26 research outputs found
GeoWorlds: Integrating GIS and digital libraries for situation understanding and management
No full textHelping organizations to marshal, analyze, discuss, and act on all of the available information about a situation playing out over space and time is a critical problem. GeoWorlds (http://www.isi.edu/geoworlds) is a component-based information management system that addresses this issue. It brings together information analysis, retrieval and collaboration tools and integrates digital library, geographic information systems (GIS), and remote sensor data management technologies. It provides three key services: 1) rapidly assembling a custom repository of geographic information about a region, 2) bi-directionally linking it to collections of document-based information from the World-Wide Web, and 3) monitoring real-time sensor data for information that might change conclusions or decisions formed on the basis of this rich information set. GeoWorlds framework enables synchronous and asynchronous collaboration over finding, filtering, organizing and visualizing the needed information
GeoWorlds: A Geographically Based Information System for Situation Understanding and Management
No full text
Integrating geographic information systems, spatial digital libraries and information spaces for conducting humanitarian assistance and disaster relief operations in urban environments
No full textThe GeoWorlds system integrates geographic information systems, spatial digital libraries and other information analysis, retrieval and collaboration tools. It supports multiple applications ranging from intelligence gathering to urban planning, to crisis management and response. Teams can rapidly assemble collections of document-based information from the World-Wide Web and other specialized information sources, visualize geo-spatial distribution of these collections and monitor events that might change conclusions or decisions formed on the basis of an initial information set. This functionality is provided within a framework that supports both synchronous and asynchronous collaboration over finding, filtering and organizing information and presenting it in a rich visualization environment
GeoWorlds: Integrating GIS and Digital Libraries for Situation Understanding and Management
No full textHelping organizations to marshal, analyze, discuss, and act on all of the available information about a situation playing out over space and time is a critical problem. GeoWorld
Solvent-Assisted Self-Assembly of Gold Nanorods into Hierarchically Organized Plasmonic Mesostructures
No full textPlasmonic supercrystals and periodically structured arrays comprise a class of materials with unique optical properties that result from the interplay of plasmon resonances, as well as near and far field coupling. Controlled synthesis of such hierarchical structures remains a fundamental challenge, as it demands strict control over the assembly morphology, array size, lateral spacing, and macroscale homogeneity. Current fabrication approaches involve complicated multi-step procedures lacking scalability and reproducibility, which has hindered the practical application of plasmonic supercrystal arrays. Herein, these challenges are addressed by adding an organic solvent to achieve kinetic control over the template-assisted colloidal assembly of nanoparticles from aqueous dispersion. This method yields highly regular periodic arrays, with feature sizes ranging from less than 200 nm up to tens of microns. A combined experimental/computational approach reveals that the underlying mechanism is a combination of the removal of interfacial surfactant micelles from the particle interface and altered capillary flows. Assessing the efficacy of such square arrays for surface-enhanced Raman scattering spectroscopy, we find that a decrease of the lattice periodicity from 750 nm down to 400 nm boosts the signal by more than an order of magnitude, thereby enabling sensitive detection of analytes, such as the bacterial quorum sensing molecule pyocyanin, even in complex biological media.This work has been funded by the Spanish MINECO (Grant MAT2017-
86659-R). C.H. acknowledges the Alexander von Humboldt Foundation for funding in the
framework of a Feodor Lynen fellowship. E.H.H. acknowledges receipt of a Juan de la Ciervafellowship (FJCI-2014-22598). A.M. is grateful to the funding from the European Research
Council (ERC) under the European Union’s Horizon 2020 research and innovation program
(grant agreement No. 637116, ENLIGHTMENT) and funding by the Spanish Ministerio de
Economía, Industria y Competitividad (MINECO) (Grant SEV-2015-0496 and MAT2016-79053-P. We further thank Mathias Charconnet for fruitful discussions and Vished Kumar for
TEM imaging. This work was performed under the Maria de Maeztu Units of Excellence
Program from the Spanish State Research Agency – Grant No. MDM-2017-0720.Peer reviewe
Ultrasensitive Gold Nanostar–Polyaniline Composite for Ammonia Gas Sensing
No full textGold
in the form of bulk metal mostly does not react with gases
or liquids at room temperature. On the other hand, nanoparticles of
gold are very reactive and useful as catalysts. The reactivity of
nanoparticles depends on the size and the morphology of the nanoparticles.
Gold nanostars containing copper have rough surfaces and large numbers
of active sites due to tips, sides, corners, and large surface area-to-volume
ratios due to their branched morphology. Here the sensitivity of the
gold nanostar–polyaniline composite (average size of nanostars
∼170 nm) toward ammonia gas has been investigated. For 100
ppm ammonia, the sensitivity of the composite increased to 52% from
a mere 7% value for pure polyaniline. The gold nanostar–polyaniline
composite even showed a response time as short as 15 s at room temperature.
The gold nanostars act as a catalyst in the nanocomposite. The stability
and sensitivity at different concentrations and the selectivity for
ammonia gas were also investigated
The influence of size, shape, and twin boundaries on heat-induced alloying in individual Au@Ag core-shell nanoparticles
No full textAbstract: Environmental conditions during real-world application of bimetallic core-shell nanoparticles (NPs) often include the use of elevated temperatures, which are known to cause elemental redistribution, in turn significantly altering the properties of these nanomaterials. Therefore, a thorough understanding of such processes is of great importance. The recently developed combination of fast electron tomography with in situ heating holders is a powerful approach to investigate heat-induced processes at the single NP level, with high spatial resolution in 3D. In combination with 3D finite-difference diffusion simulations, this method can be used to disclose the influence of various NP parameters on the diffusion dynamics in Au@Ag core-shell systems. A detailed study of the influence of heating on atomic diffusion and alloying for Au@Ag NPs with varying core morphology and crystallographic details is carried out. Whereas the core shape and aspect ratio of the NPs play a minor role, twin boundaries are found to have a strong influence on the elemental diffusion
