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Spangenberg B.,Offenburg University of Applied Sciences
Journal of Planar Chromatography - Modern TLC | Year: 2012

Improved separation of highly toxic contact herbicides paraquat (1,1′-dimethyl-4-4′-bipyridinium), diquat (6,7-dihydrodipyridol[ 1,2-a:2′,1′-c]pyrazine-5,8-di-ium), difenzoquat (1,2-dimethyl-3,5- diphenyl-1H-pyrazolium-methyl sulfate), mepiquat (1,1-dimethyl-piperidinium), and chloromequat (2-chloroethyltrimethylammonium) were presented by high-performance thin-layer chromatography (HPTLC). The quantification is based on a derivatization reaction, using sodium tetraphenylborate. Measurements were made in the wavelength range from 500 to 535 nm, using a light-emitting diode (LED) for excitation purposes, which emits very dense light at 365 nm. For calculations, a new theory of standard addition method was used, thus leading to a minimal error if exactly the same amount of sample content is added as a standard. The method provides a fast and inexpensive approach to quantification of the five most important quats used for plant protection purposes. The method works reliably because it takes into account losses during pre-treatment procedure. The method meets the European legislation limits for paraquat and diquat in drinking water according to United States Environmental Protection Agency (US EPA) method 549.2 which are 680 ng L -1 for paraquat and 720 ng L -1 for diquat. The method of standard addition in planar chromatography can be beneficially used to reduce systematic errors. Although recovery rates of 33.7% to 65.2% are observed, calculated contents according to the method of standard addition lie between 69% and 127% of the theoretical amounts. © Akadémiai Kiadó. Source


Riemann D.,Albert Ludwigs University of Freiburg | Nissen C.,Albert Ludwigs University of Freiburg | Palagini L.,University of Pisa | Otte A.,Offenburg University of Applied Sciences | And 2 more authors.
The Lancet Neurology | Year: 2015

Chronic insomnia is defined by difficulties in falling asleep, maintaining sleep, and early morning awakening, and is coupled with daytime consequences such as fatigue, attention deficits, and mood instability. These symptoms persist over a period of at least 3 months (Diagnostic and Statistical Manual 5 criteria). Chronic insomnia can be a symptom of many medical, neurological, and mental disorders. As a disorder, it incurs substantial health-care and occupational costs, and poses substantial risks for the development of cardiovascular and mental disorders, including cognitive deficits. Family and twin studies confirm that chronic insomnia can have a genetic component (heritability coefficients between 42% and 57%), whereas the investigation of autonomous and central nervous system parameters has identified hyperarousal as a final common pathway of the pathophysiology, implicating an imbalance of sleep-wake regulation consisting of either overactivity of the arousal systems, hypoactivity of the sleep-inducing systems, or both. Insomnia treatments include benzodiazepines, benzodiazepine-receptor agonists, and cognitive behavioural therapy. Treatments currently under investigation include transcranial magnetic or electrical brain stimulation, and novel methods to deliver psychological interventions. © 2015 Elsevier Ltd. Source


Lomonosov A.M.,University of Heidelberg | Hess P.,University of Heidelberg | Mayer A.P.,Offenburg University of Applied Sciences
Applied Physics Letters | Year: 2012

Acoustic waves guided by the cleaved edge of a Si(111) crystal were studied using a laser-based angle-tunable transducer for selectively launching isolated wedge or surface modes. A supersonic leaky wedge wave and the fundamental wedge wave were observed experimentally and confirmed theoretically. Coupling of the supersonic wave to shear waves is discussed, and its leakage into the surface acoustic wave was observed directly. The velocity and penetration depth of the wedge waves were determined by contact-free optical probing. Thus, a detailed experimental and theoretical study of linear one-dimensional guided modes in silicon is presented. © 2012 American Institute of Physics. Source


Tippmann S.,Deutsche ACCUmotive GmbH | Walper D.,Deutsche ACCUmotive GmbH | Balboa L.,Deutsche ACCUmotive GmbH | Spier B.,Deutsche ACCUmotive GmbH | Bessler W.G.,Offenburg University of Applied Sciences
Journal of Power Sources | Year: 2014

Fast charge of Li-ion cells is one of the main challenges in automotive battery application. As a particular problem at low temperatures and high charging rates, lithium deposits as metal on the anode surface (so-called lithium plating) instead of intercalation. Electrochemical models help to understand internal processes and predict aging effects, which finally lead to optimized charging strategies. In this work, a 1D + 1D (pseudo-2D) electrochemical model is developed, applied over a wide range of temperature (T = -25 C to 40 C) and current (I = 0.1 C to 6 C), and coupled with a 0D thermal model. The model is parameterized with measurement data in frequency domain using electrochemical impedance spectroscopy (EIS) and validated with time-domain data. In experiments cells are charged under different operating conditions. Capacity fade is measured after a significant number of cycles and compared to the simulated anode potential. A qualitative correlation is found between the degradation in experiment and the anode potential dropping below 0 V vs. Li/Li+ at the separator-anode boundary in the simulation. Furthermore a semi-quantitative expression for degradation is introduced. The transformation of the model into an on-board applicable form is presented in the companion contribution (part II). © 2013 Elsevier B.V. All rights reserved. Source


Dorer K.,Offenburg University of Applied Sciences
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

In their famous work on prospect theory Kahneman and Tversky have presented a couple of examples where human decision making deviates from rational decision making as defined by decision theory. This paper describes the use of extended behavior networks to model human decision making in the sense of prospect theory. We show that the experimental findings of non-rational decision making described by Kahneman and Tversky can be reproduced using a slight variation of extended behavior networks. © 2010 Springer. Source

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