Chemistry Commons^™

Electrocatalytic Valorization Of Biomass Intermediates Via 1st-Row Transition Metal Electrocatalysts, Yujie Sun

Funded Research Records

No abstract provided.

Potency And Properties Of Hydrazide Compounds That Inhibit The Growth Of Mycobacterium Tuberculosis, Ronald Bartzatt

Chemistry Faculty Publications

Aims: To examine the properties of hydrazide compounds shown to inhibit Mycobacterium tuberculosis. To identify properties that affect efficiency of bacterial inhibition.

Study Design: Utilizing data from previous studies of compounds that inhibit Mycobacterium tuberculosis, then statistical and pattern recognition methods are applied to identify interrelationships.

Place and Duration of Study: Department of Chemistry, Durham Science Center, University of Nebraska at Omaha, from January 2016 to July 2016.

Methodology: Interrelationships of pharmacological properties were identified by use of various pattern recognition techniques, such as hierarchical cluster analysis and path analysis. Molecular properties and descriptors for all compounds were …

Ph-Dependent Fluorescent Probe That Can Be Tuned For Cysteine Or Homocysteine, Yongkang Yue, Fangjun Huo, Xiaoqi Li, Ying Wen, Tao Yi, James C. Salamanca, Jorge O. Escobedo, Robert Strongin, Caixia Yin

Chemistry Faculty Publications and Presentations

The very close structural similarities between cysteine and homocysteine present a great challenge to achieve their selective detection using regular fluorescent probes, limiting the biological and pathological studies of these two amino thiols. A coumarin-based fluorescent probe was designed featuring pH-promoted distinct turn-on followed by ratiometric fluorescence responses for Cys and turn-on fluorescence response for Hcy through two different reaction paths. These specific responses demonstrate the activity differences between Cys and Hcy qualitatively for the first time. The probe could also be used for Cys and Hcy imaging in living cells.

Myofilament Calcium Sensitivity: Consequences Of The Effective Concentration Of Troponin I, Jalal K. Siddiqui, Svetlana B. Tikunova, Shane D. Walton, Bin Liu, Meredith Meyer, Pieter P. De Tombe, Nathan Neilson, Peter M. Kekenes-Huskey, Hussam E. Salhi, Paul M.L. Janssen, Brandon J. Biesiadecki, Jonathan P. Davis

Chemistry Faculty Publications

Control of calcium binding to and dissociation from cardiac troponin C (TnC) is essential to healthy cardiac muscle contraction/relaxation. There are numerous aberrant post-translational modifications and mutations within a plethora of contractile, and even non-contractile, proteins that appear to imbalance this delicate relationship. The direction and extent of the resulting change in calcium sensitivity is thought to drive the heart toward one type of disease or another. There are a number of molecular mechanisms that may be responsible for the altered calcium binding properties of TnC, potentially the most significant being the ability of the regulatory domain of TnC to …

The Role Of Particle Surface Functionality And Microstructure Development In Isothermal And Non-Isothermal Crystallization Behavior Of Polyamide 6/Cellulose Nanocrystals Nanocomposites, Shahram Rahimi, Joshua U. Otaigbe

Faculty Publications

Polyamide 6 (PA6)/cellulose nanocrystal (CNC) and aminopropyl triethoxy silane (APS) - modified CNC nanocomposites were prepared by in situ anionic ring opening polymerization and subsequent melt extrusion. The morphological observation of these hybrid systems revealed that the non-modified nanocrystals developed a network-like fibrillar structure while the APS-modified CNCs were finely dispersed mostly as individual whiskers. The isothermal and non-isothermal crystallization kinetics was extensively studied with emphasis on the effects of CNC surface functionality and the subsequent microstructure development on crystallization behavior of these novel nanocomposite systems. The non-modified CNC particles with corresponding fibrillar microstructure were found significantly hinder the crystallization …

The Role Of The Unusual Threonine String In The Conversion Of Prion Protein, Romany Abskharon, Fei Wang, Kayla J. Vander Stel, Kumar Sinniah

University Faculty Publications and Creative Works

The conversion of normal prion protein (PrP) into pathogenic PrP conformers is central to prion disease, but the mechanism remains unclear. The α-helix 2 of PrP contains a string of four threonines, which is unusual due to the high propensity of threonine to form β-sheets. This structural feature was proposed as the basis for initiating PrP conversion, but experimental results have been conflicting. We studied the role of the threonine string on PrP conversion by analyzing mouse Prnpa and Prnpb polymorphism that contains a polymorphic residue at the beginning of the threonine string, and PrP mutants in which threonine 191 …

Electropolymerization Of B–Cyclodextrin Onto Multi–Walled Carbon Nanotube Composite Films For Enhanced Selective Detection Of Uric Acid, Mulugeta B. Wayu, Luke T. Dipasquale, Margaret A. Schwarzmann, Samuel D. Gillespie, Michael C. Leopold

Chemistry Faculty Publications

An amperometric uric acid (UA) sensor incorporating a multi-walled carbon nanotubes (MWCNT) network in Nafion and electropolymerized β-cyclodextrin (β-CD) layer is investigated. The electrochemical sensor is comprised of a glassy carbon electrode modified with Nafion-MWCNT nanocomposite film, a β-CD polymer inner selective layer, and a Hydrothane polyurethane (HPU) outer selective coating. The surface morphology and electronic structure of the electrode material are characterized using transmission electron microscopy (TEM), scanning electron microscope (SEM), and Fourier transform infrared (FTIR) spectroscopy. The electrocatalytic activity of the sensor is studied using cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Analytical performance of …

Vitamin E Circular Dichroism Studies: Insights Into Conformational Changes Induced By The Solvent’S Polarity, Drew Marquardt, Brad J. Van Oosten, Mikel Ghelfi, Jeffrey Atkinson, Thad A. Harroun

Chemistry and Biochemistry Publications

We used circular dichroism (CD) to study differences in CD spectra between α-, δ-, and methylated-α-tocopherol in solvents with different polarities. CD spectra of the different tocopherol structures differ from each other in intensity and peak locations, which can be attributed to chromanol substitution and the ability to form hydrogen bonds. In addition, each structure was examined in different polarity solvents using the Reichardt index—a measure of the solvent’s ionizing ability, and a direct measurement of solvent–solute interactions. Differences across solvents indicate that hydrogen bonding is a key contributor to CD spectra at 200 nm. These results are a first …

End-Capping Strategies For Triggering End-To-End Depolymerization Of Polyglyoxylates, Bo Fan, John Trant, Elizabeth Gillies

Chemistry Publications

Polymers that undergo end-to-end depolymerization in response to the cleavage of a stimuli-responsive end-cap are promising for diverse applications from drug delivery to responsive coatings and plastics. It is critical that the end-cap is designed to respond to an appropriate stimulus for the application. In the current work, end-caps for triggering the depolymerization of poly(ethyl glyoxylate) (PEtG) were explored. First, a phenylboronate, a disulfi de, and an azobenzene were utilized to impart redox-responsive properties to PEtG. Then, methoxy-substituted trityl groups were used to provide sensitivity to mild acid. A multiresponsive platform was also introduced, allowing PEtG to respond to multiple …

In-Class Versus At-Home Quizzes: Which Is Better? A Flipped Learning Study In A Two-Site Synchronously-Broadcast Organic Chemistry Course, Michael A. Christensen, Alyssia M. Lambert, Louis S. Nadelson, Kami M. Dupree, Trish A. Kingsford

Chemistry and Biochemistry Faculty Publications

We recently shared our design of a two-semester flipped organic chemistry course, in which we gave students in-class quizzes to incentivize attendance and watching the lecture videos in advance. With a second iteration, we planned to make the video-watching experience more engaging. We accordingly hypothesized that if students completed short at-home quizzes while watching the videos, then attentiveness, engagement, and learning would increase. We tested this with a later section of the course, dividing the material into 13 units. For units 1-6, we gave in-class quizzes; for 7-13, quizzes were at home. Although units 1-6 and 7-13 covered different material, …

Phthalate Plasticizers Covalently Linked To Pvc Via Copper-Free Or Copper Catalyzed Axide-Alkyne Cycloadditions, Aruna Earla, Li Longbo, Philip Costanzo, Rebecca Braslau

Chemistry and Biochemistry

Plasticization of PVC was carried out by covalently linking phthalate derivatives via copper-free (thermal) or copper catalyzed azide-alkyne cycloadditions. Di(2-ethylhexyl) phthalate derivatives (DEHP-ether and DEHP-ester) were synthesized and appended to PVC at two different densities. The glass transition temperatures of the modified PVC decreased with increasing content of plasticizer. PVC-DEHP-ether gave lower glass transition temperatures than PVC-DEHP-ester, reflecting the enhanced flexibility of the ether versus ester linker.

The Effect Of Mo Doping On The Charge Separation Dynamics And Photocurrent Performance Of Bivo4 Photoanodes, Brian Pattengale, Jier Huang

Chemistry Faculty Research and Publications

Doping with electron-rich elements in BiVO₄ photoanodes has been demonstrated as a desirable approach for improving their carrier mobility and charge separation efficiency. However, the effect of doping and dopant concentration on the carrier dynamics and photoelectrochemical performance remains unclear. In this work, we examined the effects of Mo doping on the charge separation dynamics and photocurrent performance in BiVO₄photoanodes. We show that the photocurrent of BiVO₄ photoanodes increases with increasing concentration of the Mo dopant, which can be attributed to both the improved carrier mobility resulting from increased electron density and charge separation efficiency due …

Over Or Under: Hydride Attack At The Metal Versus The Coordinated Nitrosyl Ligand In Ferric Nitrosyl Porphyrins., E G. Abucayon, R L. Khade, D R. Powell, Michael J. Shaw, Y Yang, G B. Richter-Addo

SIUE Faculty Research, Scholarship, and Creative Activity

Hydride attack at a ferric heme–NO to give an Fe–HNO intermediate is a key step in the global N--‐cycle. We demonstrate differential reactivity when six--‐ and five--‐coordinate ferric heme--‐NO models react with hydride. Although Fe–HNO formation is thermodynamically favored from this reaction, Fe–H formation is kinetically favored for the 5C case.

Design And Synthesis Of Novel Azasteroids And Pseudoazulenyl Nitrones, Nagaraju Birudukota

FIU Electronic Theses and Dissertations

Steroids are one of the essential classes of bioactive compounds and are involved in many biological functions which include their role as signaling compounds, the alteration of membrane fluidity and the regulation of a variety of metabolic processes. In order to identify novel compounds with beneficial pharmacological action, the synthesis of modified steroids is gaining much attention in recent years. Among those analogs, azasteroids are one of the most important classes which display a variety of biological activities, often free from undesirable side effects. The challenges in the synthesis of steroids, particularly azasteroids, and the potential of azasteroids as novel …

An Examination Of Student Outcomes In Studio Chemistry, Alan L. Kiste, Gregory E. Scott, Jesse Paul Bukenberger, Miles Markmann, Jennifer Moore

Chemistry and Biochemistry

Twenty years ago, a major curriculum revision at a large, comprehensive university in the Western United States led to the implementation of an integrated lecture/laboratory (studio) experience for our engineering students taking general chemistry. Based on these twenty years of experience, construction of four purpose-built studio classrooms to house the majority of the remaining general chemistry courses was completed in 2013. A detailed study of the effects of the entire ecology of the studio experience on student success was initiated at that time. Data from content knowledge pre- and post-tests, learning attitudes surveys, and student course evaluations show positive effects …

A Grand Unified Model For Liganded Gold Clusters, Wen Wu Xu, Beien Zhu, Xiao Cheng Zeng, Yi Gao

Xiao Cheng Zeng Publications

A grand unified model (GUM) is developed to achieve fundamental understanding of rich structures of all 71 liganded gold clusters reported to date. Inspired by the quark model by which composite particles (for example, protons and neutrons) are formed by combining three quarks (or flavours), here gold atoms are assigned three ‘flavours’ (namely, bottom, middle and top) to represent three possible valence states. The ‘composite particles’ in GUM are categorized into two groups: variants of triangular elementary block Au₃(2e) and tetrahedral elementary block Au₄(2e), all satisfying the duet rule (2e) of the valence shell, akin to …

Secondary Structure Adopted By The Gly-Gly-X Repetitive Regions Of Dragline Spider Silk, Geoffrey M Gray, Arjan Van Der Vaart, Chengchen Guo, Justin Jones, David Onofrei, Brian R Cherry, Randolph V Lewis, Jeffery L Yarger, Gregory P Holland

Chemistry Faculty Publications

Solid-state NMR and molecular dynamics (MD) simulations are presented to help elucidate the molecular secondary structure of poly(Gly-Gly-X), which is one of the most common structural repetitive motifs found in orb-weaving dragline spider silk proteins. The combination of NMR and computational experiments provides insight into the molecular secondary structure of poly(Gly-Gly-X) segments and provides further support that these regions are disordered and primarily non-β-sheet. Furthermore, the combination of NMR and MD simulations illustrate the possibility for several secondary structural elements in the poly(Gly-Gly-X) regions of dragline silks, including β-turns, 3

Fluorine Atom Influence On Intramolecular Hydrogen Bonding, Isomerization And Methyl Group Rotation In Fluorinated Acetylacetones, Brett De Vries, Mark Muyskens

University Faculty Publications and Creative Works

1-Fluoro-pentane-2,4-dione (monofluoroacetylacetone, MFAA) is an asymmetric β-diketone with a strong intramolecular hydrogen bond similar to acetylacetone (AA) and its fluorinated analogs 1,1,1-trifluoro-(TFAA), and 1,1,1,5,5,5-hexafluoroacetylacetone (HFAA). The presence of a fluorine atom in MFAA has the potential to open an HF elimination channel in its gas-phase photochemistry motivating this study of MFAA hydrogen bonding by computer modeling using Density Functional Theory (DFT). As a context, we also report DFT modeling of AA and selected fluorinated acetylacetones: 1,1-difluoro-pentane-2,4-dione (difluoroacetylacetone, DFAA), TFAA, and HFAA. The most stable molecular structure for all three asymmetric β-diketones (MFAA, DFAA and TFAA) is the isomer with the …

A Non-Traditional Approach To Synthesizing Aryl Vinyl Sulfides Is Described. 2,2-Diphenyl-1,3-Oxathiolane Slowly Liberates Vinyl Sulfide Anion Under Basic Conditions. Using A Pd/Xantphos Catalyst System To Activate A Wide Range Of Aryl Bromides, This Transient Sulfide Species Can Be Effectively Trapped And Fed Into A Traditional Pd0/Pdii Catalytic Cycle. Scope And Limitations Of The Methodology Are Presented Along With Significant Discussion Of A Competitive C–S Bond Activation By This Catalyst System., Jason R. Schmink, Summer A. Baker Dockrey, Tianyi Zhang, Naomi Chebet, Alexis Van Venrooy, Mary Sexton, Sarah I. Lew, Steffany Chou, Ami Okazaki

Chemistry Faculty Research and Scholarship

A non-traditional approach to synthesizing aryl vinyl sulfides is described. 2,2-diphenyl-1,3-oxathiolane slowly liberates vinyl sulfide anion under basic conditions. Using a Pd/Xantphos catalyst system to activate a wide range of aryl bromides, this transient sulfide species can be effectively trapped and fed into a traditional Pd⁰/Pd^II catalytic cycle. Scope and limitations of the methodology are presented along with significant discussion of a competitive C–S bond activation by this catalyst system.

Cucurbit[7]Uril-Tetramethylrhodamine Conjugate For Direct Sensing And Cellular Imaging, Andrew T. Bockus, Lauren C. Smith, Amy G. Grice, Omar A. Ali, Carolyn C. Young, William Mobley, Ashley Leek, James Lewis Roberts, Brittany Vinciguerra, Lyle D. Isaacs, Adam R. Urbach

Chemistry Faculty Research

This paper describes the design and synthesis of a conjugate (Q7R) comprising the synthetic host cucurbit[7]uril (Q7) linked to the fluorescent dye tetramethylrhodamine (TMR), and the characterization of its optical and guest-binding properties as well as its cellular uptake. Q7R was synthesized in two steps from monofunctionalized azidobutyl-Q7 and NHS-activated TMR. The fluorescence of Q7R is quenched upon guest binding, and this observable was used to determine equilibrium dissociation constant (K_d) values. Unexpectedly, the K_d values for guests binding to Q7R and to unmodified Q7 were essentially identical. Therefore, Q7R can directly report binding to Q7 without …

Food And Energy For All, Bradley Stevens, Stephen Rybczynski, Deborah Herrington

Peer Reviewed Articles

When asked what plants need for photosynthesis, many students can correctly recall the reaction equation and state that plants require CO2, H2O, and light. Many students, however, do not understand that these reactants are the raw materials plants use to make sugars and instead believe that they are food for plants. Moreover, when questioned further, students often voice the idea that plants get their food from the soil (Kestler 2014). This is consistent with findings that fewer than half of current middle and high school students have a correct understanding of the process of photosynthesis (AAAS 2015). We developed this …

Enhancements In Localized Classification For Uterine Cervical Cancer Digital Histology Image Assessment, Peng Guo, Haidar A. Almubarak, Koyel Banerjee, R. Joe Stanley, L. Rodney Long, Sameer K. Antani, George R. Thoma, Rosemary E. Zuna, Shelliane R. Frazier, Randy Hays Moss, William V. Stoecker

Electrical and Computer Engineering Faculty Research & Creative Works

Background: In previous research, we introduced an automated, localized, fusion-based approach for classifying uterine cervix squamous epithelium into Normal, CIN1, CIN2, and CIN3 grades of cervical intraepithelial neoplasia (CIN) based on digitized histology image analysis. As part of the CIN assessment process, acellular and atypical cell concentration features were computed from vertical segment partitions of the epithelium region to quantize the relative distribution of nuclei.

Methods: Feature data was extracted from 610 individual segments from 61 images for epithelium classification into categories of Normal, CIN1, CIN2, and CIN3. The classification results were compared against CIN labels obtained from two pathologists …

A Pes Study Of Factors Influencing Metal Partitioning In Aquatic Systems: “Design Of Experiment As, Cd, Co, Cr, Cu, Pb, Ni, And Zn”, Eid A. Alkhatib, John Rapaglia, Leon Theim

Chemistry & Physics Faculty Publications

Mobility and bioavailability of heavy metals are related to their partitioning amongst suspended sediment and water. A Particle Entrainment Simulator (PES) is used to simulate sediment resuspention in natural surface water systems. The simulations were carried out under various conditions of water/suspended solids conditions. Five factors, each at various levels, are tested collectively: the pH of water at two levels (4 and 8), shear stress on bottom sediment at three levels (0.1, 0.3, and 0.5 N/m2 ) salinity of water at two levels (0.01 and 14.0 ppt), organic matter in sediment at three levels (0.50, 1.93, and 3.80%) and temperature …

Persistent Organic Chemicals In The Pacific Basin Countries: An Overview, Bommanna G. Loganathan

Faculty & Staff Research and Creative Activity

The Pacific Basin is a unique geographical region representing tropical, temperate and polar zones. This region is home to 2/3 of world’s population and consists of rapidly growing economies (countries) and highly developed countries. The Pacific Basin countries have had a history of use of persistent organic chemicals (POCs) at varying proportions during the last five decades. Due to diverse climatic and socio-economic conditions, the environment and biota in different countries in this basin have varying degrees of environmental contamination and effects on wildlife and humans. In this chapter, the historical background of POCs including, discovery, production, use, regulations/restrictions imposed, …

Environmental Emission Of Pharmaceuticals From Wastewater Treatment Plants In The Usa, Bikram Subedi, Bommanna G. Loganathan

Faculty & Staff Research and Creative Activity

The residual drugs, drug bioconjugates, and their metabolites, mostly from human and veterinary usage, are routinely flushed down the drain, and enter wastewater treatment plants (WWTP). Increasing population, excessive use of allopathic medicine, continual introduction of novel drugs, and existing inefficient wastewater treatment processes result in the discharge of large volumes of pharmaceuticals and their metabolites from the WWTPs into the environment. The effluent from the WWTPs globally contaminate ~25% of rivers and the lakes. Pharmaceuticals in the environment, as contaminants of emerging concerns, behave as pseudo-persistent despite their relatively short environmental half-lives in the environment. Therefore, residual levels of …

Subtractive Methods To Form Pyrite And Sulfide Nanostructures Of Fe, Co, Ni, Cu And Zn, Kurt W. Kolasinski

Chemistry Faculty Publications

The low Z metals Fe, Co, Ni, Cu and Zn are Earth abundant, i.e. inexpensive, and their sulfides are of low toxicity. This makes them appealing candidates for materials applications requiring semiconductors or, in the case of CoS₂, a metal since they can potentially be produced in large quantities and low cost. Though of great potential little work has explored how subtractive methods can be used to form nanostructured and/or porous structures in, e.g. FeS₂, CoS₂, NiS, Cu₂S and ZnS.

Characterization Of Wy 14,643 And Its Complex With Aldose Reductase, Michael Sawaya, Malkhey Verma, Vaishnavi Balendiran, Nigam Rath, Duilio Cascio, Ganesaratnam Balendiran

Chemistry & Biochemistry Faculty Works

The peroxisome proliferator, WY 14,643 exhibits a pure non-competitive inhibition pattern in the aldehyde reduction and in alcohol oxidation activities of human Aldose reductase (hAR). Fluorescence emission measurements of the equilibrium dissociation constants, Kd, of oxidized (hAR•NADP+) and reduced (hAR•NADPH) holoenzyme complexes display a 2-fold difference between them. Kd values for the dissociation of WY 14,643 from the oxidized (hAR•NADP+•WY 14,643) and reduced (hAR•NADPH•WY 14,643) ternary complexes are comparable to each other. The ternary complex structure of hAR•NADP+•WY 14,643 reveals the first structural evidence of a fibrate class drug binding to hAR. These observations demonstrate how fibrate molecules such as …

Design And Synthesis Of Novel Octacarboxy Porphyrinic Metal-Organic Frameworks, Jacob A. Johnson

Department of Chemistry: Dissertations, Theses, and Student Research

Metal-Organic Frameworks (MOFs) are a class of nanoporous crystalline materials constructed via the interconnection between metal-ions/inorganic clusters and organic ligands. Since the surface area, pore size and distribution, and chemical functionalities of MOFs are highly tunable via the judicious combinations of inorganic clusters and organic ligands, MOFs have attracted intensive interests for a variety of applications including gas adsorption and separation, catalysis, chemical sensing, and drug delivery among others. Porphyrin based ligands are of particular interest for building functional MOFs due to their unique photo-, electro-, and catalytic properties. In addition, the four-fold symmetry of porphyrin ligands offers an effective …

Glutathione Species And Metabolomic Prints In Subjects With Liver Disease As Biological Markers For The Detection Of Hepatocellular Carcinoma, Juan R. Sanabria, Rajan S. Kombu, Guo Fang Zhang, Yana Sandlers, Jizhou Ai, Rafael A. Ibarra, Rime Abbas, Kush Goyal, Henri Brunengraber

Chemistry Faculty Publications

© 2016 The Authors Background The incidence of liver disease is increasing in USA. Animal models had shown glutathione species in plasma reflects liver glutathione state and it could be a surrogate for the detection of hepatocellular carcinoma (HCC). Methods The present study aimed to translate methods to the human and to explore the role of glutathione/metabolic prints in the progression of liver dysfunction and in the detection of HCC. Treated plasma from healthy subjects (n = 20), patients with liver disease (ESLD, n = 99) and patients after transplantation (LTx, n = 7) were analyzed by GC- or LC/MS. …

Relation Of Serum Estrogen Metabolites With Terminal Duct Lobular Unit Involution Among Women Undergoing Diagnostic Image-Guided Breast Biopsy., Hannah Oh, Zeina G Khodr, Mark E Sherman, Maya Palakal, Ruth M Pfeiffer, Laura Linville, Berta M Geller, Pamela M Vacek, Donald L Weaver, Rachael E Chicoine, Roni T Falk, Hisani N Horne, Daphne Papathomas, Deesha A Patel, Jackie Xiang, Xia Xu, Timothy Veenstra, Stephen M Hewitt, John A Shepherd, Louise A Brinton, Jonine D Figueroa, Gretchen L Gierach

Pharmaceutical Sciences Faculty Publications

Higher levels of circulating estrogens and estrogen metabolites (EMs) have been associated with higher breast cancer risk. In breast tissues, reduced levels of terminal duct lobular unit (TDLU) involution, as reflected by higher numbers of TDLUs and acini per TDLU, have also been linked to elevated breast cancer risk. However, it is unknown whether reduced TDLU involution mediates the risk associated with circulating EMs. In a cross-sectional analysis of 94 premenopausal and 92 postmenopausal women referred for clinical breast biopsy at an academic facility in Vermont, we examined the associations of 15 EMs, quantified using liquid chromatography-tandem mass spectrometry, with …