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

Consideraciones geométrico cinéticas sobre reacciones solido-fluido

En este trabajo se muestra que, partiendo de un tratamiento cinético para la reacción entre un sólido poroso y un fluido, el orden de reacción aparente con respecto al sólido debe ser menor que uno. Esto a su vez implica otra conclusión de naturaleza exclusivamente geométrica acerca de la estructura porosa del reactivo sólido. Esta conclusión expresa que la superficie por unidad de volumen hecha adimensional tiene que ser mayor que la concentración adimensional del sólido, tomándose como condición de referencia para adimensionalizar a la del estado inicial.It is shown in this paper that from the kinetic treatment for a reaction between a fluid and a porous solid it can he concluded that the apparent order of reaction for the solid ought to he less than one. This in turn implies another conclusion of a purely geometric nature about the porous structure of the solid rèactant; this conclusion says that the dimensionless surface area of solid reactant per unit volume ought to he greater than the dimensionless concentration of that solid, the reference condition being those of the initial ones

Criterios para la optimización de pastillas de catalizador

Se estudia la optimización de pastillas de catalizador para las zonas de factor de efectividad igual a uno y asintótico y para regímenes laminar y turbulento. Se analiza la influencia de la presencia de orificios en la pastilla así como de su diámetro y relación longitud a diámetro sobre el costo total del proceso.Cost optimization of catalyst pellets is analyzed. Developments are made for effectiveness factor equal to one and in the asymptotic region and for laminar and turbulent regimes. Influence of cylindrical holes, pellet diameter and length to pellet diameter ratio upon total cost (pumping plus catalyst costs) are studied

Determinación de la cinética de descomposición térmica de alcoholes e hidrocarburos mediante un reactor pulso

Se estudió la cinética de descomposición térmica de alcoholes e hidrocarburos en un reactor capilar de oro isotérmico, mediante la técnica del pulso cromatográfico, en la que se reemplaza la columna cromatográfica por un reactor. Se determinaron energías de activación y orden de reacción para el n-decano, n-propanol, isopropanol y terbutanol, observándose que respondían a una cinética lineal en el rango de temperaturas y tiempos de residencia estudiados. Los valores de energías de activación encontrados permitirían argumentar un proceso catalítico debido a efectos de pared y a la presencia de vestigios de oxígeno.The thermal decomposition kimetics of alcohols and hidrocarbors was studied in a gold, capilar, isothermal reactor applying the chromatographic pulse technique. This technique consists in the chromatographic column replacement by a reactor called "pulsed reactor"’. Reaction orders and activation energies were measured for n-decane, n-propanol, isopropanol and ten-butanol; it was observed reation kinetics were off first order within the experimental temperatures and residence times ranges. Activation energies values could be explained by a wall catalytic effect and the influence of oxygen traces. The chromatographic technique is very suitable for kinetic studies because of its versatility ard celerity

A protostellar system fed by a streamer of 10,500 au length

Binary formation is an important aspect of star formation. One possible route for close-in binary formation is disk fragmentation$^{[1,2,3]}$. Recent observations show small scale asymmetries (<300 au) around young protostars$^{[2,4]}$, although not always resolving the circumbinary disk, are linked to disk phenomena$^{[5,6]}$. In later stages, resolved circumbinary disk observations$^{[7]}$ (<200 au) show similar asymmetries, suggesting the origin of the asymmetries arises from binary-disk interactions$^{[8,9,10]}$. We observed one of the youngest systems to study the connection between disk and dense core. We find for the first time a bright and clear streamer in chemically fresh material (Carbon-chain species) that originates from outside the dense core (>10,500 au). This material connects the outer dense core with the region where asymmetries arise near disk scales. This new structure type, 10x larger than those seen near disk scales, suggests a different interpretation of previous observations: large-scale accretion flows funnel material down to disk scales. These results reveal the under-appreciated importance of the local environment on the formation and evolution of disks in early systems$^{[13,14]}$ and a possible initial condition for the formation of annular features in young disks$^{[15,16]}$.Comment: Published in Nature Astronomy on July 27th 2020. This is the authors' version before final edits, including methods section. Link to the NatAstro publication: https://www.nature.com/articles/s41550-020-1150-

Annotation and curation of human genomic variations: an ELIXIR Implementation Study

Background: ELIXIR is an intergovernmental organization, primarily based around European countries, established to host life science resources, including databases, software tools, training material and cloud storage for the scientific community under a single infrastructure. Methods: In 2018, ELIXIR commissioned an international survey on the usage of databases and tools for annotating and curating human genomic variants with the aim of improving ELIXIR resources. The 27-question survey was made available on-line between September and December 2018 to rank the importance and explore the usage and limitations of a wide range of databases and tools for annotating and curating human genomic variants, including resources specific for next generation sequencing, research into mitochondria and protein structure. Results: Eighteen countries participated in the survey and a total of 92 questionnaires were collected and analysed. Most respondents (89%, n=82) were from academia or a research environment. 51% (n=47) of respondents gave answers on behalf of a small research group (10 people). The survey showed that the scientific community considers several resources supported by ELIXIR crucial or very important. Moreover, it showed that the work done by ELIXIR is greatly valued. In particular, most respondents acknowledged the importance of key features and benefits promoted by ELIXIR, such as the verified scientific quality and maintenance of ELIXIR-approved resources. Conclusions ELIXIR is a "one-stop-shop" that helps researchers identify the most suitable, robust and well-maintained bioinformatics resources for delivering their research tasks

Meta-analysis of randomized trials: evaluation of benefit from gemcitabine-based combination chemotherapy applied in advanced pancreatic cancer

<p>Abstract</p> <p>Background</p> <p>Single-agent gemcitabine (GEM) is a standard treatment for advanced and metastatic pancreatic cancer. This study examines the question whether GEM-based combination chemotherapy can further improve treatment efficacy.</p> <p>Methods</p> <p>A meta-analysis was performed to evaluate randomized trials comparing GEM versus GEM+X (X = cytotoxic agent). Fifteen trials including 4465 patients were eligible for an analysis of overall survival, the primary end-point of this investigation.</p> <p>Results</p> <p>The meta-analysis revealed a significant survival benefit for GEM+X with a pooled hazard ratio (HR) of 0.91 (95% CI: 0.85 – 0.97, p = 0.004). The overall test for heterogeneity resulted in p = 0.82 (I²= 0%). The analysis of platinum-based combinations indicated a HR of 0.85 (95% CI: 0.76 – 0.96, p = 0.010), while for fluoropyrimidine-based combinations the HR was 0.90 (95% CI: 0.81 – 0.99, p = 0.030). No risk reduction was observed in the group of trials combining GEM with irinotecan, exatecan or pemetrexed (HR = 0.99). A meta-analysis of the trials with adequate information on baseline performance status (PS) was performed in five trials with 1682 patients. This analysis indicated that patients with a good PS had a marked survival benefit when receiving combination chemotherapy (HR = 0.76; 95% CI: 0.67 – 0.87; p < 0.0001). By contrast, application of combination chemotherapy to patients with an initially poor PS appeared to be ineffective (HR = 1.08; 95% CI: 0.90 – 1.29, p = 0.40).</p> <p>Conclusion</p> <p>The meta-analysis of randomized trials indicated a significant survival benefit when GEM was either combined with platinum analogs or fluoropyrimidines. Based on a preliminary subgroup analysis (representing 38% of all patients included in this meta-analysis), pancreatic cancer patients with a good PS appear to benefit from GEM-based cytotoxic combinations, whereas patients with a poor PS seem to have no survival benefit from combination chemotherapy.</p

Urocortin-1 within the Centrally-Projecting Edinger-Westphal Nucleus Is Critical for Ethanol Preference

Converging lines of evidence point to the involvement of neurons of the centrally projecting Edinger-Westphal nucleus (EWcp) containing the neuropeptide Urocortin-1 (Ucn1) in excessive ethanol (EtOH) intake and EtOH sensitivity. Here, we expanded these previous findings by using a continuous-access, two-bottle choice drinking paradigm (3%, 6%, and 10% EtOH vs. tap water) to compare EtOH intake and EtOH preference in Ucn1 genetic knockout (KO) and wild-type (WT) mice. Based on previous studies demonstrating that electrolytic lesion of the EWcp attenuated EtOH intake and preference in high-drinking C57BL/6J mice, we also set out to determine whether EWcp lesion would differentially alter EtOH consumption in Ucn1 KO and WT mice. Finally, we implemented well-established place conditioning procedures in KO and WT mice to determine whether Ucn1 and the corticotropin-releasing factor type-2 receptor (CRF-R2) were involved in the rewarding and aversive effects of EtOH (2 g/kg, i.p.). Results from these studies revealed that (1) genetic deletion of Ucn1 dampened EtOH preference only in mice with an intact EWcp, but not in mice that received lesion of the EWcp, (2) lesion of the EWcp dampened EtOH intake in Ucn1 KO and WT mice, but dampened EtOH preference only in WT mice expressing Ucn1, and (3) genetic deletion of Ucn1 or CRF-R2 abolished the conditioned rewarding effects of EtOH, but deletion of Ucn1 had no effect on the conditioned aversive effects of EtOH. The current findings provide strong support for the hypothesis that EWcp-Ucn1 neurons play an important role in EtOH intake, preference, and reward

Epidermal Growth Factor Receptor (EGFR) gene copy number (GCN) correlates with clinical activity of irinotecan-cetuximab in K-RAS wild-type colorectal cancer: a fluorescence in situ (FISH) and chromogenic in situ hybridization (CISH) analysis

<p>Abstract</p> <p>Background</p> <p>K-RAS wild type colorectal tumors show an improved response rate to anti-EGFR monoclonal antibodies. Nevertheless 70% to 40% of these patients still does not seem to benefit from this therapeutic approach. FISH EGFR GCN has been previously demonstrated to correlate with clinical outcome of colorectal cancer treated with anti-EGFR monoclonal antibodies. CISH also seemed able to provide accurate EGFR GCN information with the advantage of a simpler and reproducible technique involving immunohistochemistry and light microscopy. Based on these findings we investigated the correlation between both FISH and CISH EGFR GCN and clinical outcome in K-RAS wild-type colorectal cancer treated with irinotecan-cetuximab.</p> <p>Methods</p> <p>Patients with advanced K-RAS wild-type, colorectal cancer receiving irinotecan-cetuximab after failure of irinotecan-based chemotherapy were eligible.</p> <p>A cut-off value for EGFR GCN of 2.6 and 2.12 for FISH and CISH respectively was derived from ROC curve analysis.</p> <p>Results</p> <p>Forty-four patients were available for analysis. We observed a partial remission in 9 (60%) and 2 (9%) cases with a FISH EGFR GCN ≥ 2.6 and < 2.6 respectively (p = 0.002) and in 10 (36%) and 1 (6%) cases with a CISH EGFR GCN ≥ 2.12 and < 2.12 respectively (p = 0.03). Median TTP was 7.7 and 6.4 months in patients showing increased FISH and CISH EGFR GCN whereas it was 2.9 and 3.1 months in those with low FISH and CISH EGFR GCN (p = 0.04 and 0.02 respectively).</p> <p>Conclusion</p> <p>FISH and CISH EGFR GCN may both represent effective tools for a further patients selection in K-RAS wild-type colorectal cancer treated with cetuximab.</p

The Cognitive Impact of the ANK3 Risk Variant for Bipolar Disorder: Initial Evidence of Selectivity to Signal Detection during Sustained Attention

BACKGROUND: Abnormalities in cognition have been reported in patients with Bipolar Disorder (BD) and their first degree relatives, suggesting that susceptibility genes for BD may impact on cognitive processes. Recent genome-wide genetic studies have reported a strong association with BD in a single nucleotide polymorphism (SNP) (rs10994336) within ANK3, which codes for Ankyrin 3. This protein is involved in facilitating the propagation of action potentials by regulating the assembly of sodium gated ion channels. Since ANK3 influences the efficiency of transmission of neuronal impulses, allelic variation in this gene may have widespread cognitive effects. Preclinical data suggest that this may principally apply to sequential signal detection, a core process of sustained attention. METHODOLOGY/PRINCIPAL FINDINGS: One hundred and eighty-nine individuals of white British descent were genotyped for the ANK3 rs10994336 polymorphism and received diagnostic interviews and comprehensive neurocognitive assessment of their general intellectual ability, memory, decision making, response inhibition and sustained attention. Participants comprised euthymic BD patients (n = 47), their unaffected first-degree relatives (n = 75) and healthy controls (n = 67). The risk allele T was associated with reduced sensitivity in target detection (p = 0.0004) and increased errors of commission (p = 0.0018) during sustained attention regardless of diagnosis. We found no effect of the ANK3 genotype on general intellectual ability, memory, decision making and response inhibition. CONCLUSIONS/SIGNIFICANCE: Our results suggest that allelic variation in ANK3 impacts cognitive processes associated with signal detection and this mechanism may relate to risk for BD. However, our results require independent replication and confirmation that ANK3 (rs10994336) is a direct functional variant