Gabor zone plate with binary transmittance values.

A methodology is presented for producing a Gabor zone plate by using a binary transmittance function that is both radially and azimuthally distributed on the surface of the plate. The measured optical properties of such a plate are shown to be in agreement with those of the idealized Gabor plate that possesses a radially sinusoidal transmittance function.

Synthesis and evaluation of ureido- and vinylureidopenicillins as inhibitors of intraruminal lactic acid production.

A series of 14 vinylureidopenicillins and a series of 9 ureidopenicillins were prepared by reaction of 6-aminopenicillanic acid with vinyl isocyanates and isocyanates. These compounds were evaluated for their potential to protect ruminants against lactic acidosis. The compounds were tested for inhibition of in vitro ruminal lactic and propionic acid production, and six compounds inhibited lactic acid production to less than 10% of control at doses of 0.31 microgram/mL or lower, whereas they did not inhibit propionic acid production at doses greater than 10 micrograms/mL. The most active compounds also were screened for general antibacterial activity and were found to be weakly active against Gram-positive bacteria. The structure--activity relationships are discussed for both series. Triethylammonium 6-[3[2-(4-tert-butylphenyl)vinyl]ureido]penicillanate (4) was chosen for evaluation as an inhibitor of intraruminal lactic acidosis in vivo.

Synthesis and antimicrobial activity of certain 6H-1,2,4-oxadiazin-3(2H)-ones.

Treatment of 6H-1,2,4-oxadiazin-3(2H)-one-5(4H)-thione (2) with hydroxylamine, hydrazine, methylamine, or benzylamine afforded the corresponding N5-substituted 5-amino-6H-1,2,4-oxadiazin-3(2H)-ones 3c-f. Refluxing a dioxane solution of 6H-1,2,4-oxiazine-3,5(2H,4H)-dione (1) with benzylamine or aminodiphenylmethane and hexamethyldisilazane in the presence of ammonium sulfate gave 5-benzylamino-6H-1,2,4-oxadiazin-3(2H)-one (3f) and the corresponding 5-diphenylmethylamino derivative 3g. Reaction of 1 with methyl iodide, benzyl chloride, dihydropyran, dihydrofuran, or benzyloxycarbonyl chloride afforded the corresponding 2-substituted 6H-1,2,4-oxadiazine-3,5(2H,4H)-diones 6a-e. Reaction of 2-methyl-6H-1,2,4-oxadiazine-3,5(2H,4H)-dione (6a) or the corresponding 2-benzyl derivative 6b with phosphorus pentasulfide in dioxane gave 2-methyl-6H-1,2,4-oxadiazin-3(2H)-one-5(4H)-thione (8a) and the corresponding 2-benzyl derivative 8b, respectively. Reaction of 8a with ammonia in dioxane afforded 2-methyl-5-amino-6H-1,2,4-oxadiazin-3(2H)-one (9). The degree of in vitro activity and the presence of antibacterial activity in the urine of animals given 5-amino-6H-1,2,4-oxadiazin-3(2H)-one (3a) by oral route of administration prompted selection of this compound for further study.