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DOE OSTI2012

Nitrogen-sensitized dual phase titanate/titania for visible-light driven phenol degradation

A dual-phase material (DP-160) comprising hydrated titanate (H{sub 2}Ti{sub 3}O{sub 7}{center_dot}xH{sub 2}O) and anatase (TiO{sub 2}) was synthesized in a low-temperature one-pot process in the presence of triethylamine (TEA) as the N-source. The unique structure exhibits strong visible light absorption. The chromophore is linked to Ti-N bonds derived from both surface sensitization and sub-surface (bulk) doping. From transmission electron microscope (TEM) and textural studies by N{sub 2} physisorption, the composite exists as mesoporous particles with a grain size of {approx}20 nm and mean pore diameter of 3.5 nm, responsible for the high surface area ({approx}180 m{sup 2}/g). DP-160 demonstrated photocatalytic activity in the degradation of phenol under visible light ({lambda}>420 nm). The activity of the composite was further enhanced by a small addition (0.001 M) of H{sub 2}O{sub 2}, which also gave rise to some visible light activity in the control samples. This effect is believed to be associated with the surface peroxo-titanate complex. GC-MS analyses showed that the intermediate products of phenol degradation induced by visible light irradiation of DP-160 did not differ from those obtained by UV (band-gap) irradiation of TiO{sub 2}. The overall performance of the composite is attributed to efficient excitation via inter-band states (due to N-doping), surface sensitization, improved adsorptive properties of aromatic compounds due to the N-carbonaceous overlayer, and the presence of heterojunctions that are known to promote directional charge transfer in other mixed-phase titanias like Degussa P25. - graphical abstract: Nitrogen-sensitized dual phase titanate/titania photocatalyst showing extended visible light absorption and efficient photocatalytic degradation of phenol. Highlights: Black-Right-Pointing-Pointer Low temperature one-pot synthesis of visible light active dual phase photocatalyst. Black-Right-Pointing-Pointer The dual phase consists of nanoscale titanate and anatase titania phases. Black-Right-Pointing-Pointer The photocatalyst displays high activity in degrading phenol under visible light. Black-Right-Pointing-Pointer Mechanisms for the sensitization to visible light are considered.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

ON THE ACTIVE REGION BRIGHT GRAINS OBSERVED IN THE TRANSITION REGION IMAGING CHANNELS OF IRIS

The Interface Region Imaging Spectrograph (IRIS) provides spectroscopy and narrow band slit-jaw (SJI) imaging of the solar chromosphere and transition region at unprecedented spatial and temporal resolutions. Combined with high-resolution context spectral imaging of the photosphere and chromosphere as provided by the Swedish 1 m Solar Telescope (SST), we can now effectively trace dynamic phenomena through large parts of the solar atmosphere in both space and time. IRIS SJI 1400 images from active regions, which primarily sample the transition region with the Si iv 1394 and 1403 Å lines, reveal ubiquitous bright “grains” which are short-lived (two to five minute) bright roundish small patches of sizes 0.″5–1.″7 that generally move limbward with velocities up to about 30 km s{sup −1}. In this paper, we show that many bright grains are the result of chromospheric shocks impacting the transition region. These shocks are associated with dynamic fibrils (DFs), most commonly observed in Hα. We find that the grains show the strongest emission in the ascending phase of the DF, that the emission is strongest toward the top of the DF, and that the grains correspond to a blueshift and broadening of the Si iv lines. We note that the SJI 1400 grains can also be observed in the SJI 1330 channel which is dominated by C ii lines. Our observations show that a significant part of the active region transition region dynamics is driven from the chromosphere below rather than from coronal activity above. We conclude that the shocks that drive DFs also play an important role in the heating of the upper chromosphere and lower transition region.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2024

Active learning of ternary alloy structures and energies

Abstract Machine learning models with uncertainty quantification have recently emerged as attractive tools to accelerate the navigation of catalyst design spaces in a data-efficient manner. Here, we combine active learning with a dropout graph convolutional network (dGCN) as a surrogate model to explore the complex materials space of high-entropy alloys (HEAs). We train the dGCN on the formation energies of disordered binary alloy structures in the Pd-Pt-Sn ternary alloy system and improve predictions on ternary structures by performing reduced optimization of the formation free energy, the target property that determines HEA stability, over ensembles of ternary structures constructed based on two coordinate systems: (a) a physics-informed ternary composition space, and (b) data-driven coordinates discovered by the Diffusion Maps manifold learning scheme. Both reduced optimization techniques improve predictions of the formation free energy in the ternary alloy space with a significantly reduced number of DFT calculations compared to a high-fidelity model. The physics-based scheme converges to the target property in a manner akin to a depth-first strategy, whereas the data-driven scheme appears more akin to a breadth-first approach. Both sampling schemes, coupled with our acquisition function, successfully exploit a database of DFT-calculated binary alloy structures and energies, augmented with a relatively small number of ternary alloy calculations, to identify stable ternary HEA compositions and structures. This generalized framework can be extended to incorporate more complex bulk and surface structural motifs, and the results demonstrate that significant dimensionality reduction is possible in thermodynamic sampling problems when suitable active learning schemes are employed.

Chemistry↗

DOE OSTI2020

First observation of the production of three massive vector bosons and search for long-lived particles using delayed photons in pp collisions at $\sqrt{s}=13\text{ TeV}$

This thesis presents the first observation of the production of three massive vector bosons (VVV with V = W, Z) in proton-proton collisions at the LHC at $\sqrt{s}=13\text{ TeV}$. The search was performed in final states with two same-sign charged leptons (electrons or muons) plus one or two jets, and three, four, five, or six leptons from WWW, WWZ, WZZ and ZZZ decays, with a data sample corresponding to an integrated luminosity of 137 fb -1 collected by the CMS experiment during 2016-2018. The observed (expected) significance of the combined VVV production is 5.7 (5.9) standard deviations, and the production cross section is measured to be 1010$^{+210}_{-200}$(stat) $^{+150}_{-120}$(syst) fb, corresponding to a signal strength of 1.02$^{+0.26}_{-0.23}$. We also found evidence for WWW and for WWZ production, with observed significances of 3.3 and 3.4 standard deviations, respectively. The measured production cross sections for individual VVV processes are also reported. The establishment of VVV production opens a new program of many standard model studies (such as gauge-gauge and Higgs-gauge couplings), and provides a new tool for many new physics searches (such as anomalous gauge coupling searches, new resonance searches). This thesis also reports a search for long-lived supersymmetry particles decaying to photons in proton-proton collisions at the LHC at $\sqrt{s} = 13 TeV$, with a data sample corresponding to an integrated luminosity of 77.4 fb -1 collected by CMS during 2016-2017. Results are interpreted with a gauge-mediated supersymmetry breaking model, where the long-lived particle is a neutralino and the lightest supersymmetry particle is a gravitino. For neutralino proper decay lengths of 0.1, 1, 10, and 100 m, masses up to 320, 525, 360, and 215 GeV are excluded at 95% confidence level, respectively. This result extends the limits from previous searches by one order of magnitude for the neutralino proper decay length and up to 100 GeV more for the neutralino mass. Motivated by the need for precision timing measurements for long-lived particle searches, as well as for improvements in general object reconstruction performance, the timing performance of two types of sensors are studied in this thesis: one with a Cerium doped Lutetium Yttrium Orthosilicate (LYSO:Ce) crystal as the scintillator and a silicon photomultiplier (SiPM) as the photodetector, another with a Cadmium-Telluride sensor as the active material for a sampling calorimeter. Both setups have been demonstrated with test beams to be able to provide timing measurements of particles with a resolution below 30 ps.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2013

ENVIRONMENTAL EFFECTS IN THE INTERACTION AND MERGING OF GALAXIES IN zCOSMOS

We analyze the environments and galactic properties (morphologies and star formation histories) of a sample of 153 close kinematic pairs in the redshift range 0.2 < z < 1 identified in the zCOSMOS-bright 10 k spectroscopic sample of galaxies. Correcting for projection effects, the fraction of close kinematic pairs is three times higher in the top density quartile than in the lowest one. This translates to a three times higher merger rate because the merger timescales are shown, from mock catalogs based on the Millennium simulation, to be largely independent of environment once the same corrections for projection are applied. We then examine the morphologies and stellar populations of galaxies in the pairs, comparing them to control samples that are carefully matched in environment so as to remove as much of the well-known effects of environment on the properties of the parent population of galaxies as possible. Once the environment is properly taken into account in this way, we find that the early-late morphology mix is the same as for the parent population, but that the fraction of irregular galaxies is boosted by 50%-75%, with a disproportionate increase in the number of irregular-irregular pairs (factor of 4-8 times), due to the disturbance of disk galaxies. Future dry mergers, involving elliptical galaxies comprise less than 5% of all close kinematic pairs. In the closest pairs, there is a boost in the specific star formation rates of star-forming galaxies of a factor of 2-4, and there is also evidence for an increased incidence of post-starburst galaxies. Although significant for the galaxies involved, the 'excess' star formation associated with pairs represents only about 5% of the integrated star formation activity in the parent sample. Although most pair galaxies are in dense environments, the effects of interaction appear to be largest in the lower density environments. By preferentially bringing more pairs into the sample in lower density environments, this could dilute the dependence of pair fraction on environment and may introduce other biases into the observational study of mergers, especially those based on morphological criteria.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2025

Evaluation of Properties for Microsample Identification

A study was conducted to determine if individual particle characteristics could be used to identify particles of interest, sub-samples, from bulk post-detonation debris. Three archived post-detonation debris samples were used for this effort. Particles from these samples were identified as active (produced fission tracks), and inactive (did not produce fission tracks), as the first defining characteristic. Morphology was the secondary characteristic to select particles for further study, i.e. spherical/non-spherical. Once particles were identified and isolated, they were characterized by optical microscopy for size in µm, number of fission tracks, morphology, transmitted light color, and reflected light color. Particles were then analyzed by scanning electron microscopy for morphology, elemental content, and compound identification. Raman spectroscopy was attempted on five particles with indeterminate results due to environmental mixing (heterogeneity) during the events of particle formation. Once all non-destructive analyses were completed all particles were analyzed by thermal ionization mass spectrometry to determine isotopic atom percents of plutonium and uranium, and an estimate of atoms of plutonium and uranium in each particle. An estimate of the ratio of uranium to plutonium was also obtained (U/Pu). Data analytics of the data from the particles showed that combining characteristics of the particles have a high probability of identifying particles of interest from bulk post-detonation debris samples. Please note that this version of the report is an abridged version of the full report (Wagnon et al. 2025) that has been edited to be appropriate for public release.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

NASA NTRS1997

Enhancement of Cognitive Processing by Multiple Sclerosis Patients Using Liquid Cooling Technology: A Case Study

Recent neuropsychological studies demonstrate that cognitive dysfunction is a common symptom in patients with multiple sclerosis. In many cases the presence of cognitive impairment affects the patient's daily activities to a greater extent than would be found due to their physical disability alone. Cognitive dysfunction can have a significant impact on the quality of life of both the patient and that of their primary caregiver. Two cognitively impaired male MS patients were given a visual discrimination task before and after a one hour cooling period. The subjects were presented a series of either red or blue circles or triangles. One of these combinations, or one fourth of the stimuli, was designated as the "target" presentation. EEG was recorded from 20 scalp electrodes using a Tracor Northern 7500 EEG/ERP system. Oral and ear temperatures were obtained and recorded manually every five minutes during the one hour cooling period. The EEG ERP signatures from each series of stimuli were analyzed in the energy density domain to determine the locus of neural activity at each EEG sampling time. The first subject's ear temperature did not decrease during the cooling period. It was actually elevated approximately 0.05 C by the end of the cooling period compared to his mean of control period value. In turn, Subject One's discrimination performance and cortical energy remained essentially the same after body cooling. In contrast, Subject Two's ear temperature decreased approx. 0.8 C during his cooling period. Subject Two's ERROR score decreased from 12 during the precooling control period to 2 after cooling. His ENERGY value increased approximately 300%, from a precooling value of approximately 200 to a postcooling value of nearly 600. These findings might be interpreted by the following three-part hypothesis: (1) the general cognitive impairment of MS patients may be a result of low or unfocused metabolic energy conversion in the cortex; (2) such differences show up most strongly in reduced energy in the occipital region during the initial processing of the precooling period visual stimulus which may indicate impaired early visual processing; and (3) increased postcooling activation in the le ft angular gyrus may result in enhanced higher-level reasoning related to processing visual task information. By this hypothesis the superior performance of Subject Two following body cooling may be a result of increased neural activation in his early visual recognition and processing centers.

Montgomery, Leslie D.↗

DOE OSTI2022

Star formation and AGN feedback in the local Universe: Combining LOFAR and MaNGA

The effect of active galactic nuclei (AGN) on their host galaxies – in particular their levels of star formation – remains one of the key outstanding questions of galaxy evolution. Successful cosmological models of galaxy evolution require a fraction of energy released by an AGN to be redistributed into the interstellar medium to reproduce the observed stellar mass and luminosity function and to prevent the formation of over-massive galaxies. Observations have confirmed that the radio-AGN population is energetically capable of heating and redistributing gas at all phases, however, direct evidence of AGN enhancing or quenching star formation remains rare. With modern, deep radio surveys and large integral field spectroscopy (IFS) surveys, we can detect fainter synchrotron emission from AGN jets and accurately probe the star-forming properties of galaxies, respectively. Here, in this paper, we combine data from the LOw Frequency ARray Two-meter Sky Survey (LoTSS) with data from one of the largest optical IFS surveys, Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), to probe the star-forming properties of 307 local (z < 0.15) galaxies that host radio-detected AGN (RDAGN). We compare our results to a robust control sample of non-active galaxies that each match the stellar mass, redshift, visual morphology, and inclination of a RDAGN host. We find that RDAGN and control galaxies have broad star-formation rate (SFR) distributions, typically lie below the SFMS, and have negative stellar light-weighted age gradients. These results indicate that AGN selected based on their current activity are not responsible for suppressing their host galaxies’ star formation. Rather, our results support the maintenance mode role that radio AGN are expected to have in the local Universe.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2019

Fungi in the Canopy: How Soil Fungi and Extracellular Enzymes Differ Between Canopy and Ground Soils

Abstract Tropical montane cloud forests contain a large abundance and diversity of canopy epiphytes, which depend on canopy soil to retain water and nutrients. We lack an in depth understanding of how these soils contribute to ecosystem processes and soil diversity and how sensitive they may be to projected climate change. We compared canopy and ground soils in Monteverde, Costa Rica, to determine how these two soil types differ in their extracellular enzyme activity (EEA) and fungal communities. Samples were also collected along two elevation gradients to reveal if canopy soils differed in how EEA and fungal communities responded to elevation compared to ground soils. We found that canopy soils had higher EEA than ground soils. Fungal communities were less diverse and differed significantly between the two soil types. These differences were associated with higher relative abundances of yeasts and endophytes in canopy soils. The relative abundances of free-living filamentous fungi and yeasts shifted more dramatically with elevation in canopy soils compared to ground soils. Our study suggests that canopy soils may be a reservoir for endophytes. Epiphytes may invest in symbionts that promote stress tolerance over mycorrhizal fungi whose high resource demands are costly and less beneficial. Overall, soils harbor distinct fungal communities that may be altered under projected climate change.

Environmental Sciences & Ecology↗

DOE OSTI2011

Neutron Induced Beta Radiography

In the present paper we give a new methodology named, 'neutron induced beta radiography-NIBR' which makes use of neutron activated Dy or In foils as source of (3-radiation. Radiographs are obtained with an aluminium cassette containing image plate, a sample under inspection and the activated Dy or In foil kept in tight contact. The sensitivity of the technique to thickness was evaluated for different materials in the form of step wedges. Some radiographs are presented to demonstrate potential of method to inspect thin samples.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2014

Trends in ultracool dwarf magnetism. II. The inverse correlation between X-ray activity and rotation as evidence for a bimodal dynamo

Observations of magnetic activity indicators in solar-type stars exhibit a relationship with rotation with an increase until a 'saturation' level and a moderate decrease in activity in the very fastest rotators ('supersaturation'). While X-ray data have suggested that this relationship is strongly violated in ultracool dwarfs (UCDs; spectral type ≳M7), the limited number of X-ray detections has prevented firm conclusions. In this paper, we analyze the X-ray activity-rotation relation in 38 UCDs. Our sample represents the largest catalog of X-ray active UCDs to date, including seven new and four previously unpublished Chandra observations presented in a companion paper. We identify a substantial number of rapidly rotating UCDs with X-ray activity extending two orders of magnitude below the expected saturation level and measure a 'supersaturation'-type anticorrelation between rotation and X-ray activity. The scatter in UCD X-ray activity at a fixed rotation is ∼3 times larger than that in earlier-type stars. We discuss several mechanisms that have been proposed to explain the data, including centrifugal stripping of the corona, and find them to be inconsistent with the observed trends. Instead, we suggest that an additional parameter correlated with both X-ray activity and rotation is responsible for the observed effects. Building on the results of Zeeman-Doppler imaging of UCD magnetic fields and our companion study of radio/X-ray flux ratios, we argue that this parameter is the magnetic field topology, and that the large scatter in UCD X-ray fluxes reflects the presence of two dynamo modes that produce distinct topologies.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1994

Robotic servicing system for space material experiment

A containerless image furnace with an electrostatic positioning device has been developed as one of the material experiment facilities on the Japanese experimental module (JEM). It is characterized by heating/melting/cooling the sample whose position is kept without any contacts by actively controlled electrostatic force exerted between the sample and a set of electrodes. The experiment using the image furnace requires various servicing operations. We have been developing a robotic servicing system with an internal robot accommodated in the rack as an alternative to the crew. It aims to reduce the load on the crew by automating regular tasks and to increase the flexibility applicable to simple irregular tasks by introducing a remote teleoperation scheme. The present robot has poor capability to replace the crew. In order to compensate it, introducing of the concept of the robot friendliness and improving the controllability of the teleoperation by the ground operator aids are essential. In this paper, we identify the tasks to be performed by the robotic servicing system and discuss the way to compensate the capability of the robot. In addition we describe the evaluation tests using an experimental model.

Yamawaki, Toshihiko↗

DOE OSTI2013

LoCuSS: THE STEADY DECLINE AND SLOW QUENCHING OF STAR FORMATION IN CLUSTER GALAXIES OVER THE LAST FOUR BILLION YEARS

We present an analysis of the levels and evolution of star formation activity in a representative sample of 30 massive galaxy clusters at 0.15 < z < 0.30 from the Local Cluster Substructure Survey, combining wide-field Spitzer/MIPS 24 μm data with extensive spectroscopy of cluster members. The specific SFRs of massive (M > or approx. 10{sup 10} M{sub ☉}) star-forming cluster galaxies within r{sub 200} are found to be systematically ∼28% lower than their counterparts in the field at fixed stellar mass and redshift, a difference significant at the 8.7σ level. This is the unambiguous signature of star formation in most (and possibly all) massive star-forming galaxies being slowly quenched upon accretion into massive clusters, their star formation rates (SFRs) declining exponentially on quenching timescales in the range 0.7-2.0 Gyr. We measure the mid-infrared Butcher-Oemler effect over the redshift range 0.0-0.4, finding rapid evolution in the fraction (f{sub SF}) of massive (M{sub K} < – 23.1) cluster galaxies within r{sub 200} with SFRs > 3 M{sub ☉} yr{sup –1}, of the form f{sub SF}∝(1 + z){sup 7.6±1.1}. We dissect the origins of the Butcher-Oemler effect, revealing it to be due to the combination of a ∼3 × decline in the mean specific SFRs of star-forming cluster galaxies since z ∼ 0.3 with a ∼1.5 × decrease in number density. Two-thirds of this reduction in the specific SFRs of star-forming cluster galaxies is due to the steady cosmic decline in the specific SFRs among those field galaxies accreted into the clusters. The remaining one-third reflects an accelerated decline in the star formation activity of galaxies within clusters. The slow quenching of star formation in cluster galaxies is consistent with a gradual shut down of star formation in infalling spiral galaxies as they interact with the intracluster medium via ram-pressure stripping or starvation mechanisms. The observed sharp decline in star formation activity among cluster galaxies since z ∼ 0.4 likely reflects the increased susceptibility of low-redshift spiral galaxies to gas removal mechanisms as their gas surface densities decrease with time. We find no evidence for the build-up of cluster S0 bulges via major nuclear starburst episodes.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2019

A continuous fluorescence assay for simple quantification of bile salt hydrolase activity in the gut microbiome

The microbiota of the mammalian gut plays a dynamic role in controlling host physiology. The effect of gut microbiota activity on host health is particularly evident in the case of bile homeostasis. Bile is produced by the host and is modified by the gut microbiota, which impacts the net hydrophobicity of the total bile acid pool, and also modulates host signaling pathways. A key mechanism by which the microbiota modify bile is through de-conjugation of bile salts through bile salt hydrolase (BSH) enzymatic activity, which is postulated to be a prerequisite for all further microbial metabolism. BSH activity in the gut is largely considered to be beneficial, and genes encoding BSHs are found in the genomes of many taxa found in over-the-counter probiotics. Despite the therapeutic relevance of this enzyme, there is no reliable and simple assay for continuous monitoring of BSH activity, and there are no non-destructive means of characterizing its activity in whole cell or microbial community samples. Herein, we describe a continuous fluorescence assay that can be used for characterization of BSH activity with purified protein, cell lysates, whole cells, and in human gut microbiome samples. The method is a “turn-on” reporter strategy, which employs synthetic substrates that yield a fluorescent product upon BSH-dependent turnover. This assay is used to show the first in vivo characterization of BSH activity. Furthermore, we demonstrate the first example of continuous, non-destructive quantification of BSH activity in human gut microbiome samples.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2016

Results on the neutron energy distribution measurements at the RECH-1 Chilean nuclear reactor

Neutron activations experiments has been perform at the RECH-1 Chilean Nuclear Reactor to measure its neutron flux energy distribution. Samples of pure elements was activated to obtain the saturation activities for each reaction. Using - ray spectroscopy we identify and measure the activity of the reaction product nuclei, obtaining the saturation activities of 20 reactions. GEANT4 and MCNP was used to compute the self shielding factor to correct the cross section for each element. With the Expectation-Maximization algorithm (EM) we were able to unfold the neutron flux energy distribution at dry tube position, near the RECH-1 core. In this work, we present the unfolding results using the EM algorithm.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2018

Effect of Acid-Washing on the Nature of Bulk Characteristics of Nitrogen-Doped Carbon Nanostructures as Oxygen Reduction Reaction Electrocatalysts in Acidic Media

In this work, CN x catalysts were synthesized using Fe-doped MgO as a growth substrate. The oxygen reduction reaction (ORR) performance of the synthesized samples was evaluated in a half-cell. Acid-washing improved the ORR activity for the synthesized CN x samples. This is attributed to the removal of the exposed metal, which is likely to be blocking the active sites. Characterization experiments suggest that acid-washing totally eliminates the support material (MgO) and renders carbon more graphitic. This is likely to be due to elimination of amorphous or less crystalline species during washing. In addition, characterization experiments reveal significant differences in the metallic species that are exposed versus those encased in the carbon nanostructure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Use of Tracer Elements for Estimating Community Exposure to Marcellus Shale Development Operations

Since 2009, unconventional natural gas development (UNGD) has significantly increased in Appalachia’s Marcellus Shale formation. Elevations of fine particulate matter <2.5 µm (PM2.5), have been documented in areas surrounding drilling operations during well stimulation. Furthermore, many communities are experiencing increased industrial activities and probable UNGD air pollutant exposures. Recent studies have associated UNGD emissions with health effects based on distances from well pads. In this study, PM2.5 filter samples were collected on an active gas well pad in Morgantown, West Virginia, and three locations downwind during hydraulic stimulation. Fine particulate samples were analyzed for major and trace elements. An experimental source identification model was developed to determine which elements appeared to be traceable downwind of the UNGD site and whether these elements corresponded to PM2.5 measurements. Results suggest that 1) magnesium may be useful for detecting the reach of UNGD point source emissions, 2) complex surface topographic and meteorological conditions in the Marcellus Shale region could be modeled and confounding sources discounted, and 3) well pad emissions may be measurable at distances of at least 7 km. If shown to be more widely applicable, future tracer studies could enhance epidemiological studies showing health effects of UNGD-associated emissions at ≥15 km.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2013

Dispersion states and acid properties of SiO{sub 2}-supported Nb{sub 2}O{sub 5}

Nb{sub 2}O{sub 5}/SiO{sub 2} samples were prepared by the incipient-wetness impregnation method using niobium oxalate aqueous solution. The microstructure and dispersion process of the niobia species supported on SiO{sub 2} were characterized by means of power X-ray diffraction (XRD), laser Raman spectroscopy (LRS), and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The acid properties were investigated by the method of Hammett indicator and Pyridine adsorption infrared (Py-IR) spectroscopy. The results showed that the dispersion process of Nb{sub 2}O{sub 5} was performed by consuming surface hydroxyl groups of the amorphous SiO{sub 2} support. The aggregation of niobia species led to the formation of microcrystalline particles, so that there was no a clear monolayer dispersion capacity for Nb{sub 2}O{sub 5} supported on amorphous SiO{sub 2}. Furthermore, the catalytic activities of the as-prepared samples were evaluated by the condensation reaction of iso-butene (IB) and iso-butyraldehyde (IBA) to form 2,5-dimethyl-2,4-hexadiene (DMHD). The catalytic activities of the as-prepared samples for the condensation and their acid properties were strongly affected by the dispersion states. - Graphical abstract: The acid amount and strength of Nb{sub 2}O{sub 5}/SiO{sub 2} samples varied with the increase of Nb{sub 2}O{sub 5} loading. The catalytic activities of the as-prepared samples for the condensation and their acid properties were strongly affected by the dispersion states. - Highlights: • The dispersed process of Nb{sub 2}O{sub 5} was completed by consuming surface hydroxyl groups of SiO{sub 2}. • XRD quantitative phase analysis is not applicable for oxides dispersing on amorphous support. • The catalytic activity of Nb{sub 2}O{sub 5}/SiO{sub 2} is closely related to the dispersion state of SiO{sub 2}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗