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Amines at typical atmospheric concentrations of a only few molecules per trillion air molecules combine with sulphuric acid to form highly stable aerosol particles at rates similar to those observed in the lower atmosphere. Atmospheric chemistry of anthropogenic amines Amines emitted into the atmosphere from anthropogenic sources are thought to enhance nucleation from trace atmospheric vapours, stimulate particle formation and influence the development and properties of clouds. Direct evidence for this under atmospheric conditions has been lacking; however, this study, using the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN, demonstrates that amines at atmospherically relevant concentrations can sufficiently increase nucleation rates to be able to account for the particle formation rates observed in the atmospheric environment. Nucleation of aerosol particles from trace atmospheric vapours is thought to provide up to half of global cloud condensation nuclei 1 . Aerosols can cause a net cooling of climate by scattering sunlight and by leading to smaller but more numerous cloud droplets, which makes clouds brighter and extends their lifetimes 2 . Atmospheric aerosols derived from human activities are thought to have compensated for a large fraction of the warming caused by greenhouse gases 2 . However, despite its importance for climate, atmospheric nucleation is poorly understood. Recently, it has been shown that sulphuric acid and ammonia cannot explain particle formation rates observed in the lower atmosphere 3 . It is thought that amines may enhance nucleation 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , but until now there has been no direct evidence for amine ternary nucleation under atmospheric conditions. Here we use the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN and find that dimethylamine above three parts per trillion by volume can enhance particle formation rates more than 1,000-fold compared with ammonia, sufficient to account for the particle formation rates observed in the atmosphere. Molecular analysis of the clusters reveals that the faster nucleation is explained by a base-stabilization mechanism involving acid–amine pairs, which strongly decrease evaporation. The ion-induced contribution is generally small, reflecting the high stability of sulphuric acid–dimethylamine clusters and indicating that galactic cosmic rays exert only a small influence on their formation, except at low overall formation rates. Our experimental measurements are well reproduced by a dynamical model based on quantum chemical calculations of binding energies of molecular clusters, without any fitted parameters. These results show that, in regions of the atmosphere near amine sources, both amines and sulphur dioxide should be considered when assessing the impact of anthropogenic activities on particle formation.

Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations.

Cloud cover at CERN A substantial source of cloud condensation nuclei in the atmospheric boundary layer is thought to originate from the nucleation of trace sulphuric acid vapour. Despite extensive research, we still lack a quantitative understanding of the nucleation mechanism and the possible role of cosmic rays, creating one of the largest uncertainties in atmospheric models and climate predictions. Jasper Kirkby and colleagues present the first results from the CLOUD experiment at CERN, which studies nucleation and other ion-aerosol cloud interactions under precisely controlled conditions. They find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume increase the nucleation rate of sulphuric acid particles by more than a factor of 100 to 1,000. They also find that ion-induced binary nucleation of H 2 SO 4 –H 2 O can occur in the mid-troposphere, but is negligible in the boundary layer and so additional species are necessary. Even with the large enhancements in rate caused by ammonia and ions, they conclude that atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary layer nucleation. Atmospheric aerosols exert an important influence on climate 1 through their effects on stratiform cloud albedo and lifetime 2 and the invigoration of convective storms 3 . Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours 4 , although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small 5 , 6 . Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia 7 . Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100–1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H 2 SO 4 –H 2 O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation.

The large diffusion coefficients of sub-10 nm aerosol have posed a long-standing challenge to the aerosol community; to understand nucleation and early growth, there is a need for methods such as those presented here that transmit a strong, high resolution signal of classified charged aerosol to the detector. I introduce a framework for comparison of the Flagan Laboratory classifiers to other instruments, and I show why our instruments perform favorably relative to these alternatives. Reducing the size of the classification region reduces the effect of diffusion on performance and will ultimately enable the development of personal health monitors. The deployment of our instruments to the Cosmics Leaving OUtdoor Droplets experiment at CERN motivated a deeper look into detector performance and design for extreme operating conditions. I caution about the possible interference of ion nucleation with measurements and introduce a process for optimizing detector performance at arbitrary temperature. My experience with aerosol classifications has inspired the invention of separation methods for related fields; I conclude by describing methods for the high resolution separation of gas ions and of aqueous particles such as proteins and antibodies.

Take the movement of Global Business Services (GBS) as an example, where organizations centralize and often develop large scale outsourcing contracts for facilities management, finance, IT and procurement. In a transaction-based model, the buyer likely will not get any value beyond cost savings, as many RFx methods focus only on price according to the specification of what is being asked for. Requests for proposal are used for larger, more complex and technical solicitations where selection is based on factors beyond just price or cost, such as technical capability, capacity and potential shared design with the supplier. A request for partner is typically focused on selecting a supplier where there is a need for a high level of investment or collaboration between the buyer/ company over a longer time horizon-such as a large outsourcing project that will require significant change for the buyer and supplier versus implementation of a more standard

The reactions of PhBCl 2 with Li[CE(N t Bu)( n Bu)] or Li[CS(N t Bu)(NH t Bu)] (1:1 molar ratio) in toluene at 23°C produced the heterocycles Ph(Cl)B( -N t Bu)( -E)C( n Bu) ( 1a , E = N t Bu; 1b , E = O; 1c , E = S) or Ph(Cl)B( -N t Bu)( -S)C(NH t Bu) ( 2 ), which were characterized by 1 H, 11 B and 13 C NMR and by mass spectra. X-ray structural determinations revealed that 1a , 1c and 2 contain four-membered rings. In 2 the thioamidate ligand adopts an N,S bonding mode. Crystal data: 1a , monoclinic, space group P2 1 , a = 8.816(3), b = 11.311(2), c = 10.168(3) Å, = 98.86(3)°, V = 1001.7(5) Å 3 , Z = 2, R = 0.042, and R w = 0.020; 1c , monoclinic, space group P2 1 /n, a = 7.617(2), b = 11.200(1), c = 19.568(2), = 90.74(2)°, V = 1669.1(5) Å 3 , Z = 4, R = 0.046, and R w = 0.059; 2 , monoclinic, space group P2 1 /a, a = 11.357(2), b = 12.289(2), c = 12.620(3) Å, = 95.43(2)°, V = 1753.4(5) Å 3 , Z = 4, R = 0.043, and R w = 0.027. Key words: boron, amidinate, oxoamidate, thioamidate, X-ray structures.

Metal injection molding (MIM) processes are generally more cost-effective for the generation of metallic AM components. However, the thermal processing required to remove the polymer and sinter the metal powder is not well understood in terms of resulting mechanical response and damage evolution, especially in ambient atmospheres where contamination is present. This study aims to provide a range of achievable mechanical properties of copper produced using a MIM-based method called fused filament fabrication (FFF) that is post-processed in a nonideal environment. These results showed direct correlations between sintering temperature to multiple aspects of material behavior. In addition, Nondestructive Evaluation (NDE) methods are leveraged to understand the variation in damage evolution that results from the processing, and it is shown that the higher sintering temperatures provided more desirable tensile properties for strength-based applications. Moreover, these results demonstrate a potential to tailor mechanical properties of FFF manufactured copper for a specific application.