A note on the two symmetry-preserving covering maps of the gyroid minimal surface

Our study of the gyroid minimal surface has revealed that there are two distinct covering maps from the hyperbolic plane onto the surface that respect its intrinsic symmetries. We show that if a decoration of is chiral, the projection of this pattern via the two covering maps gives rise to distinct structures in .     

Some novel three-dimensional Euclidean crystalline networks derived from two-dimensional hyperbolic tilings

We demonstrate the usefulness of two-dimensional hyperbolic geometry as a tool to generate three-dimensional Euclidean (E³) networks. The technique involves projection of edges of tilings of the hyperbolic plane (H²) onto three-periodic minimal surfaces, embedded in E³. Given the extraordinary wealth of symmetries commensurate with H², we can generate networks in E³ that are difficult to construct otherwise. In particular, we form four-, five- and seven-connected (E³) nets containing three- and five-rings, viz. (3, 7), (5, 4) and (5, 5) tilings in H². Received 14 January 2002 / Received in final form 12 August 2002 Published online 4 February 2003 RID="a" ID="a"e-mail: stephen.hyde@anu.edu.au     

ON THE BEHAVIOR OF PHASE TRANSITION SHOWN IN DISASSYMBLY PROCESSES OF VERY HOT AND DILUTE FINITE NUCLEAR SYSTEMS

The behaviors of phase transition shown in disassymbly processes of very hot and dilute finite nuclear system have been exposed by using canonical (microcanonical) ensemble Monte Carlo simulation.It is explained that they result from the competition between Coulomb interaction and the effect of finiteness.     

燃烧法制备纳米CdFe2O4及表征

以Fe（NO3）3.9H2O和Cd（NO3）2.4H2O为原料,以柠檬酸为还原剂,采用燃烧法制备了CdFe2O4纳米粉体,用X射线粉末衍射仪（XRD）、透射电子显微镜（TEM）、红外光谱（IR）和振动样品磁强计（VSM）等手段对样品进行了表征,结果表明,样品为尖晶石型铁酸镉纳米粉体,其粒径大约为20—50nm,且具有超顺磁性。     

Charge fluctuations in Au+Au collisions at RHIC energy

A hadron and string cascade model, JPCIAE, together with the corresponding Monte Carlo event generator, has been employed in this paper to investigate further the charge fluctuations in Au+Au collisions at Snn = 130 GeV. The default JPCIAE calculations are in good agreement with PHENIX and STAR data. We found that the thermal predictions for the π gas, the resonance π gas and quark matter deviate, respectively, from the corresponding dynamical simulations from the JPCIAE model. The discrepancies were also found between the π charge fluctuations and the charge fluctuations of all species of hadrons. However the charge fluctuations for "π from ρ and ω decay" and for all the hadrons from resonance decay are close to each other, indicating the correlation between positively and negatively charged hadrons is not sensitive to the species of hadrons. This work shows further that it is questionable to use the charge fluctuations as a signature of QGP.     

催化光度法测定痕量钒——钒(Ⅴ)-溴甲酚紫-过氧化氢体系

催化光度法测定钒已有报道[1～3],在0.45 mol·L-1磷酸介质及加热条件下,过氧化氢氧化溴甲酚紫褪色反应非常缓慢,而痕量钒对此反应具有较高的催化活性,且在一定浓度范围内,钒量与褪色反应程度呈线性关系,据此可建立测定痕量钒的方法.方法的检出限为1.9×10-6g·L-1,测定范围为0.003～1.8 mg·L-1.方法操作简便,重现性好,用于钢样中痕量钒的测定,结果满意.     

Oxidation of N-substituted dopamine derivatives: irreversible formation of a spirocyclic product

Oxidation of amide, urea and guanidinium derivatives of dopamine gives relatively stable ortho-quinones whereas oxidation of corresponding thioamide and amidinium derivatives rapidly and quantitatively gives novel bicyclic and spirocyclic products formed via the corresponding ortho-quinone.