Performance test of passive radon–thoron discriminative detectors on environmental parameters

This paper describes how humidity, wind and ambient aerosols in air influence the detection responses of passive detectors. Two types of alpha track detectors based on a passive radon (²²²Rn)–thoron (²²⁰Rn) discriminative measurement technique were used: the Raduet and Radopot detectors that were developed and calibrated by the National Institute of Radiological Sciences, Japan. The initial experiment showed that the infiltration rate of ²²⁰Rn onto sponges with a high air exchange rate for the Raduet detectors was one third lower than that onto filters for the Radopot detectors. Little distinct dependence on humidity was observed for the ²²²Rn detection responses of both detectors. For ²²⁰Rn, the detection responses of both detectors for the high air exchange rate seemed to decrease slightly at high humidity conditions. The ²²⁰Rn detection responses of the Radopot detectors had little influence from wind speed. The ²²⁰Rn detection responses of the Raduet detectors for the high air exchange rate seemed to decrease at low wind speeds. Furthermore, there was little difference between the detection responses in the presence and absence of ambient aerosol particles because the ambient aerosols were filtered out during their passive diffusion through the sponges and filters for the Raduet and Radopot detectors, respectively.     

A touch-and-go lipid wrapping technique in microfluidic channels for rapid fabrication of multifunctional envelope-type gene delivery nanodevices

Multifunctional envelope-type gene delivery nanodevices (MENDs) are promising non-viral vectors for gene therapy. Though MENDs remain strong in prolonged exposure to blood circulation, have low immunogenic response, and are suitable for gene targeting, their fabrication requires labor-intensive processes. In this work, a novel approach has been developed for rapid fabrication of MENDs by a touch-and-go lipid wrapping technique in a polydimethylsiloxane (PDMS)/glass microfluidic device. The MEND was fabricated on a glass substrate by introduction of a condensed plasmid DNA core into microfluidic channels that have multiple lipid bilayer films. The principle of the MEND fabrication in the microfluidic channels is based on electrostatic interaction between the condensed plasmid DNA cores and the coated lipid bilayer films. The constructed MEND was collected off-chip and characterized by dynamic light scattering. The MEND was constructed within 5 min with a narrow size distribution centered around 200 nm diameter particles. The size of the MEND showed strong dependence on flow velocity of the condensed plasmid DNA core in the microfluidic channels, and thus, could be controlled to provide the optimal size for medical applications. This approach was also proved possible for fabrication of a MEND in multiple channels at the same time. This on-chip fabrication of the MEND was very simple, rapid, convenient, and cost-effective compared with conventional methods. Our results strongly indicated that MENDs fabricated with our microfluidic device have a good potential for medical use. Moreover, MENDs fabricated by this microfluidic device have a great potential for clinical use because the devices are autoclavable and all the fabrication steps can be completed inside closed microfluidic channels without any external contamination.     

Rhodium-catalyzed asymmetric addition of arylboroxines to β-alkoxyacrylate esters

Asymmetric addition of arylboroxines to β-alkoxyacrylate esters proceeded in the presence of a rhodium complex coordinated with a chiral diene ligand to give high yields of β-alkoxy-β-arylcarboxylic acid esters with very high enantioselectivity.     

Isolation and total syntheses of two new alkaloids, dubiusamines-A, and -B, from Pandanus dubius

Chemical investigation of the crude base of Pandanus dubius led to the isolation of two new alkaloids, dubiusamine-A (1) and dubiusamine-B (2). The structures of the two alkaloids including their absolute configuration were unambiguously confirmed by 1D and 2D NMR analysis and asymmetric total synthesis.     

New pyrrolidine alkaloids from the roots of Pandanus amaryllifolius

Four new alkaloids, pandamarilactonines-E, -F, and -F-N-oxide consisting of a pyrrolidine moiety and two α-methyl-γ-lactone residues, and pandamarilactonine-G, possessing a pyrrolidinone function, were isolated from the roots of Pandanus amaryllifolius. Their structures were determined based on spectroscopic analyses and chemical syntheses.     

Effect of external fields applied during hot-water treatment on the aspect ratio of nanocrystallites formed on SiO<Subscript>2</Subscript>·TiO<Subscript>2</Subscript> coatings derived from sol–gel techniques

SiO₂·TiO₂ coatings were prepared by a sol–gel route. The effect of the external fields including mechanical vibration and electric charge applied during hot-water treatment on titania precipitation at the surface of the coatings was investigated. The shape of the resulting precipitates tended to elongate by applying vibration in a parallel or perpendicular direction, or by applying an electric charge. The organization of titania nanocrystallites possibly occurs because of the concentration gradient of dissolved titania species generated by the external fields during the hot-water treatment. A maximum aspect ratio of 38.1 was achieved for the precipitate prepared by hot-water treatment performed under parallel vibration for 5 h. The shape of the resulting precipitates was also influenced by the content of TiO₂ in the SiO₂·TiO₂ coating, with a smaller proportion of TiO₂ increasing the aspect ratio of the resulting precipitate.     

Two new alkaloids from Crinum asiaticum var. sinicum

Two new alkaloids (1, 2) were isolated from the whole plants of Crinum asiaticum var. sinicum together with seven known alkaloids. The structures of the new alkaloids were elucidated by spectroscopic analyses and chemical conversions from known alkaloids. New alkaloid 1 was isolated for the first time as a natural product, although it has been prepared as a synthetic product.     

Formation of Anatase Nanocrystals-Precipitated Silica Coatings on Plastic Substrates by the Sol-Gel Process with Hot Water Treatment

Anatase nanocrystals-precipitated silica coatings were formed on plastic substrates such as poly(ethylene terephtalate) (PET), acrylic resin (AC) and polycarbonate (PC) from silica-titania gel coatings with and without addition of poly(ethylene glycol) (PEG) by hot water treatment. The maximum thickness of the coatings which can be formed without cracking or peeling-off was 100 to 200 nm for PET and PC substrates, whereas it was less than 50 nm for AC substrates. After a hot water treatment at 90°C for 120 min, the size of the anatase nanocrystals increased to be 30 and 50 nm for the coatings obtained with and without PEG, respectively. Anatase nanocrystals were formed throughout the whole of the coatings obtained with PEG and were formed only on the surface of the coatings obtained without PEG. Both coatings obtained with and without PEG were highly transparent. The plastic substrates with coatings obtained without PEG showed good weathering resistance owing to the protective effects of the residual silica under-layer. The coatings obtained with PEG showed higher photocatalytic activities than those obtained without PEG due to smaller size and higher dispersion of anatase nanocrystals in the coatings.     

Applicability of silanol to sensitizing dye for dye-sensitized solar cell

Applicability of silanols to dye-sensitized solar cells was investigated for the first time with bis(4-azobenzene)silanediol as a model compound. The silanol dye showed high adsorption ability on the surface of TiO₂ electrode and effective electron transfer from the light-excited dye to the electrode was confirmed, exhibiting the effectiveness of the silanol dyes for the sensitizers.