Chemistry Commons^™

Polymorphism And Polyamorphism In Bilayer Water Confined To Slit Nanopore Under High Pressure, Jaeil Bai, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

A distinctive physical property of bulk water is its rich solid-state phase behavior, which includes 15 crystalline (ice I–ice XIV) and at least 3 glassy forms ofwater, namely, low-density amorphous, highdensity amorphous, and very-high-density amorphous (VHDA). Nanoscale confinement adds a new physical variable that can result in a wealth of new quasi-2D phases of ice and amorphous ice. Previous computer simulations have revealed that when water is confined between two flat hydrophobic plates about 7–9 Å apart, numerous bilayer (BL) ices (or polymorphs) can arise [e.g., BL-hexagonal ice (BL-ice I)]. Indeed, growth of the BL-ice I through vapor deposition on …

Progress Toward Red And Near-Infrared (Nir) Emitting Saccharide Sensors, Martha Sibrian-Vazquez, Jorge O. Escobedo, Mark Lowry, Robert M. Strongin

Chemistry Faculty Publications and Presentations

Red-shifted and near-infrared (NIR)-active rhodamine analogs and their boronic acid derivatives were synthesized and studied. These latter compounds function as fluorogenic NIR active substrates for sugar sensing. The effects of benzannulation and boronic acid functionalization on fluorophore optical and sensing properties are described.

Phoenix Mars Mission Wet Chemistry Laboratory Detection Limit Of Martian Soil Oxidants, Lauren B. Petersen, Richard C. Quinn Dr.

STAR Program Research Presentations

This project utilizes the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) Wet Chemistry Laboratory Testbed (WCL), a payload component of the NASA Phoenix Mars Mission, to analyze Mars soil analogs to find the limits of detection for various compounds of interest- including peroxides, chlorates, sulfates, and other oxidants. When the Phoenix Rover landed in the northern plains of Mars in the summer of 2008, three soil samples were analyzed for soluble components. In this analysis, large amounts of perchlorate were detected. Now, we are relooking at the Phoenix data to see if it shows evidence of other oxidants. The electrochemical techniques …

En Route Towards Α-Benzotriazoyl Nitroso Derivatives, Jean-Christophe M. Monbaliu, Lucas K. Beagle, Judit K. Beagle, Matthias Zeller, Christian V. Stevens, Alan R. Katritzky

Chemistry Faculty Publications

A new class of geminally-substituted nitroso compounds, i.e., α-benzotriazoyl nitroso derivatives, is presented. These compounds display a rather different behavior than other related nitroso compounds bearing a geminal electron-withdrawing group. An unexpected and spontaneous oxidation to the nitro analog is observed in solution.

Synthesis And Characterization Of Graphene Oxide, Jeremy A. Waddell, Arthur Cheng, Bin Chen

STAR Program Research Presentations

Graphene, a single atomic layer of sp² carbon atoms, has gotten a lot of attention from the scientific community because of its excellent mechanical and electronic properties. The mechanical exfoliation methods used to obtain graphene nanosheets are not effective for large scale manufacturing, so scalable synthesis approaches from structurally similar compounds are of great scientific interest. Graphene oxide is one such compound which is synthesized through the oxidation of graphite powder. The oxidation was performed using a modification of the previous experimental procedure. After synthesis, the powder was fabricated into graphene oxide films through vacuum filtration and transfer to …

Long-Range Ordered Carbon Clusters: A Crystalline Material With Amorphous Building Blocks, Lin Wang, Bingbing Liu, Hui Li, Wenge Yang, Yang Ding, Stanislav V. Sinogeikin, Yue Meng, Zhenxian Liu, Xiao Cheng Zeng, Wendy L. Mao

Xiao Cheng Zeng Publications

Solid-state materials can be categorized by their structures into crystalline (having periodic translation symmetry), amorphous (no periodic and orientational symmetry), and quasi-crystalline (having orientational but not periodic translation symmetry) phases. Hybridization of crystalline and amorphous structures at the atomic level has not been experimentally observed. We report the discovery of a long-range ordered material constructed from units of amorphous carbon clusters that was synthesized by compressing solvated fullerenes. Using x-ray diffraction, Raman spectroscopy, and quantum molecular dynamics simulation, we observed that, although carbon-60 cages were crushed and became amorphous, the solvent molecules remained intact, playing a crucial role in maintaining …

Reactions Of Methyl Perfluoroalkyl Ethers With Isopropyl Alcohol: Experimental And Theoretical Studies, Howard Knachel, Vladimir Benin, Chadwick Barklay, Janine C. Birkbeck, Billy D. Faubion, William E. Moddeman

Chemistry Faculty Publications

The reaction of an isomeric mixture of the methyl perfluoroalkyl ether, C4F9OCH3 (Novec-7100), in the presence of isopropyl alcohol (IPA) and/or water has been studied by measuring the rate of product formation using an ion-selective electrode (ISE) for fluoride ion, Karl Fisher coulometric titrations for water, and 1H and 19F NMR spectroscopy for product identification and rate studies. The results showed the methyl perfluoroalkyl ether to be very stable with products forming at the rate of ∼1 ppm per year at a laboratory temperature of 20 °C. Measurements over the temperature range of 6° to 100 °C were made on …

Development And Validation Of An Lc–Ms/Ms Method For Pharmacokinetic Study Of Methoxyamine In Phase I Clinical Trial, Shuming Yang, Panayiotis Savvides, Lili Liu, Stanton L. Gerson, Yan Xu

Chemistry Faculty Publications

Methoxyamine (MX) is the first DNA base-excision-repair (BER) inhibitor evaluated in humans. This work described the development and validation of an LC–MS/MS method for quantitative determination of MX in human plasma. In this method, MX and its stable isotope methoxyl-d3-amine (MX-d3 as internal standard) were directly derivatized in human plasma with 4-(N,N-diethylamino)benzaldehyde. The derivatized MX and IS were extracted by methyl-tert-butyl ether, and separated isocratically on a Xterra C18 column (2.1 mm × 100 mm) using an aqueous mobile phase containing 45% acetonitrile and 0.4% formic acid at a flow rate of 0.200 ml/min. Quantitation of MX was carried out …

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Analysis Of Lower Pecos Rock Paints And Possible Pigment Sources, Jon Russ, Kaixuan Bu, Jeff Hamrick, James V. Cizdziel

Master of Science in Analytics (MSAN) Faculty Research

Chemical analyses of prehistoric rock paints from the Lower Pecos Region of southwestern Texas were undertaken using laser ablation-inductively coupled plasma-mass spectrometry. This technique allowed us to measure the chemical composition of the paint pigments with minimal interference from a natural rock coating that completely covers the ancient paints. We also analyzed samples representing potential sources of paint pigments, including iron-rich sandstones and quartzite from the study area and ten ochre samples from Arizona. Cluster analysis, principle component analysis and bivariate plots were used to compare the chemical compositions of the paint and pigment sources. The results indicate that limonite …

Concentration Effects And Ion Properties Controlling The Fractionation Of Halides During Aerosol Formation, Marcelo I. Guzman, Richa R. Athalye, Jose M. Rodriguez

Chemistry Faculty Publications

During the aerosolization process at the sea surface, halides are incorporated into aerosol droplets, where they may play an important role in tropospheric ozone chemistry. Although this process may significantly contribute to the formation of reactive gas phase molecular halogens, little is known about the environmental factors that control how halides selectively accumulate at the air-water interface. In this study, the production of sea spray aerosol is simulated using electrospray ionization (ESI) of 100 nM equimolar solutions of NaCl, NaBr, NaI, NaNO(2), NaNO(3), NaClO(4), and NaIO(4). The microdroplets generated are analyzed by mass spectrometry to study the comparative enrichment of …

The Analysis Of Protein-Bound Thiocyanate In Plasma Of Smokers And Non-Smokers As A Marker Of Cyanide Exposure, Stephanie L. Youso, Gary A. Rockwood, Brian A. Logue

Chemistry and Biochemistry Faculty Publications

When cyanide is introduced into the body, it quickly transforms through a variety of chemical reactions, normally involving sulfur donors, to form more stable chemical species. Depending on the nature of the sulfur donor, cyanide may be transformed into free thiocyanate, the major metabolite of cyanide transformation, 2-amino-2-thiazoline-4-carboxylic acid or protein-bound thiocyanate (PB-SCN) adducts. Because protein adducts are generally stable in biological systems, it has been suggested that PB-SCN may have distinct advantages as a marker of cyanide exposure. In this study, plasma was analyzed from 25 smokers (chronic low-level cyanide exposure group) and 25 non-smokers for PB-SCN. The amount …

Identification And Analysis Of Stereoselective Drug Interactions With Low Density Lipoprotein By High-Performance Affinity Chromatography, Matt Sobansky, David S. Hage

Chemistry Department: Faculty Publications

Columns containing immobilized low density lipoprotein (LDL) were prepared for the analysis of drug interactions with this agent by high-performance affinity chromatography (HPAC). R/SPropranolol was used as a model drug for this study. The LDL columns gave reproducible binding to propranolol over 60 h of continuous use in the presence of pH 7.4, 0.067 M potassium phosphate buffer. Experiments conducted with this type of column through frontal analysis indicated that two types of interactions were occurring between R-propranolol and LDL, while only a single type of interaction was observed between S-propranolol and LDL. The first type …

K-Shell X-Ray Spectroscopy Of Atomic Nitrogen, M. M. Sant'anna, Gunnar Ohrwall, Wayne C. Stolte, Alfred S. Schlachter, Dennis W. Lindle, B. M. Mclaughlin

Chemistry and Biochemistry Faculty Research

Absolute K-shell photoionization cross sections for atomic nitrogen have been obtained from both experiment and state-of-the-art theoretical techniques. Because of the difficulty of creating a target of neutral atomic nitrogen, no high-resolution K-edge spectroscopy measurements have been reported for this important atom. Interplay between theory and experiment enabled identification and characterization of the strong 1s → np resonance features throughout the threshold region. An experimental value of 409.64 ± 0.02 eV was determined for the K-shell binding energy.

Preparation And Rapid Analysis Of Antibacterial Silver, Copper And Zinc Doped Sol–Gel Surfaces, Brendan Duffy, Swarna Jaiswal, Patrick Mchale

Articles

The colonisation of clinical and industrial surfaces with microorganisms, including antibiotic-resistant strains, has promoted increased research into the development of effective antibacterial and antifouling coatings. This study describes the preparation of metal nitrate (Ag, Cu, Zn) doped methyltriethoxysilane (MTEOS) coatings and the rapid assessment of their antibacterial activity using polyproylene microtitre plates. Microtitre plate wells were coated with different volumes of liquid sol–gel and cured under various conditions. Curing parameters were analysed by thermogravimetric analysis (TGA) and visual examination. The optimum curing conditions were determined to be 50–70C using a volume of 200ul. The coated wells were challenged with Gram-positive …

Unusual Activities Of The Thioesterase Domain For The Biosynthesis Of The Polycyclic Tetramate Macrolactam Hsaf In Lysobacter Enzymogenes C3, Lili Lou, Haotong Chen, Ronald Cerny, Yaoyao Li, Yuemao Shen, Liangcheng Du

Ronald Cerny Publications

HSAF is an antifungal natural product with a new mode of action. A rare bacterial iterative PKSNRPS assembles the HSAF skeleton. The biochemical characterization of the NRPS revealed that the thioesterase (TE) domain possesses the activities of both a protease and a peptide ligase. Active site mutagenesis, circular dichroism spectra and homology modeling of the TE structure suggested that the TE may possess uncommon features that may lead to the unusual activities. The iterative PKS-NRPS is found in all polycyclic tetramate macrolactam gene clusters, and the unusual activities of the TE may be common to this type of hybrid PKS-NRPS.

Self-Assembling Subnanometer Pores With Unusual Mass-Transport Properties, Xibin Zhou, Guande Liu, Kazuhiro Yamato, Yi Shen, Ruixian Cheng, Xiaoxi Wei, Wanli Bai, Yi Gao, Hui Li, Yi Liu, Futao Liu, Daniel M. Czajkowsky, Jingfang Wang, Michael J. Dabney, Zhonghou Cai, Jun Hu, Frank V. Bright, Lan He, Xiao Cheng Zeng, Zhifeng Shao, Bing Gong

Xiao Cheng Zeng Publications

A long-standing aim in molecular self-assembly is the development of synthetic nanopores capable of mimicking the mass-transport characteristics of biological channels and pores. Here we report a strategy for enforcing the nanotubular assembly of rigid macrocycles in both the solid state and solution based on the interplay of multiple hydrogen-bonding and aromatic π − π stacking interactions. The resultant nanotubes have modifiable surfaces and inner pores of a uniform diameter defined by the constituent macrocycles. The self-assembling hydrophobic nanopores can mediate not only highly selective transmembrane ion transport, unprecedented for a synthetic nanopore, but also highly efficient transmembrane water permeability. …

Ccpa Regulates Arginine Biosynthesis In Staphylococcus Aureus Through Repression Of Proline Catabolism, Austin S. Nuxoll, Steven M. Halouska, Marat R. Sadykov, Mark L. Hanke, Kenneth W. Bayles, Tammy Kielian, Robert Powers, Paul D. Fey

Chemistry Department: Faculty Publications

Staphylococcus aureus is a leading cause of community-associated and nosocomial infections. Imperative to the success of S. aureus is the ability to adapt and utilize nutrients that are readily available. Genomic sequencing suggests that S. aureus has the genes required for synthesis of all twenty amino acids. However, in vitro experimentation demonstrates that staphylococci have multiple amino acid auxotrophies, including arginine. Although S. aureus possesses the highly conserved anabolic pathway that synthesizes arginine via glutamate, we demonstrate here that inactivation of ccpA facilitates the synthesis of arginine via the urea cycle utilizing proline as a substrate. Mutations within putA, rocD, …

Crystalline Nano Structures, Barry Chin Li Cheung, Joseph Reese Brewer, Nirmalendu Deo

Chemistry Department: Faculty Publications

The present invention comprises nano obelisks and nanostructures and methods and processes for same. The nano obelisks of the present invention are advantageous structures for use as electron source emitters. For example, the ultra sharp obelisks can be used as an emitter source to generate highly coherent and high energy electrons with high current.

In-Use Measurement Of Locomotive Emissions, Matt Breuer

Summer Research

The Environmental Protection Agency’s newest emissions standards set into law in 2004, which took effect in 2010, limited the level of emissions that locomotives are allowed to produce. For the most part, these standards have been verified in the laboratory and not while the locomotives were in actual use. My research looked at the emissions from these locomotives in-use, under normal operating conditions. The measurements took place on two Pierce County bridges that are above operating train tracks. A remote sensing device (the FEAT) was used to look at locomotive emissions of CO, HC, NO, NO_2, SO₂, …

Unraveling The Structural Complexity In A Single-Stranded Rna Tail: Implications For Efficient Ligand Binding In The Prequeuosine Riboswitch, Catherine D. Eichhorn, Jun Feng, Krishna C. Suddala, Nils G. Walter, Charles L. Brooks Iii, Hashim M. Al-Hashimi

Chemistry Department: Faculty Publications

Single-stranded RNAs (ssRNAs) are ubiquitous RNA elements that serve diverse functional roles. Much of our understanding of ssRNA conformational behavior is limited to structures in which ssRNA directly engages in tertiary interactions or is recognized by proteins. Little is known about the structural and dynamic behavior of free ssRNAs at atomic resolution. Here, we report the collaborative application of nuclear magnetic resonance (NMR) and replica exchange molecular dynamics (REMD) simulations to characterize the 12 nt ssRNA tail derived from the prequeuosine riboswitch. NMR carbon spin relaxation data and residual dipolar coupling measurements reveal a flexible yet stacked core adopting an …

Behavioral And Chemical Analysis Of Deposited Chemical Cues In Striped Plateau Lizards, Jay Goldberg

Summer Research

Many pheromones are produced by glands and deposited on substrates throughout the environment. Lizards possess an array of glands that secrete chemical cue. During mating seasons the glandular secretions of many lizards contain elevated levels of lipophilic compounds including: free-fatty acids, sterols, and long-chain fatty alcohols. This study examines the effect of season and hydrophobicity of chemicals on male response to female deposited chemical cues in the Striped Plateau Lizard (Sceloporous virgatus). Cues were collected and then scraped into a vial containing hexane and water in order to separate hydrophilic and lipophilic molecules. Chemical cue fractions were then …

Ƴ-Selective Directed Catalytic Asymmetric Hydroboration Of 1,1-Disubstituted Alkenes, Sean M Smith, Gia L. Hoang, Rhitankar Pal, Mohammad O. Bani Khaled, Liberty S. W. Pelter, Xiao Cheng Zeng, James M. Takacs

Xiao Cheng Zeng Publications

Directed catalytic asymmetric hydroborations of 1,1-disubstituted alkenes afford ƴ

-dioxaborato amides and esters in high enantiomeric purity (90–95% ee).

Quantitative Analysis Of Some Important Metals And Metalloids In Tobacco Products By Inductively Coupled Plasma-Mass Spectrometry (Icp-Ms), Syed Ghulam Musharraf, Muhammad Shoaib, Amna Jabbar Siddiqui, Muhammad Najam-Ul-Haq, Aftab Ahmed

Pharmacy Faculty Articles and Research

Background: Large scale usage of tobacco causes a lot of health troubles in human. Various formulations of tobacco are extensively used by the people particularly in developing world. Besides several toxic tobacco constituents some metals and metalloids are also believed to pose health risks. This paper describes inductively coupled plasma-mass spectrometric (ICP-MS) quantification of some important metals and metalloids in various brands of smoked, sniffed, dipped and chewed tobacco products.

Results: A microwave-assisted digestion method was used for sample preparation. The method was validated by analyzing a certified reference material. Percentage relative standard deviation (% R.S.D.) between recovered …

Dynamic Light Scattering And Microelectrophoresis: Main Prospects And Limitations, Vuk Uskoković

Pharmacy Faculty Articles and Research

Microelectrophoresis based on the dynamic light scattering (DLS) effect has been a major tool for assessing and controlling the conditions for stability of colloidal systems. However, both the DLS methods for characterization of the hydrodynamic size of dispersed submicron particles and the theory behind the electrokinetic phenomena are associated with fundamental and practical approximations that limit their sensitivity and information output. Some of these fundamental limitations, including the spherical approximation of DLS measurements and an inability of microelectrophoretic analyses of colloidal systems to detect discrete charges and differ between differently charged particle surfaces due to rotational diffusion and particle orientation …

Features For Non-Targeted Cross-Sample Analysis With Comprehensive Two-Dimensional Chromatography, Stephen E. Reichenbach, Xue Tian, Chiara Cordero, Qingping Tao

School of Computing: Faculty Publications

This review surveys different approaches for generating features from comprehensive two-dimensional chromatography for non-targeted cross-sample analysis. The goal of non-targeted cross-sample analysis is to discover relevant chemical characteristics (such as compositional similarities or differences) from multiple samples. In non-targeted analysis, the relevant characteristics are unknown, so individual features for all chemical constituents should be analyzed, not just those for targeted or selected analytes. Cross-sample analysis requires matching the corresponding features that characterize each constituent across multiple samples so that relevant characteristics or patterns can be recognized. Non-targeted, cross-sample analysis requires generating and matching all features across all samples. Applications of …

Synthesis And Flame Retardant Testing Of New Boronated And Phosphonated Aromatic Compounds, Vladimir Benin, Sravanthi Durganala, Alexander Morgan

Chemistry Faculty Publications

The present report describes the preparation and use of some dimethyl terephthalate derivatives in transition metal-catalyzed coupling reactions to produce new reactive flame retardants. Dimethyl iodoterephthalate and dimethyl 2,5-diiodoterephthalate were successfully employed in the preparation of phosphonic and boronic esters and acids. The latter were tested for heat release with a microcombustion calorimeter (ASTM D7309) to determine the potential for heat release reduction of these flame retardant molecules. The results showed that the addition of boronic or phosphonic acids greatly lowered the heat release, due to a condensed phase (char formation) mechanism. Adding ester groups to the boronic acids or …