Thermo-gravimetric analysis (TGA) after different exposures of high density polyethylene (HDPE) and poly vinyl chloride (PVC) geomembranes

This paper presents the results of thermogravimetric analysis (TGA) tests in PVC (1.0; 2.0 mm) and HDPE (0.8; 2.5 mm) geomembranes exposed to weathering and leachate after 30 months. The aim of this paper is the comparison of fresh and exposed samples to assess the degradation process concerning the total loss of mass of geomembranes. The exposure was conducted in accordance with the recommendations of ASTM standards. The TGA tests were carried out according to ASTM D6370 and E2105. Results show, for instance, that for PVC geomembrane the largest reductions of plasticizers occurred for samples exposed to weathering. The loss of plasticizers after the exposure contributed to the decrease of deformation and consequent increase in stiffness. TGA tests shows to be a valuable tool to control the quality of the materials. © 2012 ejge.

Acute Phase Responses of Different Positions of High-Goal (Elite) Polo Ponies

The aim of this study was to investigate the acute phase response (APR) in 15 horses by quantifying physiological venous blood variables and serum acute phase proteins (APP) at 5 minutes and 6 and 12 hours after a training match of high-goal polo. The horses were divided into three experimental groups based on their team positions, including defense (n = 6), midfield (n = 5), and attack (n = 4). Serum proteinograms were obtained by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Data were evaluated using analysis of variance for repeated measures. The match represented a high-intensity stimulus for all positions. Defenders appeared to use the anaerobic pathway more than the other positions, as shown by their lower pH and greater lactatemia. Alterations in muscle membrane permeability were observed in all horses, as seen by the increase in serum creatine kinase activity without a correlation with APR. Significant elevations in total serum protein, albumin, ceruloplasmin, haptoglobin, alpha-1 antitrypsin, and 23-kDa protein were seen only during the course of the physical exertion of the match, although there were no differences in these values among positions of the team. After 6 hours of the match, the concentration of transferrin declined, whereas that of alpha-1 acid glycoprotein remained unaltered at all assessed times. These results demonstrated that the defenders required the most use of the anaerobic pathway during the match, and that equestrian polo exercise triggers an acute phase response of relatively short duration; this APR is characterized as noninflammatory, as APR appears to be a physiological alteration related to the stress inherent in physical exercise. © 2013 Elsevier Inc. All rights reserved.

Characterization of high density polyethylene (HDPE) reinforced with banana peel fibers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A randomized clinical trial of high volume peritoneal dialysis versus extended daily hemodialysis for acute kidney injury patients

Background: Acute kidney injury (AKI) requiring dialysis in critically ill patients is associated with an in-hospital mortality rate of 50-80 %. Extended daily hemodialysis (EHD) and high volume peritoneal dialysis (HVPD) have emerged as alternative modalities. Methods: A double-center, randomized, controlled trial was conducted comparing EHD versus HVPD for the treatment for AKI in the intensive care unit (ICU). Four hundred and seven patients were randomized and 143 patients were analyzed. Principal outcome measure was hospital mortality, and secondary end points were recovery of renal function and metabolic and fluid control. Results: There was no difference between the two groups in relation to median ICU stay [11 (5.7-20) vs. 9 (5.7-19)], recovery of kidney function (26.9 vs. 29.6 %, p = 0.11), need for chronic dialysis (9.7 vs. 6.5 %, p = 0.23), and hospital mortality (63.4 vs. 63.9 %, p = 0.94). The groups were different in metabolic and fluid control. Blood urea nitrogen (BUN), creatinine, and bicarbonate levels were stabilized faster in EHD group than in HVPD group. Delivered Kt/V and ultrafiltration were higher in EHD group. Despite randomization, there were significant differences between the groups in some covariates, including age, pre-dialysis BUN, and creatinine levels, biased in favor of the EHD. Using logistic regression to adjust for the imbalances in group assignment, the odds of death associated with HVPD was 1.4 (95 % CI 0.7-2.4, p = 0.19). A detailed investigation of the randomization process failed to explain the marked differences in patient assignment. Conclusions: Despite faster metabolic control and higher dialysis dose and ultrafiltration with EHD, this study provides no evidence of a survival benefit of EHD compared with HVPD. The limitations of this study were that the results were not presented according to the intention to treat and it did not control other supportive management strategies as nutrition support and timing of dialysis initiation that might influence outcomes in AKI. © 2012 Springer Science+Business Media Dordrecht.

Scaling invariance of the diffusion coefficient in a family of two-dimensional Hamiltonian mappings

We consider a family of two-dimensional nonlinear area-preserving mappings that generalize the Chirikov standard map and model a variety of periodically forced systems. The action variable diffuses in increments whose phase is controlled by a negative power of the action and hence effectively uncorrelated for small actions, leading to a chaotic sea in phase space. For larger values of the action the phase space is mixed and contains a family of elliptic islands centered on periodic orbits and invariant Kolmogorov-Arnold-Moser (KAM) curves. The transport of particles along the phase space is considered by starting an ensemble of particles with a very low action and letting them evolve in the phase until they reach a certain height h. For chaotic orbits below the periodic islands, the survival probability for the particles to reach h is characterized by an exponential function, well modeled by the solution of the diffusion equation. On the other hand, when h reaches the position of periodic islands, the diffusion slows markedly. We show that the diffusion coefficient is scaling invariant with respect to the control parameter of the mapping when h reaches the position of the lowest KAM island. © 2013 American Physical Society.

Zeros of a family of hypergeometric para-orthogonal polynomials on the unit circle

Para-orthogonal polynomials derived from orthogonal polynomials on the unit circle are known to have all their zeros on the unit circle. In this note we study the zeros of a family of hypergeometric para-orthogonal polynomials. As tools to study these polynomials, we obtain new results which can be considered as extensions of certain classical results associated with three term recurrence relations and differential equations satisfied by orthogonal polynomials on the real line. One of these results which might be considered as an extension of the classical Sturm comparison theorem, enables us to obtain monotonicity with respect to the parameters for the zeros of these para-orthogonal polynomials. Finally, a monotonicity of the zeros of Meixner-Pollaczek polynomials is proved. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of high temperature plasma immersion ion implantation on wear resistance of Ti-Si-B sintered alloys

Although titanium and its alloys own good mechanical properties and excellent corrosion resistance, these materials present poor tribological properties for specific applications that require wear resistance. In order to produce wear-resistant surfaces, this work is aimed at achieving improvement of wear characteristics in Ti-Si-B alloys by means of high temperature nitrogen plasma immersion ion implantation (PIII). These alloys were produced by powder metallurgy using high energy ball milling and hot pressing. Scanning electron microscopy (SEM) and X-ray diffraction identified the presence of α-titanium, Ti6Si2B, Ti5Si3, TiB and Ti3Si phases. Wear tests were carried out with a ball-on-disk tribometer to evaluate the friction coefficient and wear rate in treated and untreated samples. The worn profiles were measured by visible light microscopy and examined by SEM in order to determine the wear rates and wear mechanisms. Ti-7.5Si-22.5B alloy presented the highest wear resistance amongst the untreated alloys produced in this work. High temperature PIII was effective to reduce the wear rate and friction coefficient of all the Ti-Si-B sintered alloys. © 2013 Elsevier B.V.

Optimisation of High Hydrostatic Pressure Processing of Pêra Rio Orange Juice

The influence of high hydrostatic pressure (HHP) on Pêra Rio orange juice was investigated using response surface methodology. A central composite design was used to evaluate the effects of three processing conditions (independent variables), namely pressure (100-600 MPa), temperature (30-60 °C) and time (30-360 s), on the native microflora and pectin methylesterase (PME) activity of orange juice. Analysis of variance showed that second-order polynomial models fitted well with the experimental data for PME residual activity (R2 = 0.9586, p < 0.001) and aerobic microorganism count (R2 = 0.9879, p < 0.001). The optimum HHP processing conditions to produce orange juice with PME residual activity of less than 20 % and low microorganism count (<2 log cycles CFU/mL) were 550 to 600 MPa, 55 to 60 °C and 330 to 360 s. © 2013 Springer Science+Business Media New York.

Resveratrol reduces chronic inflammation and improves insulin action in the myocardium of high-fat diet-induced obeserats

OBJETIVO: Avaliar o efeito do resveratrol sobre a via de sinalização da insulina e melhora do quadro inflamatório no miocárdio de ratos Wistar obesos induzidos por dieta.MÉTODOS: Ratos Wistar foram divididos em grupos: controle (dieta padrão para roedores), obeso (dieta hiperlipídica) e obeso suplementado com resveratrol (20 mg/kg/dia), por 8 semanas (n=10). Ao final do período experimental, realizou-se o teste de tolerância à insulina, nos tempos 0 (sem insulina), 5, 10, 15, 20, 25 e 30 minutos após injeção intraperitoneal de insulina (2 U/kg). O peso corporal e o tecido adiposo epididimal foram mensurados. Fragmentos do miocárdio foram extraídos para análises da via da insulina e moléculas pró-inflamatórias através de Western blot.RESULTADOS: Os resultados indicam que a intervenção com resveratrol aumenta a constante de decaimento da glicose, fosforilação do receptor de insulina, substrato do receptor de insulina e da proteína quinase B. A suplementação de resveratrol também reduziu os níveis proteicos do fator de necrose tumoral alfa e de moléculas envolvidas com a transdução do sinal pró-inflamatório (quinase indutora do kappa B e fator nuclear kappa B). Os resultados ainda sugerem que a melhora na sensibilidade à insulina e a redução das moléculas pró-inflamatórias ocorreram independentemente da perda de peso corporal e da redução do tecido adiposo epididimal.CONCLUSÃO: A suplementação de resveratrol aumenta a sensibilidade à insulina, o que está relacionado à redução de fatores inflamatórios no miocárdio.

Prevalence of high blood pressure in Brazilian adolescents and quality of the employed methodological procedures: systematic review

OBJETIVO:Revisar a literatura sobre estudos que estimaram a prevalência de pressão arterial elevada (PAE) ou hipertensão arterial sistêmica (HAS) em adolescentes brasileiros, considerando os procedimentos metodológicos empregados.MÉTODOS:Pesquisa bibliográfica de estudos de prevalência de PAE/HAS em adolescentes de 1995 a 2010. A busca foi realizada nas bases de dados eletrônicos PubMed/Medline, Lilacs, SciELO, Isi e Adolec. Foram utilizados os descritores: hipertensão, pressão arterial, adolescente, estudantes, estudos transversais, prevalência e Brasil, nas línguas portuguesa e inglesa. Além disso, foi elaborado um escore, baseado nas Recommendations for Blood Pressure Measurement in Humans and Experimental Animals e nas VI Diretrizes Brasileiras de Hipertensão, para a análise dos procedimentos utilizados para medida da PA nos estudos variando de 0 a 18.RESULTADOS:Foram identificados 21 artigos, a maioria publicada nos últimos 10 anos, sendo 90,5% realizados em base escolar e nas regiões sudeste, nordeste e sul do país. As prevalências de PAE/HAS variaram de 2,5 a 30,9%. A pontuação dos estudos variou de 0 a 16. Foi observada uma correlação negativa significante (rho = -0,504; p = 0,020) entre a prevalência de PAE/HAS e o escore da qualidade da medida da PA.CONCLUSÃO:A grande variabilidade das estimativas da PAE/HAS parece ser influenciada pelos procedimentos metodológicos utilizados nos estudos.

Impact strength and abrasion resistance of high strength concrete with rice husk ash and rubber tires

The paper discusses the application of High Strength Concrete (HSC) technology for concrete production with the incorporation of Rice Husk Ash (RHA) residues by replacing a bulk of the material caking and rubber tires with partial aggregate volume, assessing their influence on the mechanical properties and durability. For concrete with RHA and rubber, it was possible to reduce the brittleness by increasing the energy absorbing capacity. With respect to abrasion, the RHA and rubber concretes showed lower mass loss than the concrete without residues, indicating that this material is attractive to be used in paving. It is thus hoped that these residues may represent a technological and ecological alternative for the production of concrete in construction works.

A family of dissipative two-dimensional mappings: Chaotic, regular and steady state dynamics investigation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

SVET, SKP and EIS study of the corrosion behaviour of high strength Al and Al-Li alloys used in aircraft fabrication

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The Effects of Weathering Exposure on the Physical, Mechanical, and Thermal Properties of High-density Polyethylene and Poly (Vinyl Chloride)

This paper presents results describing the physical, mechanical, and thermal properties (melt flow index - MFI and oxidative induction time - OIT) of high density polyethylene and poly (vinyl chloride) after weathering exposure (6, 12, 18, and 30 months). The materials exposed were geomembranes of two thicknesses: 1.0 and 2.0 mm (PVC) and 0.8 and 2.5 mm (HDPE). The climate parameters (average) obtained were 25 degrees C (temperature), 93 mm (precipitation), 66% (relative humidity), and 19 MJ/m(2). day (intensity of global radiation). Some results showed, for instance, that the behavior of the geomembranes changed after the exposures. A few minor variations in physical properties occurred. The density and thickness, for instance, varied 0.5-1.0% (average) for both the PVC and HDPE geomembranes. The mechanical properties changed as a function of the period of exposure. In general, some decreases were verified by the deformation of PVC. The samples became more rigid. In contrast, HDPE geomembranes became more ductile. Despite the variations in elasticity, some increases in deformability were verified. An MFI test showed some degradation in HDPE geomembranes. OIT tests revealed small values for both intact and exposed samples.

Nutritional value of high moisture corn silage in the diet of Holstein cows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)