Shape coexistence in187Hg

Excited states of¹⁸⁷Hg have been investigated via the¹⁶⁴Dy (²⁸Si,5n) reaction by means of in- beam gamma-ray spectroscopy using the multidetector 4π away “Ckāteau de. Cristal”. Different bands were populated up to spin I- 45/2. Coexistence of both prolate and oblate structures is observed for the first time in an odd- A Hg isotope. The crossing of aligned and strongly coupled sequences of levels built on the vi13/2 orbital infers the near degeneracy of oblate and prolate structures in¹⁸⁷Hg.     

High-spin states in 155Ho

High-spin states in ¹⁵⁵Ho have been populated in the ¹⁴⁵Nd(¹⁴N, 4n)¹⁵⁵Ho reaction. Excitation functions, lifetimes, angular distributions and γ-γ coincidences were measured. An $\text{11}\text{2}{}^{\mathrm{?}}$ isomeric state with $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 0.88}\text{ms}$ has been found at very low energy. The rotational band built on this state is developed up to spin $\text{35}\text{2}$. The behaviour of its moment of inertia is compared with that of the doubly even neighbouring nuclei.     

Biochemical investigation of the formation of three-dimensional networks from DNA-grafted large silica particles

DNA is used to rationally build up networks of silica nanoparticles (SiNPs) based on the molecular recognition properties of complementary sequences. Network self-assembly is controlled from DNA covalently grafted at the surface of chemically modified SiNPs. Two strategies are compared, where grafted DNA sequences are designed in a three-strand system using noncomplementary sequences and an extra DNA linker, or in a two-strand approach for direct hybridization. In this paper, both systems are compared in terms of DNA hybridization stability, network size, and three-dimensional organization using a combination of dynamic light scattering and electron microscopy. The observed differences are discussed in terms of hybridization interactions between DNA sequences in particle-free systems through fluorescence, circular dichroism, and UV spectroscopy techniques.     

Low-energy measurement of the 7Be(p,gamma)8B cross section

We have measured the cross section of the 7Be(p,gamma)8B reaction for E(c.m.) = 185.8, 134.7, and 111.7 keV using a radioactive 7Be target (132 mCi). Single and coincidence spectra of beta+ and alpha particles from 8B and 8Be* decay, respectively, were measured using a large acceptance spectrometer. The zero energy S factor inferred from these data is 18.5+/-2.4 eV b and a weighted mean value of 18.8+/-1.7 eV b (theoretical uncertainty included) is deduced when combining this value with our previous results at higher energies.     

The finite cutset property

A cutset of H is a subset of ∪ H which meets every element of H. H has the finite cutset property if every cutset of H contains a finite one. We study this notion, and in particular how it is related to the compactness of H for the natural topology. MSC: 04A20, 54D30.     

The Menger property for infinite ordered sets

It is shown that, if an ordered set P contains at most k pairwise disjoint maximal chains, where k is finite, then every finite family of maximal chains in P has a cutset of size at most k. As a corollary of this, we obtain the following Menger-type result that, if in addition, P contains k pairwise disjoint complete maximal chains, then the whole family, M (P), of maximal chains in P has a cutset of size k. We also give a direct proof of this result. We give an example of an ordered set P in which every maximal chain is complete, P does not contain infinitely many pairwise disjoint maximal chains (but arbitrarily large finite families of pairwise disjoint maximal chains), and yet M (P) does not have a cutset of size <x, where x is any given (infinite) cardinal. This shows that the finiteness of k in the above corollary is essential and disproves a conjecture of Zaguia.     

Measurement of the ionization probability of the 1s σ MO on the way into the nuclear fusion reaction58Ni+54Fe

The total excitation probability of the 1s σ molecular orbital on the way into the nuclear reaction⁵⁸Ni+⁵⁴Fe at 238 MeV has been directly measured. The result found is (3.1±0.6) 10^?2. The method is based on the detection at zero degree with respect to the beam direction of the x-rays emitted in the reaction, in coincidence with the gamme rays following the deexcitation of the evaporation residues produced in the nuclear reaction. The difference in the doppler shift of the x-ray energies enables to discriminate between the internal conversion x-rays and the prompt atomic x-rays following the decay of the vacancies made in the approach of the nuclear reaction. The experimental data is compared with numerical evaluations of different mechanisms which can produce a vacancy in theK-shell of the united atom at the end of the collision. The best agreement is found with the value of the direct ionization of the 1sσ MO evaluated in the framework of the Brigg's model.