We have fabricated highly packed and ordered In0.4Ga0.6As quantum dots (QDs) array on GaAs(311)B substrate without coalescence of QDs. Reflection high-energy electron diffraction and Auger spectra suggest the inhomogeneous distribution of In and Ga in QD. In concentration near the surface of QD is larger than that of the inside, and the inhomogeneous distribution of In and Ga in QDs prevents QDs from merging.
SUMMARYIntestinal epithelial cell (IEC)-derived cytokines, such as stem cell factor (SCF), interleukin (IL)-7 and IL-15 are known to be required for the development of intestinal intraepithelial lymphocytes (IELs). A newly described cytokine, IL-18, has also been shown to be produced by intestinal epithelial cells. To demonstrate the functional effects of IL-18 on human IELs, we assessed IL-18/IL-18 receptor expression in IEC/IEL and proliferation following stimulation of intestinal IELs by IL-18. IL-18 transcripts were detected both in freshly isolated human colonic epithelial cells and in various colonic epithelial cell lines. IL-18 protein was also detected by ELISA and flow cytometric analysis using antihuman IL-18-specific monoclonal antibody (MoAb). Furthermore, IELs constitutively expressed the IL-18 receptor in addition to the IL-2 and IL-7 receptors. More importantly, IL-18 augmented significant proliferative responses of IEL in combination with IL-2, IL-7 and IL-15 both in the presence and in absence of anti-CD3 MoAb. These results suggest that IL-18 might play a crucial role in the proliferation and maintenance of intestinal IELs.
Collectively, the power of the colitis model induced by the adoptive transfer of CD4CD45RB T cells into nude mice is that one can investigate the roles of TH2-type cells and B cells in a regulatory T cell-depleted condition.
The influence of the amount of hydrogen (H) in hydrogenated silicon nitride films (SixNy:Hz) on the etching properties and etching mechanism are unclear for hydrofluorocarbon plasma etching. Therefore, the authors have investigated the effect of H in SixNy:Hz films on the surface reactions during CH2F2/Ar/O2 plasma etching by experimental and numerical simulation techniques. The experimental etch yield (EY) and polymer layer thickness (TC−F) values for SixNy:Hz films with different H concentrations of 2.6% (low-SiN), 16.8% (mod-SiN), and 21.9% (high-SiN) show different trends with the CH2F2/(CH2F2 + O2) flow rate ratio. To understand the mechanism of the different etching properties, the authors estimated the chemical reaction probabilities of the H outflux between F, O, N, C, and Si dangling bonds using first principles calculations and the results of Fourier transform infrared spectroscopy. Based on the estimated reaction probabilities, the authors modeled the surface reactions of SixNy:Hz films under the assumption that the H outflux mainly scavenges incident F radicals (the main etchant species). The authors also consider that the reaction between H and N from outfluxes decreases the desorption reactions of C2N2 and HCN, resulting in a larger TC−F value. Comparing the simulation results of the trends in the whole flow rate ratio range and the absolute values of EY and TC−F with experimental data, the surface model can successfully explain the mechanism. Furthermore, the authors demonstrated time-dependent etched profile and damage distribution for fin-type field-effect transistor SixNy:Hz side-wall etching using the three-dimensional voxel-slab model with the above surface reactions to obtain knowledge about the effect of H on the etched profile and damage distribution. The results show that the etched profile and damage distribution on the Si fin structure are very different for low-SiN and high-SiN because of the different EY and TC−F values induced by different H outfluxes. These results indicate that it is important to carefully control both the etching process and amount of H in the SixNy:Hz film to achieve high-performance advanced complementary metal oxide semiconductor devices.
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