Investigation of the Burning Behavior of Cryogenic Solid Propellants

Cryogenic Solid Propellant (CSP)‐technology is a new approach to develop more powerful rocket motors. CSPs include the advantages of classical solid propellants to save weight as well as those of a high energy content and safety of modern liquid propellants. The charges consist of liquid and/or gaseous fuels and oxidizers, both frozen. Two main versions of CSP‐technology can be realised: 1. Mono‐CSPs show the burning behavior of solid propellants. Experiments with mono‐CSPs have been carried out under inert pressure conditions in a window bomb. Mono‐CSPs have a stable burning behavior with a constant regression rate which follows the Vieille's law under varying pressure conditions. 2. The advantage of high safety is obtained by assembling oxidizer and fuel in sandwich configurations. The grain geometry governs the burning behavior. Such systems can be externally controlled, e.g. by the heat from a gas generator or they can work self‐sustained. A Rod‐in‐Matrix burner shows self‐sustained combustion in an inert pressure atmosphere with overall burning rates in a similar range as solid rocket propellants which obey also a Vieille‐like pressure law. Disc stack burners have also been investigated, the combustion of which is strongly dependent on the disc thickness. For a short time Mach's nodes have been observed in the exhaust plume of a disc stack burner. Currently, the temperature ranges are limited to the boiling temperature of liquid nitrogen. Therefore, liquid oxidizers like H₂O₂ have been used. However, for the first time a propellant strand of polymer rods embedded in solid oxygen was prepared and burnt. The experiments with CSPs end in the combustion of a small rocket motor showing no serious technical obstacles. Simplified models based on the heat flow equation can simulate the burning characteristics of the frozen energetic materials including phase transitions.     

Curcumin‐Derived Pyrazoles and Isoxazoles: Swiss Army Knives or Blunt Tools for Alzheimer's Disease?

Curcumin binds to the amyloid beta peptide (Abeta) and inhibits or modulates amyloid precursor protein (APP) metabolism. Therefore, curcumin-derived isoxazoles and pyrazoles were synthesized to minimize the metal chelation properties of curcumin. The decreased rotational freedom and absence of stereoisomers was predicted to enhance affinity toward Abeta(42) aggregates. Accordingly, replacement of the 1,3-dicarbonyl moiety with isosteric heterocycles turned curcumin analogue isoxazoles and pyrazoles into potent ligands of fibrillar Abeta(42) aggregates. Additionally, several compounds are potent inhibitors of tau protein aggregation and depolymerized tau protein aggregates at low micromolar concentrations.     

Magnetresonanz-Messung von Eisenumsatzprozessen in Sanden: Nicht-invasive Charakterisierung von Reaktionsabläufen

In this study, Nuclear Magnetic Resonance (NMR), a non-destructive measurement technique, has been applied for investigation of iron turn-over processes. In non-invasive laboratory experiments, iron dissolution and precipitation reactions in saturated natural sands were observed spatially and temporally. These processes play an important role in groundwater with varying redox and pH conditions. Redox reactions turning Fe²⁺ into Fe³⁺ and Fe³⁺ into Fe²⁺ were detected in aqueous solution by the difference in magnetic relaxation times. Furthermore, the spatial distribution of the iron reduction reaction, the consumption and diffusive transfer to and from the reaction sites, was observed in a 1D set-up with natural sands. The achieved spatial resolution was less than one millimetre while repeating measurements every half an hour. It showed the system changing from diffusion-limited to reaction-limited.     

Event-driven architecture for decision support in traffic management systems

Decision support systems for traffic management systems have to cope with a high volume of events continuously generated by sensors. Conventional software architectures do not explicitly target the efficient processing of continuous event streams. Recently, event-driven architectures (EDA) have been proposed as a new paradigm for event-based applications. In this paper we propose a reference architecture for event-driven traffic management systems, which enables the analysis and processing of complex event streams in real-time and is therefore well-suited for decision support in sensor-based traffic control systems. We will illustrate our approach in the domain of road traffic management. In particular, we will report on the redesign of an intelligent transportation management system (ITMS) prototype for the high-capacity road network in Bilbao, Spain.     

Symbolic model checking for channel-based component connectors

This paper introduces a temporal logic framework to reason about the coordination mechanisms and data flow of exogenous coordination models. We take a CTL-like branching time logic, augmented with regular expressions that specify the observable I/O-operations, as a starting point. The paper provides the syntax and semantics of our logic and introduces the corresponding model checking algorithm. The second part of the paper reports an implementation that relies on a symbolic representation of the coordination network and the connected components by means of binary decision diagrams. A couple of examples are given to illustrate the efficiency of the model checking techniques and their implementation.     

Symbolic Model Checking for Channel-based Component Connectors

The paper reports on the foundations and experimental results with a model checker for component connectors modelled by networks of channels in the calculus Reo. The specification formalisms is a branching time logic that allows to reason about the coordination principles of and the data flow in the network. The underlying model checking algorithm relies on variants of standard automata-based approaches and model checking for CTL-like logics. The implementation uses a symbolic representation of the network and the enabled I/O-operations by means of binary decision diagrams. It has been applied to a couple examples that illustrate the efficiency of our model checker.     

Lemon balm extract causes potent antihyperglycemic and antihyperlipidemic effects in insulin‐resistant obese mice

Over the last decades polyetiological metabolic diseases such as obesity and type 2 diabetes have emerged as a global epidemic. Efficient strategies for prevention and treatment include dietary intervention and the development of validated nutraceuticals. Safe extracts of edible plants provide a resource of structurally diverse molecules that can effectively interfere with multifactorial diseases. In this study, we describe the application of ethanolic lemon balm (Melissa officinalis) leaves extract for the treatment of insulin‐resistance and dyslipidemia in mice. We show that lemon balm extract (LBE) activates the peroxisome proliferator‐activated receptors (PPARs), which have key roles in the regulation of whole body glucose and lipid metabolism. Application of LBE (0.6 mg/mL) to human primary adipocytes resulted in specific peroxisome proliferator‐activated receptor target gene expression. LBE treatment of insulin‐resistant high‐fat diet‐fed C57BL/6 mice (200 mg/kg/day) for 6 weeks considerably reduced hyperglycemia and insulin resistance, plasma triacylglycerol, nonesterified fatty acids and LDL/VLDL cholesterol levels. Taken together, ethanolic lemon balm extract can potentially be used to prevent or concomitantly treat type 2 diabetes and associated disorders such as dyslipidemia and hypercholesterolemia.     

Green electricity policies in the Netherlands: an analysis of policy decisions

Over the last decades, fundamental changes can be observed in both market conditions and the national policy framework for green electricity in the Netherlands. The Dutch Government has regularly intervened in markets, demonstrating fundamental shifts in policy and approach. This study aims to analyse the developments in renewable energy policy making in the Netherlands. It assesses changes in the choice of policy instruments and target groups, the role of stakeholders, and offers explanations behind policy successes and failures. Dutch green electricity policy over the last decade can be characterised roughly by three phases: in the early 1990s, the government negotiated voluntary agreements with the energy distribution sector on targets for green electricity sales, which were never met. In the second half of the 1990s, a regulatory energy tax was introduced, from which customers of green electricity were exempt. This led to a substantial increase in demand, which was largely met by green electricity imports, and did not lead to additional domestic renewable energy capacity. Finally, a change in policy has taken place recently (2003) shifting the focus from promotion of demand to the promotion of supply through a system of regulated feed-in tariffs. Despite the renewable energy policies, growth of the renewable energy market in the Netherlands has been small and targets have not been fully met. The Dutch government has not yet succeeded in substantially reducing market uncertainties and in building confidence among market parties, because the policies have not been stable and policy objectives have frequently been partly ambiguous. In addition, the influence of stakeholders in renewable energy policy making has been small which has the early acceptance and implementation of alternative policies.