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Umgang mit Lebenskrisen
(2015)
A 2D-separation of 16 polyaromatic hydrocarbons (PAHs) according to the Environmental Protecting Agency (EPA) standard was introduced. Separation took place on a TLC RP-18 plate (Merck, 1.05559). In the first direction, the plate was developed twice using n-pentane at −20°C as the mobile phase. The mixture acetonitrile-methanol-acetone-water (12:8:3:3, v/v) was used for developing the plate in the second direction. Both developments were carried out over a distance of 43 mm. Further on in this publication, a specific and very sensitive indication method for benzo[a]pyrene and perylene was presented. The method can detect these hazardous compounds even in complicated PAH mixtures. These compounds can be quantified by a simple chemiluminescent reaction with a limit of detection (LOD) of 48 pg per band for perylene and 95 pg per band for benzo[a]pyrene. Although these compounds were separated from all other PAHs in the standard, a separation of both compounds was not possible from one another. The method is suitable for tracing benzo[a]pyrene and/or perylene. The proposed chemiluminescence screening test on PAHs is extremely sensitive but may indicate a false positive result for benzo[a]pyrene.
The state-of-the-art electrochemical impedance spectroscopy (EIS) calculations have not yet started from fully multi-dimensional modeling. For a polymer electrolyte membrane fuel cell (PEMFC) with long flow channel, the impedance plot shows a multi-arc characteristic and some impedance arcs could merge. By using a step excitation/Fourier transform algorithm, an EIS simulation is implemented for the first time based on the full 2D PEMFC model presented in the first part of this work. All the dominant transient behaviors are able to be captured. A novel methodology called ‘configuration of system dynamics’, which is suitable for any electrochemical system, is then developed to resolve the physical meaning of the impedance spectra. In addition to the high-frequency arc due to charge transfer, the Nyquist plots contain additional medium/low-frequency arcs due to mass transfer in the diffusion layers and along the channel, as well as a low-frequency arc resulting from water transport in the membrane. In some case, the impedance spectra appear partly inductive due to water transport, which demonstrates the complexity of the water management of PEMFCs and the necessity of physics-based calculations.
A two-dimensional single-phase model is developed for the steady-state and transient analysis of polymer electrolyte membrane fuel cells (PEMFC). Based on diluted and concentrated solution theories, viscous flow is introduced into a phenomenological multi-component modeling framework in the membrane. Characteristic variables related to the water uptake are discussed. A Butler–Volmer formulation of the current-overpotential relationship is developed based on an elementary mechanism of electrochemical oxygen reduction. Validated by using published V–I experiments, the model is then used to analyze the effects of operating conditions on current output and water management, especially net water transport coefficient along the channel. For a power PEMFC, the long-channel configuration is helpful for internal humidification and anode water removal, operating in counterflow mode with proper gas flow rate and humidity. In time domain, a typical transient process with closed anode is also investigated.
Systemic Constellations are a phenomenological approach to resolving personal, professional and organizational issues. They offer a way of mapping a present reality, working at the source of the hidden dynamics and moving to a resolution. This systemic approach often delivers surprising and unexpected insights while also offering the possibility to analyze and solve organizational problems. Rational analysis provides the whole picture of the problem which often turns out to be too complex for a decision making. Systemic constellations can help to simplify and clarify the situation and inform what has to happen next [8], [17]. The outcomes of systemic constellations as an additional resource for solving comprehensive technical problems have not yet been sufficiently investigated. In structural constellation work dealing with technical problems, the individuals who are involved in the problem situation are used to represent different system components, substances or fields. A moderator voices the feedback from the representatives concerning their feelings or intuitive movements, and points to possible solutions. For example, a moderator places the representatives somewhere in the room, develops a three-dimensional picture of the constellation of the analyzed situation and tries to expose the factors empowering or blocking the way towards constructive solutions [13]. This paper explores the theoretical background and practical outcomes of the systemic constellation method for technical problem solving. It presents some case study work which has been conducted in recent years, and then discusses its findings and implications. The research outlined in this paper demonstrates that the noteworthy contribution of structural constellation work for problem solving is typically the result of a combination of functional analysis and the feeling-as-information principle. The constellation work helps, at first, to reveal the subjective experiences, such as feelings, moods, emotions, and bodily sensations, and then to accept them as a source of objective information relevant to the decision making process. In accordance with the latest research [19], the use of feelings as a source of information follows the same principles as the use of any other information. This paper provides the structures of some standard templates and types of constellation work for technical problems, and discusses the preconditions for their application.
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.
Eine repräsentative Studie mit 2.400 deutschen Arbeitnehmern zeigt, dass Mitarbeiter seltener krank werden, wenn sie sich an ihr Unternehmen gebunden fühlen. Die Studie offenbart auch, dass die Intensität des Commitment maßgeblich von fünf Einflussfaktoren abhängt. Die Kenntnis dieser Faktoren ermöglicht es Personalmanagern, Mitarbeiter gezielter an das Unternehmen zu binden, um so den Krankenstand positiv zu beeinflussen.
Transcatheter aortic valve implantation is a therapy for patients with reduced left ventricular ejection fraction and symptomatic aortic stenosis. The aim of the study was to compare the pre-and post- transcatheter aortic valve implantation procedures to determine the QRS and QT ventricular conduction times as a potential predictor of permanent pacemaker therapy requirement after transcatheter aortic valve implantation. QRS and QT ventricular conduction times were prolonged after transcatheter aortic valve implantation in heart failure patients with permanent dual chamber pacemaker therapy after transcatheter aortic valve implantation. QRS and QT ventricular conduction times may be useful parameters to evaluate the risk of post-procedural ventricular conduction block and permanent pacemaker therapy in transcatheter aortic valve implantation.
We present a 3D simulation approach utilising the diffuse interface representation of the phase-field method combined with a heat transfer equation to analyse the thermal conductivity in air-filled aluminium foams with complex cellular structures of different porosity. Algorithmic methods are introduced to create synthetic open-cell foam structures and to compute the thermal conductivity by means of phase-field modelling. A material law for the effective thermal conductivity is derived by determining the appropriate exponent depending on the relative density in the system. The results are compared with the thermal conductivity in massive aluminium and in pure air.
Photovoltaics Energy Prediction Under Complex Conditions for a Predictive Energy Management System
(2015)
The energy system of the future will transform from the current centralised fossil based to a decentralised, clean, highly efficient, and intelligent network. This transformation will require innovative technologies and ideas like trigeneration and the crowd energy concept to pave the way ahead. Even though trigeneration systems are extremely energy efficient and can play a vital role in the energy system, turning around their deployment is hindered by various barriers. These barriers are theoretically analysed in a multiperspective approach and the role decentralised trigeneration systems can play in the crowd energy concept is highlighted. It is derived from an initial literature research that a multiperspective (technological, energy-economic, and user) analysis is necessary for realising the potential of trigeneration systems in a decentralised grid. And to experimentally quantify these issues we are setting up a microscale trigeneration lab at our institute and the motivation for this lab is also briefly introduced.
Phosphate-based inorganic–organic hybrid nanoparticles (IOH-NPs) with the general composition [M]2+[Rfunction(O)PO3]2– (M = ZrO, Mg2O; R = functional organic group) show multipurpose and multifunctional properties. If [Rfunction(O)PO3]2– is a fluorescent dye anion ([RdyeOPO3]2–), the IOH-NPs show blue, green, red, and near-infrared fluorescence. This is shown for [ZrO]2+[PUP]2–, [ZrO]2+[MFP]2–, [ZrO]2+[RRP]2–, and [ZrO]2+[DUT]2– (PUP = phenylumbelliferon phosphate, MFP = methylfluorescein phosphate, RRP = resorufin phosphate, DUT = Dyomics-647 uridine triphosphate). With pharmaceutical agents as functional anions ([RdrugOPO3]2–), drug transport and release of anti-inflammatory ([ZrO]2+[BMP]2–) and antitumor agents ([ZrO]2+[FdUMP]2–) with an up to 80% load of active drug is possible (BMP = betamethason phosphate, FdUMP = 5′-fluoro-2′-deoxyuridine 5′-monophosphate). A combination of fluorescent dye and drug anions is possible as well and shown for [ZrO]2+[BMP]2–0.996[DUT]2–0.004. Merging of functional anions, in general, results in [ZrO]2+([RdrugOPO3]1–x[RdyeOPO3]x)2– nanoparticles and is highly relevant for theranostics. Amine-based functional anions in [MgO]2+[RaminePO3]2– IOH-NPs, finally, show CO2 sorption (up to 180 mg g–1) and can be used for CO2/N2 separation (selectivity up to α = 23). This includes aminomethyl phosphonate [AMP]2–, 1-aminoethyl phosphonate [1AEP]2–, 2-aminoethyl phosphonate [2AEP]2–, aminopropyl phosphonate [APP]2–, and aminobutyl phosphonate [ABP]2–. All [M]2+[Rfunction(O)PO3]2– IOH-NPs are prepared via noncomplex synthesis in water, which facilitates practical handling and which is optimal for biomedical application. In sum, all IOH-NPs have very similar chemical compositions but can address a variety of different functions, including fluorescence, drug delivery, and CO2 sorption.
Instabilities of the interface between two thin liquid films under DC electroosmotic flow are investigated using linear stability analysis followed by an asymptotic analysis in the long-wave limit. The two-liquid system is bounded by two rigid plates which act as substrates. The Boltzmann charge distribution is considered for the two electrolyte solutions and gives rise to a potential distribution in these liquids. The effect of van der Waals interactions in these thin films is incorporated in the momentum equations through the disjoining pressure. Marginal stability and growth rate curves are plotted in order to identify the thresholds for the control parameters when instabilities set in. If the upper liquid is a dielectric, the applied electric field can have stabilizing or destabilizing effects depending on the viscosity ratio due to the competition between viscous and electric forces. For viscosity ratio equal to unity, the stability of the system gets disconnected from the electric parameters like interface zeta potential and electric double-layer thickness. As expected, disjoining pressure has a destabilizing effect, and capillary forces have stabilizing effect. The overall stability trend depends on the complex contest between all the above-mentioned parameters. The present study can be used to tune these parameters according to the stability requirement.
Lean und ERP - Synergie oder Widerspruch? Ein neuer Ansatz zur Steigerung der Unternehmenseffizienz
(2015)
Eine erfolgreiche Zusammenführung der Vorteile von ERP-Systemen mit den Vorzügen des Lean-Ansatzes kann zur Erschließung eines erheblichen Verbesserungspotenzials und damit zu signifikanten Wettbewerbsvorteilen einer Unternehmung führen. Da dieser Ansatz in der Praxis häufig kritisiert und bisher kaum adäquat verfolgt wird, zielt dieser Beitrag darauf ab, einen innovativen Lösungsweg vorzustellen, welcher nicht nur theoretisch, sondern auch anhand eines ERP-Einführungsprojekts in einem KMU empirisch aufzeigt, dass Lean und ERP nutzbringend miteinander kombiniert werden können und sollten.