Physicochemical Characterization, and Relaxometry Studies of Micro-Graphite Oxide, Graphene Nanoplatelets, and Nanoribbons

The chemistry of high-performance magnetic resonance imaging contrast agents remains an active area of research. In this work, we demonstrate that the potassium permanganate-based oxidative chemical procedures used to synthesize graphite oxide or graphene nanoparticles leads to the confinement (intercalation) of trace amounts of Mn2+ ions between the graphene sheets, and that these manganese intercalated graphitic and graphene structures show disparate structural, chemical and magnetic properties, and high relaxivity (up to 2 order) and distinctly different nuclear magnetic resonance dispersion profiles compared to paramagnetic chelate compounds. The results taken together with other published reports on confinement of paramagnetic metal ions within single-walled carbon nanotubes (a rolled up graphene sheet) show that confinement (encapsulation or intercalation) of paramagnetic metal ions within graphene sheets, and not the size, shape or architecture of the graphitic carbon particles is the key determinant for increasing relaxivity, and thus, identifies nano confinement of paramagnetic ions as novel general strategy to develop paramagnetic metal-ion graphitic-carbon complexes as high relaxivity MRI contrast agents

Synthesis of Polystyrene-Supported Dithizone Analogues for Use as Chemical Sensors for Heavy Metals

This paper describes methods for chemical immobilization of a diarylthiocarbazone unit onto a polystyrene matrix

The comparison of the reasons of women’s participation in different forms of physical activity such as aerobics and aqua aerobics

Over the last few years the interest for the so-called healthy lifestyle motivated by the fitness ideology has increased significantly. However, there is still little research concerning this question, especially with regard exercises in water. The purpose of this research was the comparison of the reason of women’s participation in different forms of physical activity such as aerobics and aqua aerobics classes, and whether the reasons for taking up this activity were related to health problems, place of residence or perhaps totally random. The research included 140 women who took part in 60-minutes long aerobics and aqua aerobics classes. The research was carried out by means of a statistical poll using a questionnaire. Among the main factors influencing the women’s decision to take up some kind of physical activity are: better life quality, lower stress level, better well-being, beneficial influence sports have on their health as well as improvement in physical appearance. It has been found out that regardless of the place of exercise, the motivation for taking up aerobics are similar for all women included in the research. The choice of place is motivated by their health capabilities and the environment they live in

Gadolinium (III) loaded nanoparticulate zeolites as potential high-field MRI contrast agents: relationship between structure and relaxivity

The effects of dealumination, pore size, and calcination on the efficiency (as expressed in the relaxivity) of Gd3+-loaded zeolites for potential application as magnetic resonance imaging (MRI) contrast agents were studied. Partial dealumination of zeolites NaY or NaA by treatment with (NH4)(2)SiF6 or diluted HCl resulted in materials that, upon loading with Gd3+, had a much higher relaxivity than the corresponding non-dealuminated materials. Analysis of the H-1 NMR dispersion profiles of the various zeolites showed that this can be mainly ascribed to an increase of the amount of water inside the zeolite cavities as a result of the destruction of walls between cavities. However, the average residence time of water inside the Gd3+-loaded cavities did not change significantly, which suggests that the windows of the Gd3+-loaded cavities are not affected by the dealumination. Upon calcination, the Gd3+ ions moved to the small sodalite cavities and became less accessible for water, resulting in a decrease in relaxivity. The important role of diffusion for the relaxivity was demonstrated by a comparison of the relaxivity of Gd3+-loaded zeolite NaY and NaA samples. NaA had much lower relaxivities due to the smaller pore sizes. The transversal relaxivities of the Gd3+-doped zeolites are comparable in magnitude to the longitudinal ones at low magnetic fields (&lt; 60 MHz). However at higher fields, the transversal relaxivities steeply increased, whereas the longitudinal relaxivities decreased as field strength increased. Therefore, these materials have potential as T-t MRI contrast agents at low field, and as T-t agents at higher fields.</p