Thermal effects and dynamical hysteresis in the turn-on and turn-off of vertical-cavity surface-emitting lasers

Thermal effects and dynamical hysteresis in VCSELs under dc modulation have been experimentally studied. The results show that the VCSEL turn-on and turn-off currents can display both positive hysteresis and negative hysteresis, depending on the current modulation frequency and on the substrate temperature. Numerical simulations of semiconductor laser rate equations, extended to take into account thermal effects, show a good agreement with the observations.     

Through the eye of an electrospray needle: mass spectrometric identification of the major peptides and proteins in the milk of the one‐humped camel (Camelus dromedarius)

The milk of the one‐humped camel (Camelus dromedarius) reportedly offers medicinal benefits, perhaps because of its unique bioactive components. Milk proteins were determined by (1) two‐dimensional gel electrophoresis and peptide mass mapping and (2) liquid chromatography–tandem mass spectrometry (LC–MS/MS) following one‐dimensional polyacrylamide gel electrophoresis. Over 200 proteins were identified: some known camel proteins including heavy‐chain immunoglobulins and others exhibiting regions of exact homology with proteins from other species. Indigenous peptides were also identified following isolation and concentration by two strategies: (1) gel‐eluted liquid fraction entrapment electrophoresis and (2) small‐scale electrophoretic separation. Extracts were analyzed by LC–MS/MS and peptides identified by matching strategies, by de novo sequencing and by applying a sequence tag tool requiring similarity to the proposed sequence, but not an exact match. A plethora of protein cleavage products including some novel peptides were characterized. These studies demonstrate that camel milk is a rich source of peptides, some of which may serve as nutraceuticals. Copyright © 2013 John Wiley & Sons, Ltd.