Superparamagnetic Poly (3-hydroxybutyrate-co-3 hydroxyvalerate) (PHBV) nanoparticles for biomedical applications

Indexación: ScieloBackground: The progress in material science and the recent advances in biodegradable/biocompatible polymers and magnetic iron oxide nanoparticles have led to develop innovative diagnostic and therapeutic strategies for diseases based on multifunctional nanoparticles, which include contrast medium for magnetic resonance imaging, agent for hyperthermia and nanocarriers for targeted drug delivery. The aim of this work is to synthesize and characterize superparamagnetic iron oxide (magnetite), and to encapsulate them into poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles for biomedical applications. Results: The magnetite nanoparticles were confirmed by X-ray diffraction and exhibited a size of 22.3 ± 8.8 nm measured by transmission electron microscopy (TEM). Polymeric PHBV nanoparticles loaded with magnetite (MgNPs) were analyzed using dynamic light scattering and showed a size of 258.6 ± 35.7 nm and a negative zeta potential (-10.8 ± 3.5 mV). The TEM examination of MgNPs exhibited a spherical core-shell structure and the magnetic measurements showed in both, non-encapsulated magnetite and MgNPs, a superparamagnetic performance. Finally, the in vitro studies about the magnetic retention of MgNPs in a segment of small intestine of rats showed an active accumulation in the region of the magnetic field. Conclusions: The results obtained make the MgNPs suitable as potential magnetic resonance imaging contrast agents, also promoting hyperthermia and even as potential nanocarriers for site-specific transport and delivery of drugs. Keywords: hyperthermia, magnetic resonance image (MRI), magnetite, PHBV, polymeric nanoparticles.http://ref.scielo.org/cxt57

Doping, medicamentos prohibidos

Es muy común hablar del Dóping y sus efectos, pero muy difícil aún para directivos y técnicos, tener una noción clara de las sustancias que producen los efectos dopantes, o mejor aquellas que se detectan por los procedimientos técnicos que se emplean para su control. Las Federaciones internacionales y aún el Comité Olímpico Internacional, elaboran listas de medicamentos prohibidos y de otros procedimientos ilegales, cuando se acercan competencias mundiales pero lo hacen con una terminología a la que no tienen acceso la mayoría de las personas que tienen bajo su responsabilidad el manejo del deporte y el cuidado de las selecciones nacionales

L-Grassf: A New Model for Simulating the Genetic Environment Interactions on the Reproductive Phenology of Grasses

Predicting the reproductive phenology in perennial grasses is a major concern because it determines the quantity and quality of forage. It varies a lot depending on site, year and cultivar. Projections of future climates suggest significant changes in seasonal temperature pattern, with new combinations of temperature and photoperiod, whose consequences on the floral induction of perennial grasses are unknown. L-GrassF is a new Functional Structural Plant Model simulating genetic variability of the phenology of perennial ryegrass in order to better understand the perenniality of grasslands and better anticipate the effects of climate change. L-GrassF stems from a previous model (L-Grass) and now simulates the reproductive stages by integrating the interactions between vegetative growth, floral induction and reproductive organ development. The sensitivity analysis of a set of parameters was studied in the range of oceanic temperate climate conditions, on several European cultivars. It was further calibrated and validated on two independent datasets from the French Variety and Seed Study and Control Group (GEVES), which include the observations of heading dates for seven cultivars of Lolium perenne grown in six French locations between 2001 and 2017

Modelling of Nitrogen Allocation and Partitioning Within Lucerne (\u3cem\u3eMedicago Sativa\u3c/em\u3e) Shoot Tissues During Recovery from Defoliation: An Approach to Estimate Forage Production and Nitrogen Composition

Lucerne has been grown over centuries for forage. Its forage production is strongly correlated to the initial taproot and stubble N reserves (Avice et al., 1996; Meuriot et al., 2004). However, the influence of cutting management on the level of N storage and the contribution of these N reserves to forage production still remain unclear and need to be studied at the whole plant level. For this purpose, a deterministic model of N allocation within the different organs and partitioning within different biochemical N pools was developed for lucerne with high and low initial N status and cutting heights of 6 or 15 cm

Length of the artificial incubation in red-legged partridge (Alectoris rufa)

La incubación artificial de los huevos es una fase del manejo clave para la viabilidad de las granjas cinegéticas de perdiz roja (Alectoris rufa). Sin embargo, la duración de la incubación artificial y la dispersión de las eclosiones no han sido previamente cuantificadas en esta especie. Con este objetivo se analizaron cuatro ensayos de incubación artificial de huevos de perdiz roja procedentes de tres granjas cinegéticas del sur de España realizados incluyendo variabilidad de factores de manejo de los reproductores y de la incubación. La duración media de la incubación fue de 23,4 días, difiriendo entre ensayos (P = 0,004), con un valor modal de 23 días y finalizando la mayoría de las eclosiones (percentil 95) el día 24,5 de incubación. La eclosión mostró una distribución asimétrica positiva y leptocúrtica, como corresponde al patrón de eclosión de las especies precociales. Las eclosiones, que pueden comenzar el día 21,5 y finalizar el día 26 de incubación, se extendieron en promedio durante cuatro días, periodo mayor que el descrito en la literatura divulgativa probablemente porque en el presente estudio los huevos no estuvieron en contacto entre sí, lo que pudo limitar la sincronía en la eclosión. Los resultados de este estudio son útiles para conocer la distribución de la eclosión en las granjas cinegéticas de perdiz roja, posibilitando la mejora del manejo de los lotes de huevos en la nacedoraThe artificial incubation of the eggs is a key management phase for the feasibility of the red-legged partridge (Alectoris rufa) game farms. However, the length of the artificial incubation and the spreading pattern of the hatching have not been previously quantified in this species. To this end, four trials of artificial incubation of eggs from three red-legged partridge game farms located in southern Spain were analised. The trials included a wide range of variability with regard to management of breeders and incubation process. The average length of the incubation period was 23.4 days, with differences among trials (P = 0,004), showing a modal value of 23 days. Most of the chicks (percentile 95) hatched before 24.5 days of incubation. The distribution of the hatch was leptokurtic and showed positive asymmetry, fitting with the hatching pattern of the precocial species. The hatching, that can start on day 21.5 and finish on day 26 of incubation, were spread over four days on average. This period was longer than that described in the informative literature, probably because in the present study the eggs were not in contact with each other, which could have limited the hatching synchrony. The results of the present study are useful to understand the distribution of hatching in the red-legged game farms, enabling improved management of the batches of eggs in the hatchery

Thermodynamic analysis and modeling of water vapor adsorption isotherms of roasted specialty coffee (Coffee arabica L. cv. Colombia)

[EN] The experimental assessment and computer modeling of the water vapor adsorption isotherms of roasted specialty coffee is addressed in this study. Thus, both coffee beans and ground coffee of medium (850 mu m) and fine (600 mu m) particle sizes were analyzed over a range of water activities of between 0.1 and 0.9 and at temperatures of 25, 35, and 45 C. The adsorption isotherms were determined using the dynamic dew point (DDI) method. The computer modeling of adsorption isotherms was addressed in order to describe the influence of the water activity and temperature on the equilibrium moisture content. Furthermore, the hygroscopic capacity of roasted coffee was analyzed by differential thermodynamic analysis. Experimental results and modeling showed that the high level of moisture adsorption found in the ground coffee was related to a large adsorption area, suggesting that specialty coffee should preferably be stored as beans. The Peleg empirical model was the most suitable at representing both type III upward concave adsorption behavior and the effect of temperature on the adsorption isotherms. Differential thermodynamic analysis revealed an increase in the water adsorption energy at low equilibrium moisture content, while negative Gibbs free energy values revealed the spontaneity of the adsorption process.The authors thank the Centro Surcolombiano de Investigacion en Cafe (CESURCAFE) of the Universidad Surcolombiana Neiva-Huila of Colombia and the Grupo de Analisis y Simulacion de Procesos Agroalimentarios (ASPA) of the Universitat Politecnica de Valencia-Espana, for their support which was indispensable for this study.Collazos-Escobar, GA.; Gutiérrez-Guzmán, N.; Garcia-Perez, J.; Bon Corbín, J.; Váquiro-Herrera, HA. (2022). Thermodynamic analysis and modeling of water vapor adsorption isotherms of roasted specialty coffee (Coffee arabica L. cv. Colombia). LWT - Food Science and Technology. 160:1-10. https://doi.org/10.1016/j.lwt.2022.11333511016

Operaciones de cobertura con derivados financieros en el mercado de energéticos (crudo)

En el siguiente trabajo se detallarán los resultados que se obtuvieron al dar uso de las herramientas de cobertura contra el riesgo generado por la volatilidad de los precios del crudo, estas herramientas son los contratos a futuro y las opciones. El estudio tuvo como fecha inicial el 24 de septiembre de 2010, día en que se cotiza el contrato futuro, el subyacente cotizado en el mismo se identifica con el nemotécnico CLZ10 con fecha de vencimiento al 19 de noviembre de 2010, el cual se monitoreó durante casi dos meses, exactamente los días 29 de septiembre, 4, 7, 11, 18, y 21 de octubre del presente año. Al mismo tiempo se analizó el comportamiento de las primas de las opciones tipo call y put; todos estos datos fueron obtenidos de la página web de la bolsa de new york (www.ino.com). Luego de esto, a través del modelo Black-Scholes, se valoraron las opciones midiendo la sensibilidad de las variables delta, theta, Ro, Gama y Vega. Además también se observaron otras variables como la Maduración, tasa de interés y la volatilidad

Modelado de las isotermas de desorción y calor isosterico de sorción en granos de café pergamino húmedo (Coffee arabica L.)

Drying is one of the essential operations to guarantee the stability and quality of parchment coffee beans. The objective of the present work was to model the desorption isotherms of the wet parchment coffee beans by means of a prototype of convective drying at laboratory scale and the estimation of the energy requirement of the process. The experimental data were modeled with three empirical expressions that link the dependence of equilibrium moisture content and water activity with temperature. The net isosteric heat of sorption was estimated by the Clausius-Clapeyron equation. The Iglesias and Chirife model satisfactorily modeled representing the effect of temperature on the isotherms of the wet parchment coffee beans; presented a determination coefficient higher than 0.97 and a root mean square error lower than 0.1 kg kg−1 dry basis, all of which indicate a good fit for practical purposes. The net isothermal heat of sorption decreased with increases in moisture content indicating the net energy expenditure of the drying process.El secado es una de las operaciones imprescindibles para garantizar la estabilidad y calidad de los granos de café pergamino. El objetivo del presente trabajo fue modelizar las isotermas de desorción de los granos de café pergamino húmedo mediante un prototipo de secado convectivo a escala de laboratorio y la estimación del requerimiento de energía del proceso. Los datos experimentales fueron modelizados con tres expresiones empíricas que vinculan la dependencia del contenido de humedad de equilibrio y la actividad de agua con la temperatura. El calor isosterico neto de sorción fue estimado mediante la ecuación de Clausius-Clapeyron. El modelo de Iglesias y Chirife logro representar satisfactoriamente el efecto de la temperatura en las isotermas de los granos de café pergamino húmedo; presento un coeficiente de determinación ajustado mayor a 0.97 y un error cuadrático medio menor a 0.1 kg kg−1, base seca, indicando buen ajuste para fines prácticos. El calor isosterico neto de sorción disminuyo con incrementos del contenido de humedad indicando el gasto energético neto del proceso de secado

A Fingerprint Image Encryption Scheme Based on Hyperchaotic Rössler Map

Currently, biometric identifiers have been used to identify or authenticate users in a biometric system to increase the security in access control systems. Nevertheless, there are several attacks on the biometric system to steal and recover the user’s biometric trait. One of the most powerful attacks is extracting the fingerprint pattern when it is transmitted over communication lines between modules. In this paper, we present a novel fingerprint image encryption scheme based on hyperchaotic Rössler map to provide high security and secrecy in user’s biometric trait, avoid identity theft, and increase the robustness of the biometric system. A complete security analysis is presented to justify the secrecy of the biometric trait by using our proposed scheme at statistical level with 100% of NPCR, low correlation, and uniform histograms. Therefore, it can be used in secure biometric access control systems