Total synthesis of (-)-polycavernoside A: Suzuki-Miyaura coupling approach

A total synthesis of (-)-polycavernoside A, a marine lethal toxin isolated from the edible alga Gracilaria edulis , has been achieved via a convergent approach. The synthesis is highlighted by catalytic asymmetric syntheses of the two key fragments and their union through Suzuki-Miyaura coupling and Keck macrolactonization.     

Reduction of thermal fluctuations in a cryogenic laser interferometric gravitational wave detector

The thermal fluctuation of mirror surfaces is the fundamental limitation for interferometric gravitational wave (GW) detectors. Here, we experimentally demonstrate for the first time a reduction in a mirror's thermal fluctuation in a GW detector with sapphire mirrors from the Cryogenic Laser Interferometer Observatory at 17 and 18 K. The detector sensitivity, which was limited by the mirror's thermal fluctuation at room temperature, was improved in the frequency range of 90 to 240 Hz by cooling the mirrors. The improved sensitivity reached a maximum of 2.2×10(-19) m/√Hz at 165 Hz.     

Highly enantioselective synthesis of silahelicenes using Ir-catalyzed [2+2+2] cycloaddition

Silahelicenes, which contain two silole moieties in a helically chiral structure, were synthesized by a chiral Ir-catalyzed intermolecular [2+2+2] cycloaddition of tetraynes with diynes along with a Ni-mediated intramolecular [2+2+2] cycloaddition. The photophysical properties of the obtained highly enantiomerically enriched silahelicenes (up to 93% ee) were also measured.     

Dehydration from conserved stem regions is fundamental for ligand-dependent conformational transition of the adenine-specific riboswitch

Conformational dynamics and observed equilibrium constants for ligand binding of the adenine-specific riboswitch (add-A riboswitch) in the absence of Mg(2+) and presence of various concentrations of poly-ethylene glycol having an average molecular weight of 200 indicated that 54.2 water molecules were released from P2 and P3 stem regions of the add-A riboswitch during conformational transition upon the binding of 2-aminopurine, an analog of the natural ligand adenine.     

Copper-catalyzed coupling reaction of unactivated secondary alkyl iodides with alkyl Grignard reagents in the presence of 1,3-butadiene as an effective additive

Cu-catalyzed cross-coupling of unactivated secondary alkyl iodides with alkyl Grignard reagents in the presence of 1,3-butadiene as a ligand precursor was developed. The use of 1,3-butadiene resulted in improved yields of alkyl-alkyl products with improved selectivities.     

Direct drug metabolism monitoring in a live single hepatic cell by video mass spectrometry

The metabolism of anti-breast cancer drug, tamoxifen, in a single human hepatocellular carcinoma cell, HepG2, was directly monitored by a video-mass spectroscope. The cytoplasm, a vacuole or nucleus of the cell was directly sucked by a nano-spray tip under a video-microscope, and then was introduced into a mass spectrometer. Unchanged drug molecules were found in cytoplasm and a vacuole, but the metabolites were only found in the cytoplasm. This direct detection of drug metabolites in a live single cell is useful for speedy drug metabolism monitoring.     

Rapid discharge-pumped wide aperture X-ray preionized KrF laser

A wide aperture X-ray preionized discharge-pumped KrF excimer laser has been constructed. A flat plate pulse-forming line (36 nF, 340 kV) charges a peaking capacitor (6 nF) through a rail-gap to facilitate a rapid discharge in the laser head. Collimated X-ray preionization is employed to obtain a wide and uniform discharge. The laser is intended to be used as a short pulse amplifier and results are presented when characterized as an oscillator. The active cross-section of the laser beam is 10×8 cm² with 50 cm effective electrode length. The laser pulse energy exceeds 4.7 J in a 28 ns pulse (FWHM).     

The Simulated Detection of the Objects at Variant Depth Using Depth-Adaptive Voxel Size Scheme in Diffuse Reflective Optical Tomography (DROT)

We study diffuse reflective optical tomography (DROT), aiming at the real-time imaging of the redox state change of the human cerebral cortex with the brain activity. In the uniform voxel size and simple regularization scheme we studied so far, the spatial resolution in the shallow region is unnecessarily good, whereas the noise and the sensitivity in the shallow region are too large to recover the signal in the depth. In this paper, we propose depth-adaptive voxel size reconstruction. By assigning wider lateral voxel size in the deep range, the relative sensitivity in the deep range is increased so that the signal in the deep range would be less masked by the presence of the unwanted target in the shallow range. We demonstrate that we can detect the deep objects without being masked by the shallow object using the proposed method.