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[en] At the request of Area Completion Engineering and in support of the 488-1D Ash Basin closure, the Savannah River National Laboratory (SRNL) performed hydrologic simulations of the revised 488-1D Ash Basin closure cap design using the Hydrologic Evaluation of Landfill Performance (HELP) model. The revised design substitutes a MicroDrain Liner®-60-mil low-density polyethylene geomembrane structurally integrated with 130-mil drainage layer-for the previously planned drainage/barrier system-300-mil geosynthetic drainage layer (GDL), 300-mil geosynthetic clay liner (GCL), and 6-inch common fill soil layer. For a 25-year, 24-hour storm event, HELP model v3.07 was employed to (1) predict the peak maximum daily hydraulic head for the geomembrane layer, and (2) ensure that South Carolina Department of Health and Environmental Control (SCDHEC) requirements for the barrier layer (i.e., ≤ 12 inches hydraulic head on top of a barrier having a saturated hydraulic conductivity ≤1.0E-05 cm/s) will not be exceeded. A 25-year, 24-hour storm event at the Savannah River Site (SRS) is 6.1 inches rainfall (Weber 1998). HELP model v3.07 results based upon the new planned cap design suggest that the peak maximum daily hydraulic head on the geomembrane barrier layer will be 0.15 inches for a minimum slope equal to 3%, which is two orders of magnitude below the SCDHEC upper limit of 12 inches.
[en] Highlights: ► A new approach of using Ag as a barrier layer to retard the electromigration-induced Cu dissolution. ► Two kinds of interfacial structures, Sn/Cu/Ag/Cu and Sn/Ni/Ag/Cu, were designed to perform electromigration tests. ► Under current stressing, thin Ag3Sn phase remained layer-structured. ► Electromigration force cannot fully drive Cu atoms across the Ag3Sn layer. ► The resistance to electromigration damage in Sn-based IMC phases: Ag3Sn > (Cu,Ni)6Sn5 > Ni3Sn4 > Cu6Sn5. -- Abstract: Dissolution of Cu metallization induced by electromigration is a serious reliability issue in flip-chip packaging. The passage of electron currents greatly increases the consumption of Cu layer while large amounts of Cu6Sn5 phase form in the solder matrix. In this study we proposed a new approach of using Ag as a barrier layer to retard the electromigration-induced Cu dissolution. Two different interfacial structures Sn/Cu/Ag/Cu and Sn/Ni/Ag/Cu were designed to perform electromigration tests where Cu or Ni could prevent the dissolution of the 1.5 μm Ag layer during reflow soldering. After aging the outer Cu or Ni layers form Cu6Sn5 and (Cu,Ni)6Sn5 layers which are dispersed in the solder matrix by electromigration. Surprisingly thin Ag3Sn phase remained layer-structured. Even after prolonged current stressing, inner Cu substrate was not significantly consumed. Therefore electromigration force could not fully drive Cu atoms across the Ag3Sn layer. These results have clearly demonstrated that Ag served as a very effective barrier layer in the current-induced Cu dissolution
[en] Stainless steel specimens equivalent to AISI type 304 taken from the CREVONA sodium loop (Forschungszentrum Karlsruhe, Germany), which was operated for more than 80 000 h, were analysed for microstructures and changes in chemical composition of depleted layers using SEM/EDAX. SEM micrographs were obtained in the cross-section of the specimens to reveal the thickness of the corroded layer. EDX analysis confirms depletion of Ni and Cr in the corroded layer. The leaching rates of chromium and nickel are obtained from the depleted layer width. These results are compared with the degraded layer and corrosion resistant node formation in sodium-exposed AISI type 316 SS specimens. The corroded layer widths of the specimens taken from the CREVONA loop determined using known models for life prediction like those proposed by Thorley and Tyzack are found to be much less than the actual layer widths observed experimentally after sodium exposure. The materials were exposed to flowing sodium for about 10 years
[en] We report improvement of emission efficiency in polymer light-emitting devices (PLEDs) employing phosphorescent polymers. A hole-blocking layer was inserted between the emissive layer and the cathode to enhance recombination efficiency for the injected holes and electrons. Aluminum(III)bis(2-methyl-8-quinolinato)4-phenylphenolato (BAlq) was used for the hole-blocking layer. The resultant PLEDs exhibited significant improvement of emission efficiency. The respective external quantum efficiencies for red, green and blue PLEDs were 6.6, 11 and 6.9%. These values are very high compared with those based on conventional fluorescent polymers
[en] A theory of surface waves in a layer of a spatially inhomogeneous cold electron plasma is presented. Four types of surface waves are revealed, and the conditions under which they can exist are determined. Complex frequency spectra are obtained, and the mechanisms for wave damping by plasma inhomogeneity are discussed
[en] The distributions of 210Po and 210Pb in the intermediate layer (400-2000 m) of the northwestern North Pacific were determined to elucidate the export flux of particulate matter. 210Po generally showed depletion relative to 210Pb in the intermediate layer, suggesting that 210Po was scavenged by particles. Because the removal rate constants of 210Po in the western region were higher than those in the eastern region and this trend coincided with that of the particle fluxes in the surface layer, the export production in the surface layer was assumed to influence the particle flux in the intermediate layer of the northwestern North Pacific. (author)
[en] The depletion length in a semiconductor nanosphere depends not only on the material parameters but on the nanosphere radius as well. For this reason, the depletion length does not present a universal characteristic length for all spherical interfaces. The difference from the standard flat model caused by the surface curvature is significant for a structure with the depletion length comparable to the radius of a nanosphere. We show that the depletion layer capacitance in a nanosphere becomes quite sensitive to the light intensity when, as a result of increasing optical generation rate, the surface potential barrier height is decreased and becomes very small. (paper)
[en] In this paper, a TCAD-based analysis of unconventional-geometry microstrip radiation detectors is discussed. In particular, thick-substrate and large-pitch devices, recently suggested for the adoption in outer layers of particle tracking systems have been considered. Correlation among parasitic capacitance and geometrical features is discussed, providing intuitive interpretation for experimentally observed behaviors. Influence of the substrate thickness on depletion voltage is discussed, and dependence of detector performance on the width/pitch ratio is taken into account as well, providing a complete picture of the behavior of thick-substrate devices, in view of their future use in LHC experiments
[en] Highlights: • TiO2-C composite with a Ti–C chemically bonded interface short the charger transfer path. • TiO2-C composite displayed exceptional photoelectron responses compared to TiO2/C composite without Ti–C bond. • The rate of visible-light driven photocatalytic water splitting for H2 generation of TiO2-C was about 12 times of TiO2/C composite. The construction of semiconductor composites is known a powerful method to realize the spatial separation of electrons and holes, which results in more electrons or holes dispersing on the surface, accompanying a charge transfer and further extending the region of charge depletion at the interface between these two components of the composite. However, most of them are based on a random accumulation connection of two different crystals and there are obvious empty spaces, which are formed as deplete layer to hinders the charge transfer to a large extent. In order to shorten the charger transfer path and make a direct charge transform from interface to surface, a chemically bonded interface in the composite is more reasonable. In this work, using one-dimensional TiO2-C composite nanorods with a Ti–C chemically bonded interface as a touchstone, which was prepared through a simple carbonized process, the above strategy for better semiconductor photocatalytic water splitting property has been realized.