3,510 research outputs found
Insights into the relationship between inherent materials properties of PZT and photochemistry for the development of nanostructured silver.
Recently there has been great interest in using patterned ferroelectric
materials for the photochemical growth of metal nanostructures. Variations in
surface and sub-surface structure influence the photochemical processes. Here we
show that crystallography, and hence remnant polarization, of the ferroelectric
affects photo-deposition. The ratio of metal growth on c– and c+ domains varies
from 1 : 2 for [100] to 1 : 100 for [111]. This is shown to be dependent on the
variations in the band structu
Radiative capture reaction for Ne formation within a full three-body model
Background: The breakout from the hot Carbon-Nitrogen-Oxigen (CNO) cycles can
trigger the rp-process in type I x-ray bursts. In this environment, a
competition between and the
two-proton capture reaction is
expected.
Purpose: Determine the three-body radiative capture reaction rate for
formation including sequential and direct, resonant and
non-resonant contributions on an equal footing.
Method: Two different discretization methods have been applied to generate
Ne states in a full three-body model: the analytical transformed
harmonic oscillator method and the hyperspherical adiabatic expansion method.
The binary --O interaction has been adjusted to reproduce the known
spectrum of the unbound F nucleus. The dominant contributions to
the reaction rate have been
calculated from the inverse photodissociation process.
Results: Three-body calculations provide a reliable description of Ne
states. The agreement with the available experimental data on Ne is
discussed. It is shown that the
reaction rates computed within the two methods agree in a broad range of
temperatures. The present calculations are compared with a previous theoretical
estimation of the reaction rate.
Conclusions: It is found that the full three-body model provides a reaction
rate several orders of magnitude larger than the only previous estimation. The
implications for the rp-process in type I x-ray bursts should be investigated.Comment: 10 pages, 10 figures. Corrected versio
Screening of heterogeneous surfaces: charge renormalization of Janus particles
Nonlinear ionic screening theory for heterogeneously charged spheres is
developed in terms of a mode-decomposition of the surface charge. A far-field
analysis of the resulting electrostatic potential leads to a natural
generalization of charge renormalization from purely monopolar to dipolar,
quadropolar, etc., including mode-couplings. Our novel scheme is generally
applicable to large classes of surface heterogeneities, and is explicitly
applied here to Janus spheres with differently charged upper and lower
hemispheres, revealing strong renormalization effects for all multipoles.Comment: 2 figure
Blade loss transient dynamics analysis, volume 1. Task 1: Survey and perspective
An analytical technique was developed to predict the behavior of a rotor system subjected to sudden unbalance. The technique is implemented in the Turbine Engine Transient Rotor Analysis (TETRA) computer program using the component element method. The analysis was particularly aimed toward blade-loss phenomena in gas turbine engines. A dual-rotor, casing, and pylon structure can be modeled by the computer program. Blade tip rubs, Coriolis forces, and mechanical clearances are included. The analytical system was verified by modeling and simulating actual test conditions for a rig test as well as a full-engine, blade-release demonstration
Blade loss transient dynamics analysis, volume 2. Task 2: Theoretical and analytical development. Task 3: Experimental verification
The component element method was used to develop a transient dynamic analysis computer program which is essentially based on modal synthesis combined with a central, finite difference, numerical integration scheme. The methodology leads to a modular or building-block technique that is amenable to computer programming. To verify the analytical method, turbine engine transient response analysis (TETRA), was applied to two blade-out test vehicles that had been previously instrumented and tested. Comparison of the time dependent test data with those predicted by TETRA led to recommendations for refinement or extension of the analytical method to improve its accuracy and overcome its shortcomings. The development of working equations, their discretization, numerical solution scheme, the modular concept of engine modelling, the program logical structure and some illustrated results are discussed. The blade-loss test vehicles (rig full engine), the type of measured data, and the engine structural model are described
Photochemical growth of silver nanoparticles on c- and c+ domains on PZT thin films
The photochemical growth of silver nanoparticles on the negative domains of lead zirconate titanate thin films is reported. A sample of highly [100] orientated lead zirconate titanate, with a ratio of 30:70, that was 65−70 nm thick grown on Pt-coated MgO was poled by use of piezoresponse force microscopy to produce defined regions of surface positive and negative polarization. A comparison between the growth of silver nanoparticles on the surface of the lead zirconate titanate when illuminated with two sources of super band gap UV is given. In both cases the wavelength of illumination leads to growth on the positive domains but only illumination with a Honle H lamp, with a high photon output over 250−200 nm, caused significant growth of silver nanoparticles on the negative domain. The deposition on the negative domain is explained in terms of changed band bending due to the excitation of electrons into the conduction band, the rate of decay to the ground state, and dimensions of the ferroelectric film. The rate of deposition of silver nanoparticles on the negative domains is approximately half that on the positive domains
Multiple scattering effects in quasi free scattering from halo nuclei: a test to Distorted Wave Impulse Approximation
Full Faddeev-type calculations are performed for Be breakup on proton
target at 38.4, 100, and 200 MeV/u incident energies. The convergence of the
multiple scattering expansion is investigated. The results are compared with
those of other frameworks like Distorted Wave Impulse Approximation that are
based on an incomplete and truncated multiple scattering expansion.Comment: 7 pages, 16 figures, to be published in Phys. Rev.
Changes in volatile compounds of pork loin (fresh and marinated) with different irradiation and packaging during storage
The analysis of volatile compounds by gas chromatography- mass spectrometry after extraction by purge and trap has been used to investigate the volatile compounds of fresh and marinated pork loin after E-beam treatmet as a function of packaging type (air, vacuum and modified atmosphere), radiation dose (1 and 2 kGy) and storage temperature (4 and 8 °C). Major differences were found between fresh and marinated samples but, in general, only minor differences were found in the volatile compounds of both types of loin due to storage temperature, packaging method and doses of irradiation. It is concluded that the application of E-beam is a very useful way to extend the shelflife of fresh and marinated pork loin with no changes in the odor of the products.<br><br>Se ha utilizado la cromatografía de gases/espectrometría de masas, la extracción mediante purga y trampa para estudiar los compuestos volátiles de lomo de cerdo fresco y adobado, tratados con electrones acelerados (1 y 2 kGy) y almacenado en refrigeración (4 y 8 °C) bajo diferentes atmósferas (aire, vacío y atmósfera modificada). Se observaron diferencias importantes entre las muestras de lomo fresco y adobado pero, en general, solo pequeñas diferencias fueron observadas en algunos compuestos volátiles de ambos tipos de lomo debidas al efecto de la temperatura, tiempo de almacenamiento, tipo de atmósfera o dosis de radiación. Se ha concluido que la aplicación de electrones acelerados es una tecnología muy eficaz para ampliar la vida útil del lomo de cerdo fresco y adobado sin que se detecten cambios en el olor de los productos
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