Zukunft braucht Dialog — Dialog braucht Grundlagen

In an open society, visions in the field of power generation can only be realized if accepted by a clear majority of the population. The goal of the ?Preview 95” of the Swiss Association of Electric Power Producers and Distributors (VSE) is to supply facts, alternative solutions and criteria for a dialogue with all groups concerned.     

Solvent control of crack dynamics in a reversible hydrogel

The resistance to fracture of reversible biopolymer hydrogels is an important control factor of the textural characteristics of food gels (such as gummy candies and aspic preparations). It is also critical for their use in tissue engineering, for which mechanical protection of encapsulated components is needed. Its dependence on loading rate and, recently, on the density and strength of crosslinks has been investigated. But, so far, no attention has been paid to solvent or to environment effects. Here we report a systematic study of crack dynamics in gels of gelatin in water/glycerol mixtures. We show in this model system that increasing solvent viscosity slows down cracks; moreover soaking with solvent markedly increases gel fragility; finally tuning the viscosity by adding a miscible liquid affects crack propagation through diffusive invasion of the crack tip vicinity. The results highlight the fact that fracture occurs by viscoplastic chain pull-out. This mechanism, as well as the related phenomenology, should be common to all reversibly crosslinked (physical) gels.     

Structure and activity of platinum–silica catalysts prepared by a combustion process

By combustion of a mixture of silicone oil and chloroplatinic acid and organic solvents, Pt–SiO₂ catalysts with Pt concentrations between 37 and 90% have been prepared and their activity in benzene hydrogenation has been tested in a static system. The special structural characteristics conferred on the catalysts by the combustion method, i.e. small Pt particles with smooth round surfaces well separated by silica, ensure good resistance to de-activation by exposure to elevated temperatures as well as to atmospheres with high humidity at low temperatures.     

Development of early-summer meningoencephalitis (FSME) in the Thurgau region 1990-1995--a new endemic area?

Tick-borne encephalitis (TBE) is a viral infection transmitted by bites of infected ticks. The clinical course is mostly mild, but death occurs in 1-2% of TBE infections and nearly half of patients with meningitis/meningoencephalitis show residual disease, above all chronic headache. TBE-infected ticks occur only in endemic areas. A knowledge of the endemic areas is very important for immunoprophylaxis of TBE. In recent years between 26 and 97 cases of TBE have occurred in Switzerland. The largest endemic areas are in Canton Schaffhausen, the northern part of Canton Zurich and the north-west of Canton Thurgau. Another endemic area is known in the region of Thun in Canton Berne. Another possible endemic area is known in the Zurich Oberland around Elgg, only 7 km from Aadorf in Thurgau. Up to now, Diessenhofen in the north-west of Thurgau was the only known possible endemic area. In 1994 and 1995 we observed an accumulation of TBE infections in western Thurgau. The question was whether there are other endemic areas in Thurgau. In this retrospective analysis we studied the TBE cases in Thurgau between 1990 and 1995 with data derived from the cantonal health authorities reports. Clinical data were taken from case histories of the two cantonal hospitals in Frauenfeld and Münsterlingen, completed by data from family doctors and patients. Between 1990 and 1995 30 TBE infections (1990; 1, 1991: 4, 1992: 3, 1993: 1, 1994: 4 certain, 3 uncertain, 1995: 14) were observed. TBE infections appeared between May and October (maximum in May). 14 patients remembered a bite by a tick several weeks before onset of the illness. 7 bites occurred in the area of Frauenfeld/Aadorf. Only one bite occurred in Diessenhofen. 2 patients were infected in well-known endemic areas in Canton Zurich, a vicinal region in the west of Thurgau. In 1995 the incidence of TBE in Thurgau was 5.4/100000 population. In 9 of the 14 patients recalling a bite by a tick (64.4%), the bites occurred near their domicile. No bite was seen east of a line between Steckborn and Weinfelden. The incidence of TBE in Thurgau in 1995 was clearly higher than the average in Switzerland in recent years (0.46/100000), and higher than in the well-known endemic areas in the vicinity (Schaffhausen 3.95, Zurich 1.31). Based on our data, the region Frauenfeld/Aadorf must be declared a new endemic area for TBE. Probably the well-known endemic area in the Zurich Oberland in the vicinity of Elgg has spread eastward. Persons who are often in the forests of this region should be advised to be vaccinated.     

Creation and control of a two-dimensional electron liquid at the bare SrTiO3 surface

Many-body interactions in transition-metal oxides give rise to a wide range of functional properties, such as high-temperature superconductivity, colossal magnetoresistance or multiferroicity . The seminal recent discovery of a two-dimensional electron gas (2DEG) at the interface of the insulating oxides LaAlO(3) and SrTiO(3) (ref. 4) represents an important milestone towards exploiting such properties in all-oxide devices. This conducting interface shows a number of appealing properties, including a high electron mobility, superconductivity and large magnetoresistance, and can be patterned on the few-nanometre length scale. However, the microscopic origin of the interface 2DEG is poorly understood. Here, we show that a similar 2DEG, with an electron density as large as 8×10(13) cm(-2), can be formed at the bare SrTiO(3) surface. Furthermore, we find that the 2DEG density can be controlled through exposure of the surface to intense ultraviolet light. Subsequent angle-resolved photoemission spectroscopy measurements reveal an unusual coexistence of a light quasiparticle mass and signatures of strong many-body interactions.     

An In Vivo Definition of Brain Histamine Dynamics Reveals Critical Neuromodulatory Roles for This Elusive Messenger

Histamine is well known for mediating peripheral inflammation; however, this amine is also found in high concentrations in the brain where its roles are much less known. In vivo chemical dynamics are difficult to measure, thus fundamental aspects of histamine’s neurochemistry remain undefined. In this work, we undertake the first in-depth characterization of real time in vivo histamine dynamics using fast electrochemical tools. We find that histamine release is sensitive to pharmacological manipulation at the level of synthesis, packaging, autoreceptors and metabolism. We find two breakthrough aspects of histamine modulation. First, differences in H3 receptor regulation between sexes show that histamine release in female mice is much more tightly regulated than in male mice under H3 or inflammatory drug challenge. We hypothesize that this finding may contribute to hormone-mediated neuroprotection mechanisms in female mice. Second, a high dose of a commonly available antihistamine, the H1 receptor inverse agonist diphenhydramine, rapidly decreases serotonin levels. This finding highlights the sheer significance of pharmaceuticals on neuromodulation. Our study opens the path to better understanding and treating histamine related disorders of the brain (such as neuroinflammation), emphasizing that sex and modulation (of serotonin) are critical factors to consider when studying/designing new histamine targeting therapeutics.     

Treatment of wood fibres with laccases: improved hardboard properties through phenolic oligomerization

European Journal of Wood and Wood Products - Laccase-treated wood fibres were tested for small-scale wet-process manufacture of hardboards. Two laccases of distinct redox potentials, one from...