bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Studies of L-Cysteine
Authors: Cheek Graham T. , Worosz Matthew A. 
Published: February 2020

Introduction
L-Cysteine is an important amino acid because of its role in various biochemical pathways (1). Considering that L-cysteine is one of the few amino acids with significant redox characteristics, it was considered worthwhile to investigate its electrochemical behavior in various media and electrode surfaces.
Experimental
L-Cysteine was obtained from Sigma-Aldrich. Electrochemical experiments were carried out using a Gamry Interface 1000 potentiostat and Gamry Framework software. Potentials are referenced against a Ag/AgCl reference electrode. Platinum and glassy carbon electrodes were obtained from BASi.
Results and Discussion
At a platinum electrode, L-cysteine in aqueous 0.10 M KNO3 produced a cyclic voltammogram with two merged oxidation processes (Figure 1), which were much more clearly resolved using differential pulse voltammetry. Preparative electrolysis at the potential of the first oxidation process (+0.80 V) resulted in the precipitation of cystine, which is the coupling product formed as a result of one-electron L-cysteine oxidation. The current for the reduction peak at -0.60 V (dotted line in Figure 1) increased during the electrolysis, suggesting that this reduction process is related to cystine formation. Similar results, including cystine formation, were also obtained in aqueous phosphate buffer at pH 7. It is likely that the platinum oxide layer on the electrode surface plays a role in L-cysteine oxidation under these conditions (2). The results of additional studies of L-cysteine oxidation in other media, particularly dimethylsulfoxide (DMSO), are also planned for presentation.
References

C. K. Mathews, K. E. Van Holde, D. R. Appling, and S. J. Anthony-Cahill, Biochemistry, 4th Edition, Pearson Canada, Toronto, 2013.

J. Koryta and J. Pradac, J. Electroanal. Chem., 17, 185-189 (1968).

Figure 1. Cyclic voltammogram of 10 mM L-cysteine at platinum in aqueous 0.10 M KNO3. 100 mV/s.
First sweep (solid line), second sweep (dotted line).

Figure 1
Low Cost 3D Printed Biosensor Arrays for Biomedical Diagnostics
Authors: Kadimisetty Karteek , Rusling James F , Malla Spundana , Satterwhite Jennifer E 
Published: February 2020

Development and fabrication of bioanalytical devices by 3D printing offers revolutionary new routes to low cost clinical diagnostic devices for molecular measurements. Relevant to future protein-based cancer diagnostics, we describe here our development of prototype protein immunoarray devices using desktop Fused Deposition Modeling (FDM) and stereolithographic 3D printers. All these system feature sensitive electro-optical detection by a method called electrochemiluminescence (ECL). Our first 3D-printed immunoarray features screen-printed sensors in which manual manipulations enable gravity flow reagent delivery for measurement of 3 proteins at detection limits of 0.3 to 0.5 pg/mL. ECL detection is achieved in an open channel on integrated disposable screen-printed sensor elements. We then address the issue of printing and processing optically clear plastic using a stereolithographic printer to build a closed ECL detection chamber. Finally, we describe a prototype 3D-printed microprocessor-controlled enclosed microfluidic ECL immunoarray featuring reagent reservoirs, micropumps and clear plastic detection chamber with printed nanowells for ECL emission.
Ti/TiO2 as an Alternative Substrate Material for Impedance Biosensors
Authors: Liu Donghao , Rose Peter , Plunkett Kyle Newton , Suni Ian Ivar 
Published: February 2020

Impedance biosensors have been widely studied for applications to biomedicine, environmental monitoring, food, and agriculture. The most common format for AC impedance biosensors involves surface immobilization of an antibody, receptor protein, DNA strand, or other species capable of bio-recognition, and AC impedance detection of the binding event.
One obstacle to application of impedance biosensors is the stability and reproducibility of protein immobilization. Alkane-thiols deposited on gold (Au) electrodes or alkenes deposited on silicon (Si) electrodes were used as impedance biosensors previously. However, Au-thiol bonds are unstable, so proteins are only stable atop such interfaces for days to weeks. While Si sensor electrodes are more stable, gradual oxidation of Si eventually displaces the polymer-protein film. Ti/TiO2 is an attractive alternative substrate material for impedance biosensors due to the biocompatibility of Ti, and the self-limiting thickness of TiO2.
Sputtered Ti films are first cathodically stripped of the Ti native oxide, and then galvanostatically anodized in 1.0 M H2SO4. Following anodization, nitrogen doping is accomplished by annealing at 600°C in NH3/N2 in a tube furnace. A bifunctional reagent was synthesized with a carboxylate group at one end, and a phosphonate group at the other terminal end that could bind to hydroxyl groups on the surface of TiO2. This reagent is used to attach mouse monoclonal antibodies to the TiO2 surface though amide bond formation using EDC/NHSS. Peanut protein Ara h1, an allergenic food protein, can then be detected at the Ti/TiO2 sensor electrodes. The response as a function of Ara h1 concentration follows the Langmuir adsorption isotherm, as expected.
Non-Stechiometric Titanates Embellished with a Catalyst and Employed for Visible-Light Water Splitting
Authors: Bienkowski Krzysztof , Kulesza Pawel J 
Published: February 2020

Titanates are known from their photocatalytic properties, but they need additional catalysts to work efficiently also they have very high electronic conductivity when they are prepared under reducing conditions in the hydrogen flame or under thermal oxidation in high temperature. We prepared these non-stechiometric titanates as materials for visible-light water and/or small organic molecules oxidation. Specific conditions of synthesis of non-stechiometric titanates, created by oxidation of the metal at high temperature in oxygen flow, allowed to get unique properties of such films like: large surface area, high conductivity, red-shift in the absorption spectrum and stability over large range of pHs. Adding to these properties, the affinity of polyoxometalate (POMs) species to the formed structures, and their ability to catalyse the water oxydation reaction, the system of TiO2-x – POM seems to be suitable for water splitting purposes under visible light irradiation. Morover, these sub-stoechiometric titanium dioxide / titanes films exhibited red-shifted IPCE photo-action spectrum. These results demonstrated the possibility to form defective TiO2 through thermal oxidation of the titanium metal as alternative to the reduction by H2.
Scanning Electrochemical Microscopy: A Tool to Study the Biomediated Calcification Process By Sporosarcina Pasteurii Biofilm
Authors: Harris Dustin , Ummadi J Ganesh , Koley Dipankar 
Published: February 2020

Sporosarcina pasteurii, are known to perform CaCO3 precipitation by hydrolyzing urea and increasing the local pH, in presence of the Ca2+ rich brine solution. We have developed a new electrochemical probes for scanning electrochemical microscopy (SECM) to study this calcification process in real time. We have used the newly developed ultramicrosensors, such as pH, Ca2+, and redox sensors, to monitor a real-time, bacteria-mediated urea hydrolysis process and subsequent changes in morphology due to CaCO3 precipitation. We observed a rapid local (500 μm above the biofilm) pH change from 7.4 to 9.2 within 2 min of addition of urea, whereas the bulk pH remains constant at 7.5. Similar Ca2+ profile was also recorded locally where the Ca2+ concentration above the biofilm depleted from 170 mM to 1 mM. Recent developments regarding the real-time live biofilm morphological change correlated with the chemical (Ca2+ and pH) information will be presented in the meeting.
Evaluation of Co-Adsorption Effect on Performance and Outdoor Stability of Organic Dye-Sensitized Solar Cells By Electrochemical Impedance Spectroscopy
Authors: Nguyen Hoang Thai , Tran Linh Thi Phuong , Nguyen Thoa Thi Phuong 
Published: February 2020

The dye-sensitized solar cells (DSCs) based on an organic sensitizer with trade name RK1 were fabricated by new fabrication procedure. The fabrication procedure that performed in inert gas atmosphere using a glove box includes: (i) assembling sandwich cells from preparative FTO/TiO2 and FTO/Pt electrodes; (ii) filling the cells with RK1 (10 mM)/DMF solutions containing 0–10 mM chenodeoxycholic acid (CDA) and keep still for 4 hours; (iii) filling the electrolyte; and (iv) sealing the cells. In high humidity environment this new proposed procedure has proved to prevent the water uptake into the cell.
In comparison with co-adsorbate free DSCs, the energy conversion efficiency (η) of DSCs with presence of co-adsorbate was improved. However, the photo-activation effect (slight increase of η) observed during first weeks of outdoor test for DSCs with CDA co-adsorbate is lesser than that of co-adsorbate free DSCs. From 14th day of outdoor test the cell efficiency began slightly decrease, and reached the initial value after 21-day-exposure. Meanwhile for the co-adsorbate free DSCs these dates are 30th and 100th, respectively.
The electrochemical impedance spectroscopy (EIS) technique was successfully applied to study electronic and ionic processes in DSC, and consequently, to evaluate the effect of co-adsorbate on cells performance and outdoor stability. The impedance data measured at open circuit voltage (Voc) under illumination were well fitted with the equivalent circuit Rs(RPtCdl)G(CdRd), in which Rs – electrolyte solution resistance, RPt and Cdl describe the modeled charge transfer resistance and capacitance at the counter electrode. The electron transport in the titanium dioxide (TiO2) film and the back reaction at the TiO2/electrolyte interface were modeled by a Gerischer element (G), revealed by an arc at the intermediate-frequency region. The RdCd circuit elements describe the ion diffusion in the electrolyte.
Analysis of impedance spectra indicated that the increase of electron injection via the effect of co-adsorption contributed to enhancement of photocurrent. This fact was revealed by the decrease of Gerischer impedance. Meanwhile the increase of photocurrent which caused the photo-activation of the cathode interface during first weeks of outdoor exposure was interpreted by the decrease of charge transfer resistance RPt. EIS data show that DSC performance declines under prolonged outdoor exposure. The DSC ageing resulted mainly from the decrease of electron injection in TiO2 film.
Insights to the Complex Role of Surface Oxide in the Oxygen Reduction Reaction
Authors: Coleman Eric J. , Zhang Fen , Co Anne C. 
Published: February 2020

Currently our work is focused on understanding the effect of surface species including their interaction between each other and with the catalysts surface that influence the activity and selectivity of the electrocatalyst. For example, highly efficient Pt-based catalysts are now able to deliver higher currents at lower overpotential. In the case of the oxygen reduction reaction (ORR), catalysis at low ORR overpotential happens at a potential range where dynamic oxide growth is occurring on the underlying Pt and Pt alloy surfaces resulting in the catalyst becoming oxidized over periods of prolonged use which alters both the catalytic activity and selectivity with time. In this paper, we report our recent analysis on decoupling electrochemical contributions from oxide growth vs. catalytic ORR.
Understanding the Effects of pH and Alkali Cations on Cyclic Voltammograms and the Hydrogen Oxidation Reaction on Transition Metal Catalyst Surfaces
Authors: McCrum Ian T. , Meduri Praveen , Hickner Michael A , Janik Michael J. 
Published: February 2020

The electrochemical interface between a catalytic electrode surface and electrolyte is complex and its structure and composition have a direct effect on the rates and mechanisms of electrocatalytic reactions. For example, it has been found that the rate of the hydrogen oxidation reaction on a platinum electrode is strongly dependent on electrolyte pH, and this effect had tentatively been correlated to a shift in hydrogen binding strength with pH (beyond the expected Nernstian shift) as measured by cyclic voltammetry [1]. We used density functional theory (DFT) to calculate the thermodynamics of adsorption of hydrogen, hydroxide, water, and alkali cations on the low index facets of platinum to support prior work which has shown that the low potential peaks measured by cyclic voltammetry on Pt(100), Pt(110), and higher order facets containing 100 and 110 steps, actually correspond to the competitive and co-adsorption of hydrogen and hydroxide [2]. We further show that increasing pH leads to an increasing amount of specifically adsorbed alkali metal cation which weakens the binding of hydroxide, leading to the experimentally observed shift in the low potential peaks measured by cyclic voltammetry, as opposed to a strengthening of hydrogen binding [2]. Now that we understand the mechanism for these experimentally measured effects of pH and alkali cations, we use experiment and DFT to examine their effect on the rate of the hydrogen oxidation reaction, which we find, on a platinum electrode, to depend on cation identity. We also discuss this effect of pH and alkali metal cation on cyclic voltammograms and the hydrogen oxidation reaction across transition metal surfaces (Ru, Ir, Pt, and Au) as measured by Strmcnik et al. [3] and Durst et al. [4].
[1] Sheng, W.; Zhuang, Z.; Gao, M.; Zheng, J.; Chen, J. G.; Yan, Y. Correlating Hydrogen Oxidation and Evolution Activity on Platinum at Different pH with Measured Hydrogen Binding Energy. Nat. Commun.
2015,
6:5848.
[2] McCrum, I.T.; Janik, M. J. pH and alkali cation effects on the Pt cyclic voltammogram explained using density funtional theory. J. Phys. Chem. C.
2016, In Press. DOI:
10.1021/acs.jpcc.5b10979
[3] Strmcnik, D.; Uchimura, M.; Wang, C.; Subbaraman, R.; Danilovic, N.; van der, V.; Paulikas, A. P.; Stamenkovic, V. R.; Markovic, N. M. Improving the Hydrogen Oxidation Reaction Rate by Promotion of Hydroxyl Adsorption. Nat. Chem.
2013,
5, 300-306.
[4] Durst, J.; Siebel, A.; Simon, C., Hasché, F.; Herranz, J.; Gasteiger, H.A. New insights into the electrochemical hydrogen oxidation and evolution reaction mechanism. Energy Environ. Sci.
2014, 7, 2255-2260.
Tolerance of Impurities in Bioethanol on Pd/C and Pdru/C Catalysts Toward the Ethanol Oxidation Reaction in Alkaline Media
Authors: Chen Rongrong , Qi Jing , Guo Junsong , Schubert Peter , Hyden Josh , Taylor E. J. 
Published: February 2020

Although the uses of alternative energy sources have been increased greatly in recent years, current major energy demand is still supplied from conventional fossil fuels such as oil, coal and natural gas. Considering the inevitable depletion of the world’s energy supply and the release of green-house in the earth’s atmosphere, it is necessary to look for an alternative source of fuel. Alkaline-anion-exchange membrane direct alcohol fuel cells (AAEM-DAFCs) are among the promising candidates as alternative power sources for both stationary and portable power applications. Due to the facile kinetics at both the cathode and the anode in alkaline media, the use of non-noble and low-cost material catalysts become feasible, which makes the AAEM-DAFCs a potentially low cost technology compared with proton exchange membrane (PEM) based DAFCs working in acidic media.
Bioethanol has high energy density and is non-toxicity, easy to transport and can be distributed with the existing infrastructure. Bioethanol is a renewable bio-based liquid fuel that can be produced from several different biomass feedstock and conversion technologies. First generation bioethanol is produced by distillation from crops such as wheat, corn, sugar cane and sugar beet; however, this bioethanol production has limitation due to concerns about food price and land use impacts. Second generation bioethanol is produced from different types of lignocellulosic materials as substrate. Currently, only negligible amounts of second generation bioethanol are produced in several demo plants around the world that work industrially, but are not yet commercially feasible. In this work, the bioethanol was produced by diversity feed stocks, like food waste and cellulosic, away from expensive corn. The produced bioethanol may contain some impurities, such as acetic acid, lactic acid, phosphorus, maltotetraose (Dp4), glucose, maltose, fructose, glycerol, isomaltotriose (Dp3), sulfur and so on.
Pd/C was a promising catalyst for the ethanol oxidation reaction (EOR) in alkaline media. Our earlier work indicated that the PdRu/C catalyst exhibited much higher initiate activity toward EOR than the Pd/C catalyst in fuel cell operation conditions. Therefore, we further study the tolerance of impurities in bioethanol on Pd/C and PdRu/C catalysts toward EOR in alkaline media and demonstrate their performance and stability in AAEM-DAFCs using bioethanol as the fuel.
Acknowledgements
We acknowledge financial supports from the National Science Foundation Partnerships for Innovation: Building Innovation Capacity (Contract 1317731).
Exploring Extracellular Electron Transfer in Hyperthermophiles for Electrochemical Energy Conversion
Authors: Sekar Narendran , Wu Chang-Hao , Adams Michael W. W. , Ramasamy Ramaraja P. 
Published: February 2020

Hyperthermophiles are microorganisms that thrive in extremely hot environment from 80 oC and upwards. They are the most primitive organisms evolved to survive in the early unhostile earth. The simplest and versatile respiratory electron transport chain of these hyperthermophiles made them suitable candidates for microbial fuel cells (MFC) anode catalysts to generate power at high temperatures. We explored the extracellular electron transfer ability of a hyperthermophilic archaeon called Pyrococccus furiosus (PF). PF is an aquatic anaerobe that grows optimally at 100 oC using a wide range of substrates such as carbohydrates and peptides1. The respiratory chain of PF is simple and unique that it does not require any terminal electron acceptor, rather reduces proton to H2 through membrane bound enzyme complex called hydrogenase2. Their ability to reduce the extracellular oxidants such as insoluble Fe(III) oxide and soluble Fe(III) citrate has been investigated. PF reduced Fe(III) oxide during its growth at 90 oC and the PF culture re-suspended in MOPS buffer (pH 7.5) was found to reduce Fe(III) citrate significantly using H2 as an electron donor. Further, low scan-rate cyclic voltammetry at 90 oC using potassium ferricyanide as a mediator showed greater mediated electron transfer by PF compared to the control without PF. The proof of concept study reported here reveals the potential of PF to generate electricity in MFCs at high temperature locations such as in solfataric fields or near hydrothermal vents. Moreover, such studies also help to advance our understanding in the field of biogeochemistry of the early hot environment and exobiology.

References:

S. D. Hamilton-Brehm, G. J. Schut and M. W. W. Adams (2005) J Bacteriol., 187(21): 7492–7499

S Mukund and M. W. W. Adams (1991) J. Biol. Chem., 266(22), 14208-14216.

Figure 1
Taxonomic Dynamics of Nitrate Reducing Microbial Fuel Cell Communities
Authors: Salvacion Michael , Ishii Shunichi , Ishii Shino , Bussey Lauren , Carpenter Kayla , Babanova Sofia , Bretschger Orianna 
Published: February 2020

The presence of nitrogen encourages the growth of organic matter and algae, which leads to eutrophication of marine and freshwater ecosystems. In conventional wastewater treatment facilities the removal of nitrogen is achieved through simultaneous nitrification and denitrification of the wastewater. Microbial fuel cells (MFC) present an alternative technology to conventional methods for nitrate removal. The MFC is a bioelectrochemical device capable of harvesting electrons from organic sources. Bacteria in the anode compartment oxidize organic compounds, and the electrons are transferred across an external load to a terminal electron acceptor at the cathode. A typical MFC has an abiotic cathode and biotic anode. Recently more attention has been given toward the utilization of biological cathodes for the reduction of sulfate, nitrate, carbon dioxide, fumarate, and other electron acceptors. Previous studies have demonstrated an MFC’s capacity for biological denitrification at the cathode1 where bacteria can reduce nitrate to nitrite to nitrogen gas. In this study we monitored the performance and taxonomic dynamics of two denitrifying MFCs with different cathode materials.
A two-chamber reactor configuration (600mL total volume) was used with alternative cathode catalysts. Acetate was provided at the anode as the electron donor and sodium nitrate was introduced at the cathode as the electron acceptor. Denitrification efficiency of the MFC was evaluated as a function of the different cathode materials and the taxonomic communities. One of the reactors had carbon cloth cathode with activated carbon/carbon black mixture (AC-MFC); the other reactor had carbon cloth cathode with carbon black layer (CB-MFC). Nitrate was periodically added to cathode chamber and the concentration of nitrate and nitrite was periodically monitored. Initial results show a removal rate of 2.02 mg/L/d and 5.31 mg/d [NO3
-] for the AC-MFC and CB-MFC after 230 days of operation. Biofilm and planktonic samples were periodically extracted from the anode, cathode, solution, and membranes of each system and were used to estimate the phylogenetic composition of each community based on 16S rRNA gene sequences. The presence of Geobacteraceae at the anode supports the observed acetate consumption and current production of both systems. Additionally, denitrifying and nitrifying bacteria were identified in the cathode compartment and support the simultaneous nitrification and denitrification observed in the cathode chamber. Further studies will be conducted to evaluate functional roles of dominant species in the community.

Figure 1