Effective phonon bottleneck in the carrier thermalization of InAs/GaAs quantum dots

We present a detailed study of the dependence of the spectral characteristics of quasiresonantly excited InAs/GaAs quantum dots on electronic structure, temperature, and hydrogen content. Multiphonon resonances dominate the resonantly excited emission spectra. Such multiphonon resonances are attributed to the competition between two different channels ruling carrier thermalization in an ensemble of quantum dots: decay between polaronic states and efficient nonradiative intradot decay. This supports an effective "phonon bottleneck" in quantum dots, which is only partially relaxed by the presence of a fast polaron thermalization channel

Factor H interferes with the adhesion of sickle red cells to vascular endothelium : a novel disease-modulating molecule

Sickle cell disease is an autosomal recessive genetic red cell disorder with a worldwide distribution. Growing evidence suggests a possible involvement of complement activation in the severity of clinical complications of sickle cell disease. In this study we found activation of the alternative complement pathway with microvascular deposition of C5b-9 on skin biopsies from patients with sickle cell disease. There was also deposition of C3b on sickle red cell membranes, which is promoted locally by the exposure of phosphatidylserine. In addition, we showed for the first time a peculiar "stop-and-go" motion of sickle cell red blood cells on tumor factor-alpha-activated vascular endothelial surfaces. Using the C3b/iC3b binding plasma protein factor H as an inhibitor of C3b cell-cell interactions, we found that factor H and its domains 19-20 prevent the adhesion of sickle red cells to the endothelium, normalizing speed transition times of red cells. We documented that factor H acts by preventing the adhesion of sickle red cells to P-selectin and/or the Mac-1 receptor (CD11b/CD18), supporting the activation of the alternative pathway of complement as an additional mechanism in the pathogenesis of acute sickle cell related vaso-occlusive crises. Our data provide a rationale for further investigation of the potential contribution of factor H and other modulators of the alternative complement pathway with potential implications for the treatment of sickle cell disease.Peer reviewe