Light emitting porous silicon diode based on silicon/porous silicon heterojunction

A new structure is proposed to improve the external quantum efficiency of porous silicon (PS) light emitting diodes (LED). It is based on a heterojunction between n-type doped silicon and PS. The heterojunction is formed due to the doping selectivity of the etching process used to form PS. The improvement of the proposed LED structure with respect to usual metal/PS LED is demonstrated. This is thought to be due to a different injection mechanism for which carriers are injected directly into conduction band states. Anodic oxidation experiments show further improvements in the LED efficiency. (C) 1999 American Institute of Physics. [S0021-8979(99)07123-6]

Effects of granulocyte-macrophage colony-stimulating factor on small cell lung cancer cells

Nonhematopoietic malignant cells may express receptors for hematopoietic growth factors and respond to these peptides. The aim of the present study was to investigate whether small cell lung cancer (SCLC) cells may be stimulated to proliferate by hematopoietic growth factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3), which are currently used in clinical trials in combination with cytotoxic chemotherapy. We studied two SCLC cell lines, H69 and N417. The effects of GM-CSF and IL-3 were evaluated by studying clonal growth, 3H-thymidine incorporation, BUDR/DNA bivariate flow cytometry, c-myc and N-myc oncogene expression, and myeloid surface markers. Our experiments show that both GM-CSF and IL-3 can increase 3H-thymidine incorporation and cloning efficiency and reduce DNA synthesis time of H69 and, to a lesser extent, N417 cells, supporting the hypothesis that hematopoietic growth factors can stimulate the growth of some malignant nonhematopoietic cells in vitro. Further in vitro and in vivo studies are needed to determine whether clinical trials applying these factors for bone marrow recovery after chemotherapy of solid tumors may be hazardous by potentially stimulating growth of remaining tumor tissue

Optical properties and photonic bands of si-based photonic crystals

A complete characterization of the photonic band structure is obtained by means of variable angle-reflectance and phase-sensitive techniques. The experimental results are compared to calculated reflectance and photonic band dispersion over a wide spectral range, and selection rules for the excitations of photonic modes in the crystal are obtained according to a symmetry analysi