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895.
Seip R. VanBaren P. Cain C.A. Ebbini E.S. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1996,43(6):1063-1073
A method for noninvasively estimating spatiotemporal temperature changes in samples using diagnostic ultrasound, and using these as inputs to a multipoint ultrasound phased array temperature controller, is presented in this paper. This method is based on a linear relationship between the apparent tissue echo pattern displacements and temperature, as seen along A-lines acquired with diagnostic ultrasound when the sample is heated by external heating fields. The proportionality constant between echo displacement and temperature is determined by the local change in speed of sound due to temperature and the linear coefficient of thermal expansion of the material. Accurate estimation of the displacements and proportionality constant yields accurate calibrated high-resolution (1 mm spatial, sub-°C) noninvasive sample temperature estimates. These are used as inputs to a multipoint temperature controller, capable of controlling ultrasound phased array treatments in real-time. Phantom and in vitro results show that the noninvasively estimated temperature values can effectively be used to control ultrasound hyperthermia treatments, almost replacing invasive thermocouple measurements. The mathematical background and assumptions of the noninvasive temperature estimator and the controller are presented in this paper, together with experimental results showing estimator and controller performance and limitations. To the best of our knowledge, this paper presents the first demonstration of real-time treatment control based entirely on noninvasive temperature estimates 相似文献
896.
J. E. G. Hulshoff K. Van Dijk J. P. C. M. Van Der Waerden W. Kalk J. A. Jansen 《Journal of materials science. Materials in medicine》1996,7(10):603-609
The bone response to different calcium phosphate (Ca-P) coated implants was evaluated in a goat animal model. Two types of plasma spray coatings were applied to a commercially pure titanium (cpTi) tapered, conical screw-design implant (BioComp®); hydroxyapatite (HA-PS) and a dual coating, consisting of FA and HA (FA/HA-PS). In addition an amorphous RF magnetron sputter coating (Ca-P-a) and uncoated implants were investigated. Forty-eight implants were inserted in the maxilla of 12 adult female goats. After implantation periods of 3 and 6 months, the bone implant interface was evaluated histologically and histomorphometrically. After both implantation periods all plasma spray coated implants were maintained. On the other hand three Ca-P-a and two cpTi implants were lost. Histological examination revealed a better bone response to both plasma spray coated implants. Histomorphometrical evaluation confirmed this finding. At 3 and 6 months significantly higher percentages of bone contact (p<0.001, ANOVA) were measured for both plasma spray coated implants than for the cpTi and Ca-P-a implants, while no significant difference (p<0.05) existed between both implantation periods. Degradation of both plasma spray coatings was observed. Supported by the results, it is concluded that, although Ca-P coatings can improve the performance of dental implants, the presence of a Ca-P coating is not the only important factor for bone healing around implants placed in low density trabecular bone. 相似文献
897.
H Bensahel P Souchet GF Pennecot Y Desgrippes 《Canadian Metallurgical Quarterly》1994,120(5):298-9; discussion 300
Current work on disease states involving the patella has led to increased interest in patellar instability. We reviewed a series of patellar luxations. True trauma-induced luxations are rare. Most cases are recurrent luxations in subjects with a morphological anomaly of the knee extensor system. Because of the growth cartilages, selective therapeutic techniques are needed to stabilize the patella. Recurrent or permanent luxations of the patella result from congenital malformations of the muscles or skeleton. A complete MRI study is highly indicated. The patella can be correctly realigned by surgical release. In cases with femoropatellar dysplasia, which is not specific for children, well conducted rehabilitation therapy often leads to favourable outcome. 相似文献
898.
All-Union Scientific-Research Institute of Nuclear Power Plants NIIP. Translated from Atomnaya énergiya, Vol. 77, No. 5, pp.
392–402, November, 1994. 相似文献
899.
The short-range order (SRO) structure of a Au-25 at. pct Fe single crystal was studied using wide-angle diffuse synchrotron
X-radiation scattering at room temperature. Two heat treatments were investigated: a 400 °C aging treatment for 2 days and
a 440 °C treatment for 5 days, both preceded by solution treatment in the single-phase field and water-quenched to room temperature.
Evolution of the SRO structure with aging was determined by fitting the two sets of Cowley-Warren (C-W) SRO parameters to
a pair of 140,608-atom models. The microstructures, although quite disordered, showed a trend with aging for an increasing
volume fraction of an Fe-enriched and an Fe-depleted environment. The Fe-enriched environment displayed a preference for Fe
segregation to the {110} and {100} face-centered cubic (fcc) matrix planes. A major portion of the Fe-depleted environment
was found to contain elements (and variations of these elements) of the Dla ordered superstructure. The SRO contained in the Fe-depleted environment may be best described in terms of the standing concentration
wave packet (SCWP) model. This study provides, for the first time, a quantitative real-space view of the atomic arrangements,
which make up both environments in the SRO structure of Au-25 at. pct Fe.
Formerly Graduate Research Assistant, University of Illinois, Urbana, IL. 相似文献
900.