| 1. |
- Popov, V., et al.
(author)
-
Morphology of PZT-PMN films grown from airflow
- 2003
-
In: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 54, s. 575-584
-
Journal article (peer-reviewed)abstract
- Lead zirconate titanate-lead magnesium niobate (PZT-PMN) films with thicknesses in the range 5 to 200 mum were fabricated by deposition from airflow at room temperature. Precursor powders of PZT and PMN were mixed in a ball mill and entrained in an airflow generated by a commercial jet-mill ( Micron-Master 02-506 ). Films were grown at a rate of 1 mum/minute onto the Ni and tungsten carbide substrates exposed to the air-powder mixture. Unfired, poled PZT-PMN films provided an audio acoustic response and form translucent 20-30 mum thick layers. Full density of the air-flow deposited materials has been achieved at temperatures 450degreesC lower than that typical for ball milled bulk PZT-PMN ceramics. After sintering for 2 hours at 850degreesC PZT-PMN ceramics with relative density of 99.5%, epsilon similar to 2170, tan delta similar to 0.009 @1 kHz and acceptable piezoelectric properties was obtained. Films sintered 2 hours at 1000degreesC showed remnant polarization P-r = 26 muC/cm(2) , P-s = 36 muC/cm(2) @95 kV/cm, and 50 Hz ac electric breakdown field as high as 120-170 kV/cm. Unusual grain morphology governs improved sinterability and enhanced properties of ferroelectric ceramics. Optical and AFM micrographs revealed needle-like grains preferentially oriented parallel to the air-powder stream. As-deposited films were found to be very non-uniform across the thickness: glass-like and with tensile strain on the contact surface. This strain is released and film microcrystalline structure becomes uniform in annealed film.
|
|
| 2. |
|
|
| 3. |
- Forséni, M., et al.
(author)
-
Detection and localization of interleukin-6 in the rat middle ear during experimental acute otitis media, using mRNA in situ hybridization and immunohistochemistry
- 2001
-
In: International Journal of Pediatric Otorhinolaryngology. - 0165-5876 .- 1872-8464. ; 57:2, s. 115-121
-
Journal article (peer-reviewed)abstract
- OBJECTIVE: Otitis media is one of the most common diseases among children. A well-known sequela of acute, chronic, and secretory otitis media is tympanosclerosis. With the exception of surgery, there is no causal treatment available for this condition, which may cause hearing disabilities. This study aimed to describe the localization of interleukin (IL)-6 mRNA and its gene product in the rat middle ear during pneumococcal otitis media. IL-6 is known to be involved in inflammatory and bone remodeling processes. METHODS: Using an experimental model of pneumococcal acute otitis media, the expression of interleukin IL-6, was analyzed. Sprague-Dawley rats were sacrificed at different time points varying from 1 h to 6 days intervals after inoculation. The middle ears were analyzed by messenger RNA in situ hybridization, and by immunohistochemistry with cell-type specific antibodies directed against IL-6. RESULTS: Transcripts of IL-6 were observed only on day 1 post-inoculation, whereas the final gene product was observed at all intervals after inoculation. IL-6 was localized in the bony part of the bulla nearest to the mucosa, around mucosal vessels, and in the ciliae of the mucosal epithelium. The results demonstrated that IL-6 was synthesized locally as early as 1 h after bacterial middle ear challenge, and that although transcription could not be detected after 24 h, the cytokine product persisted for at least 5 days after the infection was introduced. CONCLUSIONS: IL-6 was shown to be produced early in the inflammatory process during induced pneumococcal otitis media in the rat. No production was seen after 24 h although the protein remained in the tissue for at least 5 days. IL-6 could initiate a differentiation of macrophages to osteoclasts and thereby participate in a bone remodeling process leading to tympanosclerosis development.
|
|
| 4. |
|
|
| 5. |
- Ryan, K.M., et al.
(author)
-
Three Dimensional Architectures of Ultra-high Density Semiconducting Nanowires Deposited on Chip
- 2003
-
In: Journal of the American Chemical Society. - 0002-7863 .- 1520-5126. ; 125:20, s. 6284-6288
-
Journal article (peer-reviewed)abstract
- We report a "clean" and fast process, utilizing supercritical carbon dioxide, for producing ultrahigh densities, up to 10(12) nanowires per square centimeter, of ordered germanium nanowires on silicon and quartz substrates. Uniform mesoporous thin films were employed as templates for the nucleation and growth of unidirectional nanowire arrays orientated almost perpendicular to a substrate surface. Additionally, these nanocomposite materials display room-temperature photoluminescence (PL), the energy of which is dependent on the diameter of the encased nanowires. The ability to synthesis ultrahigh-density arrays of semiconducting nanowires on-chip is a key step in future "bottom-up" fabrication of multilayered device architectures for nanoelectronic and optoelectronic devices.
|
|
| 6. |
- Ziegler, K., et al.
(author)
-
The synthesis of matrices of embedded semiconducting nanowires
- 2004
-
In: Faraday discussions. - : Royal Society of Chemistry (RSC). - 1359-6640 .- 1364-5498. ; 125, s. 311-326
-
Journal article (peer-reviewed)abstract
- In this work we report how single crystal nanowires can be assembled into regular arrays using mesoporous thin films to define the architecture. Mesoporous thin films were prepared by a sol-gel method. These provide films of very regular structure and dimensions. The films produced in this way have almost single crystal like structures and can also exhibit strong epitaxy to the underlying silicon substrate. The films are subjected to a supercritical fluid (SCF) environment in which a precursor is decomposed to yield nanowires of metals, semiconductors or oxides. Using these SCF conditions, pore filling is complete and the products are nanowires which are single crystals and structurally aligned in one direction. The growth mechanism of the nanowires is described and size effects discussed.
|
|
| 7. |
|
|
| 8. |
- Christlieb, Norbert, et al.
(author)
-
New Searches for R-Process Enhanced Stars
- 2001
-
In: Proceedings of "Astrophysical Ages and Times Scales", ASP Conference Series. - : Astronomical Society of the Pacific, San Francisco, U.S.A.. - 1583810838 ; , s. 298-300
-
Conference paper (other academic/artistic)abstract
- We discuss strategies for the detection of additional examples of highly r-process-enhanced, ultra-metal-poor stars, such as the two presently known examples of the class, CS~22892-052, and the newly discovered CS~31082-001. We expect that a quick, modera
|
|
| 9. |
- Christlieb, N., et al.
(author)
-
The Hamburg/ESO R-process Enhanced Star survey (HERES). I. Project description, and discovery of two stars with strong enhancements of neutron-capture elements
- 2004
-
In: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 428:3, s. 1027-1037
-
Journal article (peer-reviewed)abstract
- We report on a dedicated effort to identify and study metal-poor stars strongly enhanced in r-process elements ([r/Fe]>1 dex; hereafter r-IIstars), the Hamburg/ESO R-process Enhanced Star survey (HERES).Moderate-resolution (∼2 Å) follow-up spectroscopy has been obtained for metal-poor giant candidates selected from the Hamburg/ESO objective-prism survey (HES) as well as the HK survey to identify sharp-lined stars with [Fe/H]<-2.5 dex. For several hundred confirmed metal-poor giants brighter than B∼ 16.5 mag (most of them from theHES), ``snapshot'' spectra (R∼ 20 000; S/N ∼ 30 per pixel) are being obtained with VLT/UVES, with the main aim of finding the 2-3% r-II stars expected to be among them. These are studied in detail by means of higher resolution and higher S/N spectra. In this paper we describe a pilot study based on a set of 35 stars, including 23 from the HK survey,eight from the HES, and four comparison stars. We discovered two new r-II stars, CS 29497-004 ([Eu/Fe]=1.64± 0.22) and CS 29491-069([Eu/Fe]=1.08± 0.23). A first abundance analysis of CS 29497-004 yields that its abundances of Ba to Dy are on average enhanced by 1.5 dex with respect to iron and the Sun and match a scaled solar r-process pattern well, while Th is underabundant relative to that pattern by 0.3dex, which we attribute to radioactive decay. That is, CS 29497-004 seems not to belong to the class of r-process enhanced stars displaying an ``actinide boost'', like CS 31082-001 (Hill et al. 2002), or CS30306-132 (Honda et al. 2004b). The abundance pattern agrees well with predictions of the phenomenological model of Qian & Wasserburg.Based in large part on observations collected at the European Southern Observatory, Paranal, Chile (proposal number 68.B-0320).}
|
|
| 10. |
- Cummins, D., et al.
(author)
-
Ultrafast electrochromic windows based on redox-chromophore modified nanostructured semiconducting and conducting films
- 2000
-
In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1089-5647 .- 1520-6106 .- 1520-5207. ; 104:48, s. 11449-11459
-
Journal article (peer-reviewed)abstract
- Described is the construction of an ultrafast electrochromic window. One electrode of this window is based on a transparent nanostructured TiO2 (anatase) film (4.0 mum. thick) supported on conducting glass (F-doped tin oxide, 10 Ohm cm(-2), 0.5 mum thick) and modified by chemisorption of a monolayer of the redox chromophore bis(2-phosphonoethyl)-4,4'-bipyridinium dichloride. The other electrode is based on a transparent nanostructured SnO2 film (3.0 mum thick) supported on conducting glass (F-doped tin oxide, 10 Ohm cm-2, 0.5 mum thick) and modified by chemisorption of a monolayer of the redox chromophore [beta-(10-phenothiazyl)propoxy]phosphonic acid. The electrolyte used is LiClO4 (0.2 mol dm(-3)) in gamma -butyrolactone. The excellent performance of a 2.5 cm x 2.5 cm window over 10 000 electrochromic test cycles-switching times (coloring and bleaching) of less than 250 ms, coloration efficiency of 270 cm(2) C-1, steady-state currents (colored and bleached) of less than 6 muA cm(-2), and memory of greater than 600 s (time required for low end transmittance to increase by 5%)-suggest a practical technology.
|
|
