bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental evidence for proarrhythmic effects of nonsteroidal anti‐inflammatory drugs in a sensitive whole‐heart model
Authors: Wolfes Julian , Ellermann Christian , Bäumer Svenja , Fehr Michael , Willy Kevin , Wegner Felix , Leitz Patrick R. , Eckardt Lars , Frommeyer Gerrit
Published: October 2021

Background

Previous studies have raised serious concerns on cardiovascular safety of widely prescribed nonsteroidal anti‐inflammatory drugs (NSAIDs). Therefore, the aim of this study was to characterize the electrophysiological effects of certain NSAIDs in an established whole heart model of proarrhythmia.

Methods and results

Thirty‐eight hearts of New Zealand White rabbits were harvested and retrogradely perfused employing a Langendorff setup, and electrophysiology studies were performed to investigate action potential duration at 90% of repolarization (APD90), QT intervals, and effective refractory period (ERP). After generating baseline data, hearts were perfused with ibuprofen (Group 1, n = 12; 10 and 30 μM), indomethacin (Group 2, n = 13; 10 and 20 μM) and diclofenac (Group 3, n = 13; 10 and 20 μM), respectively, and the pacing protocols were repeated for each concentration. In all groups, perfusion with the NSAIDs resulted in a significant and reproducible shortening of APD90 and QT interval. In all groups, the arrhythmia susceptibility was significantly raised as occurrence of monomorphic ventricular tachycardia under programmed ventricular stimulation was significantly increased under perfusion with ibuprofen, indomethacin and diclofenac in all concentrations.

Conclusion

The perfusion with ibuprofen, indomethacin and diclofenac in commonly used doses raised the arrhythmia susceptibility in an established rabbit whole‐heart model while APD shortening and shortened ERP seem to be crucial for arrhythmogenesis.
Intestinal pathophysiological abnormalities in steady state and after vaso‐occlusive crisis in murine sickle cell disease
Authors: Poplawska Maria , Dutta Dibyendu , Jayaram Manjunath , Salifu Moro , Chong Ngee S. , Lim Seah H.
Published: October 2021

We showed in the present study that, not unlike in adult patients with sickle cell disease (SCD), Townes mice exhibit increases in serum intestinal fatty acid binding proteins and lipopolysaccharides (LPS), together with a breach in the intestinal barrier. These abnormalities increased rapidly after the induction of vaso‐occlusive crisis (VOC). We also confirmed higher intestinal microbial density in SCD. These findings support the concept that SCD and/or its complications, and not hospitalisation or medications, are responsible for the intestinal pathophysiological changes. The present results provide the basis for use of Townes mice to further elucidate the mechanistic relationship between intestinal pathophysiology and VOC.
Role of NaV1.7 in action potential conduction along human bronchial vagal afferent C‐fibres
Authors: Kollarik Marian , Ru Fei , Pavelkova Nikoleta , Mulcahy John , Hunter John , Undem Bradley J.
Published: October 2021

Background and Purpose

The purpose of this study was to determine the role of NaV1.7 in action potential conduction in C‐fibres in the bronchial branches of the human vagus nerve.

Experimental Approach

Bronchial branches of the vagus nerve were dissected from human donor tissue. The C‐wave of the electrically evoked compound action potential was quantified in the absence and presence of increasing concentrations of the selective NaV1.7 blocking drugs, PF‐05089771 and ST‐2262, as well as the NaV1.1, 1.2, and 1.3 blocking drug ICA121‐431. The efficacy and potency of these inhibitors were compared to the standard NaV1 blocker, tetrodotoxin. We then compared the relative potencies of the NaV1 blockers in inhibiting the C‐wave of the compound action potential, with their ability to inhibit parasympathetic cholinergic contraction of human isolated bronchi, a response previously shown to be strictly dependent on NaV1.7 channels.

Key Results

The selective NaV1.7 blockers inhibited the C‐wave of the compound action potential with potencies similar to that observed in the NaV1.7 bronchial contractions assay. Using rt‐PCR, we noted that NaV1.7 mRNA was strongly expressed and transported down the vagus nerve bundles.

Conclusions and Implications

NaV1.7 blockers can prevent action potential conduction in the majority of vagal C‐fibres arising from human bronchi. Blockers of NaV1.7 channels may therefore have value in inhibiting the responses to excessive airway C‐fibre activation in inflammatory airway disease, responses that include coughing as well as reflex bronchoconstriction and secretions.
Young children’s agency with digital technologies
Authors: Nolan Andrea , Edwards Susan , Salamon Andi , Straker Leon , Grieshaber Susan , Skouteris Helen , Henderson Michael , Highfield Kate , Bartlett Jacinta
Published: October 2021

This paper examines the evidence of children's agency in research about infants, toddlers and technologies. It finds that an implicit reliance on technological determinism as a theoretical perspective for positioning technologies relative to young children's development tends to shape research in terms of understanding the impact of technologies on young children. Drawing on critical constructivism as a philosophical stance on technologies, this paper argues that children's agency with technologies may be further investigated in terms of practice architectures to better understand the social mediation of infant and toddler interactions and engagements with technologies.
Preschoolers’ relevance inferences in linguistic and non‐linguistic contexts
Authors: Sullivan Jessica , Alvarez Joseph , Goldstein Blair
Published: October 2021

Understanding symbols requires going beyond what they literally are, and figuring out what they're intended to communicate. For example, a drawing of a bird (or the word bird) could refer to a particular bird, a species, etc… The interpreter must decide between these intended meanings. We ask how children go beyond the literal meanings of communicative acts (i.e., compute pragmatic inferences), and whether these inferences are domain‐general. We tested 443 US 2‐ to 6‐year‐olds’ inferences about the referential interpretation of ambiguous symbols. We manipulated the domain (e.g., word or a drawing) and task (interpret vs. create the communicative act). Children robustly identified the referents of ambiguous symbols and chose from among alternatives during linguistic and non‐linguistic communication tasks. There were no effects of age or domain on performance. These data provide some of the earliest evidence of children's computations of pragmatic inferences, and provide exciting evidence that pragmatic inferences may extend beyond the domain of language.
Fiber‐specific white matter analysis reflects upper motor neuron impairment in amyotrophic lateral sclerosis
Authors: Ogura Aya , Kawabata Kazuya , Watanabe Hirohisa , Choy Shao Wei , Bagarinao Epifanio , Kato Toshiyasu , Imai Kazunori , Masuda Michihito , Ohdake Reiko , Hara Kazuhiro , Nakamura Ryoichi , Atsuta Naoki , Nakamura Tomohiko , Katsuno Masahisa , Sobue Gen
Published: October 2021

Background and purpose

To clarify the relationship between fiber‐specific white matter changes in amyotrophic lateral sclerosis (ALS) and clinical signs of upper motor neuron (UMN) involvement, we performed a fixel‐based analysis (FBA), a novel framework for diffusion‐weighted imaging analysis.

Methods

We enrolled 96 participants, including 48 nonfamilial ALS patients and 48 age‐ and sex‐matched healthy controls (HCs), in this study and conducted whole‐brain FBA and voxel‐based morphometry analysis. We compared the fiber density (FD), fiber morphology (fiber cross‐section [FC]), and a combined index of FD and FC (FDC) between the ALS and HC groups. We performed a tract‐of‐interest analysis to extract FD values across the significant regions in the whole‐brain analysis. Then, we evaluated the associations between FD values and clinical variables.

Results

The bilateral corticospinal tracts (CSTs) and the corpus callosum (CC) showed reduced FD and FDC in ALS patients compared with HCs (p < 0.05, familywise error‐corrected), and the comparison of FCs revealed no region that was significantly different from another. Voxel‐based morphometry showed cortical volume reduction in the regions, including the primary motor area. Clinical scores showed correlations with FD values in the CSTs (UMN score: rho = −0.530, p < 0.001; central motor conduction time [CMCT] in the upper limb: rho = −0.474, p = 0.008; disease duration: rho = −0.383, p = 0.007; ALS Functional Rating Scale‐Revised: rho = 0.340, p = 0.018). In addition, patients whose CMCT was not calculated due to unevoked waves also showed FD reduction in the CSTs.

Conclusions

Our findings suggest that FD values in the CST estimated via FBA can be potentially used in evaluating UMN impairments.
Performing nationalism: The United Nations Human Rights Council (UNHRC) and Sri Lankan Tamil diasporic politics in Switzerland
Authors: Thurairajah Tanuja
Published: October 2021

The history of post‐war Sri Lanka has seen an escalation of nationalisms that constantly collide. Post‐2009, with the end of the war, the reproduction of narratives around nationalisms has become intense, with home‐grown protests for accountability of minority injustices continuing to sustain its fervour over time. Within the context of Switzerland these events in Sri Lanka are invariably aligned with diasporic engagement. Dominant spaces such as the United Nations (UN) in Geneva, Switzerland become transnational sites for the performance of long‐distance nationalism by Tamil diaspora groups, raising questions around legitimacy and claims‐making. This paper presents empirical insights as to how long‐distance Tamil nationalism is manifested as political engagement, by groups, and/ or individuals, in formal and informal transnational sites within the socio‐political landscape of Switzerland. It argues that modes of political engagement are manifested through rituals of performance and performativity such as scripting and iteration of claims‐making processes that enable legitimacy in transnational sites of lobby and protest within the UN arena in Geneva during the Human Rights Council (HRC) sessions. The paper situates its analysis within a shift in post‐war Tamil diaspora claims‐making narratives from a separatist stance to that of victimhood and human rights producing narratives that present the Tamil diaspora as a singular actor albeit with complex heterogeneity.
Cation exchange synthesis of porous Cd1‐xZnxS twinned nanosheets for visible light highly active H2 evolution
Authors: Wang Jing , Li Jiajia , Xiao Lu , Kurbanjan Dilnur , Nie Hong , Du Hong
Published: October 2021

Efficient charge separation is critical for the enhancement of photocatalytic activity for hydrogen generation. The porous Cd1‐xZnxS nanosheets with twinned phase junctions were synthesized by the cation‐exchange approach of inorganic‐organic hybrid ZnS‐diethylenetriamine nanoflakes with cadmium ions. With the synergy of the phase junctions induced by nano twins and porous structure, the hydrogen evolution average rate over the optimal sample Cd0.5Zn0.5S photocatalyst reaches 14.44 mmol h−1 g−1 without noble metal loading under visible light irradiation, corresponding to apparent quantum efficiency of 37.3% at 420 nm and solar‐to‐hydrogen energy conversion efficiency of 3.46%. On the one hand, twin‐induced phase junctions can improve the separation efficiency of photoelectron‐hole pairs, on the other hand, the large specific surface area ascribed to the porous nanosheet can effectively improve the light absorption capacity of photocatalysis, and provide more surface active sites. This study could provide a facile approach to design and fabricate advanced materials with porous twinned phase junctions for photocatalytic applications and optoelectronic devices.
Identification of pyroptosis‐related lncRNAs for constructing a prognostic model and their correlation with immune infiltration in breast cancer
Authors: Lv Wenchang , Tan Yufang , Zhao Chongru , Wang Yichen , Wu Min , Wu Yiping , Ren Yuping , Zhang Qi
Published: October 2021

The inflammasome‐dependent cell death, which is denoted as pyroptosis, might be abnormally regulated during oncogenesis and tumour progression. Long non‐coding RNAs (LncRNAs) are pivotal orchestrators in breast cancer (BC), which have the potential to be a biomarker for BC diagnosis and therapy. The present study aims to explore the correlation between pyroptosis‐related lncRNAs and BC prognosis. In this study, a profile of 8 differentially expressed lncRNAs was screened in the TCGA database and used to construct a prognostic model. The BC patients were divided into high‐ and low‐risk groups dependent on the median cutoff of the risk score in the model. Interestingly, the risk model significantly distinguished the clinical characteristics of BC patients between high‐ and low‐risk groups. Then, the risk score of the model was identified to be an excellent independent prognostic factor. Notably, the GO, KEGG, GSEA and ssGSEA analyses revealed the different immune statuses between the high‐ and low‐risk groups. Particularly, the 8 lncRNAs expressed differentially in BC tissues between two risk subgroups in vitro validation. Collectively, this constructed well‐validated model is of high effectiveness to predict the prognosis of BC, which will provide novel means that is applicable for BC prognosis recognition.
Comparative transcriptomic analysis of THP‐1‐derived macrophages infected with Mycobacterium tuberculosis H37Rv, H37Ra and BCG
Authors: Pu Wenyuan , Zhao Chen , Wazir Junaid , Su Zhonglan , Niu Mengyuan , Song Shiyu , Wei Lulu , Li Li , Zhang Xia , Shi Xudong , Wang Hongwei
Published: October 2021

Tuberculosis (TB) remains a worldwide healthcare concern, and the exploration of the host‐pathogen interaction is essential to develop therapeutic modalities and strategies to control Mycobacterium tuberculosis (M.tb). In this study, RNA sequencing (transcriptome sequencing) was employed to investigate the global transcriptome changes in the macrophages during the different strains of M.tb infection. THP‐1 cells derived from macrophages were exposed to the virulent M.tb strain H37Rv (Rv) or the avirulent M.tb strain H37Ra (Ra), and the M.tb BCG vaccine strain was used as a control. The cDNA libraries were prepared from M.tb‐infected macrophages and then sequenced. To assess the transcriptional differences between the expressed genes, the bioinformatics analysis was performed using a standard pipeline of quality control, reference mapping, differential expression analysis, protein‐protein interaction (PPI) networks, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Q‐PCR and Western blot assays were also performed to validate the data. Our findings indicated that, when compared to BCG or M.tb H37Ra infection, the transcriptome analysis identified 66 differentially expressed genes in the M.tb H37Rv‐infected macrophages, out of which 36 genes were up‐regulated, and 30 genes were down‐regulated. The up‐regulated genes were associated with immune response regulation, chemokine secretion, and leucocyte chemotaxis. In contrast, the down‐regulated genes were associated with amino acid biosynthetic and energy metabolism, connective tissue development and extracellular matrix organization. The Q‐PCR and Western blot assays confirmed increased expression of pro‐inflammatory factors, altered energy metabolic processes, enhanced activation of pro‐inflammatory signalling pathways and increased pyroptosis in H37Rv‐infected macrophage. Overall, our RNA sequencing‐based transcriptome study successfully identified a comprehensive, in‐depth gene expression/regulation profile in M.tb‐infected macrophages. The results demonstrated that virulent M.tb strain H37Rv infection triggers a more severe inflammatory immune response associated with increased tissue damage, which helps in understanding the host‐pathogen interaction dynamics and pathogenesis features in different strains of M.tb infection.
Impaired reproductive fitness despite high fecundity in European eel (Anguilla anguilla L.) from a Baltic Sea drainage area
Authors: Reismann Theresa , Frankowski Jens
Published: October 2021

The reproductive fitness of female European eels (Anguilla anguilla L.) from the Warnow River, Germany, Baltic Sea region, was evaluated by estimating fecundity and applying a spawning model. Individual fecundity ranged from 1,440,000 to 7,455,000 oocytes and mean relative fecundity equalled 5,956,015 oocytes kg−1. Modelling suggests that 43% of eels hold insufficient energy storages or are within 10% of complete depletion. The fraction of eels with insufficient energy supply increases from 19% to 35% if the effect of parasitic infection is considered.
Differential hyperpolarization to substance P and calcitonin gene‐related peptide in smooth muscle versus endothelium of mouse mesenteric artery
Authors: Norton Charles E. , Boerman Erika M. , Segal Steven S.
Published: October 2021

Objective

We sought to define how sensory neurotransmitters substance P and calcitonin gene‐related peptide (CGRP) affect membrane potential of vascular smooth muscle and endothelium.

Methods

Microelectrodes recorded membrane potential of smooth muscle from pressurized mouse mesenteric arteries (diameter, ~150 µm) and in endothelial tubes.

Results

Resting potential was similar (~ −45 mV) for each cell layer. Substance P hyperpolarized smooth muscle and endothelium ~ −15 mV; smooth muscle hyperpolarization was abolished by endothelial disruption or NO synthase inhibition. Blocking KCa channels (apamin + charybdotoxin) attenuated hyperpolarization in both cell types. CGRP hyperpolarized endothelium and smooth muscle ~ −30 mV; smooth muscle hyperpolarization was independent of endothelium. Blocking KCa channels prevented hyperpolarization to CGRP in endothelium but not smooth muscle. Inhibiting KATP channels with glibenclamide or genetic deletion of KIR6.1 attenuated hyperpolarization in smooth muscle but not endothelium. Pinacidil (KATP channel agonist) hyperpolarized smooth muscle more than endothelium (~ −35 vs. ~ −20 mV).

Conclusions

Calcitonin gene‐related peptide elicits greater hyperpolarization than substance P. Substance P hyperpolarizes both cell layers through KCa channels and involves endothelium‐derived NO in smooth muscle. Endothelial hyperpolarization to CGRP requires KCa channels, while KATP channels mediate hyperpolarization in smooth muscle. Differential K+ channel activation in smooth muscle and endothelium through sensory neurotransmission may selectively tune mesenteric blood flow.
Phytoglobin‐NO cycle and AOX pathway play a role in anaerobic germination and growth of deepwater rice
Authors: Kumari Aprajita , Singh Pooja , Kaladhar Vemula Chandra , Manbir  , Paul Debarati , Pathak Pradeep Kumar , Gupta Kapuganti Jagadis
Published: October 2021

An important and interesting feature of rice is that it can germinate under anoxic conditions. Though several biochemical adaptive mechanisms play an important role in the anaerobic germination of rice but the role of phytoglobin‐nitric oxide cycle and alternative oxidase pathway is not known, therefore in this study we investigated the role of these pathways in anaerobic germination. Under anoxic conditions, deepwater rice germinated much higher and rapidly than aerobic condition and the anaerobic germination and growth were much higher in the presence of nitrite. The addition of nitrite stimulated NR activity and NO production. Important components of phytoglobin‐NO cycle such as methaemoglobin reductase activity, expression of Phytoglobin1, NIA1 were elevated under anaerobic conditions in the presence of nitrite. The operation of phytoglobin‐NO cycle also enhanced anaerobic ATP generation, LDH, ADH activities and in parallel ethylene levels were also enhanced. Interestingly nitrite suppressed the ROS production and lipid peroxidation. The reduction of ROS was accompanied by enhanced expression of mitochondrial alternative oxidase protein and its capacity. Application of AOX inhibitor SHAM inhibited the anoxic growth mediated by nitrite. In addition, nitrite improved the submergence tolerance of seedlings. Our study revealed that nitrite driven phytoglobin‐NO cycle and AOX are crucial players in anaerobic germination and growth of deepwater rice.
Molecular characterization of biphenotypic epithelioid and plexiform melanoma with deep penetrating nevus‐like features
Authors: Giubellino Alessio , Nelson Andrew C. , He Yuyu , Munro Sarah A. , Song Kyu Young , Glitza Oliva Isabella C. , Torres‐Cabala Carlos
Published: October 2021

Tumor heterogeneity is a relevant hallmark of melanoma due to the high mutation burden and immunogenicity commonly encountered. Heterogeneity at the histologic level frequently corresponds to heterogeneity at the molecular level. A better understanding of this feature of malignancy can help refine the development of predictive biomarkers and to define more effective targeted therapies. Here, we describe a case of melanoma displaying a dual phenotype: a DPN‐like/plexiform portion in conjunction with a conventional epithelioid morphology. Molecular studies revealed shared BRAF and PTEN mutations in both components but a CTNNB1 mutation was exclusively found in the DPN‐like area of the tumor, consistent with the distinct morphology observed. There was considerable heterogeneity in sequence variants identified in the two regions. Gene expression analysis highlighted differentially regulated genes between the two histologies, including a relevant cluster of genes in the receptor tyrosine kinase (RTK) family and related signaling pathways upregulated in the DPN‐like/plexiform area.
Business and human rights implications of climate change litigation: Milieudefensie et al. v Royal Dutch Shell
Authors: Macchi Chiara , van Zeben Josephine
Published: October 2021

In Milieudefensie et al. v Royal Dutch Shell, the District Court in the Hague ordered the respondent company to cut its global carbon dioxide emissions by 45 percent by 2030, as compared with 2019 levels. The landmark judgement represents the first imposition of a specific mitigation obligation on a private company over and above reduction targets set by existing ‘cap‐and‐trade’ regulations and/or other governmental mitigation policies. In interpreting Royal Dutch Shell's duty of care under Dutch tort law, the Court referred extensively to international soft law, including the United Nations Guiding Principles on Business and Human Rights. This note considers the implications of this case for corporate responsibility for environmental and human rights.
Identification of the novel HLA‐C*03:03:01:52N allele, a splice‐site variant at the boundary of intron1 and exon2
Authors: Ulrich Silvia , Lang Johanna , Bodem Oliver , Posch Ursula , Schlenke Peter
Published: October 2021

HLA‐C*03:03:01:52N differs from HLA‐C*03:03:01:01 by one nucleotide substitution at position gDNA 202 (A>G) in Intron1.
Legal geographies of medication abortion in the USA
Authors: Calkin Sydney
Published: October 2021

Medication abortion with pills (mifepristone and misoprostol) challenges the spatiality of abortion provision because it creates the possibility for safe, self‐managed abortion outside of clinical infrastructure. This possibility has been contested by pro‐ and anti‐abortion actors for as long as medication abortion has been in existence. In this paper, I offer a legal geography account of medication abortion technology that examines how medication abortion has been regulated in the United States. Conceptually, the paper uses a legal geography methodology to probe the social spatialities that abortion laws construct. Empirically, the paper analyses trends in legislation to restrict medication abortion and two significant court challenges where abortion providers brought suit against medication abortion restrictions. Drawing on legislation and litigation over mifepristone, I demonstrate that restrictions on it function by anchoring mifepristone inside the clinical spaces and regulatory frameworks established for surgical abortion. In this way, mifepristone regulations circumscribe its availability in order to prevent the creation of alternative models for abortion provision that could re‐arrange its geography and expand abortion access.
Dos mujeres frente a la totalidad del universo: sor Juana Inés de la Cruz y sor María de Jesús de Ágreda
Authors: Gutiérrez Reyna Jorge
Published: October 2021

El presente artículo busca llamar la atención sobre la notoria influencia que la obra de la monja española sor María de Jesús de Ágreda (1602-1665) ejerció sobre la de sor Juana Inés de la Cruz (1648-1695), sobre todo en su Primero sueño. A través de la obra de sor María, en particular su Mística Ciudad de Dios, puede establecerse un vínculo entre la obra maestra de la jerónima y uno de los que podemos considerar como uno de sus escritos menores y menos conocidos: los Ejercicios de la Encarnación. En los textos anteriores hay un elemento en común: el alma de una mujer se ve favorecida por una visión de la totalidad.
El estilo de la crítica literaria en La máscara, la transparencia
Authors: Antzus Ramos Ioannis
Published: October 2021

En este artículo estudiamos el estilo de la crítica literaria en La máscara, la transparencia (1975), la gran obra ensayística de Guillermo Sucre (Venezuela, 1933). Para llevar a cabo este análisis partimos de su propia concepción de la crítica y nos centramos en dos aspectos fundamentales: 1) la dialéctica entre el movimiento y la fijeza, y el intento de convertir el texto crítico en un absoluto verbal, y 2) la conciencia de que está tratando con palabras (y no con cosas), lo que da lugar a una actitud de pasión y de crítica con respecto a la propia escritura. Ponemos así de manifiesto cómo los postulados críticos de los que parte el autor permean su propia escritura ensayística.
Dual Fluorescence Emission by Irradiation of Single Optical Source for Fluorescein Sodium and 5-ALA Applications
Authors: Kwon So Yoon , Yoon Ki-Cheol , Kim Kwang Gi
Published: October 2021

Most brain surgeries aim to completely resection a tumor. However, the arrangement of blood vessels around brain tumors is often complex. Moreover, the tumors and blood vessels have similar colors, making it difficult to identify the boundaries between them with the naked eye. Fluorescent staining is a method used to distinguish the borders between brain tumors and blood vessels. The fluorescent contrast agents commonly used to observe tumors are 5-aminolevulinic acid and fluorescein sodium, which have different surgical sensitivities, depending on the type of tumor. In this article, a dual band bandpass filter with dual-wavelength emission for 5-aminolevulinic acid and fluorescein sodium is designed, and the dual-band bandpass filter capable of inducing simultaneous fluorescence emission of fluorescein sodium and 5-aminolevulinic acid was investigated experimentally to improve accuracy, speed, and energy efficiency in clinical settings. The possibility of dual fluorescence emission with a single irradiation is proposed. The efficiency of transmission and reflection (optical density) is 98% and 0.01%, respectively, and the bandwidth is 50% in the proposed filter. The proposed fluorescent dual-band filter has the advantage of saving energy, reducing auxiliary manpower and unit costs, and reducing operating room space requirements by producing two fluorescence diagnostic effects using a single equipment.
Importance of Three-Dimensional Vehicle Heat Exchanger Modeling
Authors: Schmid Michal , Paščenko Petr , Bozkurt Fatih , Petržela Pavel
Published: October 2021

This article demonstrates, via a comprehensive study, the necessity of using a 3D computational fluid dynamics (CFD) approach for heat exchanger (HTX) modeling within underhood vehicle simulation. The results are presented as the difference between 1D and 3D CFD approaches with a focus on auxiliary fluid (e.g., coolant) temperature prediction as a function of primary fluid (e.g., air) inlet conditions. It has been shown that the 1D approach could significantly underpredict auxiliary fluid inlet temperature due to neglecting the spatial distribution of primary fluid velocity magnitude. The resultant difference in the auxiliary fluid flow HTX inlet temperature is presented and discussed as a function of the uniformity index (UI) of the primary fluid flow velocity magnitude. In addition, the 3D HTX model’s importance is demonstrated in an industrial example of full 3D underhood simulation.
A Simulation Study on the Effect of Particle Size Distribution on the Printed Geometry in Selective Laser Melting
Authors: Sagar Vaishak Ramesh , Lorin Samuel , Göhl Johan , Quist Johannes , Jareteg Klas , Cromvik Christoffer , Mark Andreas , Edelvik Fredrik , Wärmefjord Kristina , Söderberg Rikard
Published: October 2021

Selective laser melting (SLM) process is a powder bed fusion additive manufacturing process that finds applications in aerospace and medical industries for its ability to produce complex geometry parts. As the raw material used is in the powder form, particle size distribution (PSD) is a significant characteristic that influences the build quality in turn affecting the functionality and esthetic aspects of the product. This article investigates the effect of PSD on the printed geometry for 316L stainless steel pow der, where three coupled in-house simulation tools based on discrete element method (DEM), computational fluid dynamics (CFD), and structural mechanics are employed. DEM is used for simulating the powder bed distribution based on the different powder PSD. The CFD is used as a virtual testbed to determine thermal parameters such as heat capacity and thermal conductivity of the powder bed viewed as a continuum. The values found as a stochastic function of the powder distribution are used to analyze the effect on the melted zone and deformation using structural mechanics. Results showed that mean particle size and PSD had a significant effect on the packing density, melt pool layer thickness, and the final layer thickness after deformation. Specifically, a narrow particle size distribution with smaller mean particle size and standard deviation produced solidified final layer thickness closest to nominal layer thickness. The proposed simulation approach and the results will catalyze the development of geometry assurance strategies to minimize the effect of particle size distribution on the geometric quality of the printed part.
Bayesian Experimental Design of Cyber-Physical Tests for Hydrodynamic Model Calibration
Authors: Abbiati Giuseppe , Sauder Thomas
Published: October 2021

An application of cyber-physical testing to the empirical estimation of difference-frequency quadratic transfer functions is presented. As an alternative to today’s procedure based on hydrodynamic tests with broad-banded or realistic (e.g., JONSWAP) wave spectra, tests in bichromatic waves are considered. The laboratory setup is the one developed by Sauder & Tahchiev (2020) that enables magnifying the sensitivity of the floater response to the low-frequency wave loading by adjusting the stiffness and damping parameters of a virtual soft mooring system. Bayesian experimental design is proposed to optimize the selection of the control variables (frequencies in the bichromatic wave and properties of the virtual mooring system) for a batch of cyber-physical tests. The experimental design algorithm is based on the recent work of Huan & Marzouk (2013). In a virtual yet realistic case study using an uncertain parametric quadratic transfer function, we demonstrate how the uncertainty of its describing parameters and other calibration parameters (low-frequency added mass and hydrodynamic damping) can be reduced. Results indicate that the proposed procedure has the potential for reducing experimental cost for calibration of hydrodynamic models.
Application of the Quemada Viscosity Model for Drilling Fluids
Authors: Knutsen Sandra , Cayeux Eric , Saasen Arild , Khalifeh Mahmoud
Published: October 2021

A number of different models are used to describe the shear rate dependent viscosity of drilling fluids. Most, such as the Herschel-Bulkley model, have a purely empirical basis. The Quemada model, while still empirical, is based on physical principles. It is based on the notion that structural units develop in the fluid at low shear rates which are then partially broken down as the applied shear rate increases.

In the current work, drilling fluid rheological data are fitted to the Herschel-Bulkley and the Quemada model. The development of the Quemada model and the calculation of each model parameter are presented. We show that the Quemada model better fits measurements over a wider range of shear rates than the Herschel-Bulkley model. We describe how to select the parameters of the Quemada model. Knowing the difficulty of obtaining a known shear rate for fluids with yield stresses, we discuss how this can affect the quality of the Quemada model fit. Furthermore, in principle, the Quemada model is not applicable in presence a non-zero yield stress. Therefore, we show how to handle the yield stress using a (very high) zero shear rate viscosity.
An Optimization Based Approach for Damage Identification of Idealized Ship Structural Assemblies
Authors: Silionis Nicholas E. , Anyfantis Konstantinos N.
Published: October 2021

Damage identification in ship structures is traditionally performed through on-site inspections. In this work, a first step is made towards assessing an in-line with operation ship hull Structural Health Monitoring system by registering onboard sensor data. Specifically, an optimization-based approach is proposed for solving the inverse problem for damage identification through processing static response data. Idealized geometry and loading conditions are considered for the deck and shell plating. Damage is abstractly represented as a single circular hole randomly located within the defined domain. Strain readings representing onboard measured data are provided by a FE model developed for this purpose. These correspond to zero-strain paths for each considered case: axial strains along the ship’s neutral axis on the side shells and shear strains along the deck’s centerline. Damage detection amounts to predicting its location, essentially considered the design variable of an optimization problem seeking to minimize an error function between strains measured for various damage scenarios and an indicative target scenario. Three established optimization algorithms are used for this task: a gradient-based, a Genetic Algorithm-based and a statistics-based method (Design of Experiments and Response Surface Methodology). Results indicate that the gradient and GA based approaches are more efficient while the less efficient statistics-based approach proved less computationally demanding.
Mechatronic Design and Maneuverability Analysis of a Novel Robotic Shark for Coral Reef Detection
Authors: Gao Liyang , Li Peng , Qin Hongde , Deng Zhongchao
Published: October 2021

In this paper, mechatronic design of a novel robotic shark for coral reef detection is presented. To obtain good maneuverability, a barycenter regulating device is designed to assist the posture adjustment of the robotic shark at low speed. Based on STAR-CCM+ software, the lift coefficients and drag coefficients of pectoral fin are calculated using overlapping grid technique. Based on Newton-Euler approach, a dynamic model with particular consideration of pectoral fins for three-dimensional motion is established. A CPG controller is used to generate rhythmic motion of each joint. Furthermore, based on the dynamic model, three-dimensional trajectory of spiral motion and swimming speed in different oscillation parameters are simulated. The results show that swimming speed of the robotic shark can be improved by increasing the amplitude and frequency or decreasing the phase difference. Also, oscillation frequency plays a more significant role. Furthermore, under the action of single pectoral fin, the robotic shark can achieve spiral motion and the turning radius is about 35.8m under the parameters set in this article.
Effect of Air Fraction on Force Coefficients in Oscillatory Flow
Authors: Vested Malene Hovgaard , Christensen Erik Damgaard
Published: October 2021

The forces on marine and offshore structures are often affected by spilling breakers. The spilling breaker is characterized by a roller of mixed air and water with a forward speed approximately equal to the wave celerity. This high speed in the top of the wave has the potential to induce high wave loads on upper parts of the structures. This study analyzed the effect of the air content on the forces. The analyses used the Morison equation to examine the effect of the percentage of air on the forces. An experimental set-up was developed to include the injection of air into an otherwise calm water body. The air-injection did introduce a high level a turbulence. It was possible to assess the amount of air content in the water for different amounts of air-injection. In the mixture of air and water the force on an oscillating square cylinder was measured for different levels of air-content, — also in the case without air. The measurements indicated that force coefficients for clear water could be use in the Morison equation as long as the density for water was replaced by the density for the mixture of air and water.
Cuttings Transport With Oil- and Water-Based Drilling Fluids
Authors: Ytrehus Jan David , Lund Bjørnar , Taghipour Ali , Saasen Arild
Published: October 2021

Deviated well sections are common in modern well construction. In mature areas like the North Sea region, practically all producers or injector wells will have highly deviated sections. These wells must be drilled and completed in an optimal manner with respect to drill time, cost, risk and functionality. Most cuttings transport and hydraulic models are developed based on tests with model fluids and often in small diameter test sections. Hole cleaning properties and hydraulic behaviour of field fluids differ from those of most model fluids. Furthermore, results from small diameter tests may not always be relevant for, nor scalable to, field applications due to time, length and other scale differences. Hence, there is a need for studies in controlled laboratory environments with various field application designed drilling fluids to improve engineering models and practices.

This paper presents results from laboratory tests using field applied fluids. The drilling fluids have similar density and viscosity within the relevant shear rate range applied during drilling operations and in the tests. One of the fluids is oil-based and the other one is an inhibitive water-based drilling fluid.
Effect of Bilge Radius and Bilge Keel Height on Roll Damping Performance of Floating Structures
Authors: Kwon Chang Seop , Kim Joo-Sung , Kim Hyun Joe
Published: October 2021

A round bilge with a bilge keel structure is a key element which can alleviate roll motions of ships and floating structures by transferring the roll momentum of a floating body into the kinetic energy of water. This study presents a practical guide to properly designing a bilge radius and bilge keel height of a barge-shaped and tanker-shaped FPSOs. A parametric study to figure out the effect of bilge radius and bilge keel height on the roll damping performance is conducted through a series of numerical roll free decay simulations based on Computational Fluid Dynamics (CFD). The bilge radius is normalized by the half breadth of ship, and the bilge keel height is normalized by the maximum bilge keel height which is limited by the molded lines of a side shell and bottom shell. In addition, it is investigated to identify how the roll damping performance of a rectangular section differs from the result of a typical round bilge section with maximum available bilge keel height.
Large-Eddy Simulation of Flow Past a Circular Cylinder Using OpenFOAM and Nektar++
Authors: Jiang Hongyi , Ju Xiaoying , Lu Yucen
Published: October 2021

Steady incoming flow past a circular cylinder has been a classical problem in fluid mechanics owing to its extensive practical applications in e.g. offshore engineering. In this study, large-eddy simulations are performed for flow past a circular cylinder at the Reynolds number (Re) of 3900. Particular focuses are on the comparisons of different numerical methods and computational domain patterns. The case Re = 3900 is computed with both OpenFOAM and Nektar++, which are based on the conventional finite volume method and the highorder spectral/hp element method, respectively. It is found that the computational cost for the Nektar++ model is only less than 10% of that for the OpenFOAM model. In addition, both circular and C-shaped domains are tested for the OpenFOAM and Nektar++ models. It is found that a circular domain is required for the OpenFOAM model to minimise the footprint of mesh non-orthogonality on the simulated flow, while the Nektar++ model does not have strict requirements for the orthogonality of the mesh. The present findings regarding the computational cost and the domain/mesh patterns are expected to be applicable to the numerical modelling of bluff-body flows in general. Based on Nektar++ and the circular domain, additional simulations are performed at Re = 1000 and 7000. For the three Re values investigated, the Strouhal number, hydrodynamic forces and the streamwise and spanwise vorticity fields are examined and compared.
Sea Trials Summarization on Fundamental Formation Control of Multiple Cruising AUVs
Authors: Fujiwara Toshifumi , Kim Kangsoo , Sasano Masahiko , Sato Takumi , Inaba Shogo , Okamoto Akihiro , Imasato Motonobu , Osawa Hiroyuki
Published: October 2021

In the 2nd term SIP project (SIP2), “Innovative Technology for Exploration of Deep Sea Resources” in Japan, National Maritime Research Institute, NMRI, is promoting the AUVs control system construction initiatively together with the leading agency, Japan Agency for Marine-Earth Science and Technology, JAMSTEC. To promote future high-level formation control, two types of fundamental formation control tests were tried using two AUVs and one ASV in the sea. One of them is virtual leader-follower control, and the other is centralized AUV control by one ASV. Seafloor topography mapping at the coast in Japan was successfully conducted by the two control methods with AUVs as test trials.

In this paper, the results of the fundamental formation control tests of them are reported and summarized. Detailed consideration of the test results is represented using a simple simulation of AUVs in the latter half of this paper. Moreover, the plan for the promotion of the formation control system that will be done in near future is introduced.
Evaluation of Cumulative Collapse of a LNG Carrier Hull Girder Under Dynamic Cyclic Bending Moments
Authors: Ji Jian , Liu Bin , Chen Lin , Liao Xianting , Guedes Soares C.
Published: October 2021

The present paper continues the recent work reported by Liu and Guedes Soares [1] where finite element simulations were conducted to investigate the ultimate strength of a container ship hull girder under cyclic bending moments. Here a membrane LNG carrier is investigated to evaluate the “cyclic ultimate strength” of this specialized ship hull structure including double bottoms, sides and decks. The paper aims to analyze the ultimate strength and to compare the collapse modes of a LNG carrier hull girder under monotonic and dynamic cyclic bending moments, revealing the difference in their failure modes. Nonlinear finite element method is employed, using the explicit LS-DYNA solver, to analyze the ultimate strength of hull structures. The numerical results show that the cyclic ultimate strength of hull structures is about 20% lower than the monotonic ultimate strength in the present study.
Ship Collision Analysis of Double Hull Structures in Various Ship Types
Authors: Chen Jie , Liu Bin , Villavicencio R. , Ji Jian , Guedes Soares C.
Published: October 2021

This paper elaborates the impact characteristics of double hull structures in various ship types including bulk carrier, container ship, LNG carrier and oil tanker. Their own structural configurations, such as the strengthened topside tank in the container ship, affect the crashworthiness of double hull structures in ship collisions. Two striking bows are modeled so as to evaluate the crashworthiness of the double hull structures. The calculations are performed using LS-DYNA to assess the impact characteristics of four struck ships. The ship collision analysis also discusses the assumption of rigid bow in conventional analysis and its effect on the evaluation of side structural crashworthiness. The numerical force-displacement responses and absorbed energy-displacement curves of various ships are compared. The comparison aims to reveal the discrepancy of the crashworthiness of the four typical double hull structures. It is of importance to analyze their structural characteristics for the design of crashworthy structures.
A Low-Cost Modular Image-Based Approach to Characterize Large-Field Wave Shapes in Glass Wave Flume
Authors: Fu Shuangjiu , Vronsky Michael , Alam Mohammad-Reza
Published: October 2021

Accurately determining water surface elevation and wave shapes in the hydraulic laboratory is critical for experimental research and physical understanding of ocean waves. Existing technologies such as wave gauges cannot capture the continuous wave profile across both space and time. This poses an issue, as nonlinear wave characteristics vary as a function of position and cannot be fully described using such point measurements. Furthermore, wave gauges are intrusive to the flow field. Alternative single-camera methods can’t capture wave characteristics in a large field-of-view properly without sacrificing resolution. In this paper, the authors propose an easy-to-use, low-cost method for measuring wave height and shape along the length of the flume over time. The method utilizes stitching of multiple web-cameras and the application of a Canny-based edge detection algorithm with experimentally determined thresholds and additional filters for maximum robustness and efficacy. Additionally, distortion correction is implemented in a computationally efficient manner. Video is acquired by three Logitech C920 PRO HD cameras recording at a resolution of 1280 × 720 at 24fps. The wave generator can generate waves with frequency between 0.1Hz and 1Hz. The experimental results show that wave height measurements can be obtained with a maximum resolution of 0.83mm with a relative error of ±1.5% when compared with a reference wave gauge measurement. This work demonstrates the ability to arbitrarily extend the horizontal field-of-view while providing more accurate measurement results.
Model-Inversion Feedforward Control for Wave Load Reduction in Floating Wind Turbines
Authors: Fontanella Alessandro , Belloli Marco
Published: October 2021

This paper develops a novel feedforward control strategy for reducing structural loads caused by waves in floating offshore wind turbines. The proposed control strategy is based on the inversion of a linear model of the floating wind turbine, and a real-time forecast of the wave obtained from an upstream measurement is utilized to compute a collective pitch control action. Two feedforward controllers are considered: one is designed to cancel the rotor speed oscillations and one to lower the towertop fore-aft shear force. The feedforward control strategies are implemented in a 10MW floating wind turbine, complementing the standard feedback controller for generator speed regulation. Numerical simulations are carried out in FAST, in four operating conditions with realistic wind and waves, proving the proposed feedforward controller effectively mitigates the structural loads caused by waves. In detail, the feedforward action reduces the loads spectra in the frequency range where linear wave is active. The best performance is realized higher winds (the FA force is reduced up to 25% in 22 m/s wind), where the wave excitation is the strongest.