Automated direct high-performance liquid chromatographic assay for estetrol, estriol, cortisone and cortisol in serum and amniotic fluid.

An automated direct assay for the simultaneous determination of unconjugated estetrol, estriol, cortisone and cortisol in serum and amniotic fluid, using high-performance liquid chromatography with electrochemical detection and ultraviolet detection, has been developed. The analysis time is ca. 1 h. This system offers good reproducibility with low coefficients of variation (estetrol, 2.3%; estriol, 2.3%; cortisone, 2.6%; cortisol, 1.9%). Detection limits are low enough for routine determinations (estetrol and estriol, 150 pg; cortisone and cortisol, 5 ng). Comparison of the values measured by the present method and by radioimmunoassay revealed significant correlations for estetrol (r = 0.787, p less than 0.01), estriol (r = 0.957, p less than 0.01), cortisone (r = 0.956, p less than 0.01) and cortisol (r = 0.865, p less than 0.01). This system proved to be valuable in monitoring feto-placental function.     

Uranium,thorium and potassium occurrences in the vicinity of hot springs in the northern neotectonic belt in the Eastern Cape Province,South Africa

Gamma ray measurements were carried out along two parallel lines close to each of the hot springs using a RS 125 spectrometer to find the concentration (ppm) of U, Th, and K at Polile Tshisa, Aliwal North, and Badfontein hot springs. The RS 125 spectrometer is auto-stabilized on the naturally occurring U, Th, and K, and provides concentrations (ppm) of the radioelements. The results show that the concentration of thorium is higher, and is below the world average hazardous threshold of 7.4 ppm. Thorium is related to the occurrence of monazite seen at the scanning electron microscope. Higher ratios of U/K are indicative of an increase of uranium relative to potassium. Binary diagrams (Th–U, K–U, and K–Th) do not show a clear best fit except at Polile Tshisa hot spring where thorium shows a quasi positive correlation to potassium. In general, it can be concluded that the concentrations of these three radioelements are quite low, acceptable for groundwater, and could be hazardous to the health of humans and animals if exposed to long time radiations.     

Dynamics of the photoinduced desorption of nitric oxide molecules from the surface of pure and modified platinum

The distribution of NO molecules desorbed from a Pt(111) surface due to valence electron excitation over rotational energy levels N(J) is analyzed using a simple impulse-induced model. A linear dependence is found between lnN(J) and (E_r)^1/2, where E_r is the rotational energy of the desorbed molecules. The lifetime of the excited state and the critical time of residence in the excited state estimated using this dependence are found to be close to one another (~10^?15 s). The frequency and amplitude of the tilting vibrations of the adsorbed molecules in the excited state are estimated.     

Determination of tryptophan and its metabolites in human plasma and serum by high-performance liquid chromatography with automated sample clean-up system

An automated high-performance liquid chromatographic method that incorporates direct injection of biological samples followed by chromatographic sample clean-up in a precolumn is described for the determination of tryptophan and its metabolites in human plasma and serum. The system gave reproducible data with a coefficient of variation of less than 3% with a sample size of 100 microliters of human plasma. The major tryptophan metabolites found in 100 microliters of human plasma were kynurenine, indolelactic acid, indoleacetic acid, indolepropionic acid, serotonin and 5-hydroxyindoleacetic acid. The level of tryptophan and kynurenine in individuals was constant in comparison with other metabolites. Analysis of samples from normal controls, diabetics, gravida and their foetuses showed a tendency for tryptophan metabolites to be low in maternal plasma.     

Xenon-plasma light ultrahigh-resolution ARPES study of low-energy single-particle excitation gap in (Bi,Pb)2Sr2CuO6

We have performed ultrahigh-resolution angle-resolved photoemission spectroscopy of (Bi,Pb)₂Sr₂CuO₆ by using a newly developed xenon-plasma light source to clarify the origin of the pseudogap (PG). We determined the comprehensive momentum and temperature dependences of the superconducting (SC) gap and the PG, and revealed a smooth evolution of the PG from the SC gap. We also found a linear scaling behavior of the characteristic PG temperature with the SC gap size regardless of the momentum location. These experimental results strongly suggest that the observed PG is caused by the precursor pairing.     

Warm-white light-emitting diode with yellowish orange SiALON ceramic phosphor

A warm-white light-emitting diode (LED) without blending of different kinds of phosphors is demonstrated. An approach that consists of a blue LED chip and a wavelength-conversion phosphor is carried out. The phosphor is a newly developed yellowish orange CaEuSiAlON ceramic phosphor with high efficiency. The CIE1931 chromaticity coordinates (x, y) are (0.458, 0.414), the color temperature is 2750 K, and the luminous efficacy of this LED is 25.9 lm/W at room temperature and with a forward-bias current of 20 mA. The chromaticity of the assembled LED is more thermally stable than that of a LED with a conventional oxide phosphor (YAG:Ce) because of the better thermal stability of the oxynitride phosphor.     

Application of a high-performance,special-purpose computer,GRAPE-2A,to molecular dynamics

The special-purpose computer GRAPE-2A accelerates the calculation of pairwise interactions in many-body systems. This computer is a back-end processor connected to a host computer through a Versa Module Europe (VME) bus. GRAPE-2A receives coordinates and other physical data for particles from the host and then calculates the pairwise interactions. The host then integrates an equation of motion by using these interactions. We did molecular dynamics simulations for two systems of liquid water: System 1 (1000 molecules), and System 2 (1728 molecules). The time spent for one step of molecular dynamics was 3.9 s (System l), and 10.2 s (System 2). The larger the molecular system, the higher the performance. The speed of GRAPE-2A did not depend on the formula describing the pairwise interaction. The cost performance was about 20 times better than that of the fastest workstations available today, and GRAPE-2A cost only $22,000. © 1994 by John Wiley & Sons, Inc.     

Automated direct assay system for the measurement of sex steroid hormones in serum using high-performance liquid chromatography

An automated direct assay system using high-performance liquid chromatography was developed for the simultaneous measurement of estradiol, estrone, progesterone, 17 alpha-hydroxyprogesterone, 20 alpha-hydroxyprogesterone, testosterone and androstenedione in biological fluids. A comparison between the values measured by this method and by radioimmunoassay revealed good correlation for estradiol (r = 0.938, p less than 0.001) and progesterone (r = 0.903, p less than 0.001). Estradiol and estrone could be analysed above the level of 250 pg/ml, and progesterone, 17 alpha-hydroxyprogesterone, 20 alpha-hydroxyprogesterone, testosterone and androstenedione could be analysed above the level of 5.0-7.5 ng/ml. The method was applied to the clinical appraisal of placental function and maturation of ovarian follicles.     

Role of anionic vacancies in lithium fluoride in the catalytic oxidation of carbon monoxide on the surface of the Au/LiF/Mo(110) system

The oxidation of carbon monoxide molecules on the surface of gold nanoclusters formed on a lithium fluoride film has been investigated by IR spectroscopy and temperature-programed reaction. The CO oxidation rate is much higher in the case of gold clusters produced on the surface of a LiF film enriched with anionic vacancies (F-centers). This is due to the fact that the gold clusters bonded to F-centers of the substrate differ in electronic state from the clusters that are not bonded to F-centers.     

Angle-resolved photoemission spectroscopy of the iron-chalcogenide superconductor Fe1.03Te0.7Se0.3: strong coupling behavior and the universality of interband scattering

We have performed angle-resolved photoemission spectroscopy of the iron-chalcogenide superconductor Fe1.03Te0.7Se0.3 to investigate the electronic structure relevant to superconductivity. We observed a holelike Fermi surface (FS) and an electronlike FS at the Brillouin zone center and corner, respectively, which are nearly nested by the Q～(π,π) wave vector. We do not find evidence for the nesting instability with Q～(π+δ,0) reminiscent of the antiferromagnetic order in the parent compound Fe1+yTe. We have observed an isotropic superconducting (SC) gap along the holelike FS with the gap size Δ of ～4 meV (2Δ/kBTc ～ 7), demonstrating the strong-coupling superconductivity. The observed similarity of low-energy electronic excitations between iron-chalcogenides and iron-arsenides strongly suggests that common interactions which involve Q～(π,π) scattering are responsible for the SC pairing.