Magnon delocalization in ferromagnetic chains with long-range correlated disorder

We study one-magnon excitations in a random ferromagnetic Heisenberg chain with long-range correlations in the coupling constant distribution. By employing an exact diagonalization procedure, we compute the localization length of all one-magnon states within the band of allowed energies $E$. The random distribution of coupling constants was assumed to have a power spectrum decaying as $S(k)\propto 1/k^{\alpha}$. We found that for $\alpha < 1$, one-magnon excitations remain exponentially localized with the localization length $\xi$ diverging as 1/E. For $\alpha = 1$ a faster divergence of $\xi$ is obtained. For any $\alpha > 1$, a phase of delocalized magnons emerges at the bottom of the band. We characterize the scaling behavior of the localization length on all regimes and relate it with the scaling properties of the long-range correlated exchange coupling distribution.Comment: 7 Pages, 5 figures, to appear in Phys. Rev.

Nanocomposite gels of poloxamine and Laponite for β-Lapachone release in anticancer therapy

Nano-hybrid systems have been shown to be an attractive platform for drug delivery. Laponite® RD (LAP), a biocompatible synthetic clay, has been exploited for its ability to establish of strong secondary interactions with guest compounds and hybridization with polymers or small molecules that improves, for instance, cell adhesion, proliferation, and differentiation or facilitates drug attachment to their surfaces through charge interaction. In this work, LAP was combined with Tetronics, X-shaped amphiphilic PPO-PEO (poly (propylene oxide)–poly (ethylene oxide) block copolymers. β-Lapachone (BLPC) was selected for its anticancer activity and its limited bioavailability due to very low aqueous solubility, with the aim to improve this by using LAP/Tetronic nano-hybrid systems. The nanocarriers were prepared over a range of Tetronic 1304 concentrations (1 to 20% w/w) and LAP (0 to 3% w/w). A combination of physicochemical methods was employed to characterize the hybrid systems, including rheology, particle size and shape (DLS, TEM), thermal analysis (TG and DSC), FTIR, solubility studies and drug release experiments. In vitro cytotoxicity assays were performed with BALB/3T3 and MCF-7 cell lines. In hybrid systems, a sol-gel transition can occur below physiological temperature. BLPC exhibits the most significant increase in solubility in formulations with a high concentration of T1304 (over 10% w/w) and 1.5% w/w LAP, or systems with only LAP (1.5%), with a 50 and 100-fold increase in solubilisation, respectively. TEM images showed spherical micelles of T1304, which elongated into wormlike micelles with concentration (20%) and in the presence of LAP, a finding that has not been reported before. A sustained release of BLPC over 140 hours was achieved in one of the formulations (10% T1304 with 1.5% laponite), which also showed the best selectivity index towards cancer cells (MCF-7) over BALB/3T3 cell lines. In conclusion, BLPC-loaded T1304/LAP nano-hybrid systems proved safe and highly effective and are thus a promising formulation for anticancer therapy.Financial support for this research was provided by the Coordination of Improvement of Higher-Level Personnel - Brazil (CAPES) - 1575/2015. We also acknowledge the collaboration of Prof. Dr. Daniele Ribeiro de Araujo from Federal University of ABC for the rheological experiments. Dr. Raquel de Melo Barbosa acknowledges the grant for mobility to Brazilian professors from Fundación Carolina (Spain), the Spanish research group CTS-946, to the Centre for Scientific Instrumentation (Centro de Instrumentación Científica or CIC) for transmission microscopy analysis and the Andalusian Earth Sciences Institute (IACT) for support during her mobility period in Spain

Características físicas da carne de ovinos Morada Nova alimentados com farelos de biscoito e de castanha de caju como fontes alternativas de energia.

A utilização de subprodutos industriais vem se tornando uma alternativa cada vez mais presente na dieta dos animais, por apresentar bom valor nutricional e disponibilidade para ser usado como opção de fonte energética e proteica. Objetivou-se determinar o efeito das dietas energéticas sobre as características físicas da carne de ovinos Morada Nova.Edición de las Memorias de la 25a. Reunión de la Asociación Latinoamericana de Producción Animal (ALPA), 2016, Recife, Brasil

Desenvolvimento de tecnologias para a produção integrada de banana no Submédio do Vale do São Francisco.

O presente trabalho teve como objetivo gerar, validar e transferir tecnologias e conhecimentos sobre o Sistema de Produção Integrada de Banana para agricultores familiares na região do Submédio do Vale do São Francisco

Produção e qualidade da videira Superior Seedless sob restrição hídrica na fase de maturação.

O objetivo deste trabalho foi avaliar o efeito das condições de defi cit hídrico, na fase de maturação da uva, sobre a produção e qualidade da uva 'Superior Seedless' entre julho e novembro de 2007. O experimento foi realizado em delineamento de blocos ao acaso, com quatro repetições, em arranjo fatorial (3x3) + 1: três épocas de alteração da aplicação das lâminas de irrigação (21, 13 e 5 dias antes da colheita); três lâminas de irrigação (100, 50 e 0% da evapotranspiração da cultura); e um tratamento controle (manejo de irrigação adotado pelo produtor). As épocas de irrigação e as lâminas de irrigação utilizadas infl uenciaram a fi rmeza das bagas e a acidez titulável. A interrupção da irrigação, aos 13 ou 21 dias antes da colheita, resultou em produtividade, qualidade de frutos e efi ciência do uso da água semelhante às obtidas pelo produtor, assim, pode ser adotada para economia da água de irrigação na Região do Submédio do Vale do São Francisco

Uso do LiDAR na estimativa de atributos florestais: uma revisão.

Estudos com o LiDAR (Light Detection and Ranging) têm revelado precisão satisfatória nas medições da estrutura de árvores, o que tem contribuído para a compreensão dos ecossistemas florestais, bem como para o fornecimento de dados necessários para a investigação de propriedades biofísicas da floresta. Frente à importância dessa ferramenta, o presente estudo teve como objetivo apresentar uma revisão sobre o LiDAR direcionado para aplicações florestais, e especificamente apresentar suas possibilidades e uso na Caatinga. A varredura a laser tem diversas classificações, uma delas baseia-se na plataforma onde o scanner está instalado. Assim, tem-se o laser scanner terrestre, que pode ser usado em uma base fixa ou móvel na superfície terrestre; o laser scanner aéreo, com o uso de aeronaves tripuladas e não-tripuladas; e o laser scanner orbital, localizado em plataformas espaciais. Em escala refinada, a estrutura tridimensional das árvores pode ser detectada pelo LiDAR, e assim se obter importantes informações de traços de espécies vegetais, bem como permitir sua identificação. Ainda, a medição de atributos florestais promovida pelos diferentes tipos de LiDAR tem fornecido dados consistentes de biomassa e carbono florestais, importantes para o desenvolvimento de estudos e monitoramento de estoque de carbono terrestre, o que tem colaborado com as estratégias de redução de efeitos das mudanças climáticas. Na caatinga, o LiDAR tem permitido a contabilização de árvores e a determinação de sua altura e diâmetro da copa, e por conseguinte, a aplicação de equações alométricas para estimativa dos estoques de carbono na vegetação

Sink or carbon source? how the Opuntia cactus agroecosystem interacts in the use of carbon, nutrients and radiation in the Brazilian semi-arid region.

Anthropogenic disturbances directly influence environmental processes and increase the concentration of carbon (C) in the atmosphere. Here, we compare the differences in the seasonality of the balance of carbon, energy, and radiation, as well as seek to identify the interrelationships between these environmental variables and their impact on the growth of Opuntia cactus. Data were acquired from an eddy covariance flux tower over a cactus crop agroecosystem (2019–2021) in the Brazilian semi-arid region. In addition, we use plant growth rates, carbon and nutrient stocks, evapotranspiration (ET) and water use efficiency (WUE), and radiation (RUE). We show that the closure of the surface energy balance was 71%, although there are minimal fluxes of available energy lost (29%) by unquantified processes. At all seasons, the highest net ecosystem CO2 exchange (NEE) rate was between 11:00–13:00 (�� 5.75 μmol m�� 2 s�� 1). During the dry and wet-dry season, there was the lowest daily gross primary productivity (GPP) (2.5 μmol m�� 2 s�� 1) and net radiation—Rn (217.97 W m�� 2). Ecosystem respiration was more expressive during the wet season (2.41 μmol m�� 2 s�� 1), and maximum diurnal value of 2.65 μmol m�� 2 s�� 1. Furthermore, the latent heat flux was higher during the wet season (114.68 W m�� 2) and lowered in the dry season (9.39 W m�� 2). The net assimilation rate showed higher values during the dry-wet transition. The dry season presented higher nutrient use efficiency and WUE (14.77 g m�� 2 mm�� 1). The highest ET occurred during the wet season (227 mm), and RUE was 81.48% higher than in the dry season. Overall, the cactus was a potential C sink during the three years of assessment (NEE: �� 377 g C m�� 2 year�� 1; GPP: 881 g C m�� 2 year�� 1). The results help us to understand that most of the Rn energy is used in the sensible heat flux (58% ratio)

Monitoring energy balance, turbulent flux partitioning, evapotranspiration and biophysical parameters of Nopalea cochenillifera (Cactaceae) in the Brazilian Semi-Arid environment.

The in-situ quantification of turbulent flux and evapotranspiration (ET) is necessary to monitor crop performance in stressful environments. Although cacti can withstand stressful conditions, plant responses and plant?environment interactions remain unclear. Hence, the objective of our study was to investigate the interannual and seasonal behaviour of components of the surface energy balance, environmental conditions, morphophysiological parameters, biomass yield and water relations in a crop of Nopalea cochenillifera in the semi-arid region of Brazil. The data were collected from a micrometeorological tower between 2015 and 2017. The results demonstrate that net radiation was significantly higher during the wet season. Latent heat flux was not significant between the wet season and dry season. During the dry-wet transition season in particular, sensible heat flux was higher than during the other seasons. We observed a large decline in soil heat flux during the wet season. There was no difference in ET during the wet or dry seasons; however, there was a 40% reduction during the dry-wet transition. The wet seasons and wet-dry transition showed the lowest Evaporative Stress Index. The plants showed high cladode water content and biomass during the evaluation period. In conclusion, these findings indicate high rates of growth, high biomass and a high cladode water content and explain the response of the cactus regarding energy partitioning and ET