Community Participation in Mine Action: A Review and Conceptual Framework

In line with the Norwegian People\u27s Aid (NPA) international strategy, which promotes a rights-based partnership approach, the NPA is committed to exploring new approaches to mine action that promote greater involvement of the local mine affected populations. A starting point in this process is a review and conceptual framework paper prepared for NPA by Ruth Bottomley. Through a review of existing documents, the paper provides a reflection on why community participation is important in mine action and outlines some of the challenges. Existing examples of community participation in mine action are compiled with documented strengths and weaknesses

Interactions of Water with Mineral Dust Aerosol: Water Adsorption, Hygroscopicity, Cloud Condensation, and Ice Nucleation

Mineral dust aerosol is one of the major types of aerosol present in the troposphere. The molecular level interactions of water vapor with mineral dust are of global significance. Hygroscopicity, light scattering and absorption, heterogneous reactivity and the ability to form clouds are all related to water–dust interactions. In this review article, experimental techniques to probe water interactions with dust and theoretical frameworks to understand these interactions are discussed. A comprehensive overview of laboratory studies of water adsorption, hygroscopicity, cloud condensation, and ice nucleation of fresh and atmspherically aged mineral dust particles is provided. Finally, we relate laboratory studies and theoretical simulations that provide fundemental insights into these processes on the molecular level with field measurements that illustrate the atmospheric significance of these processes. Overall, the details of water interactions with mineral dust are covered from multiple perspectives in this review article.United States. National Aeronautics and Space Administration (Grant NNX13AO15G)Massachusetts Institute of Technology. Victor P. Starr Career Development Chai

ClNO2 and nitrate formation via N2O5 uptake to particles: Derivation of N2O5 uptake coefficients from ambient datasets

Oral presentation abstract given at EGU General Assembly 2015.We present estimates of the uptake coefficient of N2O5 using ambient measurements of the trace gases N2O5 and ClNO2 and particle composition and surface area at the Kleiner Feldberg observatory, near Frankfurt, SW Germany, during the PARADE campaign (summer 2011). Three methods used to extract gamma(N2O5) from the datasets were found to be in reasonable agreement, generating values between 0.001 and 0.4. Gamma (N2O5) displayed a significant dependence on relative humidity (RH), the largest values obtained, as expected, at high RH. No significant dependence of gamma(N2O5) on particle organic content or sulphate-to-organic ratio was observed. The variability in gamma(N2O5) is however large, indicating that humidity is not the sole factor determining the uptake coefficient. There is also an indication that the yield of ClNO2 with respect to N2O5 uptake is larger with lower concentrations of PM1 total organics. Our results will be compared to existing uptake coefficients from laboratory studies and those derived from field observations.Max Planck Societ

Effects of NH3 and alkaline metals on the formation of particulate sulfate and nitrate in wintertime Beijing

Sulfate and nitrate from secondary reactions remain as the most abundant inorganic species in atmospheric particle matter (PM). Their formation is initiated by oxidation (either in gas phase or particle phase), followed by neutralization reaction primarily by NH3, or by other alkaline species such as alkaline metal ions if available. The different roles of NH3 and metal ions in neutralizing H2SO4 or HNO3, however, are seldom investigated. Here we conducted semi-continuous measurements of SO4 2−, NO3 −, NH4 +, and their gaseous precursors, as well as alkaline metal ions (Na+, K+, Ca2+, and Mg2+) in wintertime Beijing. Analysis of aerosol acidity (estimated from a thermodynamic model) indicated that preferable sulfate formation was related to low pH conditions, while high pH conditions promote nitrate formation. Data in different mass fraction ranges of alkaline metal ions showed that in some ranges the role of NH3 was replaced by alkaline metal ions in the neutralization reaction of H2SO4 and HNO3 to form particulate SO4 2− and NO3 −. The relationships between mass fractions of SO4 2− and NO3 − in those ranges of different alkaline metal ion content also suggested that alkaline metal ions participate in the competing neutralization reaction of sulfate and nitrate. The implication of the current study is that in some regions the chemistry to incorporate sulfur and nitrogen into particle phase might be largely affected by desert/fugitive dust and sea salt, besides NH3. This implication is particularly relevant in coastal China and those areas with strong influence of dust storm in the North China Plain (NCP), both of which host a number of megacities with deteriorating air quality

E3 ubiquitin ligase CHIP facilitates Toll-like receptor signaling by recruiting and polyubiquitinating Src and atypical PKCζ

In mouse macrophages and dendritic cells, the CHIP E3 ubiquitin ligase is needed for transduction of signals initiated by TLR4 and TLR9 stimulation

Atmospheric heterogeneous reactions of N 2 O 5 and NO 3 radicals with mineral dust particles

Die heterogenen Reaktionen von N2O5 bzw. NO3 auf mineralischen Staubpartikeln wurden untersucht, um deren Einfluss auf den Abbau atmosphärischer Stickoxide (NOx) sowie auf die chemische Veränderung der Staubpartikel während ihres Transportes durch die Atmosphäre besser verstehen zu können. Die experimentellen Studien wurden bei Atmosphärendruck, Raumtemperatur und unterschiedlichen relativen Luftfeuchten durchgeführt. Der Aufnahmekoeffizient γ(N2O5) von N2O5 auf dispergiertem Staub aus der Sahara wurde zu 0,020 ± 0,002 (1σ) bestimmt, unabhängig von der relativen Feuchte (0 - 67 %) sowie der N2O5-Konzentration (5x1011 - 3x1013 Moleküle cm-3).rnDie Analyse der Reaktionsprodukte in der Gasphase sowie auf der Partikeloberfläche führt zu der Annahme, dass N2O5 auf der Staubpartikeloberfläche zu Nitrat hydrolysiert wird. Es konnte kein Einfluss der relativen Feuchte auf den Aufnahmekoeffizienten ermittelt werden, was durch das vorhandene interlamellare Wasser, welches bis zu 10 % der Partikelmasse betragen kann, erklärbar ist. Der gemessene Wert des Aufnahmekoeffizienten ist unabhängig von der Eingangs-N2O5-Konzentration, was sich über die sehr große innere Oberfläche der Partikel erklären lässt. Dennoch ließ sich durch eine vorherige Konditionierung der Partikel mit gasförmigem HNO3, was eine Nitratanreicherung an der Oberfläche bewirkt, die Effizienz der N2O5-Aufnahme auf die Staubpartikel reduzieren. Zusätzliche Studien befassten sich mit der Bestimmung des Aufnahmekoeffizienten von N2O5 auf Illit-Partikeln und auf Teststaub aus Arizona. Bei einer relativen Luftfeuchte von 0 % wurden für γ(N2O5) Werte von 0,084 ± 0,019 (1σ) für Illit und von 0,010 ± 0,001 (1σ) für Arizona Teststaub ermittelt.rnUnter Anwendung einer neuartigen Messmethode, die auf der zeitgleichen Messung der Konzentrationsabnahme von NO3 und N2O5 relativ zueinander beruht, wurde das Verhältnis γ(NO3)/γ(N2O5) der Aufnahmekoeffizienten von NO3 und N2O5 auf Saharastaub zu 0,9 ± 0,4 (1σ) bestimmt. Dieser Wert war unabhängig von der relativen Feuchte, den NO3- und N2O5-Konzentrationen sowie der Reaktionszeit, obwohl eine Oberflächendeaktivierung für beide Spurenstoffe beobachtet wurde.The heterogeneous reactions of mineral dust particles with N2O5 and NO3 radicals have been investigated at atmospheric pressure, room temperature, and different relative humidities. These studies are important for evaluating the role of these reactions in the removal of NOx in the atmosphere and the chemical aging of dust particles during transport.rnThe uptake coefficient of N2O5, γ(N2O5), was determined to be 0.020±0.002 (1 σ) on dispersed Saharan dust particles, independent of relative humidities (0-67%) and initial N2O5 concentration (5×1011-3×1013 molecules cm-3). Gas-phase and particulate products analysis suggests that N2O5 undergoes heterogeneous hydrolysis on the dust surface, leading to the formation of particulate nitrate with a yield of about 2. The independence of γ(N2O5) on relative humidity is due to the large amount of internal water (up to >10% of the dust mass) contained by dust particles. The independence of γ(N2O5) on initial N2O5 concentration can be explained by availability of a large internal surface for dust particles. Nevertheless, the dust particles can be deactivated if the particulate nitrate reaches high levels resulting from exposure to HNO3(g). In addition, the uptake of N2O5 on Illite and Arizona Test dust was studied, and γ(N2O5) at RH=0% was determined to be 0.084±0.019 (1 σ) on Illite and 0.010±0.001 (1 σ) for Arizona Test Dust, respectively.rnUsing a novel relative rate method, the uptake coefficient ratio of NO3 to N2O5, γ(NO3)/γ(N2O5), was measured to be 0.9±0.4 (1 σ) on Saharan dust particles. This result was independent of relative humidity (0-70%), NO3 and N2O5 concentration, and reaction time, though surface deactivation was observed for both species. The uptake of NO3 radicals on mineral dust particles is proposed to proceed via the reaction of adsorbed NO3 with internal water contained by dust particles, leading to the formation of nitrate

A database for deliquescence and efflorescence relative humidities of compounds with atmospheric relevance

Deliquescence relative humidity (DRH) and efflorescence relative humidity (ERH), the two parameters that regulate phase state and hygroscopicity of substances, play important roles in atmospheric science and many other fields. A large number of experimental studies have measured the DRH and ERH values of compounds with atmospheric relevance, but these values have not yet been summarized in a comprehensive manner. In this work, we develop for the first-of-its-kind a comprehensive database which compiles the DRH and ERH values of 110 compounds (68 inorganics and 42 organics) measured in previous studies, provide the preferred DRH and ERH values at 298 K for these compounds, and discuss the effects of a few key factors (e.g., temperature and particle size) on the measured DRH and ERH values. In addition, we outline future work that will broaden the scope of this database and enhance its accessibility

Measurements of HO2 uptake coefficient on aqueous (NH4)(2)SO4 aerosol using aerosol flow tube with LIF system

Laboratory studies of HO2 uptake coefficients, gamma(HO2), were conducted at room temperature using an aerosol flow tube coupled with a laser induced fluorescence (LIF) system. The measurement was conducted with atmospherically relevant HO2 concentrations (similar to 1 x 10(9) molecule/cm(3)) at 51% RH. The measured gamma(HO2) onto aqueous (NH4)(2)SO4 aerosol was 0.001 +/- 0.0007, which was consistent with the relatively low first-order loss rate of HO2 onto aqueous (NH4)(2)SO4 aerosol. The gamma(HO2) was elevated with increase of Cu(II) concentrations in aqueous (NH4)(2)SO4 aerosol. The threshold of Cu(II) concentration was 10(-3) mol/L for the dramatic increase of gamma(HO2). It was found that gamma(HO2) reached 0.1 when Cu(II) concentration in aerosol was larger than 10(-3) mol/L, suggesting that gamma(HO2) is very sensitive to concentration of transition metal ions in aerosol. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved