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.

Development of a low-temperature photoelectron spectroscopy instrument using an electrospray ion source and a cryogenically controlled ion trap.

Abstract: The ability to control ion temperatures is critical for gas phase spectroscopy and has been a challenge in chemical physics. A low-temperature photoelectron spectroscopy instrument has been developed for the investigation of complex anions in the gas phase, including multiply charged anions, solvated species, and biological molecules. The new apparatus consists of an electrospray ionization source, a three dimensional (3D) Paul trap for ion accumulation and cooling, a time-of-flight mass spectrometer, and a magnetic-bottle photoelectron analyzer. A key feature of the new instrument is the capability to cool and tune ion temperatures from 10to350K in the 3D Paul trap, which is attached to the cold head of a closed cycle helium refrigerator. Ion cooling is accomplished in the Paul trap via collisions with a background gas and has been demonstrated by observation of complete elimination of vibrational hot bands in photoelectron spectra of various anions ranging from small molecules to complex species. Further evidence of ion cooling is shown by the observation of H2-physisorbed anions at low temperatures. Cold anions result in better resolved photoelectron spectra due to the elimination of vibrational hot bands and yield more accurate energetic and spectroscopic information. Temperature-dependent studies are made possible for weakly bonded molecular and solvated clusters, allowing thermodynamic information to be obtained.

Collaborative visualization: definition, challenges, and research agenda

Abstract: The conflux of two growing areas of technology - collaboration and visualization - into a new research direction, coLLaborative visualization, provides new research chaLLenges TechnoLogy now aLLows us to easily connect and collaborate with one another - in settings as diverse as over networked computers, across mobile devices, or using shared displays such as interactive waLLs and tabletop surfaces Digital information is now reguLarLy accessed by muLtipLe people in order to share information, to view it together, to analyze it, orto form decisions VisuaLizations are used to deal more effectively with Large amounts of information white interactive visuaLizations aLLow users to expLore the underlying data White researchers face many chaLLenges in coLLaboration and in visualization, the emergence of coLLaborative visualization poses additional chaLLenges, but it is also an exciting opportunity to reach new audiences and applications for visualization tooLs and techniques] to provide a definition, clear scope, and overview of the evolving field of coLLaborative visualization, (2) to help pinpoint the unique focus of coLLaborative visualization with its specific aspects, chaLLenges, and requirements within the intersection of generaL computer-supported cooperative work and visualization research, and (3) to draw attention to important future research questions to be addressed by the community We conclude by discussing a research agenda for future work on coLLaborative visualization and urge for a new generation of visuaLization toots that are designed with coLLaboration in mind from their very inception

Tandem mass spectrometry identifies many mouse brain O-GlcNAcylated proteins including EGF domain-specific O-GlcNAc transferase targets

Abstract: O-linked N-acetylglucosamine (O-GlcNAc) is a reversible posttranslational modification of Ser and Thr residues on cytosolic and nuclear proteins of higher eukaryotes catalyzed by O-GlcNAc transferase (OGT). O-GlcNAc has recently been found on Notch1 extracellular domain catalyzed by EGF domain-specific OGT. Aberrant O-GlcNAc modification of brain proteins has been linked to Alzheimer's disease (AD). However, understanding specific functions of O-GlcNAcylation in AD has been impeded by the difficulty in characterization of O-GlcNAc sites on proteins. In this study, we modified a chemical/enzymatic photochemical cleavage approach for enriching O-GlcNAcylated peptides in samples containing ∼100 μg of tryptic peptides from mouse cerebrocortical brain tissue. A total of 274 O-GlcNAcylated proteins were identified. Of these, 168 were not previously known to be modified by O-GlcNAc. Overall, 458 O-GlcNAc sites in 195 proteins were identified. Many of the modified residues are either known phosphorylation sites or located proximal to known phosphorylation sites. These findings support the proposed regulatory cross-talk between O-GlcNAcylation and phosphorylation. This study produced the most comprehensive O-GlcNAc proteome of mammalian brain tissue with both protein identification and O-GlcNAc site assignment. Interestingly, we observed O-β-GlcNAc on EGF-like repeats in the extracellular domains of five membrane proteins, expanding the evidence for extracellular O-GlcNAcylation by the EGF domain-specific OGT. We also report a GlcNAc-β-1,3-Fuc-α-1-O-Thr modification on the EGF-like repeat of the versican core protein, a proposed substrate of Fringe β-1,3-N-acetylglucosaminyltransferases.

Tuning Pt-CeO2 interactions by high-temperature vapor-phase synthesis for improved reducibility of lattice oxygen.

Abstract: In this work, we compare the CO oxidation performance of Pt single atom catalysts (SACs) prepared via two methods: (1) conventional wet chemical synthesis (strong electrostatic adsorption–SEA) with calcination at 350 °C in air; and (2) high temperature vapor phase synthesis (atom trapping–AT) with calcination in air at 800 °C leading to ionic Pt being trapped on the CeO2 in a thermally stable form. As-synthesized, both SACs are inactive for low temperature (<150 °C) CO oxidation. After treatment in CO at 275 °C, both catalysts show enhanced reactivity. Despite similar Pt metal particle size, the AT catalyst is significantly more active, with onset of CO oxidation near room temperature. A combination of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and CO temperature-programmed reduction (CO-TPR) shows that the high reactivity at low temperatures can be related to the improved reducibility of lattice oxygen on the CeO2 support. While single-atom catalysts (SACs) have attracted a lot of interest, the nature of the active sites in SACs remains elusive. Here the authors elucidate that depositing single atoms via high temperature synthesis leads to improved reducibility of lattice oxygen on CeO2 yielding low temperature reactivity of Pt catalysts in CO oxidation.