Physical Sciences and Mathematics Commons^™

Data From: Stability, Electronic, And Optical Properties Of Two-Dimensional Phosphoborane, Alexander I. Boldyrev, Nikolay Tkachenko

Browse all Datasets

The structure and properties of two-dimensional phosphoborane sheets were computationally investigated using Density Functional Theory calculations. The calculated phonon spectrum and band structure point to dynamic stability and allowed characterization of the predicted two-dimensional material as a direct-gap semiconductor with a band gap of ~1.5 eV. The calculation of the optical properties showed that the two-dimensional material has a relatively small absorptivity coefficient. The parameters of the mechanical properties characterize the two-dimensional phosphoborane as a relatively soft material, similar to the monolayer of MoS2. Assessment of thermal stability by the method of molecular dynamics indicates sufficient stability of the predicted …

Dataset For: Multiple Local Σ-Aromaticity Of Nonagermanide Clusters, Alexander I. Boldyrev, Nikolay Tkachenko

Browse all Datasets

Nonagermanide clusters are widely used in inorganic synthesis and are actively studied by experimentalists and theoreticians. However, chemical bonding of such versatile species is still not completely understood. In our work we deciphered a bonding pattern for various experimentally obtained nonagermanide species. We localized the electron density via the AdNDP algorithm for the model structures ([Ge9]4−, [Ge9{P(NH2)2}3]−, Cu[Ge9{P(NH2)2}3] and Cu(NHC)[Ge9{P(NH2)2}3]) and obtained a simple and chemically intuitive bonding pattern which can explain the variety of active sites and the existence of both D3h and C4v geometries for such clusters. Moreover, the [Ge9]4− core is found to be a unique example …

Data From: Dibridged, Monobridged, Vinylidene-Like, And Linear Structures For The Alkaline Earth Dihydrides Be2h2, Mg2h2, Ca2h2, Sr2h2, And Ba2h2. Proposals For Observations, Alexander I. Boldyrev, Nikolay Tkachenko

Browse all Datasets

This research reports a search for peculiar monobridged structures of the E2H2 molecules (E = Be, Mg, Ca, Sr, Ba). For Be2H2 and Mg2H2, the monobridged geometry is not an equilibrium but rather a transition state between the vinylidene-like structure and the global minimum HE–EH linear geometry. However, for Ca2H2, Sr2H2, and Ba2H2, this situation changes significantly; the linear structure is no longer the global minimum but lies higher in energy than two other equilibria, the dibridged and monobridged structures. The planar dibridged structures of both Sr2H2 and Ba2H2 should be observable via IR spectroscopy. Although the remarkable monobridged structures …

Data For: Record Low Ionization Potentials Of Alkali Metal Complexes With Crown Ethers And Cryptands, Alexander I. Boldyrev, Nikolay Tkachenko

Browse all Datasets

Electronic properties of series of alkali metals complexes with crown ethers and cryptands were studied via DFT hybrid functionals. For [M([2.2.2]crypt)] (M=Li, Na, K) extremely low (1.70–1.52 eV) adiabatic ionization potentials were found. Such low values of ionization energies are significantly lower than those of alkali metal atoms. Thus, the investigated complexes can be defined as superalkalis. As a result, our investigation opens up new directions in the designing of chemical species with record low ionization potentials and extends the explanation of the ability of the cryptates and alkali crown ether complexes to stabilize multiple charged Zintl ions.

Data From: Computational Prediction Of The Low-Temperature Ferromagnetic Semiconducting 2d Sin Monolayer, Alexander I. Boldyrev, Nikolay Tkachenko

Browse all Datasets

Since the discovery of graphene, 2D materials have captured the minds of scientists because of their attractive and unique electronic properties. In particular, magnetic 2D materials have become a subject of extensive discussions today. Using density functional theory calculations, it is shown that 2D SiN sheet (built out of nonmetallic main group atoms) is a ferromagnetic semiconducting material with a magnetic moment 1 μB per unit cell and an indirect bandgap of 1.55 eV. Calculated phonon spectrum and conducted ab initio molecular dynamics simulation reveal thermal and dynamical stability of the designed material. It is shown that the ferromagnetic state …

Data From: All-Metal Σ-Antiaromaticity In Dimeric Cluster Anion {[Cuge9mes]2}4−, Alexander I. Boldyrev, Nikolay Tkachenko

Browse all Datasets

In this work, we report a dimeric cluster anion, {[CuGe9Mes]2}4−, which was isolated as the [K(2,2,2-crypt)]+ salt and characterized by using single-crystal X-ray diffraction and ESI mass spectroscopy. The title cluster represents the first locally σ-antiaromatic compound in the solid state, as well as the first heteroatomic antiaromatic compound.

Data From: Σ-Aromaticity-Induced Stabilization Of Heterometallic Supertetrahedral Clusters [Zn6ge16]4− And [Cd6ge16]4−, Alexander I. Boldyrev, Nikolay Tkachenko

Browse all Datasets

In this work, the largest heterometallic supertetrahedral clusters, [Zn6Ge16]4− and [Cd6Ge16]4−, were directly self-assembled through highly-charged [Ge4]4− units and transition metal cations, in which 3-center–2-electron σ bonding in Ge2Zn or Ge2Cd triangles plays a vital role in the stabilization of the whole structure. The cluster structures have an open framework with a large central cavity of diameter 4.6 Å for Zn and 5.0 Å for Cd, respectively. Time-dependent HRESI-MS spectra show that the larger clusters grow from smaller components with a single [Ge4]4− and ZnMes2 units. Calculations performed at the DFT level indicate a very large HOMO–LUMO energy gap in …

Data From: Structure And Bonding In [Sb@In8sb12]3− And [Sb@In8sb12]5−, Alexander I. Boldyrev, Nikolay Tkachenko

Browse all Datasets

We report the characterization of the compound [K([2.2.2]crypt)]4[In8Sb13], which proves to contain a 1:1 mixture of [Sb@In8Sb12]3− and [Sb@In8Sb12]5−. The tri-anion displays perfect Th symmetry, the first completely inorganic molecule to do so, and contains eight equivalent In3+ centers in a cube. The gas-phase potential energy surface of the penta-anion has eight equivalent minima where the extra pair of electrons is localized on one In+ center, and these minima are linked by low-lying transition states where the electron pair is delocalized over two adjacent centers. The best fit to the electron density is obtained from a model where the structure …

Digital Appendix Of Masters Thesis "Constraining Deformation Mechanisms Of Damage Zones: A Case Study Of The Shallow San Andreas Fault At Elizabeth Lake, Southern California, James P. Evans, Caroline Studnicky

Browse all Datasets

We performed macroscopic, optical petrographic, scanning electron microscopy, and geochemical analyses on rock core acquired across the San Andreas Fault at Elizabeth Lake, California, in order to understand the distribution and accommodation of fault-related slip and energy within the shallow damage zone of this continental scale strike-slip fault. We characterized the deformation structures, alteration textures, and elemental variabilities to constrain the properties of the uppermost ~2 km fault-related damage zone at this site. We identified evidence for coseismic slip in the form of pulverized rocks, injection veins, clay-clast aggregates, and pseudotachylyte, and aseismic slip through calcite twins, dilatant vein fills, …

Electron Yield Decay Curves For Analysis Of Sample Charging And Neutralization, Matthew Robertson

Utah Space Grant Consortium

Excess charge on a material will affect the electron yield of the material. Electron yield is an attribute of materials which describe how the material behaves when irradiated with electrons. It is the ratio of the number of electrons going into the material over the number of electrons leaving the material. Understanding how a sample charges is important in both how it affects the electron yield and how it can be neutralized.

Comparing P-11b To D-3he Fusion For Direct Drive Fusion Rockets, Christopher Hooper

Utah Space Grant Consortium

Direct Fusion Drive (DFD) is a theoretical configuration that uses a magnetically confined fusing plasma to provide thrust for a rocket. In the words of the original authors, Princeton Satellite Systems (PSS) and Razinet al., it is “...a compact, anuetronic fusion engine [which] will enable more challenging exploration missions in the solar system.” DFD is proposed as a theoretical alternative to chemical and ion propulsion rockets – as seen in Table 1, it has clear advantages over both in exhaust velocity (specific impulse) and mass ratio, and a large advantage over ion propulsion in thrust and thrust-to-weight ratio. Despite being …

Air Quality Measurements In Ephraim, Ut, Alex Allred

Utah Space Grant Consortium

Standard Air Quality indicators: NO, NOx, SO2, CO, O3 and PM2.5 were measured in Ephraim, Sanpete county, Utah from Dec 16, 2020 -Mar 6, 2021. The Air quailty monitoring station was installed in December 2020 and is currently operating. Ephraim is located in a high mountain valley at 5541 feet elevation. Events of interest were evaluated using back trajectories and wind rose analysis.

Evaluating Gallium As A Catalyst For Silicon Nanodot Synthesis, Rylan Woods

Utah Space Grant Consortium

Silicon nanostructures, such as silicon nanowires and silicon nanodots, exhibit notably different thermoelectric, electric, and optical properties from bulk silicon. These nanostructures are ideal for utilization in a variety of electronic and optical devices ranging from batteries to solar panels. While various synthesis methods and catalysts exist for making silicon nanowires, gallium exhibits unique nanowire shapes compared to other catalyst metals such as gold or silver. This experiment uses gallium as a catalyst to form silicon nanostructures onoriented silicon substrate at temperatures of 0, 850, and 900ºC. Analyzing dosed samples via SEM resulted in several samples showing possible evidence of …

A Study Of Oxidation In Thin-Film Uranium-Niobium Alloys, Logan C. Page

Utah Space Grant Consortium

Uranium, a nuclear fuel material, can oxidize and degrade in reactor conditions. Previous studies have shown oxidation resistance in a uranium-niobium alloy, U-6Nb (six weight percent niobium in uranium). The nature of the oxides that form on sputtered U-6Nb thin films after long exposure to air was previously explored using neutron diffraction at Los Alamos National Laboratory. In the present work, we deposited thin films of uranium-niobium alloys for oxidation studies. We used ellipsometry to quantify the oxide growth over time as a function of niobium content. We found that the oxide thickness increases linearly with the logarithmic of time. …

Comparison Of Rayleigh-Scatter Lidar Temperature Climatologies In The Mesosphere And Lower Thermosphere Between The Traditional Reduction Method And The New Optimal Estimation Method, Jonathan Price

Utah Space Grant Consortium

An optimal estimation method (OEM) was used to obtain all-night temperature profiles from Rayleigh-scatter lidar (RSL) observations obtained by the original and updated lidar systems at Utah State University (USU). These data were used to produce annual climatologies of temperatures above USU. The climatology of temperatures from the original lidar, which operated from late 1993 through 2004, was compared with the climatology produced using the widely used Hauchecorne-Chanin method (HC). This comparison highlights the similarities at lower altitudes and differences, which start between 70 km and 80 km and extend to the top altitudes with the OEM temperatures warmer on …

Seeking The Origin Of Electromagnetic Signatures Of Black Holes, Alexandra B. Chanson

Utah Space Grant Consortium

Relativistic-jet formation in astrophysical black holes lacks a rigorously understood mechanism of energy extraction in the high-energy regime although, in recent years, progress has been made in extending the non-linear equations of Force-Free Electrodynamics (FFE) into the high-spin regime. In particular, M. J. Rodriguez and A. Strominger were able to show, using the Near Horizon Extremal Kerr spacetime, that the near horizon FFE solutions have an additional scaling symmetry which allows the construction of a pseudo-analytical infinite tower of solutions. These families of solutions stand in stark contrast to the relatively few full Kerr solutions found analytically: this tension can …

Phase-Space Dynamics Of Runaway Electrons In Tokamaks, Gavin Held

Physics Capstone Projects

Nuclear fusion converts the rest mass energy of ions like the deuteron and triton into kinetic energy. In theory, this energy can be harvested from a thermonuclear reactor to provide power outputs on the scale of 500 MW. High temperatures are needed for significant fusion to occur, hence the tokamak (a modern fusion confinement device) employs strong magnetic fields to keep the ionized gas (plasma) away from the tokamak wall. However, a problem that occasionally arises in a tokamak is that during a disruption an inductive electric field is created which can accelerate electrons to relativistic speeds (these electrons are …

Standard Non-Uniform Noise Dataset, Andres Imperial, John M. Edwards

Browse all Datasets

Fixed Pattern Noise Non-Uniformity Correction through K-Means Clustering

Fixed pattern noise removal from imagery by software correction is a practical approach compared to a physical hardware correction because it allows for correction post-capture of the imagery. Fixed pattern noise presents a unique challenge for de-noising techniques as the noise does not present itself where large number statistics are effective. Traditional noise removal techniques such as blurring or despeckling produce poor correction results because of a lack of noise identification. Other correction methods developed for fixed pattern noise can often present another problem of misidentification of noise. This problem can result …

Meta-Analysis Reveals Different Competition Effects On Tree Growth Resistance And Resilience To Drought, Daniele Castagneri, Giorgio Vacchiano, Andrew Hacket-Pain, R. Justin Derose, Tamir Klein, Alessandra Bottero

Wildland Resources Faculty Publications

Drought will increasingly threaten forest ecosystems worldwide. Understanding how competition influences tree growth response to drought is essential for forest management aiming at climate change adaptation. However, published results from individual case studies are heterogeneous and sometimes contradictory. We reviewed 166 cases from the peer-reviewed literature to assess the influence of stand-level competition on tree growth response to drought. We monitored five indicators of tree growth response: mean sensitivity (inter-annual tree ring width variability); association between inter-annual growth variability and water availability; resistance; recovery; and resilience to drought. Vote counting did not indicate a consistent effect of competition on mean …

Retail Trading And Stock Volatility: The Case Of Robinhood, Cooper Jones

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

We examine the relation between Robinhood usership and stock market volatility. We show that daily fluctuations in Robinhood usership, which is used to proxy retail trading, significantly influence various measures of volatility. These results might suggest that Robinhood users contribute to noise trading as they are generally individuals trading on name recognition, media coverage, popularity, and familiarity of products, rather than on fundamental values. In our empirical approach, we find that the percentage increase in Robinhood usership Granger causes increases in daily stock volatility.

Optimal Control Of Algae Biofilm Growth In Wastewater Treatment Using Computational Mathematical Models, Gerald Benjamin Jones

Undergraduate Honors Capstone Projects

Microalgal biofilms are comprised of a syntrophic consortium of microalgae and other microorganisms embedded within an extracellular matrix. Despite significant processes in the application of microalgal biofilms in wastewater treatment, mechanistic understanding and optimization of microalgal biomass yield and productivity under environmental constraints is still lacking. This paper identifies theoretical insights on this challenging biological problem by leveraging novel mathematical and computational tools. In particular, through a computational mathematical model to advance the understanding of microalgal biofilm growth kinetics under environmental constraints through a systematic parameter study. Moreover, design of algae biofilm reactors for optimal biomass yield and productivity in …

The Reflection Of Light From Periodic Conducting Interfaces, Christian Lange

Undergraduate Honors Capstone Projects

It is known that carbon-nanotube (CNT) forests, nanopillar arrays, and other high aspect-ratio conducting and semi-conducting nanostructures can have extremely low reflectance in a wide range of wavelengths, and that reflectance begins to rise at long wavelengths. The mechanism for this behavior is poorly understood. It has been shown that the reflectance of CNT forest varies with the morphology of the forest, which indicates that the interface of such a material may play a primary role in its reflectance and absorptance.

Simulations of the reflection of light from arrays of conducting nanorods using commercial finite-difference-time-domain software predict a similar increase …

Environmental Racism In A Growing City: Investigating Demographic Shifts In Salt Lake City's Polluted Neighborhoods, Emma Nathel Jones

Undergraduate Honors Capstone Projects

Studies investigating the spatial distribution of environmental hazards have repeatedly demonstrated the existence of environmental racism -- the disproportionate impact of environmental hazards on communities of color. We aim to contribute to research on environmental racism by asking how relationships between race and hazard exposure change over time. Our study area, Salt Lake City (SLC), UT, USA is one of the largest cities in the intermountain west and is expected to see continued population growth. SLC was 99% white from 1860-1950. 2019 census estimates indicate that SLC is becoming more racially diverse with 35.6% of the population identifying as racial …

Fundamental Aspects Of Black Holes, Jacob Fisher Ciafre

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The literature study here seeks to present the foundations of black hole physics in General Relativity. The report includes a discussion of the Kerr black hole metric, black hole entropy, particle creation, the laws of black hole mechanics, and a bilinear mass formula for the Kerr-Newman black hole solution.

The Effects Of Materials And Profiles Of Gratings On Diffraction Spectra, Brock Halling

Physics Capstone Projects

Diffraction patterns can be made either by transmitting or reflecting light from a grating which is an array of parallel lines (rulings) with a fixed periodicity. Elementary optical treatment of diffraction gratings only describes diffraction angles as a function of periodicity of the grating. However, we have observed that the profile and materials of the grating do affect the diffraction pattern. In this study, I investigated the correlation between the grating profiles obtained by scanning electron microscopy and the materials of the grating (polymer and silicon dioxide) and the spectra as a function of the diffraction angle. An optical spectrometer …

Developing Electron Beam Lithography At Nanoscale Device Laboratory, Din Pašić

Physics Capstone Projects

At the Nanoscale Device Laboratory, we can routinely create patterns with a minimum linewidth of 800 nm using photolithography. However, to create photonic devices, the pattern size must be smaller than the wavelength of visible light (400 to 800 nm). Dedicated electron beam writers can achieve a sub-10 nm linewidth, but this system is beyond our reach. In this project, we plan to use a Nanometer Pattern Generation System connected to a Quanta 650 scanning electron microscope to perform e-beam lithography. After setting up a computer to run the NPGS system, and establishing communications with the SEM, we experimented with …

Comparisons Of Mesospheric Temperatures Between 70 And 110 Km: Usu Lidar, Nasa's Timed Satellite, And The Msis2 Empirical Model, David M. Collins

Physics Capstone Projects

Earth’s atmosphere can be characterized by its temperature structure, dividing the atmosphere into natural discrete regions. The mesosphere (50 to ~100 km) has been the least studied. Rayleigh-scatter lidars (RSL) and rockets can obtain local, high-resolution measurements above one spot, while satellites looking almost horizontally obtain global measurements. These two methods of measuring atmospheric conditions are compared using the USU RSL and the SABER instrument on NASA’s TIMED satellite. These measurements were graphed to show four sets of temperatures from several sources in the atmospheric region 70 km to 110 km above USU. The results show similar temperatures for many …

Taphonomy Of Late Jurassic (Tithonian) Morrison Formation Apatosaurus Sp. Vertebrae Found Associated With Teeth From Allosaurus Sp. And Ceratosaurus Sp., And Body Size Extrapolation From The Associated Theropod Teeth., Greg C. Agyan

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

An Apatosaurus sp. locality from Dinosaur National Monument designated DNM-15 was excavated in 1985, and associated with two Allosaurus teeth and one Ceratosaurus tooth that were near one of the caudal vertebrae. The Ceratosaurus tooth was buried between an overlying rib and that same caudal vertebra. The caudal vertebrae of the DNM-15 Apatosaurus were intact and articulated, but the anterior skeleton was mostly absent, with a row of articulated sacral vertebrae in close association with a femur. Two other Allosaurus teeth were reported near the preserved ilium of the Apatosaurus, but they could not be located in the collections. …

The Biggest Snowball Fight In Earth History: Stratigraphy, Facies Analysis, And Geochronology Of The Pocatello Formation, Matthew W. Ellison

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Snowball Earth Hypothesis details a time in Earth’s history (the Cryogenian period) where the entire planet was encapsulated by kilometer thick ice sheets for two, multi-million-year glaciations. The first, known as the Sturtian, lasted from 717 – 660 million years ago while the second, known as the Marinoan, lasted form approximately 650 – 635 million years ago. Snowball Earth was caused by a few processes that sort of built upon each other: Rodinia began splitting apart ~740 million years ago which allowed for increased rates of silicate weathering. High rates of silicate weathering resulted in CO₂ drawdown which …

Deep Learning And Optimization In Visual Target Tracking, Mohammadreza Javanmardi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Visual tracking is the process of estimating states of a moving object in a dynamic frame sequence. It has been considered as one of the most paramount and challenging topics in computer vision. Although numerous tracking methods have been introduced, developing a robust algorithm that can handle different challenges still remains unsolved. In this dissertation, we introduce four different trackers and evaluate their performance in terms of tracking accuracy on challenging frame sequences. Each of these trackers aims to address the drawbacks of their peers. The first developed method is called a structured multi-task multi-view tracking (SMTMVT) method, which exploits …