bluuebunny/crossref_metadata_2025_split huggingface dataset:
Is critical flicker‐fusion frequency a valid measure of visual fatigue? A post‐hoc analysis of a double‐masked randomised controlled trial
Authors: Singh Sumeer , Downie Laura E. , Anderson Andrew J. 
Published: November 2022

AbstractPurposeCritical flicker‐fusion frequency (CFF) has been used in clinical studies as a measure of visual fatigue. We examine the correlation between CFF and subjective reports of visual fatigue in a group of symptomatic computer users, to consider whether CFF may be used as a surrogate measure of visual fatigue symptoms.MethodsWe analysed data from a previous randomised controlled trial. One hundred and twenty adults, diagnosed with computer vision syndrome, had CFF and visual fatigue symptoms quantified before and after a visually demanding 2‐h computer task. Symptoms were assessed using a questionnaire with nine subcomponents that summed to a total score of 900. CFF was measured using a two‐interval forced‐choice method, with the flicker rate altered by a computer‐controlled staircase procedure. For our primary analysis, we determined Spearman correlation coefficients between post‐task symptom scores and CFF, and between change from baseline symptom scores and CFF. We also used a bootstrap procedure to consider whether symptom score subcomponents were significantly (Bonferroni‐corrected) different from overall scores with regard to their correlations with CFF.ResultsAlthough visual fatigue symptom scores altered significantly post‐task (mean change: 92 units; 95% confidence interval [CI]: 11 to 122), CFF did not (mean change −0.7 Hz; 95% CI: −1.7 to 0.3). There was no significant correlation between overall symptom scores and CFF, either for the post‐task (r = −0.13; 95% CI: −0.31 to 0.05) or the change from baseline (r = −0.18; 95% CI: −0.35 to 0.01) analysis. Subcomponents of the symptom questionnaire did not show a significant correlation with CFF, either for the post‐task or the change from baseline analysis.ConclusionsWe find that CFF is not a useful surrogate for symptoms of visual fatigue, given its low correlation with scores on a visual fatigue symptom questionnaire.
Tumor‐suppressive miR‐323a inhibits pancreatic cancer cell proliferation and glycolysis through targeting HK‐2
Authors: Wei Yangnian , Wang Mingdong , Liang Mingkun , Liu Ling , Mo Shifa , Zhang Hongchang , Chen Yunhui , Li Nianfeng 
Published: November 2022

AbstractPancreatic ductal adenocarcinoma (PDAC) accounts for more than 85% of all malignant pancreatic exocrine tumors and is one of the main causes of cancer‐related fatalities. PDAC is characterized by a high glycolytic rate to ensure its survival as a result of hypovascularization and the desmoplastic reaction. In this study, microRNA 323a (miR‐323a) was shown to be downregulated within pancreatic cancer tissues and cells, and enriched in the glucose metabolism pathway. In vitro, overexpression of miR‐323a suppressed cell viability, DNA synthesis, and colony formation; in vivo, miR‐323a overexpression suppressed the tumor growth within a xenograft mouse model. Regarding cellular glycolysis, miR‐323a overexpression decreased glucose‐6‐phosphate levels, inhibited glucose uptake, and reduced lactate and adenosine triphosphate production. miR‐323a was found to directly target hexokinase 2 (HK‐2) and negatively regulated HK‐2 expression. HK‐2 overexpression exerted oncogenic effects on pancreatic cancer cells and promoted cellular glycolysis; more importantly, HK‐2 overexpression partially eliminated the effects of miR‐323a overexpression. In conclusion, miR‐323a is downregulated within pancreatic cancer and serves as a tumor‐suppressive miRNA through inhibiting cancer cell proliferation and glycolysis. miR‐323a exerts its tumor‐suppressive effects through targeting HK‐2.
Learning new meanings for known L2 words: Long‐term semantic representation is updated to integrate new information after consolidation
Authors: Chen Jiayan , Chen Baoguo 
Published: November 2022

AbstractPrevious research about learning new meanings for known words in second language (L2) has found that semantic relatedness, i.e., congruency, between new and existing meanings benefits encoding and explicit memory of new meanings, and reduces instant interference on accessing existing meanings. However, they did not take the memory consolidation process into account. Thus, integration of new meaning into long‐term semantic memory, update of existing meaning representation, and the impact of semantic relatedness between new and existing meanings in this process remain unclear. The present study used the event‐related potential (ERP) technique to explore these questions. We asked Chinese students to learn English known words' subdominant meanings variedly related to existing meanings and probed semantic representations with EEG recorded in primed lexical decision tasks four times before and after consolidation. We found that new meaning needs to go through offline consolidation to get integrated. Semantic relatedness/congruency boosted new meaning integration, not by directly expediting it during encoding or preliminary offline consolidation, but by promoting the update of existing meaning representation first, which presumably paved the way for better incorporation of new meaning in the long run. The whole pattern of results implies that long‐term semantic representation of existing meaning is updated to integrate related new meaning after consolidation, which not only draws a clearer picture of L2 ambiguous word acquisition but also bears broader implications for research on memory updating.
Experience of using expired lyophilized snake antivenom during a medical emergency situation in Lao People's Democratic Republic––A possible untapped resource to tackle antivenom shortage in Southeast Asia
Authors: Blessmann Jörg , Hanlodsomphou Soulaphab , Santisouk Bounlom , Krumkamp Ralf , Kreuels Benno , Ismail Ahmad Khaldun , Yong Mun Yee , Tan Kae Yi , Tan Choo Hock 
Published: November 2022

AbstractObjectivesTo evaluate the safety and efficacy of expired lyophilized snake antivenom of Thai origin during a medical emergency in 2020/2021 in Lao People's Democratic Republic.MethodsObservational case series of patients with potentially life‐threatening envenoming who consented to the administration of expired antivenom between August 2020 and May 2022.ResultsA total of 31 patients received the expired antivenom. Malayan pit vipers (Calloselasma rhodostoma) were responsible for 26 (84%) cases and green pit vipers (Trimeresurus species) for two cases (6%). In three patients (10%) the responsible snake could not be identified. Of these, two presented with signs of neurotoxicity and one with coagulopathy. A total of 124 vials of expired antivenom were administered. Fifty‐nine vials had expired 2–18 months earlier, 56 vials 19–36 months and nine vials 37–60 months before. Adverse effects of variable severity were observed in seven (23%) patients. All 31 patients fully recovered from systemic envenoming.ConclusionsUnder closely controlled conditions and monitoring the use of expired snake antivenom proved to be effective and safe. Discarding this precious medication is an unnecessary waste, and it could be a valuable resource in ameliorating the current shortage of antivenom. Emergency use authorization granted by health authorities and preclinical testing of expired antivenoms could provide the support and legal basis for such an approach.
Ageing and endothelium‐mediated vascular dysfunction: the role of the NADPH oxidases
Authors: Kwon Oh Sung , Noh Sung Gi , Park Soung Hun , Andtbacka Robert H. I. , Hyngstrom John R. , Richardson Russell S. 
Published: November 2022

AbstractThe present study aimed to determine the isoform‐specific role of the NADPH oxidases (NOX) in the endothelium‐mediated vascular dysfunction associated with ageing. Endothelium‐dependent [intraluminal flow‐ and acetylcholine (ACh)‐induced] vasodilatation in human skeletal muscle feed arteries (SMFAs) of young (24 ± 1 years, n = 16), middle aged (45 ± 1 years, n = 18) and old (76 ± 2 years, n = 21) subjects was assessed in vitro with and without the inhibition of NOX1 (ML090), NOX2 (gp91) and NOX4 (plumbagin). To identify the role of nitric oxide (NO) bioavailability in these responses, NO synthase blockade (l‐NG‐monomethyl arginine citrate) was utilized. SMFA NOX1, NOX2 and NOX4 protein expression was determined by western blotting. Age related endothelium‐dependent vasodilatory dysfunction was evident in response to flow (young: 69 ± 3; middle aged: 51 ± 3; old: 27 ± 3%, P < 0.05) and ACh (young: 89 ± 2; middle aged: 72 ± 3; old: 45 ± 4%, P < 0.05). NOX1 inhibition had no effect on SMFA vasodilatation, whereas NOX2 inhibition restored flow‐ and ACh‐induced vasodilatation in the middle aged and the old SMFAs (middle aged + gp91: 69 ± 3; 86 ± 3, old + gp91: 65 ± 5; 83 ± 2%, P < 0.05) and NOX4 inhibition tended to restore these vasodilatory responses in these two groups, but neither achieved statistical significance (P ≈ 0.06). l‐NG‐monomethyl arginine citrate negated the restorative effects of NOX2 and NOX4 blockade. Only NOX2 and NOX4 protein expression was significantly greater in the two older groups and inversely related to vascular function (r = 0.48 to 0.93, P < 0.05). NOX2 and, to a lesser extent, NOX4 appear to play an important, probably NO‐mediated, role in age‐related endothelial dysfunction.
imageKey points
The present study aimed to determine the isoform‐specific role of the NADPH oxidases (NOX) in the endothelium‐mediated vascular dysfunction associated with ageing.
Age related endothelium‐dependent vasodilatory dysfunction was evident in skeletal muscle feed arteries in response to both flow and acetylcholine.
NOX2 inhibition (gp91) restored endothelium‐dependent vasodilatation in the middle aged and the old skeletal muscle feed arteries, and NOX4 inhibition (plumbagin) tended to restore these vasodilatory responses in these two groups. Nitric oxide synthase inhibition negated the restorative effects of NOX2 and NOX4 blockade.
NOX2 and NOX4 protein expression was significantly greater in the two older groups and inversely related to vascular function.
NOX2 and, to a lesser extent, NOX4 appear to play an important, probably nitric oxide‐mediated, role in age‐related endothelial dysfunction and could be important therapeutic targets to maintain vascular health with ageing.
Localized Damage Identification in the Last Stage Low-Pressure Steam Turbine Blade Using Dynamic Parameter Measurements
Authors: Shetkar Keshav Ramesh , Srinivas J. 
Published: November 2022

Abstract
Steam turbine blades are the important components in power system shaft lines subjected to severe temperatures, leading to low/high cycle fatigue failures. The transient conditions occurring during startup and shutdown events generate alternative stresses causing the fracture at the blade roots. The present work deals with the effect of localized damage on the vibration characteristics and damage identification study in the last stage low-pressure (LP) steam turbine blade. Initially, free vibration studies and transient analysis of the last row LP blade section are conducted using the finite element model. A crack near the root region is modeled by a torsional spring, whose stiffness is expressed in terms of crack depth ratio. Effects of crack depth ratio and location near the roots on the natural frequencies and transient response amplitudes are studied in detail. The relationship between the damage parameters and blade frequencies is established through the backpropagation neural network model.
Numerical Investigation of a Heavy Duty Compression Ignition Engine Converted to Ammonia Spark Ignition Operation
Authors: Liu Jinlong , Ulishney Christopher , Dumitrescu Cosmin E. 
Published: November 2022

Abstract
The need for global decarbonization in power generation requires the increased use of zero-carbon fuels. Compared to hydrogen, ammonia is easier to store, transport, and produce. In addition, the products of complete combustion of ammonia are water and nitrogen. As a result, ammonia is an ideal green fuel for generating power in internal combustion engines. The drawbacks in power generation relate to the high energy needed to ignite the combustible mixture and the low laminar flame speed of ammonia compared to conventional fuels. The three-dimensional numerical study presented here investigated the potential of converting existing diesel engines to ammonia spark ignition operation. The results indicated that the use of ammonia in a diesel-like combustion chamber produced a slower kernel inception process. But the speed of the fully developed turbulent flame was large enough to rapidly complete the bulk combustion process despite the lower laminar flame speed inside the ammonia-air mixture, and this was in the absence of any combustion promoters such as the addition of hydrogen. The problem with pure ammonia operation was the reduced combustion efficiency and the high level of unburned ammonia emissions, since the slow spark inception process can be compensated by a larger compression ratio. The results also suggested that emissions formation and subsequent oxidation were a more complex phenomena. For example, lean ammonia combustion produced higher nitrogen oxides (NOx) concentrations due to the nitrogen in the fuel, despite the lower combustion temperature. Moreover, advancing spark timing reduced the NOx emissions, which was opposite to the traditional spark ignition engines. Additionally, the ammonia in engine crevices that escaped the late oxidation process was the main source of nitrous oxide (N2O) species in the exhaust gas that usually do not appear in traditional engines. Overall, all these results suggested that more fundamental research on ammonia combustion is needed to understand its use in efficient, decarbonized engines.
Numerical Modeling and Analysis of Energy-Assisted Compression Ignition of Varying Cetane Number Jet Fuels for High-Altitude Operation
Authors: Sapra Harsh Darshan , Hessel Randy , Amezcua Eri , Stafford Jacob , Miganakallu Niranjan , Rothamer David , Kim Kenneth , Kweon Chol-Bum M. , Kokjohn Sage 
Published: November 2022

Abstract
Computational Fluid Dynamics (CFD) simulations are performed to study the potential of Energy-Assisted Compression Ignition (EACI) strategy for enabling ignition and enhancing combustion of different cetane number jet fuels during high-altitude operation. EACI employs an ignition assistant (IA), which is an advanced glow-plug design with the ability to sustain higher temperatures for prolonged periods, to provide the necessary ignition energy for precise ignition control and enhanced combustion. In the numerical simulations, the combustion chemistry solver is coupled with a multi-component wide distillation fuel mechanism, energy source modeling, and a turbulence-chemistry interaction model to accurately capture the Ignition Assisted-combustion. The simulation is first validated against optical engine measurements for CN 48 jet fuel and then transferred to another single-cylinder test engine to study the ignition and combustion characteristics of EACI with CN 35 jet fuel at varying IA temperatures. Simulation results show that EACI significantly improves fuel ignitability. Ignition delay reductions for CN 48 fuel of 57% and CN 35 fuel of 25% are noted at IA temperatures of 1550 K and 1405 K compared to when the IA is switched off. Furthermore, EACI improved the combustion efficiency to 99.7% compared to the 90% estimated for the IA off case in the optical engine.
Evaluation of Spray and Combustion Models for Simulating Dilute Combustion in a Direct-Injection Spark-Ignition Engine
Authors: Kim Joohan , Ameen Muhsin , Scarcelli Riccardo , Kim Namho , Singh Eshan , Sjöberg Magnus 
Published: November 2022

Abstract
Dilute combustion in spark-ignition engines has the potential to improve thermal efficiency by mitigating knock and by reducing throttling and wall heat losses. However, ignition and combustion processes can become unstable for dilute operation due to a lowered laminar flame speed, resulting in excessive cycle-to-cycle variability (CCV) of the combustion process. To compensate for the slower combustion in less reactive mixtures, a modified intake port geometry can be employed to generate a strong tumble flow in the cylinder and elevate turbulence levels around the spark plug, thereby promoting a faster transition to turbulent deflagration. Consequently, optimizing combustion chamber geometry and operating strategy is crucial to maximizing the benefits of using dilute combustion with enhanced in-cylinder turbulence across a wide range of operating conditions. Computational fluid dynamics (CFD) simulations can be utilized for virtual engine optimization tasks, but this would require the models to be truly predictive regarding the impact of changes to the engine design and operational parameters.
In this study, multi-cycle large-eddy simulations (LES) are performed for a direct-injection spark-ignition engine to investigate the model performance in predicting engine combustion characteristics with respect to changes in the intake configuration. A tumble plate that blocks the lower part of the intake port inlet is used to vary the tumble. A set of CFD models that have been recently developed are employed, which takes into account the drag of non-spherical droplets, flash-boiling behavior of liquid sprays, spray-wall interaction, surrogate formulation of a research-grade E10 gasoline, and fast chemical kinetic solvers. Simulation results are compared to experimental engine data in terms of cylinder pressure, apparent heat release rate, mass fraction burned timing, and flame images. It is found that LES employing the state-of-the-art CFD models are capable of properly predicting the spray processes and reproducing the measured mean cylinder pressure for the case with the tumble plate. On the other hand, the LES over-predicts the combustion rate during the early combustion stage and under-estimates the CCV, and these discrepancies become larger when the tumble plate is removed.
Design Optimization of an Ethanol Heavy-Duty Engine Using Design of Experiments and Bayesian Optimization
Authors: Tekgul Bulut , Liu I-Han , Vittal Manohar , Schanz Robert , Blumreiter Julie , Johnson Bernard H. , Magnotti Gina M. 
Published: November 2022

Abstract
Diesel-fueled engines still hold a large market share in the medium and heavy-duty transportation sector. However, the increase in fossil fuel prices and the strict emission regulations are leading engine manufacturers to seek cleaner alternatives without a compromise in performance. Alcohol-based fuels, such as ethanol, offer a promising alternative to diesel fuel in meeting regulatory demands. Ethanol provides cleaner combustion and lower levels of soot due to its chemical properties, in particular its lower level of carbon content. In addition, the stoichiometric operating conditions of alcohol fueled engines enable the mitigation of NOx emissions in aftertreatment stage. With the promise of retrofitting diesel engines to run on ethanol to reduce emissions, the thermal efficiency of these engines remains the primary optimization target. In order to find the optimal ethanol-fueled engine design that maximizes the thermal efficiency, a large design space needs to be investigated using engineering tools.
In this study, previous research by the authors on optimizing the design of a single-cylinder ethanol-fueled engine was extended to explore the design space for a heavy-duty multi-cylinder engine configuration. A heavy-duty engine setup with multiple operating conditions at different engine speeds and loads were considered. A design optimization analysis was performed to identify the potential designs that maximize the indicated thermal efficiency in an ethanol-fueled compression ignition engine. First, a computational fluid dynamics (CFD) model of the engine was validated using experimental data for four drive cycle points. Using a design of experiments (DoE) approach and a parameterized piston bowl geometry, the model was then exercised to explore the relationship among geometric features of the piston bowl and spray targeting angle and indicated thermal efficiency across all tested operating conditions. After evaluating 165 candidate designs, a piston bowl geometry was identified that yielded an increase between 1.3 to 2.2 percentage points in indicated thermal efficiency for all tested conditions, while satisfying the operational design constraints for peak pressure and maximum pressure rise rate. The increased performance was attributed to enhanced mixing that led to the formation of a more homogeneous distribution of in-cylinder temperature and equivalence ratio, higher combustion temperatures, and shorter combustion duration. Finally, a Bayesian optimization (BOpt) analysis was employed to find the optimal piston bowl geometry with a fixed spray injector angle for one of the operating conditions. Using BOpt, a piston candidate was identified that resulted in a 1.9 percentage point increase in thermal efficiency from the baseline design, yet only required 65% of the design samples investigated using the DoE approach.
A Study of Seizure Mechanism at Around the Piston Pin of a Medium Duty Diesel Engine
Authors: Shirotori Yunosuke , Watanabe Takuya , Ito Akemi 
Published: November 2022

Abstract
Downsizing and lowering engine speed is effective for fuel economy. However, such measures lead to severe lubrication condition and increase the risk of seizure because of higher load for the sliding surface. The bearing of the small end of a connecting rod is one of the sliding parts used under the severest lubrication conditions. Therefore, clarifying the mechanism of its seizure is an important subject. In the previous study, it is shown that higher the cylinder pressure thicker the oil film between the piston pin and bearing of the small end of the connecting rod. It derived a hypothesis that cylinder pressure causes a deformation of the pin and thicker oil film at around the center of the bearing and heavy contact at the bearing end. This study aimed clarifying the mechanism of the seizure occurring at around the piston pin. The calculated results showed that oil film could be generated by deformation of the piston pin. Further, oil film thickness was measured by laser induced fluorescence method for investigating the effect of pin stiffness. Measured result showed lower the stiffness of the piston pin thicker the oil film. It was found that the deformation of piston pin caused thick oil films. The fact that seizure occurred often the engine operation with the low stiffness piston pin also proved the hypothesis adequate.