scispace - formally typeset
Search or ask a question
Institution

Pacific Northwest National Laboratory

FacilityRichland, Washington, United States
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.
Topics: Catalysis, Aerosol, Mass spectrometry, Population, Ion


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, the coupling among groundwater-surface water mixing, microbial communities and biogeochemistry was investigated using DNA sequencing and ultra-high-resolution organic carbon profiling to investigate the coupling between groundwater and surface water mixing in the hyporheic zone.
Abstract: Environmental transitions often result in resource mixtures that overcome limitations to microbial metabolism, resulting in biogeochemical hotspots and moments. Riverine systems, where groundwater mixes with surface water (the hyporheic zone), are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. Here, to investigate the coupling among groundwater–surface water mixing, microbial communities and biogeochemistry, we apply ecological theory, aqueous biogeochemistry, DNA sequencing and ultra-high-resolution organic carbon profiling to field samples collected across times and locations representing a broad range of mixing conditions. Our results indicate that groundwater–surface water mixing in the hyporheic zone stimulates heterotrophic respiration, alters organic carbon composition, causes ecological processes to shift from stochastic to deterministic and is associated with elevated abundances of microbial taxa that may degrade a broad suite of organic compounds. Groundwater-surface water mixing zones link critical ecosystem domains, but attendant microbe-biogeochemistry-hydrology interactions are poorly known. Here, the authors show that groundwater-surface water mixing stimulates respiration, alters carbon composition, and shifts the ecology from stochastic to deterministic.

249 citations

Journal ArticleDOI
12 May 2017-Science
TL;DR: A structurally complex, mesoporous uranium-based metal-organic framework (MOF) made from simple starting components that is anchored by oxygen-coordinated uranium cations and has been reported as the lowest-density MOF reported to date.
Abstract: Bottom-up construction of highly intricate structures from simple building blocks remains one of the most difficult challenges in chemistry. We report a structurally complex, mesoporous uranium-based metal-organic framework (MOF) made from simple starting components. The structure comprises 10 uranium nodes and seven tricarboxylate ligands (both crystallographically nonequivalent), resulting in a 173.3-angstrom cubic unit cell enclosing 816 uranium nodes and 816 organic linkers—the largest unit cell found to date for any nonbiological material. The cuboctahedra organize into pentagonal and hexagonal prismatic secondary structures, which then form tetrahedral and diamond quaternary topologies with unprecedented complexity. This packing results in the formation of colossal icosidodecahedral and rectified hexakaidecahedral cavities with internal diameters of 5.0 nanometers and 6.2 nanometers, respectively—ultimately giving rise to the lowest-density MOF reported to date.

249 citations

Journal ArticleDOI
TL;DR: The crystallization of Li(15)Si(4) from amorphous Li(x)Si is a spontaneous, congruent phase transition process without phase separation or large-scale atomic motion, which is drastically different from what is expected from a classic nucleation and growth process.
Abstract: It is well-known that upon lithiation, both crystalline and amorphous Si transform to an armorphous LixSi phase, which subsequently crystallizes to a (Li, Si) crystalline compound, either Li15Si4 or Li22Si5. Presently, the detailed atomistic mechanism of this phase transformation and the degradation process in nanostructured Si are not fully understood. Here, we report the phase transformation characteristic and microstructural evolution of a specially designed amorphous silicon (a-Si) coated carbon nanofiber (CNF) composite during the charge/discharge process using in situ transmission electron microscopy and density function theory molecular dynamic calculation. We found the crystallization of Li15Si4 from amorphous LixSi is a spontaneous, congruent phase transition process without phase separation or large-scale atomic motion, which is drastically different from what is expected from a classic nucleation and growth process. The a-Si layer is strongly bonded to the CNF and no spallation or cracking is o...

249 citations

Journal ArticleDOI
TL;DR: The current state of knowledge regarding large-scale meteorological patterns (LSMPs) associated with short-duration (less than 1-week) extreme precipitation events over North America is surveyed in this article.
Abstract: This paper surveys the current state of knowledge regarding large-scale meteorological patterns (LSMPs) associated with short-duration (less than 1 week) extreme precipitation events over North America. In contrast to teleconnections, which are typically defined based on the characteristic spatial variations of a meteorological field or on the remote circulation response to a known forcing, LSMPs are defined relative to the occurrence of a specific phenomenon—here, extreme precipitation—and with an emphasis on the synoptic scales that have a primary influence in individual events, have medium-range weather predictability, and are well-resolved in both weather and climate models. For the LSMP relationship with extreme precipitation, we consider the previous literature with respect to definitions and data, dynamical mechanisms, model representation, and climate change trends. There is considerable uncertainty in identifying extremes based on existing observational precipitation data and some limitations in analyzing the associated LSMPs in reanalysis data. Many different definitions of “extreme” are in use, making it difficult to directly compare different studies. Dynamically, several types of meteorological systems—extratropical cyclones, tropical cyclones, mesoscale convective systems, and mesohighs—and several mechanisms—fronts, atmospheric rivers, and orographic ascent—have been shown to be important aspects of extreme precipitation LSMPs. The extreme precipitation is often realized through mesoscale processes organized, enhanced, or triggered by the LSMP. Understanding of model representation, trends, and projections for LSMPs is at an early stage, although some promising analysis techniques have been identified and the LSMP perspective is useful for evaluating the model dynamics associated with extremes.

249 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present an overview of soil properties and processes that must be considered and classify the methods for determining soil C changes as direct or indirect direct methods include field and laboratory measurements of total C, various physical and chemical fractions, and C isotopes.
Abstract: Changes in soil and vegetation management can impact strongly on the rates of carbon (C) accumulation and loss in soil, even over short periods of time Detecting the effects of such changes in accumulation and loss rates on the amount of C stored in soil presents many challenges Consideration of the temporal and spatial heterogeneity of soil properties, general environmental conditions, and management history is essential when designing methods for monitoring and projecting changes in soil C stocks Several approaches and tools will be required to develop reliable estimates of changes in soil C at scales ranging from the individual experimental plot to whole regional and national inventories In this paper we present an overview of soil properties and processes that must be considered We classify the methods for determining soil C changes as direct or indirect Direct methods include field and laboratory measurements of total C, various physical and chemical fractions, and C isotopes A promising direct method is eddy covariance measurement of CO2 fluxes Indirect methods include simple and stratified accounting, use of environmental and topographic relationships, and modeling approaches We present a conceptual plan for monitoring soil C changes at regional scales that can be readily implemented Finally, we anticipate significant improvements in soil C monitoring with the advent of instruments capable of direct and precise measurements in the field as well as methods for interpreting and extrapolating spatial and temporal information

249 citations


Authors

Showing all 11848 results

NameH-indexPapersCitations
Yi Cui2201015199725
Derek R. Lovley16858295315
Xiaoyuan Chen14999489870
Richard D. Smith140118079758
Taeghwan Hyeon13956375814
Jun Liu13861677099
Federico Capasso134118976957
Jillian F. Banfield12756260687
Mary M. Horowitz12755756539
Frederick R. Appelbaum12767766632
Matthew Jones125116196909
Rainer Storb12390558780
Zhifeng Ren12269571212
Wei Chen122194689460
Thomas E. Mallouk12254952593
Network Information
Related Institutions (5)
ETH Zurich
122.4K papers, 5.1M citations

91% related

Centre national de la recherche scientifique
382.4K papers, 13.6M citations

91% related

Georgia Institute of Technology
119K papers, 4.6M citations

90% related

Tsinghua University
200.5K papers, 4.5M citations

90% related

Pennsylvania State University
196.8K papers, 8.3M citations

90% related

Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023130
2022459
20211,793
20201,795
20191,598
20181,619