bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation of the Heat Transfer Performance of Low Concentration Surfactant Aided Pool Boiling With Electric Field
Authors: Cheng Chung Ki , Ni Song , Lau Kwun Ting , Khan Shahid Ali , Zhao Jiyun
Published: September 2024

Nucleate boiling has been known as one of the efficient methods for transferring large amounts of heat. Such a method has a broad spectrum of applications, for instance, thermal management of power generation and cooling of high-intensity heat flux devices. In the current work, the effect of applying electric field to the bulk solution was experimentally investigated with the presence of surfactants. A number of studies have shown how the electric fields may enhance heat transfer performance with the aid of surfactants. This work focuses on the coupling behavior of the low-concentration surfactant-aided pool boiling with the presence of electric fields and how it will affect the heat transfer performance. On the other hand, two types of surfactants with different electric charges have been chosen in this work. Namely a cationic surfactant, Dodecyl-trimethylammonium bromide (DTAB), and an anionic surfactant, Sodium Dodecyl Sulfate (SDS). The coupling behavior between the surfactant and the electric field is also shown. When only surfactants are present, the critical heat flux (CHF)is reduced by 27% and 25% for 1 mM SDS and 1 mM DTAB, respectively. And the maximum heat transfer coefficient (HTC) is enhanced by 44% and 169% for 1 mM SDS and 1 mM DTAB, respectively. When an electric field is applied to both surfactants at the same concentration, the CHF doesn’t have significant enhancement. Meanwhile, HTC is enhanced by 9.2% and 4% for SDS and DTAB, respectively.
An Experimental Investigation on Characteristics of Liquid Film Thickness of Gas-Liquid Taylor Flow in Rectangular Microchannel
Authors: Fu Dengwei , Hong Sihui
Published: September 2024

Liquid film thickness is one of the most important parameters for understanding two-phase flow in micro-scales. In the present work, experiments were conducted to investigate the variation of liquid film thickness in square tubes with hydraulic diameter Dh = 0.3, 0.5, 0.7, 1.0 mm, and rectangular tubes with a depth of 0.5mm and widths of 0.3, 0.5, 0.7, 1.0 mm. The liquid film thicknesses were measured using a laser focus displacement meter, and visualization images were captured by a high-speed camera. The experiments revealed that at low capillary numbers, surface tension determines the lower limit of the liquid film thickness in either square or rectangular microchannels. At medium capillary numbers, viscous force becomes prominent, and increase the thickness of the liquid film. At high capillary numbers, inertia forces determine the upper limit of the liquid film thickness. The non-uniform distribution of the liquid film thickness in rectangular channels intensifies with the increase in the aspect ratio of channel width to depth.
Molecular Dynamics Investigation of Wettability Transition of Copper and Design of a Durable Superwetting Structure
Authors: Huang Zhigang , Long Jiangyou , Luo Kai
Published: September 2024

Superwettability of clean metal surfaces cannot endure for extended periods in natural atmospheric conditions. Among the various factors that may contribute to the wettability transition of metals, we believe that the adsorption of organics plays a significant role. In this study, we investigate the impact and extent of adsorbed organics on the wettability of copper through Molecular Dynamics simulations of carboxyl acids adsorbing on its surface. We examine the change in surface energy with increasing coverage ratio of organics. The result reveals that a clean metal surface exhibits high surface energy, corresponding to a superwettability nature. However, as the coverage ratio of organics increases, the wettability decreases and changes to hydrophobic at a coverage ratio of about 0.5–0.6. The simulations indicate that this wettability transition is primarily caused by the water-repelling effect originating from the carbon backbone of the organic molecules. Shorter molecules exhibit lower water-repelling strength and form weaker adsorption structures, leading to a less pronounced wettability transition. To achieve durable superwetting, we propose a porous structure composed of sufficiently small voids that allow water molecules to enter while preventing the penetration of organic molecules. Experimental results demonstrate that this structure enables superwetting to persist for several months in urban atmospheric conditions. These superwetting surfaces hold significant potential for various applications across different domains.
Multi-Fidelity Design of Flow Boiling Heat Transfer Processes in Microchannels
Authors: Yuan Yi , Chen Li , Zhang Chuangde , Tao Wen-Quan
Published: September 2024

Topology optimization (TO) is a powerful method with high degree of design freedom. However, TO is difficult to perform effectively for complex problems represented by flow boiling. This paper builds a framework that avoids time-consuming two-phase simulation and generates structures with high flow boiling heat transfer performance. In this study, the necessary numerical methods are modeled and integrated into a multi-fidelity workflow, including low-fidelity TO and high-fidelity evaluation. Based on these models, the flow boiling heat transfer performance of low-fidelity TO structures is parametrically investigated under different heat flux, subcooling and inlet velocity. The results show that the high temperature at corners of the heat sink leads to accumulation of vapor that severely degrades the heat transfer performance. Based on this result, the high temperature at corners in the low-fidelity temperature field is considered to be a feature with poor high-fidelity performance. This feature is verified by comparing performance of three TO structures, and interestingly, the results show that structures with high low-fidelity performance do not lead to high high-fidelity performance. Then this feature is quantified as an index. By comparing this index under the low-fidelity condition, the performance under the high-fidelity condition can be judged. Twelve TO structures are evaluated by this index, and the results show that there is a significant positive correlation between the index and flow boiling heat transfer performance. The new index can characterize the high-fidelity flow boiling performance of low-fidelity TO structures.
Tunable Electro-Optical Switch in Infrared Communication Band Through Coupling Surface Plasmon Polaritons and Magnetic Polaritons
Authors: Gong Yiquan , Guo Yanming , Chen Shuni , Pan Qinghui , Shuai Yong
Published: September 2024

Optical switch is an essential component in optical communication, which essentially modulates the transmittance in the radiation characteristics of objects. Micro-nano optical switches have the advantage of shorter switching time compared to traditional mechanical optical switches, but their extinction ratio (ER) is lower than that of mechanical optical switches, which seriously restricts the development of micro-nano optical switch. In this article, we achieved an ER of up to 42.6 dB in the infrared communication band (6000cm−1–8000cm−1) based on the electrochromic material lithium titanate (LTO) using the coupling of surface plasmon polariton (SPP) and magnetic polaritons (MP). When the optical switch is in “on” mode, the transmittance can reach 0.967 at wavenumber 6400cm−1, however the transmittance is suppressed to 5.27 × 10−5 at wavenumber 6400cm−1 when the optical switch is in “off” mode. The oblique incidence calculation shows that our optical switch can still maintain good performance under high angle incidence. Our research may contribute to the development of infrared optical communication.
Experimental and Numerical Investigation of the Combustion of a Polymer Infused Fuel Droplet
Authors: Spandan Rimjhim , Bohrey Aayushi , Deka Mandeep , Xia Jun , Ravikrishna R. V. , Panda Pratikash
Published: September 2024

Gelled propellants are a propulsion system fuel whose rheological properties are modified by the addition of a gellant, usually a polymeric or colloidal substance, leading to the liquid fuel having a very viscous liquid, or gel-like consistency. Gelled propellants offer many advantages over conventional liquid pro-pellants such as greater control over the energy density, as well as, ease of transportation and storage (like solid propellants). In this work, we study the combustion dynamics of a single polymer-infused fuel droplet, using both experiments and numerical simulation. The droplet is suspended over a flat flame and different stages of combustion are captured. Using the observations from the experimental data, we formulate a theoretical model for the internal dynamics of the polymer-infused fuel droplet till the end of the initial stage. The resulting partial differential equation is solved numerically and is compared against the experimental data.
Power-Generating Smart Glass With Adjustable Spectral Transmission
Authors: Chen Shuni , Guo Yanming , Gong Yiquan , Shen Chao , Shuai Yong
Published: September 2024

Solar energy is usually difficult to utilize efficiently once it reaches the building through the window glass. Smart glass regulates and utilizes the solar energy spectrum through its material and structural properties, greatly improving the utilization of solar energy. This article offers a multilayers structure smart glass with a metal-particle-doped photovoltaic material layer, which can reach selective transmission of human eye spectral response and relatively high photoelectric conversion efficiency. Four typical doping combinations were calculated and optimized by a multi-island genetic algorithm to obtain structural parameters that give better performance. Under the optimized weighting of 1:1, the average transmittance in the spectral response range of the eye can reach more than 0.75, while the photovoltaic conversion efficiency is between 0.1 and 0.2 or greater than 0.2. The work in this paper provides a reference for the design of smart glass structures to improve the energy efficiency of buildings.
Experimental and Numerical Study on Phase Change Heat Transfer of Ternary Non-Azeotropic Mixture
Authors: Zhang Bo , Tian Peipei , Wang Zhiguo , Sun Zhiwei , Cui Peilin , Liu Zhenyu
Published: September 2024

In this work, one water/1,2-propylene glycol/glycerol ternary solution was constructed to investigate the influences of heating power and solution components on its heat and mass transfer in the phase transition process. The experiment studied the effects of power ranging from 30 W to 70 W, water volume fraction ranging from 30% to 50%, and 1,2-PG volume fraction changing from 5% to 15% on various parameters. Additionally, one corresponding theoretical model was proposed to provide a guidance for the utilization of ternary non-azeotropic mixtures as working fluid. The influential pattern of power on factors, such as the phase change rate and system temperature, has been obtained. The analysis indicates that increasing the volume fraction of low-boiling-point components leads to a decrease in the phase change rate of high-boiling-point components. Furthermore, while increasing the volume fraction of high-boiling-point components elevates their own phase change rate, it does not significantly affect the phase change rate of low-boiling-point components.
Flow Boiling in Microchannels Based Heat Sinks Combined With Micro-Nano Modified Surfaces
Authors: Perez Mariana , Pontes Pedro , Moreira António L. N. , Moita Ana S.
Published: September 2024

The present paper addresses an experimental study on the development of a microchannel based heat sink to cool photovoltaic panels, mainly focusing on the flow instabilities and on the potential effect of surface microstructuring in heat transfer enhancement and in controlling two-phase flow instabilities in a single microchannel. The results include pressure drop and heat flux maps, obtained combining pressure sensors with high-speed imaging and time resolved thermography. After identifying the flow boiling regimes, the observed phenomena are qualitatively and quantitatively described. Results show that surface cavities per se do not promote active nucleation sites. However, a regular pattern of microcavities enhances heat transfer and promotes the occurrence of a more stable flow in the microchannels.
Molecular Dynamic Study on the Nucleation Characteristics of Carbon Dioxide During Pressure Drop
Authors: Wang Xiang , Liu Fang
Published: September 2024

Heterogeneous nucleation is one of the most effective mechanism for initiating phase transformation. Impurities serve as a catalyst in the formation of a new thermodynamic phase by lowering the activation energy necessary for a phase transition and promoting nucleation. This study utilizes molecular dynamics (MD) simulation to examine the heterogeneous nucleation process of CO2 refrigerant during pressure drop phase transformation in the motive flow section of the CO2 ejector. The study results indicate that elevated target pressures in CO2 systems can reduce the minimum Gibbs free energy required for the formation of CO2 clusters of varying sizes, thereby promoting refrigerant nucleation. At a target pressure of 2.70 MPa, the nucleation rate exhibits an increase of 0.34 × 1032 m−2s−1 at 2.86 MPa, 1.11 × 1032 m−2s−1 at 3.14 MPa, and 2.4 × 1032 m−2s−1 at 3.38 MPa. Furthermore, the introduction of PAG lubricating oil into the system decreases the minimum Gibbs free energy necessary for the formation of CO2 clusters of different sizes, while simultaneously enhancing intermolecular forces and facilitating the molecular nucleation of CO2 refrigerants. In comparison to an oil-free CO2 system operating at a target pressure of 3.14 MPa, elevating the mass fraction of PAG oil results in an increased nucleation rate of N3 clusters by 0.43 × 1032 m−2s−1 (2% of PAG), 0.37 × 1032 m−2s−1 (1 % of PAG), and 0.2 × 1032 m−2s−1 (3% of PAG) respectively. This acceleration contributes to the nucleation process of CO2 refrigerants. Nevertheless, it simultaneously leads to a decrease in the mass diffusion coefficient of CO2 molecules within the system. It is worth noting, however, that pressure continues to be the predominant factor influencing CO2 refrigerant nucleation.
Effect of Temperature and Water Content on Thermal Conductivity in Ordered and Amorphous Proton Exchange Membranes: A Molecular Dynamics Study
Authors: Ren Ke , Liu Xinjian , Rao Zhonghao
Published: September 2024

Proton exchange membrane (PEM) is the key component of proton exchange membrane fuel cell. The thermal conductivity of the PEM determines the efficiency of heat dissipation through various cooling methods, directly impacting the fuel cell’s performance. Imparting order to Nafion molecules is a potentially effective method to significantly improve the thermal conductivity of PEM. However, the intrinsic mechanism of this effect as well as the regulatory mechanism is still unclear.

In order to investigate the regulatory mechanism of temperature and water content on the thermal transport mechanism of PEM and to compare the thermal transport properties of ordered and amorphous membranes, this study used reverse non-equilibrium molecular dynamics simulations (RNEMD) to investigate the thermal conductivity of ordered and amorphous membranes at 300 K and 350 K under different water content conditions. The simulation results show that it is effective to improve the thermal conductivity of PEM by imparting order to Nafion molecules, and the thermal conductivity of the ordered membrane is approximately twice that of the amorphous membrane. Furthermore, it was also found that increasing temperature and hydration level can enhance the thermal conductivity of both ordered and amorphous membranes.
Numerical Study of Pool Boiling Heat Transfer on a Heated Cylinder by Lattice Boltzmann Method
Authors: Li Xi , Li Huixiong , Wu Xiaoyi
Published: September 2024

Pool boiling is widely utilized in various industrial applications due to the high heat transfer performance. In the numerical simulations, the pseudopotential LB model is capable of simulating the entire boiling processes, including the bubble nucleation. Under the effect of gravity and surface tension, the distribution of phase fields on the circle surface is nonuniform. The bubble dynamics, and the heat transfer characteristics during the pool boiling processes on the circular surfaces would be unique compared to those on the heated plate. In this study, the bubble dynamics and heat transfer during pool boiling processes at a heated cylinder with different wall superheats were simulated using the MRT pseudopotential model coupled with phase-change model. The bubble dynamics and heat transfer with various orientations of the heated cylinder during pool boiling processes were investigated. In addition, the influence of surface tension and saturated temperature on pool boiling heat transfer was studied. It was found that increasing surface tension could enhance the heat transfer performance for the nucleate boiling with high wall superheat, and CHF is proportional to 0.254 power of surface tension. When Ja is low, the saturated temperature has little influence on heat transfer performance. However, in the nucleate boiling regime with large Ja, heat transfer performance as well as CHF decrease with the increasing saturated temperature.
Experimental Study of Single-Bubble Dynamics and Microlayer Characteristics in Pool Boiling on Different Wettability Surfaces
Authors: Zhao Pengfei , Jamali Jawed Ahmed , Zhu Zihou , He Ying
Published: September 2024

Nucleate boiling is the most effective mode of heat transfer in pool boiling, exploring the morphological changes of bubbles under different conditions is of great help in improving the heat transfer mechanism of nucleate boiling. This study obtains hydrophilic, smooth, and hydrophobic surfaces with contact angles of 40.3°, 69.3°, and 90° by grinding, oxidizing, and corroding copper surface with 276 um machined cavity, respectively, and then build a boiling experimental bench that can stably generate single-bubble, and the PIV technique is used to carry out single-bubble experiments on heat transfer surfaces with different wettability to observe the morphology of single-bubble and the trend of their surrounding fluids. The experimental results show that as the hydrophobicity of the heat transfer surface increases, the volume, the base circle radius, etc., and the thickness of the microlayer beneath the bubble will increase, the heat carried away by the single bubble will be more, and the replenishment rate of liquid due to the evaporation of microlayer at the moment of bubble detachment will also be faster, which will lead to the formation of a new bubble and help it detach from the surface and enhance the heat transfer.
A New Model for Capillary Imbibition With Asymmetric Wettability Walls
Authors: Zhu Chenyue , Yan Yuying , Alston Mark
Published: September 2024

The imbibition dynamics is controlled by energy dissipation mechanisms and influenced by asymmetric wettability in a nanochannel. This work proposes a new theoretical model for capillary imbibition while the imbibition dynamics are described by a combined model of the Lucas-Washburn equation and the Cox-Voinov law considering velocity-dependent contact angles. Most of previous studies on capillary imbibition have focused on channels with walls of homogeneous and symmetric wettability. The imbibition dynamics in channels with asymmetric wettability is not well understood. Meanwhile, the energy dissipation mechanism in capillary imbibition also remains to be elucidated. Here, theoretical analysis and molecular dynamics simulations are combined to investigate the energy dissipation mechanism of capillary imbibition in nanochannels. The model may have a wide range of applications, for example, in development of novel materials and microfluidic chips, control of transport of water molecules and ions in cement-based materials, and regulating the spontaneous imbibition of hydraulicfracturing fluids in shale reservoirs.
Two-Dimensional Numerical Simulation on Bubble Growth in Microchannel Boiling Flow
Authors: Gao Hongtao , Zhai Jianrong , Niu Dong , Liu Huaqiang , Yan Yuying
Published: September 2024

In this paper, a gradient constraint algorithm is proposed to study the boiling flow mechanism of lithium bromide solution in microchannels. The numerical results obtained using this method demonstrate good agreement with the experimental results. In this study, the growing process of a single refrigerant bubble and the merging of two lateral bubbles in a two-dimensional microchannel were examined. The impact of various factors, such as wall superheat, Reynolds number, surface tension, and double bubble merging on wall heat transfer were investigated. The results show that increases in both wall superheat and inflow Reynolds number improve the heat flux at the heated wall. The effects of changes in surface tension on the heat flux at the heated wall surface differ in the pre- and post-bubble growth periods. The algorithm is still able to keep the interface clear and sharp during multi-bubble merging, and it is found that multi-bubble merging also improves the heat flux at the heated wall.
Experimental Study on the Heat Transfer Performance of a Cesium Oscillating Heat Pipe
Authors: Feng Yanmin , Ji Yulong , Liu Zhonghao , Wu Mengke , Liu Huaqiang
Published: September 2024

Due to the active chemical properties, explosive risk and high price of cesium metal, research on high-temperature oscillating heat pipe (HOHP) with cesium as a working fluid has not been reported. In view of the application of HOHPs and the need for systematic academic research, a high-temperature heat pipe with cesium as the working fluid was fabricated in this paper and the filling ratio was 50 %. The start-up and operating characteristics of the Cs-HOHP at an operating temperature of 80°C were investigated experimentally, and the effects of different inclination angles (90°, 60°, 30°, 0°) and different input powers on the heat transfer performance were analysed. The experimental results show that: (1) when the inclination angle was 90°, 60°, and 30°, the start-up temperature of Cs-HOHP was lower compared with that of HOHP with sodium, potassium, and sodium-potassium alloys as the working fluids, whereas the start-up of Cs-HOHP could not be started or had a poor start-up performance when the inclination angle was 0°. (2) At an inclination angle of 60°–90°, the heat transfer performance of Cs-HOHP was insensitive to the inclination angle, and when the inclination angle was 30°, the thermal resistance increased significantly, especially when the input power was low. (3) At an inclination angle of 90° and an input power of 3373 W, the thermal resistance was the smallest, with a value of 0.17 °C/W.
Development of Enhanced Interactions for Highly Coarse-Grained Materials
Authors: Seaton Michael , Sokhan Vlad , Todorov Ilian
Published: September 2024

Modelling micro- and mesoscale transport of soft condensed matter hinges upon its representation, including any complex phenomena, at appropriate length and time scales, especially when using larger-than-atomistic techniques such as dissipative particle dynamics (DPD). Simple repulsive pairwise interactions typically used in DPD calculations can capture some complexity, but certain thermodynamic behaviours such as single-component phase coexistence and transitions are normally unavailable. By extending the commonly-used DPD interactions to include attraction and additional control on repulsion, we have devised a new interaction model for highly coarse-grained and mesoscopic scales. The model, denoted here as nDPD, retains many advantages of the original while enabling more complex thermodynamic behaviours, particularly vapour-liquid coexistence below a critical point and solid-liquid transitions. Some of its features include: changes in liquid curves for vapour-liquid coexistence based on repulsion steepness, comparatively low melting points, contraction of solid phases upon heating (negative thermal expansion) and pressure-induced melting. Here, we demonstrate how nDPD can be parameterised for highly coarse-grained water, and how well it fits potentials for long polymeric chains that have been systematically coarse-grained from atomistic molecular dynamics calculations. These enable further exploration of these materials in the rheological domain using DPD-based modelling.
Numerical Investigation on Mixed Convection With Nanofluids in Vertical Channels With Different Aspect Ratios and Moving Plate
Authors: Buonomo Bernardo , Manca Oronzio , Nardini Sergio , Ripoli Chiara , Sarli Gianluca
Published: September 2024

A numerical investigation on 2-dimensional steady-state mixed convection in a vertical channel asymmetrically heated with water-alumina (Al2O3) nanofluids has been conducted to assess the aspect ratio’s impact on thermal and fluid dynamic behaviors. This research is of interest due to its relevance to various technological applications such as nuclear reactors and electronic components. The nanoparticles used have a fixed diameter of 30 nm, and four different concentrations (ranging from 0 to 6%) were examined. The computational domain comprises the channel and two lateral reservoirs, which mimic the external ambient conditions. The channel is defined by two vertical parallel plates: one plate is subjected to a constant heat flux, while the other plate moves in the direction of buoyancy. The governing equations were solved numerically using the finite volume method with the ANSYS-Fluent code. Three different aspect ratios of the channel (5, 10, and 20), seven wall heat flux values (corresponding to Ra = 7*102 to 106), and six velocities of the unheated plate (with Re = 1 to 102) were considered. The results are presented in terms of velocity, temperature, shear stress, and stream function. Additionally, correlations for predicting the average Nusselt number along the heated plate are provided.
Lithium-Ion Battery Thermal Management System Using Diamond Based Nanofluid and Hybrid Nanofluid Active Cooling
Authors: Siddiqui Farooq Riaz , Zhang Jim
Published: September 2024

A robust battery thermal management system (BTMS) is crucial for the safety, reliability, and efficiency of Li-ion batteries. An efficient BTMS keeps the battery within a reasonable temperature range, improving its performance. In this research, we investigated the cooling performance of commercially available Li-ion batteries using the diamond nanofluid and the alumina-diamond hybrid nanofluid under laminar and transition flow conditions. We compared the cooling performance of nanofluid and hybrid nanofluid with a benchmark fluid, water. Initially, we performed dry tests without any cooling to investigate the battery mean surface temperature. Subsequently, we performed liquid cooling tests for a series of discharge cycles to evaluate the battery cooling performance. We found that the diamond nanofluid and alumina-diamond hybrid nanofluid outperformed water in battery cooling performance under laminar and transition flow conditions. Moreover, a reduction of up to 25.2% in the temperature increase to discharge capacity ratio (TIDCR) was achieved using nanofluid and hybrid nanofluid cooling compared to water cooling. Also, in a laminar flow regime, the battery cooling performance improved with increasing concentration of the diamond nanofluid. The results indicate that diamond based nanofluids and hybrid nanofluids are viable options for Li-ion battery cooling.
Numerical Simulation of Leidenfrost Effect of Droplets on Porous Substrate
Authors: Cui Peilin , Liu Zhenyu , Wu Huiying
Published: September 2024

The Leidenfrost effect refers to the phenomenon where a liquid droplet instantaneously contacts a high-temperature surface, forming a vapor film that suspends it above the surface. To overcome the increased heat resistance and deteriorated heat transfer caused by the Leidenfrost effect, the surface texturing has been employed to enhance the Leidenfrost point. In this study, a VOF phase-change model coupled with species transport models was established to investigate the phase-change, spreading, and permeation processes of droplet on high-temperature porous surfaces. Furthermore, the effects of heating surface temperature (423 K to 623 K) on droplet dynamics were explored. The results indicate that, due to the competition between capillary forces from the porous structure and vapor expansion, the porous surfaces exhibit a delaying effect on the Leidenfrost phenomenon compared to the flat surfaces. The evaporation of droplets on a porous surface generates higher pressure due to hindered vapor diffusion within the porous structure.
Thermal and Hemodynamic Characterization of Intracranial Aneurysm on Chip: A Numerical Investigation
Authors: Kumar Gaurav , A. M. Aneesh , Kumar Sumit
Published: September 2024

Intracranial aneurysms (IAs) are localized dilations along the blood vessels of the cerebral artery. The rupture of these IAs leads to subarachnoid hemorrhage, which has a very high mortality rate. So, it is essential to understand the flow behavior and rupture mechanism of IAs to improve the existing treatment techniques and develop novel treatment techniques. Aneurysm-on-chip is a microfluidic chip that simulates typical aneurysm mechanics and physiological responses. For hyperthermia and hypothermia patients, the body temperature can vary from 41 °C to 32 °C, above and below which patients need medical emergency. However, a few researchers have investigated the effect of the temperature-dependent viscosity on the flow behavior in IAs. The effect of temperature-dependent viscosity is considered in the present study for a better understanding of the flow behavior in IAs. This problem is simulated using Ansys Fluent 18.1 software. The effect of blood inlet and surface temperatures on the various hemodynamic parameters, such as wall shear stress (WSS) and oscillatory shear index (OSI), have been investigated. It is found that higher WSS and OSI are observed for the lower value of blood inlet and surface temperatures. Thus, Hypothermia patients should be given more care having IAs.
Frequency Analysis of Pressure Oscillations in Subcooled Flow Boiling Through Microchannel Heat Sink
Authors: Shah Nishant , Mehta Hemantkumar B. , Banerjee Jyotirmay
Published: September 2024

The study presents frequency analysis of pressure drop oscillations in subcooled flow boiling through a MCHS. The analysis employs the Welch power spectrum method to estimate the dominant frequency, providing insights into the dynamic behavior of the flow oscillation. The Welch Power Spectrum method addresses its limitation related to spectral leakage by incorporating windowing, leading to more accurate and reliable spectral analysis, especially in scenarios involving non-stationary signals or noisy data. To control the backflow during flow boiling, a single disc spring loaded flow restrictor is incorporated before the inlet plenum of the MCHS. The impact of flow restrictor on pressure drop oscillations is comprehensively examined using Welch power spectrum across varying heat fluxes (25 W/cm2 to 80 W/cm2) and mass fluxes (520 kg/m2s) in a high aspect ratio configuration (500μm channel height and 230μm channel width) of 44 parallel microchannels. This approach enables the identification of dominant frequencies linked to the flow boiling phenomenon, based on the temporal variation of pressure drop. Additionally, the research highlights the efficacy of the flow restrictor in mitigating flow boiling instability within the MCHS.
Numerical simulation projects in micromagnetics with Jupyter
Authors: Lonsky Martin , Lang Martin , Holt Samuel , Pathak Swapneel Amit , Klause Robin , Lo Tzu-Hsiang , Beg Marijan , Hoffmann Axel , Fangohr Hans
Published: September 2024

We report a case study where an existing materials science course was modified to include numerical simulation projects on the micromagnetic behavior of materials. The Ubermag micromagnetic simulation software package is used in order to solve problems computationally. The simulation software is controlled through the Python code in Jupyter notebooks. Our experience is that the self-paced problem-solving nature of the project work can facilitate a better in-depth exploration of the course contents. We discuss which aspects of the Ubermag and the project Jupyter ecosystem have been beneficial for the students' learning experience and which could be transferred to similar teaching activities in other subject areas.
Flipping the electronics lab: Learning upper division electronics at home
Authors: Rasnow Brian
Published: September 2024

A junior-level four-unit electronics curriculum is described in which students learn by building their own automated electronic test equipment and performing a rigorous suite of electronics experiments outside the classroom. Each student builds an electronics “workbench” based on an Arduino Nano microcontroller under the control of a software scripting environment (in our case, MATLAB). In the course of their work, students (1) construct a DC power supply and function generator and iteratively add programmable serial interfaces; (2) create an oscilloscope and spectrum analyzer that provides real-time displays of two analog channels for measurement of AC voltage amplitudes, frequency, and phase difference; (3) automate measurements of device I–V curves and transistor gain; (4) design, build, and characterize audio amplifiers and filters through measurement of time constants and frequency responses; and (5) compare the measured and simulated Bode plots. Mixing unconventional topics such as automation, numerical simulation, and programming with basic electronics removes the drudgery of data collection and provides more exposure, repetition, and organization of key concepts. Without being restricted to making measurements within the imposed lab schedule, students can work where and when they are able, repeat automated experiments in seconds, and continue exploring electronics with their workbench. After completing this course, our students demonstrate more confidence and capability with integrating electronics, automation, and programming into other projects and in improving existing systems. Likewise, students glean hands-on experience with scripting repetitive activities, saving enormous effort in their data-gathering work and leaving more time for analysis and creativity.
Resource Letter: Synthesis of the elements in stars
Authors: Spyrou Artemis
Published: September 2024

This Resource Letter provides a guide to the literature on the field of nuclear astrophysics, and particularly the origin of the elements. Nuclear astrophysics is a multidisciplinary field that aims at understanding where everything we see around us comes from and how it came to be. Astronomical observations, astrophysics modeling, and nuclear physics experiment and theory come together to answer important questions like: Where and how are the elements created? How do stars evolve? What drives the different types of stellar explosions? What is left behind after the cataclysmic death of a star? This Resource Letter presents our current understanding of the origin of the various chemical elements, together with modern research and new developments in the field, with a particular focus on the measurement of nuclear properties for astrophysical applications.
Loss of SELENOW aggravates muscle loss with regulation of protein synthesis and the ubiquitin-proteasome system
Authors: Yang Jia-Cheng , Liu Meng , Huang Rong-Hui , Zhao Ling , Niu Qin-Jian , Xu Ze-Jing , Wei Jin-Tao , Lei Xin Gen , Sun Lv-Hui
Published: September 2024

Sarcopenia is characterized by accelerated muscle mass and function loss, which burdens and challenges public health worldwide. Several studies indicated that selenium deficiency is associated with sarcopenia; however, the specific mechanism remains unclear. Here, we demonstrated that selenoprotein W (SELENOW) containing selenium in the form of selenocysteine functioned in sarcopenia. SELENOW expression is up-regulated in dexamethasone (DEX)–induced muscle atrophy and age-related sarcopenia mouse models. Knockout (KO) of SELENOW profoundly aggravated the process of muscle mass loss in the two mouse models. Mechanistically,
SELENOW
KO suppressed the RAC1-mTOR cascade by the interaction between SELENOW and RAC1 and induced the imbalance of protein synthesis and degradation. Consistently, overexpression of SELENOW in vivo and in vitro alleviated the muscle and myotube atrophy induced by DEX. SELENOW played a role in age-related sarcopenia and regulated the genes associated with aging. Together, our study uncovered the function of SELENOW in age-related sarcopenia and provides promising evidence for the prevention and treatment of sarcopenia.
Submicroscopic magnetite may be ubiquitous in the lunar regolith of the high-Ti region
Authors: Cao Zhi , Guo Zhuang , Li Chen , Zhao Sizhe , Li Yang , He Qi , Wen Yuanyun , Xiao Zhiyong , Li Xiongyao , Xiao Long , Li Lifang , Wang Junhu , Liu Jianzhong
Published: September 2024

Magnetite is rare on the Moon. The ubiquitous presence of magnetite in lunar soil has been hypothesized in previous Apollo Mössbauer spectroscopy and electron spin resonance studies, but there is currently no mineralogical evidence to prove it. Here, we report a large number of submicroscopic magnetite particles embedded within iron-sulfide on the surface of Chang’e-5 glass, with a close positive correlation between magnetite content and the TiO
2
content of the surrounding glass. The morphology and mineralogy of the iron-sulfide grains suggest that these magnetite particles formed via an impact process between iron-sulfide droplets and silicate glass melt, and ilmenite is necessary for magnetite formation. Magnetite in lunar glass is a potential candidate for the “magnetite-like” phase detected in the Apollo era and suggests that impact-induced submicroscopic magnetite may be ubiquitous in high-Ti regions of the Moon. Moreover, these impact-induced magnetite particles may be crucial for understanding the lunar magnetic anomalies and mineral components of the deep Moon.
Generation and characterization of giant panda induced pluripotent stem cells
Authors: Liu Yuliang , Zhang Shihao , Zou Gaoyang , An Junhui , Li Yuan , Lin Danni , Wang Donghui , Li Yan , Chen Jiasong , Feng Tongying , Li Hongyan , Chen Yijiao , Zhang Mingyue , Kumar Manish , Wang Luqin , Hou Rong , Liu Jing
Published: September 2024

The giant panda (
Ailuropoda melanoleuca
) stands as a flagship and umbrella species, symbolizing global biodiversity. While traditional assisted reproductive technology faces constraints in safeguarding the genetic diversity of giant pandas, induced pluripotent stem cells (iPSCs) known for their capacity to differentiate into diverse cells types, including germ cells, present a transformative potential for conservation of endangered animals. In this study, primary fibroblast cells were isolated from the giant panda, and giant panda iPSCs (GPiPSCs) were generated using a non-integrating episomal vector reprogramming method. Characterization of these GPiPSCs revealed their state of primed pluripotency and demonstrated their potential for differentiation. Furthermore, we innovatively formulated a species-specific chemically defined FACL medium and unraveled the intricate signaling pathway networks responsible for maintaining the pluripotency and fostering cell proliferation of GPiPSCs. This study provides key insights into rare species iPSCs, offering materials for panda characteristics research and laying the groundwork for in vitro giant panda gamete generation, potentially aiding endangered species conservation.
South American monsoon intensification during the last millennium driven by joint Pacific and Atlantic forcing
Authors: Lyu Zhiqiang , Vuille Mathias , Goosse Hugues , Orrison Rebecca , Novello Valdir F. , Cruz Francisco W. , Stríkis Nicolás M. , Cauhy Julio
Published: September 2024

The South American summer monsoon (SASM) profoundly influences tropical South America’s climate, yet understanding its low-frequency variability has been challenging. Climate models and oxygen isotope data have been used to examine the SASM variability over the last millennium (LM) but have, at times, provided conflicting findings, especially regarding its mean-state change from the Medieval Climate Anomaly to the Little Ice Age. Here, we use a paleoclimate data assimilation (DA) method, combining model results and δ
18
O observations, to produce a δ
18
O-enabled, dynamically coherent, and spatiotemporally complete austral summer hydroclimate reconstruction over the LM for tropical South America at 5-year resolution. This reconstruction aligns with independent hydroclimate and δ
18
O records withheld from the DA, revealing a centennial-scale SASM intensification during the MCA-LIA transition period, associated with the southward shift of the Atlantic Intertropical Convergence Zone and the strengthening Pacific Walker circulation (PWC). This highlights the necessity of accurately representing the PWC in climate models to predict future SASM changes.
Prediction of immunotherapy response using mutations to cancer protein assemblies
Authors: Kong JungHo , Zhao Xiaoyu , Singhal Akshat , Park Sungjoon , Bachelder Robin , Shen Jeanne , Zhang Haiyu , Moon Jimin , Ahn Changho , Ock Chan-Young , Carter Hannah , Ideker Trey
Published: September 2024

While immune checkpoint inhibitors have revolutionized cancer therapy, many patients exhibit poor outcomes. Here, we show immunotherapy responses in bladder and non–small cell lung cancers are effectively predicted by factoring tumor mutation burden (TMB) into burdens on specific protein assemblies. This approach identifies 13 protein assemblies for which the assembly-level mutation burden (AMB) predicts treatment outcomes, which can be combined to powerfully separate responders from nonresponders in multiple cohorts (e.g., 76% versus 37% bladder cancer 1-year survival). These results are corroborated by (i) engineered disruptions in the predictive assemblies, which modulate immunotherapy response in mice, and (ii) histochemistry showing that predicted responders have elevated inflammation. The 13 assemblies have diverse roles in DNA damage checkpoints, oxidative stress, or Janus kinase/signal transducers and activators of transcription signaling and include unexpected genes (e.g., PIK3CG and FOXP1) for which mutation affects treatment response. This study provides a roadmap for using tumor cell biology to factor mutational effects on immune response.
Molecular basis of TMED9 oligomerization and entrapment of misfolded protein cargo in the early secretory pathway
Authors: Xiao Le , Pi Xiong , Goss Alissa C. , El-Baba Tarick , Ehrmann Julian F. , Grinkevich Elizabeth , Bazua-Valenti Silvana , Padovano Valeria , Alper Seth L. , Carey Dominique , Udeshi Namrata D. , Carr Steven A. , Pablo Juan Lorenzo , Robinson Carol V. , Greka Anna , Wu Hao
Published: September 2024

Intracellular accumulation of misfolded proteins causes serious human proteinopathies. The transmembrane emp24 domain 9 (TMED9) cargo receptor promotes a general mechanism of cytotoxicity by entrapping misfolded protein cargos in the early secretory pathway. However, the molecular basis for this TMED9-mediated cargo retention remains elusive. Here, we report cryo–electron microscopy structures of TMED9, which reveal its unexpected self-oligomerization into octamers, dodecamers, and, by extension, even higher-order oligomers. The TMED9 oligomerization is driven by an intrinsic symmetry mismatch between the trimeric coiled coil domain and the tetrameric transmembrane domain. Using frameshifted Mucin 1 as an example of aggregated disease-related protein cargo, we implicate a mode of direct interaction with the TMED9 luminal Golgi-dynamics domain. The structures suggest and we confirm that TMED9 oligomerization favors the recruitment of coat protein I (COPI), but not COPII coatomers, facilitating retrograde transport and explaining the observed cargo entrapment. Our work thus reveals a molecular basis for TMED9-mediated misfolded protein retention in the early secretory pathway.
CheB localizes to polar receptor arrays during repellent adaptation
Authors: Fukuoka Hajime , Nishitani Keisuke , Deguchi Taiga , Oshima Taketo , Uchida Yumiko , Hamamoto Tatsuki , Che Yong-Suk , Ishijima Akihiko
Published: September 2024

Adaptation of the response to stimuli is a fundamental process for all organisms. Here, we show that the adaptation enzyme CheB methylesterase of
Escherichia coli
assembles to the ON state receptor array after exposure to the repellent
l
-isoleucine and dissociates from the array after adaptation is complete. The duration of increased CheB localization and the time of highly clockwise-biased flagellar rotation were similar and depended on the strength of the stimulus. The increase in CheB at the receptor array and the decrease in cytoplasmic CheB were both ~100 molecules, which represents 15 to 20% of the total cellular content of CheB. We confirmed that the main binding site for CheB in the ON state array is the P2 domain of phosphorylated CheA, with a second minor site being the carboxyl-terminal pentapeptide of the serine chemoreceptor. Thus, we have been able to quantify the regulation of the signal output of the receptor array by the intracellular dynamics of an adaptation enzyme.
Detecting the dimensionality of genuine multiparticle entanglement
Authors: Cobucci Gabriele , Tavakoli Armin
Published: September 2024

Complex forms of quantum entanglement can arise in two qualitatively different ways: either between many qubits or between two particles with higher-than-qubit dimension. While both the many-qubit frontier and the high-dimension frontier are well established, state-of-the-art quantum technology is becoming increasingly able to create and manipulate entangled states that simultaneously feature many particles and high dimension. Here, we investigate generic states that can be considered both genuinely high-dimensional and genuine multiparticle entangled. We consider a natural quantity that characterizes this key property. To detect it, we develop three different classes of criteria. These enable us both to probe the ultimate noise tolerance of this form of entanglement and to make detection schemes using sparse or even minimal measurement resources. The approach provides a simple way of benchmarking entanglement dimensionality in the multiparticle regime and general, platform-independent, detection methods that readily apply to experimental use.
Subset-specific mitochondrial stress and DNA damage shape T cell responses to fever and inflammation
Authors: Heintzman Darren R. , Sinard Rachael C. , Fisher Emilie L. , Ye Xiang , Patterson Andrew R. , Elasy Joel H. , Voss Kelsey , Chi Channing , Sugiura Ayaka , Rodriguez-Garcia Gabriel J. , Chowdhury Nowrin U. , Arner Emily N. , Krystoviak Evan S. , Mason Frank M. , Toudji Yasmine T. , Steiner KayLee K. , Khan Wasay , Olson Lana M. , Jones Angela L. , Hong Hanna S. , Bass Lindsay , Beier Katherine L. , Deng Wentao , Lyssiotis Costas A. , Newcomb Dawn C. , Bick Alexander G. , Rathmell W. Kimryn , Wilson John T. , Rathmell Jeffrey C.
Published: September 2024

Heat is a cardinal feature of inflammation, yet its impacts on immune cells remain uncertain. We show that moderate-grade fever temperatures (39°C) increased murine CD4 T cell metabolism, proliferation, and inflammatory effector activity while decreasing regulatory T cell suppressive capacity. However, heat-exposed T helper 1 (T
H
1) cells selectively developed mitochondrial stress and DNA damage that activated Trp53 and stimulator of interferon genes pathways. Although many T
H
1 cells subjected to such temperatures died, surviving T
H
1 cells exhibited increased mitochondrial mass and enhanced activity. Electron transport chain complex 1 (ETC1) was rapidly impaired under fever-range temperatures, a phenomenon that was specifically detrimental to T
H
1 cells. T
H
1 cells with elevated DNA damage and ETC1 signatures were also detected in human chronic inflammation. Thus, fever-relevant temperatures disrupt ETC1 to selectively drive apoptosis or adaptation of T
H
1 cells to maintain genomic integrity and enhance effector functions.