Synthesis of Fullerene Derivatives for Incorporation in Sol-Gel Glasses

We report on the synthesis of fullerene derivatives containing a trialkoxysilane moiety that exhibit enhanced solubility in solvents commonly used for sol-gel processing. These derivatives have been successfully embedded in glassy bulk samples and thin films that show very promising optical limiting properties.     

7‐Chloro‐3,6‐di­methyl‐1H‐indene‐2‐carb­aldehyde

In the crystal structure of C₁₂H₁₁ClO, the (planar) mol­ecules give rise to a parallel packing. A model crystal obtained by semi‐empirical and packing‐energy calculations is consistent with the observed structure.     

Hexayne Amphiphiles and Bolaamphiphiles

Oligoynes with two or more conjugated carbon–carbon triple bonds are useful precursors for carbon-rich nanomaterials. However, their range of applications has so far been severely limited by the challenging syntheses, particularly in the case of oligoynes with functional groups. Here, we report a universal synthetic approach towards both symmetric and unsymmetric, functionalized hexaynes through the use of a modified Eglinton–Galbraith coupling and a sacrificial building block. We demonstrate the versatility of this approach by preparing hexaynes functionalized with phosphonic acid, carboxylic acid, ammonium, or thiol head groups, which serve as neutral, cationogenic, or anionogenic interfacially active groups. We show that these hexaynes are carbon-rich amphiphiles or bolaamphiphiles that self-assemble at liquid–liquid interfaces, on solid surfaces, as well as in aqueous media.     

SAXS study of the structure of amorphous Fe75TM5B20 (TM  Ti,V, Cr,Mn, Fe,Co, Ni)

A SAXS study was undertaken on Fe₇₅TM₅B₂₀ amorphous alloys (TM  Ti, V, Cr, Mn, Fe, Co, Ni) to prove the effects of the substituting metals on structural homogeneity of the systems. A density-density correlation extending up to 20 Å belongs to Fe-, Ni- and Co-containing alloys whereas the absence of a medium-range order characterizes the texture of the remaining alloys. A net correspondence was found between these structural conditions and the isothermal behavior of the resistivity.     

Binding sites for SiH2/Si(0 0 1): A combined ab initio, tight-binding, and classical investigation

Binding sites for SiH₂ on Si(0 0 1) are investigated theoretically by using several different methods. Possible local minima are first sampled by classical molecular dynamics simulations of the SiH₂/Si(0 0 1) impact, allowing for a preliminary, fast selection. A further refinement is carried out by geometry optimizations using semiempirical tight-binding and density functional theory calculations, based on both the local density and generalized gradient approximations. In most cases only minor morphological changes are obtained when comparing the ab initio sites with the classical potentials and tight-binding ones. The purely classical treatments here tested, however, overestimate the number of minima and fail in accurately reproducing the relative energy of some of the adsorption sites. Closer agreement is obtained with tight-binding, with the noticeable exception of the lowest ab initio minimum (on-dimer site).     

Quantum gravity,random geometry and critical phenomena

We discuss the theory of non-critical strings with extrinsic curvature embedded in a target space dimensiond greater than one. We emphasize the analogy between 2d gravity coupled to matter and non self-avoiding liquid-like membranes with bending rigidity. We first outline the exact solution for strings in dimensionsd<1 via the double scaling limit of matrix models and then discuss the difficulties of an extension tod>1. Evidence from recent and ongoing numerical simulations of dynamically triangulated random surfaces indicate that there is a non-trivial crossover from a crumpled to an extended surface as the bending rigidity is increased. If the cross-over is a true second order phase transition corresponding to a critical point there is the exciting possibility of obtaining a well defined continuum string theory ford>1. This essay received the third award from the Gravity Research Foundation, 1992-Ed.     

A class of strongly nonlinear functional differential equations

Let H be a real Hilbert space, :H [0, + ] a proper l.s.c., convex function with L_k:={u H; u² + (u) k} compact for every k > 0, let > 0 be a given constant and . We prove an existence result for strong solutions to a class of functional differential equations of the form

Alcune probabilità geometriche di reticoli nel piano

We consider, on the euclidean planeE ₂, a lattice of fundamental regions that are regular polygons, triangles or parallelograms. We determin the probabilityp in order that a vertex of the latticeR belongs to a circle of the random center and any radius.