Laboratory Science Highlights Office of Science is the single largest supporter of basic research in the physical sciences in the United States, providing more than 40 percent of total funding for this vital area of national importance. It oversees - and is the principal federal funding agency of - the Nation's research programs in high-energy physics, nuclear physics, and fusion energy sciences.en{28096628-628B-489F-9A66-423CCF9C0E48} How Radiative Fluxes Are Affected by Cloud and Particle Characteristics<img src='/~/media/DDAF1E4A39A54347ACA8CD059D1B7BDD.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New insights improve Community Atmosphere Model’s representation.Mon, 16 Mar 2015 14:44:32 -0400<p>The research team, led by U.S. Department of Energy scientists at Pacific Northwest National Laboratory, found that the global mean radiative flux (FNET) variance is dominated by the cloud forcing variance, given the assigned uncertain parameter ranges. They also found that most selected cloud microphysics- and emission-related parameters have statistically significant impacts on the global mean FNET. Three cloud microphysics parameters (associated with the fall speed of cloud ice and snow) and assumed bounds on cloud droplet number have a smaller impact than the size threshold required for ice to change to snow. Overall, these cloud microphysics-related parameters have a larger impact on high clouds than on low clouds. The team&rsquo;s comprehensive approach not only estimates the contribution of each parameter to model sensitivity but also provides its statistical significance. This is an important quantification, rarely obtained due to the limited sampled space of parameter uncertainty.</p>{6C8A4ECA-72C0-4385-859D-D1176CD4DA12} Climate Models to Real World Shows Differences in Precipitation Intensity<img src='/~/media/D89CC2334A324FE8A0C18DDFFBA5B8A9.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Understanding the differences and similarities will help improve how models represent storm clouds and other convective processes.Mon, 16 Mar 2015 14:44:32 -0400<p>Precipitation is one of the most poorly parameterized physical processes in global climate models. Scientists often use a single grid-box column of a global climate model or a single-column model to more efficiently study and test the process representations or parameterization schemes in global climate models. The single-column model approach is also a key strategy of the U.S. Department of Energy&rsquo;s (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and Atmospheric System Research activity. However, most single-column model intercomparison studies organized by ARM have been focused on special cases or week- to month-long periods. To make a statistically meaningful comparison and evaluation of modeled precipitation, researchers conducted 3-year-long single-column model simulations of seven global climate models participating in the Fast-physics System Testbed and Research (FASTER) project at the ARM Southern Great Plains site. Results of the study, conducted by DOE scientists at Brookhaven National Laboratory, show that although most single column models can reproduce the observed average precipitation reasonably well, there are significant differences in their details. These variations (both among models and between models and observations) include differences between daytime and nighttime, warm and cold seasons, frequency and mean precipitation intensity, and convective and stratiform partition. Further analysis reveals distinct meteorological backgrounds for large underestimation and overestimation precipitation events. The former occur in strong ascending regimes with negative low-level horizontal heat and moisture influx, while the latter occur in the weak or moderate ascending regimes with positive low-level horizontal heat and moisture influx.</p>{C11C8398-A0EE-4E58-9F2B-AAA7BD26A14F} Method Relates Greenland Ice Sheet Changes to Sea-Level Rise<img src='/~/media/B72A9FB484CF4390BE2D985357CB5B47.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Modeling approach includes the effects of ice sheet elevation and region.Mon, 16 Mar 2015 14:44:33 -0400<p>The team used the new scheme in five ice sheet models and forced them with climate warming conditions taken from two different climate models. Including the elevation effects in the model increases the estimated sea-level rise by a small but significant amount (5% enhancement of melt by 2100 and 10% by 2200 for a climate warming scenario). By 2100, the choice of driving climate model conditions dominates the uncertainty, but by 2200, the uncertainty in the ice sheet model and the elevation scheme are larger.</p>{9CD9520B-8FD4-4C3B-9652-C101C56E8E85} Mathematical Method Enhances Hydrology Simulations<img src='/~/media/354E07526C1545E3BD62213B221630B2.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Approach uses land-atmosphere observations to calibrate model.Mon, 16 Mar 2015 14:44:34 -0400<p>The exchange of water and energy between the atmosphere and land is among the most uncertain aspects of climate modeling. For example, when rain falls on land, the amount of water that evaporates back into the atmosphere or gets carried by groundwater to rivers and the ocean is unclear. The answer to this and similar questions could be estimated using climate models, but these models have numerous variables or &ldquo;parameters&rdquo; that must be adjusted based on observations of different regions of the Earth. One way to adjust these parameters is to run the model repeatedly, each time changing the parameters individually until a solution that matches observations is found. However, it is possible that a different set of solutions would also match observations. Researchers evaluated inversion methodologies at select field sites based on global sensitivity analyses. They found significant improvements in the model simulations that better match the observed heat flux and runoff by using the estimated parameters compared to using the default parameters.Improvements in heat flux were found especially in areas with strong energy and water constraints.</p>{600A4347-6425-4FA6-872D-D48C16462583} Not Concentration Matters when Forming Cloud-Influencing Aerosols<img src='/~/media/E5802CD94A264A9CA0B7B9CC39131BFD.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Nitrogen oxide has nonlinear effects on the volatility and composition of SOA based on isoprene emitted by trees.Mon, 16 Mar 2015 14:44:35 -0400<p>Isoprene, an organic compound produced and emitted into the atmosphere by many tree species, plays an important role in tropospheric ozone chemistry and in formation of SOA particles. The particles can affect Earth&rsquo;s radiation balance directly through scattering or absorption of sunlight and indirectly through forming cloud condensation nuclei. Accurately simulating the impacts of SOA on climate requires understanding the chemical processes that lead to SOA formation in the atmosphere under a wide variety of environmental conditions. Previous laboratory studies have demonstrated different SOA oxidation yields and properties at &ldquo;low&rdquo; (near zero) and &ldquo;high&rdquo; levels of nitrogen oxides (NOx). Current models use a linear combination of these extreme conditions to predict altered SOA formation in the presence of anthropogenic emissions. Unfortunately, data from recent laboratory and field studies have not been consistent with this simple model. To help address this challenge, a team of U.S. Department of Energy researchers conducted laboratory experiments in an environmental chamber to investigate the effects of NOx on the volatility and chemical composition of SOA generated by isoprene photooxidation. Volatility is a key property of organic aerosol because it determines the partitioning between the gas and particle phases, and thus the formation of SOA particles. Researchers found that the volatility and oxidation state of isoprene SOA are sensitive to, and exhibit a nonlinear dependence on, NOx levels. The dependence likely arises from gas-phase chemistry of organic peroxy radicals, which compete with NOx in reactions, and succeeding particle-phase reactions. This observation helps reconcile the seemingly contradictory observations of the NOx effect on isoprene SOA volatility reported in previous literature studies.</p>{C3237E60-8A24-439B-813A-90C4F341DE11} Produces Ethanol from Switchgrass Without Pretreatment<img src='/~/media/5DFFBBDF6ADF4D1BA14ED71278832757.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Genetic engineering allows biomass-degrading bacterium to make fuel in a single process.Mon, 16 Mar 2015 14:44:36 -0400<p>Producing ethanol from plant biomass typically requires three major steps: physicochemical pretreatment, enzymatic breakdown of biomass into its constituent sugars, and fermentation. Pretreatment and enzymatic hydrolysis are costly steps in the process. CBP could reduce costs. In CBP, unpretreated cellulosic biomass is converted to a biofuel in a single process by a microbe that breaks down the biomass and ferments the resulting sugars. <em>Caldicellulosiruptor bescii </em>had been shown to ferment untreated switchgrass, but it lacked the genes to make ethanol. Because <em>C. bescii </em>is a thermophile (heat loving) and CBP is carried out at elevated temperatures, a gene for a heat-stable enzyme enabling ethanol synthesis was needed. Researchers identified a candidate gene in <em>Clostridium thermocellum </em>and cloned it into <em>C. bescii</em>. The engineered strain of <em>C. bescii </em>was then able to produce ethanol from cellobiose, Avicel, and switchgrass. To optimize ethanol fermentation, two genes were deleted that would otherwise divert fermentation products. In this new <em>C. bescii </em>strain, roughly 30% of biomass was fermented, and 1.7 moles of ethanol were produced for each mole of glucose, an amount close to the theoretical 2.0 moles of ethanol per mole of glucose. Although efficiencies can be further improved, this study is an important step in realizing the potential of CBP and provides a platform for engineering the production of advanced biofuels and other bioproducts directly from cellulosic biomass without harsh and expensive pretreatment.</p>{972D4B4B-5145-461D-AEA4-890DBCBB9A13} Transition of Vanadium Dioxide<img src='/~/media/C6EE135B1155482FB26D7B09E66F7E45.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New studies explain the transition, providing a quantitative picture of a 50-year-old mystery.Mon, 09 Mar 2015 16:54:23 -0400<p>Vanadium dioxide (VO<sub>2</sub>), a &ldquo;functional material&rdquo; that could be used in applications such as smart windows and ultrafast field effect transistors, exhibits an insulator to metal transition upon heating to just above room temperature. At the transition temperature, its electrical conductivity abruptly increases by a factor of 10,000 and the atomic lattice rearranges from a monoclinic to a tetragonal structure (see figure). A fundamental description of the physical and electronic properties during the transition in VO<sub>2</sub> has remained controversial for over 50 years. Researchers at Oak Ridge National Laboratory employed advanced neutron and x-ray scattering experiments at DOE user facilities, coupled with large-scale first-principles calculations with super computers, to determine the detailed mechanism for the transition. Their studies, published in <em>Nature</em>, revealed that the thermodynamic force driving the insulator-to-metal transition is dominated by the lattice vibrations (phonons) rather than electronic contributions. In addition, a direct, quantitative determination of the phonon dispersions was&nbsp;achieved, as well as a description of how changing occupancies in the atomic orbitals participate in the phase transition. The low-energy phonons were found to change the bonds between atoms (i.e., electron orbitals), allowing some electrons to travel freely at higher temperatures leading to a metallic state.&nbsp;This research demonstrates that anharmonic lattice dynamics play a critical role in controlling phase competition in metal oxides, and provides the complete physical model vital for the predictive design of new materials with unique properties.</p>{32364D25-2226-4DC6-8088-154942FC3D40} Formation of Biomimetic, Nanoporous Membrane Channels<img src='/~/media/54026BDE5F5E488E86C776042BA0D7C8.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Carbon nanotubes insert into artificial and active cell membranes, reproducing major features of biological channels.Mon, 09 Mar 2015 16:54:24 -0400<p>For the first time, a process for spontaneously inserting carbon nanotubes (CNTs) into cell membranes, both natural as well as synthetic, to form pores that mimic biological channels has been demonstrated. Robust, synthetic membranes that replicate the highly efficient and selective transport processes of biological channels are much sought-after but have not been realized yet. CNTs are thought to be the best candidates for mimicking biological transport because of the similarity of their inner pore structure to that of major biological channels and the possibility that, based on computational modeling, the CNTs could self-insert into biological membranes. However, creation of such hybrid membrane structures has remained an outstanding challenge. Now, a team led by scientists at Lawrence Livermore National Laboratory and including scientists from Lawrence Berkeley National Laboratory, the University of California at Berkeley, and the University of Basque Country in Spain has formed a hybrid membrane by creating membrane channels from short CNTs. They found that CNTs functionalized with lipid (fatty) molecules spontaneously insert into cell membranes, both natural and synthetic. Importantly, insertion of the small CNTs into live cell walls allowed them to interface directly with a real biological system, something not possible with long CNTs. This interface permitted the fundamental physics of nanopore transport to be investigated using a model that more closely approximated an ion channel and that mimics transport in biological pores. Despite their extremely simple structure, these membrane pores reproduce the major functional behavior of biological channels, such as selective transport of protons, water, ions, and small molecules. The CNTs do not affect the integrity of the membrane. Electron microscopy revealed that insertion is not selective to a particular nanotube length. Furthermore, a near-perpendicular orientation of the CNTs within the membrane is strongly preferred, contrary to previous simulation-based predictions. Despite significant CNT length variations, the transport properties of these hybrid membranes, termed &ldquo;CNT porins&rdquo; (where the term porins refers to protein-based biological channels), are extremely well defined, strongly suggesting that transport through the CNT pores is directed only by the barriers at the pore exit and entry. In addition, nanoscale confinement of ions in the narrow hydrophobic channel gives rise to ionic current fluctuation, mimicking the on-off gating process of ion transport that occurs in biological channels. Cumulatively, these results point to the hybrid materials having useful membrane applications. These applications include providing a platform for nanofluidic studies, building bioelectronic interfaces and artificial cells, and serving as key components for energy-efficient membrane separation systems.</p>{14A175BD-5E85-4A35-B45E-236F188D9B73} Atomic Neighborhoods for Speedier Chemical Reactions<img src='/~/media/A15AEF0143CE46A88E8E7F6D78AAAD83.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Clusters with longer separations between atoms had enhanced catalytic activity.Mon, 09 Mar 2015 16:54:24 -0400<p>Palladium-nickel nanoalloy catalysts have tunable parameters, such as particle size and atomic composition, that affect critical atomic-scale structural features.&nbsp; These key structural features include local bond distances and number of neighbors at surface sites, and are correlated with catalytic activity for the conversion of carbon monoxide into carbon dioxide. Surface sites with more atomic neighbors and longer ﬁrst-neighbor separations were found to be more active catalytically than those with fewer atomic neighbors and shorter ﬁrst-neighbor separations. This type of atomic detail has not been available by traditional studies and can aid the cycle of catalyst design by optimizing for structural parameters at the nearest neighbor level of an atomic environment.&nbsp; The atomic detail in a reactive environment was made possible by x-ray scattering techniques that involve high-energy x-rays and bright synchrotron x-ray beams able to penetrate sealed reaction chambers and resolve positions of atoms with high precision in minute amounts of nanoalloy particles. The work also demonstrated how various thermal and chemical environmental pathways alter the atomic neighborhood of nanoparticle surfaces.</p>{880B593A-D04A-45FE-BFE7-47AFF49D4B41} Nanoframes Improve Catalyst Performance<img src='/~/media/5685C7865424447EA6D8918E8F361FE9.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Concentrating noble-metal catalyst atoms on the surface of porous nano-frame alloys shows over thirty-fold increase in performance.Mon, 09 Mar 2015 16:54:25 -0400<p>Control of structure at the atomic level can precisely and effectively tune catalytic properties of materials, enabling enhancement of both activity and durability. A team of researchers from Argonne National Laboratory, Lawrence Berkeley National Laboratory, and the University of Wisconsin synthesized a highly active and durable class of electrocatalysts by exploiting the structural evolution of solid Pt-Ni bimetallic nanocrystals into porous cage-like structures or nanoframes. The material was synthesized by exploiting the structural evolution of platinum-nickel (Pt-Ni) bimetallic nanocrystals into cage-like structures with a self-assembled Pt skin structure on the interior and exterior surfaces. The starting material, crystalline PtNi<sub>3</sub> nanoparticles, are transformed in solution and at mild temperatures into Pt<sub>3</sub>Ni nanoframes with surfaces that have three-dimensional molecular accessibility. The Pt-rich edges of the starting PtNi<sub>3</sub> nanoparticles are maintained in the final Pt<sub>3</sub>Ni nanoframes. Both the interior and exterior surfaces of this open framework structure are composed of a Pt-rich skin structure that exhibits enhanced oxygen reduction reaction activity. The Pt<sub>3</sub>Ni nanoframe catalysts achieved a more than 36-fold and 22-fold enhancement in two different measures of catalytic activity (mass and specific activities, respectively) for the oxygen reduction reaction in comparison to state-of-the-art carbon-supported Pt catalysts (Pt/C) during prolonged exposure to reaction conditions. This work is a significant advance towards developing more efficient electrocatalysts for water-splitting reactions and fuel generation. &nbsp;These electrocatalyst structures were applied to the hydrogen evolution reaction (HER), which is the crucial cathodic reaction in water-alkali electrolyzers, which generate hydrogen by splitting water. The HER activity for highly crystalline Pt<sub>3</sub>Ni&ndash;Pt-skin nanoframe surface was enhanced by almost one order of magnitude relative to Pt/C. &nbsp;Utilizing the spontaneous structural evolution of a bimetallic nanoparticle from solid polyhedra to hollow nanoframes with controlled size, structure, and surface composition should be readily applicable to other multimetallic catalysts.</p>{966DA49A-325F-4433-85E4-9E48FF9ADBB7} Order to Defects - Making Way for Oxygen to Move<img src='/~/media/8BE833D50C5A475EBEBE2B56DF416441.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New metal oxide material works at temperatures low enough to improve fuel cell efficiency.Mon, 09 Mar 2015 14:13:17 -0400<p>Metal oxides are important materials found in many energy technologies such as fuel cells, superconductors, and thermoelectric systems. Most metal oxides contain oxygen deficiencies or vacancies as point defects which are often uniformly distributed in the material.&nbsp;A challenging goal is controlled generation and positioning of these oxygen deficiencies to create novel structures and functional properties. Researchers at the Pacific Northwest National Laboratory have accomplished just that in their discovery of a new, non-stoichiometric metal oxide SrCrO<sub>2.8</sub>. While attempting to prepare thin films of stoichiometric SrCrO<sub>3.0</sub>, they found that a non-stoichiometric form with the composition SrCrO<sub>2.8</sub>&nbsp;is formed instead. This new material contains ordered arrays of SrO<sub>2</sub>&nbsp;planes interleaved between layers of tetrahedrally coordinated Cr<sup>+4</sup>&nbsp;ions and separated by ~1nm.&nbsp;Moreover, when mildly heated in air, it reversibly transforms from a semiconducting form with rhombohedral (diamond-like) structure to a metallic form with a so-called cubic perovskite structure. The ordered oxygen vacancies in the rhombohedral form allow oxygen ions to diffuse through the material quickly and easily at low temperatures (~250&deg;C). This property is exceedingly important for solid oxide fuel cell technology which currently requires very high operating temperatures (~800&deg;C). First-principle calculations provided insights into the formation and stability of the non-stoichiometric SrCrO<sub>2.8</sub>&nbsp;and how oxygen ions could move so easily through the material.&nbsp;The aggregation of oxygen vacancy defects into ordered arrays is a property of interest for not only more efficient solid oxide fuel cells but also would be useful for other applications such as thermoelectrics.</p>{5020D5CE-167E-4075-8F59-3B394EF39A2A} Magnetic Behavior in Copper Oxide Superconductors<img src='/~/media/EB7BD2A057ED4D319D33966C2DF85DC3.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New theoretical techniques predict experimental observations in superconducting materials.Mon, 09 Mar 2015 14:13:15 -0400<p>Theory has long had difficulty predicting the behavior of transition metal oxides. These materials, combinations of metals such as iron, cobalt, nickel or copper with oxygen, display a wealth of important properties such as magnetism, temperature dependent phase transitions from electrically insulating to conducting, and superconductivity &ndash; a property that allows materials to conduct electricity with perfect efficiency. Accurate theoretical calculations could open the door for discovery of new materials in this class with even better properties than those currently in use. The problem with describing them theoretically is the phenomenon of <em>electron correlation</em>, the fact that the motion of individual electrons depends on the motion of all the others. Theories that treat electron correlation have been known for a number of years but required orders of magnitude greater computer resources than were available. In this research, accurate calculations of magnetic energies were performed at the ORNL leadership class computer for calcium copper oxide (Ca<sub>2</sub>CuO<sub>3</sub>) a material containing nearly one-dimensional (1D) chains of copper, a one-dimensional counterpart of the famous high temperature superconducting cuprates. Like other cuprates the pure material is a magnetic insulator but becomes superconducting with changes in composition &ndash; in this case by increasing the oxygen concentration. Standard theory predicts the pure material (and other cuprates) to be a metal in contrast to the experiments. In this research, the 1D character of the materials permitted detailed comparison between theory and experiments, and showed good agreement between the theoretical data and those obtained from neutron scattering and magnetic susceptibility measurements. The research used highly accurate Quantum Monte Carlo (QMC) calculations. QMC methods accurately describe many-body systems, but at a high computational cost. High-performance computers, such as those at the Oak Ridge Leadership Computing Facility, allow application of QMC to problems that have remained unsolved for decades.&nbsp;This achievement could lead to better predictions of superconductor behavior derived from fundamental laws of physics.</p>{05D46499-4631-4EFD-A202-F95DD2E79FCA} Shine Bright as New Terahertz Source<img src='/~/media/5BFBDB6C9BA24289B69662BF991FFCD7.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Discovery demonstrates how metamaterials may be used in non-invasive material imaging and sensing, and terahertz information technologies.Mon, 09 Mar 2015 14:13:12 -0400<p>Broadband terahertz sources offer exciting possibilities to study fundamental physics principles, to develop non-invasive material imaging and sensing, and make possible terahertz information, communication, processing, and storage. The terahertz spectral range sits between infrared and typical radar frequencies, and the challenges of efficiently generating and detecting terahertz radiation has limited its use. To solve these challenges consider metamaterials; materials that allow control of the properties of light-matter interactions at the fundamental level. The building blocks of metamaterials, known as split-ring resonators, can be designed to exhibit strong electric and magnetic response to electromagnetic fields over a wide frequency range, from terahertz to infrared. Scientists at Ames Laboratory, Iowa State University, and Karlsruhe Institute of Technology in Germany have discovered that when a two-dimensional array of nanometer-sized gold metamaterial resonators is illuminated by a tunable near-infrared femtosecond laser, with wavelengths matching the magnetic resonance of the metamaterial, a strong broadband of terahertz electromagnetic waves is emitted. The efficiency of this conversion to terahertz waves was significantly better than conventional materials that are presently used for these applications. Detailed analysis of the directionality and polarization of the emitted radiation reveals the fundamental nature of this efficient wavelength conversion. Further, these new metamaterials could allow integration of terahertz optoelectronics with high-speed telecommunications.</p>{80307784-AE35-47FF-9F8C-4B791DFA4627} of Superconductivity and Magnetism<img src='/~/media/EC968A8D3594447B8579912510CB9D83.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Coexistence of two states of matter that normally avoid one another is revealed by inelastic neutron scattering experiments.Mon, 09 Mar 2015 14:13:11 -0400<p>The observation of coexisting magnetism and superconductivity in a particular copper-oxide superconductor suggests that the two types of order can be spatially modulated and intertwined, supporting recent theoretical predictions.&nbsp;Understanding the relationship between superconductivity and a type of atomic magnetic correlation (antiferromagnetism, wherein neighboring atomic spins are oriented in opposite directions) remains a challenge. The magnetism is associated with the localization of electrons, whereas superconductivity is a state in which electrons are paired and can flow without resistance. &nbsp;Previous experiments have shown that these two states do not like to coexist in the same space. Researchers from Brookhaven National Laboratory characterized slow magnetic fluctuations in a copper-oxide superconductor. Their discovery shows that the slowly fluctuating magnetism does not disappear in the superconducting state; in fact, it grows stronger at the lowest fluctuation frequencies. The state of intertwined superconductivity and antiferromagnetism that has been proposed by theorists provides a likely explanation of the observations. These results indicate an intimate connection between superconductivity and magnetism in copper oxides, an important clue for developing a predictive theory of high-temperature superconductivity.</p>{99620D08-DA48-4FC2-B9C5-4D4AA7AB0F99} Path to Loss-Free Electricity<img src='/~/media/068E9300C781422C9166CD12956C3CCE.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Atomic-scale details of electron distribution reveal a novel mechanism for current to flow without energy loss.Mon, 09 Mar 2015 14:13:10 -0400<p>The flow of current in ordinary metals and other materials that conduct electricity is composed of electrons; however, the charge carriers are scattered when they conduct electricity, resulting in dissipation and energy loss, typically in the form of heat. In a superconductor, the electrons form into pairs that allow them to move through the material without resistance, eliminating the energy lost and thus increasing the efficient use of electricity. The challenge in creating such electron pairs is overcoming the natural tendency for electrons to repel each other. One solution is to utilize electronic polarizability that can yield an attractive interaction between electrons, thus allowing pair formation and the potential for loss-free current flow. Such a mechanism was proposed almost five decades ago, but it was never experimentally verified. Using electron diffraction with subatomic precision, scientists at Brookhaven National Laboratory have mapped out the redistribution of orbital electrons in barium iron arsenide, with and without cobalt substitution. The results reveal a remarkable increase in charge distribution around the iron and arsenic atoms as cobalt is incorporated into the material. Electron energy loss spectroscopy was carried out to determine the charge carrier-injection effect of cobalt substitution, while density functional theory was used to model electronic and atomic behavior. The induced charge redistribution around the iron and arsenic atoms after cobalt substitution suggests that the strongly coupled bond-electron fluctuation and charge separation may provide a new mechanism for high-temperature superconductivity. These results may guide the design of new superconductors.</p>{09945F3B-C1DA-4113-A81F-16844333504B} Laser Used to Produce Movies of Atomic-scale Motion<img src='/~/media/6F8E084954584AFFA263B83CAC01F5E9.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Stroboscopic x-ray pulses scatter from a vibrating crystal and reveal how energy moves.Mon, 09 Mar 2015 14:13:20 -0400<p>X-ray scattering can measure and describe the atomic positions in technologically important crystalline solids like silicon and germanium.&nbsp;After an excitation by heat or radiation, the flow of energy can be tracked as it moves through various storage modes; such as atomic spacing and bonding, atomic vibrations, and electron or magnetic ordering.&nbsp;The new technique uses advances in synchronized infra-red and x-ray laser pulses along with a large area position sensitive x-ray detector, to make x-ray scattering movies which track the response of the material from the moment of excitation.&nbsp;Infra-red light excites electrons and the x-rays measure the vibrational wave length and frequency where electron charge distortions couple strongly to changes in the atomic vibrations. Short lived transient states can be excited and measured and help determine how energy flows on atomic length scales. The time-domain measurements are a direct way to follow the excitations of solids and the flow of energy well away from their &ldquo;home&rdquo; positions and ground state.</p>{9621107B-2298-4754-807B-7D802EF297B4} Tool for Studying Toxic Metals in the Environment<img src='/~/media/DF58BF44A5E241FEA5FCEE4D14AF48A6.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Method enables quantification of thiols on bacteria and natural organic matter.Fri, 19 Dec 2014 16:40:12 -0500<p>The method uses a fluorescence-labeling reagent consisting of a thiol-reactive maleimide group known as ThioGlo-1 (TG-1). TG-1 has been used for determining thiols in biological proteins and tissues but never for directly quantifying thiols on bacteria and NOM. The ORNL team systematically evaluated and optimized the labeling conditions to minimize potential interferences with non-thiol compounds. They applied the optimized conditions to <em>Geobacter sulfurreducens</em> PCA (a gram-negative methylating bacterium) and its mutants in culture solutions, as well as to two NOM samples. Their method proved to be highly selective and capable of quantifying thiols at sub-micromolar concentration levels. This ability to directly quantify organic thiols on NOM and bacterial cells will help scientists gain a mechanistic understanding of soft metal and microbial interactions, metal speciation, and bioavailability.</p>{54438E20-9471-4699-9A26-3515D1FB1873} Hydrological Controls on Flood Frequency<img src='/~/media/FCD464A20F174092AEC0D4E0A83B8316.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Study comparing data from hundreds of U.S. catchments could improve flood prediction.Fri, 19 Dec 2014 16:40:13 -0500<p>To improve flood frequency estimates, researchers led by Department of Energy (DOE) scientists at Pacific Northwest National Laboratory conducted a study providing insights on the connections between flood frequency and measures of mean annual water balance. This water balance was expressed in terms of two controlling measures: (1) the climatic aridity index (AI), which is a measure of the competition between evaporation and precipitation, and (2) base flow index (BFI), which is a measure of total annual runoff partitioning into surface and subsurface components.&nbsp; Researchers performed the study using data from several hundred catchments across the continental United States. Their results showed that AI has a first-order control on the shape of the flood frequency curve in terms of the mean and variability of the annual maximum floods. While the mean annual flood discharge decreases with increasing aridity, variability increases. In contrast, BFI was found to exert a second-order control on flood frequency. Higher BFI, meaning higher contributions of subsurface flow to total streamflow, leads to a decrease of the mean annual (specific) flood discharge and vice versa. Developing further insights into the connection between annual water balance and flood frequency will be another step toward gaining a comprehensive, holistic understanding of hydrologic variability and similarity at the catchment scale.</p>{DD46F103-3F7C-4E98-BF34-2AD4E6C2668C} Aerosols Play Unexpected Role in Ganges Valley<img src='/~/media/526DF7436C8F40EE87478AE14769E651.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>ARM study reveals surprising amount of light absorption by large aerosol particles.Fri, 19 Dec 2014 16:40:13 -0500<p>Global climate models cannot resolve the details of individual aerosol particles, so they use broad assumptions about aerosol characteristics in their computations. Generally, climate models assume that absorbing aerosols are small (less than 1 micron). However, a recent field study in India&rsquo;s Ganges Valley indicates a surprising amount of light absorption by larger aerosol particles (1 to 10 microns). Periods of increased absorption by the larger particles ranged from a week to a month. The exact origin of the large aerosol particles is unknown, but the research team analyzed air mass trajectories using meteorological data and determined that the particles were produced locally, rather than transported long distances from other regions. A potential source of the large particles is burning of trash in the populated valley below the observational site. Because similar economic and habitation conditions are common in much of the developing world, super-micron-sized particles could play a significant role in radiative transfer and cloud processes in such regions.</p>{F7852509-F224-4B22-9A2E-190D89734CED} an Earth System Modeling Approach to Simulate Irrigation Effects<img src='/~/media/341DEFCD4A044C91B83B1AAF9EE6AD31.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Land model improvements are enabling more realistic representations of the climate and hydrological consequences of crop irrigation.Wed, 07 Jan 2015 16:58:45 -0500<p>Previous sensitivity studies of irrigation impacts on land surface provide limited analysis of uncertainties from the input data and model irrigation schemes. A team of scientists led by Department of Energy (DOE) researchers at Pacific Northwest National Laboratory found that when inputting irrigation area fraction datasets from two widely used sources, CLM4 tended to produce unrealistically large temporal variations of irrigation demand for water resources at the regional scale over the conterminous United States. The research recommends a critical path forward to realistic assessments of irrigation impacts by developing CLM to include groundwater pumping and irrigation efficiency modules, and coupling CLM with streamflow routing and water management modules to account for all water supply sources.</p>{B7D4C3F2-0484-4676-8D4A-77E83457BB62} Down the Mechanisms of Biomass Deconstruction<img src='/~/media/0ED36F24A77D4C1F8B43C58925C042B2.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Study reveals insights into plant structural changes during bioenergy pretreatments.Wed, 07 Jan 2015 16:58:46 -0500<p>The research team, led by scientists at Oak Ridge National Laboratory, studied wood chips as they were exposed to a variety of pretreatments including steam explosion, dilute acid, and ammonia fiber expansion. Researchers visualized structural changes in the biomass during processing, showing, for example, how cell wall porosity and the extent of hydration of the different biomass components change as treatments proceed. The key mechanisms responsible for structural changes are the dehydration of cellulose fibers and lignin-hemicellulose phase separation. The team&rsquo;s research was featured on the January 2014 cover of <em>Green Chemistry</em>.</p>{5B7F66D7-7B75-432D-87FA-EBFD9652FB85} Formation of Plutonium Nanoparticles<img src='/~/media/B77F2B06FE1E433CA69EFC1F8A73D1DB.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Researchers observe metal-trapping on mineral surfaces.Wed, 07 Jan 2015 16:56:59 -0500<p>The release of the radioactive element plutonium (Pu) into the environment is a major concern due to the high radiotoxicity and long half-life of some Pu isotopes. However with the absence of any geological record for Pu it is difficult to understand its chemistry or predict its fate and transport in the environment. Previous research with other heavy metals and actinide elements showed that transport in nature is often controlled by the metal atoms bonding to the surface of minerals. In these experiments, by researchers at Argonne National Laboratory, Pu(IV) nanoparticles are observed to form spontaneously from an initially Pu(III) solution when exposed for a few hours to muscovite mineral basal surfaces. This results in a broad Pu agglomeration extending &gt;7 nanometers above the muscovite surface associated with the formation of Pu(IV) oxide nanoparticles. The present result demonstrates that the interaction of this chemically-active charged metal atom with a relatively non-reactive mineral surface can effectively &lsquo;catalyze&rsquo; a change in the oxidation state of the adsorbed ion leading to the formation of nanoparticles attached to the mineral surface.&nbsp;This result provides new insight into understanding the environmental transport of plutonium and other contaminants capable of similar redox/polymerization reactions.</p>{FA73E8BC-D1F4-4201-868C-5576D55BCFAE} an Elemental Crossroad: Investigating the Chemistry of Protactinium<img src='/~/media/D770355F28FB453EAFFBBC629CACA5AA.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Studies of protactinium aim to understand its chemistry and its unique electronic properties in the actinide elements.Wed, 07 Jan 2015 16:56:58 -0500<p>Protactinium (Pa), the element between thorium and uranium is the first actinide to possess an electron in its valence f electronic-orbital. Unlike the transition metals such as iron whose chemistry is defined by its d electronic orbitals, or carbon s- and p- orbitals, the f- electronic orbitals are the defining characteristic of the actinides as well as the rare-earth elements. This is critical because the relative energies of the orbitals that participate in a chemical bond, along with their shapes and symmetries, directly affect the observed structure, reactivity and physical properties of a molecule.&nbsp; Importantly, the energies of the outermost f-orbitals, which define the chemistry of the actinide elements, and the outermost d-orbitals that drive the chemistry of the heavy transition metals, cross in energy at protactinium. Pa, though formally part of the actinide series, chemically behaves somewhat like both a transition metal and an actinide. To better understand its exceptionally complex chemistry, scientists at Argonne National Laboratory synthesized a series of Pa-fluoride complexes to demonstrate a variety of coordination environments around the ion. They discovered significant structure and symmetry diversity among the complexes suggesting there is still much to be revealed by studying Pa and its chemical relationship to the other early actinide elements.</p>{700A7BBF-8FA3-4CE4-A9F8-B4274CA2D4C3} Reveal New Electrocatalyst Family for Producing Hydrogen Fuel<img src='/~/media/48CA179E65A5437EA9FB9961E905C621.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New catalyst material provides potential for cheaper renewable hydrogen production.Wed, 07 Jan 2015 16:56:56 -0500<p>Most renewable energy is produced in the form of electricity, which is expensive to store and transport in large quantities. Producing hydrogen from water using the hydrogen evolution reaction (HER) provides an alternative renewable fuel that is more easily stored and transported than electricity generated through competing photovoltaic (PV) technologies. Due to the energy barriers of the reactions, catalysts are essential to increase the overall hydrogen production efficiency, which is lower than that of direct generation of electricity. Unfortunately, the best HER catalysts incorporate noble metals such as the rare and expensive platinum, which limits the viability of cheap, renewable hydrogen production. Researchers recently discovered a family of cobalt molybdenum nitrides with very high catalytic activity for hydrogen fuel production from water but whose chemical structure differs from known catalysts for this reaction. The atomic structures of these compounds were determined by neutron diffraction on small (~100 mg) powder samples using the Oak Ridge National Laboratory Spallation Neutron Source&rsquo;s Nanoscale-Ordered Materials Diffractometer (NOMAD) instrument. The strong sensitivity of neutron diffraction to light atoms made it possible to determine the unique location of the nitrogen atoms in the catalyst material and confirm that the superior catalytic activity of the compound Co<sub>0.6</sub>Mo<sub>1.4</sub>N<sub>2</sub>, compared to binary MoN, was due to the octahedral Mo environment.</p>{53299936-B154-4FEB-B080-D3223B7C158F} Smart Windows<img src='/~/media/A0644F87DCB7406687CAE480D27CE687.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Thin coating of nanocrystals embedded in glass can electrically control light and heat from sunlight as it passes through a window.Wed, 07 Jan 2015 16:56:56 -0500<p>To make buildings more energy efficient, controlling the visible light and heat-producing near-infrared (NIR) light is essential to reduce energy costs spent on lighting and regulating building interiors.&nbsp; Researchers have developed a &ldquo;smart&rdquo; glass that can switch between blocking light, heat or both, depending on how much voltage is applied.&nbsp;At the heart of their technology is a new &ldquo;designer&rdquo; electrochromic material, made from nanocrystals of indium tin oxide embedded in a glassy matrix of niobium oxide. Electrochromism is a reversible process that allows the glass to change its light and heat transmittance as well as optical transmittance in response to electrochemical charging and discharging. The resulting composite material combines two distinct functionalities&mdash;one providing control over visible light and the other, control over the NIR&mdash;but it is more than the sum of its parts. The researchers found a synergistic interaction in the tiny region where glassy matrix meets nanocrystal increasing the potency of the electrochromic effect, which means they can use thinner coatings without compromising performance. The key is the way atoms connect across the nanocrystal-glass interface causes a structural rearrangement in the glass matrix. The interaction opens up space inside the glass, allowing charge to move in and out more readily. Beyond electrochromic windows, this discovery suggests new opportunities for battery materials where transport of ions through electrodes can be a challenge.</p>{B578AC7B-FACC-4DB7-BC65-D89ACFB111AD} Ice Under High Pressure<img src='/~/media/E67657756CAD4B03B042A319F03ABCA5.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New insights from neutron diffraction reveal changes to atomic structure.Wed, 07 Jan 2015 16:56:55 -0500<p>Although pressure has long been expected to dissociate hydrogen from the water molecule, all present theoretical models for water predict that this occurs smoothly, with the hydrogen atoms lying close to their sites in the original molecules. However, researchers using neutron-diffraction measurements have revealed an unexpected and more dramatic mechanism for pressure-induced dissociation of so-called heavy water (D<sub>2</sub>O), and by inference regular water (H<sub>2</sub>O). What the researchers working at the Spallation Neutron Source (SNS) discovered is that approximately 25% of the protons were dissociated from the molecule, and moved to holes (octahedral voids) in the oxygen lattice. The existence of these displaced protons in this high pressure form of ice (called ice VII) has important implications for the structures of other phases of ice that occur at even higher pressures. In particular, a phenomenon called &ldquo;superionicity&rdquo; could occur in ice under more extreme conditions and has been proposed as a source of magnetic field generation in Neptune and Uranus. The key to unraveling the unexpected ice structure lay in the high sensitivity of neutron scattering to hydrogen (as compared with X-rays used previously) combined with the high intensity of the SNS neutron source and the unique capabilities of an instrument called SNAP (Spallation Neutrons and Pressure). This instrument is used to study materials under extreme pressures, and by using a new type of diamond anvil pressure cell, scientists have been able to conduct experiments at pressures above 90 GPa, which is a record for neutron diffraction.</p>{4D827E8F-CC53-4197-8365-D1EDB9C4F6C8} Lead to More Warming than Climate Models Predicted<img src='/~/media/76ADC6FD35214C91AE9B575A6E39B2A4.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Aerosol observations shed light on impact of soot and smoke.Fri, 19 Dec 2014 14:59:00 -0500<p>Evaluating wildfire effects on climate requires better understanding the properties of aerosols emitted during burning events. Using high-precision instruments, a research team from Michigan Technological University and Los Alamos National Laboratory analyzed aerosol samples collected over 10 days in Las Conchas, New Mexico, from a smoldering fire that was the largest in state history. The team found that smoke from the fire contained significant quantities (10 times more than previously thought) of a special type of spherical carbon-rich aerosol known as &ldquo;tar balls&rdquo; that strongly absorb sunlight and cause warming. Researchers also found that organic substances in the smoke almost always coat soot particles, 50% of which were coated completely in this particular study. The coating acts as a lens that focuses and amplifies the amount of sunlight a soot particle absorbs. Contrary to climate model assumptions, tar balls and coated soot particles in smoke do not cancel out each other&rsquo;s effect, but together more than double the amount of warming at the surface. Paucity of relevant data so far has resulted in an incomplete, perhaps even inaccurate, understanding of the impact of wildfires on climate.</p>{D247AAC9-2B18-4137-A9D2-17D332384AF2} U.S. Methane Sources May Be Larger than Previously Thought<img src='/~/media/D2865C916B19411A85AF01BBF0F0C800.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Inventories underestimate emissions from fossil fuel industry and animal husbandry, study finds.Fri, 19 Dec 2014 14:58:59 -0500<p>Atmospheric CH<sub>4</sub> observations from eddy covariance towers and aircraft, along with results from a high-resolution atmospheric transport model, were compared to inventories from the U.S. Environmental Protection Agency and the Emissions Database for Global Atmospheric Research (EDGAR). The study indicates that these inventories underestimate CH<sub>4</sub> emissions nationally by a factor of &sim;1.5 to &sim;1.7, respectively, and that emissions due to ruminant animals (livestock) and manure are up to twice the magnitude of existing inventories. The discrepancy in CH<sub>4</sub> estimates is particularly pronounced in the south-central United States, where total emissions are &sim;2.7 times greater than in most inventories and account for ~24% of national emissions. The spatial patterns of emission fluxes and observed CH<sub>4</sub> -propane correlations indicate that fossil fuel extraction and refining are major contributors (~45%) in the south-central United States. This result suggests that regional CH<sub>4</sub> emissions due to fossil fuel extraction and processing could be nearly five times larger than in EDGAR, the most comprehensive global CH<sub>4</sub> inventory.</p>{88002267-243D-4AED-BE68-2887CEE73DA6} Ice Sheet “Sliding” a Small Contributor to Future Sea-Level Rise<img src='/~/media/C0518B2777784B7C89B88C6A3C497457.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Modeling experiments assess impacts of key melting behavior.Fri, 19 Dec 2014 14:58:59 -0500<p>A wide range of observations suggests that water generated by melt at the ice sheet surface reaches the bed by both fracture and drainage through moulins (roughly circular, vertical to nearly vertical well-like shafts within a glacier through which water enters from the surface). However, these observations are insufficient to determine whether the water enhances ice flow. The research team performed a modeling analysis, varying flow formulations to find two contrasting possibilities: continuously increasing or bounded changes in lubrication and glacier speed with increased meltwater input. These contrasting scenarios were applied to four sophisticated ice sheet models in a series of experiments for a warmer future scenario, forced by likely changes in ice sheet surface mass, lubrication, and a combination of these. The team determined that additional sea-level rise resulting from lubrication is small (&le;8 mm) in comparison with that from experiments forced only by changes in surface mass balance (~170 mm). Although changes in lubrication generate widespread effects on ice sheet flow and form, they do not substantially affect net mass loss.</p>{E4A17481-7B0A-4311-BCFA-A847AA0D52E6} Water Projections and Climate Change<img src='/~/media/48A9E46DF6B9428FBD7380A3517FDFE3.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Model scenarios predict increased scarcity in the Middle East and India.Fri, 19 Dec 2014 14:58:58 -0500<p>Department of Energy scientists at Pacific Northwest National Laboratory, in collaboration with a multi-institutional team, used the Global Change Assessment Model to evaluate future water demands representing six socioeconomic scenarios. The modeling framework explicitly tracks future water demands for the agricultural, energy (electricity generation and primary energy production and processing), industrial (manufacturing and mining), and municipal sectors. The energy, industrial, and municipal sectors are represented in 14 geopolitical regions, with the agricultural sector further disaggregated into as many as 18 agro-ecological zones within each region. The scenarios showed increases in annual global water withdrawals from 3710 km<sup>3</sup> in 2005, to 6195&ndash;8690 km3 in 2050, and 4869&ndash;12,693 km<sup>3</sup> in 2095. Comparing the projected total regional water withdrawals to the historical supply of renewable freshwater, the Middle East exhibits the highest levels of water scarcity throughout the century, followed by India&mdash;with scarcity increasing over time in both regions. In contrast, water scarcity improves in some regions with large base-year electric sector withdrawals, such as the United States and Canada, due to capital stock turnover and the almost complete phase-out of once-through flow cooling systems. </p>{3474DA13-AD78-48BB-9664-DD9CBFE64360} Yields of Advanced Biofuels from Genetically Engineered Yeast<img src='/~/media/3D5E4C2B4F3946319ED466966FBB061F.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Strains produce “drop-in” fuels and chemicals derived from fatty acids.Fri, 19 Dec 2014 14:58:58 -0500<p>Diesel fuels are composed mainly of long-chain hydrocarbon esters similar to the fatty acids produced by yeast and other microorganisms for construction of their cell membranes. Engineering yeast to overproduce fatty acids is no easy task because elaborate regulatory and feedback systems prevent excessive accumulation of these building blocks. To overcome this hurdle, researchers at the DOE Joint BioEnergy Institute replaced the highly-regulated native promoters for fatty acid production machinery with new high-intensity promoters. These promoters are effectively always &ldquo;on,&rdquo; directing the cell to make more machinery for fatty acid assembly. The researchers also engineered cellular machinery to reroute fatty acids from cell membrane manufacture to free fatty acids that can be transformed through industrial processes to drop-in biofuels. These engineering changes led to a more than 500-fold increase in production of free fatty acids when compared to the native strain. Strains also were engineered to produce drop-in biofuels directly, rerouting fatty acids into fatty alcohols and fatty acid ethyl esters that can be used in diesel engines. With these increased yields of fatty alcohols and fatty acid ethyl esters, this work represents a major advance toward production of next-generation drop-in biofuels.</p>{CDF959CC-A450-4877-8D6F-E983C5BD0E6D} Climate Model Simulations of Clouds<img src='/~/media/55F950E0DC22430DB2A7B4CA16DCA183.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New models show reduction in bias associated with too many highly reflective clouds.Fri, 19 Dec 2014 14:58:57 -0500<p>Climate model projections of the amount of Earth&rsquo;s warming due to an increase in greenhouse gases vary widely because of different simulated responses of clouds to warming. Model cloud predictions are variable because clouds are among the least well simulated components of climate models despite much effort over many years to improve such simulations. In this study, Department of Energy scientists from Lawrence Livermore National Laboratory measure whether the ability of climate models to simulate clouds has improved in the newest generation of climate models being assessed for reports of the Intergovernmental Panel on Climate Change. The team examined the ability of 19 climate models to simulate climatological cloud amount, reflectivity, and altitude in comparison with satellite observations and found that cloud simulations are improving. In the newest models, there is widespread reduction of a bias associated with too many highly reflective clouds, with the best models having eliminated this bias. Models with increased amounts of clouds with lesser reflectivity show a significant reduction in the &ldquo;too few, too bright&rdquo; problem because the time-mean radiation balance is well-simulated by having the compensating errors of too few clouds that are too reflective.</p>{6DEAAD06-9072-46EC-A10C-58003ACA0111} Species of Bacteria Convert Elemental Mercury to Toxic Methylmercury<img src='/~/media/3424F30BD97C4C33BF3DD76CE454F136.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New insights could assist in cleanup of contaminated environments.Fri, 19 Dec 2014 14:58:57 -0500<p>Because elemental mercury has been considered to be relatively inert and is volatile, remediation approaches have focused on converting toxic forms of mercury into elemental mercury that would then bubble out of surface water and dissipate. In this study, researchers found that some bacterial species can both oxidize and methylate elemental mercury, others require the presence of a specific amino acid to perform these conversions, and still others can only oxidize elemental mercury. These findings suggest that both methylating and nonmethylating bacteria can enhance the formation of toxic methylmercury in anaerobic environments.</p>{84FB97CB-B612-4854-B085-A9709E28FD87} Sequence of a Marine Blooming Alga<img src='/~/media/D25B7396343B4000A977ED3306AE1879.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Genome variability helps explain why <em>Emiliania huxleyi </em>canflourish in diverse ocean habitats.Fri, 19 Dec 2014 14:58:57 -0500<p>The Department of Energy Joint Genome Institute (DOE JGI) has sequenced the <em>E. hux</em><em>leyi </em>genome and compared it with sequences from 13 other algal isolates. The large and complex <em>E. huxleyi </em>genome indicates that these phytoplanktondo not exist as a clearly defined species with a uniform genome. Instead, they represent a more diffuse community&mdash;a &ldquo;pan genome&rdquo;&mdash;with different individuals possessing a shared core of genes supplemented by different gene sets to cope with the particular challenges of a local environment. DOE JGI and its collaborators found that the core genes include those that allow <em>E. hux</em><em>leyi &nbsp;</em>to survive in low levels of phosphorus and assimilate and break down nitrogen-rich compounds. This sequencing effort represents the first ever algal pan genome.</p>{0B88B238-D71F-4FC4-9AA6-A10A49A45182} Cellulose More Accessible for Bioconversion<img src='/~/media/78AE123812D447988D3C3AD3EC3757E9.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Simulations and neutron diffraction reveal how amines disrupt cellulose’s structure.Fri, 19 Dec 2014 14:58:56 -0500<p>Research by an international team led by scientists at Oak Ridge National Laboratory combines neutron fiber diffraction and computational simulation to show how ethylene diamine (EDA, a representative amine solvent) binds to cellulose fibers. Experimental neutron diffraction data for EDA-cellulose complexes were the starting points for quantum chemical construction of optimized atomic-level structures that were then studied using computational molecular dynamics simulations. Results demonstrate how EDA disrupts normal hydrogen bonding in cellulose fibers, and the simulations explain the dynamic nature of EDA&rsquo;s action.</p>{2C1134B7-100F-409D-90B2-3B477E19F303} Global Wetlands and Their Methane Emissions<img src='/~/media/48420D09303D4703A1914AD109D55C98.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Climate model comparisons show wetlands remain a big challenge.Fri, 19 Dec 2014 14:58:55 -0500<p>To study the importance of wetlands in the global water and carbon cycles, a variety of hydrological and biogeochemical models have been developed over the last three decades. The Wetland and Wetland CH<sub>4</sub> Intercomparison of Models Project is assessing the ability of these models to simulate large-scale wetland characteristics and their CH<sub>4</sub> emissions, essential for evaluating key uncertainties in the mechanisms and parameters leading to such emissions. Ten modeling groups, including Department of Energy (DOE) researchers at Lawrence Berkeley National Laboratory, ran eight global and two regional models with a common experimental protocol using the same climate and atmospheric carbon dioxide (CO<sub>2</sub>) forcing datasets. The models demonstrate extensive disagreement in their simulations of wetland areal extent and CH<sub>4</sub> emissions, in both space and time. All models show a strong positive response to increased atmospheric CO<sub>2</sub> concentrations, in both CH<sub>4</sub> emissions and wetland area. In response to increasing global temperatures, the models, on average, show decreased wetland area and CH<sub>4</sub> fluxes, primarily in the tropics, but the magnitude and sign of the response varied greatly. Models were least sensitive to increased global precipitation, demonstrating a consistent small positive response in CH<sub>4</sub> fluxes and wetland area. Existing wetland CH<sub>4</sub> observation datasets are insufficient for evaluating model fluxes, severely restricting the ability to model global wetland CH<sub>4 </sub>emissions with confidence. The large range in predicted CH<sub>4</sub> emission rates suggests that there is both substantial parameter and structural uncertainty in large-scale CH<sub>4</sub> emission models, even after uncertainties in wetland areas are accounted for. Clearly, significant research is needed both in modeling and measuring wetland sources of CH<sub>4</sub> and their responses to climate.</p>{9A73C853-D960-4713-B069-399A941FCD3A} Forest Carbon Right in Climate Models<img src='/~/media/B62D68BC708D4AD6B322313957459E53.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New method predicts how climates will move as temperatures rise.Fri, 19 Dec 2014 14:58:55 -0500<p>A Department of Energy (DOE) scientist at Lawrence Berkeley National Laboratory developed a simple model for vegetation carbon response that predicts where a given climate for a region is going in the future and where a given climate will come from. His &ldquo;climate analogue&rdquo; method tracks the movement of the most statistically similar climate at every location in an ESM over an interval of time and recalculates the carbon flux within the ESMs participating in the Coupled Model Intercomparison Project 5. The most important area of disagreement between this simple method and the full ESM calculations involves southern boreal forests, where ESMs predict carbon gains, while the simplified approach projects losses.</p>{94143E4F-0770-4E05-9CD1-689E33000AFE} How Bacteria Communicate<img src='/~/media/E5DA27919E064CB5A7413D3B232B8AA3.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>New tool identifies molecules that influence microbial communities.Fri, 19 Dec 2014 15:00:37 -0500<p><em>Synechococcus</em> sp. PCC 7002 was found to steadily secrete two molecules, sucrose and glucosylglycerol, that could be used as resources by nearby bacteria. To chemically profile the microbial communities in both space and time, researchers used a technique called nanospray desorption electrospray ionization mass spectrometry, or nanoDESI, developed at the Environmental Molecular Sciences Laboratory, a DOE scientific user facility.</p>{73A7B793-11B0-482B-A07D-1FC70DEB6008} Soot’s Effect on Snow Reflectivity<img src='/~/media/56E7C0AFBA2A412A96B98F7674E9AB44.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Model comparison evaluates black carbon levels and impacts.Fri, 19 Dec 2014 15:00:37 -0500<p>As part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), Department of Energy scientists at Pacific Northwest National Laboratory compared historical black carbon aerosols simulated by eight ACCMIP models with observations including ice core records, long-term surface mass concentrations, and recent measurements of Arctic black carbon snowpack. The global black carbon burden from preindustrial to present-day levels increased 2.5 to 3 times with little variation among models, roughly matching the 2.5-fold increase in total black carbon emissions estimated during the same period. However, the models diverged substantially at both Northern and Southern Hemispheric high-latitude regions for black carbon burden and at Southern Hemispheric high-latitude regions for deposition fluxes, thus reflecting differences in poleward transport among models.</p>{C7835235-6811-4C55-BF7E-D0594E1AC12E} in High Clouds Cools Climate<img src='/~/media/B08A6E085AC24ED28D5438A9DB5515BC.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Study examines impact of ice particle competition.Fri, 19 Dec 2014 15:00:36 -0500<p>Clouds that exist high in the atmosphere trap long-wave radiation and warm the climate. However, dust, derived from natural sources such as deserts and from industrial and human activities including soil disruption, appears to have an important effect on these cold clouds. Led by a scientist at the Department of Energy&rsquo;s Pacific Northwest National Laboratory, a team of researchers used the Community Atmospheric Model version 5 (CAM5) to study the effect of dust on upper tropospheric cirrus clouds. These clouds tend to enhance ice particle formation when water vapor or droplets freeze on dust in a process called heterogeneous ice nucleation. The ice particles typically fall out or precipitate. Although scarce, heterogeneous ice nuclei could impact ice crystal number concentration, compared to standard droplet (homogeneous) freezing, by initiating ice nucleation earlier, depleting available water vapor, and hindering the occurrence of homogeneous freezing. Using two model formulations that consider homogeneous and heterogeneous nucleation and the competition between them, the team found heterogeneous nucleation on dust aerosol reduces the frequency of homogeneous nucleation and thus the number of ice crystals in the Northern Hemisphere. This drying of the heat-trapping clouds affects Earth&rsquo;s radiative balance, resulting in a net cooling of the climate.</p>{C85AA36C-0AD4-4229-AAC4-948E6146E54C} Decade of Atmospheric Research in the Tropical Western Pacific<img src='/~/media/7271E846C617464AB60F7E0F355FD370.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Long-term ARM datasets critical for cloud and solar energy studies.Fri, 19 Dec 2014 15:00:36 -0500<p>Because of its remote location, ground-based datasets of cloud, atmosphere, and radiation properties from the TWP region traditionally have come primarily from short-term field experiments. However, these short-term datasets provide only limited statistical and climatological information. To obtain long-term measurements of the surface radiation budget in the tropics and the atmospheric and cloud properties that affect it, ARM established TWP measurement sites in 1996. The PNNL team&rsquo;s analysis gives examples of the wide range of scientific uses of these unique long-term datasets, including characterization of cloud properties, analysis of cloud radiative forcing, model studies of tropical clouds and processes, and validation of satellite algorithms. The impact of recently installed instrumentation on new opportunities for tropical atmospheric science also is discussed. The study highlights contributions of ARM TWP data to increased knowledge of tropical cloud systems and the tropical surface radiation budget.</p>{DFF5CE19-ADA2-40A4-B82F-19296A37B13D} Soil Bacterium Frees Plant Sugars for Biofuels<img src='/~/media/8AC9C2DA5A034980835CA9DAD60AD658.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Microbe found to use two biochemical pathways for degrading lignin.Fri, 19 Dec 2014 15:00:36 -0500<p>The research team&mdash;including scientists from the University of Massachusetts&ndash;Amherst, the U.S. Department of Energy (DOE) Joint BioEnergy Institute, and the DOE Environmental Molecular Sciences Laboratory (EMSL)&mdash;used proteomic, transcriptomic, and metabolomic approaches at EMSL to examine the ability of <em>E. lignolyticus</em> SCF1 to degrade lignocellulose. Their study reveals that this bacterium can break down the lignin portion of cellulosic biomass by both an assimilatory pathway for use as food and a dissimilatory pathway for respiration. This is the first demonstration of an anaerobic soil bacterium using both pathways to reduce lignocellulose. By breaking down lignin, SCF1 is able to free the cellulosic sugars found in plant cells, thereby making those sugars available for use in biofuels. The study also demonstrates the importance of using a holistic, multi-&ldquo;omics&rdquo; approach to examine biochemical processes in microbes.</p>{6F6ADEE6-C885-40E4-9005-AE10691D0FB7} the Evolution of a Protein’s Function<img src='/~/media/659B291264BE4E4D99138F4DA545B2FD.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Study reveals structural changes leading to catalytic activity.Fri, 19 Dec 2014 15:00:36 -0500<p>Enzymes are proteins structurally configured to catalyze conversions of substrates to products. Thousands of protein structures are known, including those of many valuable enzymes. However, much less is known about how small changes in a protein&rsquo;s composition can alter its three-dimensional structure, control its catalytic efficiency, or even convert a protein with no catalytic function into an efficient catalyst. Scientists in this study used an extended X-ray absorption fine structure (EXAFS) station at the Stanford Synchrotron Radiation Lightsource to determine the active-site structure of a newly synthesized enzyme. The EXAFS experiments were able to show the exact chemical environment of each zinc atom in the new enzyme, leading to an explanation of why it developed the catalytic activity.</p>{37ACCE4F-32C8-44CA-9F54-C188A4DED2D2} Rainfall Processes in Climate Models<img src='/~/media/DECFA80E7C3A48039C3389D2BCE509F3.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Long-term ARM data used to evaluate precipitation simulations.Fri, 19 Dec 2014 15:00:35 -0500<p>The single-column model (SCM), which isolates a single grid column from a global model, is a useful and effective tool for studying parameterization schemes in GCMs. However, most SCM intercomparison studies with Atmospheric Radiation Measurement (ARM) data focus on special cases or week-to-month-long periods. To make a statistically meaningful comparison and evaluation of modeled precipitation, researchers have completed SCM simulations of seven GCMs participating in the&nbsp; &ldquo;FASTER&rdquo; project led by Brookhaven National Laboratory and compared the models&rsquo; performance to 3 years of observations at the ARM Southern Great Plains site. Results show that, although most SCMs can reproduce observed precipitation reasonably well, significant differences and deficiencies exist. These include problems in frequency-intensity trade-off during cold seasons, too much rain during the day rather than at night, and differences in how various models partition rain between convective and stratiform clouds. Further analysis reveals distinct meteorological backgrounds for model precipitation underestimation and overestimation, offering clues to why the models are deficient.</p>{79FA4CCA-59E1-4C52-8B1F-3A1EB11FD444} Signaling Responses to Low-Dose Radiation<img src='/~/media/9B44A6FB290644F6B2FCA9C3861148D8.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Study shows protein moves to nucleus, helps irradiated cells survive.Fri, 19 Dec 2014 15:00:35 -0500<p>Scientists at Pacific Northwest National Laboratory are working to define signaling pathways activated by low doses of radiation. Their previous studies found that the protein annexin A2 is involved in the malignant transformation of cultured mouse epidermal cells by radiation. The researchers now demonstrate that both high and low doses of ionizing radiation increase A2 annexin levels in the nuclei of human and mouse monolayer cultures and in a human skin tissue model, thus supporting a conserved nuclear function for annexin A2. Whole-genome expression profiling in the presence and absence of annexin A2 identified altered transcriptional programming that changes the radioresponsive transcriptome. Bioinformatics predicted that silencing A2 may enhance cell death responses to stress associated with reduced activation of survival signals. The researchers validated the prediction by demonstrating that the A2-silenced cells were more likely than control cells to die after treatment with tumor necrosis factor alpha. Collectively, the data suggest that annexin A2 functions to regulate cell fate, which could impact the biological response to radiation.</p>{E40ED443-15B1-4A54-8FEB-470657679C46} Science on the Horizon as Upgraded Particle Accelerator Meets Commissioning Milestones<img src='/~/media/24B4C6580552426EBA7E4B300193A0E7.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>The recently upgraded CEBAF accelerator delivers its highest-energy electron beams into a new experimental complex for the first time.Tue, 25 Nov 2014 10:11:21 -0500<p>The CEBAF accelerator is based on superconducting radiofrequency (SRF) technology and produces a stream of charged electrons. CEBAF was the first large-scale application of SRF technology in the U.S., and it is the world's most advanced particle accelerator for investigating the quark structure of the atom's nucleus. The 12 GeV CEBAF Upgrade is a $338 million DOE project to double the accelerator's maximum operational energy and includes upgrades to equipment in three existing halls, as well as the construction of a fourth experimental hall, Hall D. In the last steps of accelerator systems commissioning before its summer shutdown, the machine delivered its highest-energy beams ever, 10.5 GeV, through the entire accelerator and through the newly installed beamline to the Hall D Tagger Facility, where CEBAF's electron beam is converted into the photons that will be used for studying quark confinement in Hall D. Commissioning will continue in FY2015 in order to achieve the full 12 GeV energy and to send beams to Jefferson Lab's experimental halls for commissioning the new spectrometers and the start of experiments.</p>{73E171FC-1F93-401A-9B6B-597658F0091B} Tunneling Affects Engine Performance<img src='/~/media/609B9958D0134D72A522EE8ABFE6F285.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Understanding fundamental chemistry is important for accurate engine modeling.Wed, 07 Jan 2015 16:57:03 -0500<p>Researchers have recently studied the role of individual reaction rates on engine performance, with an emphasis on the role of quantum tunneling, an exclusively quantum mechanical phenomenon whereby a product can emerge even if reactants have insufficient energy to overcome forces impeding the reaction. Actual combustion processes occurring in engines are profoundly complex, with engine performance emerging from myriad chemical reactions interacting in the engine environment. Accurate computational models including this complexity have been prohibitively difficult to implement. For this reason, practical combustion simulators seldom include all of the underlying chemical detail and may miss important molecular-level quantum mechanical effects. This research demonstrated that quantum tunneling corrections for the rate of the reaction HO<sub>2</sub> + HO<sub>2</sub> = H<sub>2</sub>O<sub>2</sub> + O<sub>2</sub> can have a noticeable impact on the performance of a high-fidelity model of a diesel engine. The three-dimensional model included detailed descriptions of the chemistry of a surrogate for a biodiesel fuel, as well as all the features of the engine, such as the liquid fuel spray and turbulence. This study was part of a larger investigation of how the molecular &ndash;level features of key chemical reactions, their dynamics and potential energy surfaces, as well as their reaction rate uncertainties, affected engine performance.</p>{6B93A965-6248-4B0E-915F-A7E984932B19} Metals for Better Catalysis: A New Type of Metal-Support Interaction<img src='/~/media/5A145E6765254203B7BDEF2AA830DB6D.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Designing a novel catalyst for the production of hydrogen.Wed, 07 Jan 2015 16:57:02 -0500<p>BES-supported researchers at Brookhaven National Laboratory discovered a new type of metal-support interaction useful for the development of more efficient catalysts. Catalysts are often "supported," meaning the most active component, usually a noble metal, is dispersed as nanoparticles or thin layers over a high surface-area material (usually an oxide) to improve catalyst effectiveness by exposing more of the active component to the reacting fluid. The main function of the support is to spread out the active component and prevent its aggregation or clustering which lower overall activity. In addition, the support possesses chemical functions on its surface and at the interface with the active components that contribute strongly to the catalytic reaction. In heterogeneous catalysis, the Pt/TiO<sub>2</sub> system can be affected by &ldquo;strong metal-support interactions,&rdquo; which usually deactivate platinum possibly due to small aggregates of TiO<sub>2</sub> decorating the surface of the Pt particles. However, this study observed a completely different phenomenon. The results of valence photo-emission and density functional calculations point to a new type of &ldquo;strong metal-support interaction&rdquo; which produces large electronic perturbations for small Pt particles in contact with ceria and significantly enhances the ability of Pt to produce hydrogen by dissociating the O-H bonds in water. This catalytic activity of Pt increases further when TiO<sub>2</sub> is introduced to support the Pt/CeO<sub>x</sub> catalyst. This new type of &ldquo;strong metal-support interactions&rdquo; could play an important role when designing metal/oxide catalysts containing Pt to increase overall catalytic activity.</p>{5C19FF82-A777-464C-8A4A-86965E93E5E0} To Be or Not to Be Crystalline?<img src='/~/media/3BE464149BEC41A989748C50993EEF8D.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Discovery of coexisting ordered and disordered catalytic nanoparticles.Wed, 07 Jan 2015 16:57:01 -0500<p>The synthesis and unusual size-dependent properties of nanostructures between 1-10 nm, including metal nanoparticles (NPs), are the subject of intense research due to their exceptional promise in advancing catalysis for fuel and chemical manufacturing as well as drug synthesis and magnetic devices. Due to its role in energy production and, hence, worldwide economy, catalysis depends on NPs structure and the substrate and gaseous environment. Though descriptions of bulk and atomic properties of matter are well established, critical questions remain about the behavior and kinetics of nanoparticles in mesoscopic regimes. To address these questions, the structure, chemical state, and phase transformations of platinum (Pt) nanoparticles were characterized in real time and in their operational environments. The non-crystalline-to-crystalline transition of supported Pt NPs in the sub-nanometer to nanometer size range was shown to be statistical in nature, and strongly affected by particle size, support, and adsorbates. Unlike in bulk conditions, a non-crystalline phase exists that is stable. Observations of over 3000 particles by high-resolution transmission electron microscopy show a non-crystalline-to-crystalline transition zone that is non-abrupt &ndash; there is a size regime where disordered and ordered NPs coexist. The NP size at which this transition occurs is strongly dependent on both the adsorbate and the support.</p>{A648BF20-EEB3-46D1-BA3D-903D86E63B46} Decoration of “Gooey” Surface<img src='/~/media/E49E65F72CF54D0F90786570E1F3E344.ashx' align='left' style='height:75px;width:135px;margin-right:10px;margin-bottom:10px;'/>Precise, predictable positioning of nanoparticles on a liquid crystal droplet.Wed, 07 Jan 2015 16:57:01 -0500<p>For the first time, the ability of liquid crystals to control the organization of particles on a spherical surface has been demonstrated. Conceptually, this approach mimics how specific features on membrane surfaces control the organization of lipids or proteins within a cell. Liquid crystals are comprised of elongated molecules that adopt a uniform orientation in a liquid phase and the surface-mediated electrical manipulation of this orientation is the key operating factor in modern display technologies. Now, researchers at the University of Chicago and the University of Wisconsin-Madison have demonstrated the predictable positioning of small particles on a liquid crystal surface based solely on the orientation of the liquid crystal molecules. Using a powerful combination of theory, computer simulations and experimental observations, they have shown that liquid crystals encapsulated in spherical droplets can control the assembly of small particles located at their surfaces, much like how the polarized structural organization of a component of a living cell, the Golgi complex, influences protein orientation. When droplets were comprised of a simple liquid, the particles on the surface adopted a random distribution. In contrast, when the droplets were comprised of liquid crystal, the surface molecules adopted ordered structures or nanophases containing one or two points or nodes at which fluorescent polystyrene particles were anchored. The attraction between the particles and these anchoring sites was particle-size dependent: The smallest particles roamed in the interior of the droplet whereas larger particles remained anchored at these sites until the liquid crystalline organization was disrupted by heating of the droplet. Interestingly, larger particles placed on the droplet surface away from these anchoring sites quickly migrated across the surface to them. If this assembly process can be extended to higher surface coverages of particles, such liquid crystalline nanophases could have important implications for design and assembly of functional three-dimensional structures with high fidelity.</p>