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SSRN 2024年

作者： Webster, Samantha Jeong, Jihoon mogonye, Jon-Erik Zuback, James Liao, Shuheng Rocher, Julian Ehmann, Kornel Cao, Jian Department of Mechanical Engineering Northwestern University EvanstonIL60208 United States Texas A&M University United States Department of Materials Science & Engineering National Institute of Standards and Technology GaithersburgMD20852 United States

Advanced materials, better control methods, and unique toolpath planning strategies have recently been enabled through development of novel, in-situ monitoring techniques in laser powder-blown directed energy deposition (DED-LB). In-situ monitoring techniques have largely focused on melt pool monitoring and have typically been performed with off-axis or coaxially mounted cameras (e.g., infrared, two-color pyrometer, charge-coupled device (CCD), complementary metal-oxidesemiconductor (CmOS) which generate 2D data. While these techniques can have high spatial resolution, it can be challenging or expensive to implement high temporal resolution (> 200 Hz) measurements, which limits the performance of closed-loop process control. By implementing photodiodes as a functioning two-color pyrometer we established 415 Hz signals that were used to control melt pool temperature throughout a build by modulating laser power. This sensing capability enabled faster, less expensive control over the DED process. The control method was demonstrated by using Nickel alloy 718 (NI718) to build a multi-layered thin wall and a hollow cylinder. It was shown that the controller can compensate for both heat accumulation and heat loss over the geometry of a part by maintaining a steady-state melt pool temperature through laser modulation. An infrared camera was used to quantify the success of the controller through uniformity of thermal history as well as time spent in different temperature regions critical to NI718 properties. The microstructure of the uncontrolled and controlled builds showed stark differences in grain growth patterns and phase content. It was demonstrated that a more uniform thermal gradient was achieved when the photodiode controller was used in conjunction with a heated base plate. © 2024, The Authors. All rights reserved.

关键词： microstructure

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Collective Action and Entanglement of magnetically Active Liquid Crystal Elastomer Ribbons

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SSRN 2024年

作者： Dana, Asaf Benson, Christian Sivaperuman Kalairaj, manivannan Hellikson, Kayla George, Sasha m. Chimene, David C. Gibson, Jared A. Tasmim, Seelay Kohl, Phillip A. Li, Youli Abdelrahman, mustafa K. Patil, Vishal P. Ware, Taylor H. Department of Biomedical Engineering Texas A&M University College StationTX77843 United States Department of Materials Science and Engineering Texas A&M University College StationTX77843 United States Materials Research Laboratory University of California - Santa Barbara Santa BarbaraCA93106 United States Department of Mathematics University of California La Jolla San DiegoCA92093 United States

Interactions between active individuals in animal collectives lead to emergent responses that remain elusive in synthetic soft matter. Here, shape-morphing polymers serve to create bio-inspired transient solids that self-assemble with controlled mechanical properties and disassemble on demand. Dilute-suspensions of magnetic, heat-responsive liquid crystal elastomer ribbons mechanically interlock, inducing reversible aggregation. A mathematical model is developed that sheds light on the role of topological mechanisms in aggregation. Aggregation was favored for ribbons with moderate curvature as compared to flat ribbons or higher curvature ribbons. The ribbon suspensions reversibly transition between fluid- and solid-like states, exhibiting up to 6 orders-of-magnitude increase in the storage moduli of the entangled aggregates compared with the liquid dispersions. Controlled dissociation is induced by imparting kinetic energy to the individual ribbons at high magnetic field rotation speeds (>200 RPm). Imparting dynamic collective behaviors into synthetic systems may enable potential applications from bio-inspired soft robotics to injectable biomaterials. © 2024, The Authors. All rights reserved.

关键词： Kinetic energy

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4D printing of thermal responsive structure for environmentally adaptive radiative cooling and heating

Journal of Advanced Manufacturing and Processing

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Journal of Advanced manufacturing and Processing 2022年第2期4卷

作者： Liu, Yuchen Liu, Ruochen Qiu, Jingjing Wang, Shiren Department of Industrial and Systems Engineering Texas A&M University College StationTX United States Department of Materials Science and Engineering Texas A&M University College StationTX United States Department of Mechanical Engineering Texas Tech University LubbockTX United States

Four-dimensional (4D) printing, which combines a three-dimensional (3D) printing process with dynamic modulation of materials, provides a possible solution to achieve stimuli-responsive microstructure that exhibit more complex functionality. One of the potential applications for these stimuli-responsive hydrogels is switchable passive radiative cooling and warming. However, most current attempts are limited to mono-functionality, either radiative cooling or warming only. In this article, we demonstrate a double-side morphing flower structure for a dual functionality, switchable cooling or warming dependent on the environment. The morphing structure was designed with the aid of emissivity calculations and then fabricated by the 3D printing method. The transition between open-flower and close-flower states occurs at 32°C within a minute, resulting in ~35% emissivity difference between these two states. As a result, the power difference between inner layer and outer layer was as high as 22 W/m2 which is a function of pyramid bottom size. © 2021 American Institute of Chemical Engineers.

关键词： 3D printers

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In-situ curing of 3D printed freestanding thermosets

Journal of Advanced Manufacturing and Processing

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Journal of Advanced manufacturing and Processing 2022年第3期4卷

作者： Gao, Chongjie Qiu, Jingjing Wang, Shiren Department of Industrial and Systems Engineering Texas A&M University College StationTX United States Department of Mechanical Engineering Texas Tech University LubbockTX United States Department of Materials and Science Engineering Texas A&M University College StationTX United States

Direct-ink-writing (DIW) provides a high-efficiency way for thermoset printing while rapid in-situ curing has a significant role in manufacturing rate, quality, performance, and flexibility. In this review, in-situ curing methods that can be integrated into DIW were discussed, including frontal polymerization, electromagnetic heating, photochemistry, electron beam, and resistance heating curing. The in-situ process monitoring and curing kinetic analysis technologies such as differential scanning calorimetry (DSC), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), broadband dielectric spectroscopy (BDS), ultrasonic dynamic mechanical analysis (UDmA), fluorescence spectroscopy, were briefly presented. The working mechanism and features of these characterization measurements are studied. Furthermore, machine learning and other artificial intelligence tools used for the optimization of printing materials, topology design, printing path, and defect detection sensitivity are reviewed. Finally, some future research directions for the DIW and in-situ curing of thermosets are addressed. © 2022 American Institute of Chemical Engineers.

关键词： machine learning

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Photocatalytic Degradation of Perfluorooctanoic Acid by a Temperature Transformed metal-Organic Framework mIL-177-HT

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SSRN 2023年

作者： Wen, Yinghao Kirchon, Angelo Day, Gregory S. Lin, Hengyu Smith, mallory F. Yang, Yihao Boehme, Anne Ozdemir, Ray Osman K. Sharma, Virender K. ma, Xingmao Zhou, Hong-Cai Department of Civil and Environmental Engineering Texas A&M University College StationTX77843 United States Department of Chemistry Texas A&M University College StationTX77843 United States Framergy Inc. 800 Raymond Stotzer Pkwy College StationTX77945 United States Program for the Environment and Sustainability Department of Environmental and Occupational Health Texas A&M University College StationTX77843 United States Department of Materials Science and Engineering Texas A&M University College StationTX77843 United States

The prevalence of per- and polyfluoroalkyl substances (PFAS) in ground and surface water poses serious threats to public health. However, an effective destructive technology for PFAS remains elusive. Herein, we report the results of perfluorooctanoic acid (PFOA) degradation by a high temperature transformed, photocatalytic titanium-based metal-organic framework (mOF), mIL-177-HT, with infinite one-dimensional (1D) channels. mIL-177-HT removed 83% of PFOA within 24 hours with a 32% photo-induced defluorination rate. While the crystallinity and porosity were retained after photocatalysis, pore size distribution was altered after light irradiation due to PFAS adsorption and partial degradation. The results demonstrated the potential of a phase-transformable mOF for efficient PFAS removal but more importantly, the study revealed the key challenges for more effective use of photocatalytic mOF for PFAS removal: increasing the accessible adsorption sites of mOF for PFAS and improving its stability in neutral and alkaline water. © 2023, The Authors. All rights reserved.

关键词： Adsorption

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Inorganic Ions Activate Lineage-Specific Gene Regulatory Networks to Drive Stem Cells Differentiation

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SSRN 2023年

作者： Kersey, Anna L. Gaharwar, Akhilesh K. Singh, Irtisha Department of Biomedical Engineering College of Engineering Texas A&M University College StationTX77843 United States Department of Cell Biology and Genetics College of Medicine Texas A&M University College StationTX77843 United States Interdisciplinary Program in Genetics Texas A&M University College StationTX77843 United States Center for Remote Health Technologies and Systems Texas A&M University College StationTX77843 United States Department of Material Science and Engineering Dwight Look College of Engineering Texas A&M University College StationTX77843 United States

Ions released from inorganic biomaterials play a vital role in defining cell identity. However, the effect of inorganic ions on cellular functions has yet to be investigated at the transcriptomic level, representing a critical knowledge gap in the development of next-generation of bioactive materials. To address this gap, we investigated the impact of various inorganic ions including silver, copper, titanium, and platinum on human stem cells. Our finding showed that silver and copper induce osteogenic and chondrogenic differentiation respectively, through enrichment of ion-dependent signaling pathways. Specifically, silver effectively induced Wnt and mAPK signaling, which are vital for osteogenesis. On the other hand, copper specifically stimulated TGFβ signaling, while suppressing JAK-STAT signaling, thereby promoting chondrogenesis. In contrast, platinum, tantalum, and titanium ions didn't stimulate regenerative responses. Titanium displayed minimal gene expression changes, demonstrating its relative inertness, while platinum and tantalum induced oxidative stress. These findings are further supported by gene and protein level validation using traditional techniques. Together, our findings highlight the potential of inorganic biomaterials in revolutionizing tissue regeneration strategies, which currently rely largely on growth factors and small molecule therapeutics. © 2023, The Authors. All rights reserved.

关键词： Stem cells

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Revisiting the Sgte Lattice Stability of Bcc Aluminum

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SSRN 2023年

作者： van de Walle, Axel Samanta, Sayan Nataraj, Chiraag Zhu, Siya Chen, Hantong Liu, Helena Arroyave, Raymundo School of Engineering Brown University ProvidenceRI02912 United States Dept. of Materials Science and Engineering Texas A&M University College StationTX77843 United States

The CALPHAD framework rests on the ability to assign well-defined free energies to all phases, including mechanically unstable ones. Given the experimental difficulties associated with the latter, researchers have turned to computational methods to obtain a theoretically justified definition of the free energy of mechanically unstable phases. Recently, a method called "inflection detection" has been shown to yield free energies that are broadly consistent with the current SGTE (Scientific Group Thermodata Europe) standard for pure elements, which were obtained through an extrapolation of stable solid solutions free energies towards unstable end members. Despite this general agreement, apparent failures for a few elements stand out, notably for the bcc-fcc enthalpy difference for the common element Al. Here we revisit the definition of the bcc Al enthalpy and show that a careful CALPHAD-based analysis of enthalpy trends in five different mechanically stable binary solid solutions in fact does agree very well with the inflection-detection approach. © 2023, The Authors. All rights reserved.

关键词： Free energy

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A Self-Powered Kinetic motion Sensor Fabricated from Electrospun mof-5/Pvdf-Trfe Composites Piezoelectric Nanogenerators

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SSRN 2024年

作者： Park, moon Sik Kim, min Ji Jeong, Ju Yeong Han, Do Young Kim, Soaram Hwang, Geon-Tae Yoo, Hocheon Lee, Eun Kwang Department of Chemical Engineering Pukyong National University Busan48513 Korea Republic of Department of Electrical and Computer Engineering Texas A&M University College StationTX77843 United States Department of Biomedical Engineering Texas A&M University College StationTX77843 United States Center for Remote Health Technologies and Systems Texas A&M University College StationTX77843 United States Department of Materials Science and Engineering Pukyong National University Busan48513 Korea Republic of Department of Electronic Engineering Gachon University 1342 Seongnam-daero Seongnam13120 Korea Republic of

Poly(vinylidene fluoride-co-trifluoroethylene) PVDF-TrFE is known for its low dielectric loss, high biocompatibility, safety, and durability. However, its piezoelectric performance alone is insufficient. In this study, we aim to enhance the piezoelectric performance by incorporating electrospinning and metal-organic framework-5 (mOF-5). Under high voltage conditions (15 kV), electrospinning is performed to increase the ratio of the highest dielectric constant β phase. Additionally, mOF-5, a porous material with high surface area and thermal stability, is added to form a metal-organic framework scaffold and create a micro-capacitor structure in the active layer. The power density of the 5 wt% mOF-5/PVDF-TrFE piezoelectric nanogenerator (PENG) obtained from the experiments exhibits excellent performance with a power density of 0.3 µWcm–2, which is 132 times higher than that of pristine PVDF-TrFE PENG. This fabricated PENG possesses advantages such as biocompatibility and flexibility, making it suitable for sensing devices used in a self-powered kinetic motion sensor. © 2024, The Authors. All rights reserved.

关键词： Electrospinning

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Resonance with Surface Waves Induces Forbidden Velocity Bands in Dislocation Glide

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SSRN 2022年

作者： Duong, Ta Demkowicz, michael J. Department of Materials Science and Engineering Texas A&M University College StationTX77843 United States

We demonstrate a pronounced influence of free surfaces on the mobility of dislocations at near-sonic velocities. By correlating instantaneous velocities v and resolved stresses tau, we show that the mobility laws of both edge and screw characters are composed of piece-wise continuous ranges of uniform motion separated by bands of forbidden velocity. The lower limiting velocity for uniform motion of both edge and screw dislocations is the Rayleigh wave speed, cR. When forced to propagate at an average velocity greater than cR, dislocations exhibit periodic, intermittent jumps in instantaneous velocity between cR and higher velocity branches of the mobility law. Bands of forbidden velocity may be calculated directly from the velocity dependence of dislocation drag coefficients, which contain peaks near cR and—in the edge case—one other characteristic surface wave speed, which we associate with surface Love waves. We propose that peaks in the drag coefficient are due to resonance of free surface vibrations forced by nearby moving dislocations. © 2022, The Authors. All rights reserved.

关键词： Surface waves

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Enhancing coolant performance using carbon nanoparticles as additives

Nano Trends

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Nano Trends 2025年 9卷

作者： Arole, Kailash Sarmah, Anubhav Kosmoski, Joseph V. Johnson, Evan C. Green, micah J. Liang, Hong Department of Materials Science and Engineering Texas A&M University College Station 77843 TX United States Artie McFerrin Department of Chemical Engineering Texas A&M University College Station 77843 TX United States Nabors Energy Transition Solutions LLC Houston 77067 TX United States J. Mike Walker '66 Department of Mechanical Engineering Texas A&M University College Station 77843 TX United States

The mixture of water and ethylene glycol (EG) as conventional coolants has been widely used in automobile radiators for decades. However, these heat-transfer fluids have low thermal conductivity and fail to fulfill the needs of upcoming high-speed and compact vehicles. Nanomaterial additives offer an opportunity to develop new coolants with improved thermal and physical performance. The feasibility of a new class of carbon-based nanomaterial as an additive for coolant is investigated in this work. Experiments were conducted to measure the effect of carbon nanoplatelets on the thermal conductivity, thermal diffusivity, specific heat, and viscosity of ethylene glycol-based coolants. The addition of carbon nanoplatelets into EG:water at a loading of 0.5 wt.% increased thermal conductivity and diffusivity by 15.7 % and 45.9 %, respectively. The addition of 0.5 wt.% of carbon nanoplatelets showed a viscosity drop of 16.6 %. This reduction in viscosity creates a smaller boundary layer, resulting in enhanced heat transfer and better performance. Thus, the improved thermophysical properties offered by this new class of carbon nanoparticles show promise for their use as an additive in coolants. © 2025 The Author(s)

关键词： Heat transfer enhancement Nanofluids Nanomaterial Rheology

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