bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Particle Size and Shape on the Texture Property of a Solid–Liquid Dispersion System With Gel Particles
Authors: Tanikawa Miyu , Watanabe Yoshiyuki
Published: October 2024

Food texture is one of the most important factors for assessing the quality and acceptability of food. However, the study of food texture has been delayed compared with other factors, such as flavor and taste, due to the difficulty of quantitative analysis related to real physiological senses. Furthermore, the numerical and systematic evaluation of the texture property of dispersion systems, in which solid particles are dispersed in a liquid medium, is very difficult, despite most foods being in a solid–liquid dispersion state during mastication in the human mouth. In this study, the texture property of a solid–liquid dispersion system with spherical and cubic gel particles of agar and konjac was examined to evaluate the physical behavior of food during mastication using the back extrusion method. The yield stress of the system strongly depended on the size and shape of the particles, the mixing ratio of particles of different sizes and shapes, and the concentration of components in the particles. The proposed index, reflecting the size, shape, and number of particles and the yield stress of a single particle, expressed well the measured yield stress of the entire dispersion system. However, the adhesiveness and recoverability showed relatively little dependence on particle size. The findings obtained in this study will contribute to elucidating the texture property of various foods and to the development of new and novel food products and cuisines, thereby benefiting food science and industry.
Effect of furosemide on comprehensive renin‐angiotensin‐aldosterone system activity of Thoroughbred horses
Authors: Lehman Mallory L. , Domenig Oliver , Ames Marisa K. , Morgan Jessica M.
Published: October 2024

Background

Furosemide, a commonly used diuretic, activates the renin‐angiotensin‐aldosterone system (RAAS) in other species. Little is known about RAAS peptide activation in horses.

Hypothesis/Objectives

To evaluate equilibrium analysis as a practical method for RAAS quantification in horses and describe the RAAS response to a single dose of furosemide. We hypothesize that furosemide would cause transient increase in RAAS peptides in horses.

Animals

14 healthy adult thoroughbreds from a university teaching herd.

Methods

Horses received either furosemide (1 mg/kg IV) or saline IV in a crossover study design. Protease‐inhibited samples were compared with equilibrium analysis samples with Deming regression analysis. Renin‐angiotensin‐aldosterone system hormones were evaluated at 0, 0.25, 0.5, 4, and 24 hours postadministration, via equilibrium analysis. Values were compared with a mixed effects model.

Results

Correlation between protease inhibition and equilibrium analysis was high for angiotensin I peptide (AngI) and angiotensin II peptide (AngII) (r = .92 and .95, respectively). Baseline RAAS peptide concentrations were below the limit of detection except AngII (median, 7.5 [range, 3.5‐14.0] pmol/L). Furosemide administration resulted in an increase in AngI (8.0 [0.5‐15.5] pmol/L, P = .03), AngII (33.7 [9.6‐57.9] pmol/L, P = .0008), angiotensin III peptide (AngIII) (2.9 [0.9‐4.9] pmol/L, P = .0005), angiotensin IV peptide (AngIV) (2.0 [0.6‐3.4] pmol/L, P = .0005), and angiotensin 1‐5 peptide (Ang1‐5) (5.6 [1.2‐5.9] pmol/L, P = .003) at 4 hours. Differences are reported as difference in the mean (95% confidence interval [CI]).

Conclusions and Clinical Importance

Furosemide produced an increase in hormones associated with both the classical and alternative RAAS pathways. Serum equilibrium analysis is practical for RAAS analysis in horses.
The Divergent Responses of Salinity Generalists to Hyposaline Stress Provide Insights Into the Colonisation of Freshwaters by Diatoms
Authors: Judy Kathryn J. , Pinseel Eveline , Downey Kala M. , Lewis Jeffrey A. , Alverson Andrew J.
Published: October 2024

Environmental transitions, such as the salinity divide separating marine and fresh waters, shape biodiversity over both shallow and deep timescales, opening up new niches and creating opportunities for accelerated speciation and adaptive radiation. Understanding the genetics of environmental adaptation is central to understanding how organisms colonise and subsequently diversify in new habitats. We used time‐resolved transcriptomics to contrast the hyposalinity stress responses of two diatoms. Skeletonema marinoi has deep marine ancestry but has recently invaded brackish waters. Cyclotella cryptica has deep freshwater ancestry and can withstand a much broader salinity range. Skeletonema marinoi is less adept at mitigating even mild salinity stress compared to Cyclotella cryptica, which has distinct mechanisms for rapid mitigation of hyposaline stress and long‐term growth in low salinity. We show that the cellular mechanisms underlying low salinity tolerance, which has allowed diversification across freshwater habitats worldwide, includes elements that are both conserved and variable across the diatom lineage. The balance between ancestral and lineage‐specific environmental responses in phytoplankton have shaped marine–freshwater transitions on evolutionary timescales and, on contemporary timescales, will affect which lineages survive and adapt to changing ocean conditions.
A small lens on timescales and multimodality in classroom language learning emotions
Authors: Sampson Richard J.
Published: October 2024

Empirical work exploring additional language (L+) learning emotions has both proliferated and expanded its focus over the past 15 years. The current article explores one possibility for responding to the challenge of capturing and describing emotions in order to furnish a more contextualized, multidimensional picture of emotions in L+ learning: the small‐lens approach. From the perspective of the author as a practitioner–researcher, this article draws on data from an L+ discussion activity. Via the activity, the practitioner–researcher identified an emotional outcome of interest and examined the historical buildup to this phenomenon. A narrative of the research process applied aims to illustrate the ways in which multimodal analysis and interrogation of psychological timescales might illuminate intersections between the social and individual. Rather than delineating a complete description of the research, the article strives to intimate possibilities and stimulate more nuanced, situated, and dynamic empirical work into the emergence of emotions in instructed L+ learning. While not the primary focus, some of the teleological (functional) aspects of emotions and emotional expression are also unearthed.
Factors Affecting Delirium Care Core Competency Among Nurses: A Descriptive Correlational Study
Authors: Bae Ki Sook , Roh Young Sook
Published: October 2024

Nurses require optimal competency to deliver safe and high‐quality care to patients with delirium. However, the factors influencing delirium care core competency remain unclear. This study aims to investigate the factors influencing core competency in delirium care among nurses. This study was conducted as a descriptive correlational study following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. A convenience sample of 202 Korean nurses from 15 hospitals completed a structured, web‐based, self‐administered questionnaire. The survey covered general characteristics, delirium care knowledge, moral sensitivity, barriers to delirium care, and core competency in delirium care. Multiple regression analysis identified the factors affecting core competency in delirium care. Results showed that barriers to delirium care, moral sensitivity, academic qualifications, and clinical ladder level were significant factors, accounting for 18.1% of the variance in delirium care core competency. To improve delirium care among nurses, using individual, team, and organizational approaches to address perceived barriers and moral sensitivity is crucial. Competency‐based training programs and administrative support are crucial for enhancing the competency of nurses who are novices and those with associate degrees.
Mobile Health‐Based Health Literacy Weight Management Intervention Using Smart Devices for Adolescents: A Convergent Mixed‐Methods Pilot Study
Authors: Chen Yu‐Hsia , Tzeng Yu‐Fen , Gau Bih‐Shya
Published: October 2024

This study aimed to develop and evaluate the feasibility of a mobile health‐based health literacy weight management intervention program for adolescents during the COVID‐19 pandemic. Therefore, a convergent mixed‐method design was used. The “GO! GO! Smart Healthy” intervention development engaged multidisciplinary healthcare professionals, utilizing mobile health applications and smartwatches. Participants provided data on weight management, dietary habits, and health literacy via an mHealth app, while smartwatches collected objective information on physical activity and sleep. The 12‐week pilot study was conducted from March to September 2021. It evaluated the program's feasibility, employing both quantitative and thematic analyses of focus group discussions for a comprehensive assessment. Of the 27 participants, 44.4% were overweight or obese, with insufficient physical activity reported. Thematic analysis identified three main themes: empowerment, self‐awareness and self‐regulation, and self‐comparison and reflection. Adolescents engaged with smartwatches, demonstrated increased awareness, altruistic behavior, and satisfaction. After integrating mixed‐method data, revisions ensured the program's alignment with participants' preferences. Despite pandemic disruptions, mHealth apps ensured uninterrupted research, showcasing technology's evolving role in healthcare and education. Iterative feedback with participants ensured program suitability, fostering effectiveness.

Trial Registration: ClinicalTrials.gov: NCT04759716
Serial Multiple Mediation of the Marital Satisfaction and Parenting Competence in the Relationship Between Postpartum Depression and Parent–Infant Attachment in First‐Time Parents With Low‐ and High‐Risk Pregnancy Experiences: A Cross‐Sectional Study
Authors: Oh Jiwon , Ahn Sukhee
Published: October 2024

Little is known regarding the effects of postpartum depression on parent–infant attachment in high‐risk parents. Based on Mercer's theory of becoming a mother, this study aimed to (1) examine the mediating effects of marital satisfaction and parenting competence in the relationship between postpartum depression and parent–infant attachment using a serial mediation model in first‐time parent couples during the first 6 months postpartum, and (2) compare the serial mediation models between parents who had experienced low‐risk and high‐risk pregnancies. In this cross‐sectional study, a total of 194 first‐time parent couples at 1 to 6 months postpartum were included. Participants completed an online survey on postpartum depression, marital satisfaction, parenting competence, and parent–infant attachment. In both low‐ and high‐risk groups, parenting competence was a common mediator of the impact of postpartum depression on parent–infant attachment. A sequential mediation effect involving both marital satisfaction and parenting competence was observed in high‐risk mothers. Our findings suggest that the adverse impacts of postpartum depression on parent–infant attachment can be mitigated by boosting parenting competence or improving the marital satisfaction in couples experiencing first high‐risk pregnancy.
The role of reactive enteric glia‐macrophage interactions in acute and chronic inflammation
Authors: Reiner Schneider , Linda Schneider , Ebrahim Hamza , Patrick Leven , Sven Wehner
Published: October 2024

Enteric glia are a heterogeneous population of peripheral glia within the enteric nervous system and play pivotal roles in gut homeostasis, tissue integrity, coordination of motility, and intestinal immune responses. Under physiological conditions, they communicate with enteric neurons to control intestinal motility. In contrast, enteric glia undergo reactive changes in response to inflammatory signals during enteric neuroinflammation and participate in immune control. In this state, these glia are called reactive enteric glia, which promote cytokine and chemokine secretion and perpetuate immune cell recruitment, thereby affecting disease progression. Interestingly, reactive glia exhibit a huge plasticity and adapt to or shape the immune environment towards a resolving phenotype during inflammation and neuropathies. Recent studies revealed a bidirectional communication between enteric glia and resident and infiltrating immune cells under healthy conditions and in the context of inflammation‐based intestinal disorders and neuropathies. While recent reviews give a superb general overview of enteric glial reactivity, we herein discuss the latest evidence on enteric glial reactivity in two prominent inflammatory conditions: acute postoperative inflammation, resulting in postoperative ileus, and chronic inflammation in inflammatory bowel diseases. We define their plasticity during inflammation and the interplay between reactive enteric glia and intestinal macrophages. Finally, we sketch important questions that should be addressed to clarify further the impact of enteric glial reactivity on intestinal inflammation.
Multifaceted roles of TCP transcription factors in fate determination
Authors: Wang Yutao , Cao Yu , Qin Genji
Published: October 2024

Fate determination is indispensable for the accurate shaping and specialization of plant organs, a process critical to the structural and functional diversity in plant kingdom. The TEOSINTE BRANCHED 1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) family of transcription factors has been recognized for its significant contributions to plant organogenesis and morphogenesis. Recent research has shed light on the pivotal roles that TCPs play in fate determination. In this review, we delve into the current understanding of TCP functions, emphasizing their critical influence on fate determination from the organelle to the cell and organ levels. We also consolidate the molecular mechanisms through which TCPs exert their regulatory effects on fate determination. Additionally, we highlight intriguing points of TCPs that warrant further exploration in future research endeavors.
Machine Learning for Localization of Premature Ventricular Contraction Origins: A Review
Authors: Yang Rui , Wang Yiwen , Wang Yanan , Feng Xujian , Yang Cuiwei
Published: October 2024

Premature ventricular contraction (PVC) is one of the most common arrhythmias, originating from ectopic beats in the ventricles. Precision in localizing the origin of PVCs has long been a focal point in electrophysiology research. Machine learning (ML) has developed rapidly in the past two decades with increasingly widespread applications. With the increase of clinical data such as electrocardiograms (ECGs), computed tomography (CT), and magnetic resonance imaging (MRI), ML and its subfields, deep learning (DL), have become powerful analytical tools, playing an increasingly important role in electrophysiological research. In this review, we mainly provide an overview of the development of ML in the localization of PVC origins, including its applications, advantages, disadvantages, and future research directions. This information is intended to serve as a reference for clinicians and researchers, aiding them in better‐utilizing ML techniques for the diagnosis and study of PVC origins.
Voltage‐Guided and Non‐Voltage‐Guided Superior Vena Cava Isolation in Patients With Atrial Fibrillation
Authors: Saito Jumpei , Daiki Kato , Hirotoshi Sato , Matsuda Toshihiko , Koyanagi Yui , Yoshihiro Katsuya , Gibo Yuma , Shigehiro Ishigaki , Usumoto Soichiro , Igawa Wataru , Okabe Toshitaka , Isomura Naoei , Ochiai Masahiko
Published: October 2024

Background

In addition to the pulmonary vein, the superior vena cava (SVC) is an important focus of atrial fibrillation (AF). However, SVC isolation may cause serious complications, and appropriate settings and techniques for SVC isolation are lacking.

Methods

This study enrolled 86 consecutive patients with AF who underwent SVC isolation. Voltage mapping using a multi‐electrode catheter and ablation were performed under the guidance of an electro‐anatomical mapping system. The lines encircling the SVC were divided into eight anatomic segments on the SVC geometry, and each segment was subjected to voltage‐guided (VG) ablation in decreasing order of voltage (starting from the segment with the highest voltage). Non‐VG (NVG) ablation was performed anatomically from the anterior wall toward the septum with one‐round cautery.

Results

A total of 86 cases (66 males, mean age 69 [60, 74], mean CHA2DS2 VASc score 2 [1, 3], 58 paroxysmal AF) with AF were included for ablation. Electrical SVC isolation was successfully achieved in all patients. The length of the myocardial sleeves, as measured from the SVC‐RA junction to the end of the local signal, was 37 [28, 45] mm. Major axis of the RA‐SVC junction was 15 [13, 17] and minor axis of the RA‐SVC junction was 11 [9, 13]. The number of ablation points with VG SVC isolation was fewer than that for NVG SVC isolation (8 [5, 11.5] vs. 11.5 [8.8, 13.3]; p = 0.001). The procedure time of VG SVC isolation was greater than that of NVG SVC isolation (259 s [154, 379] vs. 167 s [115, 222]; p = 0.012). There were no significant differences in the complication rates.

Conclusions

VG SVC isolation reduced the number of ablation points compared with NVG SVC isolation.
Trauma‐induced coagulopathy across age pediatric groups: A retrospective cohort study evaluating testing and frequency
Authors: Deshpande Shyam J. , Tsang Hamilton C. , Phuong Jim , Hasan Rida , Liu Zhinan , Stansbury Lynn G. , Hess John R. , Vavilala Monica S.
Published: October 2024

Background

Trauma‐induced coagulopathy (TIC) is associated with negative outcomes. Pediatric TIC has been described most often in older children. Children undergo normal developmental hemostasis, but it is unknown how this process impacts the risk of TIC across childhood.

Aims

To understand variations in coagulation testing and TIC across pediatric age groups.

Methods

We evaluated testing patterns of coagulation studies at presentation and over the first 72 h of hospitalization by pediatric age group at a large, Level I trauma center, 2015–2020. The frequency of TIC was determined using published, age‐specific reference ranges and controlling for injury severity. We performed subgroup analyses of those with isolated severe traumatic brain injury (TBI) and those who presented directly from the scene of injury.

Results

Data from 2409 pediatric patients were available; 333 patients had isolated severe TBI. Children <1 year were least likely to be tested for TIC at presentation and over the first 72 h, even among the most injured. Fibrinogen testing was uncommon, regardless of injury severity. TIC was common: 22% of patients had TIC at presentation and 35% by 72 h. Greater injury severity was associated with TIC. Children 1–4 and 5–9 years had a higher frequency of TIC at presentation and over 72 h compared to older children in the least injured cohort. We saw no difference in frequency of TIC between age groups in the subset with isolated severe TBI. Using age‐specific criteria, patients most often met TIC criteria by INR/PT, followed by platelet count, and least commonly by aPTT. The presence of TIC was associated with in‐hospital mortality (OR 4.10, 95% CI 2.06–8.17).

Conclusions

Significant sampling bias exists in clinical data collection among injured children and adolescents. Contrary to previous reports and using age‐specific TIC criteria, younger children are not at lower risk of TIC than older children when controlling for injury severity.
Acute transcutaneous auricular vagus nerve stimulation modulates presynaptic SV2A density in healthy rat brain: An in vivo microPET study
Authors: Binda Karina H. , Real Caroline C. , Simonsen Mette T. , Grove Ebbe K. , Bender Dirk , Gjedde Albert , Brooks David J. , Landau Anne M.
Published: October 2024

Vagus nerve stimulation (VNS) is the subject of exploration as an adjunct treatment for neurological disorders such as epilepsy, chronic migraine, pain, and depression. A non‐invasive form of VNS is transcutaneous auricular VNS (taVNS). Combining animal models and positron emission tomography (PET) may lead to a better understanding of the elusive mechanisms of taVNS. We evaluated the acute effect of electrical stimulation of the left vagus nerve via the ear on brain synaptic vesicle glycoprotein 2A (SV2A) as a measure of presynaptic density and glucose metabolism in naïve rats. Female Sprague–Dawley rats were imaged with [11C]UCB‐J (n = 11) or [18F]fluorodeoxyglucose ([18F]FDG) PET (n = 13) on two separate days, (1) at baseline, and (2) after acute unilateral left taVNS or sham stimulation (30 min). We calculated the regional volume of distribution (VT) for [11C]UCB‐J and standard uptake values (SUV) for [18F]FDG. We observed regional reductions of [11C]UCB‐J binding in response to taVNS ranging from 36% to 59%. The changes in taVNS compared to baseline were significantly larger than those induced by sham stimulation. The differences were observed bilaterally in the frontal cortex, striatum, and midbrain. The [18F]FDG PET uptake remained unchanged following acute taVNS or sham stimulation compared to baseline values. This proof‐of‐concept study shows for the first time that acute taVNS for 30 min can modulate in vivo synaptic SV2A density in cortical and subcortical regions of healthy rats. Preclinical disease models and PET ligands of different targets can be a powerful combination to assess the therapeutic potential of taVNS.
Weak compactons of nonlinearly dispersive KdV and KP equations
Authors: Anco S. C. , Gandarias M. L.
Published: October 2024

A weak formulation is devised for the equation, which is a nonlinearly dispersive generalization of the gKdV equation  having compacton solutions. With this formulation, explicit weak compacton solutions are derived, including ones that do not exist as classical (strong) solutions. Similar results are obtained for a nonlinearly dispersive generalization of the gKP equation in two dimensions, which possesses line compacton solutions.
Functional analysis of regA paralog rlsD in Volvox carteri
Authors: Jiménez‐Marín Berenice , Ortega‐Escalante José A. , Tyagi Antariksh , Seah Jundhi , Olson Bradley J. S. C. , Miller Stephen M.
Published: October 2024

Volvox carteri is an excellent system for investigating the origins of cell differentiation because it possesses just two cell types, reproductive gonidia and motile somatic cells, which evolved relatively recently. The somatic phenotype depends on the regA gene, which represses cell growth and reproduction, preventing cells expressing it from growing large enough to become gonidia. regA encodes a putative transcription factor and was generated in an undifferentiated ancestor of V. carteri through duplication of a progenitor gene whose ortholog in V. carteri is named rlsD. Here we analyze the function of rlsD through knockdown, overexpression, and RNA‐seq experiments, to gain clues into the function of a member of an understudied putative transcription factor family and to obtain insight into the origins of cell differentiation in the volvocine algae. rlsD knockdown was lethal, while rlsD overexpression dramatically reduced gonidial growth. rlsD overexpression led to differential expression of approximately one‐fourth of the genome, with repressed genes biased for those typically overexpressed in gonidia relative to somatic cells, and upregulated genes biased toward expression in soma, where regA expression is high. Notably, rlsD overexpression affects accumulation of transcripts for genes/Pfam domains involved in ribosome biogenesis, photosynthetic light harvesting, and sulfate generation, functions related to organismal growth, and responses to resource availability. We also found that in the wild type, rlsD expression is induced by light deprivation. These findings are consistent with the idea that cell differentiation in V. carteri evolved when a resource‐responsive, growth‐regulating gene was amplified, and a resulting gene duplicate was co‐opted to repress growth in a constitutive, spatial context.
Angular Kinematics at Minimum Toe Clearance in People With Transtibial Amputation Using Articulated and Nonarticulated Prosthesis
Authors: Riveras Mauricio , Oldfield Matthew , Catalfamo-Formento Paola
Published: October 2024

Subjects with unilateral transtibial amputation exhibit altered minimum toe clearance (MTC) depending on the ankle prosthesis used. It has been suggested that a limited prosthetic ankle angle could be the cause of the change. The aim of this study was to investigate the alterations in kinematics in the joints responsible for the changes in MTC when using an articulating hydraulic ankle (AHA) prosthesis compared to a nonarticulating ankle (NAA) prosthesis. Twelve participants with unilateral transtibial amputation walked at their self-selected speed on a 10 m pathway. They used both the same AHA and NAA prosthetic models and the prosthetic characteristics were unchanged except for the ankle mechanisms and, consequently, its mass. Data from MTC and hip, knee, and ankle angles in the sagittal, frontal, and transversal plane at the time of MTC were statistically analyzed with a paired sample t-test. The AHA prosthesis showed significantly higher MTC mean (AHA=24.7 ± 9.6 mm versus NAA=17.4 ± 5.2 mm, P<0.01) and variability (13.4 ± 9.6 mm versus 6.7 ± 4.2 mm, P=0.03) on the prosthetic limb than the NAA. A higher mean MTC could be explained by an increase in ankle angle dorsiflexion (AHA=−1.2 ± 2.6 deg versus NAA=−2.9 ± 1.5 deg, P=0.01), while the variability of the prosthetic MTC appears to be influenced by changes in prosthetic mass. The results of this study suggest that ankle dorsiflexion during swing and the mass of the prosthesis have a direct influence in mean MTC and its variability, respectively.
Comprehensive Geometric Parameterization and Computationally Efficient 3D Shape Matching Optimization of Realistic Stents
Authors: Kapoor Ankush , Ray Tapabrata , Jepson Nigel , Beier Susann
Published: October 2024

Flexible and compact shape representation schemes are essential for design optimization problems. Current shape representation schemes for coronary stent designs concern predominantly idealized or independent ring (IR) designs, which are outdated and only consider a small number of core design variables (such as strut width, height, and thickness) and ignore clinically critical design characteristics such as the number of connectors. No reports exist on the geometry parameterization of the latest helical stents (HS) that have more complex geometric designs than IR stents. Here, we present two new shape parameterization schemes to fully capture the 3D designs of contemporary IR and double-helix HS stents. We developed a 3D stent geometry builder based on 17 (IR) and 18 (HS) design variables, including strut width, thickness, height, number of connectors and rings, stent length, and strut centerline shape. The shape of the strut centerline was derived via a combination of NURBS, PARSEC, quarter circle, and straight line segments. Shape matching for complex 3D geometries, such as the contemporary stents within limited function evaluations, is not trivial and requires efficient parameterization and optimization algorithms. We used shape matching optimization with a limited function evaluation budget to test the proposed parameterization and two surrogate-assisted optimization algorithms relying on predictor believer and an expected improvement maximization formulation. The performance of these algorithms is objectively compared with a gradient-based optimization method to highlight their strengths. Our work paves the way for more realistic, full-fledged stent design optimization with structural and hemodynamic objectives in the future.
Point-Based Models: A Unified Approach for Geometric Constraint Analysis of Planar n-Bar Mechanisms With Rotary, Sliding, and Rolling Joints
Authors: Lyu Zhijie , Purwar Anurag
Published: October 2024

Kinematic simulation of planar n-bar mechanisms has been an intense topic of study for several decades now. However, a large majority of efforts have focused on position analysis of such mechanisms with limited links and joint types. This article presents a novel, unified approach to the analysis of geometric constraints of planar n-bar mechanisms with revolute joint (R-joint), prismatic joint (P-joint), and rolling joint. This work is motivated by a need to create and program a system of constraint equations that deal with different types of joints in a unified way. A key feature of this work is that the rolling joint constraints are represented by four-point models, which enables us to use the well-established undirected graph rigidity analysis algorithms. As a result, mechanisms with an arbitrary combination of revolute-, prismatic joints, and wheel/gear/wheel-belt chains without any limitations on their actuation scheme can be analyzed and simulated efficiently for potential implementation in interactive computer software and large-scale data generation.
Stress Analysis and Life Assessment of the Steam Turbine Rotor During Peak Shaving Transient Processes
Authors: Fan Mengyang , Zhao Yongliang , Liu Ming , Wang Chaoyang , Wang Zhu , Yan Junjie
Published: October 2024

To achieve the net-zero emissions targets, the global share of renewable energy is rapidly increasing. The high penetration of intermittent and variable renewable power necessitates that coal-fired power plants enhance their operational flexibility for peak shaving and frequency regulation. Frequent and rapid start-ups, shutdowns, and peak shaving processes pose significant safety challenges to the steam turbine rotors. This paper investigates the impact of flexible operation on rotor stress. Firstly, an online monitoring model was developed and verified using a finite element model of a steam turbine high-medium pressure rotor. Secondly, the online calculation model was integrated with a dynamic coal-fired unit model developed using the JTopmeret software on the GSE platform, a well-established dynamic simulation tool for nuclear and fossil fuel power plants. Finally, a rotor low-cycle fatigue life assessment model was developed, and the von Mises stress and fatigue life loss under various load variation rates and ranges were determined. As the load variation rate increases, the life loss increases significantly, with maximum von Mises stress amplitudes of 5.2, 6.5 and 7.8 MPa at 1%, 2% and 3% Pe min−1 load variation rates, respectively. Conversely, as the load variation range increases, the life loss decreases substantially, with maximum von Mises stress amplitudes of 9.2 and 5.0 MPa during load variation processes of 50%–75% and 75%–100% THA, respectively. This study provides detailed guidance for optimizing the safe operation and control strategies of coal-fired power plants.
Enhanced Thermal Performance in Evacuated Tube Solar Collectors Using Titanium Oxide Nanoparticle: a Computational Fluid Dynamics (CFD) Investigation
Authors: Al Nawafah Qais , Al Nawafah Hamza , Amano Ryoichi S. , Abousabae Mohamed
Published: October 2024

This study focuses on improving thermal performance in evacuated tube solar collectors (ETSCs) by incorporating titanium oxide (TiO2) nanoparticles into the working fluid. Our work, which aims to improve the efficiency of solar thermal systems, uses Computational Fluid Dynamics (CFD) modeling to predict the heat transfer characteristics and fluid dynamics in ETSCs. The effect of incorporating TiO2 nanoparticles into the base fluid on improving the system’s thermal conductivity and overall heat transfer efficiency is investigated. The report introduces a thorough simulation framework that replicates real-world settings and examines the effect of nanoparticle concentration on the thermal characteristics of the working fluid. The core objective is to investigate how TiO2 nanoparticles can enhance the thermal conductivity of the working fluid, thereby improving the overall efficiency of solar thermal systems. The CFD model results are notable, revealing a substantial enhancement in the performance of solar collectors. The efficiency of ETSCs is observed to increase by 12.5%, primarily due to the improved thermal conductivity achieved with the incorporation of TiO2 nanoparticles while maintaining a negligible impact on the fluid’s viscosity. Future work will implement a prototype of the proposed system to study its performance experimentally and compare it with the simulated results.
Operational Flexibility and Thermodynamic Performances of a Combined Heat and Power Plant Integrated With Carbon Capture System
Authors: Liu Xingyan , Fu Yue , Liu Ming , Wang Zhu , Yan Junjie
Published: October 2024

The global energy mix is evolving to sustainable and low carbon, so carbon capture should be developed and applied for the decarbonization of coal-fired power plants. Many coal-fired power plants have been reformed to combined heat and power, which can bring significant energy saving and economic benefits. When the combined heat and power plant is integrated with post-combustion carbon capture system, the carbon capture system will consume much steam extracted from steam turbines, and the heat and power outputs of the power plant will be influenced. Therefore, operational flexibility and thermodynamic performances of a combined heat and power plant integrated with carbon capture system will be evaluated in this study. A 660MW subcritical power plant is analyzed as the reference case, and a large-scale carbon capture system is integrated. The carbon capture system is driven by the exhaust steam of the intermediate pressure cylinder. The off-design simulation model of the coal-fired power plant is developed and validated, and the Aspen Plus software is used to develop the model of the carbon capture system. The integrated system is optimized to decrease the energy consumption of the carbon capture system, Then, operational flexibility and thermodynamic performances of the integrated system is evaluated. Results show that the adjustable ranges of heat and power loads decrease due to the integration of CCS. The energy efficiency within the operation domain in dominated by the heat load, but power load has higher influence on the exergy efficiency than the heat load. The coal consumption rate for carbon capture system is about 0.09kg/kg.
Advanced Digital Techniques for Monitoring Dynamic Compressor Instabilities Through Non-Intrusive Approaches
Authors: Ratto Maurizio , Silvestri Paolo , Reggio Federico , Traverso Alberto , Pascenti Matteo , Cousins William T.
Published: October 2024

Nowadays, electrification of thermal users is strategic for energy transition. In such a context, centrifugal compressors in heat pump systems are experiencing an increasing relevance. Furthermore, thermal demand fluctuations require highly flexible compressors and efficient off-design operations, which may increase the risk of centrifugal compressor instable behavior. This paper presents an innovative approach to monitor electrically-driven compressors, validated through established vibro-acoustic signal processing, applied to a prototype heat pump rig operated at University of Genoa laboratory, equipped with a 7kW variable speed centrifugal compressor, driven by an inverter. First, the system signature characterization is performed in stable operation. Afterwards, compressor instability and surge transients are initiated and maintained by progressively closing the expansion valve in the plant, acquiring the signals before and after instability onset. In this way, suitable surge precursors can be identified and monitored, until full surge cycles establish. The frequency analysis of system dynamic responses is performed in both the sub-synchronous and the high frequency ranges. An early surge detection is demonstrated to be possible basing on electrical motor signals. Thanks to the use of such non-intrusive probes, it is shown that effective diagnostic indicators can be obtained without interacting directly with the working fluid, therefore preserving system integrity and reliability and allowing also retro-fit applications. This paper proves for the first time the effectiveness of radial compressor surge monitoring through electrical signals in a closed loop refrigeration system. The experiments are conducted both during “dry” compressor operation as well as “wet” compression operation, i.e. through refrigerant droplet injection at compressor inlet.
Investigation of NOx Generation and Ammonia Fuel Utilization in a Solid Oxide Fuel Cell
Authors: Wilhelm Cole , Willsey Aliza , Ahn Jeongmin
Published: October 2024

Decreasing the generation of CO2 from energy production is a key area in energy research and environmental sustainability. Fuel cells represent a solution to reducing CO2 generation through the use of hydrogen fuel to generate electricity. However, the widespread use of hydrogen fueled fuel cells is generally limited by difficulty of hydrogen storage, transportation, and synthesis. The primary issue with hydrogen storage is that gaseous hydrogen contains low volumetric energy density. One promising option to address these difficulties is the use of ammonia (NH3) in solid oxide fuel cells (SOFCs), which allows for storage of a liquid fuel source, rather than the highly compressed gaseous fuel. Previous work has shown that a SOFC using ammonia fuel is highly capable of generating electricity at levels comparable to that of pure hydrogen fuel. The nickel within the SOFC, along with the high operating temperatures, assists in the thermal cracking of ammonia. However, one missing piece from our previous work is an investigation of ammonia utilization. As such, this work will seek to evaluate the utilization though an exhaust gas analysis using mass spectroscopy and gas chromatography. Additionally, the exhaust gas composition is monitored for the presence of NOx group gases. With the use of ammonia as the fuel source, there is a possibility that we see nitrogen bonding to oxygen ions at the triple-phase boundary (TPB), leading to NOx formation. Given the danger presented by these gases, we must be certain that the concentrations are negligible, or that there will be sufficient NOx reduction strategies in the exhaust stream. SOFC performance results will be briefly discussed, along with an analysis of exhaust composition using gas chromatography and mass spectroscopy to demonstrate utilization of ammonia and evaluate NOx generation relative to fuel cell electrical performance at various operating temperature.
Experimental Study of Instabilities in Hydrogen-Air Fueled Rotating Detonation Combustion
Authors: Weber Justin M. , Johnson May Kristyn B. , Ferguson Don H. , Bedick Clint R. , Strakey Peter A. , Sidwell Todd G.
Published: October 2024

Conventional gas turbine engines rely on an idealized constant pressure combustion process that in reality produces a pressure decrease as a result of viscous and other non-reversible losses. An alternative approach is rotating detonation combustion (RDC) which is a form of pressure gain combustion in which one or more detonation waves propagate an annular channel resulting in an increase in pressure across, subsequently providing greater work availability compared to deflagration ultimately leading to opportunities for greater thermodynamic efficiency when used in gas turbine engines that conventionally relies on constant. Modern gas turbine engines often rely on pre-mixed reactants to limit NOx emissions, although this may result in greater susceptibility to instabilities such as flashback and thermoacoustic oscillation, particularly for applications that utilize hydrogen as the fuel. Research in RDC has focused on non-premixed reactants thus limiting the occurrence of flashback, and high frequency detonation wave propagation (kHz) may interfere with the occurrence of thermoacoustic oscillations. Thermal NOx emissions are controlled through rapid combustion and sudden expansion of the working fluid. Although RDC may not be susceptible to instabilities encountered in conventional state of the art gas turbine engine combustion, there may be other mechanisms occurring that support instabilities that could be detrimental to performance.

The design of systems utilizing RDC often incorporates a choked inlet and exit boundary conditions, but since the RDC is an inherently unsteady process it is unlikely these boundaries remain choked over the course of a complete cycle (complete rotation of a detonation wave). The presence of multiple waves could further exacerbate changes in choked conditions at inlet and exit boundaries. As a result of restrictive and changing conditions at the boundaries, reflected shock waves may occur traveling upstream from the exit or downstream from the inlet that interfere with the reactant inlet flow, mixing, and subsequent formation of a detonation wave (for example, variable wave height). The objective of this study is to utilize experimental data from multiple dynamic pressure transducers located along the length of an RDC combustor, supplemented with ion probe (chemical ionization) and OH* chemiluminescence acquired within the detonation region, to identify occurrences of instabilities during 20–30 second tests. The length of the test provides an adequate time for the combustor to reach a thermally stable condition. The axial distribution of dynamic pressure transducers provides a means of tracking reflected shock waves within the combustion channel. Experimental data are compared to a limited number of computational results that include both stable and unstable conditions with the detonation channel.
Modeling of a Novel Elastohydrodynamic Seal for sCO2 Power Cycles With Experimental Verification
Authors: Hayne Cole , Topu Ali Akbor , Hassan Mohammad Fuad , Sercer George , Xu Hanping , Cesmeci Sevki
Published: October 2024

Effective sealing remains to be one of the technological challenges at the subcomponent level for supercritical carbon dioxide (sCO2) power generation to be practical. Leakages from sCO2 power cycles can lower cycle efficiencies by up to 0.65%. Therefore, to fully harness the benefits of sCO2 power generation; this leakage must be addressed through engineering of efficient sealing technology. To this end, we propose an elastohydrodynamic (EHD) seal as a potentially effective solution that can operate at sCO2 conditions with minimal leakage and wear. In this study, an FEA/CFD based fluid-solid coupling modeling approach was presented with experimental verification. For proof-of-concept purposes, the tests were performed on a 2” static shaft seal and with pressures up to 1.2 MPa using PTFE as the seal material. Both the test and simulation results exhibited a quadratic leakage trend. The leakage rate first increased with increasing pressures, then made its peak of about 6 g/s in mid-pressure range, then started to drop to lower values of about 1.5 g/s as the pressure reached the maximum operating pressure. The proposed model was demonstrated to be a quick and handy tool to determine the design space of the EHD seals with minimal computational time. The simulation was converged in only 2 s. Yet, the proposed model could provide data regarding the leakage rate, seal deformation, pressure in the clearance, and stress on the seal, and thus, could serve as a design guide for the EHD seals.
Efficient Low-Fidelity Design Tool for Turbine-Integrated Wave Rotor Combustor
Authors: Jamshidnejad Mohammadhossein , Nalim M. Razi
Published: October 2024

Pressure-gain combustion (PGC) has attracted attention for its potential for jet propulsion without turbomachinery. However, the wave rotor combustor is a type of PGC device that may be particularly suited to achieve lower specific fuel consumption and higher specific power in gas turbines. Furthermore, instabilities inherent in conventional gas turbine combustion chambers may be avoided, especially with hydrogen fuel. Wave phenomena and non-steady flow play a key role in most PGC devices, including the wave rotor combustor. The computation of wave effects can be an obstacle to preliminary design of engine-integrated prototypes. In this article, a preliminary model has been put forth to allow low-cost, fast-response design algorithms for the wave rotor combustor integrated with a turbocharger to create a small gas turbine engine. Applications would include emergency power generators or integration in hybrid vehicles. A thermodynamic model of the combustor is used in an algorithm to match the characteristics of an available turbocharger. Simplified sizing relations are presented to assess compatibility and feasibility. It is found that when integrated with a turbocharger at a compressor pressure ratio of 2.2, a pressure gain of 1.6 is possible across the combustor, resulting in a cycle efficiency of 18.8 percent.
Effect of Non-Isothermal Conditions on Wind Patterns Near Isolated High-Rise Buildings
Authors: Najian Maede , Sharma Shivesh , Goudarzi Navid
Published: October 2024

Variations in temperature stratification conditions can change the pattern of airflow and the distribution of pollutants in urban environments. The present study explores the intricate dynamics of wind patterns within urban settings, focusing on their crucial role in evaluating wind power potential, managing air pollution, reducing urban heat island effects, ensuring urban air mobility safety, and improving pedestrian thermal comfort. It addresses the gap in understanding airflow, thermal conditions, and turbulence around buildings, emphasizing the impact of urban designs on wind behavior and temperature layers. Extending our previous research on airflow around high-rise structures, this work explores non-isothermal conditions using data and geometry from Tokyo Polytechnic University’s (TPU) wind tunnel facility. Utilizing advanced computational fluid dynamics (CFD) models, such as Unsteady Reynolds-averaged Navier-Stokes (URANS) in OpenFoam, this study predicts wind velocity, turbulence, and temperature distribution around a single isolated building. It further analyzes the effects of thermal stratification through spectral and proper orthogonal decomposition (POD), uncovering the significant influence of thermal state changes on turbulence kinetic energy. The findings indicate the complex interactions between thermal layers, urban airflow, and architectural configurations, providing valuable insights for urban planning and design. This knowledge is essential for better understanding air pollution distribution, enhancing distributed energy systems’ efficiency, and building energy performance in densely populated areas, offering a pathway to optimize microclimatic control and contribute to sustainable urban development.
Integrated CFD-VR Visualization of Indoor Displacement Ventilation
Authors: Alfred Ashish , Goudarzi Navid , Gulley Elijah , Kalatzis Apostolos
Published: October 2024

The utilization of modeling and simulation techniques is increasingly prevalent in engineering and research fields, particularly in energy efficiency and modeling. These tools offer cost-effective and flexible means of exploring diverse scenarios, including improvement in indoor thermal comfort and advancements in internal energy efficiency through the integration of advanced insulation or smart windows. However, significant challenges persist with current modeling and simulation tools, such as the requirement for specialized expertise, reliance on a wide array of complex software tools, lack of clarity for end-users, and issues related to software interoperability. This paper focuses on the integration of building information modeling with computational fluid dynamics (CFD) and virtual reality to enhance visualization in engineering applications. The project involves the construction of geometry using Autodesk Revit, setting up CFD simulation using Ansys Fluent, and exporting the simulation results for visualization in Unity. Challenges addressed such as software integration and extracting data for complicated post processing methods for visualization are mentioned. The outcomes reveal that integration of CFD with VR can help end-users to understand complex concepts of indoor airflow.