Sistemática de cálculo de reactores

Se han usado las ecuaciones de cambio con dos objetivos: 1. Mostrar analogía entre distintas formas de proceso. 2. Mostrar la reducción a casos particulares de dichas ecuaciones para diseño isotérmico sin expansión. Se han considerado todos los estaños posibles del reactor: transitorio, transitorio ya lleno y estacionario, con y sin reciclo.Equations of change have been employed to show: 1. Analogies between different ways of processing. 2. Simplified expressions to be used in isothermal design of reactors without expansion. All possible cases have been considered: transient, full reactor transient and stationary, with and without recycle

Transferencia de masa en sistemas líquido-gas (fase líquida) y su aplicación al diseño de columnas rellenas

Fil: Bernardi, Alfredo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Development of environmentally friendly composite matrices from epoxidized cottonseed oil

The continuous rise in oil prices has led to the use of other ways to obtain polymer materials. This paper proposes a methodology to obtain a thermosetting resin from cottonseed oil by epoxidation process. The cottonseed oil contains as most representative fatty acids: 52.5% of linoleic acid (C18: 2), 23.9% of palmitic acid (C16: 0) and 17.6% of oleic acid (C18: 1); the real iodine index, which is indicative of the number of double bonds, has a value of 107. Epoxidized cottonseed oil (ECSO) has been successfully obtained using conventional epoxidation process with hydrogen peroxide, acetic acid and sulfuric acid, maintaining a constant temperature of 70 °C with homogeneous magnetic stirring. Average oxirane oxygen content (OOC) of 5.32% can be obtained by conventional epoxidation process which represents a yield over 83%. The epoxidized oil has been crosslinked with mixtures of two cyclic anhydrides to tailor different properties on final crosslinked thermosetting resins: on the one hand, methyl nadic anhydride (MNA) which is characterized by a rigid molecular structure and on the other hand, dodecenylsuccinic anhydride (DDSA) with a long side chain that can confer flexibility. The crosslinking process has been followed by dynamic differential scanning calorimetry (DSC), ionic mobility and oscillatory rheometry (OR) as well as gel time determination. The effect of the hardener mixture (wt.% DDSA:MNA) on mechanical performance of cured materials has been followed by flexural and impact tests as well as the evolution of the storage modulus (G′) by dynamic mechanical analysis (DMA) in torsion mode. By selecting the appropriate hardener mixture, it is possible to obtain crosslinked materials with different properties ranging from stiff matrices for ECSO crosslinked with MNA to flexible matrices for ECSO cured with DDSA. This has occurred with other thermosetting resins like epoxidized soy bean oil (ESBO) or epoxidized linseed oil (ELO). (C) 2014 Elsevier Ltd. All rights reserved.Authors thank Conselleria d'Educacio, Cultura i Esport (Generalitat Valenciana) Ref: GV/2014/008 for financial support.Carbonell Verdú, A.; Bernardi, L.; García García, D.; Sánchez Nacher, L.; Balart Gimeno, RA. (2015). Development of environmentally friendly composite matrices from epoxidized cottonseed oil. European Polymer Journal. 63:1-10. doi:10.1016/j.eurpolymj.2014.11.043S1106

Microfracture versus microfracture and platelet-rich plasma: arthroscopic treatment of knee chondral lesions. A two-year follow-up study.

Purpose: the aim of this study was to describe and compare the clinical results obtained in patients affected by chondral lesions of the knee submitted to an arthroscopic treatment with the microfracture technique or microfracture + intraoperative autologous platelet-rich plasma (PRP) injection. Methods: a prospective observational study was performed in patients affected by chondral lesions of the knee (classed as grade III-IV according to Outer-bridge's classification) and early osteoarthritis (classed as grade 1-2 according to the Kellgren-Lawrence classification). Their mean age was 52.4 years. Thirteen patients were treated with the microfracture technique according to Steadman (Group A), while 14 were treated with microfracture + PRP injection (Group B). Both groups were assessed using series of measures (a visual analog scale for pain, the 36-Item Short Form Health Survey and the International Knee Documentation Committee Subjective Knee Form) to compare pre-operative and postoperative values at 3, 6, 12 and 24 months. Statistical analysis was conducted using a two-factor ANOVA for repeated measures. Results: the VAS score decreased from a pre-operative value of 6.62±1.26 to 3.54 ±2.26 at 24 months in Group A (p<0.001), and from 6.43±1.91 to 3.36±2.84 in Group B (p<0.001). The IKDC subjective score increased from a pre-operative value of 37.02±12.00 to 62.13±19.00 at two years in Group A (p<0.001) and from 34.63±15.00 to 67.11±26.74 in Group B (p<0.001); the SF-36 scores showed a similar trend. Although an improvement was recorded over time in both groups, in the short term the IKDC subjective score improvement seemed to be better in Group B; a similar trend was shown by the SF-36 and VAS scores. At two years, the IKDC Subjective Scale, VAS and SF-36 scores seemed to be similar in the two groups. Over time, no significant differences were found between the two groups in any of the three outcomes. Conclusions: the use of autologous PRP in association with the microfracture technique seems to give better clinical and functional results in short-term follow-up, above all as regards pain. At two-year follow-up, however, the clinical results of the two groups were similar. Level of evidence: Level II, prospective cohort study

A broadened scope for the use of hydrazones as neutral nucleophiles in the presence of H-bonding organocatalysts

Using thioureas as H-bonding organocatalysts, nitroalkenes can be activated for the conjugate addition of hydrazones as neutral nucleophiles. Formaldehyde derivatives react at the azomethine carbon as expected, whereas hydrazones from enolizable aldehydes behave as ene-hydrazines and react at the α-carbon instead. Ionic liquids were found to decrease the reaction times considerably compared to commonly used solvents, whereas alternative activation by Lewis acids resulted in decomposition of reactants

Efficacy and safety of a double-coated paclitaxel-eluting coronary stent: The EUCATAX trial

Objectives: The aim of this study was the comparison of a new double-coated paclitaxel-eluting coronary stent with bare-metal stent (BMS) in patients undergoing percutaneous coronary intervention. Background: Stent coating with biodegradable polymers as a platform for elution of drugs has the potential for complete elution of drugs and for decreasing the risk of late complications. Methods: Multicenter randomized trial comparing a paclitaxel-eluting stent (PES) coated with a biodegradable polymer and glycocalyx with the equivalent BMS. We randomly assigned 422 patients with de novo coronary lesions to PES (211 patients) or to BMS (211 patients). Primary end point was target vessel failure (TVF) defined as cardiac death, myocardial infarction, and target vessel revascularization. Clinical secondary end points were target vessel revascularization, target lesion revascularization, stent thrombosis (ST), and major adverse cardiovascular events (MACE). Angiographic secondary end points were late loss and binary restenosis. Results: At 1 year of follow-up, TVF rate was 9.5% in the PES group and 17.1% in the BMS group (P = 0.02), and MACE rate was 10% in PES and 19% in BMS arm (P = 0.009). All other secondary end points were reached but ST. ST rate was low and similar in both study arms. Conclusions: The study shows that patients treated with PES with dual coating technology had significantly lower incidence of TVF and MACE than those treated with BMS design; however, longer follow-up should be necessary to assess true advantages of this technology compared with the previous one.Fil: Rodriguez, Alfredo E.. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Vigo, Cesar F.. Sanatorio del Salvador S. A.; ArgentinaFil: Delacasa, Alejandro. Sanatorio Belgrano; ArgentinaFil: Mieres, Juan. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Fernandez Pereira, Carlos. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Bernardi, Victor. Clinica del Sol;Fil: Bettinoti, Marcelo. Sanatorio Guemes Sociedad Anonima.; ArgentinaFil: Rodriguez Granillo, Gaston Alfredo. Sanatorio "Otamendi y Miroli S.A.". Servicio de Diagnóstico por Imágenes. Departamento de Imágenes en Cardiología. Centro de Investigaciones Cardiovasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Curotto, Valeria. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Rubilar, Bibiana. Sanatorio "Otamendi y Miroli S. A."; ArgentinaFil: Tronge, Jorge. No especifíca;Fil: Palacios, Igor F.. Massachusetts General Hospital; Estados UnidosFil: Antoniucci, David. Careggi Hospital; Itali

Optimal coronary balloon angioplasty with provisional stenting versus primary stent (OCBAS) Immediate and long-term follow-up results

AbstractObjective. This study sought to compare two strategies of revascularization in patients obtaining a good immediate angiographic result after percutaneous transluminal coronary angioplasty (PTCA): elective stenting versus optimal PTCA. A good immediate angiographic result with provisional stenting was considered to occur only if early loss in minimal luminal diameter (MLD) was documented at 30 min post-PTCA angiography.Background. Coronary stenting reduces restenosis in lesions exhibiting early deterioration (>0.3 mm) in MLD within the first 24 hours (early loss) after successful PTCA. Lesions with no early loss after PTCA have a low restenosis rate.Methods. To compare angiographic restenosis and target vessel revascularization (TVR) of lesions treated with coronary stenting versus those treated with optimal PTCA, 116 patients were randomized to stent (n = 57) or to optimal PTCA (n = 59). After randomization in the PTCA group, 13.5% of the patients crossed over to stent due to early loss (provisional stenting).Results. Baseline demographic and angiographic characteristics were similar in both groups of patients. At 7.6 months, 96.6% of the entire population had a follow-up angiographic study: 98.2% in the stent and 94.9% in the PTCA group. Immediate and follow-up angiographic data showed that acute gain was significantly higher in the stent than in the PTCA group (1.95 vs. 1.5 mm; p < 0.03). However, late loss was significantly higher in the stent than the PTCA group (0.63 ± 0.59 vs. 0.26 ± 0.44, respectively; p = 0.01). Hence, net gain with both techniques was similar (1.32 ± 0.3 vs. 1.24 ± 0.29 mm for the stent and the PTCA groups, respectively; p = NS). Angiographic restenosis rate at follow-up (19.2% in stent vs. 16.4% in PTCA; p = NS) and TVR (17.5% in stent vs. 13.5% in PTCA; p = NS) were similar. Furthermore, event-free survival was 80.8% in the stent versus 83.1% in the PTCA group (p = NS). Overall costs (hospital and follow-up) were US $591,740 in the stent versus US$398,480 in the PTCA group (p < 0.02).Conclusions. The strategy of PTCA with delay angiogram and provisional stent if early loss occurs had similar restenosis rate and TVR, but lower cost than primary stenting after PTCA

Densidade de plantas em variedades de polinização aberta de milho

Information about the plant density that optimizes grain yield of maize open-pollinated varieties (OPV), especially in agro-ecological systems, is reduced. The aim of this work was to evaluate the effect of plant density on maize OPV yield. Two experiments were conducted in Papanduva, SC, Brazil, during the growing seasons of 2004/05 and 2005/06. Treatments were arranged in a completely randomized design, using a factorial scheme (4x4), with three replicates. Four maize genotypes were evaluated, three OPV (SCS 153-Esperança, MPA 01 and Pixurum 06); and one hybrid (AS-1544 in the first season and AS- 3601 in the second season). These genotypes were grown in four plant densities: 25,000; 40,000; 55,000; and 70,000 plants ha-1. Plant height, stalk diameter, plant lodging and stalk breakage, grain yield and its components (ears number per plant, grains number per ear and grain mass) were evaluated. The plant densities that optimized maize OPV grain yield ranged from 45,000 to 55,000 plants ha-1.Informações sobre densidades de plantas que maximizem a produtividade de grãos em variedades de polinização aberta (VPA) de milho, especialmente quando cultivadas em sistemas agroecológicos de produção, são escassas. O objetivo deste trabalho foi avaliar a produtividade de grãos em VPA de milho cultivadas em diferentes densidades de plantas sob sistema agroecológico. Foram conduzidos experimentos nas safras 2004/05 e 2005/06, no município de Papanduva, SC. Os tratamentos foram dispostos segundo o delineamento experimental inteiramente casualizado, em esquema fatorial (4x4), com três repetições. Quatro genótipos de milho foram avaliados, sendo três VPA (SCS 153-Esperança, MPA 01 e Pixurum 06); e um híbrido (AS-1544 na primeira safra e AS-3601 na segunda safra). Os genótipos foram cultivados em quatro densidades de plantas: 25.000, 40.000, 55.000 e 70.000 plantas ha-1. Avaliaram-se a estatura de plantas, o diâmetro do colmo, as percentagens de acamamento e quebra do colmo, a produtividade de grãos e os componentes de rendimento (número de espigas por planta, número de grãos por espiga e massa do grão). Concluiu-se que a faixa de densidade de plantas que maximiza a produtividade de grãos em VPA varia de 45.000 a 55.000 plantas ha-1

“Sobre llovido, mojado”. Problems, strategies, and demands of the Argentine popular, social, and solidarity economy during the pandemic

The emergency caused by the COVID-19 pandemic reactivated numerous debates on the social protections required for distinct labor groups and the need to guarantee work and income for the population. This article focuses on the experiences of people who work without ties to an employer and who self-identify as part of the popular, social, and solidarity economy (EPSS) in Argentina. It aims to contribute to the academic debate by identifying the conditions that favored the sustainability and organization of their work beyond the context of the emergency. In particular, we seek to examine whether the situation opened up by the pandemic led to new processes of recognition, institutionalization, and protection for these labor groups or not. A qualitative research process was developed based on interviews with representatives of 14 organizations of EPSS of Greater Rosario (primary sources) and the review of emergency measures and programs implemented by the three levels of government – national, provincial, and local – beginning with the declaration of the health emergency until December 2021 (secondary sources). In the final reflections, the main results are highlighted, positing that the state’s responses did not give rise to new institutions, rights, and protections, but rather “organized” and “administered” the institutionality that already existed

Five-year follow-up of children with perinatal HIV-1 infection receiving early highly active antiretroviral therapy

<p>Abstract</p> <p>Background</p> <p>Early highly active antiretroviral therapy (HAART), started within the first months of age, has been proven to be the optimal strategy to prevent immunological and clinical deterioration in perinatally HIV-infected children. Nevertheless, data about long-term follow-up of early treated children are lacking.</p> <p>Methods</p> <p>We report data from 40 perinatally HIV-infected-children receiving early HAART, with a median follow-up period of 5.96 years (interquartile range [IQR]:4.21–7.62). Children were enrolled at birth in the Italian Register for HIV Infection in Children. Comparison with 91 infected children born in the same period, followed-up from birth, and receiving deferred treatment was also provided.</p> <p>Results</p> <p>Nineteen children (47.5%) were still receiving their first HAART regimen at last follow-up. In the remaining children the first regimen was discontinued, after a median period of 3.77 years (IQR: 1.71–5.71) because of viral failure (8 cases), liver toxicity (1 case), structured therapy interruption (3 cases), or simplification/switch to a PI-sparing regimen (9 cases). Thirty-nine (97.5%) children showed CD4⁺T-lymphocyte values>25%, and undetectable viral load was reached in 31 (77.5%) children at last visit. Early treated children displayed significantly lower viral load than not-early treated children, until 6 years of age, and higher median CD4⁺T-lymphocyte percentages until 4 years of age. Twenty-seven (29.7%) not-early treated vs. 0/40 early treated children were in clinical category C at last follow-up (P < 0.0001).</p> <p>Conclusion</p> <p>Our findings suggest that clinical, virologic and immunological advantages from early-HAART are long-lasting. Recommendations indicating the long-term management of early treated children are needed.</p