No abstract

Background: The resonance structure in 11 C is particularly of interest with regard to the astrophysical 7 Be(α, γ) reaction, relevant at high temperature, and to the α-cluster structure in 11 C.Purpose: The measurement was to determine unknown resonance parameters for the high excited states of 11 C. In particular, the α decay width can be useful information to discuss α cluster structure in 11 C.Methods: New measurements of the 7 Be+α resonant scattering and the 7 Be(α, p) 10 B reaction in inverse kinematics were performed for center-of-mass energy up to 5.5 MeV, and the resonances at excitation energies of 8.9-12.7 MeV in the compound 11 C nucleus were studied. Inelastic scattering of 7 Be+α and the 7 Be(α, p1) 10 B * reaction were also studied with a simultaneous γ-ray measurement. The measurements were performed at the low-energy RI beam facility CRIB (CNS Radioactive Ion Beam separator) of the Center for Nuclear Study (CNS), the University of Tokyo. Results:We obtained excitation functions of 7 Be(α, α0) 7 Be (elastic scattering), 7 Be(α, α1) 7 Be * (inelastic scattering), 7 Be(α, p0) 10 B, and 7 Be(α, p1) 10 B * . Many resonances including a new one were observed and their parameters were determined by an R-matrix analysis. Conclusions:The resonances we observed possibly enhance the 7 Be(α, γ) reaction rate but in a smaller magnitude than the lower-lying resonances. A new negative-parity cluster band, similar to the one previously suggested in the mirror nucleus 11 B, is proposed.

It is a well-known fact that a cluster of nucleons can be formed in the interior of an atomic nucleus, and such clusters may occupy molecular-like orbitals, showing characteristics similar to normal molecules consisting of atoms. Chemical molecules having a linear alignment are commonly seen in nature, such as carbon dioxide. A similar linear alignment of the nuclear clusters, referred to as linear-chain cluster state (LCCS), has been studied since the 1950s, however, up to now there is no clear experimental evidence demonstrating the existence of such a state. Recently, it was proposed that an excess of neutrons may offer just such a stabilizing mechanism, revitalizing interest in the nuclear LCCS, specifically with predictions for their emergence in neutron-rich carbon isotopes. Here we present the experimental observation of α-cluster states in the radioactive 14 C nucleus. Using the 10 Be+α resonant scattering method with a radioactive beam, we observed a series of levels which completely agree with theoretically predicted levels having an explicit linear-chain cluster configuration. We regard this as the first strong indication of the linear-chain clustered nucleus.

No abstract

Radiation-induced synthesis of colloidal silver nanoparticles (Ag-NPs) using chitosan (CTS) as a stabiliser and free radical scavenger is feasible and satisfiable to green method. The conversion dose (Ag þ into Ag 0) was determined by UV-Vis spectroscopy and Ag-NPs size was characterised by transmission electron microscopy. The average diameter of Ag-NPs was smaller than 10 nm with narrow size distribution and the colloidal Ag-NPs have good stability for a long time of storage. The effect of several parameters, such as pH, Ag þ and CTS concentration and molecular weight of CTS on Ag-NPs size was also investigated. Ag-NPs of $7 nm exhibited highly antimicrobial effect. The inhibitory efficiency of Ag-NPs for Staphylococcus aureus was more than 99.9% at 5 ppm and the effective dose (ED 50) of inhibition for Corticium salmonicolor was of 27.2 ppm.

No abstract

No abstract

Colloidal silver nanoparticles were prepared by -irradiating Ag þ in aqueous solution in the presence of 2% polyvinyl pyrrolidone (PVP) as stabilising agent and ethyl alcohol as free radical (OH . ) scavenger. The saturated conversion dose of Ag þ into Ag was determined by UV-Vis spectroscopy and the silver nanoparticles size was characterised by transmission electron microscopy. The influence of Ag þ concentration (1-50 mM) on the saturated conversion dose and average diameter of silver nanoparticles was investigated. Results showed that the saturated conversion dose was from 8 to 48 kGy and the silver particles size was in the range of 6-21 nm for Ag þ concentration from 1 to 50 mM. The effect of PVP molecular weight on silver particles size was studied as well.