Performance of ceramic anvils for high pressure neutron scattering

Three kinds of ceramics, zirconia-toughened alumina (ZTA), alumina-toughened zirconia (ATZ) and yttria-stabilized zirconia (YSZ), were tested as anvil materials, mainly for the purpose of neutron scattering study under high pressure. ZTA with non-toroidal anvil profile, having the same sample volume as conventionally used double toroidal anvils, sustained pressures up to 11.9?GPa. This is comparable to anvils made of tungsten carbide (TC) with Ni binder with the same dimensions. ATZ would also be an alternative material to TC with pressure performance comparable to ZTA, whereas YSZ is much weaker than the other two ceramics. The attenuation coefficient for YSZ is significantly smaller than that of TC and similar to ZTA and ATZ, the latter being estimated by attenuation calculations. Neutron diffraction on a sample of lead in YSZ anvils as well as quasi-elastic neutron scattering on liquid water in ZTA also demonstrate the outstanding neutron transparency of these ceramics. The gain factor in count rate is up to one order of magnitude.     

Charging of metal adatoms on ultrathin oxide films: Au and Pd on FeO/Pt(111)

We present a combined experimental (STM/scanning tunneling spectroscopy) and theoretical (density functional theory) study on the deposition of Au and Pd metal atoms on FeO/Pt(111) ultrathin films. We show that while the Pd atoms are only slightly oxidized, the Au atoms form positive ions upon deposition, at variance to a charge transfer into the Au atoms as observed for MgO/Ag(100). The modulation of the adsorption properties within the surface Moiré cell and the charging induce the formation a self-assembled array of gold adatoms on FeO/Pt(111), whereas Pd atoms are randomly distributed.     

Platinum(II) halide complexes with propan-1-amine

Summary The complexescis-[PtPra₂X₂],trans-[PtPra₂X₂], [PtPra₃X]X, [PtPra₄]X₂ and [PtPra₄]X₂ · 2H₂O, where Pra= propan-1-amine and X=Cl or Br, have been prepared with good yields and characterized by thermal analysis and i.r. and¹H n.m.r. spectroscopy. The best methods to obtain the pure products are discussed. The TG and DTA data are reported for all the complexes; in particular the thermal degradation of the 13 and 14 bromo-derivatives allows to isolate the intermediatetrans-[PtPra₂Br₂]. The i.r. spectra are characteristic of geometry and stoichiometry, as the¹H n.m.r. spectra ofcis-[PtAm₂Br₂],trans-[PtAm₂Br₂], [PtAm₃Br]Br and [PtAm₄]Br₂ (Am=propan-1-amine or hexan-1-amine) in deuteriated benzene, acetone and chloroform.     

Selmer Groups over p-Adic Lie Extensions I

Let E be an elliptic curve defined over a number field F. Thepaper concerns the structure of the p-Selmer group of E overp-adic Lie extensions F of F which are obtained by adjoiningto F the p-division points of an abelian variety A defined overF. The main focus of the paper is the calculation of the Gal(F_F)-Eulercharacteristic of the p-Selmer group of E. The main theory isillustrated with the example of an elliptic curve of conductor294.     

Control of the charge state of metal atoms on thin MgO films

The arrangement of single gold and palladium atoms deposited on the surface of a 3 monolayer thin film of MgO was investigated using low-temperature scanning tunneling microscopy. While Pd atoms are arranged in a random fashion, Au forms an ordered array on the surface. The long-range ordering as well as the scanning tunneling microscopy appearance of single Au atoms on a 3 monolayer thin MgO film can be explained by partial charge transfer from the substrate to Au atoms as predicted recently by density functional theory calculations [Phys. Rev. Lett. 94, 226104 (2005)10.1103/PhysRevLett.94.226104]. In contrast with that, Au atoms on a thick film were found to be essentially neutral.     

Prediction of uncompensated polarity in ultrathin films

Relying on first principles simulations of stoichiometric MgO, ZnO, and NaCl (1x1) ultrathin (111) films, we demonstrate the existence of a critical thickness below which polarity is uncompensated: the surface charges are bulklike, and the total dipole moment and the formation energy grow linearly with thickness. This study reveals novel facets of the problematics of polarity akin to the nanoscopic size of the objects and opens stimulating perspectives on polar nanostructures with surface properties and reactivity unaffected by charge compensation as in macroscopic samples.     

Spectrally and Time-Resolved Fluorescence Imaging of 22-NBD-Cholesterol in Human Peripheral Blood Mononuclear Cells in Chronic Kidney Disease Patients

The interaction of the fluorescent probe 22-NBD-cholesterol with membranes of human peripheral blood mononuclear cells (PBMC) was tested by time- and spectrally resolved fluorescence imaging to monitor the disturbance of lipid metabolism in chronic kidney disease (CKD) and its treatment with statins. Blood samples from healthy volunteers (HV) and CKD patients, either treated or untreated with statins, were compared. Spectral imaging was done using confocal microscopy at 16 spectral channels in response to 458 nm excitation. Time-resolved imaging was achieved by time-correlated single photon counting (TCSPC) following excitation at 475 nm. The fluorescence of 22-NBD-cholesterol was mostly integrated into plasmatic membrane and/or intracellular membrane but was missing from the nuclear region. The presence of two distinct spectral forms of 22-NBD-cholesterol was uncovered, with significant variations between studied groups. In addition, two fluorescence lifetime components were unmasked, changing in CKD patients treated with statins. The gathered results indicate that 22-NBD-cholesterol may serve as a tool to study changes in the lipid metabolism of patients with CKD to monitor the effect of statin treatment.