Influence of metal organic chemical vapour deposition growth conditions on vibrational and luminescent properties of ZnO nanorods

Producción CientíficaA detailed optical characterization by means of micro Raman and cathodoluminescence spectroscopy of catalyst-free ZnO nanorods grown by atmospheric-metal organic chemical vapour deposition has been carried out. This characterization has allowed correlating the growth conditions, in particular the precursors partial-pressures and growth time, with the optical properties of nanorods. It has been shown that a high Zn supersaturation can favor the incorporation of nonradiative recombination centers, which can tentatively be associated with ZnI-related defects. Characterization of individual nanorods has evidenced that ZnI-related defects have a tendency to accumulate in the tip part of the nanorods, which present dark cathodoluminescence contrast with respect to the nanorods bottom. The effect of a ZnO buffer layer on the properties of the nanorods has been also investigated, showing that the buffer layer improves the luminescence efficiency of the ZnO nanorods, revealing a significant reduction of the concentration of nonradiative recombination centers.Ministerio de Ciencia e Innovación (Projects MAT2007-66129, MAT-2010-20441-C02, MAT-2010-16116, and TEC2011-28076-C02-02)Generalitat Valenciana (Prometeo/2011-035 and ISIC/2012/008, Institute of Nanotechnologies for Clean Energies

Atividade inseticida do óleo essencial de Schinus terebinthifolius Raddi sobre Acanthoscelides obtectus Say e Zabrotes subfasciatus Boheman.

Este trabalho teve como objetivo avaliar o efeito do óleo essencial de folhas de Schinus terebinthifolius sobre Acanthoscelides obtectus e Zabrotes subfasciatus. O óleo essencial foi obtido por arraste a vapor e dissolvido em acetona, nas diluições 10-2; 10-3; 10-4; 10-5; 10-6; 10-7 e 10-8 (v/v). Adicionou-se 1,0 mL destas soluções a placas de Petri de 9,0 cm de diâmetro, contendo papel de filtro esterilizado. Como controle, utilizou-se 1,0 mL de acetona. Após a evaporação da acetona, cinco insetos adultos foram colocados por placa, em quatro repetições, em delineamento inteiramente casualizado. Avaliou-se a mortalidade dos insetos após 24 e 48 horas. Obteve-se 100% de mortalidade de A. obtectus em 48 horas nas diluições do óleo 10-2; 10-3; 10-4; 10-5; 10-6; 10-7. No controle, a mortalidade atingiu 30% em 48 horas. Com relação a Z. subfasciatus, apenas as diluições 10-2 e 10-3 provocaram 100% de mortalidade, após 24 e 48 horas, enquanto no controle obteve-se 25% de mortalidade, em 48 horas. Este estudo evidencia a atividade inseticida do óleo essencial de S. terebinthifolius, o que sugere o seu potencial no controle dos insetos estudados.bitstream/CPAF-RO-2009-09/12172/1/bpd48_oleoessenciall.pd

Atividade inseticida do extrato etanólico de Momordica charantia L. sobre a broca-do-café Hypothenemus hampei (FERRARI) (Coleoptera: Scolytidae).

A primeira autora, Lunalva A. P. Sallet, é bolsista CNPq da Embrapa Rondônia

Polarity in GaN and ZnO: Theory, measurement, growth, and devices

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Rev. 3, 041303 (2016) and may be found at https://doi.org/10.1063/1.4963919.The polar nature of the wurtzite crystalline structure of GaN and ZnO results in the existence of a spontaneous electric polarization within these materials and their associated alloys (Ga,Al,In)N and (Zn,Mg,Cd)O. The polarity has also important consequences on the stability of the different crystallographic surfaces, and this becomes especially important when considering epitaxial growth. Furthermore, the internal polarization fields may adversely affect the properties of optoelectronic devices but is also used as a potential advantage for advanced electronic devices. In this article, polarity-related issues in GaN and ZnO are reviewed, going from theoretical considerations to electronic and optoelectronic devices, through thin film, and nanostructure growth. The necessary theoretical background is first introduced and the stability of the cation and anion polarity surfaces is discussed. For assessing the polarity, one has to make use of specific characterization methods, which are described in detail. Subsequently, the nucleation and growth mechanisms of thin films and nanostructures, including nanowires, are presented, reviewing the specific growth conditions that allow controlling the polarity of such objects. Eventually, the demonstrated and/or expected effects of polarity on the properties and performances of optoelectronic and electronic devices are reported. The present review is intended to yield an in-depth view of some of the hot topics related to polarity in GaN and ZnO, a fast growing subject over the last decade

Social connections predict brain structure in a multidimensional free-ranging primate society

Reproduction and survival in most primate species reflects management of both competitive and cooperative relationships. Here, we investigated the links between neuroanatomy and sociality in free-ranging rhesus macaques. In adults, the number of social partners predicted the volume of the mid–superior temporal sulcus and ventral-dysgranular insula, implicated in social decision-making and empathy, respectively. We found no link between brain structure and other key social variables such as social status or indirect connectedness in adults, nor between maternal social networks or status and dependent infant brain structure. Our findings demonstrate that the size of specific brain structures varies with the number of direct affiliative social connections and suggest that this relationship may arise during development. These results reinforce proposed links between social network size, biological success, and the expansion of specific brain circuits

Analysis of a sprint ski race and associated laboratory determinants of world-class performance

This investigation was designed to analyze the time-trial (STT) in an international cross-country skiing sprint skating competition for (1) overall STT performance and relative contributions of time spent in different sections of terrain, (2) work rate and kinematics on uphill terrain, and (3) relationships to physiological and kinematic parameters while treadmill roller ski skating. Total time and times in nine different sections of terrain by 12 world-class male sprint skiers were determined, along with work rate and kinematics for one specific uphill section. In addition, peak oxygen uptake (VO2peak), gross efficiency (GE), peak speed (Vpeak), and kinematics in skating were measured. Times on the last two uphill and two final flat sections were correlated to overall STT performance (r = ~−0.80, P < 0.001). For the selected uphill section, speed was correlated to cycle length (r = −0.75, P < 0.01) and the estimated work rate was approximately 160% of peak aerobic power. VO2peak, GE, Vpeak, and peak cycle length were all correlated to STT performance (r = ~−0.85, P < 0.001). More specifically, VO2peak and GE were correlated to the last two uphill and two final flat section times, whereas Vpeak and peak cycle length were correlated to times in all uphill, flat, and curved sections except for the initial section (r = ~−0.80, P < 0.01). Performances on uphill and flat terrain in the latter part were the most significant determinants of overall STT performance. Peak oxygen uptake, efficiency, peak speed, and peak cycle length were strongly correlated to overall STT performance, as well as to performance in different sections of the race