Diffusion and convection of gaseous and fine particulate from a chimney

^** Email: ajm{at}maths.strath.ac.uk Particle dispersion from a high chimney is considered and anexpression for the subsequent concentration of the particulatedeposited on the ground is derived. We consider the generalcase wherein the effects of both diffusion and convection onthe steady state ground concentration of particulate are incorporated.Two key parameters emerge from this analysis: the ratio of diffusionto convection and the nondimensionalised surface mass transferrate. We also solve the inverse problem of recovering thesetwo parameters given the boundary concentration profile andprovide an estimate of the concentration flux above the chimneystack.     

Isomerization Study of Aryltropane Analogs of Cocaine

Isomerization of brain imaging agents aryltropane cocaine analogs have been examined by HPLC under chemical conditions similar to those encountered during radiolabeling.     

Voltage-pulsed and laser-pulsed atom probe tomography of a multiphase high-strength low-carbon steel

The differences in artifacts associated with voltage-pulsed and laser-pulsed (wavelength = 532 or 355 nm) atom-probe tomographic (APT) analyses of nanoscale precipitation in a high-strength low-carbon steel are assessed using a local-electrode atom-probe tomograph. It is found that the interfacial width of nanoscale Cu precipitates increases with increasing specimen apex temperatures induced by higher laser pulse energies (0.6-2 nJ pulse(-1) at a wavelength of 532 nm). This effect is probably due to surface diffusion of Cu atoms. Increasing the specimen apex temperature by using pulse energies up to 2 nJ pulse(-1) at a wavelength of 532 nm is also found to increase the severity of the local magnification effect for nanoscale M2C metal carbide precipitates, which is indicated by a decrease of the local atomic density inside the carbides from 68 ± 6 nm(-3) (voltage pulsing) to as small as 3.5 ± 0.8 nm(-3). Methods are proposed to solve these problems based on comparisons with the results obtained from voltage-pulsed APT experiments. Essentially, application of the Cu precipitate compositions and local atomic density of M2C metal carbide precipitates measured by voltage-pulsed APT to 532 or 355 nm wavelength laser-pulsed data permits correct quantification of precipitation.     

Triterpenoid acids and lactones from the leaves of Fadogia tetraquetra var. tetraquetra (Rubiaceae)

Four triterpenoids isolated from the leaves of Fadogia tetraquetra var. tetraquetra, 3beta-hydroxy-11alpha, 12alpha-epoxyoleanan-28,13beta-olide (1), 3beta-hydroxyurs-11-en-28,13beta-olide (2), oleanolic acid (3), and ursolic acid (4), were evaluated for their antiviral and antibacterial properties. Compound 4 showed potent activity against the Semliki Forest virus with an IC50 of 14.7 microM, but was also found to be significantly cytotoxic (68% reduction in cell viability after 24 hours exposure at 50 microM) towards baby hamster kidney (BHK21) host cells. A viability assay on the mammalian human hepatocellular carcinoma (Huh-7) cell line showed no significant effects on intracellular ATP content after 48 hours exposure to compounds 1-4 at this concentration. Compound 4 also inhibited Staphylococcus aureus (MIC 12.5 microM), but was inactive against Enterobacter aerogenes, Escherichia coli, and Pseudomonas aeruginosa. Compounds 1-3 were inactive against all tested bacterial strains at 50 microM concentration.     

A route to the fully substituted cyclopentane unit of viridenomycin using a tandem radical cyclisation-trapping strategy

A silicon-tethered intramolecular radical cyclisation, in tandem with a radical trapping with allyltri-n-butylstannane forms the basis of a new synthetic strategy to the cyclopentane core of the antitumoral antibiotic substance viridenomycin isolated from Streptomyces viridochromogenes and S. gannmycicus.     

Expansion solution for subsonic compressible flow

An expansion solution in the physical plane is developed for subsonic compressible fluid flow past an obstacle. Assuming that the stream is inviscid, isentropic, irrotational and steady, it is shown that the velocity potential may be expressed as a series of homogeneous Heun functions and radial distance terms. The basis of this analysis is Ludford's formal discussion of corresponding singularities in Bergman's Linear Integral Operator Method. A modification of these results permits reduction of the governing nonlinear partial differential equation to an ordinary, nonhomogeneous, linear differential equation. The expansion solution is compared with the Rayleigh-Janzen method and the Prandtl-Glauert theory. The comparison indicates that this expansion gives better results than other methods currently used. The simplicity and economy of this expansion solution facilitates direct practical application.     

An expert system for the choice of factors for a ruggedness test in liquid chromatography

Method validation is an important and costly step in the development of liquid chromatographic methods, especially for pharmaceutical samples. A ruggedness test is valuable for finding the analytical conditions which give the best performance. By varying the factors that influence method performance, it is possible to design a more rugged method before a study of reproducibility is started. The choice of the factors to test is important. An expert system is described for the selection of factors in ruggedness tests. The system proved satisfactory for 10 of the 11 cases of pharmaceutical formulations tested.     

The prediction of traffic noise using a scale model

This paper describes the development of means of using a scale model of a road and its surrounding urban environment to predict L_eq, L₁₀ and other measures of traffic noise. The model described is that of the Centre Scientifique et Technique du Batiment, Grenoble, France. The problems involved in the development include allowance for relative sound absorption between real life and the model situation, the constraints on the accuracy of the results due to noise source variations on the model and the effects of the finite size of the model.