Chemistry Commons^™

A Nanoscale Shape-Discovery Framework Supporting Systematic Investigations Of Shape-Dependent Biological Effects And Immunomodulation, Wei Zhang, Hender Lopez, Luca Boselli, Paolo Bigini, André Perez-Potti, Zengchun Xie, Valentina Castagnola, Qi Cai, Camila P. Silveira, Joao M. De Araujo, Laura Talamini, Nicolò Panini, Giuseppe Ristagno, Martina B. Violatto, Stéphanie Devineau, Marco P. Monopoli, Mario Salmona, Valeria A. Giannone, Sandra Lara, Kenneth A. Dawson, Yan Yan

Articles

Since it is now possible to make, in a controlled fashion, an almost unlimited variety of nanostructure shapes, it is of increasing interest to understand the forms of biological control that nanoscale shape allows. However, a priori rational investigation of such a vast universe of shapes appears to present intractable fundamental and practical challenges. This has limited the useful systematic investigation of their biological interactions and the development of innovative nanoscale shape-dependent therapies. Here, we introduce a concept of biologically relevant inductive nanoscale shape discovery and evaluation that is ideally suited to, and will ultimately become, a vehicle for machine …

Splashing Of Large Helium Nanodroplets Upon Surface Collisions, Paul Martini, Simon Albertini, Felix Laimer, Miriam Meyer, Michael Gatchell, Olof E. Echt, Fabio Zappa, Paul Scheier

Faculty Publications

In the present work we observe that helium nanodroplets colliding with surfaces can exhibit splashing in a way that is analogous to classical liquids. We use transmission electron microscopy and mass spectrometry to demonstrate that neutral and ionic dopants embedded in the droplets are efficiently backscattered in such events. High abundances of weakly bound He-tagged ions of both polarities indicate a gentle extraction mechanism of these ions from the droplets upon collision with a solid surface. This backscattering process is observed for dopant particles with masses up to 400 kilodaltons, indicating an unexpected mechanism that effectively lowers deposition rates of …

Adsorption Of Helium On A Charged Propeller Molecule: Hexaphenylbenzene, Siegfried Kollotzek, Florent Calvo, Serge Krasnokutski, Fabio Zappa, Paul Scheier, Olof E. Echt

Faculty Publications

Physisorption on planar or curved graphitic surfaces or aromatic rings has been investigated by various research groups, but in these studies the substrate was usually strictly rigid. Here we report a combined experimental and theoretical study of helium adsorption on cationic hexaphenylbenzene (HPB), a propeller-shaped molecule. The orientation of its propeller blades is known to be sensitive to the environment, with substantial differences between the molecule in the gas phase and in the crystalline solid. Mass spectra of He_nHPB⁺, synthesized in helium nanodroplets, indicate enhanced stability for ions containing n = 2, 4, 14, 28, 42, …

Single-Molecule Localization Microscopy Of 3d Orientation And Anisotropic Wobble Using A Polarized Vortex Point Spread Function, Tianben Ding, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

Within condensed matter, single fluorophores are sensitive probes of their chemical environments, but it is difficult to use their limited photon budget to image precisely their positions, 3D orientations, and rotational diffusion simultaneously. We demonstrate the polarized vortex point spread function (PSF) for measuring these parameters, including characterizing the anisotropy of a molecule’s wobble, simultaneously from a single image. Even when imaging dim emitters (∼500 photons detected), the polarized vortex PSF can obtain 12 nm localization precision, 4°–8° orientation precision, and 26° wobble precision. We use the vortex PSF to measure the emission anisotropy of fluorescent beads, the wobble dynamics …

Calibration Of Gas Flow Meters Using Choked Flow And An Evacuated Vessel, Max B. Trueblood, Otmar Schmid, Nicholas Altese, Christian J. Hurst, Wenyan Liu, Teresa Gelles, Steven C. Achterberg, Philip D. Whitefield, Donald E. Hagen

Chemistry Faculty Research & Creative Works

The measurement of gas flow rates is of great importance in a wide range of modern technologies. This paper introduces a simple, yet accurate technique for in-house calibration of gas FMs (mass and volumetric) even under harsh environmental conditions such as encountered during field measurement campaigns. The method requires only readily available, low cost components: a vessel of known volume, an air pump, a pressure sensor and a metal plate orifice or a needle valve to act as a CO. The unique property of choked flow in the CO is used here for flow calibration. In the method presented here …

Reinvigorating A Technical Countering Weapons Of Mass Destruction Distance Learning Graduate Certificate Program, James C. Petrosky, Gaiven Varshney, Jeremy Slagley, Sara Shaghaghi

Faculty Publications

Current Countering Weapons of Mass Destruction (CWMD) demands can be divided broadly into policy and science. The science of chemical, biological, and radiological/nuclear weapons informs the limits of development, production, employment, operation, detection, risk characterization, human and material protection, and medical intervention. In short, the science of weapons of mass destruction (WMD) should precede and inform the development of policy. It is to this end that the Air Force Institute of Technology (AFIT) CWMD program was re-established, providing a technical educational option for practitioners to understand the science behind a very technically challenging subject.

Silk-Cellulose Acetate Biocomposite Materials Regenerated From Ionic Liquid, Ashley Rivera-Galetti, Chrtstopher R. Gough, Farhan Kaleem, Michael Burch, Chris Ratcliffe, Ping Lu, David Salas-De La Cruz, Xiao Hu

Faculty Scholarship for the College of Science & Mathematics

The novel use of ionic liquid as a solvent for biodegradable and natural organic biomaterials has increasingly sparked interest in the biomedical field. As compared to more volatile traditional solvents that rapidly degrade the protein molecular weight, the capability of polysaccharides and proteins to dissolve seamlessly in ionic liquid and form fine and tunable biomaterials after regeneration is the key interest of this study. Here, a blended system consisting of Bombyx Mori silk fibroin protein and a cellulose derivative, cellulose acetate (CA), in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIMAc) was regenerated and underwent characterization to understand the structure and physical …

Catalytic Pyrolysis Of Lignin Model Compounds (Pyrocatechol, Guaiacol, Vanillic And Ferulic Acids) Over Nanoceria Catalyst For Biomass Conversion, Nataliia Nastasiienko, Tetiana Kulik, Borys Palianytsia, Julia Laskin, Tetiana Cherniavska, Mykola Kartel, Mats Larsson

Department of Chemistry Faculty Publications

Understanding the mechanisms of thermal transformations of model lignin compounds (MLC) over nanoscale catalysts is important for improving the technologic processes occurring in the pyrolytic conversion of lignocellulose biomass into biofuels and value-added chemicals. Herein, we investigate catalytic pyrolysis of MLC (pyrocatechol (P), guaiacol (G), ferulic (FA), and vanillic acids (VA)) over nanoceria using FT-IR spectroscopy, temperature-programmed desorption mass spectrometry (TPD MS), and thermogravimetric analysis (DTG/DTA/TG). FT-IR spectroscopic studies indicate that the active groups of aromatic rings of P, G, VA, and FA as well as carboxylate groups of VA and FA are involved in the interaction with nanoceria surface. …

Bridging The 12-6-4 Model And The Fluctuating Charge Model, Pengfei Li

Chemistry: Faculty Publications and Other Works

Metal ions play important roles in various biological systems. Molecular dynamics (MD) using classical force field has become a popular research tool to study biological systems at the atomic level. However, meaningful MD simulations require reliable models and parameters. Previously we showed that the 12-6 Lennard-Jones nonbonded model for ions could not reproduce the experimental hydration free energy (HFE) and ion-oxygen distance (IOD) values simultaneously when ion has a charge of +2 or higher. We discussed that this deficiency arises from the overlook of the ion-induced dipole interaction in the 12-6 model, and this term is proportional to 1/r …

Photovoltages In Polycrystalline Mosaic Solar Cells, Steluta A. Dinca, Eric A. Schiff

Chemistry - All Scholarship

In some thin-film solar cells the light-absorbing layer is a mosaic of crystalline grains whose boundaries run from the back to the front of the cell. We used the semiconductor modeling software Sesame to do numerical calculations of the optoelectronic properties of such cells assuming that recombination of minority photocarriers occurs primarily at the grain boundaries. The work complements analytical results for diffusion-limited recombination at grain boundaries and dislocations. We chose idealized n-CdS/p-CdTe solar cells for illustration. We find that the open-circuit voltage, V_oc, under illumination declines logarithmically with increasing ratio D/θ², where D is the …

Experimental Evidence That Metapopulation Structure Can Accelerate Adaptive Evolution, Partha Pratim Chakraborty, Louis R. Nemzer, Rees Kassen

Chemistry and Physics Faculty Articles

Whether the spatial arrangement of a population influences adaptive evolution has been a long-standing question in population genetics. In contrast to standard population genetic models, evolutionary graph theory (EGT) predicts certain topologies amplify (increase) the probability that a beneficial mutation will spread in the population relative to a well-mixed population. Here, we test these predictions empirically by tracking the fixation dynamics of an antibiotic resistant mutant under positive selection as it spreads through networks of different topologies both in vitro and in silico. We show that star-like topologies involving bi-directional dispersal between a central hub and peripheral leaves can …

Awegnn: Auto-Parametrized Weighted Element-Specific Graph Neural Networks For Molecules., Timothy Szocinski, Duc Duy Nguyen, Guo-Wei Wei

Mathematics Faculty Publications

While automated feature extraction has had tremendous success in many deep learning algorithms for image analysis and natural language processing, it does not work well for data involving complex internal structures, such as molecules. Data representations via advanced mathematics, including algebraic topology, differential geometry, and graph theory, have demonstrated superiority in a variety of biomolecular applications, however, their performance is often dependent on manual parametrization. This work introduces the auto-parametrized weighted element-specific graph neural network, dubbed AweGNN, to overcome the obstacle of this tedious parametrization process while also being a suitable technique for automated feature extraction on these internally complex …

Recovery Of High Specific Activity Molybdenum-99 From Accelerator-Induced Fission On Low-Enriched Uranium For Technetium-99m Generators, M. Alex Brown, Nathan Johnson, Artem V. Gelis, Milan Stika, Anna G. Servis, Alex Bakken, Christine Krizmanich, Kristin Shannon, Peter Kozak, Amanda Barnhart, Chad Denbrock, Nicolas Luciani, Terry Grimm, Peter Tkac

Chemistry and Biochemistry Faculty Research

A new process was developed to recover high specific activity (no carrier added) 99Mo from electron-accelerator irradiated U3O8 or uranyl sulfate targets. The process leverages a novel solvent extraction scheme to recover Mo using di(2-ethylhexyl) phosphoric acid following uranium and transuranics removal with tri-n-butyl phosphate. An anion-exchange concentration column step provides a final purification, generating pure 99Mo intended for making 99Mo/99mTc generators. The process was demonstrated with irradiated uranium targets resulting in more than 95% 99Mo recovery and without presence of fission products or actinides in the product.

Evaluation Of Log P, Pka, And Log D Predictions From The Sampl7 Blind Challenge, Teresa Danielle Bergazin, Nicolas Tielker, Yingying Zhang, Junjun Mao, M. R. Gunner, Karol Francisco, Carlo Ballatore, Stefan M. Kast, David L. Mobley

Publications and Research

The Statistical Assessment of Modeling of Proteins and Ligands (SAMPL) challenges focuses the computational modeling community on areas in need of improvement for rational drug design. The SAMPL7 physical property challenge dealt with prediction of octanol-water partition coefficients and pK_a for 22 compounds. The dataset was composed of a series of N-acylsulfonamides and related bioisosteres. 17 research groups participated in the log P challenge, submitting 33 blind submissions total. For the pK_a challenge, 7 different groups participated, submitting 9 blind submissions in total. Overall, the accuracy of octanol-water log P predictions in the SAMPL7 challenge was …

Β -Technetium: An Allotrope With A Nonstandard Volume-Pressure Relationship, Emily Siska, Dean Smith, Christian Childs, Daniel Koury, Paul M. Forster, Keith V. Lawler, Ashkan Salamat

Chemistry and Biochemistry Faculty Research

We report the synthesis and structure of the second allotrope of technetium, β-Tc. Transformative pathways are accessed at extreme conditions using the laser-heated diamond anvil cell and confirmed with in situ synchrotron x-ray diffraction and Raman spectroscopy. β-Tc is fully recoverable to ambient conditions, although counter to our DFT calculations predicting a face-centered-cubic lattice, we observe a tetragonal structure (I4/mmm) that exhibits further tetragonal distortion with pressure. β-Tc has an expanded volume relative to the hcp ground state phase, that when doped with nitrogen has an unexpected volume lowering. Such anomalous behavior is possibly indicative of a rare electronic phase …

Complexes With Atomic Gold Ions: Efficient Bisligand Formation, Felix Duensing, Elisabeth Gruber, Paul Martini, Marcelo Goulart, Michael Gatchell, Bilal Rasul, Olof E. Echt, Fabio Zappa, Masoomeh Mahmoodi-Darian, Paul Scheier

Faculty Publications

Complexes of atomic gold with a variety of ligands have been formed by passing helium nanodroplets (HNDs) through two pickup cells containing gold vapor and the vapor of another dopant, namely a rare gas, diatomic molecule (H₂, N₂, O₂, I₂, P₂), or various polyatomic molecules (H₂O, CO₂, SF₆, C₆H₆, adamantane, imidazole, di-cyclopentadiene, and fullerene). The doped HNDs were irradiated by electrons; ensuing cations were identified in a high-resolution mass spectrometer. Anions were detected for benzene, di-cyclopentadiene, and fullerene. For most …

Colossal Density-Driven Resistance Response In The Negative Charge Transfer Insulator Mns2, Dylan Durkee, Nathan Dasenbrock-Gammon, G. Alexander Smith, Elliot Snider, Dean Smith, Christian Childs, Simon A.J. Kimber, Keith V. Lawler, Ranga P. Dias, Ashkan Salamat

Chemistry and Biochemistry Faculty Research

A reversible density driven insulator to metal to insulator transition in high-spin MnS2 is experimentally observed, leading with a colossal electrical resistance drop of 108 ω by 12 GPa. Density functional theory simulations reveal the metallization to be unexpectedly driven by previously unoccupied S22- σ3p∗ antibonding states crossing the Fermi level. This is a unique variant of the charge transfer insulator to metal transition for negative charge transfer insulators having anions with an unsaturated valence. By 36 GPa the emergence of the low-spin insulating arsenopyrite (P21/c) is confirmed, and the bulk metallicity is broken with the system returning to an …

Sf6+: Stabilizing Transient Ions In Helium Nanodroplets, Simon Albertini, Stefan Bergmeister, Felix Laimer, Paul Martini, Elisabeth Gruber, Fabio Zappa, Milan Ončák, Paul Scheier, Olof E. Echt

Faculty Publications

There are myriads of ions that are deemed too short-lived to be experimentally accessible. One of them is SF₆⁺. It has never been observed, although not for lack of trying. We demonstrate that long-lived SF₆⁺ can be formed by doping charged helium nanodroplets (HNDs) with sulfur hexafluoride; excess helium is then gently stripped from the doped HNDs by collisions with helium gas. The ion is identified by high-resolution mass spectrometry (resolution m/Dm = 15000), the close agreement between the expected and observed yield of ions that contain minor sulfur isotopes, and collision-induced dissociation …

Direct Detection Of 5-Mev Protons By Flexible Organic Thin-Film Devices, Ilaria Fratelli, Andrea Ciavatti, Enrico Zanazzi, Laura Basiricò, Massimo Chiari, Laura Fabbri, John E. Anthony, Alberto Quaranta, Beatrice Fraboni

Chemistry Faculty Publications

The direct detection of 5-MeV protons by flexible organic detectors based on thin films is here demonstrated. The organic devices act as a solid-state detector, in which the energy released by the protons within the active layer of the sensor is converted into an electrical current. These sensors can quantitatively and reliably measure the dose of protons impinging on the sensor both in real time and in integration mode. This study shows how to detect and exploit the energy absorbed both by the organic semiconducting layer and by the plastic substrate, allowing to extrapolate information on the present and past …

Pressure- And Temperature-Dependent Inelastic Neutron Scattering Study Of The Phase Transition And Phonon Lattice Dynamics In Para-Terphenyl, Qingan Cai, Michael Mcintire, Luke L. Daemen, Chen Li, Eric Chronister

Chemistry and Biochemistry Faculty Research

Inelastic neutron scattering has been performed on para-terphenyl at temperatures from 10 to 200 K and under pressures from the ambient pressure to 1.51 kbar. The temperature dependence of phonons, especially low-frequency librational bands, indicates strong anharmonic phonon dynamics. The pressure- and temperature-dependence of the phonon modes suggest a lack of phase transition in the region of 0-1.51 kbar and 10-30 K. Additionally, the overall lattice dynamics remains similar up to 200 K under the ambient pressure. The results suggest that the boundary between the ordered triclinic phase and the third solid phase, reported at lower temperatures and higher pressures, …

Alternative View Of Oxygen Reduction On Porous Carbon Electrocatalysts: The Substance Of Complex Oxygen-Surface Interactions, Giacomo De Falco, Marc Florent, Jacek Jagiello, Yongqiang Cheng, Luke L. Daemen, Anibal J. Ramirez-Cuesta, Teresa J. Bandosz

Publications and Research

Electrochemical oxygen reduction reaction (ORR) is an important energy-related process requiring alternative catalysts to expensive platinum-based ones. Although recently some advancements in carbon catalysts have been reported, there is still a lack of understanding which surface features might enhance their efficiency for ORR. Through a detailed study of oxygen adsorption on carbon molecular sieves and using inelastic neutron scattering, we demonstrated here that the extent of oxygen adsorption/interactions with surface is an important parameter affecting ORR. It was found that both the strength of O2 physical adsorption in small pores and its specific interactions with surface ether functionalities in the …

Electronic Transitions In Rb2+ Dimers Solvated In Helium, Simon Albertini, Paul Martini, Arne Schiller, Harald Schöbel, Elham Ghavidel, Milan Ončák, Olof E. Echt, Paul Scheier

Faculty Publications

We have measured depletion spectra of the heteronuclear (⁸⁵Rb⁸⁷Rb⁺) dimer cation complexed with up to 10 He atoms. Two absorption bands are observed between 920 and 250 nm. The transition into the repulsive 1²Sigma_u⁺ state of HeRb₂⁺ gives rise to a broad feature at 790 nm (12650 cm^–1); it exhibits a blueshift of 98 cm^–1 per added He atom. The transition into the bound 1 ²Pi_u state of HeRb₂⁺ reveals vibrational structure with a band head at < 15522 cm^–1, a harmonic …

Computational Modelling Enables Robust Multidimensional Nanoscopy, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

The following sections are included:

• Present State of Computational Modelling in Fluorescence Nanoscopy

• Recent Contributions to Computational Modelling in Fluorescence Nanoscopy

• Outlook on Computational Modelling in Fluorescence Nanoscopy

• Acknowledgments

• References

Numerical Reconstruction Of Spalled Particle Trajectories In An Arc-Jet Environment, Raghava S. C. Davuluri, Sean C. C. Bailey, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

To evaluate the effects of spallation on ablative material, it is necessary to evaluate the mass loss. To do so, a Lagrangian particle trajectory code is used to reconstruct trajectories that match the experimental data for all kinematic parameters. The results from spallation experiments conducted at the NASA HYMETS facility over a wedge sample were used. A data-driven adaptive methodology was used to adapts the ejection parameters until the numerical trajectory matches the experimental data. The preliminary reconstruction results show that the size of the particles seemed to be correlated with the location of the ejection event. The size of …

A Synergistic Anti-Diabetic Effect By Ginsenosides Rb1 And Rg3 Through Adipogenic And Insulin Signaling Pathways In 3t3-L1 Cells, Hee-Do Hong, Sun-Il Choi, Ok-Hwan Lee, Young-Cheul Kim

Nutrition Department Faculty Publication Series

Although ginsenosides Rb1 and Rg3 have been identified as the significant ginsenosides found in red ginseng that confer anti-diabetic actions, it is unclear whether insulin-sensitizing effects are mediated by the individual compounds or by their combination. To determine the effect of ginsenosides Rb1 and Rg3 on adipocyte differentiation, 3T3-L1 preadipocytes were induced to differentiate the standard hormonal inducers in the absence or presence of ginsenosides Rb1 or Rg3. Additionally, we determined the effects of Rb1, Rg3, or their combination on the expression of genes related to adipocyte differentiation, adipogenic transcription factors, and the insulin signaling pathway in 3T3-L1 cells using …

Advanced Raman Spectroscopy Detection Of Oxidative Damage In Nucleic Acid Bases: Probing Chemical Changes And Intermolecular Interactions In Guanosine At Ultralow Concentration, Francesca Ripanti, Claudia Fasolato, Flavia Mazzarda, Simonetta Palleschi, Marina Ceccarini, Chunchun Li, Margherita Bignami, Enrico Bodo, Steven E.J. Bell, Filomena Mazzei, Paolo Postorino

Bioelectrics Publications

DNA/RNA synthesis precursors are especially vulnerable to damage induced by reactive oxygen species occurring following oxidative stress. Guanosine triphosphates are the prevalent oxidized nucleotides, which can be misincorporated during replication, leading to mutations and cell death. Here, we present a novel method based on micro-Raman spectroscopy, combined with ab initio calculations, for the identification, detection, and quantification of oxidized nucleotides at low concentration. We also show that the Raman signature in the terahertz spectral range (<100 >cm(-1)) contains information on the intermolecular assembly of guanine in tetrads, which allows us to further boost the oxidative damage detection limit. Eventually, we …

Environmental Modifications Of Atomic Properties: The Ground And 1s2p Excited States Of Compressed Helium, N. C. Pyper, T. C. Naginey, Colm T. Whelan

Physics Faculty Publications

Atoms remaining as recognizably distinct constituents of bulk condensed phases can have properties modified from those of the isolated species. Dense helium bubbles at high pressures are a common form of radiation damage degrading the mechanical and electrical properties of host materials. Detailed knowledge is critical for predicting their long term performance. Modifications of the ground and first singlet excited states of confined compressed helium are investigated using an entirely non-empirical theory based on the results of ab initio self-consistent field calculations with corrections for the effects of electron correlation. For finite sized portions representing bulk condensed fcc and bcc …

Tri-Molybdenum Phosphide (Mo3P) And Multi-Walled Carbon Nanotube Junctions For Volatile Organic Compounds (Vocs) Detection, Baleeswaraiah Muchharla, Praveen Malali, Brenna Daniel, Alireza Kondori, Mohammad Asadi, Wei Cao, Hani E. Elsayed-Ali, Mickaël Castro, Mehran Elahi, Adetayo Adedeji, Kishor Kumar Sadasivuni, Muni Raj Mauya, Kapil Kumar, Abdennaceur Karoui, Bijandra Kumar

Electrical & Computer Engineering Faculty Publications

Detection and analysis of volatile organic compounds’ (VOCs) biomarkers lead to improvement in healthcare diagnosis and other applications such as chemical threat detection and food quality control. Here, we report on tri-molybdenum phosphide (Mo₃P) and multi- walled carbon nanotube (MWCNT) junction-based vapor quantum resistive sensors (vQRSs), which exhibit more than one order of magni- tude higher sensitivity and superior selectivity for biomarkers in comparison to pristine MWCNT junctions based vQRSs. Transmission electron microscope/scanning tunneling electron microscope with energy dispersive x-ray spectroscopy, x-ray diffraction, and x-ray photo- electron spectroscopy studies reveal the crystallinity and the presence of Mo and …

Simulation Studies On The Interactions Of Electron Beam With Wastewater, X. Li, S. Wang, Helmut Baumgart, G. Ciovati, F. Hannon

Electrical & Computer Engineering Faculty Publications

The manufactured chemical pollutants, like 1,4 dioxane and PFAS (per- and polyfluroralkyl substances), found in the underground water and/or drinking water are challenging to be removed or biodegraded. Energetic electrons are capable of mediating and removing them. This paper utilizes FLUKA code to evaluate the beam-wastewater interaction effects with different energy, space and divergence distributions of the electron beam. With 8 MeV average energy, the electron beam exits from a 0.0127 cm thick titanium window, travels through a 4.3 cm distance air and a second 0.0127 cm thick stainless water container window with 2.43 cm radius, and finally is injected …