Open Access. Powered by Scholars. Published by Universities.®

Chemistry Commons™

Open Access. Powered by Scholars. Published by Universities.®

Life Sciences

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 3331 - 3360 of 3947

Full-Text Articles in Chemistry

Electrical Detection Of The Temperature Induced Melting Transition Of A Dna Hairpin Covalently Attached To Gold Interdigitated Microelectrodes, Greg P. Brewood, Yaswanth Rangineni, Daniel J. Fish, Ashwini Bhandiwad, David R. Evans, Raj Solanki, Albert S. Benight Jan 2008

Electrical Detection Of The Temperature Induced Melting Transition Of A Dna Hairpin Covalently Attached To Gold Interdigitated Microelectrodes, Greg P. Brewood, Yaswanth Rangineni, Daniel J. Fish, Ashwini Bhandiwad, David R. Evans, Raj Solanki, Albert S. Benight

Chemistry Faculty Publications and Presentations

The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5' end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, manner. The structural state of the hairpin was assessed by measuring four different electronic properties of the GIME (capacitance, impedance, dissipation factor and phase angle) as a function of temperature from 25 degrees C to 80 degrees C. Consistent changes in all four electronic properties of the GIME were observed over this temperature range, and attributed to the transition of the attached single-stranded DNA (ssDNA) from an intramolecular, folded …

Go to article

Lignin Degradation In Wood-Feeding Insects, Scott M. Geib, Timothy R. Filley, Patrick G. Hatcher, Kelli Hoover, John E. Carlson, Maria Del Mar Jimenez-Gasco, Akiko Nakagawa-Izumi, Rachel L. Sleighter, Ming Tien Jan 2008

Lignin Degradation In Wood-Feeding Insects, Scott M. Geib, Timothy R. Filley, Patrick G. Hatcher, Kelli Hoover, John E. Carlson, Maria Del Mar Jimenez-Gasco, Akiko Nakagawa-Izumi, Rachel L. Sleighter, Ming Tien

Chemistry & Biochemistry Faculty Publications

The aromatic polymer lignin protects plants from most forms of microbial attack. Despite the fact that a significant fraction of all lignocellulose degraded passes through arthropod guts, the fate of lignin in these systems is not known. Using tetramethylammonium hydroxide thermochemolysis, we show lignin degradation by two insect species, the Asian longhorned beetle (Anoplophora glabripennis) and the Pacific dampwood termite (Zootermopsis angusticollis). In both the beetle and termite, significant levels of propyl side-chain oxidation (depolymerization) and demethylation of ring methoxyl groups is detected; for the termite, ring hydroxylation is also observed. In addition, culture-independent fungal gut …

Go to article

Chemical Constituents And Biological Activity Of Three Tanzanian Wild Mushroom Species, L.D. Baraza, C. C. Joseph, M. J. Moshi, M. H. H. Nkunya Dec 2007

Chemical Constituents And Biological Activity Of Three Tanzanian Wild Mushroom Species, L.D. Baraza, C. C. Joseph, M. J. Moshi, M. H. H. Nkunya

Tanzania Journal of Science

The three Tanzanian wild mushroom species Termitomyces letestui, Lactarius edulis and Agaricus sp. aff. arvensis yielded ergosterol, 5,8-peroxyergosterol and ergosta-5,22-dien-3β-ol, and a mixture of ergosterol, ergosta-7,22-dien-3β-ol and ergosta-7-en-3β-ol whose composition was deduced from gas chromatography/mass spectroscopic (GC/MS) analysis of the trimethysilylated mixture. GC/MS analysis of the lipid fraction from T. letestu revealed the presence of linoleic (C18:2), stearic (C18:0), oleic (C18:1), palmitic (C16:0), pentadecanoic (C15:0) and myristic (C14:0) acid. Polar T. letestui and L. edulis fractions yielded α,α,1'trehalose andmannitol. Some of the crude extracts from the three mushroom species showed mild antimicrobial, mosquito larvicidal and cytotoxic activities. The chemical composition …

Go to article

Preparation Of Divalent And Trivalent Antigens For Immunogical Studies On Degranulation Of Mast Cells And Preparation Of Ceragenins For Antiviral Studies Against Vaccinia Virus., Dianliang Geng Dec 2007

Preparation Of Divalent And Trivalent Antigens For Immunogical Studies On Degranulation Of Mast Cells And Preparation Of Ceragenins For Antiviral Studies Against Vaccinia Virus., Dianliang Geng

Theses and Dissertations

CHAPTER 1

Aggregation of receptors for IgE (Fc RI) causes mast cells and basophils to release preformed contents of granules, including histamine and a variety of enzymes. This process, called degranulation plays a central role in allergic reactions. Methods to study this process are to create multivalent ligands which can interact with the receptors and, in turn, lead to aggregation of the receptors. We prepared a series of fluorophore-labeled divalent and trivalent antigens to study the degranulation of mast cells. Trivalent antigens proved to be much better stimulators for degranulation of mast cells than divalent antigens. These results indicate that …

Go to article

Pyridinium Bisretinoids: Synthesis And Photoactivated Cytotoxicity, Junping Gao Dec 2007

Pyridinium Bisretinoids: Synthesis And Photoactivated Cytotoxicity, Junping Gao

Theses and Dissertations

This thesis discusses pyridinium bisretinoid compounds (PBRs), which were prepared for two purposes: 1) to use them as standards for detection of novel fluorophores in human RPE cells, which may be involved in age-related macular degeneration (AMD), and 2) to use them in the development of a targeted and triggered drug delivery system for cancer therapy. We prepared a selection of PBRs using a one-pot biomimetic method; synthesis, mechanisms for formation, and characterization of these compounds is described. We also explored the photoreactivity of three novel PBR compounds and found that these PBRs form oxidation products under blue-light irradiation. The …

Go to article

Study Of The Reproducibility Of Proteomics Methods And Variability Of Fruit Fly Proteomes., Thomas Franklin Culwell Dec 2007

Study Of The Reproducibility Of Proteomics Methods And Variability Of Fruit Fly Proteomes., Thomas Franklin Culwell

Theses and Dissertations

The reliability of biomarker discovery by means of proteomics has been called into question. It was speculated that "background noise" variation resulting from differences in preparation and handling of samples and proteome dynamics may mask subtle, yet important, differences due to the biological condition. Little is understood about complex proteomes and their variability. A critical aspect of proteomic biomarker research that is largely unexplored is the comparative reproducibility of certain methods such as two-dimensional gel electrophoresis and liquid chromatography/mass spectrometry. In particular, with liquid chromatography/mass spectrometry, it is not known whether variability in peptide quantitation is dependent on any of …

Go to article

Pyridinium Bis-Retinoids A2-Dopamine And A2-Cadaverine: Implications In Age-Related Macular Degeneration And Cancer, Mckenzie Ruth Pew Dec 2007

Pyridinium Bis-Retinoids A2-Dopamine And A2-Cadaverine: Implications In Age-Related Macular Degeneration And Cancer, Mckenzie Ruth Pew

Theses and Dissertations

Age-related macular degeneration (AMD) is the leading cause of blindness in the United States of America. The pyridinium bis-retinoid A2-ethanolamine (A2E) has been implicated to play a role in AMD. We have observed novel pyridinium bis-retinoids through melanolipofuscin and human RPE extractions that may also play a role in the pathology of AMD. We have begun the construction of an amino-retinoid library in order to identify these ocular compounds. The compounds from the amino-retinoid library are also used in a targeted and triggered drug delivery system for treating cancer. Folic acid is coupled with the amino-retinoids to specifically target cancer …

Go to article

Effects Of Water Vapor On The Kinetics Of The Methylperoxy Radical Self-Reaction And Reaction With Hydroperoxy, Alecia Mower Dec 2007

Effects Of Water Vapor On The Kinetics Of The Methylperoxy Radical Self-Reaction And Reaction With Hydroperoxy, Alecia Mower

Theses and Dissertations

The gas phase reactions of CH3O2 + CH3O2, HO2 + HO2, and CH3O2 + HO2 in the presence of water vapor have been studied at temperatures between 263 and 303 K using laser flash photolysis coupled with UV time-resolved absorption detection at 220 nm and 260 nm. Water vapor concentration was quantified using tunable diode laser spectroscopy operating in the mid-IR. The HO2 self-reaction rate constant is significantly enhanced by water vapor, consistent with what others have reported, whereas CH3O2 self-reaction and the cross-reaction (CH3O2 + HO2) rate constants are nearly unaffected. The enhancement in the HO2 self-reaction rate coefficient …

Go to article

Prevention Of Staphylococcus Epidermidis Biofilm Formation Using A Low-Temperature Processed Silver-Doped Phenyltriethoxysilane Sol–Gel Coating, Niall Stobie, Brendan Duffy, Declan Mccormack, John Colreavy, Martha Hidalgo, Patrick Mchale, Steven Hinder Dec 2007

Prevention Of Staphylococcus Epidermidis Biofilm Formation Using A Low-Temperature Processed Silver-Doped Phenyltriethoxysilane Sol–Gel Coating, Niall Stobie, Brendan Duffy, Declan Mccormack, John Colreavy, Martha Hidalgo, Patrick Mchale, Steven Hinder

Articles

Sol–gel coatings which elute bioactive silver ions are presented as a potential solution to the problem of biofilm formation on indwelling surfaces. There is evidence that high-temperature processing of such materials can lead to diffusion of silver away from the coating surface, reducing the amount of available silver. In this study, we report the biofilm inhibition of a Staphylococcus epidermidis biofilm using a low-temperature processed silver-doped phenyltriethoxysilane sol–gel coating. The incorporation of a silver salt into a sol–gel matrix resulted in an initial high release of silver in de-ionised water and physiological buffered saline (PBS), followed by a lower sustained …

Go to article

The Tropical Forest And Fire Emissions Experiment: Method Evaluation Of Volatile Organic Compound Emissions Measured By Ptr-Ms, Ftir, And Gc From Tropical Biomass Burning, T. G. Karl, Ted J. Christian, Robert J. Yokelson, Paulo Artaxo, Wei Min Hao, Alex Guenther Nov 2007

The Tropical Forest And Fire Emissions Experiment: Method Evaluation Of Volatile Organic Compound Emissions Measured By Ptr-Ms, Ftir, And Gc From Tropical Biomass Burning, T. G. Karl, Ted J. Christian, Robert J. Yokelson, Paulo Artaxo, Wei Min Hao, Alex Guenther

Chemistry and Biochemistry Faculty Publications

Volatile Organic Compound (VOC) emissions from fires in tropical forest fuels were quantified using Proton-Transfer-Reaction Mass Spectrometry (PTRMS), Fourier Transform Infrared Spectroscopy (FTIR) and gas chromatography (GC) coupled to PTRMS (GC-PTR-MS). We investigated VOC emissions from 19 controlled laboratory fires at the USFS (United States Forest Service) Fire Sciences Laboratory and 16 fires during an intensive airborne field campaign during the peak of the burning season in Brazil in 2004. The VOC emissions were dominated by oxygenated VOCs (OVOC) (OVOC/NMHC similar to 4:1, NMHC: non-methane hydrocarbons) The specificity of the PTR-MS instrument, which measures the mass to charge ratio of …

Go to article

1,3,7,10,14,17,21,28,31,42,52,55-Dodeca­Kis(Trifluoro­Meth­Yl)- 1,3,7,10,14,17,21,28,31,42,52,55-Dodeca­Hydro­(C60-IH)[5,6]Fullerene, Natalia B. Shustova Prof. Dr., O.P. Anderson, O. V. Boltalina, S. H. Strauss, I. E. Kareev Nov 2007

1,3,7,10,14,17,21,28,31,42,52,55-Dodeca­Kis(Trifluoro­Meth­Yl)- 1,3,7,10,14,17,21,28,31,42,52,55-Dodeca­Hydro­(C60-IH)[5,6]Fullerene, Natalia B. Shustova Prof. Dr., O.P. Anderson, O. V. Boltalina, S. H. Strauss, I. E. Kareev

Faculty Publications

The title compound, C72F36, is one of four isomers of C60(CF3)12 for which crystal structures have been obtained. The fullerene mol­ecule has an idealized Ih C60 core with the 12 CF3 groups arranged in an asymmetric fashion on two ribbons of edge-sharing C6(CF3)2 hexa­gons, a para–meta–para–para–para–meta–para ribbon and a para–meta–para ribbon, giving an overall pmp 3 mp,pmp structure. There are no cage Csp 3 …

Go to article

Microchip Liquid Chromatography And Capillary Electrophoresis Separations In Multilayer Microdevices, Hernan Vicente Fuentes Nov 2007

Microchip Liquid Chromatography And Capillary Electrophoresis Separations In Multilayer Microdevices, Hernan Vicente Fuentes

Theses and Dissertations

In this dissertation, several microfabricated devices are introduced to develop new applications in the area of chemical analysis. Electrochemical micropumps, chip-based liquid chromatography systems and multilayer capillary electrophoresis microdevices with crossover channels were fabricated using various substrates such as poly(dimethylsiloxane) (PDMS), glass, and poly(methyl methacrylate) (PMMA). I have demonstrated pressure-driven pumping of liquids in microfabricated channels using electrochemical actuation. PDMS-based micropumps were integrated easily with channel-containing PMMA substrates. Flow rates on the order of ~10 µL/min were achieved using low voltages (10 V). The potential of electrolysis-based pumping in microchannels was further evaluated for pressure driven microchip liquid chromatography (LC). …

Go to article

Microfluidic Electro-Osmotic Flow Pumps, John Mason Edwards Nov 2007

Microfluidic Electro-Osmotic Flow Pumps, John Mason Edwards

Theses and Dissertations

The need for miniaturized, portable devices to separate and detect unknown compounds has greatly multiplied, leading to an increased interest in microfluidics. Total integration of the detector and pump are necessary to decrease the overall size of the microfluidic device. Using previously developed thin film technologies, an electroosmotic flow (EOF) pump was incorporated in a microfluidic liquid chromatography device. An EOF pump was chosen because of its simple design and small size. EOF pumps fabricated on silicon and glass substrates were evaluated. The experimental flow rates were 0.19-2.30 microliters/minute for 40-400 V. The theoretical pump efficiency was calculated along with …

Go to article

Counter-Flow Ion Mobility Analysis: Design, Instrumentation, And Characterization, Nosa Agbonkonkon Nov 2007

Counter-Flow Ion Mobility Analysis: Design, Instrumentation, And Characterization, Nosa Agbonkonkon

Theses and Dissertations

The quest to achieve high resolution in ion mobility spectrometry (IMS) has continued to challenge scientist and engineers in the field of separation science. The low resolution presently attainable in IMS has continued to negatively impact its utility and acceptance. Until now, efforts to improve the resolution have mainly focused on better instrumentation and detection methods. However, since the resolution of IMS is diffusion limited, it makes sense to address this limitation in order to attain high resolution. This dissertation presents a new IMS technique, which utilizes a high electric field and opposing high gas flow velocity with the aim …

Go to article

Optimization Of Non-Natural Nucleotides For Selective Incorporation Opposite Damaged Dna, Diana Vineyard, Xuemei Zhang, Alison Donnelley, Irene Lee, Anthony J. Berdis Oct 2007

Optimization Of Non-Natural Nucleotides For Selective Incorporation Opposite Damaged Dna, Diana Vineyard, Xuemei Zhang, Alison Donnelley, Irene Lee, Anthony J. Berdis

Chemistry Faculty Publications

The promutagenic process known as translesion DNA synthesis reflects the ability of a DNA polymerase to misinsert a nucleotide opposite a damaged DNA template. To study the underlying mechanism of nucleotide selection during this process, we quantified the incorporation of various non-natural nucleotide analogs opposite an abasic site, a non-templating DNA lesion. Our kinetic studies using the bacteriophage T4 DNA polymerase reveal that the π-electron surface area of the incoming nucleotide substantially contributes to the efficiency of incorporation opposite an abasic site. A remaining question is whether the selective insertion of these non-hydrogen-bonding analogs can be achieved through optimization of …

Go to article

The Tropical Forest And Fire Emissions Experiment: Trace Gases Emitted By Smoldering Logs And Dung From Deforestation And Pasture Fires In Brazil, Ted J. Christian, Robert J. Yokelson, João A. Carvalho, David W.T. Griffith, Ernesto C. Alvarado, José Carlos Santos, Turibio Gomes Soares Neto, Carlos A.Gurgel Veras, Wei Min Hao Sep 2007

The Tropical Forest And Fire Emissions Experiment: Trace Gases Emitted By Smoldering Logs And Dung From Deforestation And Pasture Fires In Brazil, Ted J. Christian, Robert J. Yokelson, João A. Carvalho, David W.T. Griffith, Ernesto C. Alvarado, José Carlos Santos, Turibio Gomes Soares Neto, Carlos A.Gurgel Veras, Wei Min Hao

Chemistry and Biochemistry Faculty Publications

Earlier work showed that Amazonian biomass burning produces both lofted and initially unlofted emissions in large amounts. A mobile, Fourier transform infrared spectrometer (FTIR) measured the unlofted emissions of 17 trace gases from residual smoldering combustion (RSC) of logs as part of the Tropical Forest and Fire Emissions Experiment (TROFFEE) during the 2004 Amazonian dry season. The RSC emissions were highly variable and the few earlier RSC measurements lay near the high end of combustion efficiency observed in this study. Fuel consumption by RSC was ∼5% of total for a planned deforestation fire. Much regional RSC probably occurs in the …

Go to article

The Tropical Forest And Fire Emissions Experiment: Emission, Chemistry, And Transport Of Biogenic Volatile Organic Compounds In The Lower Atmosphere Over Amazonia, Thomas Karl, Alex Guenther, Robert J. Yokelson, Jim Greenberg, Mark Potosnak, Donald R. Blake, Paulo Artaxo Sep 2007

The Tropical Forest And Fire Emissions Experiment: Emission, Chemistry, And Transport Of Biogenic Volatile Organic Compounds In The Lower Atmosphere Over Amazonia, Thomas Karl, Alex Guenther, Robert J. Yokelson, Jim Greenberg, Mark Potosnak, Donald R. Blake, Paulo Artaxo

Chemistry and Biochemistry Faculty Publications

Airborne and ground-based mixing ratio and flux measurements using eddy covariance (EC) and for the first time the mixed layer gradient (MLG) and mixed layer variance (MLV) techniques are used to assess the impact of isoprene and monoterpene emissions on atmospheric chemistry in the Amazon basin. Average noon isoprene (7.8 +/- 2.3 mg/m(2)/h) and monoterpene fluxes (1.2 +/- 0.5 mg/m(2)/h)compared well between ground and airborne measurements and are higher than fluxes estimated in this region during other seasons. The biogenic emission model, Model of Emissions of Gases and Aerosols from Nature (MEGAN), estimates fluxes that are within the model and …

Go to article

Novel Perturbation Approach For The Structure Factor Of The Attractive Hard-Core Yukawa Fluid, Andrij Trokhymchuk, Roman Melnyk, Filip Moucka, Ivo Nezbeda Sep 2007

Novel Perturbation Approach For The Structure Factor Of The Attractive Hard-Core Yukawa Fluid, Andrij Trokhymchuk, Roman Melnyk, Filip Moucka, Ivo Nezbeda

Faculty Publications

A novel perturbation approach for the structure factor S(k) of the Lennard-Jones-type Yukawa fluid with z=1.8 is presented. An approach is based on a new reference system, that is, the short-range Yukawa model with z0 > z=1.8. By choosing for the reference system the value z0=6, it is shown that (i) the proposed approach for S(k) performs much better than the traditional hard-sphere reference perturbation method does; (ii) the use of an approximate mean spherical (MSA) description of the reference structure factor provides the results for S(k) that are more accurate as those obtained from the direct MSA computations; and (iii) …

Go to article

The Use Of Non-Natural Nucleotides To Probe Template-Independent Dna Synthesis, Anthony J. Berdis, David Mccutcheon Aug 2007

The Use Of Non-Natural Nucleotides To Probe Template-Independent Dna Synthesis, Anthony J. Berdis, David Mccutcheon

Chemistry Faculty Publications

The vast majority of DNA polymerases use the complementary templating strand of DNA to guide each nucleotide incorporation. There are instances, however, in which polymerases can efficiently incorporate nucleotides in the absence of templating information. This process, known as translesion DNA synthesis, can alter the proper genetic code of an organism. To further elucidate the mechanism of template-independent DNA synthesis, we monitored the incorporation of various nucleotides at the “blunt-end” of duplex DNA by the high-fidelity bacteriophage T4 DNA polymerase. Although natural nucleotides are not incorporated at the blunt-end, a limited subset of non-natural indolyl analogues containing extensive π-electron surface …

Go to article

Compartmentalization Of Hiv-1 In The Secondary Lymphoid Tissues, James Peter Gregson Aug 2007

Compartmentalization Of Hiv-1 In The Secondary Lymphoid Tissues, James Peter Gregson

Theses and Dissertations

Follicular dendritic cells (FDCs) reside in the lymphoid follicles of the secondary lymphoid tissues (sLTs). Following the infection of an individual with human immunodeficiency virus type 1 (HIV-1), viral particles are trapped in massive quantities on the surfaces of FDCs. HIV-1 viral compartments are cell types or tissues between which there is a restriction of virus flow. Compartmentalization of HIV-1 creates numerous sites within the body in which the virus can undergo independent evolution, giving rise to a more diverse total viral population. Given the sessile nature of the FDC, I hypothesized that contrary to common assumptions, FDC-trapped HIV-1 is …

Go to article

Fluorescent Photoinduced Electron Transfer (Pet) Proton Sensors, Risper Nyabeta Aug 2007

Fluorescent Photoinduced Electron Transfer (Pet) Proton Sensors, Risper Nyabeta

Theses, Dissertations and Culminating Projects

Two new fluorescent photoinduced electron transfer (PET) proton sensors based on anthracene and pyrazoline chromophores have been prepared. The anthracene sensor was prepared through alkylation of 2-pyridylcarbinol with 9-chloromethylanthracene and the pyrazoline sensor was prepared through an aldol condensation of 4- carboxybenzaldehyde and acetylpyridine followed by reaction with phenylhydrazine. The fluorescence of these sensors is modulated by the initiation or quenching of a PET process between the chromophore and a receptor due to protonation. The synthesis, characterization and proton binding studies of the new sensors are reported in this thesis.

Go to article

Development Of Chemomechanical Functionalization And Nanografting On Silicon Surfaces, Michael Vernon Lee Jul 2007

Development Of Chemomechanical Functionalization And Nanografting On Silicon Surfaces, Michael Vernon Lee

Theses and Dissertations

Progress in chemomechanical functionalization was made by investigating the binding of molecules and surface coverage on the silicon surface, demonstrating functionalization of silicon with gases by chemomechanical means, analyzing atomic force microscopy probe tip wear in atomic force microscopy (AFM) chemomechanical nanografting, combining chemomechanical functionalization and nanografting to pattern silicon with an atomic force microscope, and extending chemomechanical nanografting to silicon dioxide. Molecular mechanics of alkenes and alkynes bound to Si(001)-2x1 as a model of chemomechanically functionalized surfaces indicated that complete coverage is energetically favorable and becomes more favorable for longer chain species. Scribing a silicon surface in the presence …

Go to article

Synthesis Of Resveratrol And Its Analogs, Phase-Transfer Catalyzed Asymmetric Glycolate Aldol Reaction, And Total Synthesis Of 8,9-Methylamido-Geldanamycin, Jing Liu Jul 2007

Synthesis Of Resveratrol And Its Analogs, Phase-Transfer Catalyzed Asymmetric Glycolate Aldol Reaction, And Total Synthesis Of 8,9-Methylamido-Geldanamycin, Jing Liu

Theses and Dissertations

The phytoalexin resveratrol and its acetyl analogs have been made using a decarbonylative Heck reaction. The acid chloride derived from 3,5-dihydroxybenzoic acid was coupled with suitable protected 4-hydroxystyrene in the presence of palladium acetate and N,N-bis-(2,6-diisopropylphenyl)-4,5-dihydro imidazolium chloride to give the substituted stilbene in good yield as the key step. Human HL-60 cell assays showed the 4'-acetyl resveratrol variant improved activity (ED50 17 μM) relative to resveratrol (24 μM). Cinchona phase-transfer catalysts (PTC) were developed for glycolate aldol reactions to give differentially protected 1,2-diol products. Silyl enol ether of diphenylmethoxy-2,5-dimethoxyacetophenone reacted to generate benzhydryl-protected products. O-Allyl trifluorobenzyl cinchonium hydrodifluoride (20 …

Go to article

Synthesis And Antiviral Evaluation Of Some 3'-Carboxymethyl-3'-Deoxyadenosine Derivatives, Houguang Shi Jul 2007

Synthesis And Antiviral Evaluation Of Some 3'-Carboxymethyl-3'-Deoxyadenosine Derivatives, Houguang Shi

Theses and Dissertations

3'-Carboxymethyl-3'-deoxyadenosine derivatives were prepared from 2'-O-TBDMS-3'-deoxy-3'-[(ethoxycarbonyl)methyl]adenosine (1) via simple and efficient procedures. Conversion of 1 to 5'-azido-2'-O-TBDMS-3', 5'-dideoxy -3'-[(ethoxycarbonyl) methyl] adenosine (4) was accomplished via a novel one-pot method employing 5'-activation (TosCl) followed by efficient nucleophilic displacement with tetramethylguanidinium azide. Compound 4 was converted to a 5'-[(N-methylcarbamoyl)amino] derivative (5) via one-pot reduction/acylation employing H2/Pd-C followed by treatment with p-nitrophenyl N-methylcarbamate. The latter step of this two-step process required an efficient source of p-nitrophenyl N-methylcarbamate, thus a highly efficient new method for preparing p-nitrophenyl N-alkylcarbamate was developed. N6-phenylcarbamoyl groups were introduced by treatment with phenylisocyanate, and an efficient new method for …

Go to article

Regulation Of Cell Diameter, For3p Localization, And Cell Symmetry By Fission Yeast Rho-Gap Rga4p, Maitreyi Das, David J. Wiley, Saskia Medina, Helen A. Vincent, Michelle D. Larrea, Andrea Oriolo, Fulvia Verde Jun 2007

Regulation Of Cell Diameter, For3p Localization, And Cell Symmetry By Fission Yeast Rho-Gap Rga4p, Maitreyi Das, David J. Wiley, Saskia Medina, Helen A. Vincent, Michelle D. Larrea, Andrea Oriolo, Fulvia Verde

Chemistry and Physics Faculty Articles

Control of cellular dimensions and cell symmetry are critical for development and differentiation. Here we provide evidence that the putative Rho-GAP Rga4p of Schizosaccharomyces pombe controls cellular dimensions. rga4Δ cells are wider in diameter and shorter in length, whereas Rga4p overexpression leads to reduced diameter of the growing cell tip. Consistent with a negative role in cell growth control, Rga4p protein localizes to the cell sides in a “corset” pattern, and to the nongrowing cell tips. Additionally, rga4Δ cells show an altered growth pattern similar to that observed in mutants of the formin homology protein For3p. Consistent with …

Go to article

Human Frataxin: Iron And Ferrochelatase Binding Surface, Krisztina Z. Bencze, Taejin Yoon, CéSar MilláN-Pacheco, Patrick B. Bradley, Nina Pastor, J. A. Cowan, Timothy L. Stemmler May 2007

Human Frataxin: Iron And Ferrochelatase Binding Surface, Krisztina Z. Bencze, Taejin Yoon, CéSar MilláN-Pacheco, Patrick B. Bradley, Nina Pastor, J. A. Cowan, Timothy L. Stemmler

Biochemistry and Molecular Biology Faculty Publications

The coordinated iron structure and ferrochelatase binding surface of human frataxin have been characterized to provide insight into the protein’s ability to serve as the iron chaperone during heme biosynthesis.

Go to article

Asymmetric Dihydroxylation And Aziridination Of Allenes And Related Chemistry, Renmao Liu May 2007

Asymmetric Dihydroxylation And Aziridination Of Allenes And Related Chemistry, Renmao Liu

Theses and Dissertations

A novel method for asymmetric synthesis of α-hydroxy ketone with excellent regio- and stereoselectivity has been established by the systematic investigation of asymmetric dihydroxylation of allenes. The efficiency of kinetic resolution of racemic allenes was also investigated by using the AD reaction on both 1,3-disubstituted and trisubstituted allenes. Steric effects, electronic effects and allene substitution are also discussed. Aziridines were formed by copper-catalyzed intramolecular nitrene addition to alkenes. The carbamate group was used as the tether between the alkene and the nitrene. Subsequent nucleophilic attack of the aziridine was accomplished using RSH, R2NH, N3-,or ROH as the nucleophile. This addition …

Go to article

Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Vovk, Donald J. Scherer Ii, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg, Zachary Davis, Jin-Seung Jung May 2007

Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Vovk, Donald J. Scherer Ii, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg, Zachary Davis, Jin-Seung Jung

Chemistry and Biochemistry Faculty Publications

Arrays consisting of nanosized stripes of Permalloy with different length-to-width ratios have been fabricated using electron beam nanolithography, magnetron sputtering, and lift-off process. These stripes have a thickness of , a width of , and different lengths ranging from . The stripes are separated by a distance of . Magnetization hysteresis loops were measured using a superconducting quantum interference device susceptometer. Microwave absorption at was determined by means of ferromagnetic resonance technique. The dependence of the resonant field on the angle between the nanostructure and the in-plane dc magnetic field indicates the presence of uniaxial magnetic anisotropy associated with the …

Go to article

Towards Early State Disease Detection In Microdevices: Fabrication And Testing Of Micro Total Analysis Systems For Bioanalytical Applications, Tao Pan May 2007

Towards Early State Disease Detection In Microdevices: Fabrication And Testing Of Micro Total Analysis Systems For Bioanalytical Applications, Tao Pan

Theses and Dissertations

The past few years have seen a rapid expansion in interest in the characterization of the entire complement of proteins, or proteome. Micro total analysis systems (μTAS) are an emerging promising method, offering rapid, sensitive and low sample consumption separations. I have demonstrated microchip capillary electrophoresis (CE) devices made of CaF2. New methods have been developed for micromachining enclosed capillaries in CaF2. CE analysis of fluorescently labeled amino acids was used to illustrate bioanalytical applications of these microdevices. Initial on-chip infrared spectroscopy results for qualitative analyte identification were achieved in microfluidic CaF2 channels. I have also shown the evaluation of …

Go to article

Sem Analysis Of Glue Behavior When Bonding Glass Structures With Complex Geometries, Yuri Sikorski, Robert Cunningham, Herman Orgeron, Chris Schenck, Ali Zand May 2007

Sem Analysis Of Glue Behavior When Bonding Glass Structures With Complex Geometries, Yuri Sikorski, Robert Cunningham, Herman Orgeron, Chris Schenck, Ali Zand

Chemistry & Biochemistry Presentations And Conference Materials

Bonding of glass has been studied for many years and is a mature technology today. However, the recent advances in bio-photonics and micro-fluidics, such as lab-on-a-chip devices, accentuate a need to provide reliable adhesion and sealing of components with extremely complex surface geometries. In many cases it is necessary to prevent the adhesives from leaking into microscopic channels, capillaries and holes. We present the Scanning Electron Microscopy study of adhesion of glass samples with complex surface features. Variety of adhesion conditions and procedures were tried and studied. The results demonstrate the possibility of controlled reliable adhesion and sealing without filling/obstructing …

Go to article

First Prev Next Last