María Abián

EFFECT OF RECIRCULATION GASES ON SOOT FORMED FROM ETHYLENE PYROLYSIS

Flue gas recirculation (FGR) is an effective technology both to control NOx emissions during combustion processes and to control temperature and make-up for the volume of the missing N2 during oxy-fuel combustion processes. In this article, a study of the individual role of the main products that are expected to form part of the recycled flue gas (CO, H2, H2O, and CO2) on soot and gas products formed during the thermal decomposition of ethylene-additive gas mixtures in the 975–1475 K temperature range is reported. Experimental results obtained in a quartz flow reactor are examined with the main objective of assessing the effectiveness of each gas additive in suppressing or boosting soot formation. Additionally, experimental data have been interpreted in terms of a literature detailed gas-phase kinetic model to analyze the evolution of gas products and get a better understanding of the gas-phase processes involving the thermal decomposition of the ethylene-additive gas mixtures, although soot formation reactions are not included in such mechanism.

Interaction of Soot–SO2: Experimental and Kinetic Analysis

ABSTRACT This study aims to evaluate the capability of SO2 to interact with soot and to determine the kinetics of this reaction under conditions of interest for combustion. The conditions of the soot reactivity experiments were: 1% SO2 with nitrogen to balance, around 10 mg of soot, and different reaction temperatures for each run: 1275, 1325, 1375, 1425, and 1475 K. Results demonstrate that SO2 does interact with soot. The evaluation of the soot reactivity has been based on the calculation of the time for the complete conversion of carbon through the employment of the Shrinking Core Model equations for decreasing size particle with chemical reaction control. The reactivity of soot with SO2 increased by a factor of about 3 when increasing the reaction temperature of the test from 1275 K to 1475 K. Kinetics in terms of Arrhenius parameters showed that the activation energy of the interaction of soot with SO2 was around 82 kJ/mol.

Prevalence of the need for sodium intake restriction and the use of laxatives in palliative patients

espanolAntecedentes: la poblacion paliativa suele sufrir patologias que requieren una restriccion de sodio en su dieta, aunque se desconoce la prevalencia de este requerimiento. Estas patologias, junto al estrenimiento, hacen que pueda desaconsejarse el uso de laxantes con electrolitos. Objetivo: conocer la prevalencia de la necesidad de restringir la ingesta de sodio en pacientes paliativos y analizar la prevalencia de estrenimiento y del uso de laxantes, incluidos los que contienen sodio. Metodo: estudio epidemiologico, multicentrico, descriptivo, transversal y retrospectivo en pacientes mayores de 18 anos recibidos en la consulta hospitalaria de paliativos (junio 2015-marzo 2016) tanto externos como hospitalizados. Se recogieron las caracteristicas demograficas y antropometricas, enfermedades asociadas a la restriccion de sodio en la dieta y tratamientos usados. Resultados: se incluyeron 400 pacientes paliativos (edad 77,8 ± 13,0 anos, hombres 52,2%). El 68,3% fueron pacientes hospitalizados y el 31,8%, externos. En el 87,0% (IC95%: 83,3-90,0) existia comorbilidad que precisaba una dieta baja o ausente de sodio. Solo el 46,5% (IC95%: 41,5-51,5) tenia una recomendacion de dieta baja en sal. Cabe resaltar que el 50,5% (IC95%: 45,5-55,5) de los pacientes presento la necesidad de dieta baja en sodio y sufria estrenimiento. Un 53,8% (IC95%: 48,7-58,7) de los pacientes tomaba laxantes (54% productos ricos en lactulosa o polietilenglicol [PEG] con electrolitos), el 52,1% debido a estrenimiento y el 42,3% como prevencion al tratamiento con opioides. Conclusiones: un alto porcentaje de la poblacion estudiada (87%) padece algun trastorno que requiere la limitacion de sodio en su dieta y al menos la mitad presenta estrenimiento. El uso de laxantes, como tratamiento o como prevencion del estrenimiento, es frecuente en los pacientes paliativos. Por tanto, la eleccion de un laxante sin sodio sera preferible en este tipo de pacientes. EnglishBackground: palliative patients usually have diseases that require a restriction of dietary sodium, although the prevalence of this requirement is unknown. Such conditions, combined with constipation, may mean that the use of laxatives with electrolytes should be avoided. Objectives: to ascertain the prevalence of the need to restrict sodium intake in palliative patients and to analyze the prevalence of constipation and the use of laxatives, including those containing sodium. Method: this was a multicenter retrospective, descriptive, cross-sectional, epidemiological study of both inpatients and outpatients over 18 years of age treated at the palliative care clinic (June 2015-March 2016). Demographic and anthropometric characteristics, diseases associated with dietary sodium restriction and treatments administered were recorded. Results: the study sample consisted of 400 palliative patients, with a mean age of 77.8 ± 13.0 years and 52.2% were male. Of these, 68.3% were inpatients and 31.8% were outpatients. Comorbidities requiring low sodium or a sodium-free diet were found in 87.0% (95% CI: 83.3-90.0) of cases. Only 46.5% (95% CI: 41.5-51.5) of patients had been prescribed a low salt diet. It should be noted that 50.5% (95% CI: 45.5-55.5) of patients required a low sodium diet and suffered from constipation. Laxatives (polyethylene glycol or lactulose-rich products [PEG] with electrolytes in 54% of cases) were taken by 53.8% (95% CI: 48.7-58.7) of patients, 52.1% due to constipation and 42.3% as a prevention due to opioid treatment. Conclusions: a high proportion of the study cohort (87%) had some condition that required dietary sodium restriction and at least half the patients had constipation. The use of laxatives to treat or prevent constipation is common in palliative patients. A sodium-free laxative is therefore preferred in these patientsBACKGROUND palliative patients usually have diseases that require a restriction of dietary sodium, although the prevalence of this requirement is unknown. Such conditions, combined with constipation, may mean that the use of laxatives with electrolytes should be avoided. OBJECTIVES to ascertain the prevalence of the need to restrict sodium intake in palliative patients and to analyze the prevalence of constipation and the use of laxatives, including those containing sodium. METHOD this was a multicenter retrospective, descriptive, cross-sectional, epidemiological study of both inpatients and outpatients over 18 years of age treated at the palliative care clinic (June 2015-March 2016). Demographic and anthropometric characteristics, diseases associated with dietary sodium restriction and treatments administered were recorded. RESULTS the study sample consisted of 400 palliative patients, with a mean age of 77.8 ± 13.0 years and 52.2% were male. Of these, 68.3% were inpatients and 31.8% were outpatients. Comorbidities requiring low sodium or a sodium-free diet were found in 87.0% (95% CI: 83.3-90.0) of cases. Only 46.5% (95% CI: 41.5-51.5) of patients had been prescribed a low salt diet. It should be noted that 50.5% (95% CI: 45.5-55.5) of patients required a low sodium diet and suffered from constipation. Laxatives (polyethylene glycol or lactulose-rich products [PEG] with electrolytes in 54% of cases) were taken by 53.8% (95% CI: 48.7-58.7) of patients, 52.1% due to constipation and 42.3% as a prevention due to opioid treatment. CONCLUSIONS a high proportion of the study cohort (87%) had some condition that required dietary sodium restriction and at least half the patients had constipation. The use of laxatives to treat or prevent constipation is common in palliative patients. A sodium-free laxative is therefore preferred in these patients.