Showing papers by "Michigan Technological University published in 2016"
University of Minnesota1, University of Michigan2, Florida State University3, University of Twente4, Queen's University Belfast5, University of California, Berkeley6, University of Belgrade7, University of Bristol8, University of Padua9, University of York10, Osaka University11, Loughborough University12, Leibniz Association13, Brno University of Technology14, Academy of Sciences of the Czech Republic15, Comenius University in Bratislava16, École Polytechnique17, Ulster University18, Clarkson University19, Michigan Technological University20, University of Antwerp21, Lublin University of Technology22, University of Montpellier23, Eindhoven University of Technology24, Max Planck Society25, University of Alberta26, Durham University27, Lawrence Berkeley National Laboratory28, National Institute of Advanced Industrial Science and Technology29, Saint Petersburg State University30
TL;DR: A review of the state-of-the-art of this multidisciplinary area and identifying the key research challenges is provided in this paper, where the developments in diagnostics, modeling and further extensions of cross section and reaction rate databases are discussed.
Abstract: Plasma–liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on non-equilibrium plasmas.
1,078 citations
University of Queensland1, University of Western Australia2, Harvard University3, Louisiana State University4, University of Utah5, Princeton University6, Amsterdam University College7, George Mason University8, Texas A&M University9, University of Bristol10, Michigan Technological University11, California Institute of Technology12, University of Edinburgh13
TL;DR: The consensus that humans are causing recent global warming is shared by 90% to 100% of publishing climate scientists according to six independent studies by co-authors of this paper as discussed by the authors.
Abstract: The consensus that humans are causing recent global warming is shared by 90%–100% of publishing climate scientists according to six independent studies by co-authors of this paper. Those results are consistent with the 97% consensus reported by Cook et al (Environ. Res. Lett. 8 024024) based on 11 944 abstracts of research papers, of which 4014 took a position on the cause of recent global warming. A survey of authors of those papers (N = 2412 papers) also supported a 97% consensus. Tol (2016 Environ. Res. Lett. 11 048001) comes to a different conclusion using results from surveys of non-experts such as economic geologists and a self-selected group of those who reject the consensus. We demonstrate that this outcome is not unexpected because the level of consensus correlates with expertise in climate science. At one point, Tol also reduces the apparent consensus by assuming that abstracts that do not explicitly state the cause of global warming ('no position') represent non-endorsement, an approach that if applied elsewhere would reject consensus on well-established theories such as plate tectonics. We examine the available studies and conclude that the finding of 97% consensus in published climate research is robust and consistent with other surveys of climate scientists and peer-reviewed studies.
865 citations
Pacific Northwest National Laboratory1, Yale University2, National Center for Atmospheric Research3, Marine Biological Laboratory4, Colorado State University5, Wageningen University and Research Centre6, University of California, Irvine7, Kansas State University8, University of Oregon9, Michigan Technological University10, University of Sydney11, University of Minnesota12, Duke University13, University of Tennessee14, University of Copenhagen15, Spanish National Research Council16, University of New Hampshire17, Northeast Normal University18, University of California, Berkeley19, University of Oklahoma20, Hungarian Academy of Sciences21, Swedish University of Agricultural Sciences22, University of Manchester23, Tsinghua University24, National University of Singapore25, Chinese Academy of Sciences26, University of Hohenheim27, University of Georgia28, Hampshire College29, Boston University30, University of Alaska Anchorage31
TL;DR: In this article, the authors present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia, and provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections.
Abstract: The majority of the Earth's terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 ± 30 petagrams of carbon to 203 ± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 ± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12-17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon-climate feedback that could accelerate climate change.
787 citations
TL;DR: In this paper, a combination of first-principles calculations, acoustic impulse excitation measurements, and nanoindentation experiments are used to determine the elastic constants and moduli for high-conductivity LLZO compositions based on Al and Ta doping.
Abstract: The oxide known as LLZO, with nominal composition Li7La3Zr2O12, is a promising solid electrolyte for Li-based batteries due to its high Li-ion conductivity and chemical stability with respect to lithium. Solid electrolytes may also enable the use of metallic Li anodes by serving as a physical barrier that suppresses dendrite initiation and propagation during cycling. Prior linear elasticity models of the Li electrode/solid electrolyte interface suggest that the stability of this interface is highly dependent on the elastic properties of the solid separator. For example, dendritic suppression is predicted to be enhanced as the electrolyte’s shear modulus increases. In the present study a combination of first-principles calculations, acoustic impulse excitation measurements, and nanoindentation experiments are used to determine the elastic constants and moduli for high-conductivity LLZO compositions based on Al and Ta doping. The calculated and measured isotropic shear moduli are in good agreement and fall ...
387 citations
TL;DR: A third class of metallic bioabsorbable materials that are based on zinc has been introduced in the last few years and demonstrates the potential for an absorbable metallic stent with the mechanical and biodegradation characteristics required for optimal stent performance.
Abstract: Metallic stents are used to promote revascularization and maintain patency of plaqued or damaged arteries following balloon angioplasty. To mitigate the long-term side effects associated with corrosion-resistant stents (i.e., chronic inflammation and late stage thrombosis), a new generation of so-called "bioabsorbable" stents is currently being developed. The bioabsorbable coronary stents will corrode and be absorbed by the artery after completing their task as vascular scaffolding. Research spanning the last two decades has focused on biodegradable polymeric, iron-based, and magnesium-based stent materials. The inherent mechanical and surface properties of metals make them more attractive stent material candidates than their polymeric counterparts. A third class of metallic bioabsorbable materials that are based on zinc has been introduced in the last few years. This new zinc-based class of materials demonstrates the potential for an absorbable metallic stent with the mechanical and biodegradation characteristics required for optimal stent performance. This review compares bioabsorbable materials and summarizes progress towards bioabsorbable stents. It emphasizes the current understanding of physiological and biological benefits of zinc and its biocompatibility. Finally, the review provides an outlook on challenges in designing zinc-based stents of optimal mechanical properties and biodegradation rate.
310 citations
TL;DR: In this paper, a coupled simulation model is developed for both PV production and agricultural production to evaluate the technical potential of scaling agrivoltaic systems, and the results showed that the value of solar generated electricity coupled to shade-tolerant crop production created an over 30% increase in economic value.
Abstract: In order to meet global energy demands with clean renewable energy such as with solar photovoltaic (PV) systems, large surface areas are needed because of the relatively diffuse nature of solar energy. Much of this demand can be matched with aggressive building integrated PV and rooftop PV, but the remainder can be met with land-based PV farms. Using large tracts of land for solar farms will increase competition for land resources as food production demand and energy demand are both growing and vie for the limited land resources. This land competition is exacerbated by the increasing population. These coupled land challenges can be ameliorated using the concept of agrivoltaics or co-developing the same area of land for both solar PV power as well as for conventional agriculture. In this paper, the agrivoltaic experiments to date are reviewed and summarized. A coupled simulation model is developed for both PV production (PVSyst) and agricultural production (Simulateur mulTIdisciplinaire les Cultures Standard (STICS) crop model), to gauge the technical potential of scaling agrivoltaic systems. The results showed that the value of solar generated electricity coupled to shade-tolerant crop production created an over 30% increase in economic value from farms deploying agrivoltaic systems instead of conventional agriculture. Utilizing shade tolerant crops enables crop yield losses to be minimized and thus maintain crop price stability. In addition, this dual use of agricultural land can have a significant effect on national PV production. The results showed an increase in PV power between over 40 and 70 GW if lettuce cultivation alone is converted to agrivoltaic systems in the U.S. It is clear, further work is warranted in this area and that the outputs for different crops and geographic areas should be explored to ascertain the potential of agrivoltaic farming throughout the globe.
307 citations
TL;DR: It is demonstrated that 2H phase of bulk MoS2 possessed an ohmic feature, whereas 1T phase of exfoliated MoS 2 nanosheets exhibited a unique memristive behavior due to voltage-dependent resistance change.
Abstract: Memristor, which had been predicted a long time ago (Chua, L. O. IEEE Trans. Circuit Theory 1971, 18, 507), was recently invented (Strukov, D. B.; et al. Nature 2008, 453, 80). The introduction of a memristor is expected to open a new era for nonvolatile memory storage, neuromorphic computing, digital logic, and analog circuit. Furthermore, several breakthroughs were made for memristive phenomena and transistors with single-layer MoS2 (Sangwan, V. K.; et al. Nat. Nanotechnol. 2015, 10, 403. van der Zande, A. M.; et al. Nat. Mater. 2013, 12, 554. Liu, H.; et al. ACS Nano 2014, 8, 1031. Bessonov, A. A.; et al. Nat. Mater. 2015, 14, 199. Yuan, J.; et al. Nat. Nanotechnol. 2015, 10, 389). Herein, we demonstrate that 2H phase of bulk MoS2 possessed an ohmic feature, whereas 1T phase of exfoliated MoS2 nanosheets exhibited a unique memristive behavior due to voltage-dependent resistance change. Furthermore, an ideal odd-symmetric memristor with odd-symmetric I–V characteristics was successfully fabricated by th...
301 citations
Langley Research Center1, Forschungszentrum Jülich2, Leibniz Association3, University of Wyoming4, Max Planck Society5, Leibniz Institute of Marine Sciences6, ETH Zurich7, Earth System Research Laboratory8, University of Mainz9, Princeton University10, National Oceanic and Atmospheric Administration11, University of Bremen12, University of Liège13, Belgian Institute for Space Aeronomy14, University of Saskatchewan15, University of Leeds16, Deutscher Wetterdienst17, Michigan Technological University18, Université libre de Bruxelles19, Karlsruhe Institute of Technology20, University of Denver21
TL;DR: A review of the advances in stratospheric aerosol research can be found in this article, with a focus on the agreement between in situ and space-based inferences of aerosol properties during volcanically quiescent periods.
Abstract: Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfate matter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes.
299 citations
Northern Arizona University1, Forest Research Institute2, University of Eastern Finland3, University of Florida4, Sewanee: The University of the South5, University of Exeter6, Commonwealth Scientific and Industrial Research Organisation7, University of Alberta8, Oak Ridge National Laboratory9, Michigan Technological University10, University of Hamburg11, National University of Singapore12, Woods Hole Research Center13, National Park Service14, Marine Biological Laboratory15, University of Alaska Fairbanks16, University of Guelph17, United States Geological Survey18
TL;DR: In this paper, a meta-analysis of soil incubation studies from the permafrost zone suggests that thawing under aerobic conditions, which releases CO2, will strengthen the carbon feedback more than waterlogged systems, which release CO2 and CH4.
Abstract: A meta-analysis of soil incubation studies from the permafrost zone suggests that thawing under aerobic conditions, which releases CO2, will strengthen the permafrost carbon feedback more than waterlogged systems, which releases CO2 and CH4. Increasing temperatures in northern high latitudes are causing permafrost to thaw1, making large amounts of previously frozen organic matter vulnerable to microbial decomposition2. Permafrost thaw also creates a fragmented landscape of drier and wetter soil conditions3,4 that determine the amount and form (carbon dioxide (CO2), or methane (CH4)) of carbon (C) released to the atmosphere. The rate and form of C release control the magnitude of the permafrost C feedback, so their relative contribution with a warming climate remains unclear5,6. We quantified the effect of increasing temperature and changes from aerobic to anaerobic soil conditions using 25 soil incubation studies from the permafrost zone. Here we show, using two separate meta-analyses, that a 10 °C increase in incubation temperature increased C release by a factor of 2.0 (95% confidence interval (CI), 1.8 to 2.2). Under aerobic incubation conditions, soils released 3.4 (95% CI, 2.2 to 5.2) times more C than under anaerobic conditions. Even when accounting for the higher heat trapping capacity of CH4, soils released 2.3 (95% CI, 1.5 to 3.4) times more C under aerobic conditions. These results imply that permafrost ecosystems thawing under aerobic conditions and releasing CO2 will strengthen the permafrost C feedback more than waterlogged systems releasing CO2 and CH4 for a given amount of C.
290 citations
Marine Biological Laboratory1, Boston University2, United States Geological Survey3, Yale University4, Michigan Technological University5, Purdue University6, University of New Hampshire7, University of Oklahoma8, Colorado State University9, University of Georgia10, University of California, Davis11, University of Minnesota12, University of Sydney13, Chinese Academy of Sciences14, University of California, Irvine15, University of Hohenheim16, University of Oregon17, University of New Mexico18, University of Arizona19, University of California, Berkeley20, University of Copenhagen21, Stanford University22, Clemson University23, University of Amsterdam24
TL;DR: The largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming, finds that although warming increases soilrespiration rates, there is limited evidence for a shifting respiration response with experimental warming.
Abstract: The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.
284 citations
TL;DR: It is suggested that global PyC production could be in the range of 116-385 Tg C yr(-1) , that is ~0.2-0.6% of the annual terrestrial net primary production, and atmospheric emissions of soot/black C might be a smaller fraction of total PyC than previously reported.
Abstract: The production of pyrogenic carbon (PyC; a continuum of organic carbon (C) ranging from partially charred biomass and charcoal to soot) is a widely acknowledged C sink, with the latest estimates indicating that ~50% of the PyC produced by vegetation fires potentially sequesters C over centuries. Nevertheless, the quantitative importance of PyC in the global C balance remains contentious, and therefore, PyC is rarely considered in global C cycle and climate studies. Here we examine the robustness of existing evidence and identify the main research gaps in the production, fluxes and fate of PyC from vegetation fires. Much of the previous work on PyC production has focused on selected components of total PyC generated in vegetation fires, likely leading to underestimates. We suggest that global PyC production could be in the range of 116–385 Tg C yr 1 , that is ~0.2–0.6% of the annual terrestrial net primary production. According to our estimations, atmospheric emissions of soot/black C might be a smaller fraction of total PyC (<2%) than previously reported. Research on the fate of PyC in the environment has mainly focused on its degradation pathways, and its accumulation and resilience either in situ (surface soils) or in ultimate sinks (marine sediments). Off-site transport, transformation and PyC storage in intermediate pools are often overlooked, which could explain the fate of a substantial fraction of the PyC mobilized annually. We propose new research directions addressing gaps in the global PyC cycle to fully understand the importance of the products of burning in global C cycle dynamics.
TL;DR: In this article, the authors examined the temporal and latitudinal distribution of volcanic SO 2 emissions and reassess the relationship between eruptive SO 2 discharge and eruption magnitude, finding a first-order correlation between SO 2 emission and volcanic explosivity index (VEI), but with significant scatter.
13 Apr 2016
TL;DR: In this article, an atomic level understanding of the stability of phosphorene in terms of its interaction with O2 and H2O was provided based on density functional theory together with first principles molecular dynamics calculations.
Abstract: Phosphorene is a promising two-dimensional (2D) material with a direct band gap, high carrier mobility, and anisotropic electronic properties. Phosphorene-based electronic devices, however, are found to degrade upon exposure to air. In this paper, we provide an atomic level understanding of the stability of phosphorene in terms of its interaction with O2 and H2O. The results based on density functional theory together with first principles molecular dynamics calculations show that O2 could the spontaneously dissociate on phosphorene at room temperature. H2O will not strongly interact with pristine phosphorene, however, an exothermic reaction could occur if phosphorene is first oxidized. The pathway of oxidation first, followed by exothermic reaction with water is the most likely route for the chemical degradation of phosphorene-based devices in air.
TL;DR: In this article, the authors outline the evolution of additive manufacturing technology, culminating in 3D printing and present a vision of how this evolution is affecting existing global value chains (GVCs) in production.
Abstract: This article outlines the evolution of additive manufacturing technology, culminating in 3D printing and presents a vision of how this evolution is affecting existing global value chains (GVCs) in production. In particular, we bring up questions about how this new technology can affect the geographic span and density of GVCs. Potentially, wider adoption of this technology has the potential to partially reverse the trend towards global specialization of production systems into elements that may be geographically dispersed and closer to the end users (localization). This leaves the question of whether in some industries diffusion of 3D printing technologies may change the role of multinational enterprises as coordinators of GVCs by inducing the engagement of a wider variety of firms, even households.
TL;DR: In this article, an efficient visible-light photocatalytic CO2 reforming of methane (CRM) was reported by combining Pt/black TiO2 catalyst with light-diffuse-reflection surface.
Abstract: The large energy requirement of CO2 reforming of methane (CRM) has obstructed its application. Solar energy is a solution for the issue. Different from efficient photocatalytic splitting of water, photocatalysis for CRM exhibits a very low efficiency and employs only ultraviolet (UV) light. This letter reports an efficient visible-light photocatalytic CRM by combining Pt/black TiO2 catalyst with light-diffuse-reflection-surface. Under visible light illumination by filtering UV light from AM 1.5G sunlight, H2 and CO yields reached 71 and 158 mmol/h/gcat, with a quantum efficiency of 32.3% at 550 °C, and 129 and 370 mmol/h/gcat, with a quantum efficiency of 57.8% at 650 °C. Those yields are 3 orders of magnitude larger than the reported values.
TL;DR: A new method to test hadronic interaction models without relying on the absolute energy calibration is introduced, and it is applied to events with primary energy 6-16 EeV (E_{CM}=110-170 TeV), whose longitudinal development and lateral distribution were simultaneously measured by the Pierre Auger Observatory.
Abstract: Ultrahigh energy cosmic ray air showers probe particle physics at energies beyond the reach of accelerators Here we introduce a new method to test hadronic interaction models without relying on the absolute energy calibration, and apply it to events with primary energy 6-16 EeV (E_CM = 110-170 TeV), whose longitudinal development and lateral distribution were simultaneously measured by the Pierre Auger Observatory The average hadronic shower is 133 +- 016 (161 +- 021) times larger than predicted using the leading LHC-tuned models EPOS-LHC (QGSJetII-04), with a corresponding excess of muons
University of Alaska Fairbanks1, Northern Arizona University2, University of Vermont3, University of Virginia4, University of Alberta5, United States Department of Agriculture6, United States Geological Survey7, Woods Hole Oceanographic Institution8, University of Notre Dame9, University of Guelph10, VU University Amsterdam11, Mississippi State University12, University of North Texas13, Florida State University14, Université du Québec15, Swedish University of Agricultural Sciences16, McGill University17, United States Department of Energy18, University of Cincinnati19, Xiamen University20, École Normale Supérieure21, McMaster University22, University of Toronto23, Lakehead University24, Aarhus University25, University of Maryland Center for Environmental Science26, Natural Resources Canada27, University of Washington28, Umeå University29, Wilkes University30, University of Minnesota31, Michigan Technological University32, Max Planck Society33, University System of Maryland34, Queen's University35, University of Wisconsin–Milwaukee36, University of Montana System37, University of Illinois at Chicago38, Stockholm University39, University of Colorado Boulder40, University of Saskatchewan41, Alfred Wegener Institute for Polar and Marine Research42, Institut national de la recherche agronomique43, University of Michigan44, Finnish Environment Institute45, University of Eastern Finland46, Fisheries and Oceans Canada47, Northumbria University48, University of Texas at Austin49, University of Gothenburg50, Laval University51, Northwest A&F University52, Tomsk State University53, Marine Biological Laboratory54, Yale University55, Imperial College London56, Duke University57, University of Copenhagen58, University of Alabama59, Centre national de la recherche scientifique60, Uppsala University61, University of Alaska Anchorage62, Russian Academy of Sciences63
TL;DR: As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export as mentioned in this paper, and models predict that some portion of this release w...
Abstract: As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release w ...
TL;DR: In this article, the authors comprehensively review the recent research efforts of exploring MoS2 as a co-catalyst for photocatalytic hydrogen production from water, with emphasis on its combination with CdS, CdSe, graphene, carbon nitride, TiO2, and others.
Abstract: Solar-to-hydrogen conversion based on photocatalytic water splitting is a promising pathway for sustainable hydrogen production. The photocatalytic process requires highly active, inexpensive, and earth-abundant materials as photocatalysts. As a presentative layer-structured transition metal dichalcogenides, molybdenum disulfide (MoS2) is attracting intensive attention due to its unique electro and photo properties. In this article, we comprehensively review the recent research efforts of exploring MoS2 as a co-catalyst for photocatalytic hydrogen production from water, with emphasis on its combination with CdS, CdSe, graphene, carbon nitride, TiO2, and others. It is shown that MoS2–semiconductor composites are promising photocatalysts for hydrogen evolution from water under visible light irradiation.
TL;DR: In this study, for the first time an effective method based on seeded growth and chemical etching is reported for the facile synthesis of Ru nanoframes with high purity.
Abstract: Noble-metal nanoframes are of great interest to many applications due to their unique open structures. Among various noble metals, Ru has never been made into nanoframes. In this study, we report for the first time an effective method based on seeded growth and chemical etching for the facile synthesis of Ru nanoframes with high purity. The essence of this approach is to induce the preferential growth of Ru on the corners and edges of Pd truncated octahedra as the seeds by kinetic control. The resultant Pd–Ru core–frame octahedra could be easily converted to Ru octahedral nanoframes of ∼2 nm in thickness by selectively removing the Pd cores through chemical etching. Most importantly, in this approach the face-centered cubic (fcc) crystal structure of Pd seeds was faithfully replicated by Ru that usually takes an hcp structure. The fcc Ru nanoframes showed higher catalytic activities toward the reduction of p-nitrophenol by NaBH4 and the dehydrogenation of ammonia borane compared with hcp Ru nanowires with...
TL;DR: The evidence-policy gap as mentioned in this paper, which is the gap between the evidence and policy, was identified as a major barrier for policy makers to understand and solve complex, multilevel policy-making environments.
Abstract: Policy makers cannot consider all evidence relevant to policy. They use two shortcuts-emotions and beliefs to understand problems and "rational" ways of establishing the best evidence on solutions-to act quickly in complex, multilevel policy-making environments. Many studies only address one part of this problem. Improving the supply of evidence helps reduce scientific and policy maker uncertainty. However, policy makers also combine their beliefs with limited evidence to reduce ambiguity by choosing one of several possible ways to understand and solve a problem. We use this insight to consider solutions designed to "close the evidence-policy gap".
Oregon State University1, University of Sydney2, Deakin University3, Zoological Society of London4, Wildlife Conservation Society5, University of Pretoria6, Panthera Corporation7, Ohio State University8, University of Nottingham Malaysia Campus9, Xishuangbanna Tropical Botanical Garden10, University of Victoria11, University of Oxford12, Stanford University13, International Union for Conservation of Nature and Natural Resources14, University of California, Santa Cruz15, Nelson Mandela Metropolitan University16, Sao Paulo State University17, Bangor University18, University of KwaZulu-Natal19, University of New South Wales20, University of Stirling21, World Wide Fund for Nature22, Princeton University23, University of Sussex24, Duke University25, University of Wisconsin-Madison26, University of California, Los Angeles27, Michigan Technological University28, University of Washington29, University of Technology, Sydney30, University of California, Santa Barbara31, Beijing Normal University32
TL;DR: Here, the objectives are to raise awareness of how these megafauna are imperiled and to stimulate broad interest in developing specific recommendations and concerted action to conserve them.
Abstract: From the late Pleistocene to the Holocene, and now the so called Anthropocene, humans have been driving an ongoing series of species declines and extinctions (Dirzo et al. 2014). Large-bodied mammals are typically at a higher risk of extinction than smaller ones (Cardillo et al. 2005). However, in some circumstances terrestrial megafauna populations have been able to recover some of their lost numbers due to strong conservation and political commitment, and human cultural changes (Chapron et al. 2014). Indeed many would be in considerably worse predicaments in the absence of conservation action (Hoffmann et al. 2015). Nevertheless, most mammalian megafauna face dramatic range contractions and population declines. In fact, 59% of the world’s largest carnivores (≥ 15 kg, n = 27) and 60% of the world’s largest herbivores (≥ 100 kg, n = 74) are classified as threatened with extinction on the International Union for the Conservation of Nature (IUCN) Red List (supplemental table S1 and S2). This situation is particularly dire in sub-Saharan Africa and Southeast Asia, home to the greatest diversity of extant megafauna (figure 1). Species at risk of extinction include some of the world’s most iconic animals—such as gorillas, rhinos, and big cats (figure 2 top row)—and, unfortunately, they are vanishing just as science is discovering their essential ecological roles (Estes et al. 2011). Here, our objectives are to raise awareness of how these megafauna are imperiled (species in supplemental table S1 and S2) and to stimulate broad interest in developing specific recommendations and concerted action to conserve them.
TL;DR: In this article, the authors present 238U-230Th age, trace element, and Hf isotopic data from individual zircon crystals from four eruptions from the Okataina Volcanic Center, Taupo Volcanics Zone, New Zealand, in order to assess changes in trace element and isotopic composition of the reservoir following the 45-ka caldera-forming Rotoiti eruption.
Abstract: Large silicic volcanic centers produce both small rhyolitic eruptions and catastrophic caldera-forming eruptions. Although changes in trace element and isotopic compositions within eruptions following caldera collapse have been observed at rhyolitic volcanic centers such as Yellowstone and Long Valley, much still remains unknown about the ways in which magma reservoirs are affected by caldera collapse. We present 238U–230Th age, trace element, and Hf isotopic data from individual zircon crystals from four eruptions from the Okataina Volcanic Center, Taupo Volcanic Zone, New Zealand, in order to assess changes in trace element and isotopic composition of the reservoir following the 45-ka caldera-forming Rotoiti eruption. Our data indicate that (1) mixing of magmas derived from crustal melts and mantle melts takes place within the shallow reservoir; (2) while the basic processes of melt generation likely did not change significantly between pre- and post-caldera rhyolites, post-caldera zircons show increased trace element and isotopic heterogeneity that suggests a decrease in the degree of interconnectedness of the liquid within the reservoir following collapse; and (3) post-caldera eruptions from different vents indicate different storage times of the amalgamated melt prior to eruption. These data further suggest that the timescales needed to generate large volumes of eruptible melt may depend on the timescales needed to increase interconnectedness and achieve widespread homogenization throughout the reservoir.
TL;DR: The role of tunnel cations in governing the electrochemical properties of electrode materials is reported by focusing on potassium ions in α-MnO2, and the presence of cations inside 2 × 2 tunnels of manganese dioxide increases the electronic conductivity, and improves lithium ion diffusivity.
Abstract: Metal oxides with a tunnelled structure are attractive as charge storage materials for rechargeable batteries and supercapacitors, since the tunnels enable fast reversible insertion/extraction of charge carriers (for example, lithium ions). Common synthesis methods can introduce large cations such as potassium, barium and ammonium ions into the tunnels, but how these cations affect charge storage performance is not fully understood. Here, we report the role of tunnel cations in governing the electrochemical properties of electrode materials by focusing on potassium ions in α-MnO2. We show that the presence of cations inside 2 × 2 tunnels of manganese dioxide increases the electronic conductivity, and improves lithium ion diffusivity. In addition, transmission electron microscopy analysis indicates that the tunnels remain intact whether cations are present in the tunnels or not. Our systematic study shows that cation addition to α-MnO2 has a strong beneficial effect on the electrochemical performance of this material.
National Institute for Mathematical and Biological Synthesis1, University of Mississippi2, Northern Arizona University3, Algoma University4, DePaul University5, Michigan Technological University6, University of Kansas7, Montana State University8, University of Oregon9, University of South Florida10, New Mexico State University11, University of Alberta12
TL;DR: The potential to detect local adaptation for mycorrhizal relationships across a broad swath of the literature is underscored, suggesting that local adaptation represents a powerful factor for the establishment of novel combinations of fungi, plants, and soils.
Abstract: Local adaptation, the differential success of genotypes in their native versus foreign environment, arises from various evolutionary processes, but the importance of concurrent abiotic and biotic factors as drivers of local adaptation has only recently been investigated. Local adaptation to biotic interactions may be particularly important for plants, as they associate with microbial symbionts that can significantly affect their fitness and may enable rapid evolution. The arbuscular mycorrhizal (AM) symbiosis is ideal for investigations of local adaptation because it is globally widespread among most plant taxa and can significantly affect plant growth and fitness. Using meta-analysis on 1170 studies (from 139 papers), we investigated the potential for local adaptation to shape plant growth responses to arbuscular mycorrhizal inoculation. The magnitude and direction for mean effect size of mycorrhizal inoculation on host biomass depended on the geographic origin of the soil and symbiotic partners. Sympatric combinations of plants, AM fungi, and soil yielded large increases in host biomass compared to when all three components were allopatric. The origin of either the fungi or the plant relative to the soil was important for explaining the effect of AM inoculation on plant biomass. If plant and soil were sympatric but allopatric to the fungus, the positive effect of AM inoculation was much greater than when all three components were allopatric, suggesting potential local adaptation of the plant to the soil; however, if fungus and soil were sympatric (but allopatric to the plant) the effect of AM inoculation was indistinct from that of any allopatric combinations, indicating maladaptation of the fungus to the soil. This study underscores the potential to detect local adaptation for mycorrhizal relationships across a broad swath of the literature. Geographic origin of plants relative to the origin of AM fungal communities and soil is important for describing the effect of mycorrhizal inoculation on plant biomass, suggesting that local adaptation represents a powerful factor for the establishment of novel combinations of fungi, plants, and soils. These results highlight the need for subsequent investigations of local adaptation in the mycorrhizal symbiosis and emphasize the importance of routinely considering the origin of plant, soil, and fungal components.
TL;DR: In this article, the authors present an agent-based modeling software development kit, and the implementation and validation of a model using it that integrates dynamic simulation of travel demand, network supply and network operations.
Abstract: This paper discusses the development of an agent-based modeling software development kit, and the implementation and validation of a model using it that integrates dynamic simulation of travel demand, network supply and network operations. A description is given of the core utilities in the kit: a parallel discrete event engine, interprocess exchange engine, and memory allocator, as well as a number of ancillary utilities: visualization library, database IO library, and scenario manager. The overall framework emphasizes the design goals of: generality, code agility, and high performance. This framework allows the modeling of several aspects of transportation system that are typically done with separate stand-alone software applications, in a high-performance and extensible manner. The issue of integrating such models as dynamic traffic assignment and disaggregate demand models has been a long standing issue for transportation modelers. The integrated approach shows a possible way to resolve this difficulty. The simulation model built from the POLARIS framework is a single, shared-memory process for handling all aspects of the integrated urban simulation. The resulting gains in computational efficiency and performance allow planning models to be extended to include previously separate aspects of the urban system, enhancing the utility of such models from the planning perspective. Initial tests with case studies involving traffic management center impacts on various network events such as accidents show the potential of the system.
TL;DR: In this paper, the effect of GO on the hydration of cement was evaluated by XRD and FTIR, and it was found that GO can remarkably accelerate hydration rate of cement due to its catalytic behavior.
TL;DR: In this paper, a joint solution for localization and time synchronization is proposed, in which the stratification effect of underwater medium is considered, so that the bias in the range estimates caused by assuming sound waves travel in straight lines in water environments is compensated.
Abstract: Time synchronization and localization are basic services in a sensor network system. Although they often depend on each other, they are usually tackled independently. In this work, we investigate the time synchronization and localization problems in underwater sensor networks, where more challenges are introduced because of the unique characteristics of the water environment. These challenges include long propagation delay and transmission delay, low bandwidth, energy constraint, mobility, etc. We propose a joint solution for localization and time synchronization, in which the stratification effect of underwater medium is considered, so that the bias in the range estimates caused by assuming sound waves travel in straight lines in water environments is compensated. By combining time synchronization and localization, the accuracy of both are improved jointly. Additionally, an advanced tracking algorithm interactive multiple model (IMM) is adopted to improve the accuracy of localization in the mobile case. Furthermore, by combining both services, the number of required exchanged messages is significantly reduced, which saves on energy consumption. Simulation results show that both services are improved and benefit from this scheme.
TL;DR: The adhesive demonstrated the capability to transition reversibly between its adhesive and nonadhesive states with changing pH and the formation of the catechol–boronate complex increased the cross-linking density of the adhesive network.
Abstract: A smart adhesive capable of binding to a wetted surface was prepared by copolymerizing dopamine methacrylamide (DMA) and 3-acrylamido phenylboronic acid (AAPBA). pH was used to control the oxidation state and the adhesive property of the catechol side chain of DMA and to trigger the catechol–boronate complexation. FTIR spectroscopy confirmed the formation of the complex at pH 9, which was not present at pH 3. The formation of the catechol–boronate complex increased the cross-linking density of the adhesive network. Most notably, the loss modulus values of the adhesive were more than an order of magnitude higher for adhesive incubated at pH 9 when compared to those measured at pH 3. This drastic increase in the viscous dissipation property is attributed to the introduction of reversible complexation into the adhesive network. Based on the Johnson Kendall Roberts (JKR) contact mechanics test, adhesive containing both DMA and AAPBA demonstrated strong interfacial binding properties (work of adhesion (Wadh) =...
TL;DR: No evidence is found that grey wolf dietary diversity varies globally, although the results from southern Europe suggest that grey wolves may switch their diets away from domestic species if more wild ungulates are available, and the diversity of prey consumed by grey wolves shows that the species is capable of surviving dramatic anthropogenic upheaval.
Abstract: Grey wolves Canis lupus have been studied extensively, but there has been no detailed review of the species’ feeding ecology, despite growing debate about how to conserve wolf populations while limiting their impacts on wild or domestic ungulates. Here, we assess the extent to which the grey wolf diet varies among and within North America, Europe, and Asia.
We derived dietary data from searches of published literature. We grouped studies based on their bioregional location. We compared grey wolf diet among locations using non-metric multidimensional scaling and analysis of similarity. We assessed whether increased human impacts are associated with decreased grey wolf dietary diversity. Finally, using studies from southern Europe, we assessed whether the importance of wild ungulates in grey wolf diet has increased over time, coincident with a decline in domestic species in grey wolf diet over time.
We compiled dietary data from 177 studies incorporating 94607 scat and stomach samples. Grey wolf diet was dominated by large (240–650 kg) and medium-sized (23–130 kg) wild ungulates, but variation in the percentages of wild ungulates consumed, along with variation in the percentages of domestic and smaller prey species consumed, contributed to the dietary differences found among and within continents.
We found no evidence that grey wolf dietary diversity varies globally, although the results from southern Europe suggest that grey wolves may switch their diets away from domestic species if more wild ungulates are available.
The diversity of prey consumed by grey wolves shows that the species is capable of surviving dramatic anthropogenic upheaval. However, there is an urgent need to increase our understanding of grey wolf foraging ecology in human-dominated landscapes, in order to determine whether restoration of depleted prey populations, coupled with effective damage-prevention measures, will reduce human-wolf conflicts.
TL;DR: The results reveal that self-polarization due to grain orientation along the spontaneous polarization direction plays an important role in achieving large piezoelectric response in a domain motion-confined material.
Abstract: A rapid surge in the research on piezoelectric sensors is occurring with the arrival of the Internet of Things. Single-phase oxide piezoelectric materials with giant piezoelectric voltage coefficient (g, induced voltage under applied stress) and high Curie temperature (Tc) are crucial towards providing desired performance for sensing, especially under harsh environmental conditions. Here, we report a grain-oriented (with 95% texture) modified PbTiO3 ceramic that has a high Tc (364 °C) and an extremely large g33 (115 × 10-3 Vm N-1) in comparison with other known single-phase oxide materials. Our results reveal that self-polarization due to grain orientation along the spontaneous polarization direction plays an important role in achieving large piezoelectric response in a domain motion-confined material. The phase field simulations confirm that the large piezoelectric voltage coefficient g33 originates from maximized piezoelectric strain coefficient d33 and minimized dielectric permittivity ɛ33 in [001]-textured PbTiO3 ceramics where domain wall motions are absent.