Stevia rebaudiana Bertoni – Überblick über die Forschung an einer verbotenen Pflanze und derer möglichen Einsätze

Stevia rebaudiana stammt aus dem Grenzgebiet zwischen Paraguay und Brasilien. Die F?higkeit dieser Pflanze, kalorienarme sü?schmeckende Glycoside in ihren Bl?ttern zu akkumulieren, macht sie für verschiedene Anwendungen in Form eines Zuckerersatzproduktes interessant. Obwohl die Pflanze und auch die Extrakte daraus seit Jahrhunderten von der einheimischen Bev?lkerung Lateinamerikas genutzt werden, sind S. rebaudiana und diese Extrakte (Stevioside) in der EU als Lebensmittelzusatz nicht zugelassen. Ein wichtiger Aspekt ist in diesem Zusammenhang die Gew?hrleistung einer bestimmten stofflichen Zusammensetzung dieses Naturproduktes. Um externe Faktoren, die suboptimales Wachstum von S. rebaudiana bewirken und ihren endogenen Stoffwechsel beeinflussen, ausschlie?en zu k?nnen, bietet sich die Sprosskultur im Bioreaktor an, zu der in diesem Beitrag n?here Erl?uterungen gegeben werden. Die Stevioside haben durch gute Wasserl?slichkeit und Kompatibilit?t mit verschiedenen organischen S?uren von Obst und Gemüse das Potenzial u. a. im Konditorei-Gewerbe und beim Herstellen von Getr?nken eingesetzt zu werden. Vor dem Einsatz sind aber toxikologische Fragen hinreichend zu prüfen.     

Embedding of Dedicated High-Performance ASICs into Reconfigurable Systems Providing Additional Multimedia Functionality

The computational power required in many multimedia applications is well beyond the capabilities of today's multimedia systems. Therefore, the embedding of additional high-performance accelerator multimedia components into these systems is most decisive. This paper presents the embedding of multimedia components into computer systems using reconfigurable coprocessor boards. The goal of those reconfigurable platforms which can be adapted to several applications and which include programmable digital signal processors, control and memory devices as well as dedicated multimedia ASICs is worked out. On the way to such a platform four ASICs for image and text processing are presented. The embedding of these components into a computing system using a CardBus-based coprocessor board is shown. Such a reconfigurable coprocessor board is an important intermediate stage on the way to future hybrid reconfigurable systems on chip.     

Photoinduced switching of the current through a single molecule: effects of surface plasmon excitations of the leads

The photoinduced switch of the current through a single molecule is studied theoretically by including plasmon excitations of the leads. A molecule weakly linked to two spherical nanoelectrodes is considered resulting in sequential charge transmission scheme. Taking the molecular charging energy (relative to the equilibrium lead chemical potential) to be comparable to the molecular excitation energy, an efficient current switch in a low voltage range becomes possible. A remarkable enhancement of the current is achieved due to simultaneous plasmon excitations in the electrodes. The behavior is explained by an increased molecular absorbance due to oscillator strength transfer from the electrode plasmon excitations and by a net excitation energy motion from the electrodes to the molecule.     

Hotspot propagation in superconductive strip detectors

Hotspots formed in superconductive strips due to interaction with particles are considered. The superconductive strip detector is considered in terms of a model of one-dimensional superconductor. D.C. electric current flowing through a film leads to Joule heating of the normal phase and causes either expansion or collapse of the hotspot. It is shown that the energy of a particle can be obtained by measuring the length of the expanding hotspot.     

Internet-enabled modelling of extended manufacturing enterprises using process-based techniques

This article presents the preliminary results of an ongoing research project on Internet-enabled process-based modelling of extended manufacturing enterprises. We propose applying the open system architecture for CIM (CIMOSA) modelling framework alongside object-oriented Petri net models of enterprise processes and object-oriented techniques for extended enterprises modelling. We describe the main features of the proposed approach and discuss some components. We present elementary examples of object-oriented Petri net implementation and real-time visualisation.     

Eigenmoden und Eigenwerte komplementärer sektorförmiger Strukturen: Eine sphärische Multipolanalyse des elektromagnetischen Randwertproblems

Übersicht Mit Hilfe der sphärischen Multipolanalyse werden in dieser Arbeit die E-Moden und die H-Moden sektorförmiger Strukturen bestimmt. Die Lösung des Randwertproblems wird auf die Lösung eines zweiparametrigen Eigenwertproblems mit zwei gekoppelten Laméschen Differentialgleichungen zurückgeführt. Wir leiten eine bemerkenswerte Relation zwischen den Eigenwerten der Eigenmoden komplementärer sektorförmiger Strukturen ab und stellen numerische Ergebnisse vor. Abschließend untersuchen wir die Zusammenhänge zwischen den Eigenmoden komplementärer Strukturen mittels der Babinetschen Transformation.

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Eigenmodes and eigenvalues of complementary sectorstructures: A spherical multipole analysis of the electromagnetic boundary value problem

Contents In this paper the E-modes and H-modes of sectorstructures are determined using multipole expansion. The solution of the boundary value problem is reduced to a two-parametric eigenvalue problem with two coupled Lamé equations. We deduce a remarkable relation between the eigenvalues belonging to the eigenmodes of complementary sector-structures and we present numerical data. Finally, we show the relations between the eigenmodes of complementary structures with the help of Babinet's transformation.

     

Effect of high-temperature processing on the creation of boron-related deep levels in 4H-SiC

High-temperature processing was applied to SiC boron-doped epitaxial layers, epitaxial layers grown on boron-rich substrates, and boron-implanted samples in order to establish conditions favorable for the formation of boron-related centers (D-centers) that introduce a deep level in SiC bandgap. Photoluminescence (PL) was used to detect and compare the formation of the D-center after different processing steps. It was confirmed that the presence of lattice defects was required for achieving significant boron diffusion and D-center formation. In addition, epitaxial growth on the top of a boron-implanted sample yielded efficient boron in-diffusion in the growing layer, which resulted in a material compensated with D-centers. The temperature dependence of the D-center formation efficiency was investigated.     

Molecular beam epitaxy of InGaN thin films on Si(111): Effect of substrate nitridation

The effect of silicon nitridation on structural quality, indium incorporation, and electrical properties of the InGaN/Si heterojunctions is investigated. A series of In_xGa_1 − xN (x = 0-0.32) thin films are grown directly on Si(111) substrates, with and without a Si_xN_y surface layer, by plasma-assisted molecular beam epitaxy. The crystalline quality is higher and the indium incorporation is increased when the In_xGa_1 − xN thin films are grown with the intentional Si_xN_y buffer. These observations are explained by the reduced local elastic stress at the interface and N-polarity of the surface, both of which promote the incorporation of In. The obtained n-In_xGa_1 − xN/p-Si (x = 0.2-0.3) heterojunctions exhibit a nearly ohmic behavior, and the series resistance is higher for the Si_xN_y-containing junctions. Our results suggest that unlike the amorphous Si_xN_y region spontaneously formed during direct deposition of III-nitrides on Si, the Si_xN_y layer obtained by high-temperature annealing of Si(111) in nitrogen atmosphere is beneficial to the In_xGa_1 − xN deposition.