Showing papers by "University of Delaware published in 2018"

General Techno-Economic Analysis of CO2 Electrolysis Systems

Abstract: The electrochemical reduction of carbon dioxide (CO2) has received significant attention in academic research, although the techno-economic prospects of the technology for the large-scale production of chemicals are unclear. In this work, we briefly reviewed the current state-of-the-art CO2 reduction figures of merit, and performed an economic analysis to calculate the end-of-life net present value (NPV) of a generalized CO2 electrolyzer system for the production of 100 tons/day of various CO2 reduction products. Under current techno-economic conditions, carbon monoxide and formic acid were the only economically viable products with NPVs of $13.5 million and $39.4 million, respectively. However, higher-order alcohols such as ethanol and n-propanol could be highly promising under future conditions if reasonable electrocatalytic performance benchmarks are achieved (e.g. 300mA/cm2 and 0.5V overpotential at 70% faradaic efficiency). Herein, we established performance targets such that if these targets are ach...

On the Fintech Revolution: Interpreting the Forces of Innovation, Disruption, and Transformation in Financial Services

Abstract: The financial services industry has been experiencing the recent emergence of new technology innovations and process disruptions. The industry overall, and many fintech start-ups are looking for ne...

Mechanistic Insights into Electrochemical Nitrogen Reduction Reaction on Vanadium Nitride Nanoparticles

Abstract: Renewable production of ammonia, a building block for most fertilizers, via the electrochemical nitrogen reduction reaction (ENRR) is desirable; however, a selective electrocatalyst is lacking. Her...

Iterative near-term ecological forecasting: Needs, opportunities, and challenges

Abstract: Two foundational questions about sustainability are "How are ecosystems and the services they provide going to change in the future?" and "How do human decisions affect these trajectories?" Answering these questions requires an ability to forecast ecological processes Unfortunately, most ecological forecasts focus on centennial-scale climate responses, therefore neither meeting the needs of near-term (daily to decadal) environmental decision-making nor allowing comparison of specific, quantitative predictions to new observational data, one of the strongest tests of scientific theory Near-term forecasts provide the opportunity to iteratively cycle between performing analyses and updating predictions in light of new evidence This iterative process of gaining feedback, building experience, and correcting models and methods is critical for improving forecasts Iterative, near-term forecasting will accelerate ecological research, make it more relevant to society, and inform sustainable decision-making under high uncertainty and adaptive management Here, we identify the immediate scientific and societal needs, opportunities, and challenges for iterative near-term ecological forecasting Over the past decade, data volume, variety, and accessibility have greatly increased, but challenges remain in interoperability, latency, and uncertainty quantification Similarly, ecologists have made considerable advances in applying computational, informatic, and statistical methods, but opportunities exist for improving forecast-specific theory, methods, and cyberinfrastructure Effective forecasting will also require changes in scientific training, culture, and institutions The need to start forecasting is now; the time for making ecology more predictive is here, and learning by doing is the fastest route to drive the science forward

Multi-day rhythms modulate seizure risk in epilepsy

Abstract: Epilepsy is defined by the seemingly random occurrence of spontaneous seizures. The ability to anticipate seizures would enable preventative treatment strategies. A central but unresolved question concerns the relationship of seizure timing to fluctuating rates of interictal epileptiform discharges (here termed interictal epileptiform activity, IEA), a marker of brain irritability observed between seizures by electroencephalography (EEG). Here, in 37 subjects with an implanted brain stimulation device that detects IEA and seizures over years, we find that IEA oscillates with circadian and subject-specific multidien (multi-day) periods. Multidien periodicities, most commonly 20-30 days in duration, are robust and relatively stable for up to 10 years in men and women. We show that seizures occur preferentially during the rising phase of multidien IEA rhythms. Combining phase information from circadian and multidien IEA rhythms provides a novel biomarker for determining relative seizure risk with a large effect size in most subjects.

High-rate electroreduction of carbon monoxide to multi-carbon products

Abstract: Carbon monoxide electrolysis has previously been reported to yield enhanced multi-carbon (C2+) Faradaic efficiencies of up to ~55%, but only at low reaction rates. This is due to the low solubility of CO in aqueous electrolytes and operation in batch-type reactors. Here, we present a high-performance CO flow electrolyser with a well controlled electrode–electrolyte interface that can reach total current densities of up to 1 A cm–2, together with improved C2+ selectivities. Computational transport modelling and isotopic C18O reduction experiments suggest that the enhanced activity is due to a higher surface pH under CO reduction conditions, which facilitates the production of acetate. At optimal operating conditions, we achieve a C2+ Faradaic efficiency of ~91% with a C2+ partial current density over 630 mA cm–2. Further investigations show that maintaining an efficient triple-phase boundary at the electrode–electrolyte interface is the most critical challenge in achieving a stable CO/CO2 electrolysis process at high rates. The low solubility of CO in aqueous electrolytes limits the implementation of CO electrolysers, since low current densities are typically achieved despite the fact that they deliver rather high Faradaic efficiencies to multi-carbon products. Now, Jiao and co-workers report a CO flow electrolyser with a well-controlled electrode–electrolyte interface that can achieve multi-carbon Faradaic efficiencies of 91% with a partial current density of 630 mA cm–2.

Globally rising soil heterotrophic respiration over recent decades.

Abstract: Global soils store at least twice as much carbon as Earth’s atmosphere1,2. The global soil-to-atmosphere (or total soil respiration, RS) carbon dioxide (CO2) flux is increasing3,4, but the degree to which climate change will stimulate carbon losses from soils as a result of heterotrophic respiration (RH) remains highly uncertain5–8. Here we use an updated global soil respiration database9 to show that the observed soil surface RH:RS ratio increased significantly, from 0.54 to 0.63, between 1990 and 2014 (P = 0.009). Three additional lines of evidence provide support for this finding. By analysing two separate global gross primary production datasets10,11, we find that the ratios of both RH and RS to gross primary production have increased over time. Similarly, significant increases in RH are observed against the longest available solar-induced chlorophyll fluorescence global dataset, as well as gross primary production computed by an ensemble of global land models. We also show that the ratio of night-time net ecosystem exchange to gross primary production is rising across the FLUXNET201512 dataset. All trends are robust to sampling variability in ecosystem type, disturbance, methodology, CO2 fertilization effects and mean climate. Taken together, our findings provide observational evidence that global RH is rising, probably in response to environmental changes, consistent with meta-analyses13–16 and long-term experiments17. This suggests that climate-driven losses of soil carbon are currently occurring across many ecosystems, with a detectable and sustained trend emerging at the global scale.

A Highly Porous Copper Electrocatalyst for Carbon Dioxide Reduction.

Abstract: Electrochemical reduction of carbon dioxide (CO2 ) is an appealing approach toward tackling climate change associated with atmospheric CO2 emissions. This approach uses CO2 as the carbon feedstock to produce value-added chemicals, resulting in a carbon-neutral (or even carbon-negative) process for chemical production. Many efforts have been devoted to the development of CO2 electrolysis devices that can be operated at industrially relevant rates; however, limited progress has been made, especially for valuable C2+ products. Herein, a nanoporous copper CO2 reduction catalyst is synthesized and integrated into a microfluidic CO2 flow cell electrolyzer. The CO2 electrolyzer exhibits a current density of 653 mA cm-2 with a C2+ product selectivity of ≈62% at an applied potential of -0.67 V (vs reversible hydrogen electrode). The highly porous electrode structure facilitates rapid gas transport across the electrode-electrolyte interface at high current densities. Further investigations on electrolyte effects reveal that the surface pH value is substantially different from the pH of bulk electrolyte, especially for nonbuffering near-neutral electrolytes when operating at high currents.

The Power of Play: A Pediatric Role in Enhancing Development in Young Children

Abstract: Children need to develop a variety of skill sets to optimize their development and manage toxic stress. Research demonstrates that developmentally appropriate play with parents and peers is a singular opportunity to promote the social-emotional, cognitive, language, and self-regulation skills that build executive function and a prosocial brain. Furthermore, play supports the formation of the safe, stable, and nurturing relationships with all caregivers that children need to thrive. Play is not frivolous: it enhances brain structure and function and promotes executive function (ie, the process of learning, rather than the content), which allow us to pursue goals and ignore distractions. When play and safe, stable, nurturing relationships are missing in a child’s life, toxic stress can disrupt the development of executive function and the learning of prosocial behavior; in the presence of childhood adversity, play becomes even more important. The mutual joy and shared communication and attunement (harmonious serve and return interactions) that parents and children can experience during play regulate the body’s stress response. This clinical report provides pediatric providers with the information they need to promote the benefits of play and and to write a prescription for play at well visits to complement reach out and read. At a time when early childhood programs are pressured to add more didactic components and less playful learning, pediatricians can play an important role in emphasizing the role of a balanced curriculum that includes the importance of playful learning for the promotion of healthy child development.

Hexokinase-2 depletion inhibits glycolysis and induces oxidative phosphorylation in hepatocellular carcinoma and sensitizes to metformin

Abstract: Hepatocellular carcinoma (HCC) cells are metabolically distinct from normal hepatocytes by expressing the high-affinity hexokinase (HK2) and suppressing glucokinase (GCK). This is exploited to selectively target HCC. Hepatic HK2 deletion inhibits tumor incidence in a mouse model of hepatocarcinogenesis. Silencing HK2 in human HCC cells inhibits tumorigenesis and increases cell death, which cannot be restored by GCK or mitochondrial binding deficient HK2. Upon HK2 silencing, glucose flux to pyruvate and lactate is inhibited, but TCA fluxes are maintained. Serine uptake and glycine secretion are elevated suggesting increased requirement for one-carbon contribution. Consistently, vulnerability to serine depletion increases. The decrease in glycolysis is coupled to elevated oxidative phosphorylation, which is diminished by metformin, further increasing cell death and inhibiting tumor growth. Neither HK2 silencing nor metformin alone inhibits mTORC1, but their combination inhibits mTORC1 in an AMPK-independent and REDD1-dependent mechanism. Finally, HK2 silencing synergizes with sorafenib to inhibit tumor growth.

Electron magnetic reconnection without ion coupling in Earth's turbulent magnetosheath

Abstract: Magnetic reconnection in current sheets is a magnetic-to-particle energy conversion process that is fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron-scale diffusion region1,2. On larger scales, ions couple to the newly reconnected magnetic-field lines and are ejected away from the diffusion region in the form of bi-directional ion jets at the ion Alfven speed3-5. Much of the energy conversion occurs in spatially extended ion exhausts downstream of the diffusion region 6 . In turbulent plasmas, which contain a large number of small-scale current sheets, reconnection has long been suggested to have a major role in the dissipation of turbulent energy at kinetic scales7-11. However, evidence for reconnection plasma jetting in small-scale turbulent plasmas has so far been lacking. Here we report observations made in Earth's turbulent magnetosheath region (downstream of the bow shock) of an electron-scale current sheet in which diverging bi-directional super-ion-Alfvenic electron jets, parallel electric fields and enhanced magnetic-to-particle energy conversion were detected. Contrary to the standard model of reconnection, the thin reconnecting current sheet was not embedded in a wider ion-scale current layer and no ion jets were detected. Observations of this and other similar, but unidirectional, electron jet events without signatures of ion reconnection reveal a form of reconnection that can drive turbulent energy transfer and dissipation in electron-scale current sheets without ion coupling.

Paragraph-level Neural Question Generation with Maxout Pointer and Gated Self-attention Networks

Abstract: Question generation, the task of automatically creating questions that can be answered by a certain span of text within a given passage, is important for question-answering and conversational systems in digital assistants such as Alexa, Cortana, Google Assistant and Siri Recent sequence to sequence neural models have outperformed previous rule-based systems Existing models mainly focused on using one or two sentences as the input Long text has posed challenges for sequence to sequence neural models in question generation – worse performances were reported if using the whole paragraph (with multiple sentences) as the input In reality, however, it often requires the whole paragraph as context in order to generate high quality questions In this paper, we propose a maxout pointer mechanism with gated self-attention encoder to address the challenges of processing long text inputs for question generation With sentence-level inputs, our model outperforms previous approaches with either sentence-level or paragraph-level inputs Furthermore, our model can effectively utilize paragraphs as inputs, pushing the state-of-the-art result from 139 to 163 (BLEU_4)

Navigating complexity to breed disease-resistant crops.

Abstract: Plant diseases are responsible for substantial crop losses each year and pose a threat to global food security and agricultural sustainability. Improving crop resistance to pathogens through breeding is an environmentally sound method for managing disease and minimizing these losses. However, it is challenging to breed varieties with resistance that is effective, stable and broad-spectrum. Recent advances in genetic and genomic technologies have contributed to a better understanding of the complexity of host-pathogen interactions and have identified some of the genes and mechanisms that underlie resistance. This new knowledge is benefiting crop improvement through better-informed breeding strategies that utilize diverse forms of resistance at different scales, from the genome of a single plant to the plant varieties deployed across a region.

Cleaner fuels for ships provide public health benefits with climate tradeoffs

Abstract: We evaluate public health and climate impacts of low-sulphur fuels in global shipping. Using high-resolution emissions inventories, integrated atmospheric models, and health risk functions, we assess ship-related PM2.5 pollution impacts in 2020 with and without the use of low-sulphur fuels. Cleaner marine fuels will reduce ship-related premature mortality and morbidity by 34 and 54%, respectively, representing a ~ 2.6% global reduction in PM2.5 cardiovascular and lung cancer deaths and a ~3.6% global reduction in childhood asthma. Despite these reductions, low-sulphur marine fuels will still account for ~250k deaths and ~6.4 M childhood asthma cases annually, and more stringent standards beyond 2020 may provide additional health benefits. Lower sulphur fuels also reduce radiative cooling from ship aerosols by ~80%, equating to a ~3% increase in current estimates of total anthropogenic forcing. Therefore, stronger international shipping policies may need to achieve climate and health targets by jointly reducing greenhouse gases and air pollution.

Postsynthetic Functionalization of Three-Dimensional Covalent Organic Frameworks for Selective Extraction of Lanthanide Ions.

Abstract: Chemical functionalization of covalent organic frameworks (COFs) is critical for tuning their properties and broadening their potential applications. However, the introduction of functional groups, especially to three-dimensional (3D) COFs, still remains largely unexplored. Reported here is a general strategy for generating a 3D carboxy-functionalized COF through postsynthetic modification of a hydroxy-functionalized COF, and for the first time exploration of the 3D carboxy-functionalized COF in the selective extraction of lanthanide ions. The obtained COF shows high crystallinity, good chemical stability, and large specific surface area. Furthermore, the carboxy-functionalized COF displays high metal loading capacities together with excellent adsorption selectivity for Nd3+ over Sr2+ and Fe3+ as confirmed by the Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. This study not only provides a strategy for versatile functionalization of 3D COFs, but also opens a way to their use in environmentally related applications.

Graphene-Boosted, High-Performance Aqueous Zn-Ion Battery.

Abstract: Given their low cost and eco-friendliness, rechargeable Zn-ion batteries (ZIBs) have received increasing attention as a device with great potential for large-scale energy storage. However, the development of ZIBs with high capacities and long lifespans is challenging because of the dendritic growth of Zn and the absence of suitable cathode materials. Herein, we report a novel rechargeable aqueous Zn-ion battery (AZIB) that consist of Zn coated with reduced graphene oxide as the anode and V3O7·H2O/rGO composite as the cathode. The new AZIB exhibits excellent cycle stability with a high capacity retention of 79% after 1000 cycles. Moreover, it can deliver a high power density of 8400 W kg–1 at 77 W h kg–1 and a high energy density of 186 W h kg–1 at 216 W kg–1, and the former is higher than those of previously reported AZIBs. Our work provides a new perspective in developing rechargeable ZIBs and would greatly accelerate the practical applications of rechargeable ZIBs.

Fast, Ambient Temperature and Pressure Ionothermal Synthesis of Three-Dimensional Covalent Organic Frameworks

Abstract: Covalent organic frameworks (COFs) are an emerging class of porous crystalline polymers with wide range of potential applications. However, the availability of three-dimensional (3D) COFs is still limited, and their synthesis is confined to the high-temperature solvothermal method. Here, we report for the first time a general and simple strategy to produce a series of 3D ionic liquid (IL)-containing COFs (3D-IL-COFs) by using IL as a green solvent. The syntheses are carried out at ambient temperature and pressure accompanied by a high reaction speed (e.g., only three mins for 3D-IL-COF-1), and the IL can be reused without activity loss. Furthermore, the 3D-IL-COFs show impressive performance in the separation of CO2/N2 and CO2/CH4. This research thus presents a potential pathway to green large-scale industrial production of COFs.

Anserini: Reproducible Ranking Baselines Using Lucene

Abstract: This work tackles the perennial problem of reproducible baselines in information retrieval research, focusing on bag-of-words ranking models. Although academic information retrieval researchers have a long history of building and sharing systems, they are primarily designed to facilitate the publication of research papers. As such, these systems are often incomplete, inflexible, poorly documented, difficult to use, and slow, particularly in the context of modern web-scale collections. Furthermore, the growing complexity of modern software ecosystems and the resource constraints most academic research groups operate under make maintaining open-source systems a constant struggle. However, except for a small number of companies (mostly commercial web search engines) that deploy custom infrastructure, Lucene has become the de facto platform in industry for building search applications. Lucene has an active developer base, a large audience of users, and diverse capabilities to work with heterogeneous collections at scale. However, it lacks systematic support for ad hoc experimentation using standard test collections. We describe Anserini, an information retrieval toolkit built on Lucene that fills this gap. Our goal is to simplify ad hoc experimentation and allow researchers to easily reproduce results with modern bag-of-words ranking models on diverse test collections. With Anserini, we demonstrate that Lucene provides a suitable framework for supporting information retrieval research. Experiments show that our system efficiently indexes large web collections, provides modern ranking models that are on par with research implementations in terms of effectiveness, and supports low-latency query evaluation to facilitate rapid experimentation

New Ways of Seeing through Qualitative Research

Abstract: Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Bansal, Pratima; Smith, Wendy; Vaara, Eero

Electron-scale dynamics of the diffusion region during symmetric magnetic reconnection in space

Abstract: Magnetic reconnection is an energy conversion process that occurs in many astrophysical contexts including Earth’s magnetosphere, where the process can be investigated in situ by spacecraft. On 11 July 2017, the four Magnetospheric Multiscale spacecraft encountered a reconnection site in Earth’s magnetotail, where reconnection involves symmetric inflow conditions. The electron-scale plasma measurements revealed (i) super-Alfvenic electron jets reaching 15,000 kilometers per second; (ii) electron meandering motion and acceleration by the electric field, producing multiple crescent-shaped structures in the velocity distributions; and (iii) the spatial dimensions of the electron diffusion region with an aspect ratio of 0.1 to 0.2, consistent with fast reconnection. The well-structured multiple layers of electron populations indicate that the dominant electron dynamics are mostly laminar, despite the presence of turbulence near the reconnection site.

Quantitative Elastography Methods in Liver Disease: Current Evidence and Future Directions.

Abstract: US and MR elastographic techniques have developed into accurate methods for quantitative, noninvasive diagnosis of liver fibrosis in a wide range of etiologies; however, interpretation of results should take into account potential confounding factors, pitfalls, and technical limitations.