the proposed algorithm is reasonably robust, allowing for the separation of the measured pressure and velocity into reservoir and wave pressures and velocities. Application to data measured simultaneously in the aorta of the dog shows that the reservoir pressure is fairly uniform along the aorta, a test of self-consistency of the assumptions leading to the algorithm. Application to data generated with a validated numerical model indicates that the parameters derived by fitting the pressure data are close to the known values which were used to generate the numerical data. Finally, application to data measured in the human thoracic aorta indicates the potential usefulness of the separation.