Radiotracer Studies of the Nickel Catalysed Hydrogenation of Acetylene

The adsorption of acetylene on silica-supported nickel has teen investigated using a [14C]radiotracer technique. It has been found that the acetylene adsorption isotherms have two regions, a steep primary region and a linear secondary region. From the amount of ethane formed during the primary adsorption of acetylene, the average composition of the primary region has been calculated to be C2H1.9 indicating that the species adsorbed on the primary region are predominantly dissociatively adsorbed. Evidence has been obtained to show that the species involved in actual catalytic turnover during a hydrogenation reaction are located on the secondary region

Weak helix submanifolds of euclidean spaces

It is shown that there exist nonstrong weak 2-helix surfaces of R

Interdependent Pricing and Markup Behavior: An Empirical Analysis of GM, Ford and Chrysler

Our purpose in this paper is to develop and estimate a model of the US automobile industry that can be used to analyze the secular and cyclical strategic markup behavior and market structure of its three major domestic producers - - GM, Ford and Chrysler. The principal novelty in this paper is not such much in the underlying theory (we build on what Timothy Bresnahan has called the "new empirical industrial organization" literature), but rather in the actual empirical implementation of a multi-equation model sufficiently general to permit the testing of a variety of specific behavioral postulates associated with the interdependent strategic profit-maximizing behavior of GM, Ford and Chrysler. Using firm-specific annual data from 1959-83, we find that at usual levels of statistical significance, we cannot reject Cournot quantity-setting behavior, nor can we reject leader/follower quantity-setting behavior with GM as leader and Ford and Chrysler as followers; the parameter restrictions associated with leader/follower behavior are slightly more binding than those with Cournot, although the difference is not decisive. In terms of the cyclical analysis of market behavior, our most striking result is the great diversity of behavior we find among GM, Ford and Chrysler. Depending on which firm is being analyzed, there is support for the pro-cyclical "conventional wisdom" of markups (GM and Ford), as well as for the counter-cyclical "revisionist" literature (Chrysler). Diversity, rather than constancy and homogeneity, best characterizes firms in this industry.

Decoherence and Entropy Production in Relativistic Nuclear Collisions

Short thermalization times of less than 1 fm/c for quark and gluon matter have been suggested by recent experiments at the Relativistic Heavy Ion Collider (RHIC). It has been difficult to justify this rapid thermalization in first-principle calculations based on perturbation theory or the color glass condensate picture. Here, we address the related question of the decoherence of the gluon field, which is a necessary component of thermalization. We present a simplified leading-order computation of the decoherence time of a gluon ensemble subject to an incoming flux of Weizsacker-Williams gluons. We also discuss the entropy produced during the decoherence process and its relation to the entropy in the final state which has been measured experimentally.Comment: 8 pages, 3 figure

Hydration increases the lifetime of HSO5 and enhances its ability to act as a nucleation precursor – a computational study

Recent experimental findings indicate that HSO5 radicals may play a key role in the nucleation of atmospheric SO2 oxidation products. HSO5 radicals are metastable intermediates formed in the SO2 oxidation process, and their stability and lifetime are, at present, highly uncertain. Previous high-level computational studies have predicted rather low stabilities for HSO5 with respect to dissociation into SO3+HO2, and have predicted the net reaction HSO3+OH→SO3+HO2 to be slightly exothermal. However, these studies have not accounted for hydration of HSO5 or its precursor HSO3. In this study, we have estimated the effect of hydration on the stability and lifetime of HSO5 using the advanced quantum chemical methods CCSD(T) and G3B3. We have computed formation energies and free energies for mono- and dihydrates of OH, HSO3, HSO5, SO3 and HO2, and also reanalyzed the individual steps of the HSO3+O2→HSO5→SO3+HO2 reaction at a higher level of theory than previously published. Our results indicate that hydration is likely to significantly prolong the lifetime of the HSO5 intermediate in atmospheric conditions, thus increasing the probability of reactions that form products with more than one sulfur atom. Kinetic modeling indicates that these results may help explain the experimental observations that a mixture of sulfur-containing products formed from SO2 oxidation by OH radicals nucleates much more effectively than sulfuric acid taken from a liquid reservoir

NMR and x-ray studies of structure in aqueous electrolyte solutions

Related publications: 1) "Nuclear Magnetic Resonance Contact Shifts and Electron Transfer Rates for Methyl-Substituted Tris (1, 10-Phenanthroline) Iron (II) and (III) Ions," D. W. Larsen and A. C. Wahl. Students supported: 2 Under Graduate StudentsThe objectives of the project are: (1) the determination of the effects of ions on the structure of water as a function of temperature, (2) assignment of effective sizes to the hydrated ions as a function of temperature, (3) the determination of configurations of interacting complex ions as a function of temperature, (4) the determination of isothermal compressibility as a function of temperature, and (5) correlation of the above with parameters of the ions.Project # A-022-MO Agreement # 14-01-000

Analysis of headless shear stud connections

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 115-117)Highway bridges are exposed to numerous elemental and loading issues that are extremely difficult for a designer to anticipate and account for during design. The current state of practice is to design a bridge deck for a certain life span and then turn the bridge over to maintenance personnel who attempt to prolong the life of the deck through a variety of repair and rehabilitation measures. These repair measures are rarely, if ever, considered during the design process of the bridge deck. Numerous researchers have looked at making bridges, specifically decks, more repairable. The majority of these research efforts have focused on the bridge deck system as a whole. Other researchers have looked at individual elements of the bridge deck to girder connection to see if the required strength could be achieved while making the connections easier to take apart. One of the main components in the bridge deck to girder system is the steel shear stud connection, which is used to create composite action between the deck and the girder. Numerous researchers have studied this connection from a strength perspective, and the strength equations for the shear connection have been codified. Shear connections using headless studs have been researched as well, but always as a part of a larger deck to girder connection system. The headless stud has never been researched to see how it responds to a shear loading. This study looks at headless studs with varying levels of debonding along the stud shaft to analyze the impact on the load resistance that the levels of debonding would have. Granular materials for the shear transfer of load are also looked at. The results show that, as expected, the headless, debonded shear studs can carry less load than a bonded stud, but the difference in load carrying capacity is within the suggested over-estimation range of the codes that other researchers have suggested. These results suggest that the use of headless, debonded shear studs in a deck to girder connection is a feasible way to make that connection more repairable.Funded by the U.S. Dept. of the Army.by Berndt F. SpittkaS.M