Filling-in of the pseudogap in amorphous Mg—Bi alloys

The optical properties of amorphous Mg-Bi alloys have been studied in the near infrared and visible spectral regions. Amorphous Mg₃Bi₂ is found to be a semiconductor with a band gap of 0.152 ± 0.005 eV. Excess Mg or Bi in amorphous Mg₃ Bi₂ is shown to form localised states near the Fermi level which fill in the pseudogap. These results are inconsistent with the rigid band model proposed by Ferrier and Herrell.     

Uptake of mercury by caged crayfish

An in situ caged crayfish experiment was conducted in the Wabigoon River System, Ontario, Canada to determine the relative importance of food and water pathways for mercury accumulation in crayfish. Two groups of 160 crayfish were suspended in the water column; one at an ucontaminated site, the other at a location with highly elevated total mercury and methylmercury levels in water. Crayfish at each site were divided into two groups. Crayfish were fed either sucker flesh obtained from an uncontaminated lake (low mercury diet) or walleye flesh from contaminated Clay Lake, Ontario, Canada (high mercury diet). After 10 weeks crayfish at both sites fed the high mercury diet had over 20 times mercury accumulation compared to crayfish on the low mercury diet. There was no statistical effects due to sharply elevated water concentrations of total and methylmercury on mercury bodyburdens. This indicated that food was the dominant pathway for mercury accumulation in crayfish.     

The sequential analysis of long range fallout debris

A method for the determination of the principal radionuelides of Sr, Ba, Ce, Cs, Y, Zr, Nb, and W in single fallout samples containing bulk Si, Fe, and Ca is presented. The sample and added carriers are dissolved by fusion with sodium carbonate. The melt is leached first with hot water and then with hydrochloric acid. W and Cs are recovered from the water leach. Sr, Ba, Y, and the heavier rare earths appear in the hydrochloric acid leach. Ce is found in the leach residue and Nb in both the residue and the hydrochloric acid leach. The Zr and Nb in the residue are separated from Ce by absorption on an anion-exchanger from hydrochloric acid. The Zr and Nb in the hydrochloric acid leach are separated from Sr and Ba by precipitation of Sr and Ba as nitrates and then separated from Y and the heavier rare earths by absorption on the anion-exchanger. The combined Zr fractions are eluted with dilute hydrochloric acid and Nb with a hydrochloric-hydrofluoric acid mixture.     

The measurement of SO2 in power station plumes with differential lidar

The use of differential lidar for measuring SO₂ in plumes from fossil fuelled power stations is examined. The potential of the technique is investigated for the measurement of SO₂ close to power station stacks and in situations where the long range transport of emissions is important. Detection limits are discussed as a function of range and spatial resolution and it is shown theoretically that concentrations as low as 10 ppb at a range of 2 km should be measurable. Details of a prototype, computer controlled, differential lidar based on a tunable dye laser are given and its mode of operation described. Results from field experiments carried out at Drax power station in Yorkshire (UK) and Fawley Power Station in Hampshire (UK) are presented. For plumes of small diameter a deconvolution technique has been applied to obtain better spatial resolution of the plume structure.     

Poly-α-ester degradation studies. I. Introduction: Design and construction of equipment

The various types of polyester degradation known to occur at elevated temperature are briefly summarized with particular reference to features of potential diagnostic value. Although little is known of poly-α-ester degradation in particular, examination of work on other linear polyesters indicates the spectrum of analytical and kinetic information that will be needed to characterize the degradation of poly-α-esters of various structures. On the basis of this review, an apparatus has been designed which enables kinetic information to be simultaneously obtained by thermogravimetry, gas evolution analysis, and rheological studies of the residual polymer melt. In addition a gas sampling procedure enables twin-column gas-liquid chromatographic analysis to be carried out on the degradation products. Samples of the chromatographically separated degradation products are collected in a microcollector cell for infrared and mass spectrometric analysis. Other refinements include in-line filament and Curie-point pyrolysis techniques.     

Band absorption in nonhomogeneous,isotropically-scattering planetary atmospheres: theory and experiment

A computer program is developed which predicts the vertical distribution of an absorbing species in an isotropically-scattering, finite planetary atmosphere from measurements of the upwelling band radiance determined by a vertically traversing 2-channel radiometer. Comparison is made with experiment.     

Aryl trihydroxyborates: easily isolated discrete species convenient for direct application in coupling reactions

A conceptually and practically simple alternative approach to the use of arylboron species as the organometallic component in cross-coupling processes is described whereby trihydroxyborate salts are isolated and directly employed. The protocol derives practical benefit from the ease and convenience of the isolation and subsequent use of the discrete borate salts, eliminates the need for additional base, and aids the use of correct reaction stoichiometry.