Coassembly of enantiomeric amphipathic peptides into amyloid-inspired rippled β-sheet fibrils

Amphipathic peptides composed of alternating hydrophobic and hydrophilic amino acids self-assemble into amyloid-inspired, β-sheet nanoribbon fibrils. Herein, we report a new fibril type that is formed from equimolar mixtures of enantiomeric amphipathic peptides (L- and D-(FKFE)(2)). Spectroscopic analysis indicates that these peptides do not self-sort and assemble into enantiomeric fibrils composed of all-l and all-d peptides, but rather coassemble into fibrils that contain alternating L- and D-peptides in a "rippled β-sheet" orientation. Isothermal titration calorimetry indicates an enthalpic advantage for rippled β-sheet coassembly compared to self-sorted β-sheet assembly of enantiomeric peptides.     

The single-mode rate equations for semiconductor lasers with thermal effects

A mathematical model describing the coupling of electrical,optical and thermal effects in semiconductor lasers is introduced.Numerical and asymptotic solutions are derived, including expressionsfor key physical quantities such as the initial time delay,the frequency of spike oscillation and the temperature rise,together with its influence on the photon density, the electronconcentration and the threshold current. The consequences ofthermal effects in reducing efficiency are thus quantified.