bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermomechanical Stress and Creep-Fatigue Analysis of a High-Temperature Prototype Receiver for Heating Particles
Authors: Carter Matt , Korba David , Martinek Janna , Ma Zhiwen , Li Like 
Published: September 2023

Abstract
This work presents a three-dimensional (3D) thermomechanical model of a prototype-scale enclosed light trapping solar receiver for heating particles. Results of the thermoelastic model are used to estimate receiver lifetime under maximum flux conditions. A computational fluid dynamics (CFD) model is first developed to predict the temperature fields in a multi-panel assembly under steady operating conditions. Solar flux distributions on the receiver are obtained from the software package SolTrace and applied to the 3D thermal model. The subsequent particle heating is captured through a simplified 1D energy balance. Panel reradiation is considered through a surface-to-surface radiation model and natural convection loss to the surrounding air is captured in a representative fluid domain surrounding the receiver. The resulting temperature fields from the CFD analysis are used as inputs for a thermoelastic mechanical model with representative boundary conditions. With the resultant temperature and stress fields, a creep-fatigue damage and lifetime analysis is performed using the linear damage accumulation (LDA) theory. The Manson-Coffin formula and Larson Miller correlation are used to calculate the fatigue and creep, respectively. A maximum damage (corresponding to a 30-year service life) is defined for design assessment. The model was first developed and verified in detail by comparing with published results in the literature (temperature and stress profiles and distributions, and creep/fatigue damage fractions) for tubular solar receivers with supercritical carbon dioxide as the working fluid. It was then implemented to model a planar-cavity receiver with various design parameters. Specifically, three different design geometries are considered, and the results show that a maximum temperature of approximately 1200 K could be reached for each design with the given incident solar flux, with the main difference being the distribution of these temperatures. Preliminary resulting stresses for the small-scale prototype without design optimization vary from 20 MPa to 250 MPa for each design, with the maximum stresses occurring on the front face and concave geometry on the side of the panel. In future work, the developed methodology shown here will be applied to analyze a full-scale (50–150 MWth) receiver.
Urban Scale Cooling Load Prediction of High-Rise Buildings in a Hot and Arid Climate
Authors: Ahmed Omar , Moujahed Majd , Sezer Nurettin , Wang Liangzhu (Leon) , Hassan Ibrahim Galal 
Published: September 2023

Abstract
This study employs an archetype-based modeling approach to estimate and analyze the urban scale cooling load profile of high-rise buildings in the Marina district of Lusail City, Qatar. Since the Marina district is a newly built district, the building typology and geometric characteristics are considered the main criteria for the selection of representative archetypes of the district. Three high-rise building archetypes are developed using EnergyPlus software to represent the available building stocks in the district, which are residential, commercial, and mixed-use. Required data for the input parameters are collected from various sources such as the Lusail City GSAS 2 Star Rating Guidelines, which define the minimum requirements in the region, ASHRAE 90.1, and ASHRAE 62.1 standards, along with user surveys when available. Detailed cooling load profiles of the three building archetypes are obtained in EnergyPlus, which enables aggregating the cooling loads to obtain the cooling load profile of the Marina district at various time resolutions. The cooling load profiles obtained after the simulation of each building archetype model in EnergyPlus are validated with real building cooling loads measured in the case study area. The developed cooling load profiles in this study can inform district cooling facilities for an optimal design and operation of the plant, reveal the energy-saving potential of buildings, and aid in defining cost allocations or billing strategies for end users without the need for the installation of zone-level submeter to each apartment unit. This study further contributes to the establishment of a representative building archetype library for hot and arid climate zones. Thus, the building archetype models produced for the Marina district in this study are also applicable to other regions with similar building types and climatic characteristics.
Heat Transfer of Supercritical CO2 Near the Critical Condition Inside a Microchannel
Authors: Ahmed Pranzal , Parahovnik Anatoly , Peles Yoav 
Published: September 2023

Abstract
Carbon dioxide (CO2) is increasingly being used as a highly efficient, environmentally friendly and sustainable refrigerant/heat transfer fluid. Because of its high specific heat and cooling capacity, supercritical CO2 has the potential to be widely used in a range of applications, such as power generation and thermal management of data centers/electronics. Near the critical condition, the thermo-physical properties undergo drastic changes, which can affect the heat transfer performance. Thus, knowledge about the heat transfer process in the supercritical phase of CO2 is necessary.
In this experimental study, the heat transfer characteristics of supercritical CO2 near the critical condition in a microchannel were studied. An experimental setup, microfluidic devices with embedded resistance temperature detectors (RTDs), and a LabVIEW data acquisition system (DAQ), were used to obtain a range of variables, such as temperature, pressure, heat flux, and mass flux. Heat transfer coefficients (HTC) were calculated for different flow conditions (i.e., mass fluxes and pressures). In addition, the effect of the downstream position was discussed. The independent variables included mass fluxes ranging from 1825 kg/m2.s to 8080 kg/m2.s, reduced pressure (p/pR) ranging from 1.02 to 1.143, and heat fluxes up to 98 W/cm2.
Remote Thermal Measurements With Regression of Acoustic Emissions
Authors: Dunlap Christy , Pandey Hari , Marsh Jackson , Weems Ethan , Hu Han 
Published: September 2023

Abstract
Real-time thermal monitoring and regulation are critical to the mitigation of thermal runaways and device failures in two-phase cooling systems. Compared to conventional approaches that rely on the Joule effect, thermal gradient or transverse thermoelectric effect, acoustic emission (AE)-based remote sensing is more promising for robust and non-intrusive thermal monitoring. Nevertheless, due to the high stochasticity and noise of acoustic signals, existing implementations of AE in thermal systems have been limited to qualitative state monitoring. In this paper, we present a technology for real-time heat flux quantification during two-phase cooling by coupling acoustic sensing using hydrophones and condenser microphones and regression-based machine learning frameworks. These frameworks integrate a fast Fourier transform feature extraction algorithm with regressors, i.e., Gaussian process regressor and multilayer perceptron regressor for heat flux predictions. The acoustic signals and heat fluxes are collected from pool boiling tests under transient heat loads. It is shown that both hydrophone and condenser microphone signals are successful in predicting heat flux. Multiple models are trained and compared some using only one form of acoustic data while others combine both acoustic types (i.e., hydrophone and microphone) in fusion ML models (i.e., early, joint, late). The models using only hydrophone data are shown to perform better than the models using only microphone data. Also, some forms of fusion are shown to have better performance than either of the single input data type models. This AE-ML technology is demonstrated for accurate heatflux quantification. As such, this work will not only lead to a light, low-cost, and non-contact thermal measurement technology but also a new perspective for the physical explanation of bubble dynamics during boiling.
Effect of Modified Fin Geometries on the Effectiveness Of a Phase Change Material Heat Sink
Authors: Jones Austin , Darabi Jeff 
Published: September 2023

Abstract
Finned heatsinks have long been used as a passive means to cool electronic components. However, the demand for smaller, high power density products, packaged near one another, has led to the need for a different solution. One such solution is to utilize a material such as paraffin wax and its high latent heat as a phase change material (PCM). A material with high latent heat allows the components to be held at a lower temperature for a period time until all the PCM has melted. The biggest drawback of these materials is their low thermal conductivity, which does not effectively transfer the heat away from the heat source. This paper presents the experimental and numerical results of various fin geometries effectiveness at overcoming this issue. A 15.24cm × 7.62cm × 5.08cm aluminum housing was fabricated and commercially available fins were modified and inserted into the housing. Pure paraffin wax was melted and poured into the enclosure to act as the phase change material. A heater was attached to the bottom of the housing. Temperature and melt time data was collected. A computational study was then conducted using ANSYS Fluent and the results of the experiment were used to validate the model. The model was then used to study the effects of different fin geometries and heat loads.
Volumetric Additive Manufacturing With 3D Point Cloud Projection and Single-Photon Nonlinear Polymerization
Authors: Jakkinapalli Aravind , Wen Sy-Bor 
Published: September 2023

Abstract
Volumetric additive manufacturing allows simultaneously patterning an entire 3D object by irradiating a photosensitive resin with UV to near-infrared light. An obvious advantage of volumetric additive manufacturing is its capability to construct 3D objects without support structures. Also, volumetric additive manufacturing allows fast 3D fabrication compared with layer-by-layer stacking type 3D fabrication. However, demonstrated volumetric additive manufacturing, such as computed axial lithography, has a resolution limited to ∼50 μm. This study shows that enhanced 3D point cloud projection and single-photon nonlinear polymerization can be used as a new volumetric additive manufacturing method to achieve deep micron-level resolution. The enhanced 3D point cloud projection is achieved with a phase-modulated spatial light modulator (SLM) that can precisely control the diffraction of mini-rays used to generate voxels in the 3D point cloud projection. Consistent deep micron level voxel sizes with minimum side lobes were achieved by randomizing the azimuth and polar angles of the mini-rays from the SLM to diminish unwanted constructive interferences of the mini-rays except at the designed voxel locations. High spatial resolution volumetric additive manufacturing can be achieved by delivering the compressed 3D point clouds from the enhanced 3D point cloud projection with shapes mimicking the desired 3D structures in photopolymers supporting single-photon nonlinear polymerization (e.g., SU-8 with dissolved oxygen as inhibitors). Numerical algorithms for generating 3D point clouds with the enhanced 3D point cloud projection having deep micron resolution and preliminary results of generating simple 3D geometries through the new 3D point cloud projection and single-photon nonlinear polymerization are presented in this study.
The Effect of a Pulsed Flow Inlet on Vacuum Membrane Distillation Performance
Authors: Caspar Justin , Xue Guanyang , Oztekin Alparslan 
Published: September 2023

Abstract
2D Large Eddy Simulations (LES) were run to determine the effect of multiple hydrodynamic optimizations on a vacuum membrane distillation module (VMD). The first optimization considered is a morphology change from a straight channel wall to a sinusoidal one. The second change is a pulsed mass flow at the inlet — similar to adding turbulent energy to the incoming flow. Two different Reynolds/Strouhal numbers were considered, 1,500 (0.24) and 750 (0.48). Three pulsation amplitudes were considered 15%, 25%, and 50% of the base inlet velocity. Simulation results show that by only having one performance increase, going from flat to wiggly, the flux increased by 23% of the baseline value, while both the wiggly channel with pulsations showed a flux increase of 31% of the baseline value. The increase is because the vortex shedding in the wiggly channel reduces temperature polarization near the membrane surface. As pulsations are introduced into the wiggly channel, the flow separates earlier, and more of the channel experiences mixing vortices. In the flat sheet case with no geometric alterations, there is no flow separation regardless of a pulsed inlet.
Associations between prenatal malaria exposure, maternal antibodies at birth, and malaria susceptibility during the first year of life in Burkina Faso
Authors: Natama Hamtandi Magloire , Moncunill Gemma , Vidal Marta , Rouamba Toussaint , Aguilar Ruth , Santano Rebeca , Rovira-Vallbona Eduard , Jiménez Alfons , Somé M. Athanase , Sorgho Hermann , Valéa Innocent , Coulibaly-Traoré Maminata , Coppel Ross L. , Cavanagh David , Chitnis Chetan E. , Beeson James G. , Angov Evelina , Dutta Sheetij , Gamain Benoit , Izquierdo Luis , Mens Petra F. , Schallig Henk D. F. H. , Tinto Halidou , Rosanas-Urgell Anna , Dobaño Carlota 
Published: September 2023

ABSTRACT

In this study, we investigated how different categories of prenatal malaria exposure (PME) influence levels of maternal antibodies in cord blood samples and the subsequent risk of malaria in early childhood in a birth cohort study (
N
= 661) nested within the COSMIC clinical trial (NCT01941264) in Burkina Faso.
Plasmodium falciparum
infections during pregnancy and infants’ clinical malaria episodes detected during the first year of life were recorded. The levels of maternal IgG and IgG
1-4
to 15
P
.
falciparum
antigens were measured in cord blood by quantitative suspension array technology. Results showed a significant variation in the magnitude of maternal antibody levels in cord blood, depending on the PME category, with past placental malaria (PM) more frequently associated with significant increases of IgG and/or subclass levels across three groups of antigens defined as pre-erythrocytic, erythrocytic, and markers of PM, as compared to those from the cord of non-exposed control infants. High levels of antibodies to certain erythrocytic antigens (i.e., IgG to EBA140 and EBA175, IgG1 to EBA175 and MSP1
42
, and IgG3 to EBA140 and MSP5) were independent predictors of protection from clinical malaria during the first year of life. By contrast, high levels of IgG, IgG1, and IgG2 to the VAR2CSA DBL1-2 and IgG4 to DBL3-4 were significantly associated with an increased risk of clinical malaria. These findings indicate that PME categories have different effects on the levels of maternal-derived antibodies to malaria antigens in children at birth, and this might drive heterogeneity to clinical malaria susceptibility in early childhood.
PP2C phosphatases Ptc1 and Ptc2 dephosphorylate PGK1 to regulate autophagy and aflatoxin synthesis in the pathogenic fungus
Aspergillus flavus
Authors: Zhu Zhuo , Yang Mingkun , Yang Guang , Zhang Bei , Cao Xiaohong , Yuan Jun , Ge Feng , Wang Shihua 
Published: September 2023

ABSTRACT

Reversible phosphorylation by protein kinases and phosphatases plays a central role in regulating cellular processes. However, knowledge of the functions of protein phosphatase 2C (PP2C) S/T phosphatases in
Aspergillus flavus
has been unreported until now. Here, we have identified seven members of the PP2C family of protein phosphatases in
A. flavus
. Evolutionary and functional analyses indicated that two redundant PP2C phosphatases, Ptc1 and Ptc2, are highly conserved and regulate conidia development, aflatoxin synthesis, seed infection, and autophagic vesicle formation. The cytoplasmic proteins Ptc1 and Ptc2 exhibit nuclear infiltration after DNA damage-induced autophagy. Their degradation is closely linked to autophagy induction. The Asp residue coordinated with Mg
2+
is critical for phosphatase Ptc1 and Ptc2 activity, thermal stability, and biofunction in
A. flavus
. An immunoprecipitation-mass spectrometry proteomic investigation indicated that 133 proteins co-interact with Ptc1 and Ptc2. Among these proteins, phosphoglycerate kinase 1 (PGK1) interacts with Ptc1 and Ptc2 and shows high levels of phosphorylation in Δ
ptc1
, Δ
ptc2
, and Δ
ptc1
/
ptc2
mutants. Furthermore, PGK1 S203 phosphorylation levels are associated with aflatoxin synthesis and autophagic vesicle formation. Overall, these findings contribute to our understanding of the roles and mechanisms of PP2C family phosphatases in
A. flavus
and highlight their importance in various cellular processes. Furthermore, it reveals a new regulation model in
A. flavus
, where Ptc1 and Ptc2 activate autophagy and aflatoxin synthesis by regulating PGK1.

IMPORTANCE

Aspergillus flavus
is a model filamentous fungus that can produce aflatoxins when it infects agricultural crops. This study evaluated the protein phosphatase 2C (PP2C) family as a potential drug target with important physiological functions and pathological significance in
A. flavus
. We found that two redundant PP2C phosphatases, Ptc1 and Ptc2, regulate conidia development, aflatoxin synthesis, autophagic vesicle formation, and seed infection. The target protein phosphoglycerate kinase 1 (PGK1) that interacts with Ptc1 and Ptc2 is essential to regulate metabolism and the autophagy process. Furthermore, Ptc1 and Ptc2 regulate the phosphorylation level of PGK1 S203, which is important for influencing aflatoxin synthesis. Our results provide a potential target for interdicting the toxicity of
A. flavus
.
Molecular commensalism—how to investigate underappreciated health-associated polymicrobial communities
Authors: Labossiere Alex , Ramsey Matthew , Merritt Justin , Kreth Jens 
Published: September 2023

ABSTRACT

The study of human commensal bacteria began with the first observation of prokaryotes >340 years ago. Since then, the study of human-associated microbes has been justifiably biased toward the study of infectious pathogens. However, the role of commensal microbes has in recent years begun to be understood with some appreciation of them as potential protectors of host health rather than bystanders. As our understanding of these valuable microbes grows, it highlights how much more remains to be learned about them and their roles in maintaining health. We note here that a thorough framework for the study of commensals, both
in vivo
and
in vitro
is overall lacking compared to well-developed methodologies for pathogens. The modification and application of methods for the study of pathogens can work well for the study of commensals but is not alone sufficient to properly characterize their relationships. This is because commensals live in homeostasis with the host and within complex communities. One difficulty is determining which commensals have a quantifiable impact on community structure and stability as well as host health, vs benign microbes that may indeed serve only as bystanders. Human microbiomes are composed of bacteria, archaea, fungi, and viruses. This review focuses particularly on oral bacteria, yet many of the principles of commensal impacts on host health observed in the mouth can translate well to other host sites. Here, we discuss the value of commensals, the shortcomings involved in model systems for their study, and some of the more notable impacts they have upon not only each other but host health.
The mechanism for polar localization of the type IVa pilus machine in
Myxococcus xanthus
Authors: Herfurth Marco , Pérez-Burgos María , Søgaard-Andersen Lotte 
Published: September 2023

ABSTRACT

Type IVa pili (T4aP) are important for bacterial motility, adhesion, biofilm formation, and virulence. This versatility is based on their cycles of extension, adhesion, and retraction. The conserved T4aP machine (T4aPM) drives these cycles; however, the piliation pattern varies between species. To understand how these patterns are established, we focused on the T4aPM in
Myxococcus xanthus
that assembles following an outside-in pathway, starting with the polar incorporation of the PilQ secretin forming a multimeric T4aP conduit in the outer membrane. We demonstrate that PilQ recruitment to the nascent poles initiates during cytokinesis, but most are recruited to the new poles in the daughters after the completion of cytokinesis. This recruitment depends on the peptidoglycan-binding AMIN domains in PilQ. Moreover, the pilotin Tgl stimulates PilQ multimerization in the outer membrane, is transiently recruited to the nascent and new poles in a PilQ-dependent manner, and dissociates after the completion of secretin assembly. Altogether, our data support a model whereby PilQ polar recruitment and multimerization occur in two steps: the PilQ AMIN domains bind septal and polar peptidoglycan, thereby enabling polar Tgl localization, which then stimulates secretin multimerization in the outer membrane. Using computational analyses, we provide evidence for a conserved mechanism of T4aPM pilotins whereby the pilotin transiently interacts with the unfolded β-lip of the secretin monomer, i.e., the region that eventually inserts into the outer membrane. Finally, we suggest that the presence/absence of AMIN domain(s) in T4aPM secretins contributes to the different T4aPM localization patterns across bacteria.

IMPORTANCE

Type IVa pili (T4aP) are widespread bacterial cell surface structures with important functions in motility, surface adhesion, biofilm formation, and virulence. Different bacteria have adapted different piliation patterns. To address how these patterns are established, we focused on the bipolar localization of the T4aP machine in the model organism
Myxococcus xanthus
by studying the localization of the PilQ secretin, the first component of this machine that assembles at the poles. Based on experiments using a combination of fluorescence microscopy, biochemistry, and computational structural analysis, we propose that PilQ, and specifically its AMIN domains, binds septal and polar peptidoglycan, thereby enabling polar Tgl localization, which then stimulates PilQ multimerization in the outer membrane. We also propose that the presence and absence of AMIN domains in T4aP secretins contribute to the different piliation patterns across bacteria.