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51.
R.J. Mcdonald A.J. Pacheco G.J. Wozniak H.H. Bolotin L.G. Moretto C. Schück S. Shih R.M. Diamond F.S. Stephens 《Nuclear Physics A》1982,373(1):54-80
Both the magnitude and alignment of the transferred angular momentum in the reaction 165Ho + 165Ho have been measured as a function of Q-value via continuum γ-ray multiplicity and anisotropy techniques. The spin transfer and the continuum γ-ray anisotropy increase throughout the quasi-elastic region. The spin transfer as a function of Q-value saturates at ~ 35?/fragment, the anisotropy peaks at a value of ~2 and then decreases to near unity for the largest Q-values. The observed anisotropies are in good agreement with predictions from an equilibrium statistical model in which thermal excitation of angular-momentum-bearing collective modes and neutron evaporation give rise to in-plane components of the angular momentum. 相似文献
52.
The effects induced by the Z-boson exchange in the hyperfine structure and Lamb shift of some fundamental bound systems is analyzed. The hfs of muonium appears as a promising test of the Weinberg-Salam theiry. 相似文献
53.
54.
Abstract
We present the results of three-dimensional time-dependent numerical simulations of incremental spin-up of a thermally stratified fluid. The fluid inside a vertical cylindrical container of radius R and height 2H is water characterized by the kinematic viscosity ν and thermal diffusivity κ. Initially, its density (temperature) varies linearly with height and is characterized by a constant buoyancy frequency N, which is proportional to the density gradient. The system undergoes an abrupt change in the rotation rate from its initial value Ωi, when the fluid is in a solid-body rotation state, to the final value Ωf. The aim of this contribution is to show the formation of columnar vortices in a high Rossby number spin-up flow. 相似文献55.
Rui Pacheco 《Geometriae Dedicata》2010,146(1):85-99
We characterize Bianchi–Bäcklund transformations of surfaces of positive constant Gauss curvature in terms of dressing actions of the simplest type on the space of harmonic maps. 相似文献
56.
This work is motivated by a problem proposed to the authors by a bakery company in Northern Spain. The objective is to design the daily routes over the week in order to minimize the total traveled distance. For reducing this total distance, some flexibility in the dates of delivery is introduced, which will cause a stock. Therefore, we study the problem under the bi-objective perspective, “minimizing” simultaneously the total traveled distance and the stock. A bi-objective mixed-integer linear model for the problem is formulated and two methodologies of solution are presented. The first one is based on a series of linked variable neighborhood searches and the second one is based on NSGA-II provided of specific operators. Numerical results showing the obtained estimated Pareto front in both cases are presented. 相似文献
57.
Galván Sergio Rubio Carlos Jesús Pacheco Solorio Gildardo Carbajal Georgina 《Journal of Global Optimization》2013,55(4):729-749
Computational Fluids Dynamics (CFD) tools guide engineers and designers to estimate the performance of new designs. However, a CFD analysis can be very time-consuming depending mainly on the grid size and domain complexity. Thus, this paper aims to describe the tools used to evaluate and compare the performance of different 3D draft tube models for reducing the time-effort needed in an optimization procedure. The results presented here, are the second part of an overall research to establish a global optimization methodology to improve the performance of an hydraulic draft tube through the inlet velocity profile. Previously, three steps of optimization methodology to minimize the energy losses were studied: the inlet velocity profile parameterization, the numerical optimization set-up and the objective function validation. In the latter step, a global optimization method called Multi Island Genetic Algorithm (MIGA) was considered, which requires a large number of iterations before producing a reliable result. This step is able to identify an efficient inlet velocity profile to minimize the energy losses through the draft tube model. However, each iteration is expensive in terms of computational time due to the need for 3D Navier–Stokes (NS) computations to evaluate each profile’s fitness. Thus, in this work the methodology attempts to accelerate the optimization process with accurate results. In order to achieve the goal, the grid size of the 3D draft tube model was minimized, resulting in a much lower computational cost. Specifically, the draft tube calculations were performed on a sequence of five different grids each having approximately twice the number of elements compared to the previous. The measurements of the sensitivity of the draft tube performance quantities to the change of the inlet velocity parameters during the process showed that, in spite of the numerical difference between its performance, the results have the same tendency. Consequently, the 3D draft tube numerical model with a minimal grid size, is reliable and left record of its capabilities for being integrated in the optimization process. 相似文献
58.
Ana C. S. Veríssimo Mrio Pacheco Artur M. S. Silva Diana C. G. A. Pinto 《Molecules (Basel, Switzerland)》2021,26(14)
The development of novel anticancer agents is essential to finding new ways to treat this disease, one of the deadliest diseases. Some marine organisms have proved to be important producers of chemically active compounds with valuable bioactive properties, including anticancer. Thus, the ocean has proved to be a huge source of bioactive compounds, making the discovery and study of these compounds a growing area. In the last few years, several compounds of marine origin, which include algae, corals, and sea urchins, have been isolated, studied, and demonstrated to possess anticancer properties. These compounds, mainly from securamines and sterols families, have been tested for cytotoxic/antiproliferative activity in different cell lines. Bioactive compounds isolated from marine organisms in the past 5 years that have shown anticancer activity, emphasizing the ones that showed the highest cytotoxic activity, such as securamines H and I, cholest-3β,5α,6β-triol, (E)-24-methylcholest-22-ene-3β,5α,6β-triol, 24-methylenecholesta-3β,5α,6β-triol, and 24-methylcholesta-3β,5α,6β-triol, will be discussed in this review. These studies reveal the possibility of new compounds of marine origin being used as new therapeutic agents or as a source of inspiration to develop new therapeutic agents. 相似文献
59.
Raiane Aparecida LopesNeves Fausto MoreiraAraujo Felipe SiqueiraPacheco Gustavo ChevitareseAzevedo Maria Auxiliadora CostaMatos Renato CamargoMatos 《Electroanalysis》2019,31(3):496-503
Sunscreen agents and in particular UV filters are compounds added in different cosmetic formulations, that has the function of preventing damage caused by sun exposition. Therefore, this paper proposes the development of a simple, fast and reliable electroanalytical method utilizing square wave voltammetry (SWV) to the determination of Benzophenone‐3 (BZ‐3), camphor 4‐methylbenzylidene (MBC) and 2‐ethylhexyl‐4‐methoxycinnamate (OMC) in cosmetic samples. The electrochemical system consisted of a cell with three electrodes: work – gold electrode modified, reference – Ag/AgCl(sat) and auxiliary – platinum, using as supporting electrolyte 4.0 mL of Britton Robinson Buffer 0.04 mol L?1 (pH=4.0), 1.0 mL of methanol and 5.50×10?4 mol L?1 of cetyltrimethylammonium bromide (CTAB). The method was validated using three commercial sunscreen samples and the results showed recovery values between 83 and 98 %. The average values found for the analysed samples were 3.49 % m/m (728 mg L?1) to BZ‐3, 0.56 % m/m (113 mg L?1) to MBC and 0.99 % m/m (208 mg L?1) to OMC. The detection (DL) and quantification (QL) limits were 0.47 mg L?1 and 1.56 mg L?1 to BZ‐3, 0.77 mg L?1 and 2.58 mg L?1 to MBC and 0.78 mg L?1 and 2.59 mg L?1 to OMC, respectively. The sunscreen protector samples were also evaluated by high‐performance liquid chromatography (HPLC) demonstrating a good correlation between the results and compared the results with allowed concentration. 相似文献
60.
Viviane Pilla Leandro P. Alves Marcos T.T. Pacheco Egberto Munin 《Optics Communications》2008,281(23):5925-5928
Thermo-optical parameters of CdSe/ZnS core-shell nanoparticles suspended in toluene were measured using a thermal lens (TL) technique. TL transient measurements were performed using the mode-mismatched dual-beam (excitation and probe) configuration. A He-Ne laser at λp = 632.8 nm was used as the probe beam and an Ar+ laser (at λe = 514.5 nm) was used as the excitation beam for studies as a function of both core size and concentration of CdSe/ZnS nanocrystals. The fraction thermal load (φ) and radiative quantum efficiencies (η) of the CdSe/ZnS were determined. Dependence on core size (∼2-5 nm) and concentration (∼0.01-0.62 mg/ml) was observed for both φ and η parameters. 相似文献