ObjectiveTo review the available evidence evaluating the chemicals in refill solutions, cartridges, aerosols and environmental emissions of electronic cigarettes (e-cigarettes).MethodsSystematic literature searches were conducted to identify research related to e-cigarettes and chemistry using 5 reference databases and 11 search terms. The search date range was January 2007 to September 2013. The search yielded 36 articles, of which 29 were deemed relevant for analysis.ResultsThe levels of nicotine, tobacco-specific nitrosamines (TSNAs), aldehydes, metals, volatile organic compounds (VOCs), flavours, solvent carriers and tobacco alkaloids in e-cigarette refill solutions, cartridges, aerosols and environmental emissions vary considerably. The delivery of nicotine and the release of TSNAs, aldehydes and metals are not consistent across products. Furthermore, the nicotine level listed on the labels of e-cigarette cartridges and refill solutions is often significantly different from measured values. Phenolic compounds, polycyclic aromatic hydrocarbons and drugs have also been reported in e-cigarette refill solutions, cartridges and aerosols. Varying results in particle size distributions of particular matter emissions from e-cigarettes across studies have been observed. Methods applied for the generation and chemical analyses of aerosols differ across studies. Performance characteristics of e-cigarette devices also vary across and within brands.ConclusionsAdditional studies based on knowledge of e-cigarette user behaviours and scientifically validated aerosol generation and chemical analysis methods would be helpful in generating reliable measures of chemical quantities. This would allow comparisons of e-cigarette aerosol and traditional smoke constituent levels and would inform an evaluation of the toxicity potential of e-cigarettes.

Stilbazolium dimers were designed and synthesized in which methylene groups of different lengths link the two chromophores. The second-order nonlinear optical property has been detected from their Langmuir-Blodgett monolayers. Photocurrent generation as well as other photophysical properties such as absorption and fluorescence were investigated. Comparing the dimers with the stilbazolium monomer, we found strong second harmonic generation (SHG) signals and remarkable enhanced photoelectric conversion (PEC) quantum yields from 1,3-Bis [(E)-4-(2-(4-(N-methyl, N-octadecylamino) phenyl) ethenyl) pyridinyl]-alkane dibromide (B3) and 1,5-Bis [(E)-4-(2-(4-(N-methyl, N-octadecylamino) phenyl) ethenyl) pyridinyl]-alkane dibromide (B5). The structures of the Langmuir-Blodgett films of these dyes are assumed. Although these dimers are center-symmetric (or quasi-center-symmetric) molecules, they can form the ordered non-center-symmetric (in normal direction) monolayer by the compress force and the molecular interaction between the amphiphilic dye molecules and the water molecules at the air/water interface. The influences of bias, donor/acceptor, soluble oxygen, and light intensity to photocurrent generation were studied; our results provide a new perspective to improve the performance of functional molecular material without any change of the chemical structure of the chromophore itself.

Stilbazolium dimers were designed and synthesized in which methylene groups of different lengths link the two chromophores. The second-order nonlinear optical property has been detected from their LangmuirBlodgett monolayers. Photocurrent generation as well as other photophysical properties such as absorption and fluorescence were investigated. Comparing the dimers with the stilbazolium monomer, we found strong second harmonic generation (SHG) signals and remarkable enhanced photoelectric conversion (PEC) quantum yields from 1,3-BisThe structures of the Langmuir-Blodgett films of these dyes are assumed. Although these dimers are center-symmetric (or quasi-center-symmetric) molecules, they can form the ordered non-center-symmetric (in normal direction) monolayer by the compress force and the molecular interaction between the amphiphilic dye molecules and the water molecules at the air/water interface. The influences of bias, donor/acceptor, soluble oxygen, and light intensity to photocurrent generation were studied; our results provide a new perspective to improve the performance of functional molecular material without any change of the chemical structure of the chromophore itself.

Stilbazolium dimers were designed and synthesized in which methylene groups of different lengths link the two chromophores. The second-order nonlinear optical property has been detected from their Langmuir-Blodgett monolayers. Photocurrent generation as well as other photophysical properties such as absorption and fluorescence were investigated. Comparing the dimers with the stilbazolium monomer, we found strong second harmonic generation (SHG) signals and remarkable enhanced photoelectric conversion (PEC) quantum yields from 1,3-Bis [(E)-4-(2-(4-(N-methyl, N-octadecylamino) phenyl) ethenyl) pyridinyl]-alkane dibromide (B3) and 1,5-Bis [(E)-4-(2-(4-(N-methyl, N-octadecylamino) phenyl) ethenyl) pyridinyl]-alkane dibromide (B5). The structures of the Langmuir-Blodgett films of these dyes are assumed. Although these dimers are center-symmetric (or quasi-center-symmetric) molecules, they can form the ordered non-center-symmetric (in normal direction) monolayer by the compress force and the molecular interaction between the amphiphilic dye molecules and the water molecules at the air/water interface. The influences of bias, donor/acceptor, soluble oxygen, and light intensity to photocurrent generation were studied; our results provide a new perspective to improve the performance of functional molecular material without any change of the chemical structure of the chromophore itself.

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