Antennas in material media near boundaries with application to communication and geophysical exploration, Part I: The bare metal dipole

The properties of the bare metal dipole embedded in a dissipative medium near a boundary are examined. These include the distribution of current, the driving-point admittance and impedance, and the effective length, with particular reference to antennas in the earth near the air surface at frequencies in the range from 30 to 300 kHz and antennas on the sea floor at frequencies in the range from 0.3 to 3 Hz. The effects of the internal impedance of the copper conductor are included at the low frequencies where they are important.     

Gbit/s transmission experiments with a 1.3 ?m high-speed surface-emitting LED and multimode graded-index fibre

Using a 1.3 ?m wide-bandwidth surface-emitting LED, transmission experiments were performed with 50/125 ?m multimode, graded-index fibre. Pulse shaping and equalisation were used in achieving a 10-9 bit-error rate at 1.0 Gbit/s over 3.0 km with a system margin of 1.1 dB. At 500 Mbit/s the margin increased to 7.0 dB. The 3.0 Gbit km/s data rate-distance product represents a new level of performance for a surface-emitting LED and multimode fibre.     

Proteolytic degradation of connectin, a high molecular weight myofibrillar protein, during heating of meat

When homogenised muscle (pH 5·5) was heated at 55°C, connectin was extensively degraded, whereas actin and myosin heavy chains were apparently unaffected. It was concluded that carboxyl proteases (e.g. cathepsin D) were largely responsible, because the breakdown of connectin was inhibited by the addition of pepstatin. When whole muscle samples were heated at 50-70°C, degradation of connectin was inversely related to the ultimate pH of the source muscle, again indicating the role of carboxyl proteases. The greater activity of carboxyl proteases in tissues from older animals was apparently responsible for the more extensive degradation of connectin in muscle from older sheep. Because connectin is extensively degraded in cooked meat, it is unlikely to contribute to meat toughness.     

Altering pasting characteristics of sweet potato starches through amino acid additives

ABSTRACT:  This study assessed the effects of amino acid additives, aspartic acid, leucine, lysine, and methionine, on the pasting and thermal characteristics of white- and orange-fleshed Beauregard sweet potato starches. A rapid visco analyzer 3D was used to determine pasting properties. In comparing pasting characteristics, starch from orange-fleshed sweet potato was found to be easier to cook, had a lower potential for retrogradation, and was less stable during heating than the white-fleshed sweet potato starch. The RVA analysis showed that the charged amino acids, aspartic acid and lysine, altered pasting characteristics of the 2 starches more than the neutral amino acids, leucine and methionine. Aspartic acid had similar effects on both starches, making them less stable during cooking and lowering the potential for retrogradation. Lysine, when added to the orange-fleshed sweet potato starch, decreased the breakdown, allowing for more stability during cooking. This study showed that pasting properties of sweet potato starches can be altered by the addition of amino acids.     

Mechanical strength of acrylic bone cements impregnated with antibiotics

Admixing of several antibiotic powders which were insoluble in methyl methacrylate did not decrease the compressive and diametral tensile strengths of two acrylic bone cements when tested after setting for 1 day and after leaching 40 days in water at 37 degrees C. When antibiotics were added as water solutions, the included water resulted in a significant decrease in these bulk mechanical properties. Storage in water for 40 days caused surface irregularities only on specimens of the set antibiotic admixtures. Approximately 0.5% of the admixed dosage of these water-soluble antibiotics could be leached from the set cements. The observed surface channels, presumably left by the loss of antibiotic, suggest further study of surface-sensitive mechanical properties may be needed. The bulk mechanical strengths presented here are conclusive only for the particular combinations of antibiotics and cements investigated, and should not be generalized at this time to any or all antibiotic admixtures or other mechanical properties.     

4-aminobiphenyl, 2-naphthylamine, and analogs: analytical properties and trace analysis in five substrates

Methods for monitoring trace levels of 4-aminobiphenyl, 2-naphthylamine, and their hydrochloride salts in waste water, microbiological growth media, potable water, human urine, and mouse blood utilizing spectrophotofluorometry (SPF) are described. The salient elements of the methods are extraction of the residues as the free amine with benzene, rapid cleanup on an alumina column, and quantification of the free amine in methanol via SPF. Potable water solutions of the salts are diluted with 0.01 N aqueous HCL and quantified directly by SPF. Ancillary analytical information concerning gas chromatography of the free amines, partitioning properties of the compounds between solvent pairs, their solubility and stability in water, and thin-layer chromatographic data is presented. The compositions of various admixtures of 1- and 2-naphthylamine or their salts were determined by using SPF with calculations based on simultaneous equations.     

A dose-response study of anorectic drug effects on food intake, self-stimulation, and stimulation-escape

The DNA polymerase of Ustilago maydis is stimulated by a DNA binding protein from the same organism. Analysis of this stimulation shows that there is an increase in affinity for both substrates of the reaction. The apparent Km for deoxynucleoside triphosphates is decreased 3 fold, and that for denatured DNA by 4 fold. In both cases the maximum velocity (Vmax) is increased 1.2 to 1.4 fold. It is suggested that the variability in the affinity of the enzyme for deoxynucleoside triphosphates mediated by the binding protein may provide the basis for the UV sensitivity of pyrimidine auxotrophs in this organism.