Fullerene: biomedical engineers get to revisit an old friend

1. Download high-res image (169KB)
2. Download full-size image

     

The occurrence of perchlorate during drinking water electrolysis using BDD anodes

Electrochemical studies were carried out to estimate the risks of perchlorate formation in drinking water disinfected by direct electrolysis. Boron Doped Diamond (BDD) anodes were used in laboratory and commercially available cells at 20 °C. The current density was changed between 50 and 500 A m⁻². For comparison, other anode materials such as platinum and mixed oxide were also tested. It was found that BDD anodes have a thousandfold higher perchlorate formation potential compared with the other electrode materials that were tested. In long-term discontinuous experiments all the chloride finally reacted to form perchlorate. The same result was obtained when probable oxychlorine intermediates (OCl⁻, ClO₂⁻, ClO₃⁻) were electrolysed in synthetic waters in the ppm range of concentrations. The tendency to form perchlorate was confirmed when the flow rate of drinking water was varied between 100 and 300 L h⁻¹ and the temperature increased to 30 °C. In a continuous flow mode of operation a higher chloride concentration in the water resulted in a lower perchlorate formation. This can be explained by reaction competition of species near and on the anode surface for experiments both with synthetic and local drinking waters. It is concluded that the use of electrodes producing highly reactive species must be more carefully controlled in hygienically and environmentally oriented applications.     

Artificial gravity loading increases the effects of the glutamate transporter inhibitors on the glutamate release and uptake in rat brain nerve terminals

The present study evaluated the effect of artificial gravity loading on transporter-mediated uptake and release of L-glutamate using the inhibitors of glutamate transporters as tools. The competitive nontransportable, DL-threo-beta-benzyloxyaspartate (DL-TBOA), and transportable, DL-threo-beta-hydroxyaspartate (DL-THA), inhibitors were demonstrated to better inhibit the L-[¹⁴C]glutamate uptake under centrifuge-induced hypergravity compared with the normal gravity control. The effect of DL-TBOA on depolarization-induced carrier-mediated L-[¹⁴C]glutamate release also increased after hypergravity loading in Na⁺- and low [Na⁺] NMDG- supplemented media. 10 µM DL-TBOA-induced decrease in L-[¹⁴C]glutamate release in Na⁺ — supplemented medium was 15.2±2.2 % in the control experiments and 26.2±3.9 % after centrifuge-induced loading (P≤0,05) and in low [Na⁺] medium was 37.0±2.5 % and 45.0±3.4 %, respectively.     

New proposal in the thermodynamic analysis of complex heat regeneration systems

This paper presents a new approach for analyzing and/or synthesizing the heat regeneration system, which has many applications in various energy conversion plants (ECP) and between ones. The method is applied for optimizing heat exchanger networks (HENs) operating below ambient temperature conditions as an application for refrigeration machines. Exergy and exergoeconomic methods are adapted for the optimization of three-flow heat exchangers. Few cases are illustrated and discussed. Also, the heuristic rules and design criteria for pinch analysis for an optimized HEN are presented.     

Droplet deformation and break-up under shear: Hydrocolloid solution vs. suspension of starch granules

Shear induced deformation and rupture of two types of droplets, hydroxypropyl methylcellulose (HPMC) aqueous solution and modified waxy maize suspension, were studied and compared using a counter-rotating rheo-optical set-up. The motivation of the work was to explain the difference observed in flavour perception of food products thickened by these two fluids. A droplet of either fluid was placed into silicon oil and deformation and break-up were monitored as a function of applied shear stress and strain. It was found that starch suspension droplets broke up at lower deformation stress and strain than HPMC solution droplets despite viscosity ratio and capillary number suggesting the opposite. It is hypothesised that the ease with which droplets thickened by starch break-up is responsible for their rapid mixing with saliva.     

Comparison of two techniques for reliable characterization of thin metal-dielectric films

In the present study we determine the optical parameters of thin metal-dielectric films using two different characterization techniques based on nonparametric and multiple oscillator models. We consider four series of thin metal-dielectric films produced under various deposition conditions with different optical properties. We compare characterization results obtained by nonparametric and multiple oscillator techniques and demonstrate that the results are consistent. The consistency of the results proves their reliability.     

Design, production, and reverse engineering of two-octave antireflection coatings

We deal with design and production of optimal two-component antireflection (AR) coatings for an ultra broadband spectral range from 450 nm to 1800 nm. We demonstrate the whole design-production chain including design selection, choosing monitoring technique, coating production, and reverse engineering of the deposited coatings. At each step of this chain we provide thorough analysis on the basis of theoretical results and adequate computational manufacturing experiments. In order to produce the designed AR coatings we use magnetron sputtering deposition technique and accurate time monitoring.     

Verification of Hypertorus Communication Grids by Infinite Petri Nets and Process Algebra

A model of a hypertorus communication grid has been constructed in the form of an infinite Petri net. A grid cell represents either a packet switching device or a bioplast cell. A parametric expression is obtained to allow a finite specification of an infinite Petri net. To prove properties of an ideal communication protocol, we derive an infinite Diophantine system of equations from it, which is subsequently solved. Then we present the programs htgen and ht-mcrl2-gen, developed in the C language, which generate Petri net and process algebra models of a hypertorus with a given number of dimensions and grid size. These are the inputs for the respective modeling tools Tina and mCRL2, which provide model visualization, step simulation, state space generation and reduction, and structural analysis techniques. Benchmarks to compare the two approaches are obtained. An ad-hoc induction-like technique on invariants, obtained for a series of generated models, allows the calculation of a solution of the Diophantine system in a parametric form. It is proven that the basic solutions of the infinite system have been found and that the infinite Petri net is bounded and conservative. Some remarks regarding liveness and liveness enforcing techniques are also presented.