Chinongruppenhaltige Polymere als Träger zur Immobilisierung von Enzymen

Crosslinked poly(4-styrenesulfonic acid chloride) was reacted with 3-amino-4-hydroxyphenyl benzoate to give a reactive carrier after saponification and oxidation. Its binding ability was tested with α-chymotrypsin. The binding ability as well as the enzyme activity could be increased by introduction of spacers, e.g. ethylenediamine and hexamethylenediamine between the poly(styrene)-matrix and p-benzoquinone. Also crosslinked poly(vinyl alcohol) was reacted with p-benzoquinone to give a reactive carrier, which could also immobilize α-chymotrypsin. Some properties of the immobilized α-chymotrypsin as activity, pH-optimum and storage stability were investigated.     

Large‐Scale Diffusion Barriers from CVD Grown Graphene

Graphene has been long thought of as a perfect barrier material due to its impermeability to all gases as well as mechanical and chemical durability. Moreover, graphene layers are transparent and conductive, significantly widening the field of potential applications beyond simple barrier coatings. However, it is very challenging to realize such barriers on a macro­scopic scale as immaculate large area films are not available. In this work, a highly effective oxygen gas barrier made from multiple layers of chemical vapor deposited graphene is presented. The individual graphene layers are stacked using a modified polymer‐assisted transfer method, avoiding polymer residue yielding an oxygen‐tight arrangement. A stack of three layers of graphene transmitted 6.9 cm³ m⁻² d⁻¹ of O₂ which corresponds to 1.10 × 10⁻¹⁷ cm³ cm/cm² s (cm Hg) when normalized to thickness and pressure. This is several orders of magnitude better than any macroscale graphene coating reported to date and performs on a level that can compete with most modern coatings while being much thinner and conductive.     

Production of Strong Steel‐Aluminum Composites by Formation of Intermetallic Phases in Compound Forging

In times of increasing energy costs automotive light weight construction is gaining more importance. The production of hybrid compounds by forging is a promising method to successfully manufacture functional parts by applying resource‐saving process steps. However, in compound forging of steel‐aluminum parts shrinking gaps may form because of the different thermal expansion coefficients. To avoid these unwanted gaps, it is necessary to achieve a firmly bonded joint e.g. by intermetallic phases. This paper deals with the investigation of the influences of different sample preparations, process parameters and true strains on the formation of intermetallic phases. Thus, the optimum production parameters for compound forging of steel‐aluminum parts will be determined.     

Plasma Jet Machining

Plasma Jet Machining (PJM) is a surface figuring technology based on atmospheric plasma assisted chemical etching or deposition, respectively. In both cases a sub‐aperture plasma jet source is used combined with a CNC multi‐axes system for the processing of curved surfaces. It is under development for the surface figuring of a variety of optical materials by IOM for about 15 years. PJM is capable to figure deep aspheric or free‐form substrates with high material removal rate and high spatial resolution. Based on chemical reactions between plasma generated radicals and the surface PJM does not introduce any damage to the processed surface and sub‐surface region in contrast to abrasive techniques. Deterministic deposition of SiO_x layers and subsequent proportional transfer using ion beams or polishing is another plasma jet based technique for surface figuring that extends the range of machinable materials. The article gives an overview on the current state of PJM development in IOM and shows examples of its application.