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1.
Reactions between Strontium-Substituted Lanthanum Manganite and Yttria-Stabilized Zirconia: II, Diffusion Couples 总被引:1,自引:0,他引:1
Kjersti Kleveland Mari-Ann Einarsrud Christian R. Schmidt Senem Shamsili Sonia Faaland Kjell Wiik Tor Grande 《Journal of the American Ceramic Society》1999,82(3):729-734
Formation of secondary phases and diffusion of cations in diffusion couples of yttria-stabilized zirconia and lanthanum manganite substituted with 0 to 60 mol% strontium have been studied by scanning electron microscopy and energy dispersive X-ray spectroscopy. Only the primary phases were observed after 120 h at 1200°C, while formation of secondary phases was identified already after 1 h heat treatment at 1350°C. The phase composition of the reaction layer altered from La2 Zr2 O7 to SrZrO3 at increasing Sr content in La x Sr1- x MnO3 . The thickness of the reaction layer was increasing with heat treatment time. In diffusion couples of La0.4 Sr0.6 MnO3 formation of manganese oxide was observed in the perovskite layer after 1 h heat treatment at 1350°C, while isolated grains of SrZrO3 relatively deep inside the zirconia were observed after longer heat treatment time. Diffusion of Mn into zirconia was observed preferenced along grain boundaries in the early stage of the interface reaction. 相似文献
2.
The aim of this paper is to describe a simple, nonsurgical method for endoscopic placement of a nasojejunal feeding tube. A stylet inserted in the tube facilitates nasogastric intubation. A thread on the tip of the tube is grasped with a biopsy forceps inserted through an endoscope, and the tube can be placed in the distal part of the duodenum under direct endoscopic inspection. By means of a guide wire the tube can be pushed further to the desired position in the upper part of the jejunum. The endoscope can now be removed while pressure is exerted on the stylet, thus preventing the tube from dislocating. By this method, oral-nasal transfer of the tube is avoided, the tube is placed in the upper jejunum under direct endoscopic inspection, and the stylet inserted in the tube facilitates intubation and prevents it from dislocating when the endoscope is withdrawn. 相似文献
3.
Kjersti Kleveland rew Wereszczak Timothy P. Kirkland Mari-Ann Einarsrud Tor Grande 《Journal of the American Ceramic Society》2001,84(8):1822-1826
Compressive creep performance of strontium-deficient and strontium-excess SrFeO3-δ materials has been investigated in the temperature range 800°–1000°C and in the stress range 2.5–25 MPa. The absolute densities of the strontium-deficient and strontium-excess materials are 4.99 and 5.25 g/cm3 , respectively, which corresponds to porosities of ∼2% and 5%, respectively. Both materials contain secondary phases because of the cation nonstoichiometry. The creep rate is faster for the strontium-deficient material than the strontium-excess material. The stress exponent is approximately unity, and the activation energy is 260± 30 kJ/mol for both materials. The results can be explained by a cation diffusion mechanism. The present findings are discussed in relation to previous sintering data and the possible application of these materials as oxygen-permeable membranes. 相似文献
4.
Johnson M. Al-Shamma A. Bosch D. Crowley M. Farmwald M. Fasoli L. Ilkbahar A. Kleveland B. Lee T. Tz-yi Liu Quang Nguyen Scheuerlein R. So K. Thorp T. 《Solid-State Circuits, IEEE Journal of》2003,38(11):1920-1928
A 512-Mb one-time-programmable memory is described, which uses a transistorless two-terminal memory cell containing an antifuse and a diode. Cells are fabricated in polycrystalline silicon, stacked vertically in eight layers above a 0.25-/spl mu/m CMOS substrate. One-time programming is performed by applying a high voltage across the cell terminals, which ruptures the antifuse and permanently encodes a logic 0. Unruptured antifuses encode a logic 1. Cells are arranged in 8-Mb tiles, 1 K rows by 1 K columns by 8 bits high. The die contains 72 such tiles: 64 tiles for data and eight tiles for error-correcting code bits. Wordline and bitline decoders, bias circuits, and sense amplifiers are built in the CMOS substrate directly beneath the memory tiles, improving die efficiency. The device supports a generic standard NAND flash interface and operates from a single 3.3-V supply. 相似文献
5.
Kleveland B. Diaz C.H. Vook D. Madden L. Lee T.H. Wong S.S. 《Solid-State Circuits, IEEE Journal of》2001,36(10):1480-1488
The increasing number of interconnect layers that are needed in a CMOS process to meet the routing and power requirements of large digital circuits also yield significant advantages for analog applications. The reverse thickness scaling of the top metal layer can be exploited in the design of low-loss transmission lines. Coplanar transmission lines in the top metal layers take advantage of a low metal resistance and a large separation from the heavily doped silicon substrate. They are therefore fully compatible with current and future CMOS process technologies. To investigate the feasibility of extending CMOS designs beyond 10 GHz, a wide range of coplanar transmission lines are characterized. The effect of the substrate resistivity on coplanar wave propagation is explained. After achieving a record loss of 0.3 dB/mm at 50 GHz, coplanar lines are used in the design of distributed amplifiers and oscillators. They are the first to achieve higher than 10 GHz operating frequencies in a conventional CMOS technology 相似文献
6.
J. C. Walmsley A. Bardal K. Kleveland M.-A. Einarsrud T. Grande 《Journal of Materials Science》2000,35(17):4251-4260
Transmission Electron Microscopy has been conducted on rhombohedral perovskite oxides with composition LaCoO3, La0.8Sr0.2CoO3, and La0.8Ca0.2CoO3. Thin foils prepared within the first weeks of sintering showed macroscopic strain and a very high defect density, which included fault-related superlattice structures. Samples prepared several months after sintering, showed no significant macroscopic strain and the main defect was found to be domains due to reflection twinning in the pseudo-cube plane. The behaviour is likely to be related to accomodation of spontaneous strain arising upon cooling of the material from the sintering temperature. The presence of twin domains illustrates the lowering of lattice symmetry as compared to the ideal cubic perovskite structure, and is relevant for explaining recent observations of ferroelastic behaviour of these materials. 相似文献
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8.
I Lygren LP Andersen F Lerang PM Kleveland P Farup M Vatn I Aursnes 《Canadian Metallurgical Quarterly》1998,118(29):4511-4514
The article presents information gained from a survey among Norwegian hospitals in March 1997 concerning their treatment of infections with Helicobacter pylori. Altogether 52 hospitals answered the questionnaire. A combination of proton pump inhibitors, metronidazole and clarithromycin was used by 59% as first choice and urea quick test (94%) and urea breath test (42%) as the primary diagnostic procedures, whereas serology was in little use (17%). Besides ordinary ulcer disease, indications for treatment were: ulcer induced by non-steroid anti-inflammatory drugs (79%), gastrooesophageal reflux (37%), non-ulcer dyspepsia (14%) and cancer prophylaxis (14%). The gastro group at the Department of Pharmacotherapeutics at the University of Oslo invited specialists from all health regions to discuss indications for treatment of H pylori, the diagnosis and the role of general practitioners. The extensive use of clarithromycin might be doubtful due to development of resistance. Indications for treatment of H pylori other than ulcer disease and mucosa associated lymphoid tissue lymphoma are still uncertain. Uncritical use of serological tests in primary care should be discouraged. At present there is no uniform strategy for the diagnosis and treatment of H pylori infection, and a coordinated strategy between general practitioners and specialists is needed. 相似文献
9.
Detailed analysis of edge effects in SIMOX-MOS transistors 总被引:1,自引:0,他引:1
Elewa T. Kleveland B. Cristoloveanu S. Boukriss B. Chovet A. 《Electron Devices, IEEE Transactions on》1992,39(4):874-882
A comprehensive investigation of edge effects in LOCOS-isolated silicon-on-insulator devices is made by combining the measurements of the static characteristics, charge pumping, and noise. Even when a substrate bias is used to mask the conduction on the island edges, the high-frequency edge effects are still detectable. Appropriate models are proposed to separate the edge contribution from those of the front and back interfaces. It is found that the defect density on the edges is inhomogeneous, increasing vertically from the top to the bottom of the film and laterally from the middle to the end of the channel. Slow traps are identified at the back interface, close to the source/drain junctions 相似文献
10.
Cvetkovic S.R. Balachandran W. Kleveland B. Arnold P.G. Wilson F.G. Zhao A.P. 《Industry Applications, IEEE Transactions on》1996,32(4):844-850
Experimental measurements are compared with results obtained using a dedicated computer program for finite element modeling of electric fields in the vicinity of a liquid metal atomizer nozzle/tip. Good agreement between the experiment and the computer model has been achieved for two different nozzle geometries (Taylor cone and rounded tip), while paying particular attention to accuracy of the numerical solution near the tip (for equipotentials as well as derived values of field strength). In addition, the potential distribution has been calculated for several different positions of extractor voltage observed for each case. Finally, the assessment of suitability of the computer technique for qualitative consideration of the atomization process itself is presented 相似文献