排序方式: 共有43条查询结果,搜索用时 390 毫秒
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Chlamydiosis in workers at a duck farm and processing plant 总被引:4,自引:0,他引:4
DG HINTON A. SHIPLEY† JW GALVIN‡ JT HARKIN‡ RA BRUNTON† 《Australian veterinary journal》1993,70(5):174-176
SUMMARY An outbreak of chlamydiosis was Investigated in workers at a duck farm and processing plant during winter 1989. Chlamydia psittaci was isolated from ducks, but there was little evidence of clinical chlamydiosis in the ducks. Serological tests showed that 76% of workers had been exposed to Infection, 12% recently, 16% had not been exposed and 8% had inconclusive test results. There was a strong association (P < 0.05) between years of employment and exposure to Infection. Infection appeared to be contracted during the first year of employment. Measures were Implemented to reduce shed contamination and control rodents and wild birds. At the same time, ducks were medicated, the processing plant was modified, work practices were altered and workers were advised about chlamydiosis to reduce the risk of human infection. 相似文献
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Epitaxial BiFeO3 multiferroic thin film heterostructures 总被引:2,自引:0,他引:2
Wang J Neaton JB Zheng H Nagarajan V Ogale SB Liu B Viehland D Vaithyanathan V Schlom DG Waghmare UV Spaldin NA Rabe KM Wuttig M Ramesh R 《Science (New York, N.Y.)》2003,299(5613):1719-1722
Enhancement of polarization and related properties in heteroepitaxially constrained thin films of the ferroelectromagnet, BiFeO3, is reported. Structure analysis indicates that the crystal structure of film is monoclinic in contrast to bulk, which is rhombohedral. The films display a room-temperature spontaneous polarization (50 to 60 microcoulombs per square centimeter) almost an order of magnitude higher than that of the bulk (6.1 microcoulombs per square centimeter). The observed enhancement is corroborated by first-principles calculations and found to originate from a high sensitivity of the polarization to small changes in lattice parameters. The films also exhibit enhanced thickness-dependent magnetism compared with the bulk. These enhanced and combined functional responses in thin film form present an opportunity to create and implement thin film devices that actively couple the magnetic and ferroelectric order parameters. 相似文献
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Giant piezoelectricity on Si for hyperactive MEMS 总被引:1,自引:0,他引:1
Baek SH Park J Kim DM Aksyuk VA Das RR Bu SD Felker DA Lettieri J Vaithyanathan V Bharadwaja SS Bassiri-Gharb N Chen YB Sun HP Folkman CM Jang HW Kreft DJ Streiffer SK Ramesh R Pan XQ Trolier-McKinstry S Schlom DG Rzchowski MS Blick RH Eom CB 《Science (New York, N.Y.)》2011,334(6058):958-961
Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting. 相似文献
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ObjectiveTo investigate the contribution of K+ channels on peripheral antinociception induced by ketamine.Study designProspective experimental study.Animals110 male Wistar rats weighing 160–200 g.MethodsThe paw pressure required to elicit limb flexion was designated as the nociceptive threshold. Hyperalgesia was induced by intraplantar injection of prostaglandin E2. All drugs were administered locally into the right hind paw of rats. Ketamine was administered into the right hind paw 2 hours and 55 minutes after local injection of PGE2. Tetraethylammonium was administered 30 minutes prior to ketamine and the other K+ channel blockers, glibenclamide, dequalinium and paxilline, were administered 5 minutes prior to ketamine.ResultsProstaglandin E2 (2 μg per paw) induced hyperalgesia. Ketamine (10, 20, 40 and 80 μg per paw) elicited a local peripheral antinociceptive effect that was antagonized by a specific blocker of ATP‐sensitive K+ channels, glibenclamide (20, 40 and 80 μg per paw). In another experiment, the non‐selective voltage‐dependent K+ channel blocker tetraethylammonium (30 μg per paw) and small and large conductance blockers of Ca2+‐activated K+ channels, dequalinium (50 μg per paw) and paxilline (20 μg per paw), were ineffective at blocking the effect of a local ketamine injection.Conclusions and clinical relevanceAnalysis of these results provides evidence that ketamine, may in part, induce peripheral antinociceptive effects by ATP‐sensitive K+ channel pathway activation. 相似文献
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NH Bonadeo J Erland D Gammon D Park DS Katzer DG Steel 《Science (New York, N.Y.)》1998,282(5393):1473-1476
Picosecond optical excitation was used to coherently control the excitation in a single quantum dot on a time scale that is short compared with the time scale for loss of quantum coherence. The excitonic wave function was manipulated by controlling the optical phase of the two-pulse sequence through timing and polarization. Wave function engineering techniques, developed in atomic and molecular systems, were used to monitor and control a nonstationary quantum mechanical state composed of a superposition of eigenstates. The results extend the concept of coherent control in semiconductors to the limit of a single quantum system in a zero-dimensional quantum dot. 相似文献
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Tenne DA Bruchhausen A Lanzillotti-Kimura ND Fainstein A Katiyar RS Cantarero A Soukiassian A Vaithyanathan V Haeni JH Tian W Schlom DG Choi KJ Kim DM Eom CB Sun HP Pan XQ Li YL Chen LQ Jia QX Nakhmanson SM Rabe KM Xi XX 《Science (New York, N.Y.)》2006,313(5793):1614-1616
We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (Tc) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are not only ferroelectric (with Tc as high as 250 kelvin) but also polarize the quantum paraelectric SrTiO3 layers adjacent to them. Tc was tuned by approximately 500 kelvin by varying the thicknesses of the BaTiO3 and SrTiO3 layers, revealing the essential roles of electrical and mechanical boundary conditions for nanoscale ferroelectricity. 相似文献