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Discusses the optical properties of the ZnSe1-xTeX epilayers which were grown by the molecular beam epitaxy. Information on the energy gap; Identification of the Te-bound exciton and an exciton bound to the Te cluster in the photoluminescence spectra; Observation of the spectacular atomic ordering; Proposal of a configuration coordinate diagram.

Presents a study which highlights the near-band-edge properties of the epilayers of the ZnSe. Comparison of the contactless electroreflectance (CER) and piezoreflectance spectra; Calculation of the energy splitting between heavy-hole related transition energies; Reference to the degradation of these devices.

Presents a study on the contactless electroreflectance of strained Zn0.79Cd0.21Se/ZnSe double quantum wells, grown by molecular beam epitaxy on GaAs substrates. Details on the intersub-band transitions in the CER spectra; Discussion on the quantum wells at 15 and 300 k; Comparison of the experimental and theoretical values for the transitions.

A new waveform retracking system applied on 18-Hz Envisat RA-2 data (cycles 10 to 90) was successfully developed in this study and aimed to improve the accuracy of measuring sea surface heights (SSHs) in coastal oceans around Taiwan. The specialized retracking system comprised the CurveFit retracker of fitting altimetry subwaveforms to the Brown model along with Gaussian peak models and a technique of removing non-ocean waveforms. Therefore, our system can favorably retain ocean-reflected waveforms and effectively reduce the land contamination in reflected waveforms. Results demonstrated that the CurveFit retracker performed best within 0 to 5 km offshore in all the study areas, with improvement percentages (IMPs) reaching a maximum of 92%. Within 5 to 10 km from the coast, the CurveFit retracked SSHs considerably improved with an IMP of up to 93%. Given that most waveforms, particularly of ground tracks from ocean to land, conformed to a typical ocean model in the 5 to 10 km zone, all the used retrackers similarly achieved satisfactory and equivalent improvements. This study also manifested that the accuracy of retracked SSHs largely depends on both land topography and ground tracks approaching or leaving land. The amount and accuracy of valid retracked measurements along ground tracks from land to ocean were remarkably lower than those of ground tracks across the coastline reversely. Moreover, the altimetric waveforms were highly contaminated by coastal land topography when ground tracks approached coastal flat land from the ocean or passed through coastal undulating topography toward the ocean. [ABSTRACT FROM AUTHOR]

Thin InGaN epitaxial layers and GaN-based light-emitting diodes (LEDs) on conventional and vicinal cut sapphire substrates are prepared. It is found that indium atoms are distributed much more uniformly in the samples prepared on vicinal cut sapphire substrates. It is also found that stronger electroluminescence intensity can be achieved without the band-filling effect of localised states from the LEDs with vicinal cut sapphire substrate. With 20 mA current injection, it is found that 44% electroluminescence intensity enhancement can be achieved by using the 1° tilted sapphire substrate. [ABSTRACT FROM AUTHOR]

Aim To determine whether (i) proinflammatory cytokines stimulate prostaglandin E2 (PGE2) production and cyclooxygenase (COX) gene expression in dental pulp cells, and (ii) pulp cells that express different prostaglandin E2 receptor (EP) isoforms and their activation by PGE2 leads to downstream Ca2+ signalling. Methodology Cultured human dental pulp cells were exposed to interleukin (IL)-1 β and tumour necrotic factor-alpha (TNF- α). The expression of COX-1 and COX-2 was measured with reverse transcriptase-polymerase chain reaction (RT-PCR). The production of PGE2 was measured using an enzyme-linked immunosorbent assay. Expression of prostaglandin EP receptor isoforms was studied by RT-PCR, whereas fura-2 fluorescence was used to measure calcium mobilization. The Kruskal–Wallis test and Wilcoxon sum rank test with Bonferroni correction were used for statistical analysis. Results Interleukin-1 β and TNF- α stimulate PGE2 production of human dental pulp cells ( P < 0.05). IL-1 β stimulated the COX-2 but not COX-1 mRNA expression. Pulp cells express mainly EP2, EP3 and EP1 receptors as analysed by RT-PCR. PGE2 (0.25–2 μmol L−1) stimulated the Ca2+ mobilization as indicated by increase in fura-2 fluorescence. Conclusions Interleukin-1 β and TNF- α may stimulate PGE2 production in dental pulp cells. Activation of prostaglandin EP receptors in dental pulp cells by PGE2 may induce Ca2+ signalling to regulate cellular biological activity during inflammation. [ABSTRACT FROM AUTHOR]

Various glass ionomer cements (GICs) and resin-modified GICs are widely used as tooth-colored restorative materials. However, their potential effects on pulp tissues are not fully understood. In this study, the authors compared the toxicity of nine types of GICs on cultured human dental pulp cells. Exposure of pulp cells to GICs for five days led to differential growth inhibition as analyzed by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Exposure of pulp cells to ProTec CEM, Fuji II LC, Compoglass and GC Lining cement for five days decreased the cell numbers to 11%, 12%, 19% and 25%, respectively. By contrast, Hy-Bond and Fuji I showed only mild suppression on the growth of pulp cells, with 12% and 16% decreased cell numbers. Morphologically, marked retraction and rounding of pulp cells were noted following exposure to GC Lining cement; in addition, cell surface blebbing was noted following exposure to Compoglass, Fuji II LC and ProTec CEM. Exposure of the pulp cells to Fuji II SC and Fuji IX, however, led to decreases in the cell density, with no obvious morphological changes. These results indicate that resin-modified GICs, such as Compoglass, Fuji II LC, ProTec CEM and GC Lining cements, are more toxic to pulp cells than conventional GICs. It is not recommended that resin-modified GICs be directly applied onto dental pulp cells. However, additional in vivo studies are needed to evaluate the potential toxicities of these resin-modified GICs during clinical operative procedures. [ABSTRACT FROM AUTHOR]

Because betel quid (BQ) chewing has been linked to a higher prevalence of periodontal diseases, the pathobiological effects of arecoline, a main alkaloid found in areca nut, were investigated in cultured human gingival fibroblasts. At concentrations higher than 0.4 mM, arecoline inhibits cell attachment, cell spreading and cell migration in a dose-dependent manner. These inhibitory effects were associated with intracellular depletion of glutathione (GSH). At concentrations of 0.4 mM and 1 mM, arecoline depleted about 26% and 45% of GSH after 2 h incubation. Exposure of cells to arecoline at concentrations lower than 0.4 mM for 2 h showed no significant decrease in either cell viability or intracellular GSH. However, incubation of cells for 24 h in 1 mM are colined decreased the cell numbers to only 35% of those in the untreated control. Arecoline also decreased cell growth and collagen synthesis in a dose-dependent manner. Because of repeated and long-term exposure to arecoline, BQ chewers could be more susceptible to periodontal damage and less responsive to new attachment procedures. [ABSTRACT FROM AUTHOR]

Irritations and injuries to the dental pulp usually lead to different degrees of pulpal inflammation. To investigate the roles of thrombin and prostaglandins in the healing and inflammatory processes of dental pulp as well as their effects on pulpal protein synthesis, human dental pulp cell cultures were established and their protein production was measured with or without the presence of exogenous thrombin and prostaglandins. At concentrations of 1-25 U/ml, alpha-thrombin increased the protein synthesis to 1.4-2.3 fold over the vehicle control. On the contrary, 0.1 microg/ml of prostaglandin E1 (PGE1) suppressed protein synthesis by 60%. Prostaglandin E2 (PGE2) also inhibited protein synthesis with an IC50 of 0.4 microg/ml. The stimulatory effects of thrombin (10 U/ml) can be inhibited by antithrombin III (2 U/ml) (a natural thrombin inhibitor) with heparin (2 U/ml), PPACK (D-Phe-Pro-ArgCH2Cl) (20-50 microg/ml) (a serine protease inhibitor), and PGE2 (0.5-1.0 microg/ml). Moreover, TRAP (20-40 microg/ml), a thrombin receptor agonist peptide, also exerted a stimulatory effect (1.21-1.37 fold). In conclusion, thrombin-induced protein synthesis by pulp cells is dependent on proteolytic activity, but not on binding to receptors. Both PGE1 and PGE2 exert suppressive effects on protein synthesis, indicating that interactions between thrombin and prostaglandins are important in regulating the inflammation, repair and regeneration of pulp tissue following injury. [ABSTRACT FROM AUTHOR]

To investigate the mechanisms involved in expansion of radicular cysts, monoclonal antibodies against interstitial collagenase (MMP-1) and tissue inhibitor of metalloproteinases-1 (TIMP-1) were used to localize the sites of MMP-1 and TIMP-1 expression in 30 radicular cysts. Positive MMP-1 staining was detected in the lining epithelium and subepithelial fibroblasts, macrophages, endothelial cells and osteoblasts/osteocytes in all specimens. Positive TIMP-1 staining was identified in osteoblasts/osteocytes and endothelial cells of all specimens, and in the lining epithelium and subepithelial fibrous connective tissue wall of five radicular cysts with an intense inflammatory cell infiltrate. The number and distribution of positive cells for MMP-1 or TIMP-1 varied widely among individual specimens, but strong immunostaining was constantly detected at sites with prominent subepithelial inflammation. Results here support the hypothesis that MMP-1 may play an important role in the expansion of radicular cysts. The absence of TIMP-1 expression in lining epithelium and subepithelial fibroblasts and macrophages in most cases studied indicated that an imbalance between MMP-1 and TIMP-1 production may lead to radicular cyst expansion. [ABSTRACT FROM AUTHOR]