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Processamento, caracterização e determinação do perfil de polarização do Poli(fluoreto de vinilideno)
(Universidade Federal de São Carlos, 2009-03-25) Silva, Aline Bruna da; Gregório Filho, Rinaldo; https://lattes.cnpq.br/5968244801228229; https://lattes.cnpq.br/6539169612758835
This work characterized the ferroelectric polarization of the β-PVDF differentiating the individual contributions of the orientation and the crystalline phases in the remanent polarization of the PVDF. Those contributions are not known separately, because until recently the loop hysteresi was obtained only to β- PVDF from stretching the α phase films. Unoriented films exclusively in the β phase were obtained from the crystallization of PVDF from solution with N,N-dimethyl formamide at temperatures below 70ºC, some of these films were uniaxialy stretched. Also were obtained films from the uniaxial stretching of the PVDF-α from Bemberg- Folien GmbH at 80ºC and 150ºC and still unoriented samples from Bemberg in α phase, (α+β) samples from Piezotech and β sample were obtained by electrospinning. The crystalline phase, orientation and dielectric properties of the samples were determined by differential scanning calorimetry (DSC), X-Ray diffraction, Fourier transformed infrared spectroscopy (FTIR) and dielectric spectroscopy. The ferroelectric characterization was done by ramp voltage technique, in this method the electric field is applied in the form of ramps, i.e, with the relationship dE/dt equal to a constant (k). The numbers of the voltage ramps, of same polarity or reverse, is controlled, making possible the application of an arbitrary sequence of ramps, therefore the dependence of the polarization with the field can be determined in order and obtain the hysteresis loop. Through the relation between structural and ferroelectric characteristics of the samples proved that origin of permanent polarization is in the crystalline phase. The role of the interface among amorphous and crystalline phase in the metaestable polarization of the PVDF was also studied.
Estudo da fauna de Hymenoptera parasitóides associados a hortas orgânicas e da utilização de extratos vegetais no controle de Plutella xylostella (Lepidoptera, Plutellidae)
(Universidade Federal de São Carlos, 2009-03-25) Onody, Helena Carolina; Dias, Angélica Maria Penteado Martins; https://lattes.cnpq.br/8637344058859147; https://lattes.cnpq.br/4570932641664551
This work aimed to study the Hymenoptera parasitoids fauna in organic crops areas and the insecticidal activity of plant extracts from Allamanda cathartica (Apocynaceae) and Coriandrum sativum (Apiaceae) and the latex of Euphorbia milii (Euphorbiaceae) on Plutella xylostella (Lepidoptera, Plutellidae). During March 2006 to February 2007 twelve samples were performed using Malaise traps in each of the three studied organic crop areas. Immature Lepidoptera were also collected to verify the emergence of parasitoids. A total of 46,231 specimens, identified in 28 families were collected by Malaise trap. The most representative were Braconidae and Ichneumonidae (Ichneumonoidea), Eulophidae, Mymaridae and Pteromalidae (Chalcidoidea), Scelionidae (Platygastroidea) and Figitidae (Cynipoidea). Twenty-two subfamilies of Braconidae were identified, Microgastrinae being the most abundant in the three locations sampled. Seventeen subfamilies of Ichneumonidae were recognized and, in the three farms, the Campopleginae and Cremastinae were the most abundant. The genera Lysiphlebus, Opius, Dolichozele and Aleiodes were the most abundant of the 81 Braconidae genus identified. The results showed that the practice organic farming has positive effects on the abundance, richness and diversity Hymenoptera parasitoids fauna, but the results varied according to taxonomic level used and the type of management performed. The Braconidae and Ichneumonidae (Ichneumonoidea), Eulophidae and Encyrtidae (Chalcidoidea) were the most important parasitoids reared from the immature Lepidoptera hosts. New information on the associations between hosts and parasitoids were obtained for Hypomicrogaster (Braconidae, Microgastrinae) parasitizing larvae of Hellula phidilealis (Lepidoptera, Pyralidae), Eiphosoma (Cremastinae, Ichneumonidae) parasitizing larvae of Diaphania hyalinata (Pyralidae, Lepidoptera) and Colpotrochia (Ichneumonidae, Metopiinae) parasitizing larvae of Spodoptera eridania (Lepidoptera, Noctuidae). The tests performed with different concentrations of Allamanda cathartica and Coriandrum sativum extracts and Euphorbia milii latex affected the larval Plutella xylostella mortality.