Reduction of brain metastases in plasminogen activator inhibitor-1-deficient mice with transgenic ocular tumors

Plasminogen activator inhibitor-1 is known to play a paradoxical positive role in tumor angiogenesis, but its contribution to metastatic spread remains unclear. We studied the impact of plasminogen activator inhibitor (PAI)-1 deficiency in a transgenic mouse model of ocular tumors originating from retinal epithelial cells and leading to brain metastasis (TRP-1/SV40 Tag mice). PAI-1 deficiency did not affect primary tumor growth or vascularization, but was associated with a smaller number of brain metastases. Brain metastases were found to be differentially distributed between the two genotypes. PAI-1-deficient mice displayed mostly secondary foci expanding from local optic nerve infiltration, whereas wild-type animals displayed more disseminated nodules in the scissura and meningeal spaces. SuperArray GEarray analyses aimed at detecting molecules potentially compensating for PAI-1 deficiency demonstrated an increase in fibroblast growth factor-1 (FGF-1) gene expression in primary tumors, which was confirmed by reverse transcription-polymerase chain reaction and western blotting. Our data provide the first evidence of a key role for PAI-1 in a spontaneous model of metastasis and suggest that angiogenic factors, such as FGF-1, may be important for primary tumor growth and may compensate for the absence of PAI-1. They identify PAI-1 and FGF-1 as important targets for combined antitumor strategie

Metal insulator transition in TlSr2CoO5 from orbital degeneracy and spin disproportionation

To describe the metal insulator transition in the new oxide TlSr2CoO5 we investigate its electronic structure by LDA and model Hartree-Fock calculations. Within LDA we find a homogeneous metallic and ferromagnetic ground state, but when including the Coulomb interaction more explicitly within the Hartree-Fock approximation, we find an insulating state of lower energy with both spin and orbital order. We also interpret our results in terms of a simple model.Comment: 8 pages, 9 figure

Quantum Critical Behavior and Possible Triplet Superconductivity in Electron Doped CoO2 Sheets

Density functional calculations are used to investigate the doping dependence of the electronic structure and magnetic properties in hexagonal Na$_x$CoO$_2$. The electronic structure is found to be highly two dimensional, even without accounting for the structural changes associated with hydration. At the local spin density approximation level, a weak itinerant ferromagnetic state is predicted for all doping levels in the range $x=0.3$ to $x=0.7$, with competing but weaker itinerant antiferromagnetic solutions. The Fermi surface, as expected, consists of simple rounded hexagonal cylinders, with additional small pockets depending on the $c$ lattice parameter. Comparison with experiment implies substantial magnetic quantum fluctuations. Based on the Fermi surface size and the ferromagnetic tendency of this material,it is speculated that a triplet superconducting state analogous to that in Sr$_2$RuO$_4$ may exist here.Comment: 4 pages, 1 figur

Impurity-induced transition and impurity-enhanced thermopower in the thermoelectric oxide NaCo_{2-x}Cu_x$O_4

Various physical quantities are measured and analysed for the Cu-substituted thermoelectric oxide NaCo_{2-x}Cu_xO_4. As was previously known, the substituted Cu enhances the thermoelectric power, while it does not increase the resistivity significantly. The susceptibility and the electron specific-heat are substantially decreased with increasing x, which implies that the substituted Cu decreases the effective-mass enhancement. Through a quantitative comparison with the heavy fermion compounds and the valence fluctuation systems, we have found that the Cu substitution effectively increases the coupling between the conduction electron and the magnetic fluctuation. The Cu substitution induces a phase transition at 22 K that is very similar to a spin-density-wave transition.Comment: 8 pages, 7 figures, submitted to Phys. Rev.

Hidden magnetic transitions in thermoelectric layered cobaltite, [Ca2_2CoO3_3]0.62_{0.62}[CoO2_2]

A positive muon spin rotation and relaxation ($\mu^+$SR) experiment on [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$], ({\sl i.e.}, Ca$_3$Co$_4$O$_9$, a layered thermoelectric cobaltite) indicates the existence of two magnetic transitions at $\sim$ 100 K and 400 - 600 K; the former is a transition from a paramagnetic state to an incommensurate ({\sf IC}) spin density wave ({\sf SDW}) state. The anisotropic behavior of zero-field $\mu^+$SR spectra at 5 K suggests that the {\sf IC-SDW} propagates in the $a$-$b$ plane, with oscillating moments directed along the c-axis; also the {\sf IC-SDW} is found to exist not in the [Ca$_2$CoO$_3$] subsystem but in the [CoO$_2$] subsystem. In addition, it is found that the long-range {\sf IC-SDW} order completes below $\sim$ 30 K, whereas the short-range order appears below 100 K. The latter transition is interpreted as a gradual change in the spin state of Co ions %% at temperatures above 400 K. These two magnetic transitions detected by $\mu^+$SR are found to correlate closely with the transport properties of [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$].Comment: 7 pages, 8 figures. to be appeared in Phys. Rev.

Static magnetic order in Na0.75_{0.75}CoO2_2 detected by muon spin rotation and relaxation

The nature of the magnetic transition of the Na-rich thermoelectric Na$_{0.75}$CoO$_2$ at 22K was studied by positive muon-spin-rotation and relaxation ($\mu^+$SR) spectroscopy, using a polycrystalline sample in the temperature range between 300 and 2.5 K. Zero field $\mu$SR measurements indicated the existence of a static internal magnetic field at temperatures below 22 K (= $T_{\rm m}$). The observed muon spin precession signal below $T_{\rm m}$ consisted of three components with different precession frequencies, corresponding to three inequivalent muon$^+$ sites in the Na$_{0.75}$CoO$_2$ lattice. The total volume fraction of the three components was estimated as $\sim$21% at 2.5 K; thus, this magnetic transition was not induced by impurities but is an intrinsic change in the magnetism of the sample, although the sample was magnetically inhomogeneous otherwise. On the other hand, a similar experiment on a Na$_{0.65}$CoO$_2$ sample exhibited no magnetic transition down to 2.5 K; which indicates that the average valence of the Co ions is responsible for inducing the magnetic transition at 22 K.Comment: 5 pages, 4 figures, Phys. Rev. B 68 (2003) in pres

Giant Planet Formation and Migration

© 2018, The Author(s). Planets form in circumstellar discs around young stars. Starting with sub-micron sized dust particles, giant planet formation is all about growing 14 orders of magnitude in size. It has become increasingly clear over the past decades that during all stages of giant planet formation, the building blocks are extremely mobile and can change their semimajor axis by substantial amounts. In this chapter, we aim to give a basic overview of the physical processes thought to govern giant planet formation and migration, and to highlight possible links to water delivery.S.-J. Paardekooper is supported by a Royal Society University Research Fellowship. A. Johansen is supported by the Knut and Alice Wallenberg Foundation, the Swedish Research Council (grant 2014-5775) and the European Research Council (ERC Starting Grant 278675-PEBBLE2PLANET)

Characterization of New Lead-Based Monophosphate Tungsten Bronzes, Pbx(PO2)4(WO3)2m(6≤m≤10)

International audienc

Characterization of New Lead-Based Monophosphate Tungsten Bronzes, Pbx(PO2)4(WO3)2m(6≤m≤10)

International audienc

Need for a better safety evaluation of food contact materials produced from resins

International audienceHistorically, due to the often overwhelming Complexity Of the Substances migrating from food contact materials (FCMs) into food, the specific legislation in Europe started from the Substances used to manufacture these materials and articles. There are, however, FCMs with migrates almost exclusively consisting of reaction products, such as those produced from resins used, e.g. for coatings (epoxy resins, polyesters, organosols, trimellitic acid resins). Since the reaction products do not necessarily have the same toxicological profile as the starting substances to produce the resins, the use of authorized starting substances does not rule out the migration of compounds endangering human health. The European framework Regulation 1935/2004 requires the safety of all substances migrating from FCMs into food. Resolution AP2004/1 on coatings of the Council of Europe Puts the emphasis on the safety evaluation of the migrants rather than that of the substances used for manufacturing the resins and then the coatings. Nonetheless, the Code of Practice for Coatings recently issued by industry focuses oil the evaluation of the starting substances to produce resins. The authors of this paper consider the present situation unsatisfactory. it is the duty of industry to respect the legal requirements and of the regulatory authorities to ensure that these requirements are met. The authors recommend setting a time limit to have this achieved