88 research outputs found

    MĂśssbauer study of a tetrakis (pentafluorophenyl) porphyrin iron (III) chloride in comparison with the fluorine unsubstituted analogue

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    Mossbauer investigations, in association with density functional theory (DFT) calculations, have been conducted for the molecular and electronic structures of iron (III) [tetrakis (pentafluorophenyl)] porphyrin chloride [(F_{20}TPP)Fe:Cl], as a Fe(III)-tetraphenylporphyrin complex containing chloride axial ligand and substituted hydrogen atoms by fluorine ones in the four phenyl rings, in comparison with its fluorine unsubstituted analogue [(TPP)Fe:Cl]. It was found that the parameters of Mossbauer spectra of both complexes are close to one another, and correspond to the high-spin state of Fe(III) ions, but they show the different temperature dependence and the quadrupole doublets in Mossbauer spectra show different asymmetry at low temperatures. Results of DFT calculations are analyzed in the light of catalytic activity of the halogenated complex

    6-year old children with special educational needs at the beginning of school. A study of gender in the context of education reform

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    Initiators of the most socially negotiated changes under the current reform of the education system, including the lowering of school age to 6, indicate “bridging the education gap” as one of the advantages of an earlier education. In fact, there is no critical refl ection and discussion on how the education system responds to the diversity of children’s needs and identifi ed areas and risk factors of educational failures on the threshold of school. In the text we pay special attention to two important issues overlooked in the ministerial discourse: a risk factor for school failure defi ned as special educational needs (SEN) and the problem of differentiation of the level of preparedness, experience and school achievements of children based on gender, with particular regard to socioemotional development

    Evaluation of Reduced-Graphene-Oxide Aligned with WO3-Nanorods as Support for Pt Nanoparticles during Oxygen Electroreduction in Acid Medium

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    Hybrid supports composed of chemically-reduced graphene-oxide-aligned with tungsten oxide nanowires are considered here as active carriers for dispersed platinum with an ultimate goal of producing improved catalysts for electroreduction of oxygen in acid medium. Here WO3 nanostructures are expected to be attached mainly to the edges of graphene thus making the hybrid structure not only highly porous but also capable of preventing graphene stacking and creating numerous sites for the deposition of Pt nanoparticles. Comparison has been made to the analogous systems utilizing neither reduced graphene oxide nor tungsten oxide component. By over-coating the reduced-graphene-oxide support with WO3 nanorods, the electrocatalytic activity of the system toward the reduction of oxygen in acid medium has been enhanced even at the low Pt loading of 30 microg cm-2. The RRDE data are consistent with decreased formation of hydrogen peroxide in the presence of WO3. Among important issues are such features of the oxide as porosity, large population of hydroxyl groups, high Broensted acidity, as well as fast electron transfers coupled to unimpeded proton displacements. The conclusions are supported with mechanistic and kinetic studies involving double-potential-step chronocoulometry as an alternative diagnostic tool to rotating ring-disk voltammetry.Comment: arXiv admin note: text overlap with arXiv:1805.0315

    A formalism to compare electrocatalysts for the oxygen reduction reaction by cyclic voltammetry with the thin-film rotating ring-disk electrode measurements

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    This report describes a general method to correlate the features determining the performance of an electrocatalyst (EC), including the accessibility of O2 to the active sites and the kinetic activation barrier, with the outcome of conventional electrochemical experiments. The method has been implemented for oxygen reduction reaction ECs by cyclic voltammetry with the thin-film rotating ring-disk electrode setup. The method (i) does not rely on the simplifications associated with the Butler-Volmer kinetic description of electrochemical processes and (ii) does not make assumptions on the specific features of the EC, allowing to compare accurately the kinetic performance of oxygen reduction reaction ECs with completely different chemistry. Finally, with respect to other widespread figures of merit (e.g. the half-wave potential E1/2), the figure of merit here proposed, for example, E(jPt[5%]), allows for much more accurate comparisons of the kinetic performance of ECs

    The impact of competitive sports on menstrual cycle and menstrual disorders, including premenstrual syndrome, premenstrual dysphoric disorder and hormonal imbalances

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    Objectives: With the considerable increase of female participation in youth sports, it has become crucial for medical professionals, coaches and parents to improve their competitiveness by understanding the conditions for which these females are at elevated risk and mitigating possible health consequences. The aim of this study was to evaluate the effect competitive sports have on the disorders of the menstrual cycle, to investigate the frequency of PMS (premenstrual syndrome)/PMDD (premenstrual dysphoric order) in professional female athletes and to identify risk factors predisposing for PMS and PMDD. Additionally, the levels of selected hormones such as serum estradiol, FSH, LH and prolactin were investigated to identify any hormonal perturbances that might have influence or be the risk factors for menstrual dysfunctions. Material and methods: The study group consisted of 75 professional athletes (girls and young women at the age of 16–22) who lived on the territory of Silesia. The control group consisted of 50 girls and young women at the same age, who did not practice any sport. The research tools included daily diary of PMS symptoms created in line with The American College of Obstetricians and Gynecologists (ACOG) recommendations and ICD-10 diagnostic criteria, daily diary of PMDD symptoms created according to DSM-V diagnostic criteria of the American Psychiatric Association (APA) and premenstrual symptoms screening tool (PSST). Results: The analysis of menstrual cycle disorders showed statistical significance for heavy menstrual bleeding (p = 0.01) and longer breaks between menstrual bleeds (p = 0.01). PMDD was diagnosed in 8% and PMS in more than 42% of respondents. The incidence of PMDD was not at significant variance between the groups (9.33% in contrast to 6.0%), while incidence of PMS was statistically different in both groups (p = 0.045) (49.33% vs 32.0%). A significant correlation between PMS, average age (p = 0.00001) and menarche age (p = 0.03) in young active athletes has been shown. The risk of PMS increased with age (by 1.71 with each year) (p = 0.0007). Conclusions: A number of other risk factors predisposing for PMS and PMDD has also been identified. The findings of these researches will enable the athletic care network to provide better care for young female athletes

    Will You Make Me Happy? The Role of Dating and Dating Violence Victimisation in Happiness Among Adolescents in Europe

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    Purpose: the aim of the article is to show the role of dating and dating violence victimisation, different socioeconomic characteristics, personal experiences of abuse, perceived social support, and the ability to resolve social problems in happiness among adolescents in Europe. Methods: the study had a cross-sectional design. The study participants were 1.528 students from secondary schools (age 13–16) in Spain, Italy, Romania, Portugal, Poland, and the UK. In order to understand which variables were associated with happiness, we fit multiple regression models. Results: the mean value of happiness is lower when teens are in a romantic or dating relationship and have suffered physical and/or sexual violence [β (CI 95%): -1.32(-2.41; -0.22)]. Both not being a victim of bullying and cyberbullying [β(CI 95%):0.90 (0.38; 1.41)] and not witnessing domestic violence against the mother β(CI 95%):1.97(1.06; 2.87)] is associated with relatively higher mean happiness value compared to having such experiences of violence. Also, problem-solving skills [β (CI 95%):0.13 (0.11; 0.14)] and perception of social support [β (CI 95%): 0.03 (0.02, 0.03)] is positively associated with mean value of happiness. Conclusions: there is an association between dating violence victimisation, and happiness among adolescents in Europe. The results suggest the importance of creating healthy, non-violent romantic relationships to build happiness during adolescence, the importance of seeking social support and to provide educational interventions focused on the development of problem-solving skills.The project ‘Lights, Camera and Action against Dating Violence’ (Ligts4Violence) was funded by the European Commission Directorate-General Justice and Consumers Rights, Equality and Citizen Violence Against Women Program 2016 for the period 2017–2019 to promote healthy dating relationship assets among secondary school students from different European countries, under grant agreement No. 776905. It was also co-supported by the CIBER of Epidemiology and Public Health of Spain for its aid to the Gender-based Violence and Youth Research Program
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