Secondary organic aerosol reduced by mixture of atmospheric vapours

Secondary organic aerosol contributes to the atmospheric particle burden with implications for air quality and climate. Biogenic volatile organic compounds such as terpenoids emitted from plants are important secondary organic aerosol precursors with isoprene dominating the emissions of biogenic volatile organic compounds globally. However, the particle mass from isoprene oxidation is generally modest compared to that of other terpenoids. Here we show that isoprene, carbon monoxide and methane can each suppress the instantaneous mass and the overall mass yield derived from monoterpenes in mixtures of atmospheric vapours. We find that isoprene 'scavenges' hydroxyl radicals, preventing their reaction with monoterpenes, and the resulting isoprene peroxy radicals scavenge highly oxygenated monoterpene products. These effects reduce the yield of low-volatility products that would otherwise form secondary organic aerosol. Global model calculations indicate that oxidant and product scavenging can operate effectively in the real atmosphere. Thus highly reactive compounds (such as isoprene) that produce a modest amount of aerosol are not necessarily net producers of secondary organic particle mass and their oxidation in mixtures of atmospheric vapours can suppress both particle number and mass of secondary organic aerosol. We suggest that formation mechanisms of secondary organic aerosol in the atmosphere need to be considered more realistically, accounting for mechanistic interactions between the products of oxidizing precursor molecules (as is recognized to be necessary when modelling ozone production).Peer reviewe

Structure and stability of small titanium/oxygen clusters studied by ab initio quantum chemical calculations

Ab initio calcns. have been performed on TinO2n-δ clusters, with n = 1-3 and δ = 0, 1, as well as on some of their ionized species. The geometries of the different clusters were optimized and vibrational analyses were performed at the ground-state equil. geometries. The Ti-O bond lengths are essentially detd. by the coordination nos. of the resp. atoms, independent of n. The clusters are characterized by having any low pendant oxygen vibrational frequencies. The ionization energies for the (TiO2)n clusters were significantly higher than those of oxygen-deficient, TinO2n-1, clusters. Some anomalous features of the n = 1 cluster, TiO2, as compared to clusters with n > 1, are discussed. Recent exptl. mass spectrometric observations on titanium oxide clusters are discussed in the light of the present findings

Theoretical study of lithium intercalation in rutile and anatase

Motivated by recent developments concerning coloration and energy storage in lithium intercalated nanostructural TiO2, quantum chem. Hartree-Fock calcns. have been carried out to study lithium atom intercalation in rutile and anatase. Equil. geometries and effective at. charge were obtained for the rutile (110) and anatase (101) clean surfaces. Li-induced local one-electron energy levels were found in the gap between the upper valence band and the conduction band and could be attributed to Ti3+ states. The absorption energies obtained are compared with available exptl. data. The equil. positions of the Li atom and its surrounding host atoms have been calcd. for both structures. The results predict a higher possibility of lithium intercalation in the anatase structure than in rutile

Mechanism of traditional Bogolan dyeing technique with clay on cotton fabric

International audienceBogolan is a traditional dyeing technique, deeply rooted in Mali. It uses local clays from Niger River region and a leave extract from N'galama trees (Anogeissus leiocarpa). The clay contains a significant amount of iron (hydr)oxides, mainly akaganeite. It reacts with N'galama coating onto cotton to form black or brown colors. UV/Vis and IR spectroscopy indicated very similar behavior of N'galama leaves extract and carboxylic aromatic acids, mainly ellagic or gallic acids, which form dark colored complexes with iron. Since iron (hydr)oxides are coated on clay mineral particles, they contribute to the fixation of the clay mineral particles and also cause the dark color. X-ray diffraction of oriented tissue and SEM observations confirmed the presence of clay particles attached on the fiber surface

Poly(ethylene glycol)-Containing Hydrogel Surfaces for Antifouling Applications in Marine and Freshwater Environments

This work describes the fabrication, characterization, and biological evaluation of a thin protein-resistant poly(ethylene glycol) (PEG)-based hydrogel coating for antifouling applications. The coating was fabricated by free-radical polymerization on silanized glass and silicon and on polystyrene-covered silicon and gold. The physicochemical properties of the coating were characterized by infrared spectroscopy, ellipsometry, and contact angle measurements. In particular, the chemical stability of the coating in artificial seawater was evaluated over a six-month period. These measurements indicated that the degradation process was slow under the test conditions chosen, with the coating thickness and composition changing only marginally over the period. The settlement behavior of a broad and diverse group of marine and freshwater fouling organisms was evaluated. The tested organisms were barnacle larvae (Balanus amphitrite), algal zoospores (Ulva linza), diatoms (Navicula perminuta), and three bacteria species (Cobetia marina, Marinobacter hydrocarbonoclasticus, and Pseudomonas fluorescens). The biological results showed that the hydrogel coating exhibited excellent antifouling properties with respect to settlement and removal. © 2008 American Chemical Society

The Prospective Studies of Atherosclerosis (Proof-ATHERO) Consortium: Design and Rationale

Atherosclerosis - the pathophysiological mechanism shared by most cardiovascular diseases - can be directly or indirectly assessed by a variety of clinical tests including measurement of carotid intima-media thickness, carotid plaque, -ankle-brachial index, pulse wave velocity, and coronary -artery calcium. The Prospective Studies of Atherosclerosis -(Proof-ATHERO) consortium (https://clinicalepi.i-med.ac.at/research/proof-athero/) collates de-identified individual-participant data of studies with information on atherosclerosis measures, risk factors for cardiovascular disease, and incidence of cardiovascular diseases. It currently comprises 74 studies that involve 106,846 participants from 25 countries and over 40 cities. In summary, 21 studies recruited participants from the general population (n = 67,784), 16 from high-risk populations (n = 22,677), and 37 as part of clinical trials (n = 16,385). Baseline years of contributing studies range from April 1980 to July 2014; the latest follow-up was until June 2019. Mean age at baseline was 59 years (standard deviation: 10) and 50% were female. Over a total of 830,619 person-years of follow-up, 17,270 incident cardiovascular events (including coronary heart disease and stroke) and 13,270 deaths were recorded, corresponding to cumulative incidences of 2.1% and 1.6% per annum, respectively. The consortium is coordinated by the Clinical Epidemiology Team at the Medical University of Innsbruck, Austria. Contributing studies undergo a detailed data cleaning and harmonisation procedure before being incorporated in the Proof-ATHERO central database. Statistical analyses are being conducted according to pre-defined analysis plans and use established methods for individual-participant data meta-analysis. Capitalising on its large sample size, the multi-institutional collaborative Proof-ATHERO consortium aims to better characterise, understand, and predict the development of atherosclerosis and its clinical consequences

A Large-Scale, Consortium-Based Genomewide Association Study of Asthma

BACKGROUND Susceptibility to asthma is influenced by genes and environment; implicated genes may indicate pathways for therapeutic intervention. Genetic risk factors may be useful in identifying subtypes of asthma and determining whether intermediate phenotypes, such as elevation of the total serum IgE level, are causally linked to disease. METHODS We carried out a genomewide association study by genotyping 10,365 persons with physician-diagnosed asthma and 16,110 unaffected persons, all of whom were matched for ancestry. We used random-effects pooled analysis to test for association in the overall study population and in subgroups of subjects with childhood-onset asthma (defined as asthma developing before 16 years of age), later-onset asthma, severe asthma, and occupational asthma. RESULTS We observed associations of genomewide significance between asthma and the following single-nucleotide polymorphisms: rs3771166 on chromosome 2, implicating IL1RL1/IL18R1 (P = 3x10(-9)); rs9273349 on chromosome 6, implicating HLA-DQ (P = 7x10(-14)); rs1342326 on chromosome 9, flanking IL33 (P = 9x10(-10)); rs744910 on chromosome 15 in SMAD3 (P = 4x10(-9)); and rs2284033 on chromosome 22 in IL2RB (P = 1.1x10(-8)). Association with the ORMDL3/GSDMB locus on chromosome 17q21 was specific to childhood-onset disease (rs2305480, P = 6x10(-23)). Only HLA-DR showed a significant genomewide association with the total serum IgE concentration, and loci strongly associated with IgE levels were not associated with asthma. CONCLUSIONS Asthma is genetically heterogeneous. A few common alleles are associated with disease risk at all ages. Implicated genes suggest a role for communication of epithelial damage to the adaptive immune system and activation of airway inflammation. Variants at the ORMDL3/GSDMB locus are associated only with childhood-onset disease. Elevation of total serum IgE levels has a minor role in the development of asthma