Growth Mechanisms Of Multiscale, Mound-Like Surface Structures
On Titanium By Femtosecond Laser Processing,
2017
University of Nebraska-Lincoln
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 …
Dissipative Elastic Metamaterial With A Lowfrequency
Passband,
2017
Peking University
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 …
Narrowband Nanocomposite Photodetector,
2017
Lincoln, NE
Narrowband Nanocomposite Photodetector, Jinsong Huang, Fawen Guo, Liang Shen
Department of Mechanical and Materials Engineering: Faculty Publications
A photodetector includes an anode that is transparent or partially transparent to light, a cathode and an active layer disposed between the anode and the cathode. The active layer includes a nanocomposite material that has a polymer blended with nanoparticles or organic electron trapping particles. The photodetector has a low dark current when not illuminated by light and has a high conductivity when illuminated by light, in which the light passes the anode and is absorbed by the active layer. The active layer has a thickness selected such that the photodetector has a narrowband spectral response.
Role Of Copper Oxide Layer On Pool Boiling Performance With Femtosecond Laser Processed Surfaces,
2017
University of Nebraska-Lincoln
Role Of Copper Oxide Layer On Pool Boiling Performance With Femtosecond Laser Processed Surfaces, Corey Kruse, Edwin Peng, Craig Zuhlke, Jeff Shield, Dennis Alexander, Sidy Ndao, George Gogos
Department of Mechanical and Materials Engineering: Faculty Publications
Copper pool boiling surfaces are tested for pool boiling enhancement due to femtosecond laser surface processing (FLSP). FLSP creates self-organized micro/nanostructures on metallic surfaces and creates highly wetting and wicking surfaces with permanent surface features. In this study two series of samples were created. The first series consists of three flat FLSP copper surfaces with varying microstructures and the second series is an open microchannel configuration with laser processing over the horizontal surfaces of the microchannels. These microchannels range in height from 125 microns to 380 microns. Each of these surfaces were tested for pool boiling performance. It was found …
Chalcogenide Nanocrystal Assembly: Controlling Heterogeneity And Modulating Heterointerfaces,
2017
Wayne State University
Chalcogenide Nanocrystal Assembly: Controlling Heterogeneity And Modulating Heterointerfaces, Jessica Davis Davis
Wayne State University Dissertations
This dissertation work is focused on developing methods to facilitate charge transport in heterostructured materials that comprise a nanoscale component. Multicomponent semiconductor materials were prepared by (1) spin coating of discrete nanomaterials onto porous silicon (pSi) or (2) self-assembly. Spin-coating of colloidal quantum dot (QD) PbS solutions was employed to create prototype PbS QD based radiation detection devices using porous silicon (pSi) as an n-type support and charge transport material. These devices were initially tested as a photodetector to ascertain the possibility of their use in high energy radiation detection. Short chain thiolate ligands (4-fluorothiophenolate) and anion passivation at the …
Level Anticrossing Of Impurity States In Semiconductor Nanocrystals,
2017
ITMO University, St. Petersbourg, Russia
Level Anticrossing Of Impurity States In Semiconductor Nanocrystals, Anvar S. Baimuratov, Ivan D. Rukhlenko, Vadim K. Turkov, Irina Ponomareva, Mikhail Yu Leonov, Tatiana S. Perova, Kevin Berwick, Alexander V. Baranov, Anatoly V. Federov
Articles
The size dependence of the quantized energies of elementary excitations is an essential feature of quantum nanostructures, underlying most of their applications in science and technology. Here we report on a fundamental property of impurity states in semiconductor nanocrystals that appears to have been overlooked—the anticrossing of energy levels exhibiting different size dependencies. We show that this property is inherent to the energy spectra of charge carriers whose spatial motion is simultaneously affected by the Coulomb potential of the impurity ion and the confining potential of the nanocrystal. The coupling of impurity states, which leads to the anticrossing, can be …
Atomically Informed Nonlocal Semidiscrete Variational Peierls-Nabarro Model For Planar Core Dislocations,
2017
Shanghai Jiao Tong University
Atomically Informed Nonlocal Semidiscrete Variational Peierls-Nabarro Model For Planar Core Dislocations, Guisen Liu, Xi Cheng, Jian Wang, Kaiguo Chen, Yao Shen
Department of Mechanical and Materials Engineering: Faculty Publications
Prediction of Peierls stress associated with dislocation glide is of fundamental concern in understanding and designing the plasticity and mechanical properties of crystalline materials. Here, we develop a nonlocal semi-discrete variational Peierls-Nabarro (SVPN) model by incorporating the nonlocal atomic interactions into the semi-discrete variational Peierls framework. The nonlocal kernel is simplified by limiting the nonlocal atomic interaction in the nearest neighbor region, and the nonlocal coefficient is directly computed from the dislocation core structure. Our model is capable of accurately predicting the displacement profile, and the Peierls stress, of planar-extended core dislocations in face-centered cubic structures. Our model could be …
Photoluminescence From Radiative Surface States And Excitons In Methylammonium Lead Bromide Perovskites,
2017
Delft University of Technology
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 …
Helium Irradiation And Implantation Effects On The Structure Of Amorphous Silicon Oxycarbide,
2017
University of Nebraska-Lincoln
Helium Irradiation And Implantation Effects On The Structure Of Amorphous Silicon Oxycarbide, Qing Su, Shinsuke Inoue, Manabu Ishimaru, Jennifer A. Gigax, Tianyao Wang, Hepeng Ding, Michael J. Demkowicz, Lin Shao, Michael Nastasi
Department of Mechanical and Materials Engineering: Faculty Publications
Despite recent interest in amorphous ceramics for a variety of nuclear applications, many details of their structure before and after irradiation/implantation remain unknown. Here we investigated the short-range order of amorphous silicon oxycarbide (SiOC) alloys by using the atomic pair-distribution function (PDF) obtained from electron diffraction. The PDF results show that the structure of SiOC alloys are nearly unchanged after both irradiation up to 30 dpa and He implantation up to 113 at%. TEM characterization shows no sign of crystallization, He bubble or void formation, or segregation in all irradiated samples. Irradiation results in a decreased number of Si-O bonds …
Suspended Graphene-Based Gas Sensor With 1-Mw Energy Consumption,
2017
University of Utah
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 …
Development Of Multilayer Titanium Nitride-Based Coatings As Corrosion Resistant Films For Stainless Steel Bipolar Plates In Pem Fuel Cells,
2017
University at Albany, State University of New York
Development Of Multilayer Titanium Nitride-Based Coatings As Corrosion Resistant Films For Stainless Steel Bipolar Plates In Pem Fuel Cells, Nicholas Padula
Legacy Theses & Dissertations (2009 - 2024)
High cost and short lifetime are the two main reasons why the PEM fuel cell has not reached a widespread, disruptive level of commercialization. Conventional graphite bipolar plates are responsible for about 45% of the cost and 85% of the total weight of a single cell. These measures are linked to difficult machining of thick, brittle graphite and processing needed to render graphite non-porous. Stainless steel is suggested as the replacement bipolar plate material due to its favorable mechanical properties, ease of manufacturing and relatively low price, but requires a cost-effective coating as a non-conductive oxide forms on the bare …
Redox-Dependent Calcium-Mediated Signaling Networks That Control The Senescence-Associated Secretory Phenotype,
2017
University at Albany, State University of New York
Redox-Dependent Calcium-Mediated Signaling Networks That Control The Senescence-Associated Secretory Phenotype, Akshaya Chandrasekaran
Legacy Theses & Dissertations (2009 - 2024)
Cellular senescence has evolved as a protective mechanism to arrest growth of cells with oncogenic potential. While senescent cells have lost the ability to divide, they remain metabolically active and adapt a deleterious senescence associated secretory phenotype (SASP) central to the progression of several age-associated disease pathologies. The SASP is mechanistically regulated by the pro-inflammatory cytokine interleukin-1 alpha (IL-1α) whose expression and activity is responsive to the senescence associated (SA) oxidant production and the accompanying disruption of calcium (Ca2+) homeostasis. Using primary IMR-90 human fetal lung fibroblasts as a model of replicative senescence, we explored the molecular underpinnings driving Ca2+ …
Computational Optimization And Characterization Of Molecularly Imprinted Polymers,
2017
University at Albany, State University of New York
Computational Optimization And Characterization Of Molecularly Imprinted Polymers, Jacob Jordan Terracina
Legacy Theses & Dissertations (2009 - 2024)
Molecularly imprinted polymers (MIPs) are a class of materials containing sites capable of selectively binding to the imprinted target molecule. Computational chemistry techniques were used to study the effect of different fabrication parameters (the monomer-to-target ratios, pre-polymerization solvent, temperature, and pH) on the formation of the MIP binding sites. Imprinted binding sites were built in silico for the purposes of better characterizing the receptor – ligand interactions. Chiefly, the sites were characterized with respect to their selectivities and the heterogeneity between sites.
Novel Approaches To Mitigating Bacterial Biofilm Formation And Intercellular Communication,
2017
University at Albany, State University of New York
Novel Approaches To Mitigating Bacterial Biofilm Formation And Intercellular Communication, Stephen Kasper
Legacy Theses & Dissertations (2009 - 2024)
Long thought of as solitary single-cell organisms, it is now widely accepted that bacteria can act and cooperate as social organisms. Phenomena such as biofilm formation and quorum sensing (QS) are two intimately intertwined cooperative behaviors that significantly contribute to the pathogenesis of many bacteria. Biofilms are surface associated communities of bacteria encased in a secreted extracellular matrix, which provides several advantages over an individualized lifestyle, such as increased protection from antimicrobial agents as well as enhanced opportunity for the exchange of genetic material. Bacterial QS is a system of population-based communication through the production, sensing, and response to chemical …
Towards A Biomimetic Elastin-Based Nanofiber Scaffold For Salivary Gland Tissue Regeneration And Growth Factor Delivery,
2017
University at Albany, State University of New York
Towards A Biomimetic Elastin-Based Nanofiber Scaffold For Salivary Gland Tissue Regeneration And Growth Factor Delivery, Zahraa Ismail Ahmed Foraida
Legacy Theses & Dissertations (2009 - 2024)
Development of electrospun nanofibers that mimic the structural, mechanical and biochemical properties of natural extracellular matrices (ECMs) and the basement membranes is a promising approach for tissue regeneration. Electrospun fibers of synthetic polymers partially mimic the topography of the ECM, however, their high stiffness, poor hydrophilicity and lack of in vivo-like biochemical cues is not optimal for epithelial cell self-organization and function. In search of a biomimetic scaffold for salivary gland tissue regeneration, we utilized proteins and peptides to induce biomechanical and biochemical cues that resembles the native tissue environment. These functional molecules were introduced to our previously-developed poly lactic-co-glycolic …
Multifunctional Nanomaterials Utilizing Hybridization Chain Reaction For Molecular Diagnostics And Bioanalytical Applications,
2017
University at Albany, State University of New York
Multifunctional Nanomaterials Utilizing Hybridization Chain Reaction For Molecular Diagnostics And Bioanalytical Applications, Md Muhit Rana
Legacy Theses & Dissertations (2009 - 2024)
DNA nanotechnology has shown great promise in molecular diagnostic, bioanalytical and biomedical applications. The great challenge of detecting target analytes, biomarkers and small molecules, in molecular diagnostics is low yield sensitivity. To address this challenge, different nanomaterials have been used for a long time and to date there is no such cost-effective bioanalytical technique which can detect these target biomarkers (DNA, RNA, circulating DNA/miRNA) or environmental heavy metal ions (Hg2+ and Ag+) in a cost-effective and efficient manner.
Novel Uses Of Directly Patternable Silicon Oxide Based Resist For Advanced Patterning Applications,
2017
University at Albany, State University of New York
Novel Uses Of Directly Patternable Silicon Oxide Based Resist For Advanced Patterning Applications, Vishal Umeshbhai Desai
Legacy Theses & Dissertations (2009 - 2024)
Novel applications for the directly-patternable resist material, hydrogen silsesquioxane (HSQ), were studied for multiple advanced lithography techniques. Initially, electron beam lithography (EBL) patterned low-resolution HSQ patterns were demonstrated as a mandrel in a self-aligned double patterning (SADP) approach. Using the novel EBL-SADP approach, the number of total process steps was reduced, as compared to conventional SADP methods. This work provided proof-of-concept for using HSQ resist as a directly-patternable mandrel and plasma enhanced chemical vapor deposited (PECVD) low-stress silicon nitride (LSSiN) as a spacer. Furthermore, rapid thermal annealing (RTA) was demonstrated as a method to increase the spacer etch resistance in …
Impedance Biosensors And Deep Crater Salivary Gland Scaffolds For Tissue Engineering,
2017
University at Albany, State University of New York
Impedance Biosensors And Deep Crater Salivary Gland Scaffolds For Tissue Engineering, Robert Arthur Schramm
Legacy Theses & Dissertations (2009 - 2024)
The salivary gland is a complex, branching organ whose primary biological function is the production of the fluid critical to alimentary function and the lubrication and maintenance of the oral cavity, saliva. The most frequent disruption of the salivary organ system is one in which the rate of supply of saliva into the oral cavity is diminished, and this may vary from a minor reduction, to near cessation. Regenerative medicine is a field which seeks to find ways to overcome the symptoms of organ malfunction or damage by inducing regrowth, repair and replacement of partial or whole organ function. Historically, …
Exploring Magnetic Nanostructures Embedded Within Single-Crystal Silicon For Generation Of Spin-Polarized Carriers,
2017
University at Albany, State University of New York
Exploring Magnetic Nanostructures Embedded Within Single-Crystal Silicon For Generation Of Spin-Polarized Carriers, Machara Krishna Girish Malladi
Legacy Theses & Dissertations (2009 - 2024)
Integrating magnetic functionalities with silicon holds the promise of developing, in the most dominant semiconductor, a paradigm-shift information technology based on the manipulation and control of electron spin and charge. Here, we demonstrate an ion implantation approach enabling the synthesis of a ferromagnetic layer within a defect free Si environment by exploiting an additional implant of hydrogen in a region deep below the metal implanted layer. Upon post-implantation annealing, nanocavities created within the H-implanted region act as trapping sites for gettering the implanted metal species, resulting in the formation of metal nanoparticles in a Si region of excellent crystal quality. …
Mechanisms Of Euv Exposure : Photons, Electrons And Holes,
2017
University at Albany, State University of New York
Mechanisms Of Euv Exposure : Photons, Electrons And Holes, Amrit Kausik Narasimhan
Legacy Theses & Dissertations (2009 - 2024)
The microelectronics industry’s movement toward smaller and smaller feature sizes has necessitated a shift to Extreme Ultra-Violet (EUV) lithography to be able to pattern sub 20-nm features, much like earlier shifts from i-line to 248 nm. However, this shift from 193-nm lithography to EUV (13.5 nm) poses significant obstacles. EUV is the first optical lithography to operate in an energy range (92 eV per photon vs. 6.4 eV per photon for 193 nm lithography) above the electron binding energies of common resist atomic species. This significant energy increase complicates resist design. For exposures of equal dose, resists receive 14 times …
