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Item type:Publication, SnO2-TiO2 and SnO2-MoO3 based composite gas sensors to develop an e-nose for Peruvian Pisco varieties differentiation(IOP Publishing Ltd, 2022-01-01)There is great interest in the development of a simple system that could identify adulteration or counterfeiting of Peruvian Pisco (a grape-based alcoholic drink). In this study, sensors based on SnO2-TiO2 and SnO2-MoO3 composites with different weight composition ratios were synthesized and characterized. These sensors were tested with aqueous solutions of EtOH/MeOH and Pisco samples of Italia and Quebranta varieties in order to explore their capacity to identify variations in these beverages. The response profile of the most sensitive sensors showed an enhanced response to alcoholic samples with greater content of ethanol up to a concentration of 45%v/v, while the increased content of methanol in the range of 0.1 to 0.3% v/v diminished the intensity of the sensor response. Differences in the composition of methanol and ethanol in the Pisco varieties studied (Italia and Quebranta) were correlated to the capacity of the composite-based sensors to differentiate them with greater performance. Sensors based on SnO2-TiO2-1/2 composites showed greater reproducibility in their response profile over time in comparison to SnO2-TiO2-1/1 and SnO2-MoO3 composites. The PCA showed that composite sensors were able to differentiate Pisco samples according to the varieties, Italia and Quebranta. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Impact of c- and m-sapphire plane orientations on the structural and electrical properties of β-Ga2O3 thin films grown by metal-organic chemical vapor deposition(Institute of Physics, 2024-12-13)This work presents a comprehensive investigation into the structural and electrical properties of Ga2O3 thin films grown via metal-organic chemical vapor deposition on both c- and m-plane sapphire substrates. Structural characterization revealed the β-Ga2O3 phase formation in both substrate orientations, with strong epitaxial ( 2 ¯ 01 ) preferential growth on c-plane substrates and polycrystalline films on m-plane substrates. Results show that Ga2O3/m-sapphire exhibits the lower electrical resistivity than its counterpart grown on c-sapphire. Activation energies of acceptor levels were estimated at ~1.4 eV and ~0.7 eV , for Ga2O3 films grown on c- and m-plane, respectively. This result shows that growing Ga2O3 on m-plane sapphire is beneficial to reach a weakly compensated sample. Cathodoluminescence analysis suggests that the additional low activation energy of ~0.18 eV observed in Ga2O3 grown with the highest oxygen flow on m-plane sapphire can be associated to thermally-induced migration of self-trapped hole states. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Application of Machine Learning Algorithms to Classify Peruvian Pisco Varieties Using an Electronic Nose(Multidisciplinary Digital Publishing Institute (MDPI), 2023-07-01)Pisco is an alcoholic beverage obtained from grape juice distillation. Considered the flagship drink of Peru, it is produced following strict and specific quality standards. In this work, sensing results for volatile compounds in pisco, obtained with an electronic nose, were analyzed through the application of machine learning algorithms for the differentiation of pisco varieties. This differentiation aids in verifying beverage quality, considering the parameters established in its Designation of Origin”. For signal processing, neural networks, multiclass support vector machines and random forest machine learning algorithms were implemented in MATLAB. In addition, data augmentation was performed using a proposed procedure based on interpolation–extrapolation. All algorithms trained with augmented data showed an increase in performance and more reliable predictions compared to those trained with raw data. From the comparison of these results, it was found that the best performance was achieved with neural networks. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Analytical Study of an 1899 Peruvian Dinero: Unveiling the Mystery of a Coin That Wasn’t Officially Minted(Springer Science and Business Media Deutschland GmbH, 2023-12-01)The present paper presents the analytical study of an unusual Peruvian 1899 dinero coin whose authenticity has been questioned since the 1970’s. This coin, which is present in some numismatic collections although there is no record of having been minted officially, has been characterized using non-destructive techniques such as X-ray fluorescence (XRF), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM–EDS), and X-ray diffraction (XRD). Results are consistent with a cast counterfeit coin made at the turn of the 19th and 20th using a copper base alloy that was silver-platted to pass unnoticed among the public. The alloy used, generally known as german silver, was common for counterfeits in North America and Europe in that period. The historical reasons for the appearance of this unexpected coin in Peru during a time of economic difficulties, where the public experienced a shortage of small-change coins, are briefly outlined.