Organic-solvent-free extraction of carotenoids from yeast Rhodotorula glutinis by application of ultrasound under pressure

The extraction of Rhodotorula glutinis carotenoids by ultrasound under pressure (manosonication) in an aqueous medium has been demonstrated. The influence of treatment time, pressure, and ultrasound amplitude on R. glutinis inactivation and on the extraction of carotenoids was evaluated, and the obtained data were described mathematically. The extraction yields were lineal functions of those three parameters, whereas inactivation responded to a more complex equation. Under optimum treatment conditions, 82% of carotenoid content was recovered. Extraction of carotenoids in an aqueous medium was attributed to the capacity of ultrasound for cell disruption and emulsification. Cavitation caused the rupture of cell envelopes and the subsequent formation of small droplets of carotenoids surrounded by the phospholipids of the cytoplasmic membrane that would stabilize the emulsion. Analysis of the dispersed particle size of the extracts demonstrated that a fine, homogeneous emulsion was formed after treatment (average size: 230 nm; polydispersity <0.22). This research describes an innovative green process for extracting carotenoids from fresh biomass of R. glutinis in which only two unit operations are required: ultrasonic treatment, followed by a centrifugation step to discard cell debris. The extract obtained thanks to this procedure is rich in carotenoids (25 mg/L) and could be directly incorporated as a pigment in foods, beverages, and diet supplements; it can also be utilized as an ingredient in drugs or cosmetics

Structural, ferroelectric, and optical properties of Bi3+ doped YFeO3: A first‐principles study

The orthoferrites with the general formula RFeO3 (R = Ho, Er, Lu, Sc, and Y) have recently attracted a great deal of attention because they are promising candidates for a second generation of multiferroic materials. In this computational work, the structural, ferroelectric and optical properties of the YFeO3 perovskite oxide (YFO) and a Bi‐doped YFeO3 were analyzed. Bi‐substitution in YFO leads to an increase of its lattice parameters by virtue of the larger ionic radius of Bi3+. Both compounds exhibit a G‐type antiferromagnetic ground state. The calculations disclose a significant spontaneous polarization along the [101] direction of YFO‐Bi, which originates in the asymmetric distribution of the charges around the Bi3+ ions, as a result of the Bi‐6s electrons. The electric polarizability of YFO is increased upon Bi3+‐doping and the more significant components of the real permittivity tensor of YFO‐Bi are those associated with the direction along which the maximum value of spontaneous polarization is observed. The spontaneous polarization of YFO‐Bi found in this work reveals that this compound holds the potential for the next generation of multi ferroic materials

Las clases virtuales en México durante la pandemia. Ventajas y desventajas

La modalidad de clases virtuales debido a la contingencia sanitaria provocada por la COVID-19 hace necesarios estudios diagnósticos que permitan conocer sus efectos en el proceso de aprendizaje-enseñanza. En este trabajo se confrontan las ventajas y desventajas de las clases virtuales, según la opinión de 350 estudiantes y 100 profesores de universidades públicas de México, obtenida mediante un sondeo hecho por los autores a través de Google Forms®. Entre los resultados obtenidos, se puede destacar que tanto los profesores como los estudiantes identifican más desventajas que ventajas respecto a las clases virtuales; sin embargo, ambos reconocen que debido a la pandemia era necesario continuar las clases bajo esta modalidad. Aunque hay diferencias entre las respuestas de profesores y estudiantes, y se identifica que la experiencia para los docentes ha sido más positiva, también hay coincidencias. Entre las desventajas mencionadas, sobresalen la falta de interacción personal, la poca motivación, el estrés que el encierro genera, la carencia de equipo y deficiencia de la señal de internet, entre otras. Algunas de las ventajas que más se mencionan son la facilidad de acceder a distintas fuentes por medios electrónicos, el ahorro económico y el adquirir nuevas habilidades informáticas

Uses of Native Plant Species of a Communal Rangeland within ‘Sierra de Huautla’ Protected Area, México

Sustainability of communal rangelands has become a major concern at national and international levels because land use conflicts and associated social conflicts allows for over-utilization of selected species making a high pressure on them and given away their places to species with no use at all becoming lands degraded and unproductive. The objective of the study was to determine floristic composition and native plant uses by local peasants. The range surface is of 4262 ha, belongs to the communal land ‘El Limon’, in Tepalcingo, Morelos, Mexico, and it is within the Natural Reserve Area “Sierra de Huautla”. Native vegetation is mainly of deciduous shrubs, high temperatures year round and a rainy season of 4 months. Local peasants were surveyed on uses of the collected and previously identified plants. Number of species was 456, distributed in 266 and 76 botanical genders and families, respectively. Of the species identified 66, 22 and 12% had one, two or more than two uses according to local peasants. Among uses: 59% of the species were used as forage, 8% eatable, 7% firewood or ornamental, 6% medical herb, lumber or other use 4 %, construction material 3 % and for resin or handcraft 1%. The range showed a very high plant biodiversity, this feature allows for a high resiliency toward human activities

Effect of La3+/Sr2+ ordering on the magnetic properties of La2/3Sr1/3MnO3 by first principles calculations

In this work, using DFT + U formalism, we investigate the effect of order-disorder in the A-site occupation byLa3+and Sr2+on the stability of the ferromagnetic order in La2/3Sr1/3MnO3with−Rc3symmetry. To date, adetailed theoretical discussion of such phenomenon, using a combination of different representations of theelectronic structure, is still missing in the Literature. We employed structural models consisting of 120 atomsupercells constructed according to the precise stoichiometry of the compound. Two configurations, describingrandomized and ordered occupation of the La3+/Sr2+ions, were evaluated. We demonstrate that the ferro-magnetic arrangement of La2/3Sr1/3MnO3with randomly distributed La3+and Sr2+ions is more stable. In suchconfiguration wefind that the Mn3+and Mn4+ions are not distinguished, favoring the double-exchange me-chanism, enhanced by the higher degree of covalence in the MneO bonds near the Fermi level between thespin-upMn-egorbitals and the O-porbitals

Aplicación e importancia de la estrategia y toma de decisiones empresariales en el simulador Capstone

Este documento presenta el trabajo realizado en el simulador de negocios Capstone, en donde se trabajó en la administración de una empresa de sensores. Los miembros del equipo crearon estrategias para mejorar el desarrollo de la compañía durante los ocho años que cubre la simulación. Se presentan las decisiones tomadas, los estudios de mercado realizados, las estrategias de negocios, los resultados y las oportunidades de mejora

Factorizing the time evolution operator

There is a widespread belief in the quantum physical community, and in textbooks used to teach Quantum Mechanics, that it is a difficult task to apply the time evolution operator Exp{-itH/h} on an initial wave function. That is to say, because the hamiltonian operator generally is the sum of two operators, then it is a difficult task to apply the time evolution operator on an initial wave function f(x,0), for it implies to apply terms operators like (a+b)^n. A possible solution of this problem is to factorize the time evolution operator and then apply successively the individual exponential operator on the initial wave function. However, the exponential operator does not directly factorize, i. e. Exp{a+b} is not equal to Exp{a}Exp{b}. In this work we present a useful procedure for factorizing the time evolution operator when the argument of the exponential is a sum of two operators, which obey specific commutation relations. Then, we apply the exponential operator as an evolution operator for the case of elementary unidimensional potentials, like the particle subject to a constant force and the harmonic oscillator. Also, we argue about an apparent paradox concerning the time evolution operator and non-spreading wave packets addressed previously in the literature.Comment: 24 pages; added references; one figure change

Enhancement and Edge-Preserving Denoising: An OpenCL-Based Approach for Remote Sensing Imagery

Image enhancement and edge-preserving denoising are relevant steps before classification or other postprocessing techniques for remote sensing images. However, multisensor array systems are able to simultaneously capture several low-resolution images from the same area on different wavelengths, forming a high spatial/spectral resolution image and raising a series of new challenges. In this paper, an open computing language based parallel implementation approach is presented for near real-time enhancement based on Bayesian maximum entropy (BME), as well as an edge-preserving denoising algorithm for remote sensing imagery, which uses the local linear Stein’s unbiased risk estimate (LLSURE). BME was selected for its results on synthetic aperture radar image enhancement, whereas LLSURE has shown better noise removal properties than other commonly used methods. Within this context, image processing methods are algorithmically adapted via parallel computing techniques and efficiently implemented using CPUs and commodity graphics processing units (GPUs). Experimental results demonstrate the reduction of computational load of real-world image processing for near real-time GPU adapted implementation.ITESO, A.C