Nature of the green luminescent center in zinc oxide

EPR, optical absorption, and photoluminescence spectroscopies are used to characterize a wide range of different ZnO phosphor powders. A good correlation is generally observed between the 510-nm green emission intensity and the density of paramagnetic isolated oxygen vacancies. Both quantities are found to peak at a free-carrier density of about 1.4x10{sup 18}cm{sup -3}. The green emission intensity can be strongly influenced by free-carrier depletion at the particle surface, especially for small particles and/or low doping. The data suggest that the green PL in ZnO phosphors is due to recombination of electrons in singly occupied oxygen vacancies with photoexcited holes in the valence band

Omega-3 Fatty Acids from Fish Oil Lower Anxiety, Improve Cognitive Functions and Reduce Spontaneous Locomotor Activity in a Non-Human Primate

Omega-3 (ω3) polyunsaturated fatty acids (PUFA) are major components of brain cells membranes. ω3 PUFA-deficient rodents exhibit severe cognitive impairments (learning, memory) that have been linked to alteration of brain glucose utilization or to changes in neurotransmission processes. ω3 PUFA supplementation has been shown to lower anxiety and to improve several cognitive parameters in rodents, while very few data are available in primates. In humans, little is known about the association between anxiety and ω3 fatty acids supplementation and data are divergent about their impact on cognitive functions. Therefore, the development of nutritional studies in non-human primates is needed to disclose whether a long-term supplementation with long-chain ω3 PUFA has an impact on behavioural and cognitive parameters, differently or not from rodents. We address the hypothesis that ω3 PUFA supplementation could lower anxiety and improve cognitive performances of the Grey Mouse Lemur (Microcebus murinus), a nocturnal Malagasy prosimian primate. Adult male mouse lemurs were fed for 5 months on a control diet or on a diet supplemented with long-chain ω3 PUFA (n = 6 per group). Behavioural, cognitive and motor performances were measured using an open field test to evaluate anxiety, a circular platform test to evaluate reference spatial memory, a spontaneous locomotor activity monitoring and a sensory-motor test. ω3-supplemented animals exhibited lower anxiety level compared to control animals, what was accompanied by better performances in a reference spatial memory task (80% of successful trials vs 35% in controls, p<0.05), while the spontaneous locomotor activity was reduced by 31% in ω3-supplemented animals (p<0.001), a parameter that can be linked with lowered anxiety. The long-term dietary ω3 PUFA supplementation positively impacts on anxiety and cognitive performances in the adult mouse lemur. The supplementation of human food with ω3 fatty acids may represent a valuable dietary strategy to improve behavioural and cognitive functions

Efficient Process for Direct Atomic Layer Deposition of Metallic Cu Thin Films Based on an Organic Reductant

The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 339478. Acronym LAYERENG-HYBMAT. | openaire: EC/FP7/339478/EU//LAYERENG-HYBMATWe report a promising approach to use an organic reductant for in situ atomic layer deposition (ALD) of metallic copper films. The process is based on sequentially pulsed precursors copper acetyl acetonate (acac), water, and hydroquinone (HQ) and yields crystalline copper films at temperatures as low as <200 °C with an appreciably high deposition rate of ∼2 Å/cycle. Deposition parameters are explored for the process m × [n × (Cu(acac)2-H2O)-HQ] with several values of m and n, keeping m×n fixed to 500. The films are found crystalline with metallic copper as the main phase, but different trace amounts of Cu2O are observed when the HQ pulse frequency decreases below 1/5. The as-deposited copper films are shiny and specularly reflecting and show metallic-type electrical conductivity. The absolute resistivity of the films estimated at room temperature is in the order of 2-5 µO cm, having a sizable contribution, with 0.5 µO cm from residual resistivity as a result of impurities and/or imperfections. We believe thatthe new process could yield benefits in interconnect applications.Peer reviewe