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Search Results: 1 - 10 of 298 matches for " Matth?us "
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Physico-chemical properties, fatty acid and tocopherol composition of oils from some Sudanese oil bearing sources
Mariod, Abdalbasit,Matthus, Bertrand
Grasas y Aceites , 2008,
Abstract: Seven oils, obtained from seven Sudanese oil bearing sources that are Albizia lebbek Oil (ALO), Cassia obtusifolia Oil (COO), Cassia occidentalis Oil (CCO), Abutilon pannosum Oil (APO), Mitracarpus villous Oil (MVO), Ipomea indica Oil (IIO) and Sesamum alatum Oil (SAO), were investigated. The seeds were collected in Sudan from Ghibaish, North Kordofan state. In addition to the oil content, the fatty acid was determined by capillary gas chromatography and the tocopherols were evaluated by highperformance liquid chromatography. The oil content of the seven seeds amounted to 12.8, 7.0, 3.2, 7.1, 11.5, 8.8, and 21.3%, respectively.The oils contained 16.4, 20.0, 14.3, 16.8, 19.4, 19.9 and 10.9 % palmitic acid and 21.0, 24.4, 22.1, 10.9, 27.7, 34.0, 45.1 % oleic acid, and 43.8, 38.2, 45.0, 63.9, 34.6, 33.5, 36.3 % linoleic acid and traces of linolenic acid, respectively.The tocopherol content of these oils amounted to 85.6, 48.2, 32.7, 163.5, 52.5, 30.9, and 26.4 mg/100 g oil, respectively. Alpha-tocopherol was the predominant tocopherol in the oil of Albizia lebbek, Cassia obtusifolia, Cassia occidentalis, and Abutilon pannosum, while gamma-tocopherol was the predominant tocopherol in the oil of Mitracarpus villous, Ipomea indica and Sesamum alatum. Se analizan siete aceites procedentes de plantas y semillas de Sudán: Albizia lebbek Oil (ALO), Cassia obtusifolia Oil (COO), Cassia occidentalis Oil (CCO), Abutilon pannosum Oil (APO), Mitracarpus villous Oil (MVO), Ipomea indica Oil (IIO) y Sesamum alatum Oil (SAO). Las semillas se recolectaron en el estado de Ghibaish, North Kordofan. Además del contenido en aceite (12.8, 7.0, 3.2, 7.1, 11.5, 8.8, y 21.3 %, respectivamente), se determinaron los ácidos grasos mediante cromatografía de gases y los tocoferoles mediante HPLC. Los aceites contenían, respectivamente, 16.4, 20.0, 14.3, 16.8, 19.4, 19.9 y 10.9 % de ácido palmitito, 21.0, 24.4, 22.1, 10.9, 27.7, 34.0, 45.1 % de ácido oleico, 43.8, 38.2, 45.0, 63.9, 34.6, 33.5 y 36.3 % de ácido linoleico y trazas de ácido linolenico. El contenido en tocoferol total fue de 85.6, 48.2, 32.7, 163.5, 52.5, 30.9, y 26.4 mg/100 g oil, respectivamente. Alfa-tocopherol fue el predominante en los aceites de Albizia lebbek, Cassia obtusifolia, Cassia occidentalis, y Abutilon pannosum, mientras gamma-tocopherol fue el mayoritario en los aceites de was the predominant tocopherol in the oil of Mitracarpus villous, Ipomea indica y Sesamum alatum.
Amplitude equations near pattern forming instabilities for strongly driven ferromagnets
F. Matthus,H. Sauermann
Physics , 1995, DOI: 10.1007/BF02769989
Abstract: A transversally driven isotropic ferromagnet being under the influence of a static external and an uniaxial internal anisotropy field is studied. We consider the dissipative Landau-Lifshitz equation as the fundamental equation of motion and treat it in $1+1$~dimensions. The stability of the spatially homogeneous magnetizations against inhomogeneous perturbations is analyzed. Subsequently the dynamics above threshold is described via amplitude equations and the dependence of their coefficients on the physical parameters of the system is determined explicitly. We find soft- and hard-mode instabilities, transitions between sub- and supercritical behaviour, various bifurcations of higher codimension, and present a series of explicit bifurcation diagrams. The analysis of the codimension-2 point where the soft- and hard-mode instabilities coincide leads to a system of two coupled Ginzburg-Landau equations.
On the degenerated soft-mode instability
Wolfram Just,Frank Matthus,Herwig Sauermann
Physics , 1998, DOI: 10.1088/0305-4470/31/28/008
Abstract: We consider instabilities of a single mode with finite wavenumber in inversion symmetric spatially one dimensional systems, where the character of the bifurcation changes from sub- to supercritical behaviour. Starting from a general equation of motion the full amplitude equation is derived systematically and formulas for the dependence of the coefficients on the system parameters are obtained. We emphasise the importance of nonlinear derivative terms in the amplitude equation for the behaviour in the vicinity of the bifurcation point. Especially the numerical values of the corresponding coefficients determine the region of coexistence between the stable trivial solution and stable spatially periodic patterns. Our approach clearly shows that similar considerations fail for the case of oscillatory instabilities.
Can spurious indications for phase synchronization due to superimposed signals be avoided?
Stephan Porz,Matthus Kiel,Klaus Lehnertz
Quantitative Biology , 2014, DOI: 10.1063/1.4890568
Abstract: We investigate the relative merit of phase-based methods---mean phase coherence, unweighted and weighted phase lag index---for estimating the strength of interactions between dynamical systems from empirical time series which are affected by common sources and noise. By numerically analyzing the interaction dynamics of coupled model systems, we compare these methods to each other with respect to their ability to distinguish between different levels of coupling for various simulated experimental situations. We complement our numerical studies by investigating consistency and temporal variations of the strength of interactions within and between brain regions using intracranial electroencephalographic recordings from an epilepsy patient. Our findings indicate that the unweighted and weighted phase lag index are less prone to the influence of common sources but that this advantage may lead to constrictions limiting the applicability of these methods.
Biosynthetic Potentials of Metabolites and Their Hierarchical Organization
Franziska Matthus ,Carlos Salazar ,Oliver Ebenh?h
PLOS Computational Biology , 2008, DOI: 10.1371/journal.pcbi.1000049
Abstract: A major challenge in systems biology is to understand how complex and highly connected metabolic networks are organized. The structure of these networks is investigated here by identifying sets of metabolites that have a similar biosynthetic potential. We measure the biosynthetic potential of a particular compound by determining all metabolites than can be produced from it and, following a terminology introduced previously, call this set the scope of the compound. To identify groups of compounds with similar scopes, we apply a hierarchical clustering method. We find that compounds within the same cluster often display similar chemical structures and appear in the same metabolic pathway. For each cluster we define a consensus scope by determining a set of metabolites that is most similar to all scopes within the cluster. This allows for a generalization from scopes of single compounds to scopes of a chemical family. We observe that most of the resulting consensus scopes overlap or are fully contained in others, revealing a hierarchical ordering of metabolites according to their biosynthetic potential. Our investigations show that this hierarchy is not only determined by the chemical complexity of the metabolites, but also strongly by their biological function. As a general tendency, metabolites which are necessary for essential cellular processes exhibit a larger biosynthetic potential than those involved in secondary metabolism. A central result is that chemically very similar substances with different biological functions may differ significantly in their biosynthetic potentials. Our studies provide an important step towards understanding fundamental design principles of metabolic networks determined by the structural and functional complexity of metabolites.
On the Origin and Characteristics of Noise-Induced Lévy Walks of E. Coli
Franziska Matthus,Mario S. Mommer,Tine Curk,Jure Dobnikar
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018623
Abstract: Lévy walks as a random search strategy have recently attracted a lot of attention, and have been described in many animal species. However, very little is known about one of the most important issues, namely how Lévy walks are generated by biological organisms. We study a model of the chemotaxis signaling pathway of E. coli, and demonstrate that stochastic fluctuations and the specific design of the signaling pathway in concert enable the generation of Lévy walks. We show that Lévy walks result from the superposition of an ensemble of exponential distributions, which occurs due to the shifts in the internal enzyme concentrations following the stochastic fluctuations. With our approach we derive the power-law analytically from a model of the chemotaxis signaling pathway, and obtain a power-law exponent , which coincides with experimental results. This work provides a means to confirm Lévy walks as natural phenomenon by providing understanding on the process through which they emerge. Furthermore, our results give novel insights into the design aspects of biological systems that are capable of translating additive noise on the microscopic scale into beneficial macroscopic behavior.
Long-term storage of three unconventional oils
Mariod, Abdalbasit,Matthus, Bertrand,Eichner, K.,Hussein, Ismail H.
Grasas y Aceites , 2008,
Abstract: Three samples, Sclerocarya birrea oil (SCO), Melon bug oil (Aspongubus viduatus) (MBO), and Sorghum bug oil (Agonoscelis pubescens) (SBO), were stored (autoxidized) in the dark at 30 ±2 °C for 24 months. Oil aliquots were withdrawn every 2-4 month for analyses of changes in four quality indexes, namely fatty acid composition, tocopherol content, peroxide value and oxidative stability index by Rancimat. After 24 months of storage the fatty acid composition of the three oils showed no change while tocopherol contents were decreased. SCO and MBO showed only slight changes in their oxidative stability as indicated by the peroxide value and induction period during the 24 months of storage. Sorghum bug oil showed a periodical increase in the peroxide value and had less stability as measured by the Rancimat in comparison to other oils. Tres muestras de aceite, Sclerocarya birrea oil (SCO), Melon bug oil (Aspongubus viduatus) (MBO), and Sorghum bug oil (Agonoscelis pubescens) (SBO), fueron almacenadas en la oscuridad a 30 ±2 °C durante 24 meses. Cada 2- 4 meses se toman alícuotas para analizar los cambios de calidad. Se determinaron la composición en ácidos grasos, el contenido en tocoferol, el índice de peróxidos y la estabilidad oxidativa mediante el aparato Rancimat. Después de 24 meses de almacenamiento, la composición en ácidos grasos no experimentó variación mientras que el contenido en tocoferol disminuyó en los tres aceites. SCO y MBO mostraron cambios minoritarios como se comprobó por los indices de peroxides y estabilidad a los 24 meses. SBO fue el menos estable de los tres aceites.
The new database “Seed oil Fatty Acids” (SOFA)
Friedrich, H.,Aitzetmüller, K.,Matthus, B.
Grasas y Aceites , 2003,
Abstract: More than 30 years i n formation about the fatty acid composit ion of wi ld plant seeds was collected f rom the appropriate pharmaceutical, botanical and chemical literature by the former Institute for Chemistry and Physics of Lipids of the Federal Center for Cereal, Potato and Lipid Research in Münster. Since it was very difficult to search this unique source of information, the collection was transferred into an electronically searchable database. This plan was supported by financial assistance of the German Ministry of Consumer Protection, Food and Agriculture. Since some month the database is available in the internet (http:www.bagkf.de/sofa) free of charge. Up to now more than 18.000 different tables with about 110.000 individual data are recallable from the database, by different types of search forms. An overview about the application of the different search forms as well as some examples for searches is given in this publication. Mas de 30 a os de información sobre la composición en ácidos grasos de semillas de plantas silvestres ha sido recogida de la literatura farmacéutica, botánica y química por el antiguo Institute for Chemistry and Physics del Federal Center for Cereal, Potato and Lipid Research en Münster. Desde hace varios meses la base de datos está ya disponible sin cargo alguno en Internet (http:www.bagkf.de/sofa). Hasta ahora más de 18.000 tablas diferentes con alrededor de 110.000 datos individuales pueden obtenerse a partir de esa base de datos mediante diferentes tipos de búsquedas. Una panorámica de la aplicación de las diferentes posibles formas de búsquedas así como algunos ejemplos de búsquedas se dan en este artículo.
Temporal and spatial evolution of the Baltic deep water renewal in spring 2003
Rainer Feistel,Günther Nausch,Wolfgang Matthus,Eberhard Hagen
Oceanologia , 2003,
Abstract: In January 2003, a deep-water renewal process in the Baltic Sea commenced with an inflow of about 200 km3 of cold and well oxygenated water from the Kattegat, half of which was of salinity >17 PSU; it is considered to be the most important inflow since 1993. Related front propagation and the ventilation of anoxic waters between the western and the central Baltic were recorded by the Darss Sill measuring mast, the Arkona Basin buoy, a subsurface mooring in the Eastern Gotland Basin, and hydrographic research cruises conducted in January, February, March, May and August 2003. Already in May, the central Gotland Basin was reached by water with near-bottom oxygen concentrations among the highest ever recorded there. A comprehensive review of the observed spatial and temporal structures together with additional background data is presented. Estimates of the intensity of the present inflow are discussed.
Hydrographic and hydrochemical conditions in the Gotland Deep area between 1992 and 2003
Günther Nausch,Wolfgang Matthus,Rainer Feistel
Oceanologia , 2003,
Abstract: The paper describes the hydrographic-hydrochemical development in the eastern Gotland Basin between the major saltwater inflows into the Baltic Sea in 1993 and 2003. This period is characterised by only low inflow activity. The most important hydrographic events were the effects of the very strong inflow in 1993 and the weak inflows in 1993/1994 and 1997. The 1993/1994 inflows led to deep-water renewal, a steep fall in deep-water temperatures, and increasing salinity. The effects of the inflow of very warm, saline and oxygen-rich water in autumn 1997 were observed in the deep water in 1998, resulting in temperatures rising to 7°C. The recent renewal in spring 2003 is reflected in the decreasing temperature, higher salinity and improved ventilation of the bottom water. Changes in the redox conditions exert a considerable influence on the nutrient distribution. During stagnation periods, there is enrichment of phosphate and ammonium, while nitrate is absent. Thus, around 31 μmol l-1 ammonium and 7 μmol l-1 phosphate were measured prior to the water renewal in 2003. Deep-water ventilation results in lower phosphate concentrations of around 2 μmol l-1, the nitrification of ammonium and the occurrence of nitrate. For the observation period, an estimate of nutrients stored in the deep water was done for the eastern Gotland Basin. During the recent stagnation period, there was an increase of up to 150% in the phosphate pool below the halocline, whereas the pool of inorganic nitrogen compounds decreased to 80% compared with 1992 when the previous stagnation period had ended. Under specific circumstances, these unbalanced nutrients can be made available to the upper water layers and can induce large-scale blooms of algae, especially of cyanobacteria.
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