Nanometric pitch in modulated structures of twist-bend nematic liquid crystals

The extended Frank elastic energy density is used to investigate the existence of a stable periodically modulate structure that appears as a ground state exhibiting a twist-bend molecular arrangement. For an unbounded sample, we show that the twist-bend nematic phase $N_{TB}$ is characterized by a heliconical structure with a pitch in the nano-metric range, in agreement with experimental results. For a sample of finite thickness, we show that the wave vector of the stable periodic structure depends not only on the elastic parameters but also on the anchoring energy, easy axis direction, and the thickness of the sample.Comment: 11 page

Abundância de fungos micorrízicos arbusculares e biomassa total fúngica e bacteriana de solos cultivados com cana de açúcar.

A cana de açúcar movimenta no Brasil cerca de R$40 bilhões por ano com a produção e comercialização de açúcar e etanol. Os micro-organismos do solo têm são fundamentais no ciclo dos nutrientes, destacando os Fungos Micorrízicos Arbusculares (FMAs) no fornecimento de fósforo para as plantas. Os objetivos desse trabalho foram determinar os parâmetros quantitativos da microbiota do solo através da avaliação da abundância de esporos dos FMAs e biomassa total de fungos e bactérias utilizando a técnica de microscopia de Epifluorescência, em mata ciliar e em canaviais com diferentes manejos do solo. Foram selecionadas seis áreas no Estado de São Paulo e as amostras de solo foram coletadas nos períodos de outubro/novembro de 2010. A abundância de esporos dos FMAs junto ao manejo de cana de açúcar não apresentaram diferenças significativas. Houve aumento significativo do pH do solo nos solos manejados em relação com a mata ciliar. O baixo pH do solo não interferiu na comunidade dos FMAs e também não afetou na biomassa de fungos e bactérias. Foram observadas diferenças significativas no aumento para biomassa de bactérias e fungo+bactérias do solo no manejo com cana queimada, com aplicação de vinhaça e colheita mecanizada em relação à cana crua, sem vinhaça e colheita manual. Este é o primeiro estudo que se tem conhecimento realizado no Brasil utilizando a técnica de microscopia de epifluorescência para estimar a biomassa total de carbono de fungos e bactérias e os resultados apresentados aqui estão de coerentes com outros estudos da literatura. Desse modo a técnica é promissora e poderá ser utilizada em futuros estudos no Brasil.Fertbio

Ruminal in vitro fermentation kinetics and chemical composition of Sorghum cv. Nutritop at different stage of regrowth.

The objective was to estimate the ruminal degradation kinetics and chemical composition of Sorghum cv. Nutritop at different stages of regrowth, as fed for background lambs

The plasticity of non-crystalline solids: aluminum phosphate white pigments

A new white pigment made out of nano-structured non-crystalline aluminum phosphate was recently launched as an industrial product. Pigment opacifying properties are not intrinsic to aluminum phosphate but they arise as the result of a rare hollow particle nano-structure. This is in turn derived from the core-and-shell structure of amorphous aluminum phosphate precipitated under well-defined conditions. The new pigment is a product of the often neglected chemistry of non-crystalline ionic solids that can probably be a rich source of new successful products. The text describes a short account of the R&D activities, from the initial ideas to the present.745748Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Dry matter intake from beef cattle grazing natural grassland with different intensification levels.

Estimating dry matter intake from grazing animals remains a challenge. Among the indicators currently used, n-alkanes have been shown to be a good alternative, especially in heterogeneous environments such as natural grasslands

Emissões de metano por novilhos de corte em pastagem natural.

A pastagem natural é a principal fonte de alimento de bovinos de corte no Rio Grande do Sul, entretanto poucos são os dados sobre emissões de metano de novilhos de corte neste ambiente. O objetivo foi avaliar a emissão de metano por bovinos de corte em pastagem natural.Editora técnica Claudia Cristina Gulias Gomes

Propolis potential activity against Candida tropicalis adhered cells and its biofilms

Objectives: Invasive fungal infections, such as candidiasis, represent a public health problem of major importance, and Candida tropicalis has been highlighted among the main agents of candidiasis. One of the major contributions to C. tropicalis virulence is its versatility in adapting to a variety of different habitats and the formation of surface attached microbial communities known as biofilms. Moreover, from the clinical perspective, the most important feature of Candida biofilms is its role in increasing tolerance to conventional antifungal therapy. This scenario encourages the search for alternative therapies. Natural matrixes, such as propolis, compromise a multitude of bioactive properties, in particular phenolic extracts have evidenced significant antimicrobial properties against a multiple of opportunist invaders, including Candida species. Thus, the main objective of the present work was to evaluate the potential antifungal effect of propolis against Candida tropicalis biofilms. Methods: This study was conducted with four strains of C. tropicalis and one reference strain, from the American Type Culture Collection (ATCC 40042). Biofilm formation were carried out on 96-well microplates containing a cellular suspension of 1x105 cells/mL and incubated for 24 h at 37°C. Pre-formed C. tropicalis biofilms were treated with propolis (ranging from 0.47 to 1.42 mg/ml), during 24 h at 37°C and its effect assessed through quantification of the number of colony forming unit (CFU). Results: It was evident that all C. tropicalis strains tested were able to form biofilm and that propolis was able to reduce around 40% and 50% of the pre-formed biofilm. Moreover, in general the propolis effect was similar among all the C. tropicalis clinical isolates strains Conclusions: These data are promising, since they open important perspectives regarding new antifungal agents, much more effective and safer than the currently available to treat and to prevent C. tropicalis infections