bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of COVID-19 on paediatric cardiac centres in low-income and middle-income countries: a mixed-methods study
Authors: Dopke Campbell , Connor Jean , Zheleva Bistra , Gauvreau Kimberlee , Bakalcheva Bojana , Bina Najeebullah , Calvimontes Gonzalo , Cerovic Ivana , Majani Naizihijwa , Oketcho Michael , Pechilkov Dimitar , Shidhika Fenny , Shiryaev Tengiz , Jenkins Kathy
Published: November 2022

Objectives

The aim of this study was to understand the effects of the COVID-19 pandemic on paediatric cardiac services in critical access centres in low-income and middle-income countries.

Design

A mixed-methods approach was used.

Setting

Critical access sites that participate in the International Quality Improvement Collaborative (IQIC) for congenital heart disease (CHD) were identified.

Participants

Eight IQIC sites in low-income and middle-income countries agreed to participate.

Outcome measures

Differences in volume and casemix before and during the pandemic were identified, and semistructured interviews were conducted with programme representatives and analysed by two individuals using NVivo software. The qualitative component of this study contributed to a better understanding of the centres’ experiences and to identify themes that were common across centres.

Results

In aggregate, among the seven critical access sites that reported data in both 2019 and 2020, there was a 20% reduction in case volume, though the reduction varied among programmes. Qualitative analysis identified a universal impact for all programmes related to Access to Care/Clinical Services, Financial Stability and Professional/Personal Issues for healthcare providers.

Conclusions

Our study identified and quantified a significant impact of the COVID-19 pandemic on critical access to CHD surgery in low-income and middle-income countries, as well as a significant adverse impact on both the skilled workforce needed to treat CHD and on the institutions in which care is delivered. These findings suggest that the COVID-19 pandemic has been a major threat to access to care for children with CHD in resource-constrained environments and that this effect may be long-lasting beyond the global emergency. Efforts are needed to preserve vulnerable CHD programmes even during unprecedented pandemic situations.
Analysis of antibiotic use patterns in Danish hospitals 2015–2021 using an adapted version of the who aware classification
Authors: Anhøj Jacob , Boel Jonas , Olesen Birthe Riis , Bak Helle Boelsmand , Hellesøe Anne-Marie Blok , Thomsen Kim , Knudsen Jenny Dahl
Published: November 2022

Background

AWaRe is a tool to categorise and guide antibiotic use. Antibiotics are classified in three groups: Access, Watch and Reserve. The Access group contains first choice antibiotics for 25 of the most common infections. Antibiotics in the Watch and Reserve groups should be restricted to cases that cannot be effectively treated with drugs from the Access group.

Objectives

The primary aim of this study was to evaluate and adapt the WHO 2019 AWaRe classification for use with antibiotic usage data in Danish hospitals. The secondary aim was to study the usefulness of the abxaware; software package for visualisation and analysis of temporal trends in antibiotic use patterns.

Methods

We obtained data on purchases of antibiotics in Danish hospitals from January 2015 to July 2021. Sixty-seven unique drugs had been purchased. To better correspond with Danish guidelines, we moved two drugs one AWaRe level upwards. To help aggregate antibiotics according to AWaRe and visualise use patterns, we developed an R package, abxaware.

Results

After adding two drugs that were not included in the original AWaRe classification nearly all antibiotics (>99%) used in Danish hospitals were covered. The abxaware software package for R is a useful tool to help aggregate, visualise and analyse antibiotic use patterns.

Conclusions

With minor modifications, we adapted the AWaRe classification to cover most antibiotics used in Danish hospitals and to reflect Danish treatment guidelines. The abxaware package is a useful tool to aggregate and plot antibiotic usage data according to the AWaRe classification and to test for non-random variation in the percentage use of Access antibiotics.
Targeting the CD47/thrombospondin-1 signaling axis regulates immune cell bioenergetics in the tumor microenvironment to potentiate antitumor immune response
Authors: Stirling Elizabeth R , Terabe Masaki , Wilson Adam S , Kooshki Mitra , Yamaleyeva Liliya M , Alexander-Miller Martha A , Zhang Wei , Miller Lance D , Triozzi Pierre L , Soto-Pantoja David R
Published: November 2022

Background

CD47 is an integral membrane protein that alters adaptive immunosurveillance when bound to the matricellular glycoprotein thrombospondin-1 (TSP1). We examined the impact of the CD47/TSP1 signaling axis on melanoma patient response to anti-PD-1 therapy due to alterations in T cell activation, proliferation, effector function, and bioenergetics.

Methods

A syngeneic B16 mouse melanoma model was performed to determine if targeting CD47 as monotherapy or in combination with anti-PD-1 impacted tumor burden. Cytotoxic (CD8+) T cells from Pmel-1 transgenic mice were used for T cell activation, cytotoxic T lymphocyte, and cellular bioenergetic assays. Single-cell RNA-sequencing, ELISA, and flow cytometry was performed on peripheral blood mononuclear cells and plasma of melanoma patients receiving anti-PD-1 therapy to examine CD47/TSP1 expression.

Results

Human malignant melanoma tissue had increased CD47 and TSP1 expression within the tumor microenvironment compared with benign tissue. Due to the negative implications CD47/TSP1 can have on antitumor immune responses, we targeted CD47 in a melanoma model and observed a decrease in tumor burden due to increased tumor oxygen saturation and granzyme B secreting CD8+ T cells compared with wild-type tumors. Additionally, Pmel-1 CD8+ T cells exposed to TSP1 had reduced activation, proliferation, and effector function against B16 melanoma cells. Targeting CD47 allowed CD8+ T cells to overcome this TSP1 interaction to sustain these functions. TSP1 exposed CD8+ T cells have a decreased rate of glycolysis; however, targeting CD47 restored glycolysis when CD8+ T cells were exposed to TSP1, suggesting CD47 mediated metabolic reprogramming of T cells. Additionally, non-responding patients to anti-PD-1 therapy had increased T cells expressing CD47 and circulating levels of TSP1 compared with responding patients. Since CD47/TSP1 signaling axis negatively impacts CD8+ T cells and non-responding patients to anti-PD-1 therapy have increased CD47/TSP1 expression, we targeted CD47 in combination with anti-PD-1 in a melanoma model. Targeting CD47 in combination with anti-PD-1 treatment further decreased tumor burden compared with monotherapy and control.

Conclusion

CD47/TSP1 expression could serve as a marker to predict patient response to immune checkpoint blockade treatment, and targeting this pathway may preserve T cell activation, proliferation, effector function, and bioenergetics to reduce tumor burden as a monotherapy or in combination with anti-PD-1.
Effects of admission systemic inflammatory indicators on clinical outcomes in patients with vertebrobasilar artery occlusion: insight from the PERSIST registry
Authors: Zhang Pan , Xu Pengfei , Duan Zuowei , Zhang Feng , Fang Yirong , Yan Dingyi , Zhang Hanhong , Cai Qiankun , Huang Xianjun , Huang Zhixin , Gu Mengmeng , Xiao Lulu , Wang Jinjing , Sun Wen
Published: November 2022

Background

Few studies have focused on the effect of systemic inflammation in vertebrobasilar artery occlusion (VBAO). The aim of this study was to investigate the relationship between inflammatory indicators and the prognosis of VBAO patients receiving endovascular treatment (EVT).

Method

Patients with VBAO who were treated with EVT within 24 hours of the estimated occlusion time were included in this study. Multivariate logistic regression and elastic net regularization were performed to analyze the effects of inflammatory indicators on the prognosis of patients with VBAO. The primary outcome was unfavorable outcome (a modified Rankin Scale score of 4–6) at 90 days. Secondary outcomes included symptomatic intracranial hemorrhage, in-hospital mortality, 90 day mortality, 1 year unfavorable outcome, and mortality.

Results

560 patients were included in the study. Multivariate analysis showed that white blood cells (W), neutrophils (N), neutrophil to lymphocyte ratio (NLR), platelet to neutrophil ratio, platelet to white blood cell ratio, and NLR to platelet ratio were associated with the primary outcome. Elastic net regularization indicated that W, N, and NLR were the major inflammatory predictors of unfavorable outcome at 90 days. For long term prognosis, we found that the inflammatory indicators that predicted 1 year outcomes were consistent with those that predicted 90 day outcomes.

Conclusion

Inflammatory indicators, especially W, N, and NLR, were associated with moderate and long term prognosis of patients with VBAO treated with EVT.
Application of deep learning models for detection of subdural hematoma: a systematic review and meta-analysis
Authors: Abdollahifard Saeed , Farrokhi Amirmohammad , Mowla Ashkan
Published: November 2022

Background

This study aimed to investigate the application of deep learning (DL) models for the detection of subdural hematoma (SDH).

Methods

We conducted a comprehensive search using relevant keywords. Articles extracted were original studies in which sensitivity and/or specificity were reported. Two different approaches of frequentist and Bayesian inference were applied. For quality and risk of bias assessment we used Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2).

Results

We analyzed 22 articles that included 1,997,749 patients. In the first step, the frequentist method showed a pooled sensitivity of 88.8% (95% confidence interval (CI): 83.9% to 92.4%) and a specificity of 97.2% (95% CI 94.6% to 98.6%). In the second step, using Bayesian methods including 11 studies that reported sensitivity and specificity, a sensitivity rate of 86.8% (95% CI: 77.6% to 92.9%) at a specificity level of 86.9% (95% CI: 60.9% to 97.2%) was achieved. The risk of bias assessment was not remarkable using QUADAS-2.

Conclusion

DL models might be an appropriate tool for detecting SDHs with a reasonably high sensitivity and specificity.
Angioinvasive aspergillosis mimicking giant cell arteritis in an 81-year-old man with jaw pain and vision loss
Authors: Guemara Romain , Pieren Amara , Brulhart Laure
Published: November 2022

The present case report focuses on an immunocompromised 81-year-old patient initially diagnosed with Waldenström’s disease. The patient experienced a gradual vision loss and jaw pain with high erythrocyte sedimentation rate. We first suspected giant cell arteritis, despite inconclusive assessment, including a negative temporal artery biopsy. We rapidly started a corticosteroid pulse therapy followed by high-dose corticosteroid therapy that was followed even after discharge from the hospital. The patient was readmitted 20 days later with severe left retro-orbital pain and progressive left vision loss. Clinical examination revealed complete left eyelid ptosis and unilateral blindness with fixed mydriasis and no eye movement. MRI showed signs of ischaemic optic neuropathy with lysis of the left ethmoid sinus wall; thus, indicating ischaemic optic neuropathy related to lymphoplasmacytic infiltration of Waldenström’s disease (Bing-Neel syndrome). Oncological treatment of ibrutinib, a tyrosine kinase inhibitor, was then administered. Despite a favourable prognosis, no improvement was seen. An infectious aetiology was finally confirmed. The left sphenoid sinus biopsy highlighted an angioinvasive aspergillosis with rhino-orbital infiltration observed as ischaemic optic neuropathy. Oncologic treatment was discontinued and antifungal therapy with voriconazole was introduced, leading to a favourable radiological development and analgesic control, without ophtalmological improvement.
Balanced-by-Construction Regular and ω-Regular Languages
Authors: Edixhoven Luc , Jongmans Sung-Shik
Published: November 2022

Parenn is the typical generalization of the Dyck language to multiple types of parentheses. We generalize its notion of balancedness to allow parentheses of different types to freely commute. We show that balanced regular and [Formula: see text]-regular languages can be characterized by syntactic constraints on regular and [Formula: see text]-regular expressions and, using the shuffle on trajectories operator, we define grammars for balanced-by-construction expressions with which one can express every balanced regular and [Formula: see text]-regular language.
Enhanced CRNN-Based Optimal Web Page Classification and Improved Tunicate Swarm Algorithm-Based Re-Ranking
Authors: Yasin Syed Ahmed , Prasada Rao P. V. R. D.
Published: November 2022

The main intention of this paper is to develop a new intelligent framework for web page classification and re-ranking. The two main phases of the proposed model are (a) classification, and (b) re-ranking-based retrieval. In the classification phase, pre-processing is initially performed, which follows the steps like HTML (Hyper Text Markup Language) tag removal, punctuation marks removal, stop words removal, and stemming. After pre-processing, word to vector formation is done and then, feature extraction is performed by Principle Component Analysis (PCA). From this, optimal feature selection is accomplished, which is the important process for the accurate classification of web pages. Web pages contain several features, which reduces the classification accuracy. Here, the adoption of a new meta-heuristic algorithm termed Opposition based-Tunicate Swarm Algorithm (O-TSA) is employed to perform the optimal feature selection. Finally, the selected features are subjected to the Enhanced Convolutional-Recurrent Neural Network (E-CRNN) for accurate web page classification with enhancement based on O-TSA. The outcome of this phase is the categorization of different web page classes. In the second phase, the re-ranking is involved utilizing the O-TSA, which derives the objective function based on similarity function (correlation) for URL matching, which results in optimal re-ranking of web pages for retrieval. Thus, the proposed method yields better classification and re-ranking performance and reduce space requirements and search time in the web documents compared with the existing methods.
ACM UMAP 2022 report
Authors: Bellogin Alejandro , Boratto Ludovico , Santos Olga C. , Ardissono Liliana , Knijnenburg Bart
Published: November 2022

ACM UMAP is the premier international conference for researchers and practitioners working on systems that adapt to individual users, to groups of users, and that collect, represent, and model user information. For the first time in the history of the conference, UMAP 2022 ran in a hybrid mode, with the opportunity for speakers and attendees to participate onsite or online. Besides, in this edition, we celebrated the 30th anniversary of UMAP, which started as a workshop on User Modeling in 1986. In this report we comment on the conference organization and attendees' experience.
33rd ACM conference on hypertext and social media
Authors: Bellogin Alejandro , Boratto Ludovico , Cena Federica
Published: November 2022

The ACM Hypertext conference is a premium venue for peer-reviewed research on hypertext theory, systems, and applications. It is concerned with all aspects of modern hypertext research including social media, semantic web, dynamic and computed hypertext and hypermedia as well as narrative systems and applications.

Hypertext 2022 was held in Barcelona, Spain, between June 28th and July 1st, co-located with ACM WebSci and ACM UMAP. Due to the global pandemic, this edition was the first hybrid one in this conference history, embracing both online and onsite attendees. This newsletter article briefly summarizes how the conference went and its major challenges.
Conceptualising the authorial burden
Authors: Jones Joey Donald
Published: November 2022

Authoring Interactive Digital Narratives creates a burden of content creation due to their structure. This is referred to as the authorial burden. This article presents a framework for understanding the authorial burden, and it presents a taxonomy of different strategies that seek to overcome this burden.
Upcoming SIGWEB supported conferences
Authors: Roßner Daniel
Published: November 2022

The Special Interest Group on Hypertext and the Web, SIGWEB was created in 1989 to support the community participating in the annual ACM Hypertext Conference. In its fourth decade, SIGWEB continues its efforts to support a wide range of communities and eight annual conferences. SIGWEB supports several specialized conferences, short courses, and workshops of different sizes, as well as the annual Hypertext Conference. SIGWEB sponsored conferences focus on timely topics in applied and computational hypertext and Web disciplines and provide a place for members and the entire applied Hypermedia and Web community to exchange ideas and to meet with and expand their network of colleagues. In this article, we provide a brief overview of SIGWEB sponsored conferences, in addition to events that are in cooperation with SIGWEB.
An Algorithmic Meta-Theorem for Graph Modification to Planarity and FOL
Authors: Fomin Fedor V. , Golovach Petr A. , Stamoulis Giannos , Thilikos Dimitrios M.
Published: November 2022

In general, a
graph modification problem
is defined by a graph modification operation ⊠ and a target graph property 𝒫. Typically, the modification operation ⊠ may be
vertex deletion
,
edge deletion
,
edge contraction
, or
edge addition
and the question is, given a graph
G
and an integer
k
, whether it is possible to transform
G
to a graph in 𝒫 after applying the operation ⊠
k
times on
G
. This problem has been extensively studied for particular instantiations of ⊠ and 𝒫. In this article, we consider the general property 𝒫
𝛗
of being planar and, additionally, being a model of some First-Order Logic (FOL) sentence 𝛗 (an FOL-sentence). We call the corresponding meta-problem
Graph ⊠-Modification to Planarity and 𝛗
and prove the following algorithmic meta-theorem: there exists a function
f
: ℕ
2
→ ℕ such that, for every ⊠ and every FOL-sentence 𝛗, the
Graph ⊠-Modification to Planarity and 𝛗
is solvable in
f
(
k,|𝛗|
)⋅
n
2
time. The proof constitutes a hybrid of two different classic techniques in graph algorithms. The first is the
irrelevant vertex technique
that is typically used in the context of Graph Minors and deals with properties such as planarity or surface-embeddability (that are
not
FOL-expressible) and the second is the use of
Gaifman’s locality theorem
that is the theoretical base for the meta-algorithmic study of FOL-expressible problems.
More Recent Advances in (Hyper)Graph Partitioning
Authors: Çatalyürek Ümit , Devine Karen , Faraj Marcelo , Gottesbüren Lars , Heuer Tobias , Meyerhenke Henning , Sanders Peter , Schlag Sebastian , Schulz Christian , Seemaier Daniel , Wagner Dorothea
Published: November 2022

In recent years, significant advances have been made in the design and evaluation of balanced (hyper)graph partitioning algorithms. We survey trends of the past decade in practical algorithms for balanced (hyper)graph partitioning together with future research directions. Our work serves as an update to a previous survey on the topic [
29
]. In particular, the survey extends the previous survey by also covering hypergraph partitioning and has an additional focus on parallel algorithms.
Graphene/Waterborne Epoxy Coatings with Dual Functionalities of Barrier and Corrosion Inhibitor
Authors: Liu Suyun , Wang Xian-Zong , Luo Jing-Li
Published: November 2022

A facile and environmentally-friendly method is developed to prepare graphene/waterborne epoxy (WEP) composite coatings. The graphene nanosheets are produced with electrochemical-exfoliation in the solution containing surfactants, cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). The nanosheets containing solution thus formed is subjected to a quick dialysis and then directly used as a diluent for WEP without any further treatment. This preparation method overcomes the commonly identified problems of aggregations and ‘corrosion promotion’ effect associated with graphene, and increases the impedance of the composite coatings by more than two orders of magnitude. The analysis of anticorrosion performance suggested that the presence of surfactants not only improves the dispersibility of graphene nanosheets but also endows the composite coatings with both barrier and corrosion inhibition capabilities. The strategy reported herein may pave the path to the large-scale production of the graphene anticorrosion coatings.

Figure 1
Silk-Cellulose Nanocrystal Composite Coatings for Enhanced Corrosion Protection and Cytocompatibility
Authors: Asadi Hamid , Ramasamy Ramaraja
Published: November 2022

The clinical application of magnesium (Mg)-based alloys as biodegradable orthopedic implants is highly restricted because of their rapid corrosion rate in the physiological environment [1]. Polymeric coatings have been recognized as one of the most effective methods to tailor the corrosion rate of Mg alloys without changing their bulk properties, while providing them with other functionalities such as enhanced biocompatibility [2]. In this study, a composite polymeric coating based on silk fibroin (SF) and cellulose nanocrystal (CNC) was fabricated on AZ31 Mg alloy to enhance its corrosion resistance and cytocompatibility for biodegradable bone implant application. The coating was prepared by drop-cast method on AZ31 Mg alloy and fully characterized by various physiochemical techniques. The corrosion resistance of the coating and the effect of CNC inclusion on the corrosion protection performance of the coating were investigated through extensive electrochemical techniques (open circuit potential, polarization test, and electrochemical impedance spectroscopy) as well as in vitro immersion tests. In addition, the cytocompatibility of the coating in terms of cellular toxicity and adhesion was assessed toward human fetal osteoblast cells. SEM images revealed the formation of a defect-free and uniform SF-CNC coating with a thickness of 11.2 ± 2.5 µm on AZ31 alloy. The results of the electrochemical corrosion and in vitro immersion tests clearly demonstrated an enhanced corrosion resistance of the SF coating after the incorporation of CNCs. Compared to the unmodified Mg alloy, the SF-CNC coated AZ31 exhibited a remarkably improved cytocompatibility with a viability of 114% and excellent adhesion and spreading of human fetal osteoblast cells onto the coating surface. The findings of this work highlight the great potential of SF and CNC as bio-based nature-derived anticorrosive nanofillers for fabrication of protective and biocompatible coatings on Mg-based biodegradable orthopedic implants.

References:

[1] Wang, Jia‐Li, et al. "Biodegradable magnesium‐based implants in orthopedics—a general review and perspectives." Advanced science 7.8 (2020): 1902443.

[2] Asadi, Hamid, et al. "A multifunctional polymeric coating incorporating lawsone with corrosion resistance and antibacterial activity for biomedical Mg alloys." Progress in Organic Coatings 153 (2021): 106157.
Evaluation of Microbiologically Induced Corrosion in the Presence of Streptococcus Mutans
Authors: Duncan Austin , Suganthan Baviththira , Asadi Hamid , Zolti Or , Ramasamy Ramaraja
Published: November 2022

Titanium and titanium alloys are used in biomedical implants such as dental screws due to their excellent mechanical strength and high resistance to corrosion. The corrosion resistance of these alloys is largely due to the formation of a passive oxide layer on the titanium surface when in contact with oxygen. For the application of use in dental implants, titanium’s ability to withstand corrosion in the presence of oral bacteria is of utmost importance, specifically in the presence of Streptococcus mutans, the most common plaque causing oral bacteria. Previous literature has explored the effects of the formation of a S. mutans biofilm on the corrosion resistance of commercially pure titanium [1]. A decrease in corrosion resistance is observed following the formation of the biofilm, however this decrease in corrosion resistance does not invalidate the viability of titanium for use in orthodontic systems. Due to the electrochemical and material similarities between titanium and zirconium, including the formation of a passive oxide layer on the zirconium surface and high material strength, there is evidence to suggest zirconium and zirconium alloys may be a viable alternative to titanium for these applications [2]. Previous literature has explored the use of titanium-zirconium alloys in such applications and found no decrease in their ability to withstand colonization and microbiologically induced corrosion in the presence of Streptococci species relative to commercially available titanium [3]. The aim of this current research is to begin the exploration of the feasibility of zirconium based materials in orthodontic applications by investigating the microbiologically induced corrosion of commercially pure zirconium and a zirconium-niobium alloy in the presence of S. mutans and compare them against commercially pure titanium.

References:

[1] Souza, Júlio C.M., et al. “Corrosion Behaviour of Titanium in the Presence of Streptococcus Mutans.” Journal of Dentistry, vol. 41, no. 6, 2013, pp. 528–534., https://doi.org/10.1016/j.jdent.2013.03.008.

[2] Renganathan, Gunarajulu, et al. “Orthopedical and Biomedical Applications of Titanium and Zirconium Metals.” Fundamental Biomaterials: Metals, 2018, pp. 211–241., https://doi.org/10.1016/b978-0-08-102205-4.00010-6.

[3] Siddiqui, Danyal A., et al. “Evaluation of Oral Microbial Corrosion on the Surface Degradation of Dental Implant Materials.” Journal of Periodontology, vol. 90, no. 1, 2018, pp. 72–81., https://doi.org/10.1002/jper.18-0110.
(Digital Presentation) Corrosion-Resistance Investigation of Titanium Passive Layer in Acidic Solution
Authors: Fung Kuan-Zong , Tsai Shu-Yi , Li Zih-Jhun
Published: November 2022

Titanium metal is known to have good corrosion resistance. For the plating of Cu in many industrial applications, Ti metal is commonly used as the cathode for the reduction of Cu. Under an acidic and high temperature environment, the passivation layer on the surface of the titanium metal tends to react with acidic solution. As a result, the corrosion of the active titanium metal was observed. In this study, the corrosion behavior of commercial pure titanium in acid copper sulfate baths was investigated, and several surface treatments were used to improve the corrosion resistance of titanium passive layer. The microstructure of titanium metal after immersion in acid copper sulfate solution was examined by using SEM and FIB. The pitting corrosion of Ti was clearly observed using SEM. The corrosion mechanism of the titanium metal in the sulfuric acid solution was discussed. In addition, the electrochemical characteristics of commercial pure titanium metal in sulfuric acid solution were also analyzed using the three-pole potential measurement method.
(Digital Presentation) Progress Towards the Key Factors Governing Pit Stability
Authors: Wang Ke , Salasi Mobin , Iannuzzi Mariano
Published: November 2022

The pit stability product—defined as the product of pit depth and dissolution current density (x·i)—was first introduced by Galvele as the criterion indicating the conditions that sustain a critically acidic solution within the pit. The one-dimensional (1D) electrode is the most commonly used experimental configuration for determining the pit solution chemistry and pit stability product. In our current works, a ‘sandwich’ like 1D pit electrode was developed, which enabled the in-situ and ex-situ visualization of pit depth. A methodology that avoids lacy cover formation was proposed to pre-dissolve a Type 316L stainless steel (SS) 1D electrode to specific depths. Based on the new methodology and mathematical models, it was found that 1D Fick’s law of diffusion could not be used to estimate the pit stability product under a salt film because electro-migration had a measurable contribution (i.e., 67%) to the dissolution current. Although the diffusion coefficient of metal cations decreased with an increasing concentration inside the pit, it could be replaced by a constant diffusion coefficient to estimate the pit stability product, defined as an equivalent diffusion coefficient in our work. Later, a more comprehensive mathematical model, which included hydrolysis reactions and activity, was built to predict the local chemistry within the pit cavity. Recently, a galvanostatic method was developed to estimate the critical pit stability product of Type 316L SS, which was between 0.8 and 0.9 A/m in 0.6 M NaCl at 25°C, findings that were also confirmed by mass transport modelling. Here, we will present the proposed improved theoretical framework and discuss the next steps in modelling the propagation of pits in stainless steels.
Passive Film Structure and Corrosion Initiation in Al Alloys with Far-from-Equilibrium Compositions and Microstructures
Authors: Christudasjustus Jijo , Darwish Ahmed A , Witharamage Chathuranga S , Gupta Rajeev Kumar , Terryn Herman Albert
Published: November 2022

Al alloys with far-from-equilibrium compositions and microstructures are reported to possess high corrosion resistance and strength. These alloys produced are by non-equilibrium processing techniques such as high-energy ball milling, sputtering, and ion implantation. Depending on the processing techniques and conditions, the microstructure of the alloys could be heterogeneous. For example, alloys produced by high-energy ball milling and subsequent consolidation comprise a matrix with high solid solubility of the solute and uniformly distributed secondary phases. Such a heterogeneous microstructure is expected to influence the passive film composition and localized corrosion mechanisms. In the present study, passive film composition on the ball-milled alloys was studied using a combination of scanning transmission electron microscope, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry (SIMS). Additionally, pits and regions near pits were investigated which helped in understanding factors causing pit initiation and repassivation.
Ultimate Localization
Authors: Schmuki Patrik
Published: November 2022

We report approaches to grow directly noble-metal-(NM)-decorated nanotubes by self-organized anodization. Key to obtain highly defined tubes is an optimized and controlled anodization of Ti-Pt (or other NM) alloys in fluoride containing solutions. In general, the morphology of porous TiO2 and of the tubular layers is affected strongly by the electrochemical growth parameters. NM-decorated titanium-dioxide is a highly functional material that has numerous interesting properties, for example, in solar energy conversion, catalysis of the decomposition of organic compounds (self-cleaning). Therefore this simple approach to produce this highly defined nanoscopic form of NM-TiO2 bears a high potential for technological exploitation. Over the years numerous efforts have been devoted to the shrinkage of the NM-particles to enhance the usage of the noble metal. Evidently the most extreme case of shrinkage is the use of an isolated single atoms of Pt. The use of single atoms as a co-catalyst in photocatalysis has in recent years attracted strong interest, not only because the single atom state represents a maximized surface to volume efficiency, but also because single atom reactivity allows for unprecedented reaction pathways.

In the presentation we discuss the formation of Pt dispersed and anchored as single atoms on TiO2 nanotubes and the use of such tubes in highly effective photocatalysis.
Effect of Interstitial Oxygen in Stainless Steel 316L Formed Via Laser Powder Bed Fusion on Corrosion Properties
Authors: Guo Xiaolei , Huang Hsien-Lien , Zhu Menglin , Hariharan Karthikeyan , Chien Szu-Chia , Huynh Ngan , Hwang Jinwoo , Windl Wolfgang , Taylor Christopher , Schindelholz Eric John , Frankel Gerald S.
Published: November 2022

Laser powder bed fusion (PBF) has been used to create structures of many different alloys including stainless steels (SS). In contrast to SS prepared via conventional approaches, PBF-produced SS often contains a high concentration of oxygen. It is generally believed that the oxygen primarily exists as oxide inclusions with diameters ranging from tens of nanometers to several microns. Thermodynamic calculations also show that the solubility of the oxygen is extremely low in the liquid, face center cubic (FCC), or body center cubic phases that are relevant to the composition of the SS investigated in this study. Additionally, these calculations predict that majority of oxygen stays in the metastable MnSiO3 phase. In this study, we perform multi-scale, quantitative electron microscopic analysis on the as-printed SS 316L and find that a large amount of oxygen actually exists in the interstitial sites of the alloy lattice, suggesting that oxygen might have been trapped in the alloy substrate during the rapid cooling process of PBF. The observations from the atomic-scale-resolution characterization are supported by the first principles simulations through density functional theory calculations, which reveal that oxygen can stay energetically stable in the octahedral site of the FCC structure. Additionally, these interstitial oxygen atoms can form ionic bonds with the neighboring metal atoms, with a particularly high affinity towards Cr atoms. The presence of interstitial oxygen in the SS substrate appears to assist the surface passivation processes and lead to the exceptionally high pitting potential. The identification of a large amount of interstitial oxygen in the alloy may have a profound impact on the design of strong, tough, and corrosion resistant alloys.
Pitting Propagation Behavior on Low Alloy AISI 4130 (UNS G41300) Steel Exposed to Various Alkaline Earth Metal Chlorides Using the 1-D Pit Method
Authors: Demarest Charles , Scully John R. , Asmussen Matthew
Published: November 2022

This study examined pit propagation to elucidate whether alkali and alkaline earth metal chloride saltssuch as RbCl affect pitting behavior in distinctly different manner than NaCl. Pit propagation studies were conducted on a low alloy steel using one-dimensional (1-D) pit method over pit depths from 300-1000 µm. LSV and EIS of planar electrodes of 4130 in a range of Cl- solutions were conducted and revealed no differences in impedance, open circuit, corrosion potential (Ecorr), passive current density (ipass), and pitting potential (Epit) as a function of salt type. In the case of one-dimensional pits during fast downward scan rates, the saturation potential (Esat) varied as a function of salt type and pit depth when pits were shallow. Mass transported limited current density also differed with salt type in shallow pits when other alkali metal and alkaline metal cations where present. The pit surface potential (Esurf) of activated pit surfaces reached Ecorrprior to establishing a condition where the pit electrolyte surface concentration (Csurf) was less than the critical concentration for active acidified pitting (Csurf<Ccrit) in this marginally passivating steel. For various Esurf and pit current density (ipit) combinations at constant Csurf where Ccrit< Csurf < Csat, E-log(i) plots were constructed using the method of Li, Tianshu to create IR ohmic voltage corrected Tafel plots at fixed pit solution concentrations. Under these conditions, the influence of salt identity on charge transfer controlled kinetics was reexamined and slight differences in Tafel behavior were found. Differences in metal cations exert no effect on passive planar electrodes and only effect pit propagation stage in shallow pits.
(Digital Presentation) Intercalated Layered TaSi2N4 Electrodes of Zn–Air Battery
Authors: Ponnada Sreekanth , Saini Bhagirath , Singhal Rahul , Sharma Rakesh K
Published: November 2022

Metal–air batteries have attracted significant attention due to their excellent advantage of high-energy-density metal anodes with air cathodes. The development of structurally stable materials has been a great challenge for Zn-air batteries. Layered 2D materials provide unique opportunities due to their facial synthesis and structural stability. In this presentation, we demonstrate intercalated architecture TaSi2N4 layered material for cathode and anode of Zn–air batteries. The mechanistic aspects of Zn storage will be shown. These van der Waals materials undergo a phase during Zn loading. Interestingly, TaSi2N4 surface shows the two-electron mechanism of oxygen reduction. These layered materials will create new possibilities for the development of unique electrodes of Zn–air batteries.
(Invited) Overview of the Ordering Phenomena in Li and Na Layered Oxide Electrode Materials
Authors: Delmas Claude , Guignard Marie , Weill Francois
Published: November 2022

AX(M)O2 layered oxides (A = Li, Na) are considered as the best positive electrode materials either for Li ion and Na ion batteries. In most of the systems, the shape of the voltage curve shows change in slope of the curve which indicate the occurrence of structural transitions due to: (i) electronic configuration modification in the MO2 slab, (ii) change in the slab packing, (iii) alkali ion-vacancy ordering. Moreover, in AX(M,L)O2 materials a M/L ordering can occur within the (M,L)O2 slab for the pristine material.

Lithium and sodium tends to be ordered in the deintercalated materials for peculiar compositions. Nevertheless, due to the larger ionic radii of Na+ vs Li+, the repulsive interaction between sodium ions are stronger for sodium, leading to many Na+/vacancy patterns in the interslab space.

Moreover, transition element orderings can occur within the (L,M)O2 slab if the difference in size is significant and if the cation ratio corresponds to a specific composition (1/3, ½, 2/3...). Then an interesting behaviour is observed as the sodium/vacancy ordering in the interslab space can be st superimposed to the cation ordering.

Another original situation is also observed for cations (d2 or d3) which like to form M-M bonds. In this case, the pattering of short bond and long bond in the MO2 slab is directly related to the Na+/vacancy distribution and to the M3+/M4+ ratio.
(Charles W. Tobias Award) Advancing Porous Electrodes for Electrochemical Systems
Authors: Brushett Fikile R.
Published: November 2022

Electrochemical processes are poised to play a pivotal role in the evolving global power system as the efficient interconversion of electrical and chemical energy can enable the deployment of sustainable technologies that support the decarbonization of the electric grid, power the automotive fleet, and offer new opportunities in chemical manufacturing. However, advances in electrochemical science and engineering are needed to address the stringent performance, cost, and scale requirements of these emerging application spaces. Many prominent electrochemical technologies (e.g., flow batteries, fuel cells, electrolyzers) leverage forced convection to increase volumetric productivity. Of particular importance to these systems are porous electrodes which provide surfaces for electrochemical reactions, manage reactant distribution, facilitate mechanical compression, and conduct electrons and heat. Accordingly, the systematic design and engineering of porous electrodes can greatly improve cell performance and durability.

In this presentation, I will describe methods for disaggregating and quantifying resistive losses in porous electrodes using redox probes, diagnostic flow cells, and electrochemical modeling. I will then discuss how these tools can be used to guide the design of new electrode architectures with tailored property sets. Specifically, using redox flow batteries as an example, I will offer three vignettes. First, I will discuss the role of electrode microstructure and surface chemistry in balancing electrochemical and fluid dynamic performance within flow cells. Second, building on these results, I will describe efforts to develop electrodes using non-solvent induced phase separation, a synthetic approach which enables property combinations difficult to achieve via current manufacturing processes. Third and finally, I will highlight the potential of conductive particle suspensions as flowable, reconfigurable electrodes whose unusual electrochemical, rheological, and transport properties may unlock more versatile reactor designs.
(Europe Section Alessandro Volta Award) From the Oil Barrel to Reactive Metals: An Approach to the Energy Transition
Authors: Passerini Stefano
Published: November 2022

Our society is facing a millennial challenge to slow down global warming below 2 °C in the long term.[1] Ambitious policy frameworks and policy intentions are a must to achieve this target. In fact, analyzing the status quo, International Energy Agency (IEA) concluded that the related carbon dioxide tra- jectories are not compatible with the climate targets, even if current policy commitments and pledges by governments are implemented.[2,3] The challenging issues are the limited use of renewables, merely considered for power generation, but only marginally addressing other carbon-intensive industrial sectors (e.g., cement, steel, smelting), and the practical reduction of CO2 emissions from the transport sector.

Reactive metal-based storage systems are a new alternative to support the clean energy transition. Herein, the cases of Al and Na are presented, both preliminarily fulfilling the constraints regarding sustainability, but employing two rather different processes. Both, the steam combustion of molten Al for H2 and heat production,[4,5] and a new rechargeable battery, which makes use of seawater and sodium as electrodes, show promising round-trip efficiencies.[6] The latter technology also allows CO2-trapping, desalination, Na metal, and chlorine production. It is argued that further research efforts are needed to verify the sustainability and ability of reactive metal-based technologies to compete with other storage technologies.

References

[1] Report of the Conference of the Parties on its Twenty-First Session, held in Paris from 30 November to 13 December 2015, FCCC/CP/2015/10/ Add.1, United Nations Framework on Climate Change, United Nations, New York 2016.

[2] International Energy Agency, World Energy Outlook 2016, International Energy Agency, Paris 2016.

[3] International Energy Agency, World Energy Outlook 2019, International Energy Agency, Paris 2019.

[4] H. Ersoy, M. Baumann, L. Barelli, A. Ottaviano, L. Trombetti, M. Weil, S. Passerini, Adv. Mater. Technol. 2022, 2101400.

[5] L. Barelli, M. Baumann, G. Bidini, P. A. Ottaviano, R. V. Schneider, S. Passerini, L. Trombetti, Energy Technol. 2020, 8, 2000233.

[6] Y. Kim, M. Kuenzel, D. Steinle, X. Dong, G.-T. Kim, A. Varzi, S. Passerini, Energy Environ. Sci., 2022, 15, 2610.
(Invited) Integrating Material Design, in-Operando Spectroscopy and Device Testing for Next Generation Lithium-Sulfur Batteries
Authors: Kalra Vibha
Published: November 2022

Rechargeable batteries with conversion type electrodes are attractive due to their ability to achieve higher capacity through multi-electron transfer reactions. Elemental sulfur is one of the most interesting materials amongst all conversion-based cathodes because of its high theoretical capacity (~1675 mAh/g – 5-10-fold higher than Li-ion batteries), natural abundance, non-toxicity, and cost-effectiveness. In this talk, I will provide glimpses of our group’s research on integrating material design and fabrication, in-operando and postmortem spectroscopy, and device assembly and testing (coin/pouch) to study and develop next generation lithium-sulfur batteries. In particular, I will discuss our projects on studying cathode chemistries to first mitigate polysulfide shuttle via host-polysulfide interactions followed by tailoring of S redox to trigger single plateau behavior for long-term cycle stability.
Electrodeposited NiMo Alloy Coatings for Improved Molten Salt Compatibility
Authors: Hall Timothy , Garich Holly , Radhakrishnan Rajeswaran , Pint Bruce , Parker Cory , Sulejmanovic Dino , Beamer Chad
Published: November 2022

The use of molten halide salts as a primary coolant within next generation molten salt nuclear reactors (MSRs) has the potential to improve efficiency and nuclear reactor safety by operating at low pressures and high temperatures without boiling. However, these coolants will require the development of new corrosion resistant material systems that will have to meet or supersede existing standard codes for these systems. Therefore, new MSRs will require validation and testing of new material systems that can produce robust component structures and enable them to withstand these corrosive environments. Furthermore, any next generation process to apply protective coatings must allow for a conformal, thick, dense, and bonded material to be formed onto an ASME code approved material (e.g. type 316H stainless steel) that will comprise the structure of heat exchanger and containment vessel components.

Within this context, Faraday Technology Inc. in collaboration with Oak Ridge National Lab and Quintus Technologies is working to develop and demonstrate the effectiveness of a low cost and high value corrosion-resistant alloy coating for next generation molten salt reactors. The manufacturing process involves the application of a functionally graded NiMo coating by electrodeposition onto 316H alloy substrates and their subsequent high temperature corrosion evaluation in molten fluoride salt at 700°C. After application the components were hot isostatically pressed (HIPped; at Quintus) to create a diffusion bond between the coating and alloy substrate. Initially, 316H alloy coupons were coated for evaluation (Figure 1 Left) in Mo capsules with static FLiNaK salt known to be corrosive due to metallic impurities. The next stage of testing involved evaluating coatings on the inner diameter of 316H tubes (25mm outer diameter; Figure 1 Middle). Coated tubes (75mm long) had coated endcaps welded to either end and were filled with the same FLiNaK salt and tested for 500 h at 700°C and 1000 h at 750°C. In addition, the microstructure and salt performance of butt welds were evaluated for joints between coated 316H tubes and joints between coated and uncoated 316H tubes. Results from the static capsule testing will be presented including the effect of coating composition and heat treating conditions on the depth of attack in the molten salt as feedback for the coating development process. The final phase of testing will include 200 mm long coated 316H tube sections in the hot and cold legs of a flowing FLiNaK thermal convection loop experiment which is currently being fabricated (Figure 1 R).

Acknowledgements: The financial support of DOE Contract No. DE-SC0019602 is acknowledged.

Figure 1: Corrosion characterization test plan. (Left) static coupon studies, (Middle) static pipe studies, and (Right) continuous flow loop pipe studies.

Figure 1