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Abstract This investigation reports on anisotropy in the magnetic interaction, lattice-orbital coupling and degree of phonon softening in single crystal Ni3TeO6 (NTO) using temperature- and polarization-dependent X-ray absorption spectroscopic techniques. The magnetic field-cooled and zero-field-cooled measurements and temperature-dependent Ni L 3,2-edge X-ray magnetic circular dichroism spectra of NTO reveal a weak Ni-Ni ferromagnetic interaction close to ~60 K (T SO: temperature of the onset of spin ordering) with a net alignment of Ni spins (the uncompensated components of the Ni moments) along the crystallographic c-axis, which is absent from the ab-plane. Below the Néel temperature, T N~ 52 K, NTO is stable in the antiferromagnetic state with its spin axis parallel to the c-axis. The Ni L 3,2-edge X-ray linear dichroism results indicate that above T SO, the Ni 3d e g electrons preferentially occupy the out-of-plane 3d 3z 2 −r 2 orbitals and switch to the in-plane 3d x 2 −y 2 orbitals below T SO. The inherent distortion of the NiO6 octahedra and anisotropic nearest-neighbor Ni-O bond lengths between the c-axis and the ab-plane of NTO, followed by anomalous Debye-Waller factors and orbital-lattice in conjunction with spin-phonon couplings, stabilize the occupied out-of-plane (3d 3z 2 −r 2) and in-plane (3d x 2 −y 2) Ni e g orbitals above and below T SO, respectively.

Abstract The local electronic and atomic structures of the high-quality single crystal of SrFeO3-δ (δ~0.19) were studied using temperature-dependent x-ray absorption and valence-band photoemission spectroscopy (VB-PES) to investigate the origin of anisotropic resistivity in the ab-plane and along the c-axis close to the region of thermal hysteresis (near temperature for susceptibility maximum, Tm~78 K). All experiments herein were conducted during warming and cooling processes. The Fe L 3,2-edge X-ray linear dichroism results show that during cooling from room temperature to below the transition temperature, the unoccupied Fe 3d e g states remain in persistently out-of-plane 3d 3z 2 -r 2 orbitals. In contrast, in the warming process below the transition temperature, they change from 3d 3z 2 -r 2 to in-plane 3d x 2 -y 2 orbitals. The nearest-neighbor (NN) Fe-O bond lengths also exhibit anisotropic behavior in the ab-plane and along the c-axis below Tm. The anisotropic NN Fe-O bond lengths and Debye-Waller factors stabilize the in-plane Fe 3d x 2 -y 2 and out-of-plane 3d 3z 2 -r 2 orbitals during warming and cooling, respectively. Additionally, a VB-PES study further confirms that a relative band gap opens at low temperature in both the ab-plane and along the c-axis, providing the clear evidence of the charge-density-wave nature of SrFeO3-δ (δ~0.19) single crystal.

An integrated hydrogeochemical study was carried out to realize the occurrence of arsenic (As) in a saline aquifer. Saline groundwater was mostly concentrated in the uppermost aquifer, and non-saline water was in the lower aquifer in the study area. High As concentrations were found in both the uppermost and lower aquifers. No correlation among salinity, well depth and As concentration was observed. Various forms of Fe oxyhydroxides were identified in the magnetic fractions, which were concentrated by high gradient magnetic separation (HGMS) technique, revealing that the redox cycling of Fe occurred in the subsurface. High levels of Fe, HCO3-, DOC and NH4+ concentrations accompanying alkaline pH in the As-rich groundwater were consistent with the mechanism triggered by the microbially mediated reductive dissolution of Fe oxyhydroxides. A proposed threshold value of 50μg L-1 As concentration was used as an indicator for identification of active proceeding reductive dissolution of As-bearing Fe oxyhydroxides in the saline aquifer. Desorption behaviors of As were relevant to its valence in the sediments and the co-existence of anions. Experimental and numerical results showed that additions of Cl- and SO42-, which represent the main anions of saline water, had minor effect on leaching sedimentary As. Although bicarbonate addition resulted in less As desorption than that of phosphate on a molar basis, the contribution of bicarbonate to the total release of As was greater than phosphate due to the much higher concentration of bicarbonate in shallow groundwater and the associated microbial mediation. Collectively, the chemical effect of saline water on the As release to groundwater is mild in the coastal aquifer.

For the interpretation of the storm event-induced landslide distribution for an area, deterministic methods are frequently used, while a region's landslide susceptibility is commonly predicted via a statistical approach based upon multi-temporal landslide inventories and environmental factors. In this study we try to use an event-based landslide inventory, a set of environmental variables and a triggering factor to build a susceptibility model for a region which is solved using a multivariate statistical method. Data for shallow landslides triggered by the 2002 typhoon, Toraji, in central western Taiwan, are selected for training the susceptibility model. The maximum rainfall intensity of the storm event is found to be an effective triggering factor affecting the landslide distribution and this is used in the model. The model is built for the Kuohsing region and validated using data from the neighboring Tungshih area and a subsequent storm event – the 2004 typhoon, Mindulle, which affected both the Kuohsing and the Tungshih areas. The results show that we can accurately interpret the landslide distribution in the study area and predict the occurrence of landslides in the neighboring region in a subsequent typhoon event. The advantage of this statistical method is that neither hydrological data, strength data, failure depth, nor a long-period landslide inventory is needed as input.

Besides regulating calcium homeostasis, the effects of vitamin D on vascular tone and metabolic disturbances remain scarce in the literature despite an increase intake with high-fructose corn syrup worldwide. We investigated the effects of calcitriol, an active form of vitamin D, on vascular relaxation, glucose tolerance, and visceral fat pads in fructose-fed rats. Male Wistar-Kyoto rats were divided into 4 groups (n = 6 per group). Group Con: standard chow diet for 8 weeks; Group Fru: high-fructose diet (60% fructose) for 8 weeks; Group Fru-HVD: high-fructose diet as Group Fru, high-dose calcitriol treatment (20 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding; and Group Fru-LVD: high-fructose diet as Group Fru, low-dose calcitriol treatment (10 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding. Systolic blood pressure was measured twice a week by the tail-cuff method. Blood was examined for serum ionized calcium, phosphate, creatinine, glucose, triglycerides, and total cholesterol. Intra-peritoneal glucose intolerance test, aortic vascular reactivity, the weight of visceral fat pads, adipose size, and adipose angiotensin II levels were analyzed at the end of the study. The results showed that the fructose-fed rats significantly developed hypertension, impaired glucose tolerance, heavier weight and larger adipose size of visceral fat pads, and raised adipose angiotensin II expressions compared with the control rats. High- and low-dose calcitriol reduced modestly systolic blood pressure, increased endothelium-dependent aortic relaxation, ameliorated glucose intolerance, reduced the weight and adipose size of visceral fat pads, and lowered adipose angiotensin II expressions in the fructose-fed rats. However, high-dose calcitriol treatment mildly increased serum ionized calcium levels (1.44 ± 0.05 mmol/L). These results suggest a protective role of calcitriol treatment on endothelial function, glucose tolerance, and visceral adiposity in fructose-fed rats.

Microglia-mediated inflammation is implicated in pathogenesis of neurodegenerative diseases. Oroxylin A, a flavonoid isolated from Scutellariae baicalensis, has been shown to ameliorate microglia activation-mediated neurodegeneration in vivo. The molecular mechanism underlying the inhibitory effects of oroxylin A on microglia activation, however, remains unknown. In the present study, effects of oroxylin A co-treated with lipopolysaccharide (LPS, 100 ng/ml) on LPS-induced activation of cultured microglial BV-2 cells were examined. Nitric oxide (NO) production was determined by Greiss method. Expression of inducible nitric oxide synthase (iNOS), interleukin (IL)-1β and IL-6 was assessed using real-time RT-PCR or Western blot analysis. Furthermore, activation of the nuclear factor κB (NFκB) and the signal transducer and activator of transcription 1 (STAT1) was examined by Western blot analysis and transcription factor DNA-binding activity assay. Our results indicated that oroxylin A (10-100 µM) in a concentration-dependent manner inhibited LPS-induced NO production via blocking iNOS expression at both mRNA and protein levels without affecting the degradation rate of iNOS mRNA. Moreover, oroxylin A significantly attenuated LPS-induced late expression (20 hours after LPS challenge) of IL-1β and IL-6. Furthermore, oroxylin A significantly suppressed LPS-induced JAK2-mediated STAT1 phosphorylation without affecting LPS-induced NFκB-p65 nuclear translocation or NFκB-p65 DNA-binding activity. This is consistent with the finding that AG490, a specific JAK2 inhibitor, significantly inhibited LPS-induced STAT1 phosphorylation with almost completely diminished iNOS expression. These results suggest that oroxylin A, via suppressing STAT1 phosphorylation, inhibits LPS-induced expression of pro-inflammatory genes in BV-2 microglial cells.

BACKGROUND AND PURPOSE: Successful drug treatment for sepsis-related acute lung injury (ALI) remains a major clinical problem. This study was designed to assess the beneficial effects of post-treatment of oroxylin A (OroA), a flavonoid, in ameliorating lipopolysaccharides (LPS)-induced lung inflammation and fatality. EXPERIMENTAL APPROACH: Rats were injected with LPS (10 mg/kg, iv) to induce ALI, and OroA was given (15 mg/kg, iv) 1 hr or 6 hrs after LPS challenge. Twenty four hrs after LPS challenge, biochemical changes in the blood and lung tissues, and morphological/histological alterations in the lung associated with inflammation and injury were examined. Therapeutic effect of OroA was assessed by measuring the survival rate in endotoxemic mice. KEY RESULTS: LPS (10 mg/kg, iv) significantly altered WBC counts, elevated plasma tumor necrosis factor (TNF)-α and nitric oxide (NO), increased pulmonary edema, thickened alveolar septa, and decreased survival rate. These changes were ameliorated by OroA (15 mg/kg, iv) administered 1 hr or 6 hrs after LPS challenge. This post-treatment also significantly attenuated LPS-induced activation of nuclear factor-κB (NF-κB) and the release of high mobility group box 1 (HMGB1) in lung tissues. Furthermore, post-treatment with OroA (60 mg/kg, ip) administered 1 hr or 6 hrs after LPS challenge in mice significantly increased survival rate. CONCLUSION AND IMPLICATION: OroA administered after induction of ALI by LPS significantly prevent and revere lung tissues injuries with increased survival rate. Positive post-treatment effects of OroA suggest that OroA is a potentially useful candidate for managing lung inflammation in LPS-induced endotoxemia and septic shock.

The effect of isovalent chemical substitution of [Eu.sup.3+] into the [Tb.sup.3+] sites on the magnetic and electrical properties of ([Tb.sub.1-x][Eu.sub.x])Mn[O.sub.3] (0 less than equal to x less than equal to 1.0) system is examined. The results have shown that the increase in the Eu content has increased both the tolerance factor and Mn-O bond distance, leading to the reduction in the octahedral distortion and Jahn-Teller (JT) effect.

We present the orbital structure of MnTiO3 with polarization dependent x-ray absorption and resonant x-ray emission spectra accompanied with electronic structure calculations. The results clearly indicate a strongly anisotropic O 2p-Mn 3d orbital hybridization whereas the Mn 3d hole state shows a highly delocalized characteristic ascribed to the 3d-4p mixing. The extended Mn 4p orbital could enhance the exchange interaction between Mn (3d)-O (2p)-Mn (3d) leading to an asymmetric charge distribution in Mn-O bonds. The delocalized characteristic of Mn 3d holes is indispensable to the mechanism of spin-dependent-metal-ligand hybridization to explain magnetically induced ferroelectricity. [ABSTRACT FROM AUTHOR]

Abstract X-ray absorption near-edge structure (XANES) data for the PrBa2Cu3O7-y (6.21=7-y=6.95) insulating system with anomalous Pr antiferromagnetic order are reported. Pr L3-edge XANES indicates that Pr formal valence decreases from 3.17–3.18 for oxygenated samples to 3.09 for oxygen-depleted PrBa2Cu3O6.43, 3.03 for PrBa2Cu3O6.38 and 3. 01 for PrBa2Cu3O6.21. The variation of Pr valence indicates that the doped holes initially stay in the CuO1-y plane and contribute to Cu(I)–Cu(II) transformation in this plane, but gradually move into the CuO2 bi-layers with PrO8 cage and result in the appearance of Pr(IV) localized-hole state with, increasing oxygen content. Cu K-edge XANES indicates that the average Cu formal valence increases from less than 2 in oxygen-depleted region to a value larger than 2 for oxygenated samples. with the estimated Cu valence of 2.24 for PrBa2Cu3O6.95. The small average Cu formal valence or large Pr formal valence is closely related to the absence of superconductivity. [ABSTRACT FROM AUTHOR]

Abstract Ru L3-edge X-ray absorption near-edge structure (XANES) and magnetic studies for Ca2RuO4 antiferromagnetic insulator, Sr2RuO4p-wave superconductor, CaRuO3 exchange-enhanced paramagnetic metal, SrRuO3 itinerant ferromagnetic metal and BaRuO3 paramagnetic metal are compared. Although these compounds crystallized with different structural distortions, they possess similar RuO6 octahedral environment where the Ru 4d orbitals are split into partially filled t2g bands with four electrons and empty eg bands. Two 2P3/2-4d dipole transition peaks are observed with lower energy peak A for transition to unfilled t2g states and the higher energy peak B to empty eg states. The L3-edge absorption intensity, shape and eg-t2g average band separation ?E(B-A) is closely related to the variation of RuO6 distortion, Ru-O d-p hybridization and unfilled Ru 4d band width. [ABSTRACT FROM AUTHOR]

Short-range-order and long-range-order structures in Ge1 − xSnx/Ge thin films grown by molecular beam epitaxy (MBE) were investigated by using extended x-ray absorption fine structure (EXAFS) and x-ray diffraction (XRD) techniques, respectively. These materials are of great potential for constructing efficient optoelectronic devices. The EXAFS analysis demonstrates that Sn atoms occupy Ge sites in these thin-film samples with Sn concentration up to 20 at.%. The Ge-Sn bonds expected in the substitutional model were also observed in Raman spectra of these samples. The XRD results show that, in the out-of-plane direction, the lattice constants of the films are distinctly larger than that of the Ge substrates. However, such increased lattice parameters were not observed in the in-plane direction. Our x-ray and Raman results have clearly revealed substitutional incorporation of Sn with high concentration in dislocation-free MBE-grown Ge films of practical-device thickness. [ABSTRACT FROM AUTHOR]