bluuebunny/crossref_metadata_2025 huggingface dataset:
Homocitrullination of lysine residues mediated by myeloid-derived suppressor cells in the tumor environment is a target for cancer immunotherapy
Authors: Cook Katherine W , Xue Wei , Symonds Peter , Daniels Ian , Gijon Mohamed , Boocock David , Coveney Clare , Miles Amanda K , Shah Sabaria , Atabani Suha , Choudhury Ruhul H , Vaghela Poonam , Weston Daisy , Metheringham Rachael L , Brentville Victoria A , Durrant Lindy G
Published: July 2021

Background

Homocitrullination is the post-translational modification of lysine that is recognized by T cells.

Methods

This study identified homocitrullinated peptides from aldolase, enolase, cytokeratin and binding immunoglobulin protein and used human leukocyte antigen (HLA) transgenic mice to assess immunogenicity by enzyme-linked immunosorbent spot assay. Vaccine efficacy was assessed in tumor therapy studies using HLA-matched B16 melanoma expressing constitutive or interferon γ (IFNγ)-inducible major histocompatibility complex class II (MHC-II) as represented by most human tumors. To determine the mechanism behind the therapy, immune cell infiltrates were analyzed using flow cytometry and therapy studies in the presence of myeloperoxidase (MPO) inhibitor and T-cell depletion performed. We assessed the T-cell repertoire to homocitrullinated peptides in patients with cancer and healthy donors using flow cytometry.

Results

Homocitrulline (Hcit) peptide vaccination stimulated strong CD4 T-cell responses and induced significant antitumor therapy in an established tumor model. The antitumor response was dependent on CD4 T cells and the effect was driven mainly via direct tumor recognition, as responses were only observed if the tumors were induced to express MHC-II. In vitro proliferation assays show that healthy donors and patients with cancer have an oligoclonal CD4 T-cell repertoire recognizing homocitrullinated peptides. Inhibition of cyanate generation, which mediates homocitrullination, by MPO inhibition reduced tumor therapy by the vaccine induced T cells (p=0.0018). Analysis of the tumor microenvironment (TME) suggested that myeloid-derived suppressor cells (MDSCs) were a potential source of MPO. The selected B16 melanoma model showed MDSC infiltration and was appropriate to see if the Hcit vaccine could overcome the immunosuppression associated with MDSCs. The vaccine was very effective (90% survival) as the induced CD4 T cells directly targeted the homocitrullinated tumor and likely reversed the immunosuppressive environment.

Conclusion

We propose that MPO, potentially produced by MDSCs, catalyzes the buildup of cyanate in the TME which diffuses into tumor cells causing homocitrullination of cytoplasmic proteins which are degraded and, in the presence of IFNγ, presented by MHC-II for direct CD4 T-cell recognition. Homocitrullinated proteins are a new target for cancer vaccines and may be particularly effective against tumors containing high levels of MPO expressing MDSCs.
MYC suppresses STING-dependent innate immunity by transcriptionally upregulating DNMT1 in triple-negative breast cancer
Authors: Wu Si-Yu , Xiao Yi , Wei Jin-Li , Xu Xiao-En , Jin Xi , Hu Xin , Li Da-Qiang , Jiang Yi-Zhou , Shao Zhi-Ming
Published: July 2021

Background

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer and lacks definite treatment targets. Tumor immune microenvironment (TIME) heterogeneity has a profound impact on the immunotherapy response. Tumors with non-inflamed TIME derive limited benefit from immunotherapy. However, what drives the formation of the non-inflamed TIME in TNBC remains unclear.

Methods

Using our multiomics database of TNBC, we conducted an analysis to explore the key genomic events driving the formation of the non-inflamed TIME in TNBC. In vitro and in vivo studies further revealed potential mechanisms and the efficacy of combination treatment with immunotherapy.

Results

With transcriptomic and genomic data, we systematically analyzed the TIME of TNBC and revealed that the classical basal-like subtype of TNBC consisted of two distinct microenvironment phenotypes, defined as the ‘inflamed’ and ‘non-inflamed’ subtypes. We performed further screening and demonstrated that MYC amplification and overexpression led to low immune infiltration and cytolytic activity in TIME. Mechanistically, MYC bound to DNMT1 promoter and activated DNMT1 transcription in TNBC cells, thus suppressing the Cyclic GMP-AMP synthase (cGAS)-STING pathway via an epigenetic regulatory way. In MYC-overexpressing TNBC, decitabine, an Food and Drug Administration (FDA)-approved DNA methyltransferase inhibitor, converted tumors from non-inflamed to inflamed tumors by enhancing T cell infiltration. Furthermore, the combination of decitabine with programmed cell death protein 1 (PD-1) inhibitor reversed T cell exhaustion and improved T cell function in mouse models, which elicited potent antitumor activity in MYC-overexpressing TNBC.

Conclusions

Our work elucidates that the classic oncogene MYC induces immune evasion by repressing innate immunity. Furthermore, we provide a rationale for combining DNA methyltransferase inhibition with immunotherapy for the treatment of MYC-overexpressing TNBC.
Endovascular management of anterior falcotentorial dural arteriovenous fistulas: importance of functionality of deep venous system and existence of accompanying choroidal arteriovenous malformation
Authors: Islak Civan , Bagcilar Omer , Nacar Dogan Sebahat , Korkmazer Bora , Arslan Serdar , Kizilkilic Osman , Kocer Naci
Published: July 2021

Background

Anterior falcotentorial junction dural arteriovenous fistulas (AFDAVFs) are the most deeply located and most complex type of tentorial fistula due to their location and vascular anatomy. We aimed to make new angiographic definitions of AFDAVF nidus and functionality of the deep venous system of the brain and thereby provide a safer approach for endovascular treatment.

Methods

We retrospectively examined 18 patients with AFDAVF who received endovascular treatment at our neuroradiology department between June 2002 and May 2019. Pre- and post-treatment clinical assessments were performed using the modified Rankin Scale. AFDAVF niduses were defined as mixed-type or pure-dural-type on the basis of whether choroidal arteriovenous malformation was coexisting or not, respectively. The deep venous system was denoted as functional or nonfunctional.

Results

We included 13 men and 5 women (mean (range) age, 47.2 (31–62) years). We evaluated 15 patients with pure-dural-type AFDAVFs and three with mixed-type AFDAVFs. Complete occlusion of the fistula was achieved in 15/18 patients. Three patients had transient neurologic symptoms. In two patients these were due to mild thalamic ischemia and in the third patient was due to tectal venous ischemia, all in mixed-type AFDAVF. One patient also developed Parinaud syndrome due to compression of the tectal plate by a thrombosed large vein of Galen. No patients died or developed permanent morbidity.

Conclusion

Evaluating AFDAVFs as described here using our new subtyping model will help improve analysis of the malformation and development of a safer endovascular strategy, and hence may prevent periprocedural complications and improve treatment safety.
Path-integral approximations to quantum dynamics
Authors: Althorpe Stuart C.
Published: July 2021

Imaginary-time path-integral or ‘ring-polymer’ methods have been used to simulate quantum (Boltzmann) statistical properties since the 1980s. This article reviews the more recent extension of such methods to simulate quantum dynamics, summarising the chain of approximations that links practical path-integral methods, such as centroid molecular dynamics (CMD) and ring-polymer molecular dynamics (RPMD), to the exact quantum Kubo time-correlation function. We focus on single-surface Born–Oppenheimer dynamics, using the infrared spectrum of water as an illustrative example, but also survey other recent applications and practical techniques, as well as the limitations of current methods and their scope for future development.

Graphic abstract
Wave packet approach to quantum correlations in neutrino oscillations
Authors: Blasone Massimo , De Siena Silvio , Matrella Cristina
Published: July 2021

Quantum correlations provide a fertile testing ground for investigating fundamental aspects of quantum physics in various systems, especially in the case of relativistic (elementary) particle systems as neutrinos. In a recent paper, Ming et al. (Eur Phys J C 80:275, 2020), in connection with results of Daya-Bay and MINOS experiments, have studied the quantumness in neutrino oscillations in the framework of plane-wave approximation. We extend their treatment by adopting the wave packet approach that accounts for effects due to localization and decoherence. This leads to a better agreement with experimental results, in particular for the case of MINOS experiment.
Design and beam dynamics of CEPC damping ring system
Authors: Wang Dou , Cui Xiaohao , Meng Cai , Ji Daheng , Liu Yudong , Tian Saike , Shi Hua , Zhang Jingru , Gao Jie
Published: July 2021

A damping ring system which includes a small 1.1 GeV ring and two transport lines is introduced in CEPC linac in order to reduce the transverse emittance of positron beam at the end of linac and hence reduce the beam loss in the booster. This paper introduces the parameter choice and optics study of damping ring. The corresponding instability effect and IBS effect are also checked to make sure the design current and design emittance can be realized. Except for damping ring, two transport lines are needed to match the parameters between linac and damping ring. Both designs for energy compressor and bunch compressor including beam simulations are discussed in this paper.
Superconducting quadrupole magnet R&D in the interaction region of CEPC
Authors: Shen Chuang , Zhu Yingshun , Yang Xiangchen , Liang Ran , Chen Fusan
Published: July 2021

To obtain high luminosity, compact high gradient quadrupole magnets QD0 and QF1 are required on both sides of the interaction points of the proposed Circular Electron Positron Collider (CEPC). QD0 is a double aperture superconducting quadrupole closest to the interaction point with a crossing angle between two aperture centerlines of 33 mrad. Magnetic field crosstalk between two apertures of QD0 is negligible using iron yoke, and the 3D coil end is optimized by ROXIE. In the design study, both NbTi conductor and HTS conductor are taken into account. The first step of the R&D is to design and manufacture a QD0 short model magnet with a magnetic length of 0.5 m. In this paper, the R&D status of QD0 short model magnet is described, and the design study of quadrupole magnet including NbTi technology and HTS Bi-2212 technology is presented.
Making Waste Profitable: Yak Dung Derived Carbon for High-Performance Supercapacitors
Authors: Hu Mao , Xu Jia , Cheng Ru , Bai Wencai , Liang Chenghu , Lu Rongcier , Ren Yan , Li Chen , Zhu Wenkun , Yang Fan
Published: July 2021

With the continuous increase in the demand for energy storage equipment, it is imperative to develop new electrode materials with high specific capacitance. In this study, yak dung derived carbon materials (N-YD) were prepared by a simple, economical, and effective method, and it was applied as a supercapacitor electrode material. The N-YD-800 material exhibited high nitrogen content, as well as a large number of multipore structures, which were beneficial to improve the capacitance performance. N-YD-800 exhibited an excellent specific capacitance (346.3[Formula: see text]F[Formula: see text]g[Formula: see text] at 1[Formula: see text]A[Formula: see text]g[Formula: see text], good rate performance (56.6% from 0.5[Formula: see text]A[Formula: see text]g[Formula: see text] to 10[Formula: see text]A[Formula: see text]g[Formula: see text], and excellent cycling stability (93.3% after 5000 cycles). This study provided a new method for the treatment of livestock and poultry manure resources, affording a cost-effective, easy-to-use carbon source to solve the problem of nonrenewable energy.
Catalyst-Exsolving Anode-Supported Solid Oxide Fuel Cell
Authors: Horlick Samuel A , Robinson Ian A. , Huang Yilin , Wachsman Eric
Published: July 2021

Exsolution is the process in which cations that make up the lattice of a mixed ionic/electronic conductor (MIEC) are reduced to metals and migrate to the surface of the host ceramic. These materials have become quite attractive for solid oxide fuel cells (SOFCs) because they can facilitate oxygen and electron transport through their bulk and act as electrocatalysts on the surface of SOFC anodes. Also, because of the nature of the exsolution process, the highly dispersed nano-catalysts have strong particle-host interactions which have shown resistance to common SOFC failure mechanisms such as agglomeration and coking. However, the practical application of such materials has not been well studied since most research focuses on the electrolyte-supported cells, which offer a quick method for screening electrochemical activity but the large ohmic resistance makes this cell unrealistic for real energy conversion devices, especially at lower temperatures.

Here, we use a scalable ceramic processing technique to fabricate a ceramic-anode-supported SOFC that exsolves nano-catalysts for low temperature operation (600°C). SrFe0.2Ni0.4Mo0.4O3-
δ (SFNM) is used as the anode material due to its high conductivity and exsolution ability. By shifting the mechanically supporting layer from the electrolyte to this anode, we are able to drastically reduce the overall ohmic resistance of the cell. Additionally, we avoid extra processing steps for conventional catalyst deposition by taking advantage of the in-situ catalyst exsolution. During the exsolution process, we show that our cell performance increases over time, up to a peak power density of 300 mW/cm2 at 600°C with H2 fuel. Further, we discuss two major challenges facing exsolution-anode-supported SOFCs along the way and we show our efforts to identify and address the root causes of these problems.
Influence of Ni-Content on Crystallographic Parameters and Electrochemical Performance of the La0.25Sr0.25Ca0.4NixTi1
-
xO3
-
d
SOC Fuel Electrode
Authors: Korjus Ove , Aruväli Jaan , Kooser Kuno , Kivi Indrek , Käämbre Tanel , Lust Enn , Nurk Gunnar
Published: July 2021

The search for alternative fuel electrode materials to Ni-cermets is very active in the solid oxide cell (SOC) field due to several reasons. Metallic Ni is very sensitive to oxygen partial pressure (p
O2) and reoxidizes to NiO if p
O2 rises above the threshold level (temperature dependent). Ni-cermets are also prone to sulphur poisoning 1,2 and coking 3 if carbonaceous fuel without sufficient steam is used. Even if gases are carefully purified from sulphur, and correct steam to carbon ratio is used, metallic Ni centres still has a tendency to coarsen over time, which leads to performance losses 4,5.

Full ceramic anodes are envisaged as redox stable materials when compared to metal-cermets – there is no immense expansion relating to metal oxidation reduction cycles and these materials are more resistant to coking and sulphur depositions 6–8. La0.2Sr0.7
-
xCaxTiO3
-

d
(LSCTA-) has been demonstrated to be promising ceramic fuel electrode due to excellent electrical conductivity and stability if x ≤ 0.45 9.

In this work, we investigated the influence of Ni concentration on the crystallographic properties of La0.25Sr0.25Ca0.4Ti1
-
xNixO3
-

d

(LSCNT-x) (x = 0, 0.02, 0.05, 0.1, 0.2) using in situ X-ray diffraction. Sr mobility during the processing of electrodes with different Ni contents was demonstrated. The electrochemical performance of each synthesized electrodes was evaluated with electrochemical impedance spectroscopy (EIS) using a 3-electrode setup in LSCNT-x/GDC|GDC/ScCeSZ/GDC|LSC cell (LSC is La0.6Sr0.4CoO3
-

d
). Two-electrode measurements were also conducted with the most stable and electrochemically active electrode in order to assess its performance in working systems. Additionally, steam electrolysis experiments were performed to establishx the best electrode’s performance in electrolysis mode.

References:

G. Nurk et al., J. Power Sources, 240, 448–457 (2013) http://dx.doi.org/10.1016/j.jpowsour.2013.03.187.

S. Zha, Z. Cheng, and M. Liu, J. Electrochem. Soc., 154, B201 (2007).

X. Li et al., Phys. Chem. Chem. Phys., 17, 21112–9 (2015) http://www.scopus.com/inward/record.url?eid=2-s2.0-84939169120&partnerID=tZOtx3y1.

D. Simwonis, F. Tietz, and D. Stöver, Solid State Ionics, 132, 241–251 (2000).

O. M. Pecho et al., Materials (Basel)., 8, 5554–5585 (2015).

A. Faes, A. Hessler-Wyser, A. Zryd, and J. Van Herle, Membranes (Basel)., 2, 585–664 (2012).

Q. X. Fu and F. Tietz, Fuel Cells, 8, 283–293 (2008).

A. Atkinson et al., Mater. Sustain. Energy A Collect. Peer-Reviewed Res. Rev. Artic. from Nat. Publ. Gr., 213–223 (2004).

A. D. Aljaberi and J. T. S. Irvine, J. Mater. Chem. A, 1, 5868–5874 (2013).
A-Asterisk Algorithm as an Alternative to Evaluate the Geometric Tortuosity in Digitally Created SOFC Anodes
Authors: Espinoza Andaluz Mayken , Ávila Joseph , Pagalo Javier , Li Tingshuai , Qi Yuanxin , Li Shian , Zhang Xiaoqiang , Andersson Martin
Published: July 2021

A solid oxide fuel cell (SOFC) is an electrochemical device that convert the chemical energy present in reactant gases, usually any chemical compound with hydrogen as constitutive element, into electrical energy and heat. The energy conversion process occurs at a high temperature and in a noiseless manner. As a result, the efficiency is relatively high, especially if the co-generation is considered. Diffusion processes within the SOFC porous media plays an important role since the reactant gases have to reach the three-phase boundary to perform the energy conversion process. An in-depth analysis of the microstructural configuration offers an increased understanding of the reactant flow.

This paper aims to evaluate the feasibility of using the A-asterisk algorithm to compute the geometric tortuosity within SOFC anodes. A three-dimensional structure, which is digitally created, represents the SOFC anode, in which the possible paths that follow the fluid flow are analyzed. A-asterisk algorithm is used to generate possible paths, and therefore the geometric tortuosity can be computed considering an averaged distance. A tortuosity-porosity correlation is proposed, and the results are compared with previous studies. Results show that the A-asterisk algorithm is a capable algorithm to evaluate the geometric tortuosity values in SOFC anodes with different particle size distribution and porosities.
Update on Nexceris’ Solid Oxide Fuel Cell Stack Technology
Authors: Kopechek David , Swartz Scott , Arkenberg Gene , Dogdibegovic Emir
Published: July 2021

Over the past several years Nexceris has advanced its solid oxide fuel cell (SOFC) stack technology through innovations in materials, design, and operation. Sustainable fuel cell operation of Nexceris’ lightweight stack at high current density (0.5 – 0.7 A/cm²) and fuel utilization (70 – 80%) yields both high gravimetric power density and electrical efficiency. Stack robustness against thermal gradients, thermal cycling, and one-off events has been achieved through a combination of design modifications, sealing advancements, and operational protocols. Meanwhile, Nexceris’ stack technology maintains the key advantages of its patented FlexCell planar cell design, internal reforming capability, and tolerance to sulfur impurities in military logistic fuels.

Recent and ongoing work at Nexceris includes stack demonstrations in breadboard systems and at customer sites, scale-up of stack manufacturing capabilities, and the development of a 10-kW stack module, opening the door to large-scale distributed generation and energy storage applications. This presentation will provide an update on the status and capabilities of Nexceris’ SOFC stacks and cost-saving approaches to stack fabrication.
Sr and Co Vapor-Phase Transport from LSCF Cathodes
Authors: Kirby Brent , Hardy John S , Coyle Christopher , Canfield Nathan L , Droubay Tim
Published: July 2021

Strontium transport contributes to degradation mechanisms in SOFCs, especially strontium zirconate formation at the interface of the cathode barrier layer with the YSZ electrolyte. High temperatures required for cathode sintering lead to Sr transport during cell construction. SEM analysis of SOFCs with LSCF cathodes shows Sr at the YSZ/GDC barrier layer interface, but no Sr throughout the GDC barrier layer itself, as would be expected for solid-phase transport. Vapor-phase transport was identified as a possible mechanism that would lead to these observations. A series of tests were performed to differentiate between surface diffusion and vapor-phase diffusion of species from LSCF cathode material at typical sintering temperatures (up to 1100°C). A GDC substrate was printed with LSCF and separated by an air gap from a YSZ target substrate. First a simple spacer ring was used to create the air gap, and strontium transport was observed via SEM-EDS (energy dispersive spectroscopy). Then, various geometries with long surface paths were employed to reduce the possibility of surface transport. The target substrates were analyzed via x-ray photoelectron spectroscopy (XPS) with high sensitivity for surface species. An open air gap did not show evidence of Sr or Co transport. A refined, enclosed air gap with long surface path length did show such evidence for Sr and Co, indicating an enclosed area to maintain significant vapor pressure was necessary for transport. An SOFC with LSCF in direct contact with a barrier layer would also provide such an environment for vapor-phase transport to occur. Furthermore, spatially resolved analysis showed a relatively uniform distribution of Sr and Co across the target substrate. This supports the vapor-phase mechanism as Sr and Co transported via surface diffusion would have been fixed preferentially to the outer edge of the target substrate. These results have implications for adjusting sintering conditions and barrier layer requirements to prevent the formation of undesired strontium zirconate. This work was performed for the US DOE Office of Fossil Energy’s Solid Oxide Fuel Cell program under the Cathode Task.
Self-Supported Solid Oxide Fuel Cells by Multimaterial 3D Printing
Authors: Kostretsova Natalia , Pesce Arianna , Nuñez Marc , Morata Alex , Torrell Marc , Tarancón Albert
Published: July 2021

Nowadays, renewable energy increases its contribution to the present energy scenario. In this regard, the implementation of energy storage and sources as the electrolysers and fuel cells gives the opportunity to transform the surplus of renewable energy to the form of hydrogen, by water electrolysis and the use of this hydrogen as a fuel for energy generation by the reverse mode of the same devices, in the so-called power to gas and gas to power routes. Among the different technologies of fuel cells and electrolysers, the high temperature technology based on ceramic solid oxides presents the best efficiencies. However, the fabrication of this devices implies several manufacturing procedures and multiple intermediate steps of fabrications, such as tape-casting, screen-printing, annealing, manual stacking, joining, sealing, etc. As a result, the SOC production process becomes more expensive and time-consuming. Recently, it has been demonstrated that the application of additive manufacturing (AM) technologies for functional ceramics fabrication, specially to SOC production, leads to significant improvement of the process. AM represents freedom of design, that allows to enhance the performance of the SOC-based device, an increase of manufacturing speed and productiveness, while the waste material is reduced. As a final result, one-step printed monolithic SOFC stack could be produced combining different AM technologies in a single printing process.

For this purpose, hybrid 3D printing technology which combines stereolithography (SLA) and robocasting (direct ink writing, DIW) has been developed. Thus, the technique uses 8YSZ for the electrolyte fabrication by SLA and deposition of electrodes and interconnectors by DIW. The elaborated hybrid multimaterial 3D printing technology renders possible complete SOC stack fabrication as a single-step process. Complete fully printed SOFC cells, their co-sintering process and their characterization are here presented while the advantages and limitations of the fabrication process are discussed.
A Simplified Model for Reversible Solid Oxide Fuel Cells
Authors: Sezer Hayri , Mason Jerry H , Celik Ismail Bektas , Fan Yueying , Abernathy Harry W. , Epting William K , Kalapos Thomas , Hackett Gregory A
Published: July 2021

Abstract: Butler-Volmer Equations based on a first order approximation of global redox reaction kinetics have been used in the past successfully for design analysis of solid oxide fuel cells. Such a model forms the backbone of the widely used multidimensional code, DREAM-SOFC originally developed at West Virginia University and currently being used by the fuel cell research team at the US DOE lab, National Energy Technology Laboratory (NETL). Recent interest in using solid oxide cells (SOCs) for hydrogen production has prompted the question as to whether the Butler-Vomer Model (BVM) empirically calibrated and used in DREAM-SOFC would be appropriate for simulation of reversible fuel cells as well. To this end we have simulated anode supported Ni/YSZ/LSCF button cells in reversible mode and found that the BVM is not capable of reproducing the trends observed in experiments performed at various applied steam, hydrogen and oxygen concentrations, even if some key parameters such as effective bulk diffusivity and exchange current density are treated as calibration parameters and adjusted freely. To bridge this gap, we modified the oxygen electrode model using a simplified version of the single pathway oxygen reduction reaction equations originally put forth by Svensson et al. [1]. In the simplified model, it is assumed that the adsorbed oxygen concentration remains close to its equilibrium value in most of the oxygen electrode active layer. This assumption eliminates the need to solve the more difficult, stiff surface coverage transport equation leaving only the oxygen ion vacancy concentration to be solved for, thus simplifying the model greatly. This paper presents the mathematical model, and an in-depth analysis of the results from this model applied to button cells with LSCF and LSM electrodes. Figure 1 shows the comparison between the simulated and experimental polarization curves. As shown, good agreement is achieved between simulations and experiments for fuel cell and electrolysis modes. We conclude that by extending the BVM only by adding the vacancy concentration transport equation, leads to a simple yet sufficient model with which one can perform very fast calibration and design analysis of reversible SOCs with minimal computation time.

Reference:

[1] A.M. Svensson, et al., J. Electrochem. Soc., 145(4), 1390 (1998) doi: 10.1149/1.1838471

Figure 1
3D Printing of Porous-Dense-Porous 8YSZ Supports for Solid Oxide Cells Applications
Authors: Lira Maritta , Kostretsova Natalia , Anelli Simone , Morata Alex , Torrell Marc , Tarancón Albert
Published: July 2021

The development of alternative sources for electric power generation and energy storage to meet the growing demand and ensuring environmental sustainability for the next decades is still being a challenge for the scientific community. In this context, fuel cells are of great interest in enabling sustainable generation of electricity, being highly efficient and being a reliable, efficient and safe technology during its operation. Fuel cells are electrochemical devices that directly convert chemical energy into electrical energy and heat by continuously feeding a fuel and an oxidant, and can also use surpluses of energy to reduce water to hydrogen as a chemical storage route when working on reverse mode. These devices are made up of two electrodes (fuel electrode and oxygen electrode) separated by an electrolyte.

It has been shown that the use of additive manufacturing (AM) technologies combined with ceramic fabrication techniques to optimize the microstructures and geometries of the SOC devices enhance its performance and reliability. New printable formulations for ceramic pastes have been developed for electrolytes in order to enhance the active area of reaction. Among different strategies to improve the performance, the use of composite electrodes base on porous scaffold of the ionic conductor phase to be infiltrated by the catalytic active phase is widely used. With the advance of the AM technology, 8YSZ electrolytes and scaffolds with different configurations can be also fabricated by 3D printing method.

In this present work, we aim to fabricate an innovative and complex structure for YSZ electrodes with dense and porous parts and optimize the fabrication parameters for different 3D-printing process to obtain enhanced features of the ceramic supports that will be applied for SOC. Focusing on optimize the 3D processing of combined porous and dense structures for SOFC/SOECs, dense (δ>95%) monolithic gas-tight YSZ thin electrolytes supported by porous scaffolds on both sides will be fabricated for later functionalization by infiltration of the electrodes. The fabrication of the porous dense porous electrolyte will be generated by: porosity integrated by the CAD design, generation of porosity by development of new ceramic pastes and tuning of the printing parameters.
Modeling and Techno-Economic Analysis of High Temperature Electrolysis Systems Using Protonic Ceramics
Authors: Thatte Amogh , Braun Rob J
Published: July 2021

High temperature water splitting (HTWS) via electrochemical processes are of growing interest due to their potential for achieving high thermodynamic efficiency. In particular, protonic ceramic electrolysis cells (PCECs) operating between 500°-600°C have the attractive feature that, in theory, pure dry hydrogen is produced at the hydrogen electrode (see Figure 1) and, unlike more conventional solid oxide electrochemical cells (SOECs) operating at 800°C, no further gas separation is needed. These features allow much simpler and elegant hydrogen production system concepts that have the potential to be significantly less costly and more efficient. For example, the dry H2 gas production at the fuel electrode allows for a much simpler balance-of-plant. The lower operating temperature also has numerous benefits, including lower plant heat losses, the ability to find more options for integrating various process heat sources by virtue of the lower grade heat requirements, and reduced capital cost due to a reduction in both gas process heat exchanger temperature and surface area requirements. A simple thermodynamic evaluation indicates that balance-of-plant steam generation specific energy (kJ/kg) requirements are some 17% lower when operating at 500°C versus 800°C.

The present work focuses on scale-up of advancing PCEC material sets developed by collaborating faculty at the Colorado School of Mines and an industrial partner, and their design/integration into MW-scale hydrogen production systems. Realizing high efficiency HTWS systems based on novel protonic ceramics requires understanding of numerous system-level considerations. One of our efforts is largely concerned with developing viable system designs that enable >75% system efficiency at centralized hydrogen production costs of < $2/kg (without compression, dispensing, and storage). This requires evaluation of plant operating conditions, especially in the PCEC stack periphery, where operating temperature, pressure, reactant utilization, sweep gas (if any) on the fuel electrode, thermal management, gas compression, and balance-of-plant integration all play critical roles in establishing cost effective, high performance HTWS systems. In this presentation, validated PCEC models using the latest large platform experimental cell data are used to explore optimal stack design parameter selection, such as cell voltage, reactant utilization, and reactant supply composition. System design implications from parameter sensitivity studies is summarized, and a comparative techno-economic analysis of PCEC-based hydrogen production systems with SOEC and PEMEC technologies is given.

Figure 1
Study on the Thermal-Electrical Balance of the kW-zclass SOFC Stack
Authors: Biao Li , Lyu Zewei , Han Minfang , Sun Kaihua , Sun Zaihong , Liu Yang
Published: July 2021

Solid oxide fuel cells (SOFC) can directly convert chemical energy into electrical energy with high power generation efficiency. However, the power generation process is always accompanied by the release of heat, and the balance of heat and electricity is important to the safe and stable operation of the SOFC stack. In this paper, a semi-empirical model of a kilowatt-level SOFC stack was established based on the experiment data that was operated in Xuzhou HuaTsing Jingkun Energy Co. Ltd. Based on this model, the effects of different operating temperatures, fuel and air flow rates, air-to-hydrogen ratio and other factors on the thermoelectric balance were analyzed with hydrogen fuel. In addition, methanol was also selected to study the thermo-electric balance performance. The results shows that the SOFC stack would meet the thermal balance on a special voltage, called self-heating balance voltage, but which varies under different conditions. With the increase of the fuel and air flow rates, the self-heating balance voltage and the limited voltage that shows the heat is surpass the power are decreases clearly. However, the self-heating balance voltage and the limited voltage changes differently under different air-to-hydrogen ratios. The air-to-hydrogen ratio enlarges from 2.4 to 3.6, the self-heating balance voltage and the limited voltage decreases by -4.14% and -2.42% by increasing air rates, however changes 1.26% and -3.07% by decreasing hydrogen rates, respectively.
Numerical Simulation of an Internal Reforming Solid Oxide Fuel Cell Unit Fueled with Hydrogen-Natural Gas Mixtures
Authors: Fan Junhua , Wang Yuqing , Shi Jixin , Shi Yixiang , Cao Haishan , Cai Ningsheng
Published: July 2021

Blending hydrogen into natural gas grid can effectively reduce carbon emissions and promote the development of the hydrogen economy. Utilizing hydrogen-natural gas mixtures through internal reforming solid oxide fuel cells (SOFCs) can convert the chemical energy of the fuels direct into electricity, which is a promising technology for combined heat and power systems. In this study, a three-dimensional model for an internal reforming solid oxide fuel cell unit is developed coupling chemical and electrochemical reactions, mass, momentum and heat transfer processes. The influences of the hydrogen addition on the distributions of temperature, gas compositions, and current density are studied by changing the hydrogen ratios in the inlet gas mixtures. The simulation results show that the addition of hydrogen affects the coupling of the endothermic reforming reactions and exothermic electrochemical reactions, which leads to improved temperature uniformity and lower fuel utilization of the SOFC unit compared with pure methane feeding. In order to further enhance the heat transfer between the exothermic and endothermic regions, a heat-pipe enhanced interconnect is introduced in the model. The introduction of the heat pipe is demonstrated to have the ability to decrease the temperature gradient and increase the electrochemical performance.
Flexible and Modular Fully Metallic Housing Concept for Solid Oxide Fuel Cells
Authors: Steinrücken Benjamin , Herrmann Stephan , Hauck Maximilian , Spliethoff Hartmut
Published: July 2021

The state-of-the-art alumina oxide housings used in single cell test rigs are fragile, inflexible and expensive. They are designed for a specific cell geometry, a change of the cell type - changing the cell thickness - or a change in the cell size is not intended and is thus associated with an immense expenditure of effort and time. In detail, the state-of-the-art ceramic frame concept is vulnerable to a fracturing of the frame or an insufficient contacting of the cell if a change in the cell thickness occurs. The connection of the ceramic housing with the typically metallic tubing of the gas supply is fragile, prone to develop leakages and is time consuming to replace and thereby prevents a change of the cell size. Gold wire seals used at the cathode side are a common source of leakage. Furthermore, the whole ceramic housing is sensitive to fracturing due thermal or load induced stress, and thus prevents fast thermal cycling of the specimen.

This paper presents a modular, fully metallic housing concept which enables a fast and easy change of the cell size due to the utilization of a baseplate and a robustness towards different cell thicknesses due to the usage of a flexible metallic frame. The utilization of metal instead of alumina oxide reduces the manufacturing costs. Furthermore, an additional sealing on the cathode side enables a separation of the contacting pressure via a pneumatic piston from the sealing pressure applied via metallic screws. The force of the sealing pressure is not applied onto the cell and is thereby limited by the material constraints and not by the mechanical stability of the cell. For accurate voltage measurements, sense wires are separated from the current collection and are electrically isolated from the metallic housing. Thermocouples are used to measure the temperature distribution inside the anodic part of the housing, as close as possible to the cell. The chromium evaporation of the cathode part of the housing is reduced by a protective coating and the utilization of double layered tubes. In the end, the results of preliminary tests are presented.
Design and 3D Printing of Controllable and Gradient Porous Supports for Solid Oxide Fuel Cells
Authors: Du Yanhai , Panthi Dhruba , Sahu Sulata , Feng Hai , Baker Patrick
Published: July 2021

A controllable and gradient porous structure is desirable for many applications including solid oxide fuel cells (SOFC) electrodes. A SOFC contains a minimum three basic ceramic thin films with a thin yet dense electrolyte layer separates the adjacent porous anode and cathode layers. In general, the thinner the electrolyte layer, the smaller the ohmic resistance would be. The anode and cathode layers need to be porous so to allow gases (e.g. H2 and O2) to easily penetrate to the triple-phase boundary (TPB). At the same time the anode and cathode layers serve as the paths of removing the electrons generated at the TPBs. Properly design and fabricated porous electrode microstructure could greatly increase the connectedness of gas, electrons and/or protons/oxygen ions, and therefore reduce the gas diffusion and ohmic resistances of the SOFC electrodes and boost the overall fuel cell performance.

Although there are electrolyte- and cathode- supported SOFC developers, the most used configuration is anode-supported or additional component-supported, for example metal-supported or ceramic-supported with a planar or tubular geometry. Conventionally, the porosity is generated by using sacrificial templates or pyrolyzable pore-formers for pore formation. Pores are formed after the burning off these sacrificial templates or pyrolyzable pore-formers at elevated temperatures. The size, shape and amount of the pore-formers can be controlled. However, the connectivity and orientation of these pores are not easily controllable, leaving significant amount of closed and isolated pores. These isolated and/or closed pores do not contribute to the TBP. Freeze casting of water-based suspension slurries could generate aligned pores, the low connectivity and weak mechanical strength challenges remain.

This paper focuses on the design and fabrication of a desired gradient porous microstructure for use as a SOFC support. The pore size and shape, porosity and connectivity could be determined and strictly controlled by design. Tubular and planar parts with metal, cermet and/or ceramic materials are to be fabricated. Additive manufacturing (AM, or 3D printing) process enables the fabrication of the complicated parts with the desired microstructure directly from the computer-aided design (CAD) models. The morphology, porosity, permeability and tortuosity of the 3D printed parts are investigated and results are discussed.
Progress of SOC Development at Elcogen
Authors: Noponen Matti , Torri Pauli , Göös Jukka , Puranen Jouni , Lehtinen Timo , Pylypko Sergii , Ounpuu Enn
Published: July 2021

Elcogen is one of the leading European manufacturers of solid oxide cell (SOC) technology. Elcogen products are unique combination of best in class performance and low-cost product structure. The unit cell and stack products are designed for low temperature operation enabling major cost reductions in the system level. Elcogen’s operations are located in the Nordic-Baltic technology cluster of Finland and Estonia. This article summarizes the recent activities and development trends of Elcogen.

Elcogen is currently focused in ramping up its unit cell and stack production with the increased customer needs. The short-term goal is to set-up of a demonstration manufacturing plant for the unit cells and stacks with annual capacity of 50 MW. To facilitate the goals Elcogen has signed EUR 12 million loan facility with The European Investment Bank (EIB). The loan is the first in the Baltic countries to get support under the InnovFin – EU-finance for innovators programme, which is financed from the EU’s Horizon 2020 research and innovation programme. Specifically, the financing falls under InnovFin’s Energy Demonstration Projects (EDP) facility.

Elcogen is continuously developing its products for higher performance, longer lifetime, lower costs, increased quality and expanded applications. As an example, Elcogen has been testing its stack efficiency and lifetime for methane-based gas applications. The maximum efficiency has exceeded 75 % efficiency. The degradation rate in 23 000 hours test has been 15 mOhm.cm2/1000h.
Development of Solid Oxide Electrolysis and Reversible Solid Oxide Cell and Stack Technologies at Nexceris, LLC
Authors: Dogdibegovic Emir , Arkenberg Gene , Kopechek David , Wallace Anila , Swartz Scott
Published: July 2021

Increasing demand for long-term energy storage, reduced carbon emissions, more resilient grid, and the lowest cost grid balancing solutions promotes solid oxide electrolysis cell (SOEC) and reversible solid oxide cell (RSOC) technologies. These systems can achieve high hydrogen production rates with near 100 percent stack electrical efficiency while co-electrolysis of carbon dioxide and water leads to production of syngas. RSOC can serve as a grid storage device (hydrogen production) and power production plant (provide electricity during peak demand). With over 25 years’ experience building and testing solid oxide cell materials, components and stacks, Nexceris has a proven track-record of commercializing products to major OEMs. The established manufacturing platforms at Nexceris enable smooth expansion into new applications.

In this talk, development of cells, stack components and stacks will be discussed. Performance and durability improvements from single cell to short stacks will be addressed. Cells with downselected electrode sets were implemented into short stacks with active cell area of 42 cm2 and 96 cm2. Stacks were operated continuously in SOEC mode at ~1.3 V for ≥ 500 hours with <5%/kh degradation and improving. The resulting short stack demonstrations show promising baseline performance and durability platform for future cell and stack development. RSOC tests were recently initiated with dynamic operation. Nexceris’ ChromLok coatings for bipolar plates were also integrated to stacks to enhance durability.
Progress in SOC Development at Fraunhofer IKTS
Authors: Kusnezoff Mihails , Jahn Matthias , Megel Stefan , Reichelt Erik , Trofimenko Nikolai , Herz Gregor , Beckert Weiland , Schilm Jochen , Rost Axel , Schoene Jakob , Wagner Doerte , Ganzer Gregor , Sauchuk Viktar , Nousch Laura , Hielscher Sebastian , Hartmann Mathias , Rothe Stefan , Michaelis Alexander
Published: July 2021

Despite long and successful development history of Solid Oxide Cells (SOC) continuous improvement in performance, longevity, manufacturing and system integration is necessary to bring this highly efficient technology to the market. The activities on material development and optimization at IKTS are focused mainly on enhancement of durability in SOFC, SOEC and rSOC operation and on boosting the power density for electrolysis operation. The recent results show considerable enhancement in cell longevity and power density.

The SOC priorities in applied research are moving from materials to industrialization and Fraunhofer as applied R&D service provider is following this trend. During recent years considerable efforts on simplification and automation of cell and stack manufacturing processes has been addressed at IKTS. The manufacturing processes for electrode manufacturing have been adjusted for high yield automated printing on thin electrolytes with integrated quality control measures. The efficient ways for reduction of time and energy consumption for sealing process of SOC stacks have been found and shown in pilot production as well as automated assembling of components to stacks demonstrated. Furthermore the stack integration into modules utilizing stacks of different providers has been addressed during last years and reliable solutions for building of compact stack modules of higher power (2 to 10 kW) has been developed and tested with industrial partners.

The increasing interest in “green hydrogen” generated multiple opportunities for SOEC technology to be considered as inherent part of industrial and chemical processes. IKTS pioneering work on coupled operation of SOEC module with Fischer-Tropsch reactor provided first demonstration of feasibility of this approach for waxes production. The process design and analysis of steel, using SOEC technology, has been performed and resulted in multiple demonstration activities in last four years. Recently novel approaches for ammonia production are addressed at IKTS showing opportunity for transportable chemicals/fuel production without need of CO2 source.

High power electrolysis applications (>10 MW) will need new approaches for stack design and put higher requirements on durability. High power electrolysis applications will also open a new window of opportunities for industrial SOFC power plants. This vision is considered as outline for our future research.
Solid Oxide Electrolyzer Development for Cost-Effective Hydrogen Production
Authors: Meinhardt Kerry D , Royer Nathanael , Seymour Lorraine , Coyle Christopher , Bonham Charles , Bao Jie , Karri Naveen , Canfield Nathan , Whyatt Greg , Holladay Jamie , Marina Olga A
Published: July 2021

A research and development program is under way at the Pacific Northwest National Laboratory to develop, fabricate and demonstrate operation of an efficient solid oxide electrolyzer stack capable of producing hydrogen from steam. The focus is on reducing the stack manufacturing costs that could be achieved via employing advanced fabrication techniques to reduce the cell area-specific resistances, component thicknesses, and material volumes. This presentation will provide an overview of the progress on cell development, cell size scale-up, cell electrochemical testing, long term durability assessment, and post-test characterization. The data obtained using both small and large size cells will be compared. 2D and 3D models are being constructed to predict expected thermal and electrical performance of SOEC stack.