Yolk-shell-structured MoSe₂ microspheres were prepared via a simple selenization process of MoO₃ microspheres. The yolk-shell-structured MoSe₂ and MoO₃ microspheres delivered initial discharge capacities of 527 and 465 mA h g(-1) in the voltage range of 0.001-3 V vs. Na/Na(+) at a current density of 0.2 A g(-1), respectively, and their discharge capacities after 50 cycles were 433 and 141 mA h g(-1), respectively. The yolk-shell-structured MoSe₂ microspheres also exhibited outstanding high rate capabilities. The hierarchical yolk-shell structure comprised of wrinkled nanosheets facilitated fast Na-ion and electron kinetics, and buffered the large volume changes encountered during cycling.

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Yolk-shell MoS2 powders with a distinct configuration of MoS2@void@MoS2 were prepared for the first time by applying spray pyrolysis. The yolk-shell MoO3 powders prepared by spray pyrolysis were converted into MoS2 powders by a simple sulfidation process at 400 °C without altering the morphology. Dense structured MoS2 powders were also prepared by a similar process. The respective initial discharge capacities of the yolk-shell and dense structured MoS2 powders at a current density of 1000 mA g(-1) were 651 and 490 mA h g(-1), and the corresponding capacity retentions after 100 cycles measured from the second cycle were 100 and 72%.

Recently, an iterative reconstruction-reprojection (IRR) algorithm has been suggested for application to limited view computed tomography (CT). In the IRR, the interpolation operation is performed in the object space during backprojection-reprojection. The errors associated with the interpolation degrade the reconstructed image and may cause divergence unless a large number of rays is used. In this paper, we propose a projection space iterative reconstruction-reprojection (PSIRR) algorithm based on backprojection-reprojection in the projection space. In the process of the backprojection-reprojection, iteration is performed with a single equation instead of multiple equations and interpolation is eliminated. Computer simulation results are presented, and image quality of the PSIRR algorithm shows a substantial improvement compared to the original IRR algorithm. In addition, the new algorithm was applied to ultrasonic attenuation CT using a sponge phantom.

The improvement of optical and physical performances of blue emitting phosphors is needed in order to increase the brightness of flat panel displays and fluorescent lamps (FLs). The hexaaluminate particles doped with Eu 2ϩ have been key phosphors as blue light source in the plasma display panel (PDP) and FLs because of their high luminescence efficiency and stability under vacuum ultraviolet light excitation. 1-2 The critical problem in the manufacture of PDP and FL using hexaaluminate phosphor is the morphology of the particles. In conventional firing techniques, hexaaluminate particles have plate-like shapes because of their crystal growth characteristics. It is known that the morphology of phosphor particles plays an important role in improving the performances of flat panel displays and lamps. 3-6 The use of spherical phosphor particles should increase the screen brightness and improve the resolution because of lower scattering of evolved light and higher packing densities than irregularly shaped particles obtained by conventional methods. Spherical morphology also furnishes good screening properties to produce phosphor layers with good uniformity and proper adhesion strength to the substrate for practical application.Spray pyrolysis furnishes a feasible process for the preparation of improved phosphor particles. 7-9 The phosphor particles prepared by spray pyrolysis have spherical shape, fine size, narrow size distribution, and nonaggregation characteristics because of the particle formation mechanism in spray pyrolysis. In previous work, BaMgAl 10 O 17 :Eu 2ϩ phosphor system was investigated in the ultrasonic spray pyrolysis, in which aggregation of particles prepared at low temperatures (<1200ЊC) by spray pyrolysis occurred after posttreatment for crystallization and activation because of high ductility of Mg component. 10 In this work, BaMgAl 10 O 17 :Eu 2ϩ phosphor particles with complete spherical shape and submicrometer size were prepared by post-treatment of as-prepared particles obtained by the spray pyrolysis. To control the morphology of particles, a colloidal solution of aluminum hydroxide obtained by hydrolysis of aluminum isopropoxide was used to aluminum source. In the system of BaMgAl 10 O 17 :Eu 2ϩ , the intermediate compound played a key role in the preparation of particles having complete sphericity and nonaggregation.Experimental The BaMgAl 10 O 17 :Eu 2ϩ (BAM) particles, which refer to Ba 0.9 Eu 0.1 MgAl 10 O 17 , were prepared by the spray pyrolysis from colloidal and aqueous solutions. The colloidal solution was prepared from aluminum isopropoxide and metal nitrates for other components. Aluminum isopropoxide (AIP) was hydrolyzed to form the aluminum hydroxide solution at 85ЊC. Peptization was followed adding small amount of nitric acid to form a stable solution. This peptized solution was composed of fibrils with lengths of several tens of nanometers. A stoichiometric amount of each salt was dissolved in this stable solution. The aqueous solution was prepared from each metal nitrate d...