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Nanoscale Carbonate Ion-Selective Amperometric/Voltammetric Probes Based on Ion-Ionophore Recognition at the Organic/Water Interface: Hidden Pieces of the Puzzle in the Nanoscale Phase
No full textHere, we report on the successful demonstration and application of carbonate (CO32-) ion-selective amperometric/voltammetric nanoprobes based on facilitated ion transfer (IT) at the nanoscale interface between two immiscible electrolyte solutions. This electrochemical study reveals critical factors to govern CO32--selective nanoprobes using broadly available Simon-type ionophores forming a covalent bond with CO32-, i.e., slow dissolution of lipophilic ionophores in the organic phase, activation of hydrated ionophores, peculiar solubility of a hydrated ion-ionophore complex near the interface, and cleanness at the nanoscale interface. These factors are experimentally confirmed by nanopipet voltammetry, where a facilitated CO32- IT is studied with a nanopipet filled with an organic phase containing the trifluoroacetophenone derivative CO32-ionophore (CO32-ionophore VII) by voltammetrically and amperometrically sensing CO32- in water. Theoretical assessments of reproducible voltammetric data confirm that the dynamics of CO32- ionophore VII-facilitated ITs (FITs) follows the one-step electrochemical (E) mechanism controlled by both water-finger formation/dissociation and ion-ionophore complexation/dissociation during interfacial ITs. The yielded rate constant, k0 = 0.048 cm/s, is very similar to the reported values of other FIT reactions using ionophores forming non-covalent bonds with ions, implying that a weak binding between CO32- ion-ionophore enables us to observe FITs by fast nanopipet voltammetry regardless of the nature of bondings between the ion and ionophore. The analytical utility of CO32--selective amperometric nanoprobes is further demonstrated by measuring the CO32- concentration produced by metal-reducing bacteria Shewanella oneidensis MR-1 as a result of organic fuel oxidation in bacterial growth media in the presence of various interferents such as H2PO4-, Cl-, and SO42
The Fundamental Patterns of Sea Surface Temperature
No full textFor over 40 years, remote sensing observations of the Earth’s oceans have yielded global measurements of sea surface temperature (SST).With a resolution of approximately 1 km, these data trace physical processes like western boundary currents, cool upwelling at eastern boundary currents, and the formation of mesoscale and sub-mesoscale eddies. To discover the fundamental patterns of SST on scales smaller than 10 km, we developed an unsupervised, deep contrastive learning model named NENYA. We trained NENYA on a subset of 8 million cloud-free cutout images (~ 80 × 80km2) from the MODerate-resolution Imaging Spectroradiometer (MODIS) sensor, with image augmentations to impose invariance to rotation, reflection, and translation. The 256-dimension latent space of NENYA defines a vocabulary to describe the complexity of SST and associates images with like patterns and features. We used a dimensionality reduction algorithm to explore cutouts with a temperature interval of ΔT = 0.5-1 K, identifying a diverse set of patterns with temperature variance on a wide range of scales. We then demonstrated that SST data with large-scale features arise preferentially in the Pacific and Atlantic Equatorial Cold Tongues and exhibit a strong seasonal variation, while data with predominantly sub-mesoscale structure preferentially manifest in western boundary currents, select regions with strong upwelling, and along the Antarctic Circumpolar Current. We provide a web-based user interface to facilitate the geographical and temporal exploration of the full MODIS dataset. Future efforts will link specific SST patterns to select dynamics (e.g., frontogenesis) to examine their distribution in time and space on the globe
Avoiding Artifacts in the Determination of Per- and Polyfluoroalkyl Substance Sorbent-Water Distribution
No full textCharacterizing sorbent affinity for a target compound (described by sorbent-water distribution coefficient, Ksw) is a necessary step in the sorbent selection and performance-testing process in the process of capturing aquatic contaminants. However, no standardized procedure exists to measure Ksw, and studies display significant variations in setup and performance. For per- and polyfluoroalkyl substances (PFAS), most Ksw determinations employ batch experiments with small-scale water-sorbent mixtures, methanol-based spike of target compound(s), and analysis after assumed equilibrium, but methodological details of the above procedure differ and might cause artifacts in the determination of Ksw. We conducted several batch experiments systematically varying a general procedure to characterize the effects of suboptimal experimental design. Using a selection of PFAS (6-carbon fluorinated chain length with differing functional groups) and two sorbents, we tested variations of a solution/sorbent ratio, methanol content, and PFAS initial concentration and compared derived Ksw values. Each methodological component affected log(Ksw) usually by suppressing the value (by 0-48%) when compared with a “best design” procedure. Thus, we suggest (1) a reference procedure for PFAS and sorbents used here and (2) general guidelines for batch experiment design with different compounds and sorbents. Additionally, we report well-constrained Ksw values for 23 PFAS and two sorbents
Applying landscape metrics to species distribution model predictions to characterize internal range structure and associated changes
No full textDistributional shifts in species ranges provide critical evidence of ecological responses to climate change. Assessments of climate-driven changes typically focus on broad-scale range shifts (e.g. poleward or upward), with ecological consequences at regional and local scales commonly overlooked. While these changes are informative for species presenting continuous geographic ranges, many species have discontinuous distributions—both natural (e.g. mountain or coastal species) or human-induced (e.g. species inhabiting fragmented landscapes)—where within-range changes can be significant. Here, we use an ecosystem engineer species (Sabellaria alveolata) with a naturally fragmented distribution as a case study to assess climate-driven changes in within-range occupancy across its entire global distribution. To this end, we applied landscape ecology metrics to outputs from species distribution modelling (SDM) in a novel unified framework. SDM predicted a 27.5% overall increase in the area of potentially suitable habitat under RCP 4.5 by 2050, which taken in isolation would have led to the classification of the species as a climate change winner. SDM further revealed that the latitudinal range is predicted to shrink because of decreased habitat suitability in the equatorward part of the range, not compensated by a poleward expansion. The use of landscape ecology metrics provided additional insights by identifying regions that are predicted to become increasingly fragmented in the future, potentially increasing extirpation risk by jeopardising metapopulation dynamics. This increased range fragmentation could have dramatic consequences for ecosystem structure and functioning. Importantly, the proposed framework—which brings together SDM and landscape metrics—can be widely used to study currently overlooked climate-driven changes in species internal range structure, without requiring detailed empirical knowledge of the modelled species. This approach represents an important advancement beyond predictive envelope approaches and could reveal itself as paramount for managers whose spatial scale of action usually ranges from local to regional
3D Morphodynamic Visualizations of Storm Impacts for Decision Support
No full text3D flood visualizations are commonly used by coastal managers and other experts to engage the public regarding storm impacts, and to support management decisions. 3D flood visualizations do not, however, capture physical changes to the landscape, such as erosion, that result from storms and do significant damage to human habitations and change ecological systems. We address this gap by presenting novel 3D morphodynamic visualizations that depict physical changes to the coastal mor-phology wrought by modelled storms. We propose these visualizations may be more effective than flood visualizations as decision support tools in situations where shoreline change is a factor. We de-scribe the process of creating the visualizations for storm, sea level, and mitigation scenarios and make observations of their possibilities and limitations. The visualizations plainly show profoundly different outcomes than flood visualizations for the same storm. These visualizations may be extremely useful in the sedimentary contexts considered. However, the lack of clear conventions and complexity of creating these visualizations means that more experimentation is required before such visualizations can be considered for wide application
Adults\u27 Subjective Experiences of Exploitation in South Africa
Get PDFThe exploitation of people in the environments in which they live and work continues to be a challenge globally despite efforts by stakeholders at national and international levels to bring this to a halt. Exploitation has both short-term and long-term impacts on the lives of the survivors. Attention should be given to preventing new incidents and addressing ongoing exploitation. However, there is a lack of research that focuses on the subjective experiences of different forms of exploitation within the Western Cape, South Africa. Therefore, this paper explores individuals’ experiences of being exploited, focusing on the types of exploitative situations participants are exposed to. This study sample consists of 417 adults residing in Cape Town and surrounding areas, of which 84% were South African, and 16% were from other African countries. Data were collected using a structured survey with additional semi-structured interview questions. This report used only responses to specific semi-structured questions, which were analysed through thematic analysis. The findings reveal that study participants often experience situations that leave them vulnerable to multiple forms of exploitation. This includes experiences of abuse and economic vulnerability; specifically, participants reported working in abusive environments and their economic vulnerabilities being exploited. It was also found that the type of employment could create vulnerability, which left participants at an increased risk for exploitation. Considering this, the study calls for the collaboration of different stakeholders, including but not limited to the families, community, leaders, scholars, and governmental and non-governmental sectors, in developing and prioritising strategies to prevent exploitation. This is essential in protecting and safeguarding the rights of individuals and building a just South Africa where everyone can thrive free from exploitation by others
URI Undergraduate and Graduate Course Catalog 2023-2024
Get PDFThis is a downloadable PDF version of the University of Rhode Island course catalog.https://digitalcommons.uri.edu/course-catalogs/1075/thumbnail.jp
Longboard Braking System
Get PDFA lot of kids, teenagers and young adults struggle to ride longboards because there is no safe way to properly stop the longboard after it has reached a very high velocity. For this project we will investigate and come up with a safe braking system that longboard riders can use.
To suit the needs for this project, the design must be able to be manufactured twice, once for a prototype and once for a final product, and the total price cannot exceed 300. Our proof of concept was a 3D printed braking system attached to a set of large longboard wheels that we bought from a company and we used it to test the mechanism’s ability to slow down the wheel.
During the spring semester, we had to make some design adjustments, and we redesigned our product three times. After manually and CNCing the parts, we were able to build our final product without going over our budget limit. Our final product was a V-brake style system, affixed to the skateboard axle with two rubber pads contacting the wheel surface. Once this was fully assembled, we were able to complete two tests, one was to measure heat generation between brake pads and wheels, and the other was to measure braking time. Both were successful and we considered our product to be finished. In the future, we plan to conduct different tests, adjust materials and develop new features as a torque arm, and request a patent for our idea
Propane Fast Cook Off
Get PDFTeam 11 was presented with a task from Naval Ordnance Safety and Security to develop and design a method of creating a clean burning system to cook off military munitions. Specifications that were presented to the team included: The apparatus must be a certain size to encapsulate flames around all to be tested munitions. The design must reach a desired temperature in a finite time, as well as hold a consistent higher temperature for the duration of the test. The burner also had to be modular, meaning it could be taken apart to be stored while not in use, and easily assembled when needed. Finding a solution to line freezing was another design specification, liquid propane converting to vapor propane draws heat from the ambient air causing piping and components to become cold. The temperature combined with ambient humidity causes freezing. Solutions to these specifications were initially outlined and generated by each team member. The best solutions to each specification were then cross referenced to ensure there were no patent infringements on pre-existing designs. A QFD analysis was then performed to vet out the best designs generated.
With understanding how to meet these specifications, a design had to be generated. The team used resources of a pre-existing system to assist with modeling the design. Key aspects such as fuel type and required pressure to achieve the specifications were taken from the already existing system. Having complete knowledge of the design, the team was then able to begin simulating to assure the initial build would meet the requirements needed. Simulations for fluid flows, burn rates and temperatures were conducted successfully and proved that the design would meet the requirements.
With the knowledge and data in hand, the team was able to begin the initial build. Limited funding created a slight hurdle for the team in the beginning, but with a few generous donations of material, and labor, an initial design to test was created. After testing, the initial design did not perform as the simulations predicted. Adjustments were made and retesting of the final design took place, giving better results but still not meeting some of the requirements. A plan of action for future teams tasked with this project was then created to streamline already completed work