Nonlinear ac susceptibility studies of high-TcT_c rings: Influence of the structuring method and determination of the flux creep exponent

We have studied the influence of the patterning procedure on the critical current density of high-$T_c$ YBa$_2$Cu$_3$O$_{7-\delta}$ thin rings using the nonlinear ac susceptibility method. At no applied dc magnetic field we have found that laser ablation degrades strongly the critical current density whereas ion beam etching has only a weak influence on it. From the measurements at different frequencies and dc magnetic fields we analyzed the influence of flux creep and obtained the field dependence of the flux creep exponent. Our data reconfirm the recently observed scaling relation for the nonlinear susceptibility response of type-II superconductors.Comment: 10 pages, 12 figure

A new species of Armascirus and description of the male of Scutopalus tomentosus from Brazil (Acari: Cunaxidae).

In this work, we describe the male of Scutopalus tomentosus Rocha, Skvarla & Ferla, 2013 and a new speciesArmascirus amazoniensis Wurlitzer & Silvasp. nov. from specimens collected on coconut crop, Cocos nuciferaL. (Arecaceae), cultivated in state of Pará, into the Amazonic biome, Brazil

Higher harmonics of ac voltage response in narrow strips of YBa2Cu3O7 thin films: Evidence for strong thermal fluctuations

We report on measurements of higher harmonics of the ac voltage response in strips of YBa2Cu3O7 thin films as a function of temperature, frequency and ac current amplitude. The third (fifth) harmonic of the local voltage is found to exhibit a negative (positive) peak at the superconducting transition temperature and their amplitudes are closely related to the slope (derivative) of the first (Ohmic) harmonic. The peaks practically do not depend on frequency and no even (second or fourth) harmonics are detected. The observed data can be interpreted in terms of ac current induced thermal modulation of the sample temperature added to strong thermally activated fluctuations in the transition region.Comment: 9 pages, 4 figures (PDF file

Effective Area-Elasticity and Tension of Micro-manipulated Membranes

We evaluate the effective Hamiltonian governing, at the optically resolved scale, the elastic properties of micro-manipulated membranes. We identify floppy, entropic-tense and stretched-tense regimes, representing different behaviors of the effective area-elasticity of the membrane. The corresponding effective tension depends on the microscopic parameters (total area, bending rigidity) and on the optically visible area, which is controlled by the imposed external constraints. We successfully compare our predictions with recent data on micropipette experiments.Comment: To be published in Phys. Rev. Let

Stability and microstructure of powdered pulp of the Palmer mango obtained by the process of lyophilisation.

ABSTRACT The aim of this work was to study the stability of powdered mango pulp obtained through the process of lyophilisation, as well as its structural characteristics using electron microscopy analysis. In response to an earlier experimental design using maltodextrin concentrations of 0%, 10%, 20% and 30% and periods of 24 and 30 hours, the condition of 20% maltodextrin and 24 hours drying was chosen as the best for drying mango in a freeze dryer. The stability study was therefore carried out using powdered mango pulp obtained under the above best-drying conditions, stored for 90 days and monitored every two weeks by analysis of the moisture, ascorbic acid content, b* colorimetric parameter and hygroscopicity. Storage was at room temperature (27 °C) in vacuum and non-vacuum laminated packaging, and in non-vacuum plastic packaging. The vacuum laminated packaging maintained the initial characteristics of the stored product for longer, especially the ascorbic acid content, hygroscopicity and b* colour parameter. The microstructure of the sample was then studied under different concentrations of maltodextrin (0%, 10%, 20% and 30%) so as to understand the effect of the drying agent on the final product. Close-up images of the powder revealed the porous surface formation and the effect of the agent on particle size, where higher concentrations of maltodextrin resulted in more porous powders with smaller particles.</div

Bebida vegetal de amêndoa de castanha-de-caju desenvolvida pela Embrapa comparada a produto comercial.

A Embrapa desenvolveu o processo de uma bebida à base de amêndoa de castanha-de-caju, em que a amêndoa é triturada com água, na proporção de 1:10 (m/m), e açúcar (3%), seguindo-se tratamento térmico a 140 °C por quatro segundos. O objetivo deste trabalho foi comparar a bebida vegetal de amêndoa de castanha-de-caju quebrada, obtida por processo da Embrapa, com produto comercial. Observou-se que a bebida desenvolvida na Embrapa apresentou maiores teores de sólidos, cinzas, carboidratos, valor energético e índice de branco. Os atributos sensoriais mostraram maior intensidade de gosto doce, corpo e sabor de amêndoa na bebida da Embrapa e poucas diferenças em relação à homogeneidade, presença de partículas na boca e cor branca. Essas diferenças fizeram com que a bebida da Embrapa apresentasse médias superiores à bebida comercial para a aceitação de aparência, textura, sabor e impressão global. No entanto, não se observou diferença de aceitação para cor e aroma.bitstream/item/224669/1/BP-219.pd

Evaluation of thermal and non-thermal processing effect on non-prebiotic and prebiotic acerola juices using 1HqNMR and GC - MS coupled to chemometrics.

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The origin of paramagnetic magnetization in field-cooled YBa2Cu3O7 films

Temperature dependences of the magnetic moment have been measured in YBa_2Cu_3O_{7-\delta} thin films over a wide magnetic field range (5 <= H <= 10^4 Oe). In these films a paramagnetic signal known as the paramagnetic Meissner effect has been observed. The experimental data in the films, which have strong pinning and high critical current densities (J_c ~ 2 \times 10^6 A/cm^2 at 77 K), are quantitatively shown to be highly consistent with the theoretical model proposed by Koshelev and Larkin [Phys. Rev. B 52, 13559 (1995)]. This finding indicates that the origin of the paramagnetic effect is ultimately associated with nucleation and inhomogeneous spatial redistribution of magnetic vortices in a sample which is cooled down in a magnetic field. It is also shown that the distribution of vortices is extremely sensitive to the interplay of film properties and the real experimental conditions of the measurements.Comment: RevTex, 8 figure