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3,722 result(s) for "Smith, Robert B."
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The Yellowstone magmatic system from the mantle plume to the upper crust
The Yellowstone supervolcano is one of the largest active continental silicic volcanic fields in the world. An understanding of its properties is key to enhancing our knowledge of volcanic mechanisms and corresponding risk. Using a joint local and teleseismic earthquake P-wave seismic inversion, we revealed a basaltic lower-crustal magma body that provides a magmatic link between the Yellowstone mantle plume and the previously imaged upper-crustal magma reservoir. This lower-crustal magma body has a volume of 46,000 cubic kilometers, ∼4.5 times that of the upper-crustal magma reservoir, and contains a melt fraction of ∼2%. These estimates are critical to understanding the evolution of bimodal basaltic-rhyolitic volcanism, explaining the magnitude of CO2 discharge, and constraining dynamic models of the magmatic system for volcanic hazard assessment.
Integration of Riboflavin-Modified Carbon Fiber Mesh Electrode Systems in a 3D-Printed Catheter Hub
Background: Catheter line infection is a common complication within clinical environments, and there is a pressing need for technological options to aid in reducing the possibility of sepsis. The early identification of contamination could be pivotal in reducing cases and improving outcomes. Method: A sensing rationale based on a riboflavin-modified electrode system integrated within a modified 3D-printed catheter needle-free connector is proposed, which can monitor changes in pH brought about by bacterial contamination. Results: Riboflavin, vitamin B2, is a biocompatible chemical that possesses a redox-active flavin core that is pH dependent. The oxidation peak potential of the adsorbed riboflavin responds linearly to changes in pH with a near-Nernstian behavior of 63 mV/pH unit and is capable of accurately monitoring the pH of an authentic IV infusate. Conclusions: The proof of principle is demonstrated with an electrode-printed hub design offering a valuable foundation from which to explore bacterial interactions within the catheter lumen with the potential of providing an early warning of contamination.
An extraordinary episode of Yellowstone caldera uplift, 2004-2010, from GPS and InSAR observations
Geodetic measurements of Yellowstone ground deformation from 2006 to June 2010 reveal deceleration of the recent uplift of the Yellowstone caldera following an unprecedented period of uplift that began in 2004. In 2006–2008 uplift rates decreased from 7 to 5 cm/yr and 4 to 2 cm/yr in the northern and southwest caldera, respectively, and in 2009 rates further reduced to 2 cm/yr and 0.5 cm/yr in the same areas. Elastic‐dislocation modeling of the deformation data robustly indicates an expanding sill at ∼7–10 km depth near the top of a seismically imaged, crystallizing magma reservoir, with a 60% decrease in the volumetric expansion rate between 2006 and 2009. Reduction of hydrothermal‐volcanic recharge from beneath the northeast caldera and seismic moment release of the 2008 and 2010 large earthquake swarms are plausible mechanisms for decelerating the caldera uplift and may have influenced the change in recent caldera motion from uplift to subsidence.
Accelerated Uplift and Magmatic Intrusion of the Yellowstone Caldera, 2004 to 2006
The Yellowstone caldera began a rapid episode of ground uplift in mid-2004, revealed by Global Positioning System and interferometric synthetic aperture radar measurements, at rates up to 7 centimeters per year, which is over three times faster than previously observed inflation rates. Source modeling of the deformation data suggests an expanding volcanic sill of ~1200 square kilometers at a 10-kilometer depth beneath the caldera, coincident with the top of a seismically imaged crustal magma chamber. The modeled rate of source volume increase is 0.1 cubic kilometer per year, similar to the amount of magma intrusion required to supply the observed high heat flow of the caldera. This evidence suggests magma recharge as the main mechanism for the accelerated uplift, although pressurization of magmatic fluids cannot be ruled out.
Monitoring super-volcanoes: geophysical and geochemical signals at Yellowstone and other large caldera systems
Earth's largest calderas form as the ground collapses during immense volcanic eruptions, when hundreds to thousands of cubic kilometres of magma are explosively withdrawn from the Earth's crust over a period of days to weeks. Continuing long after such great eruptions, the resulting calderas often exhibit pronounced unrest, with frequent earthquakes, alternating uplift and subsidence of the ground, and considerable heat and mass flux. Because many active and extinct calderas show evidence for repetition of large eruptions, such systems demand detailed scientific study and monitoring. Two calderas in North America, Yellowstone (Wyoming) and Long Valley (California), are in areas of youthful tectonic complexity. Scientists strive to understand the signals generated when tectonic, volcanic and hydrothermal (hot ground water) processes intersect. One obstacle to accurate forecasting of large volcanic events is humanity's lack of familiarity with the signals leading up to the largest class of volcanic eruptions. Accordingly, it may be difficult to recognize the difference between smaller and larger eruptions. To prepare ourselves and society, scientists must scrutinize a spectrum of volcanic signals and assess the many factors contributing to unrest and toward diverse modes of eruption.
Three-dimensional inversion of large-scale EarthScope magnetotelluric data based on the integral equation method: Geoelectrical imaging of the Yellowstone conductive mantle plume
Interpretation of the EarthScope MT (magnetotelluric) data requires the development of a large‐scale inversion method which can address two common problems of 3D MT inversion: computational time and memory requirements. We have developed an efficient method of 3D MT inversion based on an IE (integral equation) formulation of the MT forward modeling problem and a receiver footprint approach, implemented as a massively parallel algorithm. This method is applied to the MT data collected in the western United States as a part of the EarthScope project. As a result, we present one of the first 3D geoelectrical images of the upper mantle beneath Yellowstone revealed by this large‐scale 3D inversion of the EarthScope MT data. These images show a highly conductive body associated with the tomographically imaged mantle plume‐like layer of hot material rising from the upper mantle toward the Yellowstone volcano. The conductive body identified in these images is west‐dipping in a similar way to a P‐wave low‐velocity body. Key Points A new large‐scale MT inversion method is created We discovered highly conductive plume in the mantle under Yellowstone The geoelectric anomaly is similar to seismic tomography image
Evaluating polyanthranilic acid as a polymeric template for the production of Prussian blue nanoclusters
The electropolymerization of anthranilic acid (2-aminobenzoic acid) has been shown to lead to the production of a redox polymer functionalized with carboxylate groups capable of complexing metal ions. The polymer was exploited as a means of capturing ferric ion from solution with the iron decorated polymer chains used as seeding points for the formation of Prussian blue (PB). Nanoclusters of PB were dispersed throughout the three-dimensional polymer matrix with deposition achieved through direct electrochemical means or via a dip process. The latter exploited the chemical combination of Fe(III) + Ferrocyanide to yield PB allowing its dispersal of the PB throughout the polymer film. The polymer film and its subsequent modification have been characterized by electron microscopy, X-ray analysis, Raman spectroscopy and electrochemical analysis. The stability toward peroxide has also been explored. Graphical Abstract
Dynamics and rapid migration of the energetic 2008-2009 Yellowstone Lake earthquake swarm
Yellowstone National Park experienced an unusual earthquake swarm in December–January, 2008–2009 that included rapid northward migration of the activity at 1 km per day and shallowing of the maximum focal depths from 12 to 2 km beneath northern Yellowstone Lake. The swarm consisted of 811 earthquakes, 0.5 < MW < 4.1, aligned on a N–S 12‐km‐long vertical plane of hypocenters. The largest earthquake of the swarm had a 50% tensile crack‐opening source determined by a full waveform inversion that we interpret as a magmatic expansion component. In addition, GPS data revealed E–W crustal extension coincident with the swarm. Modeling of GPS and seismic data is consistent with E–W opening of ∼10 cm on a N–S striking vertical dike. Our interpretation is that the swarm was induced by magmatic fluid migration or propagation of a poroelastic stress pulse along a pre‐existing fracture zone.
Microneedle array sensors based on carbon nanoparticle composites: interfacial chemistry and electroanalytical properties
Conductive microneedle patches consisting of carbon nanoparticles embedded in a polystyrene matrix have been prepared using micro-moulding techniques. The interfacial properties of the structures before and after electrochemical etching have been characterised using X-ray photoelectron spectroscopy and contact angle. Anodisation of the needles leads to a significant increase in oxygen functionality and is shown to dramatically improve the electroanalytical capabilities of the microneedle array. The detection of uric acid in horse blood was used as a model system through which to assess the performance of the system. The composite approach is shown to lead to viable carbon-based sensors and can offer a rapid prototype option for the development of tailored microneedle systems.
Anthranilic Acid: A Versatile Monomer for the Design of Functional Conducting Polymer Composites
Polyaniline has been utilized in various applications, yet its widespread adoption has often been impeded by challenges. Composite systems have been proposed as a means of mitigating some of these limitations, and anthranilic acid (2-aminobenzoic acid) has emerged as a possible moderator for use in co-polymer systems. It offers improved solubility and retention of electroactivity in neutral and alkaline media, and, significantly, it can also bestow chemical functionality through its carboxylic acid substituent, which can greatly ease post-polymer modification. The benefits of using anthranilic acid (as a homopolymer or copolymer) have been demonstrated in applications including corrosion protection, memory devices, photovoltaics, and biosensors. Moreover, this polymer has been used as a versatile framework for the sequestration of metal ions for water treatment, and, critically, these same mechanisms serve as a facile route for the production of catalytic metallic nanoparticles. However, the widespread adoption of polyanthranilic acid has been limited, and the aim of the present narrative review is to revisit the early promise of anthranilic acid and assess its potential future use within modern smart materials. A critical evaluation of its properties is presented, and its versatility as both a monomer and a polymer across a spectrum of applications is highlighted.