1,640 research outputs found

    Carbon Dioxide Reduction on Large Area Liquid Metal Gallium-indium Electrocatalysts

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    Carbon dioxide (CO2) is widely known as a greenhouse gas that contributes to global warming due to the burning of fossil fuels. The carbon dioxide reduction reaction (CO2RR) is widely studied to reutilize CO2 to useful products, including methane, ethane, and carbon monoxide. This project studies the use of liquid metal gallium-indium as an electrocatalyst to perform CO2 reduction to carbon monoxide (CO) or possibly solid carbon in various solutions. Gallium-indium is characterized and studied through its “wetting” properties and adhesion to substrate foil through the measurement of contact angles inside solution. These liquid metal adhesion qualities mirror the study of “hydrophobicity and hydrophilicity” of water. Through the use of mechanical polishing, gallium-indium interfaces with copper to demonstrate more favorable adhesion forces. In conditions without water present, gallium-indium reduces CO2 to CO at voltages less than -2.25 volts and performs comparably to other known CO2RR catalysts that are more expensive, such as gold. Although solid carbon CO2RR was not discovered, the high catalytic rates suggest its importance as a catalyst for CO production. With the introduction of water to the electrolyte, hydrogen evolution occurs as a competing reaction, limiting the rates of CO production

    Carbon Dioxide Reduction on Large Area Liquid Metal Gallium-indium Electrocatalysts

    Get PDF
    Carbon dioxide (CO2) is widely known as a greenhouse gas that contributes to global warming due to the burning of fossil fuels. The carbon dioxide reduction reaction (CO2RR) is widely studied to reutilize CO2 to useful products, including methane, ethane, and carbon monoxide. This project studies the use of liquid metal gallium-indium as an electrocatalyst to perform CO2 reduction to carbon monoxide (CO) or possibly solid carbon in various solutions. Gallium-indium is characterized and studied through its “wetting” properties and adhesion to substrate foil through the measurement of contact angles inside solution. These liquid metal adhesion qualities mirror the study of “hydrophobicity and hydrophilicity” of water. Through the use of mechanical polishing, gallium-indium interfaces with copper to demonstrate more favorable adhesion forces. In conditions without water present, gallium-indium reduces CO2 to CO at voltages less than -2.25 volts and performs comparably to other known CO2RR catalysts that are more expensive, such as gold. Although solid carbon CO2RR was not discovered, the high catalytic rates suggest its importance as a catalyst for CO production. With the introduction of water to the electrolyte, hydrogen evolution occurs as a competing reaction, limiting the rates of CO production

    Companions to peculiar red giants: HR 363 and HR 1105

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    Recent IUE observations of two Tc-deficient S-type peculiar red giants that are also spectroscopic binaries, HR 363 and HR 1105 are reported. A 675 min SWP exposure of HR 363 shows emission lines of O I 1304 and Si II 1812 and a trace of continuum. Compared to the M giants, the far UV flux may be relatively larger, indicating a possible contribution from a white dwarf companion, but no high temperature emission lines are seen to indicate that this is an interacting system where mass-transfer recently occurred. However, HR 1105 appears to have a highly variable UV companion. In 1982, no UV flux was discerned for this system, but by 1986 C IV was strong, increasing by a factor of 3 in 1987 with prominent lines of Si III, C III, O III, Si IV, and N V. Using orbital parameters, these observations are consistent with high activity occuring when the side of the S-star primary illuminated by the companion faces the Earth, but since the IUE data were taken over 3 orbits, a secular change in the UV component cannot be excluded

    Combating Antibiotic Resistance Through the Health Impact Fund

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    The Health Impact Fund (Hollis & Pogge 2008) is an innovative financing mechanism for global drug discovery and dissemination, separating the reward for successful R&D from the market price of the drug, also known as de-linkage. Aaron Kesselheim and Kevin Outterson have recently proposed a mechanism to reimburse companies for antibiotics according to their social value, but conditioned on achieving conservation goals to limit resistance (Kesselheim & Outterson 2010, 2011). This paper will explore whether this antibiotic resistance conservation proposal can be adapted to the framework of the Health Impact Fund. If these proposals can be meshed, then antibiotics might be an interesting therapeutic class for a test of the Health Impact Fund

    Producing Feeder Pigs in Texas.

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    The M-type stars

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    The papers in this volume cover the following topics: (1) basic properties and photometric variability of M and related stars; (2) spectroscopy and nonthermal processes; (3) circumstellar radio molecular lines; (4) circumstellar shells, the formation of grains, and radiation transfer; (5) mass loss; (6) circumstellar chemistry; (7) thermal atmospheric models; (8) quasi-thermal models; (9) observations on the atmospheres of M dwarfs; and (1) theoretical work on M dwarfs

    Structural and Mutational Analysis of Escherichia coli AlkB Provides Insight into Substrate Specificity and DNA Damage Searching

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    Background: In Escherichia coli, cytotoxic DNA methyl lesions on the N1 position of purines and N3 position of pyrimidines are primarily repaired by the 2-oxoglutarate (2-OG) iron(II) dependent dioxygenase, AlkB. AlkB repairs 1-methyladenine (1meA) and 3-methylcytosine (3-meC) lesions, but it also repairs 1-methylguanine (1-meG) and 3-methylthymine (3-meT) at a much less efficient rate. How the AlkB enzyme is able to locate and identify methylated bases in ssDNA has remained an open question. Methodology/Principal Findings: We determined the crystal structures of the E. coli AlkB protein holoenzyme and the AlkBssDNA complex containing a 1-meG lesion. We coupled this to site-directed mutagenesis of amino acids in and around the active site, and tested the effects of these mutations on the ability of the protein to bind both damaged and undamaged DNA, as well as catalyze repair of a methylated substrate. Conclusions/Significance: A comparison of our substrate-bound AlkB-ssDNA complex with our unliganded holoenzyme reveals conformational changes of residues within the active site that are important for binding damaged bases. Sitedirected mutagenesis of these residues reveals novel insight into their roles in DNA damage recognition and repair. Our data support a model that the AlkB protein utilizes at least two distinct conformations in searching and binding methylated bases within DNA: a ‘‘searching’ ’ mode and ‘‘repair’ ’ mode. Moreover, we are able to functionally separate these mode

    Instantaneous Capture and Mineralization of Flue Gas Carbon Dioxide: Pilot Scale Study

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    Multiple CO2 capture and storage (CCS) processes are required to address anthropogenic CO2 problems. However, a method which can directly capture and mineralize CO2 at a point source, under actual field conditions, has advantages and could help offset the cost associated with the conventional CCS technologies. The mineral carbonation (MC), a process of converting CO2 into stable minerals (mineralization), has been studied extensively to store CO2. However, most of the MC studies have been largely investigated at laboratory scale. Objectives of this research were to develop a pilot scale AMC (accelerated mineral carbonation) process and test the effects of flue gas moisture content on carbonation of fly ash particles. A pilot scale AMC process consisting of a moisture reducing drum (MRD), a heater/humidifier, and a fluidized-bed reactor (FBR) was developed and tested by reacting flue gas with fly ash particles at one of the largest coal-fired power plants (2120 MW) in the USA. The experiments were conducted over a period of 2 hr at ~ 300 SCFM flow-rates, at a controlled pressure (115.1 kPa), and under different flue gas moisture contents (2-16%). The flue gas CO2 and SO2 concentrations were monitored before and during the experiments by an industrial grade gas analyzer. Fly ash samples were collected from the reactor sample port from 0-120 minutes and analyzed for total inorganic carbon (C), sulfur (S), and mercury (Hg). From C, S, and Hg concentrations, %calcium carbonate (CaCO3), %sulfate (SO42-), and %mercury carbonate (HgCO3) were calculated, respectively. Results suggested significant mineralization of flue gas CO2, SO2, and Hg within 10-15 minutes of reaction. Among different moisture conditions, ~16% showed highest conversion of flue gas CO2 and SO2 to %CaCO3 and %SO42- in fly ash samples. For example, an increase of almost 4% in CaCO3 content of fly ash was observed. Overall, the AMC process is cost-effective with minimum carbon footprint and can be retrofitted to coal fired power plants (existing and/or new) as a post-combustion unit to minimize flue gas CO2, SO2, and Hg emissions into the atmosphere. Used in conjunction with capture and geologic sequestration, the AMC process has the potential to reduce overall cost associated with CO2 separation/compression/transportation/pore space/brine water treatment. It could also help protect sensitive amines and carbon filters used in flue gas CO2 capture and separation process and extend their life

    Lichenizing Pedagogy: Art Explorations in More-than-Human Performance and Practice

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    This project of performative writing and visual inquiry proposes the concept of “lichenizing” as a collaborative methodology for engaging with the lively pedagogy of the more-than-human. Looking to the multispecies mosaic of Lichen as teacher and ally, this arts-based, collectively produced foray considers transcorporeal, intermingled relationships as a pedagogical tool for fostering a radical, ecologically-centered curiosity for learning and making. To support our theorizing, we present two collaborative art projects where tenets of lichenizing were utilized to instruct process and form, and suggest further exploration and research on the practice of “lichenizing.

    Synchronization of Developmental Processes and Defense Signaling by Growth Regulating Transcription Factors

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    Growth regulating factors (GRFs) are a conserved class of transcription factor in seed plants. GRFs are involved in various aspects of tissue differentiation and organ development. The implication of GRFs in biotic stress response has also been recently reported, suggesting a role of these transcription factors in coordinating the interaction between developmental processes and defense dynamics. However, the molecular mechanisms by which GRFs mediate the overlaps between defense signaling and developmental pathways are elusive. Here, we report large scale identification of putative target candidates of Arabidopsis GRF1 and GRF3 by comparing mRNA profiles of the grf1/grf2/grf3 triple mutant and those of the transgenic plants overexpressing miR396-resistant version of GRF1 or GRF3. We identified 1,098 and 600 genes as putative targets of GRF1 and GRF3, respectively. Functional classification of the potential target candidates revealed that GRF1 and GRF3 contribute to the regulation of various biological processes associated with defense response and disease resistance. GRF1 and GRF3 participate specifically in the regulation of defense-related transcription factors, cell-wall modifications, cytokinin biosynthesis and signaling, and secondary metabolites accumulation. GRF1 and GRF3 seem to fine-tune the crosstalk between miRNA signaling networks by regulating the expression of several miRNA target genes. In addition, our data suggest that GRF1 and GRF3 may function as negative regulators of gene expression through their association with other transcription factors. Collectively, our data provide new insights into how GRF1 and GRF3 might coordinate the interactions between defense signaling and plant growth and developmental pathways
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