bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Fields That Enhance the Rates of Multistep Reactions Important in Energy Storage and Conversion
Authors: Gellett Wayne L. , Lee Heung Chan , Reed Jessica Jewett , Leddy Johna
Published: February 2020

Reactions at the electrode solution interface are ubiquitous and integral in electrochemical generation and storage systems. As the number of steps in the electron transfer process increases, the probability of reduce energy efficiency increases through undesirable side reactions and slow steps. When the electron transfer step slows the overall reaction rate, electrocatalysts can increase net efficiency.

    Incorporation of magnetic microparticles to the electrode has been shown to increase the efficiency of various electrochemical energy systems that include fuel cells, batteries, photovoltaics, and supercapacitors. It is generally observed that energy and power are increased by 40 % on incorporation of magnetic microparticles.

    Every interfacial electron transfer process is composed of multiple steps. The simplest model is mass transport of the reactant to the electrode surface, the electron transfer, and mass transport of the product into the solution. In multistep processes, additional steps may be important such as adsorption, multiple electron transfers, and chemical reaction on the surface or in the bulk. The electron transfer step is usually envisioned as a simple charge transfer. However, the electron transfer includes transfer of charge and spin. Magnetic properties of the electron and molecular entities arise through the spin. Addition of magnetic microparticles alters the rates of interfacial electron transfers.

    Here, three examples of magnetoelectrocatalysis in reactions important to electrochemical generation and storage are presented. In each of these systems, chemically inert micromagnets are held to the electrode surface in a coating of Nafion (R). In these reactions, there are components of mass transport, adsorption, interfacial spin and charge transfer, and surface reactions.

The hydrogen evolution reaction (HER) is facilitated at magnetically modified, single crystal p-Si. Overpotential is reduced >500 mV on magnetic modification.

Hydride storage in palladium is improved as the interfacial rates of H∙ transfer are increased by several orders of magnitude and overpotentials reduced by several hundred millivolts.

CO oxidation on platinum occurs near the thermodynamic potential at room temperature in water. The overpotential is reduced 600 mV with micromagnets.

    In each of these technologically important reactions, magnetic microparticles increase the rates of inherently slow, interfacial reactions. The effect is a physical interaction wherein magnetoelectrocatalysis effects substantially increased rates of electron transfer.
Methanol Photooxidation on Colloidal Anatase TiO2: A Mechanistic Study
Authors: Alpuche-Aviles Mario A , Barakoti Krishna K. , Recinos Andrew
Published: February 2020

We present a study of the methanol photo-oxidation reaction using anatase as a model reaction for colloidal suspensions of photocatalysts. We perform our reactions with suspended anatase nanoparticles of ca. 20 nm diameter. Our model includes photo-oxidation of methanol to formaldehyde under controlled conditions that minimize the content of water and oxygen. We investigate the reaction products from the photooxidation of methanol under an inert atmosphere (Ar) by analyzing the solution phase. Fourier Transform Infrared (FTIR) and Electrospray Ionization (ESI) techniques are employed to detect methanol oxidation products to provide a comprehensive view of the process. We are using modified procedure to detect formaldehyde in a matrix predominantly composed of methanol by detection of a derivative in ESI. Our observations reveal formaldehyde as the predominant photo-oxidation product for UV-illuminated TiO2 suspension in methanol. Interestingly, our measurements did not show carbon dioxide as a by-product. Conversion of methanol into formaldehyde is consistent with a two electron oxidation mechanism as the main reaction pathway. Here, report our qualitative and quantitative analysis of the possible methanol by products and its implications for the photoelectrochemical measurements of colloidal NPs.
Mechanistic Study of Energy Efficient Electrochemical Capture and Release of CO2 in Ionic Liquid Complexes
Authors: Singh Poonam , Buttry Daniel A
Published: February 2020

There is an urgent need for the development of energy efficient methods for the capture and storage of carbon dioxide (CO2). Several electrochemical agents which can capture CO2 have been explored in our group over the last few years. The basic idea is to electrochemically reduce a precursor (P) to generate a potent nucleophile (N-) which then reacts with CO2 to form an adduct (N-CO2
-). Later, this adduct is electrochemically oxidized to regenerate the precursor and the released CO2 can then be captured. In most cases, the CO2 is bound to either a nitrogen or a sulfur atom of the nucleophile. In the current work, we describe the mechanism for the electrochemistry of bipyridines and disulphides in presence of CO2 in n-butyl-n-methylpyrrolidinium bis(trifluoromethylsulfonly)imide (BMP+ TFSI-) ionic liquid using a combined approach employing experimental studies and digital simulation.

The work has been focused on using bipyridine and disulphide systems for electrochemical CO2 capture. In these systems, the electrogenerated nucleophiles i.e.  bipyridinium radical anions (as shown in Figure 1) or thiolates reacts with CO2 to form an adduct. Furthermore, the CO2 adduct i.e. carbamate or thiocarbonate can be oxidized to release the precursor and CO2. The oxidation potential of these adducts shifts far positive as compared to the oxidation of the nucleophiles. Based on the detailed comparison of the experimental data with simulations using possible mechanistic models, it is found that the electrogeneration of nucleophiles reacts with CO2 to form an adduct and the direct oxidation of the adduct using EC mechanism releases the precursor and CO2.

Acknowledgement

We acknowledge the support from Advanced Research Projects Agency (ARPA-E) for this work. 

References

1.  P.V. Danckwerts, Chemical Engineering Science, 34(4),443-446 (1979).

2. G.P. Hammond and S.S.O. Akwe, International  
Journal of Energy Research,
31(12), 1180-1201 (2007).

3.  H.W. Pennline et al., Fuel Processing Technology, 89
(9), 897-907 (2008).

4.  S.S. Moganty and R.E. Baltus, Industrial &
Engineering Chemistry Research, 49(12), 5846-5853 (2010).

5. M.B. Mizen and M.S. Wrighton, Journal of The
Electrochemical Society, 136(4), 941-946, (1989).

6. H. Ishida, T. Ohba, T. Yamaguchi and K. Ohkubo, Chemistry Letters, 905-908 (1994).

7. E. Shouji and D. A. Buttry, Journal of Physical 
Chemistry B,
103(12)
, 2239-2247 (1999).

Figure-1 Experimental (black) and simulated (red) cyclic voltammograms for electrochemistry of 10 mM 4,4'-bipyridine in the presence of 10 mM CO2 in BMP+ TFSI- ionic liquid on glassy carbon electrode. Scan rate: 50 mV/s.

Figure 1
On the Mechanism of Electrochemical Reduction of Niobium Halides in Ionic Liquids
Authors: Ispas Adriana , Bund Andreas
Published: February 2020

In this paper we will discuss possible mechanisms of the charge transfer for the reduction of Nb halides in ionic liquids with pyrrolidinium cations. The reduction sequence starts from Nb(V) and seems to be relatively complex. Our experimental approach is mainly based on voltammetry combined with in-situ microgravimetry (quartz crystal microbalance) to study the mass-charge balance of the reduction process. There is strong indication for the occurance of at least one intermediate species, probably Nb(III). This intermediate can be detected in rotating ring disk electrode experiments. The rate constants of the individual charge transfer steps can be estimated from square wave voltammetry.
Effect of 1-Butyl-1-Methylpyrrolidnium Dicyanamide on the Structure of Pd Electrodeposit
Authors: Shrestha Sujan , Biddinger Elizabeth J
Published: February 2020

One of the most widely investigated applications of ionic liquids (ILs) is electrodeposition (1). Wide electrochemical window, good conductivity, metal complexing ability, and low water content are the advantages of doing electrodeposition in ILs. Electrodeposition of metals from every group of the periodic table has been studied (2). One of such metal is Pd, which has hydrogen embrittlement issues in aqueous-based solutions. In ILs, the embrittlement issue could be avoided (3). Although many ILs have been tried for Pd electrodeposition, the morphology of the electrodeposit has often been often been powdery and prone to cracks (3-5). Understanding the structure of the Pd electrodeposited in ILs could reveal ways to improve its morphology.

     In this work, structure of the Pd electrodeposited in 1-butyl-methylpyrrolidinium dicyanamide ([Bmpyrr][DCA]) is studied. Due to the metal complexing ability of [DCA]- anions, previous works have shown that [Bmpyrr][DCA] is a suitable room-temperature ILs to electrodeposit Pd (6, 7). After electrodeposition, we found significant presence of nitrogen on the Pd deposits through X-ray photoelectron spectroscopy (Figure 1). Since the source of nitrogen cannot be atmosphere, we hypothesized that the nitrogen was from [Bmpyrr][DCA] tethered to the Pd electrodeposit. This raises interesting questions as to the role of ILs in the structure of the Pd deposits. We will present further characterization of the Pd deposits using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron microscopy (XPS) to study the role of [Bmpyrr][DCA] on structure of the Pd deposit.

References

1.         F. Endres, D. R. MacFarlane and A. P. Abbott, Electrodeposition from ionic liquids, WILEY-VCH Verlag GmbH & Co. KGaA, Germany (2008).

2.         A. P. Abbott, G. Frisch and K. S. Ryder, Annual Review of Materials Research, 43, 335 (2013).

3.         T. Mehner, D. Nickel, S. Nehrkorn, A. Yulinova, M. Pügner, I. Scharf, G. Lanzinger, R. Böck and T. Lampke, Advanced Engineering Materials, 1 (2014).

4.         I. W. Sun and C. L. Hussey, Journal of Electroanalytical Chemistry, 274, 325 (1989).

5.         S. Schaltin, N. R. Brooks, J. Sniekers, L. Van Meervelt, K. Binnemans and J. Fransaer, Chemical Communications, 50, 10248 (2014).

6.         H.-Y. Huang and P.-Y. Chen, Talanta, 83, 379 (2010).

7.         H.-Y. Huang and P.-Y. Chen, Electrochimica Acta, 56, 2336 (2011).

Figure 1
Conductivity and Ionicity of Ionic Liquids Made By Ligand Assisted Ionization of Metal Halides
Authors: Hasani Mohammad , Angell Charles Austen
Published: February 2020

Ionic liquids with both metal containing anions and cations are of interest for their novelty and high metal concentration. They can be made similar to the well-known halometallate ionic liquids except that instead of having an organic chloride salt, the halide is transferred from another metal center to form a cationic metal species. Previous contributions[1]report on the synthesis and characterization of these systems.

            It is realized in our lab that heterolytic cleavage of Al2Cl6 with Lewis basic ligands results in ionic mixtures with low melting points. A variety of ligands including amides, amines, ureas, sulfones and organic carbonates has been used to bring about this auto-ionization. The ionic nature of the mixtures is manifested in their electrical conductivity. Considering the conductivity data in combination with viscosity and employing a Walden plot analysis, the ionicities of these melts have been studied (Figure-1). The Walden plot shows the urea and acetamide cases to be not fully ionic and hints at the presence of neutral species or aggregates of ions. The speciation of the metal center has been further studied by NMR spectroscopy.

[1] a) Hadi M. Abood et al. Chem. Commun., 2011, 47, 3523–3525. b) Nakayama Yuri et al. Phys. Chem. Chem. Phys., 2015, 17, 5758.c) Coleman Fergal et al. Angew. Chem. Int. Ed. 2013, 52, 12582.

Figure 1
Effective Design and Fabrication of Harsh Environment and Biomedical Gas Sensors
Authors: Dutta Prabir
Published: February 2020

Solid-state electrochemical devices composed of stabilized zirconia electrolytes (YSZ), e,g, oxygen sensor is used extensively for sensing in combustion environments. However, sensors for detecting other gases have not been as forthcoming. We will present our work in the area of NOx sensors based both on potentiometric and resistive strategies. We find that the heterogeneous catalytic activity of WO3, yttria-stabilized zirconia (YSZ), and Pt containing zeolite Y (PtY) have a significant influence on the performance of solid-state potentiometric gas sensors. Pt electrodes covered with PtY and WO3 are used as the reference and working electrodes because of the significant reactivity difference. Using highly catalytic active PtY to filter incoming gas mixtures can effectively remove interferences from 2000ppm CO, 800ppm propane, 10ppm NH3, as well as minimize effects of 1~13% O2, CO2, and H2O. A second strategy involves the use of p and n-type semiconducting oxides to cancel contributions of oxidizing gases, while enhancing the response to NO, thus leading to sensitivity of ppb levels. The improvement in sensitivity has led to new applications, particularly monitoring human breath for diagnosis of asthma and upper airway inflammation. We will present MEMS-based strategies for manufacture of miniaturized harsh environment tolerant gas sensors.
Performance Evaluation of Mixed-Potential HC, NOx and NH3 Sensors in Diesel and Lean Gasoline Engine Exhaust
Authors: Kreller Cortney R , Brosha Eric L. , Mukundan Rangachary , Prikhodko Vitaly , Pihl Josh , Curran Scott , Parks James E
Published: February 2020

Mixed-potential sensors fabricated via well-established commercial manufacturing methods present a promising avenue to enable the widespread utilization of NOx, hydrocarbon, and ammonia sensing technology.  These devices are fundamentally simple, inexpensive, and robust devices owing to their close relationship to the well-established and ubiquitous automotive Lambda sensor. Our first dynamometer experiments (2014) focused on testing a single device in lean-burn, diesel exhaust from a 1.9L GM turbo-diesel engine in both NOx and HC modes with gas sampling occurring both before and after the DOC.  In general, there was excellent qualitative agreement between actual exhaust gas composition (determined by FTIR and FID) however the inability to reproduce engine exhaust gas conditions exactly made precisely correlating sensor data to specific engine events while testing in the respective sensor operating modes difficult.  Recently, multiple mixed potential sensors were tested simultaneously in the exhaust of a lean-burn, 4 cylinder 2.0-liter naturally aspirated, direct injection gasoline engine (model year 2008, E87 European model BMW 1-series 120i.)  A mixed potential NOx sensor and a new NH3 sensor were tested downstream of the three way catalyst while a dedicated HC sensor was simultaneously tested upstream of the TWC. The sensor response and heater power applied to the sensors (e.g. sensor temperature) were continuously monitored while the high frequency impedance of a dedicated fourth sensor was tested for the purpose of independently monitoring sensor electrolyte temperature stability during dynamometer operation. Data from the sensors were collected under rich, stoichiometric, lean homogeneous, and lean stratified conditions (0.98<λ<1.8) and at various engine loads. To simulate the occurrence of ammonia slip in a selective catalytic reduction (SCR) emissions system, ammonia was injected upstream of the NH3 sensor to evaluate the ammonia sensitivity in the presence other exhaust gas constituents. The sensor response in the exhaust gas environment was compared with laboratory calibrations to assess the relative importance of the varying interferents species on the sensor response to the target species and to develop quantitative calibration curves relevant to the exhaust gas environment.
CO2 Gas Sensing Response of YPO4 Nanobelts Produced By a Colloidal Method
Authors: Michel Carlos R , Martinez Alma H , Rivera-Tello Cesar D
Published: February 2020

YPO4 has been extensively studied as host lattice for luminescence materials; however, little is known about its gas sensor properties. In this work, YPO4 was synthesized by a colloidal method using yttrium nitrate, phosphorous acid and CTAB (as surfactant). The calcination at 500ºC produced single–phase YPO4 nanobelts, having length between 3 and 10 mm, and width between 70 and 250 nm. Impedance measurements were performed on thick films made with the as–prepared YPO4 nanobelts. The results show repeatability for detecting 200 ppm CO2, from 350ºC; however, the response was enhanced at 400ºC. At this temperature YPO4 responded in a wider frequency range, from 100 Hz to 100 kHz. Quantitative detection of CO2, in the range 200 – 800 ppm, was evaluated through a variation of the dielectric constant of the film. Preliminary results of CO sensing displayed a fast response, but also large data scattering and a long term drift were present. According to its response to CO, a p–type semiconductor behavior was noticed.
Facile Detection of Troponin I Using Dendritic Platinum Nanoparticles and Glass Capillary Tube Indicators
Authors: Lee Sanghee , Kwon Donghoon , Yim Changyong , Jeon Sangmin
Published: February 2020

A facile method was developed for the detection of Troponin I (TnI) using dendritic platinum nanoparticles and capillary tube indicators. Dendritic platinum nanoparticles were functionalized with TnI antibodies, which were used to capture TnI in human serum. The captured TnI was conjugated to the inner surface of a glass vial, to which a hydrogen peroxide (H2O2) solution was added. After sealing the glass vial with a screw cap containing a silicon septum, a capillary tube containing a drop of ink was inserted through the septum. The catalytic dissociation of H2O2 to water and oxygen increased the pressure inside the glass vial and raised the ink level in the capillary tube. The ink level increased with the platinum nanoparticle concentration, which is proportional to the TnI concentration. The sensitivity of this assay for TnI in human serum after a 5-min dissociation reaction, detected with the naked eye, was 0.1 ng/mL, which was better than the sensitivity of the conventional colorimetric method using the TMB oxidation reaction under the same experimental conditions. A control experiment using alpha-fetoprotein, interleukin-5, and C-reactive protein revealed that the developed method was highly selective for the detection of TnI.

Figure 1
A Study on Contamination Control of Oxygen Analyzer By Applying Purifier
Authors: Yun Jin Hyuk , Park Se Geun , Lee Young Ho , Lee Che Young , An Jung Su , Cho In Su
Published: February 2020

Rapid thermal annealing(RTA) has been widely used to anneal Si wafer via rapid thermal process chamber. RTA helps the doped ions be activated and reduces the defects in Si lattices by restructuring the bonding [1]. However, when atmospheric air permeates the chamber during RTA process due to the chamber leakage, it generates unwanted silicide on the Si substrate and reduces the electrical properties. It degrades device performance and reliability. For those reasons, oxygen analyzer always monitors the oxygen density in processing chamber during RTA process to prevent any further damage of product quality owing to chamber leakage. However, when oxygen analyzer is contaminated by processed gases, it causes signal delay or low signal which makes it difficult to sense the real oxygen density of chamber [2]. In this paper, to prevent the contamination of oxygen analyzer due to the processed gas, the oxygen purifier was adopted at the inner part of processed gases flow line.

Fig.1 shows various kinds of oxygen density profiles during RTA process depending on normal / delay / low signals, respectively.

Fig.2 shows secondary electron microscope (SEM) image of unused and used for 180 days of porous thimble type oxygen sensor. In mass analysis experiment, O, Si, C, P were detected as contaminants on surface of the used oxygen sensor.

Fig.3 is the gas flow diagram of oxygen analyzer with oxygen purifier.

Fig.4 is average oxygen density during RTA process for 180 days with and without purifier.

 In experimental results, oxygen purifier selectively eliminated the contaminants in processed gas which passes through oxygen sensor. We obtained dramatic improvement of sensor sensitivity deviation nearly 71% than before.

 As a result, More accurate oxygen density monitoring of RTA chamber is possible than before. In addition, oxygen purifier in RTA chamber prevents the quality degradation of semiconductor device immediately when the wafer is exposed to atmospheric air caused by chamber leakage.

Reference

[1]] O.Flament and J.L.Leray, IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 42 NO. 6, DECEMBER 1995

[2]R.RAMADOORTHY,P. K. DUTTA, S. A. AKBAR, JOURNAL OF MATERIALS SCIENCE 38(2003)4271-4283

Figure 1
Biosensing Application of Electrodeposited Nanoparticles As an Electron Transfer Facilitator for Protein Immobilization
Authors: Bayandori Moghaddam Abdolmajid
Published: February 2020

Reactive oxygen species (ROS), including hydrogen peroxide, hydroxyl radical, superoxide anion, and peroxynitrite are involved in some diseases. Among the ROS, H2O2 is the most durable species which is a product of several biological, enzyme-catalyzed reactions. In addition, it is toxic to cellular life and is an indicator of oxidative stress. Therefore, a selective and sensitive method for determination of H2O2is practically important, especially in the field of biosensor fabrication.

Biosensors have attracted attention for use in biodiagnostics [1]. The capability of biosensors will be completely changed by advances in nanoscience and nanotechnology.

Nanostructured metals and metal oxides have various applications in sensors and actuators due to their unique semiconducting and piezoelectric properties [2]. Good biocompatibility, nontoxicity, high surface area, and in particular, chemical stability and fast electron transfer features make them appropriate to apply in various fields.

In this work, cerium oxide nanoparticles (CeO2 NPs) on the electrode surface were electrodeposited. Cerium was firstly electrodeposited at -0.75 V from a 1.0 mM cerium nitrate in ammonium nitrate buffer solution. Afterwards, the electrode was placed into a buffer solution pH 7.0 and was electrochemically passivated. Scanning electron microscopy has been used as diagnostic tools to identify the synthesized CeO2 NPs. For the preparation of biosensor, the hemoglobin immobilized on the CeO2NPs. Immobilized Hb showed an electrochemical redox

 behavior pertained to Hb(Fe(III)-Fe(II)) by direct electron transfer between protein and nanoparticles with a formal potential of -55.5 mV in phosphate buffer solution (PBS).

The anodic charge transfer coefficient (α) and heterogeneous electron transfer rate constant (k
s) were 0.42 and 0.75 s-1, respectively. The prepared biosensor showed a satisfactory sensitivity and reproducibility for H2O2.

 References:

1. Y. Ding, J. Li, R.E. Campbell, Nature Methods, 12, 195 (2015).

2. R.C. Ashoori, Nature, 379, 413 (1996).
Highly Sensitive Detection of Small Molecule Markers By Surface Plasmon Resonance Imaging
Authors: Al Mubarak Zainab Hussain , Premaratne Gayan , Rodenbaugh Cassandra , Krishnan Sadagopan
Published: February 2020

Surface plasmon resonance (SPR) spectroscopy is a label-free method for monitoring binding events among biomolecules in real time and for sensing applications.1 SPR spectroscopy has been widely used in chemistry, biochemistry, and biology research. Our objective is to achieve ultra-low level detection of small molecules that are important markers of cancer disease. Also, we are interested in monitoring pH changes in less abundant biological samples. As we know, pH is an essential parameter in biological, medical and industrial applications. Monitoring the pH level in biological fluids reflects the abnormal conditions in human body.2
,
3We will present our findings on sensitive detection of small molecules and amplification of SPR signals by using chemical indicators and detection by an SPR-array imager

Acknowledgements.This project was supported by Oklahoma State University.

1.         Fasoli, J. B.; Corn, R. M., Surface Enzyme Chemistries for Ultrasensitive Microarray Biosensing with SPR Imaging. Langmuir 2015, 10.1021/la504797z.

2.         Sim, J.; Kwon, D.-S.; Kim, J., Acid-sensitive pH sensor using electrolysis and a microfluidic channel for read-out amplification. RSC Advances 2014, 4 (75), 39634-39638.

3.         Kick, A.; Mertig, M., Characterization of pH-sensitive polymer layers by surface plasmon resonance and quartz crystal microbalance. physica status solidi (a), 2015,

10.1002/pssa.201431604.
Rapid Detection of Pathogenic Bacteria with the Naked Eye Using Magnetophoretic Chromatography Technique
Authors: Kwon Donghoon , Lee Sanghee , Lee Hyeonjeong , Jeon Sangmin
Published: February 2020

A colorimetric method that uses magnetic nanoparticle clusters (MNCs) and magnetophoretic chromatography is developed to detect pathogenic bacteria. Monoclonal Escherichia coli O157:H7 (EC) antibodies were functionalized to MNCs and used to capture E. coli bacteria in milk. After magnetic separation of free MNCs and MNC-EC complexes from the milk, a precision pipette was used to imbibe the E. coli-containing solution, then a viscous polyethylene glycol solution. The MNC-EC complexes were separated from the free MNCs by applying an external magnetic field, then added to a tetramethylbenzidine (TMB) solution. Catalytic oxidation of TMB by Pt produced color changes of the solution, which enabled identification of low concentration of E. coli bacteria with the naked eye.

Figure 1
Enzyme Functionalized Gold Nanoparticles for the Enhanced Electrochemical Detection of Lactate
Authors: Manickam Pandiaraj , Umasankar Yogeswaran , Bhansali Shekhar
Published: February 2020

Lactate is a key molecule in the anaerobic carbohydrate metabolism ­of glucose in muscles. It is primarily considered as the biomarker for tissue oxidative stress. Heavy workout, heart failure, liver disease, drug toxicity and different cancer types causes excess production of lactate in sweat and blood. Therefore the measurement of lactate is important for clinical emergencies, sports and in general medicine. Even though there are reports in literature about lactate sensing, gold nanoparticles functionalized with the enzyme lactate oxidase using disulphide crosslinkers shows promising catalytic activity. In this work, a ultrasensitive biosensor was fabricated by covalently immobilizing lactate oxidase on self-assembled monolayer (SAM) on the gold nanoparticles modified screen printed electrodes (SPE). The sensing mechanism involves the detection of hydrogen peroxide produced during the enzymatic oxidation of lactate. Scanning electron microcopy and cyclic voltammetry were used to characterize the fabricated biosensor. The results show that SAM on uniformly deposited gold nanoparticles provides a favorable microenvironment to retain the bioactivity of enzyme towards lactate detection. The proposed lactate biosensor exhibited good analytical performances including high sensitivity and selectivity with satisfactory stability to electrochemical determination of lactate.
Upconverting Nanoparticles for Sensing
Authors: Vetrone Fiorenzo
Published: February 2020

Rare earth doped nanoparticles have the uncharacteristic ability to (up)convert near-infrared (NIR) excitation light to higher energies spanning the UV, visible, and shorter wavelength NIR regions via a multiphoton process known as upconversion. The ability to stimulate luminescent nanoparticles with NIR light has made possible their use in a plethora of biological and medical applications. In fact, the biggest impact of these upconverting nanoparticles (UCNPs) would be in the field of disease diagnostics and therapeutics, now commonly referred to as theranostics. UCNPs that can be excited by low levels of NIR light but that emit higher-energy emission offer an attractive alternative to conventional fluorophores, both as detectable species for labeling and as energy donors for FRET-based bioassays. UCNPs can be excited selectively in the presence of very high levels of conventional fluorophores. Relative to visible and UV radiation, NIR photons have greater tissue penetration and cause much less damage to the specimens under study because NIR radiation is not absorbed strongly by chromophores commonly found in tissues. Thus, NIR excitation of UCNPs in a biological sample does not give rise to background autofluorescence and consequently detection sensitivity can, in principle, be very high. Upconverting labels also have unique potential advantages as energy donors in FRET-based bioassays because NIR excitation will only excite the donor, and not the acceptor or any fluorescent impurities in the sample. Here, we present the synthesis and surface functionalization of various NIR excited UCNPs and demonstrate their potential use in sensing applications.
Magnetic Optical Microarray Imager for Diagnosing Type of Diabetes in Clinical Matrices
Authors: Singh Vini , Krishnan Sadagopan
Published: February 2020

Diabetes is a metabolic disorder in which body’s inability to produce enough insulin leads to either low (hypoglycemia) or elevated levels of glucose (hyperglycemia). This imbalance in glucose metabolism can eventually lead to serious health problems such as kidney failure, heart disease, blindness, etc. Insulin (a polypeptide hormone) serves as a valuable predictor in diagnosing the type of diabetes and depending upon its levels in clinical matrices, diabetes can be broadly classified as type 1 (< 50 pM) or type 2 (> 80 pM). In type 1 (insulin dependent), the body does not produce enough insulin, while in type 2 (non-insulin dependent), the excess insulin produced is not utilized by the body, thus elevating the glucose levels. 2012 statistics from American Diabetes Association reported 9.3 % of the population to be diabetic and a predicted 25% of population with pre-diabetic conditions. Diagnosis of diabetes, by ultrasensitive detection methods, has therefore become the need, which can detect and measure insulin levels at clinical sites.

We present herein, an ultrasensitive microarray imager, which can detect insulin levels in clinical matrices such as serum and whole blood by an optical tool, surface plasmon resonance. The imager involves an immunoassay utilizing antibody immobilized gold arrays and magnetic particles spiked various insulin concentrations to detect picomolar levels of insulin and diagnose the type of diabetes with high sensitivity. The magnetic microarray insulin imager developed is a promising platform for detecting insulin in serum and whole blood at clinical sites.

Acknowledgements. We are grateful for the financial support by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under Award Number R15DK103386.
Gas Sensing Properties of Hierarchically Structured Zinc Oxide Films By Electrophoretic Deposition
Authors: Chung Yoonsung , Park Hyejin , Lee Eunji , Lee Seokhee , Kim Dong-Joo
Published: February 2020

During last years, the interest in wearable devices has increased significantly. A portable and wearable gas sensor system is one area of interest. Integration of fabric and gas sensors for a wearable breath monitoring system would monitor signature gas from patients’ breath such as acetone gas for diabetes (1), ammonia for renal disease (2), and ethanol for hepatic steatosis (3). Breath sensing system is painless, faster and potentially less expensive than blood tests - and easy to repeat as often as needed, even while patients are sleeping or exercising.

Semiconducting nano-scale metal oxides such as tin oxide (4), zinc oxide (5), and nickel oxide (6) have been used to develop gas sensors. Among them, zinc oxide, which shows n-type behavior, is one of excellent candidates because of its electric properties such as wide band gap and high electron mobility (5). Various morphologies for ZnO nanostructures such as nanorods, nanotubes, and nanowires have been investigated to understand morphology-driven properties. Recently, hollow micro/nanosphere ZnO has been fabricated and its properties have been investigated. Such structure may be applied for dye-sensitised solar cells, photocatalts, high performance electrodes, and gas sensors due to its large surface-to-volume ratio and reduced transport lengths for both mass and charge transport (7).

In this study, the hollow microsphere ZnO particles were prepared by a simple precipitate method. The crystal structure and morphology after calcination are shown in Fig. 1 and Fig. 2, respectively. Electrophoretic deposition (EPD) was then used to construct ZnO layers on flexible substrates. The structural properties of the deposited ZnO layers were analyzed by using SEM, TEM, and XRD.  Then, gas sensing behaviors to detect ethanol and acetone by morphological variation of layers are discussed in detail.

This research was partially supported by Agency for Defense Development (ADD) as global corporative research and Auburn University IGP. 

1.             Zhang, Q., Wang, P., Li, J., and Gao, X. (2000) Biosensors and Bioelectronics 15, 249-256

2.             Moorhead, K. T., Lee, D., Chase, J. G., Moot, A., Ledingham, K., Scotter, J., Allardyce, R., Senthilmohan, S., and Endre, Z. (2008) Computer methods and programs in biomedicine
89, 226-238

3.             de Lacy Costello, B., Ewen, R., Ratcliffe, N. M., and Richards, M. (2008) Journal of Breath Research 2, 037017

4.             Ahn, H., Noh, J. H., Kim, S.-B., Overfelt, R. A., Yoon, Y. S., and Kim, D.-J. (2010) Materials Chemistry and Physics 124, 563-568

5.             Ahn, H., Park, J.-H., Kim, S.-B., Jee, S. H., Yoon, Y. S., and Kim, D.-J. (2010) Electrochemical and Solid-State Letters
13, J125-J128

6.             Dirksen, J. A., Duval, K., and Ring, T. A. (2001) Sensors and Actuators B: Chemical
80, 106-115

7.             Xie, Q., Li, J., Tian, Q., and Shi, R. (2012) Journal of Materials Chemistry
22, 13541-13547

Figure 1
Activation Free SAM-Assisted Silver Electroless Metallization of Textile for Strain Sensor Application
Authors: Molazemhosseini Alireza , Cattarinuzzi Emanuele , Gastaldi Dario , Vena Pasquale , Magagnin Luca
Published: February 2020

Flexible, stretchable and wearable electronic devices are becoming more

demanding due to their facile interaction with human body. These devices can be

easily mount on clothing or directly attached onto skin. Among wearable

electronic devices, highly stretchable and sensitive strain sensors have drawn lots

of attention for monitoring human body motions. There are number of

requirements for a high performance strain sensor including high sensitivity (i.e.,

gauge factor (GF)), high stretchability, fast response, high stability and low

fabrication cost. Personal health monitoring, sport performance monitoring and

human motion capturing for entertainment systems are the most popular

applications for a high performance strain senor.

In this paper, we present a cost effective simple strain sensor fabricated through

silver electroless metallization of commercial polyester fabric. To avoid using

SnCl2 or PdCl2 activation solutions, a silica-like layer was formed on polyester

fabric using an acetone based aminopropyltrimethoxysilane (APTMS) solution

followed by UV irradiation. Once the anchoring sites for later silanization were

developed, a toluene based solution of (3-Mercaptopropyl)trimethoxysilane

(MPTMS) were used to activate the polyester fabric. Silver electroless

metallization was carried out on activated polyester using silver nitrate salt and

glucose as reducing agent. Scanning electron microscopy (SEM) and X-ray

diffraction spectroscopy (XRD) were used to characterize the Ag-coated polyester.

A thin silver coating (<1 μm) with uniform morphology and high purity was

deposited on polyester. The conductive fabric was cut into strips of 5mm

thickness for stretch-conductivity measurements. A micro-tensile machine with

an in-situ confocal microscope was coupled with a digital multimeter (2-point

probing) to investigate strain dependence electrical resistivity. In-situ confocal

imaging was used to investigate the micromechanical mechanisms responsible for

changes in resistivity during stretching. A linear decrease in electrical resistance

was detected by stetching untill it reaches to a platu. The results of stretch–conductivity

measurements suggest the potential application of Ag/Polyester for

strain sensors.

Figure 1
Electrochemical Sensing System for Detection of Tricresyl Phosphate (TCP) in Aqueous Solution and Air
Authors: Chanysheva Alina N , Arugula Mary A , Simonian Alex L
Published: February 2020

The analysis of the air quality in commercial airliners suggests that there is a risk of cabin air contamination with tricresyl phosphate (TCP), which is an anti-wear additive in jet engine oils. TCP is an organophosphate that inhibits vital enzymes, and induces an organophosphorus-induced delayed neuropathy (OPIDN). Large size and high cost complex techniques for TCP detection include gas chromatography, photometric detector, mass spectrometric recognition, and are impractical in an aircraft. The development of a portable TCP sensing device would rely on employing electrochemical methods due to their time and cost effectiveness and possibility to integrate them into a portable device. TCP is not electroactive, and gas samples of TCP are not readily available, thereby electrochemical sensing is accomplished via detecting the products of TCP hydrolysis, cresols. Besides commercially obtained TCP, cresol detection in jet engine oils has been performed. The challenging part of the amperometric detection of such phenolic compounds as cresols is fouling of the working glassy carbon electrode; this can be resolved by electrode modification with poly(3,4-ethylenedioxythiophene)-poly(styrenesulphonate) PEDOT:PSS. Currently, microfluidic devices are potentially important detection systems in environmental monitoring with reduced cost, portability and increase analysis speed. Our goal is to develop a microfluidic based electrochemical system that can provide rapid and reliable determination of TCP in trace levels.
Understanding the Electrochemical Induction of Urea to Ammonia on Nickel Based Catalyst in Alkaline Medium
Authors: Lu Fei , Botte Gerardine G
Published: February 2020

Background

Ammonia is an important chemical used in many fields such as the fertilizer industry and food industry. One popular application of ammonia is to control nitrogen oxide (NOx) emissions and ammonia has been proved to be an effective reductant to remove NOx, this technology is known as selective catalytic reduction (SCR) and is commercially available. Conventionally, urea can be thermally hydrolyzed or converted into to ammonia on demand as shown in eqn. (1).

The electrochemical dissociation of urea has been investigated at the Center for Electrochemical Engineering Research (CEER) for the purpose of producing hydrogen using Ni catalyst, two parallel reactions are found as shown in eqn. (2) and (3).It is proposed that urea to ammonia conversion will be induced with the electrochemically generated NiOOH in alkaline medium. Therefore higher yield of ammonia in eU2A is expected comparing to thermal hydrolysis or urea (THU) under the same conditions. This work will demonstrate that eU2A enables higher reaction rate of ammonia production and experiments will be conducted to understand how the urea to ammonia reaction could be induced through an electrochemical approach.

Methodology

An electrochemical induced urea to ammonia (eU2A) reactor was developed at CEER for the production of ammonia from urea. In the reactor, both the cathode and anode are Ni-based materials and during the experiment, different voltages will be applied to the electrodes at various temperatures. If no potential is applied to these electrodes, the reactor will work at thermal hydrolysis of urea (THU) mode. The alkaline supporting medium used in this investigation is hydroxide (KOH). The produced ammonia in the experiments will be determined using an ion selective electrode (ISE) and the residual urea concentration in the reactors will be monitored by spectrophotometric methods such as UV-vis spectroscopy [6]. Preliminary data has already shown that eU2A mode enables higher generation rate of ammonia compare to THU mode at 70 °C with the feed of diesel exhaust fluid (DEF) in the presence of 7 M KOH. Raman Spectroscopy will be used to monitor the surface change of Ni electrodes and how urea to ammonia reaction occurs heterogeneously. In addition, liquid FTIR will be utilized to identify and quantify the intermediates and products to further understand eU2A process in the reactor.

Figure 1
Agarose Based Biopolymer Gel Electrolyte for Electrochemical Applications
Authors: Singh Rahul
Published: February 2020

A novel electrochemically stable biopolymer gel electrolyte has been reported. To develop biopolymer electrolyte, the solution is comprised of potassium iodide and ionic liquid 1-ethyl-3-methylimidazolium dicyanamide with varying solvents such as distilled water (H2O), Dimethyl sulfoxide (DMSO), Dimethylformamide (DMF) have been added to the Agarose matrix at room temperature and further used in the application of dye sensitized solar cell (DSSC), extra iodine was added in the matrix. Details of the fabrication, characterization and application of the biopolymer gel electrolyte films based on Agarose is given in the paper. Structural, electrical and electrochemical studies have been done on samples which demonstrate promising characteristics of the biopolymer gel electrolyte. The possible conformational/structural changes in the biopolymer due to the formation of a complex nature, entrapment of iodine solution, crystallinity and amorphous nature have been investigated by Fourier transform  infrared (FTIR), Polarized optical microscopy (POM) and X-ray diffraction (XRD). Complex impedance spectroscopy showed the manifold enhancement in ionic conductivity by salt doping. The conductivity maxima were obtained near 60:40 compositions at room temperature. The temperature dependence of electrical conductivity of biopolymer–ionic liquid blends and gel polymer electrolyte follows the Arrhenius behavior. The dielectric studies and ion transport number measurement confirms the ionic conduction in the gel polymer electrolyte. DSSC was fabricated using maximum conductivity and comparative measured values of the FF, Voc, Jsc and efficiency at 100mW/cm were tabulated.

Figure 1
Fabrication of Copper / Single-Walled Carbon Nanotube Composite Plating Films By Electrodeposition
Authors: Kirihata Kyohei , Arai Susumu , Uejima Mitsugu , Hirota Mitsuhito
Published: February 2020

Introduction

Copper has many excellent properties such as high electrical conductivity and good thermal conductivity and ductility, resulting in the wide use of copper plating in the electronics industry. Single-walled carbon nanotubes (SWCNTs) also exhibit attractive characteristics such as stable electrical resistance in the presence of high currents and good thermal conductivity and field emission properties, resulting in their application in a wide range of fields. Cu/SWCNT composites would therefore be expected to have excellent electrical and thermal conductivity properties.Our laboratory previously reported the fabrication of electroless Cu/SWCNT composite plating films, 1)but the fabrication of Cu/SWCNT composite plating films by electrodeposition has not been reported.Here we describe an attempt to fabricate Cu/SWCNT composite plating films with homogeneously distributed SWCNTs using electrodeposition.

Experimental

The Cu/SWCNT composite plating bath comprised 0.1 M CuSO4･5H2O, 0.2 M EDTA･2Na, SWCNTs (Super-growth SWCNTs, Zeon Co.) and dispersants. EDTA･Na was used as a copper chelating agent. A magnetic stirrer, an ultrasonic homogenizer and a mechanical atomizer (Star Burst Labo, SUGINO MACHINE Co.) were used to fragment the SWCNT bundles. The dispersibility of the SWCNTs was evaluated using a particle size distribution analyzer. Electrodeposition was conducted under galvanostatic conditions. A pure copper plate and a phosphorus-containing copper plate were used as cathode and anode, respectively. The morphologies of the composite films were observed by field emission scanning electron microscopy (FE-SEM) and the phase structures of the films were analyzed by X-ray diffraction. The thermal and electrical conductivities of the composite films were also evaluated. In addition, the SWCNTs were quantitatively analyzed.

Results and Discussion

 The results demonstrated that fragmentation of the SWCNTs was improved significantly by using a mechanical atomizer. The content of SWCNTs in the films increased with increasing SWCNT concentration in the plating bath. Fig. 1 shows a surface SEM image of a prepared Cu/SWCNT composite plating film and indicates that the SWCNTs are incorporated relatively uniformly into the Cu film. The diameter of the SWCNTs is ca. 15 nm or less, indicating that the bundles of SWCNTs are highly fragmented.

References

1) T. Osaki, S. Arai, Abstract of ADMETAPlus 2013 Asian Session (2013) 86

Figure 1
The Effect of the Angle of Incident of the Light upon the Optical Reflactance on Silicon Nanowires Grown By Electroless Etching
Authors: Velez Victor H. , Mertens Robert George , Sundaram Kalpathy B
Published: February 2020

Silicon nanowires (SiNW’s) arrays prepared by electroless etching method can significantly suppress light reflection across the visible spectrum [1]. The decrease in reflectivity is evidently due to optical absorption in the silicon. The nanowires scatter the incident light by reflection, refraction, and diffraction processes, and the light will interact with several nanowires until it is either absorbed by a nanowire or the substrate, or is reflected by the sample [2].  However, the Fresnel reflection predicts a large reflectance at a large angle of incidence (AOI) [3]. For effects of comparison, the reflectance versus wavelength data using visible light on SiNW’s grown by eletroless etching in three different concentrations of Hydrofluoric Acid (HF) and Silver nitrate (AgNO3) for different etching times at room temperature have been provided at different AOI values. In general, SiNW’s exhibit low reflectance over a wide range of AOI. SiNW’s etched with high concentration of AgNO3 produce low reflectance. These results are beneficial to the design and fabrication of nanowire-based optoelectronic devices.

In this experiment a Cary 100 UV-Visible Spectrometer was used for reflectance analysis and silicon (Si) wafers were dipped for 15, 30, 45 and 60 minutes at room in an electroless solution prepared in a petri dish containing silver nitrate (AgNO3) and hydrofluoric acid (HF) [4].