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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
The Roles Of Tidal Marshes In The Estuarine Biochemical Processes: A Numerical Modeling Study, Xun Cai
The Roles Of Tidal Marshes In The Estuarine Biochemical Processes: A Numerical Modeling Study, Xun Cai
VIMS Articles
Observations suggest that the existence of tidal marsh can alter the oxygen and nutrient dynamics in adjacent water bodies, but assessing the impacts of large tidal marshes on an estuary is challenging. In this study, we use a modeling approach to investigate the roles of tidal marshes on the estuarine biochemical processes. The marsh model, which simulates the ecological functions of marshes at seasonal and annual time-scales, is embedded inside an unstructured-grid three-dimensional hydrodynamic and eutrophication model (SCHISM-ICM). This modeling system simulates the growth and metabolism of the tidal marshes and links biological processes to nutrient dynamics in the water …
Comparison Of Electrochemical Polishing Treatments Between Phosphoric Acid And A Deep Eutectic Solvent For High-Purity Copper, Tarek M. Abdel-Fattah, Jon Derek Loftis
Comparison Of Electrochemical Polishing Treatments Between Phosphoric Acid And A Deep Eutectic Solvent For High-Purity Copper, Tarek M. Abdel-Fattah, Jon Derek Loftis
VIMS Articles
This study investigated and compared the acid-free electropolishing of copper with the state-of-the-art acidic electropolishing process. The acid-free medium used in this study is based on a deep eutectic solvent comprised of 2:1 ethylene glycol and choline chloride. The electrochemical study included voltammetry and chronoamperometry tests during the electropolishing process. The characterization techniques used were atomic force microscopy (AFM) and digital microscopy, and surface morphology comparisons summarized the electropolishing efficiency of phosphoric acid and acid-free deep eutectic solvent treatments for high-purity copper. Electropolishing copper with a deep eutectic solvent resulted in a mirror finish and a post-treatment surface that was …
Comparison Of Electropolishing Of Aluminum In A Deep Eutectic Medium And Acidic Electrolyte, Tarek M. Abdel-Fattah, Jon Derek Loftis
Comparison Of Electropolishing Of Aluminum In A Deep Eutectic Medium And Acidic Electrolyte, Tarek M. Abdel-Fattah, Jon Derek Loftis
VIMS Articles
Research advances in electropolishing, with respect to the field of metalworking, have afforded significant improvements in the surface roughness and conductivity properties of aluminum polished surfaces in ways that machine polishing and simple chemical polishing cannot. The effects of a deep eutectic medium as an acid-free electrolyte were tested to determine the potential energy thresholds during electropolishing treatments based upon temperature, experiment duration, current, and voltage. Using voltammetry and chronoamperometry tests during electropolishing to supplement representative recordings via atomic force microscopy (AFM), surface morphology comparisons were performed regarding the electropolishing efficiency of phosphoric acid and acid-free ionic liquid treatments for …
Modeling Distinct Vertical Biogeochemical Structure Of The Black Sea: Dynamical Coupling Of The Oxic, Suboxic, And Anoxic Layers, T Oguz, Hw Ducklow, P Malanotte-Rizzoli
Modeling Distinct Vertical Biogeochemical Structure Of The Black Sea: Dynamical Coupling Of The Oxic, Suboxic, And Anoxic Layers, T Oguz, Hw Ducklow, P Malanotte-Rizzoli
VIMS Articles
A one-dimensional, vertically resolved, physical-biogeochemical model is used to provide a unified representation of the dynamically coupled oxic-suboxic-anoxic system for the interior Black Sea. The model relates the annual cycle of plankton production in the form of a series of successive phytoplankton, mesozooplankton, and higher consumer blooms to organic matter generation and to the remineralization-ammonification-nitrification-dentrification chain of the nitrogen cycle as well as to anaerobic sulfide oxidation in the suboxic-anoxic interface zone. The simulations indicate that oxygen consumption during remineralixation and nitrification, together with a lack of ventilation of subsurface waters due to the presence of strong stratification, are the …
Gas Chromatographic Isolation Of Individual Compounds From Complex Matrices For Radiocarbon Dating, Ti Eglinton, Li Alueihare, Je Bauer, Erm Druffel, Ap Mcnichol
Gas Chromatographic Isolation Of Individual Compounds From Complex Matrices For Radiocarbon Dating, Ti Eglinton, Li Alueihare, Je Bauer, Erm Druffel, Ap Mcnichol
VIMS Articles
This paper describes the application of a novel, practical approach for isolation of individual compounds from complex organic matrices for natural abundance radiocarbon measurement. This is achieved through the use of automated preparative capillary gas chromatography (PCGC) to separate and recover sufficient quantities of individual target compounds for C-14 analysis by accelerator mass spectrometry (AMS). We developed and tested this approach using a suite of samples (plant lipids, petroleums) whose ages spanned the C-14 time scale and which contained a variety of compound types (fatty acids, sterols, hydrocarbons), Comparison of individual compound and bulk radiocarbon signatures for the isotopically homogeneous …
Correlation Between Electron Capture Negative Chemical Ionization Mass Spectrometric Fragmentation And Calculated Internal Energies For Polychlorinated Biphenyls, John Greaves, Ellen Harvey, William G. Macintyre
Correlation Between Electron Capture Negative Chemical Ionization Mass Spectrometric Fragmentation And Calculated Internal Energies For Polychlorinated Biphenyls, John Greaves, Ellen Harvey, William G. Macintyre
VIMS Articles
Correlations between molecular structure and fragmentation observed in electron capture negative chemical ionization mass spectra (moderator gas = methane) of 49 selected tetrachlorinated, pentachlorinated, and hexachlorinated biphenyls have been investigated by using molecular modeling. The semiempirical general molecular orbital program MOPAC was used to calculate molecular properties for biphenyl and the 209 polychlorinated biphenyls. The mass spectrometric ionization and fragmentation processes were found to be linked to the number of chlorine atoms present on the biphenyl, and to the number of those chlorine atoms in the ortho (2, 2', 6, and 6') positions. The intensity of molecular ions increased with …
Determination Of Tributyltin In The Marine-Environment, Rg Huggett, Michael A. Unger, Fa Espourteille, Cd Rice
Determination Of Tributyltin In The Marine-Environment, Rg Huggett, Michael A. Unger, Fa Espourteille, Cd Rice
VIMS Articles
Tributyltin (TBT) is a biocide used in antifouling paints to protect hulls from nuisance organisms such as barnacles, worms and algae. The use of TBT paints has increased over the past decade due to its effectiveness as an antifoulant which is related to its toxicity. Water concentrations of less than 100 ng L- have been shown to harm some aquatic species in laboratory tests and observations in the natural environment indicate that levels below 10 ng L- may be harmful. Tributyltin is bioconcentrated by many species to levels of one thousand, or more, times ambient water concentrations. Sediment-water partitioning coefficients …