Mostrando recursos 161 - 180 de 61,794

  1. Ezequiel Uricoechea en Europa: del naturalismo a la filología

    Botero, Clara Isabel
    Ezequiel Uricoechea, uno de los grandes científicos colombianos del siglo XIX, reunió la doble condición de naturalista y de filólogo. Como naturalista se dedicó al estudio de la química y la mineralogía, trabajó también sobre etnografía y arqueología colombianas: como filólogo se interesó por e l español además de rescatar y publicar gramáticas y vocabularios de lenguas indígenas y ser el primer catedrático de lengua árabe en una universidad europea. Su profunda inquietud por el saber lo llevó también a realizar trabajos en cartografía y numismática y editar diccionarios biográficos y bibliografías americanistas y colombianas.

  2. La radiactividad al servicio de la cronología

    Zarco de Gea, Juan
    Como es sabido, la radiactividad puede ser de dos clases: natural y artificial. La primera, conocida desde hace más de 60 años, se encuentra en los elementos químicos más pesados, como el uranio, radio, torio y actinio.La segunda se encuentra en los llamados radioisótopos, obtenidos artificialmente ya sea por bombardeo electrónico en los ciclotrones, ya también en las pilas atómicas. Este trabajo lo limitaremos a los radioelementos naturales.

  3. Desarrollo y aplicación de materiales virtuales en español y en inglés para un curso de Química Analítica

    Palacios Santander, J. M.; Milla González, Miguel; Bellido Milla, Dolores; Hidalgo Hidalgo De Cisneros, José Luis; Naranjo Rodríguez, Igancio; Cubillana Aguilera, Laura
    The main objective of this work consists of the creation of an INTERACTIVE COURSE OF ANALYTICAL CHEMISTRY based on the development of a broad set of virtual teaching resources, in many cases translated to English, and supported on the new Information and Communication Technologies (ICT), aimed mainly at students of the Degree in Chemistry. However, it also intends to be a useful tool for other students of science in general, as well as for teachers and professionals belonging to the scientific-technological field who are non-specialist in Analytical Chemistry, but need to know some basics and applications of this issue. The...

  4. Adición de polielectrolitos sobre la fase acuosa de un suelo sulfatado ácido interior de Cordoba, Colombia

    Mercado, Jaime L.; Combatt, Enrique Miguel; Palencia, Manuel S.
    El uso de polímeros, en particular polielectrolitos (PELs), en suelos se ha enfocado principalmente en el incremento de la capacidad de almacenamiento y uso efiiente del agua, aumento de la velocidad de infitración, reducción de la frecuencia de irrigación, control de la erosión, disminución de las perdidas por escurrimiento de aguas y aumento de su utilidad para la siembra de cultivos. El objetivo de este trabajo fue determinar el efecto de la adición de polielectrolitos sobre la composición química de la fase acuosa del suelo de Suelos Sulfatados Ácidos (SSA). Para eso, SSA diferentes fueron recolectadas e incubadas con soluciones...

  5. La Monitorización Biológica: una herramienta para la evaluación del riesgo químico en el trabajo

    Casal Lareo, Amparo
    La exposición a sustancias químicas durante el trabajo puque puede influenciar en la absorcion de la sustancia en su excrecion y consecientemente en los efectos derivados.o sus metaboliede comportar un efecto tóxico alterando el estado de salud de los trabajadores expuestos. El riesgo de provocarlo depende principalmente de la cantidad de sustancia que penetra en el organismo (dosis interna). La monitorización biológica es una herramienta fundamental en la evaluación del riesgo químico en Salud laboral, ya que cuantifica la dosis interna, permite la identificación de la fuente de exposición, evidencia las diferencias existentes entre los trabajadores en relación a  la...

  6. Los reglamentos REACH-CLP y la prevención del riesgo químico

    Guardino Solá, Xavier
    En el presente artículo se revisa la actual legislación europea sobre productos químicos basada en el Reglamento REACH (Registry, Evaluation, Authorisation and Restriction of Chemicals) y su más importante modificación, el Reglamento CLP (Classification, Labelling and Packaging), que representa la incorporación a la legislación europea de sistema GHS (Globally Harmonized System), destinado a lograr una uniformización a nivel mundial de los mecanismos de identificación y comunicación del riesgo químico.Aunque ambos reglamentos no estarán plenamente operativos hasta 2018, su nivel de desarrollo es suficiente para evaluar sus efectos positivos sobre gestión de la prevención frente al riesgo químico desde el punto...

  7. Valoración físico-química y fitotóxica de las aguas residuales depuradas/regeneradas destinadas al riego agrícola

    Pérez Donato, J. A.; Vera, L.; Bravo Sánchez, L. R.; Delgado Díaz, S.; González Cabrera, E.
    The most widespread application of reuse of treated / reclaimed domestic wastewater is agricultural irrigation. The common regulations on quality of reclaimed water for reuse contemplated physicochemical and biological parameters to minimize health risks, but rarely taken into account phytotoxic parameters that may be limiting for agricultural applications. The physicochemical and phytotoxic parameters change to advance the degree of purification / regeneration of wastewater, so it is of interest to know what stage of the installation provides adequate water for irrigation. This paper presents a correlation study of phytotoxicity with physicochemical parameters in water samples taken at the end of each of the stages of conventional treatment of domestic sewage, including biological...

  8. Caracterización química del material particulado PM10 de la zona urbana de Cuenca- Ecuador e investigación de su genotoxicidad e inducción de estrés oxidativo en células epiteliales alveolares A549

    Astudillo Alemán, A. L.; Ramírez Orellana, M. I.; García Alvear, N. B.; González Arévalo, G. J.; Gutiérrez Valle, I. A.; Bailón Moscoso, N. C.
    Exposure to environmental particles is a risk factor that causes damage to human health, such as respiratory and cardiovascular diseases and cancer. The toxicity and inflammatory effects of these particles is related to their size and chemical characteristics. The aim of this study was to determine the chemical characteristics of the aqueous fraction of Particulate Matter PM10, collected in three monitoring sites Cuenca-Ecuador, and to evaluate their genotoxic activity and induction of reactive oxygen species (ROS) in human alveolar epithelial cell line A-549. Samples were collected using a low volume equipment. Particulate matter concentrations determined by gravimetric analysis in the three study points exceeded the 50 ug / m3 limit stated...

  9. Raleio químico de frutos de ameixeira com ethephon

    Pavanello, Alexandre Pozzobom; Ayub, Ricardo Antonio
    Thinning of plum trees promotes balance between vegetative growth and production, increases the fruit size and avoids alternation of production. The objective of this study was to evaluate the effect of different ethephon concentrations as chemical thinning of plum cv. 'Irati' and cv. 'Reubennel', in Arapoti-PR. Five treatments with ethephon were evaluated at dosages (0, 60, 80, 100, 120 μL L-1) in cv. 'Irati' and four treatments at dosages; 0; 60; 80; 120 μL L-1 in cv. 'Reubennel', all applied when fruits diameter was 5 mm followed by measurements plant yield, weight, size, soluble solids, firmness, titratable acidity, pH and...

  10. Estabilidade físico-química e microbiológica de banana passa orgânica

    Batista, Daniele de Vasconcellos Santos; Cardoso, Ricardo Luis; Godoy, Rossana Catie Bueno de; Evangelista Barreto, Norma Suely
    The objective of this study was to evaluate the physical, physico-chemical and microbiological stability of dried organic banana varieties Caipira, Pacovan Ken and Prata Anã, 180 days of storage, as well as adjust the drying curves . The bananas were dried in an oven with forced air circulation at 65 ° C until final humidity of 20-25 % ( wb). The variety Pacovan Ken reached the final moisture after 37h of dehydration . The value of water activity for the three varieties, remained stable at 180 days and features the product as intermediate moisture. Not observed in any treatment, significant...

  11. Composição química de folhas de oliveira ("Olea europaea" L.) da região de Caçapava do Sul, RS

    Cavalheiro, Caroline Viegas; Rosso, Vandrisa Dellinghausen; Paulus, Eloi; Cichoski, Alexandre José; Wagner, Roger; Menezes, Cristiano Ragagnin de; Barin, Juliano Smanioto
    The olive tree (Olea europaea L.) is a plant characteristic of the Mediterranean region that is cultivated in various countries of the world due to the great interest in the production of olives and their oil, which is rich in essential fatty acids. The leaves of the olive tree are an important by-product generated by pruning of trees that have significant amount of phenolic and fatty acids important to health. Given the importance of compounds present in olive leaves and the recent crop in southern Brazil, this study aimed to perform an exploratory study on the proximate composition, total phenolic...

  12. Suscetibilidade de duas Gramas-boiadeiras a diferentes formulações de glyphosate

    Scherner, Ananda; Avila, Luis Antonio de; Schreiber, Fábio; Kruse, Nelson Diehl; Agostinetto, Dirceu; Pinto, Jesus Juares Oliveira; Pestana, Rodrigo Ribeiro
    The use of glyphosate to chemical control of Cutgrass and Peruvian Watergrass with the use of non-selective herbicides has not been efficient. In this context, the investigation of chemical control of these species to glyphosate is very important, since there are not available commercially selective herbicides to control these species in post-emergence of irrigated rice. Therefore, the objective of this study was to evaluate the susceptibility of Cutgrass and Peruvian Watergrass to different formulations of glyphosate. Two factorial experiments were conducted in a greenhouse, in the first the A factor were two formulations of glyhposate (potassium and isopropylamine salt) and...

  13. Caracterização física, química e sensorial de sobremesas à base de soja, elaboradas com mucilagem de chia

    Spada, Jordana C.; Dick, Melina; Pagno, Carlos Henrique; Vieira, Aline Campos; Bernstein, Anahí; Coghetto, Chaline Caren; Marczak, Ligia D.F.; Tessaro, Isabel Cristina; Cardozo, Nilo Sérgio Medeiros; Flôres, Simone H.
    In product development is important to study the influence of ingredients in the physical, chemical and sensory properties of the product. The aim of this study was to characterize soy-based desserts with and without addition of chia mucilage, used as food thickener. The formulations were characterized for their rheological properties, °Brix, pH and color. The sensory profile was determined by Quantitative Descriptive Analysis (QDA) using 10 trained judges. The results regarding to pH, ° Brix and color coordinate a* did not differ. Unlike these parameters, the other chromaticity coordinates and the rheological properties presented significant statistical differences between the samples....

  14. Características físico-químicas del suelo y su asociación con macroelementos en áreas destinadas a pastoreo en el estado yaracuy

    Borges, J. A.; Barrios, Mariana; Sandoval, Espartaco; Bastardo, Yanireth; Márquez, Oswaldo
    The objective of this work was to study the association between phosphorus, calcium and potassium, and physicochemical parameters such as texture, relief, organic matter (OM), pH, and electrical conductivity in soils with pastures in dual purpose production units in Yaracuy State. Soil samples were taken in production units of the municipalities Manuel Monge, Veroes, Bolivar and Nirgua, during the dry period (December 2009-February 2010), at depths of 0-20 cm, which were processed by routine methods of soil fertility analysis. The data were sorted by texture and relief and compared by analysis of variance (Anova) and mean separation by Tukey for chemical variables (OM, pH and...

  15. A família do usuário de drogas no CAPS: um relato de experiência

    Braun, Lori Maria; Dellazzana-Zanon, Letícia Lovato; Halpern, Silvia C.
    The aim of this article was to present an experience report on the treatment provided by a social family therapist to the family of a drug addict in a public mental health center (CAPS). The identified patient, his wife and parents participated in the study. 12 sessions were held during three months Data were collected through family interviews, hospital visits, and home visits. It was observed that the family had little knowledge on chemical dependency. The main feelings reported were shame, guilty and worthlessness. The guarantee of a reserved space for talking about chemical dependency produced considerable changes, generating coherence...

  16. Actividad de un área de descontaminación química de un servicio de urgencias

    Nogué, Santiago; Amigó Tadín, Montserrat; Uría Álvarez, Elisabet; Velasco, Verónica; Fernández, Fuensanta
    Las exposición a productos químicos con contaminación cutánea y/o ocular es un motivo de consulta a urgencias. Se describen las características (epidemiológicas, toxicológicas, clínicas, terapéuticas y evolutivas) de los pacientes atendidos en un área hospitalaria de descontaminación química, durante un periodo de 18 meses. Fueron 36 pacientes, con una media de edad de 42,8 (16,7) años, y de los cuales 24 (66,7%) eran mujeres. Los productos implicados con mayor frecuencia fueron los cáusticos (52,8%), disolventes o desengrasantes (19,4%), pegamentos (13,9%) y sprays de defensa personal (8,3%). Los accidentes domésticos (41,7%) y laborales (36,1%) fueron las causas más frecuentes, pero también hubo agresiones (8,3%) y una tentativa suicida. La afectación...

  17. Análise microestrutural e físico químico do colágeno presente em espinhos intramusculares do peixe Bocachico (Prochilodus sp.)

    Suárez Mahecha, Héctor; Gaitán, Oscar; Diaz, Consuelo
    Background: the presence of intramuscular pin bones hinders the production and commercialization of fish fillet products; however, application of physical processes, such as thermal treatments, offers alternatives for the degradation of said bones. Objective: the present study aimed to conduct a microstructural and physicochemical analysis of Bocachico intramuscular pin bones subjected to a thermal treatment. Methods: collagen extracted from intramuscular pin bones of Bocachico fillets was analyzed using SDS-polyacrylamide gel electrophoresis and viscosity. Pin bones were subjected to 1.5, 2, and 3 minutes heating time and analyzed using electron microscopy and cutting force. Results: intramuscular pin bones contain type I...

  18. Efectos del blanqueamiento dental sobre la morfología, composición química y estructura del diente

    Vallet-Regí, María; Izquierdo Barba, Isabel; Torres Rodríguez, Carolina
    Nowadays, there are a number of very effective methods for the dental bleaching, which typically consist in directly applying oxidizing agents, such as the hydrogen peroxide, to the tooth surface. After bleaching, several research studies have been carried out to evaluate the efficacy and consequences of the treatment with bleaching agents on teeth, existing a great controversy concerning the techniques used and the pre-treatment, requirements, which could alter the final results. The aim of the present study is to evaluate the effect of a treatment with 38% (p/v) hydrogen peroxide during 20 minutes onto morphological, physicochemical, structural and wettability features in the human enamel and dentin. For this purpose, we used instrumental techniques...

  19. Tratamiento de las quemaduras oculares por productos químicos mediante aplicación tópica y subconjuntival de plasma rico en factores regeneradores: estudio comparativo

    Márquez de Aracena, Rafael
    Estudio de la aplicación subconjuntival y tópica de plasma rico en factores regeneradores (PRFR) en pacientes con quemaduras oculares por productos químicos. Se analizaron 15 ojos de 15 pacientes con quemaduras químicas oculares. Se dividieron en tres grupos: uno de control con tratamiento médico clásico; otro con tratamiento médico clásico y tópico de PRFR y un tercero, con tratamiento médico clásico e infiltración subconjuntival de PRFR. Se estudió la evolución clínica de las lesiones y tiempo hasta su curación final. En los grupos con PRFR tópico y subconjuntival hubo un acortamiento de los días de curación frente al grupo control, que fueron significativos para las variables tiempo de...

  20. Linhaça marrom e dourada: propriedades químicas e funcionais das sementes e dos óleos prensados a frio

    Barroso, Ana Karina Mauro; Torres, Alexandre Guedes; Branco, Vanessa Naciuk Castelo; Ferreira, Andrea; Finotelli, Priscilla Vanessa; Freitas, Suely P.; Leão, Maria Helena Miguez da Rocha
    The aim of the study was to compare the chemical composition and antioxidant capacity of the brown and golden flaxseed and their cold-pressed oils, and evaluate the oxidative stability of oils. We determined the chemical composition, total antioxidant capacity and total phenolic compounds of the seeds. In the oils we determined acid and peroxide value, unsaponifiable matter, composition of fatty acids and tocopherols, phenolic compounds, antioxidant capacity and oxidative stability in four storage conditions up to one year. There were no significant differences between the flaxseed types in the analyzed properties and between the oils in terms of yield after...

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