X-ray diffraction of protein crystal grown in a nano-liter scale droplet in a microchannel and evaluation of its applicability

We describe the technical aspects of the in-situ X-ray diffraction of a protein crystal prepared by a nanodroplet-based crystallization method. We were able to obtain diffraction patterns from a crystal grown in a capillary without any manipulation. Especially in our experimental approach, the crystals that moved to the nanodroplet interface were fixed strongly enough to carry out X-ray diffraction measurements that could be attributed to the high surface tension of the nanodroplet. The crystal was damaged by an indirect action of the X-rays because our in-situ X-ray diffraction measurement was carried out in the liquid phase without freezing the crystal; however, the obtained several diffraction patterns were of sufficiently fine quality for the crystal structure factors to be generated. We consider the technical examination presented in this paper to represent a seamless coupling of crystallization to X-ray analysis.     

Ion engineering techniques for the preparation of the highly effective TiO<Subscript>2</Subscript> photocatalysts operating under visible light irradiation

The successful application of ion engineering techniques for the development of TiO₂ photocatalysts operating under visible and/or solar light irradiations has been summarized in this review article. First, we have physically doped various transition metal ions within a TiO₂ lattice on an atomic level by using an advanced metal ion implantation method. The metal ion implanted TiO₂ could efficiently work as a photocatalyst under visible light irradiation. Some field tests under solar light irradiation clearly revealed that the Cr or V ions implanted TiO₂ samples showed 2–3 times higher photocatalytic reactivity than the un-implanted TiO₂. Second, we have developed the visible light responsive TiO₂ thin film photocatalyst by a single process using an RF-magnetron sputtering (RF-MS) deposition method. The vis-type TiO₂ thin films showed high photocatalytic reactivity for various reactions such as reduction of NOx, degradation of organic compounds, and splitting of H₂O under visible and/or solar light irradiations.     

Cell separation by the combination of microfluidics and optical trapping force on a microchip

We investigated properties of cells affecting their optical trapping force and successfully established a novel cell separation method based on the combined use of optical trapping force and microfluidics on a microchip. Our investigations reveal that the morphology, size, light absorption, and refractive index of cells are important factors affecting their optical trapping force. A sheath flow of sample solutions created in a microchip made sample cells flow in a narrow linear stream and an optical trap created by a highly focused laser beam captured only target cells and altered their trajectory, resulting in high-efficiency cell separation. An optimum balance between optical trapping force and sample flow rate was essential to achieve high cell separation efficiency. Our investigations clearly indicate that the on-chip optical trapping method allows high-efficiency cell separation without cumbersome and time-consuming cell pretreatments. In addition, our on-chip optical trapping method requires small amounts of sample and may permit high-throughput cell separation and integration of other functions on microchips. Figure Optical trapping in a microchannel allows high-efficiency separation of cells, e.g., dead and live HeLa cells

Nazarov‐type Reactions in Water

Different in water! We have developed Nazarov‐type reactions in water. Different reaction courses compared with those in organic solvents are observed in water. In the presence of a scandium based, surfactant‐type catalyst, water‐trapping products are obtained exclusively. The results presented are unprecedented and provide a valuable extension to information available regarding organic reactions in water.

     

Photocatalytic activity of visible light-responsive TiO<Subscript>2</Subscript> thin films deposited on various anodized Ti-metal substrates by a RF magnetron sputtering method

Visible light-responsive TiO₂ (Vis-TiO₂) thin film has been deposited on two different kinds of anodized Ti-metal substrates, i.e., plate-type Titanystar (P-Titanystar) or non-woven fabric Titanystar (N-Titanystar) by a radio-frequency magnetron sputtering (RF-MS) method. These Vis-TiO₂ thin film photocatalysts (Vis-TiO₂/P-Titanystar and Vis-TiO₂/N-Titanystar) showed high activity for the oxidation of 2-propanol in water under UV light irradiation while Vis-TiO₂/N-Titanystar showed higher activity than Vis-TiO₂/P-Titanystar. Furthermore, photocatalytic activity of Vis-TiO₂/N-Titanystar was enhanced by the Pt deposition by an RF-MS deposition method. Pt loaded Vis-TiO₂/N-Titanystar (Pt-Vis-TiO₂/N-Titanystar) acted as an efficient photocatalyst for the oxidation of methanol vapor under UV light irradiation even in a flow system. Moreover, it was found that Pt-Vis-TiO₂/N-Titanystar is an effective photocatalyst for the oxidation of various organic compounds in gas phase or ammonia gas even under visible light irradiation (λ > 420 nm) at 293 K.     

Total synthesis of incednam, the aglycon of incednine

The first total synthesis of incednam (1), the aglycon of antibiotic incednine (2), is described. Incednine has been reported to exhibit significant inhibitory activity against the antiapoptotic oncoproteins Bcl-2 and Bcl-xL. The synthesis of 1 commenced with the preparation of the C1-C13 subunit 3 and the C14-C23 subunit 4. The construction of the novel 24-membered macrocycle was achieved by the application of a Stille coupling between 3 and 4, followed by macrolactamization.     

Synthesis and Assignment of the Absolute Configuration of Indenotryptoline Bisindole Alkaloid BE-54017

Synthesis of the indenotryptoline bisindole alkaloid, BE-54017, was accomplished using osmium-promoted cis-dihydroxylation of maleimide as a key step. After optical resolution, the absolute configuration of this molecule was determined by comparing its optical rotation and HPLC profile to those obtained for BE-54017 derived from enantiopure cladoniamide A, whose stereochemistry has been reported previously. BE-54017 with the correct absolute stereochemistry induced apoptosis of epidermal growth factor (EGF)-stimulated EGF receptor overexpressing A431 cells and inhibited vacuolar-type H(+)-ATPase (V-ATPase).     

Terahertz tomography of a photo-induced carrier based on pump-probe spectroscopy using counterpropagation geometry

A novel technique for the terahertz (THz) tomography of a photo-induced carrier that is based on optical-pump THz-probe time-resolved reflection spectroscopy using counterpropagation geometry of the pump and probe pulses has been proposed. Transient reflection due to the photo-induced carrier provides information about the physical properties and spatial distribution separately. We have experimentally demonstrated this method using a silicon wafer. The obtained complex reflection can be reproduced by the exact solution of Maxwell's equations, assuming an exponential distribution of the photo-induced carrier density.     

Study on the ferromagnetic state in iron mixed-valence complexes, A[FeIIFeIII(dto)3] (A = (n-CnH2n + 1)4N; dto = C2S2O2) by means of Mössbauer spectroscopy

We have investigated the ferromagnetic states for (n-C_nH_2n?+?1)₄N[Fe^IIFe^III(dto)₃] (n = 3–6; dto = C₂O₂S₂) by means of ⁵⁷Fe Mössbauer spectroscopy. The major component of the spin configuration in the ferromagnetic states for n = 3 and 4 is the low-temperature phase (LTP) with the Fe^III (S = 5/2) and Fe^II (S = 0) states. The high-temperature phase (HTP) of n = 4 remains by more than 20%, which is consistent with two ferromagnetic transitions (T_C = 7 & 13 K). Moreover, it was revealed that the Mössbauer spectra in the ferromagnetic states for n = 5 and 6 correspond to the HTP consisting of the Fe^II (S = 2) and Fe^III (S = 1/2) states.