In Situ Synthesis of Polymer/Clay Nanocomposites by Type II Photoinitiated Free Radical Polymerization

Cataloged from PDF version of article.A new synthetic route for the preparation of poly(methyl methacrylate)/montmorillonite (PMMA/MMT) nanocomposites was reported. In this method, first 4-(dimethylamino)benzoate group was incorporated into silicate layers of clay by esterification reaction and used to produce PMMA/MMT nanocomposites by in situ Type II photoinitiated free radical polymerization. In situ photopolymerization of methyl methacrylate through into the silicate layers by either visible or UV light irradiation leads to PMMA/MMT nanocomposites. Copyright © 2011 Wiley Periodicals, Inc

“Cooperative Learning Does Not Work for Me”: Analysis of Its Implementation in Future Physical Education Teachers

Cooperative learning (CL) is one of the pedagogical models that has had more application in the area of Physical Education (PE), being highly worked in the initial training of teachers. The aim of the study is to check to what extent future PE teachers are able to apply in the classroom the PE training they have received at university, deepening their fears, insecurities and problems when carrying it out. Thirteen future PE teachers (7 girls and 6 boys) aged 20.87 ± 1.43 participated and, after having been trained in CL in various subjects, applied it in the classroom during their internship. They were selected through purposeful non-probability sampling. A qualitative methodology was used, being the interviews, the teaching diaries and the seminars with the tutor the instruments of data collection used. Three categories of analysis were used: (a) initial expectations in the application of the CL; (b) problems encountered in its implementation; (c) reflection about its application in the future. The results showed how the future teachers did not see their expectations of success fulfilled, encountering resistance from both students and teachers in PE. Furthermore, they reflect the need to continue training in a model that has infinite nuances so that it can be implemented satisfactorily. It is necessary to continue researching a pedagogical model with so many possibilities in the area of PE and with so much transversality on a social level

Synthesis and characterization of polypropylene-graft-poly(l-lactide) copolymers by CuAAC click chemistry

Altinkok, Cagatay (Trakya author)The syntheses of polypropylene-graft-poly(l-lactide) copolymers (PP-g-PLAs) via copper (I)-catalyzed azide-alkyne cycloaddition "click" reaction (CuAAC) using azide side-chain functionalized polypropylene (PP-N-3) and alkyne end-functionalized poly(l-lactide) (PLA-Alkyne) were reported. The CuAAC was then applied to azide and different feeding ratios of alkyne functional polymers to give PP-g-PLAs that were characterized by FTIR, H-1-NMR, GPC, DSC, and WCA measurements. The CuAAC click reaction was achieved by two different feeding ratio (PP-N-3:PLA-Alkyne = 1:5 and 1:10) and thermal, biodegradable, and surface properties of obtained graft copolymers were investigated. The molar ratio of PLA were calculated as 72.7 (PP-g-PLA-1) and 78.4% (PP-g-PLA-2) by H-1-NMR spectroscopy. The water contact angle (WCA) values of PP-g-PLA-1 (81(o) +/- 1.3) and PP-g-PLA-2 (75(o) +/- 1.6) copolymers were compared with commercial chlorinated polypropylene (PP-Cl) (90(o) +/- 1.0), suggesting a more hydrophilic nature of desired graft copolymers produced. Conversely, the enzymatic biodegradation studies revealed that the weight losses of graft copolymers were determined as 13.6 and 22.1%, which is about 4% for commercial PP-Cl sample. Thus, it was clear that this simple and facile method was effective in promoting biodegradation of commercial polypropylene and attractive particularly for worldwide environmental remediation goals. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2595-260

Controlled vortex motion in multiple interpenetrating pinning arrays

We study the effect of multiple interpenetrating pinning arrays on the vortex motion in the presence of an ac driving force, fd(t), by using extensive molecular dynamics (MD) simulations. Firstly, the response to a square ac wave fd(t) has been explored for the vortices interacting with a periodic square pinning array which has different pinning strengths and sizes. The effect of the type of an ac drive and its amplitude on the oscillatory dynamics of vortices have been investigated in detail. For very low displacements of the vortices, we have found that the single-particle model can produce results analytically similar to the ones obtained by the MD simulations. It is shown that the collective motion of vortices can be controlled easily by varying the number of multiple interpenetrating square pinning lattices (NSPSL). A regular sequence of peaks has been observed for NSPSL = 3 in the time evolution of the average velocity of the vortices (i.e., V̅x - t curves). The number of peaks (Npeak) strongly depends on the magnitude of fd(t), and increases with increasing the magnitude of fd. The close relation between Npeak and fd is considered as an indication of controlling vortex motion in a multiple periodic pinning structure. Finally, the variation of the power spectrum of noise S(ν) with NSPSL has been investigated. For NSPSL = 3, it has been found that the plastic motion of the row of vortices evolves at low frequencies, i.e., 1/ν behavior, whereas, at high frequencies, S(ν) shows a typical behavior of Gaussian white noise

The correlation between skull fractures and intracranial lesions due to traffic accidents

In this study, it was aimed to investigate the relationship between skull fractures and intracranial lesions following head injury. For this purpose, 500 cases, which were referred to the Third Committee of Council of Forensic Medicine in Istanbul due to traffic accidents by the courts of laws between 1998 and 2000, were examined retrospectively. They were categorized in 3 groups based on findings of their cranium x-rays and brain tomographies. 1- The cases who have fractures in skull bones with brain lesions 2- The cases who have fractures in skull bones with no brain lesions 3- The cases who have brain lesions with no skull fractures. They were examined in detail according to age, sex, localization of skull fractures and brain lesions, and if surgery was applied or not