Physical Sciences and Mathematics Commons^™

Exploring The Relationships Among Stoichiometric Coefficients, Number Of Transferred Electrons, Mean Oxidation Number Of Carbons, And Oxidative Ratio In Organic Combustion Reactions, Pong Kau Yuen, Cheng Man Diana Lau

Faculty Publications

Combustion reactions, stoichiometry, and redox reactions are some of the basic contents in chemistry curriculum. Although the counting of transferred electrons is critical in redox reactions, assigning mean oxidation number of organic carbons (ONc) is not always easy. Even though the relationship between the oxidative ratio (OR) and ONc is known, the relationship between the number of transferred electrons (Te−) and OR has not been thoroughly studied. The H-atom method has already been developed to balance and deduct organic combustion reactions. It can be used further to help establish the relationships among the stoichiometric coefficients (SC), the number of transferred …

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 …

Single-Variable Porous Nanomaterial Series From Polymer Structure-Directing Agents, Morgan Stefik

Faculty Publications

Block polymer structure-directing agents (SDA) enable the production of porous nanoscale materials. Most strategies rely upon polymer equilibration where diverse morphologies are realized in porous functional materials. This review details how solvent selectivity determines the polymer SDA behaviors, spanning from bulk-type to solution-type. Equilibrating behavior of either type, however, obscures nanostructure cause-and-effect since the resulting sample series convolve multiple spatial variations. Solution-type SDA behaviors include both dynamic and persistent micelles. Persistent micelle templates (PMT) use high solvent selectivity for kinetic entrapment. PMTs enable independent wall thickness control with demonstrated 2 Å precision alterations. Unimodal PMT pore size distributions have spanned …

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, …

New Approach For Assigning Mean Oxidation Number Of Carbons To Organonitrogen And Organosulfur Compounds, Pong Kau Yuen, Cheng Man Diana Lau

Faculty Publications

Organonitrogen and organosulfur compounds are abundant in the natural environment. To understand the biological redox pathways properly, it is important for learners to be able to count the oxidation number of organic carbons. However, the process of counting is not always easy. In addition, organonitrogen and organosulfur molecules are seldom studied. To compensate these problems, this paper explores the bonddividing method, which can effectively determine the mean oxidation number of carbons of organonitrogen and organosulfur molecules. This method uses the cleavage of carbon-sulfur and carbon-nitrogen bonds to obtain the organic and inorganic fragments. The mean oxidation numbers of carbon atoms, …

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.

Fe-Catalyzed Sulfide Oxidation In Hydrothermal Plumes Is A Source Of Reactive Oxygen Species To The Ocean, Timothy J. Shaw, George W. Luther Iii, Richard Rosas, Véronique E. Oldham, Nicole R. Coffey, John L. Ferry, Dewamunnage M. C. Dias, Mustafa Yücel, Aubin Thibault De Chanvalon

Faculty Publications

Historically, the production of reactive oxygen species (ROS) in the ocean has been attributed to photochemical and biochemical reactions. However, hydrothermal vents emit globally significant inventories of reduced Fe and S species that should react rapidly with oxygen in bottom water and serve as a heretofore unmeasured source of ROS. Here, we show that the Fe-catalyzed oxidation of reduced sulfur species in hydrothermal vent plumes in the deep oceans supported the abiotic formation of ROS at concentrations 20 to 100 times higher than the average for photoproduced ROS in surface waters. ROS (measured as hydrogen peroxide) were determined in hydrothermal …

Small Studies, Big Decisions: The Role Of Pilot/Feasibility Studies In Incremental Science And Premature Scale-Up Of Behavioral Interventions, Michael William Beets, Lauren Von Klinggraeff, Robert G. Weaver, Bridget Ryan Armstrong, Sarah Burkart

Faculty Publications

Background: Careful consideration and planning are required to establish “sufficient” evidence to ensure an investment in a larger, more well-powered behavioral intervention trial is worthwhile. In the behavioral sciences, this process typically occurs where smaller-scale studies inform larger-scale trials. Believing that one can do the same things and expect the same outcomes in a larger-scale trial that were done in a smaller-scale preliminary study (i.e., pilot/feasibility) is wishful thinking, yet common practice. Starting small makes sense, but small studies come with big decisions that can influence the usefulness of the evidence designed to inform decisions about moving forward with a …

Encirclement Of Moving Targets Using Noisy Range And Bearing Measurements, Cammy Peterson, Puneet Jain, Randal Beard

Faculty Publications

This paper presents theoretically justified controllers that use relative range and bearing measurements to steer a team of autonomous vehicles, operating without inertial position information, to circular trajectories around a constant-acceleration, constant-velocity, or stationary target. An extended Kalman filter is used to improve the noisy relative measurements and estimate the velocity of the moving target. These estimated values are used in the control laws to encircle constant-velocity moving targets. Lyapunov techniques are utilized to show that the vehicle will converge to the desired circular formations. Additionally, cooperating vehicles are shown to converge to a circular formation with equal temporal spacing …

Heteroacene-Based Amphiphile As A Molecular Scaffold For Bioimaging Probes, Tharindu A. Ranathunge, Mahesh Loku Yaddehige, Jordan H. Varma, Cameron Smith, Jay Nguyen, Iyanuoluwani Owolabi, Wojciech Kolodziejczyk, Nathan I. Hammer, Glake Hill, Alex Flynt, Davita L. Watkins

Faculty Publications

The challenges faced with current fluorescence imaging agents have motivated us to study two nanostructures based on a hydrophobic dye, 6H-pyrrolo[3,2-b:4,5-b’]bis [1,4]benzothiazine (TRPZ). TRPZ is a heteroacene with a rigid, pi-conjugated structure, multiple reactive sites, and unique spectroscopic properties. Here we coupled TRPZ to a tert-butyl carbamate (BOC) protected 2,2-bis(hydroxymethyl)propanoic acid (bisMPA) dendron via azide-alkyne Huisgen cycloaddition. Deprotection of the protected amine groups on the dendron afforded a cationic terminated amphiphile, TRPZ-bisMPA. TRPZ-bisMPA was nanoprecipitated into water to obtain nanoparticles (NPs) with a hydrodynamic radius that was <150 nm. For comparison, TRPZ-PG was encapsulated in pluronic-F127 (Mw …

Swir Emissive Rosindolizine Dyes With Nanoencapsulation In Water Soluble Dendrimers, Satadru Chatterjee, William E. Meador, Cameron Smith, Indika Chandrasiri, Mohammad Farid Zia, Jay Nguyen, Austin Dorris, Alex Flynt, Davita L. Watkins, Nathan I. Hammer, Jared H. Delcamp

Faculty Publications

Shortwave infrared (SWIR) emission has great potential for deep-tissue in vivo biological imaging with high resolution. In this article, the synthesis and characterization of two new xanthene-based RosIndolizine dyes coded ^PhRosIndz and ^tolRosIndz is presented. The dyes are characterized via femtosecond transient absorption spectroscopy as well as steady-state absorption and emission spectroscopies. The emission of these dyes is shown in the SWIR region with peak emission at 1097 nm. ^TolRosIndz was encapsulated with an amphiphilic linear dendritic block co-polymer (LDBC) coded 10-PhPCL-G3 with high uptake yield. Further, cellular toxicity was examined in vitro using HEK (human embryonic …

Health Disparity And Covid-19—A Retrospective Analysis, Sanjay Sarkar, Archie Taylor, Pratik Dutta, Bidisha Sengupta, Debarshi Roy

Faculty Publications

Background and Aims

According to the World Health Organization (WHO), more than 75.7 million confirmed cases of coronavirus disease 2019 (COVID-19), a global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), have been reported so far. Researchers are working relentlessly to find effective solutions to this catastrophe, using genomic sequence-based investigation, immunological analysis, and more. The role of health disparity has also emerged as an intriguing factor that made a huge impact on the lives of people.

Methods

We analyzed various factors that triggered the health disparity in the United States of America along with the rate of …

Free Three-Dimensional Carborane Carbanions, H.D.A. Zzzchathumal Jayaweera, Md. Mamdudur Rahman, Perry J. Pellechia, Mark D. Smith, Dmitry V. Peryshkov

Faculty Publications

Carbon atom functionalization via generation of carbanions is the cornerstone of carborane chemistry. In this work, we report the synthesis and structural characterization of free ortho-carboranyl [C₂B₁₀H₁₁]⁻, a three-dimensional inorganic analog of the elusive phenyl anion that features a “naked” carbanion center. The first example of a stable, discrete C(H)-deprotonated carborane anion was isolated as a completely separated ion pair with a crown ether-encapsulated potassium cation. An analogous approach led to the isolation and structural characterization of a doubly deprotonated 1,1′-bis(o-carborane) anion [C₂B₁₀H₁₀] …

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 …

Tailored Porous Carbons Enabled By Persistent Micelles With Glassy Cores, Eric R. Williams, Paige L. Mcmahon, Joseph E. Reynolds Iii, Jonathan L. Snider, Vitalie Stavila, Mark Allendorf, Morgan Stefik

Faculty Publications

Porous nanoscale carbonaceous materials are widely employed for catalysis, separations, and electrochemical devices where device performance often relies upon specific and well-defined regular feature sizes. The use of block polymers as templates has enabled affordable and scalable production of diverse porous carbons. However, popular carbon preparations use equilibrating micelles which can change dimensions in response to the processing environment. Thus, polymer methods have not yet demonstrated carbon nanomaterials with constant average template diameter and tailored wall thickness. In contrast, persistent micelle templates (PMTs) use kinetic control to preserve constant micelle template diameters, and thus PMT has enabled constant pore diameter …

Host–Guest Interactions In A Metal–Organic Framework Isoreticular Series For Molecular Photocatalytic Co2 Reduction, Philip M. Stanley, Johanna Haimerl, Christopher Thomas, Alexander Urstoeger, Michael Schuster Prof. Dr., Natalia B. Shustova Prof. Dr., Angela Casini Prof. Dr., Bernhard Rieger Prof. Dr., Julien Warnan Dr., Roland A. Fischer Prof. Dr.

Faculty Publications

A strategy to improve homogeneous molecular catalyst stability, efficiency, and selectivity is the immobilization on supporting surfaces or within host matrices. Herein, we examine the co-immobilization of a CO2 reduction catalyst [ReBr(CO)3(4,4′-dcbpy)] and a photosensitizer [Ru(bpy)2(5,5′-dcbpy)]Cl2 using the isoreticular series of metal–organic frameworks (MOFs) UiO-66, -67, and -68. Specific host pore size choice enables distinct catalyst and photosensitizer spatial location—either at the outer MOF particle surface or inside the MOF cavities—affecting catalyst stability, electronic communication between reaction center and photosensitizer, and consequently the apparent catalytic rates. These results allow for a rational understanding of an optimized supramolecular layout of catalyst, …

Beyond Structural Motifs: The Frontier Of Actinide-Containing Metal–Organic Frameworks, Corey R. Martin, Gabrielle A. Leith, Natalia B. Shustova Prof. Dr.

Faculty Publications

In this perspective, we feature recent advances in the field of actinide-containing metal–organic frameworks (An-MOFs) with a main focus on their electronic, catalytic, photophysical, and sorption properties. This discussion deviates from a strictly crystallographic analysis of An-MOFs, reported in several reviews, or synthesis of novel structural motifs, and instead delves into the remarkable potential of An-MOFs for evolving the nuclear waste administration sector. Currently, the An-MOF field is dominated by thorium- and uranium-containing structures, with only a few reports on transuranic frameworks. However, some of the reported properties in the field of An-MOFs foreshadow potential implementation of these materials and …

Beyond Structural Motifs: The Frontier Of Actinide-Containing Metal–Organic Frameworks, Corey R. Martin, Gabrielle A. Leith, Natalia B. Shustova

Faculty Publications

In this perspective, we feature recent advances in the field of actinide-containing metal-organic frameworks (An-MOFs) with a main focus on their electronic, catalytic, photophysical, and sorption properties. This discussion deviates from a strictly crystallographic analysis of An-MOFs, reported in several reviews, or synthesis of novel structural motifs, and instead delves into the remarkable potential of An-MOFs for evolving the nuclear waste administration sector. Currently, the An-MOF field is dominated by thorium- and uranium-containing structures, with only a few reports on transuranic frameworks. However, some of the reported properties in the field of An-MOFs foreshadow potential implementation of these materials and …

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 …

Engineering Donor-Acceptor Conjugated Polymers For High-Performance And Fast-Response Organic Electrochemical Transistors, Hanyu Jia, Zhen Huang, Peiyun Li, Song Zhang, Yunfei Wang, Jie Yu Wang, Xiaodan Gu, Ting Lei

Faculty Publications

To date, high-performance organic electrochemical transistors (OECTs) have mostly been based on polythiophene systems. Donor–acceptor (D–A) conjugated polymers are expected to be promising materials for OECTs owing to their high mobility and comparatively low crystallinity (good for ion diffusion). However, the OECT performance of D–A polymers lags far behind that of the polythiophenes. Here we synergistically engineered the backbone and side chain of a series of diketopyrrolopyrrole (DPP)-based D–A polymers and found that redox potential, molecular weight, solution processability, and film microstructures all have a severe impact on their performance. After systematic engineering, P(bgDPP-MeOT2) exhibited the best figure-of-merit (μC …

The Supercam Instrument Suite On The Mars 2020 Rover: Science Objectives And Mast-Unit Description, S. Maurice, R. C. Wiens, P. Bernardi, P. Caïs, S. Robinson, T. Nelson, O. Gasnault, J. -M. Reess, M. Deleuze, F. Rull, J. -A. Manrique, S. Abbaki, R. B. Anderson, Y. André, Stanley M. Angel, G. Arana, T. Battault, P. Beck, K. Benzerara, S. Bernard, Et. Al.

Faculty Publications

On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2–7 m, while providing data at sub-mm to mm scales. We report …

Broken-Hearted” Carbon Bowl Via Electron Shuttle Reaction: Energetics And Electron Coupling, Gabrielle A. Leith, Allison M. Rice, Brandon J. Yarbrough, Preecha Kittikhunnatham, Abijai Mathur, Nicholas A. Morris, Megan J. Francis, Anna A. Berseneva, Poonam Dhull, Richard D. Adams, M. Victoria Bobo, Aaron A. Vannucci, Mark D. Smith, Sophya Garashchuk, Natalia B. Shustova

Faculty Publications

Unprecedented one-step CC bond cleavage leading to opening of the buckybowl (π-bowl), that could provide access to carbon-rich structures with previously inaccessible topologies, is reported; highlighting the possibility to implement drastically different synthetic routes to π-bowls in contrast to conventional ones applied for polycyclic aromatic hydrocarbons. Through theoretical modeling, we evaluated the mechanistic pathways feasible for π-bowl planarization and factors that could affect such a transformation including strain and released energies. Through employment of Marcus theory, optical spectroscopy, and crystallographic analysis, we estimated the possibility of charge transfer and electron coupling between “open” corannulene and a strong electron acceptor such …

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 …

Transepithelial Anti-Neuroblastoma Response To Kale Among Four Vegetable Juices Using In Vitro Model Co-Culture System, John Piletz, Yuhan Mao, Debarshi Roy, Bilal Qizilbash, Eurielle Nkamssi, Enleyona Weir, Jessica Graham, Mary Emmanuel, Suwaira Iqbal, Kellie Brue, Bidisha Roy Sengupta

Faculty Publications

Juicing vegetables is thought to be an anticancer treatment. Support exists for a rank order of anticancer greens (kale > dandelion > lettuce > spinach) based on degrees of bioavailability of different phytochemicals, also offset by some noxious molecules (i.e., calcium-oxalate). We developed a new in vitro transepithelial anti-neuroblastoma model system. The juices were diluted as predicted once in the small intestine. They were applied to apical Caco-2Bbe1 cells atop dividing SH-SY5Y neuroblastoma cells, and changes in transepithelial electrical resistance (TEER) and cell growth were considered with juice spectroscopies. Studied first in monoculture, kale and dandelion were the most cytostatic juices on SH-SY5Ys, …

Self-Assembled Thermoresponsive Nanogel From Grafted Hyaluronic Acid As A Biocompatible Delivery Platform For Curcumin With Enhanced Drug Loading And Biological Activities, Jittima Amie Luckanagul, Pahweenvaj Ratnatilaka Na Bhuket, Chawanphat Muangnoi, Pranee Rojsitthisak, Qian Wang, Pornchai Rojsitthisak

Faculty Publications

A hyaluronic acid-grafted poly(N-isopropylacrylamide) (HA-pNIPAM) was synthesized as a polymeric nanogel platform for encapsulation and delivery of hydrophobic bioactive compounds using curcumin as a model drug. As demonstrated by transmission electron microscopy and dynamic light scattering techniques, the HA-pNIPAM was simply assembled into spherical nano-sized particles with the thermoresponsive behavior. The success of curcumin aqueous solubilization was confirmed by fluorescent spectroscopy. The resulting nanogel formulation enhanced the aqueous solubility and uptake into NIH-3T3 cells of curcumin. This nanogel formulation also demonstrates cytocompatibility against NIH-3T3 cells, which deems it safe as a delivery vehicle. Moreover, the formulation has a slight skin-protection …

Direct Determination Of Absolute Stereochemistry Of Α-Methylselenocysteine Using The Mosher Method, Robert J. Wehrle, Douglas R. Powell, Douglas S. Masterson

Faculty Publications

Mosher amides of α-methylselenocysteine were synthesized to determine the absolute stereochemistry of the sterically hindered α-carbon utilizing ¹H, ¹³C, ¹⁹F, and ⁷⁷Se NMR spectroscopies. After analysis of these spectra using the established Mosher method, the stereochemistry of the α-carbon was determined to be (R), which was subsequently confirmed using x-ray crystallography.

Dicer Represses The Interferon Response And The Double-Stranded Rna-Activated Protein Kinase Pathway In Mouse Embryonic Stem Cells, Chandan Gurung, Mona Fendereski, Krishna Sapkota, Jason Guo, Faqing Huang, Yan Lin Guo

Faculty Publications

Recent studies have demonstrated that embryonic stem cells (ESCs) are deficient in expressing type I interferons (IFN), the cytokines that play key roles in antiviral responses. However, the underlying molecular mechanisms and biological implications of this finding are poorly understood. In this study, we developed a synthetic RNA-based assay that can simultaneously assess multiple forms of antiviral responses. Dicer is an enzyme essential for RNA interference (RNAi), which is used as a major antiviral mechanism in invertebrates. RNAi activity is detected in wild-type ESCs but is abolished in Dicer knockout ESCs (D-/-ESCs) as expected. Surprisingly, D-/-ESCs have gained the ability …

Tubular J-Aggregates Of Cyanine Dyes In The Near-Infrared, Austin Bailey, Arundhati Deshmukh, Timothy Luke Atallah, Ulugbek Barotov, Monica Pengshung

Faculty Publications

No abstract provided.