Faceted anomalous scaling in the epitaxial growth of semiconductor films

We apply the generic dynamical scaling theory (GDST) to the surfaces of CdTe polycrystalline films grown in glass substrates. The analysed data were obtained with a stylus profiler with an estimated resolution lateral resolution of $l_c=0.3 \mu$m. Both real two-point correlation function and power spectrum analyses were done. We found that the GDST applied to the surface power spectra foresees faceted morphology in contrast with the self-affine surface indicated by the local roughness exponent found via the height-height correlation function. This inconsistency is explained in terms of convolution effects resulting from the finite size of the probe tip used to scan the surfaces. High resolution AFM images corroborates the predictions of GDST.Comment: to appear in Europhysics Letter

Modelling of epitaxial film growth with a Ehrlich-Schwoebel barrier dependent on the step height

The formation of mounded surfaces in epitaxial growth is attributed to the presence of barriers against interlayer diffusion in the terrace edges, known as Ehrlich-Schwoebel (ES) barriers. We investigate a model for epitaxial growth using a ES barrier explicitly dependent on the step height. Our model has an intrinsic topological step barrier even in the absence of an explicit ES barrier. We show that mounded morphologies can be obtained even for a small barrier while a self-affine growth, consistent with the Villain-Lai-Das Sarma equation, is observed in absence of an explicit step barrier. The mounded surfaces are described by a super-roughness dynamical scaling characterized by locally smooth (faceted) surfaces and a global roughness exponent $\alpha>1$. The thin film limit is featured by surfaces with self-assembled three-dimensional structures having an aspect ratio (height/width) that may increase or decrease with temperature depending on the strength of step barrier.Comment: To appear in J. Phys. Cond. Matter; 3 movies as supplementary materia

Hormigón ligero con agregado reciclado de EVA para atenuación del ruido de impacto

The purpose of this study is to evaluate the acoustic performance of lightweight concrete with ethylene vinyl acetate copolymer (EVA) residues to reduce impact noise on floors. Three types of concrete with three different mix proportions were evaluated. The method adopted includes the characterization of water absorption, voids and density of the samples. The experimental study of noise impact followed the procedures of ISO 140. The results indicate that the lightweight concrete with EVA recycled aggregate can reduce impact noise levels by up to 15 dB and the highest percentage of coarse aggregate EVA does not entail a higher acoustic performance.La propuesta de este estudio consiste en la evaluación del desempeño acústico del hormigón ligero con residuos de ethylene vinyl acetate copolymer (EVA) para a reducción del ruido de impacto en pisos. Fueron evaluados tres tipos de hormigón con tres trazas diferentes. El método adoptado incluye la caracterización de la absorción de agua, del índice de vacíos y de la densidad en las muestras. El estudio experimental del ruido de impacto siguió las recomendaciones de ISO 140. Los resultados indican que el hormigón ligero con EVA reciclado puede reducir el nivel de ruido de impacto en hasta 15 dB y que el porcentaje más alto de agregado grueso de EVA no aumenta el desempeño acústico

Rubber Additions into Concrete and Gamma Radiation Effects on Mechanical Properties and Microwave Absorption Capacity

Rubber is the indispensable raw material for the manufacture of tires; it is obtained from plants, trees and currently can be produced synthetically. The tire rubber is mixed with compounds such as carbon black, sulfur, cement, paints, antioxidants, oils and fats, steel wire, almost etc., making impossible to recycle the tires itself. In this work, we investigate, the effects of the incorporation of ground rubber in concrete, mixture designed to establish the possibility of being used in the construction industry. The samples of concrete were addition with, 5 vol. %., 15 vol. % and 25 vol. % of rubber. Samples with different rubber addition were irradiated by a cobalt 60 gamma source to study the effect on their mechanical compression properties and microwave absorption capacity. Likewise, the microwave absorption capacity was studied for both irradiated and the non-irradiated. It was found that between 5 vol. % and 15 vol. % of rubber addition change the mechanical properties approximately 25 %, higher rubber additions result in a decrease in a 75 % of its mechanical properties. The fracture behavior is not the expected one due to as the curves of stress vs. strain show a double slope, which is associated with the concrete porosity and rubber content. The aging with the gamma rays generates loss of mechanical properties, especially at lower rubber addition, since at content greater than 15 Vol % the radiation effect is less. These rubber additions allow moderate deformations in compression, thus contributing to the care and preservation of the environment

Superpulsed low-level laser therapy protects skeletal muscle of mdx mice against damage, inflammation and morphological changes delaying dystrophy progression.

Aim: To evaluate the effects of preventive treatment with low-level laser therapy (LLLT) on progression of dystrophy in mdx mice. Methods: Ten animals were randomly divided into 2 experimental groups treated with superpulsed LLLT (904 nm, 15 mW, 700 Hz, 1 J) or placebo-LLLT at one point overlying the tibialis anterior muscle (bilaterally) 5 times per week for 14 weeks (from 6th to 20th week of age). Morphological changes, creatine kinase (CK) activity and mRNA gene expression were assessed in animals at 20th week of age. Results: Animals treated with LLLT showed very few morphological changes in skeletal muscle, with less atrophy and fibrosis than animals treated with placebo-LLLT. CK was significantly lower (p = 0.0203) in animals treated with LLLT (864.70 U.l−1, SEM 226.10) than placebo (1708.00 U.l−1, SEM 184.60). mRNA gene expression of inflammatory markers was significantly decreased by treatment with LLLT (p<0.05): TNF-α (placebo-control = 0.51 µg/µl [SEM 0.12], - LLLT = 0.048 µg/µl [SEM 0.01]), IL-1β (placebo-control = 2.292 µg/µl [SEM 0.74], - LLLT = 0.12 µg/µl [SEM 0.03]), IL-6 (placebo-control = 3.946 µg/µl [SEM 0.98], - LLLT = 0.854 µg/µl [SEM 0.33]), IL-10 (placebo-control = 1.116 µg/µl [SEM 0.22], - LLLT = 0.352 µg/µl [SEM 0.15]), and COX-2 (placebo-control = 4.984 µg/µl [SEM 1.18], LLLT = 1.470 µg/µl [SEM 0.73]). Conclusion: Irradiation of superpulsed LLLT on successive days five times per week for 14 weeks decreased morphological changes, skeletal muscle damage and inflammation in mdx mice. This indicates that LLLT has potential to decrease progression of Duchenne muscular dystrophy

Caracterização de biocarvões com FTIR visando à avaliação de seu potencial como condicionador de solo.

As Terras Pretas de Índio (TPI) são solos antropogênicos encontrados na Amazônia. Possuem alto potencial de fertilidade e alta capacidade de recuperação num ambiente onde a fertilidade dos solos normalmente é um fator limitante à produção agrícola. O componente responsável por estas qualidades das TPI é o carbono (C) orgânico que neles se encontra. A origem deste C é biomassa carbonizada que foi incorporada ao solo, durante séculos, por habitantes indígenas na era pré-colombiana. Tomando a prática secular como exemplo, a incorporação de biomassa carbonizada (biocarvão) ao solo, recentemente tem sido proposta como alternativa para sequestrar C no solo e aumentar a sua fertilidade de uma maneira sustentável

Efeito da temperatura de carbonização sobre características espectroscópicas dos carvões de duas espécies de bambu.

O objetivo desse trabalho foi caracterizar carvões vegetais de bambu nativo e exótico, com pirólise em diferentes temperaturas, com espectroscopia infravermelha a fim de descrever propriedades relevantes a sua função no solo como condicionador e investigar a possibilidade de quantificação desses materiais em solos.Apresentação oral - graduação

Characterization of grapevine (Vitis vinifera L.) cultivars from northern Portugal using RAPD and microsatellite markers

Twelve grapevine cultivars from northern Portugal were characterized with RAPD and microsatellites. Nine primers were used in the RAPD analysis; 8 of the varieties showed monotypic patterns. With the 6 microsatellite loci a total of 38 alleles was obtained. Relationships among the studied varieties were observed. Both types of molecular markers have proved useful for identification. Existence of synonymies is discussed.