Unambiguous detection of target DNAs by excimer-monomer switching molecular beacons

A new class of molecular beacons were developed in which pyrene fluorophores were connected both at 3' and 5' ends of a single-stranded oligonucleotide. The two pyrene-based fluorophores were synthesized from the same starting material, so that the preparation of the beacons was simplified. The detection strategy of the beacons for target DNAs is based on "excimer-monomer emission switching" of the pyrene fluorophores: excimer emission of the pyrene moieties changed to monomer one when the beacons hybridized with the targets. This type of two-state mode of fluorescence allows unambiguous detection of the target DNAs because strict 1:1 correlation between the nonhybridized and the hybridized beacons can be monitored by the presence of isoemissive points of the fluorescence changes. The beacons can detect target 19-mer DNAs and can discriminate the targets from their single-nucleotide mismatches at 1 nM concentration. Advantages of the excimer-monomer switching molecular beacons were discussed in comparison with conventional ones.     

Iridium complex-catalyzed highly enantio- and diastereoselective [2+2+2] cycloaddition for the synthesis of axially chiral teraryl compounds

An asymmetric [2+2+2] cycloaddition of an alpha,omega-diyne, possessing ortho-substituted aryl groups on its terminus, and a monoalkyne with oxygen functionalities gave various axially chiral teraryl compounds. The coupling proceeded with extremely high enantio- (>99.5% ee) and diastereoselectivities (dl/meso = >95/5) when catalyzed by an iridium-chiral phosphine complex. As the products were readily transformed into diol compounds by deprotection without racemization, the present procedure provides access to a new chiral pool of diol compounds with C2 symmetry.     

Non-destructive analysis of the two subspecies of African elephants, mammoth, hippopotamus, and sperm whale ivories by visible and short-wave near infrared spectroscopy and chemometrics

Visible (VIS) and short-wave near infrared (SW-NIR) spectroscopy was used for non-destructive analysis of ivories. VIS-SW-NIR (500-1000 nm) spectra were measured in situ for five kinds of ivories, that is two subspecies of African elephants, mammoth, hippopotamus, and sperm whale. Chemometrics analyses were carried out for the spectral data from 500 to 1000 nm region. The five kinds of ivories were clearly discriminated from each other on the scores plot of two principal components (PCs) obtained by principal component analysis (PCA). It was noteworthy that the ivories of the two subspecies of African elephants were discriminated by the scores of PC 1. The loadings plot for PC 1 showed that the discrimination relies on the intensity changes in bands due to collagenous proteins and water interacting with proteins. It was found that the scores plot of PC 2 is useful to distinguish between the ivories of the two subspecies of African elephants and the other ivories. We also developed a calibration model that predicted the specific gravity of five kinds of ivories from their VIS-SW-NIR spectral data using partial least squares (PLS)-1 regression. The correlation coefficient and root mean square error of cross validation (RMSECV) of this model were 0.960 and 0.037, respectively.     

Generation of 360-nm ultraviolet light in first-order periodically poled bulk MgO:LiNbO3

Ultraviolet second-harmonic generation in first-order periodically poled MgO:LiNbO3 is presented. Using a high-voltage multipulse application method, we fabricated a first-order nonlinear grating with a period of 1.8 microm and depth of approximately 150 microm over 10-mm interaction length in a 1-mm-thick MgO:LiNbO3 substrate. In a single-pass configuration, continuous-wave 30-mW UV light at 362.5 nm was generated for a fundamental power of 522 mW, corresponding to a normalized conversion efficiency of 11%/W.     

Generation of harmonics of femtosecond radiation from the surface of aluminum targets

The results of a study of the generation of harmonics from a laser plasma resulting from the interaction of radiation of femtosecond duration (λ=1.06 μm, t=475 fs, and I～2×10¹⁷ W cm^?2) with aluminum targets are presented. The observed frequency shift of harmonics to the short-wavelength region (1.6 and 5.1 nm for the second and fifth harmonics, respectively) is determined by a collisionless absorption resulting from an anomalous skin effect. The efficiencies of conversion into the second and fifth harmonics in an s-polarized pumping field were lower than the conversion efficiencies in a p-polarized pumping field by a factor of eight and a factor of two, respectively (for intensities I<10¹⁷ W cm^?2). With a further increase in the pumping intensity, these values decreased to 0.8 and 0.5, respectively. The mechanisms of such behavior of the conversion process are considered.     

The activation of molecular oxygen by horseradish peroxidase with sodium sulfite

Horseradish peroxidase (HRP) utilizes molecular oxygen (O2) with sodium sulfite (Na2SO3) to oxidize thioanisole and styrene at the exterior of the heme pocket.     

Reduction of ion thermal diffusivity associated with the transition of the radial electric field in neutral-beam-heated plasmas in the large helical device

Recent large helical device experiments revealed that the transition from ion root to electron root occurred for the first time in neutral-beam-heated discharges, where no nonthermal electrons exist. The measured values of the radial electric field were found to be in qualitative agreement with those estimated by neoclassical theory. A clear reduction of ion thermal diffusivity was observed after the mode transition from ion root to electron root as predicted by neoclassical theory when the neoclassical ion loss is more dominant than the anomalous ion loss.     

Observation of the "self-healing" of an error field island in the large helical device

It was observed that the vacuum magnetic island produced by an external error magnetic field in the large helical device shrank in the presence of plasma. This was evidenced by the disappearance of flat regions in the electron temperature profile obtained by Thomson scattering. This island behavior depended on the magnetic configuration in which the plasmas were produced.     

Synthesis of a novel tripodand having 3-hydroxy-2-naphthoeic amide groups and its anion recognition ability

A novel tripodand having 3-hydroxy-2-naphthoeic amide groups was prepared by the reaction of 1,3,5-tris(aminomethyl)-2,4,6-trimethylbenzene with 3-allyloxy-2-naphthoeic acid chloride followed by thermal Claisen rearrangement. This tripodand can exhibit the anion binding ability in chloroform solution. In particular, it can bind with acetate, dihydrogen phosphate, and fluoride ions to form 1:1 complexes.