bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the Electrochemical Performance of High Power and Energy Aqueous Rechargeable Zn/MnO2 Batteries
Authors: Poyraz Altug Suleyman
Published: February 2020

Rechargeable aqueous zinc ion batteries (ZIBs) have many advantages such as high abundance and low cost of Zn and safer battery chemistry in aqueous ZnSO4 electrolytes. Tunnel and layer structured manganese dioxides (MnO2) are promising cathodes for ZIBs due to their high theoretical capacity (~300mAh/g), voltage (~1.4 V vs. Zn/Zn2+) and large tunnel openings facilitating fast Zn2+ insertion/removal. However, MnO2 suffers from severe capacity fading as the battery is put through extended charge-discharge cycles due to the cathode dissolution and formation of electrochemically inactive phases such as ZnMn2O4 and ZnMn3O7·xH2O.In order to address the shortcomings of MnO2 cathodes and improve their electrochemical performances in ZIB, we have investigated the effects of (1) electrolyte concentration and type, (2) sol-gel surface coating of the cathodes, and (3) the tunnel sizes of MnO2. Here, we report that electrochemical performance of 0.46 nm x 0.46 nm tunnel sized α-MnO2 can significantly be enhanced at low concentration (≤0.5 M) ZnSO4 and ZnTFSI electrolytes. Low concentration ZnSO4 and ZnTFSI electrolytes demonstrated higher discharge capacities and capacity retentions at long battery cycling tests. At 0.1 M ZnSO4, α-MnO2 delivered 62 and 103 mAh/g capacities with 0.3 A/g rate at the 1st and 100th cycles, respectively (166% retention). At a higher charge/discharge rate of 0.9 A/g, α-MnO2 delivered 85mAh/g capacity at the 500th cycle, where the retention was 167% with respect to the 1st cycle. On the other hand, the capacity retentions were below 30% and discharge capacities were below 60 mAh/g after 100 cycles in high concentration electrolytes. Detailed characterization of spent electrodes showed that low concentration electrolytes mitigate the formation of the impurity phases and suppresses cathode dissolution. Additionally, further improvements in the ZIB performance of MnO2 have been achieved in 0.5 M ZnTFSI electrolytes and MnO2 materials with larger tunnel and layer openings.
Anaerobic Treatment of High Fat Content Wastewater in Microbial Electrochemical Cells
Authors: Popat Sudeep , Xie Ao
Published: February 2020

Microbial electrochemical cells (MECs) are devices in which anaerobic treatment of wastewater can occur in the anode chamber, where anode-respiring bacteria oxidize fatty acids produced from fermentation of waste organics to produce an electrical current. MECs are best suited for high-strength industrial wastewater streams, rather than dilute domestic wastewater streams. We have evaluated the possibility of using MECs for treatment of rendering wastewater, which contains high concentrations of fats (and often also proteins). We first conducted biochemical methane potential (BMP) tests to determine the anaerobic biodegradability of rendering wastewater (COD concentrations of ~7000 mg/L), and to determine optimum organic loading rate (relative to biomass concentration). Using the optimum conditions, we then conducted batch MEC studies to determine maximum current densities that could be produced, as well as the COD removal and conversion efficiencies. Maximum current densities of up to 2.5 A/m2 were produced, while COD conversion to electrical current ranged between 70-80%. Our studies indicate that MECs could become suitable for treatment of high fat content wastewater streams.
Leveraging Nanoscale Phenomena in Electrochemically Dealloyed Nanoporous Gold for Gas Sensing
Authors: Wong Timothy , Newman Roger C.
Published: February 2020

As the chemical environment grows more complex in research and industrial settings, there is an increasing demand for robust and flexible sensors for volatile chemicals. Nanomaterials are a promising new frontier of investigation to tackle these challenges. While the praise of nanosensors often focuses on their high surface area, the ability to exploit nanoscale phenomena for transduction opens up exciting possibilities. The drawback of many nanoscale sensing platforms is challenging fabrication. In this work, we utilize a simple but highly controllable electrochemical method to form nanoporous gold, as well as its Pt alloy derivatives with even finer pore sizes. Rather than applying nanoporous gold to a conventional aqueous electrochemical sensor, we leveraged unique nanoscale phenomena to apply nanoporous gold as the first reported multi-variate gas sensor.

Electronic conduction in nanoporous networks is fundamentally different from bulk metallic conduction. While conduction in bulk systems is limited by phonon scattering, electrons in nanoporous gold scatter off surfaces before they encounter a phonon. This behavior is strongly modulated by chemicals adsorbed to the surface. Since the quantity adsorbed on the surface depends on the equilibrium with the gas concentration, one can use changes in resistance to sense the gas concentration. We have demonstrated this detection principle for several model volatile chemicals (water, acetone, ethanol).

By monitoring both the in phase and out of phase electrical response, we also observed changes in the capacitive behavior. These capacitive changes were driven by pore filling. Condensed liquid within the pores allows for the formation of an electric double layer. This condensation occurs far below the typical saturation pressure due to the confined curvature of nanopores. By combining such data with changes in electrical resistance, we demonstrate robust and selective gas sensing.

In this work we demonstrate that a single multi-variate nanoporous gold gas sensor can detect multiple compounds (water, acetone, ethanol). We also measure sensor characteristics: sensitivity, delay, and hysteresis. These results show the potential for the application of nanoporous gold as a versatile and selective volatile chemical sensor.

Figure 1
Solid-Contact Ion-Selective Electrodes Comprising Hydrophobic Redox Buffers
Authors: Rousseau Celeste R , Buhlmann Philippe
Published: February 2020

A calibration-free measurement with an ionophore-doped polymeric membrane ion-selective electrode requires that the phase boundary potential at the sample/sensing membrane interface is controlled by the activity of the target ion in the sample of interest, while all other phase boundary potentials in the electrochemical cell are constant and long term stable. Historically, the biggest difficulty lies in establishing a reproducible phase boundary potential at the interface of the sensing membrane and the underlying electron conductor. Efforts over several decades to use conducting polymers as an interlayer between the ion-selective membrane and an underlying electron conductor, such as a metal or carbon, have had limited success. While the performance of such devices has been much improved in terms of light sensitivity and hydrophobicity of the conducting polymer layer, devices that can be considered calibration-free are still elusive. To that end, hydrophobic redox buffers have been introduced as an alternative to conducting polymers. While hydrophilic redox buffers play central roles in all living organisms, control many geological and environmental processes, and are often utilized in the laboratory, buffering of redox potentials in hydrophobic media is a topic that has in the past been overlooked. This presentation will address principles for the use of hydrophobic redox buffers, and it will discuss recent examples of hydrophobic redox buffers suitable for the fabrication of ion-selective electrode membranes that are calibration-free.

(1) Redox Buffer Capacity of Ion-Selective Electrode Solid Contacts Doped with Organometallic Complexes, Zhen, X. V.; Rousseau, C. R.; Buhlmann, P. Anal. Chem.,
2018, 90, 11000-11007.

(2) Paper-Based All-Solid-State Ion-Sensing Platform with a Solid Contact Comprising Colloid-Imprinted Mesoporous Carbon and a Redox Buffer, Hu, J.; Zhao, W.; Bühlmann, P.; Stein, A., ACS Appl. Nano Mat.
2018, 1, 293–301.
(Invited) Portable Iron Screening System for Point-of-Care Iron Status Determination
Authors: Arugula Mary , Pinchon Erica , Haithcock Dustin , Bhatt Ketan , Pandian Prabhakar , Pant Kapil
Published: February 2020

Women undergoing basic military training are particularly susceptible to iron deficiency (ID) and iron deficiency anemia (IDA). Symptoms of iron depletion, such as fatigue and reduced cognitive ability, have raised concerns over the effect of unchecked iron deficiencies on United States military preparedness. Therefore, screening recruits for iron status is vital to the health and safety of the people serving our country. Currently, there exists no robust point-of-care method for rapid iron status determination. Here we present a point-of-care iron status determination system, which can rapidly determine iron status based on a panel of markers. The methodology used for determination of iron status is based on immunosensor measurement from human plasma samples by means of impedance analysis. Antibodies respective to soluble transferrin receptor (sTfR), transferrin, and ferritin were linked to the electrode surface using dithiobis succinimidyl propionate (DSP). The transferrin sensor exhibited linear calibration curve for concentrations ranging from 0.5-5.5 mg/mL transferrin protein. With given linearity, the transferrin levels detected in all tested plasma samples were found to be 1.5 - 1.7 mg/mL respectively, that fall within expected normal reference ranges. The transferrin clinical threshold for ID and IDA is >4.0mg/mL. The sTfR sensor was capable of measuring sTfR in PBS between 0.1 and 3.2 mg/L. The clinical threshold for ID and IDA is >3.6 mg/L of sTfR. The sTfR levels detected in all tested plasma samples were found to be 1.8 - 4.4mg/L respectively. The concentrations measured by the developed sensors were in excellent agreement with ELISA. Further improvements will be performed with screen printed array gold electrodes for multiplex sensing of all the biomarkers. These sensors will be integrated into a cartridge, and along with electronic hardware and software for interpreting the results, will be a fully functional system for the rapid determination of ID and IDA.
Effect of the Number of ME Elements on Capture Rate of a Small Number of Pathogens in the Prototype of Phage Filter with a Comparison of Rocking Method
Authors: Du Songtao , Liu Yuzhe , Chen I-Hsuan , MacLachlan Alana , Huang Tung-Shi , Chin Bryan A.
Published: February 2020

Foodborne illness is a frequent public health problem because there is potential for food to be contaminated by pathogens at any point from farms to the dinner tables. Each year, the cost of foodborne illness in the U.S. is enormous. The direct and indirect costs associated with foodborne illness are more than $15.6 billion per year. For rapid detection of foodborne pathogens, Magnetoelastic (ME) biosensor is one of the methods to detect pathogens on food surface and liquids. As the multistate outbreak caused by Romaine lettuce contamination in 2018, current microbiological testing methods, required by Food and Drug Administration (FDA)’s Bacteriological Analytical Manual (BAM), shows shortages. According to the requirement, a new method, named 3D bio-molecular filter, was developed to capture, concentrate, and isolate a small number of pathogens in large volume of liquid streams. The filter consists of ME filter elements, a pair of permanent magnetic plates, and testing glass tube. ME filter elements are magnetically held and arrayed in a testing glass tube. The target pathogen in a large volume of liquid will be capture by ME filter elements when a large volume of liquid passes through. A prototype of a compact edition was developed in this paper to support this method. The device consists of high magnetic plates, which provide uniform high magnetic force to hold ME filter elements, and a square glass tube to pass through the liquid with target pathogen. In this work, E2 phage is immobilized on ME filter elements to capture, concentrate, and isolate Salmonella
Typhimurium in processing water. Two different methods to capture Salmonella, rocking method and 3D biomolecular filter method, are compared. The capture rate and effects of the number of ME filter elements on Salmonella capture efficiency will be discussed.
Improved Magnetoelastic (ME) Sensing By Using Gelatin for Salmonella Pick-up from Large Scale Surfaces
Authors: Liu Yuzhe , Du Songtao , Chen I-Hsuan , MacLachlan Alana , Huang Tung-Shi , Chin Bryan A.
Published: February 2020

ME sensing, as a fast, on-site, and label-free measurement technique, has been studied in the recent decade for the detection of Salmonella. During the development of ME sensors, there has been a dilemma – to increase sensitivity, the size of a ME sensor must be reduced, while in direct surface detection, a reduced sensor size results in a smaller detection area, larger edge effect, and is harder to handle. To solve this problem, in this paper we introduce a novel gelatin assisted ME sensing system. A gelatin solution at a concentration of 0.05 g/ml was prepared and uniformly applied to the sample surface. A thin gelatin film formed after 2 hours of drying and was easily peeled off to remove most of the Salmonella colonies from the surface. With the application of gelatin, the detection area of one ME sensor was improved from 0.2 mm x 1 mm to 30 mm x 30 mm. In our previous study, swabbing, as an inexpensive, easy-to-use, and widely accepted sampling method, has been used to improve the ME biosensing system for quick detection of surface pathogens. Compared with the swab sampling method, not only was the recovery rate of gelatin assisted ME sensing system much higher, but the detection limit can be significantly improved.
Development of a 3D-Printed Force Sensor with Carbon Paste
Authors: Rubiano Alejandro , Shamkhalichenar Hamed , Choi Jin-Woo
Published: February 2020

Force sensors play an important role in the biomedical devices industry, especially in motion- and pressure-related devices. Such sensors are designed to collect force or pressure data by converting it into electrical signals. The data can then be sent to and analyzed by a local or cloud-based processing unit. It is vital that the sensors can be fabricated in a way that time efficiency, cost efficiency, and quality are all maximized. The advent of three-dimensional (3D) printing has greatly facilitated prototyping and customized manufacturing, as compared to older crafting methods (such as welding and woodworking), 3D printing requires less skill and involves less costly materials making it much more time- and cost-efficient. Technological advancements have also improved the quality of the actual sensing materials used in sensor-based devices, and notably, carbon-based materials have become increasingly favored for use as sensing elements. In the presented sensor, the modern sensor fabrication methods of 3D printing and using carbon materials as sensing elements are combined.

The sensor presented as a proof of the above concepts is a cantilever flex sensor. The sensor consists of a 30 mm-long cantilever extending from a 2.5 mm-thick wall, with a second wall of the same thickness parallel to the cantilever. After designing this structure and printing it using a 3D printer, the top surface of the cantilever was coated with a thin layer of conductive carbon paste and two copper wires were stripped and soldered to a pair of copper alligator clips, to be used for testing purposes. To test the sensor, the two copper wires were clipped onto the sensor (Figure 1A) and each wire was connected to a multimeter probe on the end opposite of the alligator clip. Then, using a set of four through holes in the parallel wall (along with a slotted rod), the tip of the cantilever was pressed down to an angle of 5, 10, 15, or 20 degrees (Figures 1B, 1C, 1D, and 1E, respectively) below the original plane of the cantilever and held there for 2 minutes. The resistance between the ends of the cantilever was measured throughout each trial by the multimeter, and the results (Figure 1F) for each angle were compiled and analyzed to determine the effect of each depression angle on impedance change, and thus, the overall effectiveness of the sensor. In the future, a notable improvement would be miniaturizing the sensor to facilitate in integration of the sensor in wearable and biomedical devices.

Figure 1
Electrical Sensing Capability of Carbon Nano-Tubes/Alumina Cement Composites, Probed through Frequency-Dependent Impedance Spectroscopy
Authors: Oh Jiwon , Kim Jaehwan , Lee Hyunbae , Hwang Heesu , Jang Wonjun , Choi Eunsoo , Hwang Jin-Ha
Published: February 2020

High demand on smart materials has ignited extensive academic and industrial research on hybrid materials involving carbon nano-tubes (CNTs) or grapheme-associated materials by replacing the pre-existing single-phase bulk materials. The derivatives are economically available due to tremendous research and development in association with industrial applications. The conducting features can be exploited towards smart sensing for mechanical failure (or even mechanical deformation, functioning as an indicator for safety guidelines. The smart sensing features are tested using alumina-based cements as a matrix material due to the unique characteristic of rapid-setting performance. In particular, the hydrophobic features are modified into hydrophilic ones using rationally-designed dispersing agent materials. The modified CNT solution is mixed with the alumina cement at the predetermined ratios. The degree of microstructural change is probed using the corresponding bulk resistance (or equivalently). Additionally, the mechanical robustness is evaluated based on CNT-based networks involving electronic and ionic conduction along with charge transfer between electronic and ionic conductors using ac-based impedance spectroscopy. The bulk responses involves multi-paths which are made up of CNTs, ionic paths along the interconnected pores filled with high-conductivity solution, and hydrated materials in addition to the original materials in the pristine state. The complicated electrical/dielectric responses are analyzed through the systematic integration of impedance spectroscopy and distribution of relaxation times. The roles of CNT-controlled smart materials are discussed towards the structural health monitoring in structural infrastructures, by taking into account the underlying mechanism involving chemistry and microstructural features of the CNT/alumina cement composite materials. The applicability of CNT-controlled smart materials is discussed towards the structural health monitoring in structural infrastructures, by taking into account the underlying mechanism involving chemistry and microstructural features.
Fabrication of Highely Sensitive Non-Enzymatic Glucose Sensor Based on Highly Porous Cu/Cu2o/CuO Embedded in N Doped Carbon Aerogel
Authors: Alsherhi Saad M.
Published: February 2020

A novel nanocomposite, Cu/Cu2O/CuO embedded in N-doped carbon aerogel was fabricated using egg albumin and first time used as enzyme-free amperometric electrochemical glucose sensor. Excitingly, egg white played a crucial role in the in-situ formation of highly porous, small size, well dispersed Cu/Cu2O/CuO nanoparticles in N-doped carbon aerogel. The Cu/Cu2O/CuO-NC modified electrode was employed for non-enzymatic glucose detection where it exhibited a detection limit of 0.40 M and an outstanding sensitivity of 7892 A cm−2 mM−1 which is superior to existing cu based modified electrodes. The high sensitivity was attributed to the synergy arising from the ternary compositions embedded in N-doped carbon interfacing with multiple Cu redox couples and high surface area. The Cu/Cu2O/CuO-NC modified electrode also showed excellent selectivity in detecting glucose in the presence of interfering species, including chloride salts of Na+, K+, Ca2+, and anions of ascorbic acid (AA), dopamine (DA), and uric acid (UA). This simple and scalable carbonization technique will attract interest and enable in designing other high-performance metal/metal oxide embedded in N-doped carbon composites for commercial glucose sensing applications.
Peltier-Driven Temperature Control for Fluorescent Sensing Platform
Authors: Robertson Brianna , Shin Young-Ho , Choi Jin-Woo
Published: February 2020

Fluorescence dyes are widely used in biomolecule detection/quantification, flow tracing reference for gases and liquids, pathogen detection, and other life science applications. However, fluorescence emission efficiency of the dyes is easily affected by several parameters, such as polarity, pH, and temperature. Therefore, it is essential to monitor and control these parameters for reliable and accurate measurements. We propose a 3D-printed copper cuvette holder (i.materialise, Belgium) joined with a Peltier-based temperature controller platform for stable reading of fluorescence emission from the dye. For demonstration of temperature effects on fluorescence efficiency, rhodamine B, which is one of the widely used fluorescence standards and probes in bioscience, was used.

For excitation, 530 nm wavelength lighting was utilized for stimulating the rhodamine B. A Peltier device was controlled with different levels of direct current (DC) to demonstrate the temperature controlling capability of the device and fluorescence efficiency of the rhodamine B was tested with a varying temperature level: 20 ºC to 80 ºC. For our device, the temperature will be monitored by temperature ICs that are attached at three different points of the copper body for uniform temperature heating of the solution in a cuvette. We have monitored the temperature distribution of the copper holder with an external temperature monitor, the DT304, and determined that the temperature is maintained to with a 5 ºC. We plan to monitor the solution temperature directly with the use of an infrared temperature sensor positioned down at the opening of the cuvette. The ambient temperature and the temperature of the opposite junction of the Peltier device will be monitored through the use of two thermocouples. An analysis of several different temperature components of the device allow for a better interpretation of what is happening in the system. Moreover, the implementation of a water-cooling apparatus will allow for a way to quickly decrease the temperature of the cuvette when desirable. These features allow for the sample to be monitored efficiently, allowing for proper stabilization techniques and the ability to fluctuate the temperature when required of an application.

In summary, we have developed an 3D-printed copper cuvette holder with a Peltier-based temperature controller platform for stable reading of fluorescence emission from the dye or fluorophore solution. Our compact temperature controller system provides viable option for any fluorometers to easily apply it for temperature stabilization during the fluorescence dye testing.

Figure 1
High Sensitive Au Nanoparticles Igzo FET Cancer Sensor Via Real-Time Analysis Micro-Fluid Separation
Authors: Kwon Hyo-Jun , Yang Hee-Won , Kim Min-Young , Lee Seung-Beck , Kim Chul Geun , Choi Ho-Soon , Park Jea-Gun
Published: February 2020

The bio-sensor technologies to detect cancer cells have been attracted much attention because detecting the presence of a cancer in a human blood at an early stage can extend the human lifetime. To diagnose a cancer in human normal blood cells, electrical biosensors such as carbon nanotube field-effective transistor, AlGaN/GaN HEMT, reduced graphene oxide TFT, Si nanowire FET, PEDOT:PSS conducting paper, and ZnO nano-rods have been intensively studied because they detect and diagnose the type and amount of cancer cell by estimating the electrical charge amount of the cancer cell in the human blood. However, they have not demonstrated for detecting and diagnosing a cancer cell in circulating cancer stem cell (CCSC). In our study, thus, we cultured breast cancer cell (BCC) line, MDA-MB-231, and designed cancer detecting system in which the detection devices are implemented with a separation device to separate the cancer cell from mixed solution of cancer cell line and normal blood by utilizing both size and deformability of cancer cell. In particular, we designed a real time enumeration image analysis tool to acquire morphology data of breast cancer cell line for image-based cell analysis. For detecting the cancer cell via determining the threshold voltage shift (∆Vth) of field effect transistor (FET), an In-Ga-Zn-Oxide (IGZO) based FET implemented with Au nano-particles (NPs) was fabricated. For the experimental process, the 10-μL solution of separated cancer cell lines connected with the cancer-anti-body (CD-44) was dropped on the IGZO FET channel with Au NPs where a linker (8-Mercaptooctanoic acid) was attached on Au NPs. Consequently, we successfully demonstrated the separation of cancer cell from normal blood sample and after dropping cancer cell on the detection device the ∆Vth value was shifted negative direction. Furthermore, we observed the fluorescent staining image of cancer cell separated from normal blood sample. We report the separation and detection system which enables to separate and detect cancer cell.

Figure 1
Creation of 3D Print Gel Actuator
Authors: Takishima Yuki , Yoshida Kazunari , Saito Azusa , Kawakami Masaru , Furukawa Hidemitsu
Published: February 2020

United Nations set the goal to maintain the richness of the sea in SDGs. In Japan, they are aiming for broad spectrum and real time of ocean information collection. Various kinds of underwater exploration techniques have been developed. For instance, submersible research vehicles and autonomous underwater vehicle (AUV) have been used for observation of underwater conditions, in addition to the technique of fixed-point observation. However, such research vehicles and conventional AUV are difficult to control, are expensive, and are usually made with non-biodegradable materials such as metals. For this problem, we came up with the robot composed by only organic material. This idea realizes the recycling society. Jellyfish is the most efficient swimmers, traveling for long distance with saving energy by drifting in the ocean, its body can be decomposed after death, and safe for surrounding creatures. Therefore, we are developing the jellyfish-mimic AUV using a hydrogel. For designing a Jellyfish-mimic AUV robot, it is preferable to introduce a soft actuator driven by water pressure, as it requires low electric power and it is eco-friendly. Here, we report a 3D printing hydrogel hydraulically-driven soft actuator that can make a bending motion of umbrella-shaped bell of artificial Jellyfish. We utilized the Pneunets Bending Actuator for designing the actuator, and the detailed information of this actuator is shown in the website of Soft Robotics Toolkit (see https://softroboticstoolkit.com/book/pneunets-bending-actuator). We changed the parameters of 3D print speed and UV light power gel concentration when we make some gel actuators. In addition, we measured and evaluated these performances. Finally, we are making the robot to use it and be composed by only organic materials so that we can release many robots at the same time.
Biosensor for Detection of Methicillin-Resistant Staphylococcus Aureus
Authors: Patel Dhara , Zhou Yan , Ramasamy Ramaraja P.
Published: February 2020

Bacterial pathogens are ubiquitous in nature and are important targets for detection in various applications. In the healthcare industry, Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial pathogen that is resistant to many antibiotics. MRSA, if not treated promptly, can cause severe complications such as bloodstream infections, pneumonia, and surgical site infections leading to sepsis and eventual death [1]. Current conventional detection methods for pathogens usually take a few hours to days for identification and need skilled experts and tools such as cefoxitin disk screen tests, latex agglutination tests, and real-time PCR for analyses [2]. Biosensors, on the other hand, are simple, easy to use, and provide rapid results as well as aid in real-time monitoring. Specifically, electrochemical biosensors are advantageous over conventional methods with their ease of use, high specificity and sensitivity [3]. In the current work, a carbon nanotube-based impedimetric biosensor was developed for rapid and selective detection of live MRSA cells [4]. MRSA USA300 specific phage SATA-8505 was used as the recognition element for selective detection of its host bacteria cells. The detection mechanism uses an impedimetric measurement of the resistance changes on an electrode, where bacteriophages were immobilized onto functionalized carbon nanotube using an electric field-induced, charge-directed orientation strategy. Infectivity study using disk diffusion methods showed activity retention of immobilized bacteriophages on the electrodes. The established biosensor showed high selectivity toward MRSA USA300. The biosensor could potentially be integrated into lab-on-a-chip platforms for point of care use and for other health-care associated pathogens, such as Pseudomonas aeruginosa and Klebsiella pneumoniae.

References

1. Klevens, R.M.; Morrison, M.A.; Nadle, J.; Petit, S.; Gershman, K.; Ray, S.; Harrison, L.H.; Lynfield, R.; Dumyati, G.; Townes, J.M.; et al. Invasive Methicillin-resistant Staphylococcus aureus Infections in the United States. J. Am. Med. Assoc. 2007, 298, 1763–1771.

2. Datta, P.; Gulati, N.; Singla, N.; Vasdeva, H. R.; Bala, K.; Chander, J.; Gupta, V. Evaluation of Various Methods for the Detection of Methicillin-resistant Staphylococcus aureus Strains and Susceptibility Patterns J. Med. Microbiology. 2011, 60, 1613-1616.

3. Maalouf, R.; Fournier-Wirth, C.; Coste, J.; Chebib, H.; Saikali, Y.; Vittori, O.; Errachid, A.; Cloarec, J.-P.; Martelet, C.; Jaffrezic-Renault, N. Label-Free Detection of Bacteria by Electrochemical Impedance Spectroscopy: Comparison to Surface Plasmon Resonance Anal. Chem. (Washington, DC, U. S.) 2007, 79, 4879−4886.

4. Zhou, Y.; Marar, A.; Kner, P.; Ramasamy, R.; Charge-Directed Immobilization of Bacteriophage on Nanostructured Electrode for Whole-Cell Electrochemical Biosensors Anal. Chem. 2017, 89, 11, 5734-5741.
Parameter Optimization for a Novel Phage-Based Biomolecular Filter for Detection of Pathogens from Large Volumes of Water
Authors: MacLachlan Alana , He Jiacheng , Du Songtao , Horikawa Shin , Chen I-Hsuan , Liu Yuzhe , Chin Bryan A. , Chen Pengyu
Published: February 2020

Each year in the United States, foodborne pathogens, including bacteria, viruses, and parasites, cause an estimated 48 million illnesses, 128,000 hospitalizations, and 3,000 deaths. Forty-six percent of those illnesses are attributed to fresh produce, with pathogens on leafy greens causing the most illnesses. Pathogen contamination in fresh foods is a threat to public health. Unfortunately, the microbiological testing of a few samples of whole fruits or even hundreds of spinach leaves is inadequate to ensure the safety of a batch of specialty crop produce. Similarly, microbiological testing of only a few milliliters from thousands of liters of irrigation water and wash water used to grow and process a batch of specialty crop produce is woefully inadequate. A revolutionary, non-clogging phage filter system has been developed to capture, concentrate and isolate small numbers of multiple pathogens (100 CFU) from large volumes of irrigation and wash water (1,000 liters <10 minutes), so that foodborne illnesses can be rapidly identified before food is distributed to consumers. To optimize the performance of the filter system, we investigated a broad-spectrum of parameters inclusive of sensor elements, filter configuration, flow velocity, fluid pressure and operation temperature that would contribute to the development of a better system. This project will benefit growers, processors and distributors by rapidly identifying contaminated irrigation water, contaminated lots of produce, and improving production efficiency while reducing recalls and litigation.
Synthesis and Characterization of Highly Sensitive pH Probes Based on Fluorescein-Conjugated Gold Nanoclusters
Authors: Han Sangmyeong , Pyo Kyunglim , Lee Dongil
Published: February 2020

Intracellular pH is a critical parameter that regulates the cellular metabolism. Thus, sensitive monitoring of the intracellular pH change is essential in understanding mechanisms governing drug delivery and cell apoptosis. In this work, we synthesized highly sensitive pH probes composed of fluorescein and glutathione-protected gold nanoclusters and characterized their optical properties. The fluorescein was conjugated to the gold nanocluster by using an amide coupling reaction. In steady-state photoluminescence (PL) measurements, fluorescein conjugated to gold nanocluster shows more than 160-fold pH-contrasting emission in the pH range of 4.3-7.8 while glutathione coupled fluorescein shows only 10-fold pH contrast in the same pH range. Transient absorption measurements confirmed that the enhanced PL was caused by the ultrafast energy transfer from the nonthermalized states of gold nanocluster to fluorescein. Furthermore, efficient nonthermalized energy transfer occurring in the fluorescein-conjugated gold nanocluster led to a dramatically pH-contrasting PL. In addition to the intrinsic advantages such as low toxicity and facile surface modification, fluorescein-conjugated gold nanoclusters exhibit high pH sensitivity with wide dynamic range, offering new opportunities for the study of intracellular processes.
Ionic Liquid Composite Electrocatalysts for the Oxygen Reduction Reaction
Authors: Gawas Ramchandra , Li Yawei , Snyder Joshua David
Published: February 2020

Recent advancements in electrocatalysts for oxygen reduction reaction (ORR) involve changes in electrochemical composition, nanostructure and support mechanism of catalyst layers. Some of the methods described above show significant potential for improving the catalytic performance. But, degradation of the catalyst, due to dissolution, detachment, agglomeration and carbon corrosion, remains the major challenge in utilizing them in actual fuel cell applications. Apart from the catalyst, catalyst-electrolyte interface plays a major role in cathodic ORR. Therefore, modification of this interface presents an alternative method to enhance ORR performance. Here, we present our work to incorporate protic ionic liquids into the catalyst-electrolyte interface in nanostructured as well as single crystal electrocatalysts. These ionic liquid modified electrocatalysts show improved activity and stability in ORR performance because of oxygen solubility and hydrophobicity of ionic liquids. We will present our understanding of the mechanism of activity and stability enhancement due ionic liquid interlayers as well as their integration into membrane electrode assemblies (MEA).
Multiscale Roughness Characterization of Electropolished 316L ALM Steel By Power Spectral Density Post-Treatment
Authors: Drynski Estelle , Doche Marie-Laure , Hihn Jean-Yves , Tardelli Joffrey
Published: February 2020

Electrolytic polishing (EP) is a well-known technology which may replace mechanical polishing in finishing treatment of complex geometry substrates produced by additive manufacturing (AM). This consists in an anodic dissolution process, allowing a mirror finish to be obtained by uniform roughness reduction on metallic parts immediately after the machining step. This is achieved by controlling electrolyte nature and operating parameters such as dissolution potentials, process duration and temperature [1]. Nevertheless, in the specific case of additive manufacturing, where high level of roughness can be observed, it is important to discriminate the microscopic and macroscopic scales of etching. The roughness value can be measured at different scales by several technics (mechanical sensor, optical profiler, AFM…), but the results (Ra, Sa…) are dependent on the spatial resolution of the device and on the measurement procedure like cut-off application. A way to overcome this problem consists in making these parameters independent of the roughness scale by integrating the fractal dimension of topographic records [2].

In this study, 316L stainless steel samples obtained by additive manufacturing were electropolished and compared to raw and mechanically polished samples. The characterization of the surface roughness was carried out by optical profilometry, and the 2-D data were analyzed to plot Power Spectral Density as a function of spatial frequency (PSD) [3]. Then, the curves obtained are fitted by the Weierstrass-Mandelbrot function to determinate the fractal dimension, which allows quantification of the surface irregularity level [4].

Acknowledgments : the authors would like to thank the IRT-M2P program AFTER ALM for its financial support.

[1] C. Rotty, A. Mandroyan, M.-L. Doche, and J. Y. Hihn, Surf. Coat. Technol., 307 Part A, 125–135 (2016)

[2] Majumdar, A., Tien, C.L.: Fractal characterization and simulation of rough surfaces. Wear 136(2), 313–327 (1990)

[3] Prashant Pendyala, M. S. Bobji, Giridhar Madras. Evolution of Surface Roughness During Electropolishing, (2014). Springer Science Editions

[4] S. Panda, A. Panzade, M. Sarangi, S.K.R. Chowdhury, Journal of Tribology, 139 031402-1/9 (2017)

Figure 1
Hexagonal Nickel/Nickel Hydroxide Nanoplates As Efficient Bifunctional Electrocatalysts for Overall Water Splitting
Authors: Kim Sangjin , Oh Euntaek , Lim Dongwook , Baeck Sung-Hyeon
Published: February 2020

Electrochemical water splitting has been considered as a promising strategy for next-generation energy storage and conversion applications by converting abundant water into extremely pure hydrogen and oxygen. However, the water splitting is limited by the high overpotentials for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Thus, numerous efforts have been dedicated to developing efficient and low-cost bifunctional catalysts. Among the various candidates, nickel-based compounds have attracted increasing interest for HER and OER due to their low cost, abundance, and high electrocatalytic activities. Herein, we report hexagonal Ni/Ni(OH)2 nanoplates via one-pot hydrothermal method with varying the ratio between metal precursor and hydrazine which is a strong chemical reductant. The bifunctional catalyst exhibited low overpotential of 171 mV and 310 mV to achieve the current density of 10 mA cm−2 for HER and OER, respectively. Also, the Ni/Ni(OH)2 nanoplates show the outstanding long-term stability for both HER and OER in 1 M KOH alkaline media. In overall water splitting system, the hybrid catalyst exhibits a current density of 10 mA cm−2 at a cell voltage 1.78 V. The high electrochemical activity and durability are mainly originated from the synergistic effect of Ni and Ni(OH)2. This work demonstrates that our simple synthetic approach can be applied to synthesize various metal/metal hydroxide composites and improve their electrochemical property for renewable energy storage application.
Electrochemical Polarization Behavior of 304L Stainless Steel in a Thin Layer of Chloride Solution
Authors: Korjenic Alen , Kundu Arnab , Charit Indrajit , Raja Krishnan S.
Published: February 2020

Spent nuclear fuels are stored in stainless steel canisters. The containers are cooled naturally by a convective airflow through the annulus between the overpack and the canister. This air flow draws dust into the overpacks, and the surfaces of containers are covered with dust. Salts carried by the dust will deliquesce as heat generated by radioactive decay declines over time. The deliquescence of salt deposit could induce various forms of corrosion attack such as pitting and chloride-induced stress corrosion cracking (SCC). In this study, the corrosion behavior of 304L SS - a typical dry storage container material, is evaluated by simulating the deliquescence of salt deposit using a thin electrolyte test condition.

Electrochemical corrosion test was performed on 304L Stainless Steel in 3.5 wt% NaCl solution at 20 OC. The tests were carried out in a newly fabricated electrochemical cell with exposed surface area of test specimen being 1 cm2. The cell has a movable PTFE wall which houses a Pt foil as a counter electrode. The adjustable wall enables the thickness of electrolyte to be varied between the SS specimen and the counter electrode. The thickness of the electrolyte was maintained at 1 mm in all the tests. This resulted in the volume of the electrolyte to be 10 ml. Open circuit potential, cyclic polarization and potentiostatic tests at different passivation potential were carried out. The potentiostatic passivation tests were followed by electrochemical impedance spectroscopy and Mott-Schotky analysis in order to understand the initiation of localized corrosion. For comparison, the electrochemical tests are being performed by using bulk electrolytes. The electrochemical polarization behavior in the thin film electrolyte was more or less similar to that in the bulk electrolyte. However, the pitting protection was shifted in the negative direction by about 80 mV in the thin electrolyte as compared to that of bulk electrolyte. Potentiostatic tests conducted at potentials below the pitting protection potential did not show pit initiation. Relatively a quick pit initiation event was observed when the applied potential was 60 mV anodic to the pitting protection potential. Bulk electrolytes showed no passivity breakdown at this potential. The results will be analyzed based on the EIS data, semiconducting properties of the passive film, and UV-Vis absorption of the test electrolytes.
Galvanic Corrosion Processes of Aluminum Coupled to Iron in Chloride Solutions at Near-Neutral pH
Authors: Kosaba Takumi , Muto Izumi , Sugawara Yu
Published: February 2020

Multimaterial structures are effective for weight reduction of automobiles, which contributes to the prevention of global warming and the decrease in CO2 emission. Steel-aluminum joints have many advantages such as low cost, high strength, and high corrosion resistance. However, galvanic corrosion was expected to occur because the corrosion potential of aluminum alloys is usually different from those of iron and steels. Considering the galvanic corrosion processes in chloride-containing near-neutral pH solutions, the existence of surface oxides is an important factor affecting the initiation of corrosion. In this research, the galvanic corrosion behavior of aluminum alloy coupled to iron and the steel in near-neutral pH solutions was investigated.

Pure iron, AISI 1045 carbon steel, pure aluminum, and A5083-O(Al-Mg alloy) were used as the specimens in this research. The surfaces of pure iron and AISI 1045 were polished down to 1 µm. Pure aluminum and A5083-O were polished down to 0.25 µm with a diamond paste and cleaned ultrasonically in ethanol before electrochemical measurements. The electrode area was ca. 1 cm2. Ag/AgCl (3.33 M KCl) was used as the reference electrode.

In diluted synthetic seawater (200mg/L [Cl-], pH 8.2, naturally aerated, galvanic current was measured for 20 h using zero resistance ammeter technique. The distance between two electrodes was 1 cm. Fig. 1(a) shows the time variation of the galvanic current and electrode potential of pure aluminum coupled to pure iron. From the beginning of the immersion to 30 ks, many current transients were generated. However, after 30 ks, the galvanic current became a constant value of approximately 0.15 µA cm-2. The potential gradually decreased with time. The pH of the electrolyte decreased from 8.2 to 6.7 by galvanic corrosion. Fig. 1(b) and 1(c) shows the electrode surfaces of pure iron and pure aluminum after galvanic current measurements. Rust was observed on pure iron, and filiform corrosion was generated on pure aluminum.

Anodic polarization curves were measured in diluted synthetic seawater (200mg/L [Cl-], deaerated), and the pH was adjusted to 8.2, 6.7, 5.2, 3.7, and 2.2 with NaOH or H2SO4. Potentiodynamic polarization was started from corrosion potential, and the scanning rate was 23 mV min-1. The electrode potential of pure aluminum under galvanic coupling conditions was found to be lower than the pitting potentials of pure aluminum. But, corrosion was initiated on the aluminum surface (see Fig. 1(b, c)). The galvanic corrosion behavior of pure aluminum and aluminum alloy AA5083 were discussed in terms of the surface properties of the specimens and solution chemistry.

Figure 1
Assembly of SnO2-ZnO Composite Hollow Nanofibers for CO2 reduction Reaction to Formate
Authors: Tan Daniel , Kim Young-Eun , Lee Wonhee , Park Ki Tae , Jeong Soon Kwan
Published: February 2020

Tin oxide (SnO2) is a well-known material that has been applied widely in various fields, such as catalyst, solar cell and gas sensor. As electrode material, its high selectivity through formate during carbon dioxide reduction reaction (CO2RR) make it attractive to be explored further. In addition, it is found that compare to a pure substance, composite material exhibits better performance due to the enhanced inner electric field at the particle interface. Zinc oxide (ZnO) becomes one of the promising candidates as a composite material with tin oxide due to low cost, suitability, good chemical stability, and electrochemical properties as well as its selectivity to formate. A wide range of metal oxide have been synthesized by various physical and chemical techniques. Among the techniques, electrospinning is one of the promising and versatile method to create one-dimensional nanostructures such as nanofiber, nanotubes, and nanowires with tunable diameters size and morphology. The high surface to volume ratio can provide large surface areas and also able to reduce mechanical strains within particle thus can increase the performance.

SnO2-ZnO composite hollow nanofibers were synthesized by electrospinning followed by annealing using SnCl2.2H2O and Zn(NO3)2.6H2O as main precursors. The physical characterization were investigated by field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). As a comparison, pure SnO2 nanofibers were also prepared. It shows that the crystals phase intensity is proportional to the annealing temperature. While the diameter size of the fibers strongly depends on ZnO contents associated with the Kirkendall effect which describes diffusional mobility along radial direction during annealing. The electrochemical performances were investigated in a H-type cell with 1cm2 catalyst-coated carbon fiber paper as a working electrode. While an Ag/AgCl electrode was used as a reference electrode along with a Pt coil as a counter electrode. The aqueous solution of KHCO3 and KOH were used as catholyte and anolyte respectively, with Nafion 115 as the separator. The quantitative analysis were caried out by gas chromatography (GC) and high-performance liquid chromatography (HPLC) to investigate the FE, PCD, and concentration of formate.