Verbesserung der Backeigens?haften von Weizenmehlen durch die Typ II-Lipoxygenase aus Sojabohnen

Zusammenfassung Die Verbesserung von Weizenmehlen mit normalen und schlechten Backeigenschaften (Problemweizen) durch Zugabe von Sojabohnenextrakten oder gereinigter Typ II Lipoxygenase (EC 1.13.11.12) wurde durch Messung der Teig-Rheologiei im kleinen Maßstab und durch Mikrobackversuche bestimmt. Die Anwesenheit der Lipoxygenase in Teig erhöhte die Knettoleranz, steigerte die Teigstabilität und das Brotvolumen. Diese positive Wirkung auf die Backeigenschaften zeigten auch Mehle aus Problemweizen; die Handhabung der Teige verbesserte sich erheblich. Zugabe von Linolsäure zu Teigen mit Lipoxygenase führte zu einer weiteren Zunahme der Teigfestigkeit. Die Mehlverbesserung durch Sojaextrakte war geringer als nach Zugabe des gereinigten Enzyms.[/p]

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Improvement of Dough and Baking Properties of Wheat Flour by Type II Lipoxygenase from Soybeans

Summary The improver action of both soybean flour extracts and purified type II Lipoxygenase (EC 1.13.11,12) on wheat flours of normal and poor baking qualities was studied by micro scale measurements of dough rheology and by micro scale baking tests. Presence of lipoxygenase in the dough extended the mixing tolerance, increased dough stability and enhanced the loaf volume of the bread. This significant improver effect was also observed with flours of poor quality which in addition showed better handling characteristics. Addition of linoleic acid to doughs with lipoxygenase resulted in a further increase of dough strength. The improver effect of soybean extracts was smaller than that of the purified enzyme.

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Die Arbeit wurde von der AIF finanziell unterstützt     

Utilisation of time-variant influence functions in the computer controlled polishing

In the computer controlled polishing, a polishing tool moves in a well-defined manner across the workpiece surface in order to individually remove the surface error-profile. The commonly used technique to calculate the moving of the polishing tool is the dwell time method. Based on a constant (time-invariant) removal characteristic of the polishing tool (influence function) the amount of material to be removed is controlled via the dwell time. The longer the polishing tool is in contact with a particular area of the workpiece, the more material is removed at this position.Mathematical basics to calculate dwell time-profiles are shown, and a new approach considering time-variant influence functions for the computer controlled polishing is introduced. The results point out that time-variant influence functions may contribute to further decrease the process time, and thus to make a computer controlled polishing process more efficient. The reduction of the process time was observed to approximately 35% using a combination of the dwell time method with time-variant influence functions.     

A polylinker approach to reductive loop swaps in modular polyketide synthases

Multiple versions of the DEBS 1-TE gene, which encodes a truncated bimodular polyketide synthase (PKS) derived from the erythromycin-producing PKS, were created by replacing the DNA encoding the ketoreductase (KR) domain in the second extension module by either of two synthetic oligonucleotide linkers. This made available a total of nine unique restriction sites for engineering. The DNA for donor "reductive loops," which are sets of contiguous domains comprising either KR or KR and dehydratase (DH), or KR, DH and enoylreductase (ER) domains, was cloned from selected modules of five natural PKS multienzymes and spliced into module 2 of DEBS 1-TE using alternative polylinker sites. The resulting hybrid PKSs were tested for triketide production in vivo. Most of the hybrid multienzymes were active, vindicating the treatment of the reductive loop as a single structural unit, but yields were dependent on the restriction sites used. Further, different donor reductive loops worked optimally with different splice sites. For those reductive loops comprising DH, ER and KR domains, premature TE-catalysed release of partially reduced intermediates was sometimes seen, which provided further insight into the overall stereochemistry of reduction in those modules. Analysis of loops containing KR only, which should generate stereocentres at both C-2 and C-3, revealed that the 3-hydroxy configuration (but not the 2-methyl configuration) could be altered by appropriate choice of a donor loop. The successful swapping of reductive loops provides an interesting parallel to a recently suggested pathway for the natural evolution of modular PKSs by recombination.     

Optical investigation of quantum confinement in PbSe nanocrystals at different points in the Brillouin zone

We present detailed investigations on the optical properties of PbSe nanocrystals. The absorption spectra of monodisperse, quasispherical nanocrystals exhibit sharp features as a result of distinct optical transitions. To study the size dependence, absorption spectra of nanocrystals ranging from 3.4 to 10.9 nm in diameter are analysed and a total of 11 distinct optical transitions are identified. The assignment of the various optical transitions is discussed and compared to theoretically calculated transition energies. By plotting all transitions as a function of nanocrystal size (D) we find that the energy (E) changes with the following relationship [Formula: see text] for the lowest energy transitions. The transition energy extrapolates to approximately 0.3 eV for infinite crystal size, in agreement with the bandgap of bulk PbSe at the L-point in the Brillouin zone. In addition, high-energy transitions are observed, which extrapolate to 1.6 eV for infinite crystal size, which is in good agreement with the bulk bandgap of PbSe at the Sigma-point in the Brillouin zone. Tight-binding calculations confirm that the high-energy transitions originate from the Sigma-point in the Brillouin zone. The Sigma-character of the high-energy transitions may be of importance to explain the mechanism behind multiple exciton generation in PbSe nanocrystals.     

Detection of high-temperature water vapor at 940 nm with vertical-cavity surface-emitting lasers

A vertical-cavity surface-emitting laser was used to study the absorption of water vapor in the 940 nm region. Measurements for several absorption lines within the 2 v1 + V3 vibrational band were performed. Line strengths at room temperature and in a heated absorption cell over the temperature range of 420-970 K were obtained. The line strength values were in good agreement with simulations based on the values of the HITRAN 2004 database. The measurements also showed that water vapor transitions near 940 nm are suitable for sensitive temperature determination.     

A Model–View–Controller extension for pervasive multi-client user interfaces

This paper addresses the implementation of pervasive Java Web applications using a development approach that is based on the Model–View–Controller (MVC) design pattern. We combine the MVC methodology with a hierarchical task-based state transition model in order to achieve the distinction between the task state and the view state of an application. More precisely, we propose to add a device-independent TaskStateBean and a device-specific ViewStateBean for each task state as an extension to the J2EE Service to Worker design pattern. Furthermore, we suggest representing the task state and view state transition models as finite state automata in two sets of XML files. This paper shows that the distinction between an applications task state and view state is both intuitive and facilitates several, otherwise complex, tasks, such as changing devices on the fly.