Verbesserung des Vakuums in Isoliergefäßen aus Glas

Improving the vacuum would increase the insulation capacity of commercially available glass containers by a factor of about two. To do this, pressures of 10^?4 mbar must be attained. Different approaches were taken to meet this objective. As an alternative to today's commonly practiced sealing method, three possibilities are introduced which eliminate the necessity of pump stub narrowing which causes reduced conductance. Furthermore, depending on the sealing process used, the gases occuring during sealing are either avoided completly or they can at least be reduced by having the chance of exact temperature control resp. by a lower separation temperature. A completly different approach was taken by using Getters, of which a metal hydride on a TiVMn base proved especially suitable. It is activated by heat and can be integrated into the normal production process without any problem. Aside from a shorter pump period, the added advantage here is the containment of the gasses occuring during sealing as well as that of the longterm gasses.     

Selbstbestimmung

Ohne Zusammenfassung     

Anwendung von statistischen Prüfverfahren im Bereich der Mischtechnik

Application of statistical testing to mixing. Assessment of the homogeneity of mixtures of solids and determination of the necessary mixing times are performed with the aid of statistical testing methods. The results from the basis for necessary decisions. Since reliable statements are fundamentally impossible in mathematical statistics, all such decisions are, with a certain probability, false, i.e. involve some risk. In studies of mixing, the first kind of error concerns the risk of rejecting a mixture although its homogeneity satisfies requirements, while the second kind of error concerns the risk of accepting a mixture although its homogeneity is insufficient. It is shown that barriers can be introduced for both kinds of error, and how to do this. Both the sample size and the limits of the acceptance range for the sample variance are thus laid down. If no decision is to be made concerning acceptance or rejection of a given mixture, but information is merely required about the mixing quality after a given time then this is accomplished by statement of confidence intervals.     

Impacts of new technologies on media usage and social behaviour in domestic environments

Technological infrastructure at home is changing continuously and is becoming increasingly interconnected. Media devices, including the TV set, provide access to the Internet and offer manifold opportunities to consume media on demand. Additionally, personal devices, such as smartphones, also enable flexible consumption and sharing of media. Questions about how these technologies change the user's media usage and how these changes affect the social structure of a household, however, remain largely unanswered. In order to gain insight into the adoption of new technologies into daily routines, we explored these changes in respect of people's media usage in a qualitative long-term Living Lab study. We will present findings regarding personal routines, flexible integration of new devices into existing practices, influences on households as social systems and related issues in device access and collective use. We will highlight potentials and conflicts regarding device shifts and roles; restrictions in device access; social influences in the living room; and individual changes in media consumption.     

Microenvironmental engineering: An effective strategy for tailoring enzymatic activities

Rationally, engineering a favorable physicochemical microenvironment for enzymes has recently emerged as an effective strategy to improve their catalytic performance. In this review, we discuss four microenvironmental effects according to the mechanism of action: localizing and excluding reactants and regulators, regulating microenvironmental pH, creating a water-like microenvironment, and increasing the local temperature. These mechanisms are enzyme-independent and can in principle be used in combination to tailor enzyme behaviors, offering new approaches to enabling, enhancing, and regulating enzyme catalysis in diverse applications without the need for genetic engineering.     

Pyrolysis of random and block copolymers of ethyl acrylate and methyl methacrylate

Pyrolysis gas chromatography can distinguish random from block copolymers of ethylacrylate and methyl methacrylate. The pyrograms depend on the pyrolytic temperature, the ratio of copolymerized monomers, the degree of conversion, and the method of polymerization. Larger amounts of ethyl methacrylate and methyl acrylate are formed on pyrolysis of random copolymers than of block copolymers. The presence of mixed dimers indicates random copolymerization. The sum of the percent recovery of ethyl alcohol and ethyl acrylate is fairly constant over a range of compositions and monomer sequence. Random copolymers produce less ethyl alcohol than ethyl acrylate on pyrolysis, while homopolymers and block copolymers produce more ethyl alcohol and less ethyl acrylate. In a set of random copolymers with different EA/MMA ratios, there is an increasing per cent recovery of EA monomer with decreasing EA in the copolymer, while ethyl alcohol shows the opposite behavior. The characteristic degradation patterns are thought to be governed by the availability of the tertiary hydrogen for abstraction by the alkoxy oxygen of a neighboring acrylate unit, the availability depending on the sequence distribution of acrylate/methacrylate molecules.