Application of HPLC-Thermospray Flame AAS: Interaction Between Heavy Metals and Duckweed Chlorophyll

Thermospray nebulizer interfaced HPLC-Flame AAS was used to study the effect of heavy metals (Al, Cd, Cu, Hg and Zn) on the chlorophylls of duckweed. Flame AAS was used as a metal specific detector of HPLC. Study indicated that heavy metals promote the degradation of chlorophylls. No evidence of direct replacement of central magnesium with heavy metals was found.     

Production of Ions by Repetitive Breakdown of a Vacuum Gap

Zinc ion pulses with varying amplitudes up to 1 mA have been extracted from a vacuum discharge. Repetitive operation of the pulsed discharge at 5300 Hz was maintained for 24 min. Breakdown of the 0.4 mm vacuum gap was accomplished by ramp-charging a 270 pF capacitor connected across the gap until breakdown occurred, the capacitor then being discharged through the gap. Stable operation was maintained by feedback control of the electrode spacing. The anode was eroded at 10 mg/C by the discharge, with 65 percent of the anode material being deposited on the cathode in the form of a fiber.     

On the finiteness theorem of Siegel and Mahler concerning diophantine equations

In this paper we present a new proof, involving so-called nonstandard arguments, of Siegel's classical theorem on diophantine equations: Any irreducible algebraic equation f(x,y) = 0 of genus g > 0 admits only finitely many integral solutions. We also include Mahler's generalization of this theorem, namely the following: Instead of solutions in integers, we are considering solutions in rationals, but with the provision that their denominators should be divisible only by such primes which belong to a given finite set. Then again, the above equation admits only finitely many such solutions. From general nonstandard theory, we need the definition and the existence of enlargements of an algebraic number field. The idea of proof is to compare the natural arithmetic in such an enlargement, with the functional arithmetic in the function field defined by the above equation.     

The ground state of the Bose gas

The mathematical formalism describing the Bose gas at zero temperature is analysed with the aid of methods that have recently been successful in relativistic quantum field theory. First the spectrum conditions for an infinitely extended system are given and the algebra of observables and the algebra of field operators are defined. General properties of states over these algebras are discussed and theorems are given which connect the linked cluster property, translation invariance and the purity of the states. It is proved that pure states over the algebra of observables have the property of factorisable off-diagonal long range order. The class of quasi free states is defined and of these states those which are translation invariant and possess the linked cluster property are analysed. It is shown that this class of states contains a subclass of pure states of the Bogoliubov type and a subclass of states which are mixtures of non-translationally invariant pure states. The applications of these quasi free states to the interacting Bose gas are summarized.     

Linewidth Analysis of Spin Labels in Liquids: II. Experimental

This work demonstrates that homogeneous linewidths can be extracted from continuous wave electron paramagnetic resonance spectra and that they quantitatively agree with the predictions of existing relaxation theory. We suggest that relaxation theory can be used to predict experimental lineshapes provided that the simulations properly include sources of broadening. We have found that the rotational correlation times for spin labels in different percentages of glycerol/water mixtures are best modeled by a power law treatment for the viscosity, similar to that for translational diffusion. The translational diffusion coefficients themselves also have a power law dependence on the viscosity for glycerol/water mixtures. The linewidths were linearly dependent upon both the oxygen and the spin label concentration. The hyperfine splittings of all nuclei were observed to decrease linearly with increasing spin label concentration, completely at odds with existing theory which predicts a quadratic dependence upon concentration. The linear dependence was independent of hyperfine splitting until the magnitude of the hyperfine splitting was less than the homogeneous linewidth.     

Mass separator for radioactive isotopes

A new isotope separator has been designed, constructed, and put into routine operation for separation of ¹³³Xe providing a major advancement and significant cost reduction in preparation of this radioactive isotope. The design features and advantages are discussed that expedite high purity separation of relatively small quantities of this isotope. These advantages could be easily used to expedite separation of other shorter-lived radioactive isotopes.     

Characterization and Monitoring of Porous Media with Electrical Imaging: A Review

Transport in Porous Media - Electrical geophysical imaging is a widely used noninvasive technology for visualizing porous media at scales larger than individual pores. Originally developed for...     

Counting bridgeless graphs

Methods are developed for finding the number of unlabeled bridgeless or 2-line-connected graphs of any order. These methods are based on cycle index sums, but it is shown how to avoid explicit compution with cycle index sums by using suitable inversion techniques. Similar results are obtained for unlabeled bridgeless graphs by numbers of points and lines, and connected graphs by numbers of points and bridges. Corresponding results for labeled graphs are found as corollaries. When lines or bridges are required as enumeration parameters in the labeled case it is also shown how to obtain improved recurrence relations. The latter appear to have no analog for unlabeled graphs.