bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neuronal Tau Protein Self-Assembly on Gold Surface: Electrochemical Impedance Spectroscopy and Cyclic Voltammetry Studies
Authors: Wallace William , Martic Sanela 
Published: May 2020

Tau is a neuronal protein responsible for microtubule formation [1]. It is also the pathological protein active in the Alzheimer’s Disease (AD) pathway. When Tau begins to aggregate as a result of misfolding, the neuronal cells die due to the lack of microtubule formation and can take on prion-like properties [2]. Therefore, detection of aggregated Tau can serve as a powerful tool in the early diagnosis of AD and dementia related diseases. As has been previously demonstrated, Tau 441 can be detected with an electrochemical immunoassay based on the electrochemical impedance spectroscopy (EIS) by using gold electrode [3]. The EIS was also used to monitor interactions between Tau protein and Heparin [4]. Herein, we describe use of EIS and cyclic voltammetry (CV) to monitor and detect self-assembly of Tau protein on gold electrode. After modifying the surface of the electrode with Tau, the aggregation of Tau was performed using Heparin, as an aggregation inducer. The EIS and CV were measured as a function of Tau or Heparin concentrations, and incubation time and temperature. The control experiments included, Tau-free surface, Heparin-free solution, buffer solution in order to minimize aggregation. The charge transfer resistance, Rct, was determined by fitting the experimental data to the equivalent circuit. The Rct values for Tau-films on gold surface were compared prior and post aggregation. The Rct values were highly dependent on the experimental conditions used and that the electrochemical methods are promising sensing platforms for detection of neurodegenerative biomarkers which undergo self-assembly and aggregation.

References

[1] M.D. Weingarten, A.H. Lockwood, S. Hwo, M.W. Kirschner, A Protein Factor Essential for Microtubule Assembly, Natl. Acad Sci. 72 (1975) 1858–1862.
[2] F. Clavaguera, J. Hench, M. Goedert, M. Tolnay, Prion-like transmission and spreading of tau pathology, Neuropathol. Appl. Neurobiol. 41 (2015) 47–58.
[3] N. Carlin, S. Martic-Milne, Anti-tau antibodies based electrochemical sensor for detection of tau protein biomarkers, J. Electrochem. Soc. 165 (2018) G3018–G3025.
[4] H. Trzeciakiewicz, J. Esteves-Villanueva, R. Soudy, K. Kaur, S. Martic-Milne, Electrochemical characterization of protein adsorption onto YNGRT-Au and VLGXE-Au surfaces, Sensors (Switzerland). 15 (2015) 19429–19442.
Surface Design: Exploiting the Instability of Small Nanoparticles on Metallic Substrates
Authors: Awais Nashwa , Rodriguez Paramaconi , Albrecht Tim 
Published: May 2020

Small metal nanoparticles (NPs) within the size range of 1-3 nm exhibit unique electronic and catalytic properties.1–3 Thiolated nanoparticles have been shown to undergo an entropically driven redistribution of the capping layer with a Ausurface-AuNP system. It has been postulated that different substrate and NP materials may be employed for surface design.4

The aim of this work was to investigate surface structure modification of different substrate-NP combinations, in alkaline media and via their performance in the electro-catalytic decomposition of glycerol (GlyOH).5 Ptsurface-AuNP and Ausurface-PtNP combinations were investigated, by immersion of the surfaces into solutions of the NPs. AuNPs were synthesised using a bottom-up metal reduction6, and PtNPs were synthesised via the cathodic corrosion method.7,8 Electrochemical responses were measured using cyclic voltammetry (CV).
Ptsurface-AuNP resulted in a lower current response, but no change in characteristic Pt peaks within the CV profile, indicating that the AuNPs remain protected by the thiol capping layer on the Pt surface. However, Ausurface-PtNP gave a CV displaying both Au and Pt characteristic peaks (Fig. 1), suggesting there is thiol surface diffusion from the PtNPs into the bulk.
1 S. Hrapovic, Y. Liu, K. B. Male and J. H. T. Luong, Anal. Chem., 2004, 76, 1083–1088.
2 R. Narayanan and M. A. El-Sayed, Nano Lett., 2004, 4, 1343–1348.
3 T. Albrecht, S. F. L. Mertens and J. Ulstrup, J. Am. Chem. Soc., 2007, 129, 9162–9167.
4 E. Pensa and T. Albrecht, J. Phys. Chem. Lett., 2018, 9, 57–62.
5 J. Monzó, Y. Malewski, F. J. Vidal-Iglesias, J. Solla-Gullon and P. Rodriguez, ChemElectroChem, 2015, 2, 958–962.
6 H. Qian and R. Jin, Chem. Mater., 2011, 23, 2209–2217.
7 A. I. Yanson, P. Rodriguez, N. Garcia-Araez, R. V Mom, F. D. Tichelaar and M. T. M. Koper, Angew. Chemie Int. Ed., 2011, 50, 6346–6350.
8 A. I. Yanson, P. V Antonov, P. Rodriguez and M. T. M. Koper, Electrochim. Acta, 2013, 112, 913–918.

Figure 1
Tuning Ion Diffusivity and High-Rate Cycling Performance Via Graphite Exfoliation for Rechargeable Aluminum-Graphite Batteries
Authors: Xu Jeffrey H. , Jadhav Ankur L. , Turney Damon E. , Messinger Robert J. 
Published: May 2020

Rechargeable aluminum-graphite batteries using chloroaluminate-containing ionic liquid electrolytes store charge when chloroaluminate anions (e.g. AlCl4
-) intercalate into graphite1,2. Such batteries utilize electrodes that are globally abundant, low-cost, and safe, while exhibiting ultra-fast rate capabilities, high cycle life and discharge voltages of ca. 2 V. Recently, we elucidated the relationship between graphite structure and macroscopic electrochemical properties such as high-rate performance and the maximum intercalation composition.3 Variable-rate cyclic voltammetry (CV) revealed potential-dependent transport regimes that yield new insights into their ultra-fast rate capabilities. To directly observe the chloroaluminate species intercalated within the graphite electrodes, we performed solid-state 27Al MAS NMR measurements, which revealed their various local environments and populations. To aid the interpretation of the experimental results, DFT calculations were performed to compute the magnitude of 27Al NMR shift contributions due to varying graphite d-spacing, aromatic ring-current shielding, and quadrupolar interactions.
With this increased understanding of the elusive transport mechanism of sterically-bulky chloroaluminates, the current technological objective is to improve the high-rate capacity retention of synthetic graphite electrodes. To tune the ionic diffusivity within the graphite framework, we employed liquid-phase exfoliation and centrifugation to modify the c-axis thickness of the highly-ordered pristine graphites, generating few-layered graphene structures that we characterized using Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). In full-cell electrochemical tests of the exfoliated-graphite electrodes, variable-rate galvanostatic cycling revealed increased capacity retention (~75% @ current density of 960 mA/g, compared to ~43% for non-exfoliated synthetic graphite). Furthermore, galvanostatic intermittent titration technique (GITT) experiments revealed modified ionic diffusivity and ohmic resistances. These results are expected to aid the rational design of graphite electrodes for enhanced performance in aluminum-graphite batteries.
(1) Lin, M.-C.; Gong, M.; Lu, B.; Wu, Y.; Wang, D.-Y.; Guan, M.; Angell, M.; Chen, C.; Yang, J.; Hwang, B.-J.; Dai, H. An Ultrafast Rechargeable Aluminium-Ion Battery. Nature
2015, 520, 324–328.
(2) Sun, H.; Wang, W.; Yu, Z.; Yuan, Y.; Wang, S.; Jiao, S. A New Aluminium-Ion Battery with High Voltage, High Safety and Low Cost. Chem. Commun.
2015, 51, 11892–11895.
(3) Xu, J. H.; Turney, D. E.; Jadhav, A. L.; Messinger, R. J. Effects of Graphite Structure and Ion Transport on the Electrochemical Properties of Rechargeable Aluminum-Graphite Batteries. ACS Appl. Energy Mater.
2019, 2, 7799–7810.
Synthesis of Carboxylated Viologen Cations and Their CT Salts with 1,3-Bis(dicyanomethylidene)Indan Anion
Authors: Yamaguchi Hiroto , Saito Erika , Uno Koya , Yamakado Ryohei , Okada Shuji , Yoshida Tsukasa 
Published: May 2020

Charge transfer (CT) salt by combination of ionic organic donor and acceptor can be an interesting alternative to eliminate large voltage loss in bulk-heterojunction organic solar cells. We have succeeded in synthesis of novel CT co-crystals of 1,3 bis(dicyanomethylidene)indane anion (TCNIH-) donor and N-alkyl substituted viologen cations acceptor to exhibit broad and intense light absorption from visible to NIR. However, it is not straightforward to employ heavily crystallizing organic salts in thin film devices. As an alternative approach to prove the concept, here we propose attachment of the CT pair as a dye to porous oxide semiconductor to dissociate its CT exciton and to harvest it as current in a dye sensitized solar cell (DSSC) fashion. In this work, carboxylated viologen derivatives, N,N’-bis(carboxymethyl)-4,4’-bipyridinium chloride (CE2V) and N-(2-carboxymethyl)N’-methyl-4,4’-bipyridinium iodide (CEMV) (Fig. 1) were synthesized for their attachment to porous ZnO. Their formation of CT salts with TCNIH- has also been studied.
CE2V was synthesized by carboxylation of 4,4’-bipyridinium with acrylic acid and subsequently converted to chloride with hydrochloric acid. CEMV iodide was prepared by monomethylating 4,4’-bipyridinium with methyl iodide and carboxylation with acrylic acid. The synthesized viologen was mixed with TCNIH- in 1 : 2 ratio in water, filtrated and recrystallized in ethanol to identify the structure of the co-crystals. Mesoporous ZnO film prepared by doctor blading was sequentially soaked in ethanolic solution of CE2V or CEMV, and acetone/toluene solution of TCNIH-, to obtain ZnO/viologen/TCNIH hybrid structure in the end. The attachment of respective molecules was checked by UV-vis absorption both for the film samples and the ammonia solution dissolving the entire film.
Formation of CT salts was confirmed by significant broadening of the absorption towards NIR as compared to that of the Na+ salt of TCNIH- (Fig. 1), so that the presence of the carboxylic acid anchor group in viologens do not disturb their intimate ionic interaction with TCNIH-. Triclinic single crystalline structure of the co-crystals was identified by XRD. CE2V and CEMV were adsorbed at high concentrations (500 μM and 500 μM, respectively) onto ZnO, so that the carboxylic acid group indeed acted as an anchor for their attachment to ZnO. The anionic TCNIH- in fact could directly be adsorbed onto ZnO to yield bluish films, whose spectrum, however, differed from those with pre-attached viologens (Fig. 1). Those of ZnO/viologen/TCNIH indicate clear broadening towards red, which can be attributed to the formation of CT pairs. Photoelectrochemical analysis in the presence of suitable redox system is expected to result in photocurrent from the CT state.

Figure 1
Synthesis of Poly-Neutral Red and Its Electrocatalytic Property Towards CO2 Reduction Reaction
Authors: Huang Xin , Harada Yuya , Nishiumi Nobuyuki , Coskun Halime , Aljabour Aziz , Stadler Philipp , Yoshida Tsukasa 
Published: May 2020

Concentration of carbon dioxide (CO2) in the atmosphere has steadily increased since industrial revolution. Despite the recent significant cost reduction of renewable electricity by solar and wind, their intermittency hinders the total shift to renewable energy. It is urgently needed to develop technologies for fast conversion of electrical energy into storable chemical energy by electrolysis, e.g., by water splitting and CO2 reduction. Stable and high-performance electrocatalysts are essential but must be developed without depending on precious metals for the real use and sustainability of the technology.
Recently, we have demonstrated high and stable electrocatalytic properties of conductive organic polymers, such as polydopamine (PDA) and polyguanine (PGA) for hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR)1,2). Hydrogen bonding N and O atoms introduced to these polymers are expected to stabilize the reaction intermediates for their high catalytic activities. In this study, a phenazine dye, neutral red (NR) was employed as the monomer to obtain a metal-free catalyst. NR bears many amino functions to make it electropolymerizable just like poly-aniline (electropolymerization deposition, to be called EPD). Also, oxidative chemical vapor deposition (oCVD) was employed to obtain PNR. Synthesis, characterization and comparison of the catalytic activities of PNR by EPD and oCVD are discussed.
EPD of PNR onto carbon felt (CF) was carried out by cycling potential between -1 and +1 V vs. Ag/AgCl for 100 cycles in an aqueous solution containing 0.2 mmol/L NR and 0.5 mol/L KNO3 (pH 5) at 50 mV/s. oCVD of PNR was performed in a three-zone quartz tube furnace under N2 flow, while setting the temperature for NR, sulfuric acid and CF at 375, 220 and 100ºC, respectively, for 240 min. PNR-modified as well as bare CF electrodes were measured under N2 and CO2 in a 1 M KNO3 (pH 7) for their catalytic activities for HER and CO2RR.
While bare carbon felt (CF) electrode does not show any catalytic activity towards CO2RR, showing about -3 mA cm-2 current at –1 V vs. Ag/AgCl, supposedly dominated by that for HER, the PNR coated CFs show enhanced current (Fig. 1a). That by EPD gives about -5 and -6 mA under N2 and CO2, respectively, indicating its moderate catalytic activity for HER and CO2RR. PNR prepared by oCVD, on the other hand, gives -6 and -12 mA, to demonstrate its superior activity, especially for CO2RR. Chronoamperogram measured during long term electrolysis for 17 h at the oCVD PNR electrode indicates reasonable stability of the catalysis (Fig 1b). These results already nicely confirm catalytic activity of PNR for its conductivity and hydrogen-bonding ability.

References:

1. H. Coskun et al., Sci. Adv., 2017, 3, e1700686.
2. H. Coskun et al., Adv. Mater. Interf., 2019, 10, 1901364.

Figure 1
Phosphoric Acid Doping Levels in PBI-Based Membranes for the Application in High Temperature Fuel Cells: A Comprehensive Evaluation of Different Measurement Techniques
Authors: Arslan Funda , Böhm Thomas , Kerres Jochen A. , Thiele Simon 
Published: May 2020

Alternative energy studies are crucial since the energy demand in the world increases rapidly. Nowadays, due to limited reserves of fossil fuel and CO2 emission, environmentally green energy is the most promising and desirable energy source for the future. In this context, fuel cells becoming one of the most promising alternative energy conversion devices. Especially polymer electrolyte membrane fuel cells (PEMFCs) are of great research interest.
Theoverall efficiency of PEMFCs is strongly influenced by the polymer membrane placed between the anode and cathode. The current state-of-the-art perfluorosulfonic acid (PFSA)-based membranes used in PEMFCs, such as Nafion, rely on the presence of water as the charge carrier for an efficient proton conductivity, and operate usually only up to 80 °C. Therefore, Nafion-based systems require water management, which can be avoided by using polybenzimidazole (PBI)-based membranes instead; operating at higher temperatures (up to 180 °C). Nevertheless, pristine PBI-based membranes need to be doped with acid in order to produce a highly proton conductive system. In this context, phosphoric acid (PA) is the most promising acid as the proton conduction medium. PA doping levels are essential as they govern conductivity, while an excess acid doping can deteriorate mechanical and thermal properties of the membrane. Therefore, the optimization and determination of the doping levels are important for high temperature polymer electrolyte membrane fuel cells. Commonly, titration or weighing of the membranes are used for the determination of the acid doping level, but they suffer from low accuracy and precision.
In this work, the acid doping level (ADL) of PBI-based membranes was studied by Raman, impedance, and energy-dispersive X-ray (EDX) spectroscopy, gravimetric and thermogravimetric analysis, and titration. The use of Raman spectroscopy is of great interest due to its non-destructive nature. It can be performed on the sample prior or post application in a HT-PEMFC. This study presents a new measurement protocol for ADLs by using Raman spectroscopy, which is a helpful tool for choosing the optimal ADL for a PBI-based membrane. Thus, the manufacturing process of high temperature fuel cells and their overall efficiency can be optimized.

Keywords: Acid Doping Level (ADL), Fuel Cells (FCs), High Temperature (HT), Polymer Electrolyte Membrane (PEM), Phosphoric Acid (PA), Polybenzimidazole (PBI)
Characterization of Europium Doped Silicon Oxide, Silicon Oxynitride, and Silicon Nitride Films Prepared By Integrated Ecr-PECVD and Magnetron Sputtering
Authors: Azmi Fahmida , Gao Yuxuan , Khatami Zahra , Mascher Peter 
Published: May 2020

The compatibility of Si-based light sources with mainstream metal-oxide semiconductor technology has become very interesting over the past decades due to their potential in integrated optoelectronics circuits of monolithic Si [1]. A very promising approach to improve the light emission from silicon-based materials is doping silicon with rare earth elements, and numerous research is involved in this field [1]. However, there are only a few works on europium (Eu) doped silicon-based matrix. In this work, Eu doped silicon oxide, silicon oxynitride, and silicon nitride thin films were deposited on P (100) Si substrates using integrated electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) and magnetron sputtering. Silane (SiH4), oxygen (O2), and Nitrogen(N2) gases were used as precursors and solid Eu as the sputtering target. The integrated ECR-PECVD and sputtering system allows tunable and highly consistent Eu doping concentration, better control of the layer stoichiometry along with less hydrogen incorporation in the deposited film compared to conventional CVD systems [2]. Several thin films were investigated using room temperature photoluminescence (PL) and X-ray diffraction (XRD). A detailed investigation of the effect of annealing on the PL was performed. The annealing temperature was varied from 500 OC to 1200 OC in nitrogen and a mixture of nitrogen and hydrogen atmospheres. It was observed that the intensity of the PL spectra increased with increasing annealing temperature. Besides, the hydrogen passivation effect has been studied in this work, which shows that hydrogen passivation increases the intensity of the peak. Based on the XRD measurements, we have found that the amorphous silicon oxide structure changes to a crystalline structure by adding nitrogen in the film. Interestingly silicon oxynitride and silicon nitride films do not show any luminescence at room temperature. The influence of the precursors' gases in the atomic percentage of the thin films was analyzed by Rutherford Backscattering spectrometry (RBS). In addition to it, the thickness and the index of refraction were characterized by variable angle spectroscopic ellipsometry (VASE).
Reference:
1. Lin, Z., Huang, R., Wang, H., Wang, Y., Zhang, Y., Guo, Y., ... & Li, H. (2017). Dense nanosized europium silicate clusters induced light emission enhancement in Eu-doped silicon oxycarbide films. Journal of Alloys and Compounds, 694, 946-951.
2. Miller, J. W., Khatami, Z., Wojcik, J., Bradley, J. D. B., & Mascher, P. (2018). Integrated ECR-PECVD and magnetron sputtering system for rare-earth-doped Si-based materials. Surface and Coatings Technology, 336, 99-105.
(Invited) Electrochemical Production of Graphene and Controlled Assembly of 3D Graphene Electrodes for Energy Storage Applications
Authors: Lee Michael J , Lee Hoyoung , Lee Kyungbin , Lee Byeongyong , Lee Seung Woo 
Published: May 2020

Graphene has been intensively studied for electrode material for electrochemical energy storage devices utilizing its high electrical conductivity and high surface area. Recently introduced electrochemical exfoliation process has many advantages over conventional chemical methods, including low-cost, simple operation, fast production-rate, and in-situ functionalization. In particular, anodic electrochemical exfoliation process is one of the promising methods for fast and simple production of graphene at low cost.
In this presentation, we will first discuss the detailed mechanisms of the electrochemical exfoliation process of graphite into graphene using sulfate containing electrolyte systems. We systematically monitored the structural changes in graphite and associated gas formation during the electrochemical exfoliation process, revealing that water molecules are the main source of gaseous species for the effective exfoliation of graphite into graphene. Next, we will introduce our recent efforts to fabricate 3D structured graphene anodes for Li-, Na-, K-ion batteries. Moreover, we evaluated the temperature-dependent performance of 3D graphene anodes, demonstrating their superior charge storage performance in extreme cold environments.
(Invited) Carbon Nanotubes As an Effective and Stable p-Type Contact for Perovskite Solar Cells
Authors: Habisreutinger Severin N. , Noel Nakita K. 
Published: May 2020

The enormous strides researchers have made in advancing perovskite-based photovoltaics in the past few years are fueling the dream of a rapid entry of this highly promising technology into the global energy market. This seems like serendipitous timing since solar power has gained an enormous momentum over the past decade exceeding all projections. This expansion in solar power is driven by an increasing understanding that climate change requires immediate action, in particular with regards to power generation; and simultaneously, the price for photovoltaic modules has remarkably quickly fallen to make solar power generation competitive vis-à-vis conventional technologies.
Compositional tuning of the perovskite absorber has led to immense improvements in stability and efficiency of perovskite solar cells leading to a certified efficiency of over 25% for a single-junction laboratory device. The successful transition of a photovoltaic technology from the lab into the field requires, however, two additional important parameters aside from efficiency which are essential for real-world deployment: stability and scalability.
We propose using single-walled carbon nanotubes (SWCNTs) as an alternative p-type layer for future application in perovskite solar cells.
Carbon nanotubes combine several highly attractive characteristics such as chemical inertness and mechanical resilience with intrinsically high charge-carrier mobilities endowing them with a unique potential for a much more stable dopant-free charge-selective contact. Furthermore, the SWCNT deposition techniques for large-scale use, such as spray coating, are already well-established opening clear avenues for direct implementation in a real-world industrial setting.
We demonstrate that a cascade-like transfer extraction through SWCNTs can minimize photovoltage losses by suppressing non-radiative recombination. By further improving the absorber quality, the voltage losses in solar cells can be reduced to around 340 mV which is comparable to conventional III-V semiconductor-based photovoltaics.
By further enhancing the selective charge extraction at the perovskite-SWCNT interface through interfacial charge transfer doping, we achieve steady-state efficiencies approaching 22% for alloyed narrow bandgap perovskites, illustrating the versatility and excellent performance of SWCNTs as contact material.