The effect of defects on the low temperature thermal conductivity of yttrium iron garnet

The extremely low thermal conductivity at low temperatures of some yttrium iron garnet single crystals is attributed to sheets of defects revealed by chemical etching.     

Uniqueness and growth of weak solutions to certain linear differential equations in Hilbert space

In this paper, we study, by means of a modification of the weighted energy method, the questions of uniqueness and growth of weak solutions to evolutionary equations of the form u_tt = Mu where M is a symmetric operator and u takes values in a Hilbert space. We show that if the initial energy is negative, then the kinetic and potential energies have exponential growth. This is also the case when the initial energy is nonnegative provided it is not too large and the cosine of the angle between the initial displacement and initial velocity is sufficiently close to one.We also derive a continuous dependence result.     

Maleimide polymers. I. A polymeric color reaction

Certain copolymers of maleimide and N-substituted maleimides yield brilliant colors when treated with sufficiently strong basic reagents under nonhydrolytic conditions. For color generation, the copolymer must be capable of HX elimination. The chromophores which account for color probably result from the ionization of acidic protons in structures involving one or more double bonds conjugated with imide carbonyl. The analogy to the color reactions of aconitylanil is pointed out. Spectra covering the range of 330–700 mμ are presented for a number of copolymer–amine color-generating systems. The colors produced in base with radical-initiated polymaleimide and imidazole-initiated poly-N-alkylmaleimides as well as the absence of color with anionic polymaleimide and radical poly-N-alkylmaleimides are discussed in light of what is known about their polymerization kinetics and mechanisms. Corresponding maleic anhydride copolymer systems are mentioned.     

Non-Hertzian contact stresses in a smoothly cradled heavy cylinder

Summary Contact stresses in a heavy circular cylinder resting in a smooth rigid cradle of general profile are analyzed for contact zones outside the validity of Hertz theory. Numerical results are presented for various circular cradles having radii different from that of the cylinder and contact angles up to seventy-five degrees. Discrepancies with Hertz theory are discussed.