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Item Unique Fluorescence Turn-On and Turn-Off–On Responses to Acids by a Carbazole-Based Metal–Organic Framework and Theoretical Studies(Journal of the American Chemical Society, 2022-09-21) Qiao, Junyi; Liu, Xinyao; Zhang, Lirong; Eubank, Jarrod F.; Liu, Xin; Liu, YunlingItem A Misconception Regarding the Einstein Equivalence Principle and a Possible Cure Using the Twin Paradox(Physics Teacher, 2023-02) Pepino, Ron A.; Mabile, Risley W.It has long been suspected by general relativists that physicists who do not specialize in general relativity (GR) believe that special relativity (SR) is incapable of modeling dynamics within accelerated reference frames. Consequently, many physicists may conclude that certain phenomena, such as time dilation due to acceleration, can only be described with GR. The fact of the matter is, as long as spacetime is flat, SR is fully capable of describing the dynamics of accelerated reference frames. In the classic textbook Gravitation, the authors state that "special relativity was developed precisely to predict the physics of accelerated objects." To quote Sean Carroll in his textbook Spacetime and Geometry, "The notion of acceleration in special relativity has a bad reputation, for no good reason." Finally, in a quote that drives the main point of this article home, the late general relativist Alfred Schild once said, "A good many believe that [the twin] paradox can only be resolved by the general theory of relativity. They find great comfort in this because they don't know any general relativity." [ABSTRACT FROM AUTHOR] Copyright of Physics Teacher is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)Item Enantioenrichment of racemic BINOL by way of excited state proton transfer(Royal Society of Chemistry, 2019) Ayad, Suliman; Posey, Victoria; Das, Anjan; Montgomery, Jason M.; Hanson, KennethHere we report a method for enantioenriching BINOL using a chiral auxiliary and an excited state proton transfer (ESPT) event. Regardless of the starting enantiomeric excess (ee), after irradiation the solution reaches a photostationary state whose ee is dependent solely on the identity of the chiral auxiliary group. The enantio-enriched BINOL is easily recovered by cleaving the auxiliary group in mild conditions.Item Mosaic-like Silver Nanobowl Plasmonic Crystals as Highly Active Surface-Enhanced Raman Scattering Substrates(The Journal of Physical Chemistry, 2015) Baca, Alfred J.; Baca, Joshua; Montgomery, Jason M.; Cambrea, Lee R.; Funcheon, Peter; Johnson, Linda; Moran, Mark; Connor, DanWe present a simple approach to creating a type of surface-enhanced Raman scattering (SERS) substrate composed of a mosaic-like structured Ag metal surface on nanobowl plasmonic crystals (NBPCs) formed by combining soft nanoimprinting and substrate (in situ) heating during metal deposition. This new type of sensor exploits the electromagnetic enhancement of localized surface plasmon resonances (LSPR) produced by a template nanostructured metal surface and surface plasmons (SP) in-between the gaps of the mosaic surface to create a highly SERS-active substrate. Our approach is simple, in that it implements low processing temperatures (200 °C) and does not require any postdeposition annealing or exposure to high temperature environments, enabling the use of mechanically flexible substrates. These SERS substrates exhibit higher SERS intensities in comparison to those obtained with the corresponding square array of smooth (room temperature metal deposition) nanobowl structures with similar spatial layouts. As an example toward an application, we demonstrate polychlorinated biphenyl (PCB-77) SERS detection using Ag mosaic NBPC substrates. Three-dimensional finite-difference time-domain (3D FDTD) simulations qualitatively capture the key features of these systems and suggest a route to the fabrication of optimized, highly efficient SERS substrates in silico.Item Optimization of nanopost plasmonic crystals for surface enhanced Raman scattering(The Journal of Physical Chemistry, 2011) Baca, Alfred J.; Montgomery, Jason M.; Cambrea, Lee R.; Moran, Mark; Johnson, Linda; Yacoub, Jeanine; Truong, Tu T.We present experimental and theoretical studies of a type of Surface Enhanced Raman Scattering (SERS) substrate composed of a metal coated square array of nanopost structures formed via soft nanoimprinting. These SERS substrates exhibit higher SERS intensities in comparison to those obtained with the corresponding square array of nanowell structures with similar spatial layouts and demonstrate multiple analyte detection using SERS. Three-dimensional finite-difference time-domain (3D FDTD) simulations qualitatively capture the key features of these systems and suggest a route to the fabrication of optimized, highly efficient SERS substrates in silico. Collectively, the ease of fabrication, high sensitivities, and predictable responses suggest an attractive route to SERS substrates for portable chemical warfare agent detection, environmental monitors, and other applications.Item Effect of pendant isophthalic acid moieties on the adsorption properties of light hydrocarbons in HKUST-1-like tbo -MOFs: Application to methane purification and storage(Royal Society of Chemistry, 2014) Belmabkhout , Youssef; Mouttaki, Hasnaa; Eubank, Jarrod F.; Guillerm, Vincent; Eddaoudi, MohamedEquilibrium adsorption of methane (CH4), C2+ gases (ethane (C2H6), ethylene (C2H4), propane (C3H8), and propylene (C3H6)), and carbon dioxide (CO2) was measured on a series of tbo-MOFs (topological analogues of the prototypical MOF, HKUST-1, correspondingly dubbed tbo-MOF-1), which were developed via the supermolecular building layer (SBL) pillaring strategy. Specifically, tbo-MOF-2 and its isoreticular, functionalized analogue, tbo-MOF-2-{CH2O[Ph(CO2H)2]}2 (or tbo-MOF-3), which is characterized by pendant isophthalic acid moieties freely pointing into the cavities, were evaluated on the basis of potential use in methane storage and C2+/CH4 separation. The parent, tbo-MOF-2, showed high gravimetric and volumetric CH4 uptake, close to the U.S. Department of Energy (DOE) target for methane storage at 35 bar and room temperature. Though the presence of the pendant isophthalic acid moiety in the analogous compound, tbo-MOF-3, led to a decrease in total CH4 uptake, due mainly to the reduced size of the cavities, interestingly, it increased the affinity of the SBL-based tbo-MOF platform for propane, propene, ethane, and ethylene at low pressures compared with CH4, due additionally to the enhanced interactions of the highly polarizable light hydrocarbons with the isophthalic acid moiety. Using Ideal Adsorption Solution Theory (IAST), the predicted mixture adsorption equilibria for the C3H8/CH4, C3H6/CH4, C2H6/CH4, C2H4/CH4, and C3H8/CO2 systems showed high adsorption selectivity for C2+ over methane for tbo-MOF-3 compared with tbo-MOF-2. The high working storage capacity of tbo-MOF-2 and the high affinity of tbo-MOF-3 for C2+ over CH4 and CO2 make tbo-MOF an ideal platform for studies in gas storage and separation.Item The design and optimization of plasmonic crystals for surface enhanced Raman spectroscopy using the finite difference time domain method(MDPI AG, 2018) Bigness, Alec; Montgomery, Jason M.We present computational studies of quasi three-dimensional nanowell (NW) and nanopost (NP) plasmonic crystals for applications in surface enhanced Raman spectroscopy (SERS). The NW and NP plasmonic crystals are metal coated arrays of cylindrical voids or posts, respectively, in a dielectric substrate characterized by a well/post diameter (D), relief depth (R D), periodicity (P), and metal thickness (M T). Each plasmonic crystal is modeled using the three-dimensional finite-difference time-domain (FDTD) method with periodic boundary conditions in the x- and y-directions applied to a computational unit cell to simulate the effect of a periodic array. Relative SERS responses are calculated from time-averaged electric field intensity enhancements at λ exc and λ scat or at λ mid via G SERS 4 = g 2 ( λ exc ) × g 2 ( λ scat ) or G mid 4 = g 4 ( λ mid ) , respectively, where g 2 = | E | 2 / | E 0 | 2 . Comparisons of G SERS 4 and G mid 4 are made to previously reported experimental SERS measurements for NW and NP geometries. Optimized NW and NP configurations based on variations of D, P, R D, and M T using G SERS 4 are presented, with 6× and 2× predicted increases in SERS, respectively. A novel plasmonic crystal based on square NP geometries are considered with an additional 3× increase over the optimized cylindrical NP geometry. NW geometries with imbedded spherical gold nanoparticles are considered, with 10× to 10 3 × increases in SERS responses over the NW geometry alone. The results promote the use of FDTD as a viable in silico route to the design and optimization of SERS active devices.Item The Role of the Vascular Endothelial Growth Factor (VEGF) Signaling in Biomineralization of the Oyster Crassostrea gigas Authors: Anna V. Ivanina(Frontiers Media S.A, 2018) Ivanina, Anna V.; Borah, Ballav; Rimkevicius, Tadas; Macrander, Jason; Piontkivska, Helen; Sokolova, Inna M.; Beniash, EliaVascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor (VEGFR) play a role in early development, organogenesis, and regeneration, as well as biomineralization of invertebrates. The involvement of VEGF and VEGFR in biomineralization was demonstrated in sea urchin larvae but its role in the biomineralization of other invertebrate groups such as mollusks is not known. We assessed the potential role of VEGF signaling on biomineralization of a model marine bivalve, the Pacific oyster Crassostrea gigas, by analyzing the effects of a VEGFR inhibitor (50 nM axitinib) on shell growth, shell hardness, and expression profiles of biomineralization-related genes. Bioinformatics analysis identified a wide range of biomineralization-related genes potentially activated by VEGF including carbonic anhydrases (CAs), sodium/proton and sodium/calcium exchangers, calmodulins, and genes involved in chitin metabolism. Exposure to a VEGFR inhibitor axitinib led to upregulation of CAs (CA7 and CA12), sodium/proton exchanger 10, sodium/calcium exchanger 1 and 3, as well as calmodulin mRNA in hemocytes (HCs). In the mantle tissue, axitinib exposure led to a compensatory upregulation of VEGFR mRNA but did not affect the expression of other studied biomineralization genes. Expression of VEGF, VEGFR mRNA, or that of the downstream biomineralization-related genes in a non-biomineralizing tissue (the gill) was not affected by axitinib. The shell mass was higher in the axitinib treatment group. Inhibition of VEGFR led to significant increase in shell microhardness, and to a small but statistically significant decrease in crystallinity. Our results therefore indicate that, although VEGF signaling might not play a crucial role in shell biomineralization of C. gigas as it does in mammals and echinoderms, it is involved in regulation of shell formation in bivalves and that effects of VEGF on biomineralization are likely mediated by HCs.Item Zero-periodic metal–organic material, organic polymer composites: tuning properties of methacrylate polymers via dispersion of dodecyloxy-decorated Cu-BDC nanoballs(Royal Society of Chemistry, 2015-02-02) Kim, Mu-Seong; Perry IV, John; Julien, Tamalia C. M.; Marangon, Elisa; Manouat, Cedric; Eubank, Jarrod F.; Harmon, Julie P.A self-assembled metal–organic polyhedron (i.e., MOP or nanoball) with –OC12 external/surface functionality has been incorporated into two polymeric systems: poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(methyl methacrylate) (PMMA). The nanoball, having the chemical formula [(DMSO) (MeOH)Cu2(5-(dodecyloxy)-1,3-benzenedicarboxylate)2]12, possesses 24 saturated 12-carbon chains on the surface. This work characterizes the interactions between OC12-decorated nanoballs and the polymers, revealing interesting effects from the polymer perspective. The resultant nanocomposites were characterized by differential scanning calorimetry (DSC) and microindentation. The dielectric permittivity (ε′) and loss factor (ε′′) were measured via dielectric analysis (DEA) in the frequency range 1 Hz to 100 kHz. The electric modulus formalism was used to reveal α, β, γ and conductivity relaxations. The nanoball interactions with the different polymer matrices allows for tuning of mechanical and electrical properties, by varying polymer structure and/or nanoball loadings, which could be of interest in applications related to electrochemistry, implantable polymeric sensors, drug delivery, energy storage, and beyond.Item Poly(methyl methacrylate) composites of copper-4,4′-trimethylenedipyridine(Royal Society of Chemistry, 2012) Liu, Shisi; Ananthoji, Ramakanth; Han, Sungyub; Knudsen, Bernard; Li, Xiao; Wojtas, Lukasz; Massing, Justin; Gauthier, Carmen Valdez; Harmon, Julie P.We prepared a series of poly(methyl methacrylate) (PMMA) composites with a novel one dimensional coordination polymer copper-4,4′-trimethylenedipyridine (CU-TMDP). The CU-TMDP was sonicated in a methyl methacrylate monomer and polymerized in situ. Thermal, mechanical and optical properties of CU-TMDP–PMMA composites were probed via optical microscopy, Raman spectroscopy, differential scanning calorimetry (DSC), microhardness, and dynamic mechanical analysis (DMA). The CU-TMDP was characterized by X-ray crystallography. The functionality of the CU-TMDP interacted with the polymer matrix such that mechanical properties are tuned by varying CU-TMDP loadings. The data point to the fact that interactions are primarily due to London dispersion forces or dipole–dipole interactions. This initial study forms the basis for future applications requiring tailored mechanical properties.Item Highly effective and fast removal of anionic carcinogenic dyes: Via an In3-cluster-based cationic metal-organic framework with nitrogen-rich ligand(Royal Society of Chemistry, 2019) Liu, Xinyao; Liu, Bing; Eubank, Jarrod F.; Liu, YunlingIn this work, highly effective and rapid removal of anionic carcinogenic organic dye molecules is achieved through the use of a novel cationic metal–organic framework (MOF). The MOF is constructed using a nitrogen-rich triangular organic ligand, 4,4′,4′′-s-triazine-1,3,5-triyltri-p-aminobenzoate (H3TATAB), and trinuclear 6-connected In3-cluster secondary building units (SBUs), [In3O(TATAB)2(H2O)3](NO3)·(DMA)15 (In-TATAB), which gives a structure exhibiting a new topology. As the formula indicates, In-TATAB is inherently cationic due to the [In3O(COO−)6]+ units, which thus favors interaction with anionic guests. Several organic dye molecules of varying charge and size, such as acid chrome blue K, acid red 26, congo red, direct black 38 and, orange II, were used to test the sequestration potential of the MOF material. In addition to electrostatic attraction, it is shown that hydrogen-bonding originating from the highly functional bridging ligand and terminal H2O ligands enhance the interactions between the framework and guest dye molecules, suggesting its potential use for the removal of anionic organic pollutants.Item Prediction of the Existence of LiCH: A Carbene-like Organometallic Molecule(ACS Publications, 2020) Montgomery, Jason M.; Alexander, Ezra; Mazziotti, David A.Carbenes comprise a well-known class of organometallic compounds consisting of a neutral, divalent carbon and two unshared electrons. Carbenes can have singlet or triplet ground states, each giving rise to a distinct reactivity. Methylene, CH$_2$, the parent hydride, is well-known to be bent in its triplet ground state. Here we predict the existence of LiCH, a carbene-like organometallic molecule. Computationally, we treat the electronic structure with parametric and variational two-electron reduced density matrix (2-RDM) methods, which are capable of capturing multireference correlation typically associated with the singlet state of a diradical. Similar to methylene, LiCH is a triplet ground state with a predicted 15.8 kcal/mol singlet-triplet gap. However, unlike methylene, LiCH is linear in both the triplet state and the lowest excited singlet state. Furthermore, the singlet state is found to exhibit strong electron correlation as a diradical. In comparison to dissociation channels Li + CH and Li$^+$ + CH$^-$, the LiCH was found to be stable by approximately 77 kcal/mol.Item Strong Electron Correlation in Nitrogenase Cofactor, FeMoco(ACS Publications, 2018) Montgomery, Jason M.; Mazziotti, David A.FeMoco, MoFe$_7$S$_9$C, has been shown to be the active catalytic site for the reduction of nitrogen to ammonia in the nitrogenase protein. An understanding of its electronic structure including strong electron correlation is key to designing mimic catalysts capable of ambient nitrogen fixation. Active spaces ranging from [54, 54] to [65, 57] have been predicted for a quantitative description of FeMoco's electronic structure. However, a wavefunction approach for a singlet state using a [54,54] active space would require 10$^{29}$ variables. In this work, we systematically explore the active-space size necessary to qualitatively capture strong correlation in FeMoco and two related moieties, MoFe$_3$S$_7$ and Fe$_4$S$_7$. Using CASSCF and 2-RDM methods, we consider active-space sizes up to [14,14] and [30,30], respectively, with STO-3G, 3-21G, and DZP basis sets and use fractional natural-orbital occupation numbers to assess the level of multireference electron correlation, an examination of which reveals a competition between single-reference and multi-reference solutions to the electronic Schr\"{o}dinger equation for smaller active spaces and a consistent multi-reference solution for larger active spaces.Item Maple's Quantum Chemistry Package in the Chemistry Classroom(ACS Publications, 2020) Montgomery, Jason M.; Mazziotti, David A.An introduction to the Quantum Chemistry Package (QCP), implemented in the computer algebra system Maple, is presented. The QCP combines sophisticated electronic structure methods and Maple's easy-to-use graphical interface to enable computation and visualization of the electronic energies and properties of molecules. Here we describe how the QCP can be used in the chemistry classroom using lessons provided within the package. In particular, the calculation and visualization of molecular orbitals of hydrogen fluoride, the application of the particle in a box to conjugated dyes, the use of geometry optimization and normal mode analysis for hypochlorous acid, and the thermodynamics of combustion of methane.Item Advances in atomtronics(MDPI, 2021) Pepino, Ronald A.Atomtronics is a relatively new subfield of atomic physics that aims to realize the device behavior of electronic components in ultracold atom-optical systems. The fact that these systems are coherent makes them particularly interesting since, in addition to current, one can impart quantum states onto the current carriers themselves or perhaps perform quantum computational operations on them. After reviewing the fundamental ideas of this subfield, we report on the theoretical and experimental progress made towards developing externally-driven and closed loop devices. The functionality and potential applications for these atom analogs to electronic and spintronic systems is also discussed. Comment: Accepted for publication in EntropyItem Thermomechanical characterization of thermoplastic polyimides to improve the chain collaboration via ureidopyrimidone endcaps(Society of Plastics Engineers, Inc., 2019-11) Nicholls, Alejandro Rivera; Perez, Yesenia; Pellisier, Matthew; Rodde, Arnaud; Lanusse, Pierre; Stock, John Allan; Kull, Ken; Eubank, Jarrod F. ; Harmon, Julie P.In this report, we explored the effect of incorporating ureidopyrimidone (UPy) linkers in a series of polyimides (Pis) previously studied in our laboratory. The polymers consist of an aromatic diamine monomer with a methylene linker, 4,4'-methylenebis (2,6-dimethylaniline), used to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to decrease rigidity. The polymers were designed to exhibit thermal properties in between those of conventional aromatic PIs and polymers with wholly aliphatic ether diamine links, with an aim to improve the mechanical characteristics. Through dynamic mechanical analysis and differential scanning calorimetry, it is shown that the UPy linkers with their four-hydrogen bond sites are introduced to connect the chains in series. The connection strengthens the chain interactions and increases the range of the thermal and mechanical properties of the PI. Furthermore, the connecting regions are an important component to preserve the thermal stability of PIs while maintaining the processability. The polymers were characterized by FTIR, nuclear magnetic resonance, GPC, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, microhardness, and tensile testing.Item Transport enhancement of irregular optical lattices with polychromatic amplitude modulation(IOP Publishing, 2016) Pepino, Ronald A.; Teh, W. P.; Magness, L. J.We demonstrate that the transport characteristics of deep optical lattices with one or multiple off-resonant external energy offsets can be greatly enhanced by modulating the lattice depth in an exotic way. We derive effective stationary models for our proposed modulation schemes in the strongly interacting limit, where only one particle can occupy any given site. Afterwards we discuss the modifications necessary to recover transport when more than one particle may occupy the lattice sites. For the specific five-site lattices discussed, we numerically predict transport gains for ranging from to . [ABSTRACT FROM AUTHOR] Copyright of New Journal of Physics is the property of IOP Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)Item Spattering and crackle of hot cooking oil with water: A classroom demonstration and discussion(American Chemical Society Division of Chemical Education, 2009) Pinto, Gabriel; Gauthier, Carmen ValdezThe well-known effect where hot vegetable oil will pop and spatter when it comes in contact with water is used in an activity to teach chemistry concepts that include boiling point, miscibility, and density of liquids. The importance of heat points for oils and the intermolecular interactions of vegetable oils are also taught.Item Thermomechanical characterization of thermoplastic polyimide to improve the chain interaction via crystalline domains(Society of Plastics Engineers, Inc., 2019-09) Nicholls, Alejandro Rivera; Craft, Garrett; Perez, Yesenia; Pellisier, Matthew; Stock, John Allan; Testemale, Maxime; Kull, Ken; Eubank, Jarrod F.; Harmon, Julie P.In a previous study on polyimides, we incorporated an aromatic diamine monomer with a methylene linker, 4,4'-methylenebis (2,6-dimethylaniline), to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to decrease rigidity. In this report, we explore the behavior of crystalline regions provided by the organized packing of polyethylene oxide into the formerly characterized polymers. The polymers were designed to exhibit thermal properties in between those of conventional aromatic polyimides and polymers with wholly aliphatic ether diamine links, with a target to improve the mechanical characteristics. Through dynamic mechanical analysis and differential scanning calorimetry, it is shown that the incorporation of polyethylene oxide diamine and the removal of methyl pending groups serve to improve the organized packing of the chains. All of this allows for a broader range in tenability of thermal and mechanical properties of the polyimide. Furthermore, the crystalline regions are an important component to maintain the temperature stability of polyimide while maintaining the processability. The polymers are characterized by Fourier-transform infrared spectroscopy, thermomechanical and calorimetric analysis, microhardness measurements, tensile testing, and wide-angle X-ray scattering. INTRODUCTION Highly ordered aromatic backbones allow polyimides (PIs) to have superb properties demonstrated by elevated thermal stability, solvent resistance, low coefficients of thermal expansion, low dielectric constants, high glass transition [...]Item Thermomechanical characterization of thermoplastic polyimide–polyurea to improve the chain interaction via internal hydrogen bonds(Society of Plastics Engineers, Inc, 2019-09) Nicholls, Alejandro Rivera; Pellisier, Matthew; Perez, Yesenia; Stock, John Allan; Kull, Ken; Julien, Tamalia; Eubank, Jarrod F.; Harmon, Julie P.Recently, we have studied polyimides (PIs) synthesized by incorporating an aromatic diamine monomer with a methylene linker, 4,4'-methylenebis(2,6-dimethylaniline), to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to reduce rigidity. In this report, we incorporate a urea linkage into these materials in order to observe the effect of additional hydrogen bonding. The polymers are designed to exhibit thermal properties in between those of conventional aromatic PIs and polymers with wholly aliphatic ether diamine links. Herein, we demonstrate that the addition of 1,6 hexamethylene diisocyanate and the increase of hydrogen bonds at the urea linkage can be used to improve the thermal and mechanical properties of the PI. Furthermore, the imide ring is an important component to maintain the thermal stability characteristics in poly-imidepolyurea hybrids. The polymers were characterized by FTIR, thermomechanical and calorimetric analysis, micro-hardness, and tensile testing. INTRODUCTION A series of thermoplastic polyimide-polyureas (PIUs) with tractable properties and structural improvements are synthesized and characterized in this work. Polyimides (PIs) with highly ordered aromatic backbones demonstrate high thermal [...]