Uso de adubos verdes como estratégia para restabelecer a produção agrícola do sítio Hikari, Nova Friburgo, RJ, após evento climático.

Este texto relata como a autora principal, agricultora na comunidade Rio Grande, Nova Friburgo-RJ, em parceria com o Núcleo de Pesquisa e Treinamento para Agricultores (NPTA) da Embrapa na Região Serrana do Rio de Janeiro, estabeleceu estratégia no sentido de restabelecer a produção agrícola de sua propriedade, afetada por deslizamentos e enchentes provocadas pela maior catástrofe climática e geotécnica do país, ocorrida em janeiro de 2011.Trabalho apresentado no 4. Seminário de Agroecologia do Distrito Federal e Entorno, Brasília, DF

Siting study of solar thermoelectric plants in the State of Minas Gerais.

The generation of heliothermal electricity has received increasing attention throughout the world in countries such as Spain, the USA, Germany and many others. In Brazil, this type of energy generation in the form of large projects (above 80 MW) remains unexplored. However, it is known that in the country, there are extensive areas of normal direct irradiation with high intensity and a low seasonality factor, especially in the semiarid regions in Brazil, mainly the North and Northeast of Minas Gerais. Moreover, these Minas Gerais regions have other significant characteristics for the installation of these plants: proximity to transmission lines, flatness, the fact that the respective vegetation is not endangered, a suitable land use profile (availability of land not used in agriculture), low wind speed, low population density, and, most recently, an increase in the demand for local electric energy due to the economic growth above the Brazilian average rate. Furthermore, the introduction of solar plants in that region, due to its distributed nature, will bring development and growth to the region (normally poor) by generating employment and income. This article presents a study of the optimal location of thermoelectric plants in the semiarid regions of Minas Gerais, conducted with Geographical Information System (GIS) technology. GIS consists of a set of specialised resources that allow the manipulation of spatial data, bringing efficiency and agility in the identification of suitable places for the installation of solar plants, while simultaneously enabling the consideration of future scenarios for energy planning, with its respective impact, costs and benefits. The study has identified very promising solar irradiation levels for the electric generation by solar energy, whether thermoelectric or photovoltaic, reaching an annual solar irradiation of 2700 kWh/m² in the summer and in the range of 2200 - 2400 kWh/m² on an annual basis. This area includes a vast region in the North/Northeast of the state, which also has continuous and flat regions, with slopes inferior to 3%; in addition, high-quality hydro resources are abundant and well distributed. Furthermore, the Minas Gerais region has few areas with high agriculture profile and reduced quantity of protected units. Therefore, generally speaking, the coverage of the transmission lines in that region is suitable. Considering the most relevant aspects mentioned before, and taking as a reference the micro-region limits defined by the IBGE, the following micro-regions were classified as the most promising ones: 1) Janaúba, 2) Januária, 3) Pirapora and Unaí, 4) Pirapora and Paracatu, 5) Curvelo and Três Marias, and 6) Patrocínio and Araxá. Finally, it is important to highlight that this potential might be explored gradually in the medium term, with the shortage of other supply sources, the scale up and readiness of such technologies, as well as the creation of a complex solar-wind-hydro system that leverages the strong complementarity of such resources, as has been observed

Depth Profiling Photoelectron-Spectroscopic Study of an Organic Spin Valve with a Plasma-Modified Pentacene Spacer

[[abstract]]We report an enhanced magnetoresistance (MR) in an organic spin valve with an oxygen plasma-treated pentacene (PC) spacer. The spin valve containing PC without the treatment shows no MR effect, whereas those with moderately plasma-treated PC exhibit MR ratios up to 1.64% at room temperature. X-ray photoelectron spectroscopy with depth profiling is utilized to characterize the interfacial electronic properties of the plasma-treated PC spacer which shows the formation of a derivative oxide layer. The results suggest an alternative approach to improve the interface quality and in turn to enhance the MR performance in organic spin valves.[[incitationindex]]SCI[[booktype]]電子

Radius, girth and minimum degree

Funder: UK Research and Innovation; Id: http://dx.doi.org/10.13039/100014013Funder: Cambridge TrustFunder: University of Cambridge; Id: http://dx.doi.org/10.13039/501100000735Abstract: The objective of the present paper is to study the maximum radius r of a connected graph of order n , minimum degree δ ≥ 2 and girth at least g ≥ 4 . Erdős, Pach, Pollack and Tuza proved that if g = 4 , that is, the graph is triangle‐free, then r ≤ n − 2 δ + 12 , and noted that up to the value of the additive constant, this upper bound is tight. In this paper we shall determine the exact maximum. For larger values of g little is known. We settle the order of the maximum r for g = 6 , 8 and 12, and prove an upper bound for every even g , which we conjecture to be tight up to a constant factor. Finally, we show that our conjecture implies the so‐called Erdős girth conjecture

Fundamentos básicos de emissividade e sua correlação com os materiais refratários, conservação de energia e sustentabilidade

Nas indústrias de base ou de transformação tais como, siderúrgicas, metalúrgicas, petroquímicas, entre outras, a energia consumida para o aquecimento da carga sofre perdas tanto pela exaustão dos gases quanto pelos refratários que revestem internamente esses equipamentos industriais que trabalham em altas temperaturas. De acordo a literatura, a tinta de alta emissividade, quando aplicada sobre a superfície interna do revestimento refratário desses equipamentos, contribui para o retorno do calor ao sistema, reduzindo perdas energéticas e minimizando custos no processo produtivo. Neste artigo são discutidos os fundamentos básicos da teoria de emissividade, como a radiação térmica e a teoria de bandas de energia, e a sua correlação com a composição química e aplicação de tintas refratárias visando minimizar custos decorrentes do consumo energético e tornando a unidade produtiva mais sustentável