CFD Analysis of Turbulence Models to Achieve the Digester Mixing Process

Mixing efficiency defines the features of physicochemical and biological reactions carried out in reactors or digesters. The reason for this influence is because it conditions the heat and mass transfer. That is why the mixing level and intensity become important aspects to study to know the effects they have on the processes. Furthermore, it should be noted that most of the mixing processes are carried out under turbulent conditions. Mixing enhancement evaluation is achieved in two ways, that is, experimentally and performing simulations. Simulations are based on numerical methods approximating solutions to results in line with reality. In this context, turbulence models applied in systems have great influence on the final numerical solution and, therefore, on the interpretation of improved mixing in reactors. It is also necessary to consider the influence of rheology in these simulations, since the working fluid does not always have a linear stress-strain relationship. In this way, an analysis of turbulence models and their applications in mixing characterization and the adequacy of these models to the reactor configuration and operating conditions is carried out. Mention is also made of the experiences around the study of turbulence in mixing tanks

Postharvest respiration of fruits and environmental factors interaction: An approach by dynamic regression models

The respiratory metabolism of fruits is affected by multiple internal (product) and external (environmental) factors that often interact with each other. Among the external factors that have the greatest influence on respiration are temperature, air composition, moisture content and illumination. The aim of this paper is to elucidate the influence of environmental factors on the respiration rate of peach fruits based on transfer models obtained by dynamic regression modelling (ARIMAX). The fitted ARIMA models met the criteria of parsimony and white noise in residuals. The estimated coefficients of each model were statistically significant under the Durbin-Watson (DW), Akaike (AIC) and Schwarz (SBC) criteria. Transfer functions revealed 0.15% and 1.9% increase, and 0.001% decrease in the respiration rate of the peach fruit for each unit of change in temperature, relative humidity and illumination of the storage environment, respectively. The respiration rate response took place 1-8 minutes after the change in environmental variables had occurred. It was concluded that the dynamic regression modelling is reliable for predicting the physiological response of fruits the effect of external factors imposed continuously during postharvest handling

Historia de una biblioteca viva en una escuela rural. Un relato etnográfico

Este artículo tiene el propósito de aportar conocimiento sobre la construcción social de las bibliotecas escolares en contextos rurales, sus usos pedagógicos y su potencial formativo. Se documenta una experiencia que entrelaza el currículum con la comunidad educativa, significada en la diversidad de un grupo multigrado y su entorno familiar y social. Se trata de un relato etnográfico sobre las posibilidades educativas de una biblioteca en una escuela rural mexicana, donde niños y niñas de distintas edades conviven y comparten historias que la maestra lee en voz alta, con el anhelo de sembrar el gusto por la lectura y la escritura en sus mentes y corazones infantiles. A pesar de carencias y abandonos, la escuela logra tener un rico acervo que los alumnos clasifican, cuidan y usan en beneficio propio. Se convierten en guardianes de los libros y las enseñanzas que esconden sus páginas. La biblioteca constituye un espacio cultural que genera posibilidades de intercambio y apertura al mundo para los alumnos y sus familias. Y sin duda ofrece alas para quienes emprenden el viaje del placer literario. El relato se basa en una investigación etnográfica sobre la diversidad de recursos pedagógicos que circulan en escuelas multigrado ubicadas en territorios rurales

Biodrying under Greenhouse Conditions as Pretreatment for Horticultural Waste

The biodrying process was studied as an alternative technology to reduce the mass and volume of horticultural waste. Four static piles were prepared inside a greenhouse: two containing whole waste and two consisting of shredded waste. All the piles were compared with a test pile containing whole waste and placed outside the greenhouse. In two cases, ventilation ducts were installed to improve aeration. Each greenhouse was 2.0 m wide, 3.5 m long and 1.16 m high. The air temperature and relative humidity were monitored both inside and outside the greenhouse. Mass, humidity, organic matter and total nitrogen in the waste were measured. Piles inside the greenhouse showed decreases of 80% and 75% in weight and volume, respectively, during the first 16 days. The data obtained in this work suggest that biodrying could improve the handling and transport of horticultural waste while also minimizing the impact of pollutants

Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.

Historia de una biblioteca viva en una escuela rural. Un relato etnográfico

Este artículo tiene el propósito de aportar conocimiento sobre la construcción social de las bibliotecas escolares en contextos rurales, sus usos pedagógicos y su potencial formativo. Se documenta una experiencia que entrelaza el currículum con la comunidad educativa, significada en la diversidad de un grupo multigrado y su entorno familiar y social. Se trata de un relato etnográfico sobre las posibilidades educativas de una biblioteca en una escuela rural mexicana, donde niños y niñas de distintas edades conviven y comparten historias que la maestra lee en voz alta, con el anhelo de sembrar el gusto por la lectura y la escritura en sus mentes y corazones infantiles. A pesar de carencias y abandonos, la escuela logra tener un rico acervo que los alumnos clasifican, cuidan y usan en beneficio propio. Se convierten en guardianes de los libros y las enseñanzas que esconden sus páginas. La biblioteca constituye un espacio cultural que genera posibilidades de intercambio y apertura al mundo para los alumnos y sus familias. Y sin duda ofrece alas para quienes emprenden el viaje del placer literario. El relato se basa en una investigación etnográfica sobre la diversidad de recursos pedagógicos que circulan en escuelas multigrado ubicadas en territorios rurales