Efecto de la composición del gas de refinería sobre las características del proceso de combustión

En este artículo de investigación científica se analiza el efecto del cambio de la composición del gas combustible (Gas de Refinería (GR) por Gas Natural (GN)) sobre las características del proceso combustión en hornos de la industria de refinación del petróleo; se evaluó el poder calorífico, el índice de Wobbe (IW) y exceso de oxígeno, para mezclas combustibles de composición variable. Mediante simulación computacional del proceso de combustión se calculó la temperatura adiabática de lama, eficiencia y la composición de los productos de combustión. Se evaluaron mezclas de gases combustibles con poderes caloríficos entre 800-2500 Btu/pie3 y se compararon con la combustión de gas natural. Se registró variabilidad en la temperatura adiabática y la eficiencia en función de la composición del gas y el exceso de oxígeno, lo que genera inestabilidad en el horno y mayor impacto ambiental

Reflexiones sobre el Framework de desarrollo del Consejo Superior de Investigaciones Científicas

El Consejo Superior de Investigaciones Científicas (CSIC) ha definido un marco común para realizar sus desarrollos. Dicho marco representa una ventaja estratégica gracias a su enorme flexibilidad. Tal maleabilidad permite la integración constante de nuevas tecnologías o la incorporación de nuevas tendencias en el cambiante mundo del desarrollo de aplicaciones. La presente comunicación propone una discusión sobre los problemas y las soluciones ofertadas en la evolución de los sistemas de información en plataforma Web del CSIC hacia modelos más participativos, propios de la investigación científica, que confluyen con los postulados de la Web 2.0.Peer reviewe

Assessment of the CPL-0015 isolate as a vaccine strain for the control of canine parvovirus in Cuba

The safety and protective efficacy of the CPL-0015 Cuban isolate of canine parvovirus type 2 (CPV-2) were evaluated for its possible use as a vaccine strain candidate. The study included a total of 23 healthy Beagle dogs of both sexes, aged 84 days and without specific maternal antibodies against canine parvovirus. Safety was analysed by comparing clinicopathological values, food consumption, body weight, rectal temperature and white blood cell counts for 14 consecutive days between control dogs (n=5) and dogs subcutaneously injected (n=10) with 2 mL (equivalent to two doses) of the CPL-0015 strain with an antigenic titer of 106.0 infectious dose50 in cell culture/mL. The protective effectiveness was determined by measuring and comparing anti-CPV-2 IgG levels and clinical signs during 56 experimental days between control dogs (n=2) and dogs inoculated (n=6) with double doses of 1 mL each, separated by a 21-day interval. All animals were challenged orally on day 35 with the virulent strain Cornell-780916 (105.0 infective dose50 in cell culture/mL). The results showed that the CPL-0015 strain did not negatively impact the physiological condition of the exposed animals. The inoculated and challenged animals showed not only significantly increased levels of anti-CPV-2 IgG (P<0.05) when compared to days 0, 35, and the control group animals but also had 100% survival without clinical signs of the disease, unlike the control group. It is concluded that CPL-0015 is safe and provides effective protection against homologous virulent strains

Sobre la ecología de Brycon siebenthalae y Mylossoma duriventris (Piscis: Characidae), en el río Cafre, Orinoquia

En este trabajo se reportan nuevos aspectos sobre la biología de Bryeon siebenthalae (yamú) y de Mylossoma duriventris (palometa). La reproducción de especies está altamente relacionada con la estacionalidad hídrica (lluvias-sequías) la palometa desova tan pronto comienzan las lluvias a finales de abril, con un promedio de 125.000 huevos; el yamú desova aproximadamente 231.000 huevos, dos a tres semanas más tarde, mediados de mayo. El alto número de huevos implica que el desove debe efectuarse en niveles de aguas que faciliten su dispersión. Las dos especies comparten los hábitat (cursos del río, planos inundables). Es característico del yamú su mayor desplazamiento al remontar grandes corrientes y raudales, en el desarrollo de su comportamiento migratorio de tipo longitudinal, a diferencia de la palometa cuyos movimientos son preleriblemente de tipo local y lateral a la corriente. En ambas especies predomina un hábito alimenticio macroherbívoro, correspondiente a frutos, semillas, hojas. flores y cortezas: para el yamú en un 93% y para la palometa en 99%.The ecology of the characids Bryeon siebenthalaey Mylossoma duriventriswas studied in the lower part of the río Cafre, a tributary of was studied the río Guayabero in the upper part of the río Guaviare system in Colombia. These lishes spawn in the early rainy season; theír diet consist mainly 01 Iruits, seeds, flowers and bark

Eficácia in vitro de extratos vegetais no controle do carrapato Rhipicephalus (Boophilus) microplus.

O carrapato do boi, Rhipicephalus (Boophilus) microplus (Canestrini, 1887), principal ectoparasita dos bovinos nas regiões tropicais e subtropicas, é responsável por diversas perdas econômicas na bovinocultura, dentre as quais temos, perda de peso e depreciação do couro, transmissão de hemoparasitas, espoliação sanguínea e elevados custos ao seu controle. O uso indiscriminado de produtos químicos para o controle desse ectoparasita tem levado ao desenvolvimento de resistência aos princípios químicos, além dos danos ambientais. Diante dessas circunstâncias, os fitoterápicos têm sido avaliados como um método de controle alternativo, visto que, dependendo da espécie vegetal, podem promover desenvolvimento lento da resistência, têm baixo custo e são biodegradáveis, não causando danos ao meio ambiente. O objetivo deste trabalho foi avaliar a eficácia in vitro de seis extratos vegetais em diferentes concentrações sobre fêmeas ingurgitadas (teleóginas) de R. microplus

Phosphorylation and Activation of the Plasma Membrane Na+/H+ Exchanger (NHE1) during Osmotic Cell Shrinkage

The Na+/H+ Exchanger isoform 1 (NHE1) is a highly versatile, broadly distributed and precisely controlled transport protein that mediates volume and pH regulation in most cell types. NHE1 phosphorylation contributes to Na+/H+ exchange activity in response to phorbol esters, growth factors or protein phosphatase inhibitors, but has not been observed during activation by osmotic cell shrinkage (OCS). We examined the role of NHE1 phosphorylation during activation by OCS, using an ideal model system, the Amphiuma tridactylum red blood cell (atRBC). Na+/H+ exchange in atRBCs is mediated by an NHE1 homolog (atNHE1) that is 79% identical to human NHE1 at the amino acid level. NHE1 activity in atRBCs is exceptionally robust in that transport activity can increase more than 2 orders of magnitude from rest to full activation. Michaelis-Menten transport kinetics indicates that either OCS or treatment with the phosphatase inhibitor calyculin-A (CLA) increase Na+ transport capacity without affecting transport affinity (Km = 44 mM) in atRBCs. CLA and OCS act non-additively to activate atNHE1, indicating convergent, phosphorylation-dependent signaling in atNHE1 activation. In situ 32P labeling and immunoprecipitation demonstrates that the net phosphorylation of atNHE1 is increased 4-fold during OCS coinciding with a more than 2-order increase in Na+ transport activity. This is the first reported evidence of increased NHE1 phosphorylation during OCS in any vertebrate cell type. Finally, liquid chromatography and mass spectrometry (LC-MS/MS) analysis of atNHE1 immunoprecipitated from atRBC membranes reveals 9 phosphorylated serine/threonine residues, suggesting that activation of atNHE1 involves multiple phosphorylation and/or dephosphorylation events

Hyperpolarizability of plasmonic meta-atoms in metasurfaces

Plasmonic metasurfaces are promising as enablers of nanoscale nonlinear optics and flat nonlinear optical components. Nonlinear optical responses of such metasurfaces are determined by the nonlinear optical properties of individual nanostructured plasmonic meta-atoms, which are the building blocks of the metasurfaces. Unfortunately, no simple methods exist to determine the nonlinear coefficients (hyperpolarizabilities) of the meta-atoms hindering designing of nonlinear metasurfaces. Here, we develop the equivalent RLC circuit model of such meta-atoms to estimate their second-order nonlinear optical parameter i.e. the first-order hyperpolarizability in the optical spectral range. In parallel, we extract from second-harmonic generation experiments the spectrum of the 1st-order hyperpolarizabilities of individual meta-atoms consisting of asymmetrically shaped (elongated) plasmonic nanoprisms. Moreover, we verify our results using nonlinear hydrodynamic-FDTD and with calculations based on nonlinear scattering theory. All three approaches: analytical, experimental, and computational, yield results that agree very well. Our empirical RLC model can thus be used as a simple tool to enable efficient design of nonlinear plasmonic metasurfaces

Development, intercomparison, and evaluation of an improved mechanism for the oxidation of dimethyl sulfide in the UKCA model

Dimethyl sulfide (DMS) is an important trace gas emitted from the ocean. The oxidation of DMS has long been recognised as being important for global climate through the role DMS plays in setting the sulfate aerosol background in the troposphere. However, the mechanisms in which DMS is oxidised are very complex and have proved elusive to accurately determine in spite of decades of research. As a result the representation of DMS oxidation in global chemistry–climate models is often greatly simplified. Recent field observations and laboratory and ab initio studies have prompted renewed efforts in understanding the DMS oxidation mechanism, with implications for constraining the uncertainty in the oxidation mechanism of DMS as incorporated in global chemistry–climate models. Here we build on recent evidence and develop a new DMS mechanism for inclusion in the UK Chemistry Aerosol (UKCA) chemistry–climate model. We compare our new mechanism (CS2-HPMTF) to a number of existing mechanisms used in UKCA (including the highly simplified three-reactions–two-species mechanism used in CMIP6 studies with the model) and to a range of recently developed mechanisms reported in the literature through a series of global and box model experiments. Global model runs with the new mechanism enable us to simulate the global distribution of hydroperoxylmethyl thioformate (HPMTF), which we calculate to have a burden of 2.6–26 Gg S (in good agreement with the literature range of 0.7–18 Gg S). We show that the sinks of HPMTF dominate uncertainty in the budget, not the rate of the isomerisation reaction forming it and that, based on the observed DMS / HPMTF ratio from the global surveys during the NASA Atmospheric Tomography mission (ATom), rapid cloud uptake of HPMTF worsens the model–observation comparison. Our box model experiments highlight that there is significant variance in simulated secondary oxidation products from DMS across mechanisms used in the literature, with significant divergence in the sensitivity of the rates of formation of these products to temperature exhibited; especially for methane sulfonic acid (MSA). Our global model studies show that our updated DMS scheme performs better than the current scheme used in UKCA when compared against a suite of surface and aircraft observations. However, sensitivity studies underscore the need for further laboratory and observational constraints. In particular our results suggest that as a priority long-term DMS observations be made to better constrain the highly uncertain inputs into the system and that laboratory studies be performed that address (1) the uptake of HPMTF onto aerosol surfaces and the products of this reaction and (2) the kinetics and products of the following reactions: CH3SO3 decomposition, CH3S + O2, CH3SOO decomposition, and CH3SO + O3.</p

El ciclo celular

ResumenEl proceso conocido como ciclo celular es de gran importacia para la c&eacute;lula ya que tiene como funci&oacute;n la formaci&oacute;n completa de una nueva c&eacute;lula, evitando en lo posible la creaci&oacute;n de c&eacute;lulas con m&uacute;ltiples errorres, lo cual le permite al organismo permanecer en un constante&nbsp;equilibrio, previeniendo as&iacute;&nbsp;aquellos des&oacute;rdenes&nbsp;que pueden perjudicar su salud; de esta manera, todas las c&eacute;lular est&aacute;n controladas por prote&iacute;nas que no permiten que se presenten situaciones desastrosas para un ser vivo.[Lomanto LD, Ortiz OL, Bret&oacute;n CO, G&oacute;mez AL, Mesa VM. El ciclo celular. MedUNAB 2003; 6(16):21-29].Palabras clave: Ciclo celular, factor promotor de mitosis, prote&iacute;na RB o 104, clinicas, cinasas