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Articles 1 - 19 of 19
Full-Text Articles in Physical Sciences and Mathematics
3d-Printable And Open-Source Modular Smartphone Visible Spectrophotometer, Brandon Winters, Nick Banfield, Cassandra Dixon, Anna Swensen, Dakota Holman, Braxton Fillbrown
3d-Printable And Open-Source Modular Smartphone Visible Spectrophotometer, Brandon Winters, Nick Banfield, Cassandra Dixon, Anna Swensen, Dakota Holman, Braxton Fillbrown
Chemistry Faculty Publications
The past four decades have brought significant and increasingly rapid changes to the world of instrument design, fabrication, and availability due to the emergence of 3D printing, open-source code and equipment, and low-cost electronics. These, along with other technological advances represent a nexus in time ripe for the wide-spread production and availability of low-cost sophisticated scientific equipment. To that end, the design of a 3D printable and open-source, modular spectrometer is described. This specific instrument is distinctly different from others that have been reported in recent years in that it was designed outside of the “black box” paradigm of …
Computational Analysis Beyond The Monomer Frontier Orbitals For Photovoltaic Donor-Polymer Candidates, Mitchell E. Lahm, Megan M. Niblock, John M. Migliore, Kendra M. Mckenzie, Hans P. Lüthi, Rollin A. King
Computational Analysis Beyond The Monomer Frontier Orbitals For Photovoltaic Donor-Polymer Candidates, Mitchell E. Lahm, Megan M. Niblock, John M. Migliore, Kendra M. Mckenzie, Hans P. Lüthi, Rollin A. King
Chemistry Faculty Publications
Scharber et al. proposed an efficiency model for organic photovoltaic cells based on the orbital energies of the monomers of the donor- and acceptor- polymers [Advanced Materials 18 (2006) 789–794]. We report theoretical extensions of this approach. First, the frontier-orbital energies and electronic spectra of n-length oligomers (n = 1 − 5) of 3-butylthiophene have been determined. The results show reasonable convergence with respect to system size at the point of a trimer with alkyl end caps. The HOMO-LUMO gap well matches computed excitation energies. Second, the structures and electronic spectra of dimers formed by three different monomers, with various …
Decreasing Phosphatidylcholine On The Surface Of The Lipid Droplet Correlates With Altered Protein Binding And Steatosis, Laura Listenberger, Elizabeth Townsend, Cassandra Rickertsen, Anastasia Hains, Elizabeth Brown, Emily G. Inwards, Angela K. Stoeckman
Decreasing Phosphatidylcholine On The Surface Of The Lipid Droplet Correlates With Altered Protein Binding And Steatosis, Laura Listenberger, Elizabeth Townsend, Cassandra Rickertsen, Anastasia Hains, Elizabeth Brown, Emily G. Inwards, Angela K. Stoeckman
Chemistry Faculty Publications
Alcoholic fatty liver disease (AFLD) is characterized by an abnormal accumulation of lipid droplets (LDs) in the liver. Here, we explore the composition of hepatic LDs in a rat model of AFLD. Five to seven weeks of alcohol consumption led to significant increases in hepatic triglyceride mass, along with increases in LD number and size. Additionally, hepatic LDs from rats with early alcoholic liver injury show a decreased ratio of surface phosphatidylcholine (PC) to phosphatidylethanolamine (PE). This occurred in parallel with an increase in the LD association of perilipin 2, a prominent LD protein. To determine if changes to the …
Striking The Right Balance Of Intermolecular Coupling For High-Efficiency Singlet Fission, Ryan D. Pensack, Andrew J. Tilley, Christopher Grieco, Geoffrey E. Purdum, Evgeny E. Ostroumov, Devin B. Granger, Daniel G. Oblinsky, Jacob C. Dean, Grayson S. Doucette, John B. Asbury, Yueh-Lin Loo, Dwight S. Seferos, John E. Anthony, Gregory D. Scholes
Striking The Right Balance Of Intermolecular Coupling For High-Efficiency Singlet Fission, Ryan D. Pensack, Andrew J. Tilley, Christopher Grieco, Geoffrey E. Purdum, Evgeny E. Ostroumov, Devin B. Granger, Daniel G. Oblinsky, Jacob C. Dean, Grayson S. Doucette, John B. Asbury, Yueh-Lin Loo, Dwight S. Seferos, John E. Anthony, Gregory D. Scholes
Chemistry Faculty Publications
Singlet fission is a process that splits collective excitations, or excitons, into two with unity efficiency. This exciton splitting process, unique to molecular photophysics, has the potential to considerably improve the efficiency of optoelectronic devices through more efficient light harvesting. While the first step of singlet fission has been characterized in great detail, subsequent steps critical to achieving overall highly-efficient singlet-to-triplet conversion are only just beginning to become well understood. One of the most elementary suggestions, which has yet to be tested, is that an appropriately balanced coupling is necessary to ensure overall highly efficient singlet fission; that is, the …
3d Printable Optomechanical Cage System With Enclosure, Brandon Winters, David Shepler
3d Printable Optomechanical Cage System With Enclosure, Brandon Winters, David Shepler
Chemistry Faculty Publications
The advent of the computer-age in the mid to late 20th century brought the development of sophisticated scientific equipment for myriad chemical analyses. The field of spectroscopy alone has seen significant advances in data collection, processing, and analysis due principally to the incorporation of microprocessors. While it is clear computers have revolutionized the field of instrumental chemical analysis their impact is pervasive through every segment of our lives. From word processing, data management, and Computer Aided Design in our work environments to social media, crowd funding, and digital news at home, technology is everywhere. This work seeks to incorporate the …
A Loose Domain Swapping Organization Confers A Remarkable Stability To The Dimeric Structure Of The Arginine Binding Protein From Thermotoga Maritima, Alessia Ruggiero, Jonathan D. Dattelbaum, Maria Staiano, Rita Berisio, Sabato D'Auria, Luigi Vitagliano
A Loose Domain Swapping Organization Confers A Remarkable Stability To The Dimeric Structure Of The Arginine Binding Protein From Thermotoga Maritima, Alessia Ruggiero, Jonathan D. Dattelbaum, Maria Staiano, Rita Berisio, Sabato D'Auria, Luigi Vitagliano
Chemistry Faculty Publications
The arginine binding protein from Thermatoga maritima (TmArgBP), a substrate binding protein (SBP) involved in the ABC system of solute transport, presents a number of remarkable properties. These include an extraordinary stability to temperature and chemical denaturants and the tendency to form multimeric structures, an uncommon feature among SBPs involved in solute transport. Here we report a biophysical and structural characterization of the TmArgBP dimer. Our data indicate that the dimer of the protein is endowed with a remarkable stability since its full dissociation requires high temperature as well as SDS and urea at high concentrations. In order to elucidate …
Stop Rotating! One Substitution Halts The B19- Motor, Francisco Cervantes-Navarro, Gerarso Martínez-Guajardo, Edison Osorio, Diego Moreno, William Tiznado, Rafael Islas, Kelling J. Donald, Gabriel Merino
Stop Rotating! One Substitution Halts The B19- Motor, Francisco Cervantes-Navarro, Gerarso Martínez-Guajardo, Edison Osorio, Diego Moreno, William Tiznado, Rafael Islas, Kelling J. Donald, Gabriel Merino
Chemistry Faculty Publications
The B19- anion and other boron species have been dubbed ‘Wankel motors’ for the almost barrierless rotation of inner and outer concentric rings relative to each other in these compounds. A single substitution in B19- is shown to shut down the well-established fluxionality in the anion. A carbon atom substituted in the structure to give a neutral CB18 species is shown computationally to enforce bond localization.
Science Classics, Mark Masthay
Science Classics, Mark Masthay
Chemistry Faculty Publications
An essay on the impact of the works in the Imprints and Impressions: Milestones in Human Progress, an exhibition of rare books from the collection of Stuart Rose. Exhibition was held Sept. 29-Nov. 9, 2014, at the University of Dayton.
Theoretical Design Of Stable Small Aluminium-Magnesium Binary Clusters, Edison Osorio, Alejandro Vasquez, Elizabeth Florez, Fanor Mondragon, Kelling J. Donald, William Tiznado
Theoretical Design Of Stable Small Aluminium-Magnesium Binary Clusters, Edison Osorio, Alejandro Vasquez, Elizabeth Florez, Fanor Mondragon, Kelling J. Donald, William Tiznado
Chemistry Faculty Publications
We explore in detail the potential energy surfaces of the AlxMgy (x, y = 1–4) systems as case studies to test the utility and limitations of simple rules based on electron counts and the phenomenological shell model (PSM) for bimetallic clusters. We find that it is feasible to design stable structures that are members of this set of small Al–Mg binary clusters, using simple electron count rules, including the classical 4n + 2 Hückel model, and the most recently proposed PSM. The thermodynamic stability of the title compounds has been evaluated using several different descriptors, including …
Cbe5e− (E = Al, Ga, In, Tl): Planar Pentacoordinate Carbon In Heptaatomic Clusters, Abril C. Castro, Gerarso Martinez-Guajardo, Thomas Johnson, Jesus M. Ugalde, Yan-Bo Wu, Jose M. Mercero, Thomas Heine, Kelling J. Donald, Gabriel Merino
Cbe5e− (E = Al, Ga, In, Tl): Planar Pentacoordinate Carbon In Heptaatomic Clusters, Abril C. Castro, Gerarso Martinez-Guajardo, Thomas Johnson, Jesus M. Ugalde, Yan-Bo Wu, Jose M. Mercero, Thomas Heine, Kelling J. Donald, Gabriel Merino
Chemistry Faculty Publications
A series of clusters with the general formula CBe5E- (E = Al, Ga, In, Tl) are theoretically shown to have a planar pentacoordinate carbon atom. The structures show a simple and rigid topological framework—a planar EBe4 ring surrounding a C center, with one of the ring Be–Be bonds capped in-plane by a fifth Be atom. The system is stabilized by a network of multicenter σ bonds in which the central C atom is the acceptor, and π systems as well by which the C atom donates charge to the Be and E atoms that encircle it.
Plane And Simple: Planar Tetracoordinate Carbon Centers In Small Moleculesw, Chad Crigger, Bernard K. Wittmaack, Marina Tawfik, Gabriel Merino, Kelling J. Donald
Plane And Simple: Planar Tetracoordinate Carbon Centers In Small Moleculesw, Chad Crigger, Bernard K. Wittmaack, Marina Tawfik, Gabriel Merino, Kelling J. Donald
Chemistry Faculty Publications
A class of neutral 18-electron molecules with planar tetracoordinate carbon (ptC) centers is introduced. We show computationally that when n = 3 the neutral singlet molecule C(BeH)n(BH2)4-n and other isoelectronic (18-valence electron) molecules of main group elements collapse from locally tetrahedral arrangements at the C-center to (near) planar tetracoordinate structures. For C(BeH)3BH2 and C(CH3)(BH2)Li2, for example, the tetrahedral type conformation is not even a minimum on the potential energy surface at the B3PW91, MP2(full), or CCSD levels of theory. The Mg analogue C(MgH)3BH2 …
Her2 Targeted Molecular Mr Imaging Using A De Novo Designed Protein Contrast Agent, Jingjuan Qiao, Shunyi Li, Lixia Wei, Jie Jiang, Robert Long, Hui Mao, Ling Wei, Liya Wang, Hua Yang, Hans E. Grossniklaus, Zhi-Ren Liu, Jenny J. Yang
Her2 Targeted Molecular Mr Imaging Using A De Novo Designed Protein Contrast Agent, Jingjuan Qiao, Shunyi Li, Lixia Wei, Jie Jiang, Robert Long, Hui Mao, Ling Wei, Liya Wang, Hua Yang, Hans E. Grossniklaus, Zhi-Ren Liu, Jenny J. Yang
Chemistry Faculty Publications
The application of magnetic resonance imaging (MRI) to non-invasively assess disease biomarkers has been hampered by the lack of desired contrast agents with high relaxivity, targeting capability, and optimized pharmacokinetics. We have developed a novel MR imaging probe targeting to HER2, a biomarker for various cancer types and a drug target for anti-cancer therapies. This multimodal HER20targeted MR imaging probe integrates a de novo designed protein contrast agent with a high affinity HER2 affibody and a near IR fluorescent dye. Our probe can differentially monitor tumors with different expression levels of HER2 in both human cell lines and xenograft mice …
Shorter Still: Compressing C-C Single Bonds, Gerarso Martinez-Guajardo, Kelling J. Donald, Bernard K. Wittmaack, Miguel Angel Vazquez, Gabriel Merino
Shorter Still: Compressing C-C Single Bonds, Gerarso Martinez-Guajardo, Kelling J. Donald, Bernard K. Wittmaack, Miguel Angel Vazquez, Gabriel Merino
Chemistry Faculty Publications
How short can a C-C single bond get? The bonding in a set of molecules that are related structurally to previously synthesized or theoretically examined systems with short C-C bonds is investigated. According to calculations, a single C-C bond could be compressed to 1.313 A! To the best of our knowledge, this is the shortest single C-C bond reported to date. This shortening is a consequence of a change in the C-C-C bond angle, θ, to minimize strain in the cages and an effort to offset the tension in the surrounding bridges.
Identification And Characterization Of A New Tubulin-Binding, Susan L. Mooberry, Kimberly N. Weiderhold, Sivanesan Dakshanamurthy, Ernest Hamel, Edith J. Banner, Anastasia Kharlamova, Jonathan Hempel, John T. Gupton, Milton L. Brown
Identification And Characterization Of A New Tubulin-Binding, Susan L. Mooberry, Kimberly N. Weiderhold, Sivanesan Dakshanamurthy, Ernest Hamel, Edith J. Banner, Anastasia Kharlamova, Jonathan Hempel, John T. Gupton, Milton L. Brown
Chemistry Faculty Publications
We studied the mechanism of action of 3,5-dibromo-4-(3,4-dimethoxyphenyl)-1H-pyrrole-2-carboxylic acid ethyl ester (JG-03-14) and found that it is a potent microtubule depolymerizer. JG-03-14 caused a dose-dependent loss of cellular microtubules, formation of aberrant mitotic spindles, accumulation of cells in the G2/M phase of the cell cycle, and Bcl-2 phosphorylation. These events culminated in the initiation of apoptosis, as evidenced by the caspase 3-dependent cleavage of poly(ADP-ribose) polymerase (PARP). JG-03-14 has antiproliferative activity against a wide range of cancer cell lines, with an average IC50 value of 62 nM, and it is a poor substrate for transport …
Efficient And General Synthesis Of Novel Β-Polyfluoroalkoxy Vinamidinium Salts, Koichiro Kase, Mitsuyoshi Katayama, Takashi Ishihara, Hiroki Yamanaka, John T. Gupton
Efficient And General Synthesis Of Novel Β-Polyfluoroalkoxy Vinamidinium Salts, Koichiro Kase, Mitsuyoshi Katayama, Takashi Ishihara, Hiroki Yamanaka, John T. Gupton
Chemistry Faculty Publications
Novel β-polyfluoroalkoxy vinamidinium salts 3 and/or 4 were synthesized in good yields by the reaction of N-(2- polyfluoroalkoxy-3 ,3-difluoro-1-propenyI)trimethylammonium iodides (2), prepared from N-(2,3,3-trifluoro-1-propenyl)trimethylammonium iodide (1), with secondary amines in MeCN at 70 °C for 1 h. The salts were also obtainable in comparable yields by the one-pot reaction of 1 with sodium polyfluoroalkoxide followed by treatment with amines.
Applications Of The Semiclassical Spectral Method To Nuclear, Atomic, Molecular, And Polymeric Dynamics, M. L. Koszykowski, George A. Pfeffer, Donald W. Noid
Applications Of The Semiclassical Spectral Method To Nuclear, Atomic, Molecular, And Polymeric Dynamics, M. L. Koszykowski, George A. Pfeffer, Donald W. Noid
Chemistry Faculty Publications
Nonlinear dynamics plays a dominant role in a variety of important problems in chemical physics. Examples are unimolecular reactions,’ infrared multiphoton decomposition of molecules,’ the pumping process of the gamma ray laser,’ dissociation of vibrationally excited state-selected van der Waals’s complexes,’ and many other chemical and atomic processes. The present article discusses recent theoretical studies on the quasi-periodic and chaotic dynamical aspects of vibrational-rotational states of atomic, nuclear, and molecular systems using the semiclassical spectral method (SSM).’ We note that the coordinates, momenta, and so on, are found using classical mechanics in the studies included in this review. Consequently, certain …
Method For Direct Preparation For 1,2,4-Triazole From Hydrazine And Formamide, Harris E. Petree, Joseph R. Pociask, John T. Gupton
Method For Direct Preparation For 1,2,4-Triazole From Hydrazine And Formamide, Harris E. Petree, Joseph R. Pociask, John T. Gupton
Chemistry Faculty Publications
Process for the preparation of 1,2,4-triazole comprises contacting hydrazine or its aqueous solutions with at least about 2.5 moles of formamide at a temperature of 140° to 210° C. and then recovering the resultant 1,2,4- triazole in yields of 92-98% with 94-98% purity. The formamide is maintained in an excess over about the 2.5 molar amount consumed in the reaction with the hydrazine. Recovery steps for isolating the 1,2,4-triazole are disclosed.
A Process For The Production Of 2-Alkyl Or 2-Cycloalkyl-4-Methyl-6-Hydroxypyrimidines, Joseph T. Blackwell Iii, John T. Gupton, Teruko U. Miyazaki, James B. Nabors, Joseph R. Pociask
A Process For The Production Of 2-Alkyl Or 2-Cycloalkyl-4-Methyl-6-Hydroxypyrimidines, Joseph T. Blackwell Iii, John T. Gupton, Teruko U. Miyazaki, James B. Nabors, Joseph R. Pociask
Chemistry Faculty Publications
Production of 2-alkyl- or cycloalkyl-4-methyl-6- hydroxypyrimidines by first neutralizing an alkyl imidate ester hydrochloride with a base in the presence of a water-immiscible solvent for the alkyl imidate ester to be freed thereby; condensing the alkyl imidate ester with diketene to form an oxazinone intermediate, which is then reacted in organic solution with gaseous ammonia and recovering the desired substituted 6-hydroxypyrimidine.
Photochemical Rearrangements Of 6/5 -Fused Cross-Conjugated Cyclohexadiensnes In Protic Solvents, Drury Caine, John T. Gupton, Ko Ming, William J. Powers Iii
Photochemical Rearrangements Of 6/5 -Fused Cross-Conjugated Cyclohexadiensnes In Protic Solvents, Drury Caine, John T. Gupton, Ko Ming, William J. Powers Iii
Chemistry Faculty Publications
Irradiation of the ring A unsubstituted 6/5-fused cross-conjugated cyclohexadienone (1a) and its 2-methyl derivative (1b) in methanolic acetic acid yields, in addition to other products, novel tricyclononane derivatives which have been assigned the structures (3a) and (3b).