QCD with zero, two and four flavors of light quarks - results from QCDSP

We present the results from full QCD simulations with four flavors of light stag gered dynamical quarks on {\it {\it QCDSP}} supercomputer. Previous results are reproduced and the simulation reported here yields new results consistent with o ur previous runs. The hadron spectrum obtained with Wilson valence fermions reported here will allow us to determine if our earlier conclusions are independent of lattice form alism

Status of the QCDSP project

We describe the completed 8,192-node, 0.4Tflops machine at Columbia as well as the 12,288-node, 0.6Tflops machine assembled at the RIKEN Brookhaven Research Center. Present performance as well as our experience in commissioning these large machines is presented. We outline our on-going physics program and explain how the configuration of the machine is varied to support a wide range of lattice QCD problems, requiring a variety of machine sizes. Finally a brief discussion is given of future prospects for large-scale lattice QCD machines.Comment: LATTICE98(machines), 3 pages, 1 picture, 1 figur

Structure transition from hexagonal mesostructured rodlike silica to multilamellar vesicles

We studied the synthesis of siliceous structures by using a nonionic block copolymer (Pluronic P123) and perfluorooctanoic acid (PFOA) as cotemplates in an acid-catalyzed sol-gel process. Different siliceous structures were obtained through systematically varying the molar ratio (R) of PFOA/P123, and the resultant materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen sorption analysis, and Fourier-transform infrared spectroscopy. The results are consistent and reveal a structure transition from a highly ordered 2D hexagonal (HEX) mesostructure with a rodlike morphology to multilamellar vesicles (MLVs) with sharp edges when R is increased. The fact that the MLVs are initiated from the end of hexagonally mesostructured rods provides key evidence in such a novel structure transition. Our finding indicates that, at least in our observations, the MLVs are developed gradually from HEX structures, rather than by a direct cooperative self-assembly mechanism. It is suggested that PFOA molecules with rigid fluorocarbon chains closely interact with PEO. This interaction model may well explain (1) the "wall-thicken" effect in HEX mesostructures by enlarging the hydrophilic PEO moiety (R = 0-1.4), (2) the subsequent HEX to multilamellar structure transition by modifying the hydrophilic/hydrophobic volume ratio (R = 1.4-2.8), and (3) the formation of MLVs with sharp edges by increasing the bending energy. This model provides insight into the fabrication of novel porous materials by the use of block copolymers and fluorinated surfactant mixed templates

On the origin of helical mesostructures

The investigation on the formation mechanism of helical structures and the synthesis of helical materials is attractive for scientists in different fields. Here we report the synthesis of helical mesoporous materials with chiral channels in the presence of achiral surfactants. More importantly, we suggest a simple and purely interfacial interaction mechanism to explain the spontaneous formation of helical mesostructures. Unlike the proposed model for the formation of helical molecular chains or surpramolecular packing based on the geometrically motivated model or the entropically driven model, the origin of the helical mesostructured materials may be attributed to a morphological transformation accompanied by a reduction in surface free energy. After the helical morphology is formed, the increase in bending energy together with the derivation from a perfect hexagonal mesostructure may limit the curvature of helices. Our model may be general and important in the designed synthesis of helical mesoporous materials

Effects of Low Molecular Weight Yeast β-Glucan on Antioxidant and Immunological Activities in Mice

To evaluate the antioxidant and immune effects of low molecular yeast β-glucan on mice, three sulfated glucans from Saccharomyces cerevisiae (sGSCs) with different molecular weight (MW) and degrees of sulfation (DS) were prepared. The structures of the sGSCs were analyzed through high performance liquid chromatography-gel permeation chromatography (HPLC-GPC) and Fourier transform infrared spectroscopy (FTIR). sGSC1, sGSC2, and sGSC3 had MW of 12.9, 16.5 and 19.2 kDa, respectively, and DS of 0.16, 0.24 and 0.27, respectively. In vitro and in vivo experiments were conducted to evaluate the antioxidant and immunological activities of the sGSCs. In vitro experiment, the reactive oxygen species (ROS) scavenging activities were determined. In vivo experiment, 50 male BALB/c mice were divided into five groups. The sGSC1, sGSC2 and sGSC3 treatment groups received the corresponding sGSCs at 50 mg/kg/day each. The GSC (glucans from Saccharomyces cerevisiae) treatment group received 50 mg/kg/day GSC. The normal control group received equal volume of physiological saline solution. All treatments were administered intragastrically for 14 day. Results showed that sGSC1, sGSC2 and sGSC3 can scavenge 1,1-diphenyl-2-picryl-hydrazyl (DPPH), superoxide, and hydroxyl radicals in vitro. The strength of the radical scavenging effects of the sGSCs was in the order of sGSC1 > sGSC2 > sGSC3. Oral administration of sGSC1 significantly improved serum catalase (CAT) and glutathione peroxidase (GSH-Px) activities and decreased malondialdehyde (MDA) level in mice. sGSC1 significantly improved the spleen and thymus indexes and the lymphocyte proliferation, effectively enhanced the percentage of CD4+ T cells, decreased the percentage of CD8+ T cells, and elevated the CD4+/CD8+ ratio. sGSC1 significantly promoted the secretion of IL-2 and IFN-γ. These results indicate that sGSC1 with low MW and DS has better antioxidant and immunological activities than the other sGSCs, and sGSC1 could be used as a new antioxidant and immune-enhancing agent