Endoscopic Findings of Gastric Cryptococcosis in an Immunosuppressed Patient.

A 34-year-old man with a recent HIV diagnosis presented to the emergency department with a holocranial headache and skin lesions due to cryptococcosis. He was admitted and during treatment, he presented nausea, persistent vomiting, and epigastric pain. Esophagogastroduodenoscopy revealed multiple round lesions with reddish elevated edges and a pale center in corpus and antrum which were positive for Cryptococcus in pathology analysis.

Low-Temperature Toluene Oxidation on Fe-Containing Modified SBA-15 Materials.

Transition metals as catalysts for total VOC oxidation at low temperatures (150-280 °C) are a big challenge nowadays. Therefore, iron-modified SBA-15, AlSBA-15, and ZrSBA-15 materials with 0.5 to 5.0 wt.% Fe loading were prepared and tested for toluene oxidation. It was found that increasing Fe loading significantly improved the rate of oxidation and lowered the temperature of achieving 100% removal of toluene from above 500 °C for the supports (AlSBA-15 and ZrSBA-15) to below 400 °C for 5FeZrSBA-15. The formation of finely dispersed iron oxide active sites with a particle size less than 5 nm was observed on all the SBA-15, AlSBA-15, and ZrSBA-15 supports. It was found that the surface properties of the mesoporous support due to the addition of Al or Zr predetermined the type of formed iron oxide species and their localization on the support surface. Fe-containing SBA-15 and AlSBA-15 showed activity in total toluene oxidation at higher temperatures (280-450 °C). However, 5 wt. % Fe-containing ZrSBA-15 showed excellent activity in the total oxidation of toluene as a model VOC at lower temperatures (150-380 °C) due to the synergistic effect of Fe-Zr and the presence of accessible and stable Fe2+/Fe3+ active sites.

Effects of support and reaction pressure for the synthesis of dimethyl ether over heteropolyacid catalysts.

Dimethyl ether (DME) is an advanced second-generation biofuel produced via methanol dehydration over acid catalysts such as γ-Al2O3, at temperatures above 240 °C and pressures above 10 bar. Heteropolyacids such as tungstosilicic acid (HSiW) are Brønsted acid catalysts with higher DME production rates than γ-Al2O3, especially at low temperatures (140-180 °C). In this work, we show that the performance of supported HSiW for the production of DME is strongly affected by the nature of the support. TiO2 and SiO2 supported HSiW display the highest DME production rates of ca. 50 mmolDME/h/gHSiW. Characterization of acid sites via 1H-NMR, NH3-isotherms and NH3-adsrobed DRIFT reveal that HSiW/X have Brønsted acid sites, HSiW/TiO2 showing more and stronger sites, being the most active catalyst. Methanol production increases with T until 200 °C where a rapid decay in methanol conversion is observed. This effect is not irreversible, and methanol conversion increases to ca. 90% by increasing reaction pressure to 10 bar, with DME being the only product detected at all reaction conditions studied in this work. The loss of catalytic activity with the increasing temperature and its increasing with reaction pressure accounts to the degree of contribution of the pseudo-liquid catalysis under the reaction conditions studied.

Nivel de seguridad en el manejo de los productos químicos peligrosos en la comunidad Mantilla / Security level in the management of hazardous chemical products in Mantilla community

Introducción: El manejo responsable de los productos químicos peligrosos tiene relación directa con el conocimiento, comprensión y percepción de riesgo que tengan los individuos involucrados. Objetivo: Evaluar el nivel de seguridad en el manejo de los productos químicos peligrosos en la comunidad Mantilla y compararlo con el estudio que se realizó en la comunidad Pogolotti-Finlay-Belén en La Habana, entre 2013-2015. Métodos: Investigación descriptiva exploratoria, que se realizó en el Consejo Popular Mantilla de Arroyo Naranjo en 2016, con una población de 1338 practicantes sistemáticos en el manejo de los productos químicos peligrosos. Se escogió una muestra no probabilística de 200 personas, que se seleccionaron de forma intencional. Se confeccionó una lista de verificación para evaluar el nivel de seguridad, con objetivos específicos y contenidos para esta comunidad. Se evaluaron los aspectos de seguridad, se determinaron los perfiles de riesgo con el software ASeC, y se realizó un análisis de sensibilidad en la comunidad Mantilla. Se efectuó un estudio comparativo entre los resultados del análisis de sensibilidad para la comunidad de Mantilla y la de Pogolotti-Finlay-Belén mediante diagrama de Venn. Resultados: Los resultados por aspectos de seguridad en la comunidad de Mantilla fueron evaluados de negativos y no mostraron diferencias significativas con los obtenidos en la comunidad de Pogolotti-Finlay-Belén. Conclusiones: La identificación de los focos de peligro en la comunidad Mantilla resultó crítica. Ambas comunidades no demostraron la capacidad funcional para enfrentar una emergencia y desconocen las acciones y consecuencias que tiene para la población y el medio ambiente los accidentes con productos químicos peligrosos(AU)

Introduction: Responsible management of hazardous chemical products has direct relation with the knowledge, comprehension and perception of the risk that the individuals involved have. Objective: To evaluate the safety level in the management of hazardous chemical products in Mantilla community, Havana, Cuba and compare it with the assessment performed in Pogolotti-Finlay-Belén community of the same province, from 2013 to 2015. Methods: Exploratory-descriptive research conducted in Mantilla community, Arroyo Naranjo municipality, Havana, Cuba in 2016, over a population of 1338 systematic practitioners in the handling of hazardous chemical products. The sample was of 200 people; and it was non-probabilistically and intentionally selected. An exhaustive checklist was prepared for applying the safety level assessment method with specific objectives and contents for the community. The safety aspects were assessed, the risk profile was determined by using ASeC software, and a sensitivity analysis for Mantilla community was performed. A comparison of the sensitivity analysis results was also carried out for both Mantilla and Pogolotti-Finlay-Belén communities using the Venn diagram. Results: The results by safety aspects of Mantilla community were assessed with negative values. When compared them with the results obtained on a previous research in the Pogolotti-Finlay-Belén community, some irrelevant differences where obtained. Conclusions: The hazard focus identification in Mantilla community became critical. Both communities didn't show functional capability for facing an emergency, and they didn't know what actions and consequences could have an accident related to hazardous chemical products in the population and the environment(AU)

[Antimicrobial susceptibility and mutations in the 23S rRNA gen of Helicobacter pylori in dyspeptic patients]. / Susceptibilidad antimicrobiana y mutaciones en el gen ARNr 23S de Helicobacter pylori en pacientes dispépticos.

In order to evaluate antimicrobial susceptibility and detect specific mutations in the 23S rRNA gene in Helicobacter pylori strains, a cross-sectional study was performed on 95 patients with dyspepsia treated in a private clinic in Lima. Antrum biopsies were collected by endoscopy for isolation and evaluation of antimicrobial susceptibility using the broth microdilution method. The detection of specific mutations was developed by PCR-RFLP. The percentage of infection by Helicobacter pylori was 46.3%. Resistance values of 52.3% to clarithromycin, 29.6% to metronidazole, 45.5% to levofloxacin, and 4.6% to amoxicillin were observed. The percentage of specific A2142G and A2143G mutations associated with clarithromycin resistance was 43.5%. In conclusion, we found that antimicrobial resistance rates and the percentage of Helicobacter pylori strains circulating in a private clinic in Lima were high.

Con el objetivo de evaluar la susceptibilidad antimicrobiana y detectar mutaciones puntuales en el gen ARNr 23S en cepas de Helicobacter pylori se realizó un estudio transversal que incluyó a 95 pacientes con dispepsia atendidos en una clínica privada de Lima. Mediante endoscopía se colectaron biopsias de antro para el aislamiento de cepas de Helicobacter pylori para la evaluación de la susceptibilidad antimicrobiana empleando la técnica de microdilución en caldo. La detección de mutaciones puntuales se desarrolló mediante PCR-RFLP. El porcentaje de infección por Helicobacter pylori fue de 46,3%, se observaron valores de resistencia de 52,3% a claritromicina, 29,6% a metronidazol, 45,5% a levofloxacino y 4,6% a amoxicilina. El porcentaje de mutaciones puntuales A2142G y A2143G asociados a resistencia a claritromicina fue 43,5%. En conclusión, encontramos que las tasas de resistencia antimicrobiana y el porcentaje de cepas de Helicobacter pylori circulantes en una clínica privada de Lima fueron elevadas.

Susceptibilidad antimicrobiana y mutaciones en el gen ARNr 23S de Helicobacter pylori en pacientes dispépticos / Antimicrobial susceptibility and mutations in the 23S rRNA gen of Helicobacter pylori in dyspeptic patients

RESUMEN Con el objetivo de evaluar la susceptibilidad antimicrobiana y detectar mutaciones puntuales en el gen ARNr 23S en cepas de Helicobacter pylori se realizó un estudio transversal que incluyó a 95 pacientes con dispepsia atendidos en una clínica privada de Lima. Mediante endoscopía se colectaron biopsias de antro para el aislamiento de cepas de Helicobacter pylori para la evaluación de la susceptibilidad antimicrobiana empleando la técnica de microdilución en caldo. La detección de mutaciones puntuales se desarrolló mediante PCR-RFLP. El porcentaje de infección por Helicobacter pylori fue de 46,3%, se observaron valores de resistencia de 52,3% a claritromicina, 29,6% a metronidazol, 45,5% a levofloxacino y 4,6% a amoxicilina. El porcentaje de mutaciones puntuales A2142G y A2143G asociados a resistencia a claritromicina fue 43,5%. En conclusión, encontramos que las tasas de resistencia antimicrobiana y el porcentaje de cepas de Helicobacter pylori circulantes en una clínica privada de Lima fueron elevadas.

ABSTRACT In order to evaluate antimicrobial susceptibility and detect specific mutations in the 23S rRNA gene in Helicobacter pylori strains, a cross-sectional study was performed on 95 patients with dyspepsia treated in a private clinic in Lima. Antrum biopsies were collected by endoscopy for isolation and evaluation of antimicrobial susceptibility using the broth microdilution method. The detection of specific mutations was developed by PCR-RFLP. The percentage of infection by Helicobacter pylori was 46.3%. Resistance values of 52.3% to clarithromycin, 29.6% to metronidazole, 45.5% to levofloxacin, and 4.6% to amoxicillin were observed. The percentage of specific A2142G and A2143G mutations associated with clarithromycin resistance was 43.5%. In conclusion, we found that antimicrobial resistance rates and the percentage of Helicobacter pylori strains circulating in a private clinic in Lima were high.

Mechanochemically synthesized Ag-based nanohybrids with unprecedented low toxicity in biomedical applications.

A simple and innovative mechanochemical approach was employed to synthesize Ag-polysaccharide nanohybrid materials that were proved to exhibit remarkable surface properties and structures for biomedical applications. The synthesized Ag nanomaterials possessed an unprecedented low cytotoxicity against human cell lines A549 and SH-SY5Y as compared to similarly reported Ag nanomaterials due to the stability and low release of Ag+ and high biocompatibility of the nanohybrids.

Bioseguridad en laboratorios clínicos de la atención primaria de salud / Biosafety in clinical laboratories of the primary health care

Se realizó un estudio descriptivo retrospectivo en tres laboratorios clínicos de la atención primaria de salud en el periodo de enero a diciembre del 2014, con el objetivo de identificar las principales desviaciones en el cumplimiento de los requisitos de bioseguridad en los laboratorios objeto de estudio. El instrumento para la recogida de datos fue la lista de chequeo con 38 aspectos; las dimensiones estudiadas fueron: estructura y gestión de la seguridad biológica, prácticas y procedimientos apropiados, manipulación de los desechos contaminados, protección personal y diseño de la instalación. Se aplicó el diagrama causa y efecto de la Palma Real a las dimensiones con mayor incidencia de aspectos negativo para la bioseguridad. Como resultados, las dimensiones con más aspectos negativos fueron: estructura y gestión de la seguridad biológica y manipulación de los desechos contaminados. Este estudio permitió generar la siguiente conclusión: como consecuencia del mal funcionamiento de la dirección de la práctica, no se cumple con los requisitos de seguridad establecidos para el establecimiento de una estructura que apoye la seguridad biológica en las instalaciones(AU)

Defensa en profundidad para la evaluación de riesgos laborales por ruido en termoeléctrica / Deep defense to asses labor risks for noise in power station

INTRODUCCIÓN: Las técnicas de evaluación de riesgos laborales se llevan a cabo por diferentes procedimientos, a través de las aplicaciones de métodos normativos del cumplimiento de los parámetros asociados con las mediciones de los umbrales de daño a la salud del hombre. Sin embargo, no se tienen en cuenta los principios básicos de seguridad, que incluyen las experiencias de buenas prácticas en industrias de altos requisitos de seguridad y disponibilidad. OBJETIVOS: El objetivo de este artículo es proponer un método bajo el enfoque de defensa en profundidad para evaluar los riesgos laborales por ruido en la Central Termoeléctrica (CTE) de 100 MW. Material y MÉTODOS: Se aplicó la técnica de entrevistas a técnicos y especialistas en seguridad y salud del trabajo, así como tecnólogos para explorar los elementos que tomaban en cuenta en la evaluación de los riesgos laborales por ruido, y se realizó la consulta a especialistas para precisar los elementos que debían formar parte de los aspectos de seguridad de acuerdo al método propuesto. Además Se realizó la evaluación de los riesgos laborales por ruido de acuerdo a dos metodologías implementadas con anterioridad y la propuesta. RESULTADOS: Se muestran de acuerdo a las tres metodologías. Se determinó que la generación de ruidos no es un aspecto significativo a tener en cuenta, para la metodología 1, se evidenció una dispersión del nivel sonoro, con tendencia estable a los valores máximos en determinadas áreas según la Norma Cubana de ruido, para la metodología 2 mientras que para la metodología 3, los aspectos de seguridad evaluados negativamente por cada escalón, son los que se requieren tomar medidas correctivas dirigidas a modificar los ítems calificados negativamente a positivos para elevar el nivel de seguridad. CONCLUSIONES: La evaluación empleando escalones de defensa en profundidad aplicado a los riesgos laborales posibilita un análisis con el enfoque de procesos, que permite estimar la contribución relativa y sus causas, así como resolverlas en un corto plazo

The labour risks evaluation techniques are carried out using several methods, through the application of normative methods applying the execution of the parameters associated with the measurements of the men's health damage thresholds. Basic security principles are nevertheless not taken into account, which enclose the good practices experiences in high-requirement security and availability industries. OBJECTIVES: The purpose of this article is to propose a method attending on the defence in depth in order to evaluate the noise labour risks in the Thermal Power Station (TPS) of 100 MW. MATERIAL AND METHODS: In order to explore the elements considered in the evaluation of the noise labours risks, interviews to technicians and specialists in labour security and health were taken. It was carried out the consultation to specialists in order to specify the elements that should be part of the security aspects according to the nominative method. The evaluation of the labours risks for noise together with the proposal were also carried out according to two methodologies prior employed. RESULTS: three methodologies were used. It was determined that the noise generation is not a significant aspect to keep in mind for the methodology 1. For the methodology 2 it was demonstrated a dispersion of the noise level with stable tendency to the maximal values in determining areas according to the Noise Cuban Norm, while for the methodology 3, the security aspects negatively evaluated for each step, are those which require to take corrective measures implemented to modify the negatively-qualified items to positive in order to raise the security level. CONCLUSIONS: The evaluation using the depth security levels applied to the labour risks allows to estimate an analysis with the process approach, that allow not only to esteem the relative contribution and its causes but to resolve them in a short-term period

Hierarchical zeolites and their catalytic performance in selective oxidative processes.

Hierarchical ZSM-5 zeolites prepared using a simple alkali treatment and subsequent HCl washing are found to exhibit unprecedented catalytic activities in selective oxidation of benzyl alcohol under microwave irradiation. The metal-free zeolites promote the microwave-assisted oxidation of benzyl alcohol with hydrogen peroxide in yields ranging from 45-35 % after 5 min of reaction under mild reaction conditions as well as the epoxidation of cyclohexene to valuable products (40-60 % conversion). The hierarchically porous systems also exhibited an interesting catalytic activity in the dehydration of N,N-dimethylformamide (25-30 % conversion), representing the first example of transition-metal free catalysts in this reaction.

Mechanochemical synthesis of advanced nanomaterials for catalytic applications.

Mechanochemical synthesis emerged as the most advantageous, environmentally sound alternative to traditional routes for nanomaterials preparation with outstanding properties for advanced applications. Featuring simplicity, high reproducibility, mild/short reaction conditions and often solvent-free condition (dry milling), mechanochemistry can offer remarkable possibilities in the development of advanced catalytically active materials. The proposed contribution has been aimed to provide a brief account of remarkable recent findings and advances in the mechanochemical synthesis of solid phase advanced catalysts as opposed to conventional systems. The role of mechanical energy in the synthesis of solid catalysts and their application is critically discussed as well as the influence of the synthesis procedure on the physicochemical properties and the efficiency of synthesized catalysts is studied. The main purpose of this feature article is to highlight the possibilities of mechanochemical protocols in (nano)materials engineering for catalytic applications.

Caracterización y categorización de los riesgos biológicos en el laboratorio clínico del policlínico docente Rampa, municipio Plaza de la Revolución, La Habana, Cuba / Characterization and categorization of the biological risks in the clinical laboratory of the polyclinics Rampa, Revolution Square Municipality, Havana, Cuba

El presente trabajo tiene el objetivo de caracterizar y categorizar los riesgos biológicos en las áreas de trabajo del laboratorio clínico del policlínico docente Rampa. Para realizar la investigación se aplicó una lista de chequeo por escalones de defensa en profundidad, nueva base de conocimientos integrada a un sistema de gestión del riesgo, desarrollado a través del método Evaluación de niveles de seguridad, que se basa en un enfoque avanzado de la seguridad. Se pudo constar en la aplicación al laboratorio clínico del policlínico que presenta 34 por ciento de aspectos negativos para la seguridad, que corresponde a un nivel de inaceptable-crítico, lo que significa que el riesgo debido a la práctica se ha incrementado muy por encima del nivel tolerable (aceptable o básico), siendo penalizado al nivel inmediato inferior de inaceptable-extremo, debido a la calificación del escalón de defensa en profundidad 0, lo que demuestra la dependencia del nivel de seguridad general de la instalación con la calificación de este último escalón. Se concluye que el método de Evaluación de niveles de seguridad permite obtener el perfil de riesgo por escalones de defensa ordenados por importancia cualitativa y cuantitativa, considerados contribuyentes del perfil de riesgo global del laboratorio, y contribuye a la toma de decisiones relativas a la seguridad en la instalación objeto de estudio(AU)

The present study aims to characterize and categorize biological hazards in the work areas of the clinical laboratory of the polyclinics Rampa. To conduct the research a checklist for steps of defense in depth was applied, new base of knowledge, an integrated risk management system, developed through the assessment method that Security Levels based on an advanced approach to security. It could be noted in the evaluation of application of the method to the laboratory safety levels in thr policlinics Rampa, which has 34 percent of negative issues of security level corresponding to a unacceptable-critical, which means that the risk due to the practice has increased well above the level tolerable (acceptable or basic), being penalized at the next lower level, unacceptable-end, due to tier defense rating 0, which shows the dependence the overall security of the facility with the rating this last step. We conclude that the method Assessment Levels Security, giving the risk profile defense steps sorted by relevance considered qualitative and quantitative taxpayer's overall risk profile and helps laboratory decisions relating to safety in the installation order study(AU)

Mechanochemical synthesis of maghemite/silica nanocomposites: advanced materials for aqueous room-temperature catalysis.

A simple, environmentally friendly, and highly reproducible protocol has been developed for the mechanochemical preparation of advanced nanocatalytic materials in a one-pot process. The materials proved to have unprecedented activities in aqueous Suzuki couplings at room temperature, paving the way for a new generation of highly active and stable advanced nanocatalysts.

Simple Preparation of Novel Metal-Containing Mesoporous Starches.

Metal-containing mesoporous starches have been synthesized using a simple and efficient microwave-assisted methodology followed by metal impregnation in the porous gel network. Final materials exhibited surface areas >60 m² g-1, being essentially mesoporous with pore sizes in the 10-15 nm range with some developed inter-particular mesoporosity. These materials characterized by several techniques including XRD, SEM, TG/DTA and DRIFTs may find promising catalytic applications due to the presence of (hydr)oxides in their composition.

Selective conversion of furfural to maleic anhydride and furan with VO(x)/Al(2)O(3) catalysts.

Furfural can be converted into maleic anhydride (73 % yield) through selective gas phase oxidation at 593 K with O(2) by using VO(x)/Al(2)O(3) (10 at(V) nm(-2)) as solid catalysts. The use of lower temperatures and/or O(2) pressures result in the additional formation of furan (maximum 9 % yield). Mechanistically, furfural (C(5)H(4)O(2)) is oxidized stepwise to furan (C(4)H(4)O), 2-furanone (C(4)H(4)O(2)), and finally, maleic anhydride (C(4)H(2)O(3)). The specific structure of the supported vanadium oxides and reaction conditions (temperature and reactants pressures) all influence furfural oxidation catalysis. We have found that Al(2)O(3)-supported polyvanadates are intrinsically more active (2.70 mmol h(-1) g-at V(-1)) than monovanadates (VO(4)) and V(2)O(5) crystals (0.89 and 0.70 mmol h(-1) g-at V(-1), respectively) in maleic anhydride and furan formation rates (553 K, 1.6 kPa furfural, 2.5 kPa O(2)). Our alternative approach enables the use of biomass instead of petroleum to synthesize maleic anhydride and furan from furfural. The potential variety of industrial applications is of enormous interest for the development of future biorefineries.

Preparation and characterization of Mg-Zr mixed oxide aerogels and their application as aldol condensation catalysts.

A series of Mg-Zr mixed oxides with different nominal Mg/(Mg+Zr) atomic ratios, namely 0, 0.1, 0.2, 0.4, 0.85, and 1, is prepared by alcogel methodology and fundamental insights into the phases obtained and resulting active sites are studied. Characterization is performed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N(2) adsorption-desorption isotherms, and thermal and chemical analysis. Cubic Mg(x)Zr(1-x)O(2-x) solid solution, which results from the dissolution of Mg(2+) cations within the cubic ZrO(2) structure, is the main phase detected for the solids with theoretical Mg/(Mg+Zr) atomic ratio ≤0.4. In contrast, the cubic periclase (c-MgO) phase derived from hydroxynitrates or hydroxy precursors predominates in the solid with Mg/(Mg+Zr)=0.85. c-MgO is also incipiently detected in samples with Mg/(Mg+Zr)=0.2 and 0.4, but in these solids the c-MgO phase mostly arises from the segregation of Mg atoms out of the alcogel-derived c-Mg(x)Zr(1-x)O(2-x) phase during the calcination process, and therefore the species c-MgO and c-Mg(x)Zr(1-x)O(2-x) are in close contact. Regarding the intrinsic activity in furfural-acetone aldol condensation in the aqueous phase, these Mg-O-Zr sites located at the interface between c-Mg(x)Zr(1-x)O(2-x) and segregated c-MgO display a much larger intrinsic activity than the other noninterface sites that are present in these catalysts: Mg-O-Mg sites on c-MgO and Mg-O-Zr sites on c-Mg(x)Zr(1-x)O(2-x). The very active Mg-O-Zr sites rapidly deactivate in the furfural-acetone condensation due to the leaching of active phases, deposition of heavy hydrocarbonaceous compounds, and hydration of the c-MgO phase. Nonetheless, these Mg-Zr materials with very high specific surface areas would be suitable solid catalysts for other relevant reactions catalyzed by strong basic sites in nonaqueous environments.

Control de configuraciones peligrosas a través de matrices de dependencias en centrales nucleares / Hazardous configurations control througth dependence matrixes

RESUMEN El control de configuraciones peligrosas en instalaciones con riesgo asociado se ha realizado habitualmente a través de la consulta de los listados de conjuntos mínimos de corte obtenidos durante los análisis de riesgo previos de estas o con el uso de monitores de riesgo, los que permiten detectar on-line tales configuraciones. Esta tarea es de gran importancia por cuanto, ante una demanda real, las configuraciones representan la indisponibilidad total de sistemas o, en el mejor de los casos, el deterioro de la disponibilidad de ellos, coadyuvando así al daño de la instalación. Por otra parte, las matrices de dependencias se han utilizado habitualmente como parte de los Análisis Probabilistas de Seguridad para estudiar las interfaces entre sistemas tecnológicos. En el trabajo se presentó un método cualitativo de control de configuraciones peligrosas basado en matrices de dependencias. El algoritmo informatizado en el código CONFIGURACIÓN, se puede aplicar sin necesidad de Análisis Probabilistas de Seguridad previos ni uso de monitores de riesgo. Esta posibilidad de análisis constituye una novedad. La sencillez del método justifica su extensión a instalaciones donde estas herramientas no se han desarrollado, permitiendo así la detección de las configuraciones peligrosas en caso de simultaneidades de fallos, rotaciones de equipos, pruebas y mantenimientos. Una primera versión de este sistema se utiliza como ayuda en la operación de la Central Nuclear de Embalse.

ABSTRACT The hazardous configurations control in risk related facilities has been carried out by the analysis of minimal cut sets obtained from previous risk analysis. A more complete option is the risk monitoring for the on-line detection of these configurations. This is a very important task in cases of real demand, because these configurations represent a degraded condition of system reliability and, which in the worst case, may result in the system fault, and consequently, in the loss of the facility. On the other hand, the dependence matrixes are generally used in studying the interfaces among technological systems in PSA. The paper presents a configuration control method, based on dependence matrixes. The algorithm is included in a computer code called CONFIGURACION, to determine these situations in a qualitative way, without previous PSA results or using a Risk Monitor. This possibility of analysis is a novelty. The simplicity of the method warrants its application to facilities where these tools have not been developed, thus allowing the detection of hazardous configurations in case of simultaneous failures, equipment rotations, test and/or maintenances. The first version of this configuration control system is used as an aid in the operation of NPP Embalse.

Aplicación de mantenimiento centrado en la confiabilidad a la Central Nuclear de Embalse / Application of realibility centered maintenance to embalse NPP

RESUMEN Entre las más recientes aplicaciones del Análisis Probabilista de Seguridad de la Central Nuclear de Embalse está el Programa de Mantenimiento Orientado a la Seguridad, el cual se ha desarrollado a través de la metodología de Mantenimiento Centrado en la Confiabilidad. Esta aplicación se ha realizado de manera cooperada entre el personal del departamento de seguridad nuclear de la central y especialistas cubanos del Instituto Superior de Tecnologías y Ciencias Aplicadas. Hasta la fecha se han analizado seis sistemas tecnológicos, obteniéndose importantes resultados relacionados con la optimización del programa de mantenimiento preventivo y predictivo aplicado actualmente a dichos sistemas. Algunas tareas de la metodología se han automatizado a través del código MOSEG. Los resultados del estudio se enfocan a la redacción o modificación del contenido de las Planillas de Inspección, priorización de repuestos, reorientación de técnicas de diagnóstico y modificación de frecuencias y de duración de la ejecución de las acciones de mantenimiento.

ABSTRACT One of the most recent applications of Probabilistic Safety Analysis to Embalse NPP is the Safety Oriented Maintenance Program developed through the Realibility Centered Maintenence (RCM) methodology. Such an application was carried out by a cooperated effort between the staff of nuclear safety department of NPP and experts from Higher Institute of Technologies and Applied Sciences of Cuba. So far 6 technological systems have been analized with important results regarding the optimization of preventive and predictive maintenance program of those systems. Some RCM tasks were automated using the MOSEG code. The results of this study were focused on the elaboration and modification of the Preventive Program, prioritization of stocks, reorientation of predictive techniques and modification in the time parameters of maintenance.

Formic acid dehydrogenation on au-based catalysts at near-ambient temperatures.

Selective HCOOH decomposition to H(2)/CO(2) on Au: Au species catalyze HCOOH dehydrogenation at higher rates than on Pt, previously considered the most active metal. Dehydrogenation occurs through formate decomposition limited by H(2) desorption on Au species undetectable by TEM. CO did not form (<10 ppm), making products suitable for low-temperature fuel cells.