Chemistry Commons^™

Halogen Activation Via Interactions With Environmental Ice And Snow In The Polar Lower Troposphere And Other Regions, J. P. D. Abbatt, J. L. Thomas, K. Abrahamsson, Chris Boxe, A. Granfors, A. E. Jones, M. D. King, A. Saiz-Lopez, P. B. Shepson, J. Sodeau, D. W. Toohey, C. Toubin, R. Von Glasow, S. N. Wren, X. Yang

Publications and Research

The role of ice in the formation of chemically active halogens in the environment requires a full understanding because of its role in atmospheric chemistry, including controlling the regional atmospheric oxidizing capacity in specific situations. In particular, ice and snow are important for facilitating multiphase oxidative chemistry and as media upon which marine algae live. This paper reviews the nature of environmental ice substrates that participate in halogen chemistry, describes the reactions that occur on such substrates, presents the field evidence for ice-mediated halogen activation, summarizes our best understanding of ice-halogen activation mechanisms, and describes the current state of modeling …

Rational Design And Characterization Of D-Phe-Pro-D-Arg-Derived Direct Thrombin Inhibitors, Ana C. Figueiredo, Christina C. Clement, Sheuli Zakia, Julian Gingold, Manfred Philipp, Pedro J.B. Pereira

Publications and Research

The tremendous social and economic impact of thrombotic disorders, together with the considerable risks associated to the currently available therapies, prompt for the development of more efficient and safer anticoagulants. Novel peptide-based thrombin inhibitors were identified using in silico structure-based design and further validated in vitro. The best candidate compounds contained both l- and d-amino acids, with the general sequence d-Phe(P3)-Pro(P2)-d-Arg(P1)-P1'-CONH2. The P1' position was scanned with l- and d-isomers of natural or unnatural amino acids, covering the major chemical classes. The most potent non-covalent and proteolysis-resistant inhibitors contain small hydrophobic or polar amino acids (Gly, Ala, Ser, Cys, Thr) …

Horizontally-Aligned Carbon Nanotubes Arrays And Their Interactions With Liquid Crystal Molecules: Physical Characteristics And Display Applications, Frederick Roussel, Jean-Francois Brun, Alexandre Allart, Limin Huang, Stephen O'Brien

Publications and Research

We report on the physical characteristics of horizonthally-grown Single-Walled Carbon Nanotubes (h-al-SWNT) arrays and their potential use as transparent and conducting alignment layer for liquid crystals display devices. Microscopy (SEM and AFM), spectroscopic (Raman) and electrical investigations demonstrate the strong anisotropy of h-al-SWNT arrays. Optical measurements show that h-al-SWNTs are efficient alignment layers for Liquid Crystal (LC) molecules allowing the fabrication of optical wave plates. Interactions between h-al-SWNT arrays and LC molecules are also investigated evidencing the weak azimuthal anchoring energy at the interface, which, in turn, leads to LC devices with a high pretilt angle. The electro-optical reponses of …

De Meo Carries On Tradition Of Teaching Chemistry, Aldemaro Romero Jr.

Publications and Research

No abstract provided.

Study Of The Gelling Process In The La-Co-Citric Acid System, Luminita Predoana, Andrei Jitianu, Barbara Malic, Maria Zaharescu

Publications and Research

The gelling process in the aqueous lanthanum-cobalt-citric acid system was studied using UV-VIS and IR spectroscopic methods, as well as viscosity measurements, to establish the gelling mechanism of transition metal ions (La3+ and Co2+) in the presence of chelating agent. Lanthanum and cobalt nitrates and lanthanum and cobalt acetates, respectively, were used as starting reagents, and the citric acid was used as chelating agent. The gelation process was investigated at room temperature and at 80°C. At elevated temperature, the gels were obtained after 30 h, whereas at room temperature, these were obtained in 1 month. Complex gels were formed for …

Thermal Analysis Of Organically Modified Siloxane Melting Gels, Andrei Jitianu, Kristin Lammers, Georgia A. Arbuckle-Kiel, Lisa C. Klein

Publications and Research

Hybrid melting gels were prepared by a sol–gel process, starting with a mono-substituted siloxane and a disubstituted siloxane, methyltrimethoxysilane (MTES) together with dimethyldimethoxysilane (DMDES). Five gel compositions were prepared with concentrations between 50% MTES–50% DMDES and 75% MTES–25% DMDES (in mol.%).

Synthesis Of Melting Gels Using Mono-Substituted And Di-Substituted Alkoxysiloxanes, Lisa Klein, Andrei Jitianu

Publications and Research

Hybrid organic-inorganic sol-gel materials containing silica were first called “ORMOSILs” in 1984.¹ Since then, the number of hybrid organicinorganic combinations has increased rapidly.² Hybrid materials have remarkable features resulting from the synergistic combination of both inorganic and organic components that make them suitable for a wide range of applications such as electrochemical devices, biomedical applications including drug delivery, and electronic and optoelectronic applications including light-emitting diodes, photodiodes, solar cells, gas sensors and field effect transistors.

Generally, organic-inorganic materials are classified in two broad categories: Class I materials where the organic and inorganic components are embedded one within the …

Jones Seeks To Engage Students In Chemistry, Aldemaro Romero Jr.

Publications and Research

No abstract provided.

Studies On Sucralose-Based Low Molecular Weight Gelators, Malick Samateh

Dissertations and Theses

Amphiphiles are molecules with both hydrophilic head and hydrophobic tail groups. Examples of amphiphiles include surfactants, detergents, soaps, bile acids/salts and lipids. Due to their amphiphilic nature, they tend to self-assemble in solution via non-covalent interactions such as hydrogen-bonding, π-π stacking and donor–acceptor interactions to form hierarchical morphologies like micelles, lamellae and fibers. The ones capable of subsequently forming gels are known as low molecular weight gelators (LMWGs). LMWGs usually form “polymer-like” fibers that interact to form a three-dimentional network known as a Self-Assembled Fibrillar Network (SAFIN), which entraps and immobilizes the entire solvent pool to form a viscoeslatic material …

Effects Of Arsenic And Uvb Radiation On Induction Of Cyclin D1 In Human Keratinocytes., Julian Gonzalez

Dissertations and Theses

Arsenic and Ultraviolet radiation B (UVB) are environmental toxins that have been linked to various epithelial cancers. Arsenic metabolism in humans leads to its collection in the skin, where it encounters and can act with known carcinogen UVB. Epidemiological evidence of the two toxins demonstrates their potential to affect signaling pathways, with various consequences. Here we employ an in vitro model system using Normal Human Epidermal Keratinocytes (NHEK) to identify the effect of arsenic and UVB on humans and whether they work synergistically. We find that although both cause induction of cyclin D1, culturing cells with both co-mutagens does not …

Azide-Benzyne Cycloaddition And Olefination To Vinyl Benzotriazoles, Singh Govindra

Dissertations and Theses

No abstract provided.

Fabrication Of Size-Tunable Metallic Nanoparticles Using Plasmid Dna As A Biomolecular Reactor, Jacopo Samson, Irene Piscopo, Alex Yampolski, Patrick Nahirney, Andrea Parpas, Amit Aggarwal, Raihan Saleh, Charles Michael Drain

Publications and Research

Plasmid DNA can be used as a template to yield gold, palladium, silver, and chromium nanoparticles of different sizes based on variations in incubation time at 70 °C with gold phosphine complexes, with the acetates of silver or palladium, or chromium acetylacetonate. The employment of mild synthetic conditions, minimal procedural steps, and aqueous solvents makes this method environmentally greener and ensures general feasibility. The use of plasmids exploits the capabilities of the biotechnology industry as a source of nanoreactor materials.

Group 11 Metal Compounds With Tripodal Bis(Imidazole) Thioether Ligands. Applications As Catalysts In The Oxidation Of Alkenes And As Antimicrobial Agents, Fangwei Liu, Reema Anis, Eunmi Hwang, Rafael Ovalle, Armando Varela-Ramírez, Renato J. Aguilera, María Contel

Publications and Research

New group 11 metal complexes have been prepared using the previously described tripodal bis(imidazole) thioether ligand (N-methyl-4,5-diphenyl-2- imidazolyl)2C(OMe)C(CH3)2S(tert-Bu) ({BITOMe,StBu}, 2). The pincer ligand offers a N2S donor atom set that can be used to coordinate the group 11 metals in different oxidation states [AuI , AuIII, AgI , CuI and CuII]. Thus the new compounds [Au{BITOMe,StBu}Cl][AuCl4]2 (3), [Au{BITOMe,StBu}Cl] (4), [Ag{BITOMe,StBu}X] (X = OSO2CF3 - 5, PF6 - 6) and [Cu{BITOMe,StBu}Cl2] (7) have been synthesized from reaction of 2 with the appropriate metal precursors, and characterized in solution. While attempting characterization in the solid state of 3, single crystals of the …

Polycationic Glycosides, Robert Engel, Ishrat Ghani, Diego Montenegro, Marie Thomas, Barbara Klaritch-Vrana, Alejandra Castaño, Laura Friedman, Jay Leb, Leah Rothman, Heidi Lee, Craig Capodiferro, Daniel Ambinder, Eve Cere, Christopher Awad, Faiza Sheikh, Jaimelee Rizzo, Lisa-Marie Nisbett, Erika Testani, Karin Melkonian

Publications and Research

Cationic lipids have long been known to serve as antibacterial and antifungal agents. Prior efforts with attachment of cationic lipids to carbohydrate-based surfaces have suggested the possibility that carbohydrate-attached cationic lipids might serve as antibacterial and antifungal pharmaceutical agents. Toward the understanding of this possibility, we have synthesized several series of cationic lipids attached to a variety of glycosides with the intent of generating antimicrobial agents that would meet the requirement for serving as a pharmaceutical agent, specifically that the agent be effective at a very low concentration as well as being biodegradable within the organism being treated. The initial …

Climate Change: The Fork At The End Of Now, Micha Tomkiewicz

Publications and Research

There are many books on global warming written entirely from a layman's perspective, and there is a great deal of scientific literature on this subject. But few if any books attempt to bridge the science to those who lack a rigorous background in mathematics, physics and chemistry-but who may be working on careers in environmental science and policy. The new text is designed to introduce the field of global climate change from a scientific perspective-but written in a way that is accessible to students with some or little science background. It reviews the basic principles of climatic thermodynamics and atmospheric …

Synthesis Of Alkynyl Ribofuranosides, Christian Rodriguez

Dissertations and Theses

No abstract provided.

Synthesis And Characterization Of Pbte Quantum Dots, Faiza Anwar

Dissertations and Theses

No abstract provided.

Hybrid Micro-/Nanogels For Optical Sensing And Intracellular Imaging, Weitai Wu, Shuiqin Zhou

Publications and Research

Hybrid micro-/nanogels are playing an increasing important part in a diverse range of applications, due to their tunable dimensions, large surface area, stable interior network structure, and a very short response time. We review recent advances and challenges in the developments of hybrid micro-/nanogels toward applications for optical sensing of pH, temperature, glucose, ions, and other species as well as for intracellular imaging. Due to their unique advantages, hybrid micro-/nanogels as optical probes are attracting substantial interests for continuous monitoring of chemical parameters in complex samples such as blood and bioreactor fluids, in chemical research and industry, and in food …

Identification And Quantitation Of 3,4-Methylenedioxy-N-Methylamphetamine (Mdma, Ecstasy) In Human Urine By 1h Nmr Spectroscopy. Application To Five Cases Of Intoxication, Jonathan Liu, John Decatur, Gloria Proni, Elise Champeil

Publications and Research

Identification of 3,4-methylenedioxy-N-methylamphetamine (MDMA, ecstasy) in five cases of intoxication using nuclear magnetic resonance (NMR) spectroscopy of human urine is reported. A new water suppression technique PURGE (Presaturation Utilizing Relaxation Gradients and Echoes) was used. A calibration curve was obtained using spiked samples. The method gave a linear response (correlation coefficient of 0.992) over the range 0.01–1 mg/mL. Subsequently, quantitation of the amount of MDMA present in the samples was performed. The benefit and reliability of NMR investigations of human urine for cases of intoxication with MDMA are discussed.

Core/Shell Nanoparticles As Hybrid Platforms For The Fabrication Of A Hydrogen Peroxide Biosensor, Yu-Ho Won, Doreen Aboagye, Ho Seong Jang, Andrei Jitianu, Lia A. Stanciu

Publications and Research

No abstract provided.

A Multivalent Dna Aptamer Specific For The B-Cell Receptor On Human Lymphoma And Leukemia, Prabodhika R. Mallikaratchy, Alessandro Ruggiero, Jeffrey R. Gardner, Vitaly Kuryavyi, William F. Maguire, Mark L. Heaney, Michael R. Mcdevitt, Dinshaw J. Patel, David A. Scheinberg

Publications and Research

Long-term survival still eludes most patients with leukemia and non-Hodgkin’s lymphoma. No approved therapies target the hallmark of the B cell, its mIgM, also known as the B-cell receptor (BCR). Aptamers are small oligonucleotides that can specifically bind to a wide range of target molecules and offer some advantages over antibodies as therapeutic agents. Here, we report the rational engineering of aptamer TD05 into multimeric forms reactive with the BCR that may be useful in biomedical applications. Systematic truncation of TD05 coupled with modification with locked nucleic acids (LNA) increased conformational stability and nuclease resistance. Trimeric and tetrameric versions with …

Energy Of The Conduction Band In Near Critical Point Fluids, Cherice M. Evans, G. L. Findley

Publications and Research

The study of the evolution of the conduction band in dense gases and supercritical fluids near the critical point has been complicated by a lack of precise experimental measurements. Both photoemission from an electrode immersed in the fluid and field ionization of a molecule doped into the fluid have been used to probe solvent density effects on the energy of an excess electron as a function of fluid number density and temperature. In this perspective, we present recent experimental results that show a strong critical point effect on the minimumconduction band energy near the critical density and temperature of a …

Selective Adsorption Of Dibenzothiophenes On Activated Carbons With Metal Species Deposited On Their Surfaces, Jakub Lison

Dissertations and Theses

"The objective of this thesis is an investigation of influence of porosity, surface chemistry, material composition and effects of metals oncarbon adsorbents in desulfurization of liquid fuels. Materials are derived from poly (4-styrenesulfonic acid-co-maleic acid) salts (sodium or transition metals). They are investigated in a dynamic breakthrough process using model diesel fuel containing dibenzothiophene (DBT) and 4, 6-dimethyldibenzothiophene (DMDBT). The performance of adsorbents is evaluated in terms of the capacity and selectivity. Differences in performance are investigated considering the porosity, surface chemistry and the type of material used."

Modular Synthesis Of Weinreb Amides Of 2-Fluoro-2,4-Dienoic Acids, Mohammad Chowdhury

Dissertations and Theses

No abstract provided.

Correlating Molecular Phylogeny With Venom Apparatus Occurrence In Panamic Auger Snails (Terebridae), Mandë Holford, Nicolas Puillandre, Maria Vittoria Modica, Maren Watkins, Rachel Collin, Eldredge Bermingham, Baldomero M. Olivera

Publications and Research

Central to the discovery of neuroactive compounds produced by predatory marine snails of the superfamily Conoidea (cone snails, terebrids, and turrids) is identifying those species with a venom apparatus. Previous analyses of western Pacific terebrid specimens has shown that some Terebridae groups have secondarily lost their venom apparatus. In order to efficiently characterize terebrid toxins, it is essential to devise a key for identifying which species have a venom apparatus. The findings presented here integrate molecular phylogeny and the evolution of character traits to infer the presence or absence of the venom apparatus in the Terebridae. Using a combined dataset …

Phenyl-Substituted Siloxane Hybrid Gels That Soften Below 140[Degrees]C, Andrei Jitianu, Glenn Amatucci, Lisa C. Klein

Publications and Research

A characteristic of so-called melting gels is that the gels, which are rigid at room temperature, are able to soften and resoften at temperatures around 110 [degrees]C. However, after consolidation at temperatures higher than 150 [degrees]C, the gels no longer resoften. Two systems of melting gels were investigated: phenyltrimethoxysilane (PhTMS)–diphenyldimethoxysilane (DPhDMS) and phenyltriethoxysilane (PhTES)–diphenyldiethoxysilane (DPhDES). The influence of disubstituted versus monosubstituted alkoxide on the softening behavior and the temperature of decomposition was studied. The consolidation temperature increased as the amount of disubstituted alkoxide increased, while the decomposition temperature increased only slightly. In general, the ethoxy-containing gels (maximum at 150[degrees]C) consolidated …

Structural Studies Of Biopolymers Using Computer Simulations, Optical And Magnetic Spectroscopy, Subhasish Chatterjee

Dissertations, Theses, and Capstone Projects

Biopolymers are essential components of numerous natural and synthetic macromolecular assemblies. In the present study, the structural properties of biopolymers ranging from fungal melanins to synthetic nucleic acids were investigated using spectroscopic methods and theoretical modeling. (1) Computational modeling and molecular dynamics simulations were used to study the structural properties of a short single-stranded (ss) DNA. The dependence of the conformational stability and flexibility of the ssDNA on the thermodynamic conditions of the system was demonstrated. (2) Time-resolved fluorescence spectroscopy involving an organic donor-quencher pair was utilized to study the conformational properties of Y-shaped DNA. Results highlighted the different distances …

(Μ-Diazenediyldiphenyl-Κ2c2, N2: Κ2c2′, N1) Bis [(3, 5-Dimethylphenyl) Tellurium (Ii)]., Prabodhika R. Mallikaratchy, Richard E. Norman, Frank R. Fronczek, Thomas Junk

Publications and Research

The title compound, C28H26N2Te2, prepared by reduction of (3,5-dimethylphenyl)(2-nitrophenyl)tellurium(II), is the first structurally characterized example of an azo group bridging two TeII centers. The compound is centrosymmetric and the Te—N distance [2.6916 (19) A ° ] is longer than in non-bridging azo compounds.

Metathesis Key In Production Of Pharmaceuticals, Plastics, Aldemaro Romero Jr., Michael J. Panigot

Publications and Research

No abstract provided.

Tribromo(3,5-Dimethyl-2-Nitrophenyl-J2 C1 ,O)Tellurium(Iv), Bromo(3,5-Dimethyl-2-Nitrophenyl-J2 C1 ,O)Tellurium(Ii) And Bromo(3,5-Dimethyl-2-Nitrosophenyl-J2 C1 ,O)Tellurium(Ii), Prabodhika R. Mallikaratchy, Richard E. Norman, Frank R. Fronczek, Thomas Junk

Publications and Research

All three title compounds, prepared from bis(3,5-dimethyl-2- nitrophenyl)ditellurium, exhibit high degrees of intramolecular TeÐO coordination. Their TeÐO distances increase in the order C8H8BrNOTe < C8H8BrNO2Te < C8H8Br3NO2Te, with distances of 2.165 (3), 2.306 (1) and 2.423 (6) AÊ , respectively, indicating that C8H8BrNOTe may be more aptly described as 1-bromo-4,6-dimethyl-2,1,3-benzoxatellurazole.