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191.
192.
E. R. Schmid 《Mikrochimica acta》1980,73(5-6):504-504
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Wolfgang G. Kreyling Pratim Biswas Maria E. Messing Neil Gibson Marianne Geiser Alexander Wenk Manoranjan Sahu Knut Deppert Izabela Cydzik Christoph Wigge Otmar Schmid Manuela Semmler-Behnke 《Journal of nanoparticle research》2011,13(2):511-524
The intensive use of nano-sized titanium dioxide (TiO2) particles in many different applications necessitates studies on their risk assessment as there are still open questions on their safe handling and utilization. For reliable risk assessment, the interaction of TiO2 nanoparticles (NP) with biological systems ideally needs to be investigated using physico-chemically uniform and well-characterized NP. In this article, we describe the reproducible production of TiO2 NP aerosols using spark ignition technology. Because currently no data are available on inhaled NP in the 10?C50 nm diameter range, the emphasis was to generate NP as small as 20 nm for inhalation studies in rodents. For anticipated in vivo dosimetry analyses, TiO2 NP were radiolabeled with 48V by proton irradiation of the titanium electrodes of the spark generator. The dissolution rate of the 48V label was about 1% within the first day. The highly concentrated, polydisperse TiO2 NP aerosol (3?C6 × 106 cm?3) proved to be constant over several hours in terms of its count median mobility diameter, its geometric standard deviation, and number concentration. Extensive characterization of NP chemical composition, physical structure, morphology, and specific surface area was performed. The originally generated amorphous TiO2 NP were converted into crystalline anatase TiO2 NP by thermal annealing at 950 °C. Both crystalline and amorphous 20-nm TiO2 NP were chain agglomerated/aggregated, consisting of primary particles in the range of 5 nm. Disintegration of the deposited TiO2 NP in lung tissue was not detectable within 24 h. 相似文献
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Schmid JH Ibrahim M Cheben P Lapointe J Janz S Bock PJ Densmore A Lamontagne B Ma R Ye WN Xu DX 《Optics letters》2011,36(11):2110-2112
We demonstrate, by experiment and numerical calculations, temperature-independent subwavelength grating waveguides with a periodic composite core composed of alternating regions of silicon and SU-8 polymer. The polymer has a negative thermo-optic (TO) material coefficient that cancels the large positive TO effect of the silicon. Measurements and Bloch mode calculations were carried out over a range of silicon-polymer duty ratios. The lowest measured TO coefficient at a wavelength of 1550 nm is 1.8×10(-6) K(-1); 2 orders of magnitude smaller than a conventional silicon photonic wire waveguide. Calculations predict the possibility of complete cancellation of the silicon waveguide temperature dependence. 相似文献
195.
A. Gorelov J.A. Behr D. Melconian M. Trinczek P. Dubé O. Häusser U. Giesen K.P. Jackson T. Swanson J.M. D'Auria M. Dombsky G. Ball L. Buchmann B. Jennings J. Dilling J. Schmid D. Ashery J. Deutsch W.P. Alford D. Asgeirsson W. Wong B. Lee 《Hyperfine Interactions》2000,127(1-4):373-380
Laser trapping and cooling techniques are now being applied to the study of nuclear β-decay at several labs. A magneto-optical
trap (MOT) provides a localized source of atoms suspended in space, so the low-energy recoiling nuclei can freely escape and
be detected in coincidence with the β. This allows reconstruction of the neutrino momentum, and the deduction of the β-v correlation in a more direct fashion than previously possible. In addition, the nuclei can be polarized by atomic techniques,
opening a new class of spin correlation measurements to test the degree to which parity is maximally violated in the weak
interaction. Our present experiment has detected several hundred thousand recoil-β+ coincidences from the 0+ → 0+ pure Fermi decay of 38mK, produced at the on-line isotope separators TISOL and ISAC at TRIUMF. Our goal is to set constraints on non-Standard Model
scalar bosons competitive with high-energy colliders and more conventional β-v correlation experiments.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Monatshefte für Mathematik - 相似文献
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