bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymer to Silicon Direct Bonding for Microelectronics
Authors: Dautriat Margaux , Montméat Pierre , Fournel Frank
Published: September 2023

Direct bonding consists in spontaneously bringing into contact two solid surfaces without any intermediate liquid. We focused on silicon direct bonding with polymer films. Direct bonding was evaluated with two polymers: LOR (MicroChem) and BARC (Rohm & Haas), commonly used in photolithography. Polymer bonding by thermal compression was compared to polymer direct bonding. Adhesion energies and bonding wave velocities of bonding between polymers and silicon surfaces were determined. The bonded stacks exhibited good quality bonding interfaces in terms of defects. High adherence energies up to 10 J/m² were measured.
Soft Surface Activated Bonding of Hydrophobic Silicon Substrates
Authors: Lomonaco Quentin , Abadie Karine , Hartmann Jean-Michel , Morales Christophe , Noël Paul , Marion Tanguy , Lecouvey Christophe , Papon Anne-Marie , Fournel Frank
Published: September 2023

Surface Activated Bonding (SAB) is interesting for strong silicon to silicon bonding at room temperature without any annealing needed, afterwards. This technique has been recognized by the scientific community for more than two decades now and was used for numerous reviewed applications. Although it is a well-known technique, the activation step, in particular, is scarcely documented. This paper offers insights about the impact of soft activation parameters on the amorphous region at the bonding interface. In addition, the adherence energy of hydrophobic silicon after SAB bonding is quantified, to better understand bonding mechanisms. Soft activation parameters on hydrophobic silicon substrates yield exceptionally thin bonding interfaces with acceptable bonding energy at room temperature. According to cross-sectional Transmission Electron Microscopy imaging, a 0.53 nm thick amorphous silicon interface was achieved with an adherence energy of 1337 ± 137 J/m² measured by the Double Cantilever Beam method.
Atomic Diffusion Bonding in Air Using Oxide Films
Authors: Shimatsu Takehito , Uomoto Miyuki , Fukunaga Hitomi , Makita Hiroyuki , Suzuki Yudai , Kozuka Yuhei , Muraoka Arina , Saito Takayuki
Published: September 2023

Atomic diffusion bonding (ADB) is a wafer bonding process using thin films. After ADB in air using oxide films was demonstrated, the resultant bonding performance was compared to that obtained ADB in vacuum with the oxide films. Great bonding strength can be obtained at room temperature using ADB in vacuum, whereas ADB in air required post-bonding annealing at temperature above 150 °C to achieve surface free energy at the bonded interface greater than 1 J/m2. However, ADB in air is a convenient process compared to that in vacuum. For ADB in air using oxide films, we demonstrated that very thin metal films oxidized in air can also be used as oxide films. Particularly, by using amorphous Si films, bonded wafers with a bonded interface consisting of SiO2 amorphous layer can be realized with post-bonding annealing at 150 °C.
Investigation of the Processing Behavior and Stability of Different Glass Frit Materials
Authors: Knechtel Roy , Wenig Micaela , Svoboda Stefan , Seyring Martin , Göbelt Manuela , Schwarz Uwe , Seifert Tobias , Roscher Frank , Wiemer Maik
Published: September 2023

Glass frit wafer bonding is a widely used process in the development and production of microsystems, especially for integrating sensors and their signal conditioning circuits. As a result, glass frit bonded wafers must withstand subsequent process modules, such as silicon (wafer) through vias (TSVs) processing. The properties of glass materials for wafer bonding play a crucial role in ensuring the performance and reliability of such wafers. With the advent of new environmental regulations, Lead-free glass frit materials are being developed to replace the current Lead-containing glasses. In this context, four different glass frit materials were investigated and compared in detail, and the bonding behaviors of these materials were analyzed. It was found that the low-melting main components of these glasses determined their properties and performance. The glasses' electrical and chemical properties were also investigated, and their impact on the bonding process was analyzed. The results of this study provide guidance for the process integration of glass frit wafer bonding and open up new possibilities. In addition, the study highlights the need for practical evaluations for specific applications and related details.
Recent Developments in Low Temperature Wafer Level Metal Bonding for Heterogenous Integration
Authors: Wernicke Tobias , Rebhan Bernhard , Vuorinen Vesa , Paulasto-Krockel Mervi , Dubey Vikas , Diex Kevin , Wünsch Dirk , Baum Mario , Wiemer Maik , Tanaka Shuji , Froemel Joerg , Aasmundtveit Knut E. , Nguyen Hoang V. , Dragoi Viorel
Published: September 2023

An overview of various low temperature (<200°C) wafer bonding processes using metal interlayers is presented. Such processes are very attractive for novel applications in 3D heterogenous packaging as the allow for simultaneous formation of electrical interconnects, as well as hermetic encapsulation of various sensors and microelectromechanical systems-based devices. Metal wafer bonding is a generic category of processes consisting of various sub-categories, each one defined by the different principles governing the process. One can differentiate between eutectic wafer bonding (a eutectic alloy is formed as bonding layer during the process by liquid-solid interdiffusion), intermetallic wafer bonding (an intermetallic alloy is formed as bonding layer during the process by solid-liquid interdiffusion, process known also as Solid Liquid Intermetallic Diffusion – SLID or Transient Liquid Phase – TLP), and metal thermo-compression (TC) wafer bonding. Different critical/gating parameters were investigated and their impact for generally reducing processing temperatures for the different metal bonding systems was studied.
Hydrophilic Bonding of GaN and Diamond Substrates
Authors: Matsumae Takashi , Okita Sho , Fukumoto Shoya , Hayase Masanori , Kurashima Yuichi , Takagi Hideki
Published: September 2023

We have developed a hydrophilic bonding technique for GaN and diamond substrates. Before the bonding step, the GaN substrate was dipped into HCl acid, and the diamond substrate was dipped into NH4OH/H2O2 solution to generate hydrophilic surfaces. The treated GaN and diamond substrates were contacted with each other under atmospheric conditions. They are annealed at 300 °C in 2 h for bonding formation. We expect that this bonding technique would contribute to the fabrication of the GaN-on-diamond structure.
Towards Controlled Transfer of (001) β-Ga2O3 to (0001) 4H-SiC Substrates
Authors: Liao Michael Evan , Huynh Kenny , Carson Brandon , Matto Lezli , Pan Kaicheng , Lundh James Spencer , Tadjer Marko , Hobart Karl D. , Goorsky Mark S.
Published: September 2023

We demonstrate successful surface blistering of He-implanted (001) β-Ga2O3 substrates, bonding to (0001) 4H-SiC, and initial results towards large-area transfer of (001) β-Ga2O3 to 4H-SiC. Surface blistering of unbonded, implanted substrates is an important indication of successful exfoliation and transfer of films, which is achieved by initiating He bubble nucleation during a low temperature anneal followed by bubble growth at a high temperature anneal. Prior to annealing, implanted substrates were bonded to (0001) 4H-SiC at room temperature using a thin ~5 nm Ti interlayer. However, the β-Ga2O3 substrate did not wafer split from the bonded structure after annealing. Instead, small area transfers up to ~200 μm were achieved (~7% of the total bonded area transferred while the entire structure remained bonded). Further optimization of implant parameters is underway. These are promising results towards achieving large wafer-scale (001) β-Ga2O3 composite wafers suitable for β-Ga2O3 devices with efficient thermal management characteristics.
Numerical Simulation of Liquid Water Behavior in PEFCs with Different GDL Wettability
Authors: Naito Hiroshi , Hirai Shuichiro
Published: September 2023

In this study, an unsteady numerical simulation of PEFCs using the VOF method was performed to investigate the relationship between wettability of gas diffusion layer (GDL) substrates and liquid water drainage. The simulations were conducted with contact angle of 60°, 90°, 110°, 150°. The simulation results showed that the more hydrophobic is, the more liquid water movement was facilitated. Also, in the case of higher contact angles, the contact area between liquid water and substrates was decreased, and the area of gas-liquid interface was increased, and it was observed that the curvature of gas-liquid interface increased.
Numerical Simulation of Local Entropy Generation of Oxygen Transport in Cathode Diffusion Media of PEFC
Authors: Nishida Kosuke
Published: September 2023

The oxygen transport in cathode electrodes of polymer electrolyte fuel cells (PEFCs) is a key process for determining their power generation performance. To identify the factors affecting its transport loss, this study introduced the analysis of local entropy generation into the conventional two-phase flow simulation in the cathode gas diffusion layer (GDL) of a PEFC and estimated the distribution of the entropy production rate due to oxygen diffusion. The effect of land-channel geometry on its entropy generation in the GDL was also evaluated. The results revealed that the entropy generation of oxygen diffusion becomes remarkably high under the boundary between the channel and land that causes its large concentration gradient. It was also found that the entropy generation due to oxygen diffusion in the GDL increases with an increase in the water accumulation during the operation.
Control of Liquid Water Transport in Cathode of PEFC Using Wettability-Patterned Electrodes
Authors: Kaneko Reiya , Chate Vedant , Nishida Kosuke
Published: September 2023

To address the issue of flooding in polymer electrolyte fuel cells (PEFCs), it becomes imperative to devise an electrode structure capable of actively removing accumulated liquid water within the gas diffusion electrode (GDE). This study aimed to construct a wettability patterned electrode by applying a hydrophilic solution onto the cathode-side gas diffusion layer (GDL). Furthermore, the distribution of liquid water within the patterned electrode during PEFC operation was visualized using X-ray imaging and image processing technology. As a result, it was confirmed that the introduction of a wettability patterned electrode structure enables liquid water transport control during operation and reduces the saturation of liquid water around the hydrophilic region.
Quantification Method of Mass Transfer Resistance in Cathode Catalyst Layer in PEFC
Authors: Ogawa Hikaru , Okada Yuji , Kageyama Miho , Gyoten Hisaaki , Murakami Shuka , Kawase Motoaki
Published: September 2023

The quantification method of mass transfer resistance in the cathode catalyst layer (CCL) should be established in order to appropriately evaluate the cell performance. Lots of PEFC research assumes that any resistances in PEFC are in series to reaction resistance. In this study, oxygen and proton transfer resistances in CCL were quantitatively separated from reaction resistance by applying the model where the through-plane mass- transport resistances were parallel to the reaction resistance. In order to evaluate oxygen and proton transfer resistance, a dimensionless cathode isothermal one-dimensional model was applied. The mass transfer resistance in CCL can be quantitatively evaluated by obtaining the value of five dimensionless moduli derived from mass balance. Polarization curves dependency on the oxygen partial pressure and relative humidity (RH) were measured at the temperature of 80 °C. Reaction rate parameters, effective oxygen diffusion coefficient, effective proton conductivity, and oxygen permeance through the ionomer layer were determined.
Effect of Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layers on PEFC Performance
Authors: Wang Peng , Nakajima Hironori , Kitahara Tatsumi
Published: September 2023

Addressing the voltage loss problem at high current densities is crucial to expand PEFCs output power. One approach to improve water management and extend the cell operating range is modifying the microporous layer (MPL) coated on the gas diffusion layer (GDL). This study developed a novel MPL coated GDL preparation method featuring randomly allocated hydrophobic and hydrophilic pores within the same layer, which was proven by the water permeability test. This design allows excess water at the interface between the catalyst layer (CL) and MPL to be expelled through the hydrophilic pores while maintaining gas transport via the hydrophobic pores to reduce the mass transport resistance. Various hydrophobic and hydrophilic materials were tested, and the different compositions were evaluated to determine the appropriate combination. The results demonstrated that the composite MPL further reduced total oxygen transport resistance compared to the conventional hydrophobic MPL.
Interaction of Catalysts for Unitized Regenerative Fuel Cells
Authors: Maletzko Annabelle , Gomez Villa Eduardo Daniel , Kintzel Birgit , Fietzek Harald , Schmidt Gordon , Christen Jürgen , Veit Peter , Kühne Philipp , Melke Julia
Published: September 2023

Unitized regenerative fuel cells have emerged as promising energy conversion and storage systems for various applications. However, in order to optimize their efficiency, it is crucial to enhance the performance of the bifunctional catalyst. This study aims to provide deeper insights into the electrochemical behavior and performance of the bifunctional catalyst. Several electrocatalysts were prepared and evaluated using rotating disk electrode measurements. The focus was placed on investigating the interaction between Pt, Ir, and the support material, antimony doped tin oxide (ATO), and their impact on the oxygen evolution reaction and oxygen reduction reaction. Among the analyzed catalysts, Pt-black mixed with synthesized IrO2 supported on developed ATO exhibited the highest performance, considering the results from both the fuel cell and electrolyzer systems.
Projected Fuel Cell Stack Costs Using Non-PGM Cathode Electrocatalysts
Authors: Swider-Lyons Karen , Patel Sejal , Rainford Chris
Published: September 2023

Proton exchange membrane (PEM) fuel cells presently contain platinum (Pt) at their cathode and anode for catalysis of oxygen and hydrogen, respectively. Replacing the Pt at the fuel cell cathode with electrocatalysts having no precious group metals (non-PGM or PGM-free) is a vibrant research area, aiming to protect against any rapid increase in the cost ofplatinum. However, the activity of non-PGM catalysts is presently low, so more cells, including the PEM, bipolar plates, etc., are needed to reach a rated power for a stack with a non-PGM cathode. Technoeconomic analysis (TEA) shows that a stack with non-PGM catalysts would be approximately 2.9× the size of a stack with a standard Pt cathode catalyst and would cost about 2.3× more. The stacks must still be recycled to reclaim the Pt at the anode catalyst, but recycling becomes less cost competitive as the amountof Pt in stack decreases. We conclude that for economic viability, the performance and durability of non-PGM catalysts must approach that of Pt, and researchers should investigate non-PGM anodes to eliminate recycling needs.
Molecular analysis of hydrogen-bond structures in polymer electrolyte membrane in polymer electrolyte fuel cells below freezing temperatures
Authors: Nishizawa Hiroki , Mabuchi Takuya , Uene Naoya , Tokumasu Takashi
Published: September 2023

The PEFC has been attracted to achieve carbon neutralization with using of cars and so on. Unclearness of the internal state of the polymer electrolyte membrane (PEM) below freezing temperature is one of the biggest problems toward expansion of operating temperature. Our final objective is to reveal the internal state of PEM and transport mechanism in such environment. We performed the reactive force field molecular dynamics to analyze the internal structure of PEM because under such environment chemical reaction is the key transport mechanisms. A radial distribution function (RDF) was performed to analyze the structure in PEM. Our RDF was in good agreement with other simulation results. We found the increase of water molecules in the overlapped solvation area with the decrease in temperature. The water molecules hardly move in the overlapped area, indicating that proton diffusivity decreases.
Suppression of PEFC Membrane Degradation By Using SnO2 As Electrocatalyst Support
Authors: Nakamura Shogo , Ogawa Taichi , Gautama Zulfi , Noda Zhiyun , Yasutake Masahiro , Lyth Stephen Matthew , Matsuda Junko , Hayashi Akari , Nishihara Masamichi , Sasaki Kazunari
Published: September 2023

Chemical degradation of polymer electrolyte membranes (PEMs) is a significant issue related to the durability of polymer electrolyte fuel cells (PEFCs). Previous studies have reported that certain ions dissolved from e.g. electrocatalyst materials can accelerate the chemical degradation of PEMs by promoting radical formation via the Fenton reaction. In this study, the influence of using an SnO2 support within the cathode catalyst layers on chemical degradation of the PEMs is evaluated. Accelerated chemical degradation tests were conducted by holding the cell at open circuit voltage (OCV) for 100 h, and the change in thickness of the PEMs were recorded. The results suggest that the use of SnO2 as an alternative metal oxide support for cathode catalysts can effectively suppress chemical degradation in PEMs.
Exploring Proton Activity at the Membrane/Electrode Interface with Microelectrodes
Authors: Anderson Grace C. , Rajupet Siddharth , Petrovick John G. , Kushner Douglas I. , Bell Alexis T. , Weber Adam Z.
Published: September 2023

Microelectrode measurements using a polycrystalline platinum microelectrode were used to simulate the membrane/electrode interface of a membrane-electrode-assembly (MEA) architecture. The proton activity for the hydrogen-evolution reaction (HER) was evaluated for 40, 60, and 80% relative humidity. Proton activity was calculated to be 0.5, 1.0 and 2.0 for 40, 60, and 80% relative humidity, respectively, using open circuit potential measurements between Nafion 211 and 1 molal HClO4. The fraction of protons which dissociate at a given relative humidity condition appears to be a distinctive factor in proton activity for Nafion 211 compared to an aqueous electrolyte. The microelectrode measurements exhibited a Tafel slope of ~120 mV/dec, similar to that observed for platinum in MEA systems, demonstrating that kinetic measurements made with microelectrodes can be representative of MEA kinetics.
Effects of Oxygen Defects in Zr Oxide-Based Thin Films on Oxygen Reduction Reaction in Acidic Media
Authors: Watanabe Yuri , Matsuzawa Koichi , Monden Ryuji , Nagai Takaaki , Ishihara Akimitsu
Published: September 2023

Zirconium oxide thin films were prepared by RF magnetron sputtering as model catalysts for oxygen reduction reaction (ORR) in acidic media. The effects of sputtering conditions on ORR activity in acidic media was investigated. The effect of the deposition temperature on the ORR activity depended on whether the deposition atmosphere contained oxygen (Ar+O2, Ar+N2+O2) or only nitrogen (Ar+N2). In the range of 300-800 °C of the deposition temperature, the electrodes prepared in an Ar+N2 showed higher ORR activity. XRD and XPS results showed that the tetragonal phase grew in an Ar+N2 atmosphere, while a mixed phase of tetragonal and monoclinic phases grew in an Ar+O2 atmosphere. It was found that Zr oxide thin film with a high proportion of tetragonal phase showed high ORR activity.
Ta2O5 Catalyst Support for Polymer Electrolyte Fuel Cells
Authors: Sanami Kojiro , Nishiizumi Ryosuke , Yasutake Masahiro , Noda Zhiyun , Lyth Stephen Matthew , Matsuda Junko , Hayashi Akari , Sasaki Kazunari
Published: September 2023

The platinum electrocatalysts widely used in polymer electrolyte fuel cells (PEFCs) cause oxidative degradation of the carbon support especially under start-stop cycling conditions at the cathode. In addition, the potential fluctuations caused by load cycling promote Pt particle size growth, thereby decreasing their catalytic activity. In this work we investigate the use of tantalum oxide (Ta2O5) as a thermochemically stable electrocatalyst support under strongly-acidic and high voltage conditions, as a means to suppress carbon corrosion. Pt-Co alloy nanoparticles decorated on Ta2O5 in turn supported on a mesoporous carbon (MC) scaffold were synthesized and used in the electrocatalyst layer. Microstructural observation confirmed that both Ta2O5 and Pt-Co alloy particles were loaded within the carbon scaffold mesopores. The resulting electrocatalysts displayed significantly improved oxygen reduction reaction activity in half-cell measurement, as well as improved start-stop and load cycle durability by the prevention of carbon corrosion and ripening.
Performance of a Small PEMFC Stack Operated with CO/H2 Mixtures
Authors: Yazici Mehmet S , Yıldırım Ceyhun , Kilic Murat , Turk Betul Erdor , Boyaci San Fatma Gul , Okumus Emin
Published: September 2023

CO tolerance of Ti0.8Mo0.2O2–C supported 40 wt.% Pt electrocatalysts was measured at 0.5 mg/cm2 loading with a 2-cell PEM fuel cell stack. Long-term operation under CO and switching gas composition between hydrogen and CO shows recovery of performance after poisoning. Anode catalyst loading of 0.5 mgPt/cm2 was enough to give reasonable performance under 100 ppm CO. There was no effect of stack orientation on short-term performance.
On the Importance of the Volcano Slope and Mechanistic Pathways to Comprehend Activity and Selectivity Trends in Electrocatalysis
Authors: Exner Kai S.
Published: September 2023

In this conference proceeding, the importance of the volcano slope to the description of catalytic processes with applications in energy conversion and storage is discussed. Herein, the oxygen evolution – 2 H2O → O2 + 4 H+ + 4 e–, U
0 = 1.23 V vs. RHE (reversible hydrogen electrode) – and oxygen reduction – O2 + 4 H+ + 4 e– → 2 H2O, U
0 = 1.23 V vs. RHE – reactions are chosen as prototypical examples.
A Three-Dimensional, Multiphysics Model of An Alkaline Electrolyzer
Authors: Martinho Diogo Loureiro , Berning Torsten , Abdollahzadehsangroudi Mohammadmahdi , Rasmussen Anders Rønne , Hærvig Jakob , Araya Samuel Simon
Published: September 2023

As the most mature technology within the electrolysis field, alkaline electrolyzers are expected to play an important role in the energetic transition. Advantages as their simplicity, modularity and low-cost components make it an interesting technology for the near future. However, the fundamental physics are complex as it includes multicomponent, multiphase flow, porous media, electrochemistry and heat transfer. To have a better understanding of these phenomena, the presented work is devoted to the development of a computational fluid dynamic model to better understand the behavior of all the species that are part of this technology.
Durability of Water Electrolysis Cells Against the Long-Term Voltage Fluctuation Simulating Wind Power
Authors: Hoshii Taisei , Sasaki Kazunari , Hayashi Akari
Published: September 2023

Long-term durability equivalent to 320 days was evaluated using the potential fluctuation protocol with upper potential of 2.3 V. The current density drastically decreased during the accelerated potential fluctuations, but mostly recovered by providing the sufficient rest time, suggesting that the stagnation of the generated gas causes the reversible current loss. Besides the reversible current loss, a small portion of irreversible current losses were found. From detailed evaluation of the anode structure, a partial delamination of the anode and increased pore diameter within the anode after accelerated potential fluctuation test were observed, which was not observed in our shorter potential fluctuation test. A possible reason for this difference was found to be related to the initial anode structure. The dense anode structure most likely makes produced oxygen gases hard to escape from pores, leading to increase in the pressure within the pores and finally the destruction of the anode.
Visualization of Oxygen Bubbles on a Flat Ionomer-Coated Platinum Electrode
Authors: Suwa Hideki , Kanemoto Ryo , Toyama Kohei , Kishi Sota , Araki Takuto
Published: September 2023

To improve the performance of polymer electrolyte membrane water electrolyzers (PEMWE), it is necessary to grasp oxygen transport from the reaction site. This paper presents a visualization study which examines the effect of ionomers on the behavior of oxygen bubbles generated from catalyst covered with ionomers. The bubbles are captured with a high-speed camera, and the post visualization by electron microscopy with EDX showed that there were no significant cracks and damages on the ionomers. This implies that oxygen bubbles are generated on the ionomer surface without an apparent three-phase boundary (i.e., catalyst-ionomer-water). This suggests oxygen generated on the Pt surface was transported as dissolved oxygen through the ionomer layer.
The Business Model of an Emerging Hydrogen Market in the Swedish Transportation Sector – outlook towards 2050
Authors: Särnbratt Mirjam , Fransson Nathalie , Hansson Herman , Sernhed Kerstin , Lygnerud Kristina , Andersson Martin
Published: September 2023

An improved understanding of the emerging business models for hydrogen applied in the transport sector is crucial to remove barriers for hydrogen uptake. The aim of this study is to create a characterisation of the current landscape for hydrogen road mobility in Sweden by mapping out the business model for hydrogen producers, hydrogen filling station owners and hydrogen vehicle manufacturers. This has been achieved by interviewing hydrogen market actors in the Swedish transport sector and through validation of the results in an expert elicitation. The main finding of the study is that the business model is still emerging and contains large uncertainties also about the viability of the business case. This is noticeable for example in the key partner section in the business model. Actors seek out partnerships and collaboration both horizontally and vertically along the hydrogen value chain, even with future competitors, to create a critical mass of supply and demand to enable the hydrogen market to take off. Additional value propositions and revenue streams, such as support services to the electrical grid and utilisation of residual products (excess heat and oxygen), are secondary in the business model today.
Enhancement in the Rate of CO2 Photoreduction Using Divalent Strontium Cation (Sr2+) Doped TiO2 Nanotube Arrays
Authors: Vrushabendrakumar Damini , Alam Kazi , Kumar Navneet , Chaulagain Narendra , Rajashekhar Harshitha , Riddell Saralyn , Shankar Karthik
Published: September 2023

We explored the selective surface doping of anodically formed TiO2 nanotube arrays (TNTAs) with divalent Sr2+ cations using an electrochemical cathodization process in order to modify the basicity of the surface and modify the interactions of the surface with vapor phase CO2. The resulting Sr-doped TNTAs showed a 3-fold increase in CO2 photoreduction activity. Characterization using a broad suite of bulk- and surface-sensitive characterization techniques revealed the doped Sr atoms to be widely dispersed on the surface. Our results show a way forward to achieve single atom catalysts using cathodic doping of TiO2.
Total Energy and Total Power for the SOEC: Critical Role of Area Specific Resistance in Hydrogen Production Rate
Authors: Williams Mark
Published: September 2023

This paper develops the governing Total Energy (TE) (kilowatt-hours per kilogram hydrogen) and Total Power (TP) equations for Solid Oxide ElectrolyzerCells (SOECs) and Solid Oxide Fuel Cells (SOFCs). The TE equation includes heat input, exergetic flows, enthalpy of vaporization, pressurization, heat loss, area specific resistance (ASR), etc. The TE equation developed, as it would happen, correlates well with the Idaho National Laboratory (INL) proven SOEC performance of 45 kilowatt-hours per kilogram hydrogen at 20 bars and 725 K. TE is the key performance equation necessary for designing, predicting, and planning for SOEC and SOFC performance and cost. The ASR has a critical role in SOEC TE and TP. The ASR and the targets for ASR necessary to meet important DOE performance targets are discussed.
Dr. Virkar's Self-Reflections on Research Career
Authors: Virkar Anil
Published: September 2023

I have been helped by many mentors and mentees. My greatest mentor has been my father, who received PhD in organic chemistry in 1942, more than two years before I was born. That made both my brother (who has a PhD in mathematics) and myself pursue higher education. I have been immensely helped by many mentors. I will briefly talk about them. At Northwestern University, Prof. Morris E. Fine, who was not my advisor, but had a profound influence on me. His dedication to work is unparalleled. He retired at age 65 (as was the case then) but continued as Professor Emeritus until his death at the age of 97. It was amazing for me to see that he went to work at least 3 days a week well into his 90’s. One week, he did not go to school, so people from the MSE department at Northwestern went to his house, only to find that he had passed away in his sleep. This paper gives my reflections of my career.
(Invited) On Degradation Mechanisms of Ni-YSZ Fuel Electrodes in Solid Oxide Cells
Authors: Mogensen Mogens Bjerg , Mogensen Gurli
Published: September 2023

This is a continuation of a series of articles by the principal author on degradation of Ni-YSZ cermet electrodes. This one gives a brief listing of the main aspects and in particular of the disagreements in literature on the long term degradation mechanisms of Ni-YSZ electrodes at high current density. Two main hypotheses are presented, and the weaknesses and strengths are briefly discussed. Recommendations for alleviation of the degradation are given as well as for needed experiments in the future.
Solid Oxide Electrochemical Cells for Nitrogen and Oxygen Production
Authors: Sun Xiufu , Mondi Francesco , Monich Patricia Rabelo , Pirou Stéven , Frandsen Henrik Lund , Hendriksen Peter Vang
Published: September 2023

This work presents an efficient electrochemical process for N2 and O2 production based on a solid oxide electrochemical cell technology by oxygen extraction from air. Cells with a 53×53 mm2 size consist of ca.10 μm CGO electrolyte sandwiched between composite electrodes made from either LSCF-CGO, or LSF-CGO were produced by a conventional tape casting method. To boost performance at low temperature, the electrodes were infiltrated with Pr-oxide. The electrochemical performance of the cells were characterized by iV and EIS at different temperatures with air used as feed stock to the cathode compartment and air, or oxygen used as sweep gas to the anode compartment. A voltage below 200mV is achieved to drive a current of 1A/cm2 through the cell, which can provide a purity of 90% of N2 at 650 °C. The cells were demonstrated to operate for producing a >98% pure N2 stream without degradation over a 1500h period at cell voltages below 255mV.
Opto-Electrical Properties of Graphene Oxide Liquid Crystal Films
Authors: Abdel-Motagaly Ali T. , Farghali A. A. , Zedan I. T. , El-Nahass M. M.
Published: September 2023

Graphene Oxide Liquid Crystal (GOLC) was prepared using the improved Hummer’s method. A particular purification methodology is used to reduce the disadvantages of the common purification methods. The thin films of GOLC were prepared using a wasteless low-cost drop-casting method. The optical parameters are determined for GOLC films of different thicknesses in the range from 400 nm to 2000 nm. The spectral distribution of transmittance and reflectance of GOLC films was investigated in the wavelength range from 300 nm to 2000 nm. The refractive index of GOLC films was analyzed according to the single oscillator model. The oscillator and dispersion energies are estimated using the Wemple-DiDomenico (WDD) method. The allowed transitions in GOLC films are found to be indirect, with the energy gap decreasing gradually with increasing film thickness in the investigated range. The optical and electrical conductivities as functions of photon energy are explored. Also, the third-order susceptibility and non-linear refractive index are calculated.
Theoretical Investigations of Lead-Free Halide Perovskites Na2AgInY6 (Y = Cl, Br, I) for Transport and Optoelectronic Devices
Authors: Mustafa Ghulam M. , Basheer Farzan , Noor N. A. , Younas Bisma , Mahmood Asif , Iqbal Muzammil , Almubaddel Fahad S.
Published: September 2023

Lead-free double perovskites are stable, non-toxic, and have high conversion efficiency, better oxidation resistance, and high-temperature stability, making them promising for optoelectronic and thermoelectric materials. In the current report, we have examined structural, electronic, optical, and transport characteristics of Na2AgInY6 (Y = Cl, Br, I) utilizing DFT-based Wien2k code. Thermodynamic stability is verified by calculating the enthalpy of formation. TB-mBJ measures the bandgap computations, and the investigated compositions have indirect bandgaps. The bandgap values are decreased from 3.1 eV to 1.2 eV as the halide ion is replaced from Cl - I. This substitution-dependent tuning of band edge across the visible-infrared boundary makes them favorable for solar cell applications. The optical response is evaluated by measuring the refractive index, dielectric constant, absorption coefficient, and reflectivity. The thermoelectric efficiency of Na2AgInY6 (Y = Cl, Br, I) is calculated by figure of merit and power factor. The findings of this study unveil the potential of these novel compositions for next-generation energy harvesting devices, including solar cells and thermoelectric devices.
Polarization Properties of Wurtzite III-Nitride Alloys Using the Hexagonal Reference Structure
Authors: Benbedra Abdesamed , Meskine Said , Boukortt Abdelkader , Abbassa Hamza , Abbes El Habib
Published: September 2023

The layered-hexagonal structure was proposed as a reference by Dreyer et al. [Phys. Rev. X 6, 021038 (2016)] to determine polarization properties of wurtzite materials. Using this reference in the context of the Berry-phase theory, we study the polarization of wurtzite III-nitride ternary alloys Al
x
Ga1−x
N, In
x
Ga1−x
N and In
x
Al1−x
N. We report composition-dependent expressions of the spontaneous and piezoelectric polarizations and compare these values to the zincblende results. It is found that both spontaneous and piezoelectric components exhibit nearly linear dependence on alloy concentration, which means they follow the linear behavior predicted by Vegard’s law. The total-polarization charge of the quaternary-alloy heterostructure Al
x
In
y
Ga1−x−y
N/GaN is also investigated based on the hexagonal structure. We show that the polarization charge results to be zero at certain Al and In contents, giving heterostructures free of built-in electric fields and thus allowing the design of high-efficiency optical devices. Furthermore, we compute the total-polarization charge of Al
x
Ga1-x
N/GaN, In
x
Ga1−x
N/GaN and In
x
Al1−x
N/GaN. These values are compared to available theoretical and experimental data in order to validate the results of our simulation.
Relationship between Nontraumatic Shoulder Disorders and Neuropathic Pain: Retrospective Observational Analyses of Clinical Features and Background Factors
Authors: Sasaki Tsuyoshi , Shitara Hitoshi , Tajika Tsuyoshi , Ichinose Tsuyoshi , Hamano Noritaka , Kamiyama Masataka , Yamamoto Atsushi , Kobayashi Tsutomu , Takagishi Kenji , Chikuda Hirotaka
Published: September 2023

Background. Accurate identification of neuropathic pain is necessary for appropriate treatment; however, the relationship between nontraumatic shoulder disorders and neuropathic pain remains unknown. Therefore, this retrospective observational study aimed to investigate the relationship, features, background factors, and prevalence of neuropathic pain among patients with nontraumatic shoulder disorders. Methods. We evaluated 198 patients who visited our outpatient clinic, which specializes in shoulder disorders, from April 2015 to March 2016. The patients’ age, sex, affected side, diagnosis, and pain duration were recorded, and the results of physical examination, including passive range of motion, impingement sign, and muscular strength assessments, were analyzed. The presence of neuropathic pain was assessed using the painDETECT questionnaire. Participants were divided into two groups according to the presence of neuropathic pain. Pain intensity was assessed using a visual analog scale, and the patient’s mental status was assessed using the short-form McGill Pain Questionnaire and Hospital Anxiety and Depression Scale. The scores were compared between the groups. Results. Neuropathic pain was observed in 7.6% of patients. The visual analog scale score for pain, short-form McGill Pain Questionnaire score, and Hospital Anxiety and Depression Scale score were significantly associated with the presence of neuropathic pain in the univariate analysis. Patient background factors and physical function were not associated with the presence of neuropathic pain. The prevalence of neuropathic pain in patients with frozen shoulder was 33.3%, which was significantly higher than that in patients with other shoulder disorders. Conclusion. The occurrence of neuropathic pain may aggravate pain in patients with nontraumatic shoulder disorders. Neuropathic pain was not a rare condition in patients with nontraumatic shoulder disorders, particularly in those with frozen shoulder. The coexistence of neuropathic pain cannot be determined from background factors or physical function. Accurate diagnosis of neuropathic pain is essential in patients with nontraumatic shoulder disorders.
Pharmaceutical Assessment of the Impact of the Method of Extraction on the Suitability of Pectin from Plantain (Musa paradisiaca) Peels as a Suspending Agent in Oral Liquid Formulations
Authors: Owusu Frederick William Akuffo , Acquah Prince George Jnr , Boakye-Gyasi Mariam E. L. , Johnson Raphael , Yeboah Genevieve Naana , Archer Mary-Ann , Antwi Mercy Birago , Asare Sandra Obenewaa
Published: September 2023

Natural polymers such as pectin have gained increased utilization in pharmaceutical and biotechnology sectors because they are affordable, easily accessible, nontoxic, and chemically modifiable, with the potential to be biodegradable and biocompatible. Musa paradisiaca (plantain) peels make up 30–40% of the overall weight of the fruit. The extraction of pectin from these residues can therefore be viewed as a possible waste of wealth. This study, therefore, focused on evaluating the suspending properties of pectin obtained from Musa paradisiaca (plantain) peels (through acid and alkaline extraction) and presented an alternative suspending agent in the pharmaceutical formulation of suspensions. The unripe peels of Musa paradisiaca were acquired and authenticated at the Department of Pharmacognosy, Faculty of Pharmacy and Pharmaceutical Sciences, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana. Pectin was extracted from the peels using both acid and alkaline extraction processes, respectively, characterized, and evaluated for its phytochemical properties. Different concentrations of the acid and alkaline pectin extracts were employed as a suspending agent in paracetamol suspensions, using acacia gum as a standard. The pectin yields obtained were 4.88% and 7.61% for the acid and alkaline extraction processes, respectively, while phytochemical screening revealed the presence of glycosides, tannins, saponins, and phenols in both extracts. The alkaline pectin extract recorded higher equivalent weight, degree of esterification, ash content, and crude content than the acid pectin extract, while FTIR identified similar functional groups in both acid and alkaline pectin extracts. The test suspensions reported significant differences (

P

 < 0.05) in flow rates, ease of redispersion, sedimentation volumes, and rates compared with acacia gum. Moreover, when the acid and alkaline pectin extracts were compared, significant differences (

P

 < 0.05) were observed in sedimentation rates and sedimentation volumes, suggesting that the extraction method may affect suspending properties. Ultimately, the alkaline pectin extract had better suspending properties than the acid pectin extract; however, they both can be used as an alternative to acacia gum as a suspending agent.
Coronary Atherosclerosis Across the Glycemic Spectrum Among Asymptomatic Adults: The Miami Heart Study at Baptist Health South Florida
Authors: Patel Kershaw V. , Budoff Matthew J. , Valero-Elizondo Javier , Lahan Shubham , Ali Shozab S. , Taha Mohamad B. , Blaha Michael J. , Blankstein Ron , Shapiro Michael D. , Pandey Ambarish , Arias Lara , Feldman Theodore , Cury Ricardo C. , Cainzos-Achirica Miguel , Shah Svati H. , Ziffer Jack A. , Fialkow Jonathan , Nasir Khurram
Published: September 2023

BACKGROUND:

The contemporary burden and characteristics of coronary atherosclerosis, assessed using coronary computed tomography angiography (CCTA), is unknown among asymptomatic adults with diabetes and prediabetes in the United States. The pooled cohort equations and coronary artery calcium (CAC) score stratify atherosclerotic cardiovascular disease risk, but their association with CCTA findings across glycemic categories is not well established.

METHODS:

Asymptomatic adults without atherosclerotic cardiovascular disease enrolled in the Miami Heart Study were included. Participants underwent CAC and CCTA testing and were classified into glycemic categories. Prevalence of coronary atherosclerosis (any plaque, noncalcified plaque, plaque with ≥1 high-risk feature, maximal stenosis ≥50%) assessed by CCTA was described across glycemic categories and further stratified by pooled cohort equations–estimated atherosclerotic cardiovascular disease risk and CAC score. Adjusted logistic regression was used to evaluate the associations between glycemic categories and coronary outcomes.

RESULTS:

Among 2352 participants (49.5% women), the prevalence of euglycemia, prediabetes, and diabetes was 63%, 30%, and 7%, respectively. Coronary plaque was more commonly present across worsening glycemic categories (euglycemia, 43%; prediabetes, 58%; diabetes, 69%), and similar pattern was observed for other coronary outcomes. In adjusted analyses, compared with euglycemia, prediabetes and diabetes were each associated with higher odds of any coronary plaque (OR, 1.30 [95% CI, 1.05–1.60] and 1.75 [1.17–2.61], respectively), noncalcified plaque (OR, 1.47 [1.19–1.81] and 1.99 [1.38–2.87], respectively), and plaque with ≥1 high-risk feature (OR, 1.65 [1.14–2.39] and 2.53 [1.48–4.33], respectively). Diabetes was associated with stenosis ≥50% (OR, 3.01 [1.79–5.08]; reference=euglycemia). Among participants with diabetes and estimated atherosclerotic cardiovascular disease risk <5%, 46% had coronary plaque and 10% had stenosis ≥50%. Among participants with diabetes and CAC=0, 30% had coronary plaque and 3% had stenosis ≥50%.

CONCLUSIONS:

Among asymptomatic adults, worse glycemic status is associated with higher prevalence and extent of coronary atherosclerosis, high-risk plaque, and stenosis. In diabetes, CAC was more closely associated with CCTA findings and informative in a larger population than the pooled cohort equations.
Impact of the dominant competitor on the aggressiveness of host ants toward slave-makers
Authors: Włodarczyk Tomasz
Published: September 2023

Slave-making ants might exert strong pressure on their host populations by pillaging their nests and sometimes destroying the whole colonies. Consequently, host ants have evolved many adaptations reducing the probability of being attacked, resisting an assault or, as a last line of defence, minimising the losses associated with a successful slave-maker invasion. This paper presents the results of a study on a common Palearctic ant species, Formica fusca, which falls victim to slave raids organised by the congeneric F. sanguinea. Slave-making ants were placed close to the nest entrance of the host ants, and the subsequent instances of aggression were recorded. The study was carried out in the context of the influence of the dominant competitor by selecting host colonies located within and outside the territory of the wood ants (F. rufa and F. polyctena). This approach enabled the potential co-evolutionary interplay among three species performing different roles in mutual ecological interactions. The F. fusca ants reacted with aggression to the slave-making ants but not to the dominant competitors. Moreover, the avoidance of the aggression of host ants toward wood ants entails an environment-induced component, besides the presumably inherited one. The impact of the dominant competitor as a territory holder manifests itself in the reduced promptness of F. fusca ants to defend their colonies against slave-makers. The results suggest that this effect is mediated by the negative impact of wood ants on F. fusca colony size.
Hobbes on the Cause of Action: How to Rethink Practical Reasoning
Authors: Pécharman Martine
Published: September 2023

In the free-will discussion between Hobbes and Bramhall, Hobbes’s principle that actions are necessary is not immediately action-theoretic. The fundamental theoretical context of Hobbes’s explanation of action lies in an understanding of causation more generally. However, Hobbes’s action theory is not simply modeled after the account of cause and effect in his First Philosophy. It introduces a temporal qualification which ranks necessitarianism higher than First Philosophy does: not only a voluntary action, but also the determinate moment when the mental act of volition is formed, is necessitated. My paper argues that this strengthening of causal necessity is due to the Hobbesian scheme of deliberation, which must be analyzed in terms of one distinctive kind of ‘mental discourse’ and practical reasoning, not merely in terms of a series of passions. For Hobbes, the impossibility of a direct representation of the future requires the mediation of a mental construction.
Reisen als Grenzüberwindung?
Authors: Ubl Linus
Published: September 2023

On several layers, Fortunatus can be described as a liminal text. This does not only apply to the level of materiality or the readership of the novel but in particular to content and structure. Using an anthropological perspective and assessing the numerous transitions which the main protagonists, Fortunatus and his son Andolosia, undergo, this article demonstrates that these transitions ultimately result in the different outcomes for the two generations. In addition, the woodcuts of the text’s first edition undermine this reading through their arrangement. In conclusion, the structural order in combination with its figurative elaboration shape the character of the text as a negotiation of rites of passage.