Experimental and Modeling High-Pressure Study of Ammonia-Methane Oxidation in a Flow Reactor.

The present work deals with an experimental and modeling analysis of the oxidation of ammonia-methane mixtures at high pressure (up to 40 bar) in the 550-1250 K temperature range using a quartz tubular reactor and argon as a diluent. The impact of temperature, pressure, oxygen stoichiometry, and CH4/NH3 ratio has been analyzed on the concentrations of NH3, NO2, N2O, NO, N2, HCN, CH4, CO, and CO2 obtained as main products of the ammonia-methane mixture oxidation. The main results obtained indicate that increasing either the pressure, CH4/NH3 ratio, or stoichiometry results in a shift of NH3 and CH4 conversion to lower temperatures. The effect of pressure is particularly significant in the low range of pressures studied. The main products of ammonia oxidation are N2, NO, and N2O while NO2 concentrations are below the detection limit for all of the conditions considered. The N2O formation is favored by increasing the CH4/NH3 ratio and stoichiometry. The experimental results are simulated and interpreted in terms of an updated detailed chemical kinetic mechanism, which, in general, is able to describe well the conversion of both NH3 and CH4 under almost all of the studied conditions. Nevertheless, some discrepancies are found between the experimental results and model calculations.

Experimental and Modeling Evaluation of Dimethoxymethane as an Additive for High-Pressure Acetylene Oxidation.

The high-pressure oxidation of acetylene-dimethoxymethane (C2H2-DMM) mixtures in a tubular flow reactor has been analyzed from both experimental and modeling perspectives. In addition to pressure (20, 40, and 60 bar), the influence of the oxygen availability (by modifying the air excess ratio, λ) and the presence of DMM (two different concentrations have been tested, 70 and 280 ppm, for a given concentration of C2H2 of 700 ppm) have also been analyzed. The chemical kinetic mechanism, progressively built by our research group in the last years, has been updated with recent theoretical calculations for DMM and validated against the present results and literature data. Results indicate that, under fuel-lean conditions, adding DMM enhances C2H2 reactivity by increased radical production through DMM chain branching pathways, more evident for the higher concentration of DMM. H-abstraction reactions with OH radicals as the main abstracting species to form dimethoxymethyl (CH3OCHOCH3) and methoxymethoxymethyl (CH3OCH2OCH2) radicals are the main DMM consumption routes, with the first one being slightly favored. There is a competition between ß-scission and O2-addition reactions in the consumption of both radicals that depends on the oxygen availability. As the O2 concentration in the reactant mixture is increased, the O2-addition reactions become more relevant. The effect of the addition of several oxygenates, such as ethanol, dimethyl ether (DME), or DMM, on C2H2 high-pressure oxidation has been compared. Results indicate that ethanol has almost no effect, whereas the addition of an ether, DME or DMM, shifts the conversion of C2H2 to lower temperatures.

Prognostic factors and combined use of tocilizumab and corticosteroids in a Spanish cohort of elderly COVID-19 patients.

Coronavirus disease 2019 (COVID-19) infection in elderly patients is more aggressive and treatments have shown limited efficacy. Our objective is to describe the clinical course and to analyze the prognostic factors associated with a higher risk of mortality of a cohort of patients older than 80 years. In addition, we assess the efficacy of immunosuppressive treatments in this population. We analyzed the data from 163 patients older than 80 years admitted to our institution for COVID-19, during March and April 2020. A Lasso regression model and subsequent multivariate Cox regression were performed to select variables predictive of death. We evaluated the efficacy of immunomodulatory therapy in three cohorts using adjusted survival analysis. The mortality rate was 43%. The mean age was 85.2 years. The disease was considered severe in 76.1% of the cases. Lasso regression and multivariate Cox regression indicated that factors correlated with hospital mortality were: age (hazard ratio [HR] 1.12, 95% confidence interval [CI]: 1.03-1.22), alcohol consumption (HR 3.15, 95% CI: 1.27-7.84), CRP > 10 mg/dL (HR 2.67, 95% CI: 1.36-5.24), and oxygen support with Venturi Mask (HR 6.37, 95% CI: 2.18-18.62) or reservoir (HR 7.87, 95% CI: 3.37-18.38). Previous treatment with antiplatelets was the only protective factor (HR 0.47, 95% CI: 0.23-0.96). In the adjusted treatment efficacy analysis, we found benefit in the combined use of tocilizumab (TCZ) and corticosteroids (CS) (HR 0.09, 95% CI: 0.01-0.74) compared to standard treatment, with no benefit of CS alone (HR 0.95, 95% CI: 0.53-1.71). Hospitalized elderly patients suffer from a severe and often fatal form of COVID-19 disease. In this regard, several parameters might identify high-risk patients upon admission. Combined use of TCZ and CS could improve survival.

Experimental Study of the Pyrolysis of NH3 under Flow Reactor Conditions.

The possibility of using ammonia (NH3), as a fuel and as an energy carrier with low pollutant emissions, can contribute to the transition to a low-carbon economy. To use ammonia as fuel, knowledge about the NH3 conversion is desired. In particular, the conversion of ammonia under pyrolysis conditions could be determinant in the description of its combustion mechanism. In this work, pyrolysis experiments of ammonia have been performed in both a quartz tubular flow reactor (900-1500 K) and a non-porous alumina tubular flow reactor (900-1800 K) using Ar or N2 as bath gas. An experimental study of the influence of the reactor material (quartz or alumina), the bulk gas (N2 or Ar), the ammonia inlet concentration (1000 and 10 000 ppm), and the gas residence time [2060/T (K)-8239/T (K) s] on the pyrolysis process has been performed. After the reaction, the resulting compounds (NH3, H2, and N2) are analyzed in a gas chromatograph/thermal conductivity detector chromatograph and an infrared continuous analyzer. Results show that H2 and N2 are the main products of the thermal decomposition of ammonia. Under the conditions of the present work, differences between working in a quartz or non-porous alumina reactor are not significant under pyrolysis conditions for temperatures lower than 1400 K. Neither the bath gas nor the ammonia inlet concentration influence the ammonia conversion values. For a given temperature and under all conditions studied, conversion of ammonia increases with an increasing gas residence time, which results into a narrower temperature window for NH3 conversion.

Orthopedic Surgical Treatment and Perioperative Complications in Multiple Myeloma Bone Disease: Analysis of a Series (2009-2018).

BACKGROUND: More than 90% of patients with multiple myeloma (MM) develop lytic bone lesions that can be surgically treated for symptomatic relief and functional improvement. METHODS: This was a retrospective observational analytic study conducted between 2009 and 2018, including 58 patients with MM bone disease who underwent 77 orthopedic surgical procedures and were co-managed by internal medicine. Analysis of data related to MM bone disease, different modalities of surgical treatment, perioperative complications, and survival was performed. RESULTS: Median age was 72 years (66.5-77 years) and 56.9% of patients were males; 54.43% of injuries were located in the spine, 27.85% in the pelvis or lower limbs, 15.19% in the upper limbs, and 75.32% of patients had pathologic fractures. In 29.31% of the cases, the bone lesion was the debut of MM. Surgical procedures performed were mainly kyphoplasty (48.05%) and intramedullary nailing (29.87%). The overall complication rate following surgery was 74.03%. Only 20.78% of cases had a surgical complication. Among medical complications, we registered 28.57% transfusion requirements, 25.97% acute renal failures, 24.68% developed an infection, and 10.39% developed hypercalcemia. Patients were followed-up for a mean of 6.13 years and 37.93% suffered a new fracture. The median overall survival time for patients after surgery was 32.9 months (11.6-49). The estimated overall survival at 1, 3, and 5 years after surgery was 81.17%, 57%, and 34.11%, respectively. CONCLUSIONS: The orthopedic surgical treatment of MM bone disease aims to improve symptomatology and patient quality of life; however, these patients have a high risk of perioperative complications and considerable early mortality, making multidisciplinary management with medical specialties essential.

VOC removal and deodorization of effluent gases from an industrial plant by photo-oxidation, chemical oxidation, and ozonization.

The efficiency of photo-oxidation, chemical oxidation by sodium hypochlorite, and ozonization for the industrial-scale removal of volatile organic compounds (VOCs) and odors from gaseous emissions was studied by applying these treatments (in an experimental system) to substances passing through an emission stack of a factory producing maize derivatives. Absorption and ozonization were the most efficient treatment, removing 75% and 98% of VOCs, respectively, while photo-oxidation only removed about 59%. The emitted chemical compounds and odors were identified and quantified by gas chromatography-mass spectrometry (in full-scan mode). In addition to presenting the results, their implications for selecting optimal processes for treating volatile emissions are discussed.

Spontaneous dislocation of a phakic refractive lens into the vitreous cavity.

A 36-year-old woman with high myopia had uneventful implantation of a phakic refractive lens (PRL) bilaterally. Two months postoperatively, the best corrected visual acuity (BCVA) in the right eye decreased to the preoperative level and the posterior chamber PRL disappeared from the anterior segment and was found lying in the vitreous cavity inferiorly. After lensectomy and pars plana vitrectomy, the PRL was removed through the initial clear corneal incision, improving the BCVA to 1.0. A zonular defect associated with high myopia, previously forgotten and unrecognized ocular trauma, or intraoperative manipulations may have resulted in the spontaneous dislocation of the PRL.

Identificación de levaduras y sensibilidad in vitro a diversos antifúngicos / Identification of yeasts and sensitivity in vitro against different antifungal

Introducción: El aumento en la incidencia de infecciones por hongos levaduriformes del género Candida y su repercusión en el ámbito hospitalario y comunitario (vaginitis recidivante), así como el conocimiento de los nuevos antifúngicos en el arsenal terapéutico, nos han motivado a identificar levaduras de este género de diverso origen y a estudiar su comportamiento frente a los antifúngicos utilizando métodos comerciales de fácil aplicación en el uso clínico. Material y métodos: Se han identificado por métodos comerciales (CHROMagar Candida® y Auxacolor®), un total de 317 levaduras del género Candida: 108 vaginales, 138 de unidades de cuidados intensivos de neonatos y 71 de unidades de cuidados intensivos de adultos, realizándose el antifungigrama a 199 de los aislados utilizando un método comercial (Fungitest®). Resultados y conclusiones: Candida albicans se identifica como el microorganismo más frecuente en ambos tipos de muestras, comunitarias y hospitalarias (el 78,7 y el 45,93 por ciento, respectivamente) seguida de Candida glabrata (el 19,44 y el 28,23 por ciento, respectivamente). La sensibilidad a anfotericina B y 5-fluorocitosina ha sido muy elevada en todos los grupos estudiados, mientras que la sensibilidad a derivados imidazólicos depende de la procedencia de las muestras (menor sensibilidad en los aislados de unidades de cuidados intensivos de neonatos), así como de la especie (C. glabrata es menos sensible que C. albicans) (AU)