Aeroelastic tailoring using lamination parameters

The aim of the present work is to passively reduce the induced drag of the rear wing of a Formula One car at high velocity through aeroelastic tailoring. The angle-of-attack of the rear wing is fixed and is determined by the required downforce needed to get around a turn. As a result, at higher velocity, the amount of downforce and related induced drag increases. The maximum speed on a straight part is thus reduced due to the increase in induced drag. A fibre reinforced composite torsion box with extension-shear coupled upper and lower skins is used leading to bending-torsion coupling. Three-dimensional static aeroelastic analysis is performed loosely coupling the Finite Element code Nastran and the Computational Fluid Dynamics panel code VSAERO using ModelCenter. A wing representative of Formula One rear wings is optimised for minimum induced drag using a response surface methodology. Results indicate that a substantial induced drag reduction is achievable while maintaining the desired downforce during low speed turns.     

Providing the stability of the coefficient of friction of a vehicle disk brake under extreme operating conditions

The authors propose a method of providing stability of the coefficient of friction of a disk brake. The method is based on the use of combination of friction materials in the force pattern of working elements of a disk brake. These friction materials interact with a brake disk and have individual level of loading. The article theoretically substantiates the possibility of the impact of the integral properties of a combination of friction materials involved in the force interaction on vehicle braking parameters. The reasonability of the proposed method is proved by the results of the experimental research. A brake-pad (lining) design has been developed to implement this method.     

Transfer of low nanoliter volumes between microplates using focused acoustics—automation considerations

Acoustic droplet ejection (ADE) gently and precisely aliquots nanoliter and picoliter liquid volumes without any physical contact with the solution being transferred. The technology is very automation-friendly, as it is compatible with conventional microplates. Focused energy from an acoustic transducer induces droplet ejection into an inverted standard microplate. The commercial system transfers low-nanoliter volumes of dimethyl sulfoxide–dissolved compound libraries and thereby enables cell-based assays to be performed in 1536-well plates.     

Synthesis, characterization and aggregation behavior of block copolymers containing a polyisocyanopeptide segment

Following up on previous preliminary communications the synthesis of a series of block copolymers by applying amine end-capped polymers as initiators for the nickel(II) catalyzed polymerization of isocyanides is reported. Using a polystyrene derivative as the initiator, superamphiphiles containing a hydrophobic polystyrene tail and a charged helical polyisocyanide headgroup were prepared. Under proper conditions these superamphiphiles self-assembled in water to give a variety of aggregate morphologies, among which are superhelical architectures. Initiators derived from carbosilane dendritic wedges gave block copolymers with a unique combination of structural elements, i.e. a flexible dendritic block and a rigid polyisocyanide block. Block copolymers derived from the 3rd generation dendrimers form well-defined micellar aggregates in the presence of Ag⁺ ions. These aggregates have been used to construct nanoarrays of metallic silver.     

Templated self-assembly of porphyrin cages

The development of self-assembling catalysts, although an often-tried approach, has achieved little success so far. Toward the construction of substrate selective catalysts, we have self-assembled a porphyrin cage based upon the recognition of the templates meso-dipyridyl ( DPyP ) or meso-tetrapyridyl porphyrin ( TPyP ) by glycoluril-based receptors that are functionalized with two pendant zinc porphyrins.     

Mercury exposure and risks from dental amalgam in the US population, post-2000

Dental amalgam is 50% metallic mercury (Hg) by weight and Hg vapour continuously evolves from in-place dental amalgam, causing increased Hg content with increasing amalgam load in urine, faeces, exhaled breath, saliva, blood, and various organs and tissues including the kidney, pituitary gland, liver, and brain. The Hg content also increases with maternal amalgam load in amniotic fluid, placenta, cord blood, meconium, various foetal tissues including liver, kidney and brain, in colostrum and breast milk.Based on 2001 to 2004 population statistics, 181.1 million Americans carry a grand total of 1.46 billion restored teeth. Children as young as 26 months were recorded as having restored teeth. Past dental practice and recently available data indicate that the majority of these restorations are composed of dental amalgam.Employing recent US population-based statistics on body weight and the frequency of dentally restored tooth surfaces, and recent research on the incremental increase in urinary Hg concentration per amalgam-filled tooth surface, estimates of Hg exposure from amalgam fillings were determined for 5 age groups of the US population.Three specific exposure scenarios were considered, each scenario incrementally reducing the number of tooth surfaces assumed to be restored with amalgam. Based on the least conservative of the scenarios evaluated, it was estimated that some 67.2 million Americans would exceed the Hg dose associated with the reference exposure level (REL) of 0.3 μg/m³ established by the US Environmental Protection Agency; and 122.3 million Americans would exceed the dose associated with the REL of 0.03 μg/m³ established by the California Environmental Protection Agency.Exposure estimates are consistent with previous estimates presented by Health Canada in 1995, and amount to 0.2 to 0.4 μg/day per amalgam-filled tooth surface, or 0.5 to 1 μg/day/amalgam-filled tooth, depending on age and other factors.     

Stark cell noise reduction of a CO2laser beam

A technique is demonstrated for reducing the rapid intensity fluctuations in the beam of a single frequency, polarized CO2laser tuned to theP(20)transition at 10.6 μm. The method uses a Stark-tunable absorption line in NH2D to compensate for the fluctuations of the laser output. Substantial reductions in laser beam intensity noise have been obtained. The method may be applied to other lines of the CO2laser and indeed to other types of lasers.     

Two-photon lifetime imaging of fluorescent probes in intact blood vessels: a window to sub-cellular structural information and binding status

Fluorescence lifetime imaging (FLIM) provides a complementary contrast mechanism to fluorescence intensity and ratio imaging in intact tissue. With FLIM the time-resolved decay in fluorescence intensity of (interacting) fluorophores can be quantified by means of time correlated single photon counting (TCSPC). Here we focus on fluorescence lifetime imaging in intact blood vessels. Requisites for imaging in intact tissue are good penetration depth and limited tissue damage. Therefore, in this pilot-study, we performed TCSPC-FLIM using two-photon laser scanning microscopy to determine, with sub-cellular resolution, the fluorescence lifetime of two fluorescent probes. First, we focused on the nucleic acid dye SYTO41 in the various compartments of cells in vitro and in situ in the wall of intact mouse carotid arteries. Second, it was assessed whether the interaction of the lectin WGA-FITC with the endothelial glycocalyx affects its fluorescence lifetime. Results showed comparable mono-exponential fluorescence lifetimes of SYTO41 in the nuclei of cells in vitro and in situ. The slightly shorter fluorescence lifetime observed in the cytoplasm allowed discrimination of the nuclei. SYTO41 displayed strong mitochondrial staining, as was verified by the mitochondrion-specific probe CMXRos. In addition, mitochondrial staining by SYTO41 was accompanied by a green shift in emission. In the mitochondrial region, SYTO41 showed a highly bi-exponential and relatively fast decay, with two distinct lifetime components. It is hypothesized that the fitted bi-exponential decay can either be contributed to (1) the mathematical approximation of the fluorescence intensity decay or (2) the presence of free and DNA-bound SYTO41 in the mitochondrial compartment, leading to two lifetime components. The fluorescence lifetime of WGA-FITC decreased by approximately 25% upon binding to the endothelial glycocalyx. From this study, we conclude that FLIM offers an additional contrast mechanism in imaging intact tissue and provides information on binding status between a probe and its ligand.