Strain-Compensated InGaAsP Superlattices for Defect Reduction of InP Grown on Exact-Oriented (001) Patterned Si Substrates by Metal Organic Chemical Vapor Deposition.

We report on the use of InGaAsP strain-compensated superlattices (SC-SLs) as a technique to reduce the defect density of Indium Phosphide (InP) grown on silicon (InP-on-Si) by Metal Organic Chemical Vapor Deposition (MOCVD). Initially, a 2 μm thick gallium arsenide (GaAs) layer was grown with very high uniformity on exact oriented (001) 300 mm Si wafers; which had been patterned in 90 nm V-grooved trenches separated by silicon dioxide (SiO₂) stripes and oriented along the [110] direction. Undercut at the Si/SiO₂ interface was used to reduce the propagation of defects into the III-V layers.

Ridge-width dependence of the threshold of long wavelength (λ ≈ 14 µm) Quantum Cascade lasers with sloped and vertical sidewalls.

We investigate the ridge-width dependence of the threshold of Quantum Cascade lasers fabricated by wet and dry etching, respectively. The sloped sidewalls resulting from wet etching affect the threshold in two ways as the ridge gets narrower. First, the transverse modes are deeper in the substrate, hence reducing the optical confinement factor.

Enhanced bandwidth and reduced dispersion through stacking multiple optical metamaterials.

All-semiconductor, highly anisotropic metamaterials provide a straightforward path to negative refraction in the mid-infrared. However, their usefulness in applications is restricted by strong frequency dispersion and limited spectral bandwidth. In this work, we show that by stacking multiple metamaterials of varying thickness and doping into one compound metamaterial, bandwidth is increased by 27% over a single-stack metamaterial, and dispersion is reduced.

Temperature-insensitive long-wavelength (λ ≈14 µm) Quantum Cascade lasers with low threshold.

We demonstrate high-performance, long-wavelength (λ ≈14 µm) Quantum Cascade (QC) lasers based on a diagonal optical transition and a "two-phonon-continuum" depletion scheme in which the lower laser level is depopulated by resonant longitudinal optical phonon scattering followed by scattering to a lower energy level continuum. A 2.8 mm long QC laser shows a low threshold current density of 2.

Reduced expression of TGF beta1RII in agnogenic myeloid metaplasia is not due to mutation or methylation.

Agnogenic myeloid metaplasia (AMM) is characterized by bone marrow fibrosis and enhanced proliferation of megakaryocytes and CD34+ cells. We have analyzed the factors that could lead to reduced expression of TGF beta1RII in CD34+ cells of AMM patients. Our results demonstrate absence of mutations in the coding region and the promoter of this gene and absence of CpG methylation of its promoter in AMM patients.

Osteosclerosis in idiopathic myelofibrosis is related to the overproduction of osteoprotegerin (OPG).

Objective: The aim of this study is to investigate the mechanism of osteosclerosis in IMF in relation to OPG derangement.

Methods: Plasma OPG level was assayed by OPG ELISA in 19 patients with IMF, 15 patients with other myeloproliferative disorders (MPDs), and 12 normal volunteers as controls and correlated with the degree of osteosclerosis. Furthermore, the level of OPG mRNA, in the cultured bone marrow stromal (BMS) cells of patients with IMF and anemia patients used as controls, in the presence or absence of TGF-beta1, was studied by real-time RT-PCR.