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Articles 1561 - 1590 of 2100

Full-Text Articles in Chemistry

Characterization Of Esterase Activity From The Bacteria, Francisella Tularensis, The Causative Agent Of Tularemia, Leigh Anna Weston May 2011

Characterization Of Esterase Activity From The Bacteria, Francisella Tularensis, The Causative Agent Of Tularemia, Leigh Anna Weston

Undergraduate Honors Thesis Collection

Francisella tularensis is the bacteria responsible for causing the disease tularemia and is listed as one of the top three-biowarfare agents. Among the proteins essential to the virulence and infectivity of F.tularensis are multiple esterases, which are enzymes that break down various ester, thioester, and amide bonds. In this project, the catalytic activity, substrate speci fi city, and structure of a putative esterase from F.tularensis was studied. Latent fluorophores based on the molecule, fluorescein, were unmasked by the enzymatic activity of the esterase and the increase in fluorescence was measured over time to determine how well the e tcrase recognized …

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Chiral Recognition Study Of A Bimolecular Process In Amino Acid Chiral Ionic Liquids, Laurel Millikan Heckman May 2011

Chiral Recognition Study Of A Bimolecular Process In Amino Acid Chiral Ionic Liquids, Laurel Millikan Heckman

Undergraduate Honors Thesis Collection

In this study, chiral ionic liquid (CIL) solvents were prepared and tested for their chiral discrimination ability by probing with luminescence quenching. The CIL's were also tested for their impurities, viscosity and density. These experiments will help to determine the ability of CIL's to act as solvents in asymmetric catalysis. The chiral ionic liquids in this study were composed of amino acid methyl ester cations and bis(trifluoromethane) sulfonimide or bistri flimide anions (i.e. I-alanine methyl ester bistriflimid e, d-alanine methyl ester bistr iflim ide and I-leuci ne methyl ester bistriflimde). Circularly polarized luminescence (CPL) and its quenching in the chiral …

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An Assessment Of Stable Hydrogen-Isotope Analysis Methods To Assign Geographic Origin To Migratory Red-Tailed Hawks (Buteo Jamaicensis), Carla Marie Ahlschwede May 2011

An Assessment Of Stable Hydrogen-Isotope Analysis Methods To Assign Geographic Origin To Migratory Red-Tailed Hawks (Buteo Jamaicensis), Carla Marie Ahlschwede

Department of Environmental Studies: Undergraduate Student Theses

Stable-hydrogen isotopes are becoming an increasingly popular method of studying migratory birds, though sample preparation methods may affect results.  In this study I examined feathers from red-tailed hawks (Buteo jamaicensis) to determine the relationship between measure of δD due to inter-feather variation or drying methods, assessed the accuracy of results by using two birds of known-origin and estimated possible natal origins of migratory red-tailed hawks.  Two feathers per individual were taken from 81 wild hawks caught at Hitchcock Nature Center near Crescent IA and from 2 rescued red-tailed hawks, Raptor Recovery Nebraska near Eagle, NE. 119 of the …

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The Applications Of Graphene And Its Derivatives For Heavy Metal Removal, Clemonne John Madarang May 2011

The Applications Of Graphene And Its Derivatives For Heavy Metal Removal, Clemonne John Madarang

Theses, Dissertations and Culminating Projects

Heavy metal pollution is very prevalent in our environment. The entire removal of heavy metal and organic contaminants in natural water resources will not only affect the environment itself, but also can block the toxic contaminant transfers in food chains. Currently, there are many studies being done to remove these heavy metal ions from our water, such as reduction reactions, chemical precipitation, reverse osmosis and electrolytic recovery. One of the promising techniques is adsorption. The focus of this research is using graphene and its derivatives, such as silylated graphene oxide (GO), to adsorb heavy metals, specifically, lead. This research describes …

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Investigation Of Charge Recombination In Escherichia Coli Photolyase And Vibrio Cholera Cryptochrome Dash, Agnieszka Zieba May 2011

Investigation Of Charge Recombination In Escherichia Coli Photolyase And Vibrio Cholera Cryptochrome Dash, Agnieszka Zieba

Theses, Dissertations and Culminating Projects

Proton-coupled electron-transfer (PCET) is a mechanism of great importance in protein electron transfer and enzyme catalysis, and the involvement of aromatic amino acids in this process is of much interest. The DNA repair enzyme photolyase provides a natural system that allows for the study of PCET using a neutral radical tryptophan (Trp‘). In Escherichia coli photolyase, photoreduction of the flavin adenine dinucleotide (FAD) cofactor in its neutral radical semiquinone form (FADH') results in the formation of FADH and Trp . Charge recombination between these two intermediates requires O A/T # the uptake of a proton by ~ Trp . The …

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Germline Cyst Formation And Development In Zebrafish, Tess Cherlin May 2011

Germline Cyst Formation And Development In Zebrafish, Tess Cherlin

Renée Crown University Honors Thesis Projects - All

In developing pre-natal mice, germline cysts are clusters or packages of cells consisting of individual oocytes. They are formed after the primordial germ cells move to the ovary during embryogenesis. The primordial germ cells divide, but do not completely separate. The cells within the cysts are linked by intercellular bridges, which end up breaking down leading to the formation of primordial follicles. The primordial follicles are oocytes surrounded by somatic cells called granulosa cells. Only one third of the original oocytes survive cyst breakdown and become the eggs that will be used by the mouse for her reproduction. This developmental …

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Protein-Lipid Interactions: Influence Of Anchoring Groups And Buried Arginine On The Properties Of Membrane-Spanning Peptides, Vitaly V. Vostrikov May 2011

Protein-Lipid Interactions: Influence Of Anchoring Groups And Buried Arginine On The Properties Of Membrane-Spanning Peptides, Vitaly V. Vostrikov

Graduate Theses and Dissertations

Designed transmembrane peptides were employed for investigations of protein-lipid interactions by means of oriented solid-state deuterium NMR spectroscopy using isotope-enriched alanine residues. Using the model GWALP23 sequence (GGALW(LA)6LWLAGA) as a host peptide having single interfacial tryptophan anchor residues, the effects of different guest mutations were explored. Replacements of glycine residues 2 and 22 to positively charged lysine or arginine on both termini had little influence on the peptide average orientation. Conversely, glycine to tryptophan substitutions had profound effects, manifested in the increased dynamics and altered tilt direction of the peptide. While the charged residues at the peptide termini did not …

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Synthetic Dosage Lethality Screen With Actin Cytoskeleton In Yeast, Jessica Cho May 2011

Synthetic Dosage Lethality Screen With Actin Cytoskeleton In Yeast, Jessica Cho

Renée Crown University Honors Thesis Projects - All

The actin cytoskeleton is a vitally important organizing structure found in the cytoplasm of our cells. It contributes to essential cell functions from growth and cell division, development, signal transduction, adaptation, to gene expression. Interest in how regulation of the actin cytoskeleton---due to actin cytoskeleton's importance to cell function-may contribute to diverse human disease states such as the rampant cell division and metastasis that occurs in cancerous tissues. It has been further elucidated that many human genetic disorders are the result of complex haploinsufficiencies (CHI) and/or altered gene dosages at multiple loci. By reviewing a large number of potential Synthetic …

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Characterization Of Ceriporiopsis Subvermispora Bicupin Oxalate Oxidase Expressed In Pichia Pastoris, Patricia Moussatche, Alexander Angerhofer, Witcha Imaram, Eric Hoffer, Kelsey Uberto, Christopher Brooks, Crystal Bruce, Daniel Sledge, Nigel G. J. Richards, Ellen W. Moomaw May 2011

Characterization Of Ceriporiopsis Subvermispora Bicupin Oxalate Oxidase Expressed In Pichia Pastoris, Patricia Moussatche, Alexander Angerhofer, Witcha Imaram, Eric Hoffer, Kelsey Uberto, Christopher Brooks, Crystal Bruce, Daniel Sledge, Nigel G. J. Richards, Ellen W. Moomaw

Faculty Articles

Oxalate oxidase (E.C. 1.2.3.4) catalyzes the oxygen-dependent oxidation of oxalate to carbon dioxide in a reaction that is coupled with the formation of hydrogen peroxide. Although there is currently no structural information available for oxalate oxidase fromCeriporiopsis subvermispora (CsOxOx), sequence data and homology modeling indicate that it is the first manganese-containing bicupin enzyme identified that catalyzes this reaction. Interestingly, CsOxOx shares greatest sequence homology with bicupin microbial oxalate decarboxylases (OxDC). We show that CsOxOx activity directly correlates with Mn content and other metals do not appear to be able to support catalysis. EPR spectra indicate that the Mn is present …

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Differentiation Of Bacillus Endospores From Gas Chromatography-Mass Spectrometry Of Biomarkers Produced By Thermochemolysis Methylation, Tai Van Truong Apr 2011

Differentiation Of Bacillus Endospores From Gas Chromatography-Mass Spectrometry Of Biomarkers Produced By Thermochemolysis Methylation, Tai Van Truong

Theses and Dissertations

Methods for fast, simple detection of biomarkers to detect and differentiate closely related Bacillus endospores including Bacillus anthracis (BA), Bacillus thuringiensis (BT), Bacillus atrophaeus (BG), and Bacillus cereus (BC) using thermochemolysis and methylation (TCM), coiled wire filament (CWF), solid phase micro extraction (SPME) and gas chromatography-mass spectrometry (GC-MS) were developed. The main biomarkers detected and used for differentiation include dipicolinic acid methyl ester (DPAME), fatty acid methyl esters (FAMEs), 3-methyl-2-butenoic acid methyl ester (3M2BAME), 2-butenoic acid methyl ester (2BAME), and several methylated sugars. TCM of endospores was performed based on hydrolysis and methylation at elevated temperature after the endospores were …

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Epistatic Roles For Pseudomonas Aeruginosa Muts And Dinb (Dna Pol Iv) In Coping With Reactive Oxygen Species-Induced Dna Damage, Laurie H. Sanders, Babho Devadoss, Geraldine V. Raja, Jaime O'Connor, Shengchang Su, Daniel J. Wozniak, Daniel J. Hassett, Anthony J. Berdis, Mark D. Sutton Apr 2011

Epistatic Roles For Pseudomonas Aeruginosa Muts And Dinb (Dna Pol Iv) In Coping With Reactive Oxygen Species-Induced Dna Damage, Laurie H. Sanders, Babho Devadoss, Geraldine V. Raja, Jaime O'Connor, Shengchang Su, Daniel J. Wozniak, Daniel J. Hassett, Anthony J. Berdis, Mark D. Sutton

Chemistry Faculty Publications

Pseudomonas aeruginosa is especially adept at colonizing the airways of individuals afflicted with the autosomal recessive disease cystic fibrosis (CF). CF patients suffer from chronic airway inflammation, which contributes to lung deterioration. Once established in the airways, P. aeruginosa continuously adapts to the changing environment, in part through acquisition of beneficial mutations via a process termed pathoadaptation. MutS and DinB are proposed to play opposing roles in P. aeruginosa pathoadaptation: MutS acts in replication-coupled mismatch repair, which acts to limit spontaneous mutations; in contrast, DinB (DNA polymerase IV) catalyzes error-prone bypass of DNA lesions, contributing to mutations. As part of …

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Characterization Of Ips Pini Ipsdienol Dehydrogenase (Idol Dh), Heidi Pak, Claus Tittiger, William Welch Apr 2011

Characterization Of Ips Pini Ipsdienol Dehydrogenase (Idol Dh), Heidi Pak, Claus Tittiger, William Welch

Festival of Communities: UG Symposium (Posters)

Ipsdienol is an important pheromone component for pine engraver beetle, Ips pini. Ipsdienol is a ten carbon monoterpenoid secondary alcohol and ipsdienone is the corresponding ketone. We are characterizing the activity of recombinant IDOL DH produced in Sf9 (insect) cells. The enzyme has a high stereospecificity: (-) ipsdienol was found to be a substrate while (+)-ipsdienol was neither a substrate nor inhibitor. Closely related monoterpenoids, such as nerol, geraniol, and citral, were neither substrates nor inhibitors. Smaller compounds, such as 2-propanol, also failed to act as an inhibitor or substrate. This indicates the binding site of this enzyme is highly …

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Dicarbonyldichloridobis(Trimethylphosphane)Iron(Ii)–Carbonyldichloridotris(Trimethylphosphane)Iron(Ii)–Tetrahydrofuran (1/1/2), Nigam Rath, Meghan Stouffer, Matthew Janssen, John Bleeke Apr 2011

Dicarbonyldichloridobis(Trimethylphosphane)Iron(Ii)–Carbonyldichloridotris(Trimethylphosphane)Iron(Ii)–Tetrahydrofuran (1/1/2), Nigam Rath, Meghan Stouffer, Matthew Janssen, John Bleeke

Chemistry & Biochemistry Faculty Works

The asymmetric unit of the title crystal, [FeCl2(C3H9P)3(CO)]·[FeCl2(C3H9P)2(CO)2]·2C4H8O, contains half mol­ecules of the two closely related FeII complexes lying on mirror planes and a tetra­hydro­furan solvent mol­ecule, one C atom of which is disordered over two sets of sites with site occupancy factors 0.633 (9) and 0.367 (9). In both FeII complex mol­ecules, a distorted octa­hedral coordination geometry has been observed around the Fe atoms. Weak intermolecular C-H...O inter­actions are observed in the crystal structure.

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Bioinformatics, Thermodynamics And Kinetics Analysis Of An All Alpha Helical Protein With A Gree-Key Topology, Hai Li Apr 2011

Bioinformatics, Thermodynamics And Kinetics Analysis Of An All Alpha Helical Protein With A Gree-Key Topology, Hai Li

Chemistry & Biochemistry Theses & Dissertations

Computational and experimental studies focusing on the role of conserved residues for folding and stability is an active and promising area of research. To further expand our understanding we present the results of a bioinformatics analysis of the death domain superfamily. The death domain superfamily fold consists of six α-helices arranged in a Greek-key topology, which is shared by the all β-sheet immunoglobulin and mixed α/β-plait superfamilies. Our sequence and structural studies have identified a group of conserved hydrophobic residues and corresponding long-range interactions, which we propose are important in the formation and stabilization of the hydrophobic core and native …

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Organometallic Iron(Iii)-Salophene Exerts Cytotoxic Properties In Neuroblastoma Cells Via Mapk Activation And Ros Generation, Kyu Kwang Kim, Rakesh K. Singh, Robert M. Strongin, Richard G. Moore, Laurent Brard, Thilo S. Lange Apr 2011

Organometallic Iron(Iii)-Salophene Exerts Cytotoxic Properties In Neuroblastoma Cells Via Mapk Activation And Ros Generation, Kyu Kwang Kim, Rakesh K. Singh, Robert M. Strongin, Richard G. Moore, Laurent Brard, Thilo S. Lange

Chemistry Faculty Publications and Presentations

The objective of the present study was to investigate the specific effects of Iron(III)-salophene (Fe-SP) on viability, morphology, proliferation, cell cycle progression, ROS generation and pro-apoptotic MAPK activation in neuroblastoma (NB) cells. A NCI-DTP cancer screen revealed that Fe-SP displayed high toxicity against cell lines of different tumor origin but not tumor type-specificity. In a viability screen Fe-SP exhibited high cytotoxicity against all three NB cell lines tested. The compound caused cell cycle arrest in G1 phase, suppression of cells progressing through S phase, morphological changes, disruption of the mitochondrial membrane depolarization potential, induction of apoptotic markers as well as …

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Computational Investigation Of The Bioactive Selenium Compounds Ebselen And Selenious Acid, Sonia Antony Apr 2011

Computational Investigation Of The Bioactive Selenium Compounds Ebselen And Selenious Acid, Sonia Antony

Chemistry & Biochemistry Theses & Dissertations

Selenium, a toxic element, is required in trace quantities for the proper functioning of biological systems. The experimental mechanistic study of the reactions of ebselen and selenious acid is difficult due to complexity of the reaction mixtures and the presence of short-lived intermediates. Computational modeling of the reactivity of these species can give us an insight into their mechanisms, but the process is complicated by proton exchanges associated with the mechanistic steps. In gas phase modeling, this may be corrected to a certain level using the solvent assisted proton exchange (SAPE) method. SAPE is a modeling technique that mimics solvent …

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Human Endogenous Sodium Pump Inhibitors Measurement, Source, Synthesis And Regulation, Jie Ma Mar 2011

Human Endogenous Sodium Pump Inhibitors Measurement, Source, Synthesis And Regulation, Jie Ma

Theses and Dissertations

The sodium pump (SP or Na+,K+-ATPase) is a membrane embedded protein complex that pumps 3 sodium ions out and 2 potassium ions into the cell per cycle and in so doing creates a cell membrane electrochemical potential. The membrane potential is critical for any functional cell. In the vasculature, reduction in the voltage potential causes vascular smooth muscle contraction and a narrowing of blood vessels (vasoconstriction) which can lead to increased blood pressure (hypertension). Substantial research over the past several decades has provided a vast amount of research on SP inhibitors, sometimes called endogenous digitalis-like factors (EDLF). Increased levels of …

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Super Collision Energy Transfer Studies In Single Collisions Between Vibrationally Hot Benzene Like Molecules And Ground State Bath Molecules: The Effect Of Physical Properties Of Donor And Bath Molecules On Super Collision Energy Transfer, Kilyoung Kim Mar 2011

Super Collision Energy Transfer Studies In Single Collisions Between Vibrationally Hot Benzene Like Molecules And Ground State Bath Molecules: The Effect Of Physical Properties Of Donor And Bath Molecules On Super Collision Energy Transfer, Kilyoung Kim

Theses and Dissertations

This research is focused on single-collision energy transfer events between highly vibrationally excited benzene-like donor molecules and small bath molecules, CO2 and N2O in the vibrational ground level. Measuring how much energy is transferred from donors to bath molecules was accomplished by probing bath molecules scattered into specific-rotational states using a tunable Δv=0.0003 cm-1 solid state diode laser. The normalized energy transfer probability distribution function, P(E,E'), determined from energy gain information, is very useful in comparing collisional energy transfer efficiency between various collision systems. P(E,E') is also used to investigate the effects of donor and bath physical properties on collisional …

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A Novel Use Of Digoxin Immune Fab Fragment In Identification And Isolation Of An Endogenous Digitalis-Like Factor Found In Preeclampsia, Moana Lee Hopoate-Sitake Mar 2011

A Novel Use Of Digoxin Immune Fab Fragment In Identification And Isolation Of An Endogenous Digitalis-Like Factor Found In Preeclampsia, Moana Lee Hopoate-Sitake

Theses and Dissertations

The mechanisms mediating the hypertension of preeclampsia (PE) are unclear. Endogenous digitalis-like factors (EDLFs) are specific sodium pump (SP) inhibitors implicated in essential and experimental hypertension, but they have not been fully explored in the setting of PE. This study uses a digoxin antibody Fab fragment to address the question of whether such factors are present and increased in PE, to investigate a possible treatment of PE, and to isolate and characterize all EDLFs present in PE. Sera and placenta from women with PE did show a significant increase in SP inhibition in comparison to women with normal pregnancy and …

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Surface Modification, Fabrication, And Characterization Of Silicon, Polymer, And Nanotube Composite Materials, Lei Pei Mar 2011

Surface Modification, Fabrication, And Characterization Of Silicon, Polymer, And Nanotube Composite Materials, Lei Pei

Theses and Dissertations

In my research, I have performed many characterization and fabrication experiments that are based on tools of analytical chemistry, materials chemistry, and surface science. My research projects are as follows. (1) Fabrication of transparent polymer templates for nanostructured amorphous silicon photovoltaics was done using low-cost nanoimprint lithography of polydimethylsiloxane. This approach provides a test bed for absorption studies in nanostructured film geometries and should result in improved light capturing designs in thin-film solar cells. Nanopatterned polymer films were characterized by scanning electron microscopy and optical measurements. (2) A straightforward method for fabricating freely suspended, thin, carbon nanotube (CNT) membranes infiltrated …

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Transformation Of Fusarium Verticillioides With A Polyketide Gene Cluster Isolated From A Fungal Endophyte Activates The Biosynthesis Of Fusaric Acid, Yunxuan Xie, Wei Zhang, Yaoyao Li, Mingzi Wang, Ronald Cerny, Yue Shen, Liangcheng Du Mar 2011

Transformation Of Fusarium Verticillioides With A Polyketide Gene Cluster Isolated From A Fungal Endophyte Activates The Biosynthesis Of Fusaric Acid, Yunxuan Xie, Wei Zhang, Yaoyao Li, Mingzi Wang, Ronald Cerny, Yue Shen, Liangcheng Du

Liangcheng Du Publications

A large number of bioactive natural products have been isolated from plant endophytic fungi. However, molecular mechanisms for the biosynthesis of these metabolites have lagged behind because genetic and biochemical studies are difficult to perform within many of the endophytes. In this work, we describe our attempt to express a putative mycoepoxydiene (MED) biosynthetic gene cluster in Fusarium verticillioides, which has a well-developed genetic system for the study fungal polyketide biosynthesis. MED was isolated from Phomopsis sp. A123, a fungal endophyte of the mangrove plant, Kandelia candel. It has several unusual structural features and interesting biological activities. Integration of …

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Quantifying The Energetic Contributions Of Desolvation And Π-Electron Density During Translesion Dna Synthesis, Edward A. Motea, Irene Lee, Anthony J. Berdis Mar 2011

Quantifying The Energetic Contributions Of Desolvation And Π-Electron Density During Translesion Dna Synthesis, Edward A. Motea, Irene Lee, Anthony J. Berdis

Chemistry Faculty Publications

This report examines the molecular mechanism by which high-fidelity DNA polymerases select nucleotides during the replication of an abasic site, a non-instructional DNA lesion. This was accomplished by synthesizing several unique 5-substituted indolyl 2′-deoxyribose triphosphates and defining their kinetic parameters for incorporation opposite an abasic site to interrogate the contributions of π-electron density and solvation energies. In general, the Kd, app values for hydrophobic non-natural nucleotides are ∼10-fold lower than those measured for isosteric hydrophilic analogs. In addition, kpol values for nucleotides that contain less π-electron densities are slower than isosteric analogs possessing higher degrees of π-electron density. The differences …

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Formation And Stability Of Atmospherically Relevant Isoprene-Derived Organosulfates And Organonitrates, Adam I. Darer, Neil C. Cole-Filipiak, Alison E. O'Connor, Matthew J. Elrod Mar 2011

Formation And Stability Of Atmospherically Relevant Isoprene-Derived Organosulfates And Organonitrates, Adam I. Darer, Neil C. Cole-Filipiak, Alison E. O'Connor, Matthew J. Elrod

Faculty & Staff Scholarship

Isoprene is the precursor for number of alcohol, organosulfate, and organonitrate species observed in ambient secondary organic aerosol (SOA). Recent laboratory and field work has suggested that isoprene-derived epoxides may be crucial intermediates that can explain the existence of these compounds in SOA. To confirm this hypothesis, the specific hydroxy epoxides observed in gas phase isoprene photooxidation experiments (as well as several other related species) were synthesized and the bulk phase aqueous reactions of these species in the presence of sulfate and nitrate were studied via nuclear magnetic resonance (NMR) techniques. The results indicate that both primary and tertiary organosulfates …

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Development Of Monolithic Stationary Phases For Cation-Exchange Capillary Liquid Chromatography Of Peptides And Proteins, Xin Chen Feb 2011

Development Of Monolithic Stationary Phases For Cation-Exchange Capillary Liquid Chromatography Of Peptides And Proteins, Xin Chen

Theses and Dissertations

This dissertation focuses on the preparation of polymeric monolithic capillaries for ion exchange chromatography of peptides and proteins, since polymeric monoliths have shown promise for providing improved protein separations. Characteristics of monolithic columns include low back pressure, simplicity of fabrication and biocompatibility. Preparation of strong and weak cation-exchange monolithic stationary phases in 75 μm I.D. capillaries by direct in situ copolymerization was achieved using various functional monomers including sulfopropyl methacrylate, phosphoric acid 2-hydroxyethyl methacrylate, bis[2-(methacryloyloxy)ethyl] phosphate and 2-carboxyethyl acrylate with polyethylene glycol diacrylate and other PEG materials. The resulting monoliths provided excellent ion exchange capillary LC of peptides and proteins …

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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 Feb 2011

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 …

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A New Noncovalent Force: Comparison Of P∙∙∙N Interaction With Hydrogen And Halogen Bonds, Steve Scheiner Jan 2011

A New Noncovalent Force: Comparison Of P∙∙∙N Interaction With Hydrogen And Halogen Bonds, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

When PH(3) is paired with NH(3), the two molecules are oriented such that the P and N atoms face one another directly, without the intermediacy of a H atom. Quantum calculations indicate that this attraction is due in part to the transfer of electron density from the lone pair of the N atom to the σ(∗) antibond of a P-H covalent bond. Unlike a H-bond, the pertinent hydrogen is oriented about 180° away from, instead of toward, the N, and the N lone pair overlaps with the lobe of the P-H σ(∗) orbital that is closest to the P. In …

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A Bulk Water-Dependent Desolvation Energy Model For Analyzing The Effects Of Secondary Solutes On Biological Equilibria, Daryl K. Eggers Jan 2011

A Bulk Water-Dependent Desolvation Energy Model For Analyzing The Effects Of Secondary Solutes On Biological Equilibria, Daryl K. Eggers

Faculty Publications, Chemistry

A new phenomenological model for interpreting the effects of solutes on biological equilibria is presented. The model attributes changes in equilibria to differences in the desolvation energy of the reacting species that, in turn, reflect changes in the free energy of the bulk water upon addition of secondary solutes. The desolvation approach differs notably from that of other solute models by treating the free energy of bulk water as a variable and by not ascribing the observed shifts in reaction equilibria to accumulation or depletion of solutes next to the surfaces of the reacting species. On the contrary, the partitioning …

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Microfluidic Paper-Based Analytical Devices: From Pocket To Paper-Based Elisa, Andres W. Martinez Jan 2011

Microfluidic Paper-Based Analytical Devices: From Pocket To Paper-Based Elisa, Andres W. Martinez

Chemistry and Biochemistry

Microfluidic paper-based analytical devices (microPADs) began as a simple idea with an ambitious goal. The idea was to make microfluidic devices out of paper instead of plastic or glass. The goal was to develop low-cost and portable paper-based diagnostic devices to improve healthcare in developing countries. Over the past 6 years, many developments have been made in the emerging field of paper-based microfluidic devices. Reviewing the development of these devices in the Whitesides group at Harvard University (Cambridge, MA, USA) can provide some insight into the future of the field and encourage scientists from a variety of backgrounds to contribute …

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Better Biomolecule Thermodynamics From Kinetics, Kiran Girdhar, Gregory Scott, Yann R. Chemla, Martin Gruebele Jan 2011

Better Biomolecule Thermodynamics From Kinetics, Kiran Girdhar, Gregory Scott, Yann R. Chemla, Martin Gruebele

Chemistry and Biochemistry

Protein stability is measured by denaturation: When solvent conditions are changed (e.g., temperature, denaturant concentration, or pH) the protein population switches between thermodynamic states. The resulting denaturation curves have baselines. If the baselines are steep, nonlinear, or incomplete, it becomes difficult to characterize protein denaturation. Baselines arise because the chromophore probing denaturation is sensitive to solvent conditions, or because the thermodynamic states evolve structurally when solvent conditions are changed, or because the barriers are very low (downhill folding). Kinetics can largely eliminate such baselines: Relaxation of chromophores, or within thermodynamic states, is much faster than the transition over activation …

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The Fire Inventory From Ncar (Finn): A High Resolution Global Model To Estimate The Emissions From Open Burning, C. Wiedinmyer, S. K. Akagi, Robert J. Yokelson, L. K. Emmons, J. A. Al-Saadi, J. J. Orlando, A. J. Soja Jan 2011

The Fire Inventory From Ncar (Finn): A High Resolution Global Model To Estimate The Emissions From Open Burning, C. Wiedinmyer, S. K. Akagi, Robert J. Yokelson, L. K. Emmons, J. A. Al-Saadi, J. J. Orlando, A. J. Soja

Chemistry and Biochemistry Faculty Publications

The Fire INventory from NCAR version 1.0 (FINNv1) provides daily, 1 km resolution, global estimates of the trace gas and particle emissions from open burning of biomass, which includes wildfire, agricultural fires, and prescribed burning and does not include biofuel use and trash burning. Emission factors used in the calculations have been updated with recent data, particularly for the non-methane organic compounds (NMOC). The resulting global annual NMOC emission estimates are as much as a factor of 5 greater than some prior estimates. Chemical speciation profiles, necessary to allocate the total NMOC emission estimates to lumped species for use by …

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