Multifunctional and robust composite materials comprising gold nanoparticles at a spherical polystyrene particle surface

The preparation of composite particles comprising gold nanoparticles (4.5–26 nm) assembled at a polystyrene (PS) surface with tunable loading is reported with wide ranging potentials from cellular studies to catalysis.</p

Gamma ray production cross sections in proton induced reactions on natural Mg, Si and Fe targets over the proton energy range 30 up to 66 MeV

Gamma-ray excitation functions have been measured for 30, 42, 54 and 66 MeV proton beams accelerated onto C + O (Mylar), Mg, Si, and Fe targets of astrophysical interest at the separate-sector cyclotron of iThemba LABS in Somerset West (Cape Town, South Africa). A large solid angle, high energy resolution detection system of the Eurogam type was used to record Gamma-ray energy spectra. Derived preliminary results of Gamma-ray line production cross sections for the Mg, Si and Fe target nuclei are reported and discussed. The current cross section data for known, intense Gamma-ray lines from these nuclei consistently extend to higher proton energies previous experimental data measured up to Ep ~ 25 MeV at the Orsay and Washington tandem accelerators. Data for new Gamma-ray lines observed for the first time in this work are also reported.Comment: 11 pages, 6 figures. IOP Institute of Physics Conference Nuclear Physics in Astrophysics VII, 28th EPF Nuclear Physics Divisional Conference, May 18-22 2015, York, U

Measurement and analysis of nuclear γ-ray production cross sections in proton interactions with Mg, Si, and Fe nuclei abundant in astrophysical sites over the incident energy range E = 30–66 MeV

The modeling of nuclear γ -ray line emission induced by highly accelerated particles in astrophysical sites (e.g., solar flares, the gas and dust in the inner galaxy) and the comparison with observed emissions from these sites needs a comprehensive database of related production cross sections. The most important reactions of protons and α particles are those with abundant target elements like C, O, N, Ne, Mg, Si, and Fe at projectile energies extending from the reaction threshold to a few hundred MeV per nucleon. In this work, we have measured γ -ray production cross section excitation functions for 30, 42, 54, and 66 MeV proton beams accelerated onto nat C , C + O (Mylar), nat Mg , nat Si , and 56 Fe targets of astrophysical interest at the Separated Sector Cyclotron (SSC) of iThemba LABS (near Cape Town, South Africa). The AFRODITE array equipped with eight Compton suppressed high-purity (HPGe) clover detectors was used to record γ -ray line energy spectra. For known, intense lines previously reported experimental data measured up to E p ≃ 25 MeV at the Washington and Orsay tandem accelerators were thus extended to higher proton energies. Our experimental data for the last three targets are reported here and discussed with respect to previous data and to the Murphy et al. compilation [Astrophys. J. Suppl. Ser. 183, 142 (2009)]

Nuclear γ-ray line emission induced by energetic ions in solar flares and by galactic cosmic rays

International audienceThe γ-ray spectra ol the strongest solar flares often show a broad and complex structure in the 0.1-10 MeV region sitting on a bremsstrahlung continuum. This structure is composed of several outstanding narrow lines and of thousands of unresolved narrow and broad lines forming a quasi-continuum. The major part of this emission is due to prompt deexcitation lines following nuclear interactions of accelerated light and heavy ions with the atomic nuclei composing the solar atmosphere. A similar emission is expected from interactions of galactic cosmic rays with the interstellar gas and dust. Experimental nuclear reaction studies coupled with extensive calculations have been done in the last one and a half decade at Orsay for the modelisation of this γ-ray emission. After a description of the nuclear reaction studies the analysis of one solar flare spectrum and predictions for the emission from the inner Galaxy will be presented

Recent developments in carbon nanomaterial sensors

Carbon nanomaterials are among the most broadly discussed, researched and applied of synthetic nanomaterials. The structural diversity of these materials provides an array of unique electronic, magnetic and optical properties, which when combined with their robust chemistry and ease of manipulation, makes them attractive candidates for sensor applications. Furthermore, the biocompatibility exhibited by many carbon nanomaterials has seen them used as in vivo biosensors. Carbon nanotubes, graphene and carbon dots have come under intense scrutiny, as either discrete molecular-like sensors, or as components which can be integrated into devices. In this review we consider recent developments in the use of carbon nanoparticles and nanostructures as sensors and consider how they can be used to detect a diverse range of analytes.Irish Research CouncilUniversity College DublinIstituto Italiano di Tecnologi