bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical ellipsometry: A method for selecting a near-minimal infrared measurement set for β-gallium oxide
Authors: Urban Frank K. , Barton David , Schubert Mathias
Published: July 2021

The objective of this work is to develop a method for defining, a priori, a set of minimum ellipsometry measurements that provide for a near-minimal data set (measurement set) sufficient for an analysis of optically anisotropic crystals with monoclinic symmetry with minimal prior knowledge. Example measurements are obtained by reflection from two differently oriented smooth, flat, anisotropic, monoclinic β-Ga2O3 crystals. A measurement may consist of any set of common type ellipsometry data such as selected sets of normalized Jones matrix elements or selected sets of normalized Mueller matrix elements measured at selected angles of incidence and/or rotation of the sample, also know as table rotation. The only prior knowledge used here is the crystallographic surface orientation. The four complex-valued permittivity parameters of the monoclinic symmetry crystal are then the object of interest and the only remaining unknown parameters. The motif for our investigation is the desire to better understand how to reduce measurement time for the otherwise extensive data acquisition considered necessary thus far to fully characterize low-symmetry anisotropic materials in substrates and semiconductor heterostructures. The near-minimal measurement set introduced here is then obtained by selection from a prior, larger data set. The larger data set thus far largely overdetermines the amount of necessary information. The first criterion is that there be sufficient intensity of the reflected light considering the p and s polarized reflections produced by p and s polarized incident light. The second criterion for inclusion is that the permittivity tensor is sensitive to measurement, that is, a significant change in a measurement set results in a significant change in the solution for permittivity. Finally, the near-minimal measurement set must result in solvable sets of equations. This is examined by computing the Jacobian of the system of equations for various sets of measurements in order to only keep measurements for which the condition of the Jacobian falls below the threshold for usability. We find that sets containing four measurements of on-diagonal Jones matrix elements alone, obtained across a wide spread of table rotations, provide most sensitive and intrinsically sufficient information to solve for the permittivity values. In summary, the scheme consists of determining the following measurement conditions: (1) reflections of high intensity to enable accurate measurements. (2) sensitivity to the unknown parameters, and (3) a solvable set of equations.
Mechanical pretreatment of polymer melts: Critical aspects and new rheological investigations on a linear and a long-chain branched polypropylene
Authors: Münstedt Helmut
Published: July 2021

It has been known for some time that mechanical pretreatments of melts of long-chain branched polymers can increase the melt index and reduce the extrudate swell. This effect is not due to changes of the molar mass, its distribution, or the degree of branching because it may be reversed by long-term annealing or dissolution of the polymeric material and subsequent precipitation. Furthermore, molecular analysis shows a molecular structure unaltered by the treatment. The effect has not been completely understood up to now, and it is still an open question as to whether it is restricted to long-chain branched polymers, which have been preferably studied. This paper gives an overview of results from the literature and presents comparable measurements on a well characterized long-chain branched and a linear polypropylene. A wide range of linear and nonlinear rheological properties were studied, and it became obvious that long-chain branching is a strong structural precondition for the pronounced pretreatment effect occurring in processing. Based on this result, models from the literature are discussed, and it is found that chain alignment may qualitatively explain the rheological measurements.
Enhanced Prodigiosin Production in
Serratia marcescens
JNB5-1 by Introduction of a Polynucleotide Fragment into the
pigN
3′ Untranslated Region and Disulfide Bonds into
O
-Methyl Transferase (PigF)
Authors: Sun Yang , Wang Lijun , Osire Tolbert , Fu Weilai , Yi Ganfeng , Yang Shang-Tian , Yang Taowei , Rao Zhiming
Published: July 2021

This study highlights a promising strategy to improve mRNA/enzyme stability and to increase production using
de novo
PNF libraries and the introduction of disulfide bonds into the protein. PNFs could increase the half-life of target gene mRNA and effectively prevent its degradation.
Technological and Environmental Features Determine the Uniqueness of the Lambic Beer Microbiota and Production Process
Authors: Bongaerts Dries , De Roos Jonas , De Vuyst Luc
Published: July 2021

Lambic beers are beers produced through spontaneous fermentation and maturation in wooden barrels. The production process of lambic beers differs from the production processes of lagers and ales in process technology, environmental parameters, and the use of specific raw materials.
Epidemiology and Antifungal Susceptibilities of Mucoralean Fungi in Clinical Samples from the United States
Authors: Badali Hamid , Cañete-Gibas Connie , McCarthy Dora , Patterson Hoja , Sanders Carmita , David Marjorie P. , Mele James , Fan Hongxin , Wiederhold Nathan P.
Published: July 2021

The global incidence of mucormycosis has increased in recent years owing to higher numbers of individuals at risk for these infections. The diagnosis and treatment of this aggressive fungal infection are of clinical concern due to differences in species distribution in different geographic areas and susceptibility profiles between different species that are capable of causing highly aggressive infections.
Receptor Switching in Newly Evolved Adeno-associated Viruses
Authors: Havlik L. Patrick , Das Anshuman , Mietzsch Mario , Oh Daniel K. , Ark Jonathan , McKenna Robert , Agbandje-McKenna Mavis , Asokan Aravind
Published: July 2021

Understanding how viruses interact with host cells through cell surface receptors is central to discovery and development of antiviral therapeutics, vaccines, and gene transfer vectors. Here, we demonstrate that distinct epitopes on the surface of adeno-associated viruses can be evolved by infectious cycling to recognize different cell surface carbohydrates and glycoprotein receptors and solve the three-dimensional structure of one such newly evolved AAV capsid, which provides a roadmap for designing viruses with improved attributes for gene therapy applications.
Human Immunodeficiency Virus (HIV) and Human Cytomegalovirus (HCMV) Coinfection of Infant Tonsil Epithelium May Synergistically Promote both HIV-1 and HCMV Spread and Infection
Authors: Sufiawati Irna , Herrera Rossana , Mayer Wasima , Cai Xiaodan , Borkakoti Jayanta , Lin Vicky , Rosbe Kristina , Tugizov Sharof M.
Published: July 2021

Most HIV-1 and HCMV MTCT occurs in infancy, and the cotransmission of these viruses may occur via infant oropharyngeal and tonsil epithelia, which are the first biological barriers for viral pathogens. We have shown that HIV-1 and HCMV disrupt epithelial junctions, reducing the barrier functions of epithelia and thus allowing paracellular penetration of both viruses via mucosal epithelia.
Imaging and Quantification of mRNA Molecules at Single-Cell Resolution in the Human Fungal Pathogen Candida albicans
Authors: Moreno-Velásquez Sergio D. , Pérez J. Christian
Published: July 2021

Tools to visualize and quantify transcripts at single-cell resolution have enabled the dissection of spatiotemporal patterns of gene expression in animal cells and tissues. Yet the accurate quantification of transcripts at single-cell resolution remains challenging for the much smaller microbial cells.
Longitudinal COVID-19 Surveillance and Characterization in the Workplace with Public Health and Diagnostic Endpoints
Authors: Gunawardana Manjula , Breslin Jessica , Cortez John M. , Rivera Sofia , Webster Simon , Ibarrondo F. Javier , Yang Otto O. , Pyles Richard B. , Ramirez Christina M. , Adler Amy P. , Anton Peter A. , Baum Marc M.
Published: July 2021

The rapid spread of SARS-CoV-2 and the associated COVID-19 has precipitated a global pandemic heavily challenging our social behavior, economy, and health care infrastructure. In the absence of widespread, worldwide access to safe and effective vaccines and therapeutics, public health measures represent a key intervention for curbing the devastating impacts from the pandemic.
Comparison of volume guarantee and volume-controlled ventilation both using closed loop inspired oxygen in preterm infants: a randomised crossover study (CLIO-VG study)
Authors: Nair Vrinda , Lal Mithilesh Kumar , Gillone Jenna , Kannan Loganathan Prakash , Bachman Thomas Edward
Published: July 2021

Objective

The objective of this study was to compare two different modes of ventilation in maintaining oxygen saturation (SpO2) in target range (90%–95%) in ventilated preterm infants cared for with automatic control of oxygen delivery (A-FiO2).

Design

A single-centre randomised crossover study.

Settings

A level III neonatal intensive care unit.

Patients

Preterm infants receiving mechanical ventilation and oxygen requirement >21%.

Interventions

Volume guarantee (VG) vs volume controlled ventilation (VCV) modes with automatic oxygen control (A-FiO2).

Outcomes

The primary outcome of this study was the proportion of time spent with oxygen saturations in the target range (90%–95%) .

Results

Nineteen preterm infants with a median gestation age 25 weeks (IQR: 24–28) and birth weight 685 g (IQR: 595–980) were enrolled in the study. There was no significant difference in primary outcome of median proportion of time spent in target saturation between the two arms (72% (57–81) in VG vs 75% (58–83) in VCV; p=0.98). There was no significant difference in the secondary outcomes of time spent in SpO2 <80% (0.03% vs 0.14%; p=0.51), time spent in SpO2 >98% (0.50% vs 0.08%; p=0.54), the median FiO2 (31% vs 29%; p=0.51) or manual adjustments carried out between VG and VCV, respectively. The number of episodes of prolonged hypoxaemia and hyperoxaemia were similar in the two groups.

Conclusion

There was no significant difference in time spent in target SpO2 range between VG and VCV when A-FiO2 was used as the FiO2 controller in this crossover randomised control study.

Trial registration number

NCT03865069.
Fine crackles on chest auscultation in the early diagnosis of idiopathic pulmonary fibrosis: a prospective cohort study
Authors: Moran-Mendoza Onofre , Ritchie Thomas , Aldhaheri Sharina
Published: July 2021

Introduction

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease (ILD) with a poor prognosis. Early diagnosis and treatment of IPF may increase lifespan and preserve quality of life. Chest CT is the best test to diagnose IPF, but it is expensive and impractical as a screening test. Fine crackles on chest auscultation may be the only best to screen for IPF.

Methods

We prospectively assessed the presence and type of crackles on chest auscultation in all patients referred to the ILD Clinic at the Kingston Health Sciences Center in Ontario, Canada. Clinicians with varying levels of experience recorded the presence of fine crackles, coarse crackles or both independently and unaware of the final diagnosis. We applied multinomial logistic regression to adjust for ILD severity and factors that could affect the identification of crackles.

Results

We evaluated 290 patients referred to the ILD Clinic. On initial presentation, 93% of patients with IPF and 73% of patients with non-IPF ILD had fine crackles on auscultation. In patients with IPF, fine crackles were more common than cough (86%), dyspnoea (80%), low diffusing capacity (87%), total lung capacity (57%) and forced vital capacity (50%). There was 90% observer agreement in identifying fine crackles at a subsequent visit. In multiple regression analysis, the identification of fine crackles was unaffected by lung function, symptoms, emphysema, chronic obstructive pulmonary disease, obesity or clinician experience (p>0.05).

Conclusions

Fine crackles on chest auscultation are a sensitive and robust screening tool that can lead to early diagnosis and treatment of patients with IPF.
Childhood reading problems and cognitive ageing across mid to later life
Authors: John Amber , Stott Josh , Richards Marcus
Published: July 2021

Background

Little research has investigated long-term associations of childhood reading with cognitive ageing. The aim of this study was to test longitudinal associations between childhood reading problems and cognitive function from mid-adulthood (age 43) to early old age (age 69), and whether associations were mediated by education.

Methods

Data were from the MRC National Survey of Health and Development, a prospective population-based birth cohort. Reading problems were measured at age 11 using a reading test. Verbal memory and processing speed were measured at ages 43, 53, 60–64 and 69 and Addenbrooke’s Cognitive Examination (ACE) was administered at age 69. Linear mixed models and path analyses were used to test: (1) associations between reading problems and verbal memory and processing speed trajectories; (2) associations between reading problems and ACE-III scores; (3) whether associations were mediated by education.

Results

Reading problems were associated with poorer verbal memory at intercept but not rate of decline (N=1726), and were not associated with processing speed intercept or decline (N=1730). There were higher rates of scores below ACE-III clinical thresholds (<82 and <88) in people with reading problems compared with those without. Reading problems were associated with poorer total ACE-III scores and all domain scores at age 69 (N=1699). Associations were partly mediated by education.

Conclusion

Reading problems in childhood were associated with poorer cognitive function in early old age, and associations were partly mediated by education.
Long-term trajectories of decline in cognition and daily functioning before and after stroke
Authors: Heshmatollah Alis , Dommershuijsen Lisanne J. , Fani Lana , Koudstaal Peter J. , Ikram M. Arfan , Ikram M. Kamran
Published: July 2021

Objective

Although knowledge on poststroke cognitive and functional decline is increasing, little is known about the possible decline of these functions before stroke. We determined the long-term trajectories of cognition and daily functioning before and after stroke.

Methods

Between 1990 and 2016, we repeatedly assessed cognition (Mini-Mental State Examination (MMSE), 15-Word Learning, Letter–Digit Substitution, Stroop, Verbal Fluency, Purdue Pegboard) and basic and instrumental activities of daily living (BADL and IADL) in 14 712 participants within the population-based Rotterdam Study. Incident stroke was assessed through continuous monitoring of medical records until 2018. We matched participants with incident stroke to stroke-free participants (1:3) based on sex and birth year. Trajectories of cognition and daily functioning of patients who had a stroke 10 years before and 10 years after stroke and the corresponding trajectories of stroke-free individuals were constructed using adjusted linear mixed effects models.

Results

During a mean follow-up of 12.5±6.8 years, a total of 1662 participants suffered a first-ever stroke. Patients who had a stroke deviated from stroke-free controls up to 10 years before stroke diagnosis in cognition and daily functioning. Significant deviations before stroke were seen in scores of MMSE (6.4 years), Stroop (5.7 years), Purdue Pegboard (3.8 years) and BADL and IADL (2.2 and 3.0 years, respectively).

Conclusion

Patients who had a stroke have steeper declines in cognition and daily functioning up to 10 years before their first-ever stroke compared with stroke-free individuals. Our findings suggest that accumulating intracerebral pathology already has a clinical impact before stroke.
Are conscientious objectors morally obligated to refer?
Authors: Reis-Dennis Samuel , Brummett Abram L
Published: July 2021

In this paper, we argue that providers who conscientiously refuse to provide legal and professionally accepted medical care are not always morally required to refer their patients to willing providers. Indeed, we will argue that refusing to refer is morally admirable in certain instances. In making the case, we show that belief in a sweeping moral duty to refer depends on an implicit assumption that the procedures sanctioned by legal and professional norms are ethically permissible. Focusing on examples of female genital cutting, clitoridectomy and ‘normalizing’ surgery for children with intersex traits, we argue that this assumption is untenable and that providers are not morally required to refer when refusing to perform genuinely unethical procedures. The fact that acceptance of our thesis would force us to face the challenge of distinguishing between ethical and unethical medical practices is a virtue. This is the central task of medical ethics, and we must confront it rather than evade it.
Disaster preparedness should represent an augmentation of the everyday trauma system, but are we prepared?
Authors: Jørgensen Jørgen Joakim , Monrad-Hansen Peter Wiel , Gaarder Christine , Næss Paal Aksel
Published: July 2021

Background

The increased frequency, geographical spread and the heterogenicity in mass casualty incidents (MCIs) challenge healthcare systems worldwide. Trauma systems constitute the base for disaster preparedness. Norway is sparsely populated, with four regional trauma centers (TCs) and 35 hospitals treating trauma (non-trauma centers (NTCs)). We wanted to assess whether hospitals fill the national trauma system requirements for competence and the degree of awareness of MCI plans.

Methods

We conducted a cross-sectional survey of on-call trauma teams in all 39 hospitals during two time periods: July–August (holiday season (HS)) and September–June (non-holiday season (NHS)). A standardized questionnaire was used to evaluate the MCI preparedness.

Results

A total of 347 trauma team members participated (HS: 173 and NHS: 174). Over 95% of the team members were aware of the MCI plan; half had read the plan during the last 6 months, whereas 63% at the TCs and 74% at NTCs were confident with their MCI role. Trauma team exercises were conducted regularly and 86% had ever participated. Only 63% at the TCs and 53% at the NTCs had participated in an MCI exercise. The proportion of resident surgeons and anesthetists with >4 years’ clinical experience was significantly higher in TCs (88% and 63%) than in NTCs (27% and 17%). All the on-call consultant surgeons were at home, leaving interns in charge at several of the hospitals. All resident surgeons at the TCs were ATLS providers compared with 64% at the NTCs, and almost 90% of the consultant surgeons had participated in advanced trauma surgical courses.

Discussion

Despite increased national focus on disaster preparedness, we identified limited compliance with trauma system requirements concerning competency and training. Strict guidelines to secure immediate notification and early presence of consultants whenever a situation that might turn into an MCI occurs should be a prerequisite.

Level of evidence

Level IV. Study type: cross- sectional.
Where the infection is isolated rather than the specific species correlates with adherence strength, whereas biofilm density remains static in clinically isolated Candida and arthroconidial yeasts
Authors: ElGindi Mei , Al-Baghdadi Rula , Jackman Alex B. , Antonyan Angelina S. , McMahon Diana L. , Taj-Aldeen Saad J. , Finkel Jonathan S.
Published: July 2021

To colonize and infect the host, arthroconidial yeasts must avoid being killed by the host’s defenses. The formation of biofilms on implanted devices allows fungi to avoid host responses and to disseminate into the host. To better study the mechanisms of infection by arthroconidial yeasts, adherence and biofilm formation were assayed using patient samples collected over 10 years. In clinical samples, adherence varies within species, but the relative adherence is constant for those samples isolated from the same infection site. Herein we document, for the first time, in-vitro biofilm formation by Trichosporon dohaense, T. ovoides, T. japonicum, T. coremiiforme, Cutaneotrichosporon mucoides, Cutaneotrichosporon cutaneum, Galactomyces candidus, and Magnusiomyces capitatus on clinically relevant catheter material. Analysis of biofilm biomass assays indicated that biofilm mass changes less than 2-fold, regardless of the species. Our results support the hypothesis that most pathogenic fungi can form biofilms, and that biofilm formation is a source of systemic infections.
Microorganisms that participate in biochemical cycles in wetlands
Authors: Mellado Macarena , Vera Jeannette
Published: July 2021

Several biochemical cycles are performed in natural wetlands (NWs) and constructed wetlands (CWs). Knowledge of microorganisms can be used to monitor the restoration of wetlands and the performance of wastewater treatment. The phylum Proteobacteria is the most abundant in NWs and CWs, which plays a role in nitrogen (N), phosphorus (P), and sulfur (S) cycles, and in the degradation of organic matter. Other phyla were present at lower abundance. Archaea participate in methanogenesis, methane oxidation, and methanogenic N2 fixation. S and P cycles are also performed by other microorganisms, such as Chloroflexi and Nitrospirae. In general, there is more information about the N cycle, especially nitrification and denitrification. Processes where archaea participate (e.g., methane oxidation and methanogenic N2 fixation) remain unclear, and several of these microorganisms have not been isolated so far. In this study, we used 16S rDNA or functional genes. The use of functional genes provides information to monitor specific microbial populations, and 16S rDNA is more suitable for taxonomic classification. In addition, several Candidatus microorganisms have not been isolated to date. However, their metabolic roles in the biochemical cycle of wetlands have been described.
Dark matter in the fully flipped 3-3-1-1 model
Authors: Van Loi Duong , Nam Cao H. , Van Dong Phung
Published: July 2021

We present the features of the fully flipped 3-3-1-1 model and show that this model leads to dark matter candidates naturally. We study two dark matter scenarios corresponding to the triplet fermion and singlet scalar candidates, and we determine the viable parameter regimes constrained from the observed relic density and direct detection experiments.
UNIFORM DIOPHANTINE APPROXIMATION TO CANTOR SERIES EXPANSION
Authors: HAN YAN , MA CHAO
Published: July 2021

In this paper, we study the uniform Diophantine approximation in the nonautonomous dynamic system generated by the Cantor series expansions, which is formulated by considering the following set: [Formula: see text] It is of Hausdorff dimension [Formula: see text] for [Formula: see text] and is countable for [Formula: see text] under the condition that [Formula: see text]
FRACTAL-BASED MODELS STUDY OF THE RELATIVE HYDRAULIC CONDUCTIVITY AND SWCC OF BENTONITE BY SYNCHROTRON RADIATION SAXS AND X-RAY COMPUTED TOMOGRAPHY
Authors: PENG LEI , CHEN BING
Published: July 2021

Fractal-based approaches have become popular for describing the hydraulic functions. The SWCC and relative hydraulic conductivity were calculated and compared based on fractal models by the fractal dimension ([Formula: see text] determined by small angle X-ray scattering (SAXS) and X-ray computed tomography (CT). Pore structure parameters including pore size, [Formula: see text], tortuosity and tortuosity fractal dimension, porosity, characteristic length were investigated. The SWCC and relative hydraulic conductivity were predicted, compared and verified. The results indicated that the [Formula: see text] of GMZ01 calculated by SAXS and CT were 2.60 and 2.72, respectively, and the difference was small. The [Formula: see text] of GMZ01 calculated by CT was 2.62. [Formula: see text] calculated by SAXS and CT has a large difference. Nitrogen adsorption revealed the effectiveness of SAXS in predicting porosity in the nanoscale self-similar interval. A SWCC fractal model considering the tortuosity fractal dimension was improved. The tortuosity of GMZ01, CaGMZ, GMZ07 and SY are calculated as 1.53, 1.47, 1.60 and 1.29, respectively. When the tortuosity was considered, the hydraulic conductivity became lower. For GMZ01, the SWCC predicted by the fractal dimension measured by SAXS was closer to the experimental data than the SWCC predicted by the fractal dimension measured by CT. The fractal model was difficult to describe SWCC under low matric suction, while the predicted SWCC had a good correlation with the experimental value in high matric suction. The relative hydraulic conductivity calculated by Xu and Yu model was larger than that calculated by Xu model.
How to calculate the proportion of everywhere locally soluble diagonal hypersurfaces
Authors: Hirakawa Yoshinosuke , Kanamura Yoshinori
Published: July 2021

In this paper, we establish a strategy for the calculation of the proportion of everywhere locally soluble diagonal hypersurfaces of [Formula: see text] of fixed degree. Our strategy is based on the product formula established by Bright, Browning and Loughran. Their formula reduces the problem into the calculation of the proportions of [Formula: see text]-soluble diagonal hypersurfaces for all places [Formula: see text]. As worked examples, we carry out our strategy in the cases of quadratic and cubic hypersurfaces. As a consequence, we prove that around [Formula: see text] of diagonal cubic fourfolds have [Formula: see text]-rational points under a hypothesis on the Brauer–Manin obstruction.
Cesàro averages for Goldbach representations with summands in arithmetic progressions
Authors: Cantarini Marco , Gambini Alessandro , Zaccagnini Alessandro
Published: July 2021

Let [Formula: see text] be the von Mangoldt function, let [Formula: see text] be an integer and let [Formula: see text] be the counting function for the Goldbach numbers with summands in arithmetic progression modulo a common integer [Formula: see text]. We prove an asymptotic formula for the weighted average, with Cesàro weight of order [Formula: see text], with [Formula: see text], of this function. Our result is uniform in a suitable range for [Formula: see text].
Efficient Retrieval of Human Motion Episodes Based on Indexed Motion-Word Representations
Authors: Budikova Petra , Sedmidubsky Jan , Horvath Jan , Zezula Pavel
Published: July 2021

With the increasing availability of human motion data captured in the form of 2D or 3D skeleton sequences, more complex motion recordings need to be processed. In this paper, we focus on similarity-based indexing and efficient retrieval of motion episodes — medium-sized skeleton sequences that consist of multiple semantic actions and correspond to some logical motion unit (e.g. a figure skating performance). As a first step toward efficient retrieval, we apply the motion-word technique to transform spatio-temporal skeleton sequences into compact text-like documents. Based on these documents, we introduce a two-phase retrieval scheme that first finds a set of candidate query results and then re-ranks these candidates with more expensive application-specific methods. We further index the motion-word documents using inverted files, which allows us to retrieve the candidate documents in an efficient and scalable manner. We also propose additional query-reduction techniques that accelerate both the retrieval phases by removing semantically irrelevant parts of the motion query. Experimental evaluation is used to analyze the effects of the individual proposed techniques on the retrieval efficiency and effectiveness.
On split generalized mixed equilibrium and fixed point problems of an infinite family of quasi-nonexpansive multi-valued mappings in real Hilbert spaces
Authors: Akutsah F. , Abass H. A. , Mebawondu A. A. , Narain O. K.
Published: July 2021

In this paper, we study split generalized mixed equilibrium problem and fixed point problem in real Hilbert spaces with a view to analyze an iterative method for approximating a common solution of split generalized mixed equilibrium problem and fixed point problem of an infinite family of a quasi-nonexpansive multi-valued mappings. The iterative algorithm introduced in this paper is designed in such a way that it does not require the knowledge of the operator norm. We state and prove a strong convergence result of the aforementioned problems and also give application of our main result to split variational inequality problem. Our result complements and extends some related results in literature.
On the skew Laplacian spectral radius of a digraph
Authors: Chat Bilal A. , Ganie Hilal A. , Bhat Altaf A. , Bhat Mohd Y. , Lone Mehraj A.
Published: July 2021

Let [Formula: see text] be an orientation of a simple graph [Formula: see text] with [Formula: see text] vertices and [Formula: see text] edges. The skew Laplacian matrix [Formula: see text] of the digraph [Formula: see text] is defined as [Formula: see text], where [Formula: see text] is the imaginary unit, [Formula: see text] is the diagonal matrix with oriented degrees [Formula: see text] as diagonal entries and [Formula: see text] is the skew matrix of the digraph [Formula: see text]. The largest eigenvalue of the matrix [Formula: see text] is called skew Laplacian spectral radius of the digraph [Formula: see text]. In this paper, we study the skew Laplacian spectral radius of the digraph [Formula: see text]. We obtain some sharp lower and upper bounds for the skew Laplacian spectral radius of a digraph [Formula: see text], in terms of different structural parameters of the digraph and the underlying graph. We characterize the extremal digraphs attaining these bounds in some cases. Further, we end the paper with some problems for the future research in this direction.
Solid Oxide Cell Technology for Supply, Recovery, and Storage Energy
Authors: Ghezel-Ayagh Hossein
Published: July 2021

Fuel Cell Energy, Inc. (FCE) is advancing the current state of Solid Oxide Fuel Cell (SOFC) technology towards commercial deployment for efficient and nonpolluting generation of electric power from natural gas, biomass, and hydrogen fuels. Additionally, FCE is utilizing the same solid oxide cell and stack technology in steam electrolysis for production of hydrogen from renewable sources and other electric power stations such as nuclear power plants during the curtailment periods. The capabilities of SOFC as fuel cell and as electrolyzer has expanded opportunities for reversible operation and its application in energy storage.
Field Test Result of Residential SOFC CHP System Over 10 Years, 89000 Hours
Authors: Suzuki Minoru , Inoue Shuichi , Shigehisa Takashi
Published: July 2021

The maxmum operating time without stack replacement, residential SOFC power generation unit (manufactured by Kyocera in 2009), which was installed by Osaka Gas in a house in 2009, has exceeded over 10 years, 89000 power generating hours. In 2004, Osaka Gas and Kyocera started joint development of residential SOFC CHP system and from 2007, we conducted series of field tests in the SOFC demonstration project operated by NEDO and NEF. At that time, various technical issues remained, and after joint development with Aisin and Toyota Motor, it was mass-produced and commercialized in 2012. We also mention the current status of residential SOFC (Manufactured by Aisin, SOFC stack supplied by Kyocera). Osaka Gas has sold more than a total of 88,000 residential SOFC CHP systems as of October 2020.
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

Recently, it has been demonstrated that the application of additive manufacturing (AM) technologies for functional ceramics fabrication, especially 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 and to increase manufacturing productiveness, while the waste material is reduced. As a result, a 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 and robocasting has been developed. Thus, the technique uses 8YSZ for the electrolyte fabrication by stereolithography and deposition of electrodes and interconnectors by robocasting. 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 and discussed.
Development of High-Performance Anode-Supported Planar SOFC with Large Area by 4-Layer Co-Firing Process
Authors: Hussain Amjad , Song Rak-Hyun , Joh Dong Woo , Hong Jong-Eun , Lee Seung-Bok , Lim Tak-Hyoung
Published: July 2021

Solid oxide fuel cell (SOFC) technology has attracted great attention because of higher efficiency, fuel flexibility, and eco-friendly stationary power generation system. However, its commercialization is hindered due to the lack of durability and high-cost. Herein, a facile and exceptionally reliable 4-layered anode supported SOFCs with a large area (12cm×12cm) was fabricated in a single step co-firing process at 1400°C, in which tape-casted green films of NiO-YSZ, NiO-1CeScSZ, 1CeScSZ, and GDC were laminated by isostatic press. The fabrication parameter, such as viscosity of the slurries and mechanical strengths of the green films, were optimized. As a result, finely porous anode layer, and highly dense 1CeScSZ electrolyte and GDC buffer layers on a robust porous anode-support, were formed successfully. The possibility of mass production is verified through the fabrication of large area cells with an active area 100 cm2. The single cell showed high-power output of 28 W at total current 50 A at 700°C and exhibits low degradation rate of 0.2%/kh at 25A for long-term test of 1000 hrs. This facile strategy is time-efficient, reproducible, cost-effective, and highly practical to produce SOFC system satisfying both high-performance and durability.
Improving Current Collection of Tubular Solid Oxide Fuel Cells
Authors: Feng Hai , Panthi Dhruba , Du Yanhai
Published: July 2021

Solid Oxide Fuel Cells (SOFCs) are electrochemical devices with solid electrolyte materials that convert chemical energy in fuels into electrical energy. Tubular SOFC is one of the major SOFC configurations which has the advantages of good thermal conductivity, easy to seal and shorter start-up time. However, challenges remain in effectively collecting the current inside the tubular cells. Developing an efficient, easily applicable, and cost-effective collector is imperative. The properties of a desired current collector are to: reflect the fuel cell performance, be able to withstand the fuel cell’s high working temperature environment, protect the fuel cell from damage, simplify the current collector application procedure, expand the contact surface between the tube and the current collector, and save cost. We have designed a current collector and identified the materials for inside tube current collection with desired characteristics such as high temperature tolerance, low electrical resistance, and low cost. The research focused on the effectiveness of the current collector and its durability at various fuel cell operation conditions. The design achieved a peak power density of 0.21 W/cm2 at 0.7V and 700oC for a conventional tubular SOFC with material set of Ni+8YSZ‖YSZ‖LSM. Comparing to the general metal (nickel, silver) current collectors, the material which is provided in the paper can reduce the cost from hundreds of dollars per yard to $0.13/yard. The paper will discuss the design and the cost-effective material selection of the current collector which provides a potential path for the commercialization of tubular SOFC technology.
Fabrication and Characterization of a Tubular Solid Oxide Fuel Cell with Impregnated Perovskite Electrodes
Authors: Nowicki Kamil Maciej , Wang Mei , Irvine John Thomas Sirr
Published: July 2021

The tubular cells were produced by a simple and inexpensive method, suitable for mass production. A porous YSZ backbone was co-cast with a thin layer of YSZ electrolyte over it. After rolling in tubular shape and co-sintering, the porous backbone was impregnated with functional perovskite materials, the nickel doped lanthanum calcium titanate LCNT (La0.43Ca0.37Ni0.06Ti0.94O3-
γ) for the fuel side and the lanthanum strontium ferrite LSF (La0.8Sr0.2FeO3) for the air electrode. The LCNT perovskite was proposed as the alternative fuel electrode due to its mixed ionic and electronic conductivity (MIEC) properties and catalytical activity supplemented by exsolved Ni nanoparticles. The electrochemical poling at high potential, so-called 'switching', can increase the activity of LCNT due to facilitated reduction and exsolution. After switching at 2.1 V for 2 min, the tubular cell performance in fuel cell mode increased threefold. The impedance analysis indicated a reduction of ohmic and polarisation resistance on the whole frequency range and facilitated electrode kinetics under applied voltage.
Micro-Tubular Solid Oxide Fuel Cells with One Closed-End Fabricated Via Dip-Coating and Co-Firing
Authors: Hedayat Nader , Du Yanhai
Published: July 2021

The tubular solid oxide fuel cells (SOFCs) with one closed-end configuration have high thermal-cycling tolerance owing to the capability of expanding and shrinking freely in response to thermal stresses. The tubular cells with one closed-end have simple sealing requirements, and enable making the stacks with uniform temperature distribution. In this study, anode supported micro-tubular SOFCs with one closed-end were manufactured successfully by dip-coating and co-firing methods using carbon rods as a template. A dense electrolyte layer was obtained at a co-firing temperature of 1400°C, followed by cathode deposition and sintering. The prepared micro-tubular SOFCs were comprised of Ni-yttria-stabilized zirconia, Ni–scandia-stabilized zirconia (SSZ), SSZ, strontium-doped lanthanum manganite (LSM)-SSZ, and LSM as the anode support, anode functional layer, electrolyte, cathode functional layer, and cathode current collector, respectively. The developed dip-coating method is fast in turnaround time and enables fabricating the one closed-end tubes of various lengths and diameters by co-firing.
Properties and Performance of Electrolyte Supported SOFCs with EB-PVD Gd-Doped Ceria Thin-Films
Authors: Han Feng , Riegraf Matthias , Sata Noriko , Bombarda Ilaria , Liensdorf Tom , Sitzmann Carolin , Langhof Nico , Schafföner Stefan , Walter Christian , Geipel Christian , Costa Rémi
Published: July 2021

In this work, dense gadolinium-doped ceria (GDC) thin-films with thickness of 0.15 and 0.5 µm were fabricated on 90 µm thick 3YSZ electrolytes by electron beam physical vapor deposition (EB-PVD), and integrated into electrolyte supported solid oxide cells (ESC) as Sr-barrier layer. Operated at 860°C, the ESC with 0.5 µm GDC thin-film outperformed the cells with 0.15 µm GDC layers and delivered a power density of 0.54 W•cm-2 at a cell voltage of 0.7 V. Post mortem investigations by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed that 0.5 µm thick GDC thin-films were effective to suppress the formation of the strontium zirconate phase at the YSZ/GDC interface.
Additive Manufacturing of Large Area SOC with Advanced Features
Authors: Lira Maritta , Kostretsova Natalia , Bernadet Lucile , Morata Alex , Torrell Marc , Tarancón Albert
Published: July 2021

The incorporation of electrochemical-based energy devices such as Solid Oxide Cells (SOC) to the renewable energy sector in the frame of a modern energy generation strategy could be beneficial, taking into account the opportunity to store renewable energy overproduction as well as to use, subsequently, this hydrogen as a fuel for energy generation in the same device. Nowadays SOC manufacturing approaches, meet the limits originated by the capabilities of the techniques to produce the ceramic components with complicated geometries. The AM, specifically the SLA in this work, allows the simplification of SOC manufacturing process in a more effective way in terms of time, cost, and waste material reduction. To demonstrate its scalability, large area 3YSZ electrolytes (~50-60cm2) with the advanced geometries were fabricated by SLA three-dimensional printer, to be implemented as an electrolyte-supported cell using YSZ composites with lanthanum strontium manganite (LSM) as a cathode and nickel composites as an anode.
Optimization of Methane Reforming for High Efficiency and Stable Operation of SOFC Stacks
Authors: Liu Yaodong , Lyu Zewei , Han Minfang
Published: July 2021

Solid Oxide Fuel Cells (SOFCs) provides an efficient and clean pathway to generate electricity. In addition to hydrogen, SOFCs also hold the possibility for the utilization of a variety of carbon containing fuels. A practical kilowatt-class SOFC system fueled by methane has been preliminarily integrated previously. This study intended to obtain the optimized working conditions for the pre-reformer, with which the SOFC module can exhibit higher electrical performance. Detailed thermodynamic analysis and experimental measurements of steam methane reforming (SMR) were carried out under different steam to carbon ratios (S/C) and temperatures, where the experimental results matched well with the thermodynamic calculation. Based on the optimized working condition of SMR, the electrical performance and stability of a planar single-layer stack (10×10 cm2) fueled by the reformate syngas was evaluated. The maximum electrical efficiency reached 65.39% (LHV) at 750ºC, and 50-hour stable operation under 50% (LHV) electrical efficiency was achieved.
Development of a High-Efficiency, Low-Cost Hybrid SOFC/Internal Combustion Engine Power Generator
Authors: Braun Rob , Floerchinger Gus , Wahlstrom David , Sullivan Neal P. , Vincent Tyrone , Danforth Robert , Bandhauer Todd , Olsen Daniel , Windom Brett
Published: July 2021

The unique and beneficial characteristics of solid oxide fuel cell (SOFC) technology hold much promise for their eventual widespread adoption in numerous commercial building applications. Nevertheless, cost and durability challenges remain that currently limit SOFC technology penetration in stationary energy applications. Under the U.S. DOE ARPA-E INTEGRATE program, the Colorado School of Mines and its partners are developing a novel hybrid stationary power system comprised of an intermediate temperature (600-degreeC), metal-supported solid oxide fuel cell stack integrated with a high efficiency stationary engine and novel balance-of-point (BOP) equipment.
Projections for Solid Oxide Electrolysers for Water Electrolysis
Authors: Vora Shailesh , Williams Mark
Published: July 2021

It is shown that lowering area specific resistance (ASR) or Rt (total resistance) should lead to lower capital cost, CAPEX, and also to the lowest possible electrical power consumption per hydrogen produced, OPEX. Many researchers have focused for many years on thinning component layers and developing new higher-performance materials. Thinning of components to lower RT is widely researched. Based on simple correlations, the CAPEX of the solid oxide electrolysis cell (SOEC) stack cost could expect to be lowered by 25 percent by thinning components. In terms of size this low- Rt SOEC stack has the potential to be significantly smaller. Building off the DOE’s progress with SOFC, even lower Rt SOEC and SOFC’s are possible with techniques such as sputtering and Atomic Layer Deposition (ALD) which produce better conducting materials. This is truly remarkable in that the low per kilowatt SOEC stack cost and low power consumption may make the SOEC a truly realizable economically viable SO manifestation.
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

Over the past several years, Nexceris has been developing high performance Solid Oxide Electrolysis Cells “SOEC” and stacks leveraging materials, electrode, and interlayer development along with Nexceris’ high power-density stack design. Observed performance and durability improvements demonstrated on both single cells and short stacks will be addressed. Stack intent cells with downselected electrode sets were scaled to both 42 and 96 cm2 active area cells. These were implemented into short-stacks and operated continuously in SOEC mode at ~1.3 V for ≥ 500 hours with <5%/kh degradation. The resulting subscale stack demonstrations provided promising baseline performance and a 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. This paper will provide a status update on Nexceris’ SOEC technology development.
Development of a 10/40kW-Class Reversible Solid Oxide Cell System at Forschungszentrum Jülich
Authors: Peters Roland , Tiedemann Wilfried , Hoven Ingo , Deja Robert , Kruse Nicolas , Fang Qingping , Blum Ludger , Peters Ralf
Published: July 2021

In 2018, a 5/15 kW reversible solid oxide cell system was developed and successfully operated. Based on these positive outcomes, a larger system in the power class of 10/40 kW was planned, with the well-established “Integrated Module” constituting a core element. This module consists of four 20-layer sub-stacks, two heat exchangers, and five heating plates. The basic structure was retained as per the previous system and the surrounding balance of plant components were adjusted in accordance with the higher power level. This adaptation is outlined using the example of an air heat exchanger. A possible efficiency optimization in electrolysis mode via a highly efficient steam generation process is also described and substantiated by experimental results.
Forschungszentrum Jülich – Current Activities in SOC Development
Authors: De Haart L. G. J. (Bert) , Beale S. B. , Deja R. , Dittrich Lucy , Duyster T. , Fang Qingping , Foit Severin , Gross-Barsnick Sonja , Margaritis N. , de Haart U. , Hoven I. , Kruse Nicolas , Lenser C. , Ma Q. , Menzler Norbert H. , Naumenko D. , Nohl Markus , Peters Roland , Sebold D. , Thaler Florian , Tiedemann W. , Unachukwu I. , Varghese B. A. , Vibhu Vaibhav , Vinke I.C. , Wolf Stephanie E. , Zhang Shidong , Zurek J. , Blum L.
Published: July 2021

This contribution highlights selected current activities of the SOC development at Forschungszentrum Jülich. Continued efforts are being made to gain a better understanding of degradation process in our cells and stacks. New materials are being developed to mitigate known degradation phenomena. Systems development was directed at the improvement of reversible operation, especially in electrolysis mode. On cell and stack level investigation of electrolysis operation was also intensified, focusing on CO2-valorization.