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A needle-type coaxial probe for the measurement of radio frequency and microwave permittivity of biological samples is studied both theoretically and experimentally. The probe is obtained by a slanted cut, and therefore the radiation aperture is elliptical. Both theoretical analysis and experiments show that the measurement sensitivity is improved with the increased bevel angle of the probe. Calibration results using water and air at low frequencies are in agreement with theoretical calculations. Measurements on three biological samples (sonicated DNA macromolecules, water solutions of protein (the protamine), and in -aminocaproic acid) were made from 1 MHz to 1 GHz. All the measured results are in very good agreement with similar tests obtained from the same materials using a standard probe. The theoretical and experimental results show that the probe improves measurement sensitivity and it facilitates insertion into some test samples. >

Very little work has been done in the past on the use of microwave plasmas for the desulfurization of oil products. This paper presents the measured desuffurizaiion levels on a diisopropyl disulfide oil solution containing 5.2% by weight of sulfur. Complete desulfurization was obtained, using either hydrogen or helium plasmas at atmospheric pressures.The estimated cost to completely desulfurize I metric ton of oil containing 5,2% by weight of sulfur is about $20.00 by the use of this new technology.

A new technology for producing large volume microwave plasmas is introduced, Microwave energy is coupled into the plasma by means of a slow wave structure, and plasma volumes well in excess of 1000 cm3 can readily be achieved with 2.5 kW of microwave power at 2.45 GHz. General operating characteristics and some experimental data are presented.

In an attempt to understand the factors involved in failure to duplicate previous success in freezing and thawing canine kidneys, an analysis of the two ovens used revealed more irregularity of heating within the Litton chamber. In addition, direct measurement after thawing as well as thermography showed that the Litton chamber gave a wider spread in heating than did the Toshiba oven. In order to introduce an indirect way to monitor temperature changes within the chamber during the thawing process, the use of a resonant perturbation technique is described. Such measurements are noncontact and depend on the average temperature load in the oven. This method can be used to control automatically the rate of average temperature rise and regularize the heat cycle and time. Connected to a programmed microprocessor it would allow the design of ovens which could ignore the problems of magnetron sensitivity. The concentration of Me 2 SO in the solution has been demonstrated to affect the curve of thaw and the size of the kidney is also of great importance. If thawing is stopped at 0 °C, deep and uniform thawing occurs which may obviate the thermal runaway seen when the thaw is brought to higher temperature.