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Full-Text Articles in Physical Sciences and Mathematics

Very Rapid Geomagnetic Field Change Recorded By The Partial Remagnetization Of A Lava Flow, Scott Bogue, Jonathan Glen Dec 2009

Very Rapid Geomagnetic Field Change Recorded By The Partial Remagnetization Of A Lava Flow, Scott Bogue, Jonathan Glen

Scott Bogue

A new paleomagnetic result from a lava flow with a distinctive, two-part remanence reinforces the controversial hypothesis that geomagnetic change during a polarity reversal can be much faster than normal. The 3.9-m-thick lava (“Flow 20”) is exposed in the Sheep Creek Range (north central Nevada) and was erupted during a reverse-to-normal (R-N) geomagnetic polarity switch at 15.6 Ma. Flow 20 began to acquire a primary thermoremanence while the field was pointing east and down but was soon buried, reheated, and partially-remagnetized in a north-down direction by the 8.2-m-thick flow that succeeded it. A simple conductive cooling calculation shows that the …

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Mathematica In Action: Problem-Solving Through Visualization And Computation, Stan Wagon Dec 2009

Mathematica In Action: Problem-Solving Through Visualization And Computation, Stan Wagon

Stan Wagon, Retired

No abstract provided.

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Dynamic Pickup And Delivery Problems, Gerardo Berbeglia Dec 2009

Dynamic Pickup And Delivery Problems, Gerardo Berbeglia

Gerardo Berbeglia

No abstract provided.

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Understanding Space Weather Customers In Gps-Reliant Industries, Jennifer Meehan, G. Fisher, W. Murtagh Dec 2009

Understanding Space Weather Customers In Gps-Reliant Industries, Jennifer Meehan, G. Fisher, W. Murtagh

Jennifer (Jinni) Meehan

No abstract provided.

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Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, Michael Nichols, Mark Waner Dec 2009

Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, Michael Nichols, Mark Waner

Michael A Nichols

An extension of the classic keto−enol tautomerization of β-dicarbonyl compounds into a kinetic analysis of deuterium exchange is presented. It is shown that acetylacetone and ethyl acetoacetate undergo nearly complete deuterium exchange of the α-methylene carbon when dissolved in methanol-d4. The extent of deuteration may be monitored via NMR spectroscopy as a function of time. A mechanism for deuterium exchange is presented and shown to be consistent with a consecutive first-order process. The data for acetylacetone are consistent with steady-state kinetics, whereas those of ethyl acetoacetate illustrate nonsteady-state behavior, offering an accessible example where students might collect and analyze real …

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The Effect Of Ion-Pairing On The Open Circuit Potential Of 3-Mercaptoproprionic Acid Modified Gold Electrodes, Mark Anderson, Alice Harper Dec 2009

The Effect Of Ion-Pairing On The Open Circuit Potential Of 3-Mercaptoproprionic Acid Modified Gold Electrodes, Mark Anderson, Alice Harper

Mark R. Anderson

Open circuit potential (OCP) measurement is used to monitor the charge of a monolayer of 3-mercaptopropionic acid. OCP is determined by the concentrations of the reduced and oxidized forms of a redox couple in the solution adjacent to the modified interface. OCP values were monitored in the presence of the one-electron redox couple Fe(CN)63-/4- as a function of solution pH. The OCP measured at basic pHs was different from the acidic OCP due to differences in electrostatic interactions between the interface and the redox species as described by the Nernst equation. The influence of ion-pairing with the monolayer is studied …

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Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, Mark Waner, Michael Nichols Dec 2009

Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, Mark Waner, Michael Nichols

Mark J. Waner

An extension of the classic keto−enol tautomerization of β-dicarbonyl compounds into a kinetic analysis of deuterium exchange is presented. It is shown that acetylacetone and ethyl acetoacetate undergo nearly complete deuterium exchange of the α-methylene carbon when dissolved in methanol-d4. The extent of deuteration may be monitored via NMR spectroscopy as a function of time. A mechanism for deuterium exchange is presented and shown to be consistent with a consecutive first-order process. The data for acetylacetone are consistent with steady-state kinetics, whereas those of ethyl acetoacetate illustrate nonsteady-state behavior, offering an accessible example where students might collect and analyze real …

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Ans Binding Reveals Common Features Of Cytotoxic Amyloid Species, Benedetta Bolognesi, Janet Kumita, Teresa Barros, Elin Esbjorner, Leila Luheshi, Damian Crowther, Mark Wilson, Christopher Dobson, Giorgio Favrin, Justin Yerbury Dec 2009

Ans Binding Reveals Common Features Of Cytotoxic Amyloid Species, Benedetta Bolognesi, Janet Kumita, Teresa Barros, Elin Esbjorner, Leila Luheshi, Damian Crowther, Mark Wilson, Christopher Dobson, Giorgio Favrin, Justin Yerbury

Mark R Wilson

Oligomeric assemblies formed from a variety of disease-associated peptides and proteins have been strongly associated with toxicity in many neurodegenerative conditions, such as Alzheimer's disease. The precise nature of the toxic agents, however, remains still to be established. We show that prefibrillar aggregates of E22G (arctic) variant of the A beta(1-42) peptide bind strongly to 1-anilinonaphthalene 8-sulfonate and that changes in this property correlate significantly with changes in its cytotoxicity. Moreover, we show that this phenomenon is common to other amyloid systems, such as wild-type A beta(1-42), the 159T variant of human lysozyme and an SH3 domain. These findings are …

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College Algebra In Context With Applications To The Managerial, Life, And Social Sciences, Ronald Harshbarger, Lisa Yocco Dec 2009

College Algebra In Context With Applications To The Managerial, Life, And Social Sciences, Ronald Harshbarger, Lisa Yocco

Lisa S. Yocco

Harshbarger/Yocco’s College Algebra in Context with Applications for the Managerial, Life, and Social Sciences, Third Edition uses modeling and real-data problems to develop the skills that students will need for their future courses and careers. Applications anticipate the math that students will encounter in their professional lives, giving them the practice they need to become adept problem-solvers. Every chapter begins with the Algebra Toolbox, which reviews the skills and concepts necessary to master the material ahead. This new full-color edition offers a greater number of technology tips, and the content has been reorganized to accommodate a wide range of course …

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Association-Based Image Retrieval, Arun D. Kulkarni Dec 2009

Association-Based Image Retrieval, Arun D. Kulkarni

Arun Kulkarni

No abstract provided.

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Characterization And Properties Of Matrices With $K$-Involutory Symmetries Ii, William F. Trench Dec 2009

Characterization And Properties Of Matrices With $K$-Involutory Symmetries Ii, William F. Trench

William F. Trench

No abstract provided.

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The Journey To Safety: Conflict-Driven Migration Flows In Colombia, Gianfranco Piras, Nancy Lozano-Gracia, Geoffrey Hewings, Ana Maria Ibanez Dec 2009

The Journey To Safety: Conflict-Driven Migration Flows In Colombia, Gianfranco Piras, Nancy Lozano-Gracia, Geoffrey Hewings, Ana Maria Ibanez

Gianfranco Piras

No abstract provided.

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Improved Synthesis Of Pincer Ligand Precursor, And Synthesis And Structural Characterization Of Terphenyl Scaffolded S–C–S Palladium Pincer Complex., Paul Schroder, Thomas Spilker, Wilson Luu, James Updegraff, Man Lung Kwan, Paul Challen, John Protasiewicz Nov 2009

Improved Synthesis Of Pincer Ligand Precursor, And Synthesis And Structural Characterization Of Terphenyl Scaffolded S–C–S Palladium Pincer Complex., Paul Schroder, Thomas Spilker, Wilson Luu, James Updegraff, Man Lung Kwan, Paul Challen, John Protasiewicz

Paul R. Challen

An easier and more expedient synthesis of 2,6-(BrCH2C6H4)2-4-I-C6H3 (2) is reported. This material allowed easy synthesis of the new pincer ligand precursor 2,6-(4-CH3C6H4SCH2C6H4)2-4-I-C6H3 (3) in 87% yield. Compound 3 reacts with Pd2(dba)3 to give the new palladium pincer complex 4. Compound 4 has been fully characterized, including structural characterization by single crystal X-ray diffraction methods. The results of the crystallographic work on 4 reveal a twisted type pincer complex not unlike related terphenyl pincer complexes.

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Polarimetry Studies For The Npdgamma Experiment At The Sns, Jonny Dadras Nov 2009

Polarimetry Studies For The Npdgamma Experiment At The Sns, Jonny Dadras

Jonny Dadras

The NPDGamma collaboration aims to measure a parity-violating directional gamma-ray asymmetry from the capture of polarized cold neutrons on protons. The asymmetry, predicted to be on the order of 50 ppb, is a result of the weak interaction between mesons and nucleons during the neutron capture reaction. The experiment is designed to make a statistics limited measurement of the asymmetry at the level of about 20%. The experiment will be carried out at the Fundamental neutron Physics Beamline (FnPB) at the Spallation Neutron Source (SNS). The neutron beam is polarized by a super-mirror polarizer. A 9.5 G magnetic field guides …

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Measurements Of Electron Density, Temperature And Photoionization Cross Sections Of The Excited States Of Neon In A Discharge Plasma, Shaukat Mahmood, Nek Shaikh, M. Kalyar, Naveed Piracha, M. Baig Oct 2009

Measurements Of Electron Density, Temperature And Photoionization Cross Sections Of The Excited States Of Neon In A Discharge Plasma, Shaukat Mahmood, Nek Shaikh, M. Kalyar, Naveed Piracha, M. Baig

Naveed K. Piracha

In the present work emission and absorption spectroscopy have been used to determine the plasma parameters of neon in a hollow cathode discharge lamp. The excitation temperature is determined using the intensity ratio method and Boltzmann’s plot method whereas the electron density is determined from the Stark broadening of the spectral lines. The behavior of the optogalvanic signal as a function of laser energy has been studied for three transitions from the 2p53s [1/2]2 metastable state following ΔJ=ΔK=0, ±1 dipole selection rules. The saturation technique has been used to measure the photoionization cross section from three intermediate states 2p53p′ [1/2]1, …

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One Million Downloads For Uow’S Research Online, Kate Mcilwain, Michael Organ, K. Michael, M. Michael Oct 2009

One Million Downloads For Uow’S Research Online, Kate Mcilwain, Michael Organ, K. Michael, M. Michael

Michael Organ

No abstract provided.

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Zincast-1: A Photochemically Active Chelator For Zn2+, Shawn Burdette, Celina Gwizdala, Daniel Kennedy Oct 2009

Zincast-1: A Photochemically Active Chelator For Zn2+, Shawn Burdette, Celina Gwizdala, Daniel Kennedy

Shawn C. Burdette

Two strategies were applied to the synthesis of ZinCast-1, a nitrobenzhydrol-based caged complex that upon photolysis exhibits a nearly 400-fold difference in binding for Zn2+.

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An Aztec 1.1mm Survey Of The Goods-N Field – Ii. Multiwavelength Identifications And Redshift Distribution, Thushara Perera, Edward Chapin, Alexandra Pope, Douglas Scott, Itziar Aretxaga, Jason Austermann, Ranga-Ram Chary, Kristen Coppin, Mark Halpern, David Hughes, James Lowenthal, Glenn Morrison, Kimberly Scott, Grant Wilson, Min Yun Sep 2009

An Aztec 1.1mm Survey Of The Goods-N Field – Ii. Multiwavelength Identifications And Redshift Distribution, Thushara Perera, Edward Chapin, Alexandra Pope, Douglas Scott, Itziar Aretxaga, Jason Austermann, Ranga-Ram Chary, Kristen Coppin, Mark Halpern, David Hughes, James Lowenthal, Glenn Morrison, Kimberly Scott, Grant Wilson, Min Yun

Thushara A. Perera

No abstract provided.

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Copula Density Estimation By Total Variation Penalized Likelihood, Leming Qu, Yi Qian, Hui Xie Sep 2009

Copula Density Estimation By Total Variation Penalized Likelihood, Leming Qu, Yi Qian, Hui Xie

Leming Qu

Copulas are full measures of dependence among random variables. They are increasingly popular among academics and practitioners in financial econometrics for modeling comovements between markets, risk factors, and other relevant variables. A copula's hidden dependence structure that couples a joint distribution with its marginals makes a parametric copula non-trivial. An approach to bivariate copula density estimation is introduced that is based on a penalized likelihood with a total variation penalty term. Adaptive choice of the amount of regularization is based on approximate Bayesian Information Criterion (BIC) type scores. Performance are evaluated through the Monte Carlo simulation.

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Impedance Differences Found With N-Alkanethiol Monolayers Prepared By Contact Printing And Solution Adsorption, Leslie Adamczyk, Mark Anderson Aug 2009

Impedance Differences Found With N-Alkanethiol Monolayers Prepared By Contact Printing And Solution Adsorption, Leslie Adamczyk, Mark Anderson

Mark R. Anderson

Self-assembled monolayers (SAMs) of n-octadecanethiol, n-dodecanethiol and n-pentanethiol formed by contact printing and solution adsorption are characterized by electrochemical impedance spectroscopy (EIS). Impedance measurements show that monolayers prepared by contact printing are on the order of 5 times less resistive to charge transfer and have greater defect density than monolayers prepared by solution adsorption. Modeling of the average defect size and density show that the size of monolayer defects stays relatively constant independent of the monolayer preparation conditions; however, the density of defects decreases with increasing concentration for the contact printed monolayers. The impedance data also show that monolayers prepared …

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Correction To “The Theory Of Quaternion Orthogonal Designs”, Tadeusz Wysocki, Beata Wysocki, Sarah Spence Adams Jul 2009

Correction To “The Theory Of Quaternion Orthogonal Designs”, Tadeusz Wysocki, Beata Wysocki, Sarah Spence Adams

Sarah Spence Adams

Seberry et al. claimed that even though the dual-polarized transmission channel cannot be considered as described by means of a single quaternionic gain, the maximum-likelihood (ML) decoding rule can be decoupled for orthogonal space–time-polarization block codes (OSTPBCs) derived from quaternion orthogonal designs (QODs) [1, Sec. IV]. Regretfully, a correction is necessary, and we will show that decoupled decoding using the method presented therein is only optimal for codes derived from certain QODs, not from arbitrary QODs as previously suggested.

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The Spectroelectrochemical, Magnetic, And Structural Characterization Of Reduced Hexaazatriphenylenehexacarbonitrile, Hat(Cn)6., Joseph Gallegos, Anthony Francis, Nathan Ockwig, Paul Rasmussen, Raphael Raptis, Paul Challen, Issouf Ouedraogo Jul 2009

The Spectroelectrochemical, Magnetic, And Structural Characterization Of Reduced Hexaazatriphenylenehexacarbonitrile, Hat(Cn)6., Joseph Gallegos, Anthony Francis, Nathan Ockwig, Paul Rasmussen, Raphael Raptis, Paul Challen, Issouf Ouedraogo

Paul R. Challen

The cyanoazacarbon, hexaazatriphenylenehexacarbonitrile, or HAT(CN)6, is readily reduced and the spectroelectrochemical properties associated with the multiple reductions are described. The singly reduced radical monoanion forms stable salts and we report the crystal structure and magnetic properties for the tetrabutylammonium salt. [Tetra-n-butylammonium] [HAT(CN)6] behaves ferromagnetically below 3K and follows Curie Law behavior at higher temperatures after correction for Pauli-type susceptibility. The room temperature conductivity of the powdered salt is 3.8×10−8S/cm. The crystal structure shows closely bound pairs of radical anions with slip-stacking of these pairs to form a staircase, features that elucidate the observed properties. Thin films of HAT(CN)6 were found …

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Wavelet Deconvolution In A Periodic Setting Using Cross-Validation, Leming Qu, Partha Routh, Kyungduk Ko Jul 2009

Wavelet Deconvolution In A Periodic Setting Using Cross-Validation, Leming Qu, Partha Routh, Kyungduk Ko

Kyungduk Ko

The wavelet deconvolution method WaveD using band-limited wavelets offers both theoretical and computational advantages over traditional compactly supported wavelets. The translation-invariant WaveD with a fast algorithm improves further. The twofold cross-validation method for choosing the threshold parameter and the finest resolution level in WaveD is introduced. The algorithm’s performance is compared with the fixed constant tuning and the default tuning in WaveD.

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Bayesian Wavelet-Based Methods For The Detection Of Multiple Changes Of The Long Memory Parameter, Kyungduk Ko Jul 2009

Bayesian Wavelet-Based Methods For The Detection Of Multiple Changes Of The Long Memory Parameter, Kyungduk Ko

Kyungduk Ko

Long memory processes are widely used in many scientific fields, such as economics, physics, and engineering. Change point detection problems have received considerable attention in the literature because of their wide range of possible applications. Here we describe a wavelet-based Bayesian procedure for the estimation and location of multiple change points in the long memory parameter of Gaussian autoregressive fractionally integrated moving average models (ARFIMA(p, d, q)), with unknown autoregressive and moving average parameters. Our methodology allows the number of change points to be unknown. The reversible jump Markov chain Monte Carlo algorithm is used for posterior inference. The method …

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Geochemical Partitioning Of Copper, Lead And Zinc In Benthic, Estuarine Sediment Profiles, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Geochemical Partitioning Of Copper, Lead And Zinc In Benthic, Estuarine Sediment Profiles, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

Received for publication May 11, 2004. The geochemical partitioning of copper (Cu), lead (Pb), and zinc (Zn) was examined in benthic sediment profiles (0- to 20-cm depth interval) composed of relatively coarse (65–90% sand-sized particles), noncohesive, suboxic material (Eh +120 to +260 mV). Total Cu, Pb, and Zn concentrations ranged from 8.3 to 194, 16.3 to 74.8, and 30.1 to 220 mg/kg, respectively, and were related to vertical trends in sediment texture. The observed distribution coefficients describing solid–solution partitioning were in the range of 100 to 1000 L/kg. The geochemical partitioning of solid-phase Cu, Pb, and Zn between six operationally …

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Reactive Sulphide Relationships With Trace Metal Extractability In Sediments From Southern Moreton Bay, Australia, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Reactive Sulphide Relationships With Trace Metal Extractability In Sediments From Southern Moreton Bay, Australia, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

No abstract provided.

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Distribution And Enrichment Of Trace Metals In Benthic, Estuarine Sediments: Southport Broadwater, Australia, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Distribution And Enrichment Of Trace Metals In Benthic, Estuarine Sediments: Southport Broadwater, Australia, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

The distribution and enrichment of selected trace metals (Cd, Cr, Cu, Ni, Pb, Sn, Zn) in benthic sediments of the Southport Broadwater, a semi-enclosed coastal body of water adjacent to the Gold Coast city, south-eastern Queensland, Australia, was studied with the objective of assessing the extent and degree of sediment contamination. Sediment samples from the 0–10 cm and 10–20 cm depth intervals of 32 sites within the Southport Broadwater and surrounding residential canals were analysed for particle size distribution, pH, organic C and ‘near-total’ major (Al, Ca, Fe, Mn) and trace (Cd, Cr, Cu, Ni, Pb, Sn, Zn) metal contents. …

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Nutrient Leaching In Undisturbed Cores Of An Acidic Sandy Podosol Following Simultaneous Potassium Chloride And Di-Ammonium Phosphate Application, Ian Phillips, Edward Burton Jul 2009

Nutrient Leaching In Undisturbed Cores Of An Acidic Sandy Podosol Following Simultaneous Potassium Chloride And Di-Ammonium Phosphate Application, Ian Phillips, Edward Burton

Associate Professor Edward D Burton

In south-east Queensland, Australia, extensive areas of sandy soils (Podosols) with shallow (<1>m) watertables are used for exotic pine tree production. Despite concerns that surface-applied fertilisers (di-ammonium phosphate (DAP) and potassium chloride (KCl)) may be contributing to a decline in local groundwater quality, published information on nutrient leaching in these Podosols is scarce. Large (0.3 m i.d. · 0.85 m long) undisturbed soil cores were intermittently leached with deionised water following a single surface application of KCl in combination with DAP. Potassium was applied at rates (equivalent on a surface area basis) of 0 (K0), 50 (K50), 100 (K100) …

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Copper Behaviour In A Podosol. Ii: Sorption Reversibility, Geochemical Partitioning And Column Leaching, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb Jul 2009

Copper Behaviour In A Podosol. Ii: Sorption Reversibility, Geochemical Partitioning And Column Leaching, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb

Associate Professor Edward D Burton

The sorption–desorption and leaching behaviour of Cu in a Podosol from south-east Queensland, Australia, was examined. Copper sorption was described by a linear distribution coefficient at low sorption levels (KDCa→0) of 481 L/kg and a sorption capacity (CS,Max) of 382 mg/kg. Selective removal of soil organic matter reduced these values by approximately 95%, indicating that Cu was sorbed predominantly to soil organic matter. The KDCa→0 and CS,Max values from Cu desorption experiments were 934 L/kg and 516 mg/kg, respectively, which indicates that sorption was not fully reversible. This irreversibility was related to …

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Copper Behaviour In A Podosol. I: Ph-Dependent Sorption-Desorption, Sorption Isotherm Analysis And Aqueous Speciation Modelling, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb Jul 2009

Copper Behaviour In A Podosol. I: Ph-Dependent Sorption-Desorption, Sorption Isotherm Analysis And Aqueous Speciation Modelling, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb

Associate Professor Edward D Burton

The effects of pH and Cu loading on the solid/solution partitioning of Cu in a Podosol from south-east Queensland, Australia was examined. Sorption–desorption of Cu exhibited maximum linear distribution coefficients (KD) at approximately pH 5. Observed decrease in KD values at pH >5 was attributed to increased solubility of native dissolved organic carbon (DOC) at higher pH and subsequent formation of non-sorbing Cu–DOC complexes. Speciation modelling with the MINTEQA2 code indicated that >90% of aqueous Cu was present as Cu–DOC complexes at pH >5.5. The effect of Cu loading was examined with sorption isotherm analysis at pH …

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