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Mario Acosta-Flores,Marta Lilia Eraña-Díaz,Eusebio Jiménez-López,Juan Carlos García,Juan José Delfín-Vázquez,Baldomero Lucero-Velázquez 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.7
In this study, a novel method for determining stresses in the torsion problems of laminated composite trimetallic and bimetallic bars was developed and evaluated via experimental and numerical analyses. The objective of this method is to transform a real transversal section of a model for a laminated composite bar into a hypothetical virtual section that is homogenous and isotropic. An analogy with the transformed-section method for solving composite beams under flexion was conducted. The shear stresses (maximum on external surfaces and interfaces) in laminated composite bars were undergoing torsion. Isotropic symmetric and asymmetric laminated composite bars were examined analytically, and the results of their respective experimental and numerical tests were analyzed. The proposed method exhibits differences between 2 % and 12 % compared with the experimental results and between 2 % and 10 % compared with the results obtained using the finite element method.
Effect of biofertilizers and rhizospheric bacteria on growth and root ultrastucture of lettuce
Montesdeoca-Flores David,Alfayate-Casañas Carmen,Hernández-Bolaños Eduardo,Hernández-González Mercedes,Estupiñan-Afonso Zuleima,Abreu-Acosta Néstor 한국원예학회 2024 Horticulture, Environment, and Biotechnology Vol.65 No.1
Biofertilization is a technique that uses plant and animal wastes to add organic matter and nutrients to the soil. It can also use microorganisms that can metabolize these by-products to facilitate their absorption by the plant roots. In this study, we tested the eff ects of rhizospheric bacteria inoculation (T 1 ), a combination of rhizospheric bacteria with liquid fertilizer (T 2 ) and uncombined liquid fertilizer (T 3 ), on the growth, nutritional content, root tissue, and root cells of lettuce plants. The results showed signifi cant positive diff erences in all treatments compared to control plants, in terms of morphologi cal, nutritional, and productivity parameters. The combination of rhizospheric bacteria with liquid SEFEL fertilizer (T 2 ) yielded the best results, showing increased fresh and dry weight, and diameter. There were no diff erences between treat ments for nutritional content, but each treatment outperformed the control by more than 700% for all macronutrients. The best result was phosphorus content for T 1 , with 1272.22% more than control. Regarding root structure and ultrastructure, there was no variation in tissue organization compared to control plants, but increases in root hairs (T 1 ), development of transfer cells (T 2 ), and secondary growth (T 3 ) were observed. Additionally, colonization of roots by rhizospheric bacteria was confi rmed in all three treatments. In conclusion, this study suggests that inoculating with rhizospheric bacteria is a viable and environmentally friendly biofertilization for lettuce plants.
M. Cortez-Valadez,L. P. Ramírez-Rodríguez,J.-G. Bocarando-Chacon,M. FLORES-ACOSTA,S. VELUMANI,R. Ramírez-Bon 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.7
"Cadmium colloidal crystalline nanoparticles were obtained by a simple green synthesis method employing the plant extract of Opuntia ficus-indica. The plant extract reduces the Cd ions and stabilizes the size of cadmium colloidal particles at the nanometric level. The size and morphology of agglomerates of nanoparticles of about 100 nm were analyzed by field-emission scanning electron microscopy (FESEM). The size, shape and crystalline structure of the Cd nanoparticles were determined from TEM analysis. The results show that Cd nanoparticles with hexagonal crystalline structure and average size 2–3 nm were obtained by this green synthesis method. The optical absorption spectrum of the colloidal solution containing the cadmium nanoparticles displays an optical absorption band centered at 236 nm, which was attributed to the plasmon resonance of the Cd colloidal nanoparticles. Mie theory for colloidal systems was applied to reproduce theoretically the plasmon resonance absorption data of the Cd colloidal nanoparticles. Furthermore, the Raman spectrum of powder from dried samples after reduction of cadmium ions, displays a low wavenumber vibration mode centered at 114 cm-1, assigned to the Cd nanoparticles. Density functional theory (DFT) calculations at local spin density approximation (LSDA) level were performed to determine the structure and vibrational properties of small clusters of cadmium consisting of 3–10 atoms. Radial breathing modes with frequencies between 90 cm-1 and 120 cm-1 were found to be the most active Raman modes of the low-energy Cdn clusters."
L. P. RAMÍREZ-RODRÍGUEZ,M. CORTEZ-VALADEZ,H. ARIZPE-CH AVEZ,J.-G. BOCARANDO-CHACON,R. RAMÍREZ-BON,S. VELUMANI,M. FLORES-ACOSTA 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.6
Colloidal nanoparticles were obtained by green synthesis, embedded in the Opuntia ¯cus-indicaplant extract. Optical measurements allowed us to detect two absorption bands centered in230 nm and 298 nm. Agglomerates of Pb nanoparticles have size in the range 2 – 8 nm. The ef-fective absorption cross section of spherical Pb nanoparticles was calculated by applying the Mietheory for colloidal systems and compared to optical absorption measurements of Pb nano-particles. The Raman spectrum of the samples after the reduction of Pb, shows a band at lowwavenumbers centered at 116 cm? 1 . Similar bands have been assigned to small Pb and Agclusters in other experimental results. Additionally, we used the density functional theory (DFT)as well as semi-empirical methods to assign this band to radial breathing modes of Pb metalnanoparticles.