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Full-Text Articles in Nanoscience and Nanotechnology

Generalized Ultrasonic Scattering Model For Arbitrary Transducer Configurations, Andrea P. Arguelles, Joseph A. Turner Dec 2019

Generalized Ultrasonic Scattering Model For Arbitrary Transducer Configurations, Andrea P. Arguelles, Joseph A. Turner

Mechanical & Materials Engineering Faculty Publications

Ultrasonic scattering in polycrystalline media is directly tied to microstructural features. As a result, modeling efforts of scattering from microstructure have been abundant. The inclusion of beam modeling for the ultrasonic transducers greatly simplified the ability to perform quantitative, fully calibrated experiments. In this article, a theoretical scattering model is generalized to allow for arbitrary source and receiver configurations, while accounting for beam behavior through the total propagation path. This extension elucidates the importance and potential of out-of-plane scattering modes in the context of microstructure characterization. The scattering coefficient is explicitly written for the case of statistical isotropy and ellipsoidal ...


Beyond The Toolpath: Site-Specific Melt Pool Size Control Enables Printing Of Extra-Toolpath Geometry In Laserwire-Based Directed Energy Deposition, Brian T. Gibson, Bradley S. Richardson, Tayler W. Undermann, Lonnie J. Love Oct 2019

Beyond The Toolpath: Site-Specific Melt Pool Size Control Enables Printing Of Extra-Toolpath Geometry In Laserwire-Based Directed Energy Deposition, Brian T. Gibson, Bradley S. Richardson, Tayler W. Undermann, Lonnie J. Love

Mechanical & Materials Engineering Faculty Publications

A variety of techniques have been utilized in metal additive manufacturing (AM) for melt pool size management, including modeling and feed-forward approaches. In a few cases, closed-loop control has been demonstrated. In this research, closed-loop melt pool size control for large-scale, laser wire-based directed energy deposition is demonstrated with a novel modification, i.e., site-specific changes to the controller setpoint were commanded at trigger points, the locations of which were generated by the projection of a secondary geometry onto the primary three-dimensional (3D) printed component geometry. The present work shows that, through this technique, it is possible to print a ...


Effect Of Silica Fume In Concrete On Mechanical Properties And Dynamic Behaviors Under Impact Loading, Shijun Zhao, Qing Zhang Oct 2019

Effect Of Silica Fume In Concrete On Mechanical Properties And Dynamic Behaviors Under Impact Loading, Shijun Zhao, Qing Zhang

Mechanical & Materials Engineering Faculty Publications

The effect of silica fume (SF) in concrete on mechanical properties and dynamic behaviors was experimentally studied by split Hopkinson pressure bar (SHPB) device with pulse shaping technique. Three series of concrete with 0, 12%, and 16% SF as a cement replacement by weight were produced firstly. Then the experimental procedure for dynamic tests of concrete specimens with SF under a high loading rate was presented. Considering the mechanical performance and behaviors of the concrete mixtures, those tests were conducted under five different impact velocities. The experimental results clearly show concrete with different levels of SF is a strain-rate sensitive ...


System And Method For Sensing Wind Flow Passing Over Complex Terrain, Saleh Nabi, Piyush Grover, Mithu Debnath Sep 2019

System And Method For Sensing Wind Flow Passing Over Complex Terrain, Saleh Nabi, Piyush Grover, Mithu Debnath

Mechanical & Materials Engineering Faculty Publications

A wind flow sensing system determines a first approximation of the velocity field at each of the altitudes by simulating computational fluid dynamics ( CFD ) of the wind flow with operating parameters reducing a cost function of a weighted combination of errors , determines a horizontal derivative of vertical velocity at each of the altitudes from the first approximation of the velocity fields , and determines a second approximation of the velocity fields using geometric relationships between a velocity field for each of the altitudes , projections of the measurements of radial velocities on the three - dimensional axes , and the horizontal derivative of vertical ...


Multi-Agent Control System And Method, Piyush Grover, Karthik Elamvazhuthi Sep 2019

Multi-Agent Control System And Method, Piyush Grover, Karthik Elamvazhuthi

Mechanical & Materials Engineering Faculty Publications

Motion of multiple agents with identical non - linear dynamics is controlled to change density of the agents from the initial to the final density . A first control problem is formulated for optimizing a control cost of changing density of the agents from the initial density to the final density subject to dynamics of the agents in a density space . The first control problem , which is a non - linear non - convex problem over a multi - agent control and a density of the agents , is trans formed into a second control problem over the density of the agents and a product of ...


3d Printing Of Silk Fibroin-Based Hybrid Scaffold Treated With Platelet Rich Plasma For Bone Tissue Engineering, Liang Wei, Shaohua Wu, Mitchell Kuss, Xiping Jiang, Runjun Sun, Reid Patrick, Xiaohong Qin, Bin Duan Sep 2019

3d Printing Of Silk Fibroin-Based Hybrid Scaffold Treated With Platelet Rich Plasma For Bone Tissue Engineering, Liang Wei, Shaohua Wu, Mitchell Kuss, Xiping Jiang, Runjun Sun, Reid Patrick, Xiaohong Qin, Bin Duan

Mechanical & Materials Engineering Faculty Publications

3D printing/bioprinting are promising techniques to fabricate scaffolds with well controlled and patient-specific structures and architectures for bone tissue engineering. In this study, we developed a composite bioink consisting of silk fibroin (SF), gelatin (GEL), hyaluronic acid (HA), and tricalcium phosphate (TCP) and 3D bioprinted the silk fibroin-based hybrid scaffolds. The 3D bioprinted scaffolds with dual crosslinking were further treated with human platelet-rich plasma (PRP) to generate PRP coated scaffolds. Live/Dead and MTT assays demonstrated that PRP treatment could obviously promote the cell growth and proliferation of human adipose derived mesenchymal stem cells (HADMSC). In addition, the treatment ...


3d Printing Of Silk Fibroin-Based Hybrid Scaffold Treated With Platelet Rich Plasma For Bone Tissue Engineering, Liang Wei, Shaohua Wu, Mitchell Kuss, Xiping Jiang, Runjun Sun, Reid Patrick, Xiaohong Qin, Duan Bin Sep 2019

3d Printing Of Silk Fibroin-Based Hybrid Scaffold Treated With Platelet Rich Plasma For Bone Tissue Engineering, Liang Wei, Shaohua Wu, Mitchell Kuss, Xiping Jiang, Runjun Sun, Reid Patrick, Xiaohong Qin, Duan Bin

Mechanical & Materials Engineering Faculty Publications

3D printing/bioprinting are promising techniques to fabricate scaffolds with well controlled and patient-specific structures and architectures for bone tissue engineering. In this study, we developed a composite bioink consisting of silk fibroin (SF), gelatin (GEL), hyaluronic acid (HA), and tricalcium phosphate (TCP) and 3D bioprinted the silk fibroin-based hybrid scaffolds. The 3D bioprinted scaffolds with dual crosslinking were further treated with human platelet-rich plasma (PRP) to generate PRP coated scaffolds. Live/Dead and MTT assays demonstrated that PRP treatment could obviously promote the cell growth and proliferation of human adipose derived mesenchymal stem cells (HADMSC). In addition, the treatment ...


Interface Effects On He Ion Irradiation In Nanostructured Materials, Wenfan Yang, Jingyu Pang, Shijian Zheng, Jian Wang, Xinghang Zhang, Xiuliang Ma Aug 2019

Interface Effects On He Ion Irradiation In Nanostructured Materials, Wenfan Yang, Jingyu Pang, Shijian Zheng, Jian Wang, Xinghang Zhang, Xiuliang Ma

Mechanical & Materials Engineering Faculty Publications

In advanced fission and fusion reactors, structural materials suffer from high dose irradiation by energetic particles and are subject to severe microstructure damage. He atoms, as a byproduct of the (n) transmutation reaction, could accumulate to form deleterious cavities, which accelerate radiation-induced embrittlement, swelling and surface deterioration, ultimately degrade the service lifetime of reactor materials. Extensive studies have been performed to explore the strategies that can mitigate He ion irradiation damage. Recently, nanostructured materials have received broad attention because they contain abundant interfaces that are efficient sinks for radiation-induced defects. In this review, we summarize and analyze the current understandings ...


The Linc Complex, Mechanotransduction, And Mesenchymal Stem Cell Function And Fate, Tasneem Bouzid, Eunju Kim, Brandon D. Riehl, Amir Monemian Esfahani, Jordan Rosebohm, Ruiguo Yang, Bin Duan, Jung Yul Lim Aug 2019

The Linc Complex, Mechanotransduction, And Mesenchymal Stem Cell Function And Fate, Tasneem Bouzid, Eunju Kim, Brandon D. Riehl, Amir Monemian Esfahani, Jordan Rosebohm, Ruiguo Yang, Bin Duan, Jung Yul Lim

Mechanical & Materials Engineering Faculty Publications

Mesenchymal stem cells (MSCs) show tremendous promise as a cell source for tissue engineering and regenerative medicine, and are understood to be mechanosensitive to external mechanical environments. In recent years, increasing evidence points to nuclear envelope proteins as a key player in sensing and relaying mechanical signals in MSCs to modulate cellular form, function, and differentiation. Of particular interest is the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex that includes nesprin and SUN. In this review, the way in which cells can sense external mechanical environments through an intact nuclear envelope and LINC complex proteins will be briefly described. Then ...


On The Measurement Of Energy Dissipation Of Adhered Cells With The Quartz Microbalance With Dissipation Monitoring, Amir Monemian Esfahani, Weiwei Zhao, Jennifer Y. Chen, Changjin Huang, Ning Xi, Jun Xi, Ruiguo Yang Aug 2019

On The Measurement Of Energy Dissipation Of Adhered Cells With The Quartz Microbalance With Dissipation Monitoring, Amir Monemian Esfahani, Weiwei Zhao, Jennifer Y. Chen, Changjin Huang, Ning Xi, Jun Xi, Ruiguo Yang

Mechanical & Materials Engineering Faculty Publications

We previously reported the finding of a linear correlation between the change of energy dissipation (ΔD) of adhered cells measured with the quartz crystal microbalance with dissipation monitoring (QCM-D) and the level of focal adhesions of the cells. To account for this correlation, we have developed a theoretical framework for assessing the ΔD-response of adhered cells. We rationalized that the mechanical energy of an oscillating QCM-D sensor coupled with a cell monolayer is dissipated through three main processes: the interfacial friction through the dynamic restructuring (formation and rupture) of cell-extracellular matrix (ECM) bonds, the interfacial viscous damping by the liquid ...


Observations Of Shear Stress Effects On Staphylococcus Aureus Biofilm Formation, Erica Sherman, Kenneth W. Bayles, Derek Moormeir, Jennifer Endres, Timothy Wei Jul 2019

Observations Of Shear Stress Effects On Staphylococcus Aureus Biofilm Formation, Erica Sherman, Kenneth W. Bayles, Derek Moormeir, Jennifer Endres, Timothy Wei

Mechanical & Materials Engineering Faculty Publications

Staphylococcus aureus bacteria form biofilms and distinctive microcolony or “tower” structures that facilitate their ability to tolerate antibiotic treatment and to spread within the human body. The formation of microcolonies, which break off, get carried downstream, and serve to initiate biofilms in other parts of the body, is of particular interest here. It is known that flow conditions play a role in the development, dispersion, and propagation of biofilms in general. The influence of flow on microcolony formation and, ultimately, what factors lead to microcolony development are, however, not well understood. The hypothesis being examined is that microcolony structures form ...


Modeling Thermal And Mechanical Cancellation Of Residual Stress From Hybrid Additive Manufacturing By Laser Peening, Guru Madireddy, Chao Li, Jingfu Liu, Michael P. Sealy Jul 2019

Modeling Thermal And Mechanical Cancellation Of Residual Stress From Hybrid Additive Manufacturing By Laser Peening, Guru Madireddy, Chao Li, Jingfu Liu, Michael P. Sealy

Mechanical & Materials Engineering Faculty Publications

Additive manufacturing (AM) of metals often results in parts with unfavorable mechanical properties. Laser peening (LP) is a high strain rate mechanical surface treatment that hammers a workpiece and induces favorable mechanical properties. Peening strain hardens a surface and imparts compressive residual stresses improving the mechanical properties of a material. This work investigates the role of LP on layer-by-layer processing of 3D printed metals using finite element analysis. The objective is to understand temporal and spatial residual stress development after thermal and mechanical cancellation caused by cyclically coupling printing and peening. Results indicate layer peening frequency is a critical process ...


Method For Fabrication Of A Soft-Matter Printed Circuit Board, Carmel Majidi, Tong Lu, Eric J. Markvicka Jul 2019

Method For Fabrication Of A Soft-Matter Printed Circuit Board, Carmel Majidi, Tong Lu, Eric J. Markvicka

Mechanical & Materials Engineering Faculty Publications

A fabrication process for soft - matter printed circuit boards is disclosed in which traces of liquid - phase Ga - In eutectic ( eGaIn ) are patterned with UV laser micromachining ( UVLM ) . The terminals of the elastomer - sealed LM circuit connect to the surface mounted chips through vertically aligned columns of eGaIn - coated ferromagnetic micro spheres that are embedded within an interfacial elastomer layer .


Wearable Devices For Single-Cell Sensing And Transfection, Lingqian Chang, Yu-Chieh Wang, Faheem Ershad, Ruiguo Yang, Cunjiang Yu, Yubo Fan May 2019

Wearable Devices For Single-Cell Sensing And Transfection, Lingqian Chang, Yu-Chieh Wang, Faheem Ershad, Ruiguo Yang, Cunjiang Yu, Yubo Fan

Mechanical & Materials Engineering Faculty Publications

Wearable healthcare devices are mainly used for biosensing and transdermal delivery. Recent advances in wearable biosensors allow for long-term and real-time monitoring of physiological conditions at a cellular resolution. Transdermal drug delivery systems have been further scaled down, enabling wide selections of cargo, from natural molecules (e.g., insulin and glucose) to bioengineered molecules (e.g., nanoparticles). Some emerging nanopatches show promise for precise single-cell gene transfection in vivo and have advantages over conventional tools in terms of delivery efficiency, safety, and controllability of delivered dose. In this review, we discuss recent technical advances in wearable micro/nano devices with ...


Influence Of Metal Additives On Microstructure And Properties Of Amorphous Metal–Sioc Composites, Kaisheng Ming, Qing Su, Chao Gu, Dongyue Xie, Yongqiang Wang, Michael Nastasi, Jian Wang Apr 2019

Influence Of Metal Additives On Microstructure And Properties Of Amorphous Metal–Sioc Composites, Kaisheng Ming, Qing Su, Chao Gu, Dongyue Xie, Yongqiang Wang, Michael Nastasi, Jian Wang

Mechanical & Materials Engineering Faculty Publications

Strong, ductile, and irradiation-tolerant structural materials are in urgent demand for improving the safety and efficiency of advanced nuclear reactors. Amorphous ceramics could be promising candidates for high irradiation tolerance due to thermal stability and lack of crystal defects. However, they are very brittle due to plastic flow instability. Here, we realized enhanced plasticity of amorphous ceramics through compositional and microstructural engineering. Two metal–amorphous ceramic composites, Fe-SiOC and Cu-SiOC, were fabricated by magnetron sputtering. Iron atoms are preferred to form uniformly distributed nano-sized Fe-rich amorphous clusters, while copper atoms grow non-uniformly distributed nano-crystalline Cu particles. The Fe-SiOC composite exhibits ...


Biomechanical Foot Guidance Linkage, Carl Nelson, Cale J. Stolle, Judith M. Burnfield Apr 2019

Biomechanical Foot Guidance Linkage, Carl Nelson, Cale J. Stolle, Judith M. Burnfield

Mechanical & Materials Engineering Faculty Publications

A gait replication apparatus can include a scalable mechanical mechanism configured to replicate different gaits . The scalable mechanical mechanism can include , for example , a four - bar linkage , a pantograph , a cam / Scotch - yoke mechanism , and so forth . In some embodiments , the mechanical mechanism includes a beam rotating about an axis passing proximate to its center , with a foot pedal slidably coupled with the beam , and a timing chain / belt or cable pulley - pair coupled with the foot pedal and looped about the beam . A method can include decomposing a foot path defined by Cartesian coordinates into polar coordinates , and providing ...


Soft , Multilayered Electronics For Wearable Devices And Methods To Produce The Same, Carmel Majidi, Michael D. Bartlett, Eric J. Markvicka Mar 2019

Soft , Multilayered Electronics For Wearable Devices And Methods To Produce The Same, Carmel Majidi, Michael D. Bartlett, Eric J. Markvicka

Mechanical & Materials Engineering Faculty Publications

Disclosed herein is an efficient fabrication approach to create highly customizable wearable electronics through rapid laser machining and adhesion - controlled soft materials assembly . Well - aligned , multi - layered materials can be created from 2D and 3D elements that stretch and bend while seamlessly integrating with rigid components such as micro chip integrated circuits ( IC ) , discrete electrical components , and interconnects . These techniques are applied using commercially available materials . These materials and methods enable custom wearable electronics while offering versatility in design and functionality for a variety of bio - monitor ing applications .


Gastrointestinal Sensor Implantation System, Benjamin Terry, Weston Lewis, Wanchuan Xie, Pengbo Li, Alfred Tsubaki Mar 2019

Gastrointestinal Sensor Implantation System, Benjamin Terry, Weston Lewis, Wanchuan Xie, Pengbo Li, Alfred Tsubaki

Mechanical & Materials Engineering Faculty Publications

A gastrointestinal ( GI ) sensor deployment device is dis closed . In implementations , the sensor deployment device includes an orally - administrable capsule with a tissue cap ture device removably coupled to the orally - administrable capsule . The tissue capture device includes a plurality of fasteners for connecting the tissue capture device to GI tissue within a body . A biometric sensor is coupled to the tissue capture device for continuous or periodic monitoring of the GI tract of the body at the GI tissue attachment location . A chamber within the orally - administrable capsule is configured to draw gastrointestinal tissue towards the plurality of fasteners ...


Interactions Between Dislocations And Three-Dimensional Annealing Twins In Face Centered Cubic Metals, Yanxiang Liang, Xiaofang Yang, Mingyu Gong, Guisen Liu, Qing Liu, Jian Wang Mar 2019

Interactions Between Dislocations And Three-Dimensional Annealing Twins In Face Centered Cubic Metals, Yanxiang Liang, Xiaofang Yang, Mingyu Gong, Guisen Liu, Qing Liu, Jian Wang

Mechanical & Materials Engineering Faculty Publications

Annealing twins often form in metals with a face centered cubic structure during thermal and mechanical processing. Here, we conducted molecular dynamic (MD) simulations for copper and aluminum to study the interaction processes between {1 1 1}1/2 <1 1 0> dislocations and a three-dimensional annealing twin. Twin boundaries are characterized with Σ3{1 1 1} coherent twin boundaries (CTBs) and Σ3{1 1 2} incoherent twin boundaries (ITBs). MD results revealed that dislocation-ITB interactions affect slip transmission for a dislocation crossing CTBs, facilitating the nucleation of Lomer dislocation.


Strength And Plasticity Of Amorphous Silicon Oxycarbide, Kaisheng Ming, Chao Gu, Qing Su, Yongqiang Wang, Arezoo Zare, Don A. Lucca, Michael Nastasi, Jian Wang Jan 2019

Strength And Plasticity Of Amorphous Silicon Oxycarbide, Kaisheng Ming, Chao Gu, Qing Su, Yongqiang Wang, Arezoo Zare, Don A. Lucca, Michael Nastasi, Jian Wang

Mechanical & Materials Engineering Faculty Publications

Amorphous SiOC films were synthesized by magnetron sputtering at room temperature with/without radio frequency (RF) bias and further improved in terms of mechanical properties by ion irradiation. As-deposited SiOC films without RF bias exhibit catastrophic failure at a low stress and strain, which is ascribed to microstructural heterogeneities associated with the formation of voids during deposition, as evidenced by transmission electron microscopy. Ion irradiation unifies microstructure accompanied with eliminating the voids, resulting in a simultaneously increase in strength and plasticity (ultimate strength of 5–7 GPa and the strain to shear instability of over 20%). Homogeneous microstructures are demonstrated ...


Hemodynamic Interference Of Serial Stenoses And Its Impact On Ffr And Ifr Measurements, Siyeong Ju, Linxia Gu Jan 2019

Hemodynamic Interference Of Serial Stenoses And Its Impact On Ffr And Ifr Measurements, Siyeong Ju, Linxia Gu

Mechanical & Materials Engineering Faculty Publications

The hemodynamic interference of serial stenoses poses challenges for identifying the functional severity using the fractional flow reserve (FFR) method. The instantaneous wave-free ratio (iFR), i.e., the distal-to-proximal pressure ratio at 75% of diastole, was recently proposed to overcome the disadvantages of the FFR. However, the underlying mechanism remained ambiguous due to the lack of quantitative definition of hemodynamic interference. The objective of this study is to quantitatively define the hemodynamic interference and then examine its role on the FFR and iFR measurements. Pressure distributions, velocity fields, and Q-criterion which identifies vortices, were obtained through the computational fluid dynamics ...


Glocal Integrity In 420 Stainless Steel By Asynchronous Laser Processing, Michael P. Sealy, Haitham Hadidi, Cody Kanger, X. L. Yan, Bai Cui, J. A. Mcgeough Jan 2019

Glocal Integrity In 420 Stainless Steel By Asynchronous Laser Processing, Michael P. Sealy, Haitham Hadidi, Cody Kanger, X. L. Yan, Bai Cui, J. A. Mcgeough

Mechanical & Materials Engineering Faculty Publications

Cold working individual layers during additive manufacturing (AM) by mechanical surface treatments, such as peening, effectively “prints” an aggregate surface integrity that is referred to as a glocal (i.e., local with global implications) integrity. Printing a complex, pre-designed glocal integrity throughout the build volume is a feasible approach to improve functional performance while mitigating distortion. However, coupling peening with AM introduces new manufacturing challenges, namely thermal cancellation, whereby heat relaxes favorable residual stresses and work hardening when printing on a peened layer. Thus, this work investigates glocal integrity formation from cyclically coupling LENS® with laser peening on 420 stainless ...


The Role Of Low-Level Image Features In The Affective Categorization Of Rapidly Presented Scenes, L. Jack Rhodes, Matthew Rios, Jacob M. Williams, Gonzalo Quinones, Prahalada K. Rao, Vladimir Miskovic Jan 2019

The Role Of Low-Level Image Features In The Affective Categorization Of Rapidly Presented Scenes, L. Jack Rhodes, Matthew Rios, Jacob M. Williams, Gonzalo Quinones, Prahalada K. Rao, Vladimir Miskovic

Mechanical & Materials Engineering Faculty Publications

It remains unclear how the visual system is able to extract affective content from complex scenes even with extremely brief (< 100 millisecond) exposures. One possibility, suggested by findings in machine vision, is that low-level features such as unlocalized, two-dimensional (2-D) Fourier spectra can be diagnostic of scene content. To determine whether Fourier image amplitude carries any information about the affective quality of scenes, we first validated the existence of image category differences through a support vector machine (SVM) model that was able to discriminate our intact aversive and neutral images with ~ 70% accuracy using amplitude-only features as inputs. This model allowed us to confirm that scenes belonging to different affective categories could be mathematically distinguished on the basis of amplitude spectra alone. The next question is whether these same features are also exploited by the human visual system. Subsequently, we tested observers’ rapid classification of affective and neutral naturalistic scenes, presented briefly (~33.3 ms) and backward masked with synthetic textures. We tested categorization accuracy across three distinct experimental conditions, using: (i) original images, (ii) images having their amplitude spectra swapped within a single affective image category (e.g., an aversive image whose amplitude spectrum has been swapped with another aversive image) or (iii) images having their amplitude spectra swapped between affective categories (e.g., an aversive image containing the amplitude spectrum of a neutral image). Despite its discriminative potential, the human visual system does not seem to use Fourier amplitude differences as the chief strategy for affectively categorizing scenes at a glance. The contribution of image amplitude to affective categorization is largely dependent on interactions with the phase spectrum, although it is impossible to completely rule out a residual role for unlocalized 2-D amplitude measures.


Fast Growth Of Thin Mapbi3 Crystal Wafers On Aqueous Solution Surface For Efficient Lateral-Structure Perovskite Solar Cells, Ye Liu, Qingfeng Dong, Yanjun Fang, Yuze Lin, Yehao Deng, Jinsong Huang Jan 2019

Fast Growth Of Thin Mapbi3 Crystal Wafers On Aqueous Solution Surface For Efficient Lateral-Structure Perovskite Solar Cells, Ye Liu, Qingfeng Dong, Yanjun Fang, Yuze Lin, Yehao Deng, Jinsong Huang

Mechanical & Materials Engineering Faculty Publications

Solar-grade single or multiple crystalline wafers are needed in large quantities in the solar cell industry, and are generally formed by a top-down process from crystal ingots, which causes a significant waste of materials and energy during slicing, polishing, and other processing. Here, a bottom-up technique that allows the growth of wafer-size hybrid perovskite multiple crystals directly from aqueous solution is reported. Single-crystalline hybrid perovskite wafers with centimeter size are grown at the top surface of a perovskite precursor solution. As well as saving raw materials, this method provides unprecedented advantages such as easily tunable thickness and rapid growth of ...


High Strength, Deformable Nanotwinned Al–Co Alloys, S. Xue, Qiang Li, D. Y. Xie, Y. F. Zhang, Han Wang, Haiyan Wong, J. Wang, Xinghang Zhang Jan 2019

High Strength, Deformable Nanotwinned Al–Co Alloys, S. Xue, Qiang Li, D. Y. Xie, Y. F. Zhang, Han Wang, Haiyan Wong, J. Wang, Xinghang Zhang

Mechanical & Materials Engineering Faculty Publications

Aluminum (Al) alloys have been widely used in the transportation industry. However, most highstrength Al alloys to date have limited mechanical strength, on the order of a few hundred MPa, which is much lower than the flow stress of high-strength steels. In this study, we show the fabrication of nanocrystalline Al alloys with high-density growth twins enabled by a few atomic percent of Co solute. In situ uniaxial compression tests show that the flow stress of Al–Co solid solution alloys exceeds 1.5 GPa, while good work hardening capability is maintained. This study provides a new perspective on the ...


Flaw Detection With Ultrasonic Backscatter Signal Envelopes, Yongfeng Song, Christopher M. Kube, Zuoxiang Peng, Joseph A. Turner, Xiongbing Li Jan 2019

Flaw Detection With Ultrasonic Backscatter Signal Envelopes, Yongfeng Song, Christopher M. Kube, Zuoxiang Peng, Joseph A. Turner, Xiongbing Li

Mechanical & Materials Engineering Faculty Publications

Ultrasound is a prominent nondestructive testing modality for the detection, localization, and sizing of defects in engineering materials. Often, inspectors analyze ultrasonic waveforms to determine if echoes, which stem from the scattering of ultrasound from a defect, exceed a threshold value. In turn, the initial selection of the threshold value is critical. In this letter, a time-dependent threshold or upper bound for the signal envelope is developed based on the statistics governing the scattering of ultrasound from microstructure. The utility of the time-dependent threshold is demonstrated using experiments conducted on sub-wavelength artificial defects. The results are shown to enhance current ...


Spatiotemporal Characterizations Of Spontaneously Beating Cardiomyocytes With Adaptive Reference Digital Image Correlation, Akankshya Shradhanjali, Brandon D. Riehl, Bin Duan, Ruiguo Yang, Jung Yul Lim Jan 2019

Spatiotemporal Characterizations Of Spontaneously Beating Cardiomyocytes With Adaptive Reference Digital Image Correlation, Akankshya Shradhanjali, Brandon D. Riehl, Bin Duan, Ruiguo Yang, Jung Yul Lim

Mechanical & Materials Engineering Faculty Publications

We developed an Adaptive Reference-Digital Image Correlation (AR-DIC) method that enables unbiased and accurate mechanics measurements of moving biological tissue samples. We applied the AR-DIC analysis to a spontaneously beating cardiomyocyte (CM) tissue, and could provide correct quantifications of tissue displacement and strain for the beating CMs utilizing physiologically-relevant, sarcomere displacement length-based contraction criteria. The data were further synthesized into novel spatiotemporal parameters of CM contraction to account for the CM beating homogeneity, synchronicity, and propagation as holistic measures of functional myocardial tissue development. Our AR-DIC analyses may thus provide advanced non-invasive characterization tools for assessing the development of spontaneously ...


Mechanical Characterizations Of 3d-Printed Plla/Steel Particle Composites, Hozhabr Mozafari, Pengfei Dong, Haitham Hadidi, Michael P. Sealy, Linxia Gu Jan 2019

Mechanical Characterizations Of 3d-Printed Plla/Steel Particle Composites, Hozhabr Mozafari, Pengfei Dong, Haitham Hadidi, Michael P. Sealy, Linxia Gu

Mechanical & Materials Engineering Faculty Publications

The objective of this study is to characterize the micromechanical properties of poly-L-lactic acid (PLLA) composites reinforced by grade 420 stainless steel (SS) particles with a specific focus on the interphase properties. The specimens were manufactured using 3D printing techniques due to its many benefits, including high accuracy, cost effectiveness and customized geometry. The adopted fused filament fabrication resulted in a thin interphase layer with an average thickness of 3 μm. The mechanical properties of each phase, as well as the interphase, were characterized by nanoindentation tests. The effect of matrix degradation, i.e., imperfect bonding, on the elastic modulus ...


Resistance To Helium Bubble Formation In Amorphous Sioc/Crystalline Fe Nanocomposite, Qing Su, Tianyao Wang, Jonathan Gigax, Lin Shao, Michael Nastasi Jan 2019

Resistance To Helium Bubble Formation In Amorphous Sioc/Crystalline Fe Nanocomposite, Qing Su, Tianyao Wang, Jonathan Gigax, Lin Shao, Michael Nastasi

Mechanical & Materials Engineering Faculty Publications

The management of radiation defects and insoluble He atoms represent key challenges for structural materials in existing fission reactors and advanced reactor systems. To examine how crystalline/amorphous interface, together with the amorphous constituents affects radiation tolerance and He management, we studied helium bubble formation in helium ion implanted amorphous silicon oxycarbide (SiOC) and crystalline Fe composites by transmission electron microscopy (TEM). The SiOC/Fe composites were grown via magnetron sputtering with controlled length scale on a surface oxidized Si (100) substrate. These composites were subjected to 50 keV He+ implantation with ion doses chosen to produce a 5 at ...


A Sensorless Force-Feedback System For Robot-Assisted Laparoscopic Surgery, Baoliang Zhao, Carl A. Nelson Jan 2019

A Sensorless Force-Feedback System For Robot-Assisted Laparoscopic Surgery, Baoliang Zhao, Carl A. Nelson

Mechanical & Materials Engineering Faculty Publications

The existing surgical robots for laparoscopic surgery offer no or limited force feedback, and there are many problems for the traditional sensor-based solutions. This paper builds a teleoperation surgical system and validates the effectiveness of sensorless force feedback. The tool-tissue interaction force at the surgical grasper tip is estimated using the driving motor’s current, and fed back to the master robot with a position-force bilateral control algorithm. The stiffness differentiation experiment and tumor detection experiment were conducted. In the stiffness differentiation experiment, 43 out of 45 pairs of ranking relationships were identified correctly, yielding a success rate of 96 ...