A Case Study of the West Virginia Remote Online Collaborative Knowledge System

This qualitative case study provides intrinsic knowledge and perceptions about the West Virginia Remote Online Collaborative Knowledge System (WVROCKS). WVROCKS provides adult learners access to flexible, accelerated, online courses aimed towards completing a Regents Bachelor of Arts (RBA) degree or a Board of Governors Associate of Applied Science (BOG AAS) degree in West Virginia. Prior to this study, no empirical research had been conducted on the WVROCKS initiative. Procedures for data collection included website analysis and interviews using instruments created by the researcher. Fourteen higher education and related agencies’ websites were analyzed. Interviews were conducted with 15 stakeholders across three groups: a) creators and collaborators, b) administrators and staff, and c) faculty and advisors, providing further data. Application of the non-probability snowball sampling technique helped to identify interview participants. Member checks were sent to interview participants to validate the data. Triangulation of collected data, along with information collected in the literature review, further served to validate findings. Inferences about WVROCKS relate to the purpose of WVROCKS, benefits and value, barriers and drawbacks, and the future of WVROCKS. Findings infer WVROCKS as a collaborative process between institutions to help adults earn a degree. Benefits and value include greater access to online courses and promoting degree completion. Barriers and drawbacks relate to concerns about resources, processes, and online education. The future of WVROCKS indicates a growing number of students utilizing WVROCKS, and the mission for WVROCKS expanding into new areas, such as certificates

To Damn or Not Damn a Dam: Stakeholder Collaboration as a Tool for Dam Management

Dams have played an integral role in the development and economic growth of the United States for centuries, and remain important fixtures in water and energy management. However, after standing for decades, aging dams across the country are deteriorating or creating harmful environmental impacts that have made them sources of contention in many river basins. Calls to remove certain dams have been growing and in recent years have particularly intensified with respect to some large federally owned or regulated hydroelectric dams. These larger dams are subject to ongoing environmental review under the National Environmental Policy Act. Nonfederally owned dams also are subject to review through the Federal Energy Regulatory Commission’s relicensing process, and federally owned dams are reviewed by the agencies that own and manage their operations, such as the U.S. Army Corps of Engineers or Bureau of Reclamation. As dams age, these environmental reviews are generating increasing discord and litigation among dam operators, landowners, local communities, Native American Tribes, and environmental activists. Fortunately, as experience in other areas of natural resource management has shown, collaborative governance regimes that replace or supplement traditional agency decision-making can often reduce conflicts in large multistakeholder settings. Among other things, well-structured stakeholder collaboration schemes tend to incorporate more diverse perspectives and increase public acceptance of agency actions. Recognizing these potential advantages, this Article argues that federal agencies should reshape dam relicensing and reevaluation policies to incorporate more collaborative elements and outlines specific strategies for pursuing that goal

Gold/QDs-Embedded-Ceria Nanoparticles: Optical Fluorescence Enhancement as a Quenching Sensor

This work focuses on improving the fluorescence intensity of cerium oxide (ceria) nanoparticles (NPs) through added plasmonic nanostructures. Ceria nanoparticles are fluorescent nanostructures which can emit visible fluorescence emissions under violet excitation. Here, we investigated different added plasmonic nanostructures, such as gold nanoparticles (Au NPs) and Cadmium sulfide/selenide quantum dots (CdS/CdSe QDs), to check the enhancement of fluorescence intensity emissions caused by ceria NPs. Different plasmonic resonances of both aforementioned nanostructures have been selected to develop optical coupling with both fluorescence excitation and emission wavelengths of ceria. In addition, different additions whether in-situ or post-synthesis have been investigated. We found that in-situ Au NPs of a 530 nm plasmonic resonance wavelength provides the highest fluorescence emissions of ceria NPs compared to other embedded plasmonic structures. In addition to the optical coupling between plasmonic resonance of Au with the visible emissions fluorescence spectrum of ceria nanoparticles, the 530 nm in-situ Au NPs were found to reduce the bandgap of ceria NPs. We suggest that the formation of more tri-valent cerium ions traps energy levels along with more associated oxygen vacancies, which is responsible for increasing the fluorescence visible emissions intensity caused by ceria. As an application, the gold-ceria NPs is shown to optically detect the varied concentration of iron tiny particles in aqueous medium based on a fluorescence quenching mechanism. This work is promising in different applications such as biomarkers, cancer treatments, and environmental pollution monitoring

Efficiency Enhancement of Perovskite Solar Cells With Plasmonic Nanoparticles: A Simulation Study

Recently, hybrid organic-inorganic perovskites have been extensively studied due to their promising optical properties with relatively low-cost and simple processing. However, the perovskite solar cells have some low optical absorption in the visible spectrum, especially around the red region. In this paper, an improvement of perovskite solar cell efficiency is studied via simulations through adding plasmonic nanoparticles (NPs) at the rear side of the solar cell. The plasmonic resonance wavelength is selected to be very close to the spectrum range of lower absorption of the perovskite: around 600 nm. Both gold and silver nanoparticles (Au and Ag NPs) are selected to introduce the plasmonic effect with diameters above 40 nm, to get an overlap between the plasmonic resonance spectrum and the requested lower absorption spectrum of the perovskite layer. Simulations show the increase in the short circuit current density (Jsc) as a result of adding Au and Ag NPs, respectively. Enhancement in Jsc is observed as the diameter of both Au and Ag NPs is increased beyond 40 nm. Furthermore, there is a slight increase in the reflection loss as the thickness of the plasmonic nanoparticles at the rear side of the solar cell is increased. A significant decrease in the current loss due to transmission is achieved as the size of the nanoparticles increases. As a comparison, slightly higher enhancement in external quantum efficiency (EQE) can be achieved in case of adding Ag NPs rather than Au NPs

In-Situ Gold–Ceria Nanoparticles: Superior Optical Fluorescence Quenching Sensor for Dissolved Oxygen

Cerium oxide (ceria) nanoparticles (NPs) have been proved to be an efficient optical fluorescent material through generating visible emission (~530 nm) under violet excitation. This feature allowed ceria NPs to be used as an optical sensor via the fluorescence quenching Technique. In this paper, the impact of in-situ embedded gold nanoparticles (Au NPs) inside ceria nanoparticles was studied. Then, gold–ceria NPs were used for sensing dissolved oxygen (DO) in aqueous media. It was observed that both fluorescence intensity and lifetime were changed due to increased concentration of DO. Added gold was found to enhance the sensitivity of ceria to DO quencher detection. This enhancement was due to optical coupling between the fluorescence emission spectrum of ceria with the surface plasmonic resonance of gold nanoparticles. In addition, gold caused the decrease of ceria nanoparticles’ bandgap, which indicates the formation of more oxygen vacancies inside the non-stoichiometric crystalline structure of ceria. The Stern–Volmer constant, which indicates the sensitivity of optical sensing material, of ceria–gold NPs with added DO was found to be 893.7 M−1, compared to 184.6 M−1 to in case of ceria nanoparticles only, which indicates a superior optical sensitivity to DO compared to other optical sensing materials used in the literature to detect DO. Moreover, the fluorescence lifetime was found to be changed according to the variation of added DO concentration. The optically-sensitivity-enhanced ceria nanoparticles due to embedded gold nanoparticles can be a promising sensing host for dissolved oxygen in a wide variety of applications including biomedicine and water quality monitoring

Plasmonic-Ceria Nanoparticles as Fluorescence Intensity and Lifetime Quenching Optical Sensor

Ceria nanoparticles have been recently used as an optical fluorescent material with visible emission under ultraviolet excitation, due to the formation of trivalent cerium ions with corresponding oxygen vacancies. This paper introduces the enhancement of both fluorescence emission and lifetime through adding gold nanoparticles. The reason is due to possible coupling between the plasmonic resonance of gold nanoparticles and the fluorescence emission of ceria that has been achieved, along with enhanced formation of trivalent cerium ions. Both factors lead to higher fluorescence intensity peaks and shorter fluorescence lifetimes. As an application, gold-ceria nanoparticles have been used as an optical sensing material for lead particles in aqueous media based on fluorescence quenching. Stern-Volmer constant of in-situ gold-ceria nanoparticles is found to be 2.424 M−1, with a relative intensity change of up to 40% at 0.2 g/L

Structural evolution of carbon during oxidation

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1997.Includes bibliographical references (leaves 213-221).by Angelo William Kandas.Ph.D

Efficiency Improvement of Up-Conversion Process of Plasmonic-Enhanced Er-Doped-NaYF4 Nanoparticles Under IR Excitation

The up-conversion process is extensively studied because of its wide variety of applications such as bioimaging, energy harvesting, and optical sensors. However, the optical conversion efficiency is still relatively low and needs to be improved. Therefore, this paper introduces a detailed study of improving the up-conversion emission efficiency through adding plasmonic metallic nanostructures to the up-conversion optical centers. Our idea is to couple the optical plasmonic resonance with the visible emission of the optical centers under IR excitation. The optical centers are erbium ions hosted by fluoride low-phonon environment. Our calculations consider most possible transitions that can occur between the optical centers; tri-valent erbium ions, through Judd-Ofelt analysis. In addition, the effect of changing some parametric values is discussed, such as irradiance, and multi-phonon relaxations, to show their optimum values which correspond to best quantum yield efficiency. By increasing the diameter of added gold nanoparticles (Au NPs), the probability of occupation has been increased, and consequently, both the luminescence and up-conversion efficiency have been increased

Acoustic Energy Harvesting and Sensing via Electrospun PVDF Nanofiber Membrane

This paper introduces a new usage of piezoelectric poly (vinylidene fluoride) (PVDF) electrospun nanofiber (NF) membrane as a sensing unit for acoustic signals. In this work, an NF mat has been used as a transducer to convert acoustic signals into electric voltage outcomes. The detected voltage has been analyzed as a function of both frequency and amplitude of the excitation acoustic signal. Additionally, the detected AC signal can be retraced as a function of both frequency and amplitude with some wave distortion at relatively higher amplitudes and within a certain acoustic spectrum region. Meanwhile, the NFs have been characterized through piezoelectric responses, beta sheet calculations and surface morphology. This work is promising as a low-cost and innovative solution to harvest acoustic signals coming from wide resources of sound and noise