Abstract Background: The association of scaffolds to repair extensive bone defects can contribute to their evolution and morphophysiological recomposition. The incorporation of particulate biomaterials into three-dimensional fibrin bioproducts together with photobiomodulation therapy (PBM) has potential and can improve regenerative medicine procedures. The objective of this experiment was to evaluate the effects of PBM therapy on critical size defects filled with xenogenic bone substitute associated with fibrin biopolymer. Methods: A critical defect of 8 mm was performed in 36 Wistar male adult rats that were divided into four groups. Groups BC and BC-PBM were defined as controls with defects filled by a clot (without or with PBM, respectively) and groups XS and XS-PBM that comprised those filled with biocomplex Bio-OssTM in association with fibrin biopolymer. PBM was applied immediately after the surgery and three times a week every other day, with the parameters: wavelength of 830 nm, energy density 6.2 J/cm2, output power 30 mW, beam area of 0.116 cm2, irradiance 0.258,62 W/cm2, energy/point 0.72 J, total energy 2.88 J. Fourteen and 42 days after the surgery, animals were euthanatized and subjected to microtomography, qualitative and quantitative histological analysis. Results: The BC-PBM and XS-PBM groups had a similar evolution in the tissue repair process, with a higher density of the volume of new formed bone in relation to the groups without PBM (p = 0.04086; p = 0.07093, respectively). Intense vascular proliferation and bone deposition around the biomaterial particles were observed in the animals of the groups in which biocomplex was applied (XS and XS-PBM). Conclusion: PBM therapy allowed an improvement in the formation of new bone, with a more organized deposition of collagen fibers in the defect area. Biocomplex favored the insertion and permanence of the particulate material in bone defects, creating a favorable microenvironment for accelerate repair process.

Objetivo: Avaliar a capacidade da clonidina de reduzir a pressão arterial pulmonar de pacientes com hipertensão pulmonar, submetidos a cirurgia cardíaca, seja pela diminuição dos valores pressóricos a partir da aferição direta da pressão de artéria pulmonar, seja pela redução ouabolição da necessidade de dobutamina e nitroprussiato de sódio no intraoperatório. Método: Trata-se de estudo controlado, comparativo, randomizado e duplamente encoberto feito com 30 pacientes portadores de hipertensão arterial pulmonar tipo 2, submetidos a cirurgia cardíaca. Avaliaram-se a pressão média de artéria pulmonar e a posologia de dobutaminae nitroprussiato de sódio em quatro momentos: (M0) antes da administração de 2 µg/kg declonidina intravenosa ou placebo; (M1) decorridos 30 minutos do tratamento testado e antes da circulação extracorpórea; (M2) imediatamente após a circulação extracorpórea; e (M3)10 minutos após a injeção de protamina. Resultados: Não houve diferenças significativas em relação à pressão média de artéria pulmonarem nenhum dos momentos estudados. Entre os grupos não houve também diferença significativa entre as demais variáveis estudadas, como pressão arterial sistêmica média, frequência cardíaca, dosagem total de dobutamina, dosagem total de nitroprussiato de sódio e necessidade do hipnoanalgésico fentanil. Conclusão: A análise dos dados obtidos dos pacientes incluídos neste estudo permite concluir que a clonidina, na dose de 2 µg/kg administrada via intravenosa, não foi capaz de reduzir a pressão média de artéria pulmonar de pacientes com hipertensão pulmonar do grupo 2 (hipertensão venosa pulmonar), submetidos a cirurgia cardíaca, e nem reduzir ou abolir a necessidade da administração de dobutamina e nitroprussiato de sódio no intraoperatório.

Objective: Evaluate the ability of clonidine to reduce pulmonary arterial pressure in patients with pulmonary hypertension undergoing heart surgery, either by reducing the pressure values from the direct measurement of pulmonary arterial pressure or by reducing or eliminating the need for intraoperative dobutamine and nitroprusside. Method: Randomized, double-blind, placebo-controlled, comparative study conducted in 30 patients with pulmonary arterial hypertension type 2 undergoing cardiac surgery. Mean pulmonary arterial pressure and dosage of dobutamine and sodium nitroprusside were assessed four times: before intravenous administration of clonidine (2 µg/kg) or placebo (T0), 30 min after tested treatment and before cardiopulmonary bypass (T1), immediately after CPB (T2), 10 min after protamine injection (T3). Results: There were no significant differences regarding mean pulmonary arterial pressure at any time of evaluation. There was no significant difference between groups regarding other variables, such as mean systemic arterial pressure, heart rate, total dose of dobutamine, total dose of sodium nitroprusside, and need for fentanyl. Conclusion: Data analysis from patients included in this study allows us to conclude that intra-venous clonidine (2 µg/kg) was not able to reduce the mean pulmonary arterial pressure inpatients with pulmonary hypertension in group 2 (pulmonary venous hypertension), undergoing heart surgery, or reduce or eliminate the need for intraoperative administration of dobutamineand sodium nitroprusside.

Objetivo: Evaluar la capacidad de la clonidina de reducir la presión arterial pulmonar de pacientes con hipertensión pulmonar sometidos a cirugía cardíaca, sea por la disminución de los valores tensionales a partir de la comprobación directa de la presión de la arteria pulmonar, o por la reducción o supresión de la necesidad de dobutamina y nitroprusiato de sodio en el intraoperatorio. Método: Se trata de un estudio controlado, comparativo, aleatorizado y doble ciego hecho con 30 pacientes con hipertensión arterial pulmonar tipo 2, sometidos a cirugía cardíaca. Fueron evaluados la presión promedio de la arteria pulmonar y la posología de dobutamina y nitroprusiato de sodio en 4 momentos: (M0) antes de la administración de 2 µg/kg de clonidina intravenosa o placebo; (M1) transcurridos 30 min del tratamiento testado y antes de la circulación extracorpórea; (M2) inmediatamente después de la circulación extracorpórea; y (M3) 10 min después de la inyección de protamina. Resultados: No fueron verificadas diferencias significativas con relación a la presión promedio de la arteria pulmonar en ninguno de los momentos estudiados. Entre los grupos tampoco hubo diferencia significativa entre las demás variables estudiadas, como presión arterial sistémica promedio, frecuencia cardíaca, dosificación total de dobutamina, dosificación total de nitroprusiato de sodio y la necesidad del hipnoanalgésico fentanilo. Conclusiones: El análisis de los datos obtenidos de los pacientes incluidos en este estudio permite concluir que la clonidina en una dosis de 2 µg/kg administrada por vía intravenosa no fue capaz de reducir la presión promedio de la arteria pulmonar de pacientes con hipertensión pulmonar del grupo 2 (hipertensión venosa pulmonar), sometidos a cirugía cardíaca, ni tampoco reducir o suprimir la necesidad de la administración de dobutamina y nitroprusiato de sodio en el intraoperatorio.

Este trabajo presenta resultados de fisuración bajo tensión realizados con geomembranas (GM) de polietileno de alta densidad (HDPE). Las pruebas de tensión fueron realizados de acuerdo a la norma ASTM D5397: Notched Constant Tensile Load Test (NCTL) and Single Point-Notched Constant Tensile Load Test (SP-NCTL). Estos ensayos fueron realizados en muestras de control a 50 º C (ensayo padrón) y a 70 º C (condición acelerada) para comparar valores de fisuración bajo tensión. Los resultados de estos ensayos acelerados (NCTL) mostraron una economía total de 390 h (comparando etapas de carga de 25% de la tensión de ruptura) para los ensayos realizados.

This paper presents results of stress cracking tests performed in high density polyethylene (HDPE) geomembranes (GM). Stress cracking tests were performed in accordance to ASTM D5397: Notched Constant Tensile Load Test (NCTL) and Single Point-Notched Constant Tensile Load Test (SP-NCTL). Tests were conducted to the fresh sample at 50ºC (standard test) and at 70ºC (accelerated condition) in order to compare the SC values. Results from accelerated tests (NCTL) showed, for instance, a total economy of 390 hours (comparing load stages of 25% yield stress) to perform the tests.

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 ºC (temperature), 93 mm (precipitation), 66% (relative humidity), and 19 MJ/m².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.

Membranas impermeabilizantes de polietileno de alta densidade (PEAD) são utilizadas como revestimento em tanques de armazenamento de vinhaça (resíduo da cana-de-açúcar), onde esse resíduo é lançado a temperaturas médias de 80-90 °C. Devido a essas temperaturas elevadas e à acidez do resíduo, essas membranas podem degradar, fissurar e perder a função para a qual foram projetadas vindo a contaminar o solo e o lençol freático. Este trabalho avaliou o efeito da vinhaça em membranas de PEAD após 4 meses de exposição em ambiente controlado. De forma complementar, utilizou-se também um líquido agressivo de pH básico (soda cáustica). Objetivou-se avaliar a resistência da membrana em contato com esses resíduos (ácido e básico). Foram avaliadas as propriedades físicas, mecânicas, teor de negro de fumo e análise termogravimétrica (TGA) para quantificar a degradação das membranas poliméricas frente aos resíduos químicos utilizados. Os resultados mostram, por exemplo, que enquanto a soda cáustica provocou pequena variação nas propriedades físicas, a vinhaça alterou a espessura do material em 7,8%. Analisando-se a imersão na vinhaça, verificou-se uma diminuição média na resistência e deformabilidade (escoamento) de 34% e 23,5%, respectivamente. Houve um aumento médio na rigidez de 7,8% e uma pequena diminuição na resistência média ao rasgo (2,7%).

High-density polyethylene (HDPE) water-proof membranes are used as coatings in vinasse (leachate from sugar cane) storage tanks. The leachate is pumped into the tanks at temperatures of 80-90 °C. Due to these high temperatures and acidity of the waste, these membranes can be degraded, cracked and then loose the function for which they have been designed. This may cause contamination of the soil and groundwater. This study evaluated the effect of vinasse in HDPE membranes after 4 months of exposure in a controlled environment. An aggressive, alkaline pH liquid (sodium hydroxide) was also used. The objective was to evaluate the membrane resistance in contact with acidic and alkaline residues. Physical and mechanical tests, measurement of the carbon black content and thermo gravimetric analysis (TGA) were used to determine degradation of polymer membranes after chemical immersion. While sodium hydroxide resulted caused only minor changes in the physical properties, vinasse induced a thickness change of 7.8%. With immersion in vinasse, an average decrease in strength and deformability (yield) of 34% and 23.5% were measured, respectively. The stiffness increased by 7.8% (average) and the tear strength decreased by 2.7% (average).

Este trabalho teve como objetivo analisar o comportamento mecânico da mistura de um solo residual jovem de textura predominantemente arenosa reforçado com fibras de polipropileno, com vistas à aplicação em estradas florestais. Como ponto de partida, determinou-se, mediante os resultados de ensaios de compressão não-confinada, realizados em corpos-de-prova compactados na energia do ensaio Proctor Normal, que o quantitativo de 0,75% de fibras com 20 mm de comprimento foi a combinação responsável pelo maior ganho de resistência. Com a mistura solo-fibra composta por essa combinação, foram realizados ensaios triaxiais do tipo CID/Sat em corpos-de-prova compactados na energia anteriormente referida. Através desta pesquisa, foi possível avaliar: (i) a influência da variação da umidade nos parâmetros de resistência mecânica do solo e das misturas solo-fibra e (ii) a influência das fibras nos parâmetros de resistência ao cisalhamento do solo em estudo. Analisando os resultados, pôde-se concluir que o uso de fibras de polipropileno promoveu um ganho da ordem de 110% na resistência à compressão não-confinada e de 560% na coesão de intercepto do solo estudado.

The purpose of this study was to analyze the mechanical behavior of a polypropylene fiber-reinforced young residual sandy soil for forest road application. The first step was to determine the best combination of fiber content and length that would give the greatest increase in unconfined compressive strength of mixture specimens compacted at the Standard Proctor effort. The best combination resulting from the laboratory test program was 0.75% fiber content and fiber 20-mm length. The next step in the testing program was to run triaxial CID/Sat tests in mixture specimens prepared with the best combination and compacted at the Standard Proctor effort. From the laboratory testing program data it was possible to evaluate the influence of the water content in the mechanical response of the soil and fiber-reinforced soil, and to assess the influence of the fibers on the soil shear strength parameters. Data supported that soil reinforcement with polypropylene fiber was responsible for 110% increase in the unconfined compressive strength and 560% increase in the intercept cohesion of the studied soil.

O objetivo desse estudo foi caracterizar geotecnicamente o produto fibrossolo, com vistas a aplicações em obras de engenharia civil. Trabalhou-se com um tipo de solo, de textura argilosa, e pode-se avaliar, experimentalmente, via resultados de ensaios realizados em amostras de grandes dimensões, o comportamento mecânico do solo e do fibrossolo. Com esses materiais, realizou-se: (i) ensaios com o dilatômetro de Marchetti; e (ii) provas de carga com o emprego de carregamentos externos uniformemente distribuídos, aplicados na superfície dos terraplenos. Através desse trabalho foi possível avaliar a influência das fibras na capacidade de carga do solo estudado.

This study was directed to the geotechnical characterization of the material called fibersoil for civil engineering purposes. One soil was used throughout the study, encompassing a clayey soil, and can be evaluate, experimentally, from resulted of tests accomplished in samples of great dimensions, the mechanical behavior of the soil and fibersoil. For these materials, the following tests had been accomplished: (i) tests with Marchetti dilatometer, and (ii) tests with external loads evenly distributed, applied to the surface of the flat land. From the experimental testing program data it was possible to evaluate the influence of the fibers in the load capacity of the soil studied.