bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electro-Chemical Stripping and Capacitive Sensing Enabled Selective and Sensitive Ammonia Water Sensors
Authors: Lalwani Anand Vikas , Mu Linchao , Woo Kelly , Holiday Maximillian A , Senesky Debbie G , Tarpeh William Abraham 
Published: May 2020

Harmful algal blooms (HABs) and eutrophication cause billions of dollars in damages and irreversibly damage our aquatic ecosystem. According to Bernard et al. (2014), the costs of monitoring is on the order of 1 billion USD annually and Kim (2006) reported that due to HABs, Japan lost over 1 billion dollars in aquaculture.
To monitor and predict such blooms, we need to cost-effectively and remotely monitor pollutants in our water bodies. One prominent pollutant that is a factor in causing harmful algal bloom is dissolved ammonia from agriculture and sewage treatment plants. To that end, we propose a novel and cost-effective sensing solution that can detect ammonia in water. Using selective membrane separation and electrochemical stripping, we are able to selectively isolate ammonium ions from dissolved river water and wastewater in our small-scale 3-chamber system. Through capacitive sensing, we can then measure with high sensitivity (28-bit resolution) and precision the concentration of ammonium ions present in our final chamber.
Between the first and second chamber, there is a cation exchange membrane that allows only cations to pass through. Amongst the cations, only ammonium and hydrogen ions form gases and diffuse through the gas-permeable membrane between the second and third chamber. The ammonia gas is then dissolved into the sulfuric acid present in the third chamber. The dissolved ammonium ions change the permittivity of the overall solution and this change can be measured using highly sensitive capacitive-based sensors.
Presently, we have higher than 99% selectivity in isolating ammonium ions from wastewater and river water. Our capacitive sensor has a noise floor of 0.3 femtofarad. The combination of high selectivity and high sensitivity unlocks the ability to detect small traces of dissolved ammonia at low power draw, thus enabling the use of such methods for immersible ammonia sensors for environmental sensing applications.
References:
Bernard S, Kudela RM, Velo-Suárez L. Developing global capabilities for the observation and prediction of harmful algal blooms. In: Djavidnia S, Cheung V, Ott M, Seeyave S, editors. Oceans and society: blue planet. Cambridge Scholars Publishing; 2014. Chapter 6
Kim HG. Mitigation and controls of HABs. In: Granéli E, Turner JT, editors. Ecology of harmful algae. Ecological Studies. Vol. 189. Springer-Verlag; Berlin: 2006. pp. 327–338
Nano-Optomechanical Systems (NOMS) for Gas Chromatography Sensing
Authors: Hiebert Wayne K , Maksymowych Matthew P , Venkatasubramanian Anandram , Roy Swapan K , Elhamel Nadia , Westwood-Bachman Jocelyn N , Firdous Tayyaba 
Published: May 2020

Nano-optomechanical systems (NOMS) achieve high-precision measurement of displacement which enables very high sensitivity through mechanical resonance-shift sensing. A recent breakthrough [1] has shown that NOMS devices can operate in high-damping environment without sacrificing their frequency stability and sensing resolution. This is because stability losses from lower quality factor (Q) are offset by stability gains from a larger intrinsic signal-to-noise ratio.
We take advantage of this excellent stability to do atmospheric pressure resonant mechanical gas sensing with high sensitivity using NOMS [2]. In particular, we have set up a traditional gas chromatograph to output to a NOMS detector and shown parts-per-billion level detection [2]. By modifying the NOMS devices to make the silicon cantilevers porous, we have improved sensitivity by a further factor of 10 [3].
The next challenge, and opportunity, in using NOMS for mass sensing, is to separate the gas loading signals that affect both the mechanical and optical resonances in high optomechanical-coupling devices [4]. This is because, at high coupling, changes in optical resonance produce changes in mechanical resonance and vice versa. This effect can be used to amplify the sensing signal obtained when measuring mechanical frequency changes. In fact, it scales particularly well with high-finesse optical cavities and could lead to a situation where evanescent field gas loading on the optical cavity is transduced as a mechanical frequency shift with orders of magnitude better mass sensitivity than could be realized from the NEMS alone or the optical cavity alone. As an example, our present mass loading sensitivity is around 50 kDa [5]; improving the cavity linewidth merely by a factor of 10 should shrink that mass sensitivity by a factor of 1000, bringing it down to 50 Da. This level of sensitivity would allow studying chemical adsorption and desorption of individual gas chromatography molecules on the sensor surface and could provide a simple path for obtaining orthogonal information in gas chromatography detectors.
[1] S. K. Roy, V. T. K. Sauer, J. N. Westwood-Bachman, A. Venkatasubramanian, and W. K. Hiebert, Improving mechanical sensor performance through larger damping. Science
360, eaar5220 (2018); doi: 10.1126/science.aar5220.
[2] A. Venkatasubramanian, et al., Nano-optomechanical systems for gas chromatography. Nano Lett.
16, 6975-6981 (2016); doi: 10.1021/acs.nanolett.6b03066.
[3] A. Venkatasubramanian, et al., Porous nanophotonic optomechanical beams for enhanced mass adsorption. ACS sensors
4, 1197-1202 (2018); doi: 10.1021/acssensors.8b01366.
[4] M. P. Maksymowych, J. N. Westwood-Bachman, A. Venkatasubramanian, and W. K. Hiebert, Optomechanical spring enhanced mass sensing. Appl. Phys. Lett.
115, 101103 (2019); doi: 10.1063/1.5117159
[5] Da = Dalton = 1 amu = 1 atomic mass unit ~ 1.66 x 10-27 kg.
Graphene/Au/SiC Optical Waveguide-Based Surface Plasmon Resonance Sensor for Chemical and Biomedical Sensing in Aqueous Medium
Authors: Du Wei , Zhao Feng 
Published: May 2020

In chemical and biomedical sensing, identification and quantification of analytes in aqueous medium such as water, blood or other carriers are very important. It requires the core sensors to have the properties of low cost, high sensitivity, on-chip integration capability, etc. Various sensing methods have been developed such as prism coupler and grating coupler, etc. and among them, waveguide-based surface plasmon resonance (SPR) sensors, with sensitivity of the optical waveguide significantly improved by SPR, have been identified as a powerful tool for detection and quantitative characterization of chemical and biological species or biomolecular reactions in aqueous medium. For sensing in aqueous medium, the optical waveguide sensors are desirable to operate in the visible light wavelength to overcome the large absorption coefficient of water in the near infrared range. This high absorption coefficient causes optical energy in the near infrared incident light be absorbed by water rather than by the sensing medium. Conventional silicon (Si) is not the choice of material for such sensors due to the strong absorption below the wavelength of 1.1 μm due to its narrow bandgap (Eg=1.12 eV, 1.1 µm wavelength).
As a wide bandgap semiconductor, silicon carbide (SiC) is more desirable for such sensors with advantages of: (1) bandgap energy of 3.2 eV in 4H and 6H polytypes and 2.2 eV in 3C polytype with transparent wavelength in visible and near-infrared range, (2) excellent material properties especially the chemical inertness and biocompatibility, and (3) device fabrication compatibility with standard Si device fabrication for manufacturing and on-chip integration. Therefore, SiC is a desirable material candidate for SPR sensors for chemical and biomedical sensing in aqueous medium, and approaches to enhance its sensitivity have been explored. 2-D materials such as graphene, TMDCs (MoS2, WS2, MoSe2, WSe2), etc. and their applications in sensing technology has aroused wide attention because of their distinctive electrical and optical properties. SPR sensors with 2-D and Si to enhance the sensitivity have been studied by publications. In this paper, we investigated graphene/Au/SiC waveguide-based SPR sensors (Fig. 1) for aqueous medium sensing. The resonance frequency shift with different numbers of graphene layer were studied (Fig. 2). Comparison of resonance wavelength shift from conventional and proposed sensor were performed (Fig. 3). At the incident light of 633 nm, the confinement factor above 0.9 can be achieved at the refractive index of n=1.3~1.5. With the change of refractive index, the shift of resonant wavelength showed linear characteristics, and a sensitivity of 2580 nm/RIU (refractive index unit) was obtained in a refractive index range of n=1.34~1.36 (Fig. 4).

Figure 1
Development of Materials and Electrochemical Diagnostics for Fuel Cell-Based Ethanol Sensors
Authors: Easton E. Bradley 
Published: May 2020

The most common application of electrochemical ethanol sensors is in breathalyzer devices, which are widely used by law enforcement officers for roadside screening to combat impaired driving. These state-of-the-art breath alcohol sensors (BrAS) employ an electrochemical sensor based upon fuel cell technology. At the heart of the sensor is a membrane-electrode assembly (MEA) that employs a porous polyvinyl chloride (PVC) membrane filled with H2SO4 (aq). Each electrode contains massive amounts of Pt black catalyst (~10 - 20 mg/cm2) and a Teflon binder. The market for these devices is growing rapidly in large part due to the adoption of alcohol ignition interlocks for offenders and new OEM automotive safety requirements in some countries. As such, substantial cost reduction is needed to improve economic viability and OEM cost targets.
Despite its commercial success over the last 4 decades, electrochemical BrAS have been sparsely studied in the academic literature. Very little is known about how electrode structure influences sensor performance. Furthermore, environmental conditions are known to influence sensitivity and operational lifetime, yet the mode of degradation is not well understood. Since these devices closely mimic fuel cell technology from three-decades ago, our approach to BrAS has been to adapt materials and methods initially developed for power generating fuel cells. We have developed new MEA compositions employ 97% less Pt but can still achieve sensitivity that is on-par with current BrAS commercial technology.
In this presentation, I will describe how chemical modification of the electrocatalyst materials can yield enhanced sensitivity and/or stability. In particular, BrAS fabricated from carbon supported Pt and Pt-alloy catalysts will be discussed. Likewise, I will describe how the use of in situ electrochemical diagnostic measurements in working breathalyzer cells can be used to gain insight into how sensitivity and durability are related to electrode composition and water retention properties of the MEA.

Figure 1
Effects of Graphene As Conductive Additive on the Energy Capacity of Supercapacitors
Authors: Hung Wu-Ching , Sun Pei-Kai , Wang Ming-Jia , Chang Chin-Lung , Wang Li-Chun 
Published: May 2020

The brilliant electrical, thermal, and mechanical properties of graphene have drawn many attentions, and their possible applications on electronic devices, composite materials, gas sensors, and energy storage are intensively explored. Among many energy storage devices, supercapacitors have the advantages of providing higher power density, faster charge/discharge rates, longer cycle life, environment-friendly, and little maintenance. Supercapacitors have become indispensable in hybrid, renewable and high-pulse power systems, showing great market potentials from car, rail, electricity, communication to military industries. Present studies show that the mesoporous structures giving a high surface-to-volume ratio in graphene allow more extensive charge separation in the electrolytes of supercapacitors, endowing themselves significantly higher energy and power density.
The presently available supercapacitors in market mostly utilize activated carbon in their electrodes, while this material frequently shows low electrical conductivity, which greatly limits the energy capacity of the device. This study aims to investigate the effects of graphene, if taken as a conductive additive, on the performance of the supercapacitor. The graphene-based electrode was packaged as a cylinder cell with dimension of 40 x 138 mm. The supercapacitor utilizing 0.1 wt% graphene/5.9 wt% carbon black as the conductive additive of its electrodes showed higher capacitance (1728 F) than that with 6 wt% carbon black (1525 F) during the galvanostatic charge/discharge test at a current density of 44.5 A; the former further showed lower ESR(equivalent series resistance) (1.96 mΩ) while the later 2.86 mΩ. These results suggest that graphene as conductive additive in supercapacitors can effectively enhance the energy storage of the devices.
Aqueous All-Polyoxometalate Redox-Flow-Batteries
Authors: Pfanschilling Felix Leon , Cording Faye , Mitchinson Jack Oliver , Friedl Jochen , Holland-Cunz Matthäa Verena , Schricker Barbara , Fleck Robert , Wolfschmidt Holger , Stimming Ulrich 
Published: May 2020

Lithium-Ion Batteries (LIBs) are widely discussed and investigated as versatile energy storage systems. However, LIBs may pose safety risks, such as flammability of the electrodes and the electrolytes, which is a problem that may be amplified when transitioning from small-scale to medium- or large-scale energy storage. Yet, large-scale low-cost energy storage is crucial for the transition from a fossil fuel-based energy economy to renewable energy sources and in order to utilise the already existing energy sources like wind and solar power more efficiently.
A promising technology for this task are Redox-Flow-Batteries (RFBs). The RFB is the only type of battery where power output and energy capacity can be scaled independently, allowing it to be specifically tailored to a variety of applications. However, the most mature RFB so far, the All-Vanadium RFB, suffers from low energy density and low power density.
In order to overcome these challenges while maintaining the advantages of an aqueous RFB, like non-flammability and minimal self-discharge, we are investigating new redox chemistries. As redox systems, polyoxometalates (POMs) and specifically [SiW12O40]4- and [PV14O42]9- as nano-sized electron shuttles were investigated.1 These POMs exhibit fast redox kinetics (electron transfer constant k
0 ≈ 10-2 cm s-1 for [SiW12O40]4-) which together with their high solubility in water and multiple redox-centres per molecule provides the potential for for high power densities and high energy densities. The POMs that were used also exhibit high electrochemical and chemical stability, thus providing long cycle lifetimes. Other POMs were investigated as well.
The system was scaled up from a lab-sized cell of 25 cm2 membrane area to a cell of 1400 cm2 in order to assess the implications on efficiency and operational parameters.2 The cell was operated for 1400 cycles over a time of nearly three months, providing some very promising results; the Coulombic efficiency was nearly 100% with the energy efficiency dropping only from 86.1% to 85.1% during the whole period, indicating a highly stable system. The observed capacity loss of 0.011% per cycle could be attributed to ambient air leakage leading to oxidation of SiW12. Post-cycling analysis showed no sign of degradation of the electrolytes.

Acknowledgement

We acknowledge funding and the fruitful cooperation with SIEMENS AG. Also, funding from NECEM, the North East Centre for Energy Materials (EP/R021503/10) is thankfully acknowledged.
PQQ-Glucose Dehydrogenase-Calmodulin Chimera Enzyme: Different Triggered Activation for Multipurpose Biosensors
Authors: Bollella Paolo , Melman Artem , Guo Zhong , Edwardraja Selvakumar , Johnson Wayne , Alexandrov Kirill A. , Katz Evgeny 
Published: May 2020

In the last decade, the rise of synthetic biology has driven the efforts to construct artificial allosteric protein switches in order to detected and quantify natural and artificial chemistries in vitro and in vivo. Typically, this involves construction of chimeric enzymes via insertion of a regulatory receptor domain into the biocatalytic reporter domain. Construction of such chimeric enzymes utilizes the recombinant DNA technology that is a core technology of protein engineering [1].
Herein, we report on the bioelectrocatalytic properties of pyrroloquinoline quinone-dependent glucose dehydrogenase fusion with calmodulin (PQQ-GDH-CaM). This protein is catalytically inactive in its ground form but can be activated by the addition of calmodulin binding peptide that induces its conformational transition and activation. The PQQ-GDH-CaM was immobilized onto highly porous gold (hPG) produced electrochemically [2] by using a bifunctional linker, namely 4-mercaptobenzoic acid further activated through 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide (EDC/NHS) coupling to covalent bind the PQQ-GDH-CaM chimeric enzyme [3].
At first, we characterized the switchable features of PQQ-GDH-CaM by simply exposing it to the activating peptide. Subsequently we devised an approach to use proteolytic activation of a caged-peptide to generate activating peptide for PQQ-GDH-CaM. Furthermore, the system was utilized to study different pathways for PQQ-GDH-CaM triggered activation according to different logic gates in order to realize multipurpose biosensors (e.g., glucose detection, peptide detection etc.) [4].

References

Gamella, M., Guo, Z., Alexandrov, K., Katz, E. (2019). ChemElectroChem, 6(3), 638-645.

Bollella, P., Hibino, Y., Kano, K., Gorton, L., Antiochia, R. (2018). Analytical chemistry, 90(20), 12131-12136.

Koushanpour, A., Gamella, M., Guo, Z., Honarvarfard, E., Poghossian, A., Schöning, M. J., Alexandrov, K., Katz, E. (2017). The Journal of Physical Chemistry B, 121(51), 11465-11471.

Bollella, P., Katz, E. (2019). International Journal of Unconventional Computing, 14(3-4), 181-198.
Isoelectric Focusing in Liquid Plasticine for Protein Analysis
Authors: Niu Jicheng , Shi Haixiao , Xu Feng , Li Xiaoguang , Li Fei 
Published: May 2020

Protein analysis has found widespread applications in biomedical fields (e.g., disease diagnosis and precision medicine), especially recently in point-of-care testing (POCT). Conventional protein analysis is large-equipment-dependent, which limits its applications in POCT. Herein, we proposed a strategy using a shaped liquid entity, termed liquid plasticine (LP), as a platform to perform isoelectric focusing (IEF)-based protein analysis. The LP-IEF system mainly consisted of a separation channel, a catholyte module and an anolyte module, which were all in the form of self-standing liquid micro-containers with specific shapes and connected together. The basic functions of the LP-IEF system were examined using three standard proteins, with the results showing a clear separation, 10-folds concentration, and a resolution of 0.03 pH, meaning that this system could serve for pretreatment and analysis of proteins from complex physiological samples. The developed LP-IEF system was further demonstrated as a colorimetric quantitative analytical platform of clinical microalbuminuria with a relative error of <9.4% compared to the results obtained by the traditional clinical detection methods. Moreover, the LP-IEF system was coupled to MALDI-TOF-MS and successfully used to identify a-1-microglobulin/bikunin precursor (AMBP) in clinical diabetic urines. The LP-IEF system proposed in this work opens a flexible, versatile, and low-cost way for POCT of proteins, which could inspire many practical applications in future.

References

[1] J. C. Niu, T. Zhou, L. L. Niu, Z. S. Xie, F. Fang, F. Q. Yang, Z. Y. Wu, Simultaneous Pre-concentration and Separation on Simple Paper-based Analytical Device for Protein Analysis, Analytical and bioanalytical chemistry 410.6 (2018): 1689-1695. Doi:10.1007/s00216-017-0809-5.
[2] X. G. Li, H. X. Shi, Y. Y. Hu, Rod-shaped Liquid Plasticine for Gas Diffusion Detection, Soft matter, 15(15), 3085-3088. Doi:10.1039/c9sm00362b.
Fabrication of Pd/ Ni Alloy Nanotubes Via Electrospinning for High Performance Hydrogen Detection
Authors: Song Lu , Bulemo Peresi Majura , Koo Won-Tae , Kim Il Doo 
Published: May 2020

Hydrogen is one of the most important “next generation energy sources”, which is free for environment pollution, with water as the only emission. Due to the danger of hydrogen explosion when mixed with air, as well as the low specific heat capacity of hydrogen, the temperature required for combustion can be reached immediately even a little heat absorbed. Therefore, it’s necessary to search an effective way to monitor hydrogen leakage at room temperature.
In this study, the Pd based hydrogen sensor was investigated. During the transduction process, volumetric expansion occurred due to the hydrogen absorption at room temperature to achieve safe hydrogen detection. Previous research indicated that Pd/Ni alloy films/ nanofibers can achieve higher catalytic activity, stability and sensitivity than pure Pd films/nanofibers due to the synergistic effect between Pd and Ni
1

,2,3
. But both the films and nanofibers structures have limited specific surface area and therefore limited exposed hydrogen adsorption sites. To overcome these problems, we fabricated the porous Pd nanotubes alloyed with Ni by using Polyvinylpyrrolidone (PVP) and SiO2 templates electrospinning route, then the PVP and SiO2 templates were selectively removed by calcination and etching
4
, respectively. The sensing performance was measured by monitoring the resistance curves of sensing platform at various hydrogen concentrations. Compared to Pd/Ni nanofibers structures, tubular structures achieved lower LOD and higher sensitivity which are attributed to the high surface area and abundant hydrogen adsorption active sites. High performance Pd/Ni nanotubes can be successfully fabricated in an effective and facile approach for hydrogen detection at room temperature. At last, the effects of the concentration of Ni in Pd on the sensing performance was also investigated.
References
1. Guangyang Bao et al, “Synergistic effect of the Pd–Ni bimetal/carbon nanofiber composite catalyst in Suzuki coupling reaction.” Org. Chem. Front., 2019, 6,352.
2. Wang, Boyi et al. “Palladium Nanofiber Networks Hydrogen Sensor and Hydrogen-Actuated Switches: Proceedings of the 5th International Conference on Sustainable Design and Manufacturing (KES-SDM-18).” 10.1007/978-3-030-04290-5_12.
3. Feng, Li et al. “Pd–Ni Alloy Nanoparticles as Effective Catalysts for Miyaura–Heck Coupling Reactions.” The Journal of Physical Chemistry C 2015 119 (21), 11511-11515 DOI: 10.1021/jp510988m
4. Peresi Majura Bulemo et al, “Mesoporous SnO2 Nanotubes via Electrospinning−Etching Route:Highly Sensitive and Selective Detection of H2S Molecule.” October 17, 2019 at 10:40:01 (UTC).