Morphometric and anatomical characters of fruits and seeds of a population of Prosopis laevigata (Fabaceae) in Lagos de Moreno, Jalisco, Mexico

Antecedentes y Objetivos: Prosopis laevigata, especie de amplia distribución en México, es considerada un recurso con importancia ecológica y socioeconómica. A pesar de que sus semillas y frutos tienen valor nutrimental, los estudios sobre su variación morfológica y anatómica son escasos. Este trabajo es el primero en abordar la morfo-anatomía e histoquímica del fruto y semilla de P. laevigata y tiene como objetivo contribuir al conocimiento de su biología y proporcionar las bases para otras investigaciones con un enfoque ecofisiológico en esta y otras especies del género. Métodos: Muestras de frutos y semillas fueron recolectadas de árboles de P. laevigata en una localidad de Lagos de Moreno, Jalisco, México, para analizar sus caracteres morfométricos, anatómicos e histoquímicos. Adicionalmente, se estudió su composición micro elemental mediante microscopía electrónica de barrido (MEB) acoplada a espectroscopia de rayos X de energía dispersiva (EDS). Se aplicaron análisis ANOVA y de correlación para conocer la variabilidad intrapoblacional y asociación entre variables morfométricas. Resultados clave: El coeficiente de variación más alto (47.7%) fue para el número de semillas por fruto. El ANOVA demostró diferencias estadísticas significativas para las variables longitud (F=7.51, p<0.0001) y ancho de la semilla (F=8.75, p<0.0001); la correlación más alta (0.937) fue para ancho fruto-ancho semilla. Los frutos presentan epicarpo, mesocarpo con cristales de oxalato de calcio y endocarpo coriáceo. Las semillas tienen pleurograma, micrópilo subapical, testa gruesa con epidermis de macroesclereidas y osteoesclereidas en la hipodermis. Cotiledones contienen cuerpos de proteína y endospermo con almidón. La testa y el embrión presentan macroelementos (S, K, Mg) y microelementos (Al, Si, Cu). Conclusiones: La estructura morfológica, anatómica e histoquímica de frutos y semillas de P. laevigata fueron similares a otros Prosopis. La epidermis en empalizada, hipodermis con osteoesclereidas en la testa de la semilla, los estomas y cristales prismáticos en las vainas podrían representar caracteres ecofisiológicos importantes.Background and Aims: Prosopis laevigata, a widely distributed species in Mexico, is considered a resource with ecological and socioeconomic importance. Although its seeds and fruits have nutritional value, research on its morphological and anatomical variation is scarce. This study is the first to address the morpho-anatomy and histochemistry of the fruit and seed of P. laevigata and aims to contribute to the knowledge of its biology, as well as provide the basis for other research with an ecophysiological approach of this and other species of the genus. Methods: Fruit and seed samples were collected from Prosopis laevigata trees in a locality of Lagos de Moreno, Jalisco, Mexico, to analyze their morphometric, anatomic, and histochemical characters. Additionally, its micro elemental composition was studied by scanning electron microscopy (SEM) coupled to energy-dispersive X-ray spectroscopy (EDS). ANOVA and correlation analyzes were applied to determine intrapopulation variability and association between morphometric variables. Key results: The highest coefficient of variation (47.7%) was for the number of seeds per fruit. The ANOVA showed significant statistical differences for the variables seed length (F=7.51, p<0.0001) and seed width (F=8.75, p<0.0001); the highest correlation (0.937) was for fruit width-seed width. The fruits have an epicarp, mesocarp with calcium oxalate crystals and a leathery endocarp. The seeds present a pleurogram, subapical micropyle, and a thick seed coat with an epidermis of macrosclereids, and osteosclereids in the hypodermis. Cotyledons contain protein bodies and starchy endosperm. The testa and the embryo present macroelements (S, K, Mg) and microelements (Al, Si, Cu). Conclusions: The morphological and anatomical characteristics and histochemical structure of fruits and seeds of the P. laevigata were similar to other Prosopis. The palisade epidermis, hypodermis with osteosclereids in the seed coat, stomata and prismatic crystals in the pods could represent important ecophysiological characters

Bioadsorción de plomo (II) presente en solución acuosa sobre residuos de fibras naturales procedentes de la industria ixtlera (Agave lechuguilla Torr. y Yucca carnerosana (TREL.) MCKELVEY)

"El plomo ha sido reconocido como uno de los metales más tóxicos por su efecto negativo sobre el ambiente. En el presente trabajo se evaluó el uso potencial de residuos de Agave lechuguilla Torr. (lechuguilla) y Yucca carnerosana (Trel.) McKelvey (yuca) procedentes de la industria ixtlera para remover iones Pb (II) presentes en solución acuosa. Los datos del equilibrio de bioadsorción mostraron que al aumentar el pH de la solución de 2.0 a 5.0, la capacidad de bioadsorción de ambos materiales se incrementa. Este efecto se explicó considerando que la carga superficial negativa de estos materiales es mayor al aumentar el pH y por ello se favorece la remoción de Pb (II). El efecto de la temperatura de la solución en las isotermas de bioadsorción, expuso la naturaleza endotérmica del proceso. La energía libre de Gibbs y la entropía calculada (ΔG° y ΔS°) indicaron la espontaneidad de la bioadsorción y la afinidad del Pb (II) en solución por los bioadsorbentes, respectivamente. La variación de las capacidades de bioadsorción de la lechuguilla y la yuca se atribuyó a la diferencia en el contenido de sitios ácidos y lignina, lo que condujo a la presencia de diversos mecanismos de bioadsorción. En ambos materiales, la bioadsorción de Pb (II) ocurre por los mecanismos de interacciones π-catión, atracciones electrostáticas e intercambio iónico; además en el caso de la lechuguilla se evidenció un proceso de microprecipitación.""Lead has been recognized as one of the most toxic metals due to its negative effect on the environment. In the present work, the potential use of Agave lechuguilla Torr. (lechuguilla) and Yucca carnerosana (Trel.) McKelvey (yucca) residues from the ixtle industry to remove Pb (II) ions in an aqueous solution was evaluated. The adsorption equilibrium data showed that when increasing the pH in the solution from 2.0 to 5.0, the biosorption capacity of both materials increases. This effect might be explained by the negative surface charge of these materials, which is greater at high pH, favoring the removal of Pb (II). The effect of the temperature of the solution on the biosorption isotherms revealed the endothermic nature of the biosorption process. The Gibbs free energy change and the calculated entropy (ΔG° and ΔS°) indicated the spontaneity of biosorption and the affinity of Pb (II) in the solution for biosorbents, respectively. The variation of the biosorption capacities of lechuguilla and yucca was attributed to the different content of acid sites and lignin, which resulted in the presence of different biosorption mechanisms. In both materials, the biosorption of Pb (II) occurs by π-cation interactions, electrostatic attractions and ion exchange; moreover, a microprecipitation process on lechuguilla was evinced.

Synthesis, characterization and magnetic properties of Co@Au core-shell nanoparticles encapsulated by nitrogen-doped multiwall carbon nanotubes

"Co/Au bilayer thin films were deposited on Si/SiOx substrates using the magnetron sputtering method and used as a catalytic support to grow forests of aligned nitrogen-doped multiwalled carbon nanotubes (N-MWCNT) via chemical vapor deposition (CVD) at 850 °C, using benzylamine (C6H5CH2NH2) as a carbon and nitrogen source. Interestingly, the resulting N-MWCNT contains Co@Au core-shell nanoparticles located at their tips. We found that the metal particle cores consist of cobalt coated by an Au shell of few nanometers. Magnetic measurements revealed a ferromagnetic behavior of the system composed of Co@Au nanoparticles encapsulated inside N-MWCNT. The results are compared with pristine N-MWNT containing only Co nanoparticles encapsulated in their cores.

Detection of thiourea from electrorefining baths using silver nanoparticles-based sensors

A novel and easy-to-use colorimetric thiourea (TU) sensor based on immobilized polyvinylpyrrolidone-stabilized silver nanoparticles (PVP-AgNPs) is reported. The new sensor is aimed for its direct application in copper electrorefinery baths. Quantitative analysis was carried out by adding different thiourea amounts into a synthetic bath and monitoring the absorption changes of the surface plasmon resonance band (SPRB) by UV-Vis spectrophotometry. A linear correlation between the absorbance change and thiourea concentration was obtained, ranging from 0.125 mg/L to 1 mg/L. Our technique has the advantage of working in acidic and high ionic concentrated solutions as those used in electrorefinery baths. The influence of the nanoparticles synthesis conditions on the thiourea sensing was analyzed; particularly, the effect of using different silver concentrations and the same amount of borohydride ions as reducing agent ([Ag+]/[BH4 -] ratios of 2:1, 8:1, 10:1 and 20:1 during the synthesis). The proposed system provides a simple, economical, easy-to-handle and rapid measurement tool for monitoring hydrometallurgical processes for optimizing the reconditioning of thiourea solutions, reducing its environmental impact.Fil: Pedre, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Battaglini, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Delgado, Gladis Judith Labrada. Instituto Potosino de Investigación Científica y Tecnológica; MéxicoFil: Sánchez Loredo, María Guadalupe. Universidad Autonoma de San Luis Potosi; MéxicoFil: González, Graciela Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Synthesis and Characterization of α-Al₂O₃/Ba-β-Al₂O₃ Spheres for Cadmium Ions Removal from Aqueous Solutions

The search for adsorbent materials with a certain chemical inertness, mechanical resistance, and high adsorption capacity, as is the case with alumina, is carried out with structural or surface modifications with the addition of additives or metallic salts. This research shows the synthesis, characterization, phase evolution and Cd(II) adsorbent capacity of α-Al2O3/Ba-β-Al2O3 spheres obtained from α-Al2O3 nanopowders by the ion encapsulation method. The formation of the Ba-β-Al2O3 phase is manifested at 1500 °C according to the infrared spectrum by the appearance of bands corresponding to AlO4 bonds and the appearance of peaks corresponding to Ba-O bonds in Raman spectroscopy. XRD determined the presence of BaO·Al2O3 at 1000 °C and the formation of Ba-β-Al2O3 at 1600 °C. Scanning electron microscopy revealed the presence of spherical grains corresponding to α-Al2O3 and hexagonal plates corresponding to β-Al2O3 in the spheres treated at 1600 °C. The spheres obtained have dimensions of 4.65 ± 0.30 mm in diameter, weight of 43 ± 2 mg and a surface area of 0.66 m2/g. According to the curve of pH vs. zeta potential, the spheres have an acid character and a negative surface charge of −30 mV at pH 5. Through adsorption studies, an adsorbent capacity of Cd(II) of 59.97 mg/g (87 ppm Cd(II)) was determined at pH 5, and the data were fitted to the pseudo first order, pseudo second order and Freundlich models, with correlation factors of 0.993, 0.987 and 0.998, respectively

Coexistence of two-photon absorption and saturable absorption in ion-implanted platinum nanoparticles in silica plates

"Platinum nanoparticles were nucleated in a high-purity silica matrix by an ion-implantation method. The third-order nonlinear optical response of the samples was studied using femtosecond pulses at 800 nm with the z-scan technique; picosecond pulses at 532 nm using a self-diffraction approach; and nanosecond pulses at 532 nm employing a vectorial two-wave mixing experiment. Nanosecond and picosecond explorations indicated an important thermal process participating in the optical Kerr effect evaluated. However, femtosecond results allowed us to distinguish a purely electronic response, related exclusively to ultrafast refractive and absorptive nonlinearities. Femtosecond experiments pointed out the possibility to switch the dominant physical mechanism responsible for the nonlinear optical absorption in the sample. This opens the potential for controlling quantum mechanisms of optical nonlinearity by femtosecond interactions.

Pyrrolic nitrogen-doped multiwall carbon nanotubes using ball-milled slag-SiC mixtures as a catalyst by aerosol assisted chemical vapor deposition

We demonstrated that the ball-milled slag-SiC mixture is an effective catalyst to grow pyrrolic nitrogen-doped multiwall carbon nanotubes (N-MWCNTs) by aerosol assisted chemical vapor deposition (AACVD) method. N-MWCNTs synthesized at 800 °C, 850 °C and 900 °C were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, x-ray powder diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). TEM characterizations revealed the presence of a bamboo-like structure, a typical feature of nitrogen-doped carbon nanotubes. The presence of nitrogen was confirmed by the N1s XPS spectrum. Furthermore, a deconvolution of the N1s spectra revealed the presence of N-pyrrolic defects. This nitrogen functionality is investigated concerning the presence of silicon carbide material. Giant nanotubes with large diameters were obtained when SiC was added to the slag to be used as a substrate for N-MWCNTs synthesis. From Raman spectroscopy, the appearance of the D-band was observed, indicating the presence of topological defects that were also observed by TEM. XRD and TEM characterizations demonstrated the presence of Fe _3 C and α -Fe nanoparticles. The N-MWCNTs fabricated here could be used into (electro)catalytic applications or for reinforcing ceramic nanomaterial or polymers