Distinguishing nanomaterial particles from background airborne particulate matter for quantitative exposure assessment

As the production of engineered nanomaterials quantitatively expands, the chance that workers involved in the manufacturing process will be exposed to nanoparticles also increases. A risk management system is needed for workplaces in the nanomaterial industry based on the precautionary principle. One of the problems in the risk management system is difficulty of exposure assessment. In this article, examples of exposure assessment in nanomaterial industries are reviewed with a focus on distinguishing engineered nanomaterial particles from background nanoparticles in workplace atmosphere. An approach by JNIOSH (Japan National Institute of Occupational Safety and Health) to quantitatively measure exposure to carbonaceous nanomaterials is also introduced. In addition to real-time measurements and qualitative analysis by electron microscopy, quantitative chemical analysis is necessary for quantitatively assessing exposure to nanomaterials. Chemical analysis is suitable for quantitative exposure measurement especially at facilities with high levels of background NPs.     

Kinetic resolution of primary amines via enantioselective N-acylation with acyl chlorides in the presence of supramolecular cyclodextrin nanocapsules

The non-enzymatic kinetic resolution of primary amines via enantioselective N-acylation with acyl chlorides was accomplished for the first time by using the selective sequestration of one enantiomer within a supramolecular cyclodextrin (CD) nanocapsule in nonpolar solvents. In addition, the first example of a crystalline structure for an inclusion complex between an acyl chloride and a CD derivative is reported.     

Surface polyion complex gel with poly(vinylphosphonic acid) and poly(N‐vinylamide)s

The surface polyion complex gel (sPIC gel), which possesses chemically bonded nonionic gel moiety, was designed using N‐vinylacetamide (NVA), N‐vinylforamide (NVF), and vinyl phosphonic acid (VPA). Taking advantage of the property of NVF as vinylamine (VAm) precursor, the cationic moiety was introduced only onto the surface of poly(NVA‐co‐NVF), producing surface hydrolyzed poly(NVA‐co‐NVF‐co‐VAm), and the successive polymerization of VPA inside the gel successfully produced sPIC gel. The swelling ratio of the sPIC gel was investigated under various pH conditions, and compared with that of the fully polyion complex gel (PIC gel), using totally hydrolyzed poly(NVA‐co‐VAm). The swelling ratio of sPIC gel ranged between 14 and 25, while that of the PIC gel ranged between 2 and 5. The anionic compound, AR, showed a sustained release from sPIC gel at pH 2, due to the electrostatic interactions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 562–566     

Enantioselective construction of all-carbon quaternary spirocenters through a Pd-catalyzed asymmetric intramolecular ipso-Friedel–Crafts allylic alkylation of phenols

A novel catalytic asymmetric synthetic method for making spirocyclohexadienones with an all-carbon quaternary spirocenter was developed based on the Pd-catalyzed intramolecular ipso-Friedel–Crafts allylic alkylation of phenols. When 5 mol % of the Pd catalyst and 12 mol % of (?)-9-NapBN (?)-3e were used, the spirocyclic adduct was obtained with up to 93% ee, albeit with low chemical yield. On the other hand, when using 6 mol% of the Trost ligand (R,R)-3k, the spirocyclic adducts were obtained in good yields with up to 89% ee (diastereoselectivity = 9.2:1).     

Imidazolium-based chiral ionic liquids: synthesis and application

Synthesis of chiral ionic liquids containing an imidazole nucleus and chiral centers on N-substituents is reported. [(2S,3S)-2,3-Dihydroxybutane-1,4-bis(3-butylimidazolium)]-[bis(trifluoromethanesulfonyl)amide]₂ and [(4S,5S)-2-phenyl-1,3-dioxolane-4,5-bis(1-methylimidazolium)]-[bis(trifluoromethanesulfonyl)amide]₂ induced enantioselectivity in the Michael addition of malonic esters to chalcones.     

Direct observation of rectified motion of vortices by Lorentz microscopy

We have investigated the vortex dynamics for the ‘ratchet’ operation in a niobium superconductor via a direct imaging of Lorentz microscopy. We directly observe one-directional selective motion of field-gradient-driven vortices along fabricated channels. This results from the rectification of vortices in a spatially asymmetric potential under the oscillating magnetic field in a temporally symmetric manner. Based on the observation of the individual motion of vortices, we clarify the elementary process involved in this rectification.     

NOVEL TERAHERTZ PHOTOCONDUCTIVE ANTENNAS

The photoconductive (PC) antenna is a key device for the recent terahertz (THz) photonics based on laser-pumped generation and detection of THz radiation. In this paper we report on two new types of PC antennas: the Schottky PC antenna and the multi-contacts PC antenna. The former one is able to detect THz radiation intensity without the time-delay scan and useful for applications where spectroscopic information is not important, such as the THz intensity imaging. The latter one is useful for the polarization sensitive THz spectroscopy, such as the THz ellipsometry. The characteristic features of these new types of PC antennas are studied by using a THz time-domain spectroscopy system.     

Permanent data recording in transparent materials by using a nanojoule-class pulse laser

We investigated data recording for permanent data storage using an ultrafast pulse laser with nanojoule-class pulse energy and megahertz-class repetition rate in transparent materials, and driveless reading based on a simple imaging system. A transparent ceramics called Lumicera®, manufactured by Murata Mfg. Co., Ltd., was used as the recording medium. Lumicera® has a lower modification threshold and a higher recording sensitivity than those of silica glass, namely, the medium previously studied. Structural modification in Lumicera® occurs by light exposure for 10 μs, suggesting that Lumicera® has potential for a recording speed of over 100 kbps. Data recorded in Lumicera® resists heating for 2 h at 1000 °C and is expected to have a lifetime of over 300 million years. Moreover, the data recorded in Lumicera® was successfully read with a reading system based on a smart phone.