The conduction and valence band edges for electronic band gaps and Fermi levels are determined for Ta2O5, TaON, and Ta3N5 by ultraviolet photoelectron spectroscopy (UPS) and electrochemical analyses. Reasonable agreement between the results of the two methods is obtained at the pH at which the ζ potentials of the particles are zero. The tops of the valence bands are found to be shifted to higher potential energies on the order Ta2O5 < TaON < Ta3N5, whereas the bottoms of the conduction bands are very similar in the range −0.3 to −0.5 V (vs NHE at pH = 0). From the results, it is concluded that TaON and Ta3N5 are promixing catalysts for the reduction and oxidation of water using visible light in the ranges λ < 520 nm and λ < 600 nm, respectively. It is also demonstrated that the proposed UPS technique is a reliable alternative to electrochemical analyses for determining the absolute band gap positions for materials in aqueous solutions that would otherwise be difficult to measure using electrochemical methods.

PIP 3 BP is a phosphatidylinositol 3,4,5-trisphosphatebinding protein (PIP 3 BP) abundant in brain, containing a zinc finger motif and two pleckstrin homology (PH) domains. Staining of rat brain cells with anti-PIP 3 BP antibody and determination of localization of PIP 3 BP fused to the green fluorescent protein (GFP-PIP 3 BP) revealed that PIP 3 BP was targeted to the nucleus. Targeting was dependent on a putative nuclear localization signal in PIP 3 BP. Generation of PIP 3 in the nucleus was detected in H 2 O 2 -treated 293T cells, nerve growth factor (NGF)-treated PC12 cells, and platelet-derived growth factor (PDGF)-treated NIH 3T3 cells. Translocation of phosphatidylinositol 3-kinase (PI 3-kinase) to the nucleus and enhanced activity of PI 3-kinase in the nucleus fraction were observed after H 2 O 2 treatment of 293T cells, suggesting that PI 3-kinase can be activated in the nucleus as well as in the membrane after appropriate stimulation of the cells. Co-expression of the constitutively active PI 3-kinase with PIP 3 BP resulted in exportation of the protein from the nucleus to the cytoplasm, suggesting that PIP 3 BP can function as a PIP 3 -binding protein in the intact cells. These results imply that there may be an unknown function of PI 3-kinase in the nucleus.Phosphatidylinositol 3-kinase 1 is an enzyme that is activated immediately after growth factor or differentiation factor stimulation of the cells (1) and that generates second messengers, phosphatidylinositol 3,4,5-trisphosphate (PIP 3 ) and phosphatidylinositol 3,4-bisphosphate (PI 3,4-P 2 ) (2-5). These 3Ј-phosphorylated phosphoinositides can activate serine, threonine kinases such as PKB/Akt, PKCs, and PDKs (6 -9). They are also suggested to be involved in other events such as rearrangement of cytoskeleton and vesicle transport because these phenomena are sensitive to the PI 3-kinase inhibitors and dominant negative mutants of PI 3-kinase (10). Recently, it was reported that the 3Ј-phosphorylated phosphoinositides can activate guanine nucleotide exchanging factors of Rac and Arf, small G proteins involved in actin rearrangement and vesicle transport, respectively (11,12). Therefore, G proteins as well as kinases are downstream of PI 3-kinase.We have identified PIP 3 BP as a PIP 3 -binding protein, using a PIP 3 analogue column (13). It is abundant in brain, implying that it may be involved in the function of nerve systems. PIP 3 BP binds to PIP 3 but not to PI 3,4-P 2 or phosphatidylinositol 4,5-bisphosphate (PI 4,5-P 2 ). It has a zinc finger motif homologous to that of Arf-GTPase activating protein (GAP) and two PH domains. Both PH domains are shown to be involved in binding to PIP 3 . Another PIP 3 -binding protein, centaurin ␣, is highly homologous to PIP 3 BP (14). No GAP activity to Arf has been detected in either protein. Although the binding of centaurin ␣ and PIP 3 BP to PIP 3 was specific, the role of the protein is unclear. To address this question, we determined the intracellular localization by immunological techniques, using mono...

The band gap positions of the title compounds are determined by electrochemical analysis and UV photoelectron spectroscopy (UPS). The conduction band positions of the compounds are largely similar, whereas the valence band positions vary significantly (Ta 2 O 5 < TaON < Ta 3 N 5 ). The results indicate that TaON and Ta 3 N 5 are potential photocatalysts for overall water splitting utilizing solar radiation. The results of UPS are in good agreement with the electrochemical analysis, demonstrating that UPS is a reliable alternative method of determining the band positions of a wide range of photocatalytic materials. -(CHUN, W.-J.; ISHIKAWA, A.; FUJISAWA, H.; TAKATA, T.; KONDO, J. N.; HARA, M.; KAWAI, M.; MATSUMOTO, Y.; DOMEN*, K.; J.

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Angle-resolved photoemission measurements have been performed on Sr 14 Cu 24 O 41 which consists of twoleg Cu 2 O 3 ladders and edge-sharing CuO 2 chains. The data are consistent with the existence of a dispersive band near the Fermi level which has the periodicity of the ladder sublattice. The band shows a minimum binding energy at kaϭ(2nϩ1)/2, suggesting that a Mott-Hubbard gap opens on the ladder. The experimental result shows a qualitative agreement with the t-J ladder calculation. It was also found that replacement of Sr with Ca causes a transfer of holes from the chain to the ladder. ͓S0163-1829͑97͒05137-0͔

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We study the magnetic structure of perpendicularly magnetized Fe nanowires grown on Au͑788͒ by means of x-ray magnetic circular dichroism. The average size of ferromagnetic domains in the nanowires exponentially decreases with temperature, leading to a steeper decay in magnetization compared to nanoislands of Fe. The temperature dependence of magnetization and domain structures can be well described in terms of local atomic geometry, the number of atomic chains in nanowires, exchange coupling between adjacent spins, and magnetic anisotropy. The nonlinear coverage dependence of the activation energy for the creation of magnetic domains can be explained by overall shape of nanowires, which also implies that the magnetic switching processes are strongly shape dependent at the nanoscale.