bluuebunny/crossref_metadata_2025 huggingface dataset:
Study about Electrostatic Deposition of CdTe Quantum Dots on Glassy Carbon Electrodes
Authors: Muñoz Eduardo Carlo , Rojas Víctor , Navarrete Emilio Alonso , Román Javier , Henríquez Rodrigo Gonzalo , Schrebler Ricardo Silvio , Romero Mario
Published: February 2020

Quantum Dots (QDs) are semiconductor nanocrystals. These materials are characterized for its continuous absorption spectra at wavelengths ranging from ultraviolet to visible. This feature is directly related to the size of the nanoparticle. Considering their applications, these materials can be employed in solar cells, lasers, light emitting diodes, electronic devices, among others. However, one of the most attractive applications for QDs has been as sensors or biosensor.

In this work, the synthesis of CdTe Quantum Dots was carried out in aqueous media using Na2TeO3 and CdCl2 as precursors of Te2- and Cd2+ ions, respectively, mercaptosuccinic acid (MSA) as capping agent and NaBH4 as reducing agent. The QDs obtained as colloids were purified and characterized by transmission electron microscopy (TEM), while their optical properties were characterized by UV-visible spectroscopy. After, an electrostatic deposition of the QDs on a Glassy Carbon (GC) electrode was done. This last was carried out applying a positive potential value regarding to the zero charge potential of the electrode in an aqueous media, and the influence of the potential value, deposition time was determined by means cyclic voltammetry. A study of surface conductivity changes of the glassy carbon electrodes after QDs deposition was performed by means Scanning Electrochemical Microscopy (SECM). With this was possible to observe aggregates of CdTe QDs deposited on GC electrodes indicating a possible irreversible electrostatic deposition
Hydrogen Generation Reaction of Sodium Borohydride Catalyzed By Gold and Platinum Nanoparticles
Authors: Long Julia Madeline , Heyman Austin , Huff Clay , Abdel-Fattah Tarek M
Published: February 2020

The increasing energy demands of the world today have prompted a more thorough investigation into alternative fuels. The renewable nature of hydrogen gas and its environmentally-benign byproducts when produced by the hydrolysis reaction of water and sodium borohydride have identified this as a viable method of production for the alternative fuel. Gold and platinum nanoparticles were synthesized using beta-cyclodextrin for applications in hydrogen evolution reactions from sodium borohydride (NaBH4). The resulting homogenous metal nanoparticles were characterized using Ultraviolet- visible spectroscopy and Transmission Electron Microscope (TEM). Catalytic activity of the hydrogen evolution reactions was measured using a previously described gravimetric water displacement system [1,2]. The data collected shows an increase in the efficiency of the hydrogen generation reaction with the addition of gold and platinum nanoparticles when compared to the un-catalyzed reaction. Overall, gold nanoparticles showed the highest reaction rate of 0.0016 mol-1 sec-1 at a standard concentration of NaBH4, standard pH 7 and an increased temperature at 30 °C. The platinum nanoparticle catalyzed reaction preformed best with a standard concentration of NaBH4 and a standard pH 7 solution producing a rate constant of 0.0021 mol-1 sec-1. All reaction rates were determined to be second order kinematic reactions.

References

1. T. Dushatinski, C. Huff, and T. Abdel-Fattah, Applied Surface Science, 385, 282 (2016).

2. C. Huff, T. Dushatinski, A. Barzanji, N. Abdel-Fattah, K. Barzanji, and T. Abdel-Fattah, ECS J Solid State, 6, M69-M71 (2017).
(Invited) 2D Transition Metal Carbides (MXenes) in Flow-Assisted Electrochemical Energy and Water Technologies
Authors: Akuzum Bilen , Agartan Lutfi , Kumbur E. Caglan , Gogotsi Yury
Published: February 2020

In recent years, 2D transition metal carbides, also known as MXenes, have attracted much attention and found applications in many different areas due to their unique physical structure and properties [1]. Previous studies have also shown that MXene can exhibit excellent potential for electrochemical energy storage and water treatment applications due to its high electronic conductivity, good chemical and structural stability, and high surface area [1-2]. More recently, our group has found significant potential in utilization of MXene electrodes for flow-assisted electrochemical systems such as capacitive deionization (CDI) and electrochemical flow capacitors (EFCs). For CDI, along with high conductivity and surface area, hydrophilicity of MXenes seems to work well for better pore accessibility. Similarly, easy dispersability in water and high surface charge for solution stability were also found to enable much higher active material loading for flowable electrode systems, which can open up a new plethora of possibilities. In this talk, some of our most recent work on these systems, potentials for further improvement, and some of the potential drawbacks will be discussed. 

References

[1] Anasori, B., Lukatskaya, M. R., & Gogotsi, Y. (2017). Nature Reviews Materials, 2, 16098.

[2] Lipatov, A., Alhabeb, M., Lukatskaya, M. R., Boson, A., Gogotsi, Y., & Sinitskii, A. (2016). Advanced Electronic Materials, 2(12), 1600255.
High Electrical Power Densities from Salinity Gradients By Combining Electrode and Donnan Potentials in a Single Electrochemical Cell
Authors: Gorski Christopher A , Kim Taeyoung , Logan Bruce E.
Published: February 2020

Salinity gradients exist when two waters have different salt concentrations (e.g., when freshwater reaches seawater at coasts or when desalination brine is mixed with less saline water). Salinity gradients contain an immense amount of potential energy, which can theoretically provide 40% of the global electrical demand. One means to harvest salinity gradient energy is to use electrochemical techniques. In an electrochemical cell, a voltage can be created by using salinity gradients to alter electrode potentials in Capacitive Mixing or creating Donnan potentials across ion-exchange membranes in Reverse Electrodialysis. The main challenge with these techniques is that they yield power densities that are too low for commercialization (Capacitive Mixing: ~0.4 W/m2, Reverse Electrodialysis: ~3 W/m2). Here, we combined these two types of potentials in a single electrochemical cell, greatly increasing power densities to values that exceed 12 W/m2 when mixing synthetic freshwater and seawater. We examined how cell design and operating parameters as well as electrode and membrane materials influenced power production and energy efficiency. The results suggest that this type of cell may be used to effectively harvest salinity gradient energy at coasts and produce electricity from saline desalination brines.
(Invited) What would Thomas Malthus tell us in the 21st Century?: Experiences in the Water-Energy-Food Nexus from an International Development Perspective
Authors: Miralles-Wilhelm Fernando
Published: February 2020

Ongoing research focused on analyzing the synergies and tradeoffs posed by the water-energy-food nexus is presented. This covers the need for quantitative tools (e.g., data, models) to support the analysis of integrated water, energy and food systems, from three perspectives relevant to the work of international development organizations: dialog with countries and increasing awareness of “nexus” thinking and planning, building regional and in-country capacity toward integrated planning and identification/evaluation of trade-offs and synergies in developing such systems, and fostering interdisciplinary expertise in principles, algorithms, and model formulations for understanding and evaluating the potential of implementing nexus approaches within a systems perspective. This research stresses the necessity of integrating areas of disciplinary expertise, the ability to identify and address shared needs of water, energy and food stakeholders, and facilitating tailored analyses over different spatial and temporal scales. Outputs and products of recent nexus work will highlight further research and development needs focused on upstream sector planning in order to identify primary opportunities and constraints to water, energy, and food system development, and also result in an improved understanding of economic and social trade-offs among competing nexus priorities, and particularly prioritization of sector investments. Three recent studies in South Africa, China and Latin America are presented as examples of nexus tradeoffs offering a rationale for investment rationalization and priorities.
New Anion Exchange Membranes Tailored to Address Problems in Energy Conversion and Water Purification
Authors: Herring Andrew M , Pandey Tara P , Sarode Himanshu N , Liu Ye , Kuo Mei-Chen
Published: February 2020

Anion exchnge membranes (AEMs) are the weak link in low-cost versatile fuel cells and electrolyzers and in electrochemically driven water purification systems. The potential of anion exchange membrane (AEM) fuel cells to provide inexpensive compact power from a wider variety of fuels than is possible with a proton exchange membrane (PEM) fuel cell, has continued to drive the research interest in this area. Alkaline catalysis in fuel cells has been demonstrated with non-precious metal catalysts, and with a variety of fuels beyond H2 and methanol. Alkaline fuel cells (AFCs), based on aqueous solutions of KOH, have serious drawbacks associated with system complexity and carbonate formation. Anion exchange membrane (AEMs) fuel cells have a number of advantages over both PEM fuel cells and traditional AFCs; however, although anionic conductivity in AEMs can be comparable to PEMs the chemical stability of membrane attached cations in hydroxide is still not always sufficient for practical applications. Recently, it has been recognized that a number of advanced cations, may give AEMs the needed chemical stability for practical applications. Inspired by this we have attached C6 N-heterocyclic cations to a novel tri-block polymer that may be lightly cross-linked. In this way we have fabricated a processable scalable material with a more stable cation that has desirable mechanical properties. We can fabricate these polymers as large area <20 μm films. As an unexpected benefit the material also has low water uptake and high hydroxide conductivity. In this presentation we will discuss the materials properties in terms of its physical chemistry, morphology and ion transport, investigated by PFGSE NMR, SAXS and electrochemical impedance spectroscopy. We will also present some preliminary data on the membranes performance in fuel cells, electrolyzers, and in elecrodialysis for water purification.
Evaluating the Potential for Hydrogen Production with Donnan-Driven Multi-Ion Exchange Membrane Based Systems
Authors: Nazemi Mohammadreza , Agles Avery , Dobson Kelsey , Hatzell Marta C.
Published: February 2020

Reverse electrodialysis (RED) is a membrane-based electrochemical system used for harvesting salinity gradient energy (2.6 TW) through the mixing of sea and river water at global estuaries[1]. This is accomplished through a series of anion and cation exchange membranes (AEM and CEM), which drive electrical energy production at adjacent redox electrodes. As more membranes are added to the system, the generated potential increases which increases current production.

Galvanic operation of RED for electricity production has been demonstrated, but electrical power density and limiting current density are typically less than 0.2 W/m2 and 10 A/m2 [2]. Here, we propose to produce hydrogen with a RED cell, through operating in an electrolytic mode. This multiple membrane electrolysis process is partially driven by the membranes through their “Donnan-potential”, and partially driven by additional electrical energy input [3-6]. By pushing the RED cell into the electrolytic region, high current density needed for hydrogen production, can be achieved.

Here, hydrogen production using an electrolytic RED is evaluated with a varying number of cell pairs (1 to 10) and with acidic, neutral and basic electrolytes at a fixed 10 mA/cm2. Under neutral conditions, the resulting voltage obtained from the RED cell decreased from 2.1± 0.1 V to 1.2±0.2 as the number of cell pairs increased from 1 to 10. In addition, the energy conversion efficiency of the system decreased due to the increase in mixing energy (ΔGmix.) from 130.6 J to 1203.2 J at higher cell pairs. When the cell was operated with an acidic cathode and basic anode, the applied voltage and energy consumption decreased by 45% compared to neutral pH. In addition, the current density achieved was 4x greater at a voltage 1 cell pair. The hydrogen to electrical energy ratio increased from to 100% at 2 mA/cm2 when the number of cell pairs increased from 1 to 10 with neutral electrolytes. This ratio increased by 3x under acid-base electrolytes.

Logan, B.E. and M. Elimelech. Nature, 2012. 488(7411): p. 313-319.

Zhu, X., He, W., & Logan, B. E. (2015). Reducing pumping energy by using different flow rates of high and low concentration solutions in reverse electrodialysis cells. Journal of Membrane Science, 486, 215-221.

Hatzell, M.C., I. Ivanov, R.D. Cusick, X. Zhu, and B.E. Logan. Physical Chemistry Chemical Physics, 2014. 16(4): p. 1632-1638.

Nazemi, M., Zhang J., Hatzell M.C., “Harvesting Natural Salinity Gradient Energy for Hydrogen Production through Reverse Electrodialysis (RED) Power Generation”, J. Electrochem. En. Conv. Stor., 2017; DOI: 10.1115/1.4035835.

Hatzell, M.C., X. Zhu, and B.E. Logan. ACS Sustainable Chemistry & Engineering, 2014. 2(9): p. 2211-2216.

Nazemi, M., Padgett, J., and Hatzell, M.C. (2017). Acid/Base Multi‐Ion Exchange Membrane‐Based Electrolysis System for Water Splitting. Energy Technology.
Sustainable, Inexpensive Synthesis of High Purity Graphite from Biomass with Excellent Performance in Li-Ion Battery Anodes
Authors: Banek Nathan A , Abele Dustin T , McKenzie Kevin R. , Wagner Michael J
Published: February 2020

Graphite is classified as a strategic and critical mineral by the US and EU. The worldwide market for graphite was ~ $15 billion in 2016. It is used in numerous industries including metallurgy, refractories and dominates the market for active materials in Li-ion battery anodes.

Both natural and synthetic graphites are used for Li-ion anodes. Natural graphite is mined but requires large-scale beneficiation and purification with HF, HCl and H2SO4, with a large environmental impact to water, land and air. In addition, attaining the purity levels required for Li-ion application results in as much as ~70% material loss. The production of synthetic graphite is a very long and extremely energy intensive process (heating at ~ 3000 ˚C for weeks) and results in very large scale environmentally deleterious emissions.

Predicted growth in the graphite market will be driven by sharp increases in the market for Li-ion batteries, with 12 "mega" factory scheduled to begin production by 2020. Tesla's "giga" factory alone is thought to require the output of 4 - 6 new flake graphite mines or the equivalent quantity of synthetic graphite. However, supplies of natural graphite are under pressure with China recently closing ~ 200 flake graphite mines due to their environmental impact. In addition, shortages in the supply of the high quality needle petcoke necessary for synthetic graphite production are predicted. As a result, graphite price have tripled in the past 10 years, as production has been flat.

Here we report the first Li-ion battery grade synthetic graphite made from biomass. The production is carbon negative, rapid, high yield and low cost. We have demonstrated the synthesis from cellulose, lignin and inexpensive whole biomass feedstock including sawdust and corncob. The resulting graphite is extremely high purity and highly crystalline, matching commercial synthetic graphites. Its performance in Li-ion batteries is outstanding, achieving near theoretical capacity with extremely long cycle life (see figure). Details of the synthesis, characterization and performance will be presented.

Figure 1
(Invited) Reanimating Paralyzed Limbs and the Future of Bioelectronic Medicine
Authors: Bouton Chad
Published: February 2020

Millions suffer from diseases and injuries that lead to paralysis through disruption of signal pathways between the brain and the muscles. Bioelectronic devices are designed to restore lost function and can be used to form an electronic ‘neural bypass’ to circumvent disconnected pathways in the nervous system. Intracortically-recorded signals have been decoded to produce information related to motion allowing non-human primates and paralyzed humans to control computers and robotic arms through imagined movements. In a first-in-human clinical study, it has been shown that intracortically-recorded signals can be linked in real-time to muscle activation to restore movement in a paralyzed human. Machine-learning algorithms were developed to decode the neuronal activity and control electrical stimulation of the participant’s forearm muscles through a custom-built high-resolution neuromuscular electrical stimulation system. The system allowed the participant to achieve isolated finger movements and continuous cortical control of six different wrist and hand motions. Furthermore, the participant completed functional tasks relevant to daily living. Clinical assessment showed that when using the system, the participant’s motor impairment level improved from C5-C6 to a C7-T1 level unilaterally, giving him the critical abilities to grasp, manipulate and release objects. This was the first demonstration of successful control of muscle contraction utilizing intracortically-recorded signals in a paralyzed human. These results have significant implications in advancing bioelectronic technology for the millions of people worldwide living with paralysis. Future work will include developing improved machine learning algorithms and high-resolution implantable neural interface technology to support highly dexterous movement in the hand and movement in the lower extremities. Also, decoding methods are being developed for peripheral nervous system signals for extraction of important biomarkers for the diagnosis and treatment of a wide variety of diseases and conditions.
(Invited) Exploring Brain Chemistry with Microelectrodes
Authors: Wightman Robert Mark
Published: February 2020

Neurotransmitters are small molecules that are secreted from neurons into the extracellular space to communicate with adjacent neurons. Once released, the neurotransmitters diffuse to receptors, specific proteins on the surface of neurons that bind to the neurotransmitter. This binding causes an alteration in the properties of the neuron. Through this mechanism, information can be processed in the brain. It has been demonstrated that microelectrodes can be used to detect neurotransmitters as they diffuse through the extracellular space. This provides a unique way to measure these substances as they relay information and to probe the mechanisms that regulate their actions. Examples will be shown in which the neurotransmitter dopamine is detected on a subsecond time scale in the brain of a behaving animal with a carbon-fiber microelectrode.
(Invited) Carbon Nanotube-Based Microelectrodes for Enhanced Neurochemical Detection
Authors: Zestos Alexander George , Venton B. Jill
Published: February 2020

Carbon-fiber microelectrodes (CFMEs) have been traditionally used with fast scan cyclic voltammetry (FSCV) to detect neurochemicals in vivo. However, there are several challenges in detecting neurochemical changes using bare CFMEs. First and foremost, fouling has been shown to significantly decrease sensitivity through the formation of biopolymers from serotonin and other analytes that block sites for analyte absorption. The loose sheets of graphene that make up the carbon fiber also have relatively low conductivities, which result in slow electron transfer for electrode materials and low temporal resolution. Carbon Nanotubes (CNTs) have shown to be promising for use as electrode materials. Carbon nanotubes (CNTs) are highly sp2 hybridized, which is very advantageous for measuring fast neurochemical changes in vivo. The CNTs also contain a high percentage of edge-plane carbon that is the catalytic site for neurotransmitter oxidation, which is fouling resistant. Furthermore, the cylindrical structure of CNTs provide a high aspect ratio, which allows for more sites for analyte adsorption and high sensitivity to detect low basal levels of neurochemicals. Several methods have been developed to incorporate CNTs onto CFMEs such as dipcoating; however, the method is highly variable and produces noise. Wetspinning CNTs with polymers or acids to form CNT fiber has been shown to be highly efficacious in developing novel electrode materials. For example, poly(ethyleneimine) CNT fiber microelectrodes were fouling resistant to both serotonin and 5-hydroxyindoleacetic acid (5-HIAA). They were also able to detect exogenously applied serotonin onto brain slices. Acid spun CNT fiber microelectrodes were formed with either sulfuric acid or chlorosulfonic acid that preclude the use of sonication, polymers, or surfactants, which act as impurities that reduce sensitivity.
Boron-Doped Diamond Sensors for Neurotransmitter Detection: Fabrication and Characterization
Authors: Becker Michael , Rusinek Cory Allen , Fan Bin , Li Wen , Guo Yue , Rechenberg Robert
Published: February 2020

In vivo neurotransmitter sensing has developed into a significantly prominent field over the course of the past two decades. With biocompatibility and ease of miniaturization, electrochemical methods are a powerful tool for these measurements. This has largely been completed with carbon fiber microelectrodes where several analytes such as dopamine and serotonin have been detected at very low levels. However, carbon fiber electrodes can be prone to fouling and thus, boron-doped diamond (BDD) has emerged as a material capable of long-term reliability and stability. While, BDD-coated tungsten (W) wires have been used for in vivo dopamine detection in mouse brains, a remaining issue is the significant difference in Young’s modulus from BDD (»1000 GPa) and that of brain tissue (103- 105
GPa). The strain between a rigid implant and soft tissue has been thought to be a cause of irreversible tissue damage and negative immune response. Hence, a flexible material is desired to prevent such damage from occurring and polymer-based neural implants have shown promise as a possible implantable device. Though BDD is unable to be deposited directly on a polymer substrate, we developed a wafer transfer process from BDD on silicon (Si) substrates to flexible Parylene-C substrates (an FDA-approved and USP Class VI biocompatible polymer). The fabricated sensors included BDD working, reference and counter electrodes and were characterized using several analytes including Ferricyanide (Fe(CN)6
3/4-), Ruthenium hexaaamine (Ru(NH3)6
2+/3+), and dopamine. Fast scan cyclic voltammetric (FSCV) and chronoamperometric measurements of dopamine were completed as well. These novel fabricated BDD sensors on Parylene-C open a new avenue of electrochemical-based neurotransmitter sensing with potential in vivo measurement capability.

Figure 1
(Invited) In Vivo Electrochemical Monitoring of Free Endogenous Hydrogen Sulfide
Authors: Zhang Meining
Published: February 2020

Increasing researches have demonstrated that hydrogen sulfide is an important neuromodulator in the CNS and the third gasotransmitter joined with nitric oxide and carbon monoxide. It not only protects neurons and gila, and induces hippocampal long-term potential, but also is related to CNS diseases, such as Alzheimer’s disease, Parkinson’s disease, ischemic stroke and traumatic brain injury. Although there are some methods to determine hydrogen sulfide, the transformation of different forms of sulfide (S2-, HS-, H2S, bound sulfane sulfur et al.) and the chemical instability (easily oxidized) of hydrogen sulfide in physiological conditions render a great challenge to in vivo track accurately of the free hydrogen sulfide in the brain under the physiological condition.

Motivated by this need, we are dedicating to develop in vivo electrochemical method for selective monitoring free hydrogen sulfide in the brain. Based on the specific H2S-induced chemical reaction (i.e. precipitate metals salts), we synthesized an electrochemiluminescent (ECL) probe and developed a reaction-based turn-on ECL sensor to selectively detect extracellular hydrogen sulfide in the microdialysate of rat brain taking advantage of the volatile property of hydrogen sulfide. More recently, we find one electrochemical mechanism that ammineruthenium(III) (Ru(NH3)6
3+) can catalyze the electrochemical oxidation of free sulfide including both forms of HS- and H2S in a neutral solution. Based on our mechanism, we developed one simple and effective method to in vivo track the dynamic of free hydrogen sulfide in the free moving animal, which can’t reach by other developed probes and methods. These methods open a new opportunity and offers a simple and effective platform for investigations of hydrogen sulfide in physiological and pathological processes.

References

[1] Zhang, M.; Yu, P.; Mao, L. Acc. Chem. Res. 2012, 45, 533.

[2] Yue, X.; Zhu, Z.; Zhang, M.; Ye, Z. Anal. Chem. 2015, 87, 1839.

[3] Qiu, W.; Xu, M.; Li, R.; Liu, X.; Zhang, M. Anal. Chem. 2016, 88, 1117.

[4] Li, R.; Liu, X.; Qiu, W.; Zhang, M. Anal. Chem. 2016, 88, 7769.

[5] Liu, X.; Zhang,M.; Xiao,T.; Hao,J.; Li, R.; Mao, L. Anal. Chem.
2016, 88, 7238.
(Invited) Polyelectrolyte-Modified Micropipette As a New Platform for In Vivo Analysis
Authors: Yu Ping
Published: February 2020

Ion current rectification (ICR) is a physical phenomenon that ion current in one direction is greater than that in the other one, which can be attributed to the uneven transport of anions and cations across a nanostructure or a biological channel. ICR obtained at solid state nanopore and nanochannels has recently attracted much attention due to their potential application in fluidic logic circuits (i.e., iontronics),4-6 nanoionics and biosensors. So far, ICR has been observed and investigated in various systems, including nanopipette, conical polymer pores, conical glass pores, SiN nanochannel and protein channels. However, almost all of the reported system was focused on nanoscale since it is difficult to observe the ICR when the diameter of the pores was larger than 10 times debye lengths. Few papers have extended the ICR to micrometer scale by introducing more asymmetric factors. However, there is no report on the observation of ICR at micrometer scale for polyelectrolyte brush modified pore, although many papers have been published by modifying polyelectrolyte brush onto the inner surface of the na-nopores.

We interestingly found that micrometer scale ICR can be easily obtained at polyimidazolium brush (PimB) modified pipettes, which provides a new platform for cerebral biological molecular monitoring due to its unique property in easily in operation and relatively robust tip. In this abstract, we would like to introduce our recent research on the in vivo application of polyimidazolium-modified micropipette.
(Invited) Cultivation of Rat Nerve Cells on Biodegradable Sheet Made of Poly (lactic-co-glycolic acid) Thin Film with Micropatterns of Polylysine Containing Laminin Layer
Authors: Nakamura Yuki , Horiuchi Shunpu , Koshinuma Eiki , Imai Satomitsu , Nishioka Yasushiro
Published: February 2020

Cultivation of Rat Nerve Cells on
Biodegradable sheet made of 
Poly
(lactic-co-glycolic acid) thin film with micropatterns of polylysine containing laminin layer

 

Yuki Nakamura, Shunpu Horiuchi, Eiki Koshinuma, Satomitsu Imai, and Yasushiro Nishioka*

Department of Precision Machinery Engineering, College of Science and Technology, Nihon University, Funabashi, Chiba 274-8501, Japan

Tel & Fax: + 81 – 47 – 469 - 6482

*e-mail: nishioka.yasushiro@nihon-u.ac.jp

In regenerative medicine field of nervous system, a technique to fabricate microstructure of neurons on flexible and biodegradable substrates has attracted attention [1]. On the other hand, we have focused on poly lactic-co-glycolic acid (PLGA) as a candidate for the substrate material. The degradation products of PLGA have been reported to be non-cytotoxic and safely removed from host system via normal metabolic activity. Furthermore, it has also been reported that the hydrolysis reaction speed can be modified through controlling the ratio of lactide to glycolide [2]. The characteristics of degradation and removal in vivoare advantageous for regenerative medicine. Neural cell culture on micropatterns of polylysine containing laminin layer has been reported as a technique enabling selective axonal outgrowth of neurons [3]. In this research, biodegradable neuron culture thin films that enable selective axonal outgrowth of neurons were fabricated using PLGA thin films with micro lactic patterns of polylysine with laminin on them. Micro lactic patterns of polylysine with laminin as narrow as 20 μm in width ware defined by using the micromolding in capillaries (MIMIC) technique. Polydimethylsiloxane (PDMS) channel molds used for MIMIC and stencil sheets used for the microstencil method were fabricated by curing a polyether ether ketone mold, which was fabricated by nanoimprinting. The 100µm thick PLGA thin film was fabricated by diluting the PLGA into acetone (5w/w%), packing the solution into a PDMS mold, drawing a vacuum, baking and then cooling it down to cure. The selective growth of neurons on the culture sheet with the micropatterns were confirmed.

References

[1] Y. Inada, et al. "Surgical relief of causalgia with an artificial nerve guide tube: Successful surgical treatment of causalgia (Complex Regional Pain Syndrome Type II) by in situ tissue engineering with a polyglycolic acid-collagen tube." Pain 117.3: 251-258, (2005).

[2] H. K. Makadia, et al. "Poly Lactic-co-Glycolic Acid (PLGA) as Biodegradable Controlled Drug Delivery Carrier" Polymers 2011, 3: 1377-1397, (2011).

[3] L. Kam, et al. "Axonal outgrowth of hippocampal neurons on micro-scale networks of polylysine-conjugated laminin." Biomaterials 22.10: 1049-1054, (2001).
Field-Deployable Wireless Sensor Networks for Mapping Inorganic N-Containing Species in Soil
Authors: Yang Wen , He Jiacheng , Knappenberger Thorsten , Beidaghi Majid , Nadolnyak Denis , Cheng Zhongyang , Chin Bryan Allen , Chen Pengyu
Published: February 2020

Conventional practice of applying fertilizer and irrigation are empirical, often resulting in negative consequences to the environment and human welfare due to the insufficient or excess usage of fertilizer and water. Hence there is a persistent need for the knowledge to assist farmers in determining the quantity and timing of fertilizer and water application to maximize crop yield, minimize waste, and reduce cost. In this study, we aim to develop a highly sensitive radio frequency microfluidic coplanar waveguide array (MCWA) based sensor that can measure N-containing species down to the 3 picomolar by detecting small changes in permittivity of the sample solution upon analyte binding. Based on the single senor unit, we will develop an integrated MCWA sensor array by constructing a series of electrical and microfluidic circuits with each of the sensor units targeting specific analyte species for simultaneous measurement of different N-containing species simultaneously. The MCWA sensor array will be further integrated into a field-deployable soil probe and used to demonstrate the ability of mapping nitrate, ammonium, pH and soil moisture content on the farm using a network of sensor probes spread over a large area. The data from the sensor networks can be used to determine when and how much fertilizer and water should be applied, enabling just-in-time and just-enough geospatial applications of fertilizer and irrigation water, which would contribute to the food-energy-water nexus by increasing crop yield and, at the same time, reducing usage of water and fertilizer.
Label-Free and Highly Sensitive Detection of Buckwheat 16kD Allergenic Protein with Field Effect Transistor (FET) Sensor and Immunochromatography Strip
Authors: Harada Yoshitaka , Tsuna Mika , Hideshima Sho , Saito Mai , Kuroiwa Shigeki , Nakanishi Takuya , Osaka Tetsuya
Published: February 2020

A field effect transistor (FET) sensor detects the change in charge generated by binding of a specific target molecule to the sensor. This simple mechanism allows label-free rapid detection. However, the sensitivity of detection depends on the net charge of the targeted molecule. Buckwheat 2S albumin (BWp16), which is one of the major allergens of buckwheat, constitutes an analyte of buckwheat in food, but its small net charge limits its sensitivity to a FET sensor. We show here that pretreatment of BWp16 with sodium dodecyl sulfate (SDS) increases the net charge of this analyte and increases sensitivity to 1 ng/ml of BWp16 using a FET sensor. Our results suggest a FET sensor is applicable to food safety management. We also developed an immunochromatography assay strip for convenient and rapid detection of BWp16 to a lower limit of 5 ng/ml.

Food Allergen Labeling Regulations in Japan require mandatory labeling of seven allergens in foods at 10 µg/g or more, including buckwheat proteins. Allergenic contamination of food is usually monitored using enzyme-linked-immunosorbent-assay (ELISA), which requires multiple handling steps, an enzyme-labeled secondary antibody, and optical equipment for quantification. In contrast, a FET sensor and an immunochromatography assay strip are potential assay tools without those drawbacks due to their direct sensing mechanism.

In this study, we propose a FET sensor and an immunochromatography assay strip be devised for detection of buckwheat protein. Here we attempt to improve the sensitivity of a FET sensor for buckwheat protein BWp16 by increasing the net charge of its molecules.

BWp16 was determined specifically using a FET sensor. The response of the FET sensor was improved markedly by pretreatment of recombinant BWp16 (rBWp16) with SDS. The response of the FET sensor was correlated positively with the concentration of rBWp16 down to a detection limit below1 ng/ml.

The charge number of BWp16 calculated from its molecular weight (15,106 Da) and isoelectric point (pH 5.25) was small (−3.67/molecule) at the sensing condition of pH 7.4 used with the FET sensor. After the pretreatment with SDS, BWp16 was covered with enough negative charge to increase sensitivity to approximately 10 ng of buckwheat proteins/g of food material.

We devised an immunochromatography assay strip and tested the strip on 40 food samples. The assay strip gave a lower limit of detection below 5ng/ml of BWp16.

SDS pretreatment of BWp16 protein from buckwheat increased its sensitivity to detection with a FET sensor nearly 1000-fold. This simple charge-amplification technique can increase the sensitivity of a FET sensor to a targeted protein that would ordinarily carry a small net charge.

Both a FET sensor and an immunochromatography assay strip achieved highly sensitive and specific detection of buckwheat protein.
Exploration of ISE Sensor Embedded in Garden Weed Block Fabric for Continuous Soil Nitrate Sensing
Authors: Burton Lamar Kendrell , Manickam Pandiaraj , Bhansali Shekhar
Published: February 2020

The objective of this research was to explore novel sensing apparatus for quantifying spatial variation of leached nitrate in soil as well as serve as a method for site specific crop management. There is a need to develop sensors that can more accurately and successfully facilitate site specific soil management for monitoring nutrients and pollutants. The dominantly used sensing methods, both in field and in lab, can require lengthy time when analyzing samples and are costly. Therefore, the objective of this research was to develop a sensor on a water permeable weed barrier fabric used in garden bed soil to allow continuous monitoring of nitrate levels. An electrically conductive fabric material was prepared by applying conductive coatings onto the porous material. Nitrate doped polypyrrole (PPy(NO3
-)) electrodes were used as sensing membranes and proved to have high selectivity towards nitrate ions. The electropolymerization protocols and thickness of the polymer layer were optimized (monomer concentration, deposition time, and scan rate) to synthesize the ion selective electrode (ISE) for nitrate determination. The ISE sensor provides a wide dynamic range from 0.008 mg/L to 849.9 mg/L for nitrate ions in real soil solution samples. Overall, the sensing apparatus proves to successfully detect nitrate ions in soil, sand, and solution.
Solvent-Free Additive Manufacturing of Electrodes for Lithium-Ion Batteries
Authors: Ludwig Brandon , Liu Jin , Wang Yan , Pan Heng
Published: February 2020

Lithium ion battery manufacturing preparation methods have been increasingly studied to make the batteries more cost-effective for large scale platforms such as automotive vehicles. The standard method is to combine an organic solvent with a suitable binder, typically polyvinylidene fluoride (PVDF), to make a slurry. The active material and conductive additive is then mixed in to create the wet electrode material which is then cast onto a current collector. Hazards associated with the organic solvent, such as toxicity and flammability, have resulted in aqueous based slurry preparation, but this also comes with its own set of issues. The change in aqueous slurry rheology properties must be compensated for by adding thickeners and dispersing agents to aid in the wetting capability of the electrode material onto the current collector. Solvent free manufacturing methods, such as pulsed laser and sputtering deposition, have been studied but are not suitable for commercial applications due to prolonged manufacturing times. A team by Missouri S&T and WPI has been recently published a new solvent free manufacturing method by dry spraying the electrode materials onto the current collector directly. Dry sprayed electrodes were found to match, and even exceed, the electrochemical performance of slurry manufactured electrodes. Studies have also shown that the surface energy driven mixing properties of the dry particles allow for a reduction of the binder material to 1 wt% while still maintaining strong mechanical bonding.
Highly Deformable Energy Storage Device with Invereted Endoskeletal Construction
Authors: Park Jongseok , Nam Inho , Park Soomin , Bae Seongjun , Yoo Young Geun , Jerng Sung Eun , Umh Ha Nee , Yi Jongheop
Published: February 2020

According to the Dollo’s law, biological evolution that authorize a species new functions, simultaneously create a mechanical or physiological limitations. This perspective has been also applicable to technological innovation, and energy storage systems have seemed to strictly obey the rules.

Rigid external passive structures have been thought to be essential for the conventional energy storage systems, because packaging with robust wearing maintain the structure of a device and minimize damages that are caused by impacts from external forces and the environment. However, these advantageous characteristics of conventional device packaging results in critical limitations for further innovation of energy storage systems, such as (1) low degree of deformation, (2) scalability of device unit and (3) thermal and pressure controllability.

As the vertebrates blazed a trail in the biological evolution with endoskeleton frame, we propose a novel construction of energy storage device with an analogy to bio-systems. Reverse stacking to fabricate endoskeletal frame would allow energy storage devices deformable and consequently applicable to diverse electronics with generosity.
Electric Double Layer Capacitor Burn-in Procedure Optimization
Authors: Miller John R. , Butler Sue M. , Antloga Mirko , Segel Becca , Savinell Robert F
Published: February 2020

Charge storage in a carbon-electrode electric double layer capacitor (EDLC) occurs primarily via physical processes. Nevertheless, some charge is also stored via chemical processes, at least initially, which is due to active groups usually present on the surface of a fresh carbon electrode. Fundamentally, chemical charge storage processes are not as reversible as physical processes and they fade relatively quickly, usually after tens of hours on charge at elevated temperature or after a few tens of charge-discharge cycles. Importantly, charge storage irreversibility often generates gas that swells the EDLC package and eventually causes it to rupture. Physical processes, on the other hand, are highly reversible and typically provide reliable charge storage for thousands of hours and millions of charge/discharge cycles. The approach used to initially charge the capacitor may help to deactivate functional groups on an electrode’s surface and thus reduce its gas generation.

Electrolyte decomposition can also generate gas. In a carbon-electrode EDLC, decomposition is expected to be concentrated on the sharp points in an electrode where the electric field strength is highest. On a new electrode, the application of high voltage for short times (the “burn-in”) may help erode such points and thus reduce the electric field strength, which in this case is the driving force for gas generation. Then burn-in details could help to reduce gas generation and increase capacitor life.

Our study examines capacitor life as a function of the burn-in procedure. Groups of sealed EDLCs were fabricated in the Case Western Reserve University’s Electrochemical Capacitor Prototyping Laboratory (http://energy.case.edu/CECFF). A two-factor experimental design was used to assign the burn-in conditions for each of the nine groups, the factors being “applied voltage” and “voltage application time”. After burn-in, each group was aged at 65oC, 2.7 V to measure its life. Responses measured during aging included the standard electrical parameters reported for EDLCs and the gas generation rate. EDLC life was analyzed using actual or defined failures, for example, package rupture caused by pressure build-up due to generated gas or 30% fade in capacitance. Weibull life distributions were derived for each group. Results from this study are presented with burn-in optimization details.
(Invited) Rapidly Switching Conjugated Polymers in Redox Active Devices: Supercapacitors As a Case Study
Authors: Reynolds John R
Published: February 2020

When considering pseudocapacitive materials for use in supercapacitors, one must take into account many concerns including their electrochemical potential window, electrolyte compatability, processability, active material morphology, and redox switching speed. In this lecture, we will report on a family of rapidly switching electron-rich polymers, which can be utilized in both organic and aqueous electrolyte systems. To accomplish this, we have designed fully soluble and solution processed 3,4-propylenedioxythiophene/3,4-ethylenedioxythiophene (ProDOTx/EDOTy) copolymers that are electrochemically equivalent to electropolymerized PEDOT without using surfactants or dispersants. We show that these copolymers can be incorporated as active layers in solution processed thin film supercapacitors to demonstrate similar capacitance, stability, and voltage as those that use electrodeposited PEDOT as the active material with the added advantage of the possibility for large scale, and high-throughput processing. A new “water soluble/solvent resistant” route will be described towards developing especially aqueous compatible polymers. Type I supercapacitors will be described which provide exceptional cell voltages (up to 1.6 V) and highly symmetrical charge/discharge behavior, along with promising long-term stability exceeding 50,000 charge/discharge cycles.
An Energy-Power Balancing Act: Balancing the High Capacity and Rate of LiMn2O4-Carbon Nanofoam Cathodes with Solution-Processable Conducting Polymer Anodes
Authors: Sassin Megan B. , Ӧsterholm Anna , Ponder James , Reynolds John R , Long Jeffrey W.
Published: February 2020

As the energy and power demands of current and next-generation devices continually strain the capabilities of present power sources, there is a push to develop materials with high capacity and electrode architectures to facilitate delivering that capacity at high rates. En route to addressing this energy/power issue, we have shown that with the appropriate ultraporous electrode architecture, it is possible to extract full theoretical capacity from LiMn2O4, a nominal battery material, in as little as 18 seconds.[i] While representing a significant advancement at the single-electrode level, the implementation of these advanced electrode materials in practical devices has been hampered by the lack of suitable negative electrode materials with sufficient capacity to balance that of the LiMn2O4. A conducting polymer-based negative electrode would be ideal to pair with the LiMn2O4 in terms rate capability, but issues with solution processability have typically limited these materials to thin film-based electrodes, which will not provide adequate capacity for the LiMn2O4. Recently, the Reynolds group at Georgia Tech has developed synthetic protocols to overcome this roadblock for ProDOT-biEDOT-based polymers.[ii],[iii] This advancement makes it possible to incorporate such conducting polymers as thin, conformal coatings on the interior and exterior surfaces of conductive, porous carbon nanofoam-based electrodes. The nanoscale nature of the coating coupled with the intrinsically fast charge-discharge of the polymer supports high rate and the 3D projection of the conducting polymer via the macroscopically-thick carbon nanofoam provides high area-normalized capacitance to balance that of the LiMn2O4.

[i]. Sassin, M.B., Long, J.W., Greenbaum, S.G., Stallworth, P.E., Mansour, A.N., Hahn, B.P., and Pettigrew, K.A., “Achieving electrochemical capacitor functionality from a traditional battery material: Conformal, nanoscale LiMn2O4 coatings on 3-D, device-ready carbon nanoarchitectures,” J. Mater. Chem. 1, 2431 (2013).

[ii]. Ponder Jr., J. F.; Österholm, A. M.; Reynolds, J. R. “Designing a Soluble PEDOT Analogue without Surfactants or Dispersants,” Macromolecules
49, 2106 (2016).

[iii]. Österholm, A. M.; Ponder Jr., J. F.; Kerszulis, J. A.; Reynolds, J. R., “Solution Processed PEDOT Analogues in Electrochemical Supercapacitors,” ACS Appl. Mater. Interfaces
8, 13492 (2016).