Cultured aortic smooth muscle cells (SMC) of diabetic rats and rabbits, which overexpress platelet-derived growth factor (PDGF) beta-receptor compared with controls, have a unique phenotype. In this study we report on the PDGF beta-receptor overexpression in aortas of diabetic animals and the increased intimal thickening of carotid arteries in diabetic rabbits after balloon catheter injury compared with that in controls. In diabetic aortas with no treatments of balloon catheter injury, intimal thickening was not observed in spite of the overexpression of PDGF beta-receptor, indicating that the growth property of medial SMC in diabetic aortas was changed before the intimal thickening could take place. PDGF is known to be the main contributor to the intimal thickening induced by balloon catheter injury, which is one of several forms of arterial injuries. Intimal thickening after balloon catheter injury in diabetic rabbits increased compared with that in controls. These results imply that PDGF beta-receptor overexpression of SMC in medial layers plays an important role in intimal thickening in the formation of advanced diabetic macroangiopathy.

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The mechanism determining heterointerface cross-sections is studied for GaAs ridge quantum wires (QWRs) grown by selective molecular beam epitaxy (MBE). Arrays of < 1 10>-and < 1 1 2>-orientated QWRs were grown on (001) and (111)B GaAs patterned substrates, respectively. A detailed investigation of cross-sections of wires has shown that the boundary planes appear on both sides of QWRs, keeping a constant angle, with respect to the flat top of the substrate pattern, and they determine the lateral wire width. Their evolution mechanism has turned out to be a kinetic process, reflecting differences in migration and atom incorporation rates on different facets. Simple formulas for have been derived, and they have shown excellent agreements with experiment. This has led to precise kinetic control of the wire width by growth conditions. PACS codes: 81.07.Vb, 81.16.Dn Keywords: selective growth, molecular beam epitaxy (MBE), patterned substrate, growth mechanism, GaAs *Corresponding author. Fax: +81-11-716-6004, e-mail: taketomo@rciqe.hokudai.ac.jp IntroductionSelective molecular beam epitaxy (MBE) / metal organic vapour phase epitaxy (MOVPE) of III-V semiconductor heterointerfaces on pre-patterned substrates is one of the most promising techniques for the formation of position-and size-controlled arrays of quantum wires (QWRs) and quantum dots (QDs) [1][2][3][4]. Recently, we have reported that < 1 10>-oriented QWRs can be successfully formed on (001) patterned substrates by a selective MBE growth for both and GaAs-based materials [6,7]. However, growth on non-planar substrates is complicated due to the simultaneous involvement of various high-index facets and related kinetic processes. Actually, the cross-sectional features of grown QWRs were quite different in various orientations of patterned substrates. For precise control of the feature size, proper understanding of the underlying growth mechanism for various crystal orientations is inevitable.The purpose of this paper is to clarify the mechanism which determines heterointerface cross-sections of GaAs ridge QWRs grown by selective MBE process. From a new understanding of the growth mechanism, precise control of the wire width has been realized for both < 1 10>-and < 1 1 2>-oriented wires grown on (001) and (111)B patterned substrates, respectively.

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In view of applications to hexagonal binary decision diagram (BDD) quantum circuits, the growth of hexagonal GaAs nanowire networks was attempted by selective molecular beam epitaxy (MBE) on (111)B prepatterned substrates. The basic feasibility of <112>-oriented straight nanowires was first investigated. GaAs nanowires were selectively formed on the top (111)B plane of AlGaAs mesa structures with high uniformity. The lateral width of the wires was determined by two facet boundary planes separating the growth regions on the top and the side facets of the mesa structures. The angle of the boundary planes remained constant during growth, resulting in the wire width being precisely controlled by the thickness of the AlGaAs barrier layer. Then, GaAs/AlGaAs hexagonal nanowire networks were grown on the patterned substrates consisting of three equivalent <112>-oriented wires for a (111)B plane. The results of detailed structural and optical studies showed that highly uniform and smoothly connected hexagonal nanowire networks having threefold symmetry were successfully fabricated by the present selective MBE growth technique.

Immobilization of TiO 2 -based photocatalysts usually suffers from lowered surface area and mass transfer limitation compared with their suspended counterpart. In this work, TiO 2 –SiO 2 monolithic photocatalysts having straight macropores, called microhoneycombs, were synthesized. The obtained samples had straight macropores with a diameter in the range of 15–40 μm formed by walls having a thickness up to 5 μm. The samples also contain micropores and small mesopores inside their walls, which contribute to high surface areas of more than 500 m 2 g –1 . Synthesized photocatalysts were tested in a continuous flow system using the decolorization of methylene blue as a model reaction. It was found that the unique morphology of the samples can be used to promote the uniform distribution of the target fluid while reducing the pressure drop across the photocatalyst to less than a hundredth compared with a packed bed system. In addition, calcination at 600–800 °C improved the strength and photocatalytic activity of the monoliths while preserving the high surface area of the samples.

It has been pointed out that hyperphosphorylation of microtubule-associated protein tau caused by stress might participate in the early stages of Alzheimer's disease pathogenesis. In the present study, we investigated the effects of cold water stress (CWS) on tau phosphorylation in the mouse hippocampus and the effects of GSK-3beta inhibitor, LiCl, on CWS-induced changes in tau phosphorylation levels by immunoblot analyses. CWS exposure caused an increase in tau phosphorylation at the Tau-1 (Ser199/202), AT8 (Ser202/Thr205) and Ser396 sites. CWS-induced changes in tau phosphorylation at the Ser199/202 and Ser396, but not at Ser202/Thr205, were significantly attenuated by LiCl pretreatment. Total tau levels also showed a decided tendency to increase after CWS, which tendency was also countered by LiCl. Finally, we showed that CWS increased the active form of GSK-3beta that was phosphorylated at Tyr216. These results suggest that a CWS-induced increase in phosphorylated tau in the hippocampus is mediated, at least partly, by the activation of GSK-3beta.

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