Future Prospects of Positron Emission Tomography-Magnetic Resonance Imaging Hybrid Systems and Applications in Psychiatric Disorders.

A positron emission tomography (PET)-magnetic resonance imaging (MRI) hybrid system has been developed to improve the accuracy of molecular imaging with structural imaging. However, the mismatch in spatial resolution between the two systems hinders the use of the hybrid system. As the magnetic field of the MRI increased up to 7.0 tesla in the commercial system, the performance of the MRI system largely improved. Several technical attempts in terms of the detector and the software used with the PET were made to improve the performance. As a result, the high resolution of the PET-MRI fusion system enables quantitation of metabolism and molecular information in the small substructures of the brainstem, hippocampus, and thalamus. Many studies on psychiatric disorders, which are difficult to diagnose with medical imaging, have been accomplished using various radioligands, but only a few studies have been conducted using the PET-MRI fusion system. To increase the clinical usefulness of medical imaging in psychiatric disorders, a high-resolution PET-MRI fusion system can play a key role by providing important information on both molecular and structural aspects in the fine structures of the brain. The development of high-resolution PET-MR systems and their potential roles in clinical studies of psychiatric disorders were reviewed as prospective views in future diagnostics.

In vivo 3D Reconstruction of the Human Pallidothalamic and Nigrothalamic Pathways With Super-Resolution 7T MR Track Density Imaging and Fiber Tractography.

The output network of the basal ganglia plays an important role in motor, associative, and limbic processing and is generally characterized by the pallidothalamic and nigrothalamic pathways. However, these connections in the human brain remain difficult to elucidate because of the resolution limit of current neuroimaging techniques. The present study aimed to investigate the mesoscopic nature of these connections between the thalamus, substantia nigra pars reticulata, and globus pallidus internal segment using 7 Tesla (7T) magnetic resonance imaging (MRI). In this study, track-density imaging (TDI) of the whole human brain was employed to overcome the limitations of observing the pallidothalamic and nigrothalamic tracts. Owing to the super-resolution of the TD images, the substructures of the SN, as well as the associated tracts, were identified. This study demonstrates that 7T MRI and MR tractography can be used to visualize anatomical details, as well as 3D reconstruction, of the output projections of the basal ganglia.

Track-Density Ratio Mapping With Fiber Types in the Cerebral Cortex Using Diffusion-Weighted MRI.

The nerve fibers are divided into three categories: projection, commissural, and association fibers. This study demonstrated a novel cortical mapping method based on these three fiber categories using MR tractography data. The MR fiber-track data were extracted using the diffusion-weighted 3T-MRI data from 19 individuals' Human Connectome Project dataset. Anatomical MR images in each dataset were parcellated using FreeSurfer software and Brainnetome atlas. The 5 million extracted tracks per subject by MRtrix software were classified based on the basic cortical structure (cortical area in the left and right hemisphere, subcortical area), after the tracks validation procedure. The number of terminals for each categorized track per unit-sized cortical area (1 mm3) was defined as the track-density in that cortical area. Track-density ratio mapping with fiber types was achieved by mapping the density-dependent color intensity for each categorized tracks with a different primary color. The mapping results showed a highly localized, unique density ratio map determined by fiber types. Furthermore, the quantitative group data analysis based on the parcellation information revealed that the majority of nerve fibers in the brain are association fibers, particularly in temporal, inferior parietal, and occipital lobes, while the projection and commissural fibers were mainly located in the superior part of the brain. Hemispheric asymmetries in the fiber density were also observed, such as long association fiber in the Broca's and Wernicke's areas. We believe this new dimensional brain mapping information allows us to further understand brain anatomy, function.

Metal-organic-framework-derived hierarchical Co/CoP-decorated nanoporous carbon polyhedra for robust high-energy storage hybrid supercapacitors.

Electrode materials exhibiting nanostructural design, high surface area, tunable pore size, and efficient ion diffusion/transportation are essential for achieving improved electrochemical performance. In this study, we successfully prepared cobalt phosphide and cobalt nanoparticles embedded into nitrogen-doped nanoporous carbon (CoP-CoNC/CC) using a simple precipitation method followed by pyrolysis-phosphatization. Subsequently, we employed CoP-CoNC/CC as the electrode for supercapacitor applications. Notably, the resultant CoP-CoNC/CC displayed a high surface area with tunable porosity. Based on the benefits of the CoP in CoNC/CC, improved electrochemical performance was achieved with a specific capacitance of 975 F g-1 at 1 mA cm-2 in a 2 M KOH electrolyte. The assembled hybrid supercapacitor using CoP-CoNC/CC (positive electrode) and activated carbon (AC) (negative electrode) exhibited a specific capacitance of 144 F g-1, a specific energy of 39.2 W h kg-1 at 1960 W kg-1 specific power, with better cyclic stability. The higher performance can be attributed to the synergetic effect between CoP, Co metal, and the nitrogen-doped nanoporous carbon in three-dimensional carbon cloth (CC). These excellent properties make CoP-CoNC/CC a promising electrode for developing future energy-storage devices.

Effect of Winding Tension on Electrical Behaviors of a No-Insulation ReBCO Pancake Coil.

This paper presents a study on the effects of winding tension on the characteristic resistance of a no-insulation (NI) coil. Two ReBCO NI test pancake coils, having the same winding i.d. (60 mm), o.d. (67.6 mm), and number of turns (60), were sequentially prepared in a way that the first test coil was wound with a winding tension of 12-N, tested, and then rewound with a new winding tension of 20-N for the same tests. In each test, the test coil was energized at a target current, the power supply was "suddenly" disconnected, and then the temporal decay of the coil center field was measured, from which the time constant of the test coil and the consequent characteristic resistance were obtained. To check the reproducibility of experimental data, each test was repeated four times and each time the test coil was unwound and rewound with a given winding tension. The experimental results were analyzed with equivalent circuit analyses. Correlation between the winding tension and the characteristic resistance was discussed in detail.

Turn-to-turn contact characteristics for an equivalent circuit model of no-insulation ReBCO pancake coil.

This paper presents experimental and analytical studies on the characteristic resistance of NI (no-insulation) ReBCO pancake coils, which are used in an equivalent circuit model to characterize 'radial as well as spiral' current paths within the NI coils. We identified turn-to-turn contact resistance as a major source of the characteristic resistance of an NI coil. In order to verify this, three single pancake NI HTS coils-60, 40, 20 turns-were fabricated with their winding tension carefully maintained constant. A sudden discharge test was performed on each coil to obtain its characteristic resistance, and the relation between the turn-to-turn contact and the characteristic resistance was investigated. Based on the characteristic resistance and the n-value model, an equivalent circuit model was proposed to characterize the time-varying response of the NI coils. Charging tests were performed on the three test coils and the experimental results were compared with the simulated ones to validate the proposed approach with the equivalent circuit model.

No-Insulation Coil Under Time-Varying Condition: Magnetic Coupling With External Coil.

This paper presents experimental and analytical studies on the time-varying behavior of an NI (no-insulation) high-temperature superconductor pancake coil, alone or magnetically coupled to an external coil. An NI coil and another insulated coil (as an external), both of identical winding i.d. and number of turns, were fabricated. Another external coil used in this study was a 300-mm/5-T low-temperature superconductor magnet. An equivalent circuit model is proposed to simulate the NI coil, and the external coil, under time-varying conditions. Good agreement between experiment and simulation shows that the proposed equivalent circuit model is valid to characterize the time-varying electromagnetic behavior of an NI coil, alone or magnetically coupled to an external coil.

Effect of annealing environments on self-organized TiO2 nanotubes for efficient photocatalytic applications.

In the present study, amorphous titanium dioxide (TiO2) nanotubes were synthesized by one-step anodization technique and subsequently annealed in different environments to investigate the effect of annealing atmospheres on the formation of different crystalline phases. X-ray Diffraction (XRD) patterns clearly showed the presence of anatase TiO2 phase with various crystallite sizes. The samples annealed in oxygen and air atmospheres at 500 degrees C showed a dominant anatase phase and a small amount of rutile phase, on the other hand, the samples annealed in nitrogen and argon atmospheres and in a vacuum at 500 degrees C contained the anatase phase only. XPS analysis of the samples showed a broadening in the binding energy curves with respect to variation in annealing atmosphere, confirming the variation in surface defects, which in turn affect photocatalytic degradation. The vacuum-annealed sample showed superior photocatalytic degradation efficiency as it had relatively higher pseudo-first order rate constants (k) of 0.009/min.

Synthesis of copper hydroxide and oxide nanostructures via anodization technique for efficient photocatalytic application.

We have demonstrated a facile protocol for synthesizing CuO and Cu2O mixed-phase nanostructures by anodization of copper hydroxide (Cu(OH)2) nanoneedles and their heat treatment in different atmospheres, which affect photocatalytic degradation efficiency. The oxygen annealed sample had relatively small (100 nm) lamellar, spherical nanoparticulate structures on the substrate surface, which showed better photocatalytic degradation of reactive black 5 dye resulting from the appropriate morphology and phase formation, compared to the samples annealed in different atmospheres and vacuum. The pseudo first-order rate constant (k) of the oxygen annealed sample was 0.0054/min, which was relatively high due to the formation of a CuO-Cu2O heterojunction with matching band potentials. Air, nitrogen, argon and vacuum annealing resulted in bigger particles and different morphologies, which led to pseudo first-order rate constants (k) of 0.0032/min (air-annealed); 0.0021/min (N2-annealed); 0.0033/min (Ar-annealed); and 0.0027/min (vacuum-annealed), which resulted in poor photocatalytic degradation of the reactive black 5 dye.

Field Mapping, NMR Lineshape, and Screening Currents Induced Field Analyses for Homogeneity Improvement in LTS/HTS NMR Magnets.

This paper describes two general methods: field map processing and NMR lineshape analysis, that we are currently using for the on-going research of field improvement techniques specifically applied to our 700 MHz LTS/HTS NMR magnet. The validity of the methods is verified with comparison between calculations and experiments. Also, a simple but effective analysis has been used to identify the principal source of a remanent magnetic field measured in the bore of the 700 MHz LTS/HTS NMR magnet: the Screening Current induced Field (SCF) from the 100-MHz HTS insert, comprised of 48 double pancake coils, each wound with Bi2223 tape.

A Solid Nitrogen Cooled MgB(2) "Demonstration" Coil for MRI Applications.

A 700-mm bore superconducting magnet was built and operated in our laboratory to demonstrate the feasibility of newly developed MgB(2) superconductor wire for fabricating MRI magnets. The magnet, an assembly of 10 coils each wound with a reacted and s-glass insulated wire ~1-km long, was immersed in solid nitrogen rather than in a bath of liquid cryogen. This MgB(2) magnet was designed to operate in the temperature range 10-15 K, maintained by a cryocooler. A combination of this "wide" temperature range and immersion of the winding in solid nitrogen enables this magnet to operate under conditions not possible with a low temperature superconductor (LTS) counterpart. Tested individually at 13 K, each coil could carry current up to 100 A. When assembled into the magnet, some coils, however, became resistive, causing the magnet to prematurely quench at currents ranging from 79 A to 88 A, at which point the magnet generated a center field of 0.54 T. Despite the presence of a large volume (50 liters) of solid nitrogen in the cold body, cooldown from 77 K to 10 K went smoothly.