Inverse emulsions in a molten salt/hydroxy-terminated polybutadiene system using block copolymers as emulsifiers

Block copolymers of poly(N-t-butylbenzoyl ethylenimine) and poly(N-propionyl ethylenimine) (B_x/E_y and B_x/E_y/B_x) or poly (N-lauroyl ethylenimine) and poly (N-propionyl ethylenimine) (U_x/E_y) were synthesized by cationic ring-opening polymerization of 2-substituted δ2-oxazolines. Inverse emulsions (salt-in-oil) were made using these block copolymers as emulsifiers, hydroxy-terminated polybutadiene (HTPB) as the nonpolar phase and methyl ammonium ethane sulfonate (MAES) as the polar phase. These inverse emulsions (S/O) were then cured using a triisocyanate to give a dispersion of molten salt (MAES) droplets in polyurethane. Pore sizes of these cured inverse emulsions were measured from scanning electron photomicrographs as a function of stirring time and concentrations of block copolymer and molten salt. The results indicate that pores with diameters in the range of 1.5 X 10^?6 m can be obtained using triblock copolymer B_x/E_y/B_x, and that the surfactant molecules can be spread as a monolayer at the MAES-HTPB interface.     

On the [2,3] sigmatropic rearrangement of allylic nitro compounds

Allylic nitro compounds undergo relatively clean [2,3] sigmatropic rearrangement upon heating in refluxing 1,2-dichlorobenzene in the presence of DABCO to give the corresponding allylic alcohols via the intermediate allylic nitrite. [reaction: see text]     

Mathematical modelling of influence functions in computer-controlled polishing: Part I

Computer-controlled polishing (CCP) is commonly used to finish high-quality surfaces, such as optical lenses. Based on magnetorheological finishing (MRF), a mathematical model to calculate the polishing tool characteristic (influence function) was developed and verified experimentally. The first part of this paper introduces the model to predict the size and shape of an influence function. The second part of this paper describes the calculation of the distribution of material removal within the size of an influence function. The model supersedes the current cumbersome procedure for determining an influence function and thus results in considerably improved and more economical manufacture. Furthermore, the model enables the quality of the final surface to be enhanced when polishing complex, for example aspherical or free-form, workpiece geometries and provides the first step in the application of time-variant influence functions.     

Licensing a common value innovation when signaling strength may backfire

This paper reconsiders the licensing of a common value innovation to a downstream duopoly, assuming firms observe imperfect signals of the cost reduction induced by the innovation. The innovator adopts a direct revelation mechanism and awards an unrestricted license to the firm that reports the highest signal and a royalty contract to the other. Firms may signal strength to their rivals through exaggerated messages, which may however backfire, and give rise to higher royalty payments. We provide sufficient conditions for truthful implementation, and for the profitability of adding royalty contracts to what is otherwise a first-price license auction.     

The role of metacognitive monitoring in explaining differences in mathematics achievement

The relationship between practised monitoring activities and performance, especially in mathematics was examined within three nested studies. The first study deals with problems of faulty term rewritings submitted to three groups of subjects—10th to 13th graders, differing in their mathematical performance—whose task was to find the mistakes. Moreover, a questionnaire on the practice and appreciation of monitoring activities was developed. The third study, first, repeats the first study with a similar population and secondly adds interviews with some of the subjects while solving additional items concerning faulty term rewritings. Studies 1 and 3 show similar success in finding mistakes and in the replies to the questionnaire within the various groups. Furthermore, the third study points up that the subject’s answers do neither predict the practised monitoring nor the success in the test. However, the success correlates significantly with the practised monitoring. For a deeper understanding concerning the role of metacognition in explaining performance, the second study examined two of the groups who had already been involved in the first study. These were assigned some problems of a matrices test as used in cognitive psychology. While trying to solve the problem, their eye movements were recorded by means of an eye-tracker. Afterwards they had to justify their solutions in an interview. The eye movements were analysed, the verbal comments classified. Again, the groups differ in their problem solving success, dependant on the quality of the monitoring practised. Altogether, the results of the three studies elucidate the importance of practised metacognitive monitoring activities not only for success in school algebra, but furthermore the ability and the willingness to do it is deeper anchored in a person than just a trained behaviour for school algebra.     

Ring Transformation of α-Amino-β-oxoesters to δ-Butyrolactams

δ-Butyrolactams with an exocyclic ester moiety in the δ-position were accessed by reduction of 1-azido-2-cyclopentanone carboxylates with PBu₃ or Zn−AcOH. The ring transformation proceeded readily under the conditions of this reduction which is an unprecedented process. Primary amines formed by catalytic hydrogenation of α-azido-β-oxoesters with larger ring sizes or with benzannulation do not show this rearrangement under the conditions of the azide reduction. In these cases, the ring transformation to respective lactams was achieved by treatment of the α-amino-β-oxoesters with a stoichiometric amount of lithium diisopropylamide.