Estimation of secondary electron effect in the J-PARC rapid cycling synchrotron after first study

The J-PARC 3 GeV rapid-cycling synchrotron (RCS) is required to provide 1 MW pulsed protons to the spallation neutron target and the 50 GeV main ring. Since the RCS finally accelerates very high intensity beam such as 8.3 × 10¹³ ppp, the secondary electron cloud may affect the accelerator performance. We measured the secondary electron emission from the TiN coating surface and the ferrite sample. By using these measurement results, we estimated the effect of the electron cloud made by the emitted secondary electron at present beam parameters.     

Radiation from a Line Source Placed in Two-dimensional Photonic Crystals

A novel formulation of radiation from a localized line source placed in two-dimensional photonic crystals consisting of layered periodic arrays of parallel circular cylinders is presented. The method employs the spectral domain approach. The spectral response of the photonic crystals to the line source excitation is calculated using the lattice sums, the T-matrix of a circular cylinder, and the generalized reflection and transmission matrices of the layered system. The far-zone radiated field is obtained using the conventional asymptotic method to the spectral response. The radiation patterns of the localized line source sandwiched by two photonic crystals are numerically studied.     

Theory of two-step processes for nucleon-nucleus scattering

The basis of the conventional formula for the two-step-process approximation (TSPA) is discussed in terms of three-body collisions for the inelastic scattering of a nucleon by a heavy nucleus and the accompanying charge-exchange reactions. A criterion is obtained for determining the effective interaction of the first term of the TSPA and the reaction processes that should be explicitly taken into account in the second term. The applicability of the TSPA for estimating the effects of intermediate states, in which a pair of constituent particles is in a resonant state or in a virtual state, is also discussed.     

Mechanical and other characteristics of cellulose ester bonded with modified cardanol from cashew nut shells and additional aliphatic and aromatic components

Novel cellulose-based bioplastics, mainly using inedible plant resources, were produced by bonding cellulose diacetate (CDA), a modified cardanol, and additional aliphatic and aromatic components. Cardanol is a phenol derivative with a linear unsaturated hydrocarbon side chain (carbon number: 15), derived from cashew nut shells. Esterification of the modified cardanol (3-pentadecylphenoxy acetic acid: PAA) and CDA resulted in a thermoplastic PAA-bonded CDA with high tenacity (long elongation while keeping maximum bending strength), heat resistance, and water resistance. These properties were better than those of a conventional CDA composite consisting of CDA and a conventional plasticizer. By comparing the PAA-bonded CDA with a CDA bonded with stearic acid (SA), which has a linear structure similar to that of PAA’s side chain but has no phenyl part, it was suggested that the linear side chain in PAA has a main role in these prominent properties of the PAA-bonded CDA, while the phenyl part in PAA has pronounced effects on its maximum bending strength and water resistance. Additional bonding of linear alkanoic acids, especially SA as aliphatic components improved the PAA-bonded CDA’s impact strength, and additional bonding of benzoic acid (BA) as an aromatic component further increased its maximum bending strength and elastic modulus. These components improved the thermoplasticity and water resistance of the PAA-bonded CDA while maintaining its high heat resistance relatively well.     

Presence of rhodopsin and porphyropsin in the eyes of 164 fishes, representing marine, diadromous, coastal and freshwater species--a qualitative and comparative study

There are two types of visual pigments in fish eyes; most marine fishes have rhodopsin, while most freshwater fishes have porphyropsin. The biochemical basis for this dichotomy is the nature of the chromophores, retinal (A1) and 3-dehydroretinal (A2), each of which is bound by an opsin. In order to study the regional distribution of these visual pigments, we performed a new survey of the visual pigment chromophores in the eyes of many species of fish. Fish eyes from 164 species were used to examine their chromophores by high-performance liquid chromatography--44 species of freshwater fish, 20 of peripheral freshwater fish (coastal species), 10 of diadromous fish and 90 of seawater fish (marine species) were studied. The eyes of freshwater fish, limb freshwater fish and diadromous fish had both A1 and A2 chromophores, whereas those of marine fish possessed only A1 chromophores. Our results are similar to those of previous studies; however, we made a new finding that fish which live in freshwater possessed A1 if living near the sea and A2 if living far from the sea if they possessed only one type of chromophore.     

Microstructures of high-growth-rate (up to 8.3 nm/s) microcrystalline silicon photovoltaic layers and their influence on the photovoltaic performance of thin-film solar cells

Microstructures of microcrystalline silicon (μc-Si) deposited at a high-growth-rate have been investigated in order to apply to the photovoltaic i-layer. μc-Si films were prepared by very-high-frequency (100 MHz) plasma-enhanced chemical vapor deposition at 180 °C. High growth rates of 3.3–8.3 nm/s have been achieved utilizing high deposition pressures up to 24 Torr and large input powers. Applying μc-Si to n–i–p junction solar cells, as the optimum result in this experimental series, a conversion efficiency of 6.30% (J_SC: 22.1 mA/cm², V_OC: 0.470 V, and FF: 60.7%) has been achieved employing the i-layer deposited at 8.1 nm/s. Raman scattering and X-ray diffraction measurements revealed the crystalline volume fraction of around 50% with the (2 2 0) crystallographic preferential orientation, respectively. The cross-sectional transmission electron microscope image shows densely columnar structure grown directly on the underlying n-layer. These structural features are basically in good agreement those of low-growth-rate μc-Si used for a high efficiency solar cell as previously reported, implying advantages of the use of high pressures with regard to providing the photovoltaic i-layers. Finally, the implication is discussed from the photovoltaic performance as a function of the crystalline volume fraction of i-layer, and current problems in improving the photovoltaic performance are extracted.     

Time-resolved EPR spectra of a photoexcited phenanthrene-linked copper(II)-free-base porphyrin dimer: An intermediate-coupling case in a triplet-doublet spin system

Time-resolved electron paramagnetic resonance (TREPR) spectra are presented for a phenanthrene-linked copper(II)-free-base porphyrin dimer. In the lowest electronic excited state, the free-base half is in the (π, π*) triplet state and the copper-porphyrin half is in the doublet ground state due to the copper(II) spin. Because of the interaction between the triplet and doublet spins, the excited state of the dimer is described as a coupled triplet-doublet pair state. By choosing the excitation wavelength, this coupled state is produced via either the intersystem crossing within the free base or the energy transfer from the excited state of the copper porphyrin. The observed TREPR spectra show very large spectral widths compared to that of the triplet state in the free-base monomer. In addition, there is a prominent absorptive band in the center of the spectra regardless of the generation pathway. These features can be interpreted as characteristic properties in an intermediate-coupling case, where the degree of the triplet and doublet mixing largely depends on the molecular orientation relative to the magnetic field.     

Active nuclear shuffling system using a swollen conidium of Trichoderma reesei

Cellulase hyperproducers of Trichoderma reesei can be constructed using autopolyploidization and haploidization techniques. To increase the efficiency of this method, the active nuclear shuffling system in a swollen conidium was effective. A dried mature green conidium of a model strain, T. reesei QM6a (IFO 31326), was swollen to make room for a larger autopolyploid nucleus. After colchicine treatment, a larger autopolyploid nucleus was produced in such a swollen conidium. Benomyl treatment of swollen conidia generated multiple smaller nuclei from one larger autopolyploid nucleus. Those smaller nuclei were transported through conidia to mycelia after germination. This system could contribute to increasing the efficiency of genetic shuffling.     

Polykaryon formation using a swollen conidium of Trichoderma reesei

The cellulolytic fungus, Trichoderma has oval and mononucleate conidia. When these conidia are incubated in a liquid medium, they begin to swell and their shape becomes spherical followed by an increase in inner space. In such swollen conidia, it is possible to produce a larger autopolyploid nucleus using a mitotic arrester compared with the case of the original conidia. In this study, polykaryon formation was attempted using these swollen conidia. Dried mature green conidia of Trichoderma reesei QM6a (IFO 31326) were incubated in Mandel's medium in order to swell. The swollen conidia were treated with a mitotic arrester, colchicine, for autopolyploidization. After autopolyploidization, polykary on formation was carried out using the swollen conidia. After the treatment, multiple smaller nuclei whose diameter was almost the same as that of the original strain were generated from an autopolyploid nucleus in a swollen conidium. A cellulase hyperproducer without decrease in growth rate could be selected using such swollen conidia.