MTF performance verification of an athermalized large-aperture IR optical system for space environment.

We develop an athermalized IR optical system operating in the temperature range of 10°C-30°C in vacuum. As large defocus errors can occur in IR optical systems in such an environment, we estimate the amount of defocus induced by the thermoelastic effect, thermo-optic effect, and air-to-vacuum transition. Furthermore, we measure the modulation transfer function (MTF) performance of our IR optical system in a thermal vacuum chamber. Our athermal system design and accurate estimation of the air-to-vacuum transition effect enable the realization of a stable IR optical system for a space environment, which exhibits an MTF value greater than 18%.

Decursin prevents TPA-induced invasion through suppression of PKCα/p38/NF-κB-dependent MMP-9 expression in MCF-7 human breast carcinoma cells.

Decursin, a coumarin compound, was first isolated from the roots of Angelica gigas almost four decades ago. It was found to exhibit cytotoxicity against various human cancer cells and to possess anti-amnesic activity in vivo through the inhibition of AChE activity. However, the effect of decursin on breast cancer invasion is unknown. Matrix metalloproteinase-9 (MMP-9) is known to be an important factor for cancer cell invasion. Therefore, in this study, we investigated the inhibitory effect of decursin on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced MMP-9 expression and cell invasion, as well as the molecular mechanisms involved in MCF-7 cells. Our results showed that decursin inhibits TPA-induced MMP-9 expression and cell invasion through the suppression of NF-κB. Furthermore, decursin repressed the TPA-induced phosphorylation of p38 MAPK and inhibited TPA-induced translocation of PKCα from the cytosol to the membrane, but did not affect the translocation of PKCδ. These results indicate that decursin-mediated inhibition of TPA-induced MMP-9 expression and cell invasion involves the suppression of the PKCα, MAPK and NF-κB pathways in MCF-7 cells. Thus, decursin may have potential value in restricting breast cancer metastasis.

Three-shell-based lens barrel for the effective athermalization of an IR optical system.

We have developed a new IR optical system that consists of three mirrors and four lenses, and that operates in the temperature range 8°C-32°C. This temperature range can induce thermoelastic deformation in the lenses and their mounting subassembly, leading to a large defocus error associated with the displacement of the lenses inside the barrel. We suggest using a new three-shell-based athermalization structure composed of two materials with different coefficients of thermal expansion (Invar and aluminum). A finite element analysis and the experiment data were used to confirm that this new athermalization barrel had a defocus error sensitivity of 11.6 nm/°C; this is an improvement on the widely used conventional single-shell titanium barrel model, which has a defocus error sensitivity of 29.8 nm/°C. This paper provides the technical details of the new athermalization design, and its computational and experimental performance results.