bluuebunny/crossref_metadata_2025_split huggingface dataset:
Manganese Functionalized Graphene As a New Platform for Peroxynitrite Sensing
Authors: Kalil Haitham , Bayachou Mekki 
Published: February 2020

Peroxynitrite (PON, ONOO−) is a powerful oxidizing agent generated in vivo by the diffusion-controlled reaction of nitric oxide (·NO) and superoxide (O2
·−) radicals. Peroxynitrite levels accumulate under oxidative stress. Elevated peroxynitrite levels are associated with chronic inflammatory disorders including neurological and vascular diseases, as well as a number of other pathophysiological conditions. The accurate detection of this analyte in biological systems is of paramount importance, not only to understand the genesis and causes of ailment at the tissue/cellular level, but also to suggest and design potential therapeutic routes.
In the past, we studied the sensitivity of carbon electrodes modified by polymerized hemin (iron protoporphyrin) as standalone and in combination with conductive polymer PEDOT (3,4-ethylendioxythiophene). These polymerized surfaces have been used as platforms for amperometric measurements of peroxynitrite both in still solutions and under flow conditions. More recently, we extended this line of research to the use of hemin functionalized graphene as a catalytic platform for PON oxidative detection.
In this work we explored and discussed the sensitivity of manganese-based interfaces for peroxynitrite amperometric determination. Surfaces of electrodeposited manganese (Mn), manganese-graphene, and manganese-decorated graphene/hemin-based nanostructures were formed on glassy carbon electrodes as well as on carbon fiber microelectrodes. The effect of graphene on the electrodeposition of Mn was investigated by cyclic voltammetry. We tested these interfaces for electro-catalytic sensing of peroxynitrite in solution using chronoamperometric technique. The morphology of the prepared manganese interfaces was characterized using scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDXA), Ultra-Violet/Visible (UV/Vis), X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy. The results showed that manganese-functionalized hemin/graphene enhances peroxynitrite detection and quantification compared to hemin/graphene-only interfaces. We noticed that there is a synergistic effect of the presence of graphene with manganese nanoparticles in the prepared materials. We compared and contrasted on how graphene nano-sheets affect the electrochemical behavior of hemin-modified electrodes in the absence and presence of manganese nanoparticles. In conclusion, we found that the incorporation of manganese influences the sensitivity of PON-sensing hemin/graphene platforms.
Defect-Free Amorphous Indium Gallium Zinc Oxide Deposition Process By Magnetic Field Shielded Sputtering
Authors: Lee Dong Hyeok , Kim KyungDuck , Hong MunPyo 
Published: February 2020

The amorphous InGaZnO (a-IGZO) is widely accepted as a promising channel material for thin-film transistor (TFT) applications owing to their outstanding electrical properties [1, 2]. However, a-IGZO TFTs have still suffer from their bias instability with illumination [1-4]. Up to now, many researchers have studied the sub-gap density of states (DOS) as the root cause of instability. It is well known that defect states can influence on the performances and stabilities of a-IGZO TFTs. The defects states should be closely related with the deposition condition, including sputtering power, and pressure. Nevertheless, it has not been reported how these defects are created during conventional RF magnetron sputtering. In general, during conventional RF magnetron sputtering process, negative oxygen ions (NOIs) can be generated by electron attachment in oxygen atom near target surface and then accelerated up to few hundreds eV by a self-bias; at this time, the high energy bombardment of NOIs induce defects in oxide thin films. Recently, we have reported that the properties of IGZO thin films are strongly related with effects of NOIs which are generated during the sputtering process [5]. From our previous results, the electrical characteristics and the chemical bonding states of a-IGZO thin films were depended with the bombardment energy of NOIs. And also, we suggest that the deep sub-gap states in a-IGZO as well as thin film properties would be influenced by the bombardment of high energetic NOIs during the sputtering process.
In this study, we have studied the gate bias instability and their density of states (DOSs) of a-IGZO TFTs as depending on the bombardment of NOIs during conventional magnetron sputtering. Finally, we will introduce our novel technology named as Magnetic Field Shielded Sputtering (MFSS) process to prevent the NOIs bombardment effects and present how much to be improved the instability of a-IGZO TFTs by this new deposition method.
1. M.G. Kim, M.G. Kanatzidis, A. Facchetti, and T.J. Marks, Nat. Mater. 10, 382 (2011).
2. K.K. Banger, Y. Yamashita, K. Mori, R.L. Peterson, T. Leedham, J. Rickard, and H. Sirringhaus, Nat. Mater. 10, 45 (2011).
3. M.D.H. Chowdhury, P. Migliorato, and J. Jang, Appl. Phys. Lett. 98, 153511 (2011).
4. X. Xiao, W. Deng, S. Chi, Y. Shao, X. He, L. Wang, and S. Zhang, IEEE Trans. Electron Devices 60, 4159 (2013).
5. D.H. Kim, J.N. Jang, S.B. Yoon, and MunPyo Hong, Appl. Phys. Express 7, 031401 (2014).
Electrochemical Determination of Aluminium By Oxidation of Dopamine Using Platinum Nanoparticles on MWCNT As Sensor
Authors: Félix-Navarro Rosa María , García-Tapia Karelid , Reynoso-Soto Edgar Alonso , Silva-Carrillo Carolina , Lin-Ho Shui Wai , Paraguay-Delgado Francisco 
Published: February 2020

Aluminum (Al) is the most abundant metallic element and constitutes about 8% of the earth's crust. The aluminium is related to different neurological disorders like Alzheimer's, bipolar, depression, etc. As well as anemia, also reduces the absorption of calcium causing pain, deformities and broken bones.1-2 The development of nanotechnology has led to a growing interest in the study and design of nanosensors, in order to improve selectivity, limit of detection, reproducibility and durability of the current sensors.4-5

In this paper is repoted the preparation of hybrid material based on platinum nanoparticles (NP Pt) on multiwall carbon nanotubes (MWCNT) prepared by inverse microemulsion method using sodium dodecyl sulfate (SDS) as surfactant in a mixture of hexane/isopropanol/water. The hybrid material was characterized by transmission electron microscopy (TEM). The hybrid material showed small spherical nanoparticles with average sizes of 2.15±0.54 nm, well as thermogravimetric analysis a load of 20% platinum.
The NP Pt/MWCNT hybrid material use for determining Al+3 using dopamine as a chelating molecule for the indirect determination of the aluminum by differential pulse voltammetry in neutral medium. Under optimal experimental conditions it was determined the sensitivity of the NP Pt/ MWCNT sensor was 27.75 μA/ppb Al+3 with a linear response range from 0 up to 15 ppb Al3+.
References
1. C. Exley, Environ Sci: Process Impacts, 15, 1807, (2013).
2. WHO (World Health Organization), Safety evaluation of certain food additives and contaminants, p.173, WHO, Geneva, 2007.
3. R. L. McCreery, , Chem. Rev. 108, 2646 (2008).
4. A. Hayat, G. Catanante, J. Louis Marty, Sensors, 14, 23439 (2014).

Figure 1
The Analysis of Prussian Blue Bonding on the Electrochemically Functionalized Carbon Nanotubes
Authors: Je Lisa , Belli Stuart , O'Connor Thomas J. 
Published: February 2020

We have explored the pseudocapacitance of Prussian blue (PB) modified carbon nanotube electrodes.The carbon nanotubes (CNT) are deposited by chemical vapor deposition (CVD) onto a nickel catalyst that had been electroplated onto a metal base electrode. The nanotubes were then characterized by Raman spectroscopy and cyclic voltammetry. Prussian blue was electrochemically deposited onto the CNT electrode from a solution of K3Fe(CN)6 by repeated cycling between -0.1 V and 1.0 V verses a Ag/AgCl reference electrode. The ferricyanide redox couple occurs at about 0.5 V while the deposition of PB was seen as a growing redox couple at about 1.0 V see Figure 1.
Optical imaging of the CNT electrode showed a distinct blue-green tint that together with the cyanide stretch in the Raman spectrum gave evidence that PB had been deposited, see Figure 2. This suggests that this electrochemical technique utilizing CV is a viable method to functionalize CNT electrodes. Electrodes thus modified show increased pseudocapacitance compared to the unmodified CNT electrodes. The exact structure and location of the PB bonding is unknown and was the focus of this study. Scanning electron microscopy was utilized to image the electrode surface after each step of the process in order tostudy PB bonding onto the CNT electrode.
Figure 1: A CNT electrode undergoing functionalization in ferricyanide solution. The peaks growing in are thought to be Prussian blue being deposited onto the carbon nanotubes.
Figure 2: Raman spectra of functionalized and unfunctionalized carbon nanotube electrodes. The G and D bands due to the nanotubes are seen in both spectra at the expected 1587 and 1340 cm-1, respectively. For the functionalized electrode, additional peaks in the 2100 cm-1 range due to cyanide stretching are observed.

Figure 1
(Invited) GaAs Quantum Dots in Gap Nanowires: Growth and Luminescence
Authors: LaPierre Ray R , Kuyanov Paul , Boulanger Jonathan 
Published: February 2020

Nanowires are rod or whisker-like structures with length on the order of microns and diameter from tens to hundreds of nanometers. They represent a new class of three-dimensional materials, and the next step in the evolution of conventional two-dimensional thin films, quantum wells, or heterostructures. Nanowires are typically fabricated by the assistance of foreign metal catalysts, such as Au, that collect deposited material, resulting in localized growth of nanowires. However, the use of foreign metal particles can result in contamination of the nanowires and reduction in the carrier lifetime, which degrades device performance. In the present work, we present the self-assisted growth of GaP nanowires by molecular beam epitaxy, using Ga droplets as a seed particle without the use of any foreign metal catalysts. Growth of the nanowire occurs by selective-area epitaxy using a patterned array of holes in an SiOx mask. The holes collect Ga adatoms forming a Ga droplet that seeds the nanowire growth. The size of the Ga droplet can be controlled by a novel evaporation process, resulting in ultra-thin nanowire structures. GaAs heterostructures were introduced into the GaP nanowires during growth resulting in quantum dots. The quantum dots are encapsulated in GaP, resulting in passivation of the QD surfaces. Photoluminescence emission was observed from the QDs in the visible range. The emission wavelength is tunable by the size or composition of the QDs. This process results in controlled luminescence emission with application in single photon sources, light emitting diodes, or laser diodes.
Material Conversion of GaAs Nanowires
Authors: Nishioka Kohei , Ishikawa Fumitaro 
Published: February 2020

We propose material conversion of compound semiconductor GaAs nanowires for its extension of their functions and structures. As utilized for the oxidation technique of AlGaAs within GaAs-based vertical cavity surface emitting lasers for the electrical and optical confinement, such kind of material conversion enables functions which cannot be utilized without the introduction of contrastive materials. If we can convert nanoscale materials with keeping its structure, which can widely extend the tunability of wide range of materials properties such as electric, dielectric, as well as mechanical properties. Recently, we proposed precise selective oxidations to GaAs/AlGaAs heterostructure, enabling the synthesis of semiconductor/oxide composite GaAs/AlGaOx and full-oxide and finely structurally controlled GaO/AlGaOx nanowires. Characteristically, the composite nanowire provide specific white luminescence, which cannot be achievable for conventional compound semiconductors without the material conversion for nanoscale oxides[1,2] To further develop the material conversion technique for GaAs nanowires, we investigate two-step materials conversion consisting of the thermal treatment within liquid In, and nitrogen gas flow under atmospheric pressure. By the technique, we show the conversion of GaAs nanowire constituents to In, oxygen, as well as silicon from the substrate, eventually forming Ga(In)As and In(Si)O nanowires.
We used GaAs nanowires having about 100 nm diameter with 5mm length on Si substrate, synthesized by molecular beam epitaxy. The conversion was carried out in a furnace introducing nitrogen gas under atmospheric pressure. During the conversion, the nanowires were dipped into a custom-made qualz pod with In melt, which was weighted down with qualz cap. By heating the sample up to 600oC for an hour, we observe the introduction of In into the GaAs nanowire. We then carry out the heating without using the pod but just pasting the In onto the substrate surface having GaAs nanowires. As a result, the wire was converted from GaAs nanowire to InO with the constituent of substrate Si. These results suggest a possible technique realizing the introduction of wide range functionalities into the optically active and electrically high-speed compound semiconductor GaAs nanowires.
[1] H. Hibi, M. Yamaguchi, N. Yamamoto, and F. lshikawa, Nano Lett. 14, 7024, 2014.
[2] F. Ishikawa and N. Yamamoto, ECS transactions, 69, (In press), 2015.
100k Cycles and Beyond: Extraordinary Stability for Au@MnO2 core@Shell nanowires Imparted By Gel Electrolyte
Authors: Le Thai Mya , Penner R. M. , Thesma Chandran Girija 
Published: February 2020

Nanowire electrodes for batteries and super-capacitors can produce superior power relative to films of the same materials. But the Achilles Heel of nanowires is their susceptibility to degradation and failure. This is particularly true for materials that employ Faradaic reactions requiring ion insertion/deinsertion for energy storage. Here we describe the preparation of arrays of ultra-long (2.5 mm) Gold@δ-MnO2, core@shell nanowires. Gold@δ-MnO2 nanowires are prepared on glass surfaces using a variant of the Lithographically Patterned Nanowire Electrodeposition process. All nanowire capacitors prpared from these ultra-long nanowires produce state-of-the-art metrics for energy and power in MnO2-based systems, but they demonstrate irreversible capacity loss exceeding 20% in ≈4000 - 8000 cycles. This cycle stability nevertheless represents the state-of-the-art for MnO2 based electrodes. Now we have discovered that the addition of poly(methylmethacrylate)(PMMA) to the propylene carbonate (PC) electrolyte extends cycle stability to 100,000 cycles and beyond. Other energy storage metrics of these systems are not degraded by the PMMA. In this talk, I describe the results of our experiments, and present data on the charactrerization of these Gold@δ-MnO2 nanowire systems in PC electrolyte and PC electrolyte containing PMMA, before and after cycling.
Electrochemical Fabrication of 3D Gradient Refractive Index Micro-Optics
Authors: Braun Paul V 
Published: February 2020

Via electrochemical etching of silicon, followed by materials conversion, 3D gradient refractive index micro-optics were formed. Elements including flat lenses, Bragg mirrors, polarization sensitive optical splitters and structures with nearly arbitrary refractive index distributions were formed with a particular focus on micro-optics important for solar energy harvesting. The conversion from silicon to silica and titania enabled the optics to operate in the visible with minimal loss, something particularly important for solar energy harvesting applications.
Electrochemical Upgrading of Bio-Oil
Authors: Diaz Luis A. , Lister Tedd E. , Padmaperuma Asanga , Lilga Michael , Job Heather , Lemmon Teresa , Tran Quan 
Published: February 2020

Alternative fuels derived from biomass “biofuels” are an attractive alternative to substitute limited and non-renewable sources of energy. Bio-oil generated from the pyrolysis of biomass is a complex micro-emulsion with high levels of oxygen and acids, which lead to increases in viscosity, phase separation, and degradation as it ages. This instability of bio-oil complicates storage, transportation and downstream processing. Currently, catalytic upgrading of is performed to stabilize the bio-oil by means of the reduction of the oxygen content. However, the current hydrothermal upgrading technologies operate at high hydrogen pressures, up to 2000 psi, and temperatures that lead to coke formation in the catalyst bed. A milder method is needed to convert unstable carbonyl species to more stable alcohols as an intermediate step before hydrothermal treatment.
In this work an electrochemical approach has been investigated for the upgrading of bio-oil at low temperature using a proton exchange membrane (PEM) electrolyzer. The PEM electrolyzer was selected for performing the conversion as it avoids the need to add electrolyte to the oil which would cause phase separation and require later removal. Work has primarily focused on using cation-exchange membranes where protons are generated in the anode and travel through the membrane to the cathode surface. The hydrogenation of the bio-oil at the cathode competes with hydrogen evolution. Work has focused on using various electrode cell architectures and electro-catalysts to reduce both model compounds and actual pyrolysis oil derived from wood.
While further work is needed, promising results have been observed with reduction of carbonyl groups and phenolic rings. A description of the work conducted and discussion of the results will be presented.
The Role of Renewable Hydrogen in Sustainable Manufacturing
Authors: Ayers Katherine E 
Published: February 2020

Reduction of carbon dioxide emissions and other pollutants is a critical need worldwide for sustainability. Transportation is one major contributor of greenhouse gas emissions, and there is significant debate over the relative merits of fuel cells vs. batteries as the energy system. Batteries provide improved energy efficiency, but do not provide the driver with the same experience in range and fueling time as the fuel cell option. However, a major drawback for fuel cells is the lack of hydrogen fueling infrastructure. While even hydrogen from natural gas provides a well to wheels emissions benefit, hydrogen from non-carbon based sources has had challenges in being viewed as a cost effective option, largely because the electricity cost dominates the analysis.
While much attention has been directed towards hydrogen as a transportation fuel, it should also be remembered in developing global solutions that hydrogen is also a major world chemical feedstock. Most of the world's hydrogen goes to hydrogenation of fats and oils, and ammonia generation. Production of ammonia is one of the world's largest consumers of energy, largely based on the energy consumed in the generation of hydrogen from natural gas. The Haber Bosch process occurs at high pressure (150–300 atm) and high temperature (400°–500°C), and accounts for about 1-2% of the world's annual energy consumption (5% of the world's natural gas). In addition, the fossil fuel reforming of natural gas to hydrogen results in substantial carbon dioxide (CO2) emissions.
Hydrogen production from water electrolysis requires more energy per kilogram of hydrogen than natural gas reforming (when only considering the generation step), but has the option of using renewable energy as the primary energy source. In addition, polymer membrane-based electrolysis is very well suited for load-following applications. These devices can therefore operate primarily on excess electricity from what would otherwise be stranded renewable resources. Finally, because an electrolyzer is a flow cell, like a flow battery, the reactants and products are stored separately from the electrochemical device, which is more attractive for very long charge times. Higher capacity can be added simply by adding storage tanks. This talk will discuss the current status of electrolysis and challenges in bridging the gaps between present commercial status and future optimized solutions in this context.
In addition, an analysis of energy of manufacturing for electrolyzers themselves shows opportunities for improvement. One energy intensive process is the manufacture of the membrane electrode assembly. The energy required to deposit and bond the catalyst to the membrane can be reduced through advanced manufacturing processes, and use of less catalyst reduces the original refining energy, which is also a significant contribution. Progress in reduction of manufacturing energy will also be briefly discussed.

Figure 1
Nafion: A Thermodynamic Sketch
Authors: Leddy Johna , Rathuwadu Nadeesha 
Published: February 2020

Nafion®, the most commonly employed ion exchange polymer, serves as both a separator and a sensor platform. After more than 30 years of use, properties of Nafion have been measured and various models of Nafion have been proposed.
Many properties of Nafion have been measured as a function of water content and hydration [1]. This includes selectivity of alkali metal cations over protons, glass transition temperatures, decomposition temperatures, mobilities, transport numbers, conductivity, solvent swelling, gas solubilities, mechanical properties, and density.
Here, a simple thermodynamic sketch of Nafion is presented that characterizes its varied properties.
Density specifies water content that varies with the intercalated cations in both Nafion membranes and recast Nafion films [2,3]. Nafion is a known biphasic material composed of interconnected solvent filled domains and fluorocarbon domains. Because the dielectric constant reflects the ability of a matrix to support ionization, ions are found in the solvent filled domains. From the density and equivalent weight of Nafion, ion concentrations in the solvated domains are found.
Electrochemical potential μj
α for the ions is calculated based on the ionic strength in the solvated domains.
μj
α = μj
α,0 + RT ln aj
α + zjFφ = μj
α,0 + RT ln Υj
αcj
α + zjFφ
Because common models such as Debye Hückel, extended Debye Hückel, and Davies are restricted to ionic strengths well below those found in the solvated domains of Nafion, later models such as those of Stokes and Robinson are used to derive an expression for the activity coefficient.
The activity coefficient equation is used to fit literature data for selectivity, solubilities, swelling, and thermal, transport, and mechanical properties. Self consistent values for waters of hydration (and solvent molecules of solvation) are found for monocations across the literature on numerous measured properties reported as a function of solvent content.
This thermodynamic sketch of Nafion allows calculation of Nafion properties based on activity coefficients and electrochemical potential. The model also provides a practical means for design of Nafion materials with selected properties.

References

[1] J. Leddy, Modification of Nafion Membranes: Tailoring Properties for Function, ACS Symposium Series, Nanomaterials for Energy, edited by J. Liu, S. Bashir, and L.-D. Chen (2015).
[2] K.J. Oberbroekling, D.C. Dunwoody, S.D. Minteer, J. Leddy, Anal. Chem. 2002, 74, 4794-4799.
[3] L.A. Zook, J. Leddy, Anal. Chem. 1996, 68, 3793-3796.