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Abstract Sensing of viral antigens has become a critical tool in combating infectious diseases. Current sensing techniques have a tradeoff between sensitivity and time of detection; with 10–30 min of detection time at a relatively low sensitivity and 6–12 h of detection at a high (picomolar) sensitivity. In this research, uniquely nanoengineered interfaces are demonstrated on 3D electrodes that enable the detection of spike antigens of SARS‐CoV‐2 and their variants in seconds at femtomolar concentrations with excellent specificity, thus, overcoming this tradeoff. The 3D electrodes, manufactured using a high‐resolution aerosol jet 3D nanoprinter, consist of a microelectrode array of sintered gold nanoparticles coated with graphene and antibodies specific to severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) spike antigens. An impedance‐based sensing modality is employed to sense several pseudoviruses of SARS‐CoV‐2 variants of concern (VOCs). This device is sensitive to most of the pseudoviruses of SARS‐CoV‐2 VOCs. A high sensitivity of 100 f
m , along with a low limit‐of‐detection of 9.2 fm within a test range of 0.1–1000 pm , and a detection time of 43 s are shown. This work illustrates that effective nano‐bioengineering of interfaces can be used to create an ultrafast and ultrasensitive healthcare diagnostic tool for combating emerging infections. -
Abstract Sensing of clinically relevant biomolecules such as neurotransmitters at low concentrations can enable an early detection and treatment of a range of diseases. Several nanostructures are being explored by researchers to detect biomolecules at sensitivities beyond the picomolar range. It is recognized, however, that nanostructuring of surfaces alone is not sufficient to enhance sensor sensitivities down to the femtomolar level. In this paper, we break this barrier/limit by introducing a sensing platform that uses a multi-length-scale electrode architecture consisting of 3D printed silver micropillars decorated with graphene nanoflakes and use it to demonstrate the detection of dopamine at a limit-of-detection of 500 attomoles. The graphene provides a high surface area at nanoscale, while micropillar array accelerates the interaction of diffusing analyte molecules with the electrode at low concentrations. The hierarchical electrode architecture introduced in this work opens the possibility of detecting biomolecules at ultralow concentrations.more » « less
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Abstract Low temperature rechargeable batteries are important to life in cold climates, polar/deep‐sea expeditions, and space explorations. Here, this work reports 3.5–4 V rechargeable lithium/chlorine (Li/Cl2) batteries operating down to −80 °C, employing Li metal negative electrode, a novel carbon dioxide (CO2) activated porous carbon (KJCO2) as the positive electrode, and a high ionic conductivity (≈5–20 mS cm−1from −80 °C to room‐temperature) electrolyte comprised of aluminum chloride (AlCl3), lithium chloride (LiCl), and lithium bis(fluorosulfonyl)imide (LiFSI) in low‐melting‐point (−104.5 °C) thionyl chloride (SOCl2). Between room‐temperature and −80 °C, the Li/Cl2battery delivers up to ≈29 100–4500 mAh g−1first discharge capacity (based on carbon mass) and a 1200–5000 mAh g−1reversible capacity over up to 130 charge–discharge cycles. Mass spectrometry and X‐ray photoelectron spectroscopy probe Cl2trapped in the porous carbon upon LiCl electro‐oxidation during charging. At −80 °C, Cl2/SCl2/S2Cl2generated by electro‐oxidation in the charging step are trapped in porous KJCO2carbon, allowing for reversible reduction to afford a high discharge voltage plateau near ≈4 V with up to ≈1000 mAh g−1capacity for SCl2/S2Cl2reduction and up to ≈4000 mAh g−1capacity at ≈3.1 V plateau for Cl2reduction.
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Abstract. Chamber oxidation experiments conducted at the Fire Sciences Laboratory in 2016 are evaluated to identify important chemical processes contributing to the hydroxy radical (OH) chemistry of biomass burning non-methane organic gases (NMOGs). Based on the decay of primary carbon measured by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS), it is confirmed that furans and oxygenated aromatics are among the NMOGs emitted from western United States fuel types with the highest reactivities towards OH. The oxidation processes and formation of secondary NMOG masses measured by PTR-ToF-MS and iodide-clustering time-of-flight chemical ionization mass spectrometry (I-CIMS) is interpreted using a box model employing a modified version of the Master Chemical Mechanism (v. 3.3.1) that includes the OH oxidation of furan, 2-methylfuran, 2,5-dimethylfuran, furfural, 5-methylfurfural, and guaiacol. The model supports the assignment of major PTR-ToF-MS and I-CIMS signals to a series of anhydrides and hydroxy furanones formed primarily through furan chemistry. This mechanism is applied to a Lagrangian box model used previously to model a real biomass burning plume. The customized mechanism reproduces the decay of furans and oxygenated aromatics and the formation of secondary NMOGs, such as maleic anhydride. Based on model simulations conducted with and without furans, it is estimated that furans contributed up to 10 % of ozone and over 90 % of maleic anhydride formed within the first 4 h of oxidation. It is shown that maleic anhydride is present in a biomass burning plume transported over several days, which demonstrates the utility of anhydrides as markers for aged biomass burning plumes.more » « less
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A series of N-doped porous carbons with different textural properties and N contents was prepared from a mixture of algae and glucose and their capability for the separation of CO 2 /CH 4 , C 2 H 6 /CH 4 , and CO 2 /H 2 binary mixtures under different conditions (bulk pressure, mixture composition, and temperature) were subsequently assessed in great detail. It was observed that the gas (C 2 H 6 , CO 2 , CH 4 , and H 2 ) adsorption capacity at different pressure regions was primarily governed by different adsorbent parameters (N level, narrow micropore volume, and BET specific surface area). More interestingly, it was found that N-doping can selectively enhance the heats of adsorption of C 2 H 6 and CO 2 , while it had a negligible effect on those of CH 4 and H 2 . The adsorption equilibrium selectivities for separating C 2 H 6 /CH 4 , CO 2 /CH 4 , and CO 2 /H 2 gas mixture pairs on the porous carbons were predicted using the ideal adsorbed solution theory (IAST) based on pure-component adsorption isotherms. In particular, sample NAHA-1 exhibited by far the best performance (in terms of gas adsorption capacity and selectivity) reported for porous carbons for the separation of these three binary mixtures. More significantly, NAHA-1 carbon outperforms many of its counterparts ( e.g. MOFs and zeolites), emphasizing the important role of carbonaceous adsorbents in gas purification and separation.more » « less