Estudio del diseño del proceso de producción de ácido sulfúrico mediante el modelado

El ácido sulfúrico, de fórmula H2SO4, es uno de los productos químicos más producidos del mundo. Se genera a partir de trióxido de azufre (SO3), que se obtiene a su vez en un horno en el que se quema azufre elemental (S) para obtener dióxido de azufre (SO2). Este dióxido de azufre se introduce en un reactor catalítico de 5 lechos, en cuyo interior se oxida a trióxido de azufre. Las etapas de este reactor se han modelado rigurosamente, mediante la introducción de la cinética de la reacción en un modelo integrado de la planta en ASPEN Plus, que considera la pérdida de carga en los lechos, la cantidad de catalizador y el tamaño de la etapa en sí. Debido a que el proceso de producción más usado es el de doble contacto, se ha tenido también en cuenta el efecto de una absorción intermedia, entre la cuarta y la quinta etapa de reacción. Adicionalmente, como el proceso genera una gran cantidad de energía que se aprovecha parcialmente dentro del mismo proceso, es necesario considerar la integración energética entre corrientes también. El objetivo principal de este trabajo es emplear una herramienta de simulación de procesos, como es ASPEN Plus, para simular el proceso de producción del ácido sulfúrico, un proceso de producción muy importante en la industria, e intentar explicar mediante el estudio detallado del proceso y la simulación de este las condiciones de operación empleadas cuando se lleva a cabo industrialmente. Para conseguir este objetivo se llevarán a cabo las siguientes tareas: - Explicar el proceso de producción que se va a considerar en el modelado - Obtener el diagrama de equilibrio conversión-temperatura de la reacción para o las condiciones de entrada del reactor o las condiciones tras la absorción intermedia - Desarrollar un modelo mediante ASPEN Plus que incluya: o El tamaño del reactor multilecho o La cinética de la reacción o La forma y tamaño de las partículas de catalizador o El efecto de los absorbedores Para finalizar, se determina la relación entre la cantidad de catalizador y la conversión para diferentes modelos cinéticos de la oxidación del SO2, y se compara la cantidad necesaria de catalizador para obtener la conversión deseada en la primera etapa, calculada teóricamente, con la cantidad real usada en plantas industriales.Sulfuric acid, whose formula is H2SO4, is one of the most produced chemicals in the world. It is generated from sulfur trioxide (SO3), that is obtained in a furnace in which elemental sulfur (S) is burned to obtain sulfur dioxide (SO2). This sulfur dioxide is fed into a 5-bed catalytic reactor, where it is oxidized to sulfur trioxide. The stages of this reactor have been rigorously modeled by incorporating detailed reaction kinetics in an integrated model of the plant in ASPEN Plus, which considers the pressure drop in the beds, the amount of catalyst and the size of each stage. Because the most common production process is the double contact process, the effect of an intermediate absorption, between the fourth and fifth reactor stage, has also been taken into account. In addition, as the process generates a large amount of energy which is partially used within the process itself, it is necessary to consider the energy integration between streams as well. The main objective of this work is to use a process simulation tool, such as ASPEN Plus, to simulate the sulfuric acid production process, a very important production process in the industry, and to try to explain, by means of a detailed study of the process and its simulation, the operating conditions used when it is carried out industrially. To achieve this goal, the following tasks will be conducted: - To explain the production process to be considered in the modeling. - To obtain the conversion-temperature equilibrium diagram of the reaction for: o the reactor inlet conditions o the conditions after intermediate absorption - To develop a model using ASPEN Plus that includes: o The size of the multi-tube reactor o Reaction kinetics o Catalyst particle shape and size o The effect of the absorbers Finally, the relationship between the amount of catalyst and conversion for different kinetic models of SO2 oxidation is determined, and the calculated amount of catalyst needed to obtain the desired conversion in the first stage is compared with the actual amount used in industrial plants.Universidad de Sevilla. Grado en Ingeniería Químic

NIMESULIDE: DISSOLUTION PROFILE, VALIDATION OF ANALYTICAL METHODS FOR CAPSULES, AND ASSESSMENT OF PRODUCT QUALITY

Objective: The main objective of this paper was to evaluate the quality of similar (S, n=3) and generic (G, n=3) tablets and compounding capsules (C, n=6) containing nimesulide (100 mg).Methods: The parameters investigated (weight, nimesulide content, uniformity of dosage units, disintegration, friability and hardness (tablets) and dissolution profile) were evaluated against the Brazilian Pharmacopeia and a reference compound (for tablets). Nimesulide content, determined by a UV/visible spectrophotometric method, and dissolution test were validated for compounding capsules.Results: All formulations had a mean weight coefficient of variation lower than 5%. Three compounding formulations contained less than 95 mg nimesulide, with C1 (88.5 mg) also showing a lack of dosage unit uniformity. Disintegration times were lower than 5 min for all samples and friability less than 0.5% for all tablet formulations. The hardness of the reference product (25.5N) was lower compared to the other tablet samples (30-80.3N). All tablet formulations reached 75% release after 5 min of the dissolution test, but none of the compounding formulations reached the minimum 75% release after 45 min, probably due to inadequate excipient composition and amount. On average, excipient accounted for 46.3% of the capsule weight (against 74% in tablets), and some of the products did not contain water-soluble substances to promote dissolution.Conclusion: The results of this study indicate a lack of quality in compounding nimesulide products, which could jeopardize patients' health and treatment.Â

Thermal performance of ligth multi-layered facades

Traditional façade systems are at the point where the minimum comfort guarantees have peaked, showing hygrothermic performance deficiencies which result in higher heating consumption, which is why it´s necessary to make improvements in design and building construction, especially in envelopes, for which efficient building enclosures should be used, generating notable benefits. For these reasons, the study of new façade construction systems is essential, particularly light multi-layers, which offer favorable characteristics for energy consumption savings. With this background, the main aim of this study is to generate knowledge to find out to what extent light multi-layered façades are better, determining which façades are the most efficient and guarantee the comfort conditions of a building, contributing in this way to energy consumption savings. To carry out this study, a methodology of analysis shall be used, signifying that in the first phase a theoretical study has been made, analyzing different configurations of the sample façades, to obtain their thermal performance, using two different methods, thermographic and thermal, obtaining in the thermographic study: surface temperatures of the façades, while in the thermal simulation, generating isotherms, heat flows, data on thermal coupling coefficients to calculate the value of the thermal transmittance and surface conditions, among others. Therefore, using this data, the conclusion has been reached that comparing a traditional enclosure to a light multi-layered one of equal thickness, an improvement of 65% can be achieved in the thermal transmittance, which signifies a saving in energy consumption, exceeding the Technical Building Code

Cerramientos multicapas ligeros en el concurso solar Decathlon 2007

El constante crecimiento de consumo energético en todos los sectores, siendo el caso particular el de las edificaciones que consumen una tercera parte del consumo total. Todo ello surge como consecuencia del crecimiento económico y del aumento de las exigencias de las condiciones de confort, además de utilizar energías fósiles. Si se estudia el consumo energético en las edificaciones, se puede ver que el mayor consumo se genera en climatización con un 46%, luego el agua caliente con 21%, electrodomésticos 16%, cocina 10% e iluminación 7%. Desde la década de los setenta, ha surgido una creciente demanda social por un crecimiento sostenible, originado por una parte por la crisis energética iniciada con el conflicto de Medio Oriente y por otra parte por un cada vez mayor y mejor análisis de la repercusión en el ambiente de nuestras actividades. Esto ha llevado a actuaciones de ámbito mundial como son: El Protocolo de Montreal, AGENDA 21, propone el desarrollo de las energías renovables, disminuir los impactos sobre la salud y el medio ambiente de la producción y consumo de energía y el fomento de una educación hacia el desarrollo sostenible. El Programa 21 de la ONU, plantea el control de aquellas substancias que producen el agotamiento de la capa de ozono. El Protocolo de Kyoto, cuyo objetivo es la disminución de las emisiones de Gases de Efecto Invernadero, en especial del CO2. Dando respuesta a estas actuaciones mundiales la Unión Europea ha desarrollado normativas, tendentes a la mejora de la eficiencia energética y a la seguridad y diversificación de los suministros. Así ha desarrollado: La Directiva 93/76 de 13.09.93 (SAVE), El Libro Verde, La Directiva 2002/91. En España las actuaciones se han presentado con: Código Técnico de la Edificación, Documento Básico “Ahorro de Energía” y Real Decreto 47/2007, por el que se aprueba el procedimiento básico para la certificación de eficiencia energética de edificios. Este certificado deberá incluir información objetiva sobre las características energéticas de los edificios de forma que se pueda valorar y comparar su eficiencia energética, con el fin de favorecer la promoción de edificios de alta eficiencia energética y las inversiones en ahorro de energía. Como respuesta a toda esta serie de normativas para la mejora del consumo energético se tiene, por un lado es el empleo de las energías renovables, como la solar fotovoltaica, solar térmica, eólica, hidráulica, biomasa, geotérmica,… y por otro mejorar el diseño y construcción de los edificios usando cerramientos eficientes, como los multicapa y aún mejor los multicapa ligeros, ya que generan mejores prestaciones en término de confort y ahorro energético

Dual targeted therapy in patients with psoriatic arthritis and spondyloarthritis: a real-world multicenter experience from Spain

Dual targeted therapy (DTT) has emerged as a promising approach in patients with refractory spondyloarthritis (SpA) or psoriatic arthritis (PsA) and extra-musculoskeletal manifestations of both diseases, but its effectiveness/safety ratio still remains unclear. This is a retrospective, real-world multicenter study in refractory SpA and PsA patients with simultaneous use of two biological or synthetic targeted agents. Effectiveness was assessed using Ankylosing Spondylitis Disease Activity Score with C-reactive protein (ASDAS-CRP) and Disease Activity in Psoriatic Arthritis (DAPSA) Score. We identified 39 different DTT combinations in 36 patients (22 SpA; 14 PsA), 25 of them with concomitant inflammatory bowel disease. The most commonly used combinations were TNF inhibitor plus antagonist of the IL12/23 pathway, followed by TNF inhibitor plus IL-17 antagonist. During a median exposure of 14.86 months (IQR 8-20.2), DTT retention rate was 69.4% (n=25/36; 19 SpA, 6 PsA). Major clinical improvement (change in ASDAS-CRP > 2 or improvement > 85% in DAPSA) was achieved in 69.4% of patients (n=25/36 therapeutical combinations; 17/21 SpA, 8/15 PsA), with a 58.3% (n=21/36 combinations; 15/20 SpA, 6/13 PsA) low-activity/remission rate. Of the patients who were receiving glucocorticoids, 55% managed to withdraw them during follow-up. Interestingly, only four serious adverse events in three patients were observed, leading to DTT discontinuation

Maximal respiratory pressure reference equations in healthy adults and cut-off points for defining respiratory muscle weakness

[Abstract] Introduction: Maximal inspiratory and expiratory pressures (PImax/PEmax) reference equations obtained in healthy people are needed to correctly interpret respiratory muscle strength. Currently, no clear cut-off points defining respiratory muscle weakness are available. We aimed to establish sex-specific reference equations for PImax/PEmax in a large sample of healthy adults and to objectively determine cut-off points for respiratory muscle weakness. Methods: A multicentre cross-sectional study was conducted across 14 Spanish centres. Healthy non-smoking volunteers aged 18-80 years stratified by sex and age were recruited. PImax/PEmax were assessed using uniform methodology according to international standards. Multiple linear regressions were used to obtain reference equations. Cut-off points for respiratory muscle weakness were established by using T-scores. Results: The final sample consisted of 610 subjects (314 females; 48 [standard deviation, SD: 17] years). Reference equations for PImax/PEmax included body mass index and a squared term of the age as independent variables for both sexes (p<0.01). Cut-off points for respiratory muscle weakness based on T-scores ≥2.5 SD below the peak mean value achieved at a young age were: 62 and 83cmH2O for PImax and 81 and 109cmH2O for PEmax in females and males, respectively. Conclusion: These reference values, based on the largest dataset collected in a European population to date using uniform methodology, help identify cut-off points for respiratory muscle weakness in females and males. These data will help to better identify the presence of respiratory muscle weakness and to determine indications for interventions to improve respiratory muscle function

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Association Between Preexisting Versus Newly Identified Atrial Fibrillation and Outcomes of Patients With Acute Pulmonary Embolism

Background Atrial fibrillation (AF) may exist before or occur early in the course of pulmonary embolism (PE). We determined the PE outcomes based on the presence and timing of AF. Methods and Results Using the data from a multicenter PE registry, we identified 3 groups: (1) those with preexisting AF, (2) patients with new AF within 2 days from acute PE (incident AF), and (3) patients without AF. We assessed the 90-day and 1-year risk of mortality and stroke in patients with AF, compared with those without AF (reference group). Among 16 497 patients with PE, 792 had preexisting AF. These patients had increased odds of 90-day all-cause (odds ratio [OR], 2.81; 95% CI, 2.33-3.38) and PE-related mortality (OR, 2.38; 95% CI, 1.37-4.14) and increased 1-year hazard for ischemic stroke (hazard ratio, 5.48; 95% CI, 3.10-9.69) compared with those without AF. After multivariable adjustment, preexisting AF was associated with significantly increased odds of all-cause mortality (OR, 1.91; 95% CI, 1.57-2.32) but not PE-related mortality (OR, 1.50; 95% CI, 0.85-2.66). Among 16 497 patients with PE, 445 developed new incident AF within 2 days of acute PE. Incident AF was associated with increased odds of 90-day all-cause (OR, 2.28; 95% CI, 1.75-2.97) and PE-related (OR, 3.64; 95% CI, 2.01-6.59) mortality but not stroke. Findings were similar in multivariable analyses. Conclusions In patients with acute symptomatic PE, both preexisting AF and incident AF predict adverse clinical outcomes. The type of adverse outcomes may differ depending on the timing of AF onset.info:eu-repo/semantics/publishedVersio

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic