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101.
A. F.R. Rodriguez J. G. Santos L. B. Silveira A. C. Oliveira P. C. Morais O. A.C. Nunes 《The European physical journal. Special topics》2008,153(1):543-546
Photoacoustic spectroscopy (PAS) was used to investigate
samples produced from Baru (Dipteryx alata Vog.), a typical fruit from the Brazilian
Cerrado, which is considered as a good source of nutrients. The
photoacoustic (PA) spectra of samples prepared from Baru seeds present three
different absorption bands in the wavelength range 0.3–1.0 μm, named
Band-C, Band-S, and Band-L. We found that PAS can be useful for monitoring
the strong absorption of visible light by Baru's seeds constituents mainly
in the shorter wavelength measured range. This study is important from both
agricultural and commercial point of view once it introduces PAS as a
potential characterization technique allowing better control of fruit and
seed selection, storage and transportation. 相似文献
102.
The influence of the oxygen partial pressure on the properties of indium tin oxide films deposited by rf reactive magnetron sputtering has been studied. The oxygen partial pressure was varied from 3.2 × 10−4 to 1.0 × 10−3 mbar. It has been found that the 4 × 10−4 mbar of oxygen partial pressure is a critical point. When the oxygen partial pressure is lower than 4 × 10−4 mbar, the deposition rate of the films is high; the films have low transmittance and electrical resistivity; the X-ray diffraction shows that the films have a random orientation and the images of the scanning electron microscopy show that the films surface are smooth without structure. When the pressure is higher than 4 × 10−4 mbar, the deposition rate is low and does not change as the oxygen partial pressure is further increased; the transmittance and the electrical resistivity are both high; the films show the preferred orientation along the (440) direction; the films surface show a clear structure and as the pressure is increased further, the films become porous. Considering both the factor of transmittance and resistivity, the optimum oxygen partial pressure will be 3.6 × 10−4 mbar. The films prepared at this pressure have 80% transmittance and 9 × 10−4 Ω cm resistivity. 相似文献
103.
H. Kreutzmann A. Sanpera L. Santos M. Lewenstein D. Hellweg L. Cacciapuoti M. Kottke T. Schulte K. Sengstock J.J. Arlt W. Ertmer 《Applied physics. B, Lasers and optics》2003,76(2):165-172
Quasi-one-dimensional Bose–Einstein condensates (BECs) in elongated traps exhibit significant phase fluctuations even at very
low temperatures. We present recent experimental results on the dynamic transformation of phase fluctuations into density
modulations during time of flight and show the excellent quantitative agreement with the theoretical prediction. In addition
we confirm that, under our experimental conditions, in the magnetic trap density modulations are strongly suppressed even
when the phase fluctuates. We also discuss our theoretical results on control of the condensate phase by employing a time-dependent
perturbation. Our results set important limitations on future applications of BECs in precision atom interferometry and atom
optics, but at the same time suggest pathways to overcome these limitations.
Received: 17 August 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +49-511/762-3023, E-mail: Helge.Kreutzmann@ITP.uni-hannover.de 相似文献
104.
I. Josopait L. Dobrek L. Santos A. Sanpera M. Lewenstein 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):385-391
The atom optics of Bose-Einstein condensates containing a vortex of circulation one is discussed. We first analyze in detail
the reflection of such a condensate falling on an atomic mirror. In a second part, we consider a rotating condensate in the
case of attractive interactions. We show that for sufficiently large nonlinearity the rotational symmetry of the rotating
condensate is broken.
Received 16 September 2002 / Received in final form 17 November 2002 Published online 11 February 2003 相似文献
105.
Letter: Active Gravitational Mass and the Invariant Characterization of Reissner–Nordström Spacetime
We analyse the concept of active gravitational mass for Reissner-Nordström spacetime in terms of scalar polynomial invariants and the Karlhede classification. We show that while the Kretschmann scalar does not produce the expected expression for the active gravitational mass, both scalar polynomial invariants formed from the Weyl tensor, and the Cartan scalars, do. 相似文献
106.
We show that the coherent interaction between microcavity polaritons and externally stimulated acoustic phonons forms a tunable polariton superlattice with a folded energy dispersion determined by the phonon population and wavelength. Under high phonon concentration, the strong confinement of the optical and excitonic polariton components in the phonon potential creates weakly coupled polariton wires with a virtually flat energy dispersion. 相似文献
107.
We propose a new way to generate an observable geometric phase by means of a completely incoherent phenomenon. We show how to imprint a geometric phase to a system by adiabatically manipulating the environment with which it interacts. As a specific scheme, we analyze a multilevel atom interacting with a broadband squeezed vacuum bosonic bath. As the squeezing parameters are smoothly changed in time along a closed loop, the ground state of the system acquires a geometric phase. We also propose a scheme to measure such a geometric phase by means of a suitable polarization detection. 相似文献
108.
Martínez-Palou R 《Molecular diversity》2006,10(3):435-462
Summary Combinatorial methodologies have dramatically changed the chemical research and discovery process, offering an unlimited source of new molecule entities to be screened for activity. The application of microwave irradiation in Combinatorial Chemistry and high-throughput synthesis has become increasingly popular. By taking advantage of this energy source, compound libraries for lead generation can be assembled in a fraction of time required by conventional thermal heating. This review focuses on the advances in developing synthetic methodologies in microwave without polymer-supported reagents suitable for combinatorial chemistry, including the advances in microwave-assisted fluorous synthesis technology. 相似文献
109.
N.M.P. Pinto O. Frazo J.M. Baptista J.L. Santos 《Optics and Lasers in Engineering》2006,44(8):771-778
A quasi-distributed displacement sensor for structural monitoring using an optical time domain reflectometer is demonstrated. Four displacement sensing heads are placed along a standard single mode optical fibre in several locations with different intervals. Their configurations introduce power loss through the decrease of their fibre loop radius when displacement is applied. The decrease of the light intensity with displacement variation is reported. Losses of 9 dB for a 120 mm displacement with a sensitivity of 0.027 dB/mm are reported. The quasi-distributed configuration is able to address sensors with 1 m distance resolution between them. 相似文献
110.
E. Santos 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(3):531-536
A recent experiment by Brida et al. [Eur. Phys. J. D 44, 547 (2007)] is analyzed with the conclusion that the results disagree with standard quantum predictions but fit a simple
local hidden variables model. New experiments are proposed which might throw new light on the anomaly. 相似文献