Endothelial damage plays a key role in atherosclerosis and this is impacted upon by numerous risk factors including cigarette smoking. A potential measure to reduce the cardiovascular burden associated with smoking is to reduce smoke toxicant exposure. In an in vitro endothelial damage repair assay, endothelial cell migration was inhibited by cigarette smoke particulate matter (PM) generated from several cigarette types. This inhibition was reduced when cells were exposed to PM from an experimental cigarette with reduced smoke toxicant levels. As a number of toxicants induce oxidative stress and since oxidative stress may link cigarette smoke and endothelial damage, we hypothesized that PM effects were dependent on elevated cellular oxidants. However, although PM-induced cellular oxidant production could be inhibited by ascorbic acid or n-acetylcysteine, both these antioxidants were without effect on migration responses to PM. Furthermore, reactive oxygen species production, as indicated by dihydroethidium fluorescence, was not different in cells exposed to smoke from cigarettes with different toxicant levels. In summary, our data demonstrate that a cardiovascular disease-related biological response may be modified when cells are exposed to smoke containing different levels of toxicants. This appeared independent of the induction of oxidative stress.

The development and use of terahertz (THz) frequency spectroscopy systems for security screening has shown an increased growth over the past 15 years. In order to test these systems in real-world situations, safe simulants of illicit materials, such as Semtex-H, are required. Ideally, simulants should mimic key features of the material of interest, such that they at least resemble or even appear indistinguishable from the materials of interest to the interrogating technique(s), whilst not having hazardous or illicit properties. An ideal simulant should have similar physical properties (malleability, density, surface energy and volatility to the material of interest); be non-toxic and easy to clean and decontaminate from surfaces; be recyclable or disposable; and be useable in a public environment. Here, we present a method for developing such an explosive simulant (for Semtex-H) based on a database of THz spectra of common organic molecules, and the use of a genetic algorithm to select a mixture of compounds automatically to form such a simulant. Whilst we focus on a security application, this work could be applied to various other contexts, where the material of interest is dangerous, impractical or costly. We propose four mixtures that could then be used to test the spectral response of any instrument, working at terahertz frequencies, without the need for an explosive substance.

The synthesis of a novel, heterocyclic-telechelic polymer, -oxetanyl-telechelic poly(3-nitratomethyl-3-methyl oxetane), is described. Infra-red spectroscopy (IR), gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy have been used to confirm the successful synthesis, demonstrating the presence of the telechelic-oxetanyl moieties. Synthesis of the terminal functionalities has been achieved via displacement of nitrato groups, in a manner similar to that employed with other leaving groups such as azido, bromo and nitro, initiated by nucleophiles. In the present case, displacement occurs on the ends of a nitratofunctionalised polymer driven by the formation of sodium nitrate, which is supported by the polar aprotic solvent, N,N-dimethyl formamide. The formation of an alkoxide at the polymer chain ends is favoured and allows internal backbiting to the nearest carbon bearing the nitrato group, intrinsically in an SN1 reaction, leading to oxetanyl functionalisation. The telechelic-oxetanyl moieties have the potential to be cross-linked by chemical (e.g. acidic), or radiative (e.g. U.V.) curing methods without the use of high temperatures, usually below 100 o C. This type of material was designed for future use as a contraband simulant, whereby it would form the predominant constituent of elastomeric composites comprising rubbery polymer with small quantities of solids, typically crystals of contraband substances, such as explosives or narcotics. This method also provides an alternative approach to ringclosure and synthesis of heterocycles.

Explosives or energetic materials are hazardous, expensive and difficult to handle safely. As such there is a need for simulant explosive materials in order to conduct work without these issues being present. This chapter describes characterisation of a set of simulant materials with respect to millimetre wave and submillimetre wave threat detection technologies. The properties examined were the real and imaginary parts of the relative permittivity. The simulants are based on a modular approach to design appropriate chemical and physical properties which mimic explosives. Collectively, these materials are referred to as Hemtex and can be tailored to match various requirements. The subset of Hemtex materials used in this study were designed to reflect the properties of Semtex and the results of the characterisation showed promise for use as Semtex substitutes.