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Articles 2341 - 2370 of 2757
Full-Text Articles in Biochemistry, Biophysics, and Structural Biology
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
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 …
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
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 …
Novel Perturbation Approach For The Structure Factor Of The Attractive Hard-Core Yukawa Fluid, Andrij Trokhymchuk, Roman Melnyk, Filip Moucka, Ivo Nezbeda
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) …
The Use Of Non-Natural Nucleotides To Probe Template-Independent Dna Synthesis, Anthony J. Berdis, David Mccutcheon
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 …
Compartmentalization Of Hiv-1 In The Secondary Lymphoid Tissues, James Peter Gregson
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 …
Fluorescent Photoinduced Electron Transfer (Pet) Proton Sensors, Risper Nyabeta
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.
Development Of Chemomechanical Functionalization And Nanografting On Silicon Surfaces, Michael Vernon Lee
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 …
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 …
Synthesis And Antiviral Evaluation Of Some 3'-Carboxymethyl-3'-Deoxyadenosine Derivatives, Houguang Shi
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 …
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
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 …
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
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.
Asymmetric Dihydroxylation And Aziridination Of Allenes And Related Chemistry, Renmao Liu
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 …
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
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 …
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 …
Sem Analysis Of Glue Behavior When Bonding Glass Structures With Complex Geometries, Yuri Sikorski, Robert Cunningham, Herman Orgeron, Chris Schenck, Ali Zand
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 …
Electronic Anisotropy Between Open Shell Atoms In First And Second Order Perturbation Theory, Gerrit C. Groenenboom, Xi Chu, R. Krems
Electronic Anisotropy Between Open Shell Atoms In First And Second Order Perturbation Theory, Gerrit C. Groenenboom, Xi Chu, R. Krems
Chemistry and Biochemistry Faculty Publications
The interaction between two atoms in states with nonzero electronic orbital angular momenta is anisotropic and can be represented by a spherical tensor expansion. The authors derive expressions for the first order (electrostatic) and second order (dispersion and induction) anisotropic interaction coefficients in terms of the multipole moments and dynamic polarizabilities of the atoms and show that a complete description of the second order interaction requires odd rank or "out-of-phase" polarizabilities. The authors relate the tensorial expansion coefficients to the adiabatic Born-Oppenheimer potentials of the molecule and show that there are linear, and in some cases nonlinear, constraints on the …
Kinetic Studies Of 6-Halopurine Nucleoside In Snar Reactions; 6-(Azolyl, Alkylthio And Fluoro)-Purine Nucleosides As Substrates For Suzuki Reactions, Jiangqiong Liu
Theses and Dissertations
In chapter 1, we describe development of a mild and efficient method for SNAr iodination of 6-chloropurine 2'-deoxynucleosides and nucleosides. Our studies demonstrate that 6-iodopurine nucleosides are excellent substrates for certain transition metal-catalyzed cross-coupling reactions. In chapter 2, we describe synthesis of protected 6-fluoro, 6-chloro, 6-bromo and 6-sulfonylpurine nucleosides. Comparisons among 6-fluoro-, 6-chloro-, 6-bromo, 6-iodo and 6-sulfonylpurine nucleosides for SNAr reactions with various N, O and S nucleophiles were investigated. Our results demonstrate that the 6-fluoropurine nucleoside is the best substrate for SNAr reactions among the four 6-halopurine nucleosides with oxygen, sulfur and aliphatic amine nucleophiles, and also with an …
Dna-Templated Nanomaterials, Hector Alejandro Becerril-Garcia
Dna-Templated Nanomaterials, Hector Alejandro Becerril-Garcia
Theses and Dissertations
Nanomaterials display interesting physical and chemical properties depending on their shape, size and composition. Self assembly is an intriguing route to producing nanomaterials with controllable compositions and morphologies. DNA has been used to guide the self assembly of materials, resulting in: (1) metal nanowires; (2) metal or semiconductor nanorods; (3) carbon nanotubes; and (4) semiconductor, metal or biological nanoparticles. My work expands the range of DNA templated nanomaterials and develops novel ways of using DNA to pattern nanostructures on surfaces. I have performed the first synthesis of silver nanorods on single stranded DNA, an attractive material for localizing DNA coupled …
Investigation Of Novel Microseparation Techniques, Yansheng Liu
Investigation Of Novel Microseparation Techniques, Yansheng Liu
Theses and Dissertations
Ultrahigh pressure liquid chromatography (UHPLC) makes it possible to use very small particles (< 2 µm) as packing materials to provide high column efficiencies. Results from a careful comparison of small porous and nonporous particles show that when the particle size is small enough (< 2 µm), both porous and nonporous particles give excellent performance, and the differences in column efficiencies between porous and nonporous particles become insignificant. Columns packed with bare diamond particles could separate small molecules, especially polar molecules, however, severe tailing occurred for less polar compounds. The polybutadiene coated diamond particles gave greater retention and better separation of small molecules compared to bare particles, although no improvement in column efficiency was observed. Changes in surface bonding of thermally hydrogenated diamond particles was achieved by chemical modification using various organic peroxides with or without reagents containing long carbon chain functional groups. It appears that the alkyl groups were attached onto the diamond surface with limited coverage. LC experiments did not demonstrate good separation; however, changes in LC behavior were observed. A repetitive solvent programming approach was successfully applied to the analysis of a continuous sample stream in microbore LC. Each analysis cycle consisted of three steps: pseudo-injection, elution and rinse. In the pseudo-injection step, elution with a non- or poor-eluting solvent produced a concentrated sample plug due to on-column focusing. Factors influencing peak symmetry, resolution and analysis cycle length were investigated. Quantitative analysis of a continuous sample stream is possible under certain operating conditions. Electric field gradient focusing (EFGF) devices with distributed resistor substrates could focus proteins in the separation channel, however, the focused bands were not stable, and the repeatability was poor due to the formation of bubbles and pH gradient in the separation channel. Both fiber-based and porous glass capillary-based planar EFGF devices with changing cross-sectional area (CCSA) channels were constructed and evaluated with the aid of a home-made scanning laser-induced fluorescence detection system. The fiber-based CCSA EFGF devices gave poorer performance compared with glass capillary based devices. Porous glass capillary-based EFGF devices could focus single proteins and separate mixtures of two to three proteins.
The Role Of Phosducin-Like Protein As A Co-Chaperone With The Cytosolic Chaperonin Complex In Assembly Of The G Protein Βγ Subunit Dimer, Paul Jayson Ludtke
The Role Of Phosducin-Like Protein As A Co-Chaperone With The Cytosolic Chaperonin Complex In Assembly Of The G Protein Βγ Subunit Dimer, Paul Jayson Ludtke
Theses and Dissertations
Phosducin-like protein (PhLP) has been shown to interact with the cytosolic chaperonin containing TCP-1 (CCT), and the βγ subunit dimer of heterotrimeric G proteins (Gβγ). Here we provide details obtained from cryo-electron microscopic and biochemical studies on the structure of the complex between the cytosolic chaperonin CCT and PhLP. Binding of PhLP to CCT occurs through only one of the two chaperonin rings, making multiple contacts with CCT through both its N- and C-terminal domains. In addition, we show that PhLP acts as a co-chaperonin along with CCT in mediating the assembly of the G protein βγ subunit and that …
Size Dependence Of Static And Dynamic Magnetic Properties In Nanoscale Square Permalloy Antidot Arrays, Minghui Yu, Leszek M. Malkinski, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg
Size Dependence Of Static And Dynamic Magnetic Properties In Nanoscale Square Permalloy Antidot Arrays, Minghui Yu, Leszek M. Malkinski, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg
Chemistry and Biochemistry Faculty Publications
Permalloy antidot arrays with different square hole sizes ( , , and ) have been fabricated by means of electron-beam lithography and lift-off techniques. The smaller square hole size results in enhanced remanence and reduced coercivity in the antidot array. Multiple resonance modes were clearly observed for the magnetic field applied normal to the array plane, and double uniform resonance modes occurred when the field deviated more than 30° from the normal to the plane. Two distinct dipolar field patterns with different orientations and magnitudes split the uniform resonance into double resonance modes. The double resonance modes show uniaxial in-plane …
The Niemann-Pick Type C2 Protein Loads Isoglobotrihexosylceramide Onto Cd1d Molecules And Contributes To The Thymic Selection Of Nkt Cells, Paul B. Savage, Nicolas Schrantz, Yuval Sagiv, Yang Liu, Albert Bendelac, Luc Teyton
The Niemann-Pick Type C2 Protein Loads Isoglobotrihexosylceramide Onto Cd1d Molecules And Contributes To The Thymic Selection Of Nkt Cells, Paul B. Savage, Nicolas Schrantz, Yuval Sagiv, Yang Liu, Albert Bendelac, Luc Teyton
Faculty Publications
The Niemann-Pick type C2 (NPC2) protein is a small, soluble, lysosomal protein important for cholesterol and sphingolipid transport in the lysosome. The immunological phenotype of NPC2-deficient mice was limited to an impaired thymic selection of Valpha 14 natural killer T cells (NKT cells) and a subsequent reduction of NKT cells in the periphery. The remaining NKT cells failed to produce measurable quantities of interferon-gamma in vivo and in vitro after activation with alpha-galactosylceramide. In addition, thymocytes and splenocytes from NPC2-deficient mice were poor presenters of endogenous and exogenous lipids to CD1d-restricted Valpha 14 hybridoma cells. Importantly, we determined that similar …
Pressure Dissociation Of Integration Host Factor-Dna Complexes Reveals Flexibility-Dependent Structural Variation At The Protein-Dna Interface, Donald F. Senear, Vira Tretyachenko-Ladokhina, Michael L. Opel, Kimberly A. Aeling, G. Wesley Hatfield, Laurie M. Franklin, Reuben C. Darlington, J. B. A. Ross
Pressure Dissociation Of Integration Host Factor-Dna Complexes Reveals Flexibility-Dependent Structural Variation At The Protein-Dna Interface, Donald F. Senear, Vira Tretyachenko-Ladokhina, Michael L. Opel, Kimberly A. Aeling, G. Wesley Hatfield, Laurie M. Franklin, Reuben C. Darlington, J. B. A. Ross
Chemistry and Biochemistry Faculty Publications
E. coli Integration host factor (IHF) condenses the bacterial nucleoid by wrapping DNA. Previously, we showed that DNA flexibility compensates for structural characteristics of the four consensus recognition elements associated with specific binding (Aeling et al., J. Biol. Chem. 281, 39236-39248, 2006). If elements are missing, high-affinity binding occurs only if DNA deformation energy is low. In contrast, if all elements are present, net binding energy is unaffected by deformation energy. We tested two hypotheses for this observation: in complexes containing all elements, (1) stiff DNA sequences are less bent upon binding IHF than flexible ones; or (2) DNA sequences …
Dynamic Polarizabilities Of Rare-Earth-Metal Atoms And Dispersion Coefficients For Their Interaction With Helium Atoms, Xi Chu, Alexander Dalgarno, Gerrit C. Groenenboom
Dynamic Polarizabilities Of Rare-Earth-Metal Atoms And Dispersion Coefficients For Their Interaction With Helium Atoms, Xi Chu, Alexander Dalgarno, Gerrit C. Groenenboom
Chemistry and Biochemistry Faculty Publications
The dynamic scalar and tensor polarizabilities of the rare-earth-metal atoms are calculated with time-dependent density functional theory. The frequency-dependent polarizabilities at imaginary frequencies are used to determine the isotropic and orientation-dependent van der Waals coefficients for the interactions of the rare-earth-metal atoms with helium atoms. The static polarizabilities are compared with other theoretical values and with experimental results. The agreement is satisfactory in most cases but there are some exceptions where the discrepancy between theory and experiment is significant. The derived isotropic van der Waals coefficients range between 37 and 50 E(H)a(0)(6) and the orientation-dependent coefficients between 2 and -1 …
Cost-Effective Engineering Of A Small-Scale Bioreactor, John Tansey, Sadie R. Bartholomew
Cost-Effective Engineering Of A Small-Scale Bioreactor, John Tansey, Sadie R. Bartholomew
Chemistry Faculty Scholarship
Several methods exist for increasing the scale of cell culture in the laboratory. While these methods provide significant increases in biomass, they are often prohibitively expensive for many laboratories. We have engineered a small-scale bioreactor with a novel means of introducing oxygen through the catalytic breakdown of hydrogen peroxide using a manganese oxide catalyst. We have also adapted and modified an existing assay for dissolved oxygen to be compatible with culture conditions. In this system we have been able to culture CHO cells at densities of up to 107 cells/mL without the use of automated feedback systems.
The Structure And Function Of Small Nucleolar Ribonucleoproteins, Steve Reichow, Tomoko Hamma, Adrian R. Ferré-D’Amaré, Gabriele Varani
The Structure And Function Of Small Nucleolar Ribonucleoproteins, Steve Reichow, Tomoko Hamma, Adrian R. Ferré-D’Amaré, Gabriele Varani
Chemistry Faculty Publications and Presentations
Eukaryotes and archaea use two sets of specialized ribonucleoproteins (RNPs) to carry out sequencespecific methylation and pseudouridylation of RNA, the two most abundant types of modifications of cellular RNAs. In eukaryotes, these protein–RNA complexes localize to the nucleolus and are called small nucleolar RNPs (snoRNPs), while in archaea they are known as small RNPs (sRNP). The C/D class of sno(s)RNPs carries out ribose- 20-O-methylation, while the H/ACA class is responsible for pseudouridylation of their RNA targets. Here, we review the recent advances in the structure, assembly and function of the conserved C/D and H/ACA sno(s)RNPs. Structures of each of the …
A Proposal For Robust Temperature Compensation Of Circadian Rhythms, Christian I. Hong, Emery D. Conrad, John J. Tyson
A Proposal For Robust Temperature Compensation Of Circadian Rhythms, Christian I. Hong, Emery D. Conrad, John J. Tyson
Dartmouth Scholarship
The internal circadian rhythms of cells and organisms coordinate their physiological properties to the prevailing 24-h cycle of light and dark on earth. The mechanisms generating circadian rhythms have four defining characteristics: they oscillate endogenously with period close to 24 h, entrain to external signals, suffer phase shifts by aberrant pulses of light or temperature, and compensate for changes in temperature over a range of 10°C or more. Most theoretical descriptions of circadian rhythms propose that the underlying mechanism generates a stable limit cycle oscillation (in constant darkness or dim light), because limit cycles quite naturally possess the first three …
Enhancing Fertiliser Use Efficiency For Transplanted Vegetables, Dennis Phillips, Aileen Reid, Gavin D'Adhemar
Enhancing Fertiliser Use Efficiency For Transplanted Vegetables, Dennis Phillips, Aileen Reid, Gavin D'Adhemar
Horticulture research reports
Horticulture Australia (HAL) Project No. VG04018.
Project VG 04018 ‘Enhancing fertiliser use efficiency for transplanted vegetables’ showed that spraying highly concentrated solutions containing nitrogen over newly transplanted vegetable seedlings for between 14 and 21 days after planting can increase marketable yields by as much as 300% compared to other methods of fertiliser application. Crops that this method has been successfully tested on in this study by the W.A. Department of Agriculture and Food include iceberg and Cos lettuce, broccoli, cauliflower, Chinese cabbage (wombok), celery and cabbage.
The research was conducted on virgin sandy soils of the Swan Coastal Plain near …
Strokes Of Existence: The Connection Of All Things, Mari Gorman
Strokes Of Existence: The Connection Of All Things, Mari Gorman
Graduate Student Publications and Research
Acted or real—and all life is real whether one is acting or not—the common denominator and consistent, ubiquitous reality of life and all behavior is that it manifests in the form of relationships on all scales. But what is a relationship? Until now, the answer to this question has not been sufficiently known. As a result of many years of empirical research that began with the aim of discovering what is going on in a gifted actor when s/he is playing a character that can be observed and experienced as a living, intuitive being, and based on the knowledge that …
Hydrophobic, Organically-Modified Silica Gels Enhance The Structure Of Encapsulated Apomyoglobin, Daryl K. Eggers, V. A. Rocha
Hydrophobic, Organically-Modified Silica Gels Enhance The Structure Of Encapsulated Apomyoglobin, Daryl K. Eggers, V. A. Rocha
Faculty Publications, Chemistry
Insertion of hydrophobic groups in a silica matrix, by addition of propyl- or trifluoropropyltrimethoxysilane, leads to a surprising increase in the helical content of apomyoglobin following encapsulation by the sol–gel technique