On a class of bivariate second-order linear partial difference equations and their monic orthogonal polynomial solutions

AbstractIn this paper we classify the bivariate second-order linear partial difference equations, which are admissible, potentially self-adjoint, and of hypergeometric type. Using vector matrix notation, explicit expressions for the coefficients of the three-term recurrence relations satisfied by monic orthogonal polynomial solutions are obtained in terms of the coefficients of the partial difference equation. Finally, we make a compilation of the examples existing in the literature belonging to the class analyzed in this paper, namely bivariate Charlier, Meixner, Kravchuk and Hahn orthogonal polynomials

The Surface Texturing of Monocrystalline Silicon with NH4OH and Ion Implantation for Applications in Solar Cells Compatible with CMOS Technology

AbstractThis work presents the development of photovoltaic cells based on p+/n junction in Si substrates, aimed at compatibility with fabrication processes with CMOS technology. The compatible processes, which are developed in this study, are the techniques:i) Si surface texturing, with the textured surface reflection of 15% obtained by the formation of micro-pyramids (heights between 3 and 7μm) using NH4OH (ammonium hydroxide) alkaline solution, which is free of undesirable contamination by Na+ and K+ ions, when NaOH and KOH traditional solutions are used, respectively, and ii) of the ECR-CVD (ElectronCyclotron Resonance - Chemical Vapor Deposition) deposition of SiNx (silicon nitride) anti-reflective coating (ARC), which is carried out at room temperature and can be performed after the end of cell fabrication without damage on metallic tracks and without variation of p+/n junction depth. The ARC coating characterization presented that the silicon nitride has a refractive index of 1.92 and a minimum reflectance of 1.03%, which is an excellent result for application in solar (or photovoltaic) cells. For the formation of the pn junction was used ion implantation process with 11B+, E=20KeV, dose of 1x1015cm2 and four rotations of 90° to get uniformity on texturized surfaces

Sensitivity monitoring of Phakopsora pachyrhizi populations to triazoles in Brazil.

Asian soybean rust (ASR) reported in 2001 in South America spread to Brazilian producing areas and is considered one of the main diseases of the crop. Fungicides used for the control belong to QoI (strobilurins) and SBI (azole) compounds. A weaker efficacy of straight azole was observed at some regions in the end of the crop season 2006/2007. To determine whether the problem observed was due to the resistance, a sensitivity monitoring test was carried out in 2008/2009 to detect possible changes in the EC50 values of the fungus population. The test was done according to FRAC methodology. Leaves samples infected with Phakopsora pachyrhizi were sent from nine Brazilian states, in a total of 36 populations, and the spores collected were inoculated in detached leaves treated with fungicides. The triazoles tested were cyproconazole, metconazole, tebuconazole, and prothioconazole (0; 0.125; 0.25; 0.5; 1.0; 2.0; 4.0; 8.0; 16.0; 32.0 ppm). Disease severity was evaluated 15 days after inoculation. The EC50 values were estimated by Proc Probit, SAS®. Differences in EC50 values among the populations were statistically significant (P < 0.01). The EC50 for cyproconazole and metconazole ranged from 0.06 to 1.37 ppm and from 0.02 to 3.89 ppm, respectively. For tebuconazole, EC50 ranged from 0.02 to 1.28 ppm. For prothioconazole, there wasn’t a distribution of EC50 values because, with 0.25 ppm, the populations tested didn’t develop symptoms of ASR. The results showed an oscillation of EC50 values in the P. pachyrhizi population from different locations during the crop season

Hemi-Synthesis and Anti-Oomycete Activity of Analogues of Isocordoin

Indexación: Web of Science; Scopus.An efficient synthesis of a series of 4-oxyalkyl-isocordoin analogues (2–8) is reported for the first time. Their structures were confirmed by1H-NMR,13C-NMR, and HRMS. Their anti-oomycete activity was evaluated by mycelium and spores inhibition assay against two selected pathogenic oomycetes strains: Saprolegnia parasitica and Saprolegnia australis. The entire series of isocordoin derivatives (except compound 7) showed high inhibitory activity against these oomycete strains. Among them, compound 2 exhibited strong activity, with minimum inhibitory concentration (MIC) and minimum oomyceticidal concentration (MOC) values of 50 µg/mL and 75 µg/mL, respectively. The results showed that 4-oxyalkylated analogues of isocordoin could be potential anti-oomycete agents.http://www.mdpi.com/1420-3049/22/6/96

Developing a Data-driven School Building Stock Energy and Indoor Environmental Quality Modelling Method

The school building sector has a pivotal role to play in the transition to a low carbon UK economy. School buildings are responsible for 15% of the country’s public sector carbon emissions, with space heating currently making up the largest proportion of energy use and associated costs in schools. Children spend a large part of their waking life in school buildings. There is substantial evidence that poor indoor air quality and thermal discomfort can have detrimental impacts on the performance, wellbeing and health of schoolchildren and school staff. Maintaining high indoor environmental quality whilst reducing energy demand and carbon emissions in schools is challenging due to the unique operational characteristics of school environments, e.g. high and intermittent occupancy densities or changes in occupancy patterns throughout the year. Furthermore, existing data show that 81% of the school building stock in England was constructed before 1976. Challenges facing the ageing school building stock may be exacerbated in the context of ongoing and future climate change. In recent decades, building stock modelling has been widely used to quantify and evaluate the current and future energy and indoor environmental quality performance of large numbers of buildings at the neighbourhood, city, regional or national level. Building stock models commonly use building archetypes, which aim to represent the diversity of building stocks through frequently occurring building typologies. The aim of this paper is to introduce the Data dRiven Engine for Archetype Models of Schools (DREAMS), a novel, data-driven, archetype-based school building stock modelling framework. DREAMS enables the detailed representation of the school building stock in England through the statistical analysis of two large scale and highly detailed databases provided by the UK Government: (i) the Property Data Survey Programme (PDSP) from the Department for Education (DfE), and (ii) Display Energy Certificates (DEC). In this paper, the development of 168 building archetypes representing 9,551 primary schools in England is presented. The energy consumption of the English primary school building stock was modelled for a typical year under the current climate using the widely tested and applied building performance software EnergyPlus. For the purposes of modelling validation, the DREAMS space heating demand predictions were compared against average measured energy consumption of the schools that were represented by each archetype. It was demonstrated that the simulated fossil-thermal energy consumption of a typical primary school in England was only 7% higher than measured energy consumption (139 kWh/m2/y simulated, compared to 130 kWh/m2/y measured). The building stock model performs better at predicting the energy performance of naturally ventilated buildings,which constitute 97% of the stock, than that of mechanically ventilated ones. The framework has also shown capabilities in predicting energy consumption on a more localised scale. The London primary school building stock was examined as a case study. School building stock modelling frameworks such as DREAMS can be powerful tools that aid decision-makers to quantify and evaluate the impact of a wide range of building stock-level policies, energy efficiency interventions and climate change scenarios on school energy and indoor environmental performance