Design and analysis of a mechanical ventilation system based on cams

Low-cost mechanical ventilators have been developed in order to deal with the shortage of traditional ventilators whose quantity is not sufficient in an emergency context in Perú. Protofy, a company from Spain, designed one of the first low-cost mechanical ventilation systems OxyGEN which was approved by a medicine agency in its country in special context of COVID 19. Therefore, as main of this article, a redesign of this system named OxygenIP.PE was carried out according to local requirements and available technology, but maintaining its working concept based on compression mechanism by cams. Sensors were added and a control algorithm of the respiratory rate was developed. Ventilation curves monitoring over time was implemented; in this sense, a mathematical model of the whole system was developed. OxygenIP.PE was redesigned, fabricated, and tested measuring its ventilation curves over time. Results indicate that this redesign provides a sturdy equipment able to work during a longer lifetime than the original. The replicability of the ventilation curves behavior is ensured, while the mechanism dimensions are adapted for a particular airbag resuscitator. The mathematical model of the whole system can satisfactorily determine the ventilation curves over time and is used to show the air pressure, volume, and flow as a function of the compression arm's angular position and differential pressure through the breathing circuit measurement, furthermore the algorithms designed as a consequence of the mathematical model were implemented for Raspberry and ARDUINO microcontrollers. There were obtained parameters of pressure 10-65 cmH2O, airflow 50-65 l/m, volume 0-0.5 l, at two values of beat per minute (BPM) 15 and 25

Factors controlling phytoplankton in tropical high-mountain drinking-water reservoirs

Hydraulic dynamics is one of the primary factors determining the structural and temporal changes in phytoplankton communities in reservoirs. There is little information on the factors that explain the temporal changes in biotic communities in the high-mountain reservoirs that provide water to the city of Bogotá (Colombia). Our objective was to identify the environmental factors controlling the biomass and composition of algal communities in four tropical high-mountain reservoirs. We hypothesised that hydraulic dynamics is the major determining factor in temporal changes in phytoplankton communities in tropical mountain reservoirs regardless of the nutrient concentration in the system. We studied the temporal changes in phytoplankton over five years in four reservoirs that exhibit different nutrient concentrations and hydraulic management regimes. The phytoplankton in all of the reservoirs were characterised by the dominance of Dinophyceae. Canonical correspondence analyses and Pearson's correlations showed that the water renewal rate primarily explains the phytoplankton composition, followed by total nitrogen, total phosphorous and silicates. The effect of the water renewal rate was different depending on the particular conditions in each system; thus, in reservoirs with greater hydraulic dynamics, the water renewal rate explained the selection of secondary species and dominant species adapted to a broad range of environmental conditions. In the reservoir with a higher physical stability, eventual changes in the water renewal rate shifted the dominant species, reduced diversity and altered phytoplankton succession. In the reservoir with the largest volume and lowest nutrient concentration, phytoplankton species were selected primarily based on chemical and physical variables related to climatic seasonality. Our results suggest that the model for hydraulic management of the reservoirs plays an important role: in highly dynamic reservoirs, there is a direct causal relationship between phytoplankton and physical variables such as stability and water renewal rate; in less dynamic environments, phytoplankton species growth responds primarily to water chemistry.La dinámica hidráulica es uno de los principales factores que determinan la estructura y los cambios temporales de las comunidades fitoplanctónicas en embalses. Información de los factores que explican los cambios temporales de las comunidades biológicas en los embalses de alta montaña que proveen de agua la ciudad de Bogotá es escasa. El objetivo de este trabajo fue identificar los factores ambientales que controlan la biomasa y la composición de las comunidades algales en cuatro embalses tropicales de alta montaña. La hipótesis de trabajo fue que la dinámica hidráulica es el factor que principalmente determina los cambios temporales en la comunidad fitoplanctónica, con respecto a la concentración de nutrientes del sistema. Durante cinco años se estudiaron los cambios temporales del fitoplancton en cuatro embalses que se caracterizan por presentar diferentes concentraciones de nutrientes y diferente manejo hidráulico. El fitoplancton de todos los embalses se caracterizó por la dominancia de Dinophyceae. Análisis de Correspondencia Canónica y correlaciones de Pearson mostraron que la tasa de renovación hídrica explicó primariamente el fitoplancton seguida por el nitrógeno total, el fósforo total y los silicatos. El efecto de la tasa de renovación hídrica sobre el fitoplancton fue diferente dependiendo de las condiciones particulares de cada sistema; así, en embalses con una alta dinámica hidráulica, la tasa de renovación explicó las especies secundarias y seleccionó especies dominantes adaptadas a un amplio rango de condiciones ambientales. En el embalse con alta estabilidad física, cambios eventuales en la tasa de renovación cambiaron las especies dominantes, redujeron la diversidad y modificaron la sucesión del fitoplancton. En el embalse de mayor volumen y más baja concentración de nutrientes, el fitoplancton es seleccionado principalmente por otras variables físicas y químicas relacionadas con la estacionalidad climática. Los resultados sugieren que el modelo de manejo hidráulico de los embalses juega un papel importante en embalses más dinámicos, al determinar una relación causal directa entre el fitoplancton y variables físicas como la estabilidad y la tasa de renovación hídrica, mientras en embalses menos dinámicos, el crecimiento de las especies respondió principalment a la química del agua

Primer registro fotográfico de Tremarctos ornatus (Carnivora: Ursidae) y de Puma concolor (Carnivora: Felidae) en el Parque Nacional Natural Tamá, Norte de Santander, Colombia

The Andean bear (Tremarctos ornatus) and the puma (Puma concolor) are representative mammals of the Colombian Andean ecosystems. The bear is distributed in much of the Andes, from Venezuela and Colombia to Bolivia and Argentina, occupying various ecosystems from coastal deserts to moorsEl oso andino (Tremarctos ornatus) y el puma (Puma concolor) son mamíferos representativos de los ecosistemas andinos colombianos. El oso se  distribuye en gran parte de los Andes, desde Venezuela y Colombia hasta Bolivia y Argentina, ocupando variados ecosistemas desde desiertos costeros hasta páramo

Al2O3-3YTZP-Graphene multilayers produced by tape casting and spark plasma sintering

This work aims to establish a colloidal route to obtain laminates of alumina zirconia combining layers with and without graphene. Green tapes of alumina, alumina with 5 vol.% of 3Y-TZP and alumina with 5 vol.% of 3Y-TZP and graphene-oxide (2 vol.%) were obtained by aqueous tape casting. It is possible to design materials for different structural applications with a controlled microstructure with a high number of different layers. The tapes were punched into 20-mm discs, joined to form laminates alternating up to 18-layers, and sintered in one-step by spark plasma sintering (SPS) at 1400 degrees C. It has demonstrated that there is a significant graphite diffusion provoked by the required graphite holders into the SPS-furnace. Dense laminates with layer thicknesses similar to 100 mu m and good cohesion between layers were obtained. Nanoindentation results showed that hardness and elastic modulus values were higher than 27 GPa and 300 GPa, respectively, and similar for all layers. Crown Copyright (C) 2014 Published by Elsevier Ltd. All rights reserved.This work has been supported by Spanish Ministry of Economy and Competitiviness (MAT2012-31090). A. S. A. Chinelatto thanks to CAPES - Programa Ciencias sem Fronteiras (Brazil) for the concession of a fellowship for post-doctoral sabbatical grant in ICV-CSIC, Spain. A. Borrell, acknowledges the Spanish Ministry of Science and Innovation for her Juan de la Cierva contract (JCI-2011-10498) and the Generalitat Valenciana by the financial support for the BEST/2012/302 grant. Authors thank to Nanoinnova Technologies (Spain) for supplying the graphene oxide and helpful discussions.Rincón, A.; Moreno, R.; Chinelatto, ASA.; Gutierrez-Gonzalez, CF.; Rayón Encinas, E.; Salvador Moya, MD.; Borrell Tomás, MA. (2014). Al2O3-3YTZP-Graphene multilayers produced by tape casting and spark plasma sintering. Journal of the European Ceramic Society. 34(10):2427-2434. https://doi.org/10.1016/j.jeurceramsoc.2014.02.011S24272434341

Dissemination of methicillin-resistant Staphylococcus aureus USA300 sequence type 8 lineage in Latin America.

BACKGROUND: Methicillin-resistant Staphylococus aureus (MRSA) is an important nosocomial and community-associated (CA) pathogen. Recently, a variant of the MRSA USA300 clone emerged and disseminated in South America, causing important clinical problems. METHODS: S. aureus isolates were prospectively collected (2006-2008) from 32 tertiary hospitals in Colombia, Ecuador, Peru, and Venezuela. MRSA isolates were subjected to antimicrobial susceptibility testing and pulsed-field gel electrophoresis and were categorized as health care-associated (HA)-like or CA-like clones on the basis of genotypic characteristics and detection of genes encoding Panton-Valentine leukocidin and staphylococcal cassette chromosome (SCC) mec IV. In addition, multilocus sequence typing of representative isolates of each major CA-MRSA pulsotype was performed, and the presence of USA300-associated toxins and the arcA gene was investigated for all isolates categorized as CA-MRSA. RESULTS: A total of 1570 S. aureus were included; 651 were MRSA (41%)--with the highest rate of MRSA isolation in Peru (62%) and the lowest in Venezuela (26%)--and 71%, 27%, and 2% were classified as HA-like, CA-like, and non-CA/HA-like clones, respectively. Only 9 MRSA isolates were confirmed to have reduced susceptibility to glycopeptides (glycopeptide-intermediate S. aureus phenotype). The most common pulsotype (designated ComA) among the CA-like MRSA strains was found in 96% of isolates, with the majority (81%) having a \u3c or =6-band difference with the USA300-0114 strain. Representative isolates of this clone were sequence type 8; however, unlike the USA300-0114 strain, they harbored a different SCCmec IV subtype and lacked arcA (an indicator of the arginine catabolic mobile element). CONCLUSION: A variant CA-MRSA USA300 clone has become established in South America and, in some countries, is endemic in hospital settings

The influence of anthropogenic activities on the concentration of pesticides, physicochemical and microbiological properties in the Chumbao river, Andahuaylas, Perú

The province of Andahuaylas is located in the region of Apurimac, a Peruvian city located in the Andes. Andahuaylas has three important districts: San Jerónimo, Andahuaylas and Talavera. These areas are highly populated, and their buildings are close to the Chumbao River. This research aimed to determine the influence of anthropogenic activities on the concentration of pesticides, physicochemical and microbiological characteristics in the Chumbao River. Five agricultural activities, 19 organochlorine pesticides, and 25 organophosphorus pesticides were studied. Eighteen physicochemical properties and two microbiological properties were also studied at seven sampling points along the Chumbao River during the rainy and dry seasons. Several veterinary and agricultural products were identified in the agricultural activities studied. However, no significant concentration values of organochlorine and organophosphate pesticides were found; no weed control products were found. In the case of livestock farming, albendazole and ivermectin are frequently used as anthelmintics. Organophosphate and pyrethroid insecticides are used to control flies and other ectoparasites. Several pesticides have been identified in the surveys in the case of quinoa, potato, and corn crops. Some of the physicochemical and microbiological properties are above environmental quality standards according to current Peruvian regulations; these properties increase at points where wastewater is discharged directly into the river. The study evidenced a progressive deterioration of water quality in the Chumbao River caused by anthropic activities in the basin. These may cause infectious and parasitic diseases in the urban population of the Chumbao river valley

Advances in Improving Tolerance to Waterlogging in \u3cem\u3eBrachiaria\u3c/em\u3e Grasses

Poor drainage is found on about 11.3% of agricultural land in Latin America where physiography promotes flooding, high groundwater tables, or stagnant surface water (waterlogging). Waterlogging drastically reduces oxygen diffusion into the soil causing hypoxia which is the main limitation that reduces root aerobic respiration and the absorption of minerals and water. Under waterlogging conditions plants can adapt with traits and mechanisms that improve root aeration such as production of aerenchyma and development of adventitious roots. During the rainy season Brachiaria pastures are exposed to waterlogging conditions that can severely limit pasture productivity and hence animal production. The main objective of an inter-institutional and multidisciplinary project was to identify Brachiaria hybrids combining waterlogging tolerance with high forage yield and quality to improve meat and milk production and mitigate the impacts of climate change in the humid areas of Latin America. Researchers at the Centro Internacional de Agricultura Tropical (CIAT) have developed a screening method to evaluate waterlogging tolerance in Brachiaria. Using this method, 71 promising hybrids derived from three Brachiaria species (B. ruziziensis, B. brizantha, and B. decumbens) were evaluated. Four hybrids were identified as superior in waterlogging tolerance. Their superiority was based on greater green leaf biomass production, a greater proportion of green leaf to total leaf biomass, greater green leaf area, leaf chlorophyll content, and photosynthetic efficiency, and reduced dead leaf biomass. These hybrids together with previously selected hybrids and germplasm accessions are being field-tested for waterlogging tolerance in collaboration with National Agricultural Research Institutions and farmers from Colombia, Nicaragua, and Panama

Modified Polymeric Biosorbents from Rumex acetosella for the Removal of Heavy Metals in Wastewater

The contamination of water resources by effluents from various industries often contains heavy metals, which cause irreversible damage to the environment and health. The objective was to evaluate different biosorbents from the weed Rumex acetosella to remove metal cations in wastewater. Drying, grinding and sieving of the stems was carried out to obtain the biomass, re taining the fractions of 250 to 500 µm and 500 to 750 µm, which served to obtain the biosorbents in natura (unmodified), acidic, alkaline, and mixed. Proximal analysis, PZC, TOC, removal capacity, influence of pH, functional groups, thermal analysis, structural characteristics, adsorption iso therms, and kinetic study were evaluated. The 250 µm mixed treatment was the one that presented the highest removal percentages, mainly due to the OH, NH, -C-H, COOH, and C-O functional groups achieving the removal of up to 96.14% of lead, 36.30% of zinc, 34.10% of cadmium and 32.50% of arsenic. For contact times of 120 min and an optimum pH of 5.0, a loss of cellulose mass of 59% at 328 °C and a change in the surface of the material were also observed, which allowed for obtaining a topography with greater chelating capacity, and the Langmuir and pseudo-second or der models were better fitted to the adsorption data. The new biosorbents could be used in wastewater treatment economically and efficiently

Riesgo de sangrado y complicaciones ginecoobstétricas en una paciente con déficit de factor XIII. Presentación de un caso y revisión de la literatura

ResumenLa deficiencia de factor XIII de la coagulación es un trastorno raro de la coagulación, entre los que están la afibrinogenemis y los de factor II, V, V+VIII, VII, X y XI. Estos son son anormalidades de la hemostasia con herencia autosómica recesiva; su prevalencia es de 1 en 500,000 a 2 millones de personas. Por su rareza, tipo y severidad de las hemorragias y lo poco claro que es el defecto molecular y su manejo son un reto diagnóstico y terapéutico. Para algunas de estas deficiencias no existen concentrados del factor de coagulación implicado disponibles, por lo que es necesario utilizar derivados sanguíneos o medicamentos hemostáticos alternativos, lo que puede generar complicaciones, en ocasiones fatales; estas complicaciones pueden ser minimizadas evaluando en cada caso el riesgo de sangrado o de trombosis seleccionando comotratamiento alternativas diferentes a los derivados de la sangre, o incluso no administrando tratamiento en los episodios hemorrágicos leves. En este artículo se describe el caso de una paciente con diagnóstico de déficit de factor XIII que debutó con hematuria y complicaciones ginecoobstétricas; hay historia familiar de consanguinidad y de déficit de factor XIII; recibió manejo con crioprecipitados y antifibrinolíticos y profilaxis con crioprecipitados durante el transcurso de su segundo embarazo, lográndose un producto a término con un parto por cesárea sin complicaciones hemorrágicas o trombóticas.[Sossa CL, Jiménez SI, Rincón IM, Pérez CA, Galvis HD. Riesgo de sangrado y complicaciones ginecoobstétricas en una paciente con déficit de factor XIII. Presentación de un caso y revisión de la literatura. MedUNAB 2008; 11:185-190].Palabras clave: Trastorno de la coagulación, Deficiencia factor XIII