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Nitrous oxide (N2O) is an important greenhouse gas. Emissions of this gas are generated by the combustion of fossil fuels, mainly in the transportation sector worldwide. Biofuel is a promising alternative instead of diesel considering that it allows a reduction on the emissions of polluting gases. In Brazil, there is a large program on the use of biofuels, which according to the Intergovernmental Panel on Climate Change (IPCC) reduces greenhouse gas emissions. This work shows the N2O emissions resulting from combustions of diesel/beef tallow biodiesel blends of B7, B15, B20, B25, B35, and B50. In parallel, another experiment was done with fuel sample adopted by a bus fleet from Sao Paulo using blends comprising 10% of sugarcane diesel in diesel (CD10) and blends with beef tallow biodiesel of CD10: CD-B15, CD-B20, CD-B25, CD-B35, and CD-B50. The photoacoustic spectroscopy technique coupled to a quantum cascade laser (QCL) was used to detect N2O. Concentrations of the emissions were detected in the range of 5.3 to 7.4 ppmv for diesel/beef tallow biodiesel blends combustion and in the range of 4.3 to 11.0 ppmv for diesel/sugar cane diesel/beef tallow biodiesel blends combustion. The technique used was very sensitive and selective to identify and determine the emission concentrations of N2O.

The COP 21 (21st Conference of Parties) held in 2015, in Paris, proposed to limit the average global temperature increase at a maximum of 2 °C. Brazil has programs for reducing GHGs through Intended Nationally Determined Contributions (INDC) in the energy sector. Between 2012 and 2015 Brazil faced a drastic reduction in rainfall volumes which led to a decrease in hydroelectric generation, then offset by thermoelectric generation, with an increase in its emissions. The objective herein is to review the expansion in the use of renewable energy sources to meet the INDC's goals, given the future vulnerability of the Brazilian electricity matrix. The use of renewable energy such as wind, solar and co-generation for electric production has grown considerably in Brazil. The growth of wind power generation was a result of the investment initiated by these public policies to promote the Brazilian wind industry through the Programme of Incentives for Alternative Electricity Sources (PROINFA), the increase of wind generation in both South and Northeast subsystems. Wind energy is aimed to reach 20 GW of electricity production by 2024. The public and private initiatives in the solar energy segment reflect, first and foremost, upon the creation of a solar photovoltaic industry in the country and, from there, a consequent expansion of this energy's usage. The cogeneration processes have contributed to industries in a positive way, both in supplying electricity for internal energy plants' demands as well as those of the national electric system. Therefore, the diversification of the energy matrix is a goal to be achieved. The use of new renewable energy sources and the maintenance of investments in hydropower are part of the Brazilian strategy to turn its electric matrix less vulnerable climate change consequences..

The thermal diffusivity and luminescence quantum efficiency of Eu in low silica calcium aluminosilicate glasses have been measured using the mode mismatch Thermal Lens technique (TL). Two different concentrations were studied: 0.5 and 5 (wt%) of Eu 2 O 3 . Our results show that the thermal diffusivity is independent of Eu 2 O 3 concentration while the luminescence quantum efficiency decreased with the increasing in the doping concentration.

We present an investigation of beryllium doping selectivity in InGaP layers grown by chemical beam epitaxy on pre-patterned substrates. We observed a resistivity of 3.1×10 −2 and 4.5×10 −2 Ω cm for (1 1 1)A planes with the growth at 500°C and 540°C, respectively. The layers on (0 0 1) planes show a resistivity of 8.9×10 −1 Ω cm with the growth at 500°C, being essentially undoped with the growth at 540°C ⋅ We show how this strong doping selectivity can be explained by Be 3 P 2 cluster formation growth, which depends on growth temperature and planar crystalline structure.

This work reports the role of alpha particles generated by Americium (241Am) stripes placed inside the discharge channel in providing a bias ionized background plasma before, during, and after the discharge of the N2 TE UV laser (337.1 nm) circuit. The enhancement in stimulated radiation output characteristics in terms of gas pressure, charging voltage, and pulse width, with and without alpha particles, are shown. The increased laser yield is interpreted qualitatively through plasma impedance in the discharge circuit.

Effects of He + ion irradiation in InGaP/GaAs multilayered laser structures with 7 nm InGaAs quantum wells (QWs) have been investigated. Two versions of the ion irradiation were performed: (I) into the complete structure, and (II) into the structure after a removing the p ++ -GaAs contact layer. In case I, two-energy He + ion implantation includes a 20 keV irradiation for an isolation of p ++ -GaAs and a 170 keV irradiation for the isolation of the p-InGaP cladding layer. In case II, a one-energy (100 keV) implantation is used. Front-side photoluminescence studies show an appearance of the QW emission peak at 9260 A in ion irradiated structures. This transparency effect was attributed to a reduction in a free-carrier absorption in the InGaP layers.

We present an investigation on the spatial compositional variation in InGaP layers grown by chemical beam epitaxy (CBE) on pre-patterned substrates. Neighboring regions with 190 meV bandgap discontinuity are observed with the growth at 500°C. The development of laser structures on V-grooves that incorporate these lateral heterostructures is achieved by controlling the growth temperature during growth

The detection of trace gases is very important for a variety of applications, including the monitoring of atmospheric pollutants, industrial process control, measuring air quality in workplaces, research into fruits physiological processes and medical diagnosis of diseases through the analysis of exhaled gases. The implementation of these and many other applications requiring gas sensors able to meet high sensitivity and selectivity. In this work, a photoacoustic laser spectrometer with CO2 emission in the infrared range and a resonant photoacoustic cell was used. We obtain the resonance frequency of 2.4 kHz to photoacoustic cell, was estimated detection limit of the spectrometer for molecules of ethylene (C2H4), 16 ppbV and ammonia (NH3) 42 ppbV.