Measuring material parameters using a tunable monochromatic terahertz wave source.

We measured complex refractive indices of materials that transmitted well in the terahertz (THz) range using a tunable, monochromatic pulsed THz wave source and a high-sensitivity semiconductor detector. This approach is based on simple monochromatic transmission power measurements. Contrast enhancement by refractive index cladding was employed to measure the complex refractive indices. The experimental results were in good agreement with previously reported values. These results suggested that our approach could be used to quickly analyze material properties, such as surface roughness, and to determine the complex refractive indices of liquids or gases. In addition, as an application of the findings obtained here, we applied an anti-reflection polymer film to the silicon prism that served as an output coupler of the THz wave source. The film reduced surface reflection by 25%.

JAXA protein crystallization in space: ongoing improvements for growing high-quality crystals.

The Japan Aerospace Exploration Agency (JAXA) started a high-quality protein crystal growth project, now called JAXA PCG, on the International Space Station (ISS) in 2002. Using the counter-diffusion technique, 14 sessions of experiments have been performed as of 2012 with 580 proteins crystallized in total. Over the course of these experiments, a user-friendly interface framework for high accessibility has been constructed and crystallization techniques improved; devices to maximize the use of the microgravity environment have been designed, resulting in some high-resolution crystal growth. If crystallization conditions were carefully fixed in ground-based experiments, high-quality protein crystals grew in microgravity in many experiments on the ISS, especially when a highly homogeneous protein sample and a viscous crystallization solution were employed. In this article, the current status of JAXA PCG is discussed, and a rational approach to high-quality protein crystal growth in microgravity based on numerical analyses is explained.

Numerical model of protein crystal growth in a diffusive field such as the microgravity environment.

It is said that the microgravity environment positively affects the quality of protein crystal growth. The formation of a protein depletion zone and an impurity depletion zone due to the suppression of convection flow were thought to be the major reasons. In microgravity, the incorporation of molecules into a crystal largely depends on diffusive transport, so the incorporated molecules will be allocated in an orderly manner and the impurity uptake will be suppressed, resulting in highly ordered crystals. Previously, these effects were numerically studied in a steady state using a simplified model and it was determined that the combination of the diffusion coefficient of the protein molecule (D) and the kinetic constant for the protein molecule (ß) could be used as an index of the extent of these depletion zones. In this report, numerical analysis of these depletion zones around a growing crystal in a non-steady (i.e. transient) state is introduced, suggesting that this model may be used for the quantitative analysis of these depletion zones in the microgravity environment.

Deep UV light generation by a fiber/bulk hybrid amplifier at 199 nm.

A high-pulse-repetition-frequency (PRF) pulsed light source in the deep ultraviolet region has been realized by a multiple wavelength conversion technique using a hybrid fiber/bulk amplifier system. Output of 199 nm with a power of 50 mW was achieved at 2.4 MHz PRF. The 1 microm amplifier consisted of a Yb-doped fiber amplifier and a Nd-doped YVO(4) amplifier. A 1.5 microm fiber master-oscillator power amplifier was employed as the other fundamental source. The amplifiers exhibited good amplification properties in pulse energy, polarization extinction ratio, and spectrum for nonlinear wavelength conversion.

5-n-Butylpyridine-2-carboxylate-copper(II) and -iron(III) complexes.

In trans-bis(5-n-butylpyridine-2-carboxylato-kappa(2)N,O)bis(methanol-kappaO)copper(II), [Cu(C(10)H(12)NO(2))(2)(CH(4)O)(2)], the Cu atom lies on a centre of symmetry and has a distorted octahedral coordination. The Cu-O(methanol) bond length in the axial direction is 2.596 (3) A, which is much longer than the Cu-O(carboxylate) and Cu-N distances in the equatorial plane [1.952 (2) and 1.977 (2) A, respectively]. In mer-tris(5-n-butylpyridine-2-carboxylato-kappa(2)N,O)iron(III), [Fe(C(10)H(12)NO(2))(3)], the Fe atom also has a distorted octahedral geometry, with Fe-O and Fe-N bond-length ranges of 1.949 (4)-1.970 (4) and 2.116 (5)-2.161 (5) A, respectively. Both crystals are stabilized by stacking interactions of the 5-n-butylpyridine-2-carboxylate ligand, although hydrogen bonds also contribute to the stabilization of the copper(II) complex.

In vitro skin permeation of morphine hydrochloride during the finite application of penetration-enhancing system containing water, ethanol and l-menthol.

The effects of composition of applied solutions, containing water, ethanol (EtOH) and l-menthol (LM) as penetration enhancers, on the in vitro permeation of morphine hydrochloride (MPH) through excised hairless rat skin were examined in finite application experiments. Three of the five different applied solutions contained almost saturated LM and two contained levels of LM below the limit of solubility. Despite similar pseudo steady-state fluxes (maximum fluxes observed) of MPH from the solutions, lag time for the permeation of MPH from the saturated systems was shorter than that from the unsaturated systems. Lag times for the permeation of EtOH and LM from the saturated systems were also shorter than those from the unsaturated systems. Thermodynamic activity of LM is important for the enhancing effect against MPH permeation. At the beginning for the permeation experiment, the activity of LM in the unsaturated systems was lower than that in the saturated solutions. As the skin permeability of EtOH was higher than that of other components, the content of EtOH in the applied solution gradually decreased with time, while the activity of LM increased eventually showing a sufficient enhancing effect. Solvent drag effect was not important for the permeation of MPH, since penetration rate of MPH was independent of the time course of that of EtOH. The amount of LM migrating into skin appeared to be the most important parameter for the penetration-enhancing effect of the mixed system in the in vitro permeation of MPH through excised hairless rat skin.