A new subcontinuum of

We present a method for describing all indecomposable subcontinua of . This method enables us to construct in a new subcontinuum of .

We also show that the nontrivial layers of standard subcontinua can be described by our method. This allows us to construct a layer with a proper dense -subset and bring the number of (known) nonhomeomorphic subcontinua of to 14.

     

A separable non-remainder of

We prove that there is a compact separable continuum that (consistently) is not a remainder of the real line.

     

Measurements of the generalized electric and magnetic polarizabilities of the proton at low Q2 using the virtual-compton-scattering reaction

The mean square polarizability radii of the proton have been measured for the first time in a virtual-Compton-scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities obtained from a dispersion analysis of the data at Q2 = 0.057 GeV2/c2 are in agreement with O(p3) heavy baryon chiral perturbation theory. The data support the dominance of mesonic effects in the polarizabilities.     

ω* has (almost) no continuous images

We prove that the following statement follows from the Open Colouring Axiom (OCA): ifX is locally compactσ-compact but not compact and if its Čech-Stone remainderX* is a continuous image ofω*, thenX is the union ofω and a compact set. It follows that the remainders of familiar spaces like the real line or the sum of countably many Cantor sets need not be continuous images ofω*.     

Hydroxyl-directed hydrogenation of homoallylic alcohols. Effects of achiral and chiral rhodium catalysts on 1,3 stereocontrol.

The hydroxyl-directed hydrogenation of homoallylic alcohols is examined with cationic rhodium-(I) and iridium-(I) catalysts. These reactions proceed with high levels of diastereoselection when either Rh(Diphos)⁺ or Ir(pry)Pcy₃⁺ are employed as catalysts.     

Chromocene catalysts for ethylene polymerization: Scope of the polymerization

Chromocene deposited on silica supports of high surface area forms a highly active catalyst for polymerization of ethylene. Polymerization is believed to occur by a coordinated anionic mechanism previously outlined. The catalyst formation step liberates cyclopentadiene and leads to a new divalent chromium species containing a cyclopentadienyl ligand. The catalyst has a very high chain-transfer response to hydrogen which permits facile preparation of a full range of molecular weights. Catalyst activity increases with an increase in silica dehydration temperature, chromium content on silica, and ethylene reaction pressure. The temperature-activity profile is characterized by a maximum near 60°C, presumably caused by a deactivation mechanism involving silica hydroxyl groups. A value of 72 was estimated for the ethylene–propylene reactivity ratio (r₁). Linear, highly saturated polymers are normally prepared below 100°C. By contrast with other commercial polyethylenes, the chromocene catalyst produces polyethylenes of relatively narrow molecular weight distribution. Above 100°C, unsaturated, branched polymers or oligomers are formed by a simultaneous polymerization–isomerization process.