ABSTRACT
Reverse osmosis (RO) desalination is a technology that is commonly used to mitigate water scarcity problems; one of its disadvantages is the bio-fouling of the membranes used, which reduces its performance. In order to minimize this problem, this study prepared modified thin film composite (TFC) membranes by the incorporation of chitosan-silver particles (CS-Ag) of different molecular weights, and evaluated them in terms of their anti-biofouling and desalination performances. The CS-Ag were obtained using ionotropic gelation, and were characterized by Fourier transform infrared spectroscopy (FTIR), high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA) and dynamic light scattering (DLS). The modified membranes were synthetized by the incorporation of the CS-Ag using the interfacial polymerization method. The membranes (MCS-Ag) were characterized by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and contact angle. Bactericidal tests by total cell count were performed using Bacillus halotolerans MCC1, and anti-adhesion properties were confirmed through biofilm cake layer thickness and total organic carbon (%). The desalination performance was defined by permeate flux, hydraulic resistance, salt rejection and salt permeance by using 2000 and 5000 mg L-1 of NaCl. The MCS-Ag-L presented superior permeate flux and salt rejection (63.3% and 1% higher, respectively), as well as higher bactericidal properties (76% less in total cell count) and anti-adhesion capacity (biofilm thickness layer 60% and total organic carbon 75% less, compared with the unmodified membrane). The highest hydraulic resistance value was for MCS-Ag-M. In conclusion, the molecular weight of CS-Ag significantly influences the desalination and the antimicrobial performances of the membranes; as the molecular weight decreases, the membranes' performances increase. This study shows a possible alternative for increasing membrane useful life in the desalination process.
ABSTRACT
The removal of heavy metals from acid mine drainage is a key factor for avoiding damage to the environment. The microalga Nannochloropsis oculata was cultured in an algal medium with 0.05, 0.1, 0.15, 0.2, and 0.25 mM copper under completely defined conditions to assess its removal capacity; the effects of copper on the cell density and lipid productivity of N. oculata were also evaluated. The results showed that N. oculata was able to remove up to 99.92 ± 0.04% of the copper content in the culture medium. A total of 89.29 ± 1.92% was eliminated through metabolism, and 10.70 ± 1.92% was removed by adsorption. These findings are favorable because they indicate that a large amount of copper was extracted due to the ability of the microalga to metabolize copper ions. The cell density, growth rate, and lipid content decreased with increased concentrations of copper in the culture medium. A positive effect on the fatty acid profile was found, as the saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) content improved when the copper concentration was higher than 0.1 mmol L-1, which can potentiate the production of high-quality biodiesel. N. oculata is a good option for the treatment of acid mine drainage due to its ability to eliminate a substantial percentage of the copper present. Moreover, combining different culture systems such that heavy metals are removed to non-toxic levels in the first stage and high cell densities, which promote lipid production, is obtained in the second stage would be an advantageous strategy.
Subject(s)
Copper/metabolism , Microalgae/metabolism , Mining , Stramenopiles/metabolism , Water Pollutants, Chemical/metabolism , Biofuels , Environmental Restoration and Remediation , Fatty Acids/metabolism , Industrial Waste , Lipid Metabolism , Wastewater/chemistryABSTRACT
Inflammatory cloacogenic polyps are infrequent lesions that usually arise in the anorectal zone. The most common clinical presentation is rectal bleeding. Two cases of rectal bleeding related to cloacogenic polyps with different endoscopic appearance are reported. Endoscopists should be familiar with this entity, which should be considered in the differential diagnosis with other polypoid lesions observed in colonoscopy.
Subject(s)
Intestinal Polyps/diagnosis , Rectal Diseases/diagnosis , Adult , Anal Canal , Colonoscopy , Diagnosis, Differential , Female , Gastrointestinal Hemorrhage/etiology , HumansABSTRACT
Los pólipos inflamatorios cloacogénicos son lesiones poco frecuentes, que suelen surgir en la zona anorrectal. La presentación clínica más frecuente es en forma de sangrado rectal. Se presentan 2 casos de pólipos cloacogénicos con distinto aspecto endoscópico y clínica de rectorragia. El endoscopista debe tener en cuenta la existencia de esta entidad y considerarla en el diagnóstico diferencial con otras lesiones polipoideas que se pueden observar en la colonoscopia
Inflammatory cloacogenic polyps are infrequent lesions that usually arise in the anorectal zone. The most common clinical presentation is rectal bleeding. Two cases of rectal bleeding related to cloacogenic polyps with different endoscopic appearance are reported. Endoscopists should be familiar with this entity, which should be considered in the differential diagnosis with other polypoid lesions observed in colonoscopy
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Intestinal Polyps/complications , Gastrointestinal Hemorrhage/etiology , Endoscopy, Gastrointestinal , Colonoscopy , Diagnosis, Differential , Rectal Prolapse/complicationsABSTRACT
Fundamento: El sistema de formación de especialistas sanitarios (SFE) en nuestro país tiene una gran importancia en el mantenimiento de un Sistema de Salud de calidad. La evolución de dicho sistema ha ido configurando al tutor de los residentes en el eje sobre el que recae gran parte de la responsabilidad de la calidad del proceso formativo y de la competencia clínica de los especialistas titulados, sin que se hayan definido los requisitos que deberían acompañar dicha responsabilidad. El objetivo del estudio es explorar la opinión de los tutores respecto de sus responsabilidades y necesidades en el SFE, y en un contexto de tutoría planificada. Métodos: La investigación se realizó mediante cuatro grupos focales formados por tutores de atención primaria y hospitales, donde los residentes realizan su formación. Resultados: los discursos de los participantes se centraron en la definición del perfil asistencial y académico de los tutores, las características que debería reunir el proceso de selección y acreditación del tutor, y en las responsabilidades, funciones y reconocimiento de la tutoría. Conclusiones: se ha identificado claramente la falta de concordancia entre el valor que "en teoría" se otorga a la docencia y la "práctica" de la misma, caracterizada por su subordinación a la asistencia, la escasez de recursos y la falta de reconocimiento de la labor docente. Se apunta la democratización y objetivación del proceso de designación del tutor, una cierta independencia de la tutoría respecto de la estructura asistencial, la potenciación de las Comisiones Docentes y Asesoras, el reconocimiento en baremos profesionales y el tiempo destinado a la tutoría como la mejor compensación (AU)
