Reaktive membrancopolymere auf acrylbasis

The copolymerization of acrylonitrile with maleic anhydride was investigated to synthesize acylic reactive polymers for manufacture of membranes that serve as support for covalent enzyme immobilization. The free-radical copolymer synthesis was carried out in solution (N,N-dimethylformamide (DMF), dimethylacetamide (DMAC), γ-butyrolactone, ethylene carbonate), by precipitation polymerization (dioxane) as well as bulk polymerization. The polymers were characterized using IR spectroscopy, elementary analysis, NMR spectroscopy, gel permeation chromatography, viscosity measurements, osmometry and potentiometry. The kinetic parameters were followed by dilatometric measurements up to high conversions. The anhydride content in the monomer mixtures showed a significant influence on the rate of polymerization and the molecular weight. With raised concentration of anhydride the polymerization rate and molecular weights decreased. Film forming polymers (M̄_η > 30 000 g/mol) can be obtained by all copolymerization procedures with exception of solution polymerization in DMF and DMAC, respectively. The content of maleic anhydride in the membrane polymers did not exceed 5 mol-%, even though the maleic anhydride content in the monomer mixtures was raised up to the equimolar mixture. Nevertheless, such low maleic anhydride content of prepared membranes is enough for successful enzyme immobilization with amyloglucosidase (copolymer was prepared in γ-butyrolactone, M̄_η = 49 000 g/mol, c = 0,3 mol-%).     

Sydnon-äthylene. II. Elektronische Wechselwirkungen in 4-Styryl-sydnonen

Sydnone Ethylenes. II. Electronic Interactions in 4-Styryl-sydnones An estimation of intramolecular donor/acceptor interactions in 4-styryl-sydnones can be made by the substituent increments Z_trans derived from the corresponding vinyl compounds and by the comparison of the u.v.-spectra of ω(E)-substituted styrols. Because of the different anisotropic effects of sydnone and aryl groups the chemical shifts of the ethylene protons are not suitable for this purpose. The observed and calculated u.v.-spectra show that the electronic excitation of 4-styryl-sydnones causes a strengthening of the sydnone donor effect and a decrease of the bond-order in the CC-region.     

Passive Submillimeter-wave Stand-off Video Camera for Security Applications

We present the concept and experimental set-up of a passive submillimeter-wave stand-off imaging system for security applications. Our ambition is the design of an application-ready and user-friendly camera providing high sensitivity and high spatial resolution at video frame rates. As an intermediate step towards this goal, the current prototype already achieves a frame rate of 10 frames per second and a spatial resolution below 2 cm at 8 m distance. The camera is the result of a continuous development and a unique concept that yielded first high-resolution passive submillimeter-wave images provided by cryogenic sensors in May et al. (2007). It is based on an array of 20 superconducting transition-edge sensors operated at a temperature of 450 mK, a closed-cycle cooling system, a Cassegrain-type optics with a 50 cm main mirror, and an opto-mechanical scanner. Its outstanding features are the scanning solution allowing for high frame rates and the compact and integrated system design.     

Zur mechanischen Aufbereitung von Li-Ionen-Batterien

In the last four years Technical University Freiberg/Sachsen has developed a process for the mechanical recycling of Li-ion batteries from electric vehicles. After solving some safety-relevant issues (dismantling and discharging) the process offers an alternative or addition to existing energy-intensive pyro- and hydrometallurgical processes. Robustness of the process was verified for several battery types of divergent material compositions. The process capability was verified also for Li-ion starter batteries, provided that relevant parameters were adjusted. A pilot-plant is in planning.     

The capture and dissemination of integrated 3D geospatial knowledge at the British Geological Survey using GSI3D software and methodology

The Geological Surveying and Investigation in 3 Dimensions (GSI3D) software tool and methodology has been developed over the last 15 years. Since 2001 this has been in cooperation with the British Geological Survey (BGS). To-date over a hundred BGS geologists have learned to use the software that is now routinely deployed in building systematic and commercial 3D geological models. The success of the GSI3D methodology and software is based on its intuitive design and the fact that it utilises exactly the same data and methods, albeit in digital forms, that geologists have been using for two centuries in order to make geological maps and cross-sections. The geologist constructs models based on a career of observation of geological phenomena, thereby incorporating tacit knowledge into the model. This knowledge capture is a key element to the GSI3D approach. In BGS GSI3D is part of a much wider set of systems and work processes that together make up the cyberinfrastructure of a modern geological survey. The GSI3D software is not yet designed to cope with bedrock structures in which individual stratigraphic surfaces are repeated or inverted, but the software is currently being extended by BGS to encompass these more complex geological scenarios. A further challenge for BGS is to enable its 3D geological models to become part of the semantic Web using GML application schema like GeoSciML. The biggest benefits of widely available systematic geological models will be an enhanced public understanding of the sub-surface in 3D, and the teaching of geoscience students.     

FT-IR spectroscopic investigations of photochemical grafting of amphiphiles onto polyacrylonitrile surfaces

The photoreactive amphiphile p-(stearyl amido) benzoyl azide (SABAz) was synthesized and grafted onto surface of thin polyacrylonitrile (PAN) films by irradiation with UV light. Two different techniques were applied, namely, Langmuir–Blodgett (LB) deposition and casting from solution. A high degree of order and a hydrophobic surface were established by reflection-absorption FT-IR spectroscopy (RA-IR) and contact angle measurements. The stability against treatment with water, tetrahydrofuran, and chloroform was tested. A considerable amount of amphiphilic molecules remains on the surface also after treatment with chloroform. RA-IR spectra taken from photomodified PAN films prepared by both techniques are almost identical after chloroform treatment, indicating a similar coupling mechanism. © 1995 John Wiley & Sons, Inc.     

Adsorption and catalytic reactions of NO and NH3 on activated carbon

In industrial processes, the reduction of nitrogen oxides by ammonia on activated carbons is carried out at temperatures between 90 and 190 °C. Adsorption of NO and NH₃ on the catalyst was investigated separately. Reactions models for NO-reduction by carbon and ammonia were derived from experiments carried out in an integral reactor. In each case, the formation of an adsorbed (NO₂)-complex is an important step. The kinetics of both reactions was described by modified Langmuir-Hinshelwood equations.