No abstract

It is an important concern to prevent asphaltene related damages in hydrocarbon reservoirs.There are many investigations about asphaltene and its effects and how to reduce them during the oil production. In the present work, some experiments have been conducted to investigate the effect of the SiO2, NiO, and Fe3O4 nanoparticles on the oil recovery, and find out how they adsorb asphaltene and prevent its precipitation. Moreover, instead of crude oil, a synthetic solution with a given component concentration is used. Results of this study show that in solutions without nanoparticles, increase in the amount of normal heptane causes more asphaltene aggregation takes place; however, in the presence of nanoparticles, increasing the normal heptane would result in an increase in the asphaltene adsorption on the surface of nanoparticles. Furthermore, It is shown that the amount of oil recovery in the presence of different nanoparticles corresponds to the ordering: SiO2> NiO> Fe3O4.

No abstract

No abstract

No abstract

No abstract

No abstract

Near infrared spectroscopy (NIRS) is a functional imaging technique allowing measurement of local cerebral oxygenation. This modality is particularly adapted to critically ill neonates, as it can be used at the bedside and is a suitable and noninvasive tool for carrying out longitudinal studies. However, NIRS is sensitive to the imaged medium and consequently to the optical properties of biological tissues in which photons propagate. In this study, the effect of the neonatal fontanel was investigated by predicting photon propagation using a probabilistic Monte Carlo approach. Two anatomical newborn head models were created from computed tomography and magnetic resonance images: (1) a realistic model including the fontanel tissue and (2) a model in which the fontanel was replaced by skull tissue. Quantitative change in absorption due to simulated activation was compared for the two models for specific regions of activation and optical arrays simulated in the temporal area. A correction factor was computed to quantify the effect of the fontanel and defined by the ratio between the true and recovered change. The results show that recovered changes in absorption were more precise when determined with the anatomical model including the fontanel. The results suggest that the fontanel should be taken into account in quantification of NIRS responses to avoid misinterpretation in experiments involving temporal areas, such as language or auditory studies.