Behavior of sorghum lines in relation to sugarcane borer Diatraea sacchardis (Fabricius, 1974).

Sorghum lines were evaluated for resistance to the sugarcane borer (Diatraea saccharalist) at the Afranio Research Field, Pernambuco in 1976. The infestations of the lines are given in Table 1. There was significant simple positive correlation between infestation percentage and infestation intensity (r= 0.86*). There was no correlation between infestation percentage and infestation intensity with plant height or with number and external diameter of internodes.E em Annual Plant Resistance Insects Newsletter, v.4, p.38-39, 1978

Model for chaotic dynamics of the perpendicular-pumping spin-wave instability

We propose a model for the dynamics of spin-wave instabilities driven by a rf field perpendicular to the dc magnetic field in the second- order Suhl process. We show that a self-oscillation arises from the dynamic nonlinear interaction between the k=0 mode driven by the pumping field and a degenerate k≠0 magnon, with frequency that depends on the dissipation rates and the nonlinear interaction parameters and not on the sample dimensions. For certain parameter values, as the driving field increases we find a period-doubling route to chaos and odd-period bifurcation windows consistent with recent experiments in yttrium iron garnet

Modeling electrodialysis and a photochemical process for their integration in saline wastewater treatment.

Oxidation processes can be used to treat industrial wastewater containing non-biodegradable organic compounds. However, the presence of dissolved salts may inhibit or retard the treatment process. In this study, wastewater desalination by electrodialysis (ED) associated with an advanced oxidation process (photo-Fenton) was applied to an aqueous NaCl solution containing phenol. The influence of process variables on the demineralization factor was investigated for ED in pilot scale and a correlation was obtained between the phenol, salt and water fluxes with the driving force. The oxidation process was investigated in a laboratory batch reactor and a model based on artificial neural networks was developed by fitting the experimental data describing the reaction rate as a function of the input variables. With the experimental parameters of both processes, a dynamic model was developed for ED and a continuous model, using a plug flow reactor approach, for the oxidation process. Finally, the hybrid model simulation could validate different scenarios of the integrated system and can be used for process optimization

Pasteurização do leite-do-amapá in natura para controle do escurecimento enzimático.

O extrato do amapazeiro (Brosimum parinarioides Ducke), conhecido como leite-do-amapá, é utilizado pelas populações amazônicas como fonte alimentar e medicinal. A rápida alteração de cor do látex após extração representa a presença de enzimas como polifenoloxidase (PPO) e peroxidase (POD), escurecendo o produto in natura e desqualificando-o para comercialização. Desse modo, este trabalho objetivou a avaliação da atividade das enzimas PPO e POD em três amostras de leite-do-amapá resfriadas a 8°C, coletadas em amapazeiros em Moju (PA), e onze amostras de leite-do-amapá após o processo de pasteurização em diversos binômios tempo/temperatura e posteriormente resfriadas a 8°C, visando à otimização da conservação do produto in natura. Após resfriamento a 8°C, as amostras de leite-do-amapá in natura apresentaram diferença significativa entre os valores de atividade da enzima POD e, posteriormente observou-se elevação dessa atividade durante os períodos de tempo analisados. Como também se observou atividade da enzima PPO nas mesmas amostras, constata-se que esse tipo de conservação não foi efi ciente para as enzimas POD e PPO para leite-do-amapá. As amostras pasteurizadas de leitedo-amapá, e posteriormente resfriadas, apresentaram atividades das enzimas POD e PPO significativamente diferenciadas da respectiva amostra controle (sem pasteurização), concluindo que a pasteurização nos binômios estudados, aliada ao resfriamento, foi eficaz na diminuição da atividade das enzimas peroxidase e polifenoloxidase, alcançando-se a inativação destas, podendo ser um processo potencial para conservação desse produto

Manejo de irrigação em fruteiras tropicais.

As incertezas quanto a contribuição das chuvas para garantir umidade adequada no solo, tem levado a grande maioria dos fruticultores a adotarem a irrigação como tecnologia indispensável ao sistema produtivo das fruteiras. O efeito potencial da irrigação em fruteiras contribui para os dois pontos mais importantes de uma economia globalizada: o aumento da produtividade e a melhoria da qualidade da fruta. O presente trabalho procura transmitir conhecimentos básicos do sistema solo-planta-atmosfera, descrevendo os diversos métodos de obtenção dos parâmetros do solo, da planta e do clima necessários aos cálculos de manejo de irrigação. Métodos e sistemas de irrigação, necessidades hídricas e recomendações de manejo de irrigação são abordadas para fruteiras tropicais como: abacate, abacaxi, banana, citros, goiaba, mamão, manga e maracujá.bitstream/item/81294/1/Manejo-de-Irrigacao-Eugenio-Coelho-Circular-Tecnica-40-2000.pd

Concrete retrofitting using CFRP and geopolymer mortars

A new development in the repair and strengthening of reinforced concrete systems is the use of carbon fiber reinforced polymers (CFRP) strips bonded to concrete substrate with epoxy resins. It has been reported that epoxy adhesive are extremely sensitive to high temperatures. Some authors conclude that the epoxy temperature should not exceed 70 ºC in order to safeguard the adhesiveness of the epoxy and, thus, the integrity and adequate functioning of CFRP. It is noted that even frequently exposure to direct sunlight causes temperatures higher than 70 ºC. Since geopolymers are known to possess high stability at high temperature, these materials can be an alternative to epoxy resins. This papers presents results about the use of metakaolin based geopolymers mortars to insure the adhesion between the CFRP and the concrete substrate. Several compositions of geopolymer mortars were executed by varying the percentage of binder, sand/binder ratio and the concentration of sodium hydroxide. It was found that geopolymer mortars demonstrate very promising performances, having obtained a high mechanical resistance and a good adhesion to concrete. On the other hand the adhesion between CFRP and geopolymer mortars proved to be smaller than expected which could be due, to the fact that the composition of the mortar was not optimized or even to the nature of the CFRP

Concrete retrofitting using metakaolin geopolymer mortars and CFRP

This paper presents results about the use of metakaolin based geopolymers mortars for retrofitting purposes. Two main situations are addressed, the use of geopolymeric mortars as a repairing layer or as a binding agent to insure the adhesion between CFRP sheets and the concrete substrate. Several compositions of metakaolin geopolymer mortars were executed by varying the percentage of sand/binder mass ratio and the concentration of sodium hydroxide. It was found that metakaolin geopolymer mortars show a high mechanical resistance and a relevant adhesion to the concrete substrate. Although their adhesion strength is lower than the one present by commercial pre-pack repair mortars, they are very cost-effective (5 to 10 times less expensive). On the other hand, the adhesion strength between CFRP and geopolymer mortars proved to be lower than expected which could be due to the fact that the composition of the geopolymeric mortars was not optimized and also to the fact that the CFRP used was not prone to this kind of application