Mechanisms of copper and zinc bioremoval by microalgae and bacteria grown in nutrient rich wastewaters.

Swine farming produces large quantities of nutrient-rich wastewater, which often contains metals such as Cu and Zn, used as feed additives for pigs. These metals must be removed from the wastewater before discharge but their retention in the biomass can limit its subsequent utilization. Photobioreactors are a very promising alternative for swine wastewater treatment, as the consortium of microalgae and bacteria growing symbiotically in these reactors allows high nutrient and metal removal efficiency at moderate costs. This work studies the mechanisms of removal of Cu(II) and Zn(II) by the two types of microorganisms growing in these photobioreactors. A microalga commonly used in wastewater treatment (Scenedesmus almeriensis) and an activated sludge were kept in contact with synthetic wastewater containing 100 mg/L of Cu and Zn. After 72 h, Scenedesmus almeriensis removed 43% of Cu and 45% of Zn, while activated sludge removed 78% of Cu and 96% of Zn. Single and sequential extractions of the biomasses using different extracting reagents revealed that biosorption on protonable groups is the dominant removal mechanisms. Mild reagents solubilized 69% of Cu and 94% of Zn from the microalgae and 76% of Cu and 93% of Zn from the activated sludge. Low metal concentrations in the oxidizable and residual fractions evidenced minimal bioaccumulation inside the cells. FTIR and ESEM-EDX analysis confirmed biosorption by ion exchange and complexation as the main metal remediation mechanisms. The weak bonds of the biosorbed Cu and Zn ions are beneficial for the valorization of biomass and the obtaining of safe bioproducts.

Effect of process parameters on the valorization of components from microalgal and microalgal-bacteria biomass by enzymatic hydrolysis.

Photobioreactors for wastewater treatment coupled with nutrient recovery from the biomass is a promising biorefinery platform but requires working with microalgae-bacteria consortia. This work compares the effect that hydrolysis time and different enzymes have on the solubilization and recovery of components from microalgae-bacteria grown in piggery wastewater and microalgae grown in synthetic media by enzymatic hydrolysis. Higher carbohydrate solubilizations were obtained from microalgae-bacteria than from pure microalgae (38.5% vs. 27% Celluclast, 5 h), as expected from the SEM images. Proteases solubilized xylose remarkably well, but xylose recovery was negligible in all experiments. Alcalase hydrolysis (5 h) provided the highest peptide recovery from both biomasses (≈34%), but the peptide sizes were lower than 10 kDa. Low peptide recoveries (<20%) but larger peptide sizes (up to 135 kDa) were obtained with Protamex. Pure microalgae resulted in remarkably higher losses, but similar amino acid profiles and peptide sizes were obtained from both biomasses.

Baseline thorium concentration and isotope ratios in topsoil of Zacatecas State, Mexico.

Thorium is a radionuclide highly widespread in the earth's crust with a relevant contribution to the exposure to radiation of living organisms. Natural concentrations of thorium in the soil can be altered due to human activities such as mining, agriculture, and cattle industry. Mining and related industry have been operating for centuries in Zacatecas State, Mexico, leaving mining waste dumps that can release trace elements to the topsoil. There are not enough previous studies of thorium concentration in this area. Thirty-three soil samples from different locations from Zacatecas State were analyzed, using alpha-spectrometry and ICP-MS, to estimate the reference value for thorium in surface soil in order to provide regulatory agencies with a tool to verify possible disturbances due to anthropogenic activities. Geoaccumulation indexes and enrichment factors did not reveal significant alterations in topsoil thorium concentration. The average concentration was 13.6 ± 7.6 mg kg-1, which is consistent with the estimated average concentration in the earth crust and is then proposed as average basal concentration for this region. A slight disequilibrium has been found between the natural isotopes of thorium due to the semi-arid nature of the areas and climatic factors.

Comparative uptake study of arsenic, boron, copper, manganese and zinc from water by different green microalgae.

This work represents a comparative uptake study of the toxic elements arsenic, boron, copper, manganese and zinc in monometallic and multimetallic solutions by four green microalgae species (Chlamydomonas reinhardtii, Chlorella vulgaris, Scenedesmus almeriensis and an indigenous Chlorophyceae spp.), evaluating the effect of pH and contact time. Maximum removal efficiencies for each toxic element were 99.4% for Mn (C. vulgaris, pH 7.0, 3 h), 91.9% for Zn (Chlorophyceae spp., pH 5.5, 3 h), 88% for Cu (Chlorophyceae spp., pH 7.0, 10 min), 40.7% for As (S. almeriensis, pH 9.5, 3 h) and 38.6% for B (S. almeriensis, pH 5.5, 10 min). B removal efficiencies decreased remarkably in multimetallic solutions (down to 0.2% in C. reinhardtii), except for Chlorophyceae spp., the only species isolated from a polluted environment. FTIR spectra shown the highest interactions for As (1150-1300 cm-1) and Cu (3300, 1741, 1535, 1350-1400 cm-1). Results confirm microalgae biomass as a potential biosorbent for toxic elements.

Three-way principal component analysis as a tool to evaluate the chemical stability of metal bearing residues from wastewater treatment by the ferrite process.

The chemical fractionation patterns of eight metals (Cd, Co, Cu, Cr, Mn, Ni, Pb and Zn) have been determined in 27 metal-bearing residues by using the BCR sequential extraction procedure. The residues were generated as by-products during the optimization of a semi-continuous reactor for metal removal from wastewater based on ferrite synthesis by co-precipitation. The three-dimensional X dataset (samples×metals×fractions) obtained by applying the BCR procedure has been analyzed by multivariate methods: matrix augmentation (MA-PCA) and three-way principal component analysis, 3-PCA (PARAFAC and Tucker3 models). MA-PCA and PARAFAC methods led to two-factor models giving a satisfactory but incomplete picture of the metal fractionation patterns, but the Tucker3 [2,1,2] model allowed to simultaneously describe both the 'pseudo-total' (acid-soluble) contents and the chemical fractionation by means of two non-null interactions g111 and g212 which explain 53.5% and 18.0% of the total variance, respectively. The A-mode loadings of the g212 interaction showed the close relationship between the magnetic character of the solid residues, i.e. the crystalline structure, and the chemical fractionation patterns of the metals resulting from the application of the BCR sequential extraction procedure.

El Che y sus ideas acerca de la medicina / Che and his thoughts about medicine

El presente trabajo presenta un acercamiento a destacados momentos de la vida de Ernesto Che Guevara de La Serna que fueron conformando su pensamiento salubrista y su práctica transformadora relacionada con la medicina. En él se puede encontrar una de las principales fuentes de enriquecimiento científico, humanista e internacionalista de las actuales concepciones de la medicina revolucionaria que ha llevado una mejor calidad de vida a los hombres y mujeres de innumerables rincones del mundo (AU)

The current work presents an approach to relevant moments in the life of Ernesto Che Guevara de La Serna, which conformed his health thinking and his transforming practice related to medicine. It can be found on it one of the main sources of scientific, humanistic and internationalist enrichment of the current conceptions of revolutionary medicine that has provided a better quality of life to men and women of innumerable places of the world

Modelling spatial and temporal variations in the water quality of an artificial water reservoir in the semiarid midwest of Argentina.

Temporal and spatial patterns of water quality of an important artificial water reservoir located in the semiarid Midwest of Argentina were investigated using chemometric techniques. Surface water samples were collected at 38 points of the water reservoir during eleven sampling campaigns between October 1998 and June 2000, covering the warm wet season and the cold dry season, and analyzed for dissolved oxygen (DO), conductivity, pH, ammonium, nitrate, nitrite, total dissolved solids (TDS), alkalinity, hardness, bicarbonate, chloride, sulfate, calcium, magnesium, fluoride, sodium, potassium, iron, aluminum, silica, phosphate, sulfide, arsenic, chromium, lead, cadmium, chemical oxygen demand (COD), biochemical oxygen demand (BOD), viable aerobic bacteria (VAB) and total coliform bacteria (TC). Concentrations of lead, ammonium, nitrite and coliforms were higher than the maximum allowable limits for drinking water in a large proportion of the water samples. To obtain a general representation of the spatial and temporal trends of the water quality parameters at the reservoir, the three-dimensional dataset (sampling sites×parameters×sampling campaigns) has been analyzed by matrix augmentation principal component analysis (MA-PCA) and N-way principal component analysis (N-PCA) using Tucker3 and PARAFAC (Parallel Factor Analysis) models. MA-PCA produced a component accounting for the general behavior of parameters associated with organic pollution. The Tucker3 models were not appropriate for modelling the water quality dataset. The two-factor PARAFAC model provided the best picture to understand the spatial and temporal variation of the water quality parameters of the reservoir. The first PARAFAC factor contains useful information regarding the relation of organic pollution with seasonality, whereas the second factor also encloses information concerning lead pollution. The most polluted areas in the reservoir and the polluting sources were identified by plotting PARAFAC loadings as a function of the UTM (Universal Transverse Mercator) coordinates.

Magnetic solid phase extraction based on phenyl silica adsorbent for the determination of tetracyclines in milk samples by capillary electrophoresis.

A magnetic solid phase extraction method coupled to capillary electrophoresis is proposed for the determination of tetracycline, oxytetracycline, chlortetracycline and doxycycline in milk samples. Five different magnetic phenyl silica adsorbents covered with magnetite were synthesized by varying the molar ratio of phenyltrimethylsilane and tetramethylorthosilicate; these adsorbents were evaluated in terms of their pH and degree of hydrophobicity for tetracycline retention. The optimal, selected combination of conditions was a pH of 10.0 and a magnetic sorbent ratio of 4:1; under these conditions, the retention capacity ranged from 99.7% to 101.2% for the four tetracyclines analyzed. The elution conditions and initial sample volume of the proposed extraction method were also optimized, and the best results were obtained with 1×10(-3) M acetic acid in methanol as eluent and a 200 ml of sample volume. Under optimal conditions, average recoveries ranged from 94.2% to 99.8% and the limits of detection ranged from 2 to 9 µg l(-1) for the four tetracyclines. After the proposed method was optimized and validated, 25 milk samples of different brands were analyzed, oxytetracycline residues were detected in five samples, in concentrations ranging from 98 to 213 µg l(-1). Subsequent analysis of positive samples by SPE-CE and magnetic solid phase extraction-HPLC revealed than no significant differences were found from results obtained by the proposed methodology. Thus, the developed magnetic extraction is a robust pre-concentration technique that can be coupled to other analytical methods for the quantitative determination of tetracyclines.

Conocimientos y actitudes de la vigilancia en la Atención Primaria de Salud / Knowledge and Attitudes of Surveillance in Primary Health Care

Se realizó una investigación, descriptiva, transversal, con el objetivo de describir el conocimiento y las actitudes presentes en los médicos y enfermeras de la atención primaria en el municipio Nueva Paz en el año 2007. El universo de estudio lo integraron 171 médicos y enfermeras del municipio Nueva Paz. Para la realización de este estudio se aplicaron dos cuestionarios para identificar el conocimiento y las actitudes que sobre la vigilancia en salud posee el equipo básico de salud en la atención primaria de salud, de un total de 184 médicos y enfermeras se encuestaron 171 ya que excluyen los que no se encontraban en el municipio en el periodo,además se realizaron grupos focales en los consejos populares y se aplicaron 22 entrevistas a los líderes formales e informales de la comunidad. Se da una panorámica de otros elementos profundamente relacionados con el tema como es la retroalimentación y la actualización. Se concluyó que existe insuficiente nivel de conocimiento sobre vigilancia en la atención primaria de salud, actitudes inadecuadas del personal médico con relación a la vigilancia, conocimientos y actitudes adecuadas de los licenciados en enfermería sobre las acciones de la vigilancia, deficiente retroalimentación para fortalecer el sistema de vigilancia, no utilización en toda su potencialidad a los lideres formales e informales de la comunidad en el sistema de vigilancia (AU)

A descriptive, transversal investigation was conducted in order to describe the present knowledge and attitudes of doctors and nurses in primary care in Nueva Paz municipality in 2007. The universe of study was composed of 171 doctors and nurses of Nueva Paz municipality. For this study two questionnaires were applied to identify the knowledge and attitudes that has the basic health team in primary health care about health surveillance, from a total of 184 doctors and nurses, 171 were interviewed because it was excluded those who were not in the municipality during the period, plus focus groups were carried out in the Popular Councils and 22 interviews were applied to formal and informal leaders of the community. An overview of other elements deeply related to the subject is given as feedback and update. It was concluded that there is insufficient level of knowledge on surveillance in primary health care, inadequate medical staff attitudes regarding surveillance, adequate knowledge and attitudes of licentiates in nursing on surveillance measures, poor feedback to strengthen the surveillance system, non use of the full potential of formal and informal leaders of the community in the surveillance system (AU)

Comportamiento de la Bioseguridad en un área de salud / Behavior of Biosecurity in a health area

La emergencia y reemergencia de enfermedades infecciosas, unido al uso deliberado de agentes biológicos en los últimos años, constituyen un riesgo biológico inminente para el personal que labora en las instituciones de salud y para la comunidad. El incremento de los servicios de salud a nivel de la Atención Primaria convierte esta en un área de importancia para la Salud Ocupacional. Se realizó un estudio descriptivo de corte transversal en el Policlínico Universitario Luís Li Trijent con el objetivo de diagnosticar la situación actual relacionada con la Bioseguridad identificando los conocimientos que sobre esta temática poseen los trabajadores de los departamentos de mayor riesgo biológico, así como el cumplimiento de las medidas de Precaución Universal. Se aplicó una encuesta a 61 trabajadores y una guía de observación. Como resultado del diagnóstico se determinó que el 65 por ciento de lo encuestados tienen conocimientos limitados sobre Bioseguridad, el 57,3 por ciento refirió no haber recibido ninguna información sobre la Seguridad Biológica y solo el 29,5 por ciento mencionó la charla educativa como única opción de adquisición de la información. El 57,3 cumple menos del 30 por ciento de las medidas de Precaución Universales encontrándose en el nivel I. Se consideró necesario elevar la cultura de seguridad a nivel de la Atención Primaria de Salud (AU)

The emergence and reemergence of infectious diseases, together to the deliberate use of biological agents in the last years, constitutes an imminent biological risk for the personnel that works in the institutions of health and for the community. The increment of health services at level of Primary Care transforms this into an area of importance for the Occupational Health. A descriptive, transversal study was carried out in Luís Li Trijent University Polyclinic with the objective of diagnosing the current situation related with Biosecurity, identifying the knowledge that possess the workers of the departments with more biological risks about this thematic, as well as the execution of the measures of Universal Caution. A survey was applied to 61 workers and an observation guide. As a result of the diagnosis it was determined that 65 per cent of the interviewed ones have limited knowledge on Biosecurity, 57,3 per cent referred not to have received any information about Biological Security and only 29,5 per cent mentioned the educational chat as the only option of acquisition of information. The 57,3 per centcomply with less than 30 per cent of the Universal Measures of Caution being in level I. It was considered necessary to elevate the culture of security at level of the Primary Health Care

Susceptibilidad antimicrobiana en cepas de Pseudomonas Aeruginosa aisladas de pacientes con otitis externa aguda / Antimicrobian susceptibility in stumps of aerignosis paseudomonas isolated in patients with acute external otitis

Las infecciones producidas por Pseudomonas aeruginosa causan altas tasas de morbimortalidad en pacientes con factores predisponentes. Se realizó un estudio descriptivo - retrospectivo en el laboratorio de Microbiología Clínica del Centro Municipal de Higiene y Epidemiología de Güines, en el período comprendido de enero del 2004 a diciembre del 2005, con el objetivo de conocer la susceptibilidad antimicrobiana en 160 cepas de Pseudomonas aeruginosa aisladas de pacientes otitis externa aguda,frente a 14 drogas antimicrobianas. Se apreció valores de sensibilidad superiores al 80 porciento para las drogas azlocilina, ticarcilina, amikacina y gentamicina y de 71,2 porciento para la ceftazidima. El 40,6 porciento de las cepas presentó resistencia al trimetoprim sulfametoxazol. Los resultados de este estudio indican que es necesario continuar la vigilancia de la susceptibilidad de los microorganismos a los agentes antibacterianos, para guiar la terapia antimicrobiana de forma empírica (AU)

Biosorption of cadmium, copper, lead and zinc by inactive biomass of Pseudomonas Putida.

The accumulation of Cd(II), Cu(II), Pb(II) and Zn(II) at mg L(-1) concentration levels by inactive freeze-dried biomass of Pseudomonas Putida has been investigated. These metals could be efficiently removed from diluted aqueous solutions. A contact time of 10 min was sufficient to reach equilibrium. The pH has a strong effect on metal biosorption and the optimal pH values were 6.0, 5.0-6.0, 6.0-6.5 and 7.0-7.5 for Cd(II), Cu(II), Pb(II) and Zn(II) respectively. Under these conditions there was 80% removal for all metals studied. The process of biosorption can be described by a Langmuir-type adsorption model. This model accounts for 98% of the data variance. The K(A) and q(max) parameters for each metal are strongly correlated (at confidence levels greater than 98%) with the metal acidity, quantified by the constant of the corresponding M(OH)(+) complex, thus confirming previous assertions by other authors.