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131.
P Moras PM Sheverdyaeva C Carbone D Topwal L Ferrari G Bihlmayer S Ouazi S Rusponi A Lehnert H Brune 《J Phys Condens Matter》2012,24(33):335502
We examined by low-energy electron diffraction and scanning tunneling microscopy the surface of thin Cu films on Pt(111). The Cu/Pt lattice mismatch induces a moiré modulation for films from 3 to about 10?ML thickness. We used angle-resolved photoemission spectroscopy to examine the effects of this structural modulation on the electronic states of the system. A series of hexagonal- and trigonal-like constant energy contours is found in the proximity of the Cu(111) zone boundaries. These electronic patterns are generated by Cu sp-quantum well state replicas, originating from multiple points of the reciprocal lattice associated with the moiré superstructure. Layer-dependent strain relaxation and hybridization with the substrate bands concur to determine the dispersion and energy position of the Cu Shockley surface state. 相似文献
132.
133.
P Orlandi C Ferrari M John Strain A Canciamilla F Morichetti M Sorel P Bassi A Melloni 《Optics letters》2012,37(17):3669-3671
We present the design and the fabrication of compact tunable silicon-on-insulator bandpass filters based on the integration of a Mach-Zehnder interferometer with ring resonators and activated via thermo-optic phase shifters. The proposed architecture provides wide filter bandwidth tunability from 10% to 90% of the free spectral range preserving the filter off-band rejection. Possible applications are channel subset selection in wavelength division multiplexing optical systems, adaptive filtering to signal bandwidth, and reconfigurable filters for gridless networking. 相似文献
134.
Ilaria Bonaduce Leslie Carlyle Maria Perla Colombini Celia Duce Carlo Ferrari Erika Ribechini Paola Selleri Maria Rosaria Tiné 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1055-1066
This article presents a multi-analytical approach to investigating the drying, polymerisation and oxidative degradation of
linseed oil, which had undergone various treatments known to be undertaken during the nineteenth century in preparation for
painting. The oil was mechanically extracted from the same seed lot then processed by different methods: water washing, heat
treatments, and the addition of driers, with and without heat. The oil was prepared in 1999 within the framework of the MOLART
project. We compared thermogravimetric analysis (TG), which yields macromolecular information, with gas-chromatography mass-spectrometry
(GC/MS) and direct exposure mass spectrometry (DE-MS), which provide molecular information. This comparison enabled us to
elucidate the role of pre-treatment on the composition of the oil. TG and oxygen uptake curves registered at a constant temperature
helped us to identify the different physical behaviour of the oil samples, thus highlighting the presence of hydrolysed, oxidised
and crosslinked fractions, as a consequence of the different pre-treatments. GC/MS was used to characterise the soluble and
non-polymeric fraction of the oil, to calculate the ratios of palmitic to stearic acid (P/S), and azelaic to palmitic acid
(A/P), and to further evaluate the effects of oil pre-treatments. DE-MS using chemical ionisation with CH4, enabled us to establish the chemical composition of the oil in different stages of ageing. DE-MS proved to be a useful tool
for a simultaneous semi-quantitative characterisation of the free fatty acids, monoglycerids, diglycerides and triglycerides
present in each sample. The combination of thermal analysis with GC/MS and DE-MS enabled a model to be developed, which unravelled
how oil pre-treatments produce binders with different physical–chemical qualities. 相似文献
135.
New opportunities for the enhanced NAA services through the research reactor coalitions and networks
Danas Ridikas Pablo Adelfang Kevin Alldred Marta Ferrari 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):329-334
Although the number of research reactors (RRs) is steadily decreasing, more than half of the operational RRs are still heavily
underutilized, and in most cases, underfunded. The decreasing and rather old fleet of RRs needs to ensure the provision of
useful services to the community, in some cases with adequate revenue generation for reliable, safe and secure facility management
and operations. Enhancement of low and medium power research reactor (RR) utilization is often pursued by increasing the neutron
activation analysis (NAA) activities. In this paper we will present the strategy and concrete actions how NAA as one of the
most popular RR applications can contribute to the above goals in particular through (a) RR coalitions and networks, (b) implementation
of automation in different stages of NAA, (c) QA/QC, including skills improvement of involved personnel, (d) dedicated proficiency
tests performed by a number of targeted analytical laboratories. We also show that despite the IAEA’s efforts, some of the
NAA laboratories still perform badly in proficiency tests, do not have formal QA/QC procedures implemented, have not implemented
automation to process large number of samples or lack of clear marketing strategies. Some concrete actions are proposed and
outlined to address these issues in the near future. 相似文献
136.
A. Minguzzi G. Ferrari Y. Castin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):49-55
We describe the excitation spectrum of a two-component neutral Fermi gas with attractive interactions in the superfluid phase
at finite temperature by deriving a suitable Random-Phase approximation in the collisionless regime with the technique of
functional derivatives. The obtained spectrum for the homogeneous gas at small wavevectors contains the Bogoliubov-Anderson
phonon and is essentially different from the spectrum predicted by the static Bogoliubov theory, which instead shows an unphysically
large response. We adapt the results for the homogeneous system to obtain the dynamic structure factor of a harmonically confined
superfluid and we identify in the spectrum a unique feature of the superfluid phase.
Received 28 March 2001 相似文献
137.
G. D''Angelo G. Tripodo A. Bartolotta G. Carini A. Fontana M. Montagna F. Rossi M. Ferrari F. Terki 《Journal of Non》2001,280(1-3):222-227
Low-temperature specific heat measurements have been performed in porous silica xerogels with densities varying from 670 to 1730 kg m−3 to study the low-energy vibrational dynamics. The specific heat, Cp, shows a bump in the temperature range above 4 K, when reported in a plot of Cp/T3 against the temperature, T. The bump is almost independent of the sample density and is close to the boson peak observed in melt-quenched amorphous silica (a-SiO2). At temperatures <4 K, an additional contribution to that predicted by the Debye theory is observed. It follows an approximately linear temperature dependence (Cexc=aT1+v, v being equal to about 0.25). In the xerogel with the largest density, specific heat of about a factor 5 larger than that of a-SiO2 is measured, which increases with decreasing sample density. By comparison with the corresponding properties of a-SiO2, we conclude that the disorder introduced by the presence of pores does not measurably affect the excess density of vibrational states in a frequency range of the boson peak (BP), but increases the density of the two-level systems (TLS). 相似文献
138.
Christophe Ferrari Agnes Roche Veronique Jacob Panayotis Foster Patrick Baussand 《国际化学动力学杂志》1996,28(8):609-614
The rate constants of the isopropyl acetate, n-propyl acetate, isopropenyl acetate, n-propenyl acetate, n-butyl acetate, and ethyl butyrate reactions with OH radicals were determined in purified air under atmospheric conditions, at 750 torr and (295 ± 2) K. A relative rate experimental method was used; n-heptane, n-octane, and n-nonane were the reference compounds, with, respectively, rate constants for the reaction with OH of 7.12 × 10−12, 8.42 × 10−12, and 9.70 × 10−12 molecule−1 cm3s−1. The following rate constants were obtained in units of 10−12 molecule−1 cm3s−1; isopropyl acetate, (3.12 ± 0.29); n-propyl acetate, (1.97 ± 0.24); isopropenyl acetate, (62.53 ± 1.24); n-propenyl acetate, (24.57 ± 0.24); n-butyl acetate, (3.29 ± 0.35); and ethyl butyrate, (4.37 ± 0.42). Tertiary butyl acetate has a low reactivity with OH radicals (<1 × 10−12 molecule−1 cm3s−1). © 1996 John Wiley & Sons, Inc. 相似文献
139.
Nonlinear Dynamics - Vibration experiments are carried out on a slightly corrugated circular cylindrical shell made of polyethylene terephthalate fabric. The shell is liquid-filled, it is... 相似文献
140.