An outdoor smog chamber and modeling study of toluene–NOx photooxidation

An experimental investigation of the gas-phase photooxidation of toluene–NO_x–air mixtures at part-per-million concentrations has been carried out in a 65-m³, outdoor smog chamber to assess our understanding of the atmospheric chemistry of toluene. In addition, six CO? NO_x–air irradiations were conducted to characterize the chamber with regard to any wall radical sources. Measured parameters in the toluene–NO_x experiments included O₃, NO, NO₂, HNO₃, peroxyacetyl nitrate (PAN), CO, toluene, benzaldehyde, o-cresol, m-nitrotoluene, peroxybenzoyl nitrate (PBZN), temperature, relative humidity, aerosol size distributions, and particulate organic carbon. Predictions of the reaction mechanism of Leone and Seinfeld [7] are found to be in good agreement with the data under a variety of initial conditions. Additional simulations are used to investigate various mechanistic pathways in areas where our understanding of toluene chemistry is still incomplete.     

Stability and equilibrium states

For an infinite dynamical quantum system idealized as aC*-algebra acted upon by time-translations automorphisms in an asymptotically abelian way, we propose to characterize equilibrium states by the three properties of stationarity, stability for local perturbations of the dynamics, and relative purity. We show that a state with these properties either gives rise to a one-sided energy spectrum or is a KMS- (i.e. essentially a limit Gibbs-) state.     

Some Optimization Problems with Bulk-Service Queues

An optimal control problem for a single bulk-service queue is considered. Theorems that characterize the optimal control strategy in some circumstances are proved; they complement earlier results by Deb and Serfozo for a comparable problem. Most of the analysis uses direct probabilistic reasoning rather than specialized methods such as dynamic programming. Some illustrative examples are presented.     

Theory of quasimagnetic impurity in a metal: An exactly soluble model of interacting electrons

We study an impurity atom, on which two-body forces are important, dissolved in a metal, where they are negligible. With the aid of the well-known boson excitation spectrum of the electronic Fermi sea, we predict the low-energy effects of one- and two-body potentials on the impurity, in the nonmagnetic regime. We obtain for the first time exact expressions for the cutoff independent contributions to the specific heat and paramagnetic susceptibility, the spectral amplitudes or one-electron density of states on the impurity, and the scattering cross-section. The entire spectrum of manybody eigenstates is explicitly obtained. The onset of a local magnetic moment appears as a sudden breakdown of the model Hamiltonian, and occurs when the two-body potential exceeds a critical value U_c which is O(E_F) in magnitude. A study of the renormalization of the interaction parameters terminates the paper.     

The reactions of O(3P) with ozone and carbonyl sulfide

The competitive reactions between 2-trifluoromethylpropene (TMP) and OCS for O(³P) atoms were studied between 300° and 523°K, using the mercury-senstitized photolysis of N₂O as a source of O(³P). From the known value for the rate constant of the O(³P) + TMP reaction, k₃ was found to be 1.6 × 10^?11 exp (?4500/RT) cm³/particle-sec, where reaction (3) is Mixtures of O₃ and OCS were photolyzed at 197°, 228°, 273°, and 299°K with radiation above 4300 Å to produce O(³P) from the photolysis of O₃, and thus study the competition between reaction (3) and From the above value of k₃, k₁ could be computed. When combined with all the previous data, the best espression for k₁ is k₁ = 1.2 × 10^?11 exp (?4300/RT) cm³/particle-sec.     

5-nitro-2-thienylvinylation. Nucleophilic substitution on 2-(2-bromovinyl)-5-nitrothiophene,new one-step method for preparation of new biologically active ethylenic derivatives of 5-nitro--2-thiophene

A facile method for preparing 2-(2-X-vinyl)-5-nitrothiophene has been established by the reaction of (Z)-2-(2-bromovinyl)-5-nitrothiophene with O, S and N nucleophiles.     

On minimizing expected absorption times

A random walk with variable step size, depending on the location of the particle, is considered. Two cases are discussed: one with two absorbing boundaries, and another when one boundary is absorbing while the other cannot be reached. Generalization of the uniquess problem of a functional equation for the expected duration is proved. Also the optimal policy, i.e. step size for each location minimizing the expected duration, is discussed. The natural solution of the problem in case of two absorbing boundaries is verified, while for the case of one boundary a necessary and sufficient condition for the existence of optimal solution is developed, while specific policy still remains open.