NAFLA – Ein Simulationswerkzeug zur analytischen Abschätzung von Schadstofffahnenlängen

Groundwater pollution with organic contaminants remains a world-wide problem. Before selection of any remediation technique, it is important to pre-assess contaminated sites with respect to their hazard. For this, several analytical and numerical approaches have been used and an initial assessment of contaminated sites the MS-Excel^© tool “NAFLA” was developed. “NAFLA” allows a quick and straightforward calculation and comparison of some analytical approaches for the estimation of maximum plume length under steady-state conditions. These approaches differ from each other in source geometry, model domain orientation, and in the consideration of (bio)chemical reaction within the domain. In this communication, we provide details about the development of “NAFLA”, its possible usage and information for users. The tool is especially designed for application in student education, by authorities and consultants.     

Biosynthesis of novel thermoplastic polythioesters by engineered Escherichia coli

The development of non-petrochemical sources for the plastics industry continues to progress as large multinationals focus on renewable resources to replace fossil carbon. Many bacteria are known to accumulate polyoxoesters as water-insoluble granules in the cytoplasm. The thermoplastic and/or elastomeric behaviour of these biodegradable polymers holds promise for the development of various technological applications. Here, we report the synthesis and characterization of microbial polythioesters (PTEs), a novel class of biopolymers of general technological relevance. Biosynthesis of PTE homopolymers was achieved using a recombinant strain of Escherichia coli that expressed a non-natural pathway consisting of a butyrate kinase, a phosphotransbutyrylase, and a PHA synthase. Different homopolymers were produced, consisting of either 3-mercaptopropionate, 3-mercaptobutyrate, or 3-mercaptovalerate repeating units, if the respective mercaptoalkanoic acids were provided as precursor substrates to the fermentative process. The PTEs contributed up to 30% (w/w) of the cellular dry weight and were identified as hydrophobic inclusions in the cytoplasm. The chemical and stereochemical homogeneity of the purified PTEs were identified by different methods, and the estimated physical properties were compared to the oxypolyester equivalents, revealing low crystalline order and, for the poly(3-mercaptopropionate) improved thermal stability. The ability to produce PTEs through a biosynthetic route opens up new avenues in the field of biomaterials.     

Analysis of polycyclic aromatic hydrocarbons in soil: minimizing sample pretreatment using automated Soxhlet with ethyl acetate as extraction solvent

A simplified sample pretreatment method for industrially PAH-contaminated soils applying automated Soxhlet (Soxtherm) with ethyl acetate as extraction solvent is presented. Laborious pretreatment steps such as drying of samples, cleanup of crude extracts, and solvent exchange were allowed to be bypassed without notable performance impact. Moisture of the soil samples did not significantly influence recoveries of PAHs at a wide range of water content for the newly developed method. However, the opposite was true for the standard procedure using the more apolar 1:1 (v/v) n-hexane/acetone solvent mixture including postextraction treatments recommended by the U.S. EPA. Moreover, ethyl acetate crude extracts did not appreciably effect the chromatographic performance (HPLC-(3D)FLD), which was confirmed by a comparison of the purity of PAH spectra from both pretreatment methods. Up to 20% (v/v) in acetonitrile, ethyl acetate proved to be fully compatible with the mobile phase of the HPLC whereas the same concentration of n-hexane/acetone in acetonitrile resulted in significant retention time shifts. The newly developed pretreatment method was applied to three historically contaminated soils from different sources with extraction efficiencies not being significantly different compared to the standard procedure. Finally, the certified reference soil CRM 524 was subjected to the simplified procedure resulting in quantitative recoveries (>92%) for all PAHs analyzed.     

Parallel flow measurements in microstructures by use of a multifocal 4 x 1 diffractive optical fan-out element

We have developed a multifocal optical fluorescence correlation spectroscopy system for parallel flow analyses. Multifocal excitation was made possible through a 4 x 1 diffractive optical fan-out element, which produces uniform intensity in all four foci. Autocorrelation flow analyses inside a 20 microm x 20 microm square microchannel, with the 4 x 1 fan-out foci perpendicular to the flow direction, made it possible to monitor different flows in all four foci simultaneously. We were able to perform cross-correlation flow analyses by turning the microstructure, thereby having all four foci parallel to the direction of flow. Transport effects of the diffusion as a function of flow and distance could then also be studied.     

Tuneable Heterodyne Infrared Spectrometer for atmospheric and astronomical studies

The transportable setup of the Cologne Tuneable Heterodyne Infrared Spectrometer (THIS) is presented. Frequency tuneability over a wide range provided by the use of tuneable diode lasers as local oscillators (LO) allows a variety of molecules in the mid-infrared to be observed. Longtime integration, which is essential for astronomical observations, is possible owing to tight frequency control of the LO with optical feedback from an external cavity. THIS is developed to fly on the Stratospheric Observatory for Infrared Astronomy beginning in 2006 but can also be used on different types of ground-based telescopes.     

Long-term patterns and predictors of successful stressor resolution in later life.

At 1 year, 4 years, and 10 years after baseline, late-middle-aged adults reported whether they had successfully resolved their most important stressor of the past year. Compared to individuals who never resolved focal stressors over the 10-year interval, those who always did consistently showed less negative stressor appraisal, less reliance on avoidance coping, and less use of exploratory relative to directed coping responses, independent of type and severity of focal stressor. Less use of exploratory relative to directed coping and having more social resources, fewer health problems, and fewer depressive symptoms at baseline predicted more stressor resolution over the next 10 years. These predictors are promising foci for prospective efforts to optimize ways in which aging adults manage late-life stressors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On some operations on strings suggested by gene assembly in ciliates

We define three operations on strings and languages suggested by the process of gene assembly in hypotrichous ciliates. This process is considered to be a prine example of DNA computing in vivo. This paper is devoted to some computational aspects of these operations from a formal language point of view. The closure of the classes of regular and context-free languages under these operations is settled. Then, we consider theld-macronuclear language of a given languageL, which consists of allld-macronuclear strings obtained from the strings ofL by iteratively applying the loop-direct repeat-excision. Finally, we discuss some open problems and further directions of research. Rudolf Freund: He received his master and doctor degree in computer science from the Vienna University of Technology, Austria, in 1980 and 1982, respectively. In 1986, he received his master degree in mathematics and physics from the University Vienna, Austria. In 1988 he joined the Vienna University of Technology in Austria, where he became an Associate Professor in September 1995. He has given various lectures in theoretical computer science, especially on formal languages and automata. His research interests include array and graph grammars, regulated rewritung, infinite words, syntactic pattern recognition, neural networks, and especially models and systems for biological computing. In these fields he is author of more than sixty scientific papers. Carlos Martín-Vide: He is Professor and Head of the Research Group on Mathematical Linguistics at Rovira i Virgili University, Tarragona, Spain. His specialities are formal language theory and mathematical linguistics. His last volume edited is Where Mathematics, Computer Science, Linguistics and Biology Meet (Kluwer, 2001, with V. Mitrana). He published 150 papers in conference proceedings and journals such as: Acta Informatica, BioSystems. Computational Linguistics, Computers and Artificial Intelligence, Information Processing Letters, Information Sciences, International Journal of Computer Mathematics, New Generation Computing, Publicationes Mathematicae Debrecen, and Theoretical Computer Science. He is the editor-in-chief of the journal Grammars (Kluwer), and the chairman of the 1st International PhD School in Formal Languages and Applications (2001–2003). Victor Mitrana, Ph.D.: He is Professor of Computer Science at the Faculty of Mathematics, University of Bucharest. He received his MSc and PhD from the University of Bucharest in 1986 and 1993, respectively. In 1999 he was awarded with the “Gheorghe Lazar” Prize for Mathematics of the Romanian Academy. His research interests include: formal language theory and applications, combinatorics on words, computational models inspired from biology, mathematical linguistics. In these areas, he published three books, more than 100 papers, and edited two books. He is an associate editor of “The Korean Journal of Computational and Applied Mathematics” and an editor of “Journal of Universal Computer Science”.     

Prognose der Sorptionskinetik organischer Schadstoffe in heterogenem Aquifermaterial

A model for the simulation of kinetic sorption processes in heterogeneous aquifer material is presented. Sorption kinetics is responsible for the long persistence of many organic contaminants in the subsurface. Therefore, reliable model predictions of these processes are of major importance concerning, for instance, the design of efficient remediation strategies. The modeling approach presented here recognizes sorption kinetics as retarded diffusion within the intra-particle pore space and, in particular, takes into account the sedimentological and petrographical composition of the aquifer material. This is in accordance with results from laboratory experiments quantifying sorption/desorption processes. For solving the model equations a finite-difference scheme is applied which incorporates several features proven to be relevant in practical model applications (mass balance, flexible choice of boundary conditions, easy handling). The simulation results shown here focus on the impact of aquifer heterogeneity (lithological composition, grain size distribution) on sorption and desorption kinetics of organic contaminants. Furthermore, this approach can be straightforwardly coupled to existing software for simulating multi-dimensional solute transport.     

A Local Database Manager for Engineering Analysis Systems

Abstract: A local database manager (LDBM) is presented. It is a software development tool consisting of a set of easy-to-use in-core data management subroutines written in FORTRAN 77. One of the main motivations for the development of this LDBM was to enhance the eflcient use of core memory which seems to be obvious with respect to a PC programming environment. However, even on virtual machines, high performance achieved by minimizing page faults is strongly based on a sophisticated database management system (DBMS). In order to accomplish this objective, the LDBM allows the use of different data types according to the requirements of the actual situation and to the existing programming environment. Integer, short integer, real, double precision, complex, double complex and character data can be handled. Moreover, a two-level hierarchical data structure is used which groups related data in a different and more economic way rather than by means of increasing the number of levels in the DIMENSION statement. Of course, old, no longer used data may be deleted, leaving room for the allocation of new data. Using a technique of 'flexible garbage collection', i.e. the ensuing gap after the deletion of a data block is not automatically closed, the time consumed by the LDBM during a deletion operation is actually not affected by the length of data blocks.