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The characterization of the oxidative resistance of contemporary UHMWPE formulations currently relies upon time-consuming accelerated aging protocols and subsequent FTIR assessment. The potential of thermogravimetric analysis (TGA) for this purpose, however, remains mostly unknown. To study radiation and stabilization-induced changes in the decomposition process, TGA curves corresponding to virgin, e-beam irradiated, and post-irradiation stabilized UHMWPE materials were registered and analyzed. TGA traces of most materials exhibited similar features, with two weight increases before an initially non-linear decomposition and a portion of linear volatilization starting near 400 ºC. After irradiation, the onset of the second weight increase shifted to lower temperatures and the linear volatilization stage began at higher temperatures. While post-irradiation annealing did not introduce significant changes in TGA curves, remelting delayed the onset of the second weight gain. Furthermore, this weight increase disappeared after vitamin E diffusion. Energies of activation of the initially predominant thermooxidation and the subsequent thermodegradation processes were also calculated from fraction of conversion and reciprocal of temperature plots. As opposed to TGA, FTIR assessment of oxidation following accelerated aging at 120 ºC for 36 hours appeared to be less sensitive to discriminate between the different materials. This study confirms TGA as a promising technique to characterize the oxidative resistance of medical grade UHMWPEs.

Significant gender differences are 1 observed on primary school students' perception of self-efficacy 2 and test anxiety in mathematics. Girls perceive themselves to be 3 significantly worse than boys in mathematics and report higher 4 test anxiety toward mathematics exams. Gender differences in 5 self-efficacy become more pronounced as students grow up, and 6 test anxiety increases for all students. However, the present study 7 shows that teachers' do not perceive differences in self-efficacy 8 in mathematics between boys and girls. 9 Background: The low presence of women in science, technol-10 ogy, engineering, and mathematics (STEM) might be explained 11 by the attitude of young students toward mathematics. Different 12 studies show that girls are less interested in STEM areas than 13 boys during secondary school. A study on the reasons for this 14 fact pointed out that the early years of education can provide 15 a relevant insight to reverse the situation. 16 Research Questions: Is there any age-dependent gender differ-17 ence in primary school students in aspects related to mathemat-18 ics? Are teachers aware of students' perceptions? 19 Methodology: This work presents a study of over 2000 pri-20 mary school students (6-12 years old) and 200 teachers in 21 Aragón (Spain). The study consists of a survey on aspects that 22 influence the experience of female and male students with math-23 ematics and Spanish language for comparison purposes and 24 teacher's awareness of students' perception. 25 Findings: The present study shows that during primary school, 26 girls are more likely to experiment a negative attitude toward 27 mathematics than boys as they grow up, and teachers may not 28 perceive girls' situation.

Vitamin E (or a-tocopherol) is an alternative via to thermal treatments to achieve oxidative stability of gamma or electron beam irradiated ultra-high molecular weight polyethylenes (UHMWPE) used in total joint replacements. Our aim was to study the effects of vitamin E on the molecular dynamics and microstructural properties of UHMWPE. We hypothesized that the antioxidant would plasticize UHMWPE. Vitamin E was incorporated into UHMWPE at different concentrations by diffusion and blending and detected by ultraviolet and infrared spectroscopies from 500 ppm and 4000 ppm, respectively. Dynamic mechanical thermal analysis was used to characterize the influence of this antioxidant in the relaxations of the raw material. Differential scanning calorimetry and transmission electron microscopy served to characterize thermal and microstructure properties, respectively. Vitamin E concentrations above 3% by weight significantly reduced the degree of crystallinity and increased the melting transition temperature of raw UHMWPE. The presence of increasing concentrations of a-tocopherol introduced and/or strengthened the beta relaxation, which was also shifted toward gradually lower temperatures and had rising activation energies up to 188 kJ/mol. In addition, the gamma relaxation remained unaltered on vitamin E addition. Therefore, no plasticizing effects of vitamin E on the molecular dynamics of UHMWPE could be confirmed from mechanical spectroscopy data. However, the a relaxation was modified in intensity and location due to the changes in the degree of crystallinity introduced by the incorporation of vitamin E.

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