bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of Na+ channel clusters in narrowed perinexi of gap junctions enhances cardiac impulse transmission via ephaptic coupling: a model study
Authors: Ivanovic Ena , Kucera Jan P. 
Published: September 2021

AbstractIt has been proposed that when gap junctional coupling is reduced in cardiac tissue, action potential propagation can be supported via ephaptic coupling, a mechanism mediated by negative electric potentials occurring in narrow intercellular clefts of intercalated discs (IDs). Recent studies showed that sodium (Na+) channels form clusters near gap junction plaques in nanodomains called perinexi, where the ID cleft is even narrower. To examine the electrophysiological relevance of Na+ channel clusters being located in perinexi, we developed a 3D finite element model of two longitudinally abutting cardiomyocytes, with a central Na+ channel cluster on the ID membranes. When this cluster was located in the perinexus of a closely positioned gap junction plaque, varying perinexal width greatly modulated impulse transmission from one cell to the other, with narrow perinexi potentiating ephaptic coupling. This modulation occurred via the interplay of Na+ currents, extracellular potentials in the cleft and patterns of current flow within the cleft. In contrast, when the Na+ channel cluster was located remotely from the gap junction plaque, this modulation by perinexus width largely disappeared. Interestingly, the Na+ current in the ID membrane of the pre‐junctional cell switched from inward to outward during excitation, thus contributing ions to the activating channels on the post‐junctional ID membrane. In conclusion, these results indicate that the localization of Na+ channel clusters in the perinexi of gap junction plaques is crucial for ephaptic coupling, which is furthermore greatly modulated by perinexal width. These findings are relevant for a comprehensive understanding of cardiac excitation.Key points
Ephaptic coupling is a cardiac conduction mechanism involving nanoscale‐level interactions between the sodium (Na+) current and the extracellular potential in narrow intercalated disc clefts.
When gap junctional coupling is reduced, ephaptic coupling acts in conjunction with the classical cardiac conduction mechanism based on gap junctional current flow.
In intercalated discs, Na+ channels form clusters that are preferentially located in the periphery of gap junction plaques, in nanodomains known as perinexi, but the electrophysiological role of these perinexi has never been examined.
In our new 3D finite element model of two cardiac cells abutting each other with their intercalated discs, a Na+ channel cluster located inside a narrowed perinexus facilitated impulse transmission via ephaptic coupling.
Our simulations demonstrate the role of narrowed perinexi as privileged sites for ephaptic coupling in pathological situations when gap junctional coupling is decreased.
Improvement of Probabilistic Fracture Mechanics Analysis Code PASCAL-SP Regarding Stress Corrosion Cracking in Nickel Based Alloy Weld Joint of Piping System in Boiling Water Reactor
Authors: Mano Akihiro , Yamaguchi Yoshihito , Katsuyama Jinya , Li Yinsheng 
Published: September 2021

Abstract
In the past few decades, cracks because of stress corrosion cracking (SCC) have been detected in the dissimilar weld joints using nickel-based alloy in piping system of boiling water reactors (BWRs). Thus, the structural integrity assessment for such weld joints has become important. Nowadays, probabilistic fracture mechanics (PFM) analysis is recognized as a rational method for structural integrity assessment because it can consider inherent uncertainties of various influencing factors as probability distributions and quantitatively evaluate the failure probability of a cracked component. The Japan Atomic Energy Agency has developed a PFM analysis code PASCAL-SP for a weld joint of piping system in nuclear power plant. This study improves the analysis functions of PASCAL-SP for weld joint using nickel-based alloy in BWR susceptible to SCC. As an analysis example of the improved version of PASCAL-SP, the failure probability of a weld joint is quantitatively evaluated. Furthermore, sensitivity analyses are conducted concerning the effect of leak detection and in-service inspection. From the analysis results, it is concluded that the improved version of PASCAL-SP is useful for structural integrity assessment.
Evaluation of the Creep Rupture Behavior of Alloy 690 Steam Generator Tubes Considering the Pressure Ramp Rate
Authors: Kim Jong-Min , Kim Min-Chul , Kwon Joon-Yeop 
Published: September 2021

Abstract
Steam generator tubes are among the main components that form the pressure boundary of a nuclear power plant and studies of ruptures of steam generator (SG) tubes are important because they can ensure the safety of a nuclear power plant in case of a severe accident. The materials used previously for SG tubes around the world have been replaced and will be replaced by Alloy 690 given its improved corrosion resistance relative to that of Alloy 600. However, studies of the high-temperature creep and creep-rupture characteristics of SG tubes made of Alloy 690 are insufficient compared to those focusing on Alloy 600. In this study, several creep tests were conducted using half-tube shape specimens of the Alloy 690 material at temperatures ranging from 650 °C to 850 °C and stresses in the range of 30–350 MPa, with failure times to creep rupture ranging from 3 h to 870 h. Based on the creep test results, creep life predictions were then made using the well-known Larson–Miller parameter (LMP) method. Steam generator tube rupture tests were also conducted under the conditions of a constant temperature and pressure ramp using SG tube specimens. As the pressure ramp rate increases, the failure behavior changes due to the rapid change in strain near the crack tip. The rupture test equipment was designed and manufactured to simulate the transient state (rapid temperature and pressure changes) in the event of a severe accident condition. After the rupture test, the damage to the SG tubes was predicted using a creep rupture model and a flow stress model. A modified creep rupture model for Alloy 690 SG tube material is proposed based on the experimental results. A correction factor of 1.7 in the modified creep rupture model was derived for the Alloy 690 material. The predicted failure pressure was in good agreement with the experimental failure pressure.
Pneumatic Testing of Piping Assemblies: Criteria for Stored Energy and Pinhole Leak Detectability
Authors: Botros K. K. , Liu V. , Lu J. 
Published: September 2021

Abstract
Pneumatic testing is beneficial as an alternative to hydrotesting particularly in remote areas where access to hydrotest fluids becomes logistically difficult or impossible. In some cases, above-ground pipe supports cannot hold the water weight, or that the pipe is coated/lined with materials that would degrade with water/methanol/glycol mixtures, or the system cannot be fully dried and the remaining hydrotest fluids are detrimental to the service application once the system is commissioned. Additionally, the elevation profile of the piping is such that an excessive number of test sections would be required for hydrotesting according to most codes. The present work is aimed at addressing two salient questions often faced with pneumatic testing. The first is related to the appropriate piping volume to consider for calculating the stored energy in use with ASME Post Construction Committee (PCC)-2 calculation for determining the safe exclusion distance for a given piping geometry and test conditions. It was found that the 8D criteria specified in ASME PCC-2 cannot be generalized for all pipe sizes, different material toughness, grades, wall thicknesses, and test conditions. A criterion is developed based on the ductile fracture arrest length that considers all these factors combined. The second criterion is related to the ability to detect a pinhole leak from the pneumatic test data, again for a given geometry and test conditions, and what constitutes the minimum pinhole effective area in relation to the system total volume, measured uncertainties in the test pressure and temperature over the duration of the test. A seminormalized physics-based parameter is suggested that can be applied to determine the effective pinhole leak size. The methodology is applied to a pneumatic field test on DN200, 12.2 km pipeline lateral.
Experimental Study on Horizontal Fire Spread Characteristics of Transformer Oil
Authors: Li Liyang , GUO Xincheng , Lu Rongsheng , Chen Peng , Shi Congling 
Published: September 2021

Abstract
In order to study the horizontal fire spread characteristics of transformer oil, a series of experiments were carried out on the experimental platform developed, the influence of the initial temperature and the width of the oil pool on the flame propagation, including the propagation speed, flame morphology and the temperature field distribution of the gas-liquid two-phase, was analyzed to reveal the flame propagation characteristics and the oil surface temperature rise law in the process of transformer oil fire propagation, and a theoretical model of coupled liquid-phase convective heat transfer and flame radiation heat transfer was established by combining thermodynamic theory to quantitatively calculate the heat transfer process of surface flow in flame propagation process. Through the theoretical analysis and quantitative calculation of gas-liquid heat transfer, it is proved that the surface flow is mainly driven by surface tension and the flame spreads in the form of pulsation. Combined with the experimental data for verification, it is found that the proportion of liquid-phase convective heat transfer to the total heat flow is much larger than that of flame radiation to the total heat flow, which proves that liquid-phase convective heat transfer is the main mode of surface flow heat transfer.
Experimental Investigation of Direct Fuel Injection Into Low-Oxygen Recompression Interval in a Homogenous Charge Compression Ignition Engine
Authors: Sok Ratnak , Kusaka Jin 
Published: September 2021

Abstract
This work analyzed measured data from a single-cylinder engine operated under the gasoline direction injection homogenous charge compression ignition (GDI-HCCI) mode. The experiments were conducted at a 0.95 equivalence ratio (ϕ) under indicated mean effective pressure of 0.5 MPa and 1500 rpm. A side-mounted injector delivered primary reference fuel (octane number 90) into the combustion chamber during negative valve overlap (NVO) interval. Advanced combustion phase CA50 were observed as a function of the start of injection (SOI) timings. Under ϕ = 0.95, peak NVO in-cylinder pressures were lower than motoring for single and split injections, emphasizing that NVO reactions were endothermic. Zero-dimensional kinetics calculations showed classical reformate species (C3H6, C2H4, CH4) from the NVO rich mixture increased almost linearly due to SOI timings, while H2 and CO were typically low. These kinetically reformed species also shortened predicted ignition delays. This work also analyzed the effects of intake boosting pressure and single versus double pulses injections on CA50, burn duration CA10-90, peak cylinder pressure, combustion noise metrics, thermal efficiency, and emissions. Advanced SOI (single-injection) generated excessive combustion noise metrics over constraint limits, but the double-pulse injection could significantly reduce the metrics (ringing intensity (RI) ≤ 5 MW/m2, maximum pressure rise rate ≤ 0.6 MPa/CA) and NOx emission. The engine's net indicated thermal efficiency (ITE) reached 41% under GDI-HCCI mode against 36% of SI mode for the same operating conditions. Under GDI-HCCI mode and without spark ignition, late fuel injection in the intake stroke could reduce NOx to a single digit.
Experimental and Numerical Assessment on Failure Pressure of Textured Pipelines
Authors: Karampour Hassan , Alrsai Mahmoud , Khalilpasha Hossein , Albermani Faris 
Published: September 2021

Abstract
A series of physical tests and finite element (FE) analyses are conducted to evaluate the failure of smooth (conventional) and textured (proposed concept) pipes. To do so, hydrostatic pressure tests are performed on aluminum beverage cans (ductile failure) and additively manufactured Ti6Al4V-0406 titanium pipes (brittle failure). Mechanical material properties are obtained from tensile tests of coupon samples. In the absence of physical burst pressure tests, FE models are validated against experimental results of external pressure tests and are used to predict the buckle initiation (Pi) and burst pressure (Pb) capacity of the textured pipes with different number of circumferential triangles, N, and base angles, α. Results show that buckle initiation pressures of the textured concept is 2.34 and 1.80 times greater than those of the smooth aluminum cans and titanium pipes, respectively. However, the burst pressure of the textured pipe can only get 3% greater than the smooth pipe. Based on the current results, a textured pipe with N = 6 and α = 30 deg is the optimum textured design.
Numerical Investigation of Hydrodynamic Performance of a Light Buoy With Different Mooring Configurations in Regular Waves
Authors: Li Xin , Chen Yimei , Mao Lilei , Xia Huiyu 
Published: September 2021

Abstract
The single-moored light buoys employed in the lower reaches of the Yangtze River play an important role in indicating ship navigation and ensuring safety. To clarify the interaction between waves and floating buoys moored to the riverbed, this paper applies a numerical approach to investigate the wave-induced motion performance of a light buoy and reveal the effects of different mooring configurations to extend its service life. An open-source smoothed particle hydrodynamics (SPH)-based numerical model named dualsphysics coupled with MoorDyn is implemented. This coupled model is validated by simulating the motion of a moored rectangle buoy in regular waves, and compared with experimental data and the numerical results of reef3d code, a mesh-based computational fluid dynamics (CFD) model. The validation results show that the coupled model reproduces experimental data well and has a smaller deviation in comparison with reef3d. Then, the coupling model is applied to simulate the hydrodynamic performance of the real-size light buoy employed in Yangtze River and investigate the effects of encounter angle between wave propagation direction and mooring chain. The results demonstrate the capability of this coupled mooring model to simulate the motion of a moored buoy in regular waves, and this numerical approach will be extended to simulate the light buoy in more complex environments such as irregular waves, flow or extreme weather in further work.
Teammate Relationships, Loneliness, and the Motivational and Well-Being Experiences of Adolescent Athletes
Authors: Pacewicz Christine E. , Smith Alan L. 
Published: September 2021

Interpersonal exchanges may contribute to athletes’ motivational and well-being experiences through their contribution to athletes’ feelings of loneliness. Loneliness is understudied in sport, yet it is potentially salient in connecting social relationships with motivational processes and well-being of athletes. The purpose of the current research was to examine (a) the association of aspects of teammate relationships with athletes’ perceptions of burnout and engagement and (b) whether loneliness explained these associations. Adolescent athletes (N = 279) completed established measures of teammate relationships, loneliness, burnout, and engagement. The mediational model was invariant between boys and girls. Loneliness mediated the relationship of social support (β = −0.14, 0.10), corumination (β = 0.09, −0.06), and appraisal of peer rejection (β = 0.11, −0.08) with burnout and engagement, respectively. Continued examination of athletes’ loneliness will extend understanding of athletes’ motivational and well-being experiences and inform the promotion of adaptive sport experiences.
Mental Health Profiles of Danish Youth Soccer Players: The Influence of Gender and Career Development
Authors: Kuettel Andreas , Durand-Bush Natalie , Larsen Carsten H. 
Published: September 2021

The purpose of this study was (a) to investigate gender differences in mental health among Danish youth soccer players, (b) to discover the mental health profiles of the players, and (c) to explore how career progression and mental health are related. A total of 239 Danish youth elite soccer players (M = 16.85, SD = 1.09) completed an online questionnaire assessing mental well-being, depression, anxiety, along with other background variables. Female players scored significantly lower on mental well-being and had four times higher odds of expressing symptoms of anxiety and depression than males. Athletes’ mental health profiles showed that most athletes experience low depression while having moderate mental well-being. Depression, anxiety, and stress scores generally increased when progressing in age, indicating that the junior–senior transition poses distinct challenges to players’ mental health, especially for female players. Different strategies to foster players’ mental health depending on their mental health profiles are proposed.
Carbon and nitrogen isotope evidence for widespread presence of anoxic intermediate waters before and during the Permian-Triassic mass extinction
Authors: Wu Baojin , Luo Genming , Joachimski Michael M. , Wignall Paul B. , Lei Lidan , Huang Junhua , Lai Xulong 
Published: September 2021

Abstract
The largest mass extinction since the advent of animals occurred during the Permian-Triassic (P-Tr) transition, ca. 252 Ma, and is commonly attributed to the eruption of the Siberian Traps large igneous province. However, the direct killing mechanism is still debated. In this study, we investigated marine redox conditions of the intermediate water column that most organisms inhabit with special attention to the time interval before the onset of the mass extinction. The carbon isotope composition of carbonate and organic carbon (δ13Ccarb and δ13Corg) as well as the nitrogen isotope composition of bulk nitrogen (δ15N) were analyzed in four P-Tr boundary sequences (Zhongli, Jianshi, Ganxi, and Chaotian sections), which record a transect from a shallow water carbonate platform to a deep water, lower ramp slope in South China. δ13Ccarb shows a distinct negative shift in all sections and displays a clear, 2–4‰, decreasing gradient accompanying an increase in water depth both before and after the mass extinction. A distinct negative shift in δ15N is observed in the shallow water Zhongli section, whereas a minor negative shift is present in the three deeper water sections. Before the mass extinction, the δ15N values from shallow water sections are higher than those from deeper waters. The low δ15N values close to 0‰ in deeper water sections suggest that microbial nitrogen fixation was the predominant source of biologically available nitrogen before the onset of the mass extinction. Thus, the water depth- dependent gradient in δ13Ccarb and δ15N suggests that an oxygen-deficient intermediate water column was already present before the mass extinction. The uniform δ15N values around 0‰ accompanying the onset of the mass extinction reveal that anoxic intermediate waters expanded into shallow waters. Meanwhile, the distinct positive shift in δ13Corg observed in upper ramp slope sections, i.e., the Jianshi and Ganxi sections, suggests that a euxinic photic zone was at least episodically present in the earliest Triassic. The temporal coincidence between the expansion of intermediate water column anoxia and the onset of the P-Tr mass extinction supports the hypothesis that marine anoxia was a direct killing mechanism.
HbA1c performs well in monitoring glucose control even in populations with high prevalence of medical conditions that may alter its reliability: the OPTIMAL observational multicenter study
Authors: Niwaha Anxious J , Rodgers Lauren R , Greiner Rosamund , Balungi Priscilla A , Mwebaze Raymond , McDonald Timothy J , Hattersley Andrew T , Shields Beverley M , Nyirenda Moffat J , Jones Angus G 
Published: September 2021

IntroductionThe utility of HbA1c (glycosylated hemoglobin) to estimate glycemic control in populations of African and other low-resource countries has been questioned because of high prevalence of other medical conditions that may affect its reliability. Using continuous glucose monitoring (CGM), we aimed to determine the comparative performance of HbA1c, fasting plasma glucose (FPG) (within 5 hours of a meal) and random non-fasting glucose (RPG) in assessing glycemic burden.Research design and methodsWe assessed the performance of HbA1c, FPG and RPG in comparison to CGM mean glucose in 192 Ugandan participants with type 2 diabetes. Analysis was undertaken in all participants, and in subgroups with and without medical conditions reported to affect HbA1c reliability. We then assessed the performance of FPG and RPG, and optimal thresholds, in comparison to HbA1c in participants without medical conditions thought to alter HbA1c reliability.Results32.8% (63/192) of participants had medical conditions that may affect HbA1c reliability: anemia 9.4% (18/192), sickle cell trait and/or hemoglobin C (HbC) 22.4% (43/192), or renal impairment 6.3% (12/192). Despite high prevalence of medical conditions thought to affect HbA1c reliability, HbA1c had the strongest correlation with CGM measured glucose in day-to-day living (0.88, 95% CI 0.84 to 0.91), followed by FPG (0.82, 95% CI 0.76 to 0.86) and RPG (0.76, 95% CI 0.69 to 0.81). Among participants without conditions thought to affect HbA1c reliability, FPG and RPG had a similar diagnostic performance in identifying poor glycemic control defined by a range of HbA1c thresholds. FPG of ≥7.1 mmol/L and RPG of ≥10.5 mmol/L correctly identified 78.2% and 78.8%, respectively, of patients with an HbA1c of ≥7.0%.ConclusionsHbA1c is the optimal test for monitoring glucose control even in low-income and middle-income countries where medical conditions that may alter its reliability are prevalent; FPG and RPG are valuable alternatives where HbA1c is not available.
Generating insights in uncharted territories: real-time learning from data in critically ill patients–an implementer report
Authors: van de Sande Davy , Van Genderen Michel E. , Huiskens Joost , Veen Robert E. R. , Meijerink Yvonne , Gommers Diederik , van Bommel Jasper 
Published: September 2021

IntroductionIn the current situation, clinical patient data are often siloed in multiple hospital information systems. Especially in the intensive care unit (ICU), large volumes of clinical data are routinely collected through continuous patient monitoring. Although these data often contain useful information for clinical decision making, they are not frequently used to improve quality of care. During, but also after, pressing times, data-driven methods can be used to mine treatment patterns from clinical data to determine the best treatment options from a hospitals own clinical data.MethodsIn this implementer report, we describe how we implemented a data infrastructure that enabled us to learn in real time from consecutive COVID-19 ICU admissions. In addition, we explain our step-by-step multidisciplinary approach to establish such a data infrastructure.ConclusionBy sharing our steps and approach, we aim to inspire others, in and outside ICU walls, to make more efficient use of data at hand, now and in the future.