Pressure-induced changes in the magnetic and valence state of EuFe2As2

We present the results of electrical resistivity, ac specific heat, magnetic susceptibility, X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) of the ternary iron arsenide EuFe2As2 single crystal under pressure. Applying pressure leads to a continuous suppression of the antiferromagnetism associated with Fe moments and the antiferromagnetic transition temperature becomes zero in the vicinity of a critical pressure Pc ~2.5-2.7 GPa. Pressure-induced re-entrant superconductivity, which is highly sensitive to the homogeneity of the pressure, only appears in the narrow pressure region in the vicinity of Pc due to the competition between superconductivity and the antiferromagnetic ordering of Eu2+ moments. The antiferromagnetic state of Eu2+ moments changes to the ferromagnetic state above 6 GPa. We also found that the ferromagnetic order is suppressed with further increasing pressure, which is connected with a valence change of Eu ions.Comment: 7 pages, 7 figures, accepted for publication in Phys. Rev.

A Nuclear Structure Study of Doubly Odd Nuclei 154Tb and 156Ho

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Control of nanostructures by cooling rate in spinel-type manganese oxide ZnMnGaO4

Controllability of the nanostructures in spinel-type manganese oxide ZnMnGaO4 by changing cooling rate was studied via transmission electron microscopy (with selected area electron diffraction and bright- and dark-field imaging) as well as X-ray diffraction. The Quench sample exhibited a tweed pattern, suggesting the coexistence of two phases at the nanometer scale. The nanostructural changes from a fine twin structure to a checkerboard nanostructure, followed by the emergence of a lamellar-type nanostructure, were clearly observed as the cooling rate decreased from quenching to 1 °C h−1. It was suggested that the diffusion of manganese ions accompanied by the Jahn–Teller distortion play an important role in the formation of nanostructures of this system

Nuclear g-Factor of the 275.4-keV 5- Isomeric State in 212At

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Reduction of the Neutron-Induced r-Ray Background in an ISOL Experiment by Making Use of a Beam Chopper

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In-Beam r-Ray Spectroscopy of 107In

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Hydrogen peroxide is not the cause of fish kills associated with Chattonella marina : cytological and physiological evidence

Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Aquatic Toxicology 72 (2005): 351-360, doi:10.1016/j.aquatox.2005.01.007.Chattonella marina, a harmful algal bloom (HAB) causative species, was used to study the mortality, physiology, and pathology of a marine stenohaline fish, goldlined seabream exposed to the toxic alga. The median lethal time (LT50) was 3 h upon exposure to 8000 cells/ml of C. marina. Significant induction of filamental chloride cells (CCs) [i.e. increases in CC fractional area and in the volume density of CCs], concomitant with significant reduction of blood osmolality, were found in C. marina treated fish. To verify whether the toxicity of C. marina was mediated through oxidative stress, a hydrogen peroxide exposure experiment was carried out and the toxicity as well as cytological and physiological changes were compared with the C. marina treatment. Hydrogen peroxide at a concentration of 500 μM H2O2, (i.e. 25 times higher than that produced by 8000 cells/ml of C. marina (20 μM H2O2)) was unable to induce similar CC alterations and osmoregulatory impairment in fish as observed in the C. marina treatment. Non-specific membrane damage such as severe loss of microvilli projections on the CC apical opening and rupture of epithelial membranes in the lamellae were observed. The LT50 was 6 h, two times longer than that with 8000 cells/ml of C. marina. Based on the cytological and physiological evidence and toxicity data, the mechanism by which C. marina kills fish appears to be very different from that caused by H2O2/ROS. Osmoregulatory distress is the major cause of fish death upon exposure to C. marina.The work described in this paper was supported by a grant from the Research Grants Council (Project No. 9040547 CityU 1105/00M) and a grant from the University Grants Committee (Project No. AoE/P-04/04) of the Hong Kong Special Administrative Region, China. Support for D. Anderson was also provided by the US National Science Foundation through grant no. OCE-0136861

Self-assembled lamellar-type nanostructure in manganite spinel (Co, Mn, Fe)3O4

Distinct nanostructures in (Co,Mn,Fe)3O4 were investigated using X-ray diffraction techniques combined with transmission and scanning transmission electron microscopy, as well as energy dispersive X-ray spectroscopy. The size of the checkerboard nanostructure increased with annealing, followed by the appearance of lamellar nanostructures comprising different types of platelike nanodomains because of nanoscopic spinodal decomposition of Mn and Fe ions. Remarkable local strain relaxation at the nanoscale associated with the domain size is suggested to play an important role in the stabilization of these checkerboard and lamellar nanostructures

Revised Structure of Cercidinin A, a Novel Ellagitannin Having (R)-Hexahydroxydiphenoyl Esters at the 3, 4-Positions of Glucopyranose

The structue of cercidinin A, an ellagitannin isolated from the bark of Cercidiphyllum japonicum, was revised to 1, 2, 6-tri-O-galloyl-3, 4-(R)-hexahydroxydipenoyl-β-D-glucose by two-dimensional NMR spectral analysis. Cercidinin A represents the first ellagitannin possessing a hexahydroxydiphenoyl group at the 3, 4-positions of a modified 4C1-glucopyranose core