Polymerization of methyl acrylate in aqueous media

The polymerization of methyl acrylate in water and in dilute, aqueous, soap solutions, initiated by potassium peroxydisulfate, has been investigated, a dilatometric method being used to follow the conversion. It has been shown that small amounts of an anionic soap increase the rate of reaction while a cationic soap has the reverse effect. The change of molecular weight with conversion has also been examined as well as the effect of the exclusion of oxygen from the system.     

Galerkin methods applied to some model equations for non-linear dispersive waves

The application of a dissipative Galerkin scheme to the numerical solution of the Korteweg de Vries (KdV) and Regularised Long Wave (RLW) equations, is investigated. The accuracy and stability of the proposed schemes is derived using a localised Fourier analysis. With cubic splines as basis functions, the errors in the numerical solutions of the KdV equation for different mesh-sizes and different amounts of dissipation is determined. It is shown that the Galerkin scheme for the RLW equation gives rise to much smaller errors (for a given mesh-size), and allows larger steps to be taken for the integrations in time (for a specified error tolerance). Also, the interaction of two solitons is compared for the KdV and RLW equations, and several differences in their behaviour are found.     

The Nasathermionic-Conversion (TEC-Art) Program a Proposed Paper for Presentation at the May 1977 IEEE International Conference on Plasma Science at Rensselaer Polytechnic Institute

The NASA program for applied research and technology (ART) in thermionic energy conversion (TEC) comprises in-house, university-grant, and industrial-contract studies. In a few years this TEC-ART program has produced important results. Although many of these accomplishments are incremental, their integration has yielded performance gains and the knowledge necessary to direct future work. The current emphasis on out-of-core thermionics allows materials and designs previously prohibited by in-core nucleonics and geometrics. The additional degrees of freedom offer new potentialities. But as always high-temperature material effects will determine the level and lifetime of TEC performance: New electrodes must not only raise power outputs but also maintain them regardless of emitter-vapor deposition on collectors. In addition effective electrodes must serve compatibly with hot-shell alloys. Then, of course, space TEC must withstand external and internal high-temperature vaporization problems. And terrestrial TEC must tolerate hot corrosive atmospheres outside and near-vacuum inside. Finally reduction of losses between converter electrodes is essential even though rather demanding geometrics appear to be required for some modes of enhanced operation. In these and other areas from basic material characterizations to possible system definitions, significant progress is being made in the NASA TEC-ART Program.     

A Linear Programming Approach to the Solution of Constrained Multi-Facility Minimax Location Problems where Distances are Rectangular

The problem of locating new facilities with respect to existing facilities is stated as a linear programming problem where inter-facility distances are assumed to be rectangular. The criterion of location is the minimization of the maximum weighted rectangular distance in the system. Linear constraints which (a) limit the new facility locations and (b) enforce upper bounds on the distances between new and existing facilities and between new facilities can be included. The dual programming problem is formulated in order to provide for an efficient solution procedure. It is shown that the duLal variables provide information abouLt the complete range of new facility locations which satisfy the minimax criterion.     

Hestenes' Tetrad and Spin Connections

Defining a spin connection is necessary for formulating Dirac's bispinor equation in a curved space-time. Hestenes has shown that a bispinor field is equivalent to an orthonormal tetrad of vector fields together with a complex scalar field. In this paper, we show that using Hestenes' tetrad for the spin connection in a Riemannian space-time leads to a Yang-Mills formulation of the Dirac Lagrangian in which the bispinor field Ψ is mapped to a set of SL(2,R)× U(1) gauge potentials F_α^K and a complex scalar field ρ. This result was previously proved for a Minkowski space-time using Fierz identities. As an application we derive several different non-Riemannian spin connections found in the literature directly from an arbitrary linear connection acting on the tensor fields (F_α^K, ρ). We also derive spin connections for which Dirac's bispinor equation is form invariant. Previous work has not considered form invariance of the Dirac equation as a criterion for defining a general spin connection.     

SNAr iodination of 6-chloropurine nucleosides: aromatic Finkelstein reactions at temperatures below -40 degrees C

Mesitoyl or toluoyl esters of inosine and 2'-deoxyinosine were deoxychlorinated at C6 to give the crystalline 6-chloropurine nucleoside derivatives, which underwent quantitative conversion to the 6-iodo analogues with NaI/TFA/butanone at -50 to -40 degrees C. The 6-iodo compounds were efficient substrates for SNAr, Sonogashira, and Suzuki-Miyaura reactions, in contrast with the 6-chloro analogues, and gave good to high yields of C-N and C-C coupled products.     

Preparation of 5-hydroxy-1-alkenyboronates from 1-alkynylboronates, Cp2ZrCl2/2EtMgBr, and aldehydes

1-Alkynylboronates form five-membered zirconacycles with Cp(2)ZrCl(2)/2-EtMgBr as indicated by deuterium labeling. The zirconacycles add aldehydes to form seven-membered zirconacycles. Hydrolysis of the latter provides 5-hydroxy-1-alkenylboronates in fair to good isolated yields. Both aliphatic and aromatic aldehydes undergo insertion.     

Cartan-decomposition subgroups of

For and , we give explicit, practical conditions that determine whether or not a closed, connected subgroup of has the property that there exists a compact subset of with . To do this, we fix a Cartan decomposition of , and then carry out an approximate calculation of for each closed, connected subgroup of .