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51.
R. Ledworuski H. Lehr G. Niederfeld S. Walter F. Rühl J. Tschepe 《Microsystem Technologies》2002,9(1-2):133-136
Ultrasonic imaging techniques play an important role in endoscopic pre-operative staging and post operative follow-up of
tumour patients as well as for the assessment of cardiac insufficiency. However, cancerous lesions offer only low-contrast
targets. Therefore, high sensitivity systems with good contrast as well as flexible and robust handling are required to obtain
diagnostic accuracy and confidence. We developed a radial scanning ultrasonic catheter with a total diameter of 2.3 mm, which
makes use of a LIGA geared micromotor to turn an ultrasonic transducer directly at the tip of the catheter. Connector rings
fitted on a shaft as well as sliding contacts transmit the 20/30 MHz signals from the transmitter/receiver of an ultrasound
monitor system (Kretz Technik AG, Austria) to/from the rotating transducer. Due to its excellent performance and easy handling
the scanner module will be applied in a number of ultrasonic diagnostic applications.
Received: 10 August 2001/Accepted: 24 September 2001
This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2001
in June 2001. 相似文献
52.
The German Renewable Energy Act (EEG) has been very successful in promoting the deployment of renewable electricity technologies in Germany. The increasing share of EEG power in the generation portfolio, increasing amounts of fluctuating power generation, and the growing European integration of power markets governed by competition calls for a re-design of the EEG. In particular, a more efficient system integration and commercial integration of the EEG power is needed to, e.g. better matching feed-in to demand and avoiding stress on electricity grids. This article describes three different options to improve the EEG by providing appropriate incentives and more flexibility to the promotion mechanism and the quantitative compensation scheme without jeopardising the fast deployment of renewable energy technologies. In the “Retailer Model”, it becomes the responsibility of the end-use retailers to adapt the EEG power to the actual demand of their respective customers. The “Market Mediator Model” establishes an independent market mediator responsible to market the renewable electricity. This model is the primary choice when new market entrants are regarded as crucial for the better integration of renewable energy and enhanced competition. The “Optional Bonus Model” relies more on functioning markets since power plant operators can alternatively choose to market the generated electricity themselves with a premium on top of the market price instead of a fixed price. 相似文献
53.
Wilson M.P. Macgregor S.J. Given M.J. Timoshkin I.V. Sinclair M.A. Thomas K.J. Lehr J.M. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2009,16(4):1028-1036
The applied electrical fields required to initiate surface flashover of different types of dielectric material immersed in insulating oil have been investigated, by applying impulses of increasing peak voltage until surface flashover occurred. The behavior of the materials in repeatedly over-volted gaps was also analyzed in terms of breakdown mode (some bulk sample breakdown behaviour was witnessed in this regime), time to breakdown, and breakdown voltage. Cylindrical samples of polypropylene, low-density polyethylene, ultra-high molecular weight polyethylene, and Rexolite, were held between two electrodes immersed in insulating oil, and subjected to average applied electrical fields up to 870 kV/cm. Tests were performed in both uniform- and nonuniform- fields, and with different sample topologies. In applied field measurements, polypropylene required the highest levels of average applied field to initiate flashover in all electrode configurations tested, settling at ~600 kV/cm in uniform fields, and ~325 kV/cm in non-uniform fields. In over-volted point-plane gaps, ultra-high molecular weight polyethylene exhibited the longest pre-breakdown delay times. The results will provide comparative data for system designers for the appropriate choice of dielectric materials to act as insulators for high-voltage, pulsed-power machines. 相似文献
54.
A. Leitner E. Sörensen F. Wunderlich E. Lehr H. Lohmann Wz. 《Forschung im Ingenieurwesen》1944,15(1):26-28
Ohne Zusammenfassung
VDI 相似文献
55.
Human glandular kallikrein (hK2) is a possible new marker for prostate cancer that is homologous to prostate specific antigen. Purified hK2 added to serum or plasma reacted with endogenous protease inhibitors to form complexes of >350, 135, and 80 kDa, and some hK2 remained free, as judged by immunoblotting. The former two complexes could be removed by specific antibodies to alpha2-macroglobulin and to C1- inactivator, respectively, and they comigrated on SDS-PAGE with complexes formed between hK2 and purified alpha2-macroglobulin or C1-inactivator. hK2 complexes of 80 kDa could not be completely removed with any anti-serpin antibody used. Thus, these may consist of more than one type of hK2 complex. In contrast, essentially all hK2 complexes were removed from seminal plasma by antibody to protein C inhibitor, demonstrating that protein C inhibitor is the only significant inhibitor of hK2 in semen. hK2 reacted more rapidly with alpha2-macroglobulin than with any other inhibitor in plasma or serum. Divalent metal ions and heparin did not appreciably affect the rate of formation of any of the hK2 complexes in serum or plasma or with purified alpha2-macroglobulin or C1-inactivator. Measurement of one or more of the hK2 forms identified here may have diagnostic or prognostic potential for prostate cancer. 相似文献
56.
E Uhl JH Barker I Bondàr TJ Galla HA Lehr K Messmer 《Canadian Metallurgical Quarterly》1994,32(4):361-5; discussion 365-6
The effect of subcutaneously injected recombinant human basic fibroblast growth factor (bFGF) was studied in an arterial skin flap model on the ear of the hairless mouse. Fifty-three male, hairless mice were randomly assigned to 4 groups and pretreated in two different time intervals with different doses of human bFGF. Microvascular perfusion of the skin flaps was determined over a 5-day period by means of intravital microscopy after intravenous injection of the fluorescence marker fluorescein isothiocyanate-dextran (M(r) 150,000). Human bFGF (2,700 ng) injected 6 days before flap creation could not improve perfusion of the flap (n = 10) when compared with controls. However, when applied 18 days before flap creation (n = 13), the same dose resulted in a significant reduction of nonperfused tissue at day 5 after flap creation (12.3% vs 26.8%, p < 0.01). Eighteen-day pretreatment with 1,200 ng (n = 10) and 480 ng (n = 10) had no significant effect on skin flap perfusion. We conclude, therefore, that successful pretreatment with bFGF for prevention of skin flap necrosis is time and dose dependent. 相似文献
57.
58.
59.
Cavity ring-down spectroscopy and degenerate four-wave mixing have been applied for spectroscopic studies, temperature determination, and measurement of relative dipole transition moments of photochemically produced sodium hydride. In our experiment, NaH was formed within a heat-pipe oven after 3p excitation of sodium in a hydrogen atmosphere with a second dye laser. The reaction product NaH was probed in the near ultraviolet part of the spectrum at 382 nm with 1-4-μs delay to the excitation pulse using both a linear and nonlinear spectroscopic technique with a pulsed dye laser source (pulsewidth 15-ns full-width half-maximum). The strengths and limitations of these two spectroscopic techniques are discussed. Since the two processes depend on different parameters and the image-forming beams have different properties, it is difficult to define a single criterion for comparison. But our measurements indicate that cavity ring-down spectroscopy is a powerful tool with a sensitivity better than 109 particles per cm3 and quantum state which is comparable to degenerate four-wave mixing in our case 相似文献
60.
The prevalence of rheumatic forefoot arthritis is estimated at 85-95%. Early synovitis of the metatarsophalangeal (MTP) joints is frequently neglected or overlooked. The disease leads to depression of the forefoot arch, dislocation of the MTP joints and hallux valgus with severe metatarsalgia. Operative treatment may give good results in 77-91% of cases. Our preferred treatment consists of resection arthroplasties for the smaller toes and use of Swanson spacer for the big toe, extensive capsular and tendon release from the dorsal approach, reduction of the first metatarsal bone, relocation of the extensor hallucis tendon and postoperative corrective dressing for 6-12 weeks. With this technique, we obtained 36 good results out of 46 forefoot reconstructions, the mean observation period being 30 months. 相似文献