Catalytic templated length-controlled oligomerization.

Templated synthesis is an intriguing strategy for the length-controlled synthesis of oligomers. Traditionally, such reactions require stoichiometric amounts of the template with respect to the product. Recently we reported catalytic macrocyclic templates that promote oligomerization of a small molecule substrate with a remarkable degree of length control. Herein we present our efforts toward creating linear templates for catalytic length-controlled oligomer synthesis.

Targeting a Large Active Site: Structure-Based Design of Nanomolar Inhibitors of Trypanosoma brucei Trypanothione Reductase.

Trypanothione reductase (TR) plays a key role in the unique redox metabolism of trypanosomatids, the causative agents of human African trypanosomiasis (HAT), Chagas' disease, and leishmaniases. Introduction of a new, lean propargylic vector to a known class of TR inhibitors resulted in the strongest reported competitive inhibitor of Trypanosoma (T.) brucei TR, with an inhibition constant Ki of 73 nm, which is fully selective against human glutathione reductase (hGR). The best ligands exhibited in vitro IC50 values (half-maximal inhibitory concentration) against the HAT pathogen, T. brucei rhodesiense, in the mid-nanomolar range, reaching down to 50 nm. X-Ray co-crystal structures confirmed the binding mode of the ligands and revealed the presence of a HEPES buffer molecule in the large active site. Extension of the propargylic vector, guided by structure-based design, to replace the HEPES buffer molecule should give inhibitors with low nanomolar Ki and IC50 values for in vivo studies.

Effect of Roller Levelling on Tensile Properties of Aluminum Sheets.

The straightening of sheets, bars and profiles plays an important role in many machining processes. The aim of sheet straightening in the rolling mill is to ensure that the deviation of sheets from flatness is within the tolerances specified in the standards or delivery conditions. There is a wide range of information available on the roller levelling process used to meet these quality requirements. However, little attention has been paid to the effects of levelling, namely the change in properties of the sheets before and after roller levelling. The aim of the present publication is to investigate how the levelling process affects tensile test results. The experiments have shown that levelling increases the yield strength of the sheet by 14-18%, while it decreases its elongation by 1-3% and hardening exponent by 15%. The mechanical model developed allows changes to be predicted, so that a plan can be made regarding roller levelling technology that has the least effect on the properties of the sheet while maintaining the desired dimensional accuracy.