Influence of Water Content, Time, and Temperature on the Rheological Behavior of Polyethylene Terephtalate

In this work, the main factors affecting the rheological behavior of polyethylene terephtalate (PET) in the linear viscoelastic regime (water content, time delay before test, duration of experiment, and temperature) were accessed. Small amplitude oscillatory shear tests were performed after different time delays ranging from 300 to 5000 s for samples with water contents ranging from 0.02 to 0.45 wt %. Time sweep tests were carried out for different durations to explain the changes undergone by PET before and during small amplitude oscillatory shear measurements. Immediately after the time sweep tests, the PET samples were removed from the rheometer, analyzed by differential scanning calorimetry and their molar mass was obtained by viscometry analysis. It was shown that for all the samples, the delay before test and residence time within the rheometer (i.e. duration of experiment) result in structural changes of the PET samples, such as increase or decrease of molar mass, broadening of molar mass distribution, and branching phenomena. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 3525-3533, 2010

Liquid-Liquid Equilibrium of Aqueous Two-Phase Systems Containing Some Synthetic Polyelectrolytes and Polyethylene Glycol

Experimental results are presented for the liquid-liquid equilibrium of aqueous two-phase systems containing a synthetic polyelectrolyte (polysodium acrylate, polysodium methacrylate, and polysodium ethylene sulfonate) and polyethylene glycol at (298.2 and 323.2) K. A total of 40 phase diagrams were obtained, comprising data both of the binodal curve (obtained through cloud-point measurements) and of equilibrium compositions. The influences of temperature, the nature of the polyelectrolyte monomer unit, and the chain length of both types of polymers are analyzed and discussed.

Sensory Stability of Ultra-High Temperature Milk in Polyethylene Bottle

The objective of this study was to evaluate the sensory stability of ultra-high temperature (UHT) milk subjected to different heat treatments and stored at room temperature in white high density polyethylene bottles (HDPE) pigmented with titanium dioxide. Two lots of 300 units each were processed, respectively, at 135 and 141 degrees C/10 s using indirect heating and subsequently aseptically filled in an ISO class 7 clean room. These experimental lots were evaluated for appearance, aroma, flavor, and overall appreciation and compared to samples of commercial UHT milk purchased from local commercial stores. The time-temperature combinations investigated did not affect either the acceptability or the shelf life of the milk. Despite the limited light barrier properties of HDPE bottles, the product contained in the package tested exhibited good stability, with a shelf life ranging from 4 to 11 wk. Within this time period, the acceptability of the experimental lots was similar to that of the commercial products. The results achieved in this study contribute to turn the low-cost UHT system investigated into a technically viable option for small-size dairy processing plants.

Friction factor for small diameter polyethylene pipes

On this paper, the results of an experimental study oil the hydraulic friction loss for small-diameter polyethylene pipes are reported. The experiment was carried out using a range of Reynolds number between 6000 to 72000, obtained by varying discharge at 20 degrees C water temperature, with internal pipe diameters of 10.0 mm, 12.9 mm, 16.1 mm, 17.4 mm and 19.7 mm. According to the analysis results and experimental conditions, the friction factor 0 of the Darcy-Weisbach equation call be estimated with c = 0.300 and m = 0.25. The Blasius equation (c = 0.316 and m = 0.25) gives an overestimate of friction loss, although this fact is non-restrictive for micro-irrigation system designs. The analysis shows that both the Blasius and the adjusted equation parameters allow for accurate friction factor estimates, characterized by low mean error (5.1%).

Effect of Polyethylene Glycol on the Thermal Stability of Green Fluorescent Protein

Green fluorescent protein (GFP) shows remarkable structural stability and high fluorescence; its stability can be directly related to its fluorescence output, among other characteristics. GFP is stable under increasing temperatures, and its thermal denaturation is highly reproducible. Some polymers, such as polyethylene glycol, are often used as modifiers of characteristics of biological macromolecules, to improve the biochemical activity and stability of proteins or drug bioavailability. The aim of this study was to evaluate the thermal stability of GFP in the presence of different PEG molar weights at several concentrations and exposed to constant temperatures, in a range of 70-95 degrees C. Thermal stability was expressed in decimal reduction time. It was observed that the D-values obtained were almost constant for temperatures of 85, 90, and 95 degrees C, despite the PEG concentration or molar weight studied. Even though PEG can stabilize proteins, only at 75 degrees C, PEG 600 and 4,000 g/mol stabilized GFP. (C) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 26: 252-256, 2010

In vitro human epidermal and polyethylene membrane penetration and retention of the sunscreen benzophenone-3 from a range of solvents

Purpose. To study epidermal and polyethylene membrane penetration and retention of the sunscreen benzophenone-3 (BP) from a range of single solvent vehicles and evaluate solvent effects on permeability parameters. Methods. The solubility of BP was measured in a number of solvents. Penetration of BP across human epidermis and high density polyethylene (HDPE) membranes was studied from 50% saturated solutions in each solvent. Results. Maximal BP fluxes from the solvents across the two membranes varied widely. Highest fluxes were observed from 90% ethanol (EtOH) for epidermis and from isopropyl myristate (IPM) and C12-15 benzoate alcohols (C12-15 BA) for HDPE membrane. Both the flux and estimated permeability coefficient and skin-vehicle partitioning of BP appeared to be related to the vehicle solubility parameter (delta(v)). The major effects of solvents on BP flux appear to be via changes in BP diffusivity through the membranes. Conclusions. Minimal penetration of sunscreens such as BP is best achieved by choosing vehicles with a delta(v) substantially different to the solubility parameter of the membrane.

POLYETHYLENE GLYCOL ADDITION DOES NOT IMPROVE EXOGENOUS SURFACTANT FUNCTION IN AN EXPERIMENTAL MODEL OF MECONIUM ASPIRATION SYNDROME

Meconium (MEC) is a potent inactivator of pulmonary surfactant. The authors studied the effects of polyethylene glycol addition to the exogenous surfactant over the lung mechanics and volumes. Human meconium was administrated to newborn rabbits. Animals were ventilated for 20 minutes and dynamic compliance, ventilatory pressure, and tidal volume were recorded. Animals were randomized into 3 study groups: MEC group (without surfactant therapy); S100 group (100 mg/kg surfactant); and PEG group (100 mg/kg porcine surfactant plus 5% PEG). After ventilation, a pulmonary pressure-volume curve was built. Histological analysis was carried out to calculate the mean alveolar size (Lm) and the distortion index (DI). Both groups treated with surfactant showed higher values of dynamic pulmonary compliance and lower ventilatory pressure, compared with the MEC group (P .05). S100 group had a larger maximum lung volume, V30, compared with the MEC group (P .05). Lm and DI values were smaller in the groups treated with surfactant than in the MEC group (P .05). No differences were observed between the S100 and PEG groups. Animals treated with surfactant showed significant improvement in pulmonary function as compared to nontreated animals. PEG added to exogenous surfactant did not improve lung mechanics or volumes.

Polyethylene flow prediction with a differential multi-mode Pom-Pom model

We report the first steps of a collaborative project between the University of Queensland, Polyflow, Michelin, SK Chemicals, and RMIT University; on simulation, validation and application of a recently introduced constitutive model designed to describe branched polymers. Whereas much progress has been made on predicting the complex flow behaviour of many - in particular linear - polymers, it sometimes appears difficult to predict simultaneously shear thinning and extensional strain hardening behaviour using traditional constitutive models. Recently a new viscoelastic model based on molecular topology, was proposed by McLeish and Larson (1998). We explore the predictive power of a differential multi-mode version of the pom-pom model for the flow behaviour of two commercial polymer melts: a (long-chain branched) low-density polyethylene (LDPE) and a (linear) high-density polyethylene (HDPE). The model responses are compared to elongational recovery experiments published by Langouche and Debbaut (1999), and start-up of simple shear flow, stress relaxation after simple and reverse step strain experiments carried out in our laboratory.

Polyethylene-layered silicate nanocomposites for rotational moulding

A series of polyethylene-layered silicate nanocomposites has been studied as possible new candidates for rotational moulding. Two organically treated layered silicates were melt-compounded into a maleated linear low-density polyethylene host polymer at loadings of 6 and 9%, by weight. The morphology and properties of the nanocomposites were assessed by using dynamic mechanical thermal analysis, parallel-plate rheometry, wide-angle X-ray diffraction and transmission electron microscopy. The sintering behaviour of the nanocomposites was qualitatively assessed via hot-stage microscopy, indicating that the choice of nanofiller will play an important role in terms of producing nanocomposite materials with acceptable processability for rotational moulding. (C) 2003 Society of Chemical Industry.

A nova agenda internacional de segurança põe a democracia brasileira em risco?

Agenda Internacional de Segurança mudou após o fim da Guerra Fria. Surgiram novas ameaças, frequentemente domésticas, que vão de encontro às tradicionais teorias de segurança. Este artigo analisa documentos oficiais produzidos por atores nacionais e internacionais. É possível concluir que existem incentivos políticos e jurídicos para a participação de militares em atividades policiais. Essa participação, contudo, pode apresentar riscos para a democracia.

Adolescente e ato infracional : uma investigação acerca da medida socioeducativa de internação na cidade do Recife-PE

RESUMO: Este estudo procura avaliar a Medida Socioeducativa de Internação decretada a adolescentes autores de ato infracional na Cidade do Recife no ano de 2009. É um trabalho de grande importância para a sociedade brasileira, sobretudo, no que diz respeito ao combate à violência juvenil, à criminalidade em geral, e à construção de um mundo mais justo e solidário. Escolhemos a Cidade do Recife, Capital do Estado de Pernambuco, localizada na região Nordeste do Brasil, para ser o local da nossa pesquisa, por ser esta uma das mais violentas cidades do país. No decorrer desta pesquisa fizemos ainda uma breve análise do cenário sociológico da adolescência na Cidade do Recife. Em seguida estudamos o cenário jurídico dos adolescentes autores de ato infracional com base no Estatuto da Criança e do Adolescente – Lei nº 8.069/1990, analisando a evolução histórica do tratamento legal dispensado a estes jovens, abordando o conceito de adolescente e ato infracional, e investigando as Medidas Socioeducativas previstas na legislação brasileira, sobretudo, a Medida de Internação, pelo fato de ser a mais grave delas. Assim, além investigarmos através de dados estatísticos o quantitativo por gênero de adolescentes autores de ato infracional aos quais foram decretadas Medida de Internação, observamos os tipos de atos infracionais mais praticados. Intentamos, dessa forma, questionar a violência juvenil e o modo como a sociedade e as instituições envolvidas têm tratado a questão. Para tanto, foram realizadas entrevistas com servidores da Fundação de Atendimento Socioeducativo- FUNASE, entidade que trabalham diretamente com a reeducação de adolescentes autores de ato infracional submetidos à Internação na Cidade do Recife, para analisar como estão sendo aplicadas essas medidas. ABSTRACT: This study aims to evaluate the Socioeducational Measure of Internation decreed to transgressor teenagers in the City of Recife at the year 2009. This study has a big importance to Brazilian society, above all, because focalize the combat of the juvenile violence in Recife, Capital of the State of Pernambuco on the northwest of the Brazil, one of the most violent city of Brazil. During this investigation, was done a brief analysis of sociological scenery of teenage in this City. It was studied too, the juridical scenery of teenagers that committed any kind of transgression, based on the Statue of Child and the Adolescent- law n° 8.069/1990, analyzing the historical evolution of lawful treatment put into practice to this people, using the concept of adolescent and infracional act, and observing the social and educative punishment in the penal justice system of Brazil, and detaching the measure of internation, that is the gravest form of punishment. So, in this study it was investigated the quantity of transgressors adolescents based in gender and the kinds of transgression most practiced by them which results on internation measure decreed. This way, the purpose of this study is discuss about young violence and the way that society and institutions have faced this question. For this, it was realized interviews with Foundation of Socioeducative Attendance – FUNASE workers, that work directly with re-education of adolescents that committed any transgression and were submitted to internation punishment, in order to analyze how are being applied these measures.

Anemias em crianças de dois serviços de saúde de Recife, PE (Brasil)

Foi estudada a prevalência de anemia em 1.306 crianças, com idade compreendida entre 6 e 60 meses, de duas unidades de saúde, em Recife, PE, (Brasil). Na clientela pediátrica do Centro de Saúde Lessa de Andrade, mantido pelo Governo do Estado, a ocorrência de anemias era quase duas vezes superior à encontrada no Posto de Assistência Médica de Areias, pertencente ao Instituto Nacional de Assistência Médica e Previdência Social (INAMPS). A prevalência de valores baixos de hemoglobina predominava nas crianças abaixo de 2 anos de idade, variando de 41% a 77% nos extratos amostrais distribuídos nesta faixa etária. Além da relação com a idade, observou-se associação estatística entre ocorrência de anemias e estado nutricional definido pela classificação de Gomez e ainda, com a renda "per capita" das famílias das crianças examinadas. O trabalho faz parte de um estudo colaborativo sobre as anemias, em estados do nordeste do Brasil.