Semi-alicyclic polyimides as potential membrane oxygenators: Rheological implications on film processing, morphology and blood compatibility

Two polyimide structures were prepared from an alicyclic dianhydride and aromatic diamines, containing or lacking fluorine, and were tested as potential membrane oxygenators. First, the solution rheological properties were investigated to evaluate their effect on film processing by tape casting. Velocity and shear rates profiles were simulated to determine the shearing conditions during tape casting and transfer them in the flow curves. Proper films were obtained at a viscosity corresponding to a concentration in entangled regime, where pseudoplastic behavior is still noticed at shear rates beneath the blade. Theoretical predictions of gas permeability indicated a good oxygen (O2) exchange and carbon dioxide (CO2) removal through the studied polymers. Atomic force microscopy (AFM) scans revealed a morphology characterized by an intrinsic porosity. The pore size, uniformity and size distribution was affected by the structure of the diamine moiety. The interactions of blood with polyimide films indicated no prevalent adhesion of cells or plasma proteins. The results showed that the examined samples have adequate properties for potential membrane oxygenator applications

The influence of polysilane chemical structure on optical properties, rubbed film morphology and LC alignment

Polysilane films were prepared by the drop casting method and their optical and morphological properties have been analyzed in order to investigate their suitability as alignment layers for nematic molecules. The samples do not absorb the radiations in the visible domain, particularly those containing methylhydrosilyl units, and present a transmittance of about 90% starting from 390 to 1100 nm. The optical band-gap is higher than 3.26 eV for all polysilanes indicating a low probability of optical absorption processes in the visible range. The morphology of the pristine samples shows isotropically distributed granular formations. The polymer surface was oriented by rubbing with two types of velvet: one with short fibers and the other with long fibers. The latter generates higher surface anisotropy, as shown by the reduction of the surface texture direction index values. The presence of methylhydrosilyl units allows a denser packing of the polymer structure and thus finer surface periodicities, leading to better orientation of the nematic molecules on the polysilane surface

Psicologia e nutrição: predizendo a intenção comportamental de aderir a dietas de redução de peso entre obesos de baixa renda Psychology and nutrition: predicting behavioral intention to follow weight reduction diets among low-income obese patients

O presente estudo foi realizado entre 189 obesos de baixa renda atendidos por nutricionistas na rede pública de saúde de João Pessoa, Paraíba. Levantou as crenças positivas e negativas e os referentes mais expressivos sobre estes pacientes quanto ao comportamento de seguir uma dieta médica para redução de peso. Um instrumento de medida da intenção comportamental de efetivamente seguir tais dietas foi construído, o que permitiu verificar a ênfase do aspecto normativo geral e atitudinal nos obesos com renda de até um salário-mínimo sobre sua intenção comportamental. Isto pode indicar dois pontos eficazes a serem explorados em comunicações dirigidas a esta classe social em campanhas de saúde para redução de peso. Esta medição torna-se útil para ações preventivas de saúde; a obesidade é considerada uma epidemia mundial carente de controle imediato, aumentando em incidência principalmente nas classes mais baixas dos países em desenvolvimento.<br>The present study was accomplished with 189 low income obese attended by public health nutritionists of João Pessoa, Paraíba. We found out positive and negative beliefs plus the most expressive referees on these patients about the behavior of following a medical diet to reduce weight. This permitted to build a behavioral intention measurement instrument to check those who might really follow these diets. It was verified the emphasis on general normative and attitudinal aspects over obese who had up to one minimum-wage income. This may indicate two efficacious points to be explored on targeted communications to this social class during weight loss public health campaigns. This measurement can be turned into preventive health actions; obesity is considered worldwide as epidemics, in need of immediate control, growing in incidence mainly among lower ranks of the population of developing countries

Pseudomonas syringae Phytotoxins: Mode of Action, Regulation, and Biosynthesis by Peptide and Polyketide Synthetases

Coronatine, syringomycin, syringopeptin, tabtoxin, and phaseolotoxin are the most intensively studied phytotoxins of Pseudomonas syringae, and each contributes significantly to bacterial virulence in plants. Coronatine functions partly as a mimic of methyl jasmonate, a hormone synthesized by plants undergoing biological stress. Syringomycin and syringopeptin form pores in plasma membranes, a process that leads to electrolyte leakage. Tabtoxin and phaseolotoxin are strongly antimicrobial and function by inhibiting glutamine synthetase and ornithine carbamoyltransferase, respectively. Genetic analysis has revealed the mechanisms responsible for toxin biosynthesis. Coronatine biosynthesis requires the cooperation of polyketide and peptide synthetases for the assembly of the coronafacic and coronamic acid moieties, respectively. Tabtoxin is derived from the lysine biosynthetic pathway, whereas syringomycin, syringopeptin, and phaseolotoxin biosynthesis requires peptide synthetases. Activation of phytotoxin synthesis is controlled by diverse environmental factors including plant signal molecules and temperature. Genes involved in the regulation of phytotoxin synthesis have been located within the coronatine and syringomycin gene clusters; however, additional regulatory genes are required for the synthesis of these and other phytotoxins. Global regulatory genes such as gacS modulate phytotoxin production in certain pathovars, indicating the complexity of the regulatory circuits controlling phytotoxin synthesis. The coronatine and syringomycin gene clusters have been intensively characterized and show potential for constructing modified polyketides and peptides. Genetic reprogramming of peptide and polyketide synthetases has been successful, and portions of the coronatine and syringomycin gene clusters could be valuable resources in developing new antimicrobial agents