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1.
Psychol Res Behav Manag ; 17: 1417-1431, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38571966

RESUMO

Purpose: A positive leisure attitude among older adults may have a beneficial effect on psychological well-being, both directly and indirectly by fostering a more positive perception of one's health. This paper presents a correlational design that explores associations among leisure attitude, self-rated health, and psychological well-being, and analyzes the potential moderating role of gender in these relationships. Patients and Methods: The sample was selected using simple random probability sampling (N= 409; 61.9% female; Mean age = 72.9; SD = 8.43¸ Range of age 53 to 93 years). Diverse sociodemographic information was collected, and leisure attitudes, self-perceived health, and psychological well-being (positive affect and emotional ties) were assessed. Results: The results revealed a positive effect of leisure attitude on self-rated health and psychological well-being, with self-rated health fully mediating the association between the behavioral component of leisure attitude and psychological well-being. Furthermore, the moderating effect of gender on the relationship between self-rated health and psychological well-being was stronger among men. Conclusion: Positive cognitive and emotional perceptions of leisure among older adults seem to benefit psychological well-being and improve self-rated health, thereby contributing to healthy ageing.

2.
BMJ Open ; 13(7): e064769, 2023 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-37407032

RESUMO

INTRODUCTION: Developing the capabilities of individuals, groups and communities to enhance their health has received a great deal of attention in the literature. One essential source of results is evidence-based intervention programmes, which often involve a number of different variables. This paper describes a methodology for carrying out a scoping review that maps available evidence on randomised controlled trials focusing on health promotion intervention programmes. METHODS AND ANALYSIS: The scoping review protocol follows the general Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Joanna Briggs Institute guidelines. It also incorporates some modifications to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Review flowchart and complements its methodological framework. This new format, called documents, Concept, Studies, Participants, Interventions, Comparator, and Outcomes (d-CoSPICO), guides the review sequence, which is represented in a flowchart. The search will focus on different sources of information using formal (searches in thematic -PubPsych, ERIC, MedLine, PsychINFO- and multidisciplinary databases -Academic Search Ultimate, Core Collection Web of Science, Scopus and ProQuest-, repositories and other websites), informal (contact with researchers), and retrospective (previous reviews on this topic) strategies to identify relevant publications until 2021, including grey literature. Coding, identification, selection, and data extraction will be carried out following the generation of a database in which each retrieved record's content (abstract and/or full text) can be analysed. The review is expected to be completed in 2023. ETHICS AND DISSEMINATION: Ethical approval is not required for this review. The d-CoSPICO framework and the results will be disseminated through (a) peer-reviewed publications; (b) presentations at scientific dissemination events and (c) training activities for applying this protocol.


Assuntos
Academias e Institutos , Promoção da Saúde , Humanos , Estudos Retrospectivos , Bases de Dados Factuais , Literatura Cinzenta , Projetos de Pesquisa , Revisões Sistemáticas como Assunto , Literatura de Revisão como Assunto
3.
Span J Psychol ; 22: E59, 2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31868159

RESUMO

The main aims of this study were, first to analyze the partial effects of specific mechanisms of moral disengagement (MMD) on different manifestations of general aggression and dating violence (DV) in adolescents and youths; second, to explore the moderating effects of gender and age on these relations. Moral disengagement, and different forms of aggression and DV, were evaluated in a sample of 424 participants (61.1% women) aged 15 to 25 years (M = 18.80; SD = 2.69). Pearson correlations and different hierarchical multiple linear regression analyses were conducted. All regressions were controlled by social desirability. MMD contributed to physical aggression with a medium effect size (R2 = .22) and verbal aggression with a small effect size (R2 = .10). Conversely, MMD did not appear to clearly contribute to DV. In conclusion, depersonalization and rationalization were the most important MMD for physical aggression, rationalization for verbal aggression, and irresponsibility for verbal-emotional violence in dating relationships. Moreover, the relationships between physical aggression and rationalization mechanism were significantly moderated by gender: there appears to be a stronger relationship between rationalization and physical aggression in boys than in girls. Moderating effects of age on these relations were not found.


Assuntos
Agressão/psicologia , Despersonalização/psicologia , Relações Interpessoais , Violência por Parceiro Íntimo/psicologia , Princípios Morais , Pensamento , Adolescente , Adulto , Fatores Etários , Feminino , Humanos , Masculino , Fatores Sexuais , Desejabilidade Social , Adulto Jovem
4.
Span. j. psychol ; 22: e59.1-e59.10, 2019. tab
Artigo em Inglês | IBECS | ID: ibc-190210

RESUMO

The main aims of this study were, first to analyze the partial effects of specific mechanisms of moral disengagement (MMD) on different manifestations of general aggression and dating violence (DV) in adolescents and youths; second, to explore the moderating effects of gender and age on these relations. Moral disengagement, and different forms of aggression and DV, were evaluated in a sample of 424 participants (61.1% women) aged 15 to 25 years (M = 18.80; SD = 2.69). Pearson correlations and different hierarchical multiple linear regression analyses were conducted. All regressions were controlled by social desirability. MMD contributed to physical aggression with a medium effect size (R2 = .22) and verbal aggression with a small effect size (R2 = .10). Conversely, MMD did not appear to clearly contribute to DV. In conclusion, depersonalization and rationalization were the most important MMD for physical aggression, rationalization for verbal aggression, and irresponsibility for verbal-emotional violence in dating relationships. Moreover, the relationships between physical aggression and rationalization mechanism were significantly moderated by gender: there appears to be a stronger relationship between rationalization and physical aggression in boys than in girls. Moderating effects of age on these relations were not found


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Assuntos
Humanos , Masculino , Feminino , Adolescente , Adulto Jovem , Adulto , Agressão/psicologia , Despersonalização/psicologia , Relações Interpessoais , Violência por Parceiro Íntimo/psicologia , Princípios Morais , Pensamento , Fatores Etários , Fatores Sexuais , Desejabilidade Social
5.
Anal Biochem ; 550: 34-40, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29649474

RESUMO

This work reports an amperometric enzyme-electrode prepared with glucose oxidase, which have been immobilized by a cross-linking step with glutaraldehyde in a mixture containing albumin and a novel carbon nanotubes-mucin composite (CNT-muc). The obtained hydrogel matrix was trapped between two polycarbonate membranes and then fixed at the surface of a Pt working electrode. The developed biosensor was optimized by evaluating different compositions and the analytical properties of an enzymatic matrix with CNT-muc. Then, the performance of the resulting enzymatic matrix was evaluated for direct glucose quantification in human blood plasma. The novel CNT-muc composite provided a sensitivity of 0.44 ±â€¯0.01 mA M-1 and a response time of 28 ±â€¯2 s. These values were respectively 20% higher and 40% shorter than those obtained with a sandwich-type biosensor prepared without CNT. Additionally, CNT-muc based biosensor exhibited more than 3 orders of magnitude of linear dynamic calibration range and a detection limit of 3 µM. The short-term and long-term stabilities of the biosensors were also examined and excellent results were obtained through successive experiments performed within the first 60 days from their preparation. Finally, the storage stability was remarkable during the first 300 days.


Assuntos
Técnicas Biossensoriais/métodos , Glicemia/metabolismo , Mucinas/química , Nanotubos de Carbono/química , Humanos
6.
Pap. psicol ; 38(2): 135-147, mayo-ago. 2017. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-164407

RESUMO

Se presenta una revisión sistemática de estudios sobre prevalencia de la violencia en el noviazgo (física, psicológica y sexual) cometida y sufrida en adolescentes y jóvenes. De 1221 referencias iniciales, 113 cumplían con los criterios de calidad preestablecidos (evaluación de la violencia con instrumentos fiables y válidos, muestras superiores a 500 participantes u obtenidas mediante muestreo probabilístico). Se encontró una gran variabilidad en los datos de prevalencia, con rangos de variación entre el 3.8% y el 41.9% en violencia física cometida; entre el 0.4% y el 57.3% en violencia física sufrida; entre el 4.2% y el 97% en violencia psicológica cometida; entre el 8.5% y el 95.5% en violencia psicológica sufrida; entre el 1.2% y el 58.8% en violencia sexual cometida; y entre el 0.1% y el 64.6% en violencia sexual sufrida. Los resultados sugieren una mayor prevalencia en la perpetración de agresiones psicológicas por mujeres y sexuales por los hombres; una mayor victimización psicológica y sexual en mujeres; así como tasas ligeramente superiores de agresiones en los adolescentes que en los adultos jóvenes. Asimismo, en muchos de los trabajos revisados las agresiones tenían una naturaleza bidireccional (AU)


This article conducts a systematic review on the prevalence of dating violence in adolescents and young people. Primary studies about physical, psychological and sexual dating violence (perpetration and victimization) were analyzed. A total of 1,221 references were found and, out of those, 113 met the pre-established quality criteria (studies had to have used assessment tools with evidence of reliability and validity in samples of over 500 participants or obtained through probabilistic sampling). The results showed great variability in the figures on the prevalence of dating violence. Specifically, the percentages range from 3.8% to 41.9% for perpetrated physical violence; from 0.4% to 57.3% for victimized physical violence; from 4.2% to 97% for perpetrated psychological violence; from 8.5% to 95.5% for victimized psychological violence; from 1.2% to 58.8% for perpetrated sexual violence; and finally, from 0.1% to 64.6% for victimized sexual violence. The results suggest a higher prevalence in the perpetration of psychological aggression by women and sexual violence by men; greater psychological and sexual victimization in women; and slightly higher rates of aggression in adolescents than in young adults. Also, in many of the papers the aggression had a bidirectional nature (AU)


Assuntos
Humanos , Masculino , Feminino , Adolescente , Violência contra a Mulher , Violência por Parceiro Íntimo/psicologia , Comportamento do Adolescente/psicologia , Delitos Sexuais , Parceiros Sexuais/psicologia , Vítimas de Crime/psicologia , Prevalência , Fatores de Risco
7.
Radiat Prot Dosimetry ; 174(1): 94-101, 2017 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-27009246

RESUMO

Under International Atomic Energy Agency regional programme TSA3 Radiological Protection of Patients in Medical Exposures, Latin American countries evaluated the image quality and glandular doses for digital mammography equipment with the purpose of seeing the performance and compliance with international recommendations. Totally, 24 institutions participated from Brazil, Chile, Costa Rica, El Salvador, Mexico, Paraguay and Venezuela. Signal difference noise ratio results showed for CR poor compliance with tolerances; better results were obtained for full-field digital mammography equipment. Mean glandular dose results showed that the majority of units have values below the acceptable dose levels. This joint Latin American project identified common problems: difficulty in working with digital images and lack of specific training by medical physicists from the region. Image quality is a main issue not being satisfied in accordance with international recommendations; optimisation processes in which the doses are increased should be very carefully done in order to improve early detection of any cancer signs.


Assuntos
Mamografia , Exposição à Radiação , Intensificação de Imagem Radiográfica , Brasil , Chile , Costa Rica , Humanos , México , Inquéritos e Questionários
8.
Scand J Psychol ; 57(2): 129-35, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26778197

RESUMO

This study examines how the mechanisms underlying moral disengagement serve as a mediator between anger and hostility and physical and verbal aggression. The study was carried out on 424 participants (61.1% females), aged 15 to 25 years, assessing the direct and indirect effects of the distinct variables using a hierarchical multiple regression analysis and structural equation modeling. The findings suggest that anger and hostility contribute independently and positively to physical and verbal aggression. Moreover, the relationships between anger, hostility, and aggression appear to be mediated by moral disengagement. Indeed, this process of mediation was invariant across sexes, and it tended to be stronger for physical--as opposed to verbal--aggression.


Assuntos
Agressão/psicologia , Ira , Hostilidade , Princípios Morais , Adolescente , Adulto , Feminino , Humanos , Masculino , Inquéritos e Questionários , Adulto Jovem
9.
Radiat Prot Dosimetry ; 163(4): 473-9, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24993012

RESUMO

Latin American countries (Argentina, Brazil, Chile, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Mexico, Nicaragua, Paraguay, Uruguay and Venezuela) working under the International Atomic Energy Agency (IAEA) Technical Cooperation Programme: TSA3 Radiological Protection of Patients in Medical Exposures have joined efforts in the optimisation of radiation protection in mammography practice. Through surveys of patient doses, the region has a unique database of diagnostic reference levels for analogue and digital equipment that will direct future optimisation activities towards the early detection of breast cancer among asymptomatic women. During RLA9/057 (2007-09) 24 institutions participated with analogue equipment in a dose survey. Regional training on methodology and measurement equipment was addressed in May 2007. The mean glandular dose (DG) was estimated using the incident kerma in air and relevant conversion coefficients for both projections craneo caudal and mediolateral oblique (CC and MLO). For Phase 2, RLA9/067 (2010-11), it was decided to include also digital systems in order to see their impact in future dose optimisation activities. Any new country that joined the project received training in the activities through IAEA expert missions. Twenty-nine new institutions participated (9 analogue and 20 digital equipment). A total of 2262 patient doses were collected during this study and from them D(G) (mGy) for both projections were estimated for each institution and country. Regional results (75 percentile in mGy) show for CC and MLO views, respectively: RLA9/057 (analogue) 2.63 and 3.17; RLA/067: 2.57 and 3.15 (analogue) and 2.69 and 2.90 (digital). Regarding only digital equipment for CC and MLO, respectively, computed radiography systems showed 2.59 and 2.78 and direct digital radiography (DDR) systems 2.78 and 3.04. Based on the IAEA Basic Safety Standard (BSS) reference dose (3 mGy), it can be observed that there is enough room to start optimisation processes in Latin America (LA); several countries or even particular institutions have values much higher than the 3 mGy. The main issues to address are lack of well-established quality assurance programmes for mammography, not enough medical physicists with training in mammography, an increase in patient doses with the introduction of digital equipment and to create awareness on radiation risk and optimisation strategies.


Assuntos
Mamografia/métodos , Energia Nuclear , Proteção Radiológica/normas , Neoplasias da Mama , Feminino , Inquéritos Epidemiológicos , Humanos , Agências Internacionais , América Latina , Doses de Radiação
10.
Anal Chem ; 84(18): 7670-6, 2012 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-22900668

RESUMO

Propofol is a widely used, potent intravenous anesthetic for ambulatory anesthesia and long-term sedation. The target steady state concentration of propofol in blood is 0.25-10 µg/mL (1-60 µM). Although propofol can be oxidized electrochemically, monitoring its concentration in biological matrixes is very challenging due to (i) low therapeutic concentration, (ii) high concentrations of easily oxidizable interfering compounds in the sample, and (iii) fouling of the working electrode. In this work we report the performance characteristics of an organic film coated glassy carbon (GC) electrode for continuous monitoring of propofol. The organic film (a plasticized PVC membrane) improved the detection limit and the selectivity of the voltammetric sensor due to the large difference in hydrophobicity between the analyte (propofol) and interfering compounds of the sample, e.g., ascorbic acid (AA) or p-acetamidophenol (APAP). Furthermore, the membrane coating prevented electrode fouling and served as a protective barrier against electrode passivation by proteins. Studies revealed that sensitivity and selectivity of the voltammetric method is greatly influenced by the composition of the PVC membrane. The detection limit of the membrane-coated sensor for propofol in PBS is reported as 0.03 ± 0.01 µM. In serum-like electrolyte solutions containing physiologically relevant levels of albumin (5%) and 3 mM AA and 1 mM APAP as interfering agents, the detection limit was 0.5 ± 0.4 µM. Both values are below the target concentrations used clinically during anesthesia or sedation.


Assuntos
Anestésicos Intravenosos/análise , Técnicas Eletroquímicas , Eletrólitos/química , Propofol/análise , Acetaminofen/química , Ácido Ascórbico/química , Eletrodos , Membranas Artificiais , Oxirredução , Propofol/sangue
11.
Anal Chim Acta ; 704(1-2): 63-7, 2011 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-21907022

RESUMO

2,6-Diisopropylphenol (propofol) is a potent anesthetic drug with fast onset of the anesthetic effect and short recovery time for the patients. Outside of the United States, propofol is widely used in performing target controlled infusion anesthesia. With the long term vision of an electrochemical sensor for in vivo monitoring and feedback controlled dosing of propofol in blood, different alternatives for the electrochemical quantification of propofol using diverse working electrodes and experimental conditions are presented in this contribution. When the electrochemical oxidation of propofol takes place on a glassy carbon working electrode, an electrochemically active film grows on the electrode surface. The reduction current of the film is proportional to the propofol concentration and the accumulation time. Based on these findings a stripping analytical method was developed for the detection of propofol in acidic solutions between 0 and 30 µM, with a detection limit of 5.5±0.4 µM. By restricting the scanned potential window between 0.5 V and 1.0 V in cyclic voltammetric experiments, the formation of the electrochemically active polymer can be prevented. This allowed the development of a direct voltammetric method for assessing propofol in acidic solutions between 0 and 30 µM, with a 3.2±0.1 µM (n=3) detection limit. The stripping method has a better sensitivity but somewhat worse reproducibility because the electrode surface has to be renewed between each experiment. The direct method does not require the renewal of the electrode surface between measurements but has no adequate selectivity towards the common interfering compounds.


Assuntos
Anestésicos/sangue , Carbono/química , Eletroquímica/métodos , Vidro/química , Propofol/sangue , Anestésicos/farmacologia , Anestésicos/uso terapêutico , Eletroquímica/instrumentação , Eletrodos , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Oxirredução , Dor/sangue , Dor/tratamento farmacológico , Dor/prevenção & controle , Potenciometria , Propofol/farmacologia , Propofol/uso terapêutico , Reprodutibilidade dos Testes , Soluções
12.
Anal Chem ; 82(13): 5568-72, 2010 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-20518470

RESUMO

An amperometric sensor for lactate quantification is presented. The developed biosensor requires only 0.2 U of lactate oxidase, which is immobilized in a mucin/albumin hydrogel matrix. By protecting the platinum surface with a Nafion membrane, typical interference related to negatively charged species such as ascorbic acid has been minimized to practically undetectable levels. Electrochemical properties associated with the Nafion membrane are assessed as a function of Nafion concentration. In a phosphate buffer solution of pH 7.0, linear dependence of the catalytic current upon lactate bulk concentration was obtained between 2 and approximately 1000 microM. A detection limit of 0.8 microM can be calculated considering 3 times the standard deviation of the blank signal divided by the sensitivity of the sensor. The lactate biosensor presents remarkable operational stability and sensitivity (0.537 +/- 0.007) mA.M(-1), where the error is the standard deviation of the slope calculated from the linear regression of the calibration curve of a fresh biosensor. In this regard, the sensor keeps practically the same sensitivity for 5 months, while the linear range decreases until an upper value of 0.8 mM is reached. Assays performed with whole blood samples spiked with 100 microM lactate gave (89 +/- 6)% of recovery.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Ácido Láctico/sangue , Albuminas/química , Eletrodos , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Hidrogéis/química , Concentração de Íons de Hidrogênio , Oxigenases de Função Mista/química , Oxigenases de Função Mista/metabolismo , Mucinas/química , Platina/química
13.
Anal Bioanal Chem ; 397(5): 1873-81, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20449577

RESUMO

This article presents a simple chronoamperometric immunosensor for the quantitative assessment of creatine kinase MB (CK-MB) in 50 microL undiluted serum samples. The immunosensor consists of gold working and counter electrodes patterned onto a glass chip by thin-film photolithography and an external Ag|AgCl reference electrode. The detection limit (DL) of the chronoamperometric method is 13 ng mL(-1) (DL = 2xRMSD/S, where RMSD is the residual mean standard deviation of the measured points around a calibration curve with a slope of S). In spiked serum samples, the response was linear up to 300 ng mL(-1) of CK-MB. A surface plasmon resonance (SPR) system with simultaneous electrochemical detection (EC-SPR) aided the development of the sandwich immunoassay. Real-time monitoring of the SPR signal was used to optimize the capture antibody immobilization, CK-MB and detection antibody binding, as well as to minimize the nonspecific adsorption of serum proteins to the sensor surface. The detection antibody has been labeled with alkaline phosphatase (ALP) enzyme for sensitive electrochemical detection. ALP catalyzes the hydrolysis of ascorbic acid phosphate and generates ascorbic acid, which is measured chronoamperometrically. The electrochemical immunoassay for CK-MB was less sensitive to nonspecific adsorption related interferences, had a better detection limit, and required a lower volume of sample than the SPR method.


Assuntos
Creatina Quinase Forma MB/sangue , Eletroquímica/métodos , Imunoensaio/métodos , Ressonância de Plasmônio de Superfície/métodos , Eletroquímica/instrumentação , Humanos , Ressonância de Plasmônio de Superfície/instrumentação
14.
Chem Mater ; 22(7): 2248-2254, 2010 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-20454637

RESUMO

Robust surface-bound insulating polymer films with controlled thickness in <5 nm range are important for technological advances in diverse disciplines such as electrochemical sensors, molecular electronics, separations and anti-corrosive coatings. Creating these films by simple methods from readily available materials has been a significant challenge. Here we report a newly synthesized molecule combining a styrene and thiol moieties, joined via a short linker, that binds to the gold surface, polymerizes and crosslinks polymer chains to form robust films with uniform and controlled thickness and complete surface coverage. Additional layers can be deposited. These films that bridge two- and three-dimensional materials show excellent stability and insulating properties.

15.
Odontoestomatol ; 11(12): 28-33, 2009.
Artigo em Espanhol | LILACS, BNUY, BNUY-Odon | ID: lil-528034

RESUMO

Se presentan dos casos clínicos de fibroma odontogénico periférico (FOP) entidad poco frecuente. Fueron diagnosticados tratados y seguidos en las Cátedras de Patología, Semiología y Clínica Estomatológica y de Anatomía Patológica Buco-máxilo-facial de la Facultad de Odontología (UDELAR). La baja frecuencia de esta lesión en la literatura y el diagnóstico diferencial que plantea con otras lesiones hace interesante su publicación. Ambos afectaron a mujeres de 6 y 57 años respectivamente.


Assuntos
Humanos , Fibroma Ossificante
16.
Anal Chem ; 78(19): 6733-9, 2006 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-17007491

RESUMO

The theoretical framework of a general model for the simulation of concentration profiles of electroactive and nonelectroactive species, driven by an electrochemical process under potentiostatic conditions, is presented. Based on this analysis, finite differences simulations are performed to calculate the actual profiles under different experimental conditions. Furthermore, the effect of experimental parameters (diffusion coefficients of the ions of the redox couple or the supporting electrolyte, charge of the different species, etc.) on the concentration profiles is also examined. The results obtained when low and high concentrations of supporting electrolyte are compared aid understanding of the effect of the electrolyte on the measurements. The presented model also underlines the role of supporting electrolyte species when nonspecific techniques are employed to measure the concentration changes produced by electroactive species. On the other hand, if a highly specific technique were used to detect changes in the concentration or concentration gradient of a given species, then it would be possible to estimate the respective profiles of the other species. The simulations suggest that techniques measuring concentration gradients are more sensitive to determining concentration changes than those involving a measurable linearly related to concentration.

17.
Anal Chem ; 78(19): 6740-6, 2006 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-17007492

RESUMO

The theoretical model presented in part 1 of this work is employed to simulate and fit experimental probe beam deflection (PBD) data of Fe(CN)6(3-)/Fe(CN)6(4-) and Fe3+/Fe2+ couples. Current and beam deviation dependency on time at constant potential (chronoamperometry and chronodeflectometry) is analyzed via a new treatment based on the migration and diffusion properties of all the species involved. The diffusion coefficients of electroactive species are obtained by fitting chronoamperometric curves. Those coefficients are then employed to simulate the respective chronodeflectometric profiles. The experimental data and the theoretical function are fitted by the minimum squares Simplex algorithm. The effect of working with systems in which both electroactive species are charged is discussed in detail. Specifically, the possibility of quantitative analysis of nonspecific techniques data is analyzed when a relative high concentration of supporting electrolyte is used. Such analysis widens the scope of techniques as PBD since in many cases the effect of supporting electrolyte species could be negligible as compared to the response of electroactive species. The variation of the refraction index with the concentration gradient of each soluble species is also discussed.

18.
J Phys Chem B ; 110(31): 15345-52, 2006 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-16884254

RESUMO

A probe beam deflection (PBD) study of ion exchange between an electroactive polymer poly(allylamine)-bipyridyl-pyridine osmium complex film and liquid electrolyte is reported. The PBD measurements were made simultaneously to chronoamperometric oxidation-reduction cycles, to be able to detect kinetic effects in the ion exchange. Layer-by-layer (LbL) self-assembled redox polyelectrolyte films with osmium bipyridyl complex covalently attached to poly(allylamine) (PAH-Os) and poly(styrene sulfonate) (PSS) have been built by alternate electrostatic adsorption from soluble polyelectrolytes. The ionic exchange during initial conditioning of the film ("break-in") undergoing oxidation-reduction cycles and recovery after equilibration in the reduced state have shown an exchange of anions and cations with time lag between them. The effect of the nature of cation on the ionic exchange has been investigated with dilute HCl, LiCl, NaCl, and CsCl electrolytes. The ratio of anion to cation exchanged at the film-electrolyte interface has a strong dependence on the nature of charge in the topmost layer, that is, when negatively charged PSS is the capping layer, a larger proportion of cation exchange is observed. This demonstrates that the electrical potential distribution at the redox polyelectrolyte multilayer (PEM)/electrolyte interface determines the ionic flux in response to charge injection in the film.

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