Bulk and Surface Properties of Liquid Al-Li and Li-Zn Alloys

Physicochemical properties like density, surface tension, and viscosity of liquid binary Al-Li and Li-Zn alloys have been measured using draining crucible method. The experimentally measured surface-tension values have been compared to theoretical results based either on the Butler model or the compound formation model assuming the existence of the most favored A ₁ B ₂ and A ₂ B ₃ clusters. Several models for viscosity calculation have been also applied and discussed in confrontation with measured data. Finally, the clustering effects in the liquid Al-Li and Li-Zn alloys have been examined using two microscopic functions, i.e., the concentration fluctuation function in the long-wavelength limit and the Warren-Cowley short-range order parameter.     

Analytical performance of the Tandem-R free PSA immunoassay measuring free prostate-specific antigen

The analytical performance of the Tandem-R free PSA assay available from Hybritech Inc. was evaluated. Comparison of recoveries of purified free (unbound) prostate-specific antigen (PSA) diluted in female serum in the Tandem-R free PSA assay and the Tandem-R (total) PSA assay demonstrated a link in calibration between the assays and an accurate determination of percent free PSA. The cross-reactivity of the assay to purified PSA-alpha 1-antichymotrypsin was determined to be < 1%. The minimum-detectable concentration was < 0.05 microgram/L. The within-run and between-day CVs were < or = 5% for samples with > 0.3 microgram/L free PSA. Dilution and recovery showed no significant deviations from linearity across the assay range. The assay was insensitive to interference from blood components. The Tandem-R free PSA kit was shown to be an accurate, precise, and reliable assay for the measurement of free PSA.     

Modeling Immune Building Systems for Bioterrorism Defense

This paper presents the results of research on the performance of air-cleaning and air-disinfection systems used for protecting buildings against intentional releases of biological agents. The air-cleaning technologies addressed include dilution ventilation, filtration, and ultraviolet germicidal irradiation. A 40-story commercial office building is modeled using typical occupancy levels and leakage rates for doors, walls, and floors. A steady-state single-zone model is used to predict steady-state conditions resulting from the use of various levels of air cleaning. A transient single-zone model is used to predict transient indoor concentrations from which inhaled doses and estimated casualties are predicted. A transient multizone model is used to evaluate contaminant dispersion and estimate potential casualties. Three design-basis attack scenarios are simulated using various biological weapon agents. Predicted casualties are estimated using an epidemiological model of the dose response curves for each of the agents. The effect of increasing levels of air cleaning is examined under the attack scenarios to evaluate their effectiveness. Results indicate that high levels of protection are possible for building occupants with moderate and affordable levels of air cleaning when filtration is combined with ultraviolet germicidal irradiation. Results also suggest that diminishing returns occur when increased levels of air cleaning are applied. It is hypothesized that the maximum useful size of any air-cleaning system is defined and limited by building physical characteristics alone.     

Surface-tension measurements of the eutectic alloy (Ag-Sn 96.2 at.%) with Cu additions

The maximum bubble-pressure method has been used to measure the surface tension and density of liquid alloys (Ag-Sn)_eut + Cu (X_Cu = 0.005, 0.020, 0.0375, and 0.065 (mole fraction)). The surface tension and density measurements were curried out in the temperature ranges of 262–942°C and 264–937°C, respectively. The linear dependencies of surface tensions and densities on temperature were observed, and they were described by straight-line equations. It has been found that the additions of Cu to the Ag-Sn eutectic alloy increase the surface tension. Experimental data of the surface tension were compared with those from modeling based on Butler’s method, using the optimized-thermodynamic parameters from the literature, and a slight tendency contrary to the experimental results was observed.     

Geographic Variation in Acadian French /r /: What Can Correspondence Analysis Contribute Toward Explanation?

This article presents elements of a Correspondence Analysis(CA) approach to the measurement of linguistic distances indialectology. It argues that both linguistic and spatial factorsare part of an explanation of geolinguistic variation, and itshows how the exploratory and graphical properties of CA cancontribute to such an explanation. The application is a studyof the different realizations of the phoneme /r/ in AcadianFrench, a dialect spoken in Canada. Data are from the Atlaslinguistique du vocabulaire maritime acadien and include over5,000 tokens from eighteen localities. Using chi-square distances,the analysis results in a two-dimensional space that arrangesthe localities along continua. Linguistic interpretation ofthis space, based on those features of /r/ that are identifiedas accounting for the structuring of these continua, suggestsa hierarchy of phonological processes—including alternationbetween apical and dorsal articulations (in French words), andreplacement of the retroflex rhotic found in English-originwords by apical and dorsal variants. Two external spatial factors,local concentration of francophone speakers and spheres of activity,are shown to correlate with the linguistic distances among localities.     

Sex-based and hormonal contraception effects on the metabolism of nicotine among adolescent tobacco-dependent smokers.

Variations in nicotine metabolism influence smoking patterns. Differences between sexes or related to sex hormones may affect nicotine metabolism. Because smoking initiation starts during adolescence, observations gathered from adolescent smokers might broaden our understanding of such sex-based differences. We tested the hypothesis that nicotine metabolism--as indexed primarily by the ratio of trans-3'-hydroxycotinine (3HC) to cotinine--is more rapid among adolescent girl smokers compared with boys and that regular use of hormonal contraceptives influences nicotine and cotinine metabolism. We also hypothesized that more rapid nicotine metabolism is associated with higher nicotine dependence as indexed by smoking frequency and morning urgency. Plasma samples of nicotine, cotinine, and 3HC concentrations were obtained from 120 adolescents (36 boys). Plasma nicotine and cotinine concentrations were similar in boys and girls. Median plasma 3HC concentrations were 44.45 ng/ml for girls versus 35.74 ng/ml for boys (p = .025), and median plasma 3HC-cotinine ratios were significantly higher in girls than in boys (0.317 vs. 0.253, p = .025). After stratifying girls into two groups based on use versus nonuse of hormonal contraception, plasma 3HC-cotinine ratios in girls using hormonal contraception (0.47) were substantially higher (p<.0001) than in boys (0.25) and were significantly higher than in girls not using hormonal contraception (0.28). Controlling for cigarettes smoked per day, ethnicity, and age did not modify these results. Although plasma nicotine, cotinine, or 3HC concentrations were significantly lower in less dependent adolescent smokers, nicotine and cotinine metabolite ratios were similar. This study showed that hormonal contraception in adolescent girls may accelerate cotinine metabolism, an effect likely related to induction of cytochrome P450 2A6 and independent of ethnicity and cigarette consumption. Prospective controlled studies are needed to further evaluate the role of hormonal contraception in patterns of adolescent smoking and nicotine metabolism.     

Interfacial activity of 4-alkylphenylamines and the rate of palladium(II) extraction

Interfacial tension isotherms were determined in hydrocarbon-water systems for 4-alkylphenylamines containing from 6 to 16 carbon atoms in their alkyl chains, and the surface excess isotherms were computed and interpreted using various adsorption isotherms. Palladium(II) was extracted with 4-alkylphenylamines from 3 M HCI solutions. The maximum extraction rate of palladium(II) is observed for 4-decyl- and 4-dodecylphenylamines which exhibit good interfacial activity. Compounds soluble in the aqueous phase (4-hexylphenylamine) or in toluene (4-hexadecylphenylamine) extract palladium(II) slower than 4-decyl- and 4-dodecyl- phenylamines.