bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Portable Nickel-Based Sensor for Hydroxyl Ion
Authors: Jafari Behnaz , Muthuvel Madhivanan , Botte Gerardine G
Published: February 2020

The detection and measurement of hydroxyl ion (OH-) in a solution is important in many applications, namely treatments of natural water and wastewater. The quantification of OH- is normally carried out by titration method, but this method is time consuming and needs several reagents for precise analysis. Additionally, titration method cannot detect low concentration of OH- ions in solution. Alternatively, the hydroxyl ion concentration in any solution could be estimated using pH sensors. Commercial pH probes sense the proton concentration in a solution and the concentration of OH- is determined by use of the following equation.

pH= 14+log [OH-] (1)

However, these pH sensors, which are made of glass electrodes, show acidic and alkaline errors at low and high pH values, respectively [1]. Moreover, these pH meters exhibit a sluggish response, especially in alkaline media. Some reported an optical pH sensing for high pH values, but they were not portable [2].

The focus of this investigation is to develop an electrochemical sensor to detect and measure OH ion in a solution. The presence of hydroxyl ion in a solution will be detected using the electrochemical oxidation of nickel hydroxide to oxyhydroxide (eq. 2). Considering this, a simple, low-cost, easy-to-miniaturize nickel- based electrochemical sensor was designed to examine the possibility of on line electrochemical sensing of OH-. The sensor signal is based on the current produced by the following reaction that happens between the nickel electrode and the hydroxyl ions present in solution;

Ni(OH)2(s)+OH−

⇄
NiOOH(s)+H2O(l)+e−

 
(2)
 

According to this mechanism, the nickel electrode can selectively measure OH- concentration.

The analysis of the oxidation reaction was evaluated by cyclic voltammetry. Furthermore, the oxidation current at different concentrations of OH- obtained by chronoamperometry revealed a linear correlation between oxidation current and concentration in alkali range within a short response time (Figure 1). This finding suggests that the sensor can be used for OH- electrochemical quantification. However, the presence of other species in solution might affect this correlation. For instance, urea, which is widely used in fertilizers and can be found in wastewater, might affect sensor signal. It was observed when urea exists in media, urea oxidation happens and produces current which interferes with hydroxyl ion sensing.

The purpose of this work is finding of mathematical correlation between oxidation current and OH- concentration in the presence of urea.

References

Safavi, A. and H. Abdollahi (1998). "Optical sensor for high pH values." Analytica chimica acta 367(1): 167-173.

Safavi, A. and M. Bagheri (2003). "Novel optical pH sensor for high and low pH values." Sensors and Actuators B: Chemical 90(1): 143-150.

Figure 1
Field-Driven Splitting of Pure Water Based on Deep-Sub-Debye-Length Nanogap Cells
Authors: Wang Yifei , Narayanan S. R. , Wu Wei
Published: February 2020

Hydrogen is a clean and renewable energy resource. Today, more than 90% of the industrially-produced hydrogen comes from steam reforming of natural gas, which are non-renewable and generate greenhouse gases as by-products. Water electrolysis can be a solution for a sustainable energy supply. However, only 4% of the industrial hydrogen production comes from water electrolysis, basically due to the low conversion efficiency. In this paper, we have demonstrated a novel method to achieve efficient pure water splitting based on our deep-sub-Debye-length nanogap cells, with efficiency that can be even better than 1 mol/L NaOH solution. This is the first time that even pure water can be efficiently electrolyzed.

For traditional water electrolysis in macro-system, electric field has been screened into double layer region due to high-concentration electrolyte added to increase water conductivity. The weak electric field inside bulk solution leads to slow ion transport and thus slow reaction rate. In our nanogap cells with pure water, double layer regions of cathode and anode are overlapped so that huge electric field can exist in the entire electrode gap. When the gap is small enough (Figure 1), the migration rate can be even larger than electron-transfer rate (a.k.a. chemical reaction), leading to much higher efficiency than traditional method. The high electric field enhances water ionization and ion transport. From a microscopic perspective, the conductivity of water has been enhanced “equivalently”. We have named this process “virtual breakdown mechanism”.

Figure 2 shows the schematic diagram and fabrication result of our metal-dielectric-metal sandwiched-like nanogap cells, achieved by common photolithography and low DC-bias nitride etching. The gap distance (or nitride thickness) has been down to 37 nm. I-V curve measurements based on our nanogap cells with pure DI water are shown in Figure 3. When gap distance shrank, the electrolysis current became larger due to higher electric field between two electrodes (Figure 3(a)). The threshold voltage around 1.5 V suggests that the energy efficiency is very close to 100% based on a thermoneutral potential of 1.48 V. Figure 3(b) shows currents saturated at fixed voltages when the gap distance became smaller, indicating electron-transfer limited reactions. The electrolysis of pure water and 1 mol/L NaOH solution were compared in Figure 4, both based on our nanogap cells. The different data dispersion indicates the different reaction locations for pure water and NaOH solution (Figure 4(b)). The electrolysis current from pure water was comparable to that from 1 mol/L sodium hydroxide solution, indicates more than 105-fold enhancement of equivalent conductivity of pure water.

Figure 1
Fabrication of Superhydrophobic Aluminum Surfaces By Pyrophosphoric Acid Anodizing and SAM Modification
Authors: Nakajima Daiki , Kikuchi Tatsuya , Natsui Shungo , Suzuki Ryosuke O.
Published: February 2020

Anodizing is one of the most important surface finishing techniques for aluminum and its alloys in various industrial applications. Recently, we reported a novel anodic aluminum oxide formed via anodizing in a new electrolyte, pyrophosphoric acid solution (H4P2O7). Pyrophosphoric acid anodizing leads to the formation of numerous alumina nanofibers measuring less than 10 nm in diameter on the aluminum substrate. In the present investigation, we report the fabrication of a superhydrophobic aluminum surface modified by anodic alumina nanofibers and self-assembled monolayers (SAMs).

High-purity aluminum specimens (4N, 400 µm thick) were ultrasonically degreased and electropolished. The specimens were immersed in a concentrated pyrophosphoric acid solution (74.0 wt%, T = 273–293 K), and then were anodized at a constant voltage of 10 to 75 V to form anodic alumina nanofibers. After anodizing, the specimens were immersed in 5 mM n-alkylphosphonic acid / ethanol solutions (Ti= 293–313 K) for up to 48 h to form SAMs on the anodic alumina nanofibers. Seven types of n-alkylphosphonic acid with different chain lengths were used for SAM-modifications. The surface nanomorphology of the anodized specimens was examined by field emission scanning electron microscopy (FE-SEM). The water contact angles on the specimens were measured by an optical contact angle meter. Distilled water droplets (2–3 µL volume) were placed on the specimens, and the contact angles of the droplets were measured by a charge-coupled device (CCD) camera.

Figure 1 shows the appearances of water droplets on the a) electropolished aluminum surface and b) nanofiber-covered aluminum surface after TDPA-SAM modifications (Ti = 313 K, ti= 24 h). The contact angle greatly increased from approximately 110° to 160° by pyrophosphoric acid anodizing. Because the pyramidal alumina bundles were formed on the aluminum specimen by pyrophosphoric acid anodizing (Figure 2), the water droplet was supported by the top of the pyramidal alumina bundles with TDPA-SAMs, and a large amount of air was trapped in the spaces between the alumina bundles.

As the aluminum specimens were anodized at the low temperature of 273 K, the contact angle increased with anodizing time, and the aluminum surface exhibited a superhydrophobic behavior after anodizing for 4 h. However, the contact angle gradually decreased after that time, and the superhydrophobic angles above 150° no longer appeared after the excess anodizing process. High-aspect-ratio anodic alumina nanofibers then bent under their own weight, and the aluminum surface was completely covered by the long alumina nanofibers. The contact angle decreases by long-term anodizing at low temperature because of the loss of the air trapping space caused by the excess growth of the alumina nanofibers.

Figure 1
Gold Aerogel As a Novel Catalyst for Hydrogen Generation Reaction from a Hydrogen Feedstock Material
Authors: Osborn Justin , Horten Mitchell , Abdel-Fattah Tarek M
Published: February 2020

With the limited supply of fossil fuels becoming more of a concern, there has been an increased focus in finding alternative sources of energy. One source of clean energy is hydrogen gas. Studies have been done examining the generation of hydrogen gas from water, which is an energy intensive process. There has been less effort in generating hydrogen gas from a solid feedstock, such as sodium borohydride. In the presence of water, sodium borohydride releases hydrogen gas slowly. In order to be used as an efficient source of energy, this reaction needs to be catalyzed so the reaction happens at a sufficient rate. One area of catalysis is the noble metals such as gold at the nanoscale. Using metal nanoparticles is a cost-effective way to use these metals as a catalyst, because much less of the bulk precursor is needed. Without a support, the nanoparticles will not be as effective, so aerogels of gold nanoparticles were synthesized and tested to determine its effectiveness as a catalyst [1]. The evolution of hydrogen was measured using a previously described water displacement system [2,3]. The data show an increase in the efficiency of the generation of hydrogen gas with the addition of gold aerogels when compared to the un-catalyzed reaction. The gold aerogel catalyzed reaction has a rate constant of 15.8 L mol-1 hr-1, compared to the un-catalyzed reaction which produced hydrogen at rate of 6.42 L mol-1 hr-1, and was determined to be a second order reaction. This catalyzed process produced 92% more moles of hydrogen gas than the un-catalyzed reaction in the same time period.

References

D. Wen, W. Liu, D. Haubold, C. Zhu, M. Oschatz, M. Holzschuh, A. Wolf, F. Simon, S. Kaskel, and A. Eychmüller, ACS Nano, 2559–2567, Feb. 2016.

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

C. Huff, T. Dushatinski, A. Barzanji, N. Abdel-Fattah, K. Barzanji, and T. Abdel-Fattah, ECS J Solid State, 6, M69-M71 (2017).
Capacitive Deionization Performance of Thermally Surface Modified Activated Carbon Cloth Electrodes
Authors: Agartan Lutfi , Akuzum Bilen , Mathis Tyler , Ergenekon Kurtay , Agar Ertan , Gogotsi Yury , Kumbur E. Caglan
Published: February 2020

Capacitive deionization (CDI) is a low energy desalination technology with long-cycle life, which utilizes high-porosity capacitive electrodes for capturing ions from flowing saline water [1, 2]. Though still suffering from relatively low desalination capacity, one major advantage of CDI technology is its low energy requirement and high rate operation for desalination. In recent years, much effort has been put on improving electrode materials for CDI applications. These studies have mostly focused either on the use of novel electrode materials or on surface modifications (e.g. metal oxide growth, chemical treatment, and thermal treatment) of the existing CDI electrode materials [1, 3, 4].

Although thermal treatment of carbon electrodes for improved charge storage is a well-established approach, the effects of various thermal treatment procedures on the performance of CDI electrodes still remain unexplored. Inherent similarities between the operating principles of supercapacitors and CDI technology might make one to think a similar correlation could be established between thermal treatment and the CDI performance. However, due to major differences in required charge storage mechanisms, a detailed study on various treatment conditions should be conducted to understand which conditions specifically promote better ion adsorption in CDI electrodes.

Motivated by this, the effects of different thermal treatment conditions (i.e., temperature and gases) on salt adsorption performances of the activated carbon cloth (ACC) electrodes were investigated. Major discrepancy between stored charge versus salt adsorption capacity (SAC) was observed for different treatment conditions. To better assess these effects, additional BET and Raman tests on the ACC electrodes were also conducted. Results indicated interesting observations regarding charge storage capacity and SAC for different treatment conditions, which highlights the importance of selecting a suitable thermal treatment condition for enhancing the CDI performance of ACC electrodes.

References

[1] S. Porada, R. Zhao, A. van der Wal, V. Presser and P.M. Biesheuvel, Progress in Materials Science, 2013, 58(8), 1388-1442.

[2] T. J. Welgemoed and C.F. Schutte, Desalination, 2005, 183(1-3), 327-340.

[3] L. G. Zou, G. Morris and D. Qi, Desalination, 2008, 225(1-3), 329-340.

[4] M. E. Suss, S. Porada, X. Sun, P. M. Biesheuvel, J. Yoon and V. Presser, Energy and Environmental Science, 2015, 8(8), 2296-2319.
Evaluation of Non-Adiabatic Thermodynamic Cycles for Electroadsorption Based Deionization
Authors: Zhang Jiankai , Nazemi Mohammadreza , Hatzell Marta C.
Published: February 2020

There is a large push to develop appropriate technologies to treat not only seawater but brackish waters in order to increase the availability of water. Brackish water treatment requires significantly less energy than seawater desalination. To put the energy demand into perspective, the thermodynamic minimum energy require for separation, estimated by the Gibbs free energy of mixing, is between 1-3 kWh per m3 for seawater (35 g/l) and only 0.2-0.9 kWh per m3 for brackish streams (5 g/l). This energy savings quickly compounds at industrial and power generation sites which require over 1 billion m3 of water daily1. Furthermore, brackish waters are not geographically limited, available at both coastal and non-coastal regions.

The treatment of brackish rather than seawater can yield energy savings; however, achieving high energy efficiency during low saline separations processes remains a significant challenge. This has been demonstrated using state of the art desalination technology (reverse osmosis and distillation) that in general thermodynamic efficiencies are low (~5%)2. Furthermore, most common desalination technologies require additional components (heat or pressure exchangers) to recover energy. One emerging technology which aims to improve thermodynamic efficiencies associated with brackish water and simultaneously has the capability to recovery energy is termed capacitive deionization (CDI)3. CDI removes minority ions from a mixture through electroadsorbing the charged constituents when a potential is applied across an electrochemical cell. The ions stored in the electric double layer (EDL) can then be discharged into a brine solution to regenerate active surface area. During this discharge process energy can be recovered. To date, the majority of CDI energy efficiency studies have focused on evaluating systems levels losses associated with the materials, or have evaluated individual processes (charge or discharge) in order to improve performance. While optimizing individual processes provides significant insight into mechanistic losses, evaluating a complete cycle is critical in order to evaluate 2nd law limitations. Here we will evaluate the challenges associated with discharging into a brine solution, and the potential energetic and exegetic savings which can occur through non-adiabatic system operation. 

Maupin, Molly A., et al. Estimated use of water in the United States in 2010. No. 1405. US Geological Survey, 2014.

Demirel, Yaşar. "Thermodynamic analysis of separation systems." Separation science and technology 39, no. 16 (2004): 3897-3942.

Hatzell, Kelsey B., Marta C. Hatzell, Kevin M. Cook, Muhammad Boota, Gabrielle M. Housel, Alexander McBride, E. Caglan Kumbur, and Yury Gogotsi. "Effect of oxidation of carbon material on suspension electrodes for flow electrode capacitive deionization." Environmental science & technology 49, no. 5 (2015): 3040-3047.
Sustainable Autarky of Food-Energy-Water (SAFE-Water)
Authors: Chaitanya V. , Gedara S , Karbakhshi M , Khandan N
Published: February 2020

With nearly 70% of the world population already concentrated in towns and cities, and with continuing trends in population growth and sprawl of metropolitan areas, provision of the basic human needs of food, energy, and water to the inhabitants is seen as a major challenge. Being net consumers of food, energy, and water, current urban infrastructure that continues to rely on obsolete technologies to provide these basic needs is not sustainable. Development of modern infrastructure that can recover and recycle energy and materials within the food-energy-water (FEW) sectors of urban sprawl is now recognized as one of the best options to improve the sustainability of both urban and agricultural systems.

In this paper, we report on algal-based, photosynthetically oxygenated waste-to-energy recovery (POWER®) system for recovering energy, water, and nutrients from urban wastewaters (UWW) that can be utilized in the food production sector. The POWER® system affords waste treatment, net energy production, and recovery of irrigation-quality water and high-purity crop fertilizers. The strain used in the POWER® system is Galdieria sulphuraria, capable of mixotrophic growth under elevated temperatures of 45 - 55oC and low pH of 2 - 4. The POWER® system provides single-step removal of carbon and nutrients (nitrogen, N and phosphates, P) from UWWs through mixotrophic metabolism. The mixotrophic algal system is capable of incorporating all the C, N, and P in UWW into biomass without any energy input and without any loss of C as CO2 as is the case in the current activated sludge systems. In addition, solar energy captured via photosynthesis is also incorporated into the biomass. The energy-rich biomass is then hydrothermally processed in the POWER® system to yield biocrude and biochar with solubilized N and P in concentrated form as byproducts for recovery and use as fertilizers. This paper includes details of development of the POWER® system and results from a pilot scale study conducted under field conditions at an urban wastewater treatment plant.
(Invited) DOE’s Approach to the Energy Water Nexus: New Opportunities and Solutions
Authors: Ivester Robert
Published: February 2020

Energy and water systems are interdependent. Water is used in all phases of energy production and electricity generation. Similarly, energy is required to extract, convey, and deliver water of an appropriate quality for a range of uses. Because of these interdependencies, problems in one system can affect the other. For example, severe drought can limit water availability and constrain output from some power plants. Major storms and other disruptions can knock out power supplies to vital water infrastructure and lead to public health threats. Meanwhile, as population grows and traditional water sources become a less sustainable option, the demand for clean water from nontraditional sources that require more energy to produce are expected to grow.

The U.S. Department of Energy (DOE) has been focusing its science, technology, and analytic capabilities to help the nation move to more resilient energy-water systems. This presentation will address two technology topic areas the Department has been active in: treatment of non-traditional water; and advancing sustainable water utilities. Specifically, DOE has been seeking to resolve the manufacturing challenges that currently prevent the production of clean water from non-traditional sources at a cost competitive with traditional water supplies. DOE has been working with public and private partners to advance technological innovation and address barriers to help water and wastewater treatment systems transition to sustainable water utilities with low energy costs and reduced environmental impacts. These technology topic areas have been pursued as part of a broader Department-wide strategy on the energy-water nexus, stemming from the Department’s foundational 2014 report, “The Water-Energy Nexus: Challenges and Opportunities.”
(Invited) A FDA Staff Perspective on Navigating the Regulatory Landscape and Moving Medical Devices to the Marketplace
Authors: Wachrathit Kelliann
Published: February 2020

The United States Food and Drug Administration (FDA) ensures that patients in the U.S. have access to safe and effective medical devices. The Division of Neurological and Physical Medicine Devices reviews medical devices that interface with the nervous system. This presentation will assist attendees in how to navigate the FDA’s regulatory landscape to successfully bring medical devices to patients.
(Invited) Neuroengineering Overview
Authors: Shemesh Or A , Boyden Edward S
Published: February 2020

Neuroengineering, the field of creating new tools for neuroscience, is an emerging field which includes the invention of technologies to activate and silence electrical activity in the brain, technologies to read out electrical activity from cells in the brain, and tools for mapping the brain. In this talk I will give an overview of technologies that recently emerged from our lab. First, recent optogenetic tools have begun to reach the physical limits of performance. The optogenetic molecules (opsins) Chronos and Chrimson enable activation of distinct neural populations with multiple colors of light, and Jaws is a red shifted inhibitor of neural activity that enables noninvasive neural silencing. Since opsins express all along cell membranes, light focused on one cell body will result in artifactual activation of multiple cells, whose processes are physically touching the neuron of interest. To tackle this problem, we designed a class of somatic opsins that express mainly at the cell body. This, in combination with holographic stimulation enables single cell optogenetics at millisecond temporal resolution.

Activity sensors represent an area of great interest in neuroengineering. The voltage sensor Archon is an archaerhodopsin-based molecule with a high voltage sensitivity and brightness compared to its predecessors. The aforementioned cross talk problem also pertains to sensors: since cell-processes are touching cell bodies, the signal coming from a cell body could in principle originate from nearby cells. To solve this problem we developed a GCaMP6f molecule that is retained in the cell body only, called somaGCaMP6f. This molecule enables low crosstalk physiological imaging in mice and fish.

Lastly, we have developed a technology that greatly facilitates the mapping of the brain. Optical super-resolution techniques are slow and costly, and accordingly do not scale well to large-scale brain circuitry. Instead of improving the resolving power of the microscope, we have found a way to physically expand biological specimens 4x-20x in linear dimension, in an isotropic fashion. This method, which we call expansion microscopy (ExM), enables the mapping of molecules of interest across cells and tissues of extended scale, and thus facilitates the analysis of neural circuits across scales of relevance to understanding brain function.
(Invited) Exploring the Therapeutic Potential of the Endocannabinoid System in Huntington’s Disease
Authors: Cheer Joseph F
Published: February 2020

Huntington’s disease (HD) is an inherited neurodegenerative disorder caused by a polyglutamine (CAG) expansion in the huntingtin gene. Striatal and cortical dysfunction are the hallmark neuropathological features underlying dyskinesia (e.g., chorea) and akinesia at later stages. However, prominent psychiatric symptoms manifest prior to motor dysfunction. We have recently shown in the Q175 mouse model of HD that suppressed motivation – one of the earliest indicators of HD – is associated with compromised dopaminergic signaling and network dynamics in the nucleus accumbens (NAc). We will discuss how pharmacological elevation of endocannabinoid levels in Q175 mice rescues compromised neurobiological markers and ameliorates motivational deficits. Our findings indicate that modulating NAc abnormalities with endocannabinoid-based therapies may be beneficial in treating the prodromal psychiatric deficits of HD.
(Invited) Electrolytic Hydrogen Clearance for Measuring Cerebral Blood Flow
Authors: McCarty Gregory S , Lee Christie A , Walton Lindsay , Sombers Leslie A , Wightman Robert Mark
Published: February 2020

Cerebral blood flow (CBF) controls the delivery of glucose and oxygen to the brain. Blood flow is increased to activated tissue in a phenomenon known as functional hyperemia. Currently, either optical techniques or fMRI is utilized to monitor CBF. This presentation will discuss efforts to use electrolytic hydrogen clearance (EHC) to monitor changes in blood flow in the brain. In EHC hydrogen is generated by an electrode and its clearance monitored by a separate electrode. The rate of clearance can be correlated with physical processes that alter its local concentration, such as diffusion and blood flow. In this work, a microfabricated sensor comprised of a pair of platinum electrodes is utilized for making EHC measurements. Microfabricating the sensor enables small probes to be fabricated, small enough to enable use deep in the brain. This sensor has been characterized ex vivo, demonstrating its operation. More recent efforts have transitioned the sensor in vivo to compare blood flow in the cortex during spreading depolarization and in the striatum during pharmacology.
(Invited) Chemistry of Robust Neural Interfaces
Authors: Takmakov Pavel A
Published: February 2020

Neural implants of the future will be able to acquire and process signals from the nervous system to develop patient- and situation-specific electrical neuromodulation for therapeutic effects. This approach provides fantastic opportunities for dynamic, flexible and personalized treatments. However, realization of this vision requires robust neural interfaces between medical devices and biological tissue. Device failures because of the body’s immune response as well as adverse effects associated with neuromodulation are significant challenges. We are developing in vitro platforms to (1) establish root causes of these issues and (2) provide methods and techniques for rapid development of robust neural implant technologies.

One “side-effect” associated with neuromodulation is irreversible electrochemical reactions that can introduce harmful chemical species during charge injection. The exact nature of these reactions is not well understood. In this work, an in vitro platform for quantification of these reactions that is suitable for use with any specific stimulation protocol has been developed. It was observed that charge injection with imbalanced waveforms leads to decrease in dissolution of platinum. This finding suggests a reduction in irreversible electrochemical reactions, which is contrary to accepted belief.

The second aspect of a robust neural interface is related to current reliance of a new generation of neural implants on microfabrication technology, which does not necessarily yield devices with high tolerance for a biological environment. This calls for extensive R&D work on developing reliable devices. Testing of new implant designs in chronic animal experiments is slow and expensive. To facilitate innovation, reactive accelerated aging (RAA) platform has been developed. RAA is an in vitro system that simulates the biological environment, particularly attack of an implant by the immune system by exposing the device to elevated temperature and hydrogen peroxide for a short duration. RAA was used to discover failure modes for commercial devices that included dissolution of metal, delamination or substantial loss of insulation with further violation of its electrical and barrier properties. RAA was validated by comparing to failures modes that have been observed after chronic implantation in rodent brain.
(Invited) Detection of D-Serine Using an Enzymatic Amperometric Biosensor and Its Localized Detection Using Scanning Electrochemical Microscopy
Authors: Polcari David , Perry Samuel C , Pollegioni Loredano , Geissler Matthias , Mauzeroll Janine
Published: February 2020

D-Serine acts as an endogenous co-agonist for N-methyl-D-aspartate receptors at synapses, making it essential for proper brain development and function. This amino acid has also been linked to several neurodegenerative diseases such as Alzheimer’s disease and dementia. Nevertheless, the primary site and mechanism of D-serine release remains unclear. We recently demonstrated the use of an enzymatic amperometric biosensor for the in vivo quantification of endogenous D-serine release in Xenopus laevis tadpoles. We also investigate the effect of the permselective polymer layer thickness on the biosensor’s response time and selectivity. Finally, scanning electrochemical microscopy (SECM) is then used with the optimized biosensor to measure localized release of D-serine from a model system. This SECM methodology, which provides high spatial and temporal resolution, could be useful to investigate the primary site and mechanism of D-serine release in other biological samples.
(Invited) Plasma Membrane Cholesterol as a Diagnostic
Authors: Li Li , Lu Binyu , Shin Minchul , Kelley Thomas , Burgess James D.
Published: February 2020

Cholesterol is a tightly regulated major structural component of the cell plasma membrane (PM) where it forms stoichiometric complexes with phospholipids and sphingolipids. The amount of cholesterol in the PM exhibits a regulatory role in basal activity of several biomolecular processes by direct binding to proteins and by indirect local environmental effects within the PM that are also coupled to overall cellular cholesterol homeostasis. The term “active cholesterol” refers to PM cholesterol not complexed to lipids, a cholesterol state that arises above a threshold mole fraction of cholesterol in the PM. Active cholesterol level in the PM provides a control mechanism for cellular cholesterol homeostasis through its recognition by membrane bound proteins that activate genes of cholesterol synthesis enzymes. Uptake of LDL, production and release of HDL as well as reversible storage of cholesterol in the cytosol by covalent modification are also regulated and dependent on PM cholesterol (thermodynamic) activity: active cholesterol. A number of human disease states have been found to have associated alterations in PM cholesterol. Thus, an experimental aim of this research group has been the ability to monitor PM cholesterol thermodynamic activity at live cells and tissues without significant perturbation of the native physiological state. In particular, the active cholesterol pool is easily depleted leading to its physiological determination by traditional assays being out of reach. Our approach is to measure the rate of cholesterol diffusion from the PM at the point-of-contact of a microelectrode. The enzyme-modified electrode consumes the sparingly-soluble aqueous-cholesterol adjacent to the PM thus perturbing the equilibrium between aqueous- and PM-cholesterol resulting in diffusion of cholesterol from the PM only at the site of electrode contact. That is, the enzyme modified electrode creates a demand for cholesterol at the site of contact and measures the diffusional response. The rate of cholesterol diffusion (micro-extraction) is related to the thermodynamic activity of cholesterol (which is controlled by the active cholesterol concentration) in the PM by classic kinetic theory. The transition state is cholesterol that has exited the PM and has not yet formed a solvent cage. Through Collaboration with Minchul Shin at Georgia Southern University, ongoing work for human cholesterol sensing is using nano/micro manufacturing to produce sensor chips containing well-spaced regions of SiO2 that are circular with a 10-20 µm diameter for attachment of oxidase. This general approach to noninvasive human sensing could serve as a platform for screening children for hypercholesterolemia and for other markers such as glucose.
Characterization of Sintered Lithium-Ion Battery Electrodes
Authors: Robinson Pierce , Koenig Gary
Published: February 2020

Conventional lithium-ion batteries often have a low volume fraction of active material and a low electrode thickness in order to achieve high cycling rates and mechanical properties needed for electrode processing and cell assembly, but this limits the energy density that can be achieved at the cell level. Close-packed sintered electrodes are an alternative architecture that can achieve a high fraction of active material, but require careful design and understanding of the microstructure of the film. Sintered electrodes were fabricated using hydraulic pressing of active material powders into pellets, followed by sintering and assembly into cells. The performance of these electrodes has been tested through electrochemical cycling with promising initial results. The conductivities of the electrodes were examined and related to the battery polarization in coin cells. This study examines the relationship between electrode microstructure and electrochemical properties in sintered electrodes, while varying key parameters such as tortuosity, sintering conditions, thickness, active material chemistry, and particle size.
NiCo2O4
@Ni As the New Air Electrode Material to Enhance the Performance in Rechargeable Zinc–Air Batteries Application
Authors: Qiao Jinli , Nie Qi
Published: February 2020

In recent years, pollution and shortage of fossil fuels in the environment have made it a popular trend to develop portable electronic devices, use renewable energy and grid-scale energy storage in electric vehicles. Batteries have long been recognized for their capacity to convert and store electrical energy efficiently. In the present work, rechargeable metal−air batteries such as Zn-air batteries could be idealized energy storage devices which have attracted much attention compared with lithium-ion batteries ,because Zn-air batteries possess high power density, economic viability and high safety.[1-2]
Active and durable electrocatalysts on the cathode side are required to catalyse oxygen reduction reaction during discharge and oxygen evolution reaction during charge for rechargeable batteries.[3]

The aim of experiment is to synthesize mesoporous NiCo2O4@Ni. All the reagents used in this experiment were analytical grade and were used without further purification. In a typical synthetic procedure, a piece of nickel foam was thoroughly cleaned with 3 M HCl solution in an ultrasound bath for 30 minutes in order to remove the NiO layer on the surface and then washed by deionized water and absolute ethanol. Put it into watch glasses for drying. C4H6NiO4 • 4H2O (0.3 g), Co(NO3)2 • 6H2O (0.6 g) and hexamethylenetetramine (HMT, 0.8 g) were dissolved into a mixed solution of deionized water (30 mL) and ethanol (20 mL) under vigorous magnetic stirring. After stirring for 30 min, the as-obtained solution was transferred into a 60 mL polytetra-fluoroethylene (PTFE) (Teflon)-lined autoclave, and then use the cleaned nickel foam which has been worked to immerse into the reaction solution. The autoclave was sealed and maintained at 95 °C for 8 hours in an electric oven. After cooling to room temperature, the products on the nickel foam were washed with deionized water and absolute ethanol for several times respectively and then dried the nickel foam at 60°C overnight. Afterward, the samples were annealed at 250° C, 350° C and 450° C for 1h at a ramping rate of 1°C min-1 to transform into NiCo2O4@Ni-250, NiCo2O4@Ni-350 and NiCo2O4@Ni-450.

NiCo2O4@Ni-350 is a new air electrode material which has been synthesized via a hydrothermal method. This nanomaterial displays good bifunctional ORR/OER activity, cyclic stability, low cost and high energy density in the discharge and charge process. Further studies are ongoing to improve the Zn-Air batteries performance by manipulating the structure.

References

[1] D.U. Lee, J.Y. Choi, K. Feng, H.W. Park, Z.W. Chen, Advanced Energy Materials, 4,1301389(2014).

[2] P.C. Pei, Z. Ma, K.L. Wang, X.Z. Wang, M.C.Song, H.C.Xu, Journal Of Power Sources, 249,3(2014)

[3] V. Neburchilov, H.J. Wang, J.J. Martin, W. Qu, J. Power Sources 195,1271 (2010).
(Invited) New Viable Nanomaterials for Ultrafast Batteries and Asymmetric Supercapacitors
Authors: Naoi Katsuhiko
Published: February 2020

Hybrid/Asymmetric EESs based on the mechanism of “faradaic” or “extrinsic/intrinsic pseudocapacitive” can certainly overcome the EDLCs’ energy density limitation [3,4,5]. In light of this, K&W/TUAT group developed an original material processing technology called “ultracentrifugation (UC)” that allows to prepare (mass produce) a variety of ultrafast (Li-insertion) nanomaterials capable of 3-7 fold enhancement in energy density. It’ s been demonstrated that UC process typically under 75,000g (with subsequent heat or hydrothermal treatment) gives spinel Li4Ti5O12 nanocrystal as nanosheet/nanobook that are grown on the surface of carbon matrices like MWCNT, SGCNT [1,2,4]. The “nanohybrid capacitor(NHC)” configured as uc-LTO/LiBF4[PC] /AC tripled the energy density of conventional EDLCs [1,3,4]. Nippon Chemi-con Corp. is now eagerly developing commercial NHC device in order to place them in the market. Other uc-derived nanomaterials will be introduced together with their effective utilization in the 2nd gen. “NanoHybrid Capacitor” (JST NexTEP project, 2013-2018) and 3rd gen. “SuperRedox Capacitor” (JST A-step project, 2016-2021). As for LTO alternative anodes, b-axis (ultrashort) controlled 5-nm uc-TiO2(B) [6] and electrochemically activated uc-Li3VO4 [7], both showed ultrafast (300C) charge-storage performances. As cathode, nano-structured 2-cores/1-shell of [uc-LiFePO4(LFP)/amorphous/defective LFP/graphitic carbon] shows ultrafast and symmetric discharge and charge performance (300-480C) [8]. Finally, the author will present a perspective of the future supercapacitors’ market in the world.

References

[1] K. Naoi, Fuel Cells, 10, 825 (2010).

[2] K. Hata and S. Iijima et al, Science, 306, 1362 (2004).

[3] K. Naoi et al, Energy

& Environmental Science, 5, 9363 (2012).

[4] K. Naoi et al, Accounts

Chemical

Research, 46,1075(2013).

[5] M. Salanne, K. Naoi, and P. Simon et al, Nature Energy, 1, 16070 (2016).

[6] E. Iwama and K. Naoi et al, ACS Nano, 10(5), 5398, (2016).

[7] K. Naoi et al, Advanced Materials, 28, 6751 (2016).

[8] K. Naoi et al, Energy & Environmental Science, 9,2143 (2016).
(Invited) In Situ Monitoring of Mechanical Properties Via Multi-Length Scale Approach
Authors: Jäckel Nicolas , Gogotsi Yury , Levi Mikhael D. , Aurbach Doron , Presser Volker
Published: February 2020

The in situ multi-length scale methodology creates new insights for the correlation of structural changes on the (sub-) nanometer scale with the resulting behavior of a bulk electrode in batteries and supercapacitors. The primary atomic-scale effect of Li-ion intercalation-induced changes of the unit cell volume or ion insertion between layered materials generates mechanical stress. [1, 2] This electrochemical process occurs during charging and discharging, meaning insertion and extraction of ions, generating a variety of secondary multiscale dimensional changes and causes a deterioration in the energy storage performance stability. [3]

A complementary approach to monitor structural changes with in situ x-ray diffraction (XRD), microscopic changes with in situ atomic force microscopy (AFM), mesoscopic changes with hydrodynamic spectroscopy via electrical quartz microbalance measurements with dissipation monitoring (EQCM-D) and macroscopic changes with electrical dilatometry (eD) was chosen. [1, 4] We combined the results of this in situ measurement techniques. By this way, it is possible to correlate structural changes on the (sub-) nanometer scale with the resulting behavior of a bulk electrode in batteries and supercapacitors. We have proved the particularly understanding of ion intercalation into two-dimensional materials and a better understanding of the related mechanisms in composite electrodes.

1. Jäckel, N., et al., Electrochemical in Situ Tracking of Volumetric Changes in Two-Dimensional Metal Carbides (MXenes) in Ionic Liquids. ACS Applied Materials & Interfaces, 2016. 8(47): p. 32089-32093.

2. Thackeray, M., Lithium-ion batteries: An unexpected conductor. Nature Materials, 2002. 1(2): p. 81-82.

3. Shpigel, N., et al., Non-Invasive In Situ Dynamic Monitoring of Elastic Properties of Composite Battery Electrodes by EQCM-D. Angewandte Chemie International Edition, 2015. 54(42): p. 12353-12356.

4. Shpigel, N., et al., In situ hydrodynamic spectroscopy for structure characterization of porous energy storage electrodes. Nature Materials, 2016. 15(5): p. 570-575.

Figure 1: Different characteristic length scales for certain in situ measurement techniques.

Figure 1
Nitrogen-Doped Carbon Catalyst for the Electrochemical Reduction of Carbon Dioxide
Authors: LIU Jianfeng , Zhang Zhenhai
Published: February 2020

Carbon dioxide is known as the main greenhouse gas, which is enormous produced during human activities. The electrochemical reduction of carbon dioxide not only reduce the amount of CO2, also produce CO2 to CO, the intermediate for the production of some chemical and fuels. However, the electrochemical reduction process for CO2 is inhibited due to the lack of a suitable catalyst with high energy efficiency and high conversion rate.[1] The catalysts with the precious metal catalysts, such as Ag, Au, and Zn, Ni received high energy efficiency during carbon monoxide production. Some researchers utilize these metal catalysts for CO2 reduction process, and received the corresponding results.[2] However, the cost of the precious metal is another urgent issue.

In my prior work, the nitrogen-doped graphene is applied as a non-metal catalyst for oxygen reduction reaction process in aidic and alkaline media, finally exhibit high current density and mass activity.[3,4] In this work, we also heat treated carbon with the goal of doping nitrogen into carbon, and apply this nitrogen-doped carbon as catalyst for CO2 electrochemical reduction process. The nitrogen-doped carbon catalyst exhibit higher current density and higher overpotential than the corresponding carbon, that is to say, the doped nitrogen atoms play an important role for the reduction process.

[1] C. E.Tornow, M. R. Thorson, S.Ma, A. A. Gewirth, P. J. Kenis, Journal of the American Chemical Society, 134(48), 19520, (2012).

[2] A. Salehikhojin, H. R. M. Jhong, B. A. Rosen, W. Zhu, S. Ma, P. J. A. Kenis, J.phys.chem.c, 117(4), 1627, (2017).

[3] J. Liu, D. Takeshi, D. Orejon, K. Sasaki, S. M. Lyth, Journal of The Electrochemical Society, 161(4), F544, (2014).

[4] J Liu, K Sasaki, SM Lyth, ECS Transactions 58 (1), 1751 (2013)
Wet Chemistry for Large Cage Metallofullerene Isolation
Authors: Stevenson Steven , Thompson Hannah R.
Published: February 2020

There is little information regarding the chemical reactivity of trimetallic nitride fullerenes in carbon cages above C80 (e.g., M3N@C82-112). Several reasons include the (1) low production yield from the electric-arc plasma reactor and (2) their presence in a complex mixture of often more than 50 types of species. This presentation addresses the latter hurdle for which we are presenting a novel separation strategy that uses only liquids. We have replaced all solid supports, such as aminosilica, with amino alcohols, which has the advantage of NH2 groups for attachment to fullerene cages and an OH group at the other end for an ease of transfer to an aqueous layer. Unreacted metallofullerenes would remain in the organic phase. In this strategy, desired metallofullerenes could be retained whereas empty-cage fullerene and highly reactive metallofullerenes would be, upon reaction, transferred to the water phase for a chemical separation. We have evaluated an array of different solvents and varied amino alcohols, their amounts and their reaction time to obtain optimal selectivity for M3N@C88 endohedrals. For improved selectivity, we can combine enriched samples of higher endohedrals obtained from this 1st stage (amino alcohol) with a 2nd stage (Lewis acids) to obtain isolated M3N@C88 (90% purity). For experiments requiring a higher purity sample, a quick HPLC pass allows the isolation of Gd3N@C88 in 98+% purity.
Pourbaix Diagrams As a Root for the Simulation of Polarization Curves for Corroding Metal Surfaces
Authors: Perry Samuel C , Mauzeroll Janine
Published: February 2020

The corrosion of metals is a much researched area thanks to its importance in the development of materials for a wide range of applications. A common means of experimental analysis of the corrosion rate of a specific metal is the recording of polarization curves and subsequent Tafel analysis. Comparison of such data with simulated examples provides useful validation of experimental data, as well as a better understanding of the specific reactions occurring at the metal surface. Many existing models require knowledge of parameters such as the exchange current density and Tafel slope, which requires the experiment to be conducted before the model is run. Here, we propose a model based around the Pourbaix diagram, where input parameters are either simply calculated from reaction schemes, or are easily accessible from thermodynamic data tables.

In this work we use Pourbaix diagrams as a means for simulating a polarization curve at a corroding iron surface. Pourbaix diagrams show the boundaries between the changing thermodynamically stable species at a metal surface in an aqueous environment as a function of the applied potential and pH. The position of these boundaries can therefore be used to model the onset of the corresponding oxidation and reduction reactions by combining the equation of the appropriate boundary line with Butler-Volmer kinetics. At the same time, the change in pH local to the metal surface is monitored by simulating the flux of protons generated during the oxidation process, and the impact of this on the corrosion potentials and rate is taken into account. This is of great importance as the corrosion rate and the corrosion product varies according to the pH at the metal surface.

In this way, we show a simple means for the simple simulation of a polarisation curve at an iron surface, which is in excellent agreement with an experimentally recorded curve under the same conditions. This same method can then be applied to more complex metal alloys such as stainless steels, by combining the Pourbaix diagrams for the appropriate alloy components. This allows the model to be used as a standalone analytical tool for the prediction of corrosion behaviour of novel alloys before they are developed, as well as for the validation of experimental data obtained from existing samples.

Figure 1: Pourbaix diagram for the iron - water system

Figure 1