Open Access. Powered by Scholars. Published by Universities.®

Mechanical Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 57

Full-Text Articles in Mechanical Engineering

Method For Single Crystal Growth Of Photovoltaic Perovskite Material And Devices, Jinsong Huang, Qingfeng Dong Nov 2017

Method For Single Crystal Growth Of Photovoltaic Perovskite Material And Devices, Jinsong Huang, Qingfeng Dong

Department of Mechanical and Materials Engineering: Faculty Publications

Systems and methods for perovskite single crystal growth include using a low temperature solution process that employs a temperature gradient in a perovskite solution in a container , also including at least one small perovskite single crystal , and a substrate in the solution upon which substrate a perovskite crystal nucleates and grows , in part due to the temperature gradient in the solution and in part due to a temperature gradient in the substrate . For example , a top portion of the substrate external to the solution may be cooled .


Oct-Based Three Dimensional Modeling Of Stent Deployment, Pengfei Dong, David Prabhu, David L. Wilson, Hiram G. Bezerra, Linxia Gu Nov 2017

Oct-Based Three Dimensional Modeling Of Stent Deployment, Pengfei Dong, David Prabhu, David L. Wilson, Hiram G. Bezerra, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Stent deployment has been widely used to treat narrowed coronary artery. Its acute outcome in terms of stent under expansion and malapposition depends on the extent and shape of calcifications. However, no clear understanding as to how to quantify or categorize the impact of calcification. We have conducted ex vivo stenting characterized by the optical coherence tomography (OCT). The goal of this work is to capture the ex vivo stent deployment and quantify the effect of calcium morphology on the stenting. A three dimensional model of calcified plaque was reconstructed from ex vivo OCT images. The crimping, balloon expansion and …


Floating-Gate Transistor Photodetector, Jinsong Huang, Yongbo Yuan Oct 2017

Floating-Gate Transistor Photodetector, Jinsong Huang, Yongbo Yuan

Department of Mechanical and Materials Engineering: Faculty Publications

A field effect transistor photodetector that can operate in room temperature includes a source electrode , a drain electrode , a channel to allow an electric current to flow between the drain and source electrodes , and a gate electrode to receive a bias voltage for controlling the current in the channel . The photodetector includes a light - absorbing mate rial that absorbs light and traps electric charges . The light absorbing material is configured to generate one or more charges upon absorbing light having a wavelength within a specified range and to hold the one or more charges …


Software For Extracting Deformation Gradient And Stress From Md Simulations: Simulations Using The Charmm Force Field, Mehrdad Negahban, Lili Zhang, Zesheng Zhang, John Jasa, Antoine Jérusalem Aug 2017

Software For Extracting Deformation Gradient And Stress From Md Simulations: Simulations Using The Charmm Force Field, Mehrdad Negahban, Lili Zhang, Zesheng Zhang, John Jasa, Antoine Jérusalem

Department of Mechanical and Materials Engineering: Faculty Publications

Software was developed, and is provided under a general use license, to calculate continuum level deformation gradient and stress for any group of atoms in an MD simulation that uses the Charmm force fields. This software can also calculate the interaction stress applied by one group of atoms on any other group. To obtain deformation gradient and stress, the user needs to provide the selected group(s) of atoms in an atom group identification file, and provide the associated LAMMPS format files and force field parameter file. An example is included to demonstrate the use of the software.


Energy Absorbing Guardrail System, John R. Rohde, John D. Reid, King K. Mak, Dean L. Sicking Aug 2017

Energy Absorbing Guardrail System, John R. Rohde, John D. Reid, King K. Mak, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

A highway crash attenuation system having W - beam rail elements attached to a plurality of vertical posts . An impact terminal with a feeder chute guides one or more of the W - beam rail elements through the impact terminal . The feeder chute has an impact shield extending along a traffic facing side of the chute from an upstream - most end to a downstream - most end of the chute closing the traffic - facing side of the chute . The system also has an anchor cable release mechanism for releasing the cable downstream of the first …


Shape-Adaptive Mechanism For Robotic Grasping, Carl A. Nelson Aug 2017

Shape-Adaptive Mechanism For Robotic Grasping, Carl A. Nelson

Department of Mechanical and Materials Engineering: Faculty Publications

A grapser can include a first pantograph cell and a second pantograph cell coupled with the first pantogrpah cell. The first and second pantograph cells can be coupled together at a first pivot and a second pivot. The grasper can also include a finger extendable in a direction extending between the first pivot and the second pivot. The grasper can include a support base, where one or more links of the first pantograph cell can be slidably coupled with the support base for extending the grasper. In some embodiment, the grasper can be configured to extend along a curved path. …


Meniscus-Assisted Solution Printing Of Largegrained Perovskite Films For High-Efficiency Solar Cells, Ming He, Bo Li, Xun Cui, Beibei Jiang, Yanjie He, Yihuang Chen, Daniel O'Neil, Paul Szymanski, Mostafa A. El-Sayed, Jinsong Huang, Zhiqun Lin Jul 2017

Meniscus-Assisted Solution Printing Of Largegrained Perovskite Films For High-Efficiency Solar Cells, Ming He, Bo Li, Xun Cui, Beibei Jiang, Yanjie He, Yihuang Chen, Daniel O'Neil, Paul Szymanski, Mostafa A. El-Sayed, Jinsong Huang, Zhiqun Lin

Department of Mechanical and Materials Engineering: Faculty Publications

Control over morphology and crystallinity of metal halide perovskite films is of key importance to enable high-performance optoelectronics. However, this remains particularly challenging for solution-printed devices due to the complex crystallization kinetics of semiconductor materials within dynamic flow of inks. Here we report a simple yet effective meniscus-assisted solution printing (MASP) strategy to yield large-grained dense perovskite film with good crystallization and preferred orientation. Intriguingly, the outward convective flow triggered by fast solvent evaporation at the edge of the meniscus ink imparts the transport of perovskite solutes, thus facilitating the growth of micrometre-scale perovskite grains. The growth kinetics of perovskite …


Dissipative Elastic Metamaterial With A Lowfrequency Passband, Yongquan Liu, Jianlin Yi, Zheng Li, Xianyue Su, Wenlong Li, Mehrdad Negahban Jun 2017

Dissipative Elastic Metamaterial With A Lowfrequency Passband, Yongquan Liu, Jianlin Yi, Zheng Li, Xianyue Su, Wenlong Li, Mehrdad Negahban

Department of Mechanical and Materials Engineering: Faculty Publications

We design and experimentally demonstrate a dissipative elastic metamaterial structure that functions as a bandpass filter with a low-frequency passband. The mechanism of dissipation in this structure is well described by a mass-spring-damper model that reveals that the imaginary part of the wavenumber is non-zero, even in the passband of dissipative metamaterials. This indicates that transmittance in this range can be low. A prototype for this viscoelastic metamaterial model is fabricated by 3D printing techniques using soft and hard acrylics as constituent materials. The transmittance of the printed metamaterial is measured and shows good agreement with theoretical predictions, demonstrating its …


Multiple Scattering Theory For Heterogeneous Elastic Continua With Strong Property Fluctuation: Theoretical Fundamentals And Applications, Huijing He Jun 2017

Multiple Scattering Theory For Heterogeneous Elastic Continua With Strong Property Fluctuation: Theoretical Fundamentals And Applications, Huijing He

Department of Mechanical and Materials Engineering: Faculty Publications

Scattering of elastic waves in heterogeneous media has become one of the most important problems in the field of wave propagation due to its broad applications in seismology, natural resource exploration, ultrasonic nondestructive evaluation and biomedical ultrasound. Nevertheless, it is one of the most challenging problems because of the complicated medium inhomogeneity and the complexity of the elastodynamic equations. A widely accepted model for the propagation and scattering of elastic waves, which properly incorporates the multiple scattering phenomenon and the statistical information of the inhomogeneities is still missing. In this work, the author developed a multiple scattering model for heterogeneous …


A Strategy To Optimize Recovery In Orthopedic Sports Injuries, Michael P. Sealy, Ziye Liu, Chao Li, Yuebin Guo, Ben White, Mark Barkey, Brian Jordon J, Luke N. Brewer, Dale Feldman Jun 2017

A Strategy To Optimize Recovery In Orthopedic Sports Injuries, Michael P. Sealy, Ziye Liu, Chao Li, Yuebin Guo, Ben White, Mark Barkey, Brian Jordon J, Luke N. Brewer, Dale Feldman

Department of Mechanical and Materials Engineering: Faculty Publications

An important goal for treatment of sports injuries is to have as short a recovery time as possible. The critical problem with current orthopedic implants is that they are designed to be permanent and have a high complication rate (15%) that often requires removal and replacement with a second surgery; and subsequently a second rehabilitation cycle. This study was designed to test the feasibility of having a device that could provide the needed mechanical properties, while promoting healing, for a specified amount of time and then degrade away, to shorten the recovery time. The specific strategy was to create a …


Primary Blast Waves Induced Brain Dynamics Influenced By Head Orientations, Yi Hua, Yugang Wang, Linxia Gu Apr 2017

Primary Blast Waves Induced Brain Dynamics Influenced By Head Orientations, Yi Hua, Yugang Wang, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

There is controversy regarding the directional dependence of head responses subjected to blast loading. The goal of this work is to characterize the role of head orientation in the mechanics of blast wave-head interactions as well as the load transmitting to the brain. A three-dimensional human head model with anatomical details was reconstructed from computed tomography images. Three different head orientations with respect to the oncoming blast wave, i.e., front-on with head facing blast, back-on with head facing away from blast, and side-on with right side exposed to blast, were considered. The reflected pressure at the blast wave-head interface positively …


Dirichlet Process Gaussian Mixture Models For Real-Time Monitoring And Their Application To Chemical Mechanical Planarization, Jia (Peter) Liu, Omer F. Beyca, Prahalad K. Rao, Zhenyu (James) Kong, Satish T. S. Bukkapatnam Jan 2017

Dirichlet Process Gaussian Mixture Models For Real-Time Monitoring And Their Application To Chemical Mechanical Planarization, Jia (Peter) Liu, Omer F. Beyca, Prahalad K. Rao, Zhenyu (James) Kong, Satish T. S. Bukkapatnam

Department of Mechanical and Materials Engineering: Faculty Publications

The goal of this work is to use sensor data for online detection and identification of process anomalies (faults). In pursuit of this goal, we propose Dirichlet process Gaussian mixture (DPGM) models. The proposed DPGM models have two novel outcomes: 1) DP-based statistical process control (SPC) chart for anomaly detection and 2) unsupervised recurrent hierarchical DP clustering model for identification of specific process anomalies. The presented DPGM models are validated using numerical simulation studies as well as wireless vibration signals acquired from an experimental semiconductor chemical mechanical planarization (CMP) test bed. Through these numerically simulated and experimental sensor data, we …


Vorticella: A Protozoan For Bio-Inspired Engineering, Sangjin Ryu, Rachel E. Pepper, Moeto Nagai, Danielle C. France Jan 2017

Vorticella: A Protozoan For Bio-Inspired Engineering, Sangjin Ryu, Rachel E. Pepper, Moeto Nagai, Danielle C. France

Department of Mechanical and Materials Engineering: Faculty Publications

In this review, we introduce Vorticella as a model biological micromachine for microscale engineering systems. Vorticella has two motile organelles: the oral cilia of the zooid and the contractile spasmoneme in the stalk. The oral cilia beat periodically, generating a water flow that translates food particles toward the animal at speeds in the order of 0.1–1 mm/s. The ciliary flow of Vorticella has been characterized by experimental measurement and theoretical modeling, and tested for flow control and mixing in microfluidic systems. The spasmoneme contracts in a few milliseconds, coiling the stalk and moving the zooid at 15–90 mm/s. Because the …


Benchmark Burnishing With Almen Strip For Surface Integrity, Z. Y. Liu, C. H. Fu, M. P. Sealy, Y. Zhao, Y. B. Guo Jan 2017

Benchmark Burnishing With Almen Strip For Surface Integrity, Z. Y. Liu, C. H. Fu, M. P. Sealy, Y. Zhao, Y. B. Guo

Department of Mechanical and Materials Engineering: Faculty Publications

Burnishing is a surface treatment process widely used in aerospace, navy and other industries to improve fatigue and corrosion resistance by introducing a compressive residual stress layer. The measurement of residual stress by XRD is expensive, time consuming, and tedious. This work presented a quick method to determine the residual stress by using Almen strips. Inspired by the application of Almen strips in shot peening, deflections of burnished Almen strips under different burnishing conditions were measured. It was found that the deflection of Almen strip reflects the magnitude and penetration depth into subsurface of induced stress. Higher burnishing force, smaller …


Methods , Systems , And Devices Relating To Surgical End Effectors, Shane M. Farritor, Tom Fredrick, Joe Bartels Jan 2017

Methods , Systems , And Devices Relating To Surgical End Effectors, Shane M. Farritor, Tom Fredrick, Joe Bartels

Department of Mechanical and Materials Engineering: Faculty Publications

The embodiments disclosed herein relate to various medical device components, including components that can be incorporated into robotic and/or in vivo medical devices, and more specifically including end effectors that can be incorporated into such devices. Certain end effector embodiments include various vessel cautery devices that have rotational movement as well as cautery and cutting functions while maintaining a relatively compact structure. Other end effector embodiments include various end effector devices that have more than one end effector.


Flowtaxis Of Osteoblast Migration Under Fluid Shear And The Effect Of Rhoa Kinase Silencing, Brandon D. Riehl, Jeong Soon Lee, Ligyeom Ha, Il Keun Kwon, Jung Yul Lim Jan 2017

Flowtaxis Of Osteoblast Migration Under Fluid Shear And The Effect Of Rhoa Kinase Silencing, Brandon D. Riehl, Jeong Soon Lee, Ligyeom Ha, Il Keun Kwon, Jung Yul Lim

Department of Mechanical and Materials Engineering: Faculty Publications

Despite the important role of mechanical signals in bone remodeling, relatively little is known about how fluid shear affects osteoblastic cell migration behavior. Here we demonstrated that MC3T3-E1 osteoblast migration could be activated by physiologically-relevant levels of fluid shear in a shear stress-dependent manner. Interestingly, shear-sensitive osteoblast migration behavior was prominent only during the initial period after the onset of the steady flow (for about 30 min), exhibiting shear stress-dependent migration speed, displacement, arrest coefficient, and motility coefficient. For example, cell speed at 1 min was 0.28, 0.47, 0.51, and 0.84 μm min-1 for static, 2, 15, and 25 …


Photoluminescence From Radiative Surface States And Excitons In Methylammonium Lead Bromide Perovskites, Dengyang Guo, Davide Bartesaghi, Haotong Wei, Eline M. Hutter, Jinsong Huang, Tom J. Savenije Jan 2017

Photoluminescence From Radiative Surface States And Excitons In Methylammonium Lead Bromide Perovskites, Dengyang Guo, Davide Bartesaghi, Haotong Wei, Eline M. Hutter, Jinsong Huang, Tom J. Savenije

Department of Mechanical and Materials Engineering: Faculty Publications

In view of its band gap of 2.2 eV and its stability, methylammonium lead bromide (MAPbBr3) is a possible candidate to serve as a light absorber in a subcell of a multijunction solar cell. Using complementary temperature-dependent time-resolved microwave conductance (TRMC) and photoluminescence (TRPL) measurements, we demonstrate that the exciton yield increases with lower temperature at the expense of the charge carrier generation yield. The low-energy emission at around 580 nm in the cubic phase and the second broad emission peak at 622 nm in the orthorhombic phase originate from radiative recombination of charges trapped in defects with …


High-Velocity Projectile Impact Induced 9r Phase In Ultrafine-Grained Aluminium, Sichuang Xue, Zhe Fan, Olawale B. Lawal, Ramathasan Thevamaran, Qiang Li, Yue Liu, K. Y. Yu, Jian Wang, Edwin L. Thomas, Haiyan Wang, Xinghang Zhang Jan 2017

High-Velocity Projectile Impact Induced 9r Phase In Ultrafine-Grained Aluminium, Sichuang Xue, Zhe Fan, Olawale B. Lawal, Ramathasan Thevamaran, Qiang Li, Yue Liu, K. Y. Yu, Jian Wang, Edwin L. Thomas, Haiyan Wang, Xinghang Zhang

Department of Mechanical and Materials Engineering: Faculty Publications

Aluminium typically deforms via full dislocations due to its high stacking fault energy. Twinning in aluminium, although difficult, may occur at low temperature and high strain rate. However, the 9R phase rarely occurs in aluminium simply because of its giant stacking fault energy. Here, by using a laser-induced projectile impact testing technique, we discover a deformation-induced 9R phase with tens of nm in width in ultrafine-grained aluminium with an average grain size of 140 nm, as confirmed by extensive post-impact microscopy analyses. The stability of the 9R phase is related to the existence of sessile Frank loops. Molecular dynamics simulations …


Suspended Graphene-Based Gas Sensor With 1-Mw Energy Consumption, Jong-Hyun Kim, Qin Zhou, Jiyoung Chang Jan 2017

Suspended Graphene-Based Gas Sensor With 1-Mw Energy Consumption, Jong-Hyun Kim, Qin Zhou, Jiyoung Chang

Department of Mechanical and Materials Engineering: Faculty Publications

This paper presents NH3 sensing with ultra-low energy consumption for fast recovery and a graphene sheet based on a suspended microheater. Sensitivity and repeatability are important characteristics of functional gas sensors embedded in mobile devices. Moreover, low energy consumption is an essential requirement in flexible and stretchable mobile electronics due to their small dimension and fluctuating resistivity during mechanical behavior. In this paper, we introduce a graphene-based ultra-low power gas detection device with integration of a suspended silicon heater. Dramatic power reduction is enabled by a duty cycle while not sacrificing sensitivity. The new oscillation method of heating improves …


A Rapid And Non-Invasive Method For Measuring The Peak Positive Pressure Of Hifu Fields By A Laser Beam, Hua Wang, Deping Zeng, Ziguang Chen, Zengtao Yang Jan 2017

A Rapid And Non-Invasive Method For Measuring The Peak Positive Pressure Of Hifu Fields By A Laser Beam, Hua Wang, Deping Zeng, Ziguang Chen, Zengtao Yang

Department of Mechanical and Materials Engineering: Faculty Publications

Based on the acousto-optic interaction, we propose a laser deflection method for rapidly, non-invasively and quantitatively measuring the peak positive pressure of HIFU fields. In the characterization of HIFU fields, the effect of nonlinear propagation is considered. The relation between the laser deflection length and the peak positive pressure is derived. Then the laser deflection method is assessed by comparing it with the hydrophone method. The experimental results show that the peak positive pressure measured by laser deflection method is little higher than that obtained by the hydrophone, confirming that they are in reasonable agreement. Considering that the peak pressure …


Dislocations Interaction Induced Structural Instability In Intermetallic Al2Cu, Qing Zhou, Jian Wang, Amit Misra, Ping Huang, Fei Wang, Kewei Xu Jan 2017

Dislocations Interaction Induced Structural Instability In Intermetallic Al2Cu, Qing Zhou, Jian Wang, Amit Misra, Ping Huang, Fei Wang, Kewei Xu

Department of Mechanical and Materials Engineering: Faculty Publications

Intermetallic precipitates are widely used to tailor mechanical properties of structural alloys but are often destabilized during plastic deformation. Using atomistic simulations, we elucidate structural instability mechanisms of intermetallic precipitates associated with dislocation motion in a model system of Al2Cu. Interaction of non-coplanar <001> dislocation dipoles during plastic deformation results in anomalous reactions—the creation of vacancies accompanied with climb and collective glide of <001> dislocation associated with the dislocation core change and atomic shuffle—accounting for structural instability in intermetallic Al2Cu. This process is profound with decreasing separation of non-coplanar dislocations and increasing temperature and is likely to be …


Effects Of Aspect Ratio On The Mode Couplings Of Thin-Film Bulk Acoustic Wave Resonators, Nian Li, Zhenghua Qian, Jiashi Yang Jan 2017

Effects Of Aspect Ratio On The Mode Couplings Of Thin-Film Bulk Acoustic Wave Resonators, Nian Li, Zhenghua Qian, Jiashi Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We studied mode couplings in thin film bulk acoustic wave resonators of a piezoelectric film on a dielectric layer operating with the fundamental thickness-extensional mode. A system of plate equations derived in our previous paper was used which includes the couplings to the unwanted in-plane extension, flexure, fundamental and second-order thickness shear modes. It was shown that the couplings depend strongly on the plate length/thickness ratio. For a relatively clean operating mode with weak couplings to unwanted modes, a series of discrete values of the plate length/thickness ratio should be avoided and these values were determined in the present paper. …


Experimental Study Of Corrugated Metal-Composite Tubes Under Axial Loading, Arameh Eyvazian, Hozhabr Mozafari, Abdel Magid Hamouda Jan 2017

Experimental Study Of Corrugated Metal-Composite Tubes Under Axial Loading, Arameh Eyvazian, Hozhabr Mozafari, Abdel Magid Hamouda

Department of Mechanical and Materials Engineering: Faculty Publications

In this study, crushing behavior of corrugated metal-composite tube was examined experimentally under axial loading condition. Six types of specimens, classified into two groups of metal and metal-composite, were tested under quasi static axial loading. The failure mechanism and failure history of the specimens were presented and discussed. The experimental result showed that corrugated metal composite tubes demonstrate perfect energy absorption characteristics in terms of uniformity of load-displacement diagram, reduction of initial peak load and controlling failure mechanism. Moreover, it was also found that adding filament wound layer of composite on the surface of metallic corrugated tube compensated weakness of …


Clustering On Magnesium Surfaces – Formation And Diffusion Energies, Haijian Chu, Hanchen Huang, Jian Wang Jan 2017

Clustering On Magnesium Surfaces – Formation And Diffusion Energies, Haijian Chu, Hanchen Huang, Jian Wang

Department of Mechanical and Materials Engineering: Faculty Publications

The formation and diffusion energies of atomic clusters on Mg surfaces determine the surface roughness and formation of faulted structure, which in turn affect the mechanical deformation of Mg. This paper reports first principles density function theory (DFT) based quantum mechanics calculation results of atomic clustering on the low energy surfaces {0001} and {1011}. In parallel, molecular statics calculations serve to test the validity of two interatomic potentials and to extend the scope of the DFT studies. On a {0001} surface, a compact cluster consisting of few than three atoms energetically prefers a facecentered- cubic stacking, to serve as a …


Target Lesion Calcium Arc Influence The Performance Of Stenting, Pengfei Dong, Shengmao Lin, David L. Wilson, Hiram G. Bezerra, Linxia Gu Jan 2017

Target Lesion Calcium Arc Influence The Performance Of Stenting, Pengfei Dong, Shengmao Lin, David L. Wilson, Hiram G. Bezerra, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Percutaneous coronary intervention (PCI) is the most common revascularization procedure, in which, fibrocalcific plaques are found in 17–35% of patients undergoing PCI [1]. Numbers will rise with population aging and prolonged statin treatment. Calcifications often lead to stent under expansion and strut malapposition, with increased risk of thrombosis and in-stent restenosis [2]. Presence of calcium strongly inhibits stent performance, a well-documented metric for outcome [3]. The goal of this work is to develop the finite element models for inspecting the influence of the calcium arc extent on the stenting outcomes, such as the stress and strain distribution within the plaque, …


Accommodation Of The Human Lens Capsule Using A Finite Element Model Based On Nonlinear Regionally Anisotropic Biomembranes, G. David, Ryan M. Pedrigi, J. D. Humphrey Jan 2017

Accommodation Of The Human Lens Capsule Using A Finite Element Model Based On Nonlinear Regionally Anisotropic Biomembranes, G. David, Ryan M. Pedrigi, J. D. Humphrey

Department of Mechanical and Materials Engineering: Faculty Publications

Accommodation of the eyes, the mechanism that allows humans to focus their vision on near objects, naturally diminishes with age via presbyopia. People who have undergone cataract surgery, using current surgical methods and artificial lens implants, are also left without the ability to accommodate. The process of accommodation is generally well known; however the specific mechanical details have not been adequately explained due to difficulties and consequences of performing in vivo studies. Most studies have modeled the mechanics of accommodation under assumptions of a linearly elastic, isotropic, homogenous lens and lens capsule. Recent experimental and numerical studies showed that the …


Disturbed Cyclical Stretch Of Endothelial Cells Promotes Nuclear Expression Of The Pro-Atherogenic Transcription Factor Nf-Kb, Ryan M. Pedrigi, Konstantinos I. Papadimitriou, Avinash Kondiboyina, Sukhjinder Sidhu, James Chau, Miten B. Patel, Daniel C. Baeriswyl, Emmanuel M. Drakakis, Rob Krams Jan 2017

Disturbed Cyclical Stretch Of Endothelial Cells Promotes Nuclear Expression Of The Pro-Atherogenic Transcription Factor Nf-Kb, Ryan M. Pedrigi, Konstantinos I. Papadimitriou, Avinash Kondiboyina, Sukhjinder Sidhu, James Chau, Miten B. Patel, Daniel C. Baeriswyl, Emmanuel M. Drakakis, Rob Krams

Department of Mechanical and Materials Engineering: Faculty Publications

Exposure of endothelial cells to low and multidirectional blood flow is known to promote a pro-atherogenic phenotype. The mechanics of the vessel wall is another important mechano-stimulus within the endothelial cell environment, but no study has examined whether changes in the magnitude and direction of cell stretch can be pro-atherogenic. Herein, we developed a custom cell stretching device to replicate the in vivo stretch environment of the endothelial cell and examined whether low and multidirectional stretch promote nuclear translocation of NF-kB. A fluid–structure interaction model of the device demonstrated a nearly uniform strain within the region of cell attachment and …


Growth Mechanisms Of Multiscale, Mound-Like Surface Structures On Titanium By Femtosecond Laser Processing, Edwin Peng, Ryan Bell, Craig A. Zuhlke, Meiyu Wang, Dennis R. Alexander, George Gogos, Jeffrey E. Shield Jan 2017

Growth Mechanisms Of Multiscale, Mound-Like Surface Structures On Titanium By Femtosecond Laser Processing, Edwin Peng, Ryan Bell, Craig A. Zuhlke, Meiyu Wang, Dennis R. Alexander, George Gogos, Jeffrey E. Shield

Department of Mechanical and Materials Engineering: Faculty Publications

Femtosecond laser surface processing (FLSP) can be used to functionalize many surfaces, imparting specialized properties such as increased broadband optical absorption or superhydrophobicity/- hydrophilicity. In this study, the subsurface microstructure of a series of mound-like FLSP structures formed on commercially pure titanium using five combinations of laser fluence and cumulative pulse counts was studied. Using a dual beam Scanning Electron Microscope with a Focused Ion Beam, the subsurface microstructure for each FLSP structure type was revealed by cross-sectioning. The microstructure of the mounds formed using the lowest fluence value consists of the original Ti grains. This is evidence that preferential …


Micro/Nanostructures Formation By Femtosecond Laser Surface Processing On Amorphous And Polycrystalline Ni60nb40, Edwin Peng, Alfred Tsubaki, Craig A. Zuhlke, Meiyu Wang, Ryan Bell, Michael J. Lucis, Troy P. Anderson, Dennis R. Alexander, George Gogos, Jeffrey E. Shield Jan 2017

Micro/Nanostructures Formation By Femtosecond Laser Surface Processing On Amorphous And Polycrystalline Ni60nb40, Edwin Peng, Alfred Tsubaki, Craig A. Zuhlke, Meiyu Wang, Ryan Bell, Michael J. Lucis, Troy P. Anderson, Dennis R. Alexander, George Gogos, Jeffrey E. Shield

Department of Mechanical and Materials Engineering: Faculty Publications

Femtosecond laser surface processing is a technology that can be used to functionalize many surfaces, imparting specialized properties such as increased broadband optical absorption or superhydrophilicity/superhydrophobicity. In this study, two unique classes of surface structures, below surface growth (BSG) and above surface growth (ASG) mounds, were formed by femtosecond laser surface processing on amorphous and polycrystalline Ni60Nb40 with two different grain sizes. Cross sectional imaging of these mounds revealed thermal evidence of the unique formation processes for each class of surface structure. BSG mounds formed on all three substrates using the same laser parameters had similar surface …


Design And Field Testing Of A Combined Flaming And Cultivation Implement For Effective Weed Control, Brian D. Neilson, Chris A. Bruening, Strahinja Stepanovic, Avishek Datta, Stevan Z. Knezevic, George Gogos Jan 2017

Design And Field Testing Of A Combined Flaming And Cultivation Implement For Effective Weed Control, Brian D. Neilson, Chris A. Bruening, Strahinja Stepanovic, Avishek Datta, Stevan Z. Knezevic, George Gogos

Department of Mechanical and Materials Engineering: Faculty Publications

Flaming is a thermal weed control method that uses heat to control weeds within or between crop rows. Mechanical cultivation is another weed control method which undercuts weeds between crop rows, while leaving a strip of weeds within the crop row. A combination flamer/cultivator implement was designed to take advantage of the good qualities of both flaming and cultivation methods to provide a more consistent weed control than using either flaming or mechanical cultivation alone. Flaming hoods were designed in the spring of 2010 and retrofitted on an existing row crop cultivator. The flaming hoods were redesigned in the spring …