Abstract: High molecular weight linear poly(propylene fumarate) having a relatively low polydispersity index by utilizing a relatively pure intermediate and a method for making same. Fumaryl chloride and propylene glycol are reacted in the presence of potassium carbonate. The potassium carbonate present in the reaction solution prevents the acid by-product from catalyzing reactions at the fumarate double bond. The bis(propyl fumarate) produced according to this technique can be transesterified using conventional processing steps to yield P(PF). The P(PF) produced from bis(propyl fumarate) produced according to the present method has a higher molecular weight and is purer than P(PF) produced using previously known techniques.

Abstract: The present invention is for particulate compositions and methods for producing them that can absorb or scatter electromagnetic radiation. The particles are homogeneous in size and are comprised of a nonconducting inner layer that is surrounded by an electrically conducting material. The ratio of the thickness of the nonconducting layer to the thickness of the outer conducting shell is determinative of the wavelength of maximum absorbance or scattering of the particle. Unique solution phase methods for synthesizing the particles involve linking clusters of the conducting atoms, ions, or molecules to the nonconducting inner layer by linear molecules. This step can be followed by growth of the metal onto the clusters to form a coherent conducting shell that encapsulates the core.

Abstract: Heterogeneous solid supra-molecular alkylalumoxanes. A supra-molecular architecture of a nano-particle foundation on which an alkylalumoxane is built. Supra-molecular alkylalumoxanes comprise (a) an aluminum-oxide nanoparticle, (b) a linkage unit, and (c) an alkylalumoxane. Supra-molecular alkylalumoxanes are prepared by the reaction of a chemically modified aluminum-oxygen nanoparticle with either a pre-formed alkylalumoxane or an alkylaluminum compound, with subsequent hydrolysis or reaction with other alkylalumoxane yielding reagents. The supra-molecular alkylalumoxanes are active as catalysts for the polymerization of organic monomers and as co-catalysts with transition metal components for the polymerization of olefins.

Abstract: A system and method for determining transmission characteristics for a communications channel and for transmitting data on the communications channel. In one embodiment, the method starts by determining the channel's transfer function and determining interference characteristics for the channel. The interference characteristics preferably include transfer functions describing the channel's susceptibility to cross talk from neighboring channels. The channel transfer function and the interference characteristics are then examined and a transmit spectrum (or power spectral density function) is constructed for the channel. The transmit spectrum preferably uses orthogonal separation of upstream and downstream communications to increase channel capacity.

Abstract: Poly(ethylene glycol) (PEG), a highly biocompatible hydrophilic polyether, is tethered to poly(propylene fumarate) (PPF), a biodegradable polyester. To avoid change in molecular weight distribution of PPF, end hydroxyl groups of PPF are reacted with bis-carboxymethyl PEG after being treated with thionyl chloride. New end carboxyl groups of the PEG-tethered PPF are further reacted with N-hydroxysuccinimide (NHS) in the presence of dicyclohexylcarbodiimide (DCC) to couple bioactive molecules. Glutamine and glycine-arginine-glycine-aspartic acid (GRGD) are attached to the PEG-tethered PPF in 50 mM phosphate buffer of pH of 7.4. The method is valuable for the preparation of a triblock copolymer with PEG end blocks and the coupling of biologically active molecules.

Abstract: A method for controlling the gel point of a bone cement containing poly(polypropylene fumarate), a cross-linking monomer, an initiator, an inorganic filler, and a radical initiator. The gel point is controlled by varying the molecular weight of the poly(polypropylene fumarate) while maintaining the weight average molecular weight (M.sub.w) of the poly(polypropylene fumarate) above 2000 and the polydispersity index of the poly(polypropylene fumarate) below 2. In a preferred embodiment, the molecular weight of the poly(polypropylene fumarate) greater than 4000, and more preferably greater than 5000.

Abstract: An electromagnetic levitator is disclosed, comprising: a plurality of longitudinal sections formed from a conducting material and arranged around a longitudinal axis. The longitudinal sections are connected to a power source such that when the levitator is in operation, current flowing through adjacent longitudinal sections creates opposing magnetic fields. The levitator has first and second ends defining a levitation zone therebetween. When alternating current is passed through the conductors, a levitation tunnel is formed in the levitation zone, with the levitation tunnel having zero magnetic flux density along its center and non-zero magnetic flux density at all other points.