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81.
Lorenzo Codecasa Ruben Specogna Francesco Trevisan 《Journal of computational physics》2010,229(19):7401-7410
By exploiting the geometric structure behind Maxwell’s equations, the so called discrete geometric approach allows to translate the physical laws of electromagnetism into discrete relations, involving circulations and fluxes associated with the geometric elements of a pair of interlocked grids: the primal grid and the dual grid. 相似文献
82.
Characterization of mercury species in soils by HPLC-ICP-MS and measurement of fraction removed by diffusive gradient in thin films 总被引:2,自引:0,他引:2
The properties and behaviour of Hg depend on both the oxidation state and the chemical form: the bioavailability, toxicity, persistence and accumulation of mercury in the food web are strongly influenced by chemical speciation. The present work aims to determine the chemical forms of mercury present in soil and to evaluate the fraction of mercury in soil solution available to plants. In order to do this, we analyzed eight samples of contaminated soils with Hg concentrations ranging from 1.31 to 21.7 mg kg−1, collected from different depths (0–10 and 40–50 cm) close to an abandoned industrial site in Val Basento (southern Italy). Two innovative analytical techniques were used: HPLC–ICP-MS and diffusive gradient in thin films (DGT). The analytical procedure was validated using ERM 580-certified sediment and spiked samples in the case of HPLC–ICP-MS, and by a performance test in the case of DGT. In all samples, the only species found in soil and soil solution was MeHg+ and Hg2+. In soil, the MeHg+/Hgtot ratio ranged from 0.05% to 0.82%; total mercury in soil solution was less than 0.01% of total mercury in soil. The percentage of MeHg+ in soil solution varied considerably (from 0% to 50%), with a maximum concentration of 0.02 mg L−1. The root available concentration evaluated by DGT is comparable to the total mercury content of the soil solution measured by HPLC–ICP-MS. The DGT results suggest that all mercury in solution is available for uptake in DGT, and that mercury is supplied from soil to solution. However, for all samples the soluble and root available (DGT-labile) fractions of mercury are generally very low with respect to the total mercury concentration. This study confirmed that both HPLC–ICP-MS and DGT techniques are suitable tools for the estimation of Hg root availability and in assessing the risk from contaminated soils. 相似文献
83.
Summary Recent developments in the normal mode theory of lee cyclogenesis are presented. The topographic modifications of the most
unstable eigenmode are computed in the most general case of primitive equations and isolated topography. The basic state about
which linearization is performed is a midlatitude jet with maximum speed at tropopause level. The orographic modification
consists in a pressure dipole scaling on the Rossby deformation radius already found in previous theoretical and numerical
studies. The modifications of the statistical properties introduced by topography on the nonlinear feedback between zonal
wind and transient waves are determined using a simple quasi-geostrophic two-layer model. Systematic differences are found
to be consistent with the predictions of linear theories. A brief discussion on the limits of the linear theory is also included
Paper presented at the IV Congresso del Gruppo Nazionale per la Fisica dell'Atmosfera e dell'Oceano, June 22–24, 1987, Rome. 相似文献
84.
Using the many-body Green function technique effective operators for magix ±2 nuclei are derived. Our formulation allows a microscopic proof of the heuristically found additivity of anomalous moments. Possible deviations of the rule are quantitatively discussed. The theory is applied to206Pb,210Pb and210Po. The theoretical results are in good agreement with experiment. 相似文献
85.
A. Santarsiero G. Trevisan G. Cappiello G. Formenton E. Dell'Andrea 《Microchemical Journal》2005,79(1-2):299
In order to assess the pollutant load attributable to crematoria, a study was undertaken on the emissions from cremators sited in urban areas. This paper reports some preliminary results from the testing program on an urban cremator emission as it stands with current cremation practices in Italy. Results concern the concentration of the following parameters at the stack: total particulate matter, metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Sn, Tl, V, Zn), organic micropollutants such as dioxins (PCDDs), dibenzofurans (PCDFs), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). 相似文献
86.
T. Aziz J. L. Bailly S. Banerjee W. Bartl F. Bruyant B. Buschbeck C. Caso H. Dibon F. J. Diez-Hedo B. Epp A. Ferrando F. Fontanelli S. N. Ganguli I. V. Gorelov A. Gurtu P. Herquet J. Hrubec V. Khalatyan E. Kistenev S. Kitamura J. M. Kohli D. Kuhn J. MacNaughton P. K. Malhotra J. C. Marin S. Matsumoto I. S. Mittra L. Montanet G. Neuhofer P. Porth T. Rodrigo J. M. Salicio J. B. Singh S. Squarcia V. Stopchenko K. Takahashi U. Trevisan T. Tsurugai T. Yamagata G. Zholobov S. A. Zotkin EHS-RCBC Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,30(3):381-389
We have studied the inclusive production of strange meson and baryon resonances in 360 GeV/cpp interactions. Cross sections forK *+(892) andK *?(892) are estimated to be 4.42±0.62 mb and 2.54±0.47 mb respectively and those for∑ +(1385) and∑ ?(1385) are 0.67±0.11 mb and 0.26±0.07 mb respectively. Longitudinal and transverse momentum distributions forK *(892) and Σ(1385) are presented, as well as for their decay productsK 0 and Λ. An estimation is given on theK *(1430) and∑ *(1915) productions. 相似文献
87.
M. Barth E. A. De Wolf P. Theocharopoulos C. Caso H. Drevermann Y. Goldschmidt-Clermont R. T. Ross R. Contri S. Squarcia U. Trevisan J. F. Baland J. Beaufays F. Grard L. Gatignon A. Stergiou R. T. Van de Walle P. V. Chliapnikov A. B. Fenyuk I. A. Gritsaenko V. M. Kubic T. G. Makharadze Y. L. Petrovikh 《Zeitschrift fur Physik C Particles and Fields》1984,26(1):1-12
Nucleon structure functions obtained from neutrino and anti-neutrino scattering on iron nuclei at high energies (E v =30 to 250 GeV) are presented. These results are compared with the results of other lepton-nucleon scattering experiments. The structure functions are used to test the validity of the Gross-Llewellyn-smith sum rule, which measures the number of valence quarks in the nucleons, and to obtain leading and second order QCD fits. 相似文献
88.
J. L. Bailly F. Bruyant B. Buschbeck C. Caso Y. Chiba H. Dibon F. J. Diez-Hedo B. Epp A. Ferrando F. Fontanelli S. N. Ganguli V. G. Gavrjusev P. Girtler R. Hamatsu P. Herquet T. Hirose J. Hrubec Y. Iga Yu. Ivanyshevkov L. Jenik N. Khalatyan E. Kistenev T. Kobayashi J. M. Kohli S. Krasznovszky V. Kubik J. MacNaughton P. K. Malhotra L. Montanet G. Neuhofer P. Porth T. Rodrigo J. M. Salicio J. B. Singh S. Squarcia K. Sudhakar K. Takahashi L. A. Tikhonova U. Trevisan T. Tsurugai G. Zholobov S. A. Zotkin EHS-RCBC Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,35(3):295-300
Using a quark-diquark fragmentation model, in which either the Field-Feynman or the Lund model is coupled with a quark-diquark distribution function, we study transverse momentum distributions,p T, for the inclusive reactionspp→hadron +anything at 360 GeV/c. We find that a primordial mean transverse momentum 〈k T〉?0.4 GeV/c can well reproduce thep T 2 distributions of charged hadrons, π0,K s 0 , Λ0,K * and Σ* and the Feynmanx?p T correlations. We confirm that a diquark in a proton plays an important rôle in reproducing thex?p T correlation of Λ0. 相似文献
89.
J. L. Bailly W. Bartl B. Buschbeck C. Caso H. Dibon F. J. Diez-Hedo B. Epp A. Ferrando F. Fontanelli S. N. Ganguli I. V. Gorelov A. Gurtu R. Hamatsu Ph. Herquet J. Hrubec Y. Iga N. Khalatyan E. Kistenev S. Kitamura J. M. Kohli D. Kuhn J. MacNaughton P. K. Malhotra S. Matsumoto I. S. Mittra L. Montanet G. Neuhofer N. Oshima P. Porth R. Raghavan T. Rodrigo J. M. Salicio J. B. Singh S. Squarcia V. Stopchenko K. Takahashi U. Trevisan T. Tsurugai T. Yamagata G. Zholobov S. A. Zotkin EHS-RCBC Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,35(3):309-316
In a study of proton-proton interactions at \(\sqrt s = 26GeV\) , inclusive distributions of single pions and systems of pions of various charge combinations are presented, as well as the production ratio obtained in association with various trigger particles. The results are compared to current phenomenological models in an attempt to understand multiparticle productions in hadron collisions. 相似文献
90.
Bais D Trevisan A Lapasin R Partal P Gallegos C 《Journal of colloid and interface science》2005,290(2):546-556
Rheometrical techniques can be profitably used for polysaccharide matrices in order to evaluate their suitability for the preparation of stable cosmetic O/W emulsions. In particular, the rheological properties of aqueous scleroglucan systems were investigated under continuous and oscillatory shear conditions in a polymer concentration range (0.2-1.2% w/w) embracing the sol/gel transition. The effects due to the addition of two different surfactants (up to 10% w/w) were examined at constant polymer concentration (0.4% w/w). The selected additives are a nonionic polymeric siliconic surfactant (dimethicone copolyol) and a cationic surfactant (tetradecyltrimethylammonium bromide), respectively. Polysaccharide-surfactant interactions leading to complex formation were detected also through rheology. The combined action of both nonionic and cationic surfactants in the polymer solution was examined at two different surfactant concentration levels (5 and 10% w/w), demonstrating the beneficial effects produced on the mechanical properties of the polymer matrix by the coexistence of both surfactants. Such beneficial effects are confirmed by the stability and rheology shown by the emulsions prepared. In this way, the results point out the good agreement between the rheology of the continuous phase and the final characteristics of the emulsion obtained. 相似文献