1,400 research outputs found

    Evolutionary position of Peruvian land snails (Orthalicidae) among Stylommatophora (Mollusca: Gastropoda)

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    Los géneros Bostryx y Scutalus (Orthalicidae: Bulimulinae) son endémicos de América del Sur y están principalmente distribuidos en la vertiente occidental de los Andes del Perú. El objetivo del presente trabajo fue evaluar su posición evolutiva dentro de los gastrópodos Stylommatophora basada en el marcador mitocondrial 16S rRNA. Fueron obtenidas cuatro secuencias las que, junto con 28 de otros Stylommatophora disponibles en el GenBank, fueron alineadas con ClustalX. La reconstrucción filogenética se realizó mediante los métodos de Neighbor-Joining, Máxima Parsimonia, Máxima Verosimilitud e Inferencia Bayesiana. El alineamiento resultó en 371 sitios, con presencia de indels. Los dos géneros de la Familia Orthalicidae por primera vez incluidos en una filogenia molecular (Bostryx y Scutalus), formaron un grupo monofilético con otro miembro de la superfamilia Orthalicoidea (Placostylus), tal como lo obtenido con marcadores nucleares. Se discute también su relación evolutiva con otros caracoles terrestres.The genera Bostryx and Scutalus (Orthalicidae: Bulimulinae) are endemics from South America. They are mainly distributed on the western slopes of the Peruvian Andes. The goal of the present work was to assess their evolutionary position among the stylommatophoran gastropods based on the 16S rRNA mitochondrial marker. Four sequences were obtained, and along with 28 sequences of other Stylommatophora retrieved from the GenBank, were aligned with ClustalX. The phylogenetic reconstruction was carried out using the methods of Neighbor-Joining, Maximum Parsimony, Maximum Likelihood and Bayesian inference. The multiple sequence alignment had 371 sites, with indels. The two genera of the family Orthalicidae for the first time included in a molecular phylogeny (Bostryx and Scutalus), formed a monophyletic group along with another member of the superfamily Orthalicoidea (Placostylus), result that is comparable with that obtained with nuclear markers. Their evolutionary relationship with other land snails is also discussed

    The BRISA process as a path for efficient copper recovery from waste PCBs

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    In the present work, a two-stage biohydrometallurgical process for copper extraction from waste PCBs is developed. The main goal of this study is to check whether to separate the chemical leaching of copper with ferric iron from the regeneration of the leaching agent by bacterial oxidation of the ferrous iron is an efficient route for copper recovery from waste PCBs. To test this proposal, large waste PCBs pieces were retained in a stirred tank reactor (STR) in contact with a leaching liquor circulating at a high flow rate between this STR and a bioreactor. The kinetics of leaching of large PCB pieces, when ferric iron is added in excess over the stoichiometric requirements, is limited by the rate of mass transfer of the leaching agent. A heterogeneous kinetic model was proposed to fit the experimental data. It was also found that by increasing the ferric iron concentration the leaching rate was increased. Process separation has proven to be a promising configuration in which the productivity of the bioreactor has fulfilled the leaching agent demand and 90% of copper extraction was achieved in 48 h for large waste PCBs

    Endoscopic treatment (endoscopic balloon dilation/self-expandable metal stent) vs surgical resection for the treatment of de novo stenosis in Crohn's disease (ENDOCIR study): an open-label, multicentre, randomized trial

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    Crohn Disease; Self expandable metallic stents; Gastric dilatationEnfermedad de Crohn; Stents metálicos autoexpandibles; Dilatación gástricaMalaltia de Crohn; Pròtesis de stent; Dilatació gàstricaBackground: Stenosis is one of the most common complications in patients with Crohn's disease (CD). Endoscopic balloon dilation (EBD) is the treatment of choice for a short stenosis adjacent to the anastomosis from previous surgery. Self-expandable metal stents (SEMS) may be a suitable treatment option for longer stenoses. To date, however, there is no scientific evidence as to whether endoscopic (EBD/SEMS) or surgical treatment is the best approach for de novo or primary stenoses that are less than 10 cm in length. Methods/design: Exploratory study as "proof-of-concept", multicentre, open-label, randomized trial of the treatment of de novo stenosis in the CD; endoscopic treatment (EBD/SEMS) vs surgical resection (SR). The type of endoscopic treatment will initially be with EDB; if a therapeutic failure occurs, then a SEMS will be placed. We estimate 2 years of recruitment and 1 year of follow-up for the assessment of quality of life, costs, complications, and clinical recurrence. After the end of the study, patients will be followed up for 3 years to re-evaluate the variables over the long term. Forty patients with de novo stenosis in CD will be recruited from 15 hospitals in Spain and will be randomly assigned to the endoscopic or surgical treatment groups. The primary aim will be the evaluation of the patient quality of life at 1 year follow-up (% of patients with an increase of 30 points in the 32-item Inflammatory Bowel Disease Questionnaire (IBDQ-32). The secondary aim will be evaluation of the clinical recurrence rate, complications, and costs of both treatments at 1-year follow-up. Discussion: The ENDOCIR trial has been designed to determine whether an endoscopic or surgical approach is therapeutically superior in the treatment of de novo stenosis in CD.This study received a grant (FSEED; ) from the Spanish Society of Digestive Endoscopy in 2022. Taewoong provided the stents for the study free of charge, but had no role in the study design, data collection, data analysis, data interpretation, or writing of the report

    Copper recovery from unground printed circuit board by biogenic ferric at high solid/liquid ratio

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    In this work, the recovery of Cu from large waste printed circuit board (PCB) pieces by biogenic ferric sulphate at high solid to liquid ratio was studied. PCB parts were packed in a column and biogenic ferric was constantly recirculated. A high oxidation reduction potential (ORP) decrease was observed in ferric leaching due to ferric ion consumption; this drop caused a slower copper dissolution kinetics. After 25 days, 62.2% of copper was leached from PCBs column. PCBs column was connected to a flooded packed-bed (FPB) bioreactor to study the biological regeneration of ferric ion consumed in chemical reaction. The bioreactor connection enabled working at a constant ORP (700 mV vs. Ag/AgCl) during the whole test time. The improvement of oxidising conditions hugely increased copper dissolution rate, reaching 90% of copper recovery after 25 days. The FPB bioreactor operated continuously without showing inhibition problems and generating a leaching liquor with a high and constant ORP. The novel proposed configuration consists of a chemical reactor, where large PCBs pieces are piled at a high solid load, connected to a FPB bioreactor that regenerates the spent ferric ion enabling the leaching without reagents consumption, is a simple, inexpensive, low energy consumption, eco-friendly and effective system to recover copper from PCBs

    The reprocessing of hydrometallurgical sulphidic tailings by bioleaching: the extraction of metals and the use of biogenic liquors

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    Mineralurgical and metallurgical processes generate a large amount of harmful residues. These wastes usually contain a considerable fraction of sulphides and a low percentage of target metals. Due to their characteristics, the main environmental issues concern the acid mine drainage generation and the release of metals. The bioleaching of these tailings can be considered as a win–win process due to the controlled oxidation of sulphides avoids the main environmental issues, while target metals can be recovered. In this work, a residue composed of pyrite (50.4%) and quartz, containing various non-ferrous metals, was reprocessed by bioleaching and brine leaching. Copper and zinc sulphides exhibited a refractory behaviour in bioleaching due to these tailings were previously leached, being the dissolution rate controlled by mass transfer. Cobalt is directly related to the pyrite matrix, requiring the removal of pyrite to extract it. Pyrite dissolution was also controlled by mass transfer, increasing the dissolution rate when the bioreactor conditions were improved. After 10 days of bioleaching in a stirred tank reactor, 87.2% Co, 43.6% Zn, 40.4% Cu, and 96.0% FeS2 were dissolved. In addition, after bioleaching, 55.9% Pb and 37.9% Ag were dissolved through chloride leaching with moderate conditions (100 g/L NaCl, 10 g/L H2SO4, 60 ◦C, and 1 h). Considering the metals extraction and the saving in management costs of tailings, the reprocessing of these tailings was not economically feasible due to the low grade of target metals. Nonetheless, during bioleaching, a great amount of ferric ion and sulphuric acid was released that could be used in the hydrometallurgical circuit as leaching liquor. This saving increased the revenues from tailings reprocessing, obtaining an internal rate of return of 10% with a feed rate of 260 t/d.Universidad de Sevilla - VI PPI

    Heterogeneous Olefin Aziridination Reactions Catalyzed by Polymer-Bound Tris(triazolyl)methane Copper Complexes

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    Efficient olefin aziridination has been achieved with a tris(triazolyl)methane copper catalyst supported onto polystyrene. Aryl, alkyl and methoxycarbonyl-substituted olefins are converted into N-tosylaziridines in good to high yields. The solid catalyst is readily separated by filtration and recycled, allowing its reuse with no significant loss of the catalytic activity

    Temáticas prosociales e impacto de una intervención educativa Flipped Classroom relacionada con la promoción de la salud mediante la creación relatos audiovisuales

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    La creación de propuestas educativas que incentivan los actos prosociales, relacionados con la promoción de la salud, son fundamentales para proporcionar una mejor calidad de vida a la población. En este sentido, es importante sensibilizar a los adolescentes en determinadas acciones prosociales, que les puedan ayudar además en su formación a nivel personal. El objetivo de esta intervención educativa, basada en la metodología Flipped Classroom, es que los adolescentes se formen sobre trasplante y donación de órganos mediante la creación de relatos audiovisuales sobre temáticas relacionadas con el tema, con el fin de mejorar su conocimiento. Para ello los adolescentes pudieron visualizar once entrevistas que explicaban los temas más importantes del trasplante y de la donación de órganos. Se presentaron más de 60 relatos audiovisuales. La propuesta fue bien aceptada y las temáticas trabajadas demostraron una gran asimilación de los conceptos básicos sobre trasplante y donación de órganos

    Autores citados en los trabajos españoles de cirugía digestiva (1991-1995)

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    The references contained in the 483 surgical papers published by Revista Española de Enfermedades Digestivas (1991-1995) were analysed with the aim of identifying the scientific influences exercised on Spanish authors in digestive surgery. The authors cited were distributed in decreasing order of the number of citations. This distribution was compared with the theoretical one postulated by Lotka, and with that obtained when only the first author of the cited papers was considered. 23,326 citations to 15,886 different authors were taken from 8,125 references. The distribution of the cited authors and the number of citations per author follows the expression Ac=13931c-2.9 and the citations to the first author of the cited papers to Ac=6515.8c-3.23 . Both expressions show that there exists a wide spread of citations in authors with little influence. The high influence of Spanish authors on themselves is confirmed: the most cited author is a Spaniard, as are 3 of the 5 most cited authors and 6 of the 20 most cited authors. Seven (one of them Spanish) of these 20 authors don't have collaboration with the rest, and the other 13 are organised in five scientific teams, two of which are Spanish.Para identificar las influencias científicas ejercidas sobre los autores españoles en cirugía digestiva, se analizaron las referencias contenidas en los 483 artículos de cirugía publicados en Revista Española de Enfermedades Digestivas entre 1991 y 1995. Los autores citados fueron distribuidos en orden decreciente del número de citas recibidas y esta distribución fue comparada con la teórica de Lotka y con la obtenida cuando se considera exclusivamente al primer firmante del artículo citado. Hemos obtenido 23.326 citas a 15.886 autores distintos, procedentes de 8.125 referencias. La distribución de autores y citas por autor se ajusta a la expresión Ac = 13931c-2,9, y las citas a primeros firmantes a la expresión Ac = 6515,8c-3,23 ; ambas indican una alta dispersión de citas entre autores escasamente influyentes. Se confirma la elevada influencia de los autores españoles, ya que son de esta nacionalidad el más citado, tres de los cinco autores más citados y seis de los 20 más citados. De estos 20 autores, siete (uno español) no colaboran con el resto, y los otros 13 se organizan en cinco equipos de trabajo, dos de ellos españoles

    Análisis de las causas del retraso en graduación de estudiantes en cinco universidades de Latinoamérica

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    El retraso en la graduación de estudiantes de pregrado es una dimensión importante del abandono en la educación superior. Actualmente, son escasos y locales los estudios que analizan el fenómeno de retraso en graduación en la educación universitaria. En ese sentido, nuestro estudio es el primero en Latinoamérica que analiza las causas del retraso en la graduación en diferentes países del continente. En consecuencia, nuestro estudio tiene como objetivo analizar qué factores causan el retraso en la graduación de estudiantes de pregrado en cinco universidades de Latinoamérica. Para el logro de ese objetivo se desarrolló un cuestionario estandarizado de 106 preguntas que fue implementado a estudiantes de los últimos semestres que se encontraban en condición de graduación en universidades de Argentina, Bolivia, Chile, Colombia y México. Como resultado de la implementación del cuestionario se recolectaron 480 encuestas en los países bajo análisis. Mediante reducción dimensional (análisis factorial exploratorio con Paralell Analysis y rotación Varimax) se identificó la existencia cinco factores que representaban adecuadamente las respuestas de los cinco países: (a) problemas de retraso en graduación (4 ítems); (b) asesoramiento del tutor (3 ítems); (c) problemas personales del estudiante (2 ítems); (d) conocimientos de investigación (3 ítems); y (e) falta de servicios de apoyo de la universidad (2 ítems). Debido a que las encuestas realizadas pertenecen a países con historias, economías, geografías y culturas diferentes, se analizó la equivalencia de las mediciones mediante pruebas de invarianza factorial. Como resultado de las pruebas de invarianza factorial se determinó que la estructura factorial obtenida cumple criterios de invarianza configural y métrica. Este resultado sugiere que la estructura factorial obtenida es común en todos los países y los resultados obtenidos son generalizables. A continuación, se implementó análisis de ecuaciones estructurales y se encontró que los factores bajo estudio determinan los problemas relacionados con retraso en graduación. Luego, se realizaron pruebas de moderación con las variables: (a) género; (b) estado civil; (c) estudiante-trabajador; (d) asistencia a clases; (e) tipo de colegio de origen; (f) cambio de estado civil durante su carrera; (g) cambio de estado civil durante la tesis; (f) tiene hijos; y (g) semestre de estudio. Como resultado del análisis se encontró que cuando el estudiante trabaja, el tutor no influencia significativamente en la reducción de los problemas de retraso en graduación. Posteriormente se implementaron arboles de decisión con el algoritmo Exhaustive CHAID para determinar el grado de importancia de las variables bajo análisis. Como resultado del análisis se encontró que los problemas personales de los estudiantes son el predictor más importante de los problemas de retraso en graduación seguidos por la falta de servicios de apoyo de la universidad. Estos resultados sugieren que la decisión secuencial de abandonar o continuar en la universidad se encuentra relacionada con la reducción gradual de la incertidumbre del programa académico para poder graduarse a tiempo. En consecuencia, para reducir el abandono, las universidades latinoamericanas deberían: (a) prestar atención a la salud psicológica de sus estudiantes; (b) mejorar los sistemas institucionales de selección y asignación de tutores; (c) mejorar las competencias de investigación de sus estudiantes; (d) fortalecer los servicios de apoyo a estudiantes en condición de retraso; y (e) brindar apoyo académico y/o económico a los estudiantes que trabajan

    Cord blood-derived CD34+ hematopoietic cells with low mitochondrial mass are enriched in hematopoietic repopulating stem cell function

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    This work was funded by the CICE/FEDER (P08-CTS-3678) de la Junta de Andalucia with a grant to PM, the FIS/FEDER (PI10/00449 to PM and PI11/00119 to CB), the MICINN (Fondo Especial del Estado para Dinamizacion de la Economia y Empleo/PLE-2009-0111) with a grant to PM, and the Foundation "Spanish Association Against Cancer"/Junta Provincial de Albacete (CI110023 to PM). DRM (PFIS scholarship FI11/0511), RM and CB (CP07/0059) are supported by the ISCIII. ON-M was supported by the Health of Department of the Junta de Andalucia.The homeostasis of the hematopoietic stem/progenitor cell pool relies on a fine-tuned balance between self-renewal, differentiation and proliferation. Recent studies have proposed that mitochondria regulate these processes. Although recent work has contributed to understanding the role of mitochondria during stem cell differentiation, it remains unclear whether the mitochondrial content/function affects human hematopoietic stem versus progenitor function. We found that mitochondrial mass correlates strongly with mitochondrial membrane potential in CD34(+) hematopoietic stem/progenitor cells. We, therefore, sorted cord blood CD34(+) cells on the basis of their mitochondrial mass and analyzed the in vitro homeostasis and clonogenic potential as well as the in vivo repopulating potential of CD34(+) cells with high (CD34(+) Mito(High)) versus low (CD34(+) Mito(Low)) mitochondrial mass. The CD34(+) Mito(Low) fraction contained 6-fold more CD34(+)CD38(-) primitive cells and was enriched in hematopoietic stem cell function, as demonstrated by its significantly greater hematopoietic reconstitution potential in immuno deficient mice. In contrast, the CD34(+) Mito(High) fraction was more enriched in hematopoietic progenitor function with higher in vitro clonogenic capacity. In vitro differentiation of CD34(+) Mito(Low) cells was significantly delayed as compared to that of CD34(+) Mito(High) cells. The eventual complete differentiation of CD34(+) Mito(Low) cells, which coincided with a robust expansion of the CD34(-) differentiated progeny, was accompanied by mitochondrial adaptation, as shown by significant increases in ATP production and expression of the mitochondrial genes ND1 and COX2. In conclusion, cord blood CD34(+) cells with low levels of mitochondrial mass are enriched in hematopoietic repopulating stem cell function whereas high levels of mitochondrial mass identify hematopoietic progenitors. A mitochondrial response underlies hematopoietic stem/progenitor cell differentiation and proliferation of lineage-committed CD34(-) cells.Junta de Andalucia P08-CTS-3678European Union (EU) Instituto de Salud Carlos III PI10/00449 PI11/00119MICINN (Fondo Especial del Estado para Dinamizacion de la Economia y Empleo) PLE-2009-0111Foundation "Spanish Association Against Cancer"/Junta Provincial de Albacete CI110023Instituto de Salud Carlos III FI11/0511 CP07/0059ICRE
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