Reliability of AC thick-film electroluminescent lamps

The reliability of AC thick-film EL devices has been studied. The AC thickfilm EL devices were fabricated by Novatech Inc. using the industrial print screen technology. The analysis of reasons for failure has been proposed. The dependence of EL lamp parameters on physical properties of the device EL layers was found. Our analysis of the breakdown spot showed that improvement of reliability can be reached using the additional dielectric layer between the phosphor layer and transparent electrode, high concentration of phosphor powder 70 % and binder 30 %, balanced resistance between the electric circuit and EL lamp. The thickness of the phosphor layer was equal to H = (1 + √3/2)D (hexagonal packing), where D is the mean diameter of phosphor particles. The reliability dependence of EL lamp on a water adsorption property of packaging material was revealed

Nature of Donors in SiC

6H-SiC samples were examined by ESR technique in temperature range from 5 K up to 300 K. Two kinds of ESR lines were observed: a single line at g = 2.0054 ± 0.0007, called X-line, and a triplet corresponding to isolated nitrogen defect. Ionization energy of X defect was determined as about 60 meV and the ionization energy of isolated nitrogen was determined as about 200 meV below SiC conduction band

Competition of Radiation Processes in 6H-SiC Observed by Luminescence

We report on the results of photoluminescence and thermoluminescence measurements of various 6H-SiC crystals. At low temperature in all n-type samples two bands with maxima at 2.7 eV (blue) and 1.8 eV (orange) were detected. In the p-type material only blue band was observed. The measurements performed at a broad range of temperatures showed totally different behaviour of photoluminescence intensity of both bands. The presented results could be explained in the model assuming well established donor-acceptor pair recombination for the blue band emission and the conduction band - deep defect transition for the orange band. The proposed model was confirmed by thermoluminescence measurements of the orange band which showed peaks at 30 K, 80 K, 100 K, 150 K attributed to ionization of subsequent shallow donor levels

FGCaMP7, an Improved Version of Fungi-Based Ratiometric Calcium Indicator for In Vivo Visualization of Neuronal Activity

Genetically encoded calcium indicators (GECIs) have become a widespread tool for the visualization of neuronal activity. As compared to popular GCaMP GECIs, the FGCaMP indicator benefits from calmodulin and M13-peptide from the fungi Aspergillus niger and Aspergillus fumigatus, which prevent its interaction with the intracellular environment. However, FGCaMP exhibits a two-phase fluorescence behavior with the variation of calcium ion concentration, has moderate sensitivity in neurons (as compared to the GCaMP6s indicator), and has not been fully characterized in vitro and in vivo. To address these limitations, we developed an enhanced version of FGCaMP, called FGCaMP7. FGCaMP7 preserves the ratiometric phenotype of FGCaMP, with a 3.1-fold larger ratiometric dynamic range in vitro. FGCaMP7 demonstrates 2.7- and 8.7-fold greater photostability compared to mEGFP and mTagBFP2 fluorescent proteins in vitro, respectively. The ratiometric response of FGCaMP7 is 1.6- and 1.4-fold higher, compared to the intensiometric response of GCaMP6s, in non-stimulated and stimulated neuronal cultures, respectively. We reveal the inertness of FGCaMP7 to the intracellular environment of HeLa cells using its truncated version with a deleted M13-like peptide; in contrast to the similarly truncated variant of GCaMP6s. We characterize the crystal structure of the parental FGCaMP indicator. Finally, we test the in vivo performance of FGCaMP7 in mouse brain using a two-photon microscope and an NVista miniscope; and in zebrafish using two-color ratiometric confocal imaging