Biochemistry Commons^™

Calcium Binding To Calmodulin Mutants Monitored By Domain-Specific Intrinsic Phenylalanine And Tyrosine Fluorescence, W. S. Vanscyoc, B. R. Sorensen, E. Rusinova, William Laws, J. B. A. Ross, M. A. Shea

Chemistry and Biochemistry Faculty Publications

Cooperative calcium binding to the two homologous domains of calmodulin (CaM) induces conformational changes that regulate its association with and activation of numerous cellular target proteins. Calcium binding to the pair of high-affinity sites (III and IV in the C-domain) can be monitored by observing calcium-dependent changes in intrinsic tyrosine fluorescence intensity (lambda(ex)/lambda(em) of 277/320 nm). However, calcium binding to the low-affinity sites (I and II in the N-domain) is more difficult to measure with optical spectroscopy because that domain of CaM does not contain tryptophan or tyrosine. We recently demonstrated that calcium-dependent changes in intrinsic phenylalanine fluorescence (lambdaex/lambdaem of …

Guanine And 7,8-Dihydro-8-Oxo-Guanine-Specific Oxidation In Dna By Chromium(V), Kent D. Sugden, Brooke Martin

Chemistry and Biochemistry Faculty Publications

The hexavalent oxidation state of chromium [Cr(VI)] is a well-established human carcinogen, although the mechanism of cancer induction is currently unknown. Intracellular reduction of Cr(VI) forms Cr(V), which is thought to play a fundamental role in the mechanism of DNA damage by this carcinogen. Two separate pathways of DNA damage, an oxidative pathway and a metal-binding pathway, have been proposed to account for the lesions observed in cell systems. We have used a model Cr(V) complex, N,N´-ethylenebis(salicylidene-animato)oxochromium(V) [Cr(V)-Salen], to investigate the oxidative pathway of DNA damage and to elucidate the lesions generated from this oxidation process. Reaction of Cr(V)-Salen with …

Monte Carlo Simulation On The Indirect Exchange Interactions Of Co-Doped Zno Film, Abraham F. Jalbout, Hanning Chen, Scott L. Whittenburg

Chemistry and Biochemistry Faculty Publications

Monte Carlo simulations using a three-dimensional lattice model studied the Ruderman–Kittel–Kasuya–Yosida (RKKY) indirect exchange interaction of doped magnetic Co ions in ZnOfilms. The results of the calculations show that the RKKY interaction in Co-doped ZnO is long ranged and its magnitude is proportional to (inverse of the distance from a central ion). The sign oscillates with a frequency that depends on the concentration of the carrier. The long-distance sum of the RKKY indirect exchange energies is positive indicating that these materials are ferromagnetic, in direct correlation with previously reported results.

Comparison Of Water Quality, Zooplankton Density, And Cover In Razorback Sucker (Xyrauchen Texanus [Abbott]) Spawning Areas Of Lake Mead And Lake Mohave, Michael E. Golden, Paul B. Holden, Southern Nevada Water Authority

Publications (WR)

Las Vegas Bay and Echo Bay in Lake Mead have small, self-sustaining populations of razorback sucker (Xyrauchen texanus [Abbot]). Increased productivity and cover have been hypothesized as reasons for successful recruitment of razorback sucker in Lake Mead. Conversely, reproduction has been documented on Lake Mohave, another lower Colorado River reservoir, but no recruitment has been observed. In 2000, BIO-WEST, Inc. was contracted by the Southern Nevada Water Authority to design and implement a study to examine nutrient levels, zooplankton density, and cover in areas with and without razorback sucker recruitment success. We sampled Echo Bay, Las Vegas Bay, and …

Magnetization Reversal Of Elliptical Co/Cu/Co Pseudo-Spin Valve Dots, Ngocnga Dao, Scott L. Whittenburg, Y. Hao, Leszek M. Malkinski, Jian Qing Wang, C. A. Ross

Chemistry and Biochemistry Faculty Publications

We present our recent simulated results on Cr (5 nm)/ Cu (5 nm)/ Co (5 nm)/ Cu (3 nm)/ Co (2 nm) pseudo-spin valve dots. The simulated results agree qualitatively with the experimental results. Three different sizes of elliptical dots, and were simulated. Our simulations show that in these types of dots magnetization reversal occurs by the formation of domain walls: for and for No domain wall was observed in the reversal of the dots. For such dots, the simulated loops show a small two-step reversal pattern with the thin upper layer partially reversing followed by complete reversal of both …

1080 Summary Information, Department Of Agriculture, Western Australia, Department Of Conservation And Land Management, Western Australia, Department Of Health, Western Australia

Biosecurity research reports

Fluoroacetate, the active ingredient of 1080, occurs naturally in toxic plants in Australia, South Africa, and South America. Manufactured I080 underpins most vertebrate pest control programs in Australia and New Zealand. Fluoroacetate occurs naturally in about 40 plant species in Australia with most of these plants restricted to the south-west of WA.

I080 was introduced to rabbit control programs in the early 1950s and therefore has a long history of proven effectiveness and safety in Australia. There have been few repo1ted problems associated with human safety, environmental persistence, bioaccumulation or impact on populations of non-target species.

In particular, I080 baits …

The Southern African Regional Science Initiative (Safari 2000): Overview Of The Dry Season Field Campaign, R. J. Swap, H. J. Annegarn, J. T. Suttles, J. Haywood, M. C. Helmlinger, C. Hely, Peter V. Hobbs, B. N. Holben, J. Ji, M. D. King, T. Landmann, W. Maenhaut, L. Otter, B. Pak, S. J. Piketh, S. Platnick, J. Privette, D. Roy, A. M. Thompson, Darold E. Ward, Robert J. Yokelson

Chemistry and Biochemistry Faculty Publications

The Southern African Regional Science Initiative (SAFARI 2000) is an international science project investigating the earth-atmosphere-human system in southern Africa. The programme was conducted over a two-year period from March 1999 to March 2001. The dry season field campaign (August-September 2000) was the most intensive activity and involved over 200 scientists from eighteen countries. The main objectives were to characterize and quantify biogenic, pyrogenic and anthropogenic aerosol and trace gas emissions and their transport and transformations in the atmosphere, and to validate NASA's Earth Observing System's satellite Terra within a scientific context. Five aircraft - two South African Weather Service …

Production Of A Monoclonal Antibody Against Benzo[Α]Pyrene Diol Epoxide Dna Adducts, Brian Peden Austin

Chemistry & Biochemistry Theses & Dissertations

Benzo[α]pyrene is a ubiquitous pollutant produced from the incomplete combustion of organic material such as fossil fuels. It is found in the workplace, urban air, drinking water, and the food supply. Recently, it has been proposed that benzo[α]pyrene may be the causative agent in the formation of lung adenocarcinomas among some Taiwanese women exposed to cooking oil fumes without adequate ventilation. In this study, calf thymus DNA was modified in vitro with benzo[α]pyrene-diol epoxide (BPDE) to a level consistent with that found in biological samples. This DNA of low modification was used as an immunogen in the production of a …

Familial Als-Associated Mutations Decrease The Thermal Stability Of Distinctly Metallated Species Of Human Copper/Zinc Superoxide Dismutase, Daryl K. Eggers, J. A. Rodriguez, J. S. Valentine, J. A. Roe, A. Tiwari, R. H. Brown, L. J. Hayward

Faculty Publications, Chemistry

We report the thermal stability of wild type (WT) and 14 different variants of human copper/zinc superoxide dismutase (SOD1) associated with familial amyotrophic lateral sclerosis (FALS). Multiple endothermic unfolding transitions were observed by differential scanning calorimetry for partially metallated SOD1 enzymes isolated from a baculovirus system. We correlated the metal ion contents of SOD1 variants with the occurrence of distinct melting transitions. Altered thermal stability upon reduction of copper with dithionite identified transitions resulting from the unfolding of copper-containing SOD1 species. We demonstrated that copper or zinc binding to a subset of “WT-like” FALS mutants (A4V, L38V, G41S, G72S, D76Y, …

Calorimetric Study Of Block-Copolymers Of Poly(N-Butyl Acrylate) And Gradient Poly(N-Butyl Acrylate-Co-Methyl Methacrylate), A I. Buzin, M Pyda, P Costanzo, K Matyjaszewski, B Wunderlich

Chemistry and Biochemistry

The nanophase separation in diblock and triblock copolymers consisting of immiscible poly(n-butyl acrylate) (block A) and gradient copolymers of methyl methacrylate (MMA) and n-butyl acrylate (n BA) (block M/A) were investigated by means of their heat capacity, C_p, as a function of the composition of the blocks M/A and temperature. In all copolymers studied, both blocks are represented by their C_p and glass transition temperature, T_g, as well as the broadening of the transition-temperature range. The low-temperature transition of the blocks A is always close to that of the …

Impact Of Sea Grass Density On Carbonate Dissolution In Bahamian Sediments, David J. Burdige, Richard C. Zimmerman

OES Faculty Publications

Carbonate dissolution has been widely observed in shallow water tropical sediments. However, sediment budgets C have generally not been closed with respect to the amount of acid required to produce the observed carbonate dissolution. Recently it has been suggested that enhanced oxygen transport into sediments through the roots and rhizomes of sea grasses might play a role in resolving this mass balance problem. We conducted studies of sea grass-carbonate sediment interactions around Lee Stocking Island, Exuma Islands, Bahamas to further examine this problem. Our studies showed that alkalinity, total dissolved inorganic carbon (ΣCO₂) and Ca²⁺ increased with …

Intrasteric Inhibition Of Atp Binding Is Not Required To Prevent Unregulated Autophosphorylation Or Signaling By The Insulin Receptor, Mark Frankel, Ararat J. Ablooglu, Joseph W. Leone, Elena Rusinova, J. B. A. Ross, Robert L. Heinrikson, Ronald A. Kohanski

Chemistry and Biochemistry Faculty Publications

Receptor tyrosine kinases may use intrasteric inhibition to suppress autophosphorylation prior to growth factor stimulation. To test this hypothesis we made an Asp1161Ala mutant in the activation loop that relieved intrasteric inhibition of the unphosphorylated insulin receptor (IR) and its recombinant cytoplasmic kinase domain (IRKD) without affecting the activated state. Solution studies with the unphosphorylated mutant IRKD demonstrated conformational changes and greater catalytic efficiency from a 10-fold increase in kcat and a 15-fold-lower K_{m ATP} although K_{m peptide} was unchanged. Kinetic parameters of the autophosphorylated mutant and wild-type kinase domains were virtually identical. The Asp1161Ala mutation increased the …

Complex Effects Arising In Smoke Plume Simulations Due To Inclusion Of Direct Emissions Of Oxygenated Organic Species From Biomass Combustion, Sherri A. Mason, Richard J. Field, Robert J. Yokelson, Michael A. Kochivar, Mark R. Tinsley, Darold E. Ward, Wei Min Hao

Chemistry and Biochemistry Faculty Publications

Oxygenated volatile organic species (oxygenates), including HCOOH, H₂CO, CH₃OH, HOCH₂CHO (hydroxyacetaldehyde), CH₃COOH, and C₆H₅OH, have recently been identified by Fourier transform infrared measurements as a significant component of the direct emissions from biomass combustion. These oxygenates have not generally been included in the hydrocarbon-based initial emission profiles used in previous photochemical simulations of biomass combustion smoke plumes. We explore the effects of oxygenates on this photochemistry by using an established initial emission hydrocarbon profile and comparing simulation results obtained both with and without addition of the above six …

Use Of Py-Gc/Ms Analysis Techniques In Animal Waste Management: A Preliminary Survey Of Dairy Manures, Daniel L. Vaughn, Michael A. Kruge

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The increasing practice of industrial-scale agriculture tends to concentrate large masses of animal waste in relatively compact areas, potentially leading to excessive release of polluting nutrients into waterways during major storms. Anaerobic treatment conditions are generally favored to conserve nitrate N as an agricultural commodity. However, overall N contents in waste are often in excess of crop fertilization needs: storing excess N in soluble nitrate form increases pollution potential. Thus the perceived needs of agriculture and society-at-large become at odds. Organic nitrogen forms (e.g., proteins) are more environmentally stable and are less subject to unintentional release. Although U.S. farmers tend …

Control Of Phytoplankton Growth By Iron And Silicic Acid Availability In The Subantarctic Ocean: Experimental Results From The Saz Project, D. A. Hutchins, Peter N. Sedwick, G. R. Ditullio, P. W. Boyd, B. Queguiner, F. B. Griffiths, C. Crossley

OES Faculty Publications

Subantarctic Southern Ocean surface waters in the austral summer and autumn are characterized by high concentrations of nitrate and phosphate but low concentrations of dissolved iron (Fe, similar to0.05 nM) and silicic acid (Si, <1 muM). During the Subantarctic Zone AU9706 cruise in March 1998 we investigated the relative importance of Fe and Si in controlling phytoplankton growth and species composition at a station within the subantarctic water mass (46.8degreesS, 142degreesE) using shipboard bottle incubation experiments. Treatments included unamended controls; 1.9 nM added iron (+Fe); 9 muM added silicic acid (+Si); and 1.9 nM addediron plus 9 muM added silicic acid (+Fe+Si). We followed a detailed set of biological and biogeochemical parameters over 8 days. Fe added alone clearly increased community growth rates and nitrate drawdown and altered algal community composition relative to control treatments. Surprisingly, small, lightly silicified pennate diatoms grew when Fe was added either with or without Si, despite the extremely low ambient silicic acid concentrations. Pigment analyses suggest that lightly silicified chrysophytes (type 4 haptophytes) may have preferentially responded to Si added either with or without Fe. However, for many of the parameters measured the +Fe+Si treatments showed large increases relative to both the +Fe and +Si treatments. Our results suggest that iron is the proximate limiting nutrient for chlorophyll production, photosynthetic efficiency, nitrate drawdown, and diatom growth, but that Si also exerts considerable control over algal growth and species composition. Both nutrients together are needed to elicit a maximum growth response, suggesting that both Fe and Si play important roles in structuring the subantarctic phytoplankton community.

Effects Of Iron, Silicate, And Light On Dimethylsulfoniopropionate Production In The Australian Subantarctic Zone, G. R. Ditullio, P. N. Sedwick, D. R. Jones, P. W. Boyd, A. C. Crossley, D. A. Hutchins

OES Faculty Publications

Shipboard bottle incubation experiments were performed to investigate the effects of iron, light, and silicate on algal production of particulate dimethylsulfoniopropionate (DMSP_p) in the Subantarctic Zone (SAZ) south of Tasmania during March 1998. Iron enrichment resulted in threefold to ninefold increases in DMSP_p concentrations relative to control treatments, following 7 and 8-day incubation experiments. Additions of Fe and Si preferentially stimulated the growth of lightly-silicified pennate diatoms and siliceous haptophytes, respectively, to which we attribute the increased DMSP_p production in the incubation bottles. Both of these algal groups were previously believed to be low DMSP_{p …}

Analysis Of Wine For Penicillin, Gary Morris, James Yuan, Roy Williams

Chemistry & Biochemistry Faculty Publications

This study addresses the question of whether the antibiotic Penicillin, which is produced by the common mold Penicillium notatum, could possibly become a contaminate of wine during the fermentation process. The significance of this study is related to the potential health effects this agent might produce in those consumers who have an allergic response to Penicillin. It has been estimated that between 6% and 8% of the American population is subject to this type of allergic response. A method is developed for the detection of penicillin in wines using high-pressure liquid chromatography. We demonstrate that penicillin G hydrolyzes rapidly …

Identification Of The Domains Of Urer, An Arac-Like Transcriptional Regulator Of The Urease Gene Cluster In Proteus Mirabilis, Carrie A. Poore, Christopher Coker, Jonathan D. Dattelbaum, Harry L.T. Mobley

Chemistry Faculty Publications

Proteus mirabilis urease catalyzes the hydrolysis of urea to CO₂ and NH₃, resulting in urinary stone formation in individuals with complicated urinary tract infections. UreR, a member of the AraC family, activates transcription of the genes encoding urease enzyme subunits and accessory proteins, ureDABCEFG, as well as its own transcription in the presence of urea. Based on sequence homology with AraC, we hypothesized that UreR contains both a dimerization domain and a DNA-binding domain. A translational fusion of the leucine zipper dimerization domain (amino acids 302 to 350) of C/EBP and the C-terminal half of UreR …

Chemical Constituents Of Desmos Dumosus, Roxb., Mazdida Sulaiman

Student Works (2000-2009)

The chemical content of the 'leaves and bark of Des mos dumosus has been carried out in this study. The leaves yielded nine isoquinoline type of alkaloids and two flavones. The isoquinoline alkaloids isolated were pronuciferine 37, stepharine 39, nomuciferine 40, (-) - 3 - hydroxynomuciferine 41, norlirioferine 42, asimilobine 43, liriodenine 44, lysicamine 45 and O - methylmoschatoline 46. The flavones were 5 - hydroxy - 6,7 - dimethoxyflavone 47 and 5 - hydroxy - 7,8 - dimethoxyflavone 48. The same flavones, 47 and 48 and the alkaloids 45 and 46 were also present in the bark of this …

Nonsteroidal Anti-Inflammatory Drugs, Acetaminophen, Cyclooxygenase 2, And Fever, Daniel L. Simmons, David Wagner, Kenneth Westover

Faculty Publications

Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used antipyretic agents that most probably exert their antifever effect by inhibiting cyclooxygenase (COX)–2. Thus, COX-2–selective drugs or null mutation of the COX-2 gene reduce or prevent fever. Acetaminophen is antipyretic and analgesic, as are NSAIDs, but it lacks the anti-inflammatory and anticoagulatory properties of these drugs. This has led to the speculation that a COX variant exists that is inhibitable by acetaminophen. An acetaminophen-inhibitable enzyme is inducible in the mouse J774.2 monocyte cell line. Induction of acetaminophen-inhibitable prostaglandin E2 synthesis parallels induction of COX-2. Thus, inhibition of pharmacologically distinct COX-2 enzyme activity by …

Measurements Of Excess O3, Co2, Co, Ch4, C2h4, C2h2, Hcn, No, Nh3, Hcooh, Ch3cooh, Hcho, And Ch3oh In 1997 Alaskan Biomass Burning Plumes By Airborne Fourier Transform Infrared Spectroscopy (Aftir), Jon G. Goode, Robert J. Yokelson, Darold E. Ward, Ronald A. Susott, Ronald E. Babbitt, Mary Ann Davies, Wei Min Hao

Chemistry and Biochemistry Faculty Publications

We used an airborne Fourier transform infrared spectrometer (AFTIR), coupled to a flow-through, air-sampling cell, on a King Air B-90 to make in situ trace gas measurements in isolated smoke plumes from four, large, boreal zone wildfires in interior Alaska during June 1997. AFTIR spectra acquired near the source of the smoke plumes yielded excess mixing ratios for 13 of the most common trace gases: water, carbon dioxide, carbon monoxide, methane, nitric oxide, formaldehyde, acetic acid, formic acid, methanol, ethylene, acetylene, ammonia and hydrogen cyanide. Emission ratios to carbon monoxide for formaldehyde, acetic acid, and methanol were 2.2±0.4%, 1.3±0.4%, and …

Investigations On The Use Of Ion Mobility Spectrometry For Clinical Chemistry Applications, Henri Parson Patten

Theses and Dissertations in Biomedical Sciences

The major objective of this research is to examine ion mobility spectrometry as a rapid screening tool for specific application to clinical chemistry research and laboratory use. Methodology was developed for target analytes representing several classes of physiologically active substances, including anesthetics, illicit drugs, and their metabolites. The IMS characteristics of animal tissues and other compounds such as amino acids and proteins were determined. Quality assurance and control procedures were developed for specific quality data objectives. Criteria were established relating to use of IMS for assessing the precision and accuracy of data, qualitative screening, and semi-quantitative analyses.

It was found …

Biochemical Composition Of Particles And Dissolved Organic Matter Slong An Estuarine Gradient: Sources And Implications For Dom Reactivity, Antonio Mannino, H. Rodger Harvey

OES Faculty Publications

The chemical composition of high molecular weight dissolved organic matter (DOM) and particulate organic matter (POM) was examined along the salinity gradient of the Delaware Estuary. DOM was collected and fractionated by tangential-flow ultrafiltration into 1-30 kDa (HDOM; high molecular weight) and 30 kDa to 0.2 μm (VHDOM; very high molecular weight) and compared to particles collected in parallel. Polysaccharides comprised 12-43% of particulate organic carbon (POC), 30-56% of VHDOM carbon, and 7.5-19% of HDOM carbon. Hydrolyzable amino acids comprised 17-38% of POC, 5.4-12% of VHDOM carbon, and 1.5-4.2% of HDOM carbon. Only 7-43% of dissolved organic nitrogen in VHDOM …

Applications Of The Atomic Force Microscope Within The Fields Of Haematology And Cytogenetics, Margaret O'Reilly-Crowley

Theses

Atomic force microscopy [AFM] has become a rapidly developing interdisciplinary field of research in recent years. The technique, including instrumentation and specimen preparation methods, is now more sophisticated and its application has increased dramatically. The key advantage of AFM is in providing three-dimensional images of samples imaged. Both size and shape of samples imaged can be obtained allowing their subsequent quantification. Red blood cells [RBCs] and chromosomes were imaged in this work. A brief overview of the current status of biomedical AFM, has been presented in the review.

Measurement of mean cell volume [MCV] of immobilised red blood cells with …

Emissions Of Formaldehyde, Acetic Acid, Methanol, And Other Trace Gases From Biomass Fires In North Carolina Measured By Airborne Fourier Transform Infrared Spectroscopy, Robert J. Yokelson, Jon G. Goode, Darold E. Ward, Ronald A. Susott, Ronald E. Babbitt, D. D. Wade, Issac T. Bertschi, David W. T. Griffith, Wei Min Hao

Chemistry and Biochemistry Faculty Publications

Biomass burning is an important source of many trace gases in the global troposphere. We have constructed an airborne trace gas measurement system consisting of a Fourier transform infrared spectrometer (FTIR) coupled to a “flow-through” multipass cell (AFTIR) and installed it on a U.S. Department of Agriculture Forest Service King Air B-90. The first measurements with the new system were conducted in North Carolina during April 1997 on large, isolated biomass fire plumes. Simultaneous measurements included Global Positioning System (GPS); airborne sonde; particle light scattering, CO, and CO₂; and integrated filter and canister samples. AFTIR spectra acquired within …

Trace Gas Emissions From Laboratory Biomass Fires Measured By Open-Path Fourier Transform Infrared Spectroscopy: Fires In Grass And Surface Fuels, Jon G. Goode, Robert J. Yokelson, Ronald A. Susott, Darold E. Ward

Chemistry and Biochemistry Faculty Publications

The trace gas emissions from six biomass fires, including three grass fires, were measured using a Fourier transform infrared (FTIR) spectrometer coupled to an open-path, multipass cell (OP-FTIR). The quantified emissions consisted of carbon dioxide, nitric oxide, water vapor, carbon monoxide, methane, ammonia, ethylene, acetylene, isobutene, methanol, acetic acid, formic acid, formaldehyde, and hydroxyacetaldehyde. By including grass fires in this study we have now measured smoke composition from fires in each major vegetation class. The emission ratios of the oxygenated compounds, formaldehyde, methanol, and acetic acid, were 1–2% of CO in the grass fires, similar to our other laboratory and …

Micromagnetics Simulation Of Nanoshaped Iron Elements: Comparison With Experiment, Ngocnga Dao, S. R. Homer, Scott L. Whittenburg

Chemistry and Biochemistry Faculty Publications

A micromagnetics simulation has been conducted on nanostructured magnetic elements of iron in order to investigate the effect of the shape of the element on magnetic properties, such as domain formation and hysteresis loops. These results are compared with recent experimental studies. The results display an impressive agreement with both the experimentally observed magnetic domains in individual particles as well as the shape of the hysteresis loops. The simulation results then explain features in the hysteresis loops in terms of vortice formation and motion.

Induced Changes In Solvent Structure By Phospholipid Monolayer Formation At A Liquid–Liquid Interface, R. A. Walker, D. E. Gragson, G. L. Richmond

Chemistry and Biochemistry

Vibrational sum frequency spectroscopy has been used in conjunction with dynamic surface tension measurements to study formation of a 1,2-dilauroyl-sn-phosphatidylcholine (DLPC) monolayer at a water–carbon tetrachloride interface. Surface tension measurements show that an aqueous solution of liquid crystalline phosphocholine vesicles (4.5 μM DLPC) requires several hours to form a tightly packed, fully equilibrated monolayer of DLPC monomers. Vibrational spectra of the interfacial region at different stages in the monolayer formation process indicate that the solvent structure undergoes dramatic re-organization as the monolayer forms. Initial adsorption of DLPC monomers severely disrupts the interfacial hydrogen bonding. Intensity in the OH …

Nitrate Reductase Activity, Nitrate Uptake And Iodine Speciation In The Marine Environment, Chin-Chang Hung

OES Theses and Dissertations

The present method for the determination of new production (NP) by measuring the uptake of added ¹⁵NO₃^– suffers from a number of limitations. In an attempt to improve this situation, this research examined the possibility of estimating ¹⁵NO₃– uptake by measuring the activity of nitrate reductase (NRA). In addition, because it has long been suspected that the biological reduction of IO₃^– to I^– may be mediated by nitrate reductase (NR), this research investigated the ability of NR to catalyze the reduction of iodate to iodide.

An improved method for the determination …

The Mean Spherical Approximation For A Dipolar Yukawa Fluid, Douglas Henderson, Dezso Boda, Istvan Szalai, Kwong-Yu Chan

Faculty Publications

The dipolar hard sphere fluid (DHSF) is a useful model of a polar fluid. However, the DHSF lacks a vapor–liquid transition due to the formation of chain-like structures. Such chains are not characteristic of real polar fluids. A more realistic model of a polar fluid is obtained by adding a Lennard–Jones potential to the intermolecular potential. Very similar results are obtained by adding a Yukawa potential, instead of the Lennard–Jones potential. We call this fluid the dipolar Yukawa fluid (DYF). We show that an analytical solution of the mean spherical approximation (MSA) can be obtained for the DYF. Thus, the …