The extended loop group: An infinite dimensional manifold associated with the loop space

A set of coordinates in the non-parametric loop-space is introduced. We show that these coordinates transform under infinite dimensional linear representations of the diffeomorphism group. An extension of the group of loops in terms of these objects is proposed. The enlarged group behaves locally as an infinite dimensional Lie group. Ordinary loops form a subgroup of this group. The algebraic properties of this new mathematical structure are analyzed in detail. Applications of the formalism to field theory, quantum gravity and knot theory are considered.     

Proper holomorphic mappings between some nonsmooth domains

Sunto In questo lavoro si studia il problema dell'existenza o meno di mappe olomorfe proprie, F: (p,q) (pq) dove (,) Cⁿ sono domini limitati, pseudoconvessi, non lisci, di Reinhardt con centro di simmetria sulla frontiera (per la definizione v. (2), introduzione). In caso affermativo si fornisee esplicitamente l'espressione di tali mappe (v, teoremi I e II nell'introduzione).

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The author, during the redaction of this paper, was supported by MPI (40% and 60%) funds.     

Blocking sets in 3-designs

We characterize the existence of blocking sets in a particular class of S (3,4,v) and we give a construction to obtain S(3,4,2v) having blocking sets.Lavoro eseguito nell'ambito del GNSAGA e con contributo del M.P.I.     

Equazioni ellittiche del secondo ordine di tipo non variazionale in aperti non limitati

Summary In this paper we study the Dirichlet problem, for second order, linear elliptic partial differential equations with discontinuous coefficients in unbounded domains. We obtain some results about existence and uniqueness of the solution in W²().

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Lavoro eseguito nell'ambito del G.N.A.F.A. del C.N.R.     

The Smoluchowski limit for a simple mechanical model

We consider a vertical stick constantly accelerated along thex-axis by a forceF and which elastically collides with point particles of the same mass (atoms). The atoms are initially Poisson distributed and are allowed to have four velocities only. It is shown that under suitable scaling of the system the displacementQ(t) of the stick satisfies a nontrivial CLT:Q(t)=vFt+D ^1/2 W(t) (Smoluchowski equation), where the values ofv andD depend on the fact that one atom may collide several times.     

Preparation of Nanoelectrode Ensembles by Assembly of Nano—Silver Colloid on Gold Surface

A novel method for preparing silver nanoelectrode ensembles(SNEEs) and gold nanoelectrode ensembles (GNEEs) has been developed. Silver colloid particles were first absorbed to the gold electrode surface to form a monolayer silver colloid. N-hexadecyl nercaptan was then assembled on the electrode to form a thoil monolayer on which hydrophilic ions cannot be transfered. The SNEEs was prepared by removing thiol from silver colloid surface through applying and AC voltage with increasing frequency at 0.20V(vs.SCE). Finally,GNEEs was obtained by immersing a SNEEs into 6 mol/L HNO3 to remove the silver colloid particles. By comparison with other methods such as template method ect., this method enjoys some advantages of lower resistance, same diameter,easy preparation,controllable size and density.     

立方介孔相含钇氧化硅的合成与表征

以低浓度的十六烷基三甲基溴化铵为结构导向剂,在碱性条件下通过水热法合成了具有立方结构的含钇Y MCM 48介孔分子筛材料。XRD测试表明当Y/Si<0.05时可以获得典型的长程有序介孔立方结构相,随Y/Si比的增加,晶胞参数的增大和红外吸收光谱(FTIR)的变化为Y进入介孔分子筛骨架中提供了有力证据。N2吸附-脱附实验给出这种立方介孔材料的BET表面积为1180m2·g-1,BJH平均孔径为3.4nm。紫外 可见漫反射光谱(UV vis)证明钇以一种六配位的形式存在。X射线光电子能谱(XPS)进一步证明钇以三价形式存在于立方介孔分子筛骨架中。     

The behaviour of alkylcobalt carbonyls under “oxo” conditions

Both normal and secondary alkylcobalt carbonyls are shown not to undergo isomerization under catalytic “oxo” conditions, and the relevance of this obervation for the mechanism of the “oxo” reaction is discussed.     

三甘氨酸双11钨硅双核稀土杂多配合物的合成与性质

利用一缺位杂多酸对一维链式配合物的断链取代反应,合成了未见文献报道的以甘氨酸为桥联配体的双核稀土杂多配合物,其结构简式为K₁₀[(O₃₉W₁₁Si)RE(Gly)₃RE(SiW₁₁O₃₉)]·9H₂O(RE=La,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Y;Gly=NH₃⁺CH₂COO<