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31.
Bellière V Joorst G Stephan O de Groot FM Weckhuysen BM 《The journal of physical chemistry. B》2006,110(20):9984-9990
Electron energy-loss spectroscopy (EELS) in combination with scanning transmission electron microscopy (STEM) reveals that the La enrichment at the surface of cerium-lanthanum solid solutions is an averaged effect and that segregation occurs in a mixed oxide phase. This separation occurs within a crystalline particle, where the dopant-rich phase is located at the surface of the dopant-deficient phase. The limiting structure appears to be a solid solution with a La fraction of x = 0.6 in the bulk and x = 0.75 at the surface. Up to a La fraction of 0.6, this phase will coexist with a lanthanum-type structure in different proportions depending on the dopant amount. STEM-EELS appears to be a powerful technique to clarify the existence of a multiphase system, and it shows that XRF, XPS, and XRD measure averaged results and do not show the phase complexity of the solids. 相似文献
32.
Maria Belli Stephen L. R. Ellison Ales Fajgelj Ilya Kuselman Umberto Sansone Wolfhard Wegscheider 《Accreditation and quality assurance》2007,12(8):391-398
A metrological background for the selection and use of proficiency testing (PT) schemes for a limited number N of laboratories-participants (less than 20–30) is discussed. The following basic scenarios are taken into account: (1) adequate
matrix certified reference materials (CRM) or in-house reference materials (IHRM) with traceable property values are available
for PT use as test items; (2) no appropriate matrix CRM is available, but a CRM or IHRM with traceable property values can
be applied as a spike or similar; (3) only an IHRM with limited traceability is available. The discussion also considers the
effect of a limited population of PT participants N
p on statistical assessment of the PT results for a given sample of N responses from this population. When N
p is finite and the sample fraction N/N
p is not negligible, a correction to the statistical parameters may be necessary. Scores suitable for laboratory performance
assessment in such PT schemes are compared.
Presented at the 3rd International Conference on Metrology, November 2006, Tel Aviv, Israel. 相似文献
33.
Guogang Jia M. Belli U. Sansone S. Rosamilia M. Blasi 《Journal of Radioanalytical and Nuclear Chemistry》2003,256(3):513-528
In order to evaluate the possible radiological impact to the local public and environment from a phosphogypsum stockpile, 210Po and 210Pb concentrations in river water, lagoon water, suspended matter, superficial sediment, algae and bivalves samples collected in Venice lagoon area have been investigated. The results show that the mean 210Po and 210Pb concentrations in river water are 1.42±0.36 mBq.l-1 and 1.46±0.39 mBq.l-1 with a mean 210Po/210Pb ratio of 0.98±0.17 and about 60% of them are associated with the particulate; 210Po and 210Pb contribution from the phosphogypsum stockpile to the river water is negligible. Higher 210Po (2.61-5.67 mBq.l-1) and 210Pb (1.31-3.62 mBq.l-1) concentrations in the lagoon waters have been observed if compared with the literature values. About 60% of 210Po and 210Pb are found in the soluble form with a mean 210Po/210Pb ratio of 1.79±1.47. 210Po and 210Pb concentrations in 28 out 37 sediment samples ranged from 26 to 45 Bq.kg-1 (dry weight), only 9 sediments with 210Po and 210Pb concentrations greater than 45 Bq.kg-1 are found and most of them are located 1-4 km near the phosphogypsum stockpile. The elevated 210Po and 210Pb concentrations in the sediments may be due to the contamination from the phosphogypsum stockpile. The mean 210Po/210Pb ratio (0.986±0.049) in the sediments shows that 210Po and 210Pb exist in nearly secular equilibrium. 210Po and 210Pb concentrations in algae vary with different species. The mean 210Po and 210Pb concentrations in Gracilaria compress and Ulva laetevirens which show a similar behavior, are 3.18±1.23 Bq.kg-1 and 2.42±1.26 Bq.kg-1 (fresh weight), respectively, with a mean 210Po/210Pb ratio of 1.45±0.34. The mean concentration factors with respect to the filtered water are 1096±424 for 210Po and 1299±680 for 210Pb. The mean 210Po and 210Pb concentrations in the soft part of Mytilus edulis are 23.2±9.7 Bq.kg-1 and 0.537±0.203 Bq.kg-1 (fresh weight), respectively, with a mean 210Po/210Pb ratio of 43.6±10.0. The mean concentration factors with respect to the filtered water are 8006±3351 for 210Po and 290±109 for 210Pb, showing a very high accumulation effect for 210Po. The accumulation behaviors of Cerastoderma glaucum and Tapes philippinarum for 210Po are similar to Mytilus edulis, but that for 210Pb seems less effective, corresponding to a relatively higher 210Po/210Pb ratio. The estimated committed effective doses from 210Po for the individual local public through ingestion of bivalves are in the range of 0.050-0.231 mSv.y-1. 相似文献
34.
G. Jia M. Belli U. Sansone S. Rosamilia R. Ocone S. Gaudino 《Journal of Radioanalytical and Nuclear Chemistry》2002,253(3):395-406
A new and accurate method for the determination of uranium isotopes (238U, 234U and 235U) in environmental samples by alpha-spectrometry has been developed. Uranium is preconcentrated from filtered water samples by coprecipitation with iron(III) hydroxide at pH 9-10 using an ammonia solution and the precipitate is dissolved in HNO3 and mineralized with H2O2 and HF; uranium in biological samples is ashed at 600 °C, leached with Na2CO3 solution and mineralised with HNO3, HF and H2O2; uranium in soil samples is fused with Na2CO3 and Na2O2 at 600 °C and leached with HCl, HNO3 and HF. The mineralized or leaching solution in 2M HNO3 is passed through a Microthene-TOPO (tri-octyl-phosphine oxide) column; after washing, uranium is directly eluted into a cell with ammonium oxalate solution, electrodeposited on a stainless steel disk and measured by alpha-spectrometry. The lower limits of detection of the method is 0.37 Bq.kg-1 (soil) and 0.22 mBq.l-1 (water) for 238U and 234U and 0.038 Bq.kg-1 (soil) and 0.022 mBq.l-1 (water) for 235U if 0.5 g of soil and 1 litre of water are analyzed. Five reference materials supplied by the IAEA have been analyzed and reliable results are obtained. Sample analyses show that, the 238U, 234U and 235U concentrations are in the ranges of 0.30-103, 0.49-135 and 0.02-4.82 mBq.l-1 in waters, of 1.01-7.14, 0.85-7.69 and 0.04-0.32 Bq.kg-1 in mosses and lichens, and of 25.6-53.1, 26.4-53.8 and 1.18-2.48 Bq.kg-1 in sediments. The average uranium yields for waters, mosses, lichens and sediments are 74.5±9.0%, 80.5±8.3%, 77.8±4.9% and 89.4±9.7%, respectively. 相似文献
35.
R. Bernabei P. Belli F. Cappella F. Montecchia F. Nozzoli A. d’Angelo A. Incicchitti D. Prosperi R. Cerulli C. J. Dai H. L. He H. H. Kuang J. M. Ma Z. P. Ye V. I. Tretyak 《The European Physical Journal A - Hadrons and Nuclei》2005,24(1):51-56
The results of an experimental search for spontaneous cluster decay in 127I are presented. Several possible channels have been investigated considering an exposure of 33834 kg . day collected by a large-mass highly radiopure NaI(Tl) set-up deep underground in the Gran Sasso National Laboratory of the INFN. New lower limits on the lifetime of 2410Ne, 2812Mg, 3012Mg, 3214Si, 3414Si, 4820Ca, 4921Sc cluster radioactivity in 127I have been achieved. 相似文献
36.
Belli S Buffa G Di Lieto A Minguzzi P Tarrini O Tonelli M 《Journal of Molecular Spectroscopy》2000,201(2):314-318
We studied the hyperfine components of the (J = 10-9, Kl = 9) rotational transition in the v(6) = 1 excited vibrational state of CH(3)I, using collinear infrared and mm-wave radiations. The Doppler-free double-resonance technique allowed an accurate determination of the collisional broadening parameters for all the hyperfine components. An evident dependence on the F quantum number was observed and this result is perfectly consistent with a theoretical model allowing calculations of collisional broadening and coupling for the hyperfine components. Copyright 2000 Academic Press. 相似文献
37.
M. Belli A. Scafati A. Bianconi S. Mobilio L. Palladino A. Reale E. Burattini 《Solid State Communications》1980,35(4):355-361
The X-ray Absorption Near Edge Structures (XANES) of Mn compounds at the Mn K-edge have been measured with high resolution at the Frascati Synchrotron Radiation Facility “PULS”. Molecular effects, such as “shape resonances”, have been identified in molecular complexes. Experimental evidence of solid state (or long-range order) effects have been found in spectra of simple oxides.The application of XANES for determining the local structure and chemical bonding of Mn ion in unknown compounds is discussed. 相似文献
38.
R. Bernabei P. Belli R. Cerulli F. Montecchia A. Incicchitti D. Prosperi C. J. Dai M. Angelone P. Batistoni M. Pillon 《EPJ direct》2001,3(1):1-8
In this paper the results obtained by exposing a pure liquid Xenon scintillator to 2.5 MeV neutrons are presented. In particular, the ratio of the measured amount of light from a recoil nucleus to the amount of light from an electron of the same kinetic energy has been investigated. Results substantially in agreement with previous determinations are obtained. A figure of r = 0.46 ± 0.10 is cumulatively obtained. 相似文献
39.
40.
P. Belli R. Bernabei F. Cappella R. Cerulli F.A. Danevich S. dʼAngelo M.L. Di Vacri A. Incicchitti M. Laubenstein S.S. Nagorny S. Nisi A.V. Tolmachev V.I. Tretyak R.P. Yavetskiy 《Nuclear Physics A》2011
A search for double β decay of dysprosium was realized for the first time with the help of an ultra-low background HP Ge γ detector. After 2512 h of data taking with a 322 g sample of dysprosium oxide limits on double beta processes in 156Dy and 158Dy have been established on the level of T1/2?1014–1016 yr. Possible resonant double electron captures in 156Dy and 158Dy were restricted on a similar level. As a by-product of the experiment we have measured the radioactive contamination of the Dy2O3 sample and set limits on the α decay of dysprosium isotopes to the excited levels of daughter nuclei as T1/2?1015–1017 yr. 相似文献