Fundamentals and Applications of Surface-Enhanced Raman Spectroscopy (SERS)

When a molecule is adsorbed on some metallic nanostructured surfaces such as silver, copper or gold, it can undergo an enormous enhancement of the Raman signal giving rise to the so called Surface-Enhanced Raman Scattering (SERS). The high sensitivity of this effect allows an accurate structural study of adsorbates at very low concentrations. The SERS effect has historically been associated with the substrate roughness on two characteristic length scales. Surface roughness on the 10 to 100 nm length scale supports localized plasmon resonances which are considered as the dominant enhancement mechanism of SERS (Electromagnetic Enhancement Mechanism: SERS-EM). It is usually accepted that these electromagnetic resonances can increase the scattered intensity by an average factor of ca. 104 to 107. A secondary mechanism often thought to require atomic scale roughness is referred to as Charge Transfer (CT) Enhancement Mechanism (SERS-CT). This mechanism involves the photoinduced transfer of an electron from the metal to the adsorbate or vice versa and involves new electronic excited CT states which result from adsorbate–substrate chemical interactions. It is also estimated that such SERS-CT mechanism can enhance the scattering cross-section by a factor of ca. 10 to 102. These two mechanisms can operate simultaneously, depending on the particular systems and experimental conditions, making difficult to recognize each one and to estimate their relative magnitude in a particular spectrum.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A to Z of the Muon anomalous magnetic moment in the MSSM with Pati-Salam at the GUT scale

We analyse the low energy predictions of the minimal supersymmetric standard model (MSSM) arising from a GUT scale Pati-Salam gauge group further constrained by an A4 × Z5 family symmetry, resulting in four soft scalar masses at the GUT scale: one left-handed soft mass m0 and three right-handed soft masses m1, m2, m3, one for each generation. We demonstrate that this model, which was initially developed to describe the neutrino sector, can explain collider and non-collider measurements such as the dark matter relic density, the Higgs boson mass and, in particular, the anomalous magnetic moment of the muon (g − 2)μ. Since about two decades, (g − 2)μ suffers a puzzling about 3σ excessoftheexperimentallymeasuredvalueoverthetheoreticalprediction,whichour model is able to fully resolve. As the consequence of this resolution, our model predicts specific regions of the parameter space with the specific properties including light smuons and neutralinos, which could also potentially explain di-lepton excesses observed by CMS and ATLAS

Loving Outside the Neighborhood: The Conflicting Effects of External Linkages on Incremental Innovation in Clusters

[EN] The present study assesses the explanatory capacity of three levels of factors, namely, internal to the company, and internal and external to the cluster, in predicting firms' incremental innovative performance in cluster contexts. The empirical research conducted here focuses on a sample of 92 companies from the Spanish textile industrial cluster in Valencia. Findings reveal that the signifi- cant role played by firms' interorganizational ties as a moderating factor between absorptive capacity and their incremental innovative performance. Additionally, results reflect the differenti- ated roles developed by intra- and extra-cluster linkages in these interaction processes.Tomas Miquel, JV.; Molina-Morales, FX.; Expósito-Langa, M. (2019). Loving Outside the Neighborhood: The Conflicting Effects of External Linkages on Incremental Innovation in Clusters. Journal of Small Business Management. 57(4):1738-1756. https://doi.org/10.1111/jsbm.12439S17381756574Acs, Z., & Audretsch, D. 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Conceptions about carbon dioxide and its influence on climate change: evaluative and experimental didactic intervention

El cambio climático es un tema de máxima importancia para la sociedad global y de interés particular para las ciencias naturales, frecuentemente abordado por los medios de comunicación y discutido en diferentes sectores de la población. El presente artículo muestra la exploración de las concepciones respecto al CO2 y su influencia en el cambio climático, en un grupo de estudiantes universitarios de Química General. Para el estudio, se empleó un cuestionario tipo Likert como instrumento de pruebas inicial (pretest) y final (postest), intercaladas con una intervención didáctica basada en la experimentación con el uso de un kit para la generación, recolección e identificación de CO2 y la posterior discusión de material audiovisual y bibliográfico especializado. Los resultados mostraron la existencia de preconcepciones, poco conocimiento científico del fenómeno y fuerte tendencia a pensar que el dióxido de carbono es el factor principal en los problemas de cambio climático y que el ser humano es el responsable de dicho fenómeno. La intervención didáctica fue motivante y favorable para mover las preconcepciones hacia un conocimiento científicamente más estructurado. Este estudio permite avanzar en la construcción de una propuesta de educación científica climática que realmente ayude a involucrar a la sociedad en la resolución de los problemas ambientales.Climate change is an extremely important issue for global society, and a special topic for natural sciences. This subject is frequently presented by communication media and discussed in different sectors of the population. This article shows the exploration of the conceptions regarding CO2 and its influence on climate change, in a group of university General Chemistry students. A Likert-type test was used as instrument for initial exploration (pretest) and final assessment (posttest), intercalated by a didactic intervention based on experimental activities with a kit for generating, collecting, and identification of CO2. These experimental activities were accompanied with a subsequent discussion about specialized (bibliographic and audiovisual) study material. Results showed the existence of misconceptions, scarce scientific knowledge on the climatic phenomenon, and a strong trend for thinking that carbon dioxide is the main factor in the climate change problems. Furthermore, student responses revealed the tendency to believe that the human being is almost the unique element responsible of such phenomenon. The didactic intervention was favorable and motivating to remove the misconceptions and build a scientifically more structured knowledge. The present work allows advancing on the construction of a (scientific) climate educational proposal for helping the society and involving the people in the solving of environmental problems

Calculation of kinetic parameters βeff and Λ with modified open source Monte Carlo code OpenMC(TD)

This work presents the methodology used to expand the capabilities of the Monte Carlo code OpenMC for the calculation of reactor kinetic parameters: effective delayed neutron fraction βeff and neutron generation time Λ. The modified code, OpenMC(Time-Dependent) or OpenMC(TD), was then used to calculate the effective delayed neutron fraction by using the prompt method, while the neutron generation time was estimated using the pulsed method, fitting Λ to the decay of the neutron population. OpenMC(TD) is intended to serve as an alternative for the estimation of kinetic parameters when licensed codes are not available. The results obtained are compared to experimental data and MCNP calculated values for 18 benchmark configurations.Fil: Romero Barrientos, J.. Comision Chilena de Energia Nuclear; Chile. Universidad de Chile; ChileFil: Marquez Damian, Jose Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. European Spallation Source; SueciaFil: Molina, F.. Comision Chilena de Energia Nuclear; Chile. Universidad Andrés Bello; ChileFil: Zambra, M.. Comision Chilena de Energia Nuclear; Chile. Universidad Diego Portales; ChileFil: Aguilera, P.. Comision Chilena de Energia Nuclear; Chile. Universidad de Chile; ChileFil: López Usquiano, F.. Comision Chilena de Energia Nuclear; Chile. Universidad de Chile; ChileFil: Parra, B.. Instituto de Física Corpuscular; EspañaFil: Ruiz, A.. Comision Chilena de Energia Nuclear; Chile. Universidad de Chile; Chil

Wastewater treatment using microalgae: how realistic a contribution might it be to significant urban wastewater treatment?

Microalgae have been proposed as an option for wastewater treatment since the 1960’s but still this technology has not been expanded to an industrial scale. In this paper, the major factors limiting the performance of these systems are analysed. The composition of the wastewater is highly relevant, and especially the presence of pollutants such as heavy metals and emerging compounds. Biological and engineering aspects are also critical and have to be improved to at least approximate the performance of conventional systems, not just in terms of capacity and efficiency but also in terms of robustness. Finally, the harvesting of the biomass and its processing into valuable products poses a challenge; yet at the same time, an opportunity exists to increase economic profitability. Land requirement is a major bottleneck that can be ameliorated by improving the system’s photosynthetic efficiency. Land requirement has a significant impact on the economic balance but the profits from the biomass produced can enhance these systems’ reliability, especially in small cities

Design of energy control method for three-phase buck-type rectifier with very demanding load steps

Conventional three-phase rectifiers are controlled to achieve good power factor and low THD in the input. In the case of pulsating power loads, the fast dynamic response implies that the load pulses are reflected in the generator. These pulsating loads affect the life time operation of the generator, especially when it is not oversized (that is the case in aircraft applications). In order to smooth the power demanded from the generator, it is preferable to reduce the bandwidth of the controller to the rectifier but it affects its stability due to the fact that the right half plane pole given by the negative impedance of a constant power load requires high bandwidth control loop to compensate it. In this paper, an energy control method is proposed to employ the energy stored in the output capacitor of the rectifier to control the amount of power demanded through the rectifier. In such a way the bandwidth restriction for stability is eliminated and the bandwidth of the loop can be set slow enough to ensure smooth power demanded from the generator

The shade avoidance syndrome in Arabidopsis : the antagonistic role of phytochrome A and B differentiates vegetation proximity and canopy shade

Light limitation caused by dense vegetation is one of the greatest threats to plant survival in natural environments. Plants detect such neighboring vegetation as a reduction in the red to far-red ratio (R:FR) of the incoming light. The low R:FR signal, perceived by phytochromes, initiates a set of responses collectively known as the shade avoidance syndrome, intended to reduce the degree of current or future shade from neighbors by overtopping such competitors or inducing flowering to ensure seed production. At the seedling stage these responses include increased hypocotyl elongation. We have systematically analyzed the Arabidopsis seedling response and the contribution of phyA and phyB to perception of decreased R:FR, at three different levels of photosynthetically active radiation. Our results show that the shade avoidance syndrome, induced by phyB deactivation, is gradually antagonized by phyA, operating through the so-called FR-High Irradiance Response, in response to high FR levels in a range that simulates plant canopy shade. The data indicate that the R:FR signal distinguishes between the presence of proximal, but non-shading, neighbors and direct foliar shade, via a intrafamily photosensory attenuation mechanism that acts to suppress excessive reversion toward skotomorphogenic development under prolonged direct vegetation shade

Selection of native Tunisian microalgae for simultaneous wastewater treatment and biofuel production

This paper focuses on the selection of native microalgae strains suitable for wastewater treatment and biofuel production. Four Chlorophyceae strains were isolated from North-eastern Tunisia. Their performances were compared in continuous mode at a 0.3 1/day dilution rate. The biomass productivity and nutrient removal capacity of each microalgae strain were studied. The most efficient strain was identified as Scenedesmus sp. and experiments at different dilution rates from 0.2 to 0.8 1/day were carried out. Maximal biomass productivity of 0.92 g/L·day was obtained at 0.6 1/day. The removal of chemical oxygen demand (COD), ammonium and phosphorus was in the range of 92-94%, 61-99% and 93-99%, respectively. Carbohydrates were the major biomass fraction followed by lipids and then proteins. The saponifiable fatty acid content was in the 4.9-13.2% dry biomass range, with more than 50% of total fatty acids being composed of saturated and monosaturated fatty acids