Amostras de óleo obtido do fruto do Buriti (Mauritia flexuosa L.) foram caracterizadas por espectroscopia de absorção e emissão. O espectro de absorção foi obtido no intervalo de 300 a 2000 nm, enquanto o espectro de emissão foi analisado entre 400 e 800 nm, onde observamos várias bandas. Para melhor entender a complexidade destes espectros, também obtivemos os espectros de absorção e emissão dos componentes majoritários do óleo de Buriti. Correlacionando estes dados, apresentamos uma discussão sobre a origem das bandas observadas. Oil samples obtained from Buriti (Mauritia flexuosa L.) palm tree fruits were characterized by absorption and emission spectroscopies. The absorption spectrum was recorded in the range from 300 to 2000 nm, while the emission spectrum was analyzed between 400 and 800 nm, where several bands were observed. To better understand these complex spectra, we recorded both absorption and emission spectra of its major components. By correlating these data, we present a discussion on the possible origin of the bands observed.

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Variation of two and three photon upconversion band intensities in LNO:Er1%–Yb7.5% phosphor with temperature.

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This work unveils the roles played by potato starch (ST) in the immobilization, photochemical reduction, and gas sensitivity of graphene oxide (GO) films. The ST/GO films are assembled layer by layer (LbL) onto quartz substrates by establishing mutual hydrogen bonds that drive a stepwise film growth, with equal amounts of materials being adsorbed in each deposition cycle. Afterward, the films are photochemically reduced with UV irradiation (254 nm), following a first-order kinetics that proceeds much faster when GO is assembled along with ST instead of a nonoxygenated polyelectrolyte, namely, poly(diallyl dimethylammonium) hydrochloride (PDAC). Finally, the gas-sensing performance of ST/reduced graphene oxide (RGO) and PDAC/RGO sensors fabricated via LbL atop of gold interdigitated microelectrodes is evaluated at different relative humidity levels and in different concentrations of ammonia, ethanol, and acetone. In comparison to the PDAC/RGO sensor, the ones containing ST are much more sensitive, especially when operating in a high-relative-humidity environment. An array comprising these chemical sensors provides unique electrical fingerprints for each of the investigated analytes and is capable of discriminating and quantifying them in a wide range of concentrations, from 10 to 1000 ppm.