Discotic liquid crystals as novel corrosion-resistant coatings.

A discotic liquid crystal (DLC), HBC-C12, coating was successfully applied to improve the corrosion resistance of an iron surface. The iron surface with the DLC-coating exhibited improved corrosion resistance in various environments, including exposure to air and solutions with different pH values. To the best of our knowledge, studies regarding corrosion protection using DLCs have never been reported.

Trichostatin A suppresses EGFR expression through induction of microRNA-7 in an HDAC-independent manner in lapatinib-treated cells.

Lapatinib, a dual EGFR/HER2 tyrosine kinase inhibitor, has been shown to improve the survival rate of patients with advanced HER2-positive breast cancers. However, the off-target activity of lapatinib in inducing EGFR expression without tyrosine kinase activity was demonstrated to render HER2-negative breast cancer cells more metastatic, suggesting a limitation to the therapeutic effectiveness of this dual inhibitor in HER2-heterogeneous tumors. Therefore, targeting EGFR expression may be a feasible approach to improve the anticancer efficiency of lapatinib-based therapy. Inhibition of HDAC has been previously reported to epigenetically suppress EGFR protein expression. In this study, however, our data indicated that treatment with HDAC inhibitors trichostatin A (TSA), but not suberoylanilide hydroxamic acid (SAHA) or HDAC siRNA, can attenuate both protein and mRNA expressions of EGFR in lapatinib-treated triple-negative breast cancer cells, suggesting that TSA may suppress EGFR expression independently of HDAC inhibition. Nevertheless, TSA reduced EGFR 3'UTR activity and induced the gene expression of microRNA-7, a known EGFR-targeting microRNA. Furthermore, treatment with microRNA-7 inhibitor attenuated TSA-mediated EGFR suppression. These results suggest that TSA induced microRNA-7 expression to downregulate EGFR expression in an HDAC-independent manner.

The metal grating design of plasmonic hybrid III-V/Si evanescent lasers.

A hybrid III-V/silicon laser design with a metal grating layer inserted in between is proposed and numerically studied. The metal grating layer is buried in a silicon ridge waveguide surrounded by silicon dioxide, and its structural parameters such as periodicity, width and depth can be varied for optimization purpose. The plasmonic effect originated from the grating layer can manage optical fields between III-V and silicon layers in hopes of dimension reduction. The substrate is planarized to minimize the bonding failure. A numerical algorithm with various combinations of metal grating and waveguide structural parameters was created and the optimal design with 730 nm grating period and 600 nm of buried waveguide ridge height was obtained by minimizing the corresponding laser threshold. With top AlInGaAs quantum wells and optimized design of hybrid metal/silicon waveguide, a 0.6 µm(-1) threshold gain can be achieved.

Nanocasting technique to prepare lotus-leaf-like superhydrophobic electroactive polyimide as advanced anticorrosive coatings.

Nanocasting technique was used to obtain a biomimetic superhydrophobic electroactive polyimide (SEPI) surface structure from a natural Xanthosoma sagittifolium leaf. An electroactive polyimide (EPI) was first synthesized through thermal imidization. An impression of the superhydrophobic Xanthosoma sagittifolium leaf was then nanocasted onto the surface of the EPI so that the resulting EPI was superhydrophobic and would prevent corrosion. Polydimethylsiloxane (PDMS) was then used as a negative template to transfer the impression of the superhydrophobic surface of the biomimetic EPI onto a cold-rolled steel (CRS) electrode. The superhydrophobic electroactive material could be used as advanced coatings that protect metals against corrosion. The morphology of the surface of the as-synthesized SEPI coating was investigated using scanning electron microscopy (SEM). The surface showed numerous micromastoids, each decorated with many nanowrinkles. The water contact angle (CA) for the SEPI coating was 155°, which was significantly larger than that for the EPI coating (i.e., CA = 87°). The significant increase in the contact angle indicated that the biomimetic morphology effectively repelled water. Potentiodynamic and electrochemical impedance spectroscopic measurements indicated that the SEPI coating offered better protection against corrosion than the EPI coating did.

Enhanced angular characteristics of indium tin oxide nanowhisker-coated silicon solar cells.

Omnidirectional and broadband light harvesting is critical to photovoltaics due to the sun's movement and its wide spectral range of radiation. In this work, we demonstrate distinctive indium-tin-oxide nanowhiskers that achieve superior angular and spectral characteristics for crystalline silicon solar cells using angle-resolved reflectance spectroscopy. The solar-spectrum weighted reflectance is well below 6% for incident angles of up to 70° and for the wavelength range between 400nm and 1000nm. As a result, the nanowhisker coated solar cell exhibits broadband quantum efficiency characteristics and enhanced short-circuit currents for large angles of incidence.

Combined micro- and nano-scale surface textures for enhanced near-infrared light harvesting in silicon photovoltaics.

As silicon photovoltaics evolve towards thin-wafer technologies, efficient optical absorption for the near-infrared wavelengths has become particularly challenging. In this work, we present a solution that employs combined micro- and nano-scale surface textures to increase light harvesting in the near-infrared for crystalline silicon photovoltaics, and discuss the associated antireflection and scattering mechanisms. The surface textures are achieved by uniformly depositing a layer of indium-tin-oxide nanowhiskers on micro-grooved silicon substrates using electron-beam evaporation. The nanowhiskers facilitate optical transmission in the near-infrared by functioning as impedance matching layers with effective refractive indices gradually varying from 1 to 1.3. Materials with such unique refractive index characteristics are not readily available in nature. As a result, the solar cell with combined textures achieves over 90% external quantum efficiencies for a broad wavelength range of 460-980 nm, which is crucial to the development of advanced thin-substrate silicon solar cells.