Engineering Commons^™

Background Differences In Baseline And Stimulated Mmp Levels Influence Abdominal Aortic Aneurysm Susceptibility, Matthew A. Dale, Melissa K. Suh, Shijia Zhao, Trevor Meisinger, Linxia Gu, Vicki J. Swier, Devendra K. Agrawal, Timothy Greiner, Jeffrey S. Carson, B. Timothy Baxter, Wanfen Xiong

Department of Mechanical and Materials Engineering: Faculty Publications

Objective: Evidence has demonstrated profound influence of genetic background on cardiovascular phenotypes. Murine models in Marfan syndrome (MFS) have shown that genetic background-related variations affect thoracic aortic aneurysm formation, rupture, and lifespan of mice. MFS mice with C57Bl/6 genetic background are less susceptible to aneurysm formation compared to the 129/SvEv genetic background. In this study, we hypothesize that susceptibility to abdominal aortic aneurysm (AAA) will be increased in 129/SvEv mice versus C57Bl/6 mice. We tested this hypothesis by assessing differences in aneurysm size, tissue properties, immune response, and MMP expression.

Methods: Mice of C57Bl/6 or 129/SvEv background underwent AAA induction …

Imaging Thermal Conductivity With Nanoscale Resolution Using A Scanning Spin Probe, Abdelghani Laraoui, Halley Aycock-Rizzo, Yang Gao, Xi Lu, Elisa Riedo, Carlos A. Meriles

Department of Mechanical and Materials Engineering: Faculty Publications

The ability to probe nanoscale heat flow in a material is often limited by lack of spatial resolution. Here, we use a diamond-nanocrystal-hosted nitrogen-vacancy centre attached to the apex of a silicon thermal tip as a local temperature sensor. We apply an electrical current to heat up the tip and rely on the nitrogen vacancy to monitor the thermal changes the tip experiences as it is brought into contact with surfaces of varying thermal conductivity. By combining atomic force and confocal microscopy, we image phantom microstructures with nanoscale resolution, and attain excellent agreement between the thermal conductivity and topographic maps. …

System And Method For Estimating States Of Spacecraft In Planet-Moon Environment, Piyush Grover

Department of Mechanical and Materials Engineering: Faculty Publications

A method estimates a state of a spacecraft in a planet-moon environment by executing iteratively a particle filter. The particle filter comprising integrates individually states of each particle of the particle filter according to a probability-evolution equation using a model of the state of the spacecraft represented as a planar circular restricted three-body problem and determines a prior probability of each particle as a previous posterior probability of a corresponding particle during a previous iteration. A joint probability distribution of the state of the spacecraft is determines using the states of each particle and the prior probabilities of each particle …

An Estimate Of The Second-Order In-Plane Acceleration Sensitivity Of A Y-Cut Quartz Thickness-Shear Resonator, Huijing He, Jiashi Yang, John A. Kosinski

Department of Mechanical and Materials Engineering: Faculty Publications

We perform a theoretical analysis of the second-order in-plane acceleration sensitivity of a Y-cut quartz thick-ness-shear mode resonator. The second-order nonlinear theory of elasticity for anisotropic crystals is used to determine the biasing fields in the resonator under in-plane acceleration. The acceleration-induced frequency shift is determined from a per-turbation analysis based on the plate equations for small-amplitude vibrations superposed on a finite bias. We show that, whereas the first-order acceleration-induced frequency shift is zero for a structurally symmetric resonator under in-plane ac-celeration, the second-order frequency shift is nonzero and is quadratic in the acceleration. As the fourth-order nonlinear elastic constants …

Biodegradable Medical Device Having An Adjustable Degradation Rate And Methods Of Making The Same, Yuebin Guo, Michael Sealy, Meisam Salahshoor Pirsoltan

Department of Mechanical and Materials Engineering: Faculty Publications

Disclosed herein are biodegradable medical devices comprising biodegradable material (e.g., magnesium-calcium alloys) having an adjustable rate of degradation that can be used in various applications, including, but not limited to, drug delivery applications, cardiovascular applications, and orthopedic applications to make biodegradable and biocompatible devices. Also disclosed herein are methods of making biodegradable medical devices comprising biodegradable materials by using, for instance, hybrid dry cutting/hydrostatic burnishing.

Non-Wetting Surface-Driven High-Aspect-Ratio Crystalline Grain Growth For Efficient Hybrid Perovskite Solar Cells, Cheng Bi, Qi Wang, Yongbo Yuan, Zhengguo Xiao, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

Large-aspect-ratio grains are needed in polycrystalline thin-film solar cells for reduced charge recombination at grain boundaries; however, the grain size in organolead trihalide perovskite (OTP) films is generally limited by the film thickness. Here we report the growth of OTP grains with high average aspect ratio of 2.3–7.9 on a wide range of non-wetting hole transport layers (HTLs), which increase nucleus spacing by suppressing heterogeneous nucleation and facilitate grain boundary migration in grain growth by imposing less drag force. The reduced grain boundary area and improved crystallinity dramatically reduce the charge recombination in OTP thin films to the level in …

Local Control Robotic Surgical Devices And Related Methods, Eric Markvicka, Tom Frederick, Jack Mondry, Joe Bartels, Shane Farritor

Department of Mechanical and Materials Engineering: Faculty Publications

The various robotic medical devices include robotic devices that are disposed within a body cavity and positioned using a support component disposed through an orifice or opening in the body cavity. Additional embodiments relate to devices having arms coupled to a device body wherein the device has a minimal profile such that the device can be easily inserted through smaller incisions in comparison to other devices without such a small profile. Further embodiments relate to methods of operating the above devices.

Methods And Systems For Handling Or Delivering Materials For Natural Orifice Surgery, Carl Nelson, Jeff Midday, Dimitry Oleynikov, Alan Goyzueta

Department of Mechanical and Materials Engineering: Faculty Publications

The embodiments disclosed herein relate to various medical systems, including systems that can be used in conjunction with medical devices used in endoscopic surgery. Certain embodiments include various material handling devices that can transport materials between the inside and the outside of an endoscopic surgery patient.

Development And Preliminary Evaluation Of A Spray Deposition Sensing System For Improving Pesticide Application, Melissa A. Kesterson, Joe D. Luck, Michael P. Sama

Department of Mechanical and Materials Engineering: Faculty Publications

An electronic, resistance-based sensor array and data acquisition system was developed to measure spray deposition from hydraulic nozzles. The sensor surface consisted of several parallel tin plated copper traces of varying widths with varying gap widths. The system contained an embedded microprocessor to monitor output voltage corresponding to spray deposition every second. In addition, a wireless module was used to transmit the voltage values to a remote laptop. Tests were conducted in two stages to evaluate the performance of the sensor array in an attempt to quantify the spray deposition. Initial tests utilized manual droplet placement on the sensor surface …

Enhanced Pool-Boiling Heat Transfer And Critical Heat Flux On Femtosecond Laser Processed Stainless Steel Surfaces, Cory M. Kruse, Troy Anderson, Chris Wilson, Craig Zuhlke, Dennis Alexander, George Gogos, Sidy Ndao

Department of Mechanical and Materials Engineering: Faculty Publications

In this paper, we present an experimental investigation of pool boiling heat transfer on multiscale (micro/nano) functionalized metallic surfaces. Heat transfer enhancement in metallic surfaces is very important for large scale high heat flux applications like in the nuclear power industry. The multiscale structures were fabricated via a femtosecond laser surface process (FLSP) technique, which forms self-organized mound-like microstructures covered by layers of nanoparticles. Using a pool boiling experimental setup with deionized water as the working fluid, both the heat transfer coefficients and critical heat flux were investigated. A polished reference sample was found to have a critical heat flux …

Characterization Of Closed Head Impact Injury In Rat, Yi Hua, Praveen Akula, Matthew Kelso, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

The closed head impact (CHI) rat models are commonly used for studying the traumatic brain injury. The impact parameters vary considerably among different laboratories, making the comparison of research findings difficult. In this work, numerical CHI experiments were conducted to investigate the sensitivities of intracranial responses to various impact parameters (e.g., impact depth, velocity, and position; impactor diameter, material, and shape). A three-dimensional finite element rat head model with anatomical details was subjected to impact loadings. Results revealed that impact depth and impactor shape were the two leading factors affecting intracranial responses.The influence of impactor diameter was region-specific and an …

Self‑Propelled Droplets On Heated Surfaces With Angled Self‑Assembled Micro/Nanostructures, Cory Kruse, Isra Somanas, Troy Anderson, Chris Wilson, Craig Zuhlke, Dennis Alexander, George Gogos, Sidy Ndao

Department of Mechanical and Materials Engineering: Faculty Publications

Directional and ratchet-like functionalized surfaces can induce liquid transport without the use of an external force. In this paper, we investigate the motion of liquid droplets near the Leidenfrost temperature on functionalized self-assembled asymmetric microstructured surfaces. The surfaces, which have angled microstructures, display unidirectional properties. The surfaces are fabricated on stainless steel through the use of a femtosecond laser-assisted process. Through this process, mound-like microstructures are formed through a combination of material ablation, fluid flow, and material redeposition. In order to achieve the asymmetry of the microstructures, the femtosecond laser is directed at an angle with respect to the sample …

Voigt, Reuss, Hill, And Self-Consistent Techniques For Modeling Ultrasonic Scattering, Christopher M. Kube, Joseph A. Turner

Department of Mechanical and Materials Engineering: Faculty Publications

An elastic wave propagating in a metal loses a portion of its energy from scattering caused by acoustic impedance differences existing at the boundaries of anisotropic grains. Theoretical scattering models capture this phenomena by assuming the incoming wave is described by an average elastic moduli tensorC_0ijkl (x) that is perturbed by a grain with elasticityC_ijkl (x ') where the scattering event occurs when x = x’. Previous models have assumed that C_0ijkl (x) is the Voigt average of the singlecrystal elastic moduli tensor. However, this assumption …

Acoustic Nonlinearity Parameters For Transversely Isotropic Polycrystalline Materials, Christopher M. Kube, Joseph A. Turner

Department of Mechanical and Materials Engineering: Faculty Publications

This article considers polycrystalline materials with macroscopic elastic anisotropy and the effect of the anisotropy on the quadratic nonlinearity parameter used to describe second harmonic generation in solids. The polycrystal is assumed to have transversely isotropic elastic symmetry, which leads to a directional dependence of the nonlinearity parameters. Additionally, the anisotropy leads to second harmonic generation from an input shear wave. Estimates of the longitudinal and shear wave nonlinearity parameters are given as a function of single-crystal elastic constants, macroscopic anisotropy constants, and propagation direction. An inverse model is presented that relates measured nonlinearity parameters to the macroscopic anisotropy constants. …

Acoustic Attenuation Coefficients For Polycrystalline Materials Containing Crystallites Of Any Symmetry Class, Christopher M. Kube, Joesph A. Turner

Department of Mechanical and Materials Engineering: Faculty Publications

This letter provides a theoretical extension to the elastic properties of polycrystals in order to describe elastic wave scattering from grain boundaries. The extension allows the longitudinal and shear attenuation coefficients for scattering to be derived and is valid for polycrystals containing crystallites of any symmetry class. Attenuation curves are given for polycrystalline SiO₂, ZrO₂, and SnF₂, which contain monoclinic crystallites. This work will allow ultrasonic techniques to be applied to new classes of materials containing nontrivial microstructures.

Interfacial Electronic Structure At The Ch3nh3pbi3/Moox Interface, Peng Liu, Xiaoliang Liu, Lu Lyu, Haipeng Xie, Hong Zhang, Dongmei Niu, Han Huang, Cheng Bi, Zhengguo Xiao, Jinsong Huang, Yongli Gao

Department of Mechanical and Materials Engineering: Faculty Publications

Interfacial electronic properties of the CH₃NH₃PbI₃ (MAPbI₃)/M_oOx interface are investigated using ultraviolet photoemission spectroscopy and X-ray photoemission spectroscopy. It is found that the pristine MAPbI₃ film coated onto the substrate of poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate)/indium tin oxide by two-step method behaves as an n-type semiconductor, with a band gap of ~1.7 eV and a valence band edge of 1.40 eV below the Fermi energy (EF). With the MoOx deposition of 64A ° upon MAPbI3, the energy levels of MAPbI3 shift toward higher binding energy by 0.25 eV due to electron transfer …

Erratum: “The Operation Mechanism Of Poly (9,9-Dioctylfluorenyl-2,7-Diyl) Dots In High Efficiency Polymer Solar Cells” [Appl. Phys. Lett. 106, 193904 (2015)], Chunyu Liu, Yeyuan He, Xinyuan Zhang, Zhiqi Li, Jinfeng Li, Liang Shen, Zhihui Zhang, Wenbin Guo, Shengping Ruan

Department of Mechanical and Materials Engineering: Faculty Publications

We have noticed an error in Fig. 7 of the original article. Figs. 7(a) and 7(b) should be exchanged and the revised figure is shown below. We apologize for this error.¹

The Operation Mechanism Of Poly(9,9-Dioctylfluorenyl-2,7-Diyl) Dots In High Efficiency Polymer Solar Cells, Chunyu Liu, Yeyuan He, Xinyuan Zhang, Zhiqi Li, Liang Shen, Zhihui Zhang, Wenbin Guo, Shengping Ruan

Department of Mechanical and Materials Engineering: Faculty Publications

The highly efficient polymer solar cells were realized by doping poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) dots into active layer. The dependence of doping amount on devices performance was investigated and a high efficiency of 7.15% was obtained at an optimal concentration, accounting for a 22.4% enhancement. The incorporation of PFO dots (Pdots) is conducted to the improvement of Jsc and fill factor mainly due to the enhancement of light absorption and charge transport property. Pdots blended in active layer provides an interface for charge transfer and enables the formation of percolation pathways for electron transport. The introduction of Pdots was proven an effective …

Surface Analytical Investigation On Organometal Triiodide Perovskite, Chengong Wang, Xiaoliang Liu, Congcong Wang, Zhengguo Xiao, Cheng Bi, Yuchuan Shao, Jinsong Huang, Yongli Gao

Department of Mechanical and Materials Engineering: Faculty Publications

In a little over a year, there has been an unexpected breakthrough and rapid evolution of highly efficient solid-state hybrid solar cells based on organometal trihalide perovskite materials. This technology has the potential to produce solar cells with the very highest efficiencies while retaining the very lowest cost. The authors have measured the electronic density of states of CH₃NH₃PbI₃ using ultraviolet photoemission spectroscopy (UPS), inverse photoemission spectroscopy (IPES), and x-ray photoemission spectroscopy (XPS). The valence band maximum and conduction band minimum positions are obtained from the UPS and IPES spectra, respectively, by linear extrapolation of …

Blast-Induced Mild Traumatic Brain Injury Through Ear Canal: A Finite Element Study, Praveen Akula, Yi Hua, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Purpose The role of ear canal in transmitting blast waves to the brain is not clear. The goal of this work is to characterize the influence of ear canal on blast-induced mild traumatic brain injury through a computational approach.

Methods A three-dimensional human head model with single-side ear canal details was reconstructed from computed tomography images. The ear canal was positioned either facing the incident blast wave or facing away from the blast wave.

Results The blast wave-head interaction has demonstrated that the overpressure within the ear canal was substantially amplified when the ear directly faced the blast wave. When …

Phase Transformation And Magnetic Properties Of Rapidly Solidified Mn-Al-C Alloys Modified With Zr, Yunlong Geng, Micheal J. Lucis, Pamela Rasmussen, Jeffrey E. Shield

Department of Mechanical and Materials Engineering: Faculty Publications

Mn_54-xAl₄₃C₃Zr_x (x=1, 3) alloys were prepared by rapid solidification followed by heat treatment to produce the ferromagnetic s phase. The substitution of Zr for Mn in the structure resulted in an increase of the saturation magnetization (Ms) compared to that of Mn_54-xAl₄₃C₃. While the highest Ms (12861 emu/g) was obtained in Mn_54-xAl₄₃C₃Zr₁, the coercivity was also improved to 1.62 kOe, compared to 1.25 kOe for Mn_54-xAl₄₃C₃. To further improve the coercivity through grain …

Extracting Continuum-Like Deformation And Stress From Molecular Dynamics Simulations, Lili Zhang, John Jasa, George Gazonas, Antoine Jerusalem, Mehrdad Negahban

Department of Mechanical and Materials Engineering: Faculty Publications

We present methods that use results from molecular dynamics (MD) simulations to construct continuum parameters, such as deformation gradient and Cauchy stress, from all or any part of an MD system. These parameters are based on the idea of minimizing the difference between MD measures for deformation and traction and their continuum counterparts. The procedures should be applicable to non-equilibrium and inhomogeneous systems, and to any part of a system, such as a polymer chain. The resulting procedures provide methods to obtain first and higher order deformation gradients associated with any subset of the MD system, and associated expressions for …

Evaluation Of Peritoneal Microbubble Oxygenation Therapy In A Rabbit Model Of Hypoxemia, Nathan D. Legband, Jameel A. Feshitan, Mark A. Borden, Benjamin S. Terry

Department of Mechanical and Materials Engineering: Faculty Publications

Alternative extrapulmonary oxygenation technologies are needed to treat patients suffering from severe hypoxemia refractory to mechanical ventilation. We previously demonstrated that peritoneal microbubble oxygenation (PMO), in which phospholipid-coated oxygen microbubbles (OMBs) are delivered into the peritoneal cavity, can successfully oxygenate rats suffering from a right pneumothorax. This study addressed the need to scale up the procedure to a larger animal with a splanchnic cardiac output similar to humans. Our results show that PMO therapy can double the survival time of rabbits experiencing complete tracheal occlusion from6.6 ± 0.6 min for the saline controls to 12.2 ± 3.0 min for the …

Electronic Structure Evolution Of Fullerene On Ch3Nh3Pbi3, Chenggong Wang, Congcong Wang, Xiaoliang Liu, John Kauppi, Yuchuan Shao, Zhengguo Xiao, Cheng Bi, Jinsong Huang, Yongli Gao

Department of Mechanical and Materials Engineering: Faculty Publications

The thickness dependence of fullerene on CH₃NH₃PbI₃ perovskite film surface has been investigated by using ultraviolet photoemission spectroscopy (UPS), X-ray photoemission spectroscopy (XPS), and inverse photoemission spectroscopy (IPES). The lowest unoccupied molecular orbital and highest occupied molecular orbital (HOMO) can be observed directly with IPES and UPS. It is observed that the HOMO level in fullerene shifts to lower binding energy. The XPS results show a strong initial shift of core levels to lower binding energy in the perovskite, which indicates that electrons transfer from the perovskite film to fullerene molecules. Further deposition of fullerene …

Improving The Sensitivity Of A Near-Infrared Nanocomposite Photodetector By Enhancing Trap Induced Hole Injection, Liang Shen, Yanjun Fang, Qingfeng Dong, Zhengguo Xiao, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

We report the enhancement of the photoconductive gain of nanocomposite near-infrared photodetectors by a zinc oxide nanoparticles (ZnO NPs) rich surface at the nanocomposite/cathode interface. An argon plasma etching process was used to remove polymer at the surface of nanocomposite films, which resulted in a ZnO NPs rich surface. The other way is to spin-coat a thin layer of ZnO NPs onto the nanocomposite layer. The ZnO NPs rich surface, which acts as electron traps to induce secondary hole injection under reverse bias, increased hole injection, and thus the external quantum efficiency by 2–3 times. The darkcurrent declined one order …

Efficiency Enhancement In Polymer Solar Cells With A Polar Small Molecule Both At Interface And In The Bulk Heterojunction Layer, Zhengguo Xiao, Qingfeng Dong, Qi Wang, Wenjing Tian, Hui Huang, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

The polar molecules, including ferroelectric materials with large dipole moments, have been applied as interfacial layers to increase the efficiency of organic solar cells by increasing the bounded charge separation, tuning the energy levels, etc. Here, we report a small polar molecule 2-cyano-3- (4-(diphenylamino) phenyl)acrylic acid (TPACA) that can be either blended in the active layer or at the polymer/electrode interface to increase the efficiency of organic solar cell devices after poling. It is found that the built-in potential of the device is increased by 0.2 V after poling under negative bias. Blending TPACA into the active layer has shown …

Chloride Incorporation Process In Ch3Nh3Pbi3-XClX Perovskites Via Nanoscale Bandgap Maps, Jungseok Chae, Qingfeng Dong, Jinsong Huang, Andrea Centrone

Department of Mechanical and Materials Engineering: Faculty Publications

CH₃NH₃PbI_3-xCl_x perovskites enable fabrication of highly efficient solar cells. Chloride ions benefit the morphology, carrier diffusion length and stability of perovskite films; however, whether those benefits stem from the presence of Cl⁻ in the precursor solution or from their incorporation in annealed films is debated. In this work, the photothermal induced resonance (PTIR), an in situ technique with nanoscale resolution, is leveraged to measure the bandgap of CH₃NH₃PbI_3-xCl_x films obtained by a multicycle coating process that produces high efficiency (≈16 %) solar cells. Because chloride …

Electron-Hole Diffusion Lengths >175 Μm In Solution-Grown Ch3Nh3Pbi3 Single Crystals, Qingfeng Dong, Yanjun Fang, Yuchuan Shao, Padhraic Mulligan, Jie Qiu, Lei Cao, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

Long, balanced electron and hole diffusion lengths greater than 100 nanometers in polycrystalline CH₃NH₃PbI₃ are critical for highly efficient perovskite solar cells. We report that the diffusion lengths in CH₃NH₃PbI₃ single crystals grown by a solution-growth method can exceed 175 μm under 1 sun illumination and exceed 3 mm under weak light for both electrons and holes. The internal quantum efficiencies approach 100% in 3 mm-thick single crystal perovskite solar cells under weak light. These long diffusion lengths result from greater carrier mobility, lifetime and dramatically smaller trap densities in …

Relevance Of Blood Vessel Networks In Blast-Induced Traumatic Brain Injury, Yi Hua, Shengmao Lin, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Cerebral vasculature is a complex network that circulates blood through the brain. However, the role of this networking effect in brain dynamics has seldom been inspected. This work is to study the effects of blood vessel networks on dynamic responses of the brain under blast loading. Voronoi tessellations were implemented to represent the network of blood vessels in the brain. The brain dynamics in terms of maximumprincipal strain (MPS), shear strain (SS), and intracranial pressure (ICP) weremonitored and compared. Results show that blood vessel networks significantly affected brain responses.The increased MPS and SS were observed within the brain embedded with …

Role Of Interphase In The Mechanical Behavior Of Silica/Epoxy Resin Nanocomposites, Yi Hua, Linxia Gu, Sundaralingam Premaraj, Xiaodong Zhang

Department of Mechanical and Materials Engineering: Faculty Publications

A nanoscale representative volume element has been developed to investigate the effect of interphase geometry and property on the mechanical behavior of silica/epoxy resin nanocomposites. The role of interphase–matrix bonding was also examined. Results suggested that interphase modulus and interfacial bonding conditions had significant influence on the effective stiffness of nanocomposites, while its sensitivities with respect to both the thickness and the gradient property of the interphase was minimal. The stiffer interphase demonstrated a higher load-sharing capacity, which also increased the stress distribution uniformity within the resin nanocomposites. Under the condition of imperfect interfacial bonding, the effective stiffness of nanocomposites …