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31.
Xingqun Jiang Mishra N. Turner J.N. Spencer M.G. 《Nanotechnology, IEEE Transactions on》2007,6(3):328-333
A novel method has been developed for fabricating full or partial freestanding anodic alumina. In our method a sacrificial metal layer is introduced between an Al film and a Si3N4 substrate. A freestanding alumina film at wafer scale is successfully achieved by anodizing the double metal layer, during which the alumina is spontaneously stripped off the Si3N4 substrate due to the anodic oxidation of the sacrificial layer. The barrier oxide of the alumina film is effectively removed either by H3PO4 dissolution or by CF4 reactive ion etching. The freestanding alumina film is utilized as a contact mask to transfer its nanoporous pattern to a Si substrate. By patterning the sacrificial metal layer with contact lithography, a partial freestanding alumina film is successfully achieved on the silicon chip, producing a unique micro/nanofluidic channel. Compared with previous techniques, the method reported here is advantageous for its simplicity and flexibility 相似文献
32.
A Novel Inverse-Magnetostrictive Force Sensor 总被引:1,自引:0,他引:1
The change in magnetic permeability of a material under stress (inverse magnetostriction) offers the potential for a high-performance, low-cost force sensor capable of being used in harsh real-world environments. The existing force sensor technologies are limited in their use in commercial products by either cost issues or susceptibility to electromagnetic noise. Inverse Magnetostriction has been used to measure strain in controlled environments since its discovery by Joule in 1847, but not in practical applications due to a lack of data on how magnetic material properties change with environmental conditions such as temperature. Utilizing an innovative noise-reducing self-inductance design, this paper presents the basis for an inverse-magnetostrictive compressive load sensor. A lumped-parameter model for the change in sensor inductance under load, due to both mechanical and magnetic effects, is derived. The material properties of a magnetostrictive iron alloy are empirically determined over a broad range of loads and temperatures. The model and material properties are confirmed by testing a prototype force sensor. The prototype measures compressive forces from 100 to 25 000 N over a temperature range of 20 degC to 120 deg with a typical error of +/-2% (4% max). The sensor does experience significant thermal hysteresis for which the model does not currently account. This work was motivated by the need for a force sensor in an automobile electric brake system and used a single iron alloy (50% Ni), but the model and testing procedure provide a roadmap for future research to improve the performance and capabilities of such a sensor 相似文献
33.
Turning software into a service 总被引:4,自引:0,他引:4
The software as a service model composes services dynamically, as needed, by binding several lower-level services-thus overcoming many limitations that constrain traditional software use, deployment, and evolution. 相似文献
34.
We conducted a study to determine if the risk of airway compromise following tonsillectomy with uvulopalatopharyngoplasty justifies the added cost and inconvenience of step-down monitoring in an intensive care unit. We performed a retrospective chart review of 130 patients with obstructive sleep apnea who had undergone isolated tonsillectomy with uvulopalatopharyngoplasty at our tertiary care center. The average length of stay in the step-down unit was 18 hours. We found that only eight of these patients (6.2%) had a postoperative desaturation level of less than 90%, including three of 12 patients (25%) who had comorbid conditions. No patient had an adverse respiratory event. We conclude that step-down monitoring in an intensive care unit is not necessary, although caution should be exercised in monitoring patients with comorbidities because they appear to be more prone to desaturation. A complete lack of adverse respiratory events has not been reported in previous studies. 相似文献
35.
36.
Suwanprateeb K. E. Tanner S. Turner W. Bonfield 《Journal of materials science. Materials in medicine》1995,6(12):804-807
Isochronous stress-strain relationships and long term creep performance for unfilled and hydroxyapatite filled polyethylene composites have been studied. The tests were carried out in a buffered (pH=7.5) Ringer's solution at 37°C. It was observed that the inclusion of hydroxyapatite does not remove the non-linear viscoelasticity of polyethylene. The creep resistance is found to increase with increase in volume fraction of hydroxyapatite. The creep failure of composites at long times can occur due to debonding of the interface. 相似文献
37.
Robbins Michael S.; Turner Charles W.; Alexander James F.; Perez Gonzalo A. 《Canadian Metallurgical Quarterly》2003,17(4):534
This study examined the relationship between alliance and retention in family therapy. Alliance was examined at the individual (parent and adolescent) and family levels (within-family differences). Participants were 34 families who received functional family therapy for the treatment of adolescent (aged 12-18 years) behavior problems. Families were classified as treatment dropouts (n=14) or completers (n=20). Videotapes of the first sessions were rated to identify parent and adolescent alliances with the therapist. Results demonstrated that individual parent and adolescent alliances did not predict retention. However, as hypothesized, dropout cases had significantly higher unbalanced alliances (parent minus adolescent) than did completer cases. These findings highlight the importance of alliances in functional family therapy and suggest that how the alliance operates in conjoint family therapy may be a function of systemic rather than of individual processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
38.
Y Sun A Hildesheim LA Brinton PC Nasca CL Trimble RJ Kurman RP Viscidi KV Shah 《Canadian Metallurgical Quarterly》1996,63(2):200-203
We describe a case of positional dyspnea due to compression of the tracheobronchial tree by an extensive thoracic aneurysm. In a 77-year-old woman with long-standing systemic hypertension, intermittent anterior chest pain gradually developed over several years. She had no history of asthma or thoracic trauma. She was admitted to our hospital because of sudden, severe shortness of breath. The breathlessness was markedly worse when she lay on her back or on her right side. On physical examination, she was in acute respiratory distress with cyanosis, severe hypertension (180/110 mmHg), tachycardia, and inspiratory stridor. A chest X-ray film showed loss of volume and nearly complete radiopacity of the left hemithorax. Arterial blood gas analysis revealed an arterial oxygen partial pressure of 54.8 mmHg, a carbon dioxide partial pressure of 39.8 mmHg, and an oxygen saturation of 84.5 percent on room air. Computed tomographic examination of the thorax showed dilation of the aortic arch and descending aorta, and marked compression of the trachea and the left main bronchus. Examination with a fiberoptic bronchoscope revealed extrinsic compression of the trachea just proximal to the carina. The patient's symptoms stabilized. However, she did not undergo surgery because of her age and because of the size of the aneurysm. She died due to rupture of the aneurysm. 相似文献
39.
40.
Prostate development and disease are androgen dependent. However, the nature of hormonal effects on the prostate of healthy young men is not clear. We, therefore, measured prostate size in males chronically exposed to high doses of androgens (AS; habitual anabolic steroid abusers; n = 15) or estrogens (E; male to female transsexuals; n = 11) and compared the results with those in age-matched healthy eugonadal men without known prostate disorders. Prostate size was measured by planimetric ultrasound as cross-sectional areas and maximal dimensions in three orthogonal dimensions with a 7.5-megahertz B-mode sector scanner biplane in a transrectal transducer at 2.5 mm steps from the base to the apex of prostate. Total prostate volume (TPV) was reconstructed from planimetric sections, central prostate volume (CPV) was calculated by the ellipsoidal formula from the appropriate three maximum dimensions, and peripheral prostate volume was determined by the difference between TPV and CPV. Compared with age-matched controls, TPV was normal (-2%) in AS (P = 0.752) and reduced by 31% in E (P = 0.002), whereas CPV was increased by 20% in AS (P = 0.002) and reduced by 46% in E (P = 0.002), and the ratio of CPV/peripheral prostate volume was increased by 77% in AS (P < 0.001) and decreased by 33% in E (P = 0.047). Blood sex hormone-binding globulin was elevated by nearly 500% in E (P < 0.001), but was reduced by 47% in AS (P = 0.003). Prostate-specific antigen was normal (-6%) in AS (P = 0.799) and decreased by 86% in E (P = 0.002). Prostatic acid phosphatase was increased by 26% in AS (P = 0.007), but was unchanged (-28%) in E (P = 0.106). Total and free testosterone levels were reduced to castrate levels in E, whereas LH, FSH, and total testosterone levels were significantly reduced in AS. We conclude that in the human prostate of young men, CPV is more hormonally sensitive than TPV, and during high dose treatment, CPV is preferentially increased by chronic androgen treatment and decreased by chronic estrogen treatment. The reduction of TPV by estrogens was less than expected if solely attributable to inhibition of endogenous gonadotropin and testosterone secretion, suggesting that estrogens also have a positive effect on the normal human prostate. The reversibility and long term significance of androgen-induced stimulation of CPV and, in particular, its relationship to the onset and severity of benign prostatic hyperplasia remain to be clarified. 相似文献