Gel permeation chromatography of oxygenated components of cigarette smoke condensate

Oxygenated neutral constituents of a tumor-inhibiting fraction of cigarette smoke condensate were separated from interfering phenolic compounds by a combination of silicic acid and gel chromatography. Silicic acid adsorption and Bio-Beads gel chromatography separated aliphatic from aromatic ketones, and gel chromatography on Sephadex LH-20 resolved aromatic ketones from phenols. Identifications were achieved by studying individual fractions by g.c. and g.c.—m.s.     

Sensitive spectrophotometric determination of aluminium using thermal lens spectrometry

The determination of Al³⁺ in solution using a continuous-wave mode mismatched thermal lens spectrometer is reported and two spectrophotometric procedures are compared. The reagent investigated were bromopyrogallol red—tetradecyltrimethylammonium bromide (BPR—TDTA) and chrome azurol S—cetylpyridinium chloride (CAS—CPC). The CAS—CPC system gave a superior detection limit (0.17 μg 1^?1) to the BPR—TDTA system (1.15 mg 1^?1) owing to the higher reagent blanks and concomitant laser noise in the latter system.     

Carbon nanotube stabilised emulsions for electrochemical synthesis of porous nanocomposite coatings of poly[3,4-ethylene-dioxythiophene

The amphiphobic nature of carbon nanotubes allows them to stabilise droplets of water-insoluble monomers dispersed in the aqueous nanotube suspension, leading to a flexible route to electrochemical synthesis of useful nanoporous composites of nanotube doped conducting polymers, and potentially to other chemistry involving reactants incompatible in the same medium.     

Current pulse measurement of capacitance during molten salt electrochemical experiments

In earlier work in our laboratories, a current pulse method was developed that allows in situ (dynamic) measurements of electrode capacitance. The present work describes the successful application of the technique to the study of electrode properties in molten salt electrolytes. As expected, the electrode capacitance increases as the electrode surface area exposed to a molten salt bath increases. Furthermore, creep of the bath along the surface of a conductive ceramic anode and subsequent ingress into the anode pores is observed as an increase in capacitance. The pulse technique also gives an indication of phase changes that occur during the reduction of a solid titanium dioxide cathode and a highly sensitive measure of the temperature at which initial freezing of the calcium chloride electrolyte begins. These observations provide useful in situ information about changes in electrode properties in molten salt electrolytes that are difficult to obtain from other techniques. For consideration in the Special Edition: Oldham Festchrift Dedicated to our dear friend Keith B. Oldham on the occasion of his 80th birthday.     

Coverage-dependent adsorption of atomic sulfur on Fe(110): a DFT study

Adsorption of atomic sulfur at different coverages on the Fe(110) surface is examined using density functional theory (DFT) in order to investigate the effect that adsorbate-adsorbate interactions may have on the surface properties. S is adsorbed in the high-symmetry adsorption sites: 4-fold hollow, bridge, and atop sites in the following surface arrangements: c(2 x 2) and p(1 x 1) which correspond to coverages of 1/2 and 1 monolayer, respectively. The binding energy, work function change, adsorption geometry, charge density distribution, magnetic properties, and density of states are examined and compared to our previous study of S adsorbed at 1/4 monolayer coverage and p(2 x 2) arrangement [Spencer et al. Surf. Sci. 2003, 540, 420]. It was found that S forms polar covalent bonds to the surface. The bonding goes from being S-Fe dominated at the low coverages to being S-S dominated at the higher coverages where the S atoms are located closer together on the surface and interact with each other.     

Gel elution of heterocyclic analogues of polynuclear aromatic hydrocarbons from bio-beads

The Chromatographic elution characteristics from Bio-Beads SX-12 gel are reported for a wide range of polynuclear aromatic hydrocarbons and some of the heterocyclic analogues with which they are frequently associated in the environment. The use of benzene as solvent allows absorption effects to take place on the gels in the absence of hydrogenbonding effects. The elutions observed are discussed in terms of the contribution of the heteroatom to the gel elution effects.     

Brownian dynamics studies of dilute dispersions

The method of brownian dynamics of used to study the non-equilibrium properties of very dilute colloids electrostatically stabilised in dilute aqueous electrolyte. It is assumed that the colloid is a monodisperse system of structureless spherical particles embedded in a hydrodynamic continuum. Although the particles are interacting electrostatically through a screened Coulomb potential, the dilution is such that effects arising from coupling of hydrodynamic flow can be ignore. Studies of the self-diffusion coefficient and van Howe functions show that after an initial period, during which the particles move essentially independently, the flow properties of the colloids are significantly different from those expected on the basis of free brownian motion.     

On morphologies of gold nanoparticles grown from molecular dynamics simulation

The authors use a newly fitted gold embedded atom method potential to simulate the initial nucleation, coalescence, and kinetic growth process of vapor synthesized gold nanoparticles. Overall the population statistics obtained in this work seemed to mirror closely recent experimental HREM observations by Koga and Sugawara [Surf. Sci. 529, 23 (2003)] of inert gas synthesized nanoparticles, in the types of nanoparticles produced and qualitatively in their observance ratio. Our results strongly indicated that early stage coalescence (sintering) events and lower temperatures are the mainly responsible for the occurrence of the Dh and fcc based morphologies, while "ideal" atom by atom growth conditions produced the Ih morphology almost exclusively. These results provide a possible explanation as to why the Dh to Ih occurrence ratio increases as a function of nanoparticle size as observed by Koga and Sugawara.     

Ab initio modelling of boron and nitrogen in diamond nanowires

In this study an analysis is presented of the bonding and structural properties of dehydrogenated and hydrogenated doped cylindrical diamond nanowires calculated using the Vienna Ab Initio Simulation Package, employing density functional theory within the generalized-gradient approximation. The dopants studied here have been inserted substitutionally along the axis of an infinite one-dimensional diamond nanowire and include the single-electron acceptor boron and the single-electron donor nitrogen. The doped nanowires have then been re-relaxed, and properties compared with the undoped structures. The structural properties of relaxed nanowires considered here include an examination bonding via the electron charge density, with the aim of providing a better understanding of the effects of dopants on the stability of diamond nanostructures and nanodevices.