bluuebunny/crossref_metadata_2025 huggingface dataset:
China’s Promoting of Authoritarian–Westphalian Democracy and Its Implications for the Liberal International Order
Authors: CHO YOUNG CHUL
Published: September 2024

China is seen as undemocratic, illiberal, and autocratic by many who live outside it, and the terms “democracy” and “China” are often difficult to reconcile. Nonetheless, Beijing has been actively employing the concept of democracy both domestically and on the international stage in recent years. This paper aims to critically examine how Beijing conceptualizes and advocates for democracy at home and abroad. It also endeavors to explore the implications for the country’s domestic and global governance, particularly in relation to the US-centered liberal international order in the context of critical international relations studies. In so doing, this paper will focus methodologically on Beijing’s official documents and state media outlets, presenting an argument that is twofold. First, by promoting its unique form of democracy known as “whole-process people’s democracy,” Beijing domestically intertwines democracy with authoritarianism, hierarchy, and dictatorship. This whole-process people’s democracy appears to function at home as a tool of regime security that is characterized by a rule that is of and for the people but not by the people. Second, China on the international stage has adopted Western-style liberal values to advocate for enhanced democracy in international relations. Through its strategic adoption of these liberal values, Beijing accuses the United States of a hegemonic liberal hypocrisy in international relations while appearing to aspire to a world that is fragmented into essentially different entities.
Solving Promise Equations over Monoids and Groups
Authors: Larrauri Alberto , Živný Stanislav
Published: September 2024

We give a complete complexity classification for the problem of finding a solution to a given system of equations over a fixed finite monoid, given that a solution over a more restricted monoid exists. As a corollary, we obtain a complexity classification for the same problem over groups.
Investigating the Role of Fluid Dynamics on Cut Width Accuracy in Wet Bevel Cleaning Techniques
Authors: Dong Rencheng , Fujita Akira , Bassett Derek , Shinohara Kazuyoshi , Takahashi Shuhei , Simms Ihsan
Published: September 2024

In this paper, we investigate the role of fluid dynamics on cut width accuracy in wet bevel cleaning techniques. As integrated circuit (IC) manufacturers scale down technology nodes, defects from the wafer edge result in significant yield loss. The two main wet bevel cleaning techniques, backside center dispense spin (BCS) and bevel nozzle dispense spin (BVS), have not been thoroughly compared. Computational fluid dynamics (CFD) models were developed to study the liquid flow. BCS generates non-axisymmetric backside flow, leading to non-uniform cut width profiles. BVS produces a stable circular flow, resulting in a more uniform cut width profile. The cut width profile after BCS is influenced by wafer surface properties, hindering etching of hydrophobic bevel films. BVS is less affected by surface properties, making it easier to achieve the target cut width. The CFD model can be utilized as a digital twin to optimize BVS conditions based on film material properties. This study advances the understanding of fluid dynamics in wet bevel cleaning for improved wafer yield near the edge.
(Keynote) Epitaxial Si/SiGe Multi-Stacks: From Stacked Nano-Sheet to Fork-Sheet and CFET Devices
Authors: Loo Roger , Akula Anjani , Shimura Yosuke , Porret Clement , Rosseel Erik , Dursap Thomas , Hikavyy Andriy Yakovitch , Beggiato Matteo , Bogdanowicz Janusz , Merkulov Alex , Ayyad Mustafa , Han Han , Richard Olivier , Impagnatiello Andrea , Wang Dong , Yamamoto Keisuke , Sipőcz Tamás , Kerekes Árpád , Mertens Hans , Horiguchi Naoto , Langer Robert
Published: September 2024

After a short description of the evolution of metal-oxide-semiconductor (MOS) device architectures and the corresponding requirements on epitaxial growth processes, the manuscript describes the material properties of complicated Si/SiGe multi-layer stacks used for complementary field effect transistor (CFET) devices. They contain two different Ge concentrations and have been grown using conventional process gases. A relatively high growth temperature is used to obtain acceptable Si and SiGe growth rates. Still island growth has been suppressed for Ge concentrations up to 40%. Excellent structural and optical material properties of the Si/SiGe multi-layer stack will be reported, with up to 3 + 3 Si channels in the top and bottom part of the stack, respectively. The absence/presence of lattice defects has been verified by room temperature photoluminescence measurements. Photoluminescence measurements at low temperatures are used to study band-to-band luminescence from individual sub-layers and to illustrate the optical material quality of the CFET stack.
Source/Drain Epitaxy for Nanosheet-Based CFET Devices
Authors: Rosseel Erik , Porret Clement , Dursap Thomas , Loo Roger , Mertens Hans , Ganguly Jishnu , Sarkar Ritam , Cavalcante Camila , Richard Olivier , Geypen Jef , Marozas Brendan , Casey Daniel , Khazaka Rami , Demuynck Steven , P. B. Lima Lucas , Langer Robert , Biesemans Serge , Horiguchi Naoto
Published: September 2024

This work reports the progress in source/drain (S/D) epitaxy development for nanosheet-based monolithic complementary field effect transistors (mCFET). S/D processes which were set-up for bulk finFET devices can be easily transferred to mCFET devices. Owing to the complicated integration and small dimensions of the highly scaled structures however, more attention is required for the pre-epi cleaning of the exposed channel interfaces and for the additional defectivity that arises from the merging of individual epitaxial growth fronts. Low-temperature epi processes can be structurally integrated in mCFET devices, to further reduce the transistor access resistance components and comply with thermal budget limitations.
Light Emission of Sn/Ge MQW pin Diodes on Si
Authors: Oehme Michael , Hack Michael , Starz Leon , Darwish Hussain , Spieth Christian , Schaefer Soeren C. , Wanitzek Maurice , Seidel Lukas , Kasper Erich , Schwarz Daniel
Published: September 2024

Sn/Ge multi-quantum well diodes integrated on Si were grown pseudomorphically on Ge virtual substrates on Si using molecular beam epitaxy. Temperature-dependent electroluminescence analyses were conducted on these devices across a range of temperatures, from 290 K to 12 K. This analysis identified four distinct energy transitions across the entire temperature range. Two of the peaks were observed at high temperatures and were no longer discernible as the temperature decreased. The remaining two peaks were only measured at low temperatures. By analyzing them with a Ge reference diode, one of the peaks was identified as a defect peak. The intensity of the other peak increased as the temperature decreased, which is consistent with the behavior of a direct transition in an indirect semiconductor material.
Photoemission Study on Si and Ge Segregation on Al/Si0.8Ge0.2 Structures
Authors: Sakai Taiki , Ohta Akio , Taoka Noriyuki , Yamamoto Yuji , Schubert Markus Andreas , Miyazaki Seiichi , Makihara Katsunori
Published: September 2024

We have demonstrated the formation of an ultrathin Si and Ge layer on an Al/Si0.8Ge0.2(111) structure caused by controlling the annealing condition. From the XPS characteristics, the annealing temperature, rather than the time, was found to be important in controlling the Si and Ge segregation. Also, by thermal annealing in N2 ambient, the segregated Ge on the Al/Si0.8Ge0.2 structure was found to be stable and resistant to oxidation due to the surface Al oxide layer and the segregated Si. We also found that Ge atoms were highly selectively segregated from the Al/Si0.8Ge0.2(111) structure below 500ºC. It was also found that Ge atoms could be selectively segregated from the Al/Si0.8Ge0.2(111) structure by rapid thermal annealing. The results will lead to the development of two-dimensional Ge crystals that are highly compatible with Si ultra-large-scale integration processing.
Development of Novel Ternary Alloy of CSiSn for Low-Cost Next Generation Photovoltaics
Authors: Banishashemian Seyedeh , Mahmoudi Mohammad , Mosleh Aboozar , Naseem Hameed
Published: September 2024

The growing need for highly efficient solar cells calls for significant advancements in the development of a new material system to meet the needs of low-cost and low-cost production. Current multi-junction solar cell alternatives are more costly to produce. This research showcases the development and analysis of a novel ternary material system, The CSiSn (CST) alloy, which shows potential for creating low-cost material with high absorption in of solar spectrum. In this work, the following aspects regarding the CST material are investigated: 1) Material modeling using density functional theory, 2) electronic band structure estimations, 3) low-temperature material growth technique via Plasma Enhanced Chemical Vapor Deposition (PE-CVD) system; 4) advanced material and optical characterizations of CST alloys.
Benchmarking of HCl-Based Cyclic Deposition / Etch (CDE) and Single Deposition / Etch (DE) Processes for Selective Epitaxial Growth of SiGeC:B Films
Authors: Vives Jeremy , Deprat Fabien , Frauenrath Marvin , Verdier Stephane , Aybeke Ece , Baron Alain , Marque Eldrine , Chaussende Didier
Published: September 2024

In this paper, SiGeC:B growth behaviors at 550 °C, 10 Torr, were studied in a 300 mm industrial Reduced Pressure-Chemical Vapor Deposition reactor using a Si2H6/GeH4/SiH3CH3/B2H6 chemistry. Carbon atoms, for both SiGeC and SiGeC:B layers, were only incorporated into substitutional sites, with concentrations up to ~ 1.4 at%. It appeared that in-situ boron doping at a level of 1x1020 at.cm-3 did not modify the substitutional carbon incorporation. However, carbon and boron atoms were shown to compete for substitutional incorporation sites, as outlined by the increased SiGeC:B films resistivity. Cyclic Deposition / Etch (CDE) and Deposition / Etch (DE) processes were then benchmarked on blanket Si substrates and blanket Si wafers covered with 10 nm of Si3N4, with the aim to achieve selective growth on patterned wafers. The CDE process consisted of 10 cycles with deposition steps at 550 °C, 10 Torr and etch steps at 550 °C, 50 Torr with a very high HCl flow. The simpler DE process consisted in a single deposition step at 550 °C, 10 Torr, followed by a single etch step at 550, 575 or 600 °C, 600 Torr, with a very low HCl flow. CDE and DE processes both resulted in a rather low etch selectivity of 1.8 and produced slightly rough SiGeC:B surfaces. Finally, it was shown that the use of a HCl-based CDE process is not a viable solution to obtain high quality SiGeC:B films on patterned wafers at low growth temperatures. Meanwhile, DE yielded higher quality if slightly rough SiGeC:B layers.
Enhanced Stability Under Positive Bias Temperature Stress in Oxide Thin Film Transistors with Double Gate Structure By Improving Bottom Channel Interface
Authors: Son Kyoung-Seok , Kim Myoeng-Ho , Lee Seung-Hun , Kim Youn-Goo , Kim Jaybum , Lee Sunhee
Published: September 2024

In this paper, we discuss the causes of reliability degradation in oxide TFTs with a double gate structure and propose methods for improvement. Reducing IGZO deposition power significantly improves PBTS (Positive Bias Temperature Stability) reliability in double gate structures. This improvement is attributed to reduction of excess oxygen defects accumulated at the bottom channel interface, as inferred from the difference in PBTS results for the top single gate and double gate structures
IGZO TFT Backplane Integration for µLED Flat-Panel Display
Authors: Powell Eli , Woodard Trevor , Li Zhi , Corbett Brian , Garner Sean , Manley Robert G. , Hirschman Karl D.
Published: September 2024

The focus of this work is the process integration of Indium Gallium Zinc Oxide (IGZO) transistors as a µLED backplane for row/column addressing. A single pixel is composed of a µLED driven by an arrangement of two transistors and a storage capacitor. The pixels are then arrayed on a glass substrate to support active-matrix control of monochrome and full color (RGB) displays from 1x1cm (50 x 50 pixels) up to 7.6 x 7.6 cm (380 x 380 pixels). Optimization of circuit parameters considering size and scan frequency was modeled using existing TFT and µLED electrical device compact models. New process parameters and procedures were determined for the proper integration of µLEDs in an existing TFT fabrication process. Red, green, and blue µLED devices were fabricated at Tyndall National Institute on native substrates and were transferred to TFT pixels using an X-Display MTP-1003 micro-transfer printer. The performance of individual test cells was assessed using an Agilent B1500, revealing a voltage transfer characteristic indicating the ability to modulate and control µLED current.
Effect of Annealing Time on Various PtNi/C Binary Alloy Catalysts for ORR in PEFCs
Authors: Yamaguchi Kazuki , Garavdorj Batnyagt , Wakita Hidenobu , Ui Koichi , Takeguchi Tatsuya
Published: September 2024

Polymer electrolyte fuel cells (PEFCs) are used in automotive power supplies due to their advantages of low environmental impact and high energy conversion efficiency. However, Pt used for electrocatalysts is expensive and its activity and durability are problematic. In this study, the PtNi/C catalysts were prepared with different annealing times and the oxygen reduction reaction activity was evaluated. The linear sweep voltammograms and current-voltage curves showed that the PtNi/C catalysts annealing time for 60 min performed better than the commercial catalyst. This would be attributed to the internal alloying of Ni and better electronic structure due to the longer annealing time.
The Development of Uniform-Sized Pt-Based Binary Alloy Electrocatalysts for ORR in Polymer Electrolyte Fuel Cells
Authors: Garavdorj Batnyagt , Galindev Oyunbileg , Wakita Hidenobu , Ui Koichi , Takeguchi Tatsuya
Published: September 2024

Developing a highly efficient and durable reduced platinum metal (PtM) alloy catalyst with high oxygen reduction reaction (ORR)activity for polymer electrolyte fuel cells (PEFCs) is of significant interest. In this study, platinum-iron (PtFe), platinum-nickel (PtNi), and platinum-cobalt (PtCo) alloys were prepared with an average diameter of ca. 3 nm, uniformly dispersed on a high surface area carbon. The ORR activity of the prepared PtM/C catalysts was investigated under both RDE and MEA conditions. The resulting PtM/C catalysts demonstrated improved I-V cell performance at low-current density (LCD) and high-current density (HCD) regions. These findings suggest that high ORR activity and enhanced durability can be achieved through the formation of uniform Pt skin with higher electrochemical surface area (ECSA).
Activity and Stability of Iridium-Based Alloy Catalysts for PEM Electrolyzer
Authors: Mariappan Sakthivel , Drillet Jean-Francois
Published: September 2024

Bi-metallic alloy of Ir3Cr and Ir3Pt catalysts as well as Ir black as reference were synthesized by co-reduction route in sodium borohydride under hydrothermal condition. Well-distributed particles in the range of 1.7 - 2 nm in average were yielded. Ir alloy formation was confirmed by XRD spectra. Interestingly, after 1000 ADT cycle under half cell condition, Ir3Cr catalyst showed an enhanced activity of 7% and 59% for OER at 1.6 V compared to Ir3Pt and as prepared Ir black, respectively. Moreover, both alloy catalysts exhibited excellent stability with ~10 and 40 mV less overpotential for OER at 20 mA cm-2 compared to as-synthesized Ir black and commercial Ir black catalysts.
Fitting Scattering Profiles of Perfluorinated Sulfonic Acid Ionomer Dispersions
Authors: Jeong Eugene , Litster Shawn
Published: September 2024

Polymer electrolyte fuel cells (PEMFCs) are key to developing the hydrogen economy, particularly in the transportation sector. The focus on heavy-duty vehicles has driven research toward improving the efficiency and durability of catalyst layers and understanding the role of the ionomer binder. The characterization of these ionomers is important not only in their cast forms but also in inks and dispersions. Small-angle scattering (SAS) techniques have become one of the primary tools for analyzing ionomer systems in solution. While SAS can provide valuable structural information about ionomer aggregates, relevant size and shape information requires model fitting to obtain. While many scattering form factor models have been applied to uncover the behavior of aggregates in ionomer dispersions, the role of the fitting range in the fit quality has not been extensively discussed. In this work, we illustrate the effect of varying fitting ranges for three commonly used form factors.
Transport Mechanism of Hydroxide Ions Focused on the Vehicle Mechanism Near the Cation Sites in Anion Exchange Membranes
Authors: Ono Ryusei , Suzuki Hiroto , Miyatake Kenji , Tokumasu Takashi
Published: September 2024

We investigated the transport factors of hydroxide ions in anion exchange membrane (AEM). We used partially fluorinated quaternized QPAF-4 polymer with trimethylammonium groups as the AEM material and analyzed it using classical molecular dynamics (MD) simulations. Analysis of the dependence of density on water content (λ) suggested that the voids in the QPAF-4 polymer are fully filled with water molecules under high λ conditions (λ = 15), and as the polymer absorbs additional water molecules, it expands, resulting in a decrease in density. Furthermore, radial distribution function analysis and existence ratio analysis of hydroxide ions in the solvation shells of trimethylammonium groups indicated that increasing λ reduces the overlap of the first solvation shells and causes hydroxide ions to migrate from the first to the second solvation shell. This result indicates that these structural factors contribute to the enhanced diffusivity of hydroxide ions under high λ conditions.
Evaluating Effects of Cerium Concentration and Water Content on Diffusivity of Cerium Ions in PEFC Using Molecular Dynamics Simulations
Authors: Suzuki Hiroto , Tokumasu Takashi
Published: September 2024

We investigated effects of cerium concentrations and water content on diffusivity of cerium ions in Nafion membrane. The diffusion coefficients of cerium ions were taken, and the structural features that could change diffusivity were analyzed. Results show that difference in concentrations in this study is independent of diffusivity. Although there was a slight difference in structure depending on the concentration, it was suggested that this depended on the initial position of the cerium ion. The diffusion of cerium ions was found to be greatly affected by water content. When water content is 3, cerium ions coordinate with sulfonic acid group because of luck of water around cerium ion. As water content increase, cerium ions are fully hydrated, and they may have high diffusivity. The growth of water clusters, which are the transport pathway for the ions, is also thought to be the cause of the significantly larger diffusion coefficient.
High current density operation of proton exchange membrane fuel cells at a constant relative humidity
Authors: Liu Wei , Zhong Zhaoda , Liso Vincenzo , Berning Torsten
Published: September 2024

To further reduce the size and cost of proton exchange membrane fuel cells, it is desired to operate at high current densities exceeding 2 A/cm2, and consequently achieve power densities above 1 W/cm2. In a prior one-dimensional modeling study that employed the Engineering Equation Solver (EES), it was suggested that proton exchange membrane fuel cells might operate at current densities as high as 10 A/cm2 and even more when appropriate operating and channel dimensions are chosen, and perforated metal plates are used as porous transport layers instead of carbon fiber papers. The current study verifies the general findings of the previous 1-D model by a 3-D multiphase computational fluid dynamics model in Ansys CFX to obtain additional insights. Operating a proton exchange membrane fuel cell at a constant humidity (100%, 80%, 60%) from the inlet to the outlet at the cathode side appears feasible, and results for a current density above 6 A/cm2 were obtained. This mode of operation is promising also for automotive applications.
Modeling The Hydrogen Crossover Through Membrane With And Without Catalyst Layers
Authors: Polat Beste Balci , Nakamichi Kimiyo , Ma Yulei , Kageyama Miho , Polat Beste
Published: September 2024

The hydrogen crossover flux is expressed as a function of the difference in the partial pressure of hydrogen and total pressure difference between the supply and permeate sides of a membrane. The hydrogen crossover rate was measured under several operating conditions by micro gas chromatography. The permeation flux was not influenced by the total pressure difference up to 50 kPa. A bare Nafion membrane and the membrane with catalyst layers were modeled as a stack of bulk and skin layers. Hydrogen permeability of both samples showed identical bulk layer expressed by a power-law equation of the moisture content and an Arrhenius equation of temperature with an activation energy of 22.8 kJ mol–1. The measurement of skin layer resistance wasn’t successful since the skin layer resistance was too low to be measured. A skin layer of Nafion with a catalyst layer wasn’t observed due to formation of fused layer.
From Catalyst Ink to PEM Fuel Cell Stack: First Full-Size Screen Printed Catalyst Layers Tested within a Generic Stack
Authors: Ney Linda , Herbst Dominic , Wengenmeyr Noah , Kiaee Zohreh , Thombra Neethu Philip , Häußler Frank , Joerissen Ludwig , Groos Ulf
Published: September 2024

This study presents a comprehensive investigation and research platform to introduce a production process chain from catalyst ink to a generic stack level. Screen printed catalyst layers are upscaled to meet industrial active areas of 283 cm² and decal transferred onto the polymer electrolyte membrane with a roll calender, which process parameters were optimized. Afterwards, the subgaskets and gas diffusion layers were applied, and a short stack has been assembled. For the first time, screen printed catalyst layers have been tested within a short stack of automotive size, showing the same performance as its commercial references. This sets the starting point for a successful manufacturing process and stack testing platform, which is valuable especially for CCM material and component manufacturers as well as the research community.
In-Depth Analysis of the Impact of Ionomer Content on PEMFC Degradation By Combining Electrochemical Characterization Techniques and Transmission Line Modeling
Authors: Raab Sebastian , Chuang Po-Ya Abel , Weber Andre
Published: September 2024

This study analyzes the influence of the ionomer-to-carbon ratio (I/C) in cathode catalyst layers (CCL) on carbon corrosion behavior during high-potential cycling accelerated stress tests (ASTs). Membrane electrode assembly (MEA) samples with varying I/C ratios (0.5/0.85/1.2) were evaluated using polarization curve measurements and electrochemical impedance spectroscopy (EIS) under H2/air conditions. Analysis through the distribution of relaxation times (DRT) and equivalent circuit modeling revealed that the MEAs with a high I/C ratio (1.2) and a medium I/C ratio (0.85) exhibited the highest beginning of life (BoL) performance, attributed to their lower ionic resistances. Conversely, the MEA with a low I/C ratio (0.5) showed significant improvement during initial AST cycles and superior carbon degradation resistance, despite poor BoL performance. This study highlights the need for further investigation to fully understand the impact of the I/C ratio on electrode structure and carbon corrosion behavior. Furthermore, the combined results suggest that optimizing the I/C ratio could enhance the durability of PEMFC electrodes.
Effect of GDL Structure and Operating Conditions on PEMFC Performance and Liquid Water Removal
Authors: Tateyama Shota , Suzuki Takahiro , Nasu Mitsunori , Hirayama Naoki , Watanabe Masahiro , Uchida Makoto , Iiyama Akihiro , Tsushima Shohji
Published: September 2024

Gas diffusion layers (GDLs) in proton exchange membrane fuel cells (PEMFCs) are responsible for diffusion of reactant gases into the catalyst layers, current collection and the removal of produced water. An accumulation of generated liquid water within the GDL, known as flooding, impedes the supply of reactant gas and results in the increase of concentration overpotential. Therefore, understanding of oxygen transport and produced water removal characteristics is required to enhance cell performance. The objective of this study is to investigate the effect of GDL structure and operation conditions on PEMFC performance and liquid water removal, with a particular focus on comparing a novel GDL to a conventional GDL. The results of a simultaneous evaluation of cell performance and liquid water behavior in the GDLs by means of X-ray imaging under operational conditions are presented.
Relative Humidity Distribution along the Gas Flow Channel in a Wide Temperature Range
Authors: Polat Beste Balci , Nakamichi Kimiyo , Ma Yulei , Kageyama Miho , Kawase Motoaki
Published: September 2024

Relative humidity (RH) distribution is a crucial condition for proton exchange membranes in fuel cells. Estimation of the distribution in a cell by measuring RH at the cell outlet with varying the O2conversion was proposed. The O2 conversion is a function of the space time, a ratio of the active area from the inlet to the inlet volumetric gas flow rate. Varying the active area or the flow rate resulted in identical relation between the O2 conversion and the space time 60.5–90.5 oC with Nafion NR-212. Numerical simulation well reproduced the measured RH distribution, which was also closer to those estimated with assuming equal RH on the anode and cathode sides, i.e. sufficiently rapid water permeation. At higher temperature, more water generation or supply was required to attain RH equal to that at lower temperature. Increasing the inlet RH compensated the less RH increase at higher temperature.
Modeling the Effect of Cell Orientation on the Performance of an Air-Breathing Polymer Electrolyte Fuel Cell with a Columnar Cathode Plate
Authors: Garcia-Salaberri Pablo A. , Shahzad Hasan , Duque Luis , Folgado M. Antonia , Diaz-Álvarez Ester , Chaparro Antonio M
Published: September 2024

Air-breathing polymer electrolyte fuel cells (PEMFCs) are expected to play an important role in the development of sustainable portable and mobile devices, such as unnamed aerial vehicles, motorbikes or laptops. In this work, the performance of air-breathing PEMFCs with a columnar cathode plate design is examined by means of a 3D two-phase, non-isothermal model, and compared against experimental data. The results show that the performance is highly influenced by the cell orientation, namely horizontal (material plane perpendicular to gravity) versus vertical (material plane parallel to gravity). Oxygen transport in horizontal cells is mainly dominated by diffusion, leading to oxygen shortage toward the cell center and an inhomogeneous current density distribution. In contrast, oxygen transport in vertical cells is assisted by natural convection, enhancing oxygen transport throughout the cell and increasing the current density homogeneity. Water saturation is preferentially accumulated close to the cell center, being larger in horizontal cells due to the lower water removal rate of the cathode plate.
Improved Understanding of PEMFC Stack Durability Testing through Comprehensive In-Situ and Ex-Situ Characterization Techniques
Authors: Schüttoff Miriam , Wachtel Christian , Wilhelm Florian , Scholta Joachim , Hölzle Markus
Published: September 2024

Durability testing of Proton Exchange Membrane Fuel Cells for mobile applications remains a critical challenge. While most academic studies focus on single-cell testing, there are only few publications on stack testing of technical relevant sizes. This study utilizes comprehensive characterization techniques to enhance understanding of PEMFC stack durability, aiming to meet the currently targeted durability targets. A 5,500-hour long-term test, based on the Auto Stack Industry (ASI) test protocol, was performed on a 7-cell short stack of 240 cm² active area. In-situ techniques, such as spatially resolved current density measurement, cyclic voltammetry, and electrochemical impedance spectroscopy, provided real-time degradation insights, while ex-situ methods, including FIB-SEM analysis, infrared thermography or contact angle measurements provided information on material degradation mechanisms. Membrane degradation was found to be negligible. Slight thinning of the cathode indicates carbon corrosion of the catalyst support. Catalyst aging was observed in the form of Pt band formation and Co leaching. Gas diffusion layers showed hydrophobicity loss, and increased resistance in bipolar plates contributed to reduced performance. Our findings demonstrate that PEMFC stacks operated under automotive drive cycle protocols can meet the actual targeted durability objectives. Moreover, it illustrates the degradation phenomena that occur under realistic operating conditions and modes, and how they evolve over the duration of thousands of hours of operation.
Fabrication of α-W and β-W Films By Using CsF–CsCl–WO3 Molten Salt: Effect of Oxygen Contents in W Films
Authors: Wang Haochen , Norikawa Yutaro , Nohira Toshiyuki
Published: September 2024

Electrodeposition of W films in CsF–CsCl eutectic melts was investigated after adding 2.0 mol% of WO3 at 773–973 K. The oxygen content in W films electrodeposited at various temperatures was analyzed using inert gas fusion and non-dispersive infrared spectroscopy (NDIR). Oxygen contents in the W films gradually decreased from 6.65 at% to 0.24 at% as the bath temperature increased from 773 K to 923 K along with the crystal phase change from β-W to α-W, confirmed by X-ray diffractometry (XRD). Then, vacuum annealing treatment was performed for the electrodeposited β-W films. The crystal phase was transformed to pure α-W after annealing at 973 K for 3 h and the oxygen content in W films decreased from 1.82 at% to 0.38 at%. Finally, based on the above findings, we provide a promising two-step method for preparing mirror-like and dense α-W films.
Anodic Dissolution and Electropolishing of Titanium in an Amide-Type Ionic Liquid Containing Halide Ions
Authors: Yoneda Kentaro , Serizawa Nobuyuki , Katayama Yasushi
Published: September 2024

Anodic dissolution of titanium was investigated in an amide-type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)amide (BMPTFSA) in the presence of halide ions, Cl– and Br–. Electropolishing of Ti was possible in the presence of Cl– at 353 K, suggesting that the surface of a Ti electrode with the native oxide layer was activated by Cl–. The dissolved species of Ti after anodic dissolution of Ti at 0 V vs. Ag|Ag(I) was found to be tetravalent [TiCl6]2–, because the applied potential was more positive than the redox potential of [TiCl6]2–/[TiCl6]3–. The morphology of a Ti electrode changed after potentiostatic anodic oxidation at –0.5 V in BMPTFSA containing BMPBr, indicating that anodic dissolution of Ti was possible in the presence of Br–.
Anodic Dissolution of Al–Fe and Al-Fe-Si Alloys in Emimcl–AlCl3 Electrolyte
Authors: Nunomura Junji , Matsushima Hisayoshi , Kyo Yoshihiko , Kojima Yoichi , Ueda Mikito
Published: September 2024

To produce over 99.9% of high-purity Al from Al–Fe alloy containing Al6Fe and Al–Fe–Si alloy containing β-AlFeSi by electrorefining, their anodic dissolution and cathodic electrodeposition characteristics were investigated in an EmImCl–AlCl3 ionic liquid electrolyte at 323 K. Constant potential electrolysis showed that Fe dissolved from Al–Fe anode at 0.7 V vs Al/Al(III) and from Al–Fe–Si anode at 1.4 V, and was co-deposited with Al on the cathode. Notably, anodic dissolution potential of Fe was changed by forming β-AlFeSi, and Si did not dissolve from β-AlFeSi at either potential. A combination of controlled anodic dissolution potential and the use of the Al alloy containing β-AlFeSi further suppressed the dissolution and cathodic co-deposition of Fe, affording high-purity Al on the cathode.
Redox Reaction of Some Nitroxyl Radicals in 1-Butyl-1-Methylpyrrolidinium Bis(fluorosulfonyl)amide in the Presence and Absence of Lithium Ion
Authors: Katayama Yasushi , Kato Shodai , Serizawa Nobuyuki
Published: September 2024

The electrochemical behavior of 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO) and 4-oxo-TEMPO was investigated in 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)amide (BMPFSA) in the absence and presence of LiFSA. The redox reactions of TEMPO+/TEMPO and 4-oxo-TEMPO+/4-oxo-TEMPO were observed on a platinum electrode in the absence and presence of 0.5 M LiFSA. The formal potentials of TEMPO+/TEMPO and 4-oxo-TEMPO+/4-oxo-TEMPO were positively shifted in the presence of LiFSA, indicating that the interaction of TEMPO and 4-oxo-TEMPO with Li+ altered the energies of the singly occupied molecular orbitals of TEMPO and 4-oxo-TEMPO. The diffusion coefficients and standard rate constants were evaluated by chronoamperometry and electrochemical impedance spectroscopy, respectively. The diffusion coefficient and the standard rate constant were suggested to be controlled not only by the viscosity but also by the interaction between the nitroxyl radicals and Li+.
Electrochemical Characterization of Silver and Iron Ions in Choline Chloride-Ethylene Glycol DES Electrolyte
Authors: Jahrsengene Goril , Wang Zhaohui , Martinez Ana Maria
Published: September 2024

Solar energy is growing to be an important source of renewable energy in the world, and the need of recycling processes to recover the strategic materials used for this technology are necessary. Ag may be recovered from photovoltaic cells using a Deep Eutectic Solvent (DES), by selectively dissolving Ag from the waste to Ag(I) by use of an Fe(III)/Fe(II) redox couple before the recovery of Ag metal by electrowinning. Electrochemical characterization of Ag and Fe ions in ethaline DES showed that Ag, Ag(I), Fe(II) and Fe(III) ions are stable, and the standard potentials of the relevant reactions are sufficiently far from one another for the electrochemical recovery of Ag. Diffusion coefficient were estimated to be 1.77-4.16 ·10-7 cm2/s and 2.02-3.19 ·10-7 cm2/s for Ag(I) and Fe(II) ions, respectively. High quality Ag deposits were obtained with Fe ions in the solution, and with water content up to 10 wt% in the DES electrolyte.
The Local Changes in the Physicochemical Properties during Cu Electrodeposition in an Ionic Liquid Composed of [CuCl2]–
Authors: Serizawa Nobuyuki , Kuwahara Suguru , Li Xiaoyi , Katayama Yasushi
Published: September 2024

The equimolar mixture of CuCl and 1-butyl-1-methylpyrrolidinium chloride (BMPCl) was found to yield an ionic liquid composed predominantly of BMP+ and [CuCl2]–. Fine deposits of metallic Cu were obtained by potentiostatic reduction of [CuCl2]– in CuCl-BMPCl (50.0-50.0 mol%). The change in the local physicochemical properties near the electrode during the electrodeposition of Cu was analyzed using electrochemical quartz crystal microbalance. The resonance resistance of a quartz crystal electrode increased with an increase in the local viscosity near the electrode, probably reflecting the change in the composition of the electrolyte.
Electrochemical Conversion of Salinity Gradient Energy by Using Acid Surface Modified Activated Carbon Electrode
Authors: Yuan Xia-Yue , Li Jia-Jun , Liu Xin-Yu , Zhou Juan , Feng Jie , Liu Jun-Hu , Ma Xue-Jing , Zhang Wei-Bin
Published: September 2024

Salinity gradient energy is a sustainable, clean, and renewable ocean energy source. In this work, we used citric acid, phosphoric acid, and nitric acid to modify the surface of activated carbon. Based on the electrochemical capacitive mixing technology, a salinity gradient energy extraction device was constructed using acid-modified activated carbon as cathode and MoS2/MWCNTs as anode. Surface modification by different acids improves the performance of activated carbon electrodes for salt gradient energy conversion in the salt difference battery. The modification effect of nitric acid was the most pronounced, the specific capacitance of the modified electrode reaches 156 F g−1, and the concentration response voltage reaches 170 mV, with the assembled energy extraction system obtaining an energy density of 10.65 J m−2, an enhancement of 53.0% compared to the unmodified activated carbon electrode.
Tech Highlights
Authors: Pile Donald , Gallaway Joshua , Schindelholz Mara , McNulty David , Liu Zenghe , Karuppaiah Chock
Published: September 2024

A collection of technology highlights pulled from recent papers published in ECS journals.
Achieving Passive Thermal Runaway Propagation Resistance in Li-ion Battery Packs
Authors: Quinn Alexander , Darst Jacob , Keyser Matthew , Coman Paul T. , Barrera Thomas P. , Shearing Paul R. , Petrushenko David , Finegan Donal P. , Darcy Eric
Published: September 2024

Because of their high specific and volumetric energy density, lithium-ion cells are popular in energy storage systems with strict mass and volume restrictions. Such applications include electric vehicles, power tools, consumer electronics, all-electric aircraft, as well as high-reliability military and crewed spacecraft. Next-generation rechargeable lithium cell designs are characterized by higher specific energy which further increases the severity of thermal runaway (TR) safety hazards. Even with carefully controlled high-quality manufacturing processes, TR can occur unpredictably due to latent defects inside the cells causing internal short circuits. This work elaborates on the lessons learned from cell and battery pack safety research for crewed spacecraft applications.
Hypoxia-inducible factor-2α enhances neutrophil survival to promote cardiac injury following myocardial infarction
Authors: Piccolo Enzo B. , Ge Zhi-Dong , Filipp Mallory E. , Sullivan David P. , Thorp Edward B. , Sumagin Ronen
Published: September 2024

Hif2α in neutrophils increases infarct size, cardiac dysfunction, and ventricular scar after myocardial infarction. Hif2α in neutrophils supports neutrophil survival via cIAP-1 signaling and delays macrophage engulfment.
A Low‐Frequency Oscillation Identification Method for Power System Based on Adaptive Generalized S‐Transform with Bat Algorithm
Authors: Yu Miao , Wei Jingjing , Tian Shuoshuo , Sun Jianqun , Wu Yixiao , Zhang Shouzhi , Hu Jingxuan
Published: September 2024

The complexity of the interconnected grid and the continuous increase of new energy sources have led to an acute problem with low‐frequency oscillation (LFO) in power system. Identification and monitoring of LFO in power grid are prerequisites for effective control of low‐frequency oscillation phenomena. To address matter that the traditional S‐transform time‐frequency window function has a fixed scale and cannot be applied to the specific local characteristics of different signals, an adaptive generalized S‐transform algorithm based on a bat algorithm is proposed in this paper. It uses adjustment parameters to control the generalized Gaussian window function. The parameters are automatically adjusted by a bat algorithm adaptive optimization to find the best time‐frequency characterization. Secondly, the PMU data waveform with implicit low‐frequency oscillation information is converted into a two‐dimensional time‐frequency figure including the onset moment, frequency, and amplitude. The system enables identification and visual monitoring of low‐frequency oscillations. After that, simulation experiments of New England system are conducted. The superiority of the proposed method is verified, which can greatly improve the time‐frequency resolution of PMU active power data signal and has effective noise immunity.
Patient Demographics and Major Adverse Cardiovascular Events after Androgen Deprivation Therapy for Prostate Cancer
Authors: Wallis Christopher J. D. , Chen Kevin C. , Atkinson Stuart , Boldt-Houle Deborah M.
Published: September 2024

Background. The association between patient demographics and CV events after ADT using real‐world data was evaluated. In addition to encompassing >30 times more patients than all previous MACE studies, this is the first study, to the best of our knowledge, to include a comprehensive listing of many demographic factors from one large, recent US dataset over a long period of time. Materials and Methods. The retrospective analysis of data in the Decision Resources Group (now Clarivate) Real World Evidence repository, representing >300M US patients from 1991 to 2020 across all US regions, was performed. Patients with PCa receiving ≥1 ADT injection were included. MACE risk after ADT initiation was evaluated for demographic and potential PCa‐related risk factors. Kaplan–Meier survival curves were constructed, and Cox regression was used to evaluate the association between MACE risk and demographic/PCa‐related risk factors. Results. Overall, MACE risk was slightly lower in the first year after ADT initiation (3.9%) vs. years 2–4 (∼5.2%). In a multivariate Cox model, MACE risk after ADT initiation was significantly higher for older vs. younger patients (adjusted HR per increasing year = 1.08, 95% CI: 1.07–1.09), men with a history of MACE vs. without (HR = 2.22, 95% CI: 1.72–2.88), men with very low BMI vs. normal or high BMI (HR for decreasing BMI per kg/m2 = 1.02, 95% CI: 1.01–1.03), White vs. Black patients (HR = 1.30, 95% CI: 1.08–1.55), and patients who did not use statins vs. those who did (HR = 1.13, 95% CI: 1.00–1.27). Of the PCa‐related risk factors, MACE risk after ADT initiation was significantly higher for oncology vs. urology treatment setting (HR = 2.47, 95% CI: 2.12–2.88), patients with baseline metastasis vs. those without (HR = 2.30, 95% CI: 1.72–3.07), and patients treated with antagonists vs. agonists (HR = 1.62, 95% CI: 1.25–2.10). Conclusions. Demographic factors are important contributors to increased MACE risk for men with PCa on ADT. Clinicians should monitor risk factors and modify if possible.
Effects of Work‐Family Conflict and Work Engagement Interactions on Hospital Nurses’ Turnover Intentions during the COVID‐19 Pandemic: A Cross‐Sectional Study
Authors: Saigusa Toru , Yokomichi Hiroshi , Miyamura Toshihiro
Published: September 2024

High nurse turnover is a worldwide problem that was exacerbated by COVID‐19, leading to further staffing shortages and negatively affecting patient care quality. Although options to minimize nurse turnover are frequently discussed, and high levels of work‐family conflict are known to increase turnover intentions while high levels of work engagement are associated with lower turnover intentions, not much is known about how the two interact to affect turnover intentions. This study investigated the impact of work‐family conflict, work engagement, and their interaction on turnover intentions among Japanese hospital nurses. A cross‐sectional design was employed. Hobfoll’s conservation of resources theory was applied as the theoretical framework. A total of 827 nurses working at public or similar to public hospitals in the Tokyo metropolitan area participated in a web‐based survey. The survey included personal characteristics, turnover intentions, the Japanese version of the Work‐Family Conflict Scale, and the Work Engagement Scale of the New Simplified Work Stress Questionnaire. Correlation analysis, hierarchical multiple regression analysis, and simple slope analysis were used to examine the associations among turnover intention, work‐family conflict, and work engagement, and their interactions. A significance level of 0.05 (two‐tailed) was chosen. Analysis of 124 data sets revealed an average participant age of 40.0 years, with 94.4% being female. Hierarchical multiple regression identified significant relationships among work‐family conflict, work engagement, work‐family conflict x work engagement, full‐time employment, marital status, and having children. Simple slope analysis demonstrated a significant positive link between work‐family conflict and turnover intention, irrespective of work engagement level, with the effect of work‐family conflict buffered by high work engagement. Work‐family conflict must be reduced to minimize nurse turnover, but given the buffering effect of work engagement, measures to increase work engagement should be promoted.
Determination of Alzheimer’s Drugs in a Human Urine Sample by Different Chemometric Methods
Authors: Pekcan Güzide
Published: September 2024

In this study, spectrophotometric determination of donepezil and rivastigmine in healthy human urine samples was carried out by the statistical method. Partial least squares (PLS) and principal component regression (PCR) from multivariate calibration methods were used to evaluate the data obtained from the UV–Vis spectroscopy analysis of the urine sample. Mixtures of each early substance were prepared prior to urine sample analysis, and simultaneous determination of donepezil and rivastigmine was performed on the established chemometric model without any prior separation. The calibration curves of each drug were analyzed, and linearity values were also analyzed. For donepezil and rivastigmine, they were 0.9989 and 0.9997, respectively, and were linear over the concentration range of the synthetic mixture. When both chemometric methods (PLS and PCR) were evaluated in terms of accuracy and reproducibility, very high recoveries and small standard deviations were determined. In the PLS method, the standard error of prediction (SEC), the sum of the prediction residual errors (PRESS), the limit of quantitation (LOQ), and the limit of detection (LOD) values were 0.015, 0.0030, 0.067, 0.24, 0.018, 0.0042, 0.089, and 0.301 for donepezil and rivastigmine, respectively. In the PCR method, SEC, PRESS, LOD, and LOQ values are 0.016, 0.0054, 0.066, and 0.23 for donepezil and 0.022, 0.0062, 0.091, and 0.300 for rivastigmine. Chemometrics is used for speed, simplicity, and reliability. The proposed methods have been successfully applied to a sample of urine.
Length‐Weight Relationships of Native and Non‐Native Fishes in the Lower Red River Catchment, USA
Authors: Vilchez Mariaguadalupe , Dattilo John , Brewer Shannon K.
Published: September 2024

Length‐weight relationships are useful for stock assessments and modeling alternative conservation and management strategies for both native and non‐native fishes. We developed length‐weight relationships for 18 native and non‐native riverine fishes in the lower Red River catchment. Fishes were sampled in the summer and autumn seasons between May 2021 and March 2024 via electrofishing and gill nets. Measurements for each specimen consisted of total length (mm) and weight (g). We provide L‐W relationships for 14 native fishes consisting of 5 families (Lepisosteidae, Catostomidae, Ictaluridae, Sciaenidae, and Polyodontidae) and 4 non‐native species belonging to the family Cyprinidae. We collected 6,845 individuals ranging from 67 alligator gar to 1,848 smallmouth buffalo. All the L‐W relationships were significant (p < 0.05), and the majority (72% of species) of relationships between length and weight had r2 values > 0.70. Our findings provide insight into the L‐W relationships of riverine fishes and can be useful for modeling alternatives targeted at native fishes of recreational value and the removal efforts of non‐native fishes.