Transient studies of carbon monoxide oxidation over platinum catalyst

The applicability of transient techniques to the study of the catalytic oxidation of carbon monoxide is discussed. It is shown that at 100–150°C adsorption and desorption equilibria between the gas phase and catalyst cannot be assumed, and an elementary step formulation may be used to predict both multiple steady states and transient behaviour.     

Introduction to Session 3

Applied Biochemistry and Biotechnology -     

Cell decomposition of polytopes by bending

If a lineL crosses a polygonP, then bendingP up on both sides ofL yields a 3-polytope whose “upper” boundary projects back to a cell decomposition ofP transverse toL, and to a triangulation in the general case. We generalize this simple idea to polytopes of arbitrary dimension, and use it to answer several questions posed recently about possible decompositions of polytopes and of regions between polytopes. Supported in part by NSF grant DMS-8501492 and PSC-CUNY grant 666426. Supported in part by Courant Institute (NYU) and Hungarian NFSR grant 1812.     

Kinetics of the gas-phase reactions of NO3 radicals with a series of alkynes,haloalkenes, and α,β-unsaturated aldehydes

Rate constants for the gas-phase reactions of NO₃ radicals with a series of alkynes, haloalkenes, and α,β-unsaturated aldehydes have been determined at 298 ± 2 K using a relative rate technique. Using rate constants for the reactions of NO₃ radicals with ethene and propene of (1.1 ± 0.5) × 10^?16 cm³ molecule^?1 s^?1 and (7.5 ± 1.6) × 10^?15 cm³ molecule^?1 s^?1, respectively, the following rate constants (in units of 10^?16 cm³ molecule^?1 s^?1) were obtained: acetylene, ≤0.23; propyne, 0.94 ± 0.44; vinyl chloride, 2.3 ± 1.1; 1,1-dichloroethene, 6.6 ± 3.1; cis-1,2-dichloroethene, 0.75 ± 0.35; trans-1,2-dichloroethene, 0.57 ± 0.27; trichloroethene, 1.5 ± 0.7; tetrachloroethene, <0.4; allyl chloride, 2.9 ± 1.3; acrolein, 5.9 ± 2.8; and crotonaldehyde, 41 ± 9. The atmospheric implications of these data are discussed.     

Adsorption spectroscopy by polariton-induced desorption (ASPID)

A new spectroscopic technique is proposed as a means of determining the energy and momentum of adsorbed atoms and molecules. The method, abbreviated to ASPID (adsorption spectroscopy by polariton-induced desorption), uses surface phonon polaritons (SPPs) to desorb atoms. Because one may create nearly-monoenergetic SPPs, the binding energy range is determined directly from the spectrum of final energies. A kinematical analysis may be used to analyze adatom momenta, and hence band structures. The angular distribution of the SPP-desorbed atoms may be used to monitor adsorbed-film temperature. We provide an estimate of the SPP desorption rate, and conclude that the proposed experiment is feasible.     

Copolyesteramides—I. Anionic copolymers of ω-laurolactam with ϵ-caprolactone

Anionic copolymerisation of ω-laurolactam with ε-caprolactone yields copolyesteramides with NH(CH₂)₁₁CO and O(CH₂)₅CO unit contents similar to those in the feeds. Over the major part of the composition range, only the amide component crystallises, showing the γ-nylon 12 form. A transition of crystalline type to that of poly(ε-caprolactone) occurs at low (ca. 20 mol%) amide-group content and with marked depression of the degree of crystallinity of the polyester component. I.R. spectroscopy indicates the co-existence of amide-ester with amide-amide hydrogen-bonding in the copolymers, and the monotonic form of the T_m vs composition curve is explained in terms of this dual bonding. It is suggested that such interactions between the sub-species may be a general feature underlying the properties of linear aliphatic copolyesteramides.     

Polynomial realization of pseudoline arrangements

An arrangement of pseudolines is called d-stretchable if it is isomorphic to an arrangement of graphs of polynomial functions, each of degree at most d; in particular, it is 1-stretchable (classically: “stretchable”) if and only if it is isomorphic to an arrangement of lines. We show that (i) if every arrangement of n pseudolines is d-stretchable, then d ≦ cn^1/2, and (ii) every arrangement of n pseudolines is d-stretchable with d = cn².