Novel internal target for electron scattering off unstable nuclei

A novel internal target has been developed, which will make electron scattering off short-lived radioactive nuclei possible in an electron storage ring. An "ion trapping" phenomenon in the electron storage ring was successfully utilized for the first time to form the target for electron scattering. Approximately 7 x 10(6) stable 133Cs ions were trapped along the electron beam axis for 85 ms at an electron beam current of 80 mA. The collision luminosity between the stored electrons and trapped Cs ions was determined to be 2.4(8) x 10(25) cm(-2) s(-1) by measuring elastically scattered electrons.     

Basic study on the determination of total boron by conversion to tetrafluoroborate ion (BF4) followed by ion chromatography

The basic study on the determination of tetrafluoroborate ion (BF₄⁻) by ion chromatography, and total boron by conversion of boric acid to BF₄⁻ followed by ion chromatography of BF₄⁻ has been carried out. The results of thermodynamic calculations for the system of boric acid (H₃BO₃)-F⁻-H⁺ showed that the mole fraction of BF₄⁻ was higher than 99% at pH lower than 3.5 and 4.5 when the total free fluoride concentration (2[H₂F₂] + 2[HF₂⁻] + [HF] + [F⁻]) was as high as 0.1 and 1.0 M, respectively. The fraction of BF₄⁻ increased with increasing total free fluoride concentration. BF₄⁻ fraction values were higher than 99% at pH 0.75 and at total free fluoride concentration of 0.05 M or higher. BF₄⁻ was hardly formed at pH > 7 even when the total free fluoride concentration was as high as 1.0 M. According to the experimental results, the fraction of BF₄⁻ at pH 0.7-0.8 was 51.2, 95.6 and 96.7% when the total fluoride concentration (2[H₂F₂] + 2[HF₂⁻] + [HF] + [F⁻] + 3[BF₃OH⁻] + 4[BF₄⁻]) was 0.2, 1.0 and 3.3 M, respectively. The formation reaction of BF₄⁻ from boric acid reached an equilibrium state within 20 min regardless of reaction temperature, in the range of 20-50 °C, when the total boron and total fluoride concentrations were 66.7 mM and 1.0 M, respectively. Although BF₄⁻ was formed only under acidic conditions, BF₄⁻, once formed, was very stable under alkaline conditions at least for several hours. We have concluded that BF₄⁻ could be analyzed by ion chromatography using sodium hydroxide solution as an eluent because BF₄⁻ was stable under chromatographic conditions. BF₄⁻ solution prepared from boric acid could be used as a standard solution in the ion chromatographic analysis of BF₄⁻ instead of the sodium tetrafluoroborate (NaBF₄) reagent available commercially, if a discrepancy of about 4-5% was allowed.     

Dual Nickel(II)/Mechanoredox Catalysis: Mechanical-Force-Driven Aryl-Amination Reactions Using Ball Milling and Piezoelectric Materials

The combination of a nickel(II) catalyst and a mechanoredox catalyst under ball-milling conditions promotes mechanical-force-driven C−N cross-coupling reactions. In this nickel(II)/mechanoredox cocatalyst system, the modulation of the oxidation state of the nickel center, induced by piezoelectricity, is used to facilitate a highly efficient aryl-amination reaction, which is characterized by a broad substrate scope, an inexpensive combination of catalysts (NiBr₂ and BaTiO₃), short reaction times, and an almost negligible quantity of solvents. Moreover, this reaction can be readily up-scaled to the multi-gram scale, and all synthetic operations can be carried out under atmospheric conditions without the need for complicated reaction setups. Furthermore, this force-induced system is suitable for excitation-energy-accepting molecules and poorly soluble polyaromatic substrates that are incompatible with solution-based nickel(II)/photoredox cocatalysts.     

Virtual‐system‐coupled adaptive umbrella sampling to compute free‐energy landscape for flexible molecular docking

A novel enhanced conformational sampling method, virtual‐system‐coupled adaptive umbrella sampling (V‐AUS), was proposed to compute 300‐K free‐energy landscape for flexible molecular docking, where a virtual degrees of freedom was introduced to control the sampling. This degree of freedom interacts with the biomolecular system. V‐AUS was applied to complex formation of two disordered amyloid‐β (Aβ_30–35) peptides in a periodic box filled by an explicit solvent. An interpeptide distance was defined as the reaction coordinate, along which sampling was enhanced. A uniform conformational distribution was obtained covering a wide interpeptide distance ranging from the bound to unbound states. The 300‐K free‐energy landscape was characterized by thermodynamically stable basins of antiparallel and parallel β‐sheet complexes and some other complex forms. Helices were frequently observed, when the two peptides contacted loosely or fluctuated freely without interpeptide contacts. We observed that V‐AUS converged to uniform distribution more effectively than conventional AUS sampling did. © 2015 Wiley Periodicals, Inc.     

High sensitivity search for nu;e's from the sun and other sources at KamLAND

Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used to search for nu;(e)'s in the energy range 8.3相似文献   

Ultrasonic wave properties in the particle compounded agarose gels

Ultrasonic wave properties (attenuation and velocity) in the particle compounded agarose gels have been experimentally studied in the range from 1 to 30 MHz. The particles used were talc, glass beads and graphite. The effects of size and volume concentration of particles were clearly observed as changes of ultrasonic wave properties. Applying the Urick's theory for viscous liquid suspensions, the specific curves of velocity in the gels were observed as a function of a beta, where a is the radius of the particles and beta is described by angular frequency omega, density rho and fluid viscosity eta. This indicates that the particle behavior in the gels seems to be similar with that in the viscous fluid. The estimated eta in the gels was higher than that of the free water, showing the high viscosity in the gels.     

Study of Charged Pion Photoproduction on Deuteron with Tagged Photons

The reactions γd→π~- pp and γd→npπ~+π~- have been studied in an energy range from 0.8 to 1.1 GeV at the tagged photon facility of Laboratory of Nuclear Science,T ohoku University.Charged pions and protons in the final state were measured by using the Neutral Kaon Spectrometer (NKS2).The analysis of the γd→π~- pp was mainly used to check the acceptance of the NKS2 and to calibrate the tagged photon energy.The photoproduction of the Δ~(++)Δ~- was identified in the γd→npπ~+π~- reaction.Since the data analyses are still in progress,we issue an interim report and preliminary results.     

Electron scattering based on a novel internal target technique: SCRIT

A novel technique for forming internal targets, named SCRIT (Self-Confining RI Ion Target), has been developed, which can make electron scattering off short-lived radioactive nuclei possible in an electron storage ring. SCRIT confines the ions of interest by utilizing the “ion trapping” phenomenon in the electron storage ring. Approximately 10⁷ stable ¹³³Cs ions were trapped in a three-dimensional configuration along the electron beam axis at an electron beam current of 75mA. The angular distribution of the electrons scattered from the trapped ¹³³Cs ions was successfully measured, and a collision luminosity of 10²⁶/(cm² s) was achieved.     

Energy calibration of tagged photons by the d(γ,π~-pp) reaction

The energy of tagged photons, which were provided from the internal photon tagging system of the Laboratory of Nuclear Science, Tohoku University, has been calibrated using the d(γ,π-pp) reaction. Charged pions and protons in the final state were detected with the Neutral Kaon Spectrometer (NKS2). Photon energies were obtained from the reaction of d(γ,π-pp). The derived photon energy was consistent with the design of the tagger system and the previous measurement using electron-positron pair production. The consistency demonstrates the performance of NKS2 and the capability of the photon energy calibration using d(γ,π-pp).     

卤化银感光材料的现状和未来以及学会的作用

接着以前的几篇文章,作者从光吸收、潜影形成效率、最小潜影中心的尺寸以及材料储存期的稳定性角度,分析了卤化银感光材料已达到的性能现状.潜影形成的效率取决于由吸收的光子产生的量子产率、敏化中心对电子的俘获和光电子与正空穴间的复合.可以肯定,感光材料的性能提高尚有很大的余地.依据上述的考察及其与静态数字照相的比较,可预测未来世界的卤化银感光材料生产的发展会趋缓.有一点应清楚,感光科学与技术彼此间已互动促进了许多年,生产出了高精细、高复杂的感光材料,此类科学与技术不是一些后来者能轻而易举超越的,而且它们所取得的各项进展无不依赖于感光科学和技术学会的种种活动.