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Search Results: 1 - 10 of 219344 matches for " Lee D. Wilson "
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Investigation of Chitosan-PVA Composite Films and Their Adsorption Properties  [PDF]
Lewis S. Casey, Lee D. Wilson
Journal of Geoscience and Environment Protection (GEP) , 2015, DOI: 10.4236/gep.2015.32013
Abstract:

Viscous aqueous solutions of chitosan and polyvinyl alcohol (PVA) were blended to enhance miscibility and avoid polymer phase separation. The mixtures were drop-casted and air dried to yield composite film materials that were characterized by equilibrium water uptake, physical stability in aqueous solution, and thermal stability. Chitosan/PVA blends have greater thermal stability, unique morphology, and reduced solubility in acidic solution, thus extending the useful pH range for chitosan as a sorbent material. The uptake properties of the films was investigated using methylene blue (MB) and a p-nitrophenol (PNP) dyes, where it was found that each single component polymer has greater uptake toward MB than PNP. A direct relationship between film composition (chitosan:PVA) with solution pH and the uptake of MB was observed. The results are in agreement with electrostatic interactions and contributions due to the hydrophobic effect for such composite materials.

Structural Study of Cellulose-Iron Oxide Composite Materials  [PDF]
Dexu Kong, Lee D. Wilson
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.64009
Abstract:
There are limited structural studies of iron oxide coated cellulose materials despite their use as adsorbents for the removal of waterborne arsenic species. This study reports on the structural characterization of cellulose-iron oxide composites at variable iron oxide content using spectroscopy methods (Raman, solids 13C NMR, powder X-ray diffraction (pXRD)) and thermal gravi-metric analysis (TGA). Iron oxide was supported onto cellulose (ca. 25 wt.%) without significant loss in the Fe coating efficiency, where the accessibility of the biopolymer -OH groups affect the coating efficiency and yield of the iron oxide-cellulose composite. Isotherm adsorption studies for cellulose, iron oxide species and the cellulose composite materials with roxarsone (3-nitro- 4-hydroxyphenylarsonic acid) were studied to characterize the surface chemical properties of these potential adsorbent materials.
Porous Copolymer Resins: Tuning Pore Structure and Surface Area with Non Reactive Porogens
Mohamed H. Mohamed,Lee D. Wilson
Nanomaterials , 2012, DOI: 10.3390/nano2020163
Abstract: In this review, the preparation of porous copolymer resin (PCR) materials via suspension polymerization with variable properties are described by tuning the polymerization reaction, using solvents which act as porogens, to yield microporous, mesoporous, and macroporous materials. The porogenic properties of solvents are related to traditional solubility parameters which yield significant changes in the surface area, porosity, pore volume, and morphology of the polymeric materials. The mutual solubility characteristics of the solvents, monomer units, and the polymeric resins contribute to the formation of porous materials with tunable pore structures and surface areas. The importance of the initiator solubility, surface effects, the temporal variation of solvent composition during polymerization, and temperature effects contribute to the variable physicochemical properties of the PCR materials. An improved understanding of the factors governing the mechanism of formation for PCR materials will contribute to the development and design of versatile materials with tunable properties for a wide range of technical applications.
Entanglement of a two-mode squeezed state in a Gaussian environment
D. Wilson,J. Lee,M. S. Kim
Physics , 2002, DOI: 10.1080/09500340308235238
Abstract: Some non-classical properties such as squeezing, sub-Poissonian photon statistics or oscillations in photon-number distributions may survive longer in a phase-sensitive environment than in a phase-insensitive environment. We examine if entanglement, which is an inter-mode non-classical feature, can also survive longer in a phase-sensitive environment. Differently from the single-mode case, we find that making the environment phase-sensitive does not aid in prolonging entanglement.
Vapour and Solution Uptake Properties of Starch and Cellulose Biopolymers  [PDF]
Leila Dehabadi, Mohsen Shakouri, Carey J. Simonson, Mohammad Arjmand, Uttandaraman Sundararaj, Lee D. Wilson
Journal of Geoscience and Environment Protection (GEP) , 2018, DOI: 10.4236/gep.2018.65009
Abstract:
This study was aimed at gaining further insight on the role of hydration in adsorption processes of biopolymer/adsorbate systems using complementary methods (electromagnetic interference (EMI) shielding, calorimetry, and solvent/vapour adsorption isotherms). Cellulose and starch-based materials were used as the adsorbents, whereas water (liquid and vapour), ethanol and p-nitrophenol (PNP) in aqueous solution were the adsorbate systems. The biopolymer/water systems had higher uptake capacity overall, where starch materials showed higher uptake capacity than cellulose among the various solvents. The secondary and tertiary structure of the biopolymers was a key factor affecting their uptake capacity, as evidenced by the enhanced adsorption properties of starch over cellulose, along with higher uptake of amylose (AM) versus amylopectin (AP) in starch biopolymers. EMI results also confirmed that AM starch had higher adsorption toward water than ethanol. The textural properties and surface chemistry of the biopolymers were probed using dye adsorption (PNP at pH 8.5) in aqueous solution that showed parallel trends with water vapour adsorption isotherms. Isothermal Titration Calorimetry (ITC) revealed that the heat of adsorption in AP differed from that of AM since the biopolymer tertiary structure governs the accessibility of biopolymer adsorption sites. The role of branching in AP and amorphous domains in AM/AP composites are inferred to play a key role in hydration-driven allosterism known for such biopolymer/water vapour adsorption processes.
Sorption of Aromatic Compounds with Copolymer Sorbent Materials Containing β-Cyclodextrin
Lee D. Wilson,Mohamed H. Mohamed,Christopher L. Berhaut
Materials , 2011, DOI: 10.3390/ma4091528
Abstract: Urethane copolymer sorbent materials that incorporate β-cyclodextrin (CD) have been prepared and their sorption properties with chlorinated aromatic compounds ( i.e., pentachlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenoxy acetic acid) have been evaluated. The sorption properties of granular activated carbon (GAC) were similarly compared in aqueous solution at variable pH conditions. The sorbents displayed variable BET surface areas as follows: MDI-X copolymers (< 10 1 m 2/g), CDI-X copolymers (< 10 1 m 2/g), and granular activated carbon (GAC ~10 3 m 2/g). The sorption capacities for the copolymers sorbents are listed in descending order, as follows: GAC > CDI-3 copolymer ≈ MDI-3 copolymer. The sorption capacity for the aromatic adsorbates with each sorbent are listed in descending order, as follows: 2,4-dichlorophenol > 2,4-dichlorophenoxy acetic acid > pentachlorophenol. In general, the differences in the sorption properties of the copolymer sorbents with the chlorinated organics were related to the following factors: ( i) surface area of the sorbent; ( ii) CD content and accessibility; and ( iii) and the chemical nature of the sorbent material.
Chitosan Biopolymers for Analysis of Organic Acids in Aquatic Environments of Treatment Wetlands  [PDF]
Mohamed H. Mohamed, Kerry M. Peru, John V. Headley, Lee D. Wilson
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.56019
Abstract:
Herein, we report on the use of chitosan-based engineered materials for the sequestration of naphthenic acid fraction compounds (NAFCs) and other species (matrix) in oil sands process-affected water (OSPW) in order to improve monitoring of NAFCs after phytoremediation. Chitosan pellets (CPs) were cross linked with glutaraldehyde (GLU) at variable feed ratios and characterized using thermogravimetric analysis (TGA). Sorption studies at equilibrium and kinetic conditions were carried on OSPW extract, raw and treated wetland samples. The materials were shown to have similar sorption capacity for NAFCs but with variable selectivity of the species in the complex mixture. As well, the matrix uptake varied according to the type of OSPW. Overall, CP in its native form outperformed the cross linked CP pellets, as evidenced by a reduction in matrix effects.
Use of Industrial Coal Waste Materials as Adsorbents for Textile Effluent Remediation  [PDF]
Mohamed H. Mohamed, Marissa Pirlot, Michael K. Danquah, Lee D. Wilson
Journal of Materials Science and Chemical Engineering (MSCE) , 2017, DOI: 10.4236/msce.2017.58002
Abstract:
This paper presents experimental study on six carbonaceous industrial waste samples that were obtained from a local industry in Saskatchewan, Canada. Hereafter, the samples are coded as ES1, ES2, ES3, PU, RPS and SS1 and were characterized using IR and 13C solid state NMR spectroscopy, nitrogen porosimetry, TGA, metal leaching analysis using ICP and point-of-zero-charge. Adsorption studies were conducted using two types of adsorptive dye probes (p-nitrophenol, PNP; and methylene blue; MB) at pH 4.60 and pH 7.00.
Probing the Cell Cycle with Flow Cytometry  [PDF]
George D. Wilson
Journal of Biomedical Science and Engineering (JBiSE) , 2014, DOI: 10.4236/jbise.2014.79069
Abstract: Flow cytometry is a versatile technique to study different aspects of the cell cycle from subpopulations of cells to detailed cell kinetic information. In this paper a basic review of cell kinetic parameters is presented followed by detailed descriptions of the different flow cytometric methodologies that can be used to extract pertinent information for a particular study. The methodologies range from simple DNA profile analysis, the use of bromodeoxyuridine to cell cycle-associated proteins such as the cyclins.
Luminous Infrared Galaxies With the Submillimeter Array. III. The Dense Kiloparsec Molecular Concentrations of Arp 299
Kazimierz Sliwa,Christine D. Wilson,Glen R. Petitpas,Lee Armus,Mika Juvela,Satoki Matsushita,Alison B. Peck,Min S. Yun
Physics , 2012, DOI: 10.1088/0004-637X/753/1/46
Abstract: We have used high resolution (~2.3") observations of the local (D = 46 Mpc) luminous infrared galaxy Arp 299 to map out the physical properties of the molecular gas which provides the fuel for its extreme star formation activity. The 12CO J=3-2, 12CO J=2-1 and 13CO J=2-1 lines were observed with the Submillimeter Array and the short spacings of the 12CO J=2-1 and J=3-2 observations have been recovered using James Clerk Maxwell Telescope single dish observations. We use the radiative transfer code RADEX to estimate the physical properties (density, column density and temperature) of the different regions in this system. The RADEX solutions of the two galaxy nuclei, IC 694 and NGC 3690, are consistent with a wide range of gas components, from warm moderately dense gas with T_{kin} > 30 K and n(H_{2}) ~ 0.3 - 3 x 10^{3} cm^{-3} to cold dense gas with T_{kin} ~ 10-30 K and n(H_{2}) > 3 x 10^{3} cm^{-3}. The overlap region is shown to have a better constrained solution with T_{\rm{kin}}$ ~ 10-50 K and n(H_{2}) ~ 1-30 x 10^{3} cm^{-3}. We estimate the gas masses and star formation rates of each region in order to derive molecular gas depletion times. The depletion times of all regions (20-60 Myr) are found to be about 2 orders of magnitude lower than those of normal spiral galaxies. This rapid depletion time can probably be explained by a high fraction of dense gas on kiloparsec scales in Arp 299. We estimate the CO-to-H_{2} factor, \alpha_{co} to be 0.4 \pm 0.3 (3 x 10^{-4}/ x_{CO}) M_{sol} (K km s^{-1} pc^{2})^{-1} for the overlap region. This value agrees well with values determined previously for more advanced merger systems.
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