Chemistry and Physics
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Item 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 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 Copper(II) Complexes with Tridentate Bis(pyrazolylmethyl)pyridine Ligands: Synthesis, X-ray Crystal Structures and ϵ-Caprolactone Polymerization(Wiley-Blackwell, 2017-10) Rueda‐Espinosa, Juan; Torres, Juan F.; Gauthier, Carmen Valdez; Wojtas, Lukasz; Verma, Gaurav; Macías, Mario A.; Hurtado, JohnAbstract: Reactions of Cu(ClO4)2⋅6H2O with 2,6‐bis(3,5‐dimethylpirazol‐1‐ylmethyl)pyridine (dmpz‐py) (1), 2,6‐bis(4‐iodo‐3,5‐dimethylpirazol‐1‐ylmethyl)pyridine (I‐dmpz‐py) (2) and 2,6‐bis(4‐nitro‐3,5‐dimethylpirazol‐1‐ylmethyl)pyridine (NO2‐dmpz‐py) (3) yield the corresponding metal complexes: [Cu(dmpz‐py)(H2O)(ClO4)]ClO4 (4), [Cu(I‐dmpz‐py)(H2O)](ClO4)2 (5) and [Cu(NO2‐dmpz‐py)(H2O)(ClO4)2] (6). The complexes were isolated in high yields as stable solids at room temperature and characterized by melting point, electrical conductivity, and infrared and ultraviolet/visible spectroscopy. In addition, the crystal structures of the new complexes were determined by single‐crystal X‐ray diffraction and showed square‐base pyramidal (4), distorted square‐planar (5) and octahedral (6) geometries. All three complexes were active in the ring opening polymerization of ϵ‐caprolactone under solvent‐free conditions, producing polycaprolactones of narrow polydispersity and high crystallinity. The results obtained show an important increase in polymerization speed compared with analogous azole‐derived copper (II) complexes. [ABSTRACT FROM AUTHOR]Item A course-based undergraduate research experience in biochemistry that is suitable for students with various levels of preparedness(Wiley-Blackwell, 2019-05) Shelby, Shameka J.Due to resource limitations at predominantly undergraduate institutions, research opportunities for non-senior students can be limited. To provide opportunities for a variety of students to gain exposure to research, a course-based undergraduate research experience (CURE) was designed and conducted. Coupled inquiry was used to allow underclassmen and upperclassmen to participate. Students first utilized a bioinformatics approach to develop hypotheses concerning protein interactions with the receptor Mer tyrosine kinase (MERTK). Students designed experiments to identify specific sites of interactions with SH2-domain proteins utilizing an assortment of basic biochemical techniques. The semester culminated in students testing their hypotheses and producing manuscripts. Underclassmen that participated in the course also benefitted from mentor-mentee relationships developed with upperclassmen due to the collaborative nature of the course. The structure of the course also allows for further studies to be conducted based on novel findings and is highly adaptable to receptor tyrosine kinases found in other tissue types.Item Division of Chemical Education Programfor the Fall 2010 ACS National Meeting in Boston.(American Chemical Society, 2010-08) Smith, Julie; Snyder, Nicole L.; Gauthier, Carmen ValdezThe Division of Chemical Education Program for the Fall 2010 ACS National Meeting in Boston on August 22–26, 2010, is presented. The Division of Chemical Education technical sessions will be held in the Seaport Hotel, 200 Seaport Boulevard. The Undergraduate Research Poster and Sci-Mix will be held in the Boston Convention and Exhibition Center. The program schedule is provided.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 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 Engaging organic students in the message and limitation of models(ACS Publications, 2021) Bromfield-Lee, Deborah C.Chemistry courses are filled with models. Organic chemistry utilizes a wide variety of models from tangible model kits, to mechanisms, to computational analysis and spectral information. Often students are presented with these models without any discussion on their limitations or how various models allow us to derive information. Students can use molecular model kits to visualize stereoisomers and derive R/S, but a demonstration of doing this by the instructor can be very helpful. Aromaticity is displayed in many texts as a set of rules for students to memorize. While there are some models that help explain the rules and other models can display aromaticity, some of both types of these models have limitations. However, some of those models have limitations. Reactivity of carbonyls is also often relegated to a pattern or rules. Reactivity that is not explicitly discussed in lecture or the texts then may not be immediately obvious to students. Computational data, mechanisms, and model kits can help students understand the trends, but it is important for students to know how to use these, what the models indicate, and where they are derived. This chapter discusses how students are engaged in lecture with a few of these models to encourage critical thinking evaluating the models. This chapter includes examples of these classroom activities and reports both instructor and student evaluation of the usefulness and limitations of the models.Item An esterification kinetics experiment that relies on the sense of smell(Division of Chemical Education of the American Chemical Society, 2009-01) Bromfield-Lee, Deborah C.; Oliver-Hoyo, Maria T.This experiment involves an esterification synthesis to study reaction kinetics where students explore these topics utilizing the sense of smell rather than the traditional approach of using spectroscopic methods. Students study the effects of various factors including the concentration of the carboxylic acid and the amounts of the catalyst or alcohols added. The kinetics in relation to the molecular structure is studied by changing the chain lengths and branching of alcohols or the carboxylic acids and inferring the effects on rates of the reaction from the rates of ester detection. Since many esters have naturally occurring aromas that are pleasant and easily recognized, this experiment studies esterification kinetics using the sense of smell to detect the emergence of the ester aroma formed during the reaction. Feedback from students strongly suggests their interest in the experiment as they discovered that their sense of smell could be used as an analytical tool.Item Exceptional stability and high hydrogen uptake in hydrogen-bonded metal-organic cubes possessing ACO and AST zeolite-like topologies(American Chemical Society, 2009) Sava, Dorina F.; Kravtsov, Victor Ch.; Eckert, Juergen; Eubank, Jarrod F.; Nouar, Farid; Eddaoudi, MohamedA novel approach for targeting zeolite-like metal-organic frameworks (ZMOFs) that utilizes metal-organic cubes and are regarded as double four-membered rings (d4Rs) and are composite building units (BUs) in traditional inorganic zeolites are reported. The implimentation of the new method is demonstrated by two ZMOFs with ACO and AST zeolite-like topologies constructed from d4R BUs exclusively held together by hydrogen bonds.Item Functional nanoimprinted plasmonic crystals for chemical sensing and imaging(Springer, 2012) Le, An-Phong; Gray, Stephen K.; Nuzzo, Ralph G.; Rogers, John A.We describe here nanoimprinted plasmonic crystals composed of highly uniform subwavelength metal nanohole and nanopost arrays and their application in surface-enhanced sensing and imaging. Soft nanoimprint lithography is a versatile, cost-effective method to precisely replicate these structures with well-characterized optical properties. These plasmonic crystals support multiple surface plasmon modes controlled by the design rules of the nanostructures, allowing us to optimize the devices for operation in a particular wavelength range. We have demonstrated the ability to spectroscopically measure bulk refractive index changes and mechanical deformation of hydrogels resulting from pH changes, thin film imaging with sensitivities down to submonolayer levels using a common optical microscope, and Raman signal enhancement using a single common device framework. These plasmonic crystals have the potential to overcome many of the technological limitations that have limited the widespread application and integration of surface-enhanced analytical techniques.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 Implementation and student perceptions on Google Docs as an electronic laboratory notebook in organic chemistry(American Chemical Society, 2018-05-30) Bromfield-Lee, Deborah C.Electronic laboratory notebooks are gaining in popularity in industry and academia. Various types of electronic laboratory notebooks exist, and a variety of tools can be used for these forms of notebooks. Some tools are commercial products dedicated to being electronic notebooks, while individual organizations can develop ones for their own needs with tools such a OneNote and Google Docs. Google Docs was used as an electronic notebook in organic chemistry, and student perceptions were evaluated using surveys. These tools are used to reduce students’ time preparing for lab and writing reports. The implementation of the notebooks and the findings of students’ perceptions on the implementation are discussed.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 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 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 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 The prevalence of persistent organic pollutants (POPs) in West Africa – A review(Elsevier, 2022) Adebusuyi, Adewumi T.; Sojinu, Samuel O.; Aleshinloye, Abimbola O.Africa's inadequate monitoring is a major issue in combating persistent organic pollutants (POPs). The level of monitoring of these highly toxic persistent substances which have the ability to bioaccumulate through the food chain, thus causing serious health challenges is still very low in Africa especially in West Africa. Most West African countries are yet to implement the Stockholm Convention plan (2001) for reducing and eliminating the dirty dozen as coined by the UNEP. Just nine out of the sixteen West African countries have been given approval for National Implementation Plan (NIP) updates. All relevant stakeholders in West Africa must ensure that detailed monitoring of POPs in the environment is done regularly, with sufficient data collected, analyzed and well documented. Also, people should be sensitized on the harmful effects of POPs. Laws prohibiting indiscriminate dumping of refuse should be enforced and the ban on over used cars and electronics from developed countries should be implemented.Item A qualitative organic analysis that exploits the senses of smell, touch, and sound(Division of Chemical Education of the American Chemical Society, 2007-12) Bromfield-Lee, Deborah C.; Oliver-Hoyo, Maria T.This laboratory experiment utilizes the characteristic aromas of some functional groups to exploit the sense of smell as a discriminating tool in an organic qualitative analysis scheme. Students differentiate a variety of compounds by their aromas and based on their olfactory classification identify an unknown functional group. Students then perform chemical tests that rely on the senses of touch, smell, and sound to confirm the functional group present. The use of a light probe enables students to qualitatively analyze many visual changes as an auditory response. Students "hear" significant changes in color, solution viscosity, and the presence of a precipitate. Students group compounds by their functional group characteristic smells, decide on necessary confirmatory tests based on their own classification, and utilize effectively the senses of touch, sound, and smell to identify their unknowns. Student feedback strongly stated they enjoyed the experiment particularly discovering the characteristics of each functional group physically and chemically. Based on the write-ups and performance of the students in the laboratory, it is evident that this sensorial laboratory can add richness to traditional organic laboratories.