The diluted aerosols from a cigarette (3R4F) and an e-cigarette (Vype ePen) were compared in two commercially available in vitro exposure systems: the Borgwaldt RM20S and Vitrocell VC10. Dosimetry was assessed by measuring deposited aerosol mass in the exposure chambers via quartz crystal microbalances, followed by quantification of deposited nicotine on their surface. The two exposure systems were shown to generate the same aerosols (pre-dilution) within analytically quantified nicotine concentration levels (p = 0.105). The dosimetry methods employed enabled assessment of the diluted aerosol at the exposure interface. At a common dilution, the per puff e-cigarette aerosol deposited mass was greater than cigarette smoke. At four dilutions, the RM20S produced deposited mass ranging 0.1–0.5 µg/cm2/puff for cigarette and 0.1–0.9 µg/cm2/puff for e-cigarette; the VC10 ranged 0.4–2.1 µg/cm2/puff for cigarette and 0.3–3.3 µg/cm2/puff for e-cigarette. In contrast nicotine delivery was much greater from the cigarette than from the e-cigarette at a common dilution, but consistent with the differing nicotine percentages in the respective aerosols. On the RM20S, nicotine ranged 2.5–16.8 ng/cm2/puff for the cigarette and 1.2–5.6 ng/cm2/puff for the e-cigarette. On the VC10, nicotine concentration ranged 10.0–93.9 ng/cm2/puff for the cigarette and 4.0–12.3 ng/cm2/puff for the e-cigarette. The deposited aerosol from a conventional cigarette and an e-cigarette in vitro are compositionally different; this emphasises the importance of understanding and characterising different product aerosols using dosimetry tools. This will enable easier extrapolation and comparison of pre-clinical data and consumer use studies, to help further explore the reduced risk potential of next generation nicotine products.
Graphical abstract A cigarette and an e-cigarette (top left) were assessed on two different in vitro exposure systems, the Borgwaldt RM20S (top right) and the VC 10 (bottom right). Compositionally the product aerosols were different, but there was no difference between the same product on different machines (bottom left).
In this paper, we describe a two-stage method for solving optimization problems with bound constraints. It combines the active-set estimate described in Facchinei and Lucidi (J Optim Theory Appl 85(2):265–289, 1995) with a modification of the non-monotone line search framework recently proposed in De Santis et al. (Comput Optim Appl 53(2):395–423, 2012). In the first stage, the algorithm exploits a property of the active-set estimate that ensures a significant reduction in the objective function when setting to the bounds all those variables estimated active. In the second stage, a truncated-Newton strategy is used in the subspace of the variables estimated non-active. In order to properly combine the two phases, a proximity check is included in the scheme. This new tool, together with the other theoretical features of the two stages, enables us to prove global convergence. Furthermore, under additional standard assumptions, we can show that the algorithm converges at a superlinear rate. Promising experimental results demonstrate the effectiveness of the proposed method. 相似文献
Structural and energetic features of a series of 15 diarylhydrazone derivatives were studied via density functional theory (DFT) in order to identify the key features that most likely contribute to their antioxidant effect. Theoretical calculations were carried out at the B3LYP/6-31G(d,p) level. The calculated physicochemical parameters included the ionization potential, N-H dissociation enthalpy, proton affinity, HOMO/LUMO energies, and the band gaps of the most stable conformation of the compounds. To assess the contribution of these factors to the in vitro activity, the compounds were synthesized and their antioxidant activity was also determined in three commonly used assays. The hydrazones were evaluated for their radical scavenging against the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), and peroxyl (ORAC assay) radicals. The experimental radical scavenging data of the compounds have been then plotted against the physicochemical characteristics and based on the obtained fits conclusions have been drawn regarding the relative importance of the respective factors. 相似文献
We investigated the thermo- rheological behavior of high glass transition, high molecular weight and small dynamic asymmetry
blends of poly(styrene-co-maleic anhydride) (SMA) and poly (methyl methacrylate) (PMMA) with varying amounts of maleic anhydride (MA) content, namely
8 wt%, 14 wt% and 32 wt%, in the SMA component. The phase separation (binodal) temperature of each blend was determined rheologically
using a combination of dynamic frequency and temperature sweeps in parallel plate geometry; it was marked by a change in slope
of the elastic modulus and the occurrence of a peak in tan δ in temperature sweeps. Failure of the time-temperature superposition
principle and observation of two peaks in the Cole-Cole plots corroborated these findings. The blends displayed lower critical
solution temperature (LCST) behavior with the critical temperatures exhibiting a non-monotonic dependence on the MA content.
From rheological and thermal measurements it was concluded that SMA/PMMA blends containing 14% MA were more miscible than
those containing 8% or 32% MA, a finding attributed to the compositional dependence of the interplay between SMA-SMA and SMA-PMMA
interactions in the different samples. MA also influenced the dynamic asymmetry and pretransitional concentration fluctuations.
The phase diagrams corresponding to each blend were modeled using a two-parameter temperature dependent interaction parameter,
based on the concept of generalized Gibbs free energy of mixing. The fitted values of interaction parameter were in good agreement
with values calculated explicitly using the Flory-Huggins theory.
Received: 16 February 2001 Accepted: 11 July 2001 相似文献
For a large class of Cantor sets on the real-line, we find sufficient and necessary conditions implying that a set has positive (resp. null) measure for all doubling measures of the real-line. We also discuss same type of questions for atomic doubling measures defined on certain midpoint Cantor sets. 相似文献
NAI-112, a glycosylated, labionine-containing lanthipeptide with weak antibacterial activity, has demonstrated analgesic activity in relevant mouse models of nociceptive and neuropathic pain. However, the mechanism(s) through which NAI-112 exerts its analgesic and antibacterial activities is not known. In this study, we analyzed changes in the spinal cord lipidome resulting from treatment with NAI-112 of naive and in-pain mice. Notably, NAI-112 led to an increase in phosphatidic acid levels in both no-pain and pain models and to a decrease in lysophosphatidic acid levels in the pain model only. We also showed that NAI-112 can form complexes with dipalmitoyl-phosphatidic acid and that Staphylococcus aureus can become resistant to NAI-112 through serial passages at sub-inhibitory concentrations of the compound. The resulting resistant mutants were phenotypically and genotypically related to vancomycin-insensitive S. aureus strains, suggesting that NAI-112 binds to the peptidoglycan intermediate lipid II. Altogether, our results suggest that NAI-112 binds to phosphate-containing lipids and blocks pain sensation by decreasing levels of lysophosphatidic acid in the TRPV1 pathway. 相似文献