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Isolamento, identificação fenogenotípica e potencial bioativo de microrganismos endofíticos intrinsecamente associados à Miconia albicans no Cerrado de São Carlos - SP
(Universidade Federal de São Carlos, 2009-09-03) Piza, Ana Candida Martins Toledo; Sousa, Cristina Paiva de; https://lattes.cnpq.br/9002619114161319; https://lattes.cnpq.br/1085967558061540
Endophytic microorganisms lives in symbiotic association with plants and in one unique biological niche, and they are potential producers of natural bioactive substances with different chemical structure and biological activity. This study aimed to isolate and characterize endophytic microorganisms from Miconia albicans from Cerrado of São Carlos - SP. Samples were characterized phenotypically from typical features of colony morphology and macroscopic measurements, physiological, biochemical and morphodyeing and genotypically by 16S rRNA analysis. We evaluated the antagonistic potential of the isolates against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Serratia marcensis IAL 1475, Enterococcus faecalis ATCC 29212, Shigella sonnei ATCC 10231 and Candida albicans ATCC 10231. Two samples (1 and 3) showed bioactivity against E. faecalis, with inhibition halos of 1.30 and 1.90 cm in diameter, respectively. A single sample (2) showed activity against S. marcensis (3.60 cm) with no significant bioactivity against the other microorganisms tested. In one sample (4) showed activity against four of the six microorganisms tested: E. faecalis (3,15 cm) , S. aureus (3,50 cm), C. albicans (3,35 cm) e S. sonnei (3,20 cm). In another sample (6) was detected bioactivity against E. faecalis and S. aureus, with inhibition zones of 1.80 and 1.50 cm, respectively. One of the samples (8) showed bioactivity against the greatest number of indicator microorganisms with inhibitory halos of 2.60 cm against E. faecalis, 1.50 cm against S. aureus, 2.40 cm against C. albicans, 2.10 cm against E. coli and 2.50 cm against S. sonnei. In two samples (5 and 7) there was no evidence the bioactive ability against indicator microorganisms tested. Phenotypic analysis of 8 endophytic microorganisms isolated allowed us to classify 50% of these (samples 4, 6, 7 and 8) in the Actinomyces group and the others were classified in the genus Streptomyces (samples 1, 2, 3 and 5). In the genotypic analysis of two isolates with bioactivity were identified as Nocardiopsis Dassonville (sample 3) and Amycolatopsis orientalis (sample 8), reporting for the first time his association with endophytic aerial parts of Miconia albicans from Cerrado of São Carlos, SP.
Eletrólitos mono e multicamadas de céria e zircônia preparados por colagem de fita
(Universidade Federal de São Carlos, 2009-09-03) Dias, Thiago; Souza, Dulcina Maria Pinatti Ferreira de; https://lattes.cnpq.br/4100119317525940; https://lattes.cnpq.br/7694579973622141
In this work it was investigated bi-layer electrolytes prepared by the tape casting technique. These electrolytes were composed of one layer of 10 mol% gadolinia doped ceria (CDG) and another one of 8 mol% yttria-stabilized zirconia (ZEI -8). CDG tapes were prepared with powder from Fuel Cell Materials (FCM) and powder obtained by oxide mixing. ZEI-8 tapes were prepared with powder from Tosoh Corporation. In the first step, CDG and ZEI-8 tapes were prepared and dense plates were obtained after sintering. Sintered plates were characterized by impedance spectroscopy and scanning electron microscopy (SEM). At 350°C, the highest electrical conductivity of CDG samples prepared with powder obtained by oxide mixing and sintered at 1600 °C was 3.37 x10-4 S.cm-1 and with FCM powder sintered at 1500 °C was 4.33 x10-4 S.cm-1. At the same temperature, ZEI-8 samples sintered at 1600 °C showed 9.6 x10-5 S.cm-1, which agrees with literature results. CDG/ZEI-8 bilayers plates were prepared either by lamination or by double tape casting, followed by sintering at 1600 °C/2 h. Sintered bi-layers prepared by double tape casting were characterized by impedance spectroscopy. Electrical conductivity at 350 °C was 8.82 x10-5 S.cm-1, three times lower than CDG mono layer (3.37 x10-4 S.cm-1) due to high resistivity of CGD/ZEI-8 interface. The bi-layers SEM analysis showed that layers thickness of CDG and ZEI-8, were 140 μm and 24 μm respectively. The adherence between CDG and ZEI-8 layers was attributed to secondary phase in the interface which was responsible for high resistivity of the CGD/ZEI-8 interface.
Estudo de nanopartículas para preparação de compósitos com acoplamento magnetoelétrico
(Universidade Federal de São Carlos, 2009-09-03) Clabel Huamán, José Luis; Cardoso, Claudio Antonio; https://lattes.cnpq.br/0332061570052918; https://lattes.cnpq.br/9597258423214892
In recent years the necessity of new devices, in the electroelectronic industry, has lead to an increasing interest in materials called magnetoelectric (ME) or multiferroic (MF). Multiferroic is the term used to classify the materials that exhibit magnetic and electric orders simultaneously. In this sense, the idea of producing materials and smart devices have attracted the attention of many researchers from different fields of knowledge. From the technological point of view, the simultaneous mutual control of electrical and magnetic properties generates new possibilities of applications. However the number of candidate for these applications materials is limited and the effects are typically very small and in some cases observed in the low temperature. Therefore, the search for room temperature multiferroic materials is very import for technological application of these materials as well as from the academic stand point. This work aimed the preparation of new multiferroic materials suitable for technological application. We performed a systematic study on the preparation of composites. Both compounds were synthesized using Pechini method, further, they were characterized by dilatometry, densification, X-ray diffraction, electronic microscopy, magnetization and resistivity measurements. We found the best results for the manganite prepared from solution with pH=0 and then calcinated at 900 for 6 hours. After that, the powder were sinterized at 1000 for 2 hours. For bfor 2 hours.
Estudo das interações fitoplâncton-protozooplâncton no reservatório de Barra Bonita, SP, com ênfase na toxicidade de microcistinas
(Universidade Federal de São Carlos, 2009-09-03) Araujo, Laryssa Melo Rosa; Seleghim, Mirna Helena Regali; https://lattes.cnpq.br/5998337634888263; https://lattes.cnpq.br/0049999109915867
The increasing eutrophication of aquatic environments, resulting from the human activities, is related to cyanobacterial blooms that are described, all over the world, as the agents causing toxicity and death in humans, domestic and wild animals. Recently, studies are being conducted aiming to prove the possibility of the biotransference of the cyanobacterial toxins to the trophic web and their associated effects. Protozoans are very important organisms to the aquatic food web and can be useful as indicators in water quality assessment. The present study evaluated, during cyanobacteria bloom events in Barra Bonita reservoir (SP), the intra and extracellular cyanotoxin levels (microcystin LR) and also phyto and protozooplanktonic populations. Besides, it was also evaluated, in laboratory experiments, the effects of the cyanotoxins obtained from cultures of Microcystis and from material collected in Barra Bonita reservoir on the protozoan Paramecium caudatum. Due to the eutrophication degree of the studied reservoir, the cianobacteria, specially Microcystis (M. aeruginosa, M. protocystis and M. panniformes) and Pseudanabaena mucicola, were the dominant phytoplanktonic organisms. In this work it was registered only the concentrations of microcystin LR. The concentrations of this toxin were median among those found for other Brazilian aquatic environments where it was detected more than one cyanotoxin variant. Halteria grandinella and Vorticela aquadulcis were the dominant protozoans in the environment during the cyanobanterial bloom events. The protozooplanktonic densities and species composition were lower than those found in the literature for environments with the same trophic status, indicating that the protozoan seem to be negatively affected by the cyanobacterial blooms and cyanotoxins (microcystins) detected in the samples. Samples from Microcystis cultures and from the reservoir demonstrated to be toxic to P. caudatum, although they were more tolerant to the semi purified extracts from cultures than to the environmental samples.