SummaryBackgroundSmoking cessation programmes delivered via mobile phone text messaging show increases in self-reported quitting in the short term. We assessed the effect of an automated smoking cessation programme delivered via mobile phone text messaging on continuous abstinence, which was biochemically verified at 6 months.MethodsIn this single-blind, randomised trial, undertaken in the UK, smokers willing to make a quit attempt were randomly allocated, using an independent telephone randomisation system, to a mobile phone text messaging smoking cessation programme (txt2stop), comprising motivational messages and behavioural-change support, or to a control group that received text messages unrelated to quitting. The system automatically generated intervention or control group texts according to the allocation. Outcome assessors were masked to treatment allocation. The primary outcome was self-reported continuous smoking abstinence, biochemically verified at 6 months. All analyses were by intention to treat. This study is registered, number ISRCTN 80978588.FindingsWe assessed 11 914 participants for eligibility. 5800 participants were randomised, of whom 2915 smokers were allocated to the txt2stop intervention and 2885 were allocated to the control group; eight were excluded because they were randomised more than once. Primary outcome data were available for 5524 (95%) participants. Biochemically verified continuous abstinence at 6 months was significantly increased in the txt2stop group (10·7% txt2stop vs 4·9% control, relative risk [RR] 2·20, 95% CI 1·80–2·68; p<0·0001). Similar results were obtained when participants that were lost to follow-up were treated as smokers (268 [9%] of 2911 txt2stop vs 124 [4%] of 2881 control [RR 2·14, 95% CI 1·74–2·63; p<0·0001]), and when they were excluded (268 [10%] of 2735 txt2stop vs 124 [4%] of 2789 control [2·20, 1·79–2·71; p<0·0001]). No significant heterogeneity was shown in any of the prespecified subgroups.InterpretationThe txt2stop smoking cessation programme significantly improved smoking cessation rates at 6 months and should be considered for inclusion in smoking cessation services.FundingUK Medical Research Council, Primary Care Research Networks.

The pi-pi interaction between pyrene molecules and single-walled carbon nanotubes (SWNTs) or multi-walled carbon nanotubes (MWNTs) was studied by fluorescence, FTIR, Raman spectroscopy and molecular simulation. The carbon nanotubes were incubated in pyrene solution and dried for characterization. A broadband fluorescence emission at 463 nm of the incubated samples was observed, which is similar to that of pyrene excimers but shifts to shorter wavelength. The typical FTIR bands of pyrene shift to lower wavenumbers in the incubated samples. D- and G-bands in Raman spectra of SWNTs also shift to low frequencies. All these spectroscopic evidences reveal the stronger pi-pi stacking interaction between the nanotubes and pyrene molecules over the pyrene dimers, which leads to the formation of pyrene-carbon nanotube complexes. The systems of SWNTs and pyrene molecules were also studied with molecular simulation. It was found from the binding energy calculation that a stronger interaction presents between the pyrene molecule and the nanotube. In addition, the simulation gives some structural information about the pyrene-nanotube complex, such as the staggered conformation of pyrene on nanotube. The effect of defects in carbon nanotube sidewall was also discussed.

Coulomb-explosion velocity-map imaging is a new and potentially universal probe for gas-phase chemical dynamics studies, capable of yielding direct information on (time-evolving) molecular structure. The approach relies on a detailed understanding of the mapping between initial atomic positions within the molecular structure of interest and the final velocities of the fragments formed via Coulomb explosion. Comprehensive on-the-fly ab initio trajectory studies of the Coulomb explosion dynamics are presented for two prototypical small molecules, formyl chloride and cis-1,2dichloroethene, in order to explore conditions under which reliable structural information can be extracted from fragment velocity-map images. It is shown that, for low parent ion charge states, the mapping from initial atomic positions to final fragment velocities is complex, and very sensitive to the parent ion charge state as well as many other experimental and simulation parameters. For high charge states, however, the mapping is much more straightforward and dominated by Coulombic interactions (moderated, if appropriate, by the requirements of overall spin conservation). This study proposes minimum requirements for the high-charge regime, highlights the need to work in this regime in order to obtain robust structural information from fragment velocity-map images, and suggests how quantitative structural information may be extracted from experimental data.Several new and exciting experimental techniques for probing isolated (i.e. gas phase) molecules with high spatial and temporal resolution have recently been developed, and are now sufficiently mature to provide fundamental insights into phenomena such as the time evolving coupled electron and nuclear dynamics of molecules immediately following photoexcitation. Examples include timeresolved photoelectron spectroscopy, 1-5 X-ray scattering, 6 electron diffraction 7-9 and transient X-ray absorption spectroscopies. [10][11][12] Key to each of these developments have been advances in the availability and the ease of use of ultrafast laser sources delivering femtosecond (fs), and sub-fs 13 pulses across broad regions of the electromagnetic spectrum. These techniques all come with attendant challenges, however. Scattering and absorption methods require relatively high sample number or column densities, which limits the range of gas-phase systems amenable to study. Timeresolved photoelectron spectroscopy is much more sensitive: each molecule that is photoionized reports directly via the ejected electron. However, as with each of these new techniques, any full analysis of the measured data is heavily dependent on the availability of similarly cutting-edge theory, e.g. electronic structure calculations for the states involved in both the pump and the probe steps, and proper treatment of the excited state dynamics encompassing any non-adiabatic couplings en route to the ultimate products.Coulomb explosion imaging (CEI) -and its more recent variant Coulomb explosion velocity-map imaging (CE-VMI) -is an...

We describe a newly upgraded instrument for measuring absolute total electron ionization crosssections over the energy range from 0 to 300 eV, and present cross-sections for nine previously unstudied molecules, as well as several small molecules for which comparison data is available. The measured cross-sections are compared with the predictions of the BEB model, and show reasonable agreement with the model, albeit peaking at higher electron energies than predicted by the model. We show that the maxima in the cross-sections follow an additivity model, such that the molecular cross-sections can be expressed as a sum over contributions from the constituent atoms. These contributions have been determined from a global fit to the data for all molecules studied, and allow maximum cross-sections to be predicted for molecules that have not been studied to date. We demonstrate the expected correlation between the maximum ionization cross-section and the molecular polarisability, and show that the atomic contributions to the cross-section show a similar dependence on the atomic polarisability. The observed correlation can be used as an alternative method for predicting unknown maximum cross-sections.