Pacific Northwest National Laboratory

About: Pacific Northwest National Laboratory is a facility organization based out in Richland, Washington, United States. It is known for research contribution in the topics: Catalysis & Aerosol. The organization has 11581 authors who have published 27934 publications receiving 1120489 citations. The organization is also known as: PNL & PNNL.

The time evolution of aerosol composition over the Mexico City plateau

Abstract: The time evolution of aerosol concentration and chemical composition in a megacity urban plume was determined based on 8 flights of the DOE G-1 aircraft in and downwind of Mexico City during the March 2006 MILAGRO field campaign. A series of selection criteria are imposed to eliminate data points with non-urban emission influences. Biomass burning has urban and non-urban sources that are distinguished on the basis of CH 3 CN and CO. In order to account for dilution in the urban plume, aerosol concentrations are normalized to CO which is taken as an inert tracer of urban emission, proportional to the emissions of aerosol precursors. Time evolution is determined with respect to photochemical age defined as −Log 10 (NO x /NO y ). The geographic distribution of photochemical age and CO is examined, confirming the picture that Mexico City is a source region and that pollutants become more dilute and aged as they are advected towards T1 and T2, surface sites that are located at the fringe of the City and 35 km to the NE, respectively. Organic aerosol (OA) per ppm CO is found to increase 7 fold over the range of photochemical ages studied, corresponding to a change in NO x /NO y from nearly 100% to 10%. In the older samples the nitrate/CO ratio has leveled off suggesting that evaporation and formation of aerosol nitrate are in balance. In contrast, OA/CO increases with age in older samples, indicating that OA is still being formed. The amount of carbon equivalent to the deduced change in OA/CO with age is 56 ppbC per ppm CO. At an aerosol yield of 5% and 8% for low and high yield aromatic compounds, it is estimated from surface hydrocarbon observations that only ~9% of the OA formation can be accounted for. A comparison of OA/CO in Mexico City and the eastern U.S. gives no evidence that aerosol yields are higher in a more polluted environment.

Abundant Metals Give Precious Hydrogenation Performance

Abstract: Homogeneous catalysts based on precious metals have enabled highly selective synthesis of organic compounds. Precious metal catalysts including ruthenium (Ru), rhodium (Rh), and platinum (Pt) have been superstars of both homogeneous and heterogeneous catalysis. In recent years, increasing efforts have been devoted to the design and discovery of homogeneous catalysts that incorporate base metals, such as iron (Fe) and cobalt (Co) ( 1 – 3 ) (see the figure). Catalytic hydrogenations are one of the extraordinary success stories of homogeneous catalysis, and three reports in this issue describe remarkable progress in the use of Earth-abundant metals as catalysts for hydrogenations. Hydrogenations are conceptually simple—H2 is added across a C=C or C=O double bond—but mechanistic studies have revealed considerable complexity with respect to how the metal catalyzes hydrogenations ( 4 ). On page 1080, Zuo et al. ( 5 ) report iron catalysts for asymmetric hydrogenation of C=O bonds. On page 1076, cobalt catalysts for asymmetric hydrogenation of C=C bonds are described by Friedfeld et al. ( 6 ). On page 1073, Jagadeesh et al. ( 7 ) report on nanoscale iron catalysts for synthesis of functionalized anilines through hydrogenation of nitroarenes.

Cognitive science implications for enhancing training effectiveness in a serious gaming context

Abstract: Serious games use entertainment principles, creativity, and technology to meet government or corporate training objectives, but these principles alone will not guarantee that the intended learning will occur. To be effective, serious games must incorporate sound cognitive, learning, and pedagogical principles into their design and structure. In this paper, we review cognitive principles that can be applied to improve the training effectiveness in serious games and we describe a process we used to design improvements for an existing game-based training application in the domain of cyber security education.

Real-time mass spectrometric characterization of the solid-electrolyte interphase of a lithium-ion battery.

Abstract: The solid–electrolyte interphase (SEI) dictates the performance of most batteries, but the understanding of its chemistry and structure is limited by the lack of in situ experimental tools. In this work, we present a dynamic picture of the SEI formation in lithium-ion batteries using in operando liquid secondary ion mass spectrometry in combination with molecular dynamics simulations. We find that before any interphasial chemistry occurs (during the initial charging), an electric double layer forms at the electrode/electrolyte interface due to the self-assembly of solvent molecules. The formation of the double layer is directed by Li+ and the electrode surface potential. The structure of this double layer predicts the eventual interphasial chemistry; in particular, the negatively charged electrode surface repels salt anions from the inner layer and results in an inner SEI that is thin, dense and inorganic in nature. It is this dense layer that is responsible for conducting Li+ and insulating electrons, the main functions of the SEI. An electrolyte-permeable and organic-rich outer layer appears after the formation of the inner layer. In the presence of a highly concentrated, fluoride-rich electrolyte, the inner SEI layer has an elevated concentration of LiF due to the presence of anions in the double layer. These real-time nanoscale observations will be helpful in engineering better interphases for future batteries. An operando mass spectrometry technique, along with molecular dynamics simulations, unveils the evolution of the solid–electrolyte interphase chemistry and structure in lithium-ion batteries during the first cycle.