A New Technique for Time-Base Stabilization of Video Recorders

Videotape recorders in professional broadcasting use require electronic time-base correcting devices to stabilize the timing of the output signal to the accuracy needed by color television. Many schemes have been used or proposed for this purpose. The method described is arranged to provide an unusually large operating range, thereby permitting its associated recorder to be designed for fast starting time, quick recovery from large disturbances, and fully synchronous operation. The technique involves the use of switched fixed ultrasonic delay lines whose delay times are arranged in a binary order, followed by a conventional continuously variable vernier delay line. A new method of direct measurement of velocity errors is incorporated in the system.     

New optically pumped far-infrared lasers

Ninety-seven new far-infrared (FIR) laser transitions have been observed in optically pumped ethylene glycol, dimethyl ether, formic acid, and monomethyl amine, all excited by a pulsed CO2laser.     

The anodic oxidation of poly-fluorinated aromatic compounds in fluorosulphonic acid—the production of stable cation radicals

Voltammetric data are reported for a series of fluoroaromatic hydrocarbons in fluorosulphonic acid containing a base, acetic acid (0·1 M). In this medium and at room temperature, all but one of the compounds show an initial one electron oxidation to form a cation radical which is stable on the timescale of cyclic voltammetry; with the exception of the cation radical of octafluoronapthalene, none are stable indefinitely and approximate half lives are reported.Experiments at low temperatures or in solutions in this solvent where the supporting electrolyte is the acid, antimony pentafluoride, show that conditions may be defined where the cation radicals are stable indefinitely.Some preliminary preparative results are reported and these show that fluorosulphonate esters may be prepared.     

Growth depression and tissue reaction to the consumption of excess dietary methionine and S-methyl-L-cysteine

Similar depressions in growth were observed when rats consumed a 10% casein basal diet containing equal quantities of either methionine or S-methyl-L-cysteine. Supplemental glycine or serine partially alleviated the growth depression caused by the high levels of methionine but were ineffective in alleviating the growth depression caused by high levels of S-methylcysteine. Histological examination of five organs of rats fed the basal, high methionine or high S-methylcysteine diet for 6, 13 or 20 days revealed that only the spleens were affected in that there was erythrocyte engorgement and an accumulation of hemosiderin. The intensity of iron staining in spleens decreased from the second to the third week. The similarity in the depression of growth and splenic damage observed in rats consuming high levels of methionine or S-methylcysteine is consistent with an earlier suggestion that metabolism of the methionine or S-methylcysteine is consistent with an earlier suggestion that metabolism of the methyl group is in some way involved in the toxicity of methionine.     

Magnesium-lead chloride batteries

The preparation of lead chloride cathodes, and their discharge in magnesium-lead chloride batteries, is described. The lead chloride blended with graphite is pasted on grids of expanded copper, using urea formaldehyde solutions as the binder. One-, five-, and fifteen-cell batteries were discharged at temperatures between –40°C and +45°C, at low current drains. For five-cell batteries energy densities in the range 10–30 Wh/lb were obtained. Mechanical properties of the cathode, so far as investigated, were excellent. The main difficulty was cathode softening during prolonged runs at high temperatures. At –40°C the battery attained working voltage in about 5 minutes; although slower than the Mg-AgCl system, the Mg-PbCl₂ system should meet many applications at this temperature.