An Attempt at the Preparation of Macrocyclic Polymer

Syntheses of cyclic oligomer and polymer were attempted with magnesiacyclohexane as the initiator in HMPA. The oligomer of α-methylstyrene, initiated by magnesiacyclohexane, was treated with dimethyldichlorosilane in order to obtain a stable cyclic oligomer. The products were investigated by GPC, IR, NMR, and elemental analysis. It was found that magnesia-cyclohexane could not be activated enough by HMPA, and that the magnesium-carbon bond was not stable in HMPA, and that the chain transfer reaction might occur repeatedly during the polymerization. Consequently, the yield of cyclic oligomer was so low that cyclic compounds could not be discriminated from the linear oligomer.     

Activation cross-sections of longer lived products of proton induced nuclear reactions on cobalt up to 70 MeV

As a part of our series of studies on charged particle induced reactions on various target materials, proton induced excitation functions on natural cobalt have been determined by using the stacked-foil technique. In these measurements the radionuclides ^55,56,57,58Co, ⁵¹Cr, ^52,54,56Mn and ^56,57Ni have been identified. For the above mentioned nuclides the cross-sections were derived from the measured activities and were compared with the literature data and with the results of EMPIRE code calculations and tabulated values in the TENDL 2011 library (based on TALYS code calculations). The agreement with previous measurements and with theoretical values was acceptable.     

Ultra-narrow interval angular control signal for holographic data storage system

Optical Review - A precise and fast method for controlling the reference-beam angle of an angular-multiplexed holographic data storage system (HDSS)—to achieve larger capacity and faster...     

Super strong nuclear force caused by migrating K? mesons - Revival of the Heitler-London-Heisenberg scheme in kaonic nuclear clusters

We have studied the structure of K⁻pp comprehensively by solving this threebody system in a variational method, starting from the Ansatz that the Λ(1405) resonance (≡Λ^*) is a K⁻p bound state. The structure of K⁻pp reveals a molecular feature, namely, the K⁻ in Λ^* as an “atomic center” plays a key role in producing strong covalent bonding with the other proton. We point out that strongly bound $\bar{K}$ nuclear systems are formed by “super strong” nuclear force due to migrating real bosonic particles $\bar{K}$ a la Heitler-London-Heisenberg, whereas the normal nuclear force is caused by mediating virtual mesons. We have shown that the elementary process, p + p → K⁺ + Λ^* + p, which occurs in a short impact parameter and with a large momentum transfer, leads to unusually large self-trapping of Λ^* by the involved proton, since the Λ^*-p system exists as a compact doorway state propagating to K⁻pp.     

The ASACUSA CUSP: an antihydrogen experiment

In order to test CPT symmetry between antihydrogen and its counterpart hydrogen, the ASACUSA collaboration plans to perform high precision microwave spectroscopy of ground-state hyperfine splitting of antihydrogen atom in-flight. We have developed an apparatus (“cusp trap”) which consists of a superconducting anti-Helmholtz coil and multiple ring electrodes. For the preparation of slow antiprotons and positrons, Penning-Malmberg type traps were utilized. The spectrometer line was positioned downstream of the cusp trap. At the end of the beamline, an antihydrogen beam detector was located, which comprises an inorganic Bismuth Germanium Oxide (BGO) single-crystal scintillator housed in a vacuum duct and surrounding plastic scintillators. A significant fraction of antihydrogen atoms flowing out the cusp trap were detected.     

Development of a certified reference material for the determination of perfluorooctanoic acid

A certified reference material (CRM) for the determination of perfluorooctanoic acid (PFOA) has been issued as NMIJ CRM 4056-a by the National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ/AIST). Purity (kg kg^?1) based on a titration method was determined by subtracting the mass fractions of impurities measured using liquid chromatography/mass spectrometry (LC/MS) from those of acids expressed as PFOA measured by a neutralization potentiometric titration. To validate an obtained result, purity based on a mass balance method was determined by subtracting the mass fractions of impurities, measured using LC/MS, Karl-Fischer titration (KFT), and vacuum evaporation, from 1 kg kg^?1. Results from both titration and mass balance methods were in agreement within the accepted limits of uncertainty. The certified purity of NMIJ CRM 4056-a was determined to be 0.959 kg kg^?1, calculated as the mean of the results obtained with the two methods. The standard uncertainty of the certified purity was evaluated from purity evaluations as well as from sample homogeneity and stability obtained from LC/MS and KFT analyses. Consequently, the expanded uncertainty was estimated to be 0.005 kg kg^?1 with a coverage factor of k = 2.     

Study of the thermal degradability of poly(α-methylstyrene) with modified end groups

To induce degradabilities in polymers in response to environmental conditions, endm odification reactions of poly(α-methylstyrene) (PMS) derivatives were carried out. 2-Phenylallyl halide derivatives such as 2-phenylallyl bromide, 2-(p-tolyl)allyl bromide, and α-trifluoromethylstyrene were found to be suitable end-modification agents. For example, the ω-2-phenylallyl-PMS derivative was prepared with almost quantitative functionality by the reaction of the living PMS derivative with 2-phenylallyl bromide. In a similar way, ω-3,3-difluoro-2-phenylallyl- and ω-2-(4-toly)allyl-PMS derivatives were synthesized. Based on thermogravimetric analysis, the onset of the degradation temperature of the endmodified PMS derivatives decreased in the following order: ω-hydrogen- > ω-3,3-difluoro-2-phenylallyl- > ω-2-phenylallyl- > ω-2-(p-tolyl)allyl-PMS. Actually, the onset temperature of ω-2-(p-tolyl)allyl-PMS derivatives was 50°C lower than that of ω-H-PMS derivatives. These results indicate that the active species is produced effectively at the endunsaturated bond, which initiates depolymerization of the polymer at rather low temperatures. Therefore, it is concluded that a 2-phenylallyl substituent at the end of the PMS chain induces effective degradation through a radical mechanism.