Mg­(N­(SO2CF3)2)2 (MgTFSI2) solutions with dimethoxyethane (DME) exhibit a peculiar behavior. Over a certain range of salt content, they form two immiscible phases of specific electrolyte concentrations. This behavior is unique, as both immiscible phases comprise the same constituents. Thus, this miscibility gap constitutes an exceptionally intriguing and interesting case for the study of such phenomena. We studied these systems from solutions structure perspective. The study included a wide variety of analytical tools including single-crystal X-ray diffraction, multinuclei NMR, and Raman spectroscopy coupled with density functional theory calculations. We rigorously determined the structure of the MgTFSI2/DME solutions and developed a plausible theory to explain the two-phase formation phenomenon. We also determined the exchange energy of the “caging” DME molecules solvating the central magnesium ion. Additionally, by measuring the ions’ diffusion coefficients, we suggest that the caged Mg2+ and TFSI– move as free ions in the solution. Knowledge of the arrangement of the solvent/cation/anion structures in these solutions enables us to explain their properties. We believe that this study is important in a wide context of solutions chemistry and nonaqueous electrochemistry. Also, MgTFSI2/DME solutions are investigated as promising electrolyte solutions for rechargeable magnesium batteries. This study may serve as an important basis for developing further MgTFSI2/ether based solutions for such an interesting use.

Recently, MgTFSI2/MgCl2 electrolyte solutions in dimethoxyethane (DME) have been shown to function as viable electrolyte solutions for secondary Mg batteries that can facilitate reversible magnesium deposition/dissolution. MgCl2 is a crucial component in these solutions. On its own, however, it is practically insoluble in DME. Therefore, the fact that it is readily dissolved in MgTFSI2/DME solution is remarkable. Addition of MgCl2 greatly improves the electrochemical performance of MgTFSI2/DME electrolyte solutions. Thus, identifying the species formed in MgTFSI2/MgCl2 solutions is intriguing. In this study, we implemented a wide variety of analytical tools, including single crystal X-ray diffraction, multinuclear NMR, and Raman spectroscopy, to elucidate the structure of these solutions. Various solution species were determined, and a suitable reaction scheme is suggested.

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The maturation of pig articular cartilage was followed by 2 H in-phase double quantum filtered (IP-DQF) spectroscopic MRI, 1 H T 2 MRI, and 23 Na DQF and triple quantum filtered MRS. The results all lead to the conclusion that the order and density of the collagen fibers in articular cartilage increase from birth to maturity. At birth, both 2 H IP-DQF signal and 1 H T 2 were homogeneous throughout the cartilage and their values independent of the orientation of the plug relative to the magnetic field. At maturation, the 2 H IP-DQF spectrum near the bone is composed of two pairs of quadrupolar split satellites and the 1 H T 2 relaxation is biexponential, indicating the presence of two groups of collagen fibers. Maturation of cartilage plays an important role in human development from birth to adulthood. Furthermore, the integrity of articular cartilage is an essential factor for the preservation of the quality of life. Thus, a noninvasive technique that will allow follow-up of changes in the microstructure of cartilage is highly desirable.Previous studies indicate that the maturation process of articular cartilage is associated with dramatic structural and chemical composition changes. With age, the proteoglycan content progressively decreases (1-3), the collagen content significantly increases (1-4), and cellularity diminishes (1,5), as does the cartilage thickness (1,2,5). Moreover, scanning electron microscopy (SEM) studies have shown that in newborns the collagen fibers are randomly oriented (6,7), while for mature cartilage, the fibers in the deep and radial zones are well ordered with an orientation perpendicular to the surface (8,9).T 2 and T 1 have been shown to be related to the architecture of the collagen fibers and the integrity of the cartilage matrix (10 -15). The effect of maturation on the MRI appearance of articular cartilage was studied in humans, pigs, calves, and rats (5,16 -18). A progressive and significant decrease in global T 2 values with maturation was observed in rat articular cartilage (16). In another work, a decrease of T 2 -weighted signal intensity within the weight-bearing region was seen during normal development of children (17). For newborn piglets, hip cartilage was homogeneous on T 1 -and T 2 -weighted images, while from 2 weeks of age a distinct trilaminar appearance was observed on T 2 -weighted images (5). Similar results were found for 3-month-old bovine calves (18). The laminar appearance in young articular cartilage was sensitive to the place of origin within a joint (19).We have shown that 2 H double quantum filtered (DQF) spectroscopic MRI gives very detailed information about the density and orientation of the collagen fibers in articular cartilage (20). Using this method, we studied the changes in the architecture of collagen fibers when cartilage is under load (21) and when the cartilage is detached from the bone (22).In the present work, the gradual ordering of the collagen fibers, from birth to adulthood, was followed by 2 H IP-DQF (23,24) spectroscopic MRI, prot...

Recently, the nature of the carbon radicals stabilized in various coals was characterized using Electron Paramagnetic Resonance (EPR) spectroscopy. It was demonstrated that introducing diamagnetic gases, such as He, CO2, or N2, under STP conditions to the coal surface induces the appearance of a new type of carbon surface radical. This interesting phenomenon was not observed for all coal types, which suggests that the use of EPR measurements can provide information on functional groups that exist on the carbon surface. In the current study coupling Nuclear Magnetic Resonance (NMR) with gas flow in situ EPR measurements significantly enhances the ability to characterize the nature of these radicals and the surface functional groups of coal samples. It was observed that the oxidative reaction with aliphatic groups leads to the increase in stable carbon centered radicals. In addition, there are some species of carbon centered radicals that show reversible binding to O2. This phenomena, however, is dependent on the coal rank, sample porosity and the degree of the coal sample to undergo structural changes under the LTO process. These findings shed new light onto the complex heterogeneous low temperature oxidation reactions occurring at the coal surface.