High field electrostrictive response of polymers

It is well known that electrostrictive strains are proportional to the square of the applied electric field. It therefore appeared reasonable to assume that for some polymeric materials, a large acoustic thickness response, d_T, \[ \left( {d_T = \frac{{dS}}{{dE}}} \right) \] might be obtained by application of high dc bias fields, ～ 20 MV/m, to a film while driving the film with an ac signal to access the high slope region of the electrostrictive strain vs. applied field curve. Previous studies of crystallizing poly(vinylidene fluoride) (PVF₂) from solution under high electric fields have demonstrated that gel-like samples of PVF₂ with high content of the plasticizer tricresyl phosphate (TCP) could be subjected to electric fields as high as ～ 100 MV/m. Using this type of heavily plasticized PVF₂ d_T values ～ 4 Å/V were obtained. Values of 9 Å/V were obtained for a certain class of thermoplastic elastomer (i.e., a polyurethane). These d_T values are considerably greater than those obtained from conventional piezoelectric ceramic materials. In addition, large elastic strains (> 3%) were observed as a function of applied dc field. © 1994 John Wiley & Sons, Inc.     

Microchemical investigation of medicinal plants. IX

Summary A procedure is described to hydrolyzeg-amounts of scopolamine in alkaline medium using a capillary tube, followed by separation and identification of the products by thin-layer chromatography. Scopine can be recovered when the reaction is carried out at 25° for 1 hour, while scopoline is the major product at 100°. Both atropine and homatropine yield tropine at 25° for 1 hour. In contrast, apoatropine remains unchanged under these conditions.

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Zusammenfassung Ein Verfahren zur Hydrolyse von Mikrogrammengen Scopolamin in alkalischem Medium in einem Kapillarröhrchen wurde beschrieben. Die Hydrolyseprodukte wurden anschließend durch DC getrennt und identifiziert. Man erhält Scopin, wenn die Hydrolyse l Stunde bei 25° vorgenommen wird; bei 100° ist Scopolin das Hauptprodukt. Atropin und Homatropin geben bei 25° in l Stunde Tropin. Im Gegensatz dazu bleibt Apoatropin unter diesen Bedingungen unverändert.

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For Part VIII see Mikrochim. Acta [Wien] 1970, 670. Inquiries and requests for reprints of this series of papers should be addressed to Prof. T. S. Ma, Department of Chemistry, City University of New York, Brooklyn, N. Y. 11210.     

A computational procedure for the approximation of random functions

Summary A procedure is given for the problem of minimizing the expected error incurred when a random function is approximated by a polynomial.     

Iodomethylethers from 1,3-dioxolane and 1,3-oxathiolane: preparation of acyclic nucleoside analogs

Purine and pyrimidine anions were alkylated using the iodomethyl ether and thioether generated $\text{in}$$\text{situ}$ by the reaction of 1,3-dioxolane and 1,3-oxathiolane with trimethylsilyl iodide.     

Synthesis of 5,6-dimethoxyquinazolin-2(1H)-ones

Synthesis of 5,6-dimethoxyquinazolin-2(1H)-one derivatives was the subject of investigations leading to the preparation of title compounds 11, 13, 14 and 26 . Target quinazolines 1 were synthesized in three ways; the route starting from o-vanillin via the intermediacy of 6-amino-2,3-dimethoxyacetophenone ( 19 ) was used for most of the preparative work. The unexpected formation of an acid-labile dimer of 13 was discovered and solid state ¹³C nmr was used for structural assignment. The 5-methoxy substituent in these systems shows anomalous spectral characteristics and, in one case, was cleaved in acid media to 22 .