Down-hill varicose veins in struma permagna and unilateral hypoplasia of the internal jugular vein]

A barium oesophagogram of a 69-year old woman suffering from dyspnoea, episodes of suffocation and dysphagea because of massive struma, showed multiple uniform nodular filling defects in the upper oesophageal relief corresponding to downhill varices. In CT scan and MRT additionally a pathogenetic relevant hypoplasia of the right internal jugular vein was evident.     

Real-time stress evolution during Si1-xGex Heteroepitaxy: Dislocations, islanding, and segregation

We have used sensitive real-time measurements of film stress during Si_1-xGe_x molecular beam epitaxy to examine strain relaxation due to coherent island formation, and to probe the kinetics of Ge surface segregation. We first describe our novel curvature-measurement technique for real-time stress determination. Measurements of the relaxation kinetics during high temperature Si₇₉Ge₂₁ growth on Si (001) are reported in which formation of highly regular arrays of [501]-faceted islands produce 20% stress relaxation. An island shape transition is also observed that reduces the effective stress by up to 50% without dislocations. Nonuniform composition profiles due to Ge surface segregation during growth of planar alloy films are determined with submonolayer thickness resolution from the real-time stress evolution. Up to two monolayers of Ge can segregate to the growth surface.     

Schlagzähes Polystyrol mit Polyolefinen als Elastomerphase

Modification of polystyrene with certain polyolefins results in product of impact strength if some theoretically derived conditions are fulfilled. With low density polyethylene as soft phase it is demonstrated, how the modification can be reached purpously by grafting, achieving a proper morphology and partial crosslinking. The impact properties of the thus synthesized products generally prove the correctness of the theory. The temperature dependence of the properties gives further insight in the mechanism by which the disperse soft phase effects impact strength. Compared to usual rubbers, polyolefins as soft phase have the advantage of high weatherability, which is also true for ethylene-propylene-terpolymers (EPDM). In the system polystyrene-EPDM optimal modification according to the principles mentioned above results in high weatherability as well as improved impact and tensile properties.     

Selective Sampling Using the Query by Committee Algorithm

We analyze the query by committee algorithm, a method for filtering informative queries from a random stream of inputs. We show that if the two-member committee algorithm achieves information gain with positive lower bound, then the prediction error decreases exponentially with the number of queries. We show that, in particular, this exponential decrease holds for query learning of perceptrons.     

Acetylene and Ethylene Hydrogenation on Alumina Supported Pd-Ag Model Catalysts

Adsorption and co-adsorption of ethylene, acetylene and hydrogen on Pd-Ag particles, supported on thin alumina films, have been studied by temperature programmed desorption (TPD). The TPD results show that adding of Ag to Pd suppresses overall hydrogenation activity but increases selectivity towards ethylene, i.e. similar to that observed on real catalysts. The results are rationalized on the basis of a complex interplay between surface and subsurface hydrogen species available in the system, whereby the latter species are the most critical for total hydrogenation of acetylene to ethane.     

Ubiquitin binds to a short peptide segment of hydrolase UCH-L3: a study by FCS, RIfS, ITC and NMR

Screening for small peptidic affinity tags for the detection of ubiquitin and ubiquitinated proteins yielded the dodecapeptide amide DPDELRFNAIAL-NH(2) as a specific ubiquitin-interacting ligand. A peptide collection--based on crystal structures with ubiquitin-interacting proteins--was designed and confirmed by sequence comparison of ubiquitin-interacting motifs. Four independent physical detection methods demonstrated that the peptide binds to monomeric ubiquitin with an affinity of about 10 muM and with fast on and off rates. Fluorescence correlation spectroscopy with fluorescent peptides showed specific interaction with ubiquitin. Reflectometric interference spectroscopy with surface-immobilized peptides and isothermal calorimetry measurements confirmed the specific binding of ubiquitin and fast rate constants. (1)H,(15)N heteronuclear NMR localised the interaction site across the beta sheet of ubiquitin. The peptide aligns well with the ubiquitin-interacting motif and represents a lead structure for the rational design of high-affinity tags for targeting ubiquitinated protein in vitro and in vivo.