Tony L. Yang

Ultrafiltrate of saliva collected in situ for the measurement of testosterone

Abstract A device for the in situ collection of an ultrafiltrate of saliva was investigated. The collector consists of an osmotic pump that, when placed in the mouth, accumulates a prepurified salivary filtrate within a few minutes. The concentration of testosterone in saliva and in the ultrafiltrate from five male subjects was determined by a solid-phase immunoassay. The ultrafiltrate can be used without extraction as a medium for the diagnostic evaluation of free, protein-unbound testosterone. Concentrations in whole saliva and the ultrafiltrate correlate closely ( r = 0.89; n = 42). The collector can potentially be used for the measurement of a wide variety of analytes other than testosterone. An ultrafiltrate of saliva as diagnostic medium provides the following advantages: simplicity of collection; moderate stimulation of salivary flow; exclusion of potential blood contamination; prevention of binding of analytes to protein; prevention of potential metabolic degradation of analytes; reduction of viscosity by exclusion of mucopolysaccharides and other large molecules; and potential sterile sampling of ultrafiltrate.

Thermodynamics of the (lanthanum + strontium + copper + oxygen) high-Tc superconductors I. Heat capacities of SrCuO2, Sr2CuO3, and Sr14Cu24O41

Abstract The subambient heat capacities of three (SrO)x(CuO)y inter-oxide samples with x = y = 1; x = 2, y = 1; and x = 1, y = 2, were measured as a part of an investigation into the chemical thermodynamics of the high-Tc superconducting system (lanthanum + strontium + copper + oxygen). No anomalous contribution to the heat capacity was observed over the experimental region. The heat capacity of the Sr14Cu24O41 phase was derived from that of the mixed phase of nominal composition x = 1, y = 2. All samples exhibit a Debye-like behavior at low temperatures with finite linear electronic terms. Thermophysical properties at selected temperatures are presented and compared for the three compounds. The values of Smo at 298.15 K for the three compounds Sr 1 2 Cu 1 2 O , Sr 2 3 Cu 1 3 O , and Sr 14 38 Cu 24 38 O 41 38 were: 5.828·R, 5.953·R, and 6.032·R, respectively.