Applications of the Conceptual Density Functional Theory Indices to Organic Chemistry Reactivity

Indexación: Web of ScienceTheoretical reactivity indices based on the conceptual Density Functional Theory (DFT) have become a powerful tool for the semiquantitative study of organic reactivity. A large number of reactivity indices have been proposed in the literature. Herein, global quantities like the electronic chemical potential μ, the electrophilicity ω and the nucleophilicity N indices, and local condensed indices like the electrophilic and nucleophilic Parr functions, as the most relevant indices for the study of organic reactivity, are discussed.http://www.mdpi.com/1420-3049/21/6/74

Docosahexaenoic acid promotes photoreceptor differentiation without altering Crx expression

PURPOSE: The precise molecular cues required for photoreceptor development are still unknown. Pax6 and Crx are essential during early retinal development and for photoreceptor differentiation, respectively. The lipid molecule docosahexaenoic acid (DHA) has also been shown to promote photoreceptor differentiation. Pax6 expression during the early steps in photoreceptor development and whether the mutual contribution of Crx and DHA enhances photoreceptor differentiation were investigated. METHODS: Neuroblast proliferation, Crx, and Pax6 expression were investigated in rat retinas in vivo and in neuronal cultures with or without DHA. BrdU incorporation, nestin and opsin expression, apical differentiation, and axonal outgrowth were determined by phase microscopy and immunochemistry. RESULTS: Pax6 expression occurred in all proliferating retinal neuroblasts in vivo; however, after their last mitotic division, photoreceptors stopped expressing Pax6 and started expressing Crx. In vitro, photoreceptor progenitors also showed a switch from Pax6 to Crx expression immediately after they exited the cell cycle and started differentiation. In contrast, those progenitors differentiating into amacrine neurons continued expressing Pax6 and did not express Crx. Most postmitotic photoreceptors expressing Crx showed little axon development and few of them expressed opsin. The addition of DHA dramatically increased differentiation in Crx-positive photoreceptors, enhancing opsin expression, apical differentiation, and axonal outgrowth, without affecting Crx expression. CONCLUSIONS: The results suggest that Pax6 and Crx expression are mutually exclusive during photoreceptor differentiation. Onset of Crx expression may provide a permissive stage that is essential to initiate photoreceptor differentiation, but additional support of DHA, among other environmental signals, is necessary to accomplish further differentiation.Fil: Garelli, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Rotstein, Nora Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Politi, Luis Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentin

Membrane performance vs process performance: What should we enhance?

Membrane technology has demonstrated enough potential to compete with conventional systems that are governing the industrial sector already for decades due to their maturity and well-known operation. Examples are distillation, absorption, extraction, crystallization, etc, operation units that are carried out typically in columns or tanks that can be replaced by much more compact and energetically efficient equipment using membranes. There is a large variety of works, results, conclusions, and self-interpretations that can be found in the literature on membrane processes that show some technical viability. But those results and conclusions may be misinterpreted if the final industrial context is not considered properly. Focusing on the membrane performance will lead to different conclusions as those obtained when we are focused on the process performance. Thus, a key issue that arise in this ocean of results is: what should the objective be: high membrane performance or high process performance? This presentation aims at addressing the main differences between these two aspects. Once this difference is understood, the research can be addressed and focused appropriately, and the applicability of the studied systems can be really identified. Two technologies are shown as example: pervaporation and membrane distillation. Pervaporation is a separation technique based on the partial vaporization of compounds through a (commonly) non-porous membrane (dense membrane). The membrane acts as a selective barrier between the two phases, the liquid feed solution and the vapor phase permeate, and the driving force for the separation is the difference in the partial pressures of the components on the two sides of the membrane. The selectivity of the separation is given by different transport rates of the molecules through the membrane as a result of different solubilities and diffusivities of the components. Thus, the presence of azeotropes or difficult mixtures does not affect the efficiency of the separation and it makes pervaporation as a very attractive alternative to distillation. The performance of pervaporation can be done in terms of permeabilities (or permeances) and selectivities (oriented towards membrane performance), or in terms of fluxes and separation factors (oriented towards process performance), and how the interpretation of results is done may lead to very different conclusions (Luis et al., 2013; Luis & Van der Bruggen, 2015). On the other hand, membrane distillation is also considered as an alternative to conventional distillation but in a different way. In this case, the separation is determined by the thermodynamic equilibrium, like in distillation, but a lower energy consumption is envisaged. The selected operating conditions have a very significant effect on the membrane and process performances, but differently. Evaluating the mass and heat transfer coefficients is the only way to study the differences and design a process with an industrial orientation (Ruiz Salmón et al.) References : Luis P., Degrève J., Van der Bruggen B., 2013. Separation of methanol – n-butyl acetate mixtures by pervaporation: Potential of ten commercial membranes, Journal of Membrane Science, 429, 1–12. Luis P., Van der Bruggen B., 2015. The driving force as key element to evaluate the pervaporation performance of multicomponent mixtures, Separation and Purification Technology, 148, 94–102. Ruiz Salmón I., Janssens R., Luis P. Mass and heat transfer study in osmotic membrane distillation for CO2 valorization as sodium carbonate, submitted

IPSC differentiation into ependymal progenitors to treat ventricular damage during hydrocephalus

Introduction: During both obstructive congenital hydrocephalus and post-hemorrhagic hydrocephalus additional pathological events are intimately associated with their ethiology: a) a detrimental inflammatory response; b) severe damage of the underlying periventricular nervous tissue, including white matter, and c). Therapeutic approaches have been directed to overcome a) and b), however recovery of damaged neuroepithelium/ependyma is, in our present, an important therapeutic gap. Methods: Human and mouse induced pluripotent stem cells (iPSC) have been artificially differented into ependymal progenitors. Intracerebroventricular (ICV) injections of iPCS are performed ex vivo and in vivo in the damaged ventricular wall. Their integration and differentiation has been studied by immunohistochemistry and histopathological analysis. Results: Mice and human ependymal progenitors are able to integrate and differentiate into ependyma in damaged ventricular wall. Stage of ependymal differentiation by the time of the injection defined different degrees of integration. Conclusions: IPSC appear to be a good ependymal progenitor source with no ethical controversy associated.RyC 2014-16980 Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Neuroplasticity and Healthy Lifestyle: How Can We Understand This Relationship?

Our brain has this extraordinary ability to experience functional and structural changes before environmental stimuli, cognitive demand, or our experience itself. Exercise, diet, an appropriate sleep pattern, and reading habits are among those activities proposed to induce effects on cerebral architecture—an active lifestyle seems to induce changes in the brain function that favour welfare and better quality of life. This special issue is intended to extend the knowledge about the relationship between neuroplasticity and a healthy lifestyleFil: Begega, Azucena. Universidad de Oviedo; EspañaFil: Santín, Luis J.. Universidad de Málaga; EspañaFil: Galeano, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Cutuli, Debora. Universita Di Roma; ItaliaFil: Sampedro Piquero, Patricia. Universidad Autonoma de Madrid. Facultad de Psicología. Departamento de Psicología Biológica y de la Salud; Españ

Properties of ultra-cool dwarfs with Gaia. An assessment of the accuracy for the temperature determination

We aimed to assess the accuracy of the Gaia teff and logg estimates as derived with current models and observations. We assessed the validity of several inference techniques for deriving the physical parameters of ultra-cool dwarf stars. We used synthetic spectra derived from ultra-cool dwarf models to construct (train) the regression models. We derived the intrinsic uncertainties of the best inference models and assessed their validity by comparing the estimated parameters with the values derived in the bibliography for a sample of ultra-cool dwarf stars observed from the ground. We estimated the total number of ultra-cool dwarfs per spectral subtype, and obtained values that can be summarised (in orders of magnitude) as 400000 objects in the M5-L0 range, 600 objects between L0 and L5, 30 objects between L5 and T0, and 10 objects between T0 and T8. A bright ultra-cool dwarf (with teff=2500 K and \logg=3.5 will be detected by Gaia out to approximately 220 pc, while for teff=1500 K (spectral type L5) and the same surface gravity, this maximum distance reduces to 10-20 pc. The RMSE of the prediction deduced from ground-based spectra of ultra-cool dwarfs simulated at the Gaia spectral range and resolution, and for a Gaia magnitude G=20 is 213 K and 266 K for the models based on k-nearest neighbours and Gaussian process regression, respectively. These are total errors in the sense that they include the internal and external errors, with the latter caused by the inability of the synthetic spectral models (used for the construction of the regression models) to exactly reproduce the observed spectra, and by the large uncertainties in the current calibrations of spectral types and effective temperatures.Comment: 18 pages, 17 figures, accepted by Astronomy & Astrophysic

Identificación de patrones geomorfológicos a través de la interpretación de las razones entre bandas TM

7 páginas, 2 figuras, 18 referencias. Este trabajo se encuentra dentro del capítulo: Estratigrafía, Sedimentología y Geomorfología del Cuaternario. Desde el año 1972, AEQUA organiza Reuniones Nacionales de Cuaternario cada cuatro años. Se tiene una colaboración activa con el Grupo de Trabajo Portugués del Cuaternario (GTPEQ), con el que celebra cuatrianualmente congresos conjuntos denominados Reuniones del Cuaternario Ibérico. La referenciada es la II Reunión del Cuaternario Ibérico, Madrid, 25-29 septiembre, 1989. El ISBN de la obra completa: 84-7840-155-5.[EN]: A test area of 512 x 512 pixels, in the Doñana National Park, has been studied throug a Thematic Mapper image taken in February 1986. Three bands have been selected (TM3, TM4 and TM7) as well as two of their ratios (TM7/TM4 and TM4/TM3) containing enough information for the environmental study proposed. Different geomorphological and soil patterns have been identified, as well as their associated vegetation. Finally, these results have been compared with data Observed "in situ" to test their reliability.[ES]: Se realiza el estudio de un área test de 512 x 512 pixels, situada dentro del Parque Nacional de Doñana, a partir de una imagen tomada por el Thematic Mapper en febrero de 1986. Se seleccionan las bandas TM3, TM4 Y TM7, con las que se efectúan las razones TH1/TM4 y TM4/TM3 para la caracterizaci6n del medio físico. A partir de dichas bandas y combinaciones se identifican los principales patrones geomorfológicos, características edáficas y asociaciones vegetales de la zona. Estos resultados son posteriormente comparados y comprobados con observaciones sobre el terreno.Peer reviewe

Viability study of sailing propulsion combined with a conventional system

For many years now, sails have been used as a propulsion system. At present, they are restricted to recreational/sport crafts since the appearance of the first steam vessels in the beginning of the 19 th century. But in the last years, due to the increase of fuel price and the pollution of the environment, it is being studied the possibility to introduce again the sail as a propulsive method combined with other conventional systems. In this paper, it is studied the viability of using a sail as a propellant with other conventional systems of propulsion. After considering the concept of apparent wind, the range of use of this complementary propulsion is presented. The calculation methodology, the numerical simulations and the wind inputs from a specific route are also included