Identification of barramundi (Lates calcarifer) and tilapia (Oreochromis spp.) fillets by DNA- and protein-analytical methods

Fish and fillet of barramundi (Lates calcarifer) and tilapia (Oreochromis species) obtained from wholesale and retail trade were assigned to species by sequencing of PCR products. Two segments (358 and 464?bp) of the cytochrome b gene (cytb) were amplified using universal primers. The amplicons gave characteristic patterns in SSCP-analysis (single strand conformation polymorphism) suitable for differentiation of Lates calcarifer from Lates niloticus and Lateolabrax japonicus. Intra-specific variation of sequences and SSCP patterns were observed for barramundi. In case of tilapia species, it was found to be difficult to identify samples by BLAST due to the high similarity of cytb sequences of O. niloticus, O. mossambicus, O. aureus and Sarotherodon galileus. Four different patterns of single strand DNA (ssDNA) were obtained by SSCP analysis of the 464?bp amplicon of tilapia. Different patterns of ssDNA matched to variations in sequences. Protein profiles obtained by IEF (isoelectric focusing) of water-soluble proteins from raw fillet were found to be suitable for rapid differentiation of Lates calcarifer from Lateolabrax japonicus, but the three different Oreochromis species expressed only minor differences in protein patterns. The patterns of the tilapia and barramundi species showed a number of acidic, heat-stable proteins, presumably representing parvalbumin.     

Zur numerischen Pumpversuchsauswertung in Mehrschichtgrundwasserleitern

The analysis of well tests conducted in complex geological units is often not well suited with classical analytical approaches. Numerical simulators are usually needed to account for unconventional test conditions in order to analyze data which do not fit within analytical theory. In the current work, a numerical method for simulating pumping tests is adopted, which was developed about 30 years ago in the UK. The method is expanded within the present work to allow for a consistent analysis of pumping tests, vertical interference tests, pressure pulse tests, drillstem tests, and slug tests. Two-layer formations and their dual permeability equivalents can be treated by the implemented model including nonlinear well entrance losses. The application of the model is demonstrated for a pumping test conducted in the Oligocene base formation at the Teltow-Plateau south of Berlin. The test aimed at investigating potential leakages between this poor water quality base formation and overlying high water quality aquifers envisioned for future drinking water exploitation.     

Surge arresters for insulation coordination in UHV power systems—related problems and solutions

Surge arresters play an important role in the insulation coordination of ultra high-voltage (UHV) electric power systems. In this contribution the requirements on the surge arresters are discussed in comparison with those in conventional applications, and how surge arrester standards are being changed to cover these special requirements.     

Berechnung der Anlaufdaten von Asynchron-Käfigläufermotoren verschiedener Stabformen mit der Methode der finiten Differenzen

Übersicht Die spannungsabhängigen Anlaufströme und Drehmomente eines 2800 kW Asynchron-Käfigläufermotors werden mit der Methode der finiten Differenzen und einem neuen Block-SOR-Iterationsverfahren berechnet. Es wird ber die Ergebnisse für Rechteck-, Trapez- und andere Rotorstabformen berichtet. Die numerisch berechneten Daten werden mit den nach konventionellen Regeln ermittelten Zahlen verglichen. Der Sättigungseffekt ist unerwartet groß, als Folge des großen Nennstrombelages. Die ungesättigten werte stimmen sehr gut überein.

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On the calculation of the starting data of A.C. squirrel-cage motors with different bar shapes by the method of finite differences

Contents The voltage dependent starting currents and torques of a 2,800 kW 3-phase a.c. squirrel cage motor are calculated by the method of finite differences using a new block-SOR iteration technique. The paper describes the results for different rotor bars with rectangular, trapezoidal and other shapes. The calculated data are compared with conventionally determined figures. The saturation effect is rather large due to the high values of the rated current loading per air gap periphery. The unsaturated values agree very good.

     

Managing fddi networks: The state of the standards

The third in a serieson the FDDI standard, this article looksatSMT–the Fibre Distributed Data Interface Station Management–and the directions for FDDI over copper cables.     

Kraftwerkseigenschaften von Windenergieanlagen hinsichtlich Kurzschlussverhalten, Engpass- und Blindleistungsmanagement sowie Spannungsregelung

The increasing number of wind turbines will lead to new demands for transmission and distribution system control in the years to come. In order to ensure a smooth integration of wind energy into an electrical energy system structure, wind farms will have to possess power plant properties and be able to provide ancillary services. The ENERCON concept offers solutions not only for critical situations, such as short-circuits and bottlenecks in the grid, but also for normal operation, such as reactive power management or voltage control. Wind farms will essentially function in a manner similar to conventional power plants and moreover offer additional advantages in the distribution grid.