Effects of growth variables on structural and optical properties of InGaN/GaN triangular-shaped quantum wells

Structural and optical properties of InGaN/GaN triangular-shaped multiple quantum well (QW) structures were investigated under various conditions of growth parameters such as growth temperature, flow rate of Ga and/ or In composition, and well and barrier widths. The optical properties affected by the growth parameters were well correlated with an In band gap, which is determined by the potential depth and the In composition in the well region. The emission peak energy was almost independent of the barrier width due to the relaxation of the piezoelectric fields in the triangular-shaped QWs. Photoluminescence spectra of the InGaN/GaN multiple QW structures showed a parabolic curve centered at 2.66 eV. The optical property of the triangular-shaped multiple QWs was substantially improved due to formation of quantum dot-like In composition fluctuations.     

Ternary Pt<Subscript>45</Subscript>Ru<Subscript>45</Subscript>M<Subscript>10</Subscript>/C (M=Mn,Mo and W) catalysts for methanol and ethanol electro-oxidation

Ternary Pt₄₅Ru₄₅Mn₁₀/C, Pt₄₅Ru₄₅Mo₁₀/C and Pt₄₅Ru₄₅W₁₀/C catalysts were synthesized and physical and electrochemical properties were characterized. Particle sizes of the catalysts were determined by X-ray diffraction to be 3.9, 4.8 and 4.6 nm for the Mn, Mo and W incorporated catalysts, respectively. Electrochemically active surface areas were calculated from CO stripping results, which were 17.7, 17.2 and 15.7 m²/g _catal for the Pt₄₅Ru₄₅Mn₁₀/C, Pt₄₅Ru₄₅Mo₁₀/C and Pt₄₅Ru₄₅W₁₀/C catalysts, respectively. In methanol electro-oxidation, the Pt₄₅Ru₄₅W₁₀/C catalyst showed highest mass and specific activities of 2.78 A/g _cat. and 177 mA/m², respectively, which were 22 and 100% higher than those of commercial PtRu/C. In the case of ethanol electro-oxidation, the Pt₄₅Ru₄₅Mo₁₀/C catalyst exhibited highest mass and specific activities of 4.8 A/g _catal and 280 mA/m², respectively. Specific activity of the Pt₄₅Ru₄₅Mo₁₀/C catalyst was 56% higher than that of the commercial PtRu/C.     

Medical Image Processing in Diagnostic Radiology

There exists a need to quantify the radiological information contained in the digital measurements of the imaging technologies. These imaging technologies include computed tomography, nuclear medicine examinations, diagnostic ultrasound imaging, computer radiography and digitization of radiographic film images. A rapidly growing number of studies suggest that useful quantitation of radiographic information includes linear measurements for organ estimation, estimation of surface areas and volumes, estimation of tissue density, and the visualization of three-dimensional organ sites.     

Investigation of Pt/WC/C catalyst for methanol electro-oxidation and oxygen electro-reduction

A Pt/WC/C catalyst is developed to increase the methanol electro-oxidation (MOR) and oxygen electro-reduction (ORR) activities of the Pt/C catalyst. Cyclic voltammetry and CO stripping results show that spill-over of H⁺ occurs in Pt/WC/C, and this is confirmed by comparing the desorption area values for H⁺ and CO. A significant reduction in the potential of the CO electro-oxidation peak from 0.81 V for Pt/C to 0.68 V for Pt/WC/C is observed in CO stripping test results. This indicates that an increase in the activity for CO electro-oxidation is achieved by replacing the carbon support with WC. Preferential deposition of Pt on WC rather than on the carbon support is investigated by complementary analysis of CO stripping, transmission electron microscopy and concentration mapping by energy dispersive spectroscopy. The Pt/WC/C catalyst exhibits a specific activity of 170 mA m⁻² for MOR. This is 42% higher than that for the Pt/C catalyst, viz., 120 mA m⁻². The Pt/WC/C catalyst also exhibits a much higher current density for ORR, i.e., 0.87 mA cm⁻² compared with 0.36 mA cm⁻² for Pt/C at 0.7 V. In the presence of methanol, the Pt/WC/C catalyst still maintains a higher current density than the Pt/C catalyst.     

Detection of roe deer,red deer,and hare meat in raw materials and processed products available in Poland

To allow detection of meat from the most popular game species in Poland, we developed a PCR-based method for identification of roe deer (Capreolus capreolus), red deer (Cervus elaphus), and hare (Lepus europaeus). The designed primers were based on the noncoding, mitochondrial D-loop region. Amplicon sizes ranged from 116 to 255 bp. The primers exhibited no cross-reactivity with the DNA from common slaughter and other game species. The detection limit of the assay was established to be below 0.001 % in raw red deer (C. elaphus) and hare (L. europaeus) meat, and below 0.01 % in raw roe deer (C. capreolus) meat, whereas <0.5 % of hare and red deer meat in processed samples could be detected. The PCR-based assay was used for authentication of 17 samples of raw game meat and 32 samples of game meat-containing products available in Polish markets. Analysis of all tested raw meat and processed products revealed the presence of DNA of investigated species in concordance with producers’ declarations.     

Measures of region failure survivability for wireless mesh networks

Wireless Networks - Wireless mesh networks (WMNs) are considered as a promising alternative to wired local, or metropolitan area networks. However, owing to their exposure to various disruptive...     

Dynamic behavior of a droplet on a moving wall

A two-dimensional immiscible droplet deformation phenomenon on a moving channel bottom wall is simulated using the lattice Boltzmann method. We considered the effect of the initial static contact angle, the capillary number, and the size of the droplet on the dynamic behavior of the moving droplet. When the initial static contact angle is less than 90°, the moving droplet is deformed and stretched, resulting in increasing width and decreasing height of the droplet. This is due to the hydrophilic (wetting) characteristic of the channel’s bottom wall. However, when the initial static contact angle is larger than 90°, the deformed and stretched droplet on the moving channel bottom wall is broken up, and is then pinched off or detached from the moving channel bottom wall, depending on the initial static contact angle and capillary number. This is due to the hydrophobic (non-wetting) characteristic of the wall.     

Synthesis of Porous Microparticles with Aligned Porosity

Microparticles with controlled porosity have been widely used in various applications. In this Full Paper, a new method of freezing emulsions has been developed to prepare porous microparticles with unique aligned porosity. Aligned porous poly(?‐caprolactone) microparticles are formed on an aligned porous polymeric composite. The aligned porous microparticles can be released simply by dissolving the supporting composite in water. The formation mechanism for the aligned porosity is discussed. The effects of freezing temperature and stirring speed are investigated. This method is also demonstrated to be generic in preparing porous microparticles with controlled porosity. As an example, polystyrene microparticles with different types of pores are produced. A preliminary study on the application of the porous microparticles in supporting stem cell growth is performed. It is found that poly(?‐caprolactone) microparticles can support the growth of mouse embryo stem cells.     

Expression of IL-16 in allergen-induced late-phase nasal responses and relation to topical glucocorticosteroid treatment

Allergen-induced late nasal responses (LNRs) are associated with a cellular infiltrate in which CD4+ cells are prominent. These cells have been shown to be the major cellular source of Th2-type cytokines. Mechanisms responsible for the local accumulation of CD4+ cells in the nasal mucosa after allergen exposure are unclear. IL-16 is a potent chemoattractant for CD4+ cells in vitro and may play a significant role in recruiting CD4+ cells in LNRs. We investigated the expression of IL-16 messenger RNA and immunoreactivity in nasal biopsy specimens from 17 subjects with allergic rhinitis. A biopsy specimen of the nasal inferior turbinate was obtained before and 24 hours after local nasal provocation with grass pollen extract after 6 weeks of treatment with either topical fluticasone propionate (n = 9) or placebo (n = 8) nasal spray twice daily. IL-16 mRNA-positive cells and IL-16-immunoreactive cells were identified in both the epithelium and the subepithelial tissue at baseline. Within the placebo-treated group, the numbers of epithelial and subepithelial IL-16 mRNA-positive cells and IL-16-immunoreactive cells were significantly increased 24 hours after challenge compared with baseline (p < 0.001). Topical glucocorticoid therapy resulted in a decrease in allergen-induced epithelial immunoreactive cells and subepithelial IL-16 mRNA-positive cells. The numbers of CD4+ cells increased after antigen challenge compared with baseline (p < 0.05), and this increase was inhibited by glucocorticoid treatment. There were significant correlations between epithelial and subepithelial IL-16 immunoreactivity and CD4+ cell infiltration after antigen challenge. The upregulation of IL-16 expression in allergic nasal mucosa after antigen challenge may have critical implications in the accumulation of CD4+ cells in response to antigen exposure. Steroid-mediated inhibition of IL-16 may be partly responsible for the decrease in local CD4+ cells after topical glucocorticoid therapy.