Vorkommen und Entstehung von Dimethylsulfid im Spargelaroma

Zusammenfassung Aus kochendem Spargel warden 28 mg Dimethylsulfid/kg als S,S-Dimethyl(p-tolylsulfonyl)-sulfidimin isoliert. Die Identifizierung erfolgte durch Dünnschichtchromatographie und Schmelzpunktbestimmung.Um die Entstehung des Dimethylsulfids im Spargel zu klären, warden in Modellversuchen dem gekochten Spargel Dimethylsulfid, S-Methylmethionin-sulfoniumchlorid, Methionin und Methylmercaptan zugesetzt. Der zeitliche Verlauf der Sulfidimin-Bildung stimmt bei Spargel mit S-Methylmethionin-sulfoniumchlorid und frischem Spargel praktisch überein. Methionin und Methylmercaptan bildeten kein Dimethylsulfid-Derivat.     

Influence of inspiratory resistance on performance during graded exercise tests on a cycle ergometer

Due to more stringent requirements to protect personnel against hazardous gasses, the inspiratory resistance of the present generation of respiratory protective devices tends to increase. Therefore an important question is to what extent inspiratory resistance may increase without giving problems during physical work. In this study the effects of three levels (0.24; 1.4 and 8.3 kPa s l⁻¹) of inspiratory resistance were tested on maximal voluntary performance. Nine male subjects performed a graded exercise test on a cycle ergometer with and without these three levels of inspiratory resistance. Oxygen consumption, heart rate, time to exhaustion and external work were measured. The results of these experiments showed that increasing inspiratory resistance led to a reduction of time to exhaustion (TTE) on a graded exercise test(GXT). Without inspiratory resistance the mean TTE was 11.9 min, the three levels of resistance gave the following mean TTE's: 10.7, 7.8 and 2.7 min. This study showed that TTE on a GXT can be predicted when physical fitness (VO₂-max) of the subject and inspiratory resistance are known. The metabolic rate of the subjects was higher with inspiratory resistance, but no differences were found between the three selected inspiratory loads. Other breathing parameters as minute ventilation, tidal volume, expiration time and breathing frequency showed no or minor differences between the inspiratory resistances. The most important conclusion of these experiments is that the overall workload increases due to an increase in inspiratory resistance by wearing respiratory protective devices.     

Ein Gesamtkonzept zur Ermittlung der seismischen Vulnerabilität von Bauwerken – am Beispiel unterirdischer Ver- und Entsorgungsleitungen

An overall concept for calculating the seismic vulnerability of buildings – at the example of underground pipelines. Earthquakes present a great risk for the safety of human lives and man-made buildings. While the extend of an earthquake that has to be expected at a specific location is well known through seismological mapping the resulting damage of buildings is more difficult to determine. Even more difficult is the prediction of the expected financial consequences, however, this is the most important question for the insurance industry. For this reason this article presents an overall concept for calculating the damage extend of buildings and the resulting financial loss on three different levels of accuracy. The developed overall concept is presented considering as example underground pipelines. However, especially the developed damage indicators and the methods for calculating the financial loss are transferable to other building types in an analogous manner. This flexibility is among others guaranteed by the modular design of the program system and the web based user surface.     

The security of energy infrastructure and supply in North Africa: Hydrocarbons and renewable energies in comparative perspective

While security risks to energy infrastructure and supply are frequently cited as a source of concern in the public debate on Europe’s energy relationships with North Africa, few academic publications have addressed the issue to date. This article focuses on two potential threats to energy security in the North African context: first, intenational disruption of energy supplies by governments; second, attacks by non-state actors on energy infrastructure. Based on an analysis of North African security and energy geopolitics, the article provides an assessment of these threats as they have materialized with regard to existing energy industries, particularly oil and gas. The article then seeks to apply the findings to renewable energy schemes that are currently being discussed and developed, gauging the likelihood and impact of such threats materializing in respect to various technologies, and differentiating between different states of the region. Finally, the article provides recommendations for policy and further research needs for a successful common European–North African energy future.     

Improvement of surface quality of 1.6220 cast steel by calibrating process and effects on material behavior

There is a growing demand for thin walled steel casting structural parts especially in the automotive industry. Therefore an economic casting process is needed, that provides high surface quality. Requirements of spot weldability and corrosion protection need to be met, which is not possible with high surface roughness. Therefore a calibrating step is introduced aimed at reducing the surface roughness of the sand cast steel samples. Besides surface quality, also changes in geometrical dimensions and mechanical properties are investigated. Calibrating was carried out as planar forging on a forging device. This combined process of casting and forging did lead to a significant reduction of the roughness values, but this effect could only be observed in the edge area of the investigated sample plates. Furthermore a deformation of material in thickness direction and flow of material in width direction was noted. A relationship between deformation in thickness direction and straightening was detected. Another one between material flow and reduction of roughness values. Tensile tests and impact tests revealed a more brittle behavior of the material in calibrated state. Also the influence of wall thickness and heat treatment was investigated. Whereas wall thickness (as the local amount of material) mainly determines deformability and in consequence the straightening effect, heat treatment increases the ability of the material to flow, which contributes to the reduction of surface roughness. The inhomogeneity of the surface effect in combination with an extraordinary high required force remain as the main issue in trying to achieve a uniform surface quality improvement by calibrating process.     

Synthesis and characterization of three-dimensional carbon foams-LiFePO4 composites

The characterization of three-dimensional (3D) carbon foams coated with olivine structured lithium iron phosphate is reported for the first time. The LiFePO₄ as cathode material for lithium ion batteries was prepared by a Pechini-assisted reversed polyol process. The coating has been successfully performed on commercially available 3D-carbon foams by soaking in aqueous solution containing lithium, iron salts and phosphates at 70 °C for 2-4 h. After drying-out, the composites were annealed at different temperatures in the range 600-700 °C for 15-20 min under nitrogen. The formation of the olivine-like structured LiFePO₄ was confirmed by X-ray diffraction analysis performed on the powder prepared under similar conditions. The surface investigation of the prepared composites showed the formation of a homogeneous coating by LiFePO₄ on the foams. The cyclic voltammetry curves of the composites show an enhancement of electrode reaction reversibility by decreasing the annealing temperature. The electrochemical measurements on the composites showed good performances delivering a discharge specific capacity of 85 mAh g⁻¹ at a discharging rate of C/25 at room temperature.