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Search Results: 1 - 10 of 221125 matches for " C. Bosch Ojeda "
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Preconcentration of Cadmium in Environmental Samples by Cloud Point Extraction and Determination by FAAS  [PDF]
C. Bosch Ojeda, F. Sánchez Rojas, J. M. Cano Pavón
American Journal of Analytical Chemistry (AJAC) , 2010, DOI: 10.4236/ajac.2010.13016
Abstract: Cloud point extraction (CPE) has been used for the preconcentration of cadmium, after the formation of a complex with 1, 5-bis(di-2-pyridylmethylene) thiocarbonohydrazide (DPTH), and further determination by flame atomic absorption spectrometry (FAAS) using Triton X-114 as surfactant. The main factors affecting the CPE, such as concentration of Triton X-114 and DPTH, pH, equilibration temperature and incubation time, were optimized for the best extract efficiency. Under the optimum conditions i.e., pH 5.4, [DPTH] = 6x10-3%, [Triton X-114] = 0.25% (v/v), an enhancement factor of 10.5 fold was reached. The lower limit of detection (LOD) obtained under the optimal conditions was 0.95 μg L?1. The precision for 8 replicate deter- minations at 20 and 100 μgL?1 Cd were 2.4 % and 2 % relative standard deviation (R.S.D.). The calibration graph using the preconcentration method was linear with a correlation coefficient of 0,998 at levels close to the detection limit up to at least 200 μgL?1. The method was successfully applied to the determination of cadmium in water, environmental and food samples and in a BCR-176 standard reference material.
Microwave Assisted Acid Digestion of Biomorphic Ceramic Obtained from Cedar Wood Infiltrated with ZrO2  [PDF]
F. Sánchez Rojas, C. Bosch Ojeda, J. M. Cano Pavón
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.21007
Abstract: This work proposes the use of experimental design for optimization of microwave-assisted digestion of bio- morphic ZrO2-ceramic. Cedar wood is used as template and it was infiltrated with ZrO2 via sol-gel process. XPS, SEM and XRD have been used to verify the effectiveness of the synthesis. The effects of different combination of acids in the digestion of this sample have been optimized taking as response the concentra- tion of several metallic ions measured by ICP-MS.
Determination of rhodium and platinum by electrothermal atomic absorption spectrometry after preconcentration with a chelating resin
Sánchez Rojas, F.;Bosch Ojeda, C.;Cano Pavón, J.M.;
Journal of the Brazilian Chemical Society , 2007, DOI: 10.1590/S0103-50532007000600024
Abstract: the present publication describes a separation/preconcentration procedure for the subsequent trace analysis of rhodium and platinum in environmental samples. a chelating ion-exchange resin was employed for this purpose and an automatic on-line flow injection electrothermal atomic absorption spectrometry (fi-et-aas) method was used for the determination of trace amounts of rh and pt in different materials. the solutions are simultaneously treated and the ions determined sequentially. detection limits of rhodium and platinum are 0.8 and 1.0 ng ml-1, respectively. linearity was obtained in the range 0-50 ng ml-1 for rhodium and 0-100 ng ml-1 for platinum. the relative standard deviations were 1.8% for 10 ng ml-1 of rh and 1.6% for 10 ng ml-1 of pt. enrichment factors were 20 for rh and 14 for pt.
Determination of Cobalt in Food, Environmental and Water Samples with Preconcentration by Dispersive Liquid-Liquid Microextraction  [PDF]
Catalina Bosch Ojeda, Fuensanta Sánchez Rojas, José Manuel Cano Pavón
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.32018
Abstract: A new method for the determination of cobalt was developed by dispersive liquid-liquid microextraction preconcentra-tion and flame atomic absorption spectrometry. In the proposed approach, 1,5-bis(di-2-pyridyl) methylene thiocarbohydrazide (DPTH) was used as a chelating agent, and chloroform and ethanol were selected as extraction and dispersive solvents. Some factors influencing the extraction efficiency of cobalt and its subsequent determination, including extraction and dispersive solvent type and volume, pH of sample solution, concentration of the chelating agent, and extraction time, were studied and optimized. Under the optimum conditions, a preconcentration factor of 8 was reached. The detection limit for cobalt was 12.4 ng?mL–1, and the relative standard deviation (RSD) was 3.42% (n = 7, c = 100 ng?mL–1). The method was successfully applied to the determination of cobalt in food, environmental and water samples.
Recent Development in Optical Chemical Sensors Coupling with Flow Injection Analysis
Catalina Bosch Ojeda,Fuensanta Sánchez Rojas
Sensors , 2006, DOI: 10.3390/s6101245
Abstract: Optical techniques for chemical analysis are well established and sensors based on thesetechniques are now attracting considerable attention because of their importance in applications suchas environmental monitoring, biomedical sensing, and industrial process control. On the other hand,flow injection analysis (FIA) is advisable for the rapid analysis of microliter volume samples and canbe interfaced directly to the chemical process. The FIA has become a widespread automatic analyticalmethod for more reasons; mainly due to the simplicity and low cost of the setups, their versatility, andease of assembling. In this paper, an overview of flow injection determinations by using opticalchemical sensors is provided, and instrumentation, sensor design, and applications are discussed. Thiswork summarizes the most relevant manuscripts from 1980 to date referred to analysis using opticalchemical sensors in FIA.
Factores involucrados en el proceso de toma de decisiones en bibliotecas de tama o medio y peque o. Resultados del Proyecto Decimal
Bosch, M.,Espeit, C.
Revista Espa?ola de Documentación Científica , 1999,
Abstract: The article presents the research results of the DECIMAL European project. The aim of the project is to produce an integrated decision support module for library management systems used in small and medium size libraries. The quantitative and qualitative research carried out in United Kingdom, Italy and Spain has been based on a combination of different methods: literature review, interviews, questionnaires and discussion groups during both presentation workshops held. Two basic research lines are discerned: the first one involving the real use of performance measures and indicators in management and evaluation of the library activities, and also their potential interest in the case they have not been applied to the present, and the second one involving the type of decisions most frequantly made in libraries and the issues that influence decision-making process (information sources used, organizational culture, training, satisfaction level). The article has been centered in the results obtained in Spanish libraries, but the general results are also mentioned in order to be compared. The conclusions of the study have resulted in the user requirement specification, as a first step in the design of the decision support module. The project has concluded with a prototype evaluation phase organised as an iterative testing of the prototypes and successive software modifications. The development of four versions of the module has resolved the problems identified earlier in the evaluation process. Se presentan los resultados de la investigación realizada en el marco del proyecto europeo DECIMAL, que tiene como objetivo el desarrollo de un módulo integrado de soporte de la toma de decisiones para sistemas automatizados usados en bibliotecas peque as y medianas. La investigación cuantitativa y cualitativa llevada a cabo en el Reino Unido, Italia y Espa a se ha basado en una combinación de diversos métodos: revisión de la literatura, entrevistas semiestructuradas, cuestionarios y grupos de discusión en ocasión de los dos seminarios de presentación realizados. Se distinguen dos líneas básicas de investigación: la primera en torno a la utilización real de indicadores y medidas para la gestión y evaluación de la actividad del centro, así como su interés potencial en el caso que no se hayan aplicado por el momento, y la segunda en torno al tipo de decisiones más habituales en los centros y los factores que inciden en este proceso (fuentes de información utilizadas, cultura institucional, formación, nivel de satisfacción). El artículo está centrado en los resultados obt
Historia y redescripción de la angustia clínica
Ojeda,César;
Revista chilena de neuro-psiquiatría , 2003, DOI: 10.4067/S0717-92272003000200002
Abstract: we present a brief history of the concept of neurosis, its stability throughout time, and complete inclusion of dsm-iv anxiety disorders. we also present a descriptive reformulation of clinical anxiety, in which two distinct dimensions are relevant: anxiety in front of nature, and anxiety related to interpersonal encounter.
Karl Jaspers: amor, destino y libertad
Ojeda,César;
Revista chilena de neuro-psiquiatría , 2000, DOI: 10.4067/S0717-92272000000300003
Abstract: this paper presents some of the most relevant biographical moments of german psychiatrist and philosopher karl jaspers (1883-1969), along with the central aspects of his philosophy.
Ignacio Matte Blanco, Armando Roa Rebolledo y Juan Marconi Tassara: tres creadores en la psiquiatría chilena
Ojeda,César;
Revista chilena de neuro-psiquiatría , 2001, DOI: 10.4067/S0717-92272001000300002
Abstract: this work presents the main aspects of the theoretical and clinical creations of ignacio matte, armando roa and juan marconi, three of the most outstanding chilean psychiatrists of the second half of the xxth century. they developed important and original contributions in psychodynamical, phenomenological and social aspects of psychiatry, respectively. the aim of this paper is to make available to the latter generations of chilean psychiatrists a selected part of the important contributions of the mentioned authors
Francisco Varela y las ciencias cognitivas
Ojeda,César;
Revista chilena de neuro-psiquiatría , 2001, DOI: 10.4067/S0717-92272001000400004
Abstract: biologist francisco varela worked in the fields of neurobiology, theoretical biology, epistemology, and especially, at the last, in cognitive neurosciences. he was director of research at the national institute for scientific research in france and director of the laboratory of cognitive neurosciences of la salpêtrière hospital in paris. this article refers to three of his main works: conna?tre: les sciences cognitives; the embodied mind, and ethical know-how(1, 2, 3). this article seeks to present the author's main ideas on cognition as an "enactive" process and to comment on its implications
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