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1,361 results on '"Flores, F"'

16. Measuring low doping level and short carrier lifetime in indium arsenide with a contactless terahertz technique at room temperature.

Author

Guise, J., Ratovo, H., Thual, M., Fehlen, P., Gonzalez-Posada Flores, F., Rodriguez, J.-B., Cerutti, L., Centeno, E., Blin, S., and Taliercio, T.

Subjects
INDIUM arsenide, PUMP probe spectroscopy, TERAHERTZ materials, OPTICAL pumping, CARRIER density, TEMPERATURE
Abstract

Non-destructive, reliable, and accurate measurements of low doping levels and carrier lifetimes in small direct-bandgap semiconductors such as indium arsenide (InAs) at room temperature are challenging due to intrinsic limitations of conventional experimental techniques. In this article, we introduce a contactless optical-terahertz (THz) pump–probe technique in a continuous-wave regime measuring low doping levels in the 10 15 − 10 16 cm − 3 range and lifetimes down to 8 ns at room temperature in InAs. We show that a single-parameter material model can be used to retrieve the free carrier density from THz transmission measurements of InAs layers. Additionally, we show that lifetime of photogenerated excess carriers can be measured by modulating this carrier density using an amplitude-modulated optical pump. [ABSTRACT FROM AUTHOR]

Published
2023
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25. GROWTH OF THE CALIFORNIAN RED WORM (Eisenia foetida) IN VERMICOMPOSTING PROCESS OF DIESEL CONTAMINATED SOIL/CRECIMIENTO DE LA LOMBRIZ ROJA CALIFORNIANA (Eisenia foetida) EN EL PROCESO DE VERMICOMPOSTAJE DE SUELO CONTAMINADO CON DIESEL/CRESCIMENTO DA MINHOCA VERMELHA-DA-CALIFÓRNIA (Eisenia foetida) NO PROCESSO DE VERMICOMPOSTAGEM DE SOLO CONTAMINADO COM DIESEL

Author

Rodríguez-Flores, F. de Jesús, Núñez-Núñez, Cynthia M., Ordaz-Díaz, Luis A., Álvarez-Álvarez, Carlos, and Montoya, Angélica Rivera

Published
2021

30. Characterization of CdS/CdTe Ultrathin-Film Solar Cells with Different CdS Thin-Film Thicknesses Obtained by RF Sputtering.

Author

Melchor-Robles, J. A., Nieto-Zepeda, K. E., Vázquez-Barragán, N. E., Arreguín-Campos, M., Rodríguez-Rosales, K., Cruz-Gómez, J., Guillén-Cervantes, A., Santos-Cruz, J., Olvera, M. de la L., Contreras-Puente, G., and Moure-Flores, F. de

Subjects
RADIOFREQUENCY sputtering, SOLAR cells, SURFACE analysis, MAGNETRON sputtering, THIN films, PHOTOVOLTAIC power systems
Abstract

The development of semitransparent CdS/CdTe ultrathin solar cells has been delayed as a result of the activation annealing to which the device must be subjected, which may involve problems such as the sublimation of ultrathin films and the diffusion of Cd and S at the interface. In this work, CdS/CdTe ultrathin devices on soda-lime glass/SnO2:F/ZnO substrates were obtained by RF magnetron sputtering. CdS/CdTe ultrathin heterostructures were obtained with the following thicknesses for the CdS thin film: 70, 110, and 135 nm. The CdTe thickness film was kept constant at 620 nm. Subsequently, activation annealing with CdCl2 was carried out at 400 °C. Surface characterization was performed by scanning electron microscopy, which indicated that the CdCl2 annealing tripled the CdTe thin films' grain size. Raman characterization showed that CdS thin films deposited by RF sputtering present the first, the second, and the third longitudinal optical modes, indicating the good crystallinity of the CdS thin films. The study showed that the photovoltaic properties of the CdS/CdTe ultrathin devices improved as the CdS thicknesses decreased. [ABSTRACT FROM AUTHOR]

Published
2024
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40. Determination of Mycotoxigenic Fungi and Total Aflatoxins in Stored Corn from Sites of Puebla and Tlaxcala, Mexico.

Author

Saez-Gomez, K., Avila-Sosa, R., Huerta-Lara, M., Avelino-Flores, F., and Munguia-Pérez, R.

Subjects
AFLATOXINS, TOXIGENIC fungi, ASPERGILLUS flavus, CORN, FOOD safety, CORN seeds, FUSARIUM
Abstract

This paper aimed to evaluate the contamination with mycotoxigenic fungi and total aflatoxins in stored corn from different sites in Puebla and Tlaxcala, Mexico. Methodology. The study was conducted at two sites in Puebla (San Salvador El Seco and Junta Auxiliar La Resurrección) and two sites in Tlaxcala (Tlaltepango and Nativitas). A total of 80 samples of stored corn were collected. Identification of Aspergillus flavus was performed by microculture techniques and specific taxonomic keys (macromorphological and micromorphological). Then, samples of contaminated corn were selected, and aflatoxin production was confirmed using a direct solid-phase ELISA kit. A total of 25 A. flavus strains were identified. Other possible mycotoxinproducing fungi were Penicillium (n=52) and Fusarium (n=19). Regarding total aflatoxin contamination, all samples were contaminated within a range of 1.589 to 11.854 µg/kg, and the average concentration was 6.3 µg/kg corn. Implications. The detection of mycotoxigenic fungi in the samples tested and of aflatoxins in corn highlights the importance of monitoring these fungi. Since food safety is at risk, it shows the need for methods to control these fungi and their metabolites. [ABSTRACT FROM AUTHOR]

Published
2024
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48. A CRITERION FOR HYPERSYMMETRY ON DISCRETE GROUPOIDS.

Author

FLORES, F.

Subjects
*ISOTROPY subgroups, *ALGEBRA, *BANACH algebras, *GROUPOIDS, *SYMMETRY
Abstract

Given a Fell bundle $\mathscr C\overset {q}{\to }\Xi $ over the discrete groupoid $\Xi $ , we study the symmetry of the associated Hahn algebra $\ell ^{\infty ,1}(\Xi \!\mid \!\mathscr C)$ in terms of the isotropy subgroups of $\Xi $. We prove that $\Xi $ is symmetric (respectively hypersymmetric) if and only if all of the isotropy subgroups are symmetric (respectively hypersymmetric). We also characterise hypersymmetry using Fell bundles with constant fibres, showing that for discrete groupoids, 'hypersymmetry' equals 'rigid symmetry'. [ABSTRACT FROM AUTHOR]

Published
2023
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