Itinerant Ferromagnetism in layered crystals LaCoOX (X = P, As)

The electronic and magnetic properties of cobalt-based layered oxypnictides, LaCoOX (X = P, As), are investigated. LaCoOP and LaCoOAs show metallic type conduction, and the Fermi edge is observed by hard x-ray photoelectron spectroscopy. Ferromagnetic transitions occur at 43 K for LaCoOP and 66 K for LaCoOAs. Above the transition temperatures, temperature dependence of the magnetic susceptibility follows the Curie-Weiss law. X-ray magnetic circular dichroism (XMCD) is observed at the Co L2,3-edge, but not at the other edges. The calculated electronic structure shows a spin polarized ground state. These results indicate that LaCoOX are itinerant ferromagnets and suggest that their magnetic properties are governed by spin fluctuation.Comment: 16 pages, 9 figures, Physical Review B, in press. Received 17 February 2008. Accepted 29 May 200

Appearance of ferromagnetism in Pt(100) ultrathin films originated from quantum-well states with possibility of small orbital magnetic moment

Ferromagnetism was observed in a Pt(100) ultrathin film deposited on a SrTiO3(100) substrate. The ferromagnetism, which appears in films with thicknesses of 2.2-4.4 nm, periodically changes with a period of approximately 1 nm (5-6 ML) depending on the film thickness. This is consistent with the period derived from the quantum-well states formed in the thin film. X-ray magnetic circular dichroism measurements were conducted to understand the intrinsic nature of the ferromagnetism in the Pt(100) ultrathin films, and contrary to our expectations, the orbital magnetic moment of pure Pt is much smaller than that of the Pt/ferromagnetic multilayer system. These results suggest that the origin of the large magnetic anisotropy in Pt components cannot be explained only by the amount of spin-orbit coupling in Pt.Comment: 7 pages, 4 figure

Effects of muscle cooling on kinetics of pulmonary oxygen uptake and muscle deoxygenation at the onset of exercise

This study investigated effects of skeletal muscle cooling on the metabolic response and kinetics of pulmonary oxygen uptake (urn:x-wiley:2051817X:media:phy213910:phy213910-math-0001O2) and skeletal muscle deoxygenation during submaximal exercise. In the cooling condition (C), after immersion of the lower body into 12°C water for 30 min, eight healthy males performed 30‐min cycling exercise at the lactate threshold while undergoing thigh cooling by a water‐circulating pad. In the normal condition (N) as control, they conducted the same exercise protocol without cooling. Blood lactate concentration was significantly higher in C than N at 10 min after onset of exercise (4.0 ± 1.7 and 2.4 ± 1.2 mmol/L in C and N, P < 0.05). The percent change in the tissue oxygen saturation of the vastus lateralis, measured by a near‐infrared spectroscopy, was significantly lower in C at 2, 8, 10, and 20 min after the exercise onset compared with N (P < 0.05). The percent change in deoxy hemoglobin+myoglobin concentration (Deoxy[Hb+Mb]) showed a transient peak at the onset of exercise and significantly higher value in C at 10, 20, and 30 min after the exercise onset (P < 0.05). Compared to N, slower urn:x-wiley:2051817X:media:phy213910:phy213910-math-0002O2 kinetics (mean response time) was observed in C (45.6 ± 7.8 and 36.1 ± 7.7 sec in C and N, P < 0.05). The mean response time in C relative to N was significantly correlated with the transient peak of Deoxy[Hb+Mb] in C (r = 0.84, P < 0.05). These results suggest that lower oxygen delivery to the hypothermic skeletal muscle might induce greater glycolytic metabolism during exercise and slower urn:x-wiley:2051817X:media:phy213910:phy213910-math-0003O2 kinetics at the onset of exercise

Dynamic variation in cycling of hematopoietic stem cells in steady state and inflammation

Both fast-cycling and quiescent mouse hematopoietic stem cells (HSCs) can reconstitute lifelong hematopoiesis, and HSC cycling status can fluctuate over time in steady state and accelerate upon inflammation

Identification of genes potentially involved in supporting hematopoietic stem cell activity of stromal cell line MC3T3-G2/PA6

Although coculture of hematopoietic stem cells (HSCs) with stromal cells is a useful system to study hematopoiesis in the niche, little is known regarding the precise cellular and molecular mechanisms of maintaining HSCs through cell–cell interactions. The murine preadipose stromal cell line MC3T3-G2/PA6 (PA6) has been demonstrated to support HSCs in vitro. In this study, microarray analysis was performed on PA6 cells and HSC-nonsupporting PA6 subclone cells to identify genes responsible for supporting HSC activity. Comparison of gene expression profiles revealed that only 144 genes were down-regulated by more than twofold in PA6 subclone cells. Of these down-regulated genes, we selected 11 candidate genes and evaluated for the maintenance of HSC function by overexpressing these genes in PA6 subclone cells. One unknown gene, 1110007F12Rik (also named as Tmem140), which is predicted to encode an integral membrane protein, demonstrated a partial restoration of the defect in HSC-supporting activity