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41.
R. D. Armstrong A. D. Sperrin F. L. Tye G. D. West 《Journal of Applied Electrochemistry》1972,2(4):265-273
Sintered plate Cd electrodes have been studied in alkaline solutions using potentiostatic and galvanostatic techniques. The behaviour is, in many ways, similar to that of a flat Cd electrode. A pseudo steady-state current is found due to the dissolution of Cd as Cd(OH)2–4. At more anodic potentials passivation occurs due to the solid state formation of Cd(OH)2. This model can account for the results obtained on galvanostatic discharge. 相似文献
42.
Ritesh Rawal Antonio Feteira Alberto Arenas Flores Neil C. Hyatt Anthony R. West Derek C. Sinclair Kumaravinothan Sarma Neil McN. Alford 《Journal of the American Ceramic Society》2006,89(1):336-339
The dielectric properties of dense ceramics of the "twinned" 8H-hexagonal perovskite Ba8 Nb4 Ti3 O24 are reported. Single-phase powders were obtained from the mixed-oxide route at 1325°C and ceramics (>92% of the theoretical X-ray density) by sintering in air or flowing O2 at 1400°–1450°C. The ceramics are dc insulators with a band gap >3.4 eV that resonate at microwave frequencies with relative permittivity, ɛr ∼44–48, quality factor, Q × f r ∼21 000–23 500 GHz (at f r ∼5.5 GHz) and temperature coefficient of resonant frequency, TC f ,∼+115 ppm/K. 相似文献
43.
Samkharadze N Kumar A Manfra MJ Pfeiffer LN West KW Csáthy GA 《The Review of scientific instruments》2011,82(5):053902
We fabricated a He-3 immersion cell for transport measurements of semiconductor nanostructures at ultra low temperatures and in strong magnetic fields. We have a new scheme of field-independent thermometry based on quartz tuning fork Helium-3 viscometry which monitors the local temperature of the sample's environment in real time. The operation and measurement circuitry of the quartz viscometer is described in detail. We provide evidence that the temperature of two-dimensional electron gas confined to a GaAs quantum well follows the temperature of the quartz viscometer down to 4 mK. 相似文献
44.
Smith JD West AA 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2008,222(6):947-958
The rehabilitation of the range of individuals covering medical patients to elite athletes is a costly and time-consuming process involving the knowledge of experienced physical therapists, medical practitioners, coaches, and dedicated training facilities. In order to improve the effectiveness and efficiency of the rehabilitation process, a modular variable-resistance rehabilitation device has been developed. The mechanical, electromechanical, and software systems identified during this research have been shown to provide a step change in exercise functionality, real-time patient monitoring, performance feedback, and safety. Using distributed network concepts, the physical therapist will be able to design and implement training regimes remotely, which can subsequently be downloaded to the localized resistance devices. The patient and/or athlete is able to complete the required exercises without personal supervision. The data from these sessions can be saved and accessed for assessment at a convenient time, thereby maximizing therapist productivity and optimizing the utilization of medical resources. 相似文献
45.
46.
T
c data are reported for powders of cation-stoichiometric Bi2Sr2CaCu2O and for nonstoichiometric samples based on the three mechanisms BiSr, SrCa and Sr vacancy. For each, the T
c values depend critically on the final oxygen contents, which were varied by heating samples in either O2 or N2 at different temperatures. Stoichiometric Bi2Sr2CaCu2O has the highest T
c, 92 K, obtained after heating in O2 at 820 °C. Heating in O2 at lower temperatures gives rise to overdoping and T
c decreases to 60 K. The other cation compositions show a smaller maximum T
c but also less reduction in T
c on overdoping. Under-doped samples, with reduced T
c values were obtained on heating in N2. These data, together with selected literature results, lead to a unified picture of the variation of T
c with cation composition and oxygen content. 相似文献
47.
Functionally graded nickel-aluminide and iron-aluminide coatings produced via laser cladding 总被引:4,自引:0,他引:4
Functionally graded nickel-aluminide and iron-aluminide in the form of superimposed clad layers up to 4 mm total thickness were produced on nickel and on iron based substrates, respectively. A continuous wave carbon dioxide laser and two separate powder feeders were employed. The processing parameters were: 1.8 kW laser power, 3 mm beam diameter, and 7 mm s–1 traverse speed. A series of single clad layers with various Al contents were first produced in order to obtain fundamental data required for the processing of functionally graded materials. Functionally graded Ni-Al and Fe-Al coatings (up to three layers) were produced by successive deposition of clad layers normal to the substrate surface.Compositional control was achieved by keeping the powder flow of Ni or Fe constant and changing the flow rate of Al. Microstructures are interpreted and discussed in relation to aluminides based on the Ni-Al and Fe-Al systems. 相似文献
48.
Avoidance of stomas and delayed anastomosis for bowel necrosis: the ''clip and drop-back'' technique
WG Vaughan JL Grosfeld K West LR Scherer E Villamizar FJ Rescorla 《Canadian Metallurgical Quarterly》1996,31(4):542-545
Necrotizing enterocolitis (NEC) and midgut volvulus (MGV) often are associated with extensive bowel necrosis. These cases may require extensive enterectomy and the formation of high or multiple stomas, and frequently are complicated by short bowel syndrome, excessive fluid losses, fistulas, stenosis, and skin breakdown. This report describes a "clip and drop-back" technique, followed by delayed anastomosis performed 48 to 72 hours later. The technique was successful in five severely ill infants (3 NEC, 2 MGV) with extensive necrosis, bowel perforation(s), and peritonitis, who required either a high stoma near the ligament of Treitz or multiple resections and enterostomies. This method removes obvious necrotic perforated bowel, controls contamination, avoids stomas (and their inherent complications in this age group), and preserves bowel length. All five babies survived. The technique is a useful addition to the pediatric surgeon's operative armamentarium in selective cases. 相似文献
49.
C. Ibarra-Ramírez M. E. Villafuerte-Castrejón A. R. West 《Journal of Materials Science》1985,20(3):812-816
The transformation Li3PO4 shows characteristics of both continuous and martensitic transformations. Below 340° C, no detectable transformation occurs; between 340 and 410° C, the transformation goes only partially to completion; above 410° C the transformation rapidly goes to completion. At any temperature in the range 340 to 410° C, transformation proceeds rapidly in the initial stages to attain a certain degree of transformation. With prolonged isothermal heating or grinding of the samples, further transformation does not occur. The reverse transformation could not be effected under normal, dry conditions. 相似文献
50.
Over a wide range of frequencies, the a.c. conductivity of ionic materials shows two regions of frequency-dependent conductivity. These are each characterized by a term K
p
1–n
n where K, n are constants,
p is a fundamental frequency identified with the hopping rate and is the measuring frequency. This behaviour is an example of Jonscher's Law of Dielectric Response for ionic conductors. In many cases, the region of low-frequency dispersion approximates to a frequency-independent plateau which may be taken as the d.c. conductivity. In others, a significant low-frequency dispersion is present and cannot be ignored in determining the effective d.c. conductivity. A method for the extraction of d.c. conductivities, hopping rates and for estimating carrier concentration effects is described. Data for three different types of material, single-crystal LiGaO2, -alumina and Na/Ag -alumina are used to illustrate the method. 相似文献