On Gaps in the Energy Spectrum of a Three Particle Reaction

The paper deals with (nuclear) reactions with three particles in the exit channel. When a sequential decay takes place the energy spectrum (laboratory system) of a particle, being emitted in the second step of the decay, may contain an interval that is kinematically forbidden.     

Fischmehl

Ohne Zusammenfassung     

Biological Activities of Violacein, a New Antitumoral Indole Derivative, in an Inclusion Complex with β-Cyclodextrin

Violacein is a poorly water-soluble antitumoraland antibacterial drug. The solubility can be enhanced by complexation with-cyclodextrin. The inclusion complex was prepared by the co-precipitation method in molarratios of 1 : 1 and 1 : 2 of violacein/-cyclodextrin, respectively. The acutetoxicity (E. coli strain) of violacein did not changeup to 400 M, either in thepresence or absence of cyclodextrin. Cytotoxicity (V-79 cellculture) through DNA and MTT assays was significantlydecreased in the presence of the 1 : 2 molar ratio complex.Studies on erythrocyte lipid peroxidation by the thiobarbituricacid (TBA) methodshowed that violacein and violacein/-CD (1 : 2) at100 M cause 50% and 80% inhibition, respectively. At 500 M theviolacein/-CD complexinhibited lipid peroxidation completely; however, withfree violacein only 65% inhibition was reached at that concentration.     

Influence of temperature on peak shape and solvent compatibility: implications for two-dimensional liquid chromatography

Solvent compatibility is a limiting factor for the success of two-dimensional liquid chromatography (2-D LC). In the second dimension, solvent effects can result in overpressures as well as in peak broadening or even distortion. A peak shape study was performed on a one-dimensional high-performance liquid chromatography (HPLC) system to simulate the impact of peak distorting solvent effects on a reversed-phase second dimension separation operated at high temperatures. This study includes changes in injection volume, solute concentration, column inner diameter, eluent composition and oven temperature. Special attention was given to the influence of high temperatures on the solvent effects. High-temperature HPLC (HT-HPLC) is known to enhance second dimension separations in terms of speed, selectivity and solvent compatibility. The ability to minimise the viscosity contrast between the mobile phases of both dimensions makes HT-HPLC a promising tool to avoid viscosity mismatch effects like (pre-)viscous fingering. In case of our study, viscosity mismatch effects could not be observed. However, our results clearly show that the enhancement in solvent compatibility provided by the application of high temperatures does not include the elimination of solvent strength effects. The additional peak broadening and distortion caused by this effect is a potential error source for data processing in 2-D LC.     

Using engineered single-chain antibodies to correlate molecular binding properties and nanoparticle adhesion dynamics

Elucidation of the relationship between targeting molecule binding properties and the adhesive behavior of therapeutic or diagnostic nanocarriers would aid in the design of optimized vectors and lead to improved efficacy. We measured the adhesion of 200-nm-diameter particles under fluid flow that was mediated by a diverse array of molecular interactions, including recombinant single-chain antibodies (scFvs), full antibodies, and the avidin/biotin interaction. Within the panel of scFvs, we used a family of mutants that display a spectrum of binding kinetics, allowing us to compare nanoparticle adhesion to bond chemistry. In addition, we explored the effect of molecular size by inserting a protein linker into the scFv fusion construct and by employing scFvs that are specific for targets with vastly different sizes. Using computational models, we extracted multivalent kinetic rate constants for particle attachment and detachment from the adhesion data and correlated the results to molecular binding properties. Our results indicate that the factors that increase encounter probability, such as adhesion molecule valency and size, directly enhance the rate of nanoparticle attachment. Bond kinetics had no influence on scFv-mediated nanoparticle attachment within the kinetic range tested, however, but did appear to affect antibody/antigen and avidin/biotin mediated adhesion. We attribute this finding to a combination of multivalent binding and differences in bond mechanical strength between recombinant scFvs and the other adhesion molecules. Nanoparticle detachment probability correlated directly with adhesion molecule valency and size, as well as the logarithm of the affinity for all molecules tested. On the basis of this work, scFvs can serve as viable targeting receptors for nanoparticles, but improvements to their bond mechanical strength would likely be required to fully exploit their tunable kinetic properties and maximize the adhesion efficiency of nanoparticles that bear them.     

Binding of riboflavin to lysozyme promoted by peroxidase-generated triplet acetone

When riboflavin and lysozyme are added to the 2-methylpropanal/peroxidase/O₂ system, which generates triplet acetone, an adduct is formed to a small extent. The adduct can be separated by gel filtration and is similar to that prepared by irradiating riboflavin in the presence of lysozyme.