Synthesis, characterization and antifungal activity of quaternary derivatives of chitosan on Aspergillus flavus

Two series of new chitosan derivatives were synthesized by reaction of deacetylated chitosan (CH) with propyl (CH-Propyl) and pentyl (CH-Pentyl) trimethylammonium bromides to obtain derivatives with increasing degrees of substitution (DS). The derivatives were characterized by 1H NMR and potentiometric titration techniques and their antifungal activities on the mycelial growth of Aspergillus flavus were investigated in vitro. The antifungal activities increase with DS and the more substituted derivatives of both series, CH-Propyl and CH-Pentyl, exhibited antifungal activities respectively three and six times higher than those obtained with commercial and deacetylated chitosan. The minimum inhibitory concentrations (MIC) were evaluated at 24, 48 and 72h by varying the polymer concentration from 0.5 to 16g/L and the results showed that the quaternary derivatives inhibited the fungus growth at polymer concentrations four times lower than that obtained with deacetylated chitosan (CH). The chitosans modified with pentyltrimethylammonium bromide exhibited higher activity and results are discussed taking into account the degree of substitution (DS). © 2012 Elsevier GmbH.

Side-effects of thiamethoxam on the brain andmidgut of the africanized honeybee Apis mellifera (Hymenopptera: Apidae)

The development of agricultural activities coincides with the increased use of pesticides to control pests, which can also be harmful to nontarget insects such as bees. Thus, the goal of this work was assess the toxic effects of thiamethoxam on newly emerged worker bees of Apis mellifera (africanized honeybee-AHB). Initially, we determined that the lethal concentration 50 (LC50) of thiamethoxam was 4.28 ng a.i./μL of diet. To determine the lethal time 50 (LT50), a survival assay was conducted using diets containing sublethal doses of thiamethoxam equal to 1/10 and 1/100 of the LC50. The group of bees exposed to 1/10 of the LC50 had a 41.2% reduction of lifespan. When AHB samples were analyzed by morphological technique we found the presence of condensed cells in the mushroom bodies and optical lobes in exposed honeybees. Through Xylidine Ponceau technique, we found cells which stained more intensely in groups exposed to thiamethoxam. The digestive and regenerative cells of the midgut from exposed bees also showed morphological and histochemical alterations, like cytoplasm vacuolization, increased apocrine secretion and increased cell elimination. Thus, intoxication with a sublethal doses of thiamethoxam can cause impairment in the brain and midgut of AHB and contribute to the honeybee lifespan reduction. © 2013 Wiley Periodicals, Inc.

Abordagens de descoberta de conhecimento em bases de dados aplicadas ao Cadastro Territorial Multifinalitário

Pós-graduação em Ciências Cartográficas - FCT

Population, social equity and changing production patterns

Includes bibliography

Indução ao esforço e seus efeitos em parâmetros da percepção espacial de indivíduos atletas deficientes visuais e não deficientes

Pós-graduação em Ciências da Motricidade - IBRC

Ações de educação ambiental e monitoramento da água no córrego da Olaria, APTA-Pindorama, S.P

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Análise e implementação da nova proposta pedagógica estadual para o ensino de língua inglesa no ensino fundamental

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise energética e econômica da produção de milho (Zea mays spp) em sistema de plantio direto em propriedades familiares no município de Pratânia-SP

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise dos dispêndios energéticos e econômicos da implantação de eucalipto

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

A arte e o letramento em educação de jovens e adultos

Pós-graduação em Artes - IA

A maior flor do mundo de José Saramago e a educação ambiental na escola

Pós-graduação em Educação para a Ciência - FC

Narrativas sobre a prática de ensino de matemática de professores dos anos iniciais do ensino fundamental

Pós-graduação em Educação Matemática - IGCE

O desenvolvimento da matemacia no trabalho com projetos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Energy efficiency in Latin America and the Caribbean: Progress and challenges of the past five years. Executive summary

The present document analyses the progress of national programmes and activities associated with the promotion and development of energy efficiency between the years 2008 and 2013 in the 27 Latin American and the Caribbean member countries of the Latin American Energy Organization (OLADE). The new study is based on the original report —prepared by ECLAC and OLADE between July 2008 and July 20091— taking into consideration any progress made over the past four to five years, an interval long enough to justify an update both of the current status of energy efficiency and its prospects, developments and challenges in the Region of Latin America and the Caribbean.

Análise da paisagem para o planejamento e a gestão da conservação da Mata Atlântica

Landscape is dynamic, having complex nature, with tangible and intangible dimensions, presenting a continuous evolution process. The aim of this research were based on the identification and classification of landscapes in units and subunits, from the ownership by individuals; the development of a methodology to assist in the planning and management, conciliating conservation of natural areas with anthropic activities; and, from the information gathered, evaluate the different social groups aiming to design a landscape from the sustainable development perspective; thus better understanding both cultural and forest fragmentation processes, in the city of Ouro Preto, Minas Gerais. The research analyzed the current landscape and its historical evolution, distinguishing between material and immaterial dimensions. Information was raised from field trips, soil types, relief, slope, drainage, conservation units, administrative zoning, urban areas, natural resources, economy, tax raising, transport and building infrastructure, satellite images, types of management applied to the preservation or conservation of forests and fields, and semi-structured interviews with the various actors that modify and transform the territory, thus making a balance between the built landscape and the demands of the society and ecosystems. Results were composed by a map of land use in 2011; a map of landscape units and their subunits, with their appropriate definitions; a map with five levels of activities intensity, with their respective descriptions; and raising barriers to improving the welfare of the actors and the integrity of ecosystems. The number of generated ecosystem services are difficult to measure, but its benefits are useful for everyone. The physical changes are a reflection of the economy, which caused environmental impacts, mainly related to mining activities, tourism, agriculture and conservation of natural areas, all requiring ideally a shared management. In this sense, the landscape needs a management to create sustainable alternatives to anthropic activities. The dynamics of the landscape has been shaped by a slow evolution, set by mining activities due to the high financial revenues, there were areas of revegetation after clearcuts in the past, and now tourism lacks structure. The city has great potential for development projects with payments for environmental services, however, gaps for shared management exists.