Investigação de contatos elétricos e propriedades de filmes finos de SnO2 dopados com os íons terras raras Eu3+ e Ce3+

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Degradação de membrana impermeabilizante de polietileno de alta densidade usada em tanques de armazenamento de vinhaça

High-density polyethylene (HDPE) water-proof membranes are used as coatings in vinasse (leachate from sugar cane) storage tanks. The leachate is pumped into the tanks at temperatures of 80-90 °C. Due to these high temperatures and acidity of the waste, these membranes can be degraded, cracked and then loose the function for which they have been designed. This may cause contamination of the soil and groundwater. This study evaluated the effect of vinasse in HDPE membranes after 4 months of exposure in a controlled environment. An aggressive, alkaline pH liquid (sodium hydroxide) was also used. The objective was to evaluate the membrane resistance in contact with acidic and alkaline residues. Physical and mechanical tests, measurement of the carbon black content and thermo gravimetric analysis (TGA) were used to determine degradation of polymer membranes after chemical immersion. While sodium hydroxide resulted caused only minor changes in the physical properties, vinasse induced a thickness change of 7.8%. With immersion in vinasse, an average decrease in strength and deformability (yield) of 34% and 23.5% were measured, respectively. The stiffness increased by 7.8% (average) and the tear strength decreased by 2.7% (average).

Diodo planar orgânico Schottky: construção e caracterização

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Metabolism of L929 cells after contact with acrylic resins. Part 1: Acrylic denture base resins

The purpose of this study was to evaluate the effectiveness of complementary heat treatment and water storage in reducing cytotoxicity of acrylic resins denture bases used in Brazil by the MTT assay. Material and Methods: First, nine specimens were fabricated from metal matrix in the form of discs with 14 mm in diameter and 1.2 mm of thick. Immediately after making, 24 or 48 hours after storage in distilled water, the samples of heat-polymerized resins were divided into 3 groups (n = 3) according to the type of thermal treatment: Group 1: samples were individually exposed to microwave energy (500 W for 3 minutes); Group 2: samples were immersed in water at 550 C for 60 minutes; Group 3: samples did not receive heat treatment. To prepare the extracts, 3 samples of each group were placed into vials containing 3 mL of culture medium and stored at 37°C for 24 hours. L929 cells were used and the MTT assay was performed to analyze the cellular metabolism. Two-factor analysis of variance was used to detect significant among groups at 5% significance. Results: After statistical analysis, the materials were classified according to the cytotoxic effect: non-cytotoxic, slightly cytotoxic; moderately cytotoxic; and strongly cytotoxic. The results showed that the resins ranged from moderately cytotoxic to non-cytotoxic, but no statistically significant difference among experimental groups. Furthermore, the water storage and thermal treatments reduced the cytotoxicity of the resins. Conclusions: It was concluded that the resins studied are potentially toxic and that treatments can decrease their cytotoxicity.

Comparative study of resistance to heat in two species of leaf-cutting ants

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Morphological, thermal and physicochemical characteristics of small granules starch from Mirabilis jalapa L

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effects of humidity on the electrical properties of thermal inkjet-printed films of copper tetrasulfonated phthalocyanine (CuTsPc) onto paper substrates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lack of acquired resistance in dogs to successive infestations of Rhipicephalus sanguineus ticks from Brazil and Argentina

Comparative studies between brown dog tick Rhipicephalus sanguineus populations from Brazil (Jaboticabal, São Paulo) and Argentina (Rafaela, Santa Fé) showed significant biological, morphological and genetic differences between them. This work aimed to study, in a comparative way, the acquisition of resistance in domestic dogs to R. sanguineus from Jaboticabal and Rafaela, after successive and controlled infestations. Ticks were kept in a BOD incubator under controlled conditions (27 °C, 80 % relative humidity, 12-h photoperiod). Ten dogs, Dachshund breed, males and females, 6 months old, short- or long-haired, without prior contact with ticks, were used as hosts. They were distributed into two experimental groups composed of five animals each: G1 infested with ten adult couples of R. sanguineus (Jaboticabal) per animal, and G2 infested with ten adult couples of R. sanguineus (Rafaela) per animal. Ticks' biological parameters and titration of antibodies from the dogs' sera by ELISA test were used for comparison between the strains. Results of the biological parameters showed that the dogs did not acquire immunity to either of the R. sanguineus strains after repeated infestations. The ELISA test showed low antibody titers in sera of dogs from G2, in successive infestations, and higher antibody responses post second and third infestations in G1. It also demonstrated cross-reactivity between sera of dogs infested with R. sanguineus (Jaboticabal) and antigens from R. sanguineus (Rafaela) and vice versa. We conclude that Dachshund dogs did not develop resistance against neither Jaboticabal nor Rafaela strains of R. sanguineus.

Enhancement of Corrosion Resistance AISI 304 Steel by Plasma Polymerized Thin Films

The purpose of this work is the deposition of films in order to increase the corrosion resistance of AISI 304 steel, which is a material used to construct the reactors for bioethanol production. This deposition inhibits the permeation of corrosive species to the film-metal interface. Thin films were prepared by radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD) method using plasmas of hexamethyldisiloxane/argon/oxygen mixtures excited by signals of different powers. The plasma was generated by the application of RF power of 13.56 MHz to the sample holder while keeping grounded the topmost electrode and the chamber walls. The effect of the RF power on the properties of the samples was investigated by perfilometry, X-ray photoelectron spectroscopy (XPS), contact angle, and electrochemical impedance spectroscopy (EIS). The results of the corrosion resistance tests of the AISI 304 steel were interpreted in terms of the energy delivered to the growing layer by plasma excitation power.