Curing simulation by autoclave resin infusion

This paper deals with the modelling and simulation of resin flow, heat transfer and the curing of a multilayer thermoset composite by the resin film infusion process. For approximately isothermal flows, the model is based on Darcy's Law and Stoke's equations where a similarity solution is obtained and subsequently used in a two-dimensional convection-diffusion heat equation coupled with a rate of cure equation. A finite difference scheme is applied to the energy equation on a moving grid and simulations for varying laminate thicknesses and number of plies are performed.     

Multi-wafer growth of highly uniform InGaP/GaAs by low pressure MOVPE

This paper reports on the large area growth of InGaP/GaAs heterostructures for short wavelength applications (λ ∼ 650 nm) by low pressure MOVPE in a vertical, high speed, rotating disk reactor. Highly uniform films were obtained both on a single 50 mm diam wafer at the center of a 5 inch diam wafer platter and on three, 50 mm diameter GaAs wafers symmetrically placed on a 5 inch diam platter. Characterization was performed by x-ray diffraction, SEM, and room temperature photoluminescence (PL) mapping. For the single wafer growth, PL mapping results show that the total range on wavelength was ±2 nm with a 2 mm edge exclusion. The standard deviation of the peak wavelength,σ _w , is 0.7 nm. Thickness uniformity, measured by SEM, is less than 2%. Similar results were obtained for the multi-wafer runs. Each individual wafer has aσ _w of 1.1 nm. The wafers have nearly identical PL maps with the variation of the average wavelength from the three wafers within ±0.1 nm.     

Analyse de composants plan-E symétriques en guides d’onde àsection rectangulaire

A differential method is presented for the efficient calculation of the modal scattering matrix of E- plane junctions in rectangular waveguides. This formalism is based on the Maxwell’s equations written in a non- orthogonal coordinates system. In a first approach, it requires 2N numerical integrations in order to obtain a (2N X 2N)- dimensional scattering matrix. We prove that the number of integrations can be divided by half. Moreover, the differential operator contains the structure geometry. Electromagnetic effects of symmetries can be easily deduced and the system size reduced and a saving in computation time obtained.     

TIOx/Al2O3 Multilayer Ceramic Thin Films

Titanium oxide/aluminum oxide films have been deposited using molecular beam epitaxy methods and characterized by reflection high-energy electron diffraction and transmission electron microscopy techniques. Growth on silicon substrates below 973 K resulted in primarily amorphous multilayers. At 1323 K, the deposition of titanium in an oxygen atmosphere on (0001) Al₂O₃ substrates resulted in films of Ti₂O₃. These films consisted of small domains, up to 60 nm, slightly misoriented from a [1120] ∥ [1120] orientation relationship. Two variants of Ti₂O₃ were observed due to multiple positioning during growth. Closing the titanium shutter during growth resulted in an oriented TiO₂ film.     

Catalytic effects of alkaline earth carbonates in the carbon-carbon dioxide reaction

The results of a thermogravimetric study of the catalytic effects of alkaline earth carbonates in the CCO₂ reaction are described. Using graphite powder as the carbonaceous phase the rates of the reaction between 700 and 1100 °C were found to be substantially increased on addition of small amounts of BaCO₃ and SrCO₃ to the graphite. CaCO₃ was a much less active catalyst whereas MgCO₃ had only a slight effect on the kinetics. The catalytic process is interpreted in terms of a solid-state reaction between the salt and the graphite to yield the metal oxide which subsequently regenerates carbonate by reaction with gaseous CO₂.     

Deficits in habituation of cardiac arousal responses incurred by telencephalic ablation in goldfish, Carassius auratus, and their relation to other telencephalic functions

The effects of telencephalic ablation on the habituation of cardiac arousal responses in goldfish was studied. The ablation was performed either by ligating the telencephalon of habituated fish between stimulus presentations or by aspiration prior to habituation. The former technique caused dishabituation; the latter, a slower rate of habituation than that of sham-operated controls. The habituation deficit incurred by surgical ablation was found to decline with time, being small after 2 wk. The results are discussed in relation to other telencephalic involvements in behavior and to the plasticity of other parts of the brain which enables them to assume telencephalic functions.     

A Facile Method for Reversibly Linking a Recombinant Protein to DNA

A simple modification allows DNA to be linked to recombinant proteins. DNA functionalized with three nitrilotriacetic acid groups forms coordination complexes with nickel ions and the His₆‐tag of the recombinant protein (here, GFP). This noncovalent linkage is reversible, site‐specific and has a high (nanomolar) affinity.

     

ECM-Based Materials in Cardiovascular Applications: Inherent Healing Potential and Augmentation of Native Regenerative Processes

The in vivo healing process of vascular grafts involves the interaction of many contributing factors. The ability of vascular grafts to provide an environment which allows successful accomplishment of this process is extremely difficult. Poor endothelisation, inflammation, infection, occlusion, thrombosis, hyperplasia and pseudoaneurysms are common issues with synthetic grafts in vivo. Advanced materials composed of decellularised extracellular matrices (ECM) have been shown to promote the healing process via modulation of the host immune response, resistance to bacterial infections, allowing re-innervation and reestablishing homeostasis in the healing region. The physiological balance within the newly developed vascular tissue is maintained via the recreation of correct biorheology and mechanotransduction factors including host immune response, infection control, homing and the attraction of progenitor cells and infiltration by host tissue. Here, we review the progress in this tissue engineering approach, the enhancement potential of ECM materials and future prospects to reach the clinical environment.     

Nanomagnetism reveals the intracellular clustering of iron oxide nanoparticles in the organism

There are very few methods to investigate how nanoparticles (NPs) are taken up and processed by cells in the organism in the short and long terms. We propose a nanomagnetism approach, in combination with electron microscopy, to document the magnetic outcome of iron oxide-based P904 NPs injected intravenously into mice. The NP superparamagnetic properties are shown to be modified by cell internalization, due to magnetic interactions between NPs sequestered within intracellular organelles. These modifications of magnetic behaviour are observed in vivo after NP uptake by resident macrophages in spleen and liver or by inflammatory macrophages in adipose tissue as well as in vitro in monocyte-derived macrophages. The dynamical magnetic response of cell-internalized NPs is theoretically and experimentally evidenced as a global signature of their local organization in the intracellular compartments. The clustering of NPs and their magnetism become dependent on the targeted organ, on the dose administrated and on the time elapsed since their injection. Nanomagnetism probes the intracellular clustering of iron-oxide NPs and sheds light on the impact of cellular metabolism on their magnetic responsivity.