Online Speciation of Alkali Compounds by Temperature-Modulated Surface Ionization: Method Development and Application to Thermal Conversion

A novel method for online speciation of potassium- and sodium-containing compounds has been described and demonstrated. The method is based on a temperature-modulated surface ionization (TMSI) technique and may be used to determine the concentrations of alkali chlorides, hydroxides, carbonates, and sulfates in high-temperature processes. The measurement device is a further development of a surface ionization detector (SID) commonly used for online alkali measurements in combustion, gasification, and pyrolysis research. Discrimination between sodium and potassium compounds is made possible by differences in their aerosol evaporation characteristics as a function of temperature combined with the desorption kinetics of alkali on a hot platinum filament. The method is evaluated in laboratory experiments with known alkali salt concentrations. An experimental procedure where the platinum filament in the SID is regularly shifted between three temperatures is concluded to provide sufficient selectivity and time resolution for common applications. The TMSI method is successfully applied to characterize the emission of alkali compounds during pyrolysis of pine wood. The emissions during low-temperature pyrolysis are dominated by KOH, while similar amounts of KOH and NaOH are subsequently emitted from the remaining char and ash. The ability of real-time characterization of individual sodium and potassium compounds opens up new means to understand and optimize solid fuel conversion of common fuels such as low-grade biomass, waste, and coal

Water Interactions with Acetic Acid Layers on Ice and Graphite

Adsorbed organic compounds modify the properties of environmental interfaces with potential implications for many Earth system processes. Here, we describe experimental studies of water interactions with acetic acid (AcOH) layers on ice and graphite surfaces at temperatures from 186 to 200 K. Hyperthermal D₂O water molecules are efficiently trapped on all of the investigated surfaces, with only a minor fraction that scatters inelastically after an 80% loss of kinetic energy to surface modes. Trapped molecules desorb rapidly from both μm-thick solid AcOH and AcOH monolayers on graphite, indicating that water has limited opportunities to form hydrogen bonds with these surfaces. In contrast, trapped water molecules bind efficiently to AcOH-covered ice and remain on the surface on the observational time scale of the experiments (60 ms). Thus, adsorbed AcOH is observed to have a significant impact on water–ice surface properties and to enhance the water accommodation coefficient compared to bare ice surfaces. The mechanism for increased water uptake and the implications for atmospheric cloud processes are discussed

Additional file 1 of Association of lymphocyte subsets and cytokines with bone metabolism: a retrospective, cross-sectional study

Additional file 1

Water Accommodation on Ice and Organic Surfaces: Insights from Environmental Molecular Beam Experiments

Water uptake on aerosol and cloud particles in the atmosphere modifies their chemistry and microphysics with important implications for climate on Earth. Here, we apply an environmental molecular beam (EMB) method to characterize water accommodation on ice and organic surfaces. The adsorption of surface-active compounds including short-chain alcohols, nitric acid, and acetic acid significantly affects accommodation of D₂O on ice. <i>n</i>-Hexanol and <i>n</i>-butanol adlayers reduce water uptake by facilitating rapid desorption and function as inefficient barriers for accommodation as well as desorption of water, while the effect of adsorbed methanol is small. Water accommodation is close to unity on nitric-acid- and acetic-acid-covered ice, and accommodation is significantly more efficient than that on the bare ice surface. Water uptake is inefficient on solid alcohols and acetic acid but strongly enhanced on liquid phases including a quasi-liquid layer on solid <i>n</i>-butanol. The EMB method provides unique information on accommodation and rapid kinetics on volatile surfaces, and these studies suggest that adsorbed organic and acidic compounds need to be taken into account when describing water at environmental interfaces

Adjusted odds ratios of pet keeping for asthma and allergies among children^a.

<p>Adjusted odds ratios of pet keeping for asthma and allergies among children<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197274#t003fn001" target="_blank">^a</a>.</p

Prevalence (n, %) of asthma and allergy among children with different pets keeping status.

<p>Prevalence (n, %) of asthma and allergy among children with different pets keeping status.</p

Demographic information, health outcomes and exposure to pets of the investigated population, n (%).

<p>Demographic information, health outcomes and exposure to pets of the investigated population, n (%).</p

Adjusted odds ratio of pet keeping for asthma and allergy among children when an avoidance behavior is adjusted^a.

<p>Adjusted odds ratio of pet keeping for asthma and allergy among children when an avoidance behavior is adjusted<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197274#t004fn001" target="_blank">^a</a>.</p

The dose-response relationship between pets keeping in home and allergies among children.

<p>¹Odds ratios are adjusted for gender, age, total household income, family allergic history, home location, home dampness and avoidance behavior. ² Furry pet: cats, dogs, rodents and birds.</p