We studied Mn 12 -acetate by inelastic neutron scattering and diffraction. We separated the energy levels corresponding to the splitting of the lowest S multiplet (S 10 ground state). The irregular spacing of the transition energies unambiguously shows the presence of high-order terms in the spin Hamiltonian [D 20.457͑2͒ cm 21 , B 0 4 22.33͑4͒ 3 10 25 cm 21 ]. The relative intensity of the lowest energy peaks is very sensitive to the small transverse term that is responsible for quantum tunneling, providing the first determination of this term in zero magnetic field ͓B 4 4 63.0͑5͒ 3 10 25 cm 21 ͔. PACS numbers: 75.25. + z, 75.45. + j, 78.70.Nx 0031-9007͞99͞83(3)͞628(4)$15.00

TV and T/v (Neel) have been measured for a series of YBa2(Cuo.96Zno.o4)306+x samples. The T variations of the homogeneous susceptibility Xs of the Cu02 planes, given by the shift of the 89 Y NMR line, are found to be nearly unchanged with respect to pure samples for x > 0.5, which implies that the charge transfer is negligibly modified by Zn, and that the magnetic pseudogap is not associated with superconducting pairing. Detection of an unusual Curie contribution to the 89 Y NMR width for x > 0.5 provides evidence that Zn induces magnetic moments in the CuC>2 planes, which play a role in the depression of 7V. PACS numbers: 74.70.Hk, 75.20.Hr, 75.30.Kz, 76.60.Cq The sizable reduction of T c induced by Zn substitutions in cuprates has stimulated a large number of experimental studies [1] to try to understand the changes of the electronic properties induced by Zn. A major problem is to clarify whether the hole content of the conducting CUO2 planes is modified in the presence of zinc. We insist here on the use of microscopic magnetic probes [2,3], such as the 89 Y NMR, which allows a separation of the modifications of the 1:2:3 phase from those associated with the existence of minute amounts of impurity phases. In the course of a detailed study on the phase diagram of pure YBa2Cu3C>6+jc we have evidenced that Zn does not induce an appreciable reduction of Tj\ in YBa2Cu306 [2]. The present work is an attempt to compare the modifications of the magnetic properties over the whole range of oxygen content. We shall see here that both T c and T/v are very sensitive to oxygen doping. This will allow us, among other things, to resolve an apparently conflicting experimental report from Mossbauer data [4] indicating that JT/V is largely reduced by Zn substitution, in YBa2Cu 3 06. But the main concern of this Letter is to provide indications of the changes of the magnetic properties in the metallic state. We show here that the phase diagram versus oxygen content and the determination of the uniform susceptibility % s of the CuC>2 planes from 89 Y NMR data give direct evidence that the charge-transfer processes are not markedly modified by Zn in the metallic state. We rather clearly demonstrate for the first time on microscopic grounds that Zn induces local moments which are certainly responsible for a pair-breaking mechanism or an electronic localization. The fact that the moments are localized in the Q1O2 planes is demonstrated here by comparison with data taken on Co-substituted samples.

Mesoscopic ͑500-2000 Å͒ and microscopic ͑5-20 Å͒ phase segregation with temperature and magnetic field was studied in the model manganite Pr 0.7 Ca 0.3 MnO 3 by high-resolution neutron diffraction and inelastic neutron scattering. Intragranular strain-driven mesoscopic segregation between two insulating phases, one of which is charge ordered ͑CO͒, sets in below the CO temperature in zero field. The CO phase orders antiferromagnetically, while the other insulating phase shows spin-glass behavior. After field-induced metallization, the CO phase coexists with a ferromagnetic metallic phase.

BackgroundParietal fibrinous peritonitis (PFP) and generalised peritonitis (GP) are two postoperative complications in cows, characterised by fluid and fibrin accumulation throughout the peritoneum (GP) or in an encapsulated cavity (PFP). Unlike GP, PFP is scarcely documented.MethodsTwenty-one GP cases and 12 PFP cases were confirmed by ultrasound in cows referred to the Veterinary Clinic (Liège University) for complications after caesarean section. All cows underwent a standardised examination protocol. Blood samples were analysed for metabolic and inflammatory markers. Bacteriology was performed on peritoneal fluid samples. Treatment consisted of surgical drainage of the abdominal cavity (GP) or the encapsulated cavity (PFP). Variables concerning anamnesis, clinical findings and treatment outcomes were compared.ResultsPerioperative complications had occurred in 9/21 GP cows but 0/12 PFP cows (P<0.05). Biochemical analysis indicated pronounced inflammation and did not differ between groups. Peritoneal fluid samples of both groups were contaminated and contained similar bacteria (Trueperella pyogenes and Escherichia coli). While 11/12 PFP cows were discharged, all patients with GP died or were euthanased (P<0.05).ConclusionsWe hypothesise that PFP and GP are two different manifestations of perioperative peritoneal contamination. The severity and spread of the contamination determine the clinical presentation and the prognosis.