Thermophysical properties of castor oil (ricinus communis l.) biodiesel and its blends

In this study, biodiesel (methyl ester) was produced from Castor Oil (Ricinus communis L.) (CO) using sodium hydroxide (NaOH) and methanol (CH3OH) by the two-step transesterification method. Nine different fuel blends (2, 5, 10, 20, 30, 40, 50, 60 and 75% by volume blending with diesel) were prepared. The density values of Castor Oil Biodiesel (COB) and its blends were measured at the temperature range from 0 to 93°C in steps of 5°C and the kinematic viscosity values of COB and its blends were measured at the temperature range from 30 to 100°C in the steps of 5°C. The results showed that the density, kinematic viscosity, calorific value, flash point, pH, copper strip corrosion and water content of COB are 932.40 kg·m-3, 15.069 mm².s-1, 38.600 MJ·kg-1, 182°C, 7, 1a and 1067.7 mg.kg-1, respectively. The density and kinematic viscosity of fuel samples decrease as temperature increases; and also these properties decrease as a result of the increase in the amount of diesel in the blends.Neste estudo, o biodiesel (metil éter) foi produzido a partir do óleo de rícino (Ricinus communis L.) (CO, por suas siglas em inglês) usando hidróxido de sódio (NaOH) e metanol (CH3OH) através de um método de transesterificação de dois passos. Foram preparadas até nove misturas de combustível diferentes (2, 5, 10, 20, 30, 40, 50, 60 e 75% por volume de mistura com o diesel). Os valores de densidade do biodiesel de óleo de rícino (COB, por suas siglas em inglês) e as suas misturas foram calculados dentro do rango de temperatura de 0 a 93°C no passo de 5°C e os valores de viscosidade cinemática do COB e das misturas foram calculadas no rango de temperatura de 30 a 100°C no passo de 5°C. Os resultados demonstraron que a densidade, viscosidade cinemática, valor calorífico, ponto de fusão, PH, corrosão da faixa de cobre e conteúdo de água do COB eram de 932.40 kg·m-3, 15.069 mm².s-1, 38.600 MJ·kg-1, 182°C, 7, 1a e 1067.7 mg.kg-1, respectivamente. Os valores de densidade e viscosidade cinemática das amostras de combustível diminuem na medida em que aumenta a temperatura; e também essas propriedades diminuem em decorrência do aumento na quantidade de diesel nas misturas.En este estudio, se produjo biodiesel (metil éter) a partir de aceite de ricino (Ricinus communis L.) (CO, de sus siglas en ingles) utilizando hidróxido de sodio (NaOH) y metanol (CH3OH) a través del método de transesterificación en dos pasos. Se prepararon nueve mezclas diferentes (2, 5, 10, 20, 30, 40, 50, 60 and 75% dependiendo del volumen de la mezcla con biodiesel. Se estimaron los valores de densidad del Biodiesel de Aceite de Ricino (COB, de sus siglas en ingles) y sus mezclas en un rango de temperatura de 0 a 93°C en intervalos de 5°C y también se estimaron los valores de viscosidad cinemática de COB y sus mezclas dentro del rango temperatura comprendido entre 30 y 100°C en intervalos de 5°C. Los resultados mostraron que la densidad, la viscosidad cinemática, el valor calorífico, el punto de ignición, pH, la corrosión de la franja de cobre y el contenido de agua del COB son 932.40 kg·m-3, 15.069 mm².s-1, 38.600 MJ·kg-1, 182°C, 7, 1a y 1067.7 mg.kg-1, respectivamente. La densidad y la viscosidad cinemática de las muestras de combustible disminuyen a medida que aumenta la temperatura; y también estas propiedades disminuyen como resultado del aumento en la cantidad de biodiesel en las mezclas

IJTC2007-44207 PERFORMANCE EVALUATION OF HALF-WETTED HYDRODYNAMIC BEARINGS WITH DLC COATED SURFACES

ABSTRACT In conventional liquid lubrication it is assumed that surfaces are fully wetted and no slip occurs between the fluid and the solid boundary. Under the "no slip" condition the maximum shear gradient occurs at the fluid-surface interface. When one or both surfaces are non-wetted by the fluid, boundary slip can occur due to weak bonding between the fluid and the solid surface, which reduces shear stresses in the fluid adjacent to the non-wetted surface. A thrust bearing tribometer was used to compare the performance of "no slip" hydrodynamic thrust bearings with bearings surfaces that were made to slip at the interface between the surface and fluid. Hydrophobic surfaces on both runner and bearing were achieved with the deposition of hydrogenated diamond like carbon (H-DLC) films, produced by plasma-enhanced CVD on titanium alloy surfaces. Hydrophilic surfaces were created through the surface modification of DLC. A mixtures of water and glycerol was used as the lubricant. The tests were conducted using different constant bearing gaps. The normal load and the torque or traction force between the rotating runner and hydrodynamic thrust bearing were measured with load cells. The experimental results confirmed that load support is still possible when surfaces are partially-wetted or nonwetted

The role of dura mater and free peritoneal graft in the reinforcement of colon anastomosis

Anastomotic leakage is the most important complication leading to morbidity and mortality in colorectal surgery. To prevent anastomotic leakage, a number of drugs with different mechanisms of action were tested, and autogenic grafts and various synthetic materials were used for reinforcement of the anastomotic region. In this experimental study aimed at preventing anastomotic leakage and dehiscence, we used dehydrated, lyophilized human dura mater and free peritoneal graft for reinforcement of anastomotic region after primary repair in rats, and investigated whether they are superior to primary anastomosis. The rats were sacrificed 3 and 7 days postoperatively. The anastomotic region was observed macroscopically for adhesions, bursting pressure of bowel was measured for tensile strength of the anastomosis, and histopathologic evaluation was performed for anastomotic healing. Compared to the control group, dura mater and free peritoneal graft groups displayed a lower bowel bursting pressure (p < .05), worse anastomotic healing (P < .05), a higher number of adhesions, and presence of anastomotic stricture. In conclusion, both human dura mater and free peritoneal graft reinforcement groups had worse anastomosis healing. The results could be attributed to avascularity of grafts and to aggravated adhesions between anastomosis and intra-abdominal organs, which created a favorable environment for reproduction and dispersion of bacteria and consequently led to decreased anastomosis healing

Top-surface characterization of a near frictionless carbon film

A detailed study of the top surface (similar to 2 nm) of a near frictionless carbon film has revealed new information with respect to the sp(3) fraction. Previous work on near frictionless carbon films made at Argonne had shown a large fraction of sp(2)-hybridized carbon in the bulk of the film. However, in this study of the surface, the majority of the carbon was found to be sp(3). In addition we compared and contrasted the behavior of the films after mechanical abrasion and Ar+ etching. The study also revealed that oxygen on untreated samples was rapidly reduced by etching or heating or mechanical abrasions this finding was corroborated by an angle-resolved study, where different depths of the sample were probed. It was also found that the traction of sp(3) carbon decreased linearly with depth, falling in one film from similar to 90% sp(3) to similar to 80% sp(3) in the top 2 nm. (c) 2006 Elsevier B.V. All rights reserved