Authors:A. Desii, C. Duce, L. Ghezzi, S. Monti, R. Solaro and M. Tiné
The self-aggregation of two short ionic tetrapeptides (RWDW and RVDV, where R = arginine, V = valine, W = tryptophan, D = aspartic acid) was studied by different experimental techniques such as, atomic force microscopy (AFM), light scattering
(LS), isothermal titration calorimetry (ITC) and viscosimetry. AFM was used to investigate the morphology of the aggregates;
the AFM images showed the presence of fibrillar aggregates whose number and length increased with increasing oligopeptides
concentration. On the other hand, the collected experimental calorimetric and physical chemical results consistently indicated
a critical aggregation concentration (cac) around 0.5 and 2.0 mM for RWDW and RVDV respectively.
The eccentricitye(v) of a vertexv of a connected graphG is the maximum distance fromv among the vertices ofG. A nondecreasing sequencea1,a2, ...,ap of nonnegative integers is said to be an eccentric sequence if there exists a connected graphG of orderp whose vertices can be labelledv1,v2, ...,vp so thate(vi)=ai for alli. Several properties of eccentric sequences are exhibited, and a necessary and sufficient condition for a sequence to be eccentric is presented. Sequences which are the eccentricity sequences of trees are characterized. Some properties of the eccentricity sequences of self-complementary graphs are obtained. It is shown that the radius of a nontrivial self-complementary graph is two.
Authors:G. Chartrand, S. F. Kapoor, D. R. Lick and S. Schuster
For a graphG, the switched graphSv(G) ofG at a vertexv is the graph obtained fromG by deleting the edges ofG incident withv and adding the edges of
incident withv. Properties of graphs whereSv(G) ≅G or
are studied. This concept is extended to the partial complementSH(G) where H
. The investigation here centers around the existence of setsH for whichSH(G) ≅ G. A parameter is introduced which measures how near a graph is to being self-complementary.
Authors:M. R. Tiné, M. Alderighi, C. Duce, L. Ghezzi and R. Solaro
Zhang , S , Holmes , TC , Lockshin , C , Rich , A . Spontaneous assembly of a self-complementary oligopeptide to form a stable macroscopic membrane . Proc Natl Acad Sci USA 1993 90 : 3334 – 3338 10.1073/pnas.90