Fetal heart rate patterns preceding death in utero

Four cases of intrauterine fetal demise in term infants are presented. From these cases and other published reports, a sequence of fetal heart rate changes preceding intrapartum death is presented. Late or variable decelerations, if unrelieved or uncorrected, lead to baseline heart rate changes of tachycardia and loss of variability reflecting loss of fetal reserve and fetal distress. This is followed by an unstable heart rate, a sinusoidal pattern, or a rapidly changing fetal heart rate. The final event is a profound bradycardia just prior to fetal demise.     

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.     

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.     

On the vibrational spectra of poly-1,1,2,2-tetrachlorobutane-a model for head-to-head poly(vinylidene chloride)

Infra-red and Raman spectra of poly (1,1,2,2-tetrachlorobutane), a model polymer for head-to-head poly(vinylidene chloride), are presented. Mutual exclusion of the infra-red and Raman spectra is observed and the polymer appears to be highly ordered. The preferred conformation of the polymer chain is inferred to be most probably in the form of a planar zigzag.