Universidad de Sonora

About: Universidad de Sonora is a education organization based out in Hermosillo, Mexico. It is known for research contribution in the topics: Population & Thermoluminescence. The organization has 4432 authors who have published 5997 publications receiving 70780 citations. The organization is also known as: University of Sonora.

Acoustic band structure of periodic elastic composites.

Abstract: We present the first full band-structure calculations for periodic, elastic composites. For transverse polarization of the vibrations we obtain a ``phononic'' band gap which extends throughout the Brillouin zone. A complete acoustic gap or a low density of states should have important consequences for the suppression of zero-point motion and for the localization of phonons, and may lead to improvements in transducers and in the creation of a vibrationless environment.

Particle Size Effects on the Electrochemical Performance of Copper Oxides toward Lithium

Abstract: The electrochemical reactivity of tailor-made or CuO powders prepared according to the polyol process was tested in rechargeable Li cells. To our surprise, we demonstrated that CuO, a material well known for primary Li cells, and could reversibly react with 1.1 Li and 2 Li ions per formula unit, respectively, leading to reversible capacities as high as 400 mAh/g in the 3-0.02 V range. The ability of copper oxide-based Li cells to retain their capacity upon numerous cycles was found to be strongly dependent on the particle size, and the best results (100% of the total capacity up to 70 cycles) were obtained with 1 μm and CuO particles. Ex situ transmission electron microscopy data and in situ X-ray experiments show that the reduction mechanism of by Li first involved the formation of Cu nanograins dispersed into a lithia matrix, followed by the growth of an organic coating that partially dissolved upon the subsequent charge while Cu converted back to nanograins. We believe that the key to the reversible reactivity mechanism of copper oxides or other transition metal oxides toward Li is the electrochemically driven formation of highly reactive metallic nanograins during the first discharge, which enables the formation-decomposition of upon subsequent cycles. © 2001 The Electrochemical Society. All rights reserved.

A Global Look at Time: A 24-Country Study of the Equivalence of the Zimbardo Time Perspective Inventory

Abstract: In this article, we assess the structural equivalence of the Zimbardo Time Perspective Inventory (ZTPI) across 26 samples from 24 countries (N = 12,200). The ZTPI is proven to be a valid and reliable index of individual differences in time perspective across five temporal categories: Past Negative, Past Positive, Present Fatalistic, Present Hedonistic, and Future. We obtained evidence for invariance of 36 items (out of 56) and also the five-factor structure of ZTPI across 23 countries. The short ZTPI scales are reliable for country-level analysis, whereas we recommend the use of the full scales for individual-level analysis. The short version of ZTPI will further promote integration of research in the time perspective domain in relation to many different psycho-social processes.