The Effect of Ethanol on Disassembly of Amyloid-ß1-42 Pentamer Revealed by Atomic Force Microscopy and Gel Electrophoresis.

The most common type of dementia, Alzheimer's disease, is associated with senile plaques formed by the filamentous aggregation of hydrophobic amyloid-ß (Aß) in the brains of patients. Small oligomeric assemblies also occur and drugs and chemical compounds that can interact with such assemblies have attracted much attention. However, these compounds need to be solubilized in appropriate solvents, such as ethanol, which may also destabilize their protein structures. As the impact of ethanol on oligomeric Aß assembly is unknown, we investigated the effect of various concentrations of ethanol (0 to 7.2 M) on Aß pentameric assemblies (Aßp) by combining blue native-PAGE (BN-PAGE) and ambient air atomic force microscopy (AFM). This approach was proven to be very convenient and reliable for the quantitative analysis of Aß assembly. The Gaussian analysis of the height histogram obtained from the AFM images was correlated with band intensity on BN-PAGE for the quantitative estimation of Aßp. Our observations indicated up to 1.4 M (8.3%) of added ethanol can be used as a solvent/vehicle without quantitatively affecting Aß pentamer stability. Higher concentration induced significant destabilization of Aßp and eventually resulted in the complete disassembly of Aßp.

Phonon transport in the nano-system of Si and SiGe films with Ge nanodots and approach to ultralow thermal conductivity.

Phonon transport in the nano-system has been studied using well-designed nanostructured materials to observe and control the interesting phonon behaviors like ballistic phonon transport. Recently, we observed drastic thermal conductivity reduction in the films containing well-controlled nanodots. Here, we investigate whether this comes from the interference effect in ballistic phonon transport by comparing the thermal properties of the Si or Si0.75Ge0.25 films containing Ge nanodots. The experimentally-obtained thermal resistance of the nanodot layer shows peculiar nanodot size dependence in the Si films and a constant value in the SiGe films. From the phonon simulation results, interestingly, it is clearly found that in the nanostructured Si film, phonons travel in a non-diffusive way (ballistic phonon transport). On the other hand, in the nanostructured SiGe film, although simple diffusive phonon transport occurs, extremely-low thermal conductivity (∼0.81 W m-1 K-1) close to that of amorphous Si0.7Ge0.3 (∼0.7 W m-1 K-1) is achieved due to the combination of the alloy phonon scattering and Ge nanodot scattering.

Resistive switching memory performance in oxide hetero-nanocrystals with well-controlled interfaces.

For realization of new informative systems, the memristor working like synapse has drawn much attention. We developed isolated high-density Fe3O4 nanocrystals on Ge nuclei/Si with uniform and high resistive switching performance using low-temperature growth. The Fe3O4 nanocrystals on Ge nuclei had a well-controlled interface (Fe3O4/GeOx/Ge) composed of high-crystallinity Fe3O4 and high-quality GeOx layers. The nanocrystals showed uniform resistive switching characteristics (high switching probability of ~90%) and relatively high Off/On resistance ratio (~58). The high-quality interface enables electric field application to Fe3O4 and GeOx near the interface, which leads to effective positively charged oxygen vacancy movement, resulting in high-performance resistive switching. Furthermore, we successfully observed memory effect in nanocrystals with well-controlled interface. The experimental confirmation of the memory effect existence even in ultrasmall nanocrystals is significant for realizing non-volatile nanocrystal memory leading to neuromorphic devices.