1.Effects of incorporation of organically modified montmorillonite on the reaction mechanism of epoxy/amine cure.
Alzina C1, Mija A, Vincent L, Sbirrazzuoli N. J Phys Chem B. 2012 May 17;116(19):5786-94. doi: 10.1021/jp3021722. Epub 2012 May 8.
The aim of this study is to understand the effect of nonmodified or different organically modified montmorillonites on the reaction mechanism of epoxy/amine cure. The reference material consists of diglycidyl ether of bisphenol A (DGEBA) and 1,3-phenylene diamine (mPDA) in stoichiometric proportions. The reaction with various organically modified montmorillonites (I28E, I34TCN, and MMTm) is compared to highlight the catalytic effect of MMT water content and of the alkylammonium cations on the epoxy/amine reaction mechanism. In the absence of mPDA curing agent, DGEBA develops homopolymerization reactions with I28E, I34TCN, and MMTm. Chemorheological kinetics and advanced isoconversional analysis of epoxy cure are studied by rheometrical measurements and differential scanning calorimetry (DSC). Molecular mobility of the system under curing is modified in the presence of montmorillonites. Finally, the study underlines the role of montmorillonites and the influence of the change in reaction mechanisms on glass transition of the nanocomposites.
2.Hybrid nanocomposites: advanced nonlinear method for calculating key kinetic parameters of complex cure kinetics.
Alzina C1, Sbirrazzuoli N, Mija A. J Phys Chem B. 2010 Oct 7;114(39):12480-7. doi: 10.1021/jp1040629.
Complex cure kinetics involved in the elaboration of organic/inorganic hybrid silicate nanocomposites based on diglycidyl ether of bisphenol A (DGEBA), 1,3-phenylenediamine (m-PDA), and modified montmorillonite (MMTm) clay have been studied. An advanced isoconversional method has been applied to nonisothermal data in order to evaluate cure kinetic parameters. A new method based on nonlinear optimization was proposed to compute nonisothermal kinetic parameters avoiding complex optimization techniques. The objective is to obtain kinetic parameters rather than modeling values in order to give more insight into the elucidation of complex cure mechanisms. Key kinetic parameters of cure have been computed according to this method. It appears that the reaction mechanism changes if MMTm is added to the curing system. The results reveal an increase of the efficiency of collisions in presence of MMTm at the beginning of the cure and an increase of the frequency of diffusion jumps at the later stage of the reaction.
3.Filling a gap in transfusion medicine education and research.
Sibinga CT1. Transfus Med Rev. 2009 Oct;23(4):284-91. doi: 10.1016/j.tmrv.2009.06.003.
After the outbreak of the HIV/AIDS epidemic, attention was focused on the restructuring and reorganization of nationally supported safe and sustainable blood supply systems. Networking and human capacity building in transfusion medicine were developed through World Health Organization initiatives. Educational materials were created for the core elements of the blood transfusion chain. However, the management aspects of transfusion medicine as well as applied health science research in transfusion medicine were not addressed. In 2000, the World Health Organization initiated the creation of the Academic Institute for International Development of Transfusion Medicine (IDTM). This would focus on the development of a postgraduate master's course in management of transfusion medicine (MMTM) and the development of research programs for transfusion medicine-related health sciences. The Academic Institute IDTM was created at the University of Groningen Faculty of Medical Sciences, The Netherlands.
4.Mixed membership trajectory models of cognitive impairment in the multicenter AIDS cohort study.
Molsberry SA1, Lecci F, Kingsley L, Junker B, Reynolds S, Goodkin K, Levine AJ, Martin E, Miller EN, Munro CA, Ragin A, Sacktor N, Becker JT. AIDS. 2015 Mar 27;29(6):713-21. doi: 10.1097/QAD.0000000000000561.
OBJECTIVE: The longitudinal trajectories that individuals may take from a state of normal cognition to HIV-associated dementia are unknown. We applied a novel statistical methodology to identify trajectories to cognitive impairment, and factors that affected the 'closeness' of an individual to one of the canonical trajectories.