RESUMEN
The design and development of efficient and electrocatalytic sensitive nickel oxide nanomaterials have attracted attention as they are considered cost-effective, stable, and abundant electrocatalytic sensors. However, although innumerable electrocatalysts have been reported, their large-scale production with the same activity and sensitivity remains challenging. In this study, we report a simple protocol for the gram-scale synthesis of uniform NiO nanoflowers (approximately 1.75 g) via a hydrothermal method for highly selective and sensitive electrocatalytic detection of hydrazine. The resultant material was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. For the production of the modified electrode, NiO nanoflowers were dispersed in Nafion and drop-cast onto the surface of a glassy carbon electrode (NiO NF/GCE). By cyclic voltammetry, it was possible to observe the excellent performance of the modified electrode toward hydrazine oxidation in alkaline media, providing an oxidation overpotential of only +0.08 V vs Ag/AgCl. In these conditions, the peak current response increased linearly with hydrazine concentration ranging from 0.99 to 98.13 µmol L-1. The electrocatalytic sensor showed a high sensitivity value of 0.10866 µA L µmol-1. The limits of detection and quantification were 0.026 and 0.0898 µmol L-1, respectively. Considering these results, NiO nanoflowers can be regarded as promising surfaces for the electrochemical determination of hydrazine, providing interesting features to explore in the electrocatalytic sensor field.
RESUMEN
Este trabajo aborda un tema de gran actualidad, pero escasamente evaluado con investigaciones científico-empíricas en la Argentina: el bullying. El Cuestionario Revisado de Agresores / Víctimas de Olweus es uno de los instrumentos más usados en el mundo para medir el ser acosado y acosar a otros alumnos, ya que tiende a funcionar similarmente en las distintas naciones. Estudios extranjeros y preliminares en la Argentina detectaron que dicho cuestionario presenta una dimensión unifactorial tanto para la Escala Ser Agredido como para la Escala Agredir. Así, esta investigación pretendió indagar la equivalencia factorial según género de dichas escalas en una población intencional de adolescentes. Para ello se constituyó una muestra de 1.222 adolescentes (44% varones; media de edad: 14.4 años) que concurrían a escuelas de enseñanza media en la Ciudad Autónoma de Buenos Aires y en la ciudad de Paraná (Argentina), quienes completaron dicho instrumento y un cuestionario sociodemográfico. Con este fin, se llevaron a cabo análisis factoriales confirmatorios multigrupos para varones y mujeres con el Programa AMOS 16. Al fijar las cargas factoriales de los nueve ítemes de la Escala Ser Agredido, los resultados indicaron que los mismos tendían a funcionar similarmente para varones y mujeres. En cambio, los resultados de la Escala Ser Agresor sugerían que las preguntas de agresión con golpes / empujones y decir mentiras funcionaban de modo distinto, según el género. En las conclusiones se destacan las implicancias de estos hallazgos, se desarrollan explicaciones de por qué dichos ítemes funcionarían en forma diferente y se brindan sugerencias para futuras investigaciones.
The purpose of this research was to investigate a problem of great psychosocial and political relevance but scarcely studied with empirical studies in Argentina: bullying in secondary education. Argentina is a developed Latin American country of Italian and Spanish descend. This nation belongs to the high but not to the very high human development group and is the second best positioned nation in Latin America. Bullying is considered to be an important risk factor for mental health of both children and adolescents due to its association with personal, familial and social problems. Victims suffer of internalizing problems (depression, anxiety, low self-esteem, among others), on the other hand, aggressor show higher behavioral problems (antisocial behavior, substance use, among others). Several authors stated that bullying is a subset of aggressive behavior, generally defined as an act intended to inflict injury or discomfort upon another student. It is characterized by certain special features such as an asymmetric power relationship and some repetitiveness. Previous research has shown that this problem is more frequent in adolescence than in childhood. Several studies suggested differences in aggression according to gender; males present higher level of aggression and bullying compared to females due to social and biological factors. Therefore, a vital aspect in this respect is measuring of both victimization and aggression. A well-known tool to measure this problems are self-reports. Although self-reports have disadvantages -as all measures- they are efficient and low-cost techniques. Thus, the main objective was to explore factorial invariance of the Revised Olweus Bully / Victim Questionnaire according to gender. This questionnaire is the most widely used instrument to measure bullying in North America and Northern Europe and several authors suggest that the questionnaire functions similarly in many countries. Besides, studies in first countries and Argentina suggested that this questionnaire showed a unifactorial structure both for the Scale of Being a Bullied and the Scale of Being a Bully as well as good validity and reliability. Even in those countries, however, there are few published studies on their psychometric properties. This instrument asks about being bullied (or bullying other students in a different section of the questionnaire) in the past couple of months, comprising direct physical and verbal harassment and threatening and coercive behaviors as well as indirect ways of bullying. The instrument presents nine items about victimization and nine about aggression. They are rated on a 5-point scale (from 0 to 4). The questionnaire also contains several questions about the reactions of others to bullying. It was administered to a convenience sample of 1222 students belonging to high schools in Ciudad Autónoma de Buenos Aires and Paraná (Argentina), (44% males, average age: 14.4). Besides, a sociodemographic questionnaire was administered to this sample. Questionnaires were administered at school and confidentiality was ensured. Statistical Package for Social Sciences (SPSS) 17 and AMOS 16 were used for processing data. AMOS 16 was used for performing multigrup confirmatory factorial analysis in males and females. Configural model for being a bullied was acceptable (CFI = .904 y SRMR = .026). Configural model for being a bully was good (CFI = .919 and SRMR = .018), as well. After constrainting parameters, results suggested that nine items of being bullied were invariant across gender. As regards being bully, results indicated that questions regarding hitting, kicking or pushing and regarding telling lies were not invariant across gender (CFIs were .013 and .011, respectively). Conclusions highlight the relevance and implications of these findings; explanations about why those items could be not invariant in males and females are provided. Also, limitations of this research and directions for future research are pointed out.
RESUMEN
Este trabajo aborda un tema de gran actualidad, pero escasamente evaluado con investigaciones científico-empíricas en la Argentina: el bullying. El Cuestionario Revisado de Agresores / Víctimas de Olweus es uno de los instrumentos más usados en el mundo para medir el ser acosado y acosar a otros alumnos, ya que tiende a funcionar similarmente en las distintas naciones. Estudios extranjeros y preliminares en la Argentina detectaron que dicho cuestionario presenta una dimensión unifactorial tanto para la Escala Ser Agredido como para la Escala Agredir. Así, esta investigación pretendió indagar la equivalencia factorial según género de dichas escalas en una población intencional de adolescentes. Para ello se constituyó una muestra de 1.222 adolescentes (44% varones; media de edad: 14.4 años) que concurrían a escuelas de enseñanza media en la Ciudad Autónoma de Buenos Aires y en la ciudad de Paraná (Argentina), quienes completaron dicho instrumento y un cuestionario sociodemográfico. Con este fin, se llevaron a cabo análisis factoriales confirmatorios multigrupos para varones y mujeres con el Programa AMOS 16. Al fijar las cargas factoriales de los nueve ítemes de la Escala Ser Agredido, los resultados indicaron que los mismos tendían a funcionar similarmente para varones y mujeres. En cambio, los resultados de la Escala Ser Agresor sugerían que las preguntas de agresión con golpes / empujones y decir mentiras funcionaban de modo distinto, según el género. En las conclusiones se destacan las implicancias de estos hallazgos, se desarrollan explicaciones de por qué dichos ítemes funcionarían en forma diferente y se brindan sugerencias para futuras investigaciones.(AU)
The purpose of this research was to investigate a problem of great psychosocial and political relevance but scarcely studied with empirical studies in Argentina: bullying in secondary education. Argentina is a developed Latin American country of Italian and Spanish descend. This nation belongs to the high but not to the very high human development group and is the second best positioned nation in Latin America. Bullying is considered to be an important risk factor for mental health of both children and adolescents due to its association with personal, familial and social problems. Victims suffer of internalizing problems (depression, anxiety, low self-esteem, among others), on the other hand, aggressor show higher behavioral problems (antisocial behavior, substance use, among others). Several authors stated that bullying is a subset of aggressive behavior, generally defined as an act intended to inflict injury or discomfort upon another student. It is characterized by certain special features such as an asymmetric power relationship and some repetitiveness. Previous research has shown that this problem is more frequent in adolescence than in childhood. Several studies suggested differences in aggression according to gender; males present higher level of aggression and bullying compared to females due to social and biological factors. Therefore, a vital aspect in this respect is measuring of both victimization and aggression. A well-known tool to measure this problems are self-reports. Although self-reports have disadvantages -as all measures- they are efficient and low-cost techniques. Thus, the main objective was to explore factorial invariance of the Revised Olweus Bully / Victim Questionnaire according to gender. This questionnaire is the most widely used instrument to measure bullying in North America and Northern Europe and several authors suggest that the questionnaire functions similarly in many countries. Besides, studies in first countries and Argentina suggested that this questionnaire showed a unifactorial structure both for the Scale of Being a Bullied and the Scale of Being a Bully as well as good validity and reliability. Even in those countries, however, there are few published studies on their psychometric properties. This instrument asks about being bullied (or bullying other students in a different section of the questionnaire) in the past couple of months, comprising direct physical and verbal harassment and threatening and coercive behaviors as well as indirect ways of bullying. The instrument presents nine items about victimization and nine about aggression. They are rated on a 5-point scale (from 0 to 4). The questionnaire also contains several questions about the reactions of others to bullying. It was administered to a convenience sample of 1222 students belonging to high schools in Ciudad Autónoma de Buenos Aires and Paraná (Argentina), (44% males, average age: 14.4). Besides, a sociodemographic questionnaire was administered to this sample. Questionnaires were administered at school and confidentiality was ensured. Statistical Package for Social Sciences (SPSS) 17 and AMOS 16 were used for processing data. AMOS 16 was used for performing multigrup confirmatory factorial analysis in males and females. Configural model for being a bullied was acceptable (CFI = .904 y SRMR = .026). Configural model for being a bully was good (CFI = .919 and SRMR = .018), as well. After constrainting parameters, results suggested that nine items of being bullied were invariant across gender. As regards being bully, results indicated that questions regarding hitting, kicking or pushing and regarding telling lies were not invariant across gender (CFIs were .013 and .011, respectively). Conclusions highlight the relevance and implications of these findings; explanations about why those items could be not invariant in males and females are provided. Also, limitations of this research and directions for future research are pointed out.(AU)