Design Of Devices Research Articles

One-hundred Consecutive Physician-Modified Fenestrated Endovascular Aneurysm Repair of Pararenal and Thoracoabdominal Aortic Aneurysms Using the Terumo TREO Stent Graft

ObjectiveFenestrated endovascular aortic aneurysm repair (FEVAR) has been widely applied for the treatment of pararenal (PAA) and thoracoabdominal aortic aneurysms (TAAA). If custom-made devices or off-the-shelf devices are not available, physician-modified endografts (PMEG) are an alternative device option. Several different endograft platforms have been used for PMEG; however, minimal data exists on utilizing the Terumo TREO Abdominal stent-graft system in this setting. The purpose of this study was to evaluate our single-center experience treating PAA and TAAA with a physician-modified FEVAR using the TREO platform. MethodsA prospective database of consecutive patients with PAA and TAAA treated at a single-center with a FEVAR utilizing a PMEG device between March 2021 and September 2023 was queried for those having a Terumo TREO device implanted. Demographics, operative details, and postoperative complications were analyzed. Rates of technical success, type I or III endoleak, branch vessel status, reintervention, and 2-year survival were also assessed. ResultsOf the 153 patients who underwent FEVAR with a PMEG device during the study period, 100 had repair using a Terumo TREO stent-graft. The mean age of the cohort was 73.7±7.0years with the majority suffering from hypertension (n=94, 94%), coronary artery disease (n=51, 51%), and COPD (n=40, 40%). Thirty-four patients (34%) had a prior failed EVAR device in place. Mean aneurysm size was 66.0±13.7mm, with 58 (50%) patients classified as PAA and 30 (30%) patients as an extent IV TAAA. Six (6%) patients presented with symptomatic/ruptured aneurysms. The average number of target arteries incorporated per patient was 3.8±0.6. Overall technical success was 99%, procedure time was 218±116 minutes, contrast volume was 82±21mL, and cumulative air kerma was 3,054±1,560mGy. Postoperative complications were present in 20 patients (20%) and 2 patients (2%) died within 30-days. Rates of type I or III endoleak, branch vessel stenosis/occlusion, and reintervention were 2%, 1%, and 7%, respectively. Two-year overall survival was 87%. ConclusionsTreatment of pararenal and extent IV TAAA using a physician-modified fenestrated Terumo TREO endograft is safe and effective. This large, early experience using the Terumo TREO platform supports preferential use of this device in this setting due to the device design and low likelihood of type I or III endoleak.

InP Crystal Phase Heterojunction Transistor with a Vertical Gate-All-Around Structure.

Crystal phase transitions can form a new type of heterojunction with different atomic arrangements in the same material: crystal phase heterojunction (CPHJ). The CPHJ has an inherently strong impact on band engineering without concerns over critical thicknesses with misfit dislocations and a semiconductor-metal transition. In-plane CPHJ was recently demonstrated in two-dimensional (2D) transition-metal dichalcogenide (TMD) materials and utilized for conventional planar field-effect transistor applications. However, scalability such as gate electrostatic control, miniaturization, and multigate structure have been limited because of the geometrical issue. Here, we demonstrated a transistor using the CPHJ with a vertical gate-all-around structure by forming a CPHJ in conventional III-V semiconductors. The CPHJ, composed of wurtzite InP nanowires with zincblende InP substrates, showed an atomically flat heterojunction without dislocations and indicated a Type-II band discontinuity across the junction. The CPHJ transistor had moderate to good gate electrostatic controllability with high on-state currents and transconductance. The CPHJ offer will provide a new switching mechanism and add a new junction and device design choice to the long history of transistors.

Recent Progress of Quantum Dots Light-Emitting Diodes: Materials, Device Structures, and Display Applications.

Colloidal quantum dots (QDs), as a class of 0D semiconductor materials, have generated widespread interest due to their adjustable band gap, exceptional color purity, near-unity quantum yield, and solution-processability. With decades of dedicated research, the potential applications of quantum dots have garnered significant recognition in both the academic and industrial communities. Furthermore, the related quantum dot light-emitting diodes (QLEDs) stand out as one of the most promising contenders for the next-generation display technologies. Although QD-based color conversion films are applied to improve the color gamut of existing display technologies, the broader application of QLED devices remains in its nascent stages, facing many challenges on the path to commercialization. This review encapsulates the historical discovery and subsequent research advancements in QD materials and their synthesis methods. Additionally, the working mechanisms and architectural design of QLED prototype devices are discussed. Furthermore, the review surveys the latest advancements of QLED devices within the display industry. The narrative concludes with an examination of the challenges and perspectives of QLED technology in the foreseeable future.

Assessment of particle image velocimetry applied to high-speed organic vapor flows

Compressible flows of fluids whose thermophysical properties are related by complex equations are quantitatively and can be qualitatively different from high-speed flows of ideal gases. Nonideal compressible fluid dynamics (NICFD) is concerned with these fluid flows, which are relevant in many processes and power and propulsion systems. Typically, NICFD effects occur if the fluid is an organic compound and its vapor state is close to the vapor–liquid critical point, at high-reduced temperature and pressure (even supercritical). Current design and analysis of devices operating in the nonideal compressible regime demand for validated simulation software, characterized in terms of uncertainty. Moreover, experiments are needed to further validate related theory. Experimental data are limited as generating and measuring these flows is challenging given their high pressure or temperature or both. In addition, flows of organic compounds can be flammable, can thermally decompose, and sealing may demand for special materials. Recently, more research has been devoted to the measurement of these flows using both intrusive and less intrusive techniques relying on optical access and lasers. The transparency and refractive properties of these dense vapors pose additional problems. The ORCHID (organic Rankine cycle hybrid integrated device) at the Aerospace Propulsion and Power Laboratory of Delft University of Technology is a closed-loop facility, used to generate a continuous nonideal supersonic flow of siloxane MM with the vapor at 4bar\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ extrm{bar}}}$$\\end{document} and 220 °C at the inlet of the test section. Within this work, we have employed particle image velocimetry for the first time to obtain the velocity field in a de Laval nozzle in such flows. Measured velocity fields (expanded uncertainty within 1.1% of the maximum velocity) have been compared with those resulting from a CFD simulation. The comparison between experimental and simulated data is satisfactory, with deviation ranging from 0.1 to 10 % from the throat to the outlet, respectively. This discrepancy is attributed to hardware limitations, which will be overcome in the future experiments. The feasibility of PIV with uncontrolled but fixed seeding density to measure high-speed vapors of organic vapors has been demonstrated, and future experimental campaigns will target flows for which nonideal effects are more pronounced, other paradigmatic configurations, and improvements to the measurement techniques.

Opportunities and Challenges for Augmented Reality in Family Caregiving: Qualitative Video Elicitation Study.

Although family caregivers play a critical role in care delivery, research has shown that they face significant physical, emotional, and informational challenges. One promising avenue to address some of caregivers' unmet needs is via the design of digital technologies that support caregivers' complex portfolio of responsibilities. Augmented reality (AR) applications, specifically, offer new affordances to aid caregivers as they perform care tasks in the home. This study explored how AR might assist family caregivers with the delivery of home-based cancer care. The specific objectives were to shed light on challenges caregivers face where AR might help, investigate opportunities for AR to support caregivers, and understand the risks of AR exacerbating caregiver burdens. We conducted a qualitative video elicitation study with clinicians and caregivers. We created 3 video elicitations that offer ways in which AR might support caregivers as they perform often high-stakes, unfamiliar, and anxiety-inducing tasks in postsurgical cancer care: wound care, drain care, and rehabilitative exercise. The elicitations show functional AR applications built using Unity Technologies software and Microsoft Hololens2. Using elicitations enabled us to avoid rediscovering known usability issues with current AR technologies, allowing us to focus on high-level, substantive feedback on potential future roles for AR in caregiving. Moreover, it enabled nonintrusive exploration of the inherently sensitive in-home cancer care context. We recruited 22 participants for our study: 15 clinicians (eg, oncologists and nurses) and 7 family caregivers. Our findings shed light on clinicians' and caregivers' perceptions of current information and communication challenges caregivers face as they perform important physical care tasks as part of cancer treatment plans. Most significant was the need to provide better and ongoing support for execution of caregiving tasks in situ, when and where the tasks need to be performed. Such support needs to be tailored to the specific needs of the patient, to the stress-impaired capacities of the caregiver, and to the time-constrained communication availability of clinicians. We uncover opportunities for AR technologies to potentially increase caregiver confidence and reduce anxiety by supporting the capture and review of images and videos and by improving communication with clinicians. However, our findings also suggest ways in which, if not deployed carefully, AR technologies might exacerbate caregivers' already significant burdens. These findings can inform both the design of future AR devices, software, and applications and the design of caregiver support interventions based on already available technology and processes. Our study suggests that AR technologies and the affordances they provide (eg, tailored support, enhanced monitoring and task accuracy, and improved communications) should be considered as a part of an integrated care journey involving multiple stakeholders, changing information needs, and different communication channels that blend in-person and internet-based synchronous and asynchronous care, illness, and recovery.

Chiral Luminophore Guided Self-Assembly of Achiral Block Copolymers for the Amplification of Circularly Polarized Luminescence.

This work aims to examine the effect of self-assembly on the chiroptic responses of the achiral block copolymer (BCP) polystyrene-b-poly(ethylene oxide) (PS-b-PEO) associated with chiral luminophores, (R)- or (S)-1,1'-bi-2-naphthol ((R)- or (S)-BINOL), through hydrogen bonding. With the formation of a well-ordered helical phase (H*), significantly induced circular dichroism (ICD) signals for the PEO block in the mixture can be found. Most interestingly, a remarkable amplification with an extremely large dissymmetry factor of luminescence (glum) from 10-3 to 0.3 (i.e., induced circular polarized luminescence (iCPL) behavior) for the chiral BINOLs in the mixture can be achieved by the formation of the helical phase (H*) via mesochiral self-assembly. As a result, by taking advantage of BCP for mesochiral self-assembly, it is feasible to create a nanostructured monolith with substantial optical activities, offering promising applications in the design of chiroptic devices.

Elasto-inertial particle focusing in sinusoidal microfluidic channels.

Dean flow existing in sinusoidal channels could enhance the throughput and efficiency for elasto-inertial particle focusing. However, the fundamental mechanisms of elasto-inertial focusing in sinusoidal channels are still unclear. This work employs four microfluidic devices with symmetric and asymmetric sinusoidal channels to explore the elasto-inertial focusing mechanisms over a wide range of flow rates. The effects of rheological property, flow rate, sinusoidal channel curvature, particle size, and asymmetric geometry on particle focusing performance are investigated. It is intriguing to find that the Dean flow makes a substantial contribution to the particle elasto-inertial focusing. The results illustrate that a better particle focusing performance and a faster focusing process are obtained in the sinusoidal channel with a small curvature radius due to stronger Dean flow. In addition, the particle focusing performance is also related to particle diameter and rheological properties, the larger particles show a better focusing performance than smaller particles, and the smaller flow rate is required for particles to achieve stable focusing at the outlet in the higher concentration of polyvinylpyrrolidone solutions. Our work offers an increased knowledge of the mechanisms of elasto-inertial focusing in sinusoidal channels. Ultimately, these results provide supportive guidelines into the design and development of sinusoidal elasto-inertial microfluidic devices for high-performance focusing.

Circular economy for medical devices: Barriers, opportunities and best practices from a design perspective

In an era of electronics-driven healthcare, the disposability of many medical devices raises environmental concerns. Transitioning these devices towards a circular economy, involving practices like reuse, remanufacturing, and recycling, holds promise. Our paper explores this transition through desk research, literature review, and expert interviews, examining the current state of circular design in electronic medical devices. We unveil barriers, opportunities, and design recommendations for circularization. First, we highlight the circularity potential of medical devices currently on the market, implementing e.g. refuse, reuse, recycle, etc. Second, we present barriers for circular medical device design, (e.g. (perceived) safety and infection risks, (perceived) regulatory difficulties, financial constraints, and difficulties in collection and separation) and opportunities to overcome these barriers. Finally, we present 29 design-specific recommendations for creating circular medical devices. Our insights into circular healthcare practices urge design engineers to integrate sustainable principles into medical device development without compromising safety, quality, or functionality.

A Novel 4H-SiC Asymmetric MOSFET with Step Trench.

In this article, a silicon carbide (SiC) asymmetric MOSFET with a step trench (AST-MOS) is proposed and investigated. The AST-MOS features a step trench with an extra electron current path on one side, thereby increasing the channel density of the device. A thick oxide layer is also employed at the bottom of the step trench, which is used as a new voltage-withstanding region. Furthermore, the ratio of the gate-to-drain capacitance (Cgd) to the gate-to-source capacitance (Cgs) is significantly reduced in the AST-MOS. As a result, the AST-MOS compared with the double-trench MOSFET (DT-MOS) and deep double-trench MOSFET (DDT-MOS), is demonstrated to have an increase of 200 V and 50 V in the breakdown voltage (BV), decreases of 21.8% and 10% in the specific on-resistance (Ron,sp), a reduction of about 1 V in the induced crosstalk voltage, and lower switching loss. Additionally, the trade-off between the resistance of the JFET region (RJFET) and the electric field in the gate oxide (Eox) is studied for a step trench and a deep trench. The improved performances suggest that a step trench is a competitive option in advanced device design.

Large Language Model-Based AI Agent for Organic Semiconductor Devices Research.

Large language models (LLMs) have attracted widespread attention recently, however, their application in specialized scientific fields still requires deep adaptation. In this work, we designed an artificial intelligence (AI) agent for organic field effect transistors (OFETs) by integrating the GPT-4 model with well-trained machine learning (ML) algorithms. It can efficiently extract the experimental parameters of OFETs from scientific literature and reshape them into a structured database, achieving precision and recall rates both exceeding 92%. Combined with well-trained ML models, this AI agent can further provide targeted guidance and suggestions for device design. With prompt engineering and human-in-loop strategies, the agent extracted sufficient information of 709 OFETs from 277 research articles across different publishers and gathered them into a standardized database containing more than 10000 device parameters. Using this database, we trained a ML model based on XGBoost for device performance judgment. Combined with the interpretation of the high-precision model, the agent has provided a feasible optimization scheme that has tripled the charge transport properties of DP-DTT OFETs. Our work is an effective practice of LLMs in the field of organic optoelectronic devices and expands the research paradigm of organic optoelectronic materials and devices. This article is protected by copyright. All rights reserved.

Nano PDA@Tur-Modified Piezoelectric Sensors for Enhanced Sensitivity and Energy Harvesting.

Tourmaline is known for its natural negative ion effect and far-infrared radiation function, which promote human blood circulation, relieve pain, regulate the endocrine system, and enhance immunity and other functions. These functions motivate the use of this material for enhanced sensitivity of wearable sensors. In this work, taking advantage of the unique multifunctions of tourmaline nanoparticles (Tur), highly boosted piezoelectricity was achieved by incorporating polydopamine (PDA)-modified Tur in PVDF. The PDA@Tur nanofillers not only effectively increased the β-phase content of PVDF but also played a major role in significantly enhancing piezoelectricity, wettability, elasticity, air permeability, and stability of the piezoelectric sensors. Especially, the maximum output voltage of the fiber membrane with 0.5 wt % PDA@Tur reached 31.0 V, being 4 times that of the output voltage of the pure PVDF fiber membrane. Meanwhile, the sensitivity reached 0.7011 V/kPa at 1-10 N, which was 3.6 times that of pure PVDF film (0.196 V/kPa). The power intensity reached 8 μW/cm2, being 5.55 times that of the pristine PVDF PENG (1.44 μW/cm2), and the piezoelectric coefficient from d33 m/PFM is 5.5 pC/N, higher than that of pristine PVDF PENG (3.1 pC/N). Output signal graphs corresponding to flapping, finger, knee, and elbow movements were detected. The response/recovery time of the sensor device was 24/19 ms. The piezoelectric nanogenerator (PENG) was capable of charging multiple capacitors to 2 V within a short time and lighting up 15 light-emitting diodes bulbs (LEDs) simultaneously with a single beat. In addition, a 4 × 4 row-column multiplexed sensor array was made of PENGs, which showed distinct responses to different stress areas in different sensor modules. This study demonstrated high-performance PDA@Tur PVDF-based PENG being capable of energy harvesting and sensing, providing a guideline for the design and buildup of wearable self-powered devices in healthcare and human-computer interaction.

A Comprehensive Analysis of Reported Adverse Events and Device Failures Associated with Esophageal Self-Expandable Metal Stents: An FDA MAUDE Database Study.

Esophageal Stents are used to maintain esophageal lumen patency in esophageal strictures caused by intrinsic and/or extrinsic malignancies and the occlusion of concomitant esophageal fistulas. While data on the efficacy and safety of esophageal stents exist, comprehensive evaluation of adverse events is limited. The aim of this study is to investigate the reported adverse events and device failures associated with esophageal self-expandable metal stents (SEMS) using the FDA's Manufacturer and User Facility Device Experience (MAUDE) database. Post-marketing surveillance data for the esophageal SEMSs were analyzed using the FDA's MAUDE database from January 2014 to December 10, 2023. The outcomes of interest were patient-related adverse events and device failures. Statistical analysis was performed using Microsoft Excel 2010 and SPSS. Pooled numbers and percentages were calculated for each adverse event. Continuous variables underwent analysis using a two-tailed student t test, and significance was set to p ≤ 0.05. During the study period, 548 MAUDE reports revealed 873 device failures and 186 patient-related adverse events. The most common device issues were stent activation, positioning, or separation problems (4 n = 403; 46.2%), followed by device detachment or migration (n = 109, 12.5%), and material problems (n = 93, 10.7%). Patient complications included dysphagia/odynophagia (10%), perforation, pain, and bleeding (each 7.6%). The most common device failures in over-the-wire (OTW) stents and through-the-scope (TTS) stents were activation, positioning, or separation problems (TTS: n = 183, 52.6% vs OTW: n = 220, 41.9%). Compared to OTW stents, TTS stents had higher migration and breakage (13.5% vs. 11.8%, p = 0.24), and (9.2% vs. 6.7%, p = 0.08) respectively, while OTW stents had more challenges with stent advancement or removal (5.1% vs. 0.3%, p < 0.001 and 4.6% vs 3.4%, p = 0.19, respectively) and material problems (14.7% vs. 4.6%, p < 0.001). Activation, positioning, and separation problems were the most frequent device failures in fully covered (FC) and partially covered (PC) stents (FC: n = 62, 32.8%, PC: n = 168, 43.5%). FC stents had higher migration rates (20.6% vs 9.8%, p < 0.001), while PC stents exhibited more material problems (17.4% vs. 5.8%, p < 0.001) and difficulties with advancing the stents (6.7% vs. 0%, p < 0.001). Our examination showed a prevalence of reported device complications associated with stent activation, positioning, and separation problems. Dysphagia or odynophagia emerged as the most frequently reported patient complication. Furthermore, our analysis, provides insights into TTS vs. OTW and FC vs. PC esophageal SEMSs, enabling endoscopists and manufacturers to better understand adverse events and potentially optimize device design for future iterations.

Advancing LED technology: the FDCSP element’s breakthrough in mini and micro-LED packaging and backlight module enhancement

In this research, we introduce an advanced methodology for the calculation of bulk light sources tailored for free-form surface design, focusing on the principle of energy conservation. This method is especially relevant for the evolving needs of micro-LED packaging, highlighting its potential in this burgeoning field. Our work includes the development of an algorithm for creating freeform-designed chip-scale package (FDCSP) components. These components seamlessly integrate LEDs and lenses, underscoring our commitment to advancing free-form surface design in chip-level packaging. By adhering to the principle of energy conservation, our approach facilitates a meticulous comparison of simulation outcomes with predefined target functions. This enables the iterative correction of discrepancies, employing layering techniques to refine the design until the simulated results closely align with our goals, as demonstrated by an appropriate difference curve. The practical application of these simulations leads to the innovative design of FDCSP devices. Notably, these devices are not just suitable for traditional applications in backlight modules but are explicitly optimized for the emerging sector of micro-LED packaging. Our successful demonstration of these FDCSP devices within backlight modules represents a significant achievement. It underscores the effectiveness of our design strategy and its expansive potential to transform micro-LED packaging solutions. This research not only contributes to the theoretical understanding of energy conservation in lighting design but also paves the way for groundbreaking applications in micro-LED and backlight module technologies.

Tunable and enhanced thermoelectric properties in transition metal–terpyridine complex based molecular devices

Using the density function theory in combination with the non-equilibrium Green’s function method, the thermoelectric properties of molecular devices based on transition metal–terpyridine complexes are investigated. The results show that their thermoelectric properties can be significantly improved by changing the transition metal and the twist angle of the complex molecule, which is caused by shifting the molecular energy levels, resulting in increased coupling strength between the electrodes and the central molecule. The ZT value of the Ru-containing molecular device can reach up to 0.9 at room temperature, which is three orders of magnitude greater than that of the graphene nanoribbons of the same width. In addition, its thermoelectric performance can be further promoted by suppressing phonon thermal conductance through enhanced isotope scattering. The ZT value of doped devices can reach up to 1.0 in the range of 300–700 K. This work may help in the design and fabrication of transition metal-containing twistable molecular devices and provide effective methods to regulate their thermoelectric properties.

Design and Experiment of Flexible Threshing Device with Variable Stiffness for Corn

In order to solve the problem of the high damage rate of corn with a high moisture content in the Huanghuaihai region, according to the mechanical characteristics of corn in the Huanghuaihai region, we designed a flexible threshing device with a threshing rasp bar and variable stiffness spring as the buffer carrier, and the elements of the device were nail teeth and a flexible threshing rasp bar, which could be replaced freely. The experiment was based on the threshing rotor speed, threshing gap, and spring stiffness as the influencing factors, with the grain breakage rate and the unthreshed rate as an indicator of three-factor three-level experiments, and in October in Zibo through bench experiments, to determine the best parameter combinations. When the spring compression stiffness was 20.83 N/mm, the rotor speed was 375 r/min, and the gap of the concave plate was 45 mm, the grain breakage rate of the corn ear was 4.7%, and the unthreshed rate was 0.48%, which is in line with the relevant national standards.

Smart Gas Leakage Detector Using Arduino Gas Sensor

This project is carried out using the Methane Quality (MQ-2) sensor to detect Liquefied Petroleum Gas LPG, smoke and Carbon Monoxide (CO) leakage in the environment. The microcontroller used was an Arduino Uno for controlling the environmental temperature monitoring system. The results obtained from the sensor would be displayed on the 16x2 i2c Liquid Crystal Display (LCD). The new system with an Arduino microcontroller and MQ2 consists of the hardware design which includes the device design, as well as the software design which consist of the Arduino source code. They also consist of Internet of Things (IoT) enabled sensors, which work as a real-time indicator. After testing, we have 17.7% failure and 82.3% accuracy.

Design and development of an occlusion-free surface profile measurement device

The prevalent surface profile measurement techniques in the sub-millimetre measurement scale, based on active triangulation (such as laser scanners), stereo vision and photometric stereo, may miss certain parts of the surface of the object due to occlusion. Occlusion occurs in these techniques as they rely on a top-view configuration, where the illumination rays and the surface profile lie on the same plane. In this study, a surface profile measurement device is designed and developed, which can generate occlusion-free measurements by adopting a side-view configuration. This proposed measurement technique is tested on a few surfaces, and the results are presented.

Flexible wavefront manipulation using exceptional points generated by non-interleaved metasurfaces

Precise modulation of the optical wavefront is the main way in which metasurfaces act, and the exceptional point (EP) topological phase provided by non-Hermitian metasurfaces offer an additional degree of freedom for the metasurface design. Here, we design an F-shaped non-interleaved metasurface whose unit cell consists of two basic resonators – a nanowire and a split ring resonator (SRR). By adjusting the strength and coupled-mode of these two resonators, the 2π phase accumulation enclosing the EP, the asymmetric transport properties, and the evolution of wavelength-dependent EP are observed. These properties allow for flexible wavefront manipulation in polarization, amplitude and wavelength dimensions. We simulate and demonstrate a spin-decoupled metasurface hologram, a dual-wavelength decoupled metasurface hologram, as well as a dual-wavelength metasurface for near-field nanoprinting and far-field holography. Non-Hermitian topological metasurfaces can be conveniently combined with other wavefront manipulation mechanisms, showing promising applications in the design of nanophotonic devices.

Comprehensive evaluation on deposition and heat transfer performance of the mixed tube bundle based on orthogonal experimental study

Deposition on heat exchange surfaces is an urgent problem to be solved to achieve efficient utilization of energy in thermal equipment. To mitigate deposition and the resultant heat attenuation, this work proposes a mixed tube bundle strategy of inserting attached cylinders behind the tube bundle, which can effectively meet the design requirements of high anti-deposition performance, high heat transfer efficiency, and low flow resistance. An integrated dynamic model for deposition is developed to elucidate the effect of ash particles on deposition, flow, and heat transfer characteristics. Based on the inverse distance weighting interpolation, a dynamic mesh smoothing technique is employed to simulate the evolving deposition layer on the heat transfer surface. In addition, the L16(43) orthogonal experimental design method is adopted to study the influence of the arrangement angle, diameter, and distance to the primary bundle of the attached cylinder on the overall performance, and determine the optimal scheme. The results show that deposition in the cases using the mixed tube bundle strategy has significantly decreased. The weakening effects of the attached cylinder on the deposition of small-medium particles and large-sized particles are due to the inhibition of vortex development in the gap of tube bundle and the deviation of the motion trajectory, respectively. The novel design exhibits the lowest deposition mass Mdep = 1.12 g and the best comprehensive performance PEC = 1.14 under the condition of the arrangement angle of 50°, the diameter of 10 mm, and the distance between the primary bundle of 5 mm. The obtained results can provide reference schemes and guidance for the optimization of the design of heat exchange equipment and accessory devices.

Resonance Raman studies on phonon softening, phonon lifetime, Fano resonance, and multipeak analysis of MoS2 nanoflakes

AbstractIn this study, the resonance Raman spectra of hydrothermally produced 2H‐MoS2 nanoflakes excited by a 633‐nm laser were examined. Spectral observations include both fundamental MoS2 modes and additional Raman lines, which arise from alterations in the energy states of the semiconductor owing to the incidence of laser radiation. Phonon softening and alterations in the phonon lifetime were computed for different laser powers. The Fano resonance, which causes asymmetry in the Raman spectral lines, was analyzed at different laser powers. The Fano line‐shape function is used to fit the asymmetry in the in‐plane vibrational mode whereas multi‐peak fitting using the Fano‐Lorentzian function is used to fit the out‐of‐the‐plane fundamental mode, which is coupled with “b” mode. A direct study of the electron–phonon interaction was carried out with the “b” mode. The shift in laser wavenumber was then investigated using the 2LA(M) modes observed in the resonance Raman spectra. These findings provide new optoelectronic device designers with an understanding of the intricate electron–phonon interactions in transition metal dichalcogenides.