Effect of a SILICA/HPAM Nanohybrid on Heavy Oil Recovery and Treatment: Experimental and Simulation Study.

The addition of nanoparticles has been presented as an alternative approach to counteract the degradation of polymeric solutions for enhanced oil recovery. In this context, a nanohybrid (NH34) of partially hydrolyzed polyacrylamide (MW ∼12 MDa) and nanosilica modified with 2% 3-aminopropyltriethoxysilane (nSiO2-APTES) was synthesized and evaluated. NH34 was characterized by using dynamic light scattering, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. Fluid-fluid tests assessed its viscosifying power, mechanical stability, filterability, and emulsion behavior. Rock-fluid tests were carried out to determine the nanohybrid's adsorption in porous media, the inaccessible pore volume (IPV), and the resistance (RF) and residual resistance factors (RRF). These tests were conducted under the conditions of a Colombian field. NH34 results were compared with four (4) commercial polymers (P34, P88, P51, and PA2). The viscosifying power of NH34 was observed to be similar to that of the four commercial polymers at a lower concentration, but it exhibits more resistance to mechanical and chemical degradation. The evaluation of the emulsion behavior showed that the nanohybrid neither changed the dehydration process nor altered the crude oil viscosity, favoring its extraction at the wellhead. However, the water clarification treatment must be adjusted because the oil and grease contents and turbidity increase with the residual concentration of NH34. Incremental oil recovery factors obtained by numerical simulation (compared to waterflooding) were P51 (5.5%) > P34 (4.9%) > P88 (4.8%) > NH34 (2.6%) > PA2 (0.9%). The polymers P51, P34, and P88 had a better recovery factor than NH34 and PA2 due to their lower values of residual adsorption and IPV. Few studies have been reported on polymer nanohybrids' emulsion and flow behavior. Therefore, further research is needed to enhance our understanding of the fundamental enhanced oil recovery mechanisms associated with polymer nanohybrids.

Changes in marijuana use symptoms and emotional functioning over 28-days of monitored abstinence in adolescent marijuana users.

RATIONALE: Advancing marijuana prevention and intervention efforts are important given the decreasing perception of harm among adolescents and increasing marijuana legalization. OBJECTIVES: This study evaluates how a monitored abstinence protocol may contribute to emotional functioning and changes in marijuana problems that can enhance successful outcomes for non-treatment-seeking adolescent marijuana users. METHODS: Adolescent marijuana users (n = 26) and demographically matched controls (n = 30) completed 28 days of monitored abstinence confirmed by biweekly urine toxicology. Participants were given measures of emotional functioning, marijuana use symptoms, and reward sensitivity during monitored abstinence. RESULTS: All participants (n = 56) completed the protocol, and 69% of marijuana users (n = 18 of 26) were confirmed abstinent for 28 days, with all users showing decreasing marijuana use. Reductions in subsyndromal depression, positive marijuana use expectancies, and poor sleep quality were observed by the end of the monitored abstinence period (n = 26, p values < .05). Marijuana users also reported more attentional impulsivity and less responsiveness to reward stimuli during the second week of abstinence compared to controls. Later age of onset of regular marijuana use and more cumulative lifetime use were associated with a greater degree of emotional change and increased recognition of the negative effects of marijuana use. CONCLUSIONS: Monitored abstinence programs may be beneficial in reducing marijuana use, subsyndromal emotional distress symptoms, and changing beliefs about marijuana use. Future prevention and intervention efforts may consider targeting reward sensitivity and impulsivity, in addition to marijuana use, expectancies, and emotional functioning.

El trabajo nocturno y sus implicaciones en la salud de médicos, enfermeras y oficiales de seguridad de los hospitales de la Caja Costaricense del Seguro Social en Costa Rica / Night work and its implications on the health of doctors, nurses and security officers hospitals Costaricense Social Security Fund in Costa Rica

En el presente trabajo se analiza la jornada laboral nocturna y las implicaciones que ésta tiene en la salud de los trabajadores de una institución que por sus características requiere atención las 24 horas, los siete días a la semana, como lo es la Caja Costarricense del Seguro Social. Para ello se escogió una muestra de médicos, enfermeras y oficiales de seguridad y se les interrogó acerca de las enfermedades que padecían, para tratar de establecer su relación con la jornada nocturna...

This paper analyzes the night work and its implications on the health of workers in an institution which by its nature requires 24-hour care, seven days a week, as is La Caja Costarricense de Seguro Social. For this, it was chosen a sample of doctors, nurses and security officers and they were questioned about illnesses they had, to try to establish its relationship with the night shift...

Actitudes y prácticas de las mujeres en edad reproductiva relacionadas con el trabajo del promotor de salud Andes – Antioquia 1993 – 1996 / Attitudes and practices of women in maternal-age related with the job done by the health promoter program. Andes, Antioquia, 1993 - 1996

En salud, al hablar de enfermedad se pretende a través de la educación, crear una cultura, es decir, que el individuo en vez de investigar como se enfermema, reconozca que hacer para no estarlo y controle aquellas situaciones que le puedan enfermar. Con la educación se pretende cambiar “estilo de vida”, lo cual no es tarea fácil, ni se logra de la noche a la mañana. Necesariamente, los estilos de vida reflejan las condiciones culturales que nos rodean y, en consecuencia, están en permanente transformación en el tiempo, siendo el acceso a la información y a la educación determinantes en este proceso de cambio.