Molecular beam resonant two-photon ionization study of caffeine and its hydrated clusters

We investigated electronically excited states of caffeine and its 1:1 complex with water by using resonant two-photon ionization (R2PI) and UV-UV hole-burning techniques. Strong vibronic coupling between a pair of close-lying pi-pi* and n-pi* transitions is proposed to be responsible for the broad spectral feature observed. By comparing the experimental results with those of theoretical calculations, both the O-bonded and N-bonded forms were suggested to be initially produced for the 1:1 complex. The electronic transitions of the O-bonded complex were blueshifted in the R2PI spectrum. For the N-bonded complex, the excited state undergoes an ultrafast decay process, followed by dissociation on a repulsive potential energy surface, which gives rise to a characteristically anomalous cluster distribution in nanosecond experiments.     

Synthesis of perpendicular nanorod arrays with hierarchical architecture and water slipping superhydrophobic properties

The utilization of vertically aligned smooth gold nanorod arrays with and without nanoporous tip architectures as superhydrophobic surfaces is described. Nanoporous architecture was produced on the tips of nanorods by selectively dissolving less noble components from the alloy nanorods. The resulting nanoscopic dual-size roughness features enhanced the surface dewettability after surface modification with low-surface-energy materials such as long-chain normal alkanethiols and fluorinated organic compounds. The surface cleaning properties were also tested with a rolling water droplet.     

Expression of hepatitis C virus nonstructural 4B in transgenic mice

Hepatitis C virus (HCV) is a pathogen that is of great medical significance in chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma worldwide. Although the HCV proteins have been intensively investigated over the past decade, the biochemical functions of the NS4B protein are still largely unknown. To investigate NS4B as a potential causative agent of liver disease, transgenic mice expressing the NS4B protein in liver tissue were produced. The transgenic animals were phenotypically similar to their normal littermates for up to 18 months of age. Our results suggest that the HCV NS4B protein is not directly cytopathic or oncogenic in our transgenic mice model.     

Magnesium ion selective two-photon fluorescent probe based on a benzo[h]chromene derivative for in vivo imaging

A novel, two-photon probe for the detection of free Mg2+ ions in living cells and live tissues has been developed. The probe can be excited by 880 nm laser photons, emits strong two-photon excited fluorescence in response to Mg2+ ions, can be easily loaded into the cell and tissue, shows high photostability, and can measure the Mg2+ ion concentration without interference by Ca2+ ions in living cells. The intracellular dissociation constant (Kdi) for Mg2+ determined by the two-photon process is 2.5 mM, which is suitable for dynamic Mg2+ concentration measurement. In addition, the probe is capable of imaging endogenous stores of free Mg2+ at a few hundred micrometers depth in live tissues using two-photon microscopy (TPM).     

Dependence of the closed-shell repulsive interaction on the overlap of the electron densities

The relationship between the closed-shell repulsive interactions and overlap of the electron densities is investigated. It is found that the repulsive interactions vary in almost direct proportion to the absolute size of the density overlaps.     

Tuning the band-gap energy of TiO2-xCx nanoparticle for high performance photo-catalyst

We describe a method tuning the band-gap energy (E_g) of visible light sensitive TiO_2-xC_x nanoparticle. E_g tends to become smaller with the increase in the amount of carbon dopant in TiO_2-xC_x nanoparticle due to the increase in excess electrons. Photo-catalytic oxidative activity, however, did not depend on only the value of E_g, but also the energy level of valence band. TiO_1.96C_0.04 nanoparticle having E_g of 2.6 eV showed outstanding performance in oxidative decomposition of phenol under the irradiation of visible light.     

Microchip electrophoretic separation for the fast diagnosis of Anaplasma phagocytophilum infection in cattle

We report a diagnostic method for Anaplasma phagocytophilum (A. phagocytophilum) infection in cattle using a nested PCR and microchip electrophoresis (ME). A. phagocytophilum causes human granulocytic anaplasmosis and granulocytic ehrlichiosis, which are emerging tick‐borne zoonotic diseases. Nested PCR was used to amplify genomic DNA samples extracted from cattle blood. The amplified PCR products were analyzed under a sieving gel matrix of 0.7% poly(ethyleneoxide) (M_r=8 000 000) in a conventional glass microchip. In the ME assay, A. phagocytophilum was analyzed within 35 s with a relative standard deviation of 1.30% (n=5) using a programmed field strength gradient (PFSG) as follows: 615.3 V/cm for 0–24 s, 66.7 V/cm for 24–34 s, 615.3 V/cm for 34–100 s. The ME‐PFSG assay was clinically validated by comparing the 16S rRNA gene levels obtained by this method with those measured using conventional slab gel electrophoresis performed with ten cattle blood samples suspected of A. phagocytophilum infection. In contrast to slab gel electrophoresis, the proposed ME‐PFSG methodology had increased sensitivity (200–450 pg/μL), a faster analysis time (<35 s), and required a smaller sample volume (～162 fL).