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Adolescents and adults with a Fontan circulation are at risk of cognitive dysfunction; Attention and processing speed are notable areas of concern. Underlying mechanisms and brain alterations associated with worse long-term cognitive outcomes are not well determined. This study investigated brain white matter microstructure in adolescents and adults with a Fontan circulation and associations with resting and peak exercise oxygen saturations (SaONinety-two participants with a Fontan circulation (aged 13-49 years, ≥5 years post-Fontan completion) had diffusion MRI. Averaged tract-wise diffusion tensor imaging (DTI) metrics were generated for 34 white matter tracts of interest. Resting and peak exercise SaOForty-nine participants were male (53%), mean age was 23.1 years (standard deviation (SD) = 7.8 years). Mean resting and peak exercise SaOChronic hypoxemia may have long-term detrimental impact on white matter microstructure in people living with a Fontan circulation. Paradoxical associations between processing speed and tract-specific DTI metrics could be suggestive of compensatory white matter remodeling. Longitudinal investigations focused on the mechanisms and trajectory of altered white matter microstructure and associated cognitive dysfunction in people with a Fontan circulation are required to better understand causal associations.

Diffusion MRI streamlines tractography has become a major technique for inferring structural networks through reconstruction of brain connectome. However, quantification of structural connectivity based on the number of streamlines interconnecting brain grey matter regions is known to be problematic in a number of aspects, such as the ill-posed nature of streamlines terminations and the non-quantitative nature of streamline counts. This study investigates the effects of state-of-the-art connectome construction methods on the subsequent analyses of structural brain networks using graph theoretical approaches. Our results demonstrate that the characteristics of structural connectivity, including connectome variability, global network metrics, small-world attributes and network hubs, alter significantly following the improvement in biological accuracy of streamlines tractograms provided by anatomically-constrained tractography (ACT) and spherical-deconvolution informed filtering of tractograms (SIFT). Importantly, the commonly-used correction for connection density based on scaling the contribution of each streamline to the connectome by its inverse length is shown to provide incomplete correction, highlighting the necessity for the use of advanced tractogram reconstruction techniques in structural connectomics research.

Rare earth co-activated CeO2 phosphors are synthesized via hydrothermal process. Tb3+ and Yb3+ ions are deliberately incorporated in CeO2 host to convert high-energy photons into two near infrared photons with low energy for quantum cutting applications. The observed broad excitation ranging from 260 to 300 nm is associated with f-d transitions of Tb3+ ions. A strong green emission at 540 nm for Tb3+ ions along with typical Yb3+ emission band ranging from 950 to 1100 nm are observed under UV excitation. The PL intensity of Tb3+ ions starts to reduce with increase in Yb3+ emission as Yb3+ concentration increased, indicating an efficient energy transfer from Tb3+ to Yb3+. Photoluminescence decay times of CeO2:Tb3+/Yb3+ phosphors show reduction in lifetime from 2.32 to 0.83 ms with elevation of Yb3+ concentration from 0 to 12.5 mol%. Obtained results reveal the suitability of present phosphors in near-infrared quantum cutting applications.

The commercial technologies for aluminium production include production of alumina from bauxite and smelting of alumina to produce aluminium. The current technology is energy intensive, and a major source of greenhouse gas emissions and harmful fluoride emissions. Carbothermal reduction of bauxite is a promising alternative technology for aluminium and aluminoalloy production. Western Australia and Queensland bauxite ores were carbothermally reduced in steps in argon. Experiments were performed in a high temperature vertical tube furnace, and the off-gas composition was monitored using an infra-red gas analyser. The phase composition of reduced samples was characterised by XRD. Oxygen and carbon contents in reduced samples were determined by LECO analysers. The morphology of the surface and intersections was observed by SEM. The chemical compositions of the phases in the reduced samples were detected by EDS. The results of this study have proved the concept of stepwise reduction of bauxite ores in solid state by appropriate control of reduction temperature. Below 1100 °C, only iron oxides were reduced to metallic iron. A ferroalloy phase was formed at 1200 °C and above. The products in the bauxites reduced to 1600 °C include a ferroalloy of silicon and aluminium, carbides of titanium, silicon and aluminium, and unreacted alumina.

Using the Taguchi method, the authors analyzed the optimum conditions for (Y 3− x Ce x )Al 5 O 12 (YAG:Ce) phosphor, which is prepared using the solid-state reaction method. The controllable factors used in this study consisted of the following: (1) the duration of milling, (2) the quantity of substitution, (3) the duration of sintering, and (4) the temperature of sintering. Under optimum conditions, a confirmation experiment was carried out, and the average photoluminescence (PL) intensity of YAG:Ce phosphor was found to be up to 270.84 (a.u.). The percentage contribution of each controllable factor was also determined. Most interestingly, the temperature of sintering is the most influential factor within current investigation range to the solid-state-prepared YAG:Ce phosphor, and its value of percentage contribution is up to 70.90%. Aside from this, through the optimum conditions, the average PL intensity of YAG:Ce phosphor can be substantially promoted from 193.88 (a.u.), the average PL intensity of YAG:Ce phosphor sintered at 1500 °C for 6 h that was usually used to sinter YAG:Ce phosphor.

Diffusion orientation transform (DOT) is a powerful imaging technique that allows the reconstruction of the microgeometry of fibrous tissues based on diffusion MRI data. The three main error sources involving this methodology are the finite sampling of the q-space, the practical truncation of the series of spherical harmonics and the use of a mono-exponential model for the attenuation of the measured signal. In this work, a detailed mathematical description that provides an extension to the DOT methodology is presented. In particular, the limitations implied by the use of measurements with a finite support in q-space are investigated and clarified as well as the impact of the harmonic series truncation. Near- and far-field analytical patterns for the diffusion propagator are examined. The near-field pattern makes available the direct computation of the probability of return to the origin. The far-field pattern allows probing the limitations of the mono-exponential model, which suggests the existence of a limit of validity for DOT. In the regimen from moderate to large displacement lengths the isosurfaces of the diffusion propagator reveal aberrations in form of artifactual peaks. Finally, the major contribution of this work is the derivation of analytical equations that facilitate the accurate reconstruction of some orientational distribution functions (ODFs) and skewness ODFs that are relatively immune to these artifacts. The new formalism was tested using synthetic and real data from a phantom of intersecting capillaries. The results support the hypothesis that the revisited DOT methodology could enhance the estimation of the microgeometry of fiber tissues.

Diffusion-weighted magnetic resonance imaging has the ability to map neuronal architecture by estimating the 3D diffusion displacement within fibrous brain structures. This approach has non-invasively been demonstrated in the human brain with diffusion tensor tractography. Despite its valuable application in neuroscience and clinical studies however, it faces an inherent limit in mapping fiber tracts through areas with intervoxel incoherence. Recent advances in high angular resolution diffusion imaging have surpassed this limit and have the ability to resolve the complex fiber intercrossing within each MR voxel. To connect the fiber tracts from a multi-fiber system, this study proposed a modified fiber assignment using the continuous tracking (MFACT) algorithm and a tracking browser to propagate tracts along complex diffusion profiles. The Q-ball imaging method was adopted to acquire the diffusion displacements. Human motor pathways with seed points from the internal capsule, motor cortex, and pons were studied respectively. The results were consistent with known anatomy and demonstrated the promising potential of the MFACT method in mapping the complex neuronal architecture in the human brain.

In this study a sandwich TiO2 thin-film electrode for a dye-sensitized solar cell was designed and fabricated. It contained a nanocrystalline TiO2 layer that was sandwiched between an ITO (indium tin oxide) substrate and a layer of TiO2/dye composite particles. Dry particle coating was performed to coat powdered CuPc dye (copper phthalocyanine C32H16CuN8) on the surface of TiO2 powder. A nanocrystalline TiO2 layer and a layer of TiO2/dye composite particles were subsequently fabricated in that order on the ITO substrate. This layer of the TiO2/dye composite particles markedly increased the short-circuit photocurrent from 0.2 μA(conventional DSSC) to 4 μA(DSSC with a layer of TiO2/dye composite particles) because of the improved coverage of the TiO2 surface by the powder of CuPc dye. Nevertheless, this layer of TiO2/dye composite particles slightly increased the open-circuit photovoltage from 0.25 V (conventional DSSC) to 0.28 V (DSSC with a layer of TiO2/dye composite particles). The effects of the mass ratio of TiO2 to the CuPc dye and the rate of rotation of the rotating chamber on the short-circuit photocurrent were investigated. Graphical abstract This study designed and fabricated a sandwich TiO2 thin-film electrode for a dye-sensitized solar cell (DSSC), which contained a nanocrystalline TiO2 layer that was sandwiched between an ITO substrate and a layer of TiO2/dye composite particles. This layer of TiO2/dye composite particles markedly increases the short-circuit photocurrent from 0.2 μA(conventional DSSC) to 4 μA(DSSC with a layer of TiO2/dye composite particles) because of the better coverage of the TiO2 surface by the powder of CuPc dye. Download : Download full-size image

Diffusion-weighted imaging can potentially be used to infer the connectivity of the human brain in vivo using fibre-tracking techniques, and is therefore of great interest to neuroscientists and clinicians. A key requirement for fibre tracking is the accurate estimation of white matter fibre orientations within each imaging voxel. The diffusion tensor model, which is widely used for this purpose, has been shown to be inadequate in crossing fibre regions. A number of approaches have recently been proposed to address this issue, based on high angular resolution diffusion-weighted imaging (HARDI) data. In this study, an experimental model of crossing fibres, consisting of water-filled plastic capillaries, is used to thoroughly assess three such techniques: constrained spherical deconvolution (CSD), super-resolved CSD (super-CSD) and Q-ball imaging (QBI). HARDI data were acquired over a range of crossing angles and b-values, from which fibre orientations were computed using each technique. All techniques were capable of resolving the two fibre populations down to a crossing angle of 45 degrees , and down to 30 degrees for super-CSD. A bias was observed in the fibre orientations estimated by QBI for crossing angles other than 90 degrees, consistent with previous simulation results. Finally, for a 45 degrees crossing, the minimum b-value required to resolve the fibre orientations was 4000 s/mm(2) for QBI, 2000 s/mm(2) for CSD, and 1000 s/mm(2) for super-CSD. The quality of estimation of fibre orientations may profoundly affect fibre tracking attempts, and the results presented provide important additional information regarding performance characteristics of well-known methods.

This investigation designed and fabricated a working electrode with a layer of TiO2/dye composite particles on an indium–tin oxide (ITO) substrate for a dye-sensitized solar cell (DSSC). The dry particle coating technique was performed to coat the powder of the CuPc dye (copper phthalocyanine C32H16CuN8) on the surface of TiO2 powder by the Mechanofusion method. A layer of TiO2/dye composite particles was fabricated on the ITO substrate using the doctor blade technique and the working electrode was then sintered in a furnace at 165°C for 1 h. The performance of the DSSC with a layer of TiO2/dye composite particles on an ITO substrate was not inferior to that of the conventional DSSC by dipping the working electrode in the solution of dye. Furthermore, the effects of the mass ratio of TiO2 to CuPc dye and the rate of rotation of the rotating chamber in the Mechanofusion system on the short-circuit photocurrent were investigated. Most importantly, this study not only sustains the applicability of TiO2/dye composite particles to improve the performance of the DSSC, but also provides an alternate process, which can avoid the time that is needed to dip the working electrode into the solution of the dye in fabricating a conventional DSSC.

This work studies the moving pattern and collision attrition of magnetic Ni particles in pure water in a flask on top of an actuator that contains a rotating bar magnet. A Gauss meter, a digital camera, a particle size analyzer and a transmission electron microscope were adopted to record the magnetic field, the moving patterns, the particle size distributions and the micrographs of magnetic Ni powders, respectively. The effects of the placement of a bar magnet with the interface between the positive and negative poles in a bar magnet at an angle of inclination β, the amount of the starting material, and the duration of attrition on the moving pattern and the shrinkage of the Ni particles were elucidated. The distribution of magnetic lines of force was predicted and visualized. The attrition of the Ni particles is determined from the number of collisions among Ni particles. More initial Ni particles correspond to faster particle shrinkage and more ultra-fine Ni powder. Although the magnetic field is strongest at β = 0°, the attrition was maximal at β = 30°.