Optimization of Nanoparticle-Based SERS Substrates through Large-Scale Realistic Simulations

Surface-enhanced Raman scattering (SERS) has become a widely used spectroscopic technique for chemical identification, providing unbeaten sensitivity down to the singlemolecule level. The amplification of the optical near field produced by collective electron excitations plasmons in nanostructured metal surfaces gives rise to a dramatic increase by many orders of magnitude in the Raman scattering intensities from neighboring molecules. This effect strongly depends on the detailed geometry and composition of the plasmonsupporting metallic structures. However, the search for optimized SERS substrates has largely relied on empirical data, due in part to the complexity of the structures, whose simulation becomes prohibitively demanding. In this work, we use state-of-the-art electromagnetic computation techniques to produce predictive simulations for a wide range of nanoparticle-based SERS substrates, including realistic configurations consisting of random arrangements of hundreds of nanoparticles with various morphologies. This allows us to derive rules of thumb for the influence of particle anisotropy and substrate coverage on the obtained SERS enhancement and optimum spectral ranges of operation. Our results provide a solid background to understand and design optimized SERS substrates.Peer ReviewedPostprint (published version

Method for Aspect-Based Sentiment Annotation Using Rhetorical Analysis

This paper fills a gap in aspect-based sentiment analysis and aims to present a new method for preparing and analysing texts concerning opinion and generating user-friendly descriptive reports in natural language. We present a comprehensive set of techniques derived from Rhetorical Structure Theory and sentiment analysis to extract aspects from textual opinions and then build an abstractive summary of a set of opinions. Moreover, we propose aspect-aspect graphs to evaluate the importance of aspects and to filter out unimportant ones from the summary. Additionally, the paper presents a prototype solution of data flow with interesting and valuable results. The proposed method's results proved the high accuracy of aspect detection when applied to the gold standard dataset

Linear programming of a slate quarry

[Abstract] A new exploitation of roofing slate has several possibilities of marketing depending on the sizes of the pieces that it makes. Three sizes has been chosen among aH the possibilities in base of the conditions and the production of the rock in the quarry, the marketing limitation and the final price of the producto We've procces aH these data to obtain the optimun output, with the simplex algorithm. The objective function (week invoicing) and the restrictions of the problem are created in canonical and standard formo Optimun solution has been obtained among aH the basic and practical ones, using the graphic and the analytic method. Sorne conclusions come from the algorithm matrix about the outputs for each marketing option

Inter‐ and Intra‐Annual Variability of Nitrogen Concentrations in the Headwaters of the Mero River

This study examines the inter‐ and intra‐annual variability of different forms of N [total nitrogen (TN), nitrate‐nitrogen (N‐NO3) and total Kjeldahl nitrogen (TKN)] in stream waters of a rural headwater catchment in Galicia (NW Spain) during a 5‐year period, covering 2004–2009 water years (October–September). Daily time series were used to verify the temporal variability and to characterize the nitrogen pollution. The TN concentrations were low, although the values constantly exceeded the critical range (0.5–1.0 mg L−1) over which potential risk of eutrophication of water systems exists. Nitrate was the predominant form of nitrogen in the river throughout the study period, accounting for 82–85% of the TN. Significant differences were found for different forms of N between water years and seasons, indicative of wide inter‐ and intra‐annual variability of nitrogen concentrations, mainly related to rainfall and flow oscillations. The seasonal pattern in the concentrations of TN, N‐NO3 and TKN in stream water was similar to many humid and temperate catchments, with higher concentrations in winter, when variability was also the highest in the period, and lower values in summer

A General Iterative Procedure of the Non-Numerical Ranking Preferences Method for Multiple Objective Decision Making

AbstractMultiple objective evolutionary algorithms (MOEAs), which are biologically-inspired optimization methods, have become popular approaches to solve problems with multiple objective functions. With the use of MOEAs, multiple objective optimization becomes a two-part problem. First, the multiple objective optimization problem needs to be formulated and successfully solved using an MOEA. Then, a non- dominated set -also known as efficient or Pareto frontier- needs to be analyzed to select a solution to the problem. This can represent a challenging task to the decision-maker because this set can contain a large number of solutions. This decision- making stage is usually known as the post-Pareto analysis stage. This paper presents the generalization of a post-Pareto optimality method known as the non-numerical ranking preferences (NNRP) method originally proposed by Taboada et al. (2007). This method can help decision makers reduce the number of design possibilities to small subsets that clearly reflect their objective function preferences. Previous research has only presented the application of the NNRP method using three and four objective functions but had not been generalized to the case of n objective functions. The present paper expands the NNRP method to be able to consider multiple objective optimization problems with n number of objective functions

Improving the Understanding of N Transport in a Rural Catchment Under Atlantic Climate Conditions From the Analysis of the Concentration–Discharge Relationship Derived From a High-Frequency Data Set

[Abstract] Understanding processes controlling stream nutrient dynamics over time is crucial for implementing effective management strategies to prevent water quality degradation. In this respect, the study of the nutrient concentration–discharge (C–Q) relationship during individual runoff events can be a valuable tool for extrapolating the hydrochemical processes controlling nutrient fluxes in streams. This study investigated nitrogen concentration dynamics during events by analyzing and interpreting the nitrogen C–Q relationship in a small Atlantic (NW Iberian Peninsula) rural catchment. To this end, nitrate (NO3-N) and total Kjeldahl nitrogen (TKN) concentrations were monitored at a high temporal resolution during 102 runoff events over a 6-year period. For each of the selected runoff events, C–Q response was examined visually for the presence and direction of hysteresis loops and classified into three types of responses, namely clockwise, counterclockwise, and no hysteresis. Changes in concentration (ΔC) and the hysteresis direction (ΔR) were used to quantify nitrogen ( and TKN) patterns during the runoff events. The transport mechanisms varied between compounds. The most frequent hysteretic response for was counterclockwise with enrichment. On the contrary, the main TKN dynamic was enrichment with clockwise hysteresis. Event characteristics, such as rainfall amount, peak discharge (i.e., maximum discharge of the runoff event), and event magnitude relative to the initial baseflow (i.e., the difference between the maximum discharge of the runoff event and the initial baseflow divided by initial baseflow) provided a better explanation for hysteresis direction and magnitude for TKN than antecedent conditions (antecedent precipitation and baseflow at the beginning of the event). For hysteresis, the role of hydrometeorological conditions was more complex. The hysteresis magnitude was related to the magnitude of the event relative to the initial baseflow and the time elapsed since a preceding runoff event. These findings could be used as a reference for the development of N mitigation strategy in the region.This research has been supported by the Spanish Ministry of Education and Science (grant no. REN2003-08143) and Xunta of Galicia (grant nos. PGIDIT05RAG10303PR and 10MDS103031PR)Xunta of Galicia; PGIDIT05RAG10303PRXunta of Galicia; 10MDS103031P

Granite paleoweathering: A case-study under the tertiary deposit of Xinzo de Limia

[Resumen] Se estudia una paleoalteración desarrollada sobre granito y situada bajo un espesor de 120 m. de sedimentos en la cuenca terciaria de Xinzo de Limia (Ourense). El cambio minera16gico más significativo es la transformaci6n de las plagioclasas en caolinita. Se detectan también pequeñas proporciones de esmectitas. El estudio geoquímico revela una clara lixiviaci6n de bases, como lo pone de manifiesto la disminución de todos los índices de alteración (Indices de Parker, Reiche y pH de abrasi6n). El proceso de meteorización dominante es la monosialitización, con una cierta tendencia bisialítica en las primeras fases de la alteración.[Abstract] A granite paleoweathering located under 120 m of tertiary sediments at Xinzo de Limia (Galicia, NW Spain) is studied. The transformation ofplagioclase in kaolinite is the most important mineralogical change ocurred during the process. Minor proportions of smectite- are detected too. The geochemistry study reveales an evident lixiviation of bases, so the different weathering rates decrease as the process progresses (Parker and Reiche indexes and abrasion-pH). The dominant process of weathering is the monosialitization (PEDRO, 1979) although the first phases show a bisialitic trend

Characteristics principals of soils of Holguín province (Cuba). Use and soils management

[Abstract] In this paper was performed an compilation of the main characteristic and degradation processes of soils Holguín province (Cuba) in order to stablish a proposal management leading to soil preservation. The main soils in the zone are of four types. According to the cuban classification system the major soils are Fersialitics, Vertisoils, Bruns and Ferritic, which are respectively equivalent to the Luvisols, Vertisols, Cambisols and Ferralsols of the FAO system (1998). About 70% of the agricultural soils of the Holguín province are affected by different erosion degree. About 17% of soils are affected by salinity and are associated mainly to the group of Vertisoils, that in the greater part are dedicated to the sugarcane cultivated and at grassland. Together with the erosion and salinity procceses others limiting factors of the soils are the sodicity, contents of gravels and stones, efective deepth, carbonates content and relief