Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- BRC (3)
- Nanoparticles (2)
- Atomic force microscopy (1)
- Biology (1)
- Cancer (1)
-
- Contact resistance (1)
- Crystal structure (1)
- Crystallographic defects (1)
- Cytotoxicity (1)
- Doping (1)
- Electron densities of states (1)
- Epitaxy (1)
- Excitons (1)
- Gold (1)
- Green chemistry (1)
- III-V semiconductors (1)
- Ice sheet (1)
- Lakes (1)
- Magnetic moments (1)
- Mud (1)
- Nanofabrication (1)
- Nanowires (1)
- Oxides (1)
- Petrology (1)
- Photoelectron spectroscopy (1)
- Photoluminescence (1)
- Photoluminescence spectroscopy (1)
- Ponds (1)
- Quantum dots (1)
- Sea ice (1)
Articles 1 - 10 of 10
Full-Text Articles in Physics
Strain-Driven Growth Of Gaas(111) Quantum Dots With Low Fine Structure Splitting, Paul J. Simmonds
Strain-Driven Growth Of Gaas(111) Quantum Dots With Low Fine Structure Splitting, Paul J. Simmonds
Physics Faculty Publications and Presentations
Symmetric quantum dots (QDs) on (111)-oriented surfaces are promising candidates for generating polarization-entangled photons due to their low excitonic fine structure splitting(FSS). However, (111) QDs are difficult to grow. The conventional use of compressive strain to drive QD self-assembly fails to form 3D nanostructures on (111) surfaces. Instead, we demonstrate that (111) QDs self-assemble under tensile strain by growing GaAs QDs on an InP(111)A substrate. Tensile GaAs self-assembly produces a low density of QDs with a symmetric triangular morphology. Coherent, tensile QDs are observed without dislocations, and the QDs luminescence at room temperature. Single QD measurements reveal low FSS with …
Kinetic Competition During The Transcription Cycle Results In Stochastic Rna Processing, Antoine Coulon, Matthew L. Ferguson, Valeria De Turris, Murali Palangat, Carson C. Chow, Daniel R. Larson
Kinetic Competition During The Transcription Cycle Results In Stochastic Rna Processing, Antoine Coulon, Matthew L. Ferguson, Valeria De Turris, Murali Palangat, Carson C. Chow, Daniel R. Larson
Physics Faculty Publications and Presentations
Synthesis of mRNA in eukaryotes involves the coordinated action of many enzymatic processes, including initiation, elongation, splicing, and cleavage. Kinetic competition between these processes has been proposed to determine RNA fate, yet such coupling has never been observed in vivo on single transcripts. In this study, we use dual-color single-molecule RNA imaging in living human cells to construct a complete kinetic profile of transcription and splicing of the β-globin gene. We find that kinetic competition results in multiple competing pathways for pre-mRNA splicing. Splicing of the terminal intron occurs stochastically both before and after transcript release, indicating there is not …
Sliding Rocks On Racetrack Playa, Death Valley National Park: First Observation Of Rocks In Motion, Richard D. Norris, James M. Norris, Ralph D. Lorenz, Jib Ray, Brian Jackson
Sliding Rocks On Racetrack Playa, Death Valley National Park: First Observation Of Rocks In Motion, Richard D. Norris, James M. Norris, Ralph D. Lorenz, Jib Ray, Brian Jackson
Physics Faculty Publications and Presentations
The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved >60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 …
Radical Constructivism And Social Justice: Educational Implications, Dewey I. Dykstra Jr.
Radical Constructivism And Social Justice: Educational Implications, Dewey I. Dykstra Jr.
Physics Faculty Publications and Presentations
Upshot • Gash describes some very interesting and exemplary work using RC-influenced research and practices. I worry that his third stage of a three-stage emergence of constructivist epistemology in the study of cognitive development is consistent with a distinction between focus on individual cognitive development and focus on knowledge not in the mind but in the group, inconsistent with RC. An alternative is given and the issue of an RC perspective on social justice is discussed.
Cytotoxicity Of Zno Nanoparticles Can Be Tailored By Modifying Their Surface Structure: A Green Chemistry Approach For Safer Nanomaterials, Alex Punnoose, Kelsey Dodge, John W. Rasmussen, Jordan Chess, Denise Wingett, Catherine Anders
Cytotoxicity Of Zno Nanoparticles Can Be Tailored By Modifying Their Surface Structure: A Green Chemistry Approach For Safer Nanomaterials, Alex Punnoose, Kelsey Dodge, John W. Rasmussen, Jordan Chess, Denise Wingett, Catherine Anders
Physics Faculty Publications and Presentations
ZnO nanoparticles (NP) are extensively used in numerous nanotechnology applications; however, they also happen to be one of the most toxic nanomaterials. This raises significant environmental and health concerns and calls for the need to develop new synthetic approaches to produce safer ZnO NP, while preserving their attractive optical, electronic, and structural properties. In this work, we demonstrate that the cytotoxicity of ZnO NP can be tailored by modifying their surface-bound chemical groups, while maintaining the core ZnO structure and related properties. Two equally sized (9.26 ± 0.11 nm) ZnO NP samples were synthesized from the same zinc acetate precursor …
Magnetism Of Zn-Doped Sno2: Role Of Surfaces, Pushpa Raghani, Balaji Ramanujam
Magnetism Of Zn-Doped Sno2: Role Of Surfaces, Pushpa Raghani, Balaji Ramanujam
Physics Faculty Publications and Presentations
Surface effects on the magnetization of Zn-doped SnO2 are investigated using first principles method. Magnetic behavior of Zn-doped bulk and highest and lowest energy surfaces—(001) and (110), respectively, are investigated in presence and absence of other intrinsic defects. The Zn-doped (110) and (001) surfaces of SnO2 show appreciable increase in the magnetic moment (MM) compared to Zn-doped bulk SnO2. Formation energies of Zn defects on both the surfaces are found to be lower than those in bulk SnO2. Zn doping favors the formation of oxygen vacancies. The density of states analysis on the Zn-doped …
Defect Induced Ferromagnetism In Undoped Zno Nanoparticles, K. Rainey, J. Chess, J. Eixenberger, D. A. Tenne, C. B. Hanna, A. Punnoose
Defect Induced Ferromagnetism In Undoped Zno Nanoparticles, K. Rainey, J. Chess, J. Eixenberger, D. A. Tenne, C. B. Hanna, A. Punnoose
Physics Faculty Publications and Presentations
Undoped ZnO nanoparticles (NPs) with size ∼12 nm were produced using forced hydrolysis methods using diethylene glycol (DEG) [called ZnO-I] or denatured ethanol [called ZnO-II] as the reaction solvent; both using Zn acetate dehydrate as precursor. Both samples showed weak ferromagnetic behavior at 300 K with saturation magnetization Ms = 0.077 ± 0.002 memu/g and 0.088 ± 0.013 memu/g for ZnO-I and ZnO-II samples, respectively. Fourier transform infrared(FTIR) spectra showed that ZnO-I nanocrystals had DEG fragments linked to their surface. Photoluminescence (PL) data showed a broad emission near 500 nm for ZnO-II which is absent in the ZnO-I samples, …
Dopant Spin States And Magnetism Of Sn1−XFeXO2 Nanoparticles, A. Punnoose, Kelsey Dodge, J. J. Beltrán, K. M. Reddy, Nevil Franco, Jordan Chess, Josh Eixenberger
Dopant Spin States And Magnetism Of Sn1−XFeXO2 Nanoparticles, A. Punnoose, Kelsey Dodge, J. J. Beltrán, K. M. Reddy, Nevil Franco, Jordan Chess, Josh Eixenberger
Physics Faculty Publications and Presentations
This work reports detailed investigations of a series of ∼2.6 nm sized, Sn1−xFexO2 crystallites with x = 0–0.10 using Mossbauer spectroscopy, x-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy (EPR), and magnetometry to determine the oxidation state of Fe dopants and their role in the observed magnetic properties. The magnetic moment per Fe ion μ was the largest ∼6.48 × 10−3 μB for the sample with the lowest (0.001%) Fe doping, and it showed a rapid downward trend with increasing Fe doping. Majority of the Fe ions are in 3+ oxidation state occupying octahedral …
Reproducible Nanostructure Fabrication Using Atomic Force Microscopy Indentation With Minimal Tip Damage, Seunghee Jeon, Bongwoo Ryu, Wonho Jhe, Zheong G. Khim, Byung I. Kim
Reproducible Nanostructure Fabrication Using Atomic Force Microscopy Indentation With Minimal Tip Damage, Seunghee Jeon, Bongwoo Ryu, Wonho Jhe, Zheong G. Khim, Byung I. Kim
Physics Faculty Publications and Presentations
A uniform pattern of quantum dots and nanowires were reproducibly fabricated by creating holes in a two-layer structure using atomic force microscopy (AFM) indentation, dry-etching of polymer resists, and metal deposition through the indentation holes. The two-layer structure was created by depositing a thin gold layer onto a polymethyl methacrylate (PMMA) layer on a silicon substrate. The indentation depth was set so that the AFM tip penetrated the thin gold layer without the tip contacting the silicon substrate. This two-layer indentation was used to create a pattern of holes in the thin gold layer. Then, the PMMA was exposed to …
Force-Feedback High-Speed Atomic Force Microscope, Byung I. Kim, Ryan D. Boehm
Force-Feedback High-Speed Atomic Force Microscope, Byung I. Kim, Ryan D. Boehm
Physics Faculty Publications and Presentations
High-speed atomic force microscopy (HSAFM) has enabled researchers to view the nanometer-scale dynamic behavior of individual biological and bio-relevant molecules at a molecular-level resolution under physiologically relevant time scales, which is the realization of a dream in life sciences. These high-speed imaging applications now extend to the cellular/bacterial systems with the use of a smaller cantilever. By reducing the sizes of the HSAFM cantilevers by a factor of ten, systems have demonstrated image speeds up to 0.1 frames per second for larger biological systems such as bacteria. However, this imaging speed is insufficient to understand many rapid large-scale biological phenomena. …