Probe based surface modification of polymers below 30 nm pitch.

Heated probes are used to modify the surface of polymeric thin films by thermomechanical indentation and local evaporation of material. The resolution of the processes is discussed for probe-storage and surface patterning-applications. As storage densities exceed 1 Tbit/in2, the depth of the indents becomes comparable to the natural surface roughness of the polymer. By templating an atomically flat surface this limitation can be overcome, enabling storage densities of up to 4 Tbit/in2, corresponding to an indentation half-pitch of 7.5 nm.

Multi Tbit/in(2) storage densities with thermomechanical probes.

Exploiting the spatial resolution of scanning probes presents an attractive approach for novel data storage technologies in particular for large-scale data repositories because of their inherent potential for high storage density. We show that multi-Tbit/in(2) density can be achieved by means of thermomechanically embossing the information as indentation marks into a polymer film. The data density is determined by the nonlinear interaction between closely spaced indents and the fundamental scaling relations governing the shape and size of the indents. We find that cooperative effects in polymers give rise to a minimum indentation radius on the order of the correlation length of the cooperatively rearranged region even if formed by an infinitely sharp indenter. Thus, cooperativity coupled to alpha-transitions in polymers is evinced in a real space geometrical experiment. Furthermore, we predict that indentation marks cannot be made smaller than 5 nm in diameter, which limits the feature resolution for embossing technologies in general.

Relaxation kinetics of nanoscale indents in a polymer glass.

Nanometer scale indents have been written in a cross-linked polystyrene sample, and their relaxation has been studied at annealing temperatures well below the glass transition of the polymer. The indents represent a highly nonequilibrium state of the polymer which is subjected to mechanical stress of up to 0.4 GPa and thermal quench rates on the order of 10{8} K/s during writing. It is shown that the relaxation towards equilibrium evolves logarithmically over more than 10 orders of magnitude in time. The relaxation kinetics are accurately described in terms of a thermally activated process with an energy barrier whose magnitude decreases linearly with the distance from equilibrium.

The heterodimer of the Ca2+-binding proteins MRP8 and MRP14 binds to arachidonic acid.

The S100 proteins MRP8 and MRP14 have been shown to be expressed by myeloid cells during inflammatory reactions. Since the majority of S100 proteins exhibit their biological activity when associated as complex it was investigated whether murine MRP8 and MRP14 form heterodimers and whether this complex may bind lipids of the cell membrane. This is of particular importance since their anchoring into the plasma membrane is unclear although upon calcium binding the proteins translocate from the cytoplasma to the cytoskeleton and the plasma membrane. Using recombinant proteins we could show that not the monomers but only the heterodimers specifically bind arachidonic acid. This finding opens new perspectives for the role of MRP8 and MRP14 in acute and chronic inflammatory processes.

Hydrolyzed feather meal as feed component in diets for rainbow trout (Oncorhynchus mykiss) and effects of dietary protein/energy ratio on the efficiency of utilization of digestible energy and protein.

Two feeding trials were performed on rainbow trout of mean initial weights of 40 and 50 g and lasting for 12 and 14 weeks, respectively. In trial 1, diets contained per kg 300 g fish meal and varying proportions of gelatinized maize starch plus either casein or hydrolyzed feather meal. Dietary crude protein content varied from about 27 to 53%. In trial 2, all diets had about 45% crude protein. Fish meal (300 g/kg) was replaced in 3 steps by hydrolyzed feather meal either without or with supplementation of L- lysine.HCl and/or DL-methionine. In trial 1, efficiency of utilization of digestible energy (DE) rose from 38 to 50% when the ratio digestible crude protein (DCP)/DE was increased from about 11 to 17 g/MJ irrespective of the source of additional DCP, but did not further increase at higher ratios DCP/DE. Efficiency of utilization of DCP was about 50% as long as the ratio DCP/DE did not exceed 17 g/MJ. With progressing replacement of fish meal by hydrolyzed feather meal, efficiencies of utilization of DE as well as of DCP were reduced, the respective rates of reduction being about halved by supplementing lysine with no effect of supplementing methionine.