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Nucleon scattering on actinides using a dispersive optical model with extended couplings
Tamura coupling model has been extended to consider the coupling of
additional low-lying rotational bands to the ground state band. Rotational
bands are built on vibrational bandheads (even-even targets) or single particle
bandheads (odd- targets) including both axial and non-axial deformations.
These additional excitations are introduced as a perturbation to the underlying
axially-symmetric rigid rotor structure of the ground state rotational band.
Coupling matrix elements of the generalized optical model are derived for
extended multi-band transitions in even-even and odd- nuclei. Isospin
symmetric formulation of the optical model is employed.
A coupled-channels optical model potential (OMP) containing a dispersive
contribution is used to fit simultaneously all available optical experimental
databases including neutron strength functions for nucleon scattering on
Th, U and Pu nuclei and quasi-elastic (,)
scattering data on Th and U. Lane consistent OMP is derived for
all actinides if corresponding multi-band coupling schemes are defined.
Calculations using the derived OMP potential reproduce measured total
cross-section differences between several actinide pairs within experimental
uncertainty for incident neutron energies from 50 keV up to 150MeV. Multi-band
coupling is stronger in even-even targets due to the collective nature of the
coupling; the impact of extended coupling on predicted compound-nucleus
formation cross section reaches 5% below 3 MeV of incident neutron energy.
Coupling of ground-state rotational band levels in odd- nuclei is sufficient
for a good description of the compound-nucleus formation cross sections as long
as the coupling is saturated (a minimum of 7 coupled levels are typically
needed).Comment: 30 pages, 4 figures, 8 tables, 3 appendice
Predicting the optical observables for nucleon scattering on even-even actinides
Previously derived Lane consistent dispersive coupled-channel optical model
for nucleon scattering on Th and U nuclei is extended to
describe scattering on even-even actinides with 90--98. A
soft-rotator-model (SRM) description of the low-lying nuclear structure is
used, where SRM Hamiltonian parameters are adjusted to the observed collective
levels of the target nucleus. SRM nuclear wave functions (mixed in quantum
number) have been used to calculate coupling matrix elements of the generalized
optical model. The "effective" deformations that define inter-band couplings
are derived from SRM Hamiltonian parameters. Conservation of nuclear volume is
enforced by introducing a dynamic monopolar term to the deformed potential
leading to additional couplings between rotational bands. Fitted static
deformation parameters are in very good agreement with those derived by Wang
and collaborators using the Weizs\"acker-Skyrme global mass model (WS4),
allowing to use the latter to predict cross section for nuclei without
experimental data. A good description of scarce "optical" experimental database
is achieved. SRM couplings and volume conservation allow a precise calculation
of the compound-nucleus formation cross sections, which is significantly
different from the one calculated with rigid-rotor potentials coupling the
ground-state rotational band. Derived parameters can be used to describe both
neutron and proton induced reactions.Comment: 6 pages, 4 figures, 5 table
Synthesis and coordination chemistry of 2-(di-2-pyridylamino)pyrimidine; structural aspects of spin crossover in an Fe(II) complex
This paper was accepted on February 26 20122-(Di-2-pyridylamino)pyrimidine (L), a potentially ditopic tetradentate ligand, was synthesized from commercially available di-2-pyridylamine and 2-chloropyrimidine. Despite being capable of bridging two metal atoms with bidentate chelation of both metal centres, L prefers to chelate or bridge through the more basic pyridyl donors of the di-2-pyridylamine moiety. Mononuclear trans-[Fe(NCS)2(L)2] and [Cu(L)2(H2O)](BF4)2•H2O complexes, and a discrete [Ag2(L)4](PF6)2 metallomacrocycle were isolated and structurally characterized by X-ray crystallography. A mononuclear palladium complex [PdCl2(L)]•(solvate), where solvate = ½H2O or CH2Cl2, was also readily obtained in 71% yield. One example of the ligand acting as a bis(bidentate) bridging ligand was observed in a dinuclear [(PdCl2)2(L)]•¾H2O complex that was obtained only in very low yield (ca. 3%) from the reaction that produced [PdCl2(L)]•½H2O. trans-[Fe(NCS)2(L)2] undergoes a temperature dependent HS-LS (HS = high spin; LS = low spin) crossover at ca. 205 K that was 2 observed by X-ray crystallography and magnetic measurements and attempts were made to understand the structural basis of this process. Despite efforts to isolate examples of L bridging two iron(II) centres, only the mononuclear trans-[Fe(NCS)2(L)2] species could be obtained.Rachel S. Crees, Boujemma Moubaraki, Keith S. Murray, and Christopher J. Sumb
A novel route to Pt-Bi2O3 composite thin films and their application in photo-reduction of water
A novel homoleptic bismuth(III) β-diketonate (dibenzoylmethane – dbm) complex [Bi(dbm)3]2 has been used as a precursor to thin films of crystalline β-Bi2O3, and hexachloroplatinic acid (H2PtCl6·6H2O) has been demonstrated as a suitable precursor for deposition of platinum nanoparticles, both deposited via aerosol-assisted chemical vapour deposition (AACVD). Thin films of Pt–Bi2O3 were co-deposited from a mixture of [Bi(dbm)3]2 and H2PtCl6·6H2O; the introduction of Pt particles into β-Bi2O3 causes hydrogen to be evolved during photolysis of water over the composite material, a property not found for Pt particles or β-Bi2O3 alone
Novel application assigned to toluquinol: inhibition of lymphangiogenesis by interfering with VEGF-C/VEGFR-3 signalling pathway
BACKGROUND AND PURPOSE
Lymphangiogenesis is an important biological process associated with the pathogenesis of several diseases, including metastatic
dissemination, graft rejection, lymphoedema and other inflammatory disorders. The development of new drugs that block
lymphangiogenesis has become a promising therapeutic strategy. In this study, we investigated the ability of toluquinol,
a 2-methyl-hydroquinone isolated from the culture broth of the marine fungus Penicillium sp. HL-85-ALS5-R004, to inhibit
lymphangiogenesis in vitro, ex vivo and in vivo.
EXPERIMENTAL APPROACH
We used human lymphatic endothelial cells (LECs) to analyse the effect of toluquinol in 2D and 3D in vitro cultures and in the
ex vivo mouse lymphatic ring assay. For in vivo approaches, the transgenic Fli1:eGFPy1 zebrafish, mouse ear sponges and cornea
models were used. Western blotting and apoptosis analyses were carried out to search for drug targets.
KEY RESULTS
Toluquinol inhibited LEC proliferation,migration, tubulogenesis and sprouting of new lymphatic vessels. Furthermore, toluquinol
induced apoptosis of LECs after 14 h of treatment in vitro, blocked the development of the thoracic duct in zebrafish and reduced
the VEGF-C-induced lymphatic vessel formation and corneal neovascularization in mice. Mechanistically, we demonstrated that
this drug attenuates VEGF-C-induced VEGFR-3 phosphorylation in a dose-dependentmanner and suppresses the phosphorylation
of Akt and ERK1/2.
CONCLUSIONS AND IMPLICATIONS
Based on these findings, we propose toluquinol as a new candidate with pharmacological potential for the treatment of
lymphangiogenesis-related pathologies. Notably, its ability to suppress corneal neovascularization paves the way for applications
in vascular ocular pathologies.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. This work has been
supported by personal funding by FP7-PEOPLE-2013-IEF Marie
Curie Postdoctoral Fellowship (MGC). Acknowledged are the
supporting grants from the Action de Recherche Concertée
(ARC) (Université de Liège), the Fonds de la Recherche
Scientifique-FNRS (F.R.S.-FNRS), the Foundation Against Cancer
(foundation of public interest), the Centre Anticancéreux près
l’Université de Liège, the Fonds Léon Fredericq (University of
Liège), the Interuniversity Attraction Poles Programme-Belgian
Science Policy (all from Belgium) and the Plan National Cancer
(« Service Public Federal » from Belgium). Research in the lab of
A.R.Q. and M.A.M. was supported by grants BIO2014-56092-R
(MINECO and FEDER) and P12-CTS-1507 (Andalusian
Government and FEDER)
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