bluuebunny/crossref_metadata_2025 huggingface dataset:
ALKBH9C, a potential RNA m6A demethylase, regulates the response of Arabidopsis to abiotic stresses and abscisic acid
Authors: Amara Umme , Shoaib Yasira , Kang Hunseung
Published: September 2022

Although several studies have shown that AlkB homolog (ALKBH) proteins are potential RNA demethylases (referred to as ‘erasers’), biological functions of only a few ALKBH proteins have been characterized to date. In this study, we determined the function of ALKBH9C (At4g36090) in seed germination and seedling growth of Arabidopsis thaliana in response to abiotic stress and abscisic acid (ABA). Seed germination of the alkbh9c mutant was delayed in response to salt, drought, cold and ABA. Moreover, seedling growth of the mutant was repressed under salt stress or ABA but enhanced under drought conditions. Notably, the stress‐responsive phenotypes were associated with the altered expression of several m6A‐modified transcripts related to salt, drought or ABA response. Global m6A levels were increased in the alkbh9c mutant, and ALKBH9C bound to m6A‐modified RNAs and had in vitro m6A demethylase activity, suggesting its potential role as an m6A eraser. The m6A levels in several stress‐responsive genes were increased in the alkbh9c mutant, and the stability of m6A‐modified transcripts was altered in the mutant. Collectively, our results suggest that m6A eraser ALKBH9C is crucial for seed germination and seedling growth of Arabidopsis in response to abiotic stresses or ABA via affecting the stability of stress‐responsive transcripts.
Singlet Oxygen's Potential Role as aNonoxidativeFacilitator of Disulfide S–S Bond Rotation†
Authors: Turque Oliver , O'Connor Ryan M. , Greer Alexander
Published: September 2022

The role of singlet oxygen potentially mediating increased conformational flexibility of a disulfide was investigated. Density functional theory (DFT) calculations indicate that the singlet oxygenation of 1,2‐dimethyldisulfane produces a peroxy intermediate. This intermediate adopts a structure with a longer S–S bond distance and a more planar torsional angleθ(C–S–S–C) compared with the nonoxygenated 1,2‐dimethyldisulfane. The lengthened S–S bond enables a facile rotation about the torsional angle in the semicircle region 0° < θ < 210°, that is ~5 kcal mol−1lower in energy than the disulfane. The peroxy intermediate bears nO → σS–Sand nO → σ*S–Sinteractions that stabilize the S–O bond but destabilize the S–S bond, which contrasts with stabilizing nS → σ*S–Shyperconjugative effects in the disulfane S–S bond. Subsequent departure of O2from the disulfane peroxy intermediate is reminiscent of peroxy intermediates which also expel O2, yet facilitatecis‐transisomerizations of stilbenes, hexadienes, cyanines, and carotenes. “Non‐oxidative”1O2interactions with a variety of bond types are currently underappreciated. We hope to raise awareness of how these interactions can help elucidate the origins of molecular twisting.
Cross‐country evidence on the relationship between global value chain position and the tail risk of insurers
Authors: Sun Tao
Published: September 2022

This study investigates the relationship between insurance sectors' global value chain (GVC) positions and insurance firms' tail risk. Using a sample of 208 insurers from 25 countries between 2000 and 2015, we find that insurers' tail risk (i.e., expected shortfall, downside beta, and marginal expected shortfall) increases when an insurance sector's GVC upstreamness indices increase. This result suggests that when an insurance sector becomes more upstream in the global production network, the comovement between insurers' stock returns and the market returns become stronger and insurers become more exposed to market tail risk. By testing over a subsample of non‐US insurers and a sample period excluding the 2008 Global Financial Crisis, we show that our main results remain unchanged. We also use 2SLS with instrumental variables to address the potential endogeneity problem. Using the nonfinancial sectors' GVC positions as the instrumental variable, we find that the main results are robust to the bias associated with any endogeneity problem. This paper provides the first empirical evidence that highlights the role of GVC linkages in tail risk spillover among insurers around the globe. Our findings have important policy implications for the regulation of insurance firms.
Pathogen distribution and antimicrobial resistance in infections in migrants and nonmigrants in Denmark, a cross‐sectional study
Authors: Nielsen Rikke Thoft , Köse Güldas , Sloth Louise , Andersen Christian Østergaard , Petersen Jørgen Holm , Norredam Marie
Published: September 2022

Objective

To investigate differences in bacterial distribution and resistance patterns of relevant pathogens in skin and tissue infections among migrants compared to nonmigrants.

Methods

The population is based on a cohort of migrants who obtained residence as refugees or family‐reunited migrants in Denmark between January 1993 and December 2015. The cohort was linked to positive swabs and tissue cultures collected from hospitals and general practitioners between the years 2000 and 2016 at the Department of Microbiology, University Hospital Hvidovre, Denmark. We calculated odds ratios for pathogen distribution and resistance patterns using logistic regression by comparing migrants with nonmigrants.

Results

In total, 43,770 pathogens from 37,276 individuals were included, with Staphylococcus aureus being the most common bacterium. Migrants had higher odds of infections with Enterobacterales than nonmigrants (OR 1.42, 95% CI: 1.23–1.63) and lower odds of beta‐haemolytic Streptococci (OR 0.79, 95% CI: 0.73–0.86). Family‐reunited migrants and refugees had higher odds of methicillin‐resistant S. aureus (MRSA) than nonmigrants (OR 5.01, 95% CI: 3.73–6.73 and OR 3.66, 95% CI: 2.61–5.13). This was more pronounced in female migrants. The odds of ciprofloxacin‐resistant Enterobacterales were higher in both family‐reunited migrants and refugees than in nonmigrants (OR 2.21, 95% CI: 1.34–3.64 and OR 2.17, 95% CI: 1.34–3.52).

Conclusions

The prevalence of MRSA and ciprofloxacin‐resistant Enterobacterales was higher among family‐reunited migrants and refugees than in nonmigrants. Our findings suggest an increased awareness for AMR in migrants.
The Dubious Perspective of the Eastern Partnership Countries Joining the European Union
Authors: Chytopoulou Eleni
Published: September 2022

There were significant geopolitical shuffles in Europe in the early 1990s. The dissolution of the Soviet Union, the collapse of socialist regimes in Central and Eastern Europe & the disintegration of Yugoslavia emerged as severe threats to destabilizing the international system. Some European countries of the former Eastern Bloc joined the E.U. and NATO swiftly. In contrast, the adjacent countries to Russia of the so-called Eastern Partnership, even Russia in the early '90s, have shown interest in close cooperation with the West. However, the E.U.'s support for the Orange Revolution in Ukraine and the Rose Revolution in Georgia led to a loss of confidence. Discontent escalated, and the EU-Russia partnership froze after the occupation of Crimea and its annexation to Russia. Having recovered economically and politically, Russia seeks its restoration as a superpower and the rival U.S. In this perspective, Russia envisages perpetuating its influence on the countries that had been members of the Soviet Union. Presumably, Russia is directly or indirectly trying to impede the European course of the Eastern Partnership countries that have already declared an interest in becoming E.U.  members. The developments in the most significant countries of the Eastern Partnership countries, Ukraine and Georgia, confirm the difficulties they face in claiming the right to join the E.U and N.A.T.O. Has the E.U. Enlargement to the East reached its limits? Can the Eastern Partnership countries ever become E.U. members?
Toward a Theory of Permanent Environmental Reassignment for Residential Childcare: A Comprehensive Research Agenda for the 21st Century
Authors: Yacoubian George S.
Published: September 2022

Historically there have been two residential childcare institutions in Armenia: orphanages and special boarding schools. The children housed in these facilities are either natural orphans (i.e., children who have no living family or whose biological parents have had their familial rights terminated) or social orphans (i.e., children with living biological parents who are unable or unwilling to care for them but whose rights have not been terminated). In recent years, Armenia’s “transitional centers” have offered a residential alternative for older teenage girls who have outgrown the traditional orphanage but who are not yet ready for independent living. While institutionalization has historically been castigated as contrary to a child’s best interests, our previous research suggests that residential childcare facilities (RCF) provide vulnerable children with a safe haven during times of crisis, a loving environment through intimate relationships with staff and peers, emotional stability during formative years, an improved standard of living, and superior opportunities upon reaching the age of majority. These transitional centers, invaluable to the continuum of care, suggest that permanent environmental reassignment is the ideal path when familial care is surrendered or expropriated.
Reviewer Acknowledgements for Journal of Education and Training Studies, Vol. 10, No. 4
Authors: Smith Robert
Published: September 2022

Journal of Education and Training Studies (JETS) would like to acknowledge the following reviewers for their assistance with peer review of manuscripts for this issue. Many authors, regardless of whether JETS publishes their work, appreciate the helpful feedback provided by the reviewers. Their comments and suggestions were of great help to the authors in improving the quality of their papers. Each of the reviewers listed below returned at least one review for this issue.Reviewers for Volume 10, Number 4 Chris Mutseekwa, Bindura University of Science Education, ZimbabweFathia Lahwal, Elmergib University, LibyaGianpiero Greco, University of Study of Bari, ItalyHelena Reis, Polytechnic Institute of Leiria, PortugalIntakhab Khan, King Abdulaziz University, Saudi ArabiaJohn Cowan, Edinburgh Napier University, UKKendall Hartley, University of Nevada, USAKeyla Ferrari Lopes, UNICAMP, BrazilLisa Marie Portugal, American College of Education, USAMaria Rachel Queiroz, Universidade do Estado da Bahia, BrazilMaria Rosa M. Prado, Faculdades Pequeno Príncipe, BrazilMuhammad Haris Effendi-Hasibuan, Universitas Jambi, IndonesiaMustafa Çakır, Marmara University, TurkeyRichard Penny, University of Washington Bothell, USASandro Sehic, Oneida BOCES, USASenem Seda Şahenk Erkan, Marmara University, TurkeyWong Ken Keong, Inspectorate of School Sabah, MalaysiaYuChun Chen, Louisiana Tech University, USAYuxi Qiu, Florida International University, USA Robert SmithEditorial AssistantOn behalf of,The Editorial Board of Journal of Education and Training StudiesRedfame Publishing9450 SW Gemini Dr. #99416Beaverton, OR 97008, USAE-mail 1: jets@redfame.comE-mail 2: jets@redfame.orgURL: http://jets.redfame.com
Sostenibilidad y medios comunitarios en Colombia
Authors: Téllez Garzón María Patricia
Published: September 2022

Con este artículo se busca realizar una reflexión sobre la radio y la televisión comunitaria en este tiempo de posconflicto. Para ello, se realiza una aproximación a la sostenibilidad como categoría central, resultado del equilibrio entre aspectos económicos, políticos y, particularmente, socioculturales. En un segundo momento, se revisan dos experiencias: Así suenan las radios para la paz en Colombia y el Conversatorio de Medios Comunitarios. Ellas sirven como pretexto para conocer su realidad, sus alcances y limitaciones.
Effect of Compressor Unsteady Wakes on a Gas Turbine Combustor Flow
Authors: Soli Alessandro , Adoua Richard , Langella Ivan , Denman Paul , Garmory Andrew , Page Gary J.
Published: September 2022

In gas turbines, combustor inlets are characterized by significant levels of unsteady circumferential distortion due to compressor wakes and secondary flows, together with additional radial nonuniformity induced by the adverse pressure gradients in the prediffuser. This can cause nonuniform velocity distributions across the fuel injector, although the exact interaction mechanism, and the effects it has on the downstream air–fuel mixing, is not fully understood. This paper investigates the flow in an a single sector of a fully featured isothermal rig comprising of compression and combustion systems, exploiting the synchronous coupling of a compressible unsteady RANS simulation with a low-Mach large eddy simulation (LES). Validation against five-hole probe measurements shows that the coupled approach can correctly predict distortion onset and development, with no solution discontinuity at the coupling interface, and is able to preserve unsteady information. The coupled prediction is then compared against a standalone combustor simulation carried out using a circumferentially uniform inlet profile, showing that the additional turbulence from the wakes interacts with the injector, reducing the coherence of the precessing vortex core (PVC) and potentially affecting the air–fuel mixing characteristics.
Fluid Dynamics of Turbine Rim Seal Structures: A Physical Interpretation Using URANS
Authors: De Cosmo Giove , Scobie James A. , Lock Gary D. , Sangan Carl M. , Carnevale Mauro
Published: September 2022

Unsteady Reynolds-averaged Navier–Stokes modeling (URANS) is a valuable and cost-effective tool for computational fluid dynamics (CFD), including the investigation of mainstream–cavity interaction in turbines. Despite the gap in accuracy with higher order CFD methodologies, URANS is among the few simulation strategies of industrial interest suitable for predicting ingress/egress over a wide range of conditions. This paper presents a numerical study of the flow-field in the upstream double-radial seal of a 1.5 stage turbine. Various configurations are tested, including nonpurged and purged conditions. Rigor of the approach is ensured by a set of sensitivity analyses, allowing the delineation of a best practice on the use of URANS in rim seal simulations: this includes an assessment of the effects of sector size, cavity domain size, and blade count. Time-averaged and time-resolved flow predictions capture coherent structures in the rim gap. An association between the three-dimensional (3D) morphology of these structures and different ingress/egress mechanisms is proposed. Regions of enhanced radial activity are identified to correspond with the blade leading edges. A frequency analysis of unsteady pressure signals probed in the rim gap leads to a calculation of the structure number and speed. The structures are synchronous with the disk rotation for nonpurged cases but rotate at slower speed when purge is introduced. The relative number of blades and vanes directly influences the structure count and velocity. The configuration with no blades is characterized by the slowest structures. The calculations have been conducted at three different flow coefficients for the annulus flow. There is a reduction in radial activity and structure speed at lower flow coefficient, fundamentally related to the reduced pressure asymmetry and gradient of swirl across the rim seal.
Tibial Strains During Prolonged Downhill Running: A Finite Element Analysis
Authors: Khassetarash Arash , Haider Ifaz , Baggaley Michael , Edwards W. Brent
Published: September 2022

Bone strains in the lower extremity may be influenced by neuromuscular fatigue. In this study, we examined potential changes in finite element (FE) predicted tibial strains over the course of a fatiguing downhill-running protocol. Twelve physically active males ran for 30 min on an instrumented treadmill at a speed of 2.8 m s−1 and a grade of −11.3 deg. Motion capture and inverse-dynamic-based static optimization were used to estimate lower-extremity joint contact and muscle forces at the beginning, middle, and end stages of the downhill run. Finite element models of the tibia–fibula complex, from database-matched computed tomography images, were then used to estimate resulting 90th percentile strain (peak strain) and strained volume (volume of elements above 3000 με). In the fatigued state, peak ankle joint contact forces decreased an average of 8.1% (p < 0.002) in the axial direction, but increased an average of 7.7% (p < 0.042) in the anterior–posterior direction; consequently, finite element estimations of peak strain and strained volume were unaffected (p > 0.190). Although neuromuscular fatigue may influence ankle joint contact forces, it may not necessarily influence tibial strains due to the complex, and sometimes nonintuitive, relationship between applied load and resulting bone strain.
Numerical Evaluations of an Uncemented Acetabular Component in Total Hip Arthroplasty: Effects of Loading and Interface Conditions
Authors: Saviour Ceby Mullakkara , Banerjee Chowdhury Joydeep , Gupta Sanjay
Published: September 2022

Using finite element (FE) models of intact and implanted hemipelvises, the study aimed to investigate the influences of musculoskeletal loading and implant–bone interface conditions on preclinical analysis of an uncemented acetabular component after total hip arthroplasty (THA). A new musculoskeletal loading dataset, corresponding to daily activities of sitting up–down, stairs up–down and normal walking, for a pelvic bone was generated based on previously validated Gait2392 model. Three implant–bone interface conditions, fully bonded and debonded having two rim press-fits (1 mm and 2 mm), were analyzed. High tensile (2000–2415 μϵ) and compressive strains (900–1035 μϵ) were predicted for 2 mm press-fit, which might evoke microdamage in pelvic cortex. Strain shielding in periprosthetic cancellous bone was higher for bonded condition during sitting up activity, compared to other combinations of interface and loading conditions. Only the nodes around acetabular rim (less than 6%) were susceptible to interfacial debonding. Although maximum micromotion increased with increase in press-fit, postoperatively for all load cases, these were within a favorable range (52–143 μm) for bone ingrowth. Micromotions reduced (39–105 μm) with bone remodeling, indicating lesser chances of implant migration. Bone apposition was predominant around acetabular rim, compared to dome, for all interface conditions. Periprosthetic bone resorption of 10–20% and bone apposition of 10–15% were predicted for bonded condition. Whereas for press-fit (1 mm and 2 mm), predominant bone apposition of 200–300% was observed. This study highlights the importance of variations in loading and interface conditions on in silico evaluations of an uncemented acetabular component.
A Revisit to the First-Principles Prediction of Interfacial Thermal Conductance of Layered Materials Using Diffuse Mismatch Model
Authors: He Jixiong , Liu Jun
Published: September 2022

Among various models for estimating interfacial thermal conductance (ITC) across different material interfaces, the diffuse mismatch model (DMM) has been generally evaluated as a reliable approach for material interfaces at high temperatures. The previous works by DMM have indicated the correct order of magnitude of ITC in isotropic material interfaces. However, it cannot accurately reproduce the ITC for low-dimensional anisotropic layered materials that are desired for many potential applications. Also, the inappropriate mode matching process approximation of the phonon dispersion curve tends to overestimate the ITC. In this paper, we revisited and updated the numerical method in our previous work that utilizes a mode-to-mode comparison within the DMM framework to predict ITC with the first-principles accuracy. We employed this model to calculate ITCs between layered materials such as MoS2 and graphite and metals such as Al, Au, and Cr. We then compared our values with previous literature data from calculations of phonon dispersion curve and experimental data from time-domain thermoreflectance measurements. With a better mode matching algorithm, the updated numerical method can predict the ITCs with improved accuracy. Further analysis also confirmed that counting only the three acoustic modes and neglecting the low-frequency optical modes lead to significant underestimation of the ITC using DMM.
Modeling the Influence of Heat Transfer on Gas Hydrate Formation
Authors: Kar Aritra , Acharya Palash , Bhati Awan , Shahriari Arjang , Mhahdeshwar Ashish , Barckholtz Timothy A. , Bahadur Vaibhav
Published: September 2022

Gas hydrates are crystalline structures of water and gas which form at high pressures and low temperatures. Hydrates have important applications in carbon sequestration, desalination, gas separation, gas transportation and influence flow assurance in oil-gas production. Formation of gas hydrates involves mass diffusion, chemical kinetics and phase change (which necessitates removal of the heat of hydrate formation). When hydrates are synthesized artificially inside reactors, the heat released raises the temperature of the water inside the reactor and reduces the rate of hydrate formation (since the driving force is reduced). An examination of literature shows that there is inadequate understanding of the coupling between heat and mass transfer during hydrate formation. Current models treat heat and mass transfer separately during hydrate formation. In this study, we develop a first principles-based mathematical framework to couple heat and mass transfer during hydrate formation. Our model explores the difference between “actual subcooling” and “apparent subcooling” in the hydrate forming system. The apparent subcooling depends on the targeted reactor temperature and is supposedly, the driving force for hydrate growth. However, due to the increase in temperature of the reactor, the actual subcooling is lower than the apparent subcooling. All these effects are modeled for a 1-D hydrate forming reactor. Results of our simulations are compared with some experimental observations from literature. We also present mathematical scaling to determine the temperature rise in a hydrate-forming reactor. In addition to artificial synthesis of hydrates, the mathematical framework developed can also be applied to other hydrate forming systems (flow assurance, hydrate formation in nature).
Europa Lander Terminal Sterilization Subsystem (TSS) Thermal Model Verification and Validation (V&V) and Uncertainty Quantification (UQ) Processes
Authors: Irick Kevin W. , Voskuilen Tyler , Sakievich Phil
Published: September 2022

The Jet Propulsion Laboratory has a keen interest in exploring icy moons in the solar system, particularly Jupiter’s Europa. Successful exploration of the moon’s surface includes planetary protection initiatives to prevent the introduction of viable organisms from Earth to Europa. To that end, the Europa lander requires a Terminal Sterilization Subsystem (TSS) to rid the lander of viable organisms that would potentially contaminate the moon’s environment. Sandia National Laboratories has been developing a TSS architecture, relying heavily on computational models to support TSS development. Sandia’s TSS design approach involves using energetic material to thermally sterilize lander components at the end of the mission. A hierarchical modeling approach was used for system development and analysis, where simplified systems were constructed to perform empirical tests for evaluating energetic material formulation development and assist in developing computational models with multiple tiers of physics fidelity. Computational models have been developed using multiple Sandia-native computational tools. Three experimental systems and corresponding computational models have been developed: Tube, Sub-Box Small, and Sub-Box Large systems. This paper presents an explanation of the application context of the TSS along with an overview description of a small portion of the TSS development from a modeling and simulation perspective, specifically highlighting verification, validation, and uncertainty quantification (VVUQ) aspects of the modeling and simulation work. Multiple VVUQ approaches were implemented during TSS development, including solution verification, calibration, uncertainty quantification, global sensitivity analysis, and validation. This paper is not intended to express the design results or parameter values used to model the TSS but to communicate the approaches used and how the results of the VVUQ efforts were used and interpreted to assist system development.
An Experimental Study on Heat Transfer Performance of Jet Impingement Arrays
Authors: Cao Zhen , Sundén Bengt , Fu Jiahong
Published: September 2022

Jet impingement cooling is an effective way for thermal management in electronics, prevailed over many other single heat transfer modes. In general, jet arrays are better than a single jet, enhancing jet cooling performance. However, the performance of jet arrays is strongly dependent on the jet configurations, e.g., adjacent jet interval and hole-to-surface distance. Thus, in this study, jet impingement cooling is investigated on a flat heating surface placed in a channel, including in-line double jet cooling, in-line three jet cooling, and in-line four jet cooling. It is known that the outlet configuration could influence the jet performance because of the crossflow effect, and herein the outlet is designed to have intermediate crossflow only. The local Nusselt number distribution is experimentally measured by the liquid crystal method. Then the effect of the adjacent jet interval on the jet cooling performance on the target surface is compared. It is found that the jet array indeed enhances heat transfer. For example, based on the results, it is seen that in comparison to crossflow cooling, the average Nusselt number is improved by 34% by the in-line double jet cooling, and correspondingly the maximum Nusselt number is enhanced by 51%.
Investigations on Improving the Performance of Solid Desiccant Cooling Systems With Passive Radiative Sky Cooling Modules
Authors: Pan A. , Chen Siru , Ho Tsz Chung , Lee Hau Him , Tso Chi Yan
Published: September 2022

Solid desiccant cooling (SDC) systems are alternatives to conventional vapor compression refrigeration (VCR) systems for indoor air conditioning. Also, passive radiative sky cooling (PRSC) has been shown as an effective electricity-free technology for cooling. PRSC technology has also been incorporated in some air conditioning systems, which were demonstrated to improve system performance considerably. However, the use of PRSC technology in SDC systems has not yet been reported. In this work, a new SDC system was introduced, featuring the use of the PRSC component, i.e., radiative cooling panels, for cooling the supply air to improve the system performance. Mathematical models were developed for each component in the system, after which the models were combined to establish the simulation model of the whole system. The models were validated by comparing with the results in other papers. The performance of the conventional and the newly introduced hybrid SDC systems were evaluated with the established simulation models under the typical hot and humid weather condition in Hong Kong. The performance improvement by adding the PRSC component in the hybrid SDC system was analysed by comparing with the performance of the conventional SDC system. It is shown that the use of the PRSC component can further improve the cooling performance of the SDC system by lowering the air temperature by 3 °C approximately. Therefore, the new hybrid SDC systems with the PRSC component provide a more energy efficient method for indoor air conditioning than conventional SDC systems, especially in hot and humid regions, like Hong Kong.
Parameters of Micro-Nano Structured Surface on Condensation Heat Transfer Performance of Steam With Various Amounts of Non-Condensable Gas: A Theoretical Analysis
Authors: Peng Benli , Sheng Wenlong , Zhou Yong , Qiu Meizhuting , He Zhengyu
Published: September 2022

The parameters of micro-nano structured superhydrophobic surfaces is significant to the dropwise condensation heat transfer of steam with non-condensable gas but the theoretical model has not been structured completely. A theoretical model is structured based on the thermal resistance analysis in this study and applied to analyze the effect of the parameters of the micro-nano structures. The results clearly illustrate that an optimum relative micro-pillar spacing exists and strongly depends of the volumetric fraction of non-condensable gas. The optimum relative micro-pillar spacing increases with the increase of the volumetric fraction of non-condensable gas when the volumetric fraction is lower than 20% but an opposite trend is found when the volumetric fraction is higher than 20%. Moreover, the relative nano-pillar spacing can also significantly affect the optimum relative micro-pillar spacing. Smaller relative nano-pillar spacing induces higher optimum relative micro-pillar spacing. Surface subcooling causes more complicated influence to the relative optimum micro-pillar spacing. Subsequently, the results supply the primary information for optimizing the micro-nano structured surfaces that can induce the condensation heat transfer enhancement of steam with random volumetric fraction of non-condensable gas.
Numerical Investigation on Shell and Tube Latent Thermal Energy Storage Partially Filled With Metal Foam and Corrugated Internal Tube
Authors: Buonomo Bernardo , Manca Oronzio , Nardini Sergio , Plomitallo Renato Elpidio
Published: September 2022

A numerical investigation on Latent Heat Thermal Energy Storage System (LHTESS), based on a phase change material (PCM) partially filled with metal foam, is accomplished. The geometry of the system is a vertical shell and tube LHTES made with two concentric aluminum tubes with the internal tube corrugated. The corrugated internal surface of the hollow cylinder is assumed at a constant temperature above the melting temperature of the PCM to simulate the heat transfer from a hot fluid. The other external surfaces are assumed adiabatic. The phase change of the PCM is modelled with the enthalpy porosity theory while the metal foam is considered as a porous media that obeys to the Darcy-Forchheimer law. Local thermal equilibrium (LTE) model is assumed to analyze the metal foam. Numerical simulations for PCM and PCM in the porous medium in LTE assumptions are obtained and their results are compared in terms of melting time, temperature fields and energy stored. The results show that the heat transfer in the LHTES system improves giving a very faster phase change process when the presence of metal foam increases.
Review of Datasets and Correlations for Two-Phase Flow Boiling Heat Transfer of Pure Ethanol and Ethanol/Water Binary Mixtures
Authors: ElFaham Mohamed , Tang Clement C.
Published: September 2022

Two-phase flow heat transfer has gained an extensive focus over the past decades in many industrial applications and thermal systems. Flow involving phase change due to boiling or condensation exhibits much higher heat transfer coefficient compared to single-phase flow when it is only sensible heat transfer involved. The knowledge of heat transfer coefficients and their parametric behaviors can be utilized to improve the accuracy of models used for designing and optimizing heat transfer equipment for more effective thermal management applications. In two-phase flow boiling heat transfer, the working fluid can be a single pure fluid or a binary fluid mixture. In the present study, a systematic methodology is used to compare the available correlations and experimental data in the literature for pure ethanol and ethanol/water binary mixtures at various physical properties. When evaluating the experimental data available in the literature, the availability of data for flow boiling of ethanol, both as pure fluid or binary mixtures, is found to be limited. The current data that this study has collected for flow boiling of ethanol covers the ranges for mass flux of 0.33 to 290 kg/m2·s, heat flux of 2.8 to 104 kW/m2, operating gage pressure of 18 to 135 kPa, and saturation temperature of 40 to 87°C. The correlations that have high accuracies in predicting the experimental data available in the literature are identified and discussed.
A Numerical Study on the Effect of Physical Changes of Air Distribution Setup on the Heating Performance of a Forced Air Circulation System
Authors: Akula Vincent , Sebastian Anish
Published: September 2022

There is a potential to reduce residential energy consumption by harnessing “accessible and cost-effective technologies” such as a highly efficient heating system. In this study, Computational Fluid Dynamics (CFD) simulation is carried out on the baseline and modified versions of the baseline residential building’s heating system. The results are compared to investigate optimization opportunities. The modifications were limited to a specified room which included changing the location of air vents, the size of the air vents and the air flowrate. Performance criteria for the models included ASHRAE’s thermal comfort assessment, freshness of air using Simscale’s passive scalar source tool, heating efficiency, temperature distribution and air velocity efficiency. The results show that models with a higher air supply vents performed better particularly for thermal comfort and air velocity efficiency while lower air supply models performed better for temperature distribution and heating efficiency. The models which showed better performance for heating and temperature distribution did not meet standards for thermal comfort, but the results provide a roadmap for innovative energy-efficient residential heating systems design.
Experimental Investigation and Heat Transfer Analysis of Innovative Thermal Mechanical Refrigeration System Compared to Electric Compressor
Authors: Sleiti Ahmad K. , Al-Ammari Wahib A. , Al-Khawaja Mohammed
Published: September 2022

The current electric refrigeration and air condition systems are major causes for ozone depletion and global warming. These systems consume large percent of the worldwide gross production of electricity (around 17%). Therefore, developing new refrigeration systems that are able to work using renewable sources (solar, geothermal, etc) and waste heat sources is necessary to address these problems. In this paper, an experimental investigation and heat transfer analysis of an innovative thermal-mechanical refrigeration (TMR) system are presented. The TMR system replaces the electric compressor of the conventional refrigeration systems with an expander-compressor unit (ECU). The ECU can be driven by ultra-low temperature heat sources, has simple configuration, and high flexibility for the operating conditions. A hybrid electric-compressor and ECU refrigeration experimental setup was built to investigate the performance of the ECU and compare it to the electric compressor with R134a as the working fluid. The effect of the major operating parameters (condenser and evaporator pressures and temperatures) on the performance of the electric and TMR systems are investigated and analyzed. The results show that a maximum COP is obtained at refrigerant mass of 30g in electric mode and at refrigerant mass of 60g in ECU mode. A comparison of the TMR to other existing thermal refrigeration systems showed that most of these systems have more complex configurations, lower COP, and higher capital costs.
Non-Intrusive Cooling System Fault Detection and Diagnostics Using Acoustic Emission
Authors: Pandey Hari , Waldo Weston , Hu Han
Published: September 2022

Power intensification and miniaturization of electronics and energy systems are causing a critical challenge for thermal management. Single-phase heat transfer mechanisms including natural and forced convection of air and liquids cannot meet the ever-increasing demands. Two-phase heat transfer modes, such as evaporation, pool boiling, flow boiling, have much higher cooling capacities but are limited by a variety of practical instabilities, e.g., the critical heat flux (CHF), aka departure from nucleate boiling (DNB) in the nuclear industry, flow maldistribution, flow reversal, among others. These instabilities are often triggered suddenly during normal operation, and if not identified and mitigated in time, will lead to overheating issues and detrimental device failures. For example, when CHF is triggered during pool boiling, the device temperature can ramp up in the order of 150 °C/min. It is thus critical to implement real-time detection and mitigation algorithms for two-phase cooling. In the present work, we have developed an accurate and reliable technology for fault detection of high-performance two-phase cooling systems by coupling acoustic emission (AE) with multimodal fusion using deep learning. We have leveraged the contact AE sensor attached to the heater and hydrophones immersed in the working fluid to enable non-invasive fault detection.
Implementation of a Model Predictive Control Strategy to Regulate Temperature Inside Plug-Flow Solar Reactor With Counter-Current Flow
Authors: AlSahlani Assaad , Randhir Kelvin , Hayes Michael , Schimmels Philipp , Ozalp Nesrin , Klausner James
Published: September 2022

This paper presents a model predictive controller (MPC) to regulate temperature inside a tubular solar reactor for production of solid-state solar fuel as a long-term thermal storage. The reactor tube is surrounded with heating elements over a portion of its length defined as the heating zone where the reaction occurs. Inert particles enter the reactor from its top-end and they flow downward due to gravity. Simultaneously, a counter-current flowing gas is supplied from the lower end of the reactor to recuperate the sensible heat and mix with the inert particles. The solar fuel is produced via a thermochemical reaction that occurs at a temperature range between 1000°C and 1500°C. This system is analyzed numerically to formulate a low-order physical model considering heat transfer modes and the reaction kinetics. The numerical model is implemented to design a model-based MPC controller where the measured temperature inside the heating zone is fed back to the control system and the control system produces control actions fed to the reactor in a closed-loop. The control system consists of a MPC code linked to an adaptive system identification code that updates system parameters online to ensure system robustness against external disturbances, model mismatches, and uncertainty. The MPC controller parameters are tuned to optimize the system performance with minimum steady-state error and overshoot. The controller is tested to track different temperature ranges between 1000°C and 1500°C with different particles/gas mass flow rates and ramping temperature profiles. Results show that the MPC controller was successful in regulating the reactor temperature within ± 5°C of its setpoint and maintaining robust performance with minimum input effort when subjected to external disturbances.
Finite Element Conjugate Heat Transfer Strategy for Self and Applied Magnetoplasmadynamic (MPD) Thrusters
Authors: Berry K. J.
Published: September 2022

Conjugate Heat Transfer (CHT) analysis allows for the simulation of heat transfer between solid and fluid domains by exchanging thermal energy at the solid/fluid interfaces. This exchange is especially important for MPD thruster analysis due to the high temperature plasma (∼5000K) heat transfer exchange between the plasma/Cathode and plasma/Anode electrode interfaces. Proper numerical modeling captures both the large electromagnetic current and magnetic field gradients, as well as, the heat transfer thermal gradients, that occur due to large thermal and electrical diffusion coefficient differences at the plasma/solid interface. Although MPD-CHT models are typically not included, attention to such numerical detail yields an improved MPD thruster design process and provides guidance to determine external heat transfer cooling requirements to maintain proper operating parameters. The non-linear coupled finite element formulation herein provides increased stability and presents a computational framework strategy for modeling and analysis of self-field and applied field MPD thrusters considering the highly non-linear, multi-disciplinary, and temperature dependent property requirements of the integrated solid/fluid MPD problem domain. A single numerical modeling design variable (OMEGA) is also introduced that combines experimental and numerical parameters, with reference plasma thermal properties.
Machine Learning Based Control of Multi-Temperature PCM Thermal Storage Assemblies - A Comparison of On/Off Versus Fully Modulating Valve Control
Authors: Cooney Alanna Y. , Carey Van P.
Published: September 2022

Latent thermal energy storage (TES) systems which store energy in a phase change material (PCM) can be used to alleviate disparities in energy supply and demand for a variety of applications from concentrated solar plants to building heating and cooling systems. Furthermore, multiple TES modules containing PCMs with different melt temperatures can be combined in series and parallel configurations to construct a multi-temperature TES assembly to allow for wider flexibility in system optimization. This study demonstrates the feasibility of using machine learning based control methods to operate multi-temperature TES assemblies to ensure both operational reliability and optimization of energy usage. Two different TES assemblies are considered: one with on/off valves controlling flow to individual modules and one with fully modulating valves. Theoretical models are developed to determine the best flow path for the working fluid through each TES assembly for a variety of inlet temperatures and flow rates based on a dual optimization of matching a target outlet temperature and minimizing exergy destruction. Artificial Neural Network (ANN) controllers are then developed for each of the systems to predict the best operating mode based on the inlet temperature and flow rate to the TES assembly. The results demonstrate that an ANN controller can be used to successfully operate a multi-temperature TES assembly and maintain high operational reliability by matching a desired outlet temperature while also improving efficiency by decreasing the fraction of exergy destroyed to total energy transferred.
Large Eddy Simulation of Random Pebble Bed Using the Spectral Element Method
Authors: Nguyen Tri , Merzari Elia , Yuan Haomin , Dai Dezhi , Jackson Brian
Published: September 2022

The evolution of Fluoride-Cooled High-Temperature Reactors (FHRs) that utilize pebble fuel has drastically increased the demand for in-depth understanding of the heat transfer (HT) in packed beds cooled by liquid salts. The complex flow fields found in a pebble bed may require a detailed understanding to ensure the proper cooling of the reactor core during normal and accident conditions. As detailed experimental data is very difficult to obtain for these configurations high fidelity simulation like Large Eddy Simulation (LES) and direct numerical simulation (DNS) can be employed to create a high-resolution HT numerical database that can assist addressing industrial-driven issues associated with the HT behavior of FHRs.

In this paper, we performed a series of LES using the GPU-oriented spectral element CFD code NekRS to investigate the HT for a bed of 1741 pebbles at Reynolds numbers ranging from 50 to 1600 based on coolant (FLiBE) inlet velocity. Two different type of pebble power distribution were used, one with the same power density for all pebble, other with different power density. Non conjugate heat transfer (non-CHT) and conjugate heat transfer (CHT) cases have been performed and characteristics of the flow domain such as average, rms, as well as time series of velocity and temperature have been analyzed. The simulation results show a good agreement between non CHT and CHT. In addition, NekRS data have also been compared with OpenFOAM models. The good agreement has also been achieved which gave the confident of the NekRS/OpenFOAM dataset when little to no empirical data is available. The generated data will be used to benchmark HT modeling methods, local maxima/minima of HT parameters and support convective heat transfer quantification for Kairos Power, validating OpenFOAM models, as well as benchmark lower finality models such as Reynolds Averaged Navier Stokes (RANS) and/or porous media approaches.
Influences of piezoelectric positive-negative junction on the multi-field coupled waves propagation in the piezoelectric semiconductor
Authors: Wei Zibo , Wei Peijun , Xu Chunyu , Guo Xiao
Published: September 2022

The influences of the piezoelectric positive-negative junction (PN junction) between two semiconductors with different doping types on the multi-field coupled wave propagation are studied in the present work. The layered structures of semiconductors are often used in intelligent devices, and the PN junction plays an important role for performance improvement. Due to the migration and diffusion of carriers, the electric potential and concentration of the carrier are graded distribution in the PN junction. This inhomogeneity results in the reflection and transmission of coupled waves, which are the complex of multiple physical fields including the mechanical, electric, and carrier fields. The state transfer equation method is used to obtain the transfer matrix of the PN junction, and the reflection and transmission waves under the plane strain situation are evaluated numerically. The energy fluxes of the reflection and transmission waves are estimated and used to validate the numerical results by the check of energy conservation. It is found that PN junction effects hinder the wave propagation and drastically enhance the reflection ability of the interface, especially, on the coupled carrier waves, and thus are very important and cannot be ignored for the wave propagation problem. The influences of external applied stress and bias electric field are also discussed.
Wearable microneedle-based electrochemical aptamer biosensing for precision dosing of drugs with narrow therapeutic windows
Authors: Lin Shuyu , Cheng Xuanbing , Zhu Jialun , Wang Bo , Jelinek David , Zhao Yichao , Wu Tsung-Yu , Horrillo Abraham , Tan Jiawei , Yeung Justin , Yan Wenzhong , Forman Sarah , Coller Hilary A. , Milla Carlos , Emaminejad Sam
Published: September 2022

Therapeutic drug monitoring is essential for dosing pharmaceuticals with narrow therapeutic windows. Nevertheless, standard methods are imprecise and involve invasive/resource-intensive procedures with long turnaround times. Overcoming these limitations, we present a microneedle-based electrochemical aptamer biosensing patch (μNEAB-patch) that minimally invasively probes the interstitial fluid (ISF) and renders correlated, continuous, and real-time measurements of the circulating drugs’ pharmacokinetics. The μNEAB-patch is created following an introduced low-cost fabrication scheme, which transforms a shortened clinical-grade needle into a high-quality gold nanoparticle-based substrate for robust aptamer immobilization and efficient electrochemical signal retrieval. This enables the reliable in vivo detection of a wide library of ISF analytes—especially those with nonexistent natural recognition elements. Accordingly, we developed μNEABs targeting various drugs, including antibiotics with narrow therapeutic windows (tobramycin and vancomycin). Through in vivo animal studies, we demonstrated the strong correlation between the ISF/circulating drug levels and the device’s potential clinical use for timely prediction of total drug exposure.
Supplemental Material: Foreland basin response to middle Cretaceous thrust belt evolution, southwestern Montana, USA
Authors: Gardner C.T. , al. et , Finzel Emily
Published: September 2022

Files include measured stratigraphic sections, concordia diagrams for U-Pb detrital zircon data, a multidimensional scaling plot that includes arc ages, SELFRAG mineral separation methods and results, GPS coordinates for samples, R2 values for mixture model iterations, and raw point count data. 