Analytic and numerical calculations of the formation of a sulphuric acid aerosol in the upper troposphere

Analytic and numerical calculations are performed on the production of sulphuric acid aerosol in conditions of a very large nucleation event observed in the upper troposphere. The numerical results feature a growing peak in the size distribution whose magnitude is reproduced well analytically, and are consistent with the observed particle number concentration at sizes greater than 25 nm (measured dry diameter), but suggest that most of the aerosol was at unobserved smaller sizes. Because of growth and coagulation, number concentrations of the aerosol rapidly become independent of the number initially nucleated, so that conclusions as to the nucleation process, either homogeneous or ion-induced nucleation, cannot easily be drawn from existing atmospheric observations. The final concentration is very insensitive to the magnitude of the SO₂ source, but, if condensation on, and coagulation with, a remnant background aerosol occurs, such nucleation events will be cut off for source magnitudes less than a specific value. Anthropogenic emissions of SO₂ which exceed this value can produce higher aerosol number concentrations in the atmosphere with consequences for the indirect effect of aerosols on the climate.     

Effects of thermal oxidation conditions of silicon electrodes on cathodic electrochemiluminescence of Ru(bpy)3 chelate

Hot electrons emitted from thin oxide film-coated heavily doped silicon electrodes by cathodic pulse polarization can induce electrochemiluminescence from luminophores. The intensity of electrochemiluminescence produced at the electrode surface is dependent on the features of thin oxide films formed by thermal oxidation. As a preliminary study, we investigated the effect of thermal oxide growth conditions on the intensity of electrochemiluminescence produced at these electrodes, such as oxidation atmospheres, oxidation temperature, oxidation time and pre-treatment of wafers, using ruthenium(II) tris-(2,2′-bipyridine) chelate as a model luminophore. Optimal oxidation conditions of heavily doped silicon electrodes were obtained for the generation of intense electrochemiluminescence at this kind of silicon electrodes.     

Endometrial cancer cell lines are sensitive to paclitaxel

We have previously reported a 24 fold difference in the cisplatin sensitivity and a 12 fold difference in carboplatin sensitivity of endometrial carcinoma cell lines. In this study as evaluate paclitaxel sensitivity of the same cell lines. We tested nine endometrial cancer cell lines with the 96-well plate clonogenic assay using limiting dilution. The chemosensitivity was expressed as IC50 value, the drug concentration causing 50% inhibition of clonogenic survival. IC50 values were obtained from dose-response curves after fitting the data to the linear quadratic equation. The IC50 values for paclitaxel were 0.49 - 2.3 nM showing only a 4.7 fold difference between various cell lines. No correlation could be demonstrated between in vitro paclitaxel and platinum analog sensitivities of endometrial adenocarcinoma cell lines. The variance in paclitaxel sensitivity of different cell lines was little. Our results suggest that endometrial adenocarcinoma cell lines tested with the same methods. The clinical efficacy of paclitaxel in the treatment of endometrial cancer should further be evaluated in clinical trials.     

Measurement of Particulate Carbon in Atmospheric Aerosol in Helsinki

By means of a simple optical apparatus the levels and variations of concentrations of elemental carbon in particles were measured. Additionally, relations between variations of elemental carbon, lead, sulfate, total suspended particle, and nitrate concentrations were studied. Calibration was performed on real samples analyzed by a wet chemical method.     

The effect of saturation fluctuations on droplet growth

In the atmosphere the saturation ratio of water vapour varies as a function of time and space. In the present study we have investigated the effects of fluctuations of saturation ratio on droplet (cloud condansation nuclei) growth by stochastic approach employing an advanced growth model for cloud droplets. In saturated mean conditions growth of cloud droplets is accelerated by the fluctuations of saturation ratio, and our results indicate that due to fluctuations some droplets are able to grow in undersaturated conditions. Stochastic fluctuations of saturation ratio result in appearance of bimodal particle-size distribution and this is one of the possible explanations for the observed two modal cloud droplet distribution.     

The use of mobile technology for online shopping and entertainment among older adults in Finland

Older adults are becoming an important market segment for all internet-based services, but few studies to date have considered older adults as online shoppers and users of entertainment media. Utilising the concept of life course, this article investigates the use of mobile technologies for online shopping and entertainment among consumers aged 55 to 74. The data were collected with a web-based survey completed by a panel of respondents representing Finnish television viewers (N = 322). The results reveal that consumers aged 55 to 74 use a smartphone or tablet to purchase products or services online as often as younger consumers. In contrast, listening to internet radio and watching videos or programmes online with a smartphone or tablet are most typical for younger male consumers. The results demonstrate that mobile-based online shopping is best predicted by age, higher education, and household type (children living at home), and use of entertainment media by age and gender.     

Detection Efficiency of a Water-Based TSI Condensation Particle Counter 3785

In this article we present observations on the detection efficiency of a recently developed TSI 3785 Water Condensation Particle Counter (WCPC). The instrument relies on activation of sampled particles by water condensation. The supersaturation is generated by directing a saturated airflow into a “growth tube,” in which the mass transfer of water vapor is faster than heat transfer. This results in supersaturated conditions with respect to water vapor in the centerline of a “growth tube.” In this study, the cut-off diameter, that is, the size, where 50% of the sampled particles are successfully activated, varied from 4 to 14 nm for silver particles as a function of temperature difference between the saturator and the growth tube. The solubility of the sampled particles to water played an important role in the detection efficiency. Cut-off diameters for ammonium sulphate and sodium chloride particles were 5.1 and 3.6–3.8 nm, respectively at nominal operation conditions. Corresponding cut-off diameter for hydrophobic silver particles was 5.8 nm.