bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influences of Organic Matter Concentrations in Juices for Pathogen Detection Using Phage-Based Biosensors
Authors: Chen I-Hsuan , Zhang Zheye , Du Songtao , Liu Yuzhe , Huang Tung-Shi , Chin Bryan A.
Published: February 2020

Fruit and vegetables are playing an important role of today’s healthy diet. Juices are the liquid extracts from fruit and vegetables, which contain lots of organic matters, such as vitamins, minerals and plant chemicals (phytonutrients). Commercial bottle juices usually contain different percentages of real juices in their juice products. Therefore, the amount of organic matter content in juices are different in various brands of juices.

The foodborne pathogen outbreaks through the consumption of fruit or vegetable juices continue to be reported (CDC, 2016). It indicates that pathogens like Salmonella can be packaged with juices even with current manufacture microbial-inactivation process. According to several studies, the acidity in tomatoes juice and the phyto-chemicals (like chlorophyll) from damage leaves in leafy greens samples can affect the sensitivity of pathogen detection in juices. For example, chlorophyll is one of the substances in leafy green juice that inhibits PCR reaction for pathogen detection. This made the pathogen detection in some juices a difficult task to achieve.

The phage magnetoelastic (ME) biosensors are wireless sensors, whose resonance oscillation and resonance frequency are actuated and detected through magnetic fields. These biosensors have been shown to be highly sensitive and specific in pathogen detection including Salmonella on various food surfaces or liquids (Li et al., 2010). Therefore, in this study, different concentrations of juices from tomatoes and spinach with artificially spiked Salmonella (at the concentration of 104 cfu/ml) was tested by ME biosensors. The influence of pathogen detection capability was then studied by comparing the bacterial capture rates on biosensors. In tomato juice, the results showed that the capture rate of Salmonella can be reached up to 90.68% by using 100 ME biosensors in a tube rocking experiment with 10% tomato juice content. In spinach juice, the capture rate of Salmonella showed similar results as 90.68% in the same 10% juice concentration. However, when the juice concentration of spinach went up to 15% and 20%, the bacterial capture rate slightly decreased. The Salmonella capture rate were shown as 89.82% and 89.065, respectively. The decreasing of capture rate was obvious by using 50 ME sensors for the 15% and 20% spinach juices.

In conclusion, by using 100 phage ME biosensors, the detection platform can detect as high as 89% Salmonella in high juice concentration (15 % and 20%) of both tomato and spinach juice samples. While in the moderate juice concentration zone (5-10%), the ME biosensors show very promising results of detecting 90% Salmonella in both juices.
LSPR Biosensor Based on Au@Ag Core-Shell Nanobipyramids
Authors: Wang Chuanyu , Feng Xiong , Chen Pengyu
Published: February 2020

A highly precise and sensitive immune monitor is required to be biosensors for detecting various bio-marks from human blood. Localized surface plasmon resonance (LSPR) microfluidic optical biosensors allow label-free, high throughput, and real-time detection. Gold and silver nanoparticles have a collective oscillation of free electrons at their surface, where they can resonate with the incident light resulting in changes of wavelength. The higher sensitivity particles have, the more changes in wavelength are shown. In this project, for developing sensitivity of LSPR biosensor, Au@Ag core-shell nanobipyramids has been successfully synthesized with a LSPR peak at about 610 nm and relatively high refractive index sensitivity as 254 nm/RIU, where the ultralow concentration of different cytokines can be detected.
Wireless, Soft, Low-Profile Bioelectronics for Quantitative Diagnostics of Cervical Dystonia
Authors: Kwon Young-Tae , Yeo Woon-Hong
Published: February 2020

Cervical dystonia (CD) is one of the most chronic neurological syndromes, leading patients to repetitive movements and abnormal postures. CD patients suffer substantial decrease in function and quality of life including normal activities of daily living such as cooking, dressing, eating, and driving. The traditional methods for assessment of CD have involved clinical rating scales that is the Toronto Western Spasmodic Torticollis Rating-2 (TWSTRS-2) [1]. However, rating these scales based on visual observation is subject to change upon the level of training and expertise of the clinician, which significantly prevents rapid and accurate identification of CD.

Here, we introduce the first demonstration of a soft skin-like, wireless electronic system, referred to as “SKINTRONICS”, which can quantify 4 types of disorder (torticollis, laterocollis, retrocollis, and anterocollis) and the severity levels of symptoms. The ideas begin with the employment of a highly sensitive accelerometer for accurate recording of total head movements in a soft, ultrathin, conformal wearable platform. The soft-membrane construction allows the biopatch gently and seamlessly mounted on the forehead of a patient with negligible effects on natural head motions while supplying sufficient and reliable digital signals throughout the diagnostic process of CD. To validate the device accuracy, a direct comparison between SKINTRONICS-based assessment and TWSTRS-2 based manual assessment is provided from a clinical study with 5 patients and 5 healthy subjects. Collective results indicate the new class of technology platforms for wireless, diverse, accurate monitoring of abnormal head movements illuminates more effective and safe treatments to patients for improved CD healthcare.

Reference

[1] C. L. Comella et al., Mov. Disord. 2016, 31(4), 563-569.
Paper-Based Lateral Flow Immunoassay for Detection of Biomarkers in Human Fluids
Authors: Curtin Kathrine , Gao Xuefei , Wu Nick
Published: February 2020

Traumatic brain injuries (TBI) patients suffer from neurological deficits and increased risk of neurological disease, so there is a need for accurate, high throughput, and rapid diagnosis. Currently, TBI severity is detected and assessed using neurological examination and CT imaging, which require expensive hospital and doctors office visits. Protein biomarkers have emerged as an objective means to diagnose TBI; however, proteins are typically detected using time consuming and expensive methods such as ELISA and Western blot. In this work, a paper-based lateral flow assay (PLFA) has been developed for a rapid, low-cost means for detecting TBI biomarkers in blood plasma. PLFAs have received increasing attention due to their low cost and ease-of-use. However, these devices suffer from poor sensitivity and interference from the blood plasma matrix. In this study, surface-enhanced Raman scattering (SERS) was applied into a PLFA as the signal transducer to improve sensitivity and overcome biological interference. These advantages are attributed to the optical excitation in the near-infrared biological transparency window and SERS nanostructure design. The PLFA is designed using a plasmonic nanoarray chip and a blood plasma separation unit for highly sensitive TBI biomarker detection.
High-Resolution Multianalyte Biosensor Array for Analysis of Model Organ Systems
Authors: Melow Sara Lynn , Miller Dusty R. , Gizzie Evan A. , Cliffel David E.
Published: February 2020

To determine the effect of toxicants on an organ, a two-fold approach has been taken: an organotypic system (Organ-on-Chip) was used to model the organ and its system, and electrochemical sensors were used to simultaneously measure multiple biomarkers. Current electrochemical analyses using enzymes are limited by their inability to monitor cellular responses when compounds with inherent redox activity are present. Several common chemicals fall into this category including, acetaminophen (APAP), ascorbic acid (AA), and uric acid (UA). In this work, a multianalyte electrochemical biosensor array monitoring the changes of glucose, lactate, glutamate, and acetylcholine in the presence of an electroactive interferent is reported. To mitigate interference, two methods were utilized. Specifically, an osmium-based redox polymer was developed that mediates the electron transfer from an oxidase enzyme to the electrode. By taking advantage of this osmium polymer’s oxidation potential, a lower electrode bias was employed to avoid the bulk oxidation of the interferent, and therefore diminish interference. Another method electropolymerizes m-phenylenediamine on an electrode to make a size exclusion polymer (poly m-phenylenediamine). This polymer prevents larger molecules such as the interferents from reaching the electrode surface and being oxidized, and therefore detected. Both of these sensors maintained excellent sensitivity, demonstrated increased selectivity of the analyte over the interferent, and exhibited longevity. Furthermore, these low-interference tools provided a high-resolution platform for improved analyses in several potential applications including, toxicity studies on model organs (UA is an electroactive metabolite), clinical studies (APAP interferes with glucose meters), and in vivo studies on the brain (AA is an endogenous interferent).
Highly Accurate, Stable Solid-State Microelectrode for an Electrochemical Glucose Sensor
Authors: Lim Hyo-Ryoung , Hillman Nathan Patrick , Kim Yun-Soung , Yeo Woon-Hong
Published: February 2020

Wearable glucose sensors offer the promise of determining necessary insulin doses by analyzing bodily fluids in a noninvasive and continuous manner. Beyond ionotropic and optical methods that are already commercially available, electrochemical sensors can offer a small form factor, low cost, and easy fabrication process, enabled by its two-electrode configuration. Recent works have demonstrated an enhancement of sensing capabilities in the working electrode regarding both enzymatic and non-enzymatic materials. However, a reference electrode that uses the well-known silver/silver chloride (Ag/AgCl), still requires a performance improvement, especially as a form of a low-profile, solid-state configuration. The design of a solid-state electrode has reliability issues, driven in part by the non-use of a liquid chloride-based solution where the existing sensors are stored. Therefore, it is urgently needed to develop a new sensor with higher sensitivity and durability, while covering a broader range of concentrations.

Here, this study reports a newly developed solid-state Ag/AgCl electrode that offers enhanced accuracy and long-term stability in a very small form factor. Ag-deposited Si wafer was annealed to address a delamination issue before anodic chlorination. Fast scan cyclic voltammetry was performed to make conformal AgCl film on the Ag, providing an intimate contact. The correlation between electrochemical variables and stability was analyzed by changing the voltage range and the number of cycles. The initial stage of nucleation, surface morphology and structure of the multilayer were also studied to validate the improved flexibility. The resultant electrode shows high stability in DI water, pH buffer, and saline solution after adopting Nafion as an uppermost membrane. Collectively, this work provides a long-term stable (> 1 week) solid-state reference electrode which can be used for developing a wearable electrochemical glucose sensor.

Figure 1
Towards Closed Loop Control of Cell Production: Analysis of Volatile Organic Profiles in Stem Cells By Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometry
Authors: Heist Christopher A. , Dimandja Jean-Marie D. , Navaei Milad
Published: February 2020

Personalized cell therapies have demonstrated clinical benefits and have shown great promise in solving monogenetic diseases. Despite these documented benefits, commercialization has been limited due to challenges including manufacturing, characterization, quality control, and stability. Previous work has demonstrated the potential of gas chromatography coupled with mass spectrometry to evaluate the volatile organic profiles of cell cultures. However, due to the complexity of the medium and the intensity of the identified peaks, the data has been limited. This work reports on the development of a method to investigate the volatile organic compound (VOC) profiles of stem cells using the increased resolution of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC/TOF MS) for the purpose of stem cell characterization, growth status analysis, and identification of critical quality attributes.

Mesenchymal stem cells (MSCs), from a variety of sources, were cultured and analyzed throughout their growth process. Samples of spent cell culture media were collected during cell passaging and incubated prior to analyzing the headspace above the media. Solid phase microectraction (SPME) was used as to concentrate the VOCs present in the sample headspace. The use of SPME, in conjunction with GCxGC/TOF MS allowed for an expanded understanding of the MSC volatilome and the development of relevant VOC profiles. The effect of growth media, cell source, growth status, and confluency on the chemicals identified in the VOC profiles was studied. Non-targeted analysis revealed more than 100 compounds of potential interest identified through spectral deconvolution and the NIST library of electron impact spectra. The identities of the compounds of interest was validated through the use of analytical standards. Principal component analysis (PCA) was used to reduce dimensionally and visualize variance in the data. Hierarchical clustering analysis was employed to assess relatedness between samples based on their volatile organic profiles. The distinct variations between the volatilomes is able to distinguish different cell sources and growth statuses.

While this work is in its preliminary stage, it lays the foundation for closed loop control of cell manufacturing. The identification of critical quality attributes and their associated VOC profiles, using powerful laboratory equipment is the first step in closing the manufacturing loop. With the newfound knowledge, miniaturized in-line sensors can be developed to allow for complete control of the cell manufacturing process, assuring not only a high quality product, but an efficient manufacturing process as well.

Figure 1
Development of Low Power Micro Preconcentrator (μPC) for Chemical Sensing Applications
Authors: Lotfi Ardalan , Heist Christopher A. , Navaei Milad
Published: February 2020

In recent years, there is a growing need for environmental monitoring systems that can reliably trace contaminants that affect human health and environmental safety. These systems comprise of three main sub-systems: the detector(s), separation columns, and pre-concentrators. The pre-concentrator is the vital part of any systems. The pre-concentrator is used to purify a sample that increases the concentration of the targeted analytes in a range of detection limit of the detector. The ideal pre-concentrator has high adsorption capacity and desorption efficiency [1]. In this work, we have optimized the pre-concentrator’s geometry by maximizing the active surface to volume ratio while improving the desorption efficiency. These optimizations reduce the power consumption, pressure drop across the channel while shortening desorption time.

The fabrication process starts with transfer of mask pattern on to a silicon wafer using photolithography and etching the silicon using Deep Reactive Ion Etching (DRIE) for 360 µm. Next, a double sided polished silicon wafer is used to seal the pre-concentrator by gold eutectic fusion bonding [2]. The last step is to deposit the heater on the backside of the wafer using the lift-off process. The advantage, of DRIE over wet etch, is to have a high aspect ratio structure and low surface roughness level. The low surface roughness is essential for the uniform coating of the adsorbing material. The positive photoresist SPR 220 is used as the soft mask for DRIE process to reduce fabrication steps. The pre-concentrator has pillars with 50 µm in diameter and 25 µm in spacing. Other critical dimensions have been shown in Figure 1(a). The total surface to volume ratio of the pre-concentrator is 58,000 m-1 with the total volume of 13.8 µL. To optimize the geometry of the pre-concentrator, a COMSOL model was developed to calculate the pressure drop across the preconcentrator while evaluating the heater performance. The preconcentrator ramp rate is 47.5 °C/second and the average power consumption is, Figure 1(b). The pressure drop across the pre-concentrator is 1.2 kPa for the air flow of 40 sccm.

Voiculescu, I., M. Zaghloul, and N. Narasimhan, Microfabricated chemical preconcentrators for gas-phase microanalytical detection systems. TrAC Trends in Analytical Chemistry, 2008. 27(4): p. 327-343.

Navaei, M., et al., Micro-Fabrication of All Silicon 3 Meter GC Columns Using Gold Eutectic Fusion Bonding. ECS Journal of Solid State Science and Technology, 2015. 4(10): p. S3011-S3015.

Figure 1
Surface Plasmon Resonance Imaging: An Inexpensive Tool to Study the Water Transport in Thin Film PFSA Ionomers
Authors: Bayani Ahangar Shahab , Bellur Kishan , Medici Ezequiel , Tajiri Kazuya , Allen Jeffrey S , Choi Chang Kyoung
Published: February 2020

The kinetics of water transport in confined thin film Perfluorinated sulfonic-acid (PFSA) ionomers is of vital importance in various applications such as a proton-exchange membrane or catalyst layers in polymer-electrolyte fuel cells. Advanced imaging techniques such as Neutron reflectivity, grazing-incidence x-ray scattering, and atomic force microscopy have been used for studying interfacial water transport in thin film ionomers. The instruments mentioned are considered high-end, expensive, super-resolution microscopes. The need for an expensive microscopic apparatus restricts many laboratories in developing countries from conducting experiments in the field of interfacial sciences such as visualization and in-situ measurement of water transport in thin film PFSA ionomers due to financial constraints, limited infrastructure, and lack of high-end technical support. Following the notion of portable and low-cost technologies, which is a vision of many researchers, we investigated the application of high-speed surface plasmon resonance imaging (SPRi) in the visualization of diffusion transport phenomena of water in thin film (7-250 nm) ionomers (Nafion and 3M). The preliminary results show that the water uptake in the thin film ionomers locally decreases the refractive index of the material, whose changes can be tracked by SPRi. This can provide the 3D map of diffusion during water transports through the thin film ionomer.
Polyaniline Based Ternary Hierarchical Microspheres for Supercapacitor Application
Authors: Jeyaranjan Aadithya , Sakthivel Tamil Selvan , Seal Sudipta
Published: February 2020

With rapid advancements in renewable energy harvesters and flexible electronics, there is a dire need to develop energy storage devices (EEDs) that respond well to these applications. Supercapacitors are a type of EEDs with higher energy and power densities. This, combined with their ultra high cycle life makes them an attractive candidate to be used both as a standalone or coupled with other EEDs.

The active material in supercapacitors can be broadly classified into three types: carbonaceous, conductive polymer, and metal oxides. Each category of materials has its own advantages and drawbacks. It is reasonable to formulate a ternary composite such that the advantage of one material effectively suppresses the drawback of the other. Herein, a ternary hierarchical microsphere (TMS) composed of polyaniline nanofibers, CeO2 nanorods, and reduced graphene is obtained through a simple and highly scalable spray-drying technique.

The synthesized TMS was physiochemically characterized using XRD, FTIR, SEM, XPS, and gas adsorption surface analysis. Electrochemical analysis revealed that the optimized TMS possess high specific capacity (685 F g-1), good rate performance and excellent cycle life (~90% capacitance retention after 6000 cycles). An asymmetric device constructed using the TMS and rGO revealed a high specific energy density (46.3 W h kg-1) at a power density of 850 W kg-1 with a very stable cyclic performance. Thus, we demonstrate a simple yet effective strategy to produce high-performance supercapacitor material, which is highly scalable for industrial-scale production.
Stretchable and Thermally Stable Cellulose Film
Authors: Oh Jee Eun , Park Nae-Man , Choi Sukyung
Published: February 2020

Glass has been widely used as a substrate for display, because of its high transparency and low thermal expansion coefficient. However, glass is not suitable for stretchable displays because it is easily broken and has no ductility. Instead of glass, synthetic polymers can be alternative. However, most synthetic polymers have low transparency and high thermal expansion coefficient. Therefore, as a substitute for glass or synthetic polymer, cellulose nano-fiber was used to make transparent, stretchable and thermally stable film.1

Cellulose is composed of β-(1,4) linked D-glucose unit. Glucose has three hydroxyl groups on surfaces and it can form hydrogen bonds with Nitrogen, Oxygen and Fluorine. Cellulose composed of glucose has many hydroxyl groups. Due to these hydroxyl groups, they are dense with strong hydrogen bonds between the fibers. The cellulose is formed by bundles of many nano-fibers. And it can be used to make a flexible film like paper. However, there is no elasticity because of the intense hydrogen bonding between the molecules.2

In order to impart elasticity to the cellulose, it is necessary to loosen the molecular structure and a network structure. Loosening the molecular structure is possible by modifying the hydroxyl group to another functional group so that the cellulose does not allow hydrogen bonding, or by using a solvent that interrupts and breaks hydrogen bonds between molecules. It is not enough to break hydrogen bonds to give elasticity, so that cross-linking was used to form a network structure.

Prior to cross-linking, cellulose fiber was treated by homogenizer to increase the surface area and reaction efficiency of the cellulose. In this process, cellulose are nano fibrillized. Then, polymeric aldehyde was added as a cross-linking agent to the cellulose nano fiber.

In this work, the properties of the stretchable cellulose will be presented. To investigate thermal stability, DSC and TGA analyzes were performed. Tg was measured by DSC analysis and thermal decomposition temperature of cellulose film was measured by TGA anaylsis. Transparency was measured by the transmittance at various wavelengths. To determine the strength and elongation, tensile strength and strain were also measured.

REFERENCES

(1) Nogi, M; Iwamoto, S; Nakagaito, A; Yano, H. Optically Transparent Nanofiber Paper. 2009, Adv. Mater. 21, 1595–1598

(2) Striegel, A. Theory and applications of DMAc/LiCl in the analysis of polysaccharides. 1997, Carbohydrate Polymers 34, 267-214
Electrolytic Nickel Phosphide with One-Dimensional Pore Channels
Authors: Gwon Yong-Guk , Lee Jong-Won , Shin Heon-Cheol
Published: February 2020

Nickel phosphide has been widely studied in various applications including electrochemical catalyst, electrode for capacitor, electrode for solar cell and electrode for lithium/sodium ion battery. It is synthesized by a variety of methods including hydrothermal/solvothermal/ionothermal method, ball milling, organometallic method, phosphorization, electroplating, etc. Among them, electroplating has many advantages such as relatively simple equipment set up, easy control of electrodeposit’s composition/thickness/structure by changing plating condition, and simplification of process scale-up.

When used as electrochemical functional electrode, porous materials have great kinetic advantages such as decrease in activation overvoltage due to wide surface area and decrease in concentration overvoltage due to open mass transfer path. Well defined porous structure with esp. one-dimensional channels has been usually fabricated using porous template and the process includes at least more than three steps: the application of template, deposition, and removal of template. Apart from the relative complexity of the process, the template might be damaged in the course of experiments and is cost-prohibitive for large scale production.

This work reports nickel phosphide thin films with one-dimensional pore channels, prepared by an electrochemical deposition. In particular, it is synthesized by single step process without porous template. Figure shows typical porous structure of the electrolytic nickel phosphide. Based on plating mechanism and observation of deposit’s growth pattern over time, it is suggested that the porous structure is formed by complex factors such as competitive reaction between deposit formation and gas generation, and island-type deposit growth. It was proved that the porous structure can be well controlled by plating conditions such as current density and pH.

The electrochemical properties of the porous nickel phosphide thin films were investigated as an electrode for functional electrochemical devices (i.e., batteries and capacitors). The redox processes and interfacial resistance along with energy storage characteristics were analyzed through various electrochemical techniques.

In this presentation, the pore formation mechanism of the electrolytic nickel phosphide and the factors governing porous structure will be proposed. In addition, the feasibility of its use as an energy storage materials will be discussed.

Figure 1
Electrolytic Performance of a Cathode-Supported Honeycomb Solid Oxide Electrolysis Cell
Authors: Iwanaga Yoshihiro , Nakajima Hironori , Ito Kohei
Published: February 2020

Power Gas technology has recently been of great attention to convert electric power from renewable energy such as solar and wind powers to fuel for energy storage and transport. Steam electrolysis and co-electrolysis by the Solid Oxide Electrolysis Cell (SOEC) are expected to play an important role. We have developed a honeycomb electrolytic cell for a larger reactive area per unit volume than the conventional planar and tubular cells. Thereby density of fuel production rate can be significantly improved, leading to a development of compact and high performance steam electrolysis systems. In the present study, we assess hydrogen production by steam electrolysis with an SOEC having a porous honeycomb support consisting of Ni-YSZ cathode. The cathode and anode were supplied with H2O/N2/H2 mixture and air, respectively. The cathode was composed of eight flow channels and the anode was of a single channel in the cell. Current-voltage curves were measured, while increased current led to an increase in hydrogen concentration in the sampled gas from the cathode outlet determined by gas chromatography. The experimental results are useful to develop validated numerical models to design practical honeycomb cells.
Selective Conversion to Formic Acid from CO2 By Electrochemical Reduction over Cuxsny Intermetallic Compounds
Authors: Ochiai Hiroya , Gunji Takao , Matsumoto Futoshi
Published: February 2020

Electrochemical reduction of CO2 is of high value because it can reduce the amount of greenhouse gas in the atmosphere. However, since CO2 is a very stable compound due to the strength of C=O bonds, it is extremely hard to turn CO2 into other compounds. In addition, potassium bicarbonate, which is commonly used as electrolyte for electrochemical CO2 reduction, decomposes on most catalysts to form hydrogen (H2) by reduction of proton (H+) at the potentials required to reduce CO2. Therefore, it is important to use a catalyst that prevents the H2 evolution reaction.

Widely studied electrocatalysts for electrochemical CO2 reduction are novel metals, such as Pd, Ag and Au, because they can efficiently reduce the CO2 to CO in high selectivity with low overpotentials. Although non-precious metals such as Zn, Sn and/or Bi are promising as the electrocatalysis for the CO2 reduction, using them require high overpotentials and also result in the formation of H2.

Sn electrode is a viable candidate for CO2 reduction catalyst because it shows relatively high selectivity towards formation of formate. However, Sn demonstrates a function towards H2 evolution reaction. In order to overcome this problem, we have attempted alloying of Sn with Cu which can modify the electronic state and crystal structure of active site of Sn. In this study, we successfully prepared CuxSny intermetallic nanoparticles supported on carbon, which not only significantly improved the electrocatalytic activity of CO2 reduction, but also showed a highly selective conversion to formic acid. The structural difference of surface between Sn and SnCu, which corresponds to the high activity and selectivity towards CO2 reduction reaction, is also discussed in this poster session.
Co-Doping Effects of Iron and Copper into Carbon Nanotubes on Oxygen Reduction Reaction Activity
Authors: Fujibayashi Natsuki , Kato Masaru , Yasuda Satoshi , Yagi Ichizo
Published: February 2020

Polymer electrolyte fuel cells (PEFCs), which can efficiently convert hydrogen into electricity without using fossil fuels, are a promising energy conversion device. In cathodes of PEFCs, oxygen reduction reaction (ORR) occurs and its low reaction rate limits the performance of PEFCs. Therefore, the electrocatalysts for the ORR are necessary. Currently, platinum-based electrocatalysts for the ORR are mainly used because platinum shows the highest electrocatalytic activity in the metals. Since platinum metal is expensive and rare, to make the fuel cells more widely used, there is a need to develop non-platinum-based electrocatalysts based on iron and/or copper with high ORR activity1,2,3,4).

A cytochrome c oxidase (CcO), which is a metalloenzyme and contains iron and copper metal ions, catalyzes the ORR efficiently to produce ATP in mitochondria5) and its activity is higher than that of artificial platinum-based electrocatalysts6). Metalloenzymes are not practical because of their stability and difficulty in isolation and purification.

In this study, we developed iron-copper co-doped carbon electrocatalysts (Fe/Cu/CNT) synthesized from the mixtures of Fe and/or Cu complexes and carbon nanotubes in heat treatment inspired by the CcO’s active center. Synthetic conditions of Fe : Cu metal ratios and heating temperatures were optimized. The ORR activity was evaluated by hydrodynamic voltammetry using a rotating ring disk electrode in 0.05 M sulfuric acid aqueous solution saturated with oxygen. The activity of Fe/Cu/CNT electrocatalyst was compared with two electrocatalysts: iron-doped carbon electrocatalyst (Fe/CNT) and copper-doped carbon electrocatalyst (Cu/CNT). The Fe/Cu/CNT catalyst showed more positive onset potential for the ORR than Fe/CNT and Cu/CNT, indicating that Fe/Cu/CNT is more active and the coexistence of iron and copper in CNTs contributes to the improvement of ORR activity.

References

Kato et al., Chem. Lett., 45, 1213–1215 (2016).

Kato et al., Appl. Energy Mater., 1, 2358–2364 (2018).

Chung et al., Science,
357, 479–484 (2017).

Yasuda et al., Adv. Funct. Mater., 26, 738–744 (2016).

Sakamoto et al., PNAS, 108, 12271–12276 (2011).

Kjaergaard et al., Inorg. Chem. 49, 3567–3572 (2010).
Ternary Nifeco Layered Double Hydroxide Nanosheets As High-Performance Electrocatalysts for Oxygen Evolution Reaction
Authors: Kim Minsoo , Choi Yeji , Hwang Minji , Baeck Sung-Hyeon
Published: February 2020

Electrochemical water oxidation, namely, oxygen evolution reaction (OER), plays an essential role in many technologies such as metal air batteries and water electrolyzer. To date, the state-of-the-art electrocatalysts for OER are mainly based on RuO2 and IrO2. However, their scarcity, high cost, and poor durability limit the large-scale commercialization of these materials. Therefore, it is significant to develop cost-effective, abundant, and stable electrocatalysts. Among various non-precious electrocatalysts, nickel-based layered double hydroxides (LDHs) have attracted lots of attention recently owing to their low cost and high activity for OER. Herein, NiCoFe LDH nanosheets were synthesized by one-step hydrothermal method. Notably, the incorporation of Fe into NiCo LDH can modify the electronic structure of the Ni species, enhancing conductivity and intrinsic catalytic activity for OER. The NiCoFe-LDHs exhibited low overpotential of 294 mV at a current density of 10 mA cm-2, small Tafel slope of 61 mV dec-1, and long-term durability. The outstanding OER performance is mainly attributed to the synergistic effect of the ternary metal system. Consequently, such a synthesis procedure of ternary metal structure could be applied to prepare multi-metal composites for improving electrochemical performance.
In-situ EIS to Investigate Influence of Conductive Additive Addition Rate on Charge Transfer Resistance of Lithium Ion Batteries
Authors: Kojima Fumiya , Hoshi Yoshinao , Shitanda Isao , Itagaki Masayuki
Published: February 2020

In order to develop the lithium ion batteries (LIBs) with higher capacity, it is important to select the suitable compositions of conductive additives for the reduction of the internal resistance of the positive and negative electrodes of LIBs1). In the present study, the influence of the conductive additive addition rate on the internal resistance of the positive electrode was investigated by in-situ EIS 2). This method enables us to measure impedance spectra of the positive electrode, negative electrode and cell of LIBs simultaneously without stopping the measurement of charge/discharge curve.

The positive electrode was fabricated by screen printing. The mixture of the slurry containing LiCoO2 powder, carbon nanowire (CNW), polyvinylidene fluoride and N-methylpyrrolidone were screen-printed on the aluminum foil. In this case, the compositions of CNW were 8 to 30 wt % as the conductive additive. In order to investigate the effect of CNW on electrochemical properties of LIB, an acetylene black (AB) was used as the conductive additives instead of the CNW. The spherical natural graphite on cupper foil was used as the negative electrode and a lithium wire was used as the reference electrode (RE). All measurements were carried out by the three-electrode cell (Toyo system co. ltd.) at room temperature (25℃) in an argon atmosphere.

In the impedance spectrum of the positive electrode measured by the in-situ EIS, three loops were observed on the Nyquist plane. Since the diameter of the loop in the low frequency range was decreased with the increase of the states of charge (SOC), it is considered that this loop is related to the time constant of charge transfer resistance R
ct and electric double layer capacitance 2). The values of R
ct of the positive electrode estimated from the diameter of the loop in the low frequency range were decreased with increasing with the addition rate of the conductive additive. The effect of the addition rate of the conductive additive of the positive electrode on the values of R
ct at each SOC were discussed.

References:

1) F.Y. Su, C. H. You, Y. B. He, W. Lv, W. Cui, F. M. Jin, B. H. Li, Q. H. Yang and F.Y. Kang, J. Mater. Chem., 20, 9644-9650 (2010).

2) M. Itagaki, K. Honda, Y. Hoshi, I. Shitanda, J. Electroanal.
Chem., 737, 78­-84 (2015).
Development of Highly Ion-Conductive Layered Double Hydroxide As Electrolyte for Solid-State Alkaline Fuel Cells
Authors: Taniguchi Yusuke , Yamada Hirohisa , Maeda Kazuki , Sakai Chikako , Katakura Katsumi
Published: February 2020

Layered Double Hydroxides (LDHs) have been studied by many researchers for their interesting properties such as ion exchangers, adsorbents, polymer stabilizer, catalyst, and so on. LDHs are well known as anionic clays include anion species and water molecules in the interlayer which consist of positively charged metal hydroxide layers. It was reported that some types of LDHs prepared by co-precipitated method have high OH- conductivity and high performance as electrolyte for Alkaline Fuel Cells (AFCs)1). On the other hand, it is necessary to develop a newly industrial LDH synthesis method which enables to synthesize the particle and the composition uniformly. Homogeneous precipitation method with Urea is one of the general and promising LDH synthesis method to prepare the uniform LDH, in which pH controlled by hydrolysis of Urea. However only CO3
2- type LDHs are formed by the method. Therefore, we developed the new type synthesis named “decarboxylation method” that enables to synthesize LDH with high crystallinity and selective anion species in inner layer from precursor compounds in one pot.

Prepared samples were measured by ICP and XRD to determine the compositions and structures, respectively, and observed by FE-SEM. Several intercalated anion (CO3
2-, SO4
2-, NO3
-, and Cl-) type M(II) (Zn2+, Co2+, and Ni2+)-Al(III)LDHs were successfully prepared by the decarboxylation method with highly crystallinity and uniform particle size distribution. The ionic conductivities on prepared LDHs were measured by the AC impedance method. Each NO3
- type LDH has remarkably higher ionic conductivity than another type LDHs. The NO3
- type Zn-Al LDH has highest conductivity than another cation type LDHs, and its conductivity is via 16 mS/cm at 80 oC under R.H.80%.

1) Y. Furukawa, K. Tadanaga, A. Hayashi, and M. Tatsumisago, Solid State Ionics,
192, 185-187 (2011).
Two-Stage Electrochemical Synthesis of Copper Nanoparticles on Hydroxyapatite Coatings for Antibacterial Implants
Authors: Ghosh Rashmi , Swart Oliver , Westgate Sabrina , Miller Benjamin , Yates Matthew
Published: February 2020

A two-stage electrochemical synthesis method was developed to deposit copper nanoparticles onto hydroxyapatite-coated titanium. During the first-stage of electrochemical reaction, a submicron thick hydroxyapatite coating was deposited on the titanium cathode followed by electrochemical reduction of copper ions to form copper nanoparticles on the surface of the hydroxyapatite coating. Reaction parameters, including reaction time, deposition current density, copper ion precursor, and concentration were optimized to uniformly deposit nanosized copper particles. The size of the nanoparticles and overall copper content were controlled by adjusting reaction parameters in the second synthesis stage. This method, therefore, offers a route to adjust copper content in electrolytically deposited hydroxyapatite coatings independently from the hydroxyapatite coating reaction. The morphology and composition of the coatings were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The crystalline structure and the surface composition of the material were studied using X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The topography and surface roughness of the coatings were measured using atomic force microscopy (AFM). The quantity of copper ions released in the bacterial growth medium was measured using inductively coupled plasma mass spectrometry (ICP-MS) and was associated with the antimicrobial activity of copper-hydroxyapatite coating. Antibacterial properties of these materials were investigated by culturing Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria) in the presence of the coatings. The antibacterial effect of the copper-hydroxyapatite coatings was enhanced by increasing the copper content. The data further suggested that the antibacterial activity was a result of the elution of copper ions from the coatings. The copper nanoparticles acted as a reservoir for copper ions, providing sustained antibacterial activity. The incorporation of nanosized copper into bioactive hydroxyapatite coatings will offer protection against post-surgical infection of orthopedic and dental implants, to reduce or eliminate the use of prophylactic antibiotics that are known to cause antibiotic-resistant bacteria strains to develop.
A Tale of Two Environments: Being the Only Woman in the Room Doesn’t Have to be a Negative Experience
Authors: Ayers Katherine E.
Published: February 2020

While there is increasing focus on issues of diversity and discrimination in universities, it can be harder to get data from industry. In this talk, I will relate some of my personal experiences and observations over my career in industry, ranging from environments that were not optimal for women to thrive in, to being part of an inclusive environment with strong and supportive mentors. Blatant discrimination has become much less common, but subtle biases can still impede women’s progress, and impact their own sense of self-worth, such that they can hold themselves back as well. Typical examples include women speaking up in meetings and not being acknowledged, then having a male peer say the same thing and be rewarded, or supervisors always looking to a male employee for answers, even when his female peer is an expert. It can be easy to doubt yourself when this happens over and over, and question whether changing jobs will make any difference. As a result, studies show that a much higher percentage of women than men leave STEM fields entirely. However, being willing to take the risk and try again can pay huge dividends.

In many panels I have participated in on women in science, men have also asked how they can help support women. Suggestions include: Be cognizant of how women are being engaged in meetings and work environments and point out unequal treatment. When a female co-worker excels at something or brings up a great idea, be the one to point out that she did. When an opportunity comes up that a female co-worker would be really good at, encourage her to apply. While I have been the only woman at many senior level meetings, I don’t feel isolated when I have peers that value my input and work collaboratively.
An Odyssey through Lithium-Ion Battery Development, the Two Body Problem and Surviving Academia in a Foreign Language
Authors: Schougaard Steen Brian
Published: February 2020

In part due to the two body problem originating from a two Ph.D. couple desiring academic careers, this talk will cover the trials and trepidations related to a (successful) career in a foreign – not English speaking institution. Issues related to funding, career building, laboratory dynamics and the science of developing next generation lithium-ion batteries will be highlighted.

The target audience is young researchers that desire the extra challenge of “making it” in a foreign environment, while remaining in a relationship and staying relatively sane, as well as anyone who is committed to improving diversity in electrochemistry.
Advanced Semiconductor-Electrocatalyst Systems for Photoelectrochemical Hydrogen Production in Microgravity Environments
Authors: Brinkert Katharina
Published: February 2020

Efficient artificial photosynthesis systems follow the concept of the Z-scheme of natural photosynthesis. They are realized as catalyst- and surface-functionalized photovoltaic tandem devices [1,2] enabling photoelectrochemical water oxidation while simultaneously recycling CO2 and generating hydrogen as a solar fuel for storable renewable energy. The successful implementation of an efficient photoelectrochemical (PEC) water splitting cell is not only a highly desirable approach to solving the energy challenge on earth: an effective air revitalization system generating a constant flux of O2 while simultaneously recycling CO2 and providing a sustainable fuel supply is also essential for the International Space Station and long-term space missions, where a regular resupply from earth is not possible.

We demonstrate in a series of drop tower experiments that efficient direct hydrogen production can be realized photoelectrochemically in microgravity environment, providing an alternative route to existing life support technologies for space travel [3]. The photoelectrochemical cell consists of an integrated catalyst-functionalized semiconductor system that generates hydrogen with current densities >15mAcm-2 in the absence of buoyancy. Conditions are described adverting the resulting formation of ion transport blocking froth layers on the photoelectrodes. The current limiting factors were overcome by controlling the micro- and nanotopography of the electrocatalyst using shadow nanosphere lithography [4]. We show that shadow nanosphere lithography can be used as a prosperous tool to obtain desired catalyst nanostructures of high fidelity on a light-absorbing semiconductor surface with tunable optical properties showing significant advantages for photoelectrochemical hydrogen production in microgravity and terrestrial applications [5].

References

[1] Young J. L., Steiner M. A., Döscher H., France R. M., Turner J. A., Deutsch T. G. (2017). “Direct solar-to-hydrogen conversion via inverted metamorphic multi-junction semiconductor architectures”, Nat. Energ.
2. (17028).

[2] Cheng W. H., Richter M. H., May M. M., Ohlmann J., Lackner D., Dimroth F., Hannappel T., Atwater H. A., Lewerenz H. J (2018). “Monolithic Photoelectrochemical Device for 19% Direct Water Splitting”, ACS Energy Lett.
3, 8, 1795-1800.

[3] Brinkert K., Richter M. H., Akay Ö., Liedtke J., Gierisig M., Fountaine K. T., Lewerenz H. J. (2018). Efficient Solar Hydrogen Production in Microgravity Environment. Nat. Commun.
9 (2527).

[4] Patoka P., Giersig M. (2011). “Self-assembly of latex particles for the creation of nanostructures with tunable plasmonic properties”, J. Mater.
Chem.
21, 16783-16796.

[5] Brinkert K., Richter M. H., Akay Ö., Giersig M., Fountaine K. T., Lewerenz H.-J. (2018). “Advancing semiconductor-electrocatalyst systems: application of surface transformation films and nanosphere lithography”, Faraday Discuss. 208, 523-535.
Electrochemical Oxidation of Ammonia on Platinum (100) Nanoparticles at the International Space Station
Authors: Morales Camila
Published: February 2020

Experiments in microgravity environment are used as step forward for increasing the technology readiness level for further long term space missions. This project is geared towards studying the microgravity effects on nanoscale mixing of a diffusion-limited process using electrochemical electrodes in transient conditions at the International Space Station (ISS). Previous experiments conducted by this group in parabolic flights led to a decrease in catalytic current of 20-65% under microgravity conditions. This reduction in catalytic current is believed to occur due to the lack of buoyancy driven mixing at the solution-electrode interface. The objective of this project is to compare the electrochemical oxidation of ammonia in a non gravity environment with the same reaction on Earth. This project will evaluate the ammonia oxidation by performing twelve electrochemical experiments in two ammonia containments with six electrochemical cells. (100) platinum nanoparticles will be used as working electrode to perform cyclic voltammetry and chronoamperometry experiments. The electrochemical cells with an autonomous potentiostat will be send to the ISS inside a 2U Nanoracks module. Our group is developing the required hardware for the experiments to be deployed to the ISS following all strict NASA specifications for flight. Acknowledgment: NASA-EPSCoR-ISS.