Multiblock copolymers as polymeric surfactants: are “pancakes” better than “dumbbells”?

It is suggested that multiblock copolymers which form a pancake at the interface between two incompatible homopolymers would be more efficient as compatibilizers than di- or triblock copolymers. Less of the multiblock copolymers would be lost into the bulk phases as micelles or mesophases than di- or triblock copolymers if some degree of irregularity is included in the multiblock architecture, either in block length or chemical sequence distribution, without compromising the thermodynamic driving forces which localize the copolymers at the interface. This molecular design strategy is aimed at reducing the ability of the surfactant to form a separate phase, thereby increasing the interfacial activity in a nonequilibrium system with a large interfacial area. The multiblock loops which would preferentially orient into the most compatible homopolymer phases would have to exceed a certain critical size in order to avoid the entropic penalty of having an extremely flat pancake, and to provide good adhesion between the bulk phases.     

Is There a “Most Chiral Tetrahedron”?

A degree of chirality is a function that purports to measure the amount of chirality of an object: it is equal for enantiomers, vanishes only for achiral or degenerate objects and is similarity invariant, dimensionless and normalisable to the interval [0,1]. For a tetrahedron of non-zero three-dimensional volume, achirality is synonymous with the presence of a mirror plane containing one edge and bisecting its opposite, and hence it is easy to design degree-of-chirality functions based on edge length that incorporate all constraints. It is shown that such functions can have largest maxima at widely different points in the tetrahedral shape space, and by incorporation of appropriate factors, the maxima can be pushed to any point in the space. Thus the phrase "most chiral tetrahedron" has no general meaning: any chiral tetrahedron is the most chiral for some legitimate choice of degree of chirality.     

“What is KRI?” – R&D based on excellent tradition and innovation –

As far as KRI's clients were concerned, KRI's appeal was not only in having researchers who had a high level of expert knowledge, but it was also in the efficiency with which high risk jobs were conducted, and the speed of response time, especially when corporations made comparisons with their own in‐house labs. KRI, while being a facility for contract research, is also capable of becoming a profitable corporation, mostly thanks to the adoption of this system. KRI sincerely hopes to continue serving as a group made up of quality professionals who embrace a dream, and to contribute to society through its achievements. At the same time, the company strives to be sensitive to changing needs, and, of course, to conduct R&D and consulting activities which will ensure success for its clients.     

Resolution of Racemates: Did You Say “Classical”?

A successful “family approach” is already being used in industry for large-scale enantiomeric resolutions. In this method, racemates are resolved by formation of salts with mixtures of three structurally related resolving agents instead of a single one. Although the physical chemistry behind this is still largely unexplored, successful resolution is more likely and resolution efficiency is often improved over that of classical resolution.     

Sialyl Lewisx: A “Pre‐Organized Water Oligomer”?

Organized and released: Sialyl Lewis(x) (sLe(x)) represents a "pre-organized water oligomer", that is, a surrogate for clustered water molecules attached to a scaffold. The impetus for sLe(x) binding to E-selectin is shown to be the high degree of pre-organization allowing an array of directed hydrogen bonds, and the entropic benefit of the release of water molecules from the large binding interface to bulk water (see picture).