Measurement of the [Formula: see text]Ta([Formula: see text]) cross sections up to stellar s-process temperatures at the CSNS Back-n.

The neutron capture cross section of [Formula: see text]Ta is relevant to s-process of nuclear astrophysics, extraterrestrial samples analysis in planetary geology and new generation nuclear energy system design. The [Formula: see text]Ta([Formula: see text]) cross section had been measured between 1 eV and 800 keV at the back-streaming white neutron facility (Back-n) of China spallation neutron source(CSNS) using the time-of-flight (TOF) technique and [Formula: see text] liquid scintillator detectors. The experimental results are compared with the data of several evaluated libraries and previous experiments in the resolved and unresolved resonance region. Resonance parameters are extracted using the R-Matrix code SAMMY in the 1-700 eV region. The astrophysical Maxwell average cross section(MACS) from kT = 5 to 100 keV is calculated over a sufficiently wide range of neutron energies. For the characteristic thermal energy of an astrophysical site, at kT = 30keV the MACS value of [Formula: see text]Ta is 834 ± 75 mb, which shows an obvious discrepancy with the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars (KADoNiS) recommended value 766 ± 15 mb. The new measurements strongly constrain the MACS of [Formula: see text]Ta([Formula: see text]) reaction in the stellar s-process temperatures.

Growth of silver nanocrystals on graphene by simultaneous reduction of graphene oxide and silver ions with a rapid and efficient one-step approach.

A rapid and efficient one-step approach to prepare graphene-Ag nanocomposites by simultaneous reduction of graphene oxide (GO) and silver ions with formaldehyde as the reducing agent within several minutes was demonstrated.

Superhydrophobic pure silver surface with flower-like structures by a facile galvanic exchange reaction with [Ag(NH3)2]OH.

Superhydrophobic pure silver film composed of flower-like microstructures built by interconnected silver nanoplates on a copper plate without any modification was prepared by a facile galvanic exchange reaction between the aqueous [Ag(NH3)2]OH and the copper plate, giving rise to a contact angle as high as 157 degrees .

Colloid chemical reaction route to the preparation of nearly monodispersed perylene nanoparticles: size-tunable synthesis and three-dimensional self-organization.

By employing a colloid chemical reaction method we demonstrate the preparation of organic nanoparticles composed of perylene molecules (PeNPs) based on the reduction of perylene perchlorate by Br- anions in the presence of cetyl trimethyl ammonium bromide (CTA+Br-) in acetonitrile. A discrete nucleation event, followed by a slower controlled growth on the existing particles, is identified during formation of PeNPs. By changing the growth parameters, such as the monomer concentration and the method of injection, quasi-spherical PeNPs with controllable sizes from 25 to 90 nm could be obtained. The homogeneous solution phase of this method makes it capable of large-scale synthesis of PeNPs with a size distribution (<10%) that is improved by formation of a protective layer of CTA+ around the PeNPs. The three-dimensional, hierarchical self-organization of 25-nm PeNPs building blocks is observed to form nanobelts and square nanorods, possibly templated by the CTA+ lamellar micelle structures in acetonitrile. Spectroscopic results reveal two kinds of trends in the development of the optical properties of perylene as they evolve from the molecular to the bulk phase in the nanometer range. The so-called size dependence is evidenced by a switch from Y-type to E-type excimers as the size of the PeNPs increased from 25 to 90 nm. As the 25-nm PeNPs organize into nanobelts or square nanorods the oscillator strength of the Y-type excimers is relatively enhanced. That is, collective phenomena develop as the proximal particles interact in the glassy solids. Our very recent results indicate that this colloid chemical reaction method can also be applied to other organic compounds.