116 research outputs found

    Transport Contaminant in Flowing Water for Improving Water Quality

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    Clean freshwater is fundamental to sustain human activities and the aquatic life. However, cities, industries, and agriculture wastes deteriorate water quality. For example, released fertilizer induces excess algal growth. This leads to major ecological problems such as eutrophication of freshwater ecosystems which has not only a great environmental cost impact, but can also affect the health and sustenance living of the people. This project investigates the transport of nitrate, a major plant fertilizer, in flowing freshwater. Streams and rivers can transform nitrate, thus mitigating its impact. Most of the biogeochemical reactions involved in nitrate removal take place where microorganisms usually thrive, at the sediment or water interfaces. We propose to study how the riverbed sediment influences nitrate transport and transformation. At Notre Dame University, our group conducted tracer experiments in artificial streams at the Linked Ecosystem Experimental Facility (LEEF). The experiment was conducted by co-injecting a conservative tracer (NaCl) and a nitrate salt (KNO3) and measuring their concentration over time at a downstream station. The data shows how their behavior differs as a function of time. Because water flowing through the sediment is much slower than the surface flow, we can make a space for time substitution and attribute longer timescales to travel in the hyporheic zone. As a result, we can attribute reaction rates to specific reactive zones in the stream. Our results show that benthic and hyporheic nitrate uptakes were reflected in the shape of the nitrate breakthrough curves. The benthic zone induced an exponentially decreasing nitrate signal at early times, while the hyporheic uptake was reflected by the truncation of the late time power law tail. We suggest that our analysis should be useful to scientists and managers alike, as we provide a new, spatially explicit, understanding of nitrate fate in flowing systems

    The robustness of interdependent clustered networks

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    It was recently found that cascading failures can cause the abrupt breakdown of a system of interdependent networks. Using the percolation method developed for single clustered networks by Newman [Phys. Rev. Lett. {\bf 103}, 058701 (2009)], we develop an analytical method for studying how clustering within the networks of a system of interdependent networks affects the system's robustness. We find that clustering significantly increases the vulnerability of the system, which is represented by the increased value of the percolation threshold pcp_c in interdependent networks.Comment: 6 pages, 6 figure

    The enhancement of electrochemical capacitance of biomass-carbon by pyrolysis of extracted nanofibers

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    Biomass-derived carbons have been extensively researched as electrode material for energy storage and conversion recently. However, most of the previous works convert crude biomass directly into carbon and the electrochemical capacitances for the resultant carbons are quite often underestimated as well as large variations in capacitances exist in literatures due to the complex nature of biomass, which practically hinder their applications. In this work, polysaccharide nanofibers were extracted from an inexpensive natural fungus using a hydrothermal method and were converted to porous carbon nanofibers (CNFs) by potassium hydroxide activation. The porous carbons were assembled into symmetric supercapacitors using both potassium hydroxide and an ionic liquid (IL) as electrolytes. Solid state nuclear magnetic resonance characterization showed that the micropores of the as-prepared carbons are accessible to the IL electrolyte when uncharged and thus high capacitance is expected. It is found in both electrolytes the electrochemical capacitances of CNFs are significantly higher than those of the porous carbon derived directly from the crude fungus. Furthermore, the CNFs delivered an extraordinary energy density of 92.3 Wh kg−1 in the IL electrolyte, making it a promising candidate for electrode materials for supercapacitors.<br/

    Dynamic coordination of miscible polymer blends towards highly designable shape memory effect

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    Miscible polymer blends offer great designability on shape memory effect (SME) with adjustable mechanical properties and stimuli-responsiveness, by simply changing the constituent compositions. However, the thermodynamics understanding behind those SMEs on miscible polymer blends are yet to be explored. This paper describes an approach to achieve highly designable SMEs with adjustable glass transition temperature (Tg) and width of glass transition zone by dynamically coordinating components in miscible blends. An extended domain size model was formulated based on the Adam-Gibbs theory and Gaussian distribution theory to study the synergistic coordination of component heterogeneities on conformational entropy, glass transition and relaxation behaviour of the miscible blend. The effectiveness of model was demonstrated by applying it to predict dual- and triple-SMEs in miscible polymer blends, where the theoretical results show good agreements with the experiment results. We expect this study provide an effective guidance on designing advanced miscible polymer blends based on the SME

    Fiber Surface/Interfacial Engineering on Wearable Electronics.

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    Funder: Henry Royce Institute for Advanced MaterialsSurface/interfacial engineering is an essential technique to explore the fiber materials properties and fulfil new functionalities. An extensive scope of current physical and chemical treating methods is reviewed here together with a variety of real-world applications. Moreover, a new surface/interface engineering approach is also introduced: self-assembly via π-π stacking, which has great potential for the surface modification of fiber materials due to its nondestructive working principle. A new fiber family member, metal-oxide framework (MOF) fiber shows promising candidacy for fiber based wearable electronics. The understanding of surface/interfacial engineering techniques on fiber materials is advanced here and it is expected to guide the rational design of future fiber based wearable electronics

    Fiber Surface/Interfacial Engineering on Wearable Electronics

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    From Wiley via Jisc Publications RouterHistory: received 2021-05-18, rev-recd 2021-06-29, pub-electronic 2021-08-21Article version: VoRPublication status: PublishedFunder: Henry Royce Institute for Advanced MaterialsFunder: EPSRC; Id: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/R00661X/1, EP/P025021/1, EP/P025498/1Funder: Short Research Visits UK Fluids Network; Grant(s): EP/N032861/1Abstract: Surface/interfacial engineering is an essential technique to explore the fiber materials properties and fulfil new functionalities. An extensive scope of current physical and chemical treating methods is reviewed here together with a variety of real‐world applications. Moreover, a new surface/interface engineering approach is also introduced: self‐assembly via π–π stacking, which has great potential for the surface modification of fiber materials due to its nondestructive working principle. A new fiber family member, metal‐oxide framework (MOF) fiber shows promising candidacy for fiber based wearable electronics. The understanding of surface/interfacial engineering techniques on fiber materials is advanced here and it is expected to guide the rational design of future fiber based wearable electronics

    Sweat permeable and ultrahigh strength 3D PVDF piezoelectric nanoyarn fabric strain sensor

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    Commercial wearable piezoelectric sensors possess excellent anti-interference stability due to their electronic packaging. However, this packaging renders them barely breathable and compromises human comfort. To address this issue, we develop a PVDF piezoelectric nanoyarns with an ultrahigh strength of 313.3 MPa, weaving them with different yarns to form three-dimensional piezoelectric fabric (3DPF) sensor using the advanced 3D textile technology. The tensile strength (46.0 MPa) of 3DPF exhibits the highest among the reported flexible piezoelectric sensors. The 3DPF features anti-gravity unidirectional liquid transport that allows sweat to move from the inner layer near to the skin to the outer layer in 4 s, resulting in a comfortable and dry environment for the user. It should be noted that sweating does not weaken the piezoelectric properties of 3DPF, but rather enhances. Additionally, the durability and comfortability of 3DPF are similar to those of the commercial cotton T-shirts. This work provides a strategy for developing comfortable flexible wearable electronic devices

    Textile Waste Fiber Regeneration via a Green Chemistry Approach: A Molecular Strategy for Sustainable Fashion

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    From Wiley via Jisc Publications RouterHistory: received 2021-07-06, rev-recd 2021-08-15, pub-electronic 2021-09-24, pub-print 2021-12-02Article version: VoRPublication status: PublishedFunder: EPSRC; Id: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/R00661X/1, EP/P025021/1, EP/P025498/1Abstract: Fast fashion, as a continuously growing part of the textile industry, is widely criticized for its excessive resource use and high generation of textiles. To reduce its environmental impacts, numerous efforts are focused on finding sustainable and eco‐friendly approaches to textile recycling. However, waste textiles and fibers are still mainly disposed of in landfills or by incineration after their service life and thereby pollute the natural environment, as there is still no effective strategy to separate natural fibers from chemical fibers. Herein, a green chemistry strategy is developed for the separation and regeneration of waste textiles at the molecular level. Cellulose/wool keratin composite fibers and multicomponent fibers are regenerated from waste textiles via a green chemical process. The strategy attempts to reduce the large amount of waste textiles generated by the fast‐developing fashion industry and provide a new source of fibers, which can also address the fossil fuel reserve shortages caused by chemical fiber industries and global food shortages caused by natural fiber production
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