Ultrasound-assisted synthesis of Li-rich mesoporous LiMn2O4 nanospheres for enhancing the electrochemical performance in Li-ion secondary batteries

The hierarchically structured mesoporous LiMn₂O₄ (LMO) nanospheres were synthesized using a template-free self-assembly process that was coupled with ultrasound (U). The ultrasound technique suggested here is very powerful for controlling an ordered nanostructure and improving crystallinity with large single-crystalline domains. Owing to the hierarchical mesoporous structure and high crystallinity, U-LMO provides an excellent rate capability and cycle stability with a capacity retention of more than 98% up to 50 cycles at a 0.2 C rate. Here, we demonstrate that mesoporous U-LMO nanospheres were fabricated to enhance the electrochemical performance and protect it from structurally significant collapsing because of high crystallinity.     

Surface–plasmon-coupled photoluminescence from CdS nanoparticles with Au films

The enhancement of surface–plasmon-coupled photoluminescence from CdS nanoparticles was examined for various thicknesses of sputtered Au films. The improved luminescence with thickness control of Au correlated well with the increased density of surface–plasmon states, which was modified by the plasmon-dispersion relation at the planar Au/PMMA interface. By annealing the Au films to form a rough surface morphology, the emission in the CdS nanoparticles was further enhanced by the improved excitation and coupling of the surface–plasmon modes.     

Aberration characterization for the optimal design of high-resolution endoscopic optical coherence tomography catheters

We study the major factors causing degradation in the lateral resolution of gradient-index-lens-based catheters used for high-resolution optical coherence tomography. Chromatic aberration and astigmatism were taken into account in the propagation of broadband single-mode Gaussian beams through the catheter geometry. It was found that, while chromatic aberration did not preclude achieving high resolution, astigmatism posed a major technical difficulty, because its correction requires a very sensitive adjustment of parameters, especially for catheters with long working distances.     

Growth evolution and microstructural characterization of semipolar (112̄2) GaN selectively grown on etched r-plane sapphire

Semipolar (112?2) GaN was grown on stripe etched r-plane sapphire substrate by a maskless selective growth method. The initial stage of growth is analyzed by describing the competitive nucleation mechanisms, due to the interplay between kinetics and energetics, on disparate crystallographic planes within the diffusion length of adatoms. The microstructure of the final coalesced semipolar GaN film is revealed by x-ray rocking curve (XRC) analysis and transmission electron microscopy (TEM). XRC analysis yields linewidths between 280 and 550 arcsec for all on-axis and off-axis diffractions. Linewidth broadening factors in dislocated crystals are considered, and a large reduction of stacking fault density can be seen from the measured linewidths as fit to this model. TEM shows a change in the defect characteristics as compared to conventional growth on m-sapphire, filtering of stacking faults and confirmation of the low dislocation density of the final GaN film. The microstructural quality of the film substantiates the possibility of using an inclined basal-plane growth to synthesize non-basal-plane active devices, thus removing the rigid restrictions in contemporary GaN nonpolar and semipolar heteroepitaxy.     

Silica xerogel films hybridized with carbon nanotubes by single step sol–gel processing

Synthesis of multi-walled carbon nanotubes (MWCNTs) doped silica xerogel films was reported in this work. A crucial step of introducing MWCNTs was achieved by functionalizing them by acid treatment to form stable and homogenous SiO₂/MWCNTs sol. Scanning electron microscopy showed spherical particles in honeycomb network structure for undoped xerogel films whereas dispersion and wrapping of MWCNTs in silica matrix was observed for MWCNTs doped films. Various bond formations during the sol–gel process and surface modification were confirmed using Fourier transform infra-red and detailed study on the chemical bonding state of the films was carried out using X-ray photoelectron spectroscopy. Nanoindentation studies showed that the mechanical properties of MWCNTs doped xerogel film increase dramatically: higher modulus (E = 2.127 ± 0.095 GPa) and hardness (H = 0.035 ± 0.017 GPa) values than those of pristine xerogel film (E = 0.234 ± 0.058 GPa, H = 0.01 ± 0.003 GPa).     

Staurosporine and cytochalasin D induce chondrogenesis by regulation of actin dynamics in different way

Actin cytoskeleton has been known to control and/or be associated with chondrogenesis. Staurosporine and cytochalasin D modulate actin cytoskeleton and affect chondrogenesis. However, the underlying mechanisms for actin dynamics regulation by these agents are not known well. In the present study, we investigate the effect of staurosporine and cytochalasin D on the actin dynamics as well as possible regulatory mechanisms of actin cytoskeleton modulation. Staurosporine and cytochalasin D have different effects on actin stress fibers in that staurosporine dissolved actin stress fibers while cytochalasin D disrupted them in both stress forming cells and stress fiber-formed cells. Increase in the G-/F-actin ratio either by dissolution or disruption of actin stress fiber is critical for the chondrogenic differentiation. Cytochalasin D reduced the phosphorylation of cofilin, whereas staurosporine showed little effect on cofilin phosphorylation. Either staurosporine or cytochalasin D had little effect on the phosphorylation of myosin light chain. These results suggest that staurosporine and cytochalasin D employ different mechanisms for the regulation of actin dynamics and provide evidence that removal of actin stress fibers is crucial for the chondrogenic differentiation.     

Molecules and their functions in autophagy

Autophagy is a self-degradation system of cellular components through an autophagosomal-lysosomal pathway. Over the last 15 yr, yeast genetic screens led to the identification of a number of genes involved in the autophagic pathway. Most of these autophagy genes are present in higher eukaryotes and regulate autophagy process for cell survival and homeostasis. Significant progress has recently been made to better understand the molecular mechanisms of the autophagy machinery. Especially, autophagy process, including the regulation of autophagy induction through mTOR and the nucleation and elongation in autophagosome formation through class III phosphatidylinositol 3-kinase complex and ubiquitin-like conjugation systems, became evident. While many unanswered questions remain to be answered, here, we summarize the recent process of autophagy with emphasis on molecules and their protein complexes along with advanced molecular mechanisms that regulate the autophagy machinery.     

Co-immobilization of three cellulases on Au-doped magnetic silica nanoparticles for the degradation of cellulose

Three cystein-tagged cellulases co-immobilized on AuNP and Au-MSNP for the hydrolytic degradation of cellulose. The biochemical properties, stabilities, activities and reusability of these co-immobilized systems were compared to those of mixtures of free cellulases.