Papers by emanuel waddell
Supported M(I)/alumina and M(II)/alumina adsorbents were prepared using Mn+(acac)nas the precurso... more Supported M(I)/alumina and M(II)/alumina adsorbents were prepared using Mn+(acac)nas the precursor. These materials may be decomposed by careful heating to create dispersions of Mn+On/2/alumina which are SO2adsorbents. These adsorbents have been characterized by elemental analyses, diffuse reflectance infrared Fourier transform analysis spectroscopy, SO2adsorption capacity, and powder X-ray diffraction. The MgO/alumina prepared from Mg(acac)2·2H2O shows high dispersion of Mg species which are stable against sintering even when calcined to 500°C. The incremental SO2sorption capacity of this material shows nearly 1 mol SO2/mol Mg2+in the sample. The sample prepared from Li(acac) shows more SO2adsorption than the MgO/alumina for loadings <150 μmol/g alumina. However, the LiO/alumina samples show low incremental adsorption of SO2per mol of Li ion (0.12 mol/mol) at metal loadings greater than 150 μmol/g alumina. These results are discussed in the framework of ensemble theory in the light of the solution chemistry of the metal acetylacetonates.
Surface free energy (SFE) plays an important role in microfluidic device operation. Photosensitiv... more Surface free energy (SFE) plays an important role in microfluidic device operation. Photosensitive glasses such as APEX offer numerous advantages over traditional glasses for microfluidics, yet the SFE for APEX has not been previously reported. We calculate SFE with the Owens/Wendt geometric method by using contact angles measured with the Sessile drop technique. While the total SFE for APEX is found to be similar to traditional microstructurable glasses, the polar component is lower, which is likely attributable to composition. The SFE was modified at each stage of device fabrication, but the SFE of the stock and fully processed glass was found to be approximately the same at a value of 51 mJ/m^2. APEX exhibited inconsistent wetting behavior attributable to an inhomogeneous surface chemical composition. Means to produce more consistent wetting of photosensitive glass for microfluidic applications are discussed.
This is an illustrative image of a system of microfluidic structures in which the spectroscopic t... more This is an illustrative image of a system of microfluidic structures in which the spectroscopic tests are performed such that the spectrometers are coplanar with the microfluidic structures.
The sidewall of a photodefinable glass microstructure taken using the scanning electrom microscop... more The sidewall of a photodefinable glass microstructure taken using the scanning electrom microscope (SEM). Surface roughness is reduced from several microns to a root-mean-square value of 32 nm.
We are reporting the fluorescence quenching, IR, Raman, 1H-NMR, and potentiometric studies for th... more We are reporting the fluorescence quenching, IR, Raman, 1H-NMR, and potentiometric studies for the Zn2+:adenine and the Cd2+:adenine systems under ambient conditions. IR and Raman spectra suggest that Zn2+ and Cd2+ interact with adenine but the modes of interaction differ. Fluorescence spectra indicate that the interaction involving Zn2+ is more favorable than that of Cd2+, and this effect is due to the difference in ionic radii. 1H-NMR, potentiometry, and speciation diagrams indicate the formation of strong metal ion adenine complexes. Potentiometric titrations of the heavier member of group 12 metals (Hg2+) show similar results to that of Zn2+ and Cd2+. Some differences in the 1H-NMR experiments appeared between both (Zn2+ and Cd2+) compared to that of Hg2+. Due to the fluorescence quenching of adenine, adenine can be used as a sensor of Zn2+ and Cd2+.
Poly(R-3-hydroxybutyrate) (PHB) is a crystalline biological polyester. Its biocompatibility and b... more Poly(R-3-hydroxybutyrate) (PHB) is a crystalline biological polyester. Its biocompatibility and biodegradability cause this natural plastic to be widely studied in the biomedical industry. Its inflexible character and low wettability, however, make it impractical for use in its unmodified form. The effects of narrow-band UV radiation were observed on the surface of poly(R-3-hydroxybutyrate). The surface was characterized using contact angle measurements, infrared spectroscopy, UV-Vis spectroscopy, and optical magnification. The surface underwent degradation upon exposure to 222-nm excimer radiation. Mass loss was observed in addition to the formation of carboxyl and alkenyl groups on the surface.
Poly-dimethyl-siloxane (PDMS) has found many applications in fields ranging from biology to engin... more Poly-dimethyl-siloxane (PDMS) has found many applications in fields ranging from biology to engineering. Many researchers favor PDMS for fabricating microfluidic devices, however, PDMS is a hydrophobic material by nature and hence the surface has poor wetting characteristics. It has been reported earlier that deep UV modification of PDMS surfaces gives rise to the formation of carboxylic acid groups that leads to a more hydrophilic nature. This project is aimed at studying the effects of deep UV modification of the PDMS surface by irradiating it with a 254 nm Hg lamp with irradiation times ranging from 30 minutes to 120 minutes. The increasing hydrophilic nature reaches a threshold at 90 minutes at which point it regains some of its hydrophobic characteristics. Our previous studies discussed contact angle measurements, Infrared Spectroscopy and Atomic Force Microscopy. In this work we determine surface energy, quantify the number of carboxylic acid groups on the surface and finally,...
Natural product communications, 2014
Four different cactus species growing in the United States, Stenocereus thurberi growing in Organ... more Four different cactus species growing in the United States, Stenocereus thurberi growing in Organ Pipe Cactus National Monument, Arizona, Opuntia littoralis and Opuntia ficus-indica, growing on Santa Catalina Island, California, and Opuntia stricta, growing in northern Alabama, were examined for the presence of silica bodies (opaline phytoliths). Silica bodies were found in all four of these cactus species, parallelepiped-shaped crystals in S. thurberi, and starburst-shaped crystalline structures in the three Opuntia species. In addition, the essential oils of the four cactus species were obtained by hydrodistillation and analyzed by gas chromatography - mass spectrometry. To our surprise, S. thurberi, O. littoralis, and O. ficus-indica (but not O. stricta) essential oils contained cyclic oligosiloxanes. To our knowledge, cyclic oligosiloxanes have not been previously found as essential oil components.
ABSTRACT Near-infrared (NIR) time-resolved fluorescence detection in capillary electrophoresis (C... more ABSTRACT Near-infrared (NIR) time-resolved fluorescence detection in capillary electrophoresis (CE) has proven to be a viable technique for the identification of analytes separated by CE. Because of advances in excitation sources, NIR-labeling dyes, electronic hardware, and photon transduction, it is possible to evaluate fluorescence lifetimes on-line. This review will present the fundamental methods and advantages of NIR time-resolved fluorescence detection. NIR dyes, timing electronics, excitation and detection sources, data evaluation, and novel applications will be presented.
Methods in molecular biology (Clifton, N.J.), 2006
The use of microfluidic devices is making rapid inroads in the modern laboratory. Traditionally, ... more The use of microfluidic devices is making rapid inroads in the modern laboratory. Traditionally, devices have been manufactured in silica owing to its well-understood surface chemistry and micromachining techniques that are ubiquitous in the microelectronics industry. Recently researchers have begun to utilize devices fabricated from polymer substrates as an alternative to glass. Reasons include total cost and the ability to tailor physical and chemical properties. However, traditional microfabrication techniques of molds that are used to fabricate polymer devices by imprinting or injection molding are subject to similar limitations as those associated with silica. In a research and development environment, it is important that researchers have access to fabrication techniques that are rapid and easily implemented with a variety of polymer substrates. Laser ablation has been proven to be such a technique, and this chapter describes the fabrication of a simple injection tee utilizing...
The modification of polydimethylsiloxane (PDMS) by narrow band 254 nm excimer radiation under a n... more The modification of polydimethylsiloxane (PDMS) by narrow band 254 nm excimer radiation under a nitrogen atmosphere was characterized by contact angle goniometry, attenuated total reflectance infrared spectroscopy, atomic force and scanning electron microscopy. UV irradiation results in the formation of the carboxylic acids that influences the wettability of the surface. Continued exposure results in the formation of an inorganic surface (SiOx, (1
The blueprint for all cellular structures and functions is encoded in the genome of any organism.... more The blueprint for all cellular structures and functions is encoded in the genome of any organism. The genome consists of deoxyribonucleic acid (DNA) which is tightly coiled into narrow threads that, when completely stretched, reach a length of approximately 1.5 m yet possesses a width of only ~2.0 nm The threads of DNA are typically associated with many different types of proteins and are organized into structures called chromosomes that are housed within the nucleus of cells in most eukaryotic organisms. Within the human genome, there are 23 pairs of chromosomes. DNA is comprised of several different chemical units, which are a deoxyribose sugar unit, a phosphate group and one of four different nucleotide bases (adenine (A), guanine (G), cytosine (C), or thymine (T)). At a molecular level, it is the order of these bases which carries the code to build proteins within the cell that inevitably control the function of various cells and also determine the organism’s physical characteri...
Proceedings of the Water Environment Federation, 2001
Page 1. DEVELOPMENT OF AN UPSET EARLY WARNING DEVICE (UEWD) TO PREDICT DEFLOCULATION EVENTS Rober... more Page 1. DEVELOPMENT OF AN UPSET EARLY WARNING DEVICE (UEWD) TO PREDICT DEFLOCULATION EVENTS Robert F. Wimmer, Susan LR Barker, Emanuel Waddell, Allison Suggs, Laurie Locascio, Brian J. Love, and ...
Topics in Fluorescence Spectroscopy, 2003
The blueprint for all cellular structures and functions is encoded in the genome of any organism.... more The blueprint for all cellular structures and functions is encoded in the genome of any organism. The genome consists of deoxyribonucleic acid (DNA) which is tightly coiled into narrow threads that, when completely stretched, reach a length of approximately 1.5 m yet ...
2012 Proceedings of IEEE Southeastcon, 2012
This work manifests the use of microstructures made in Apex TM photosensitive glass for in-plane ... more This work manifests the use of microstructures made in Apex TM photosensitive glass for in-plane investigation of microfluidic systems by demonstrating the ability to detect chemical fluids through etched glass sidewalls. Absorption spectra of liquid ethanol in the near infrared (NIR) region and Raman spectroscopy of dimethyl sulfoxide in microcuvettes made in Apex TM photosensitive glass demonstrate the high potential of photosensitive glass processing in microfluidic applications in which stacks of microfluidic systems are analyzed from the sidewalls. This eliminates the need for non-planar observation of microfluidic systems.
Organic Photonic Materials and Devices X, 2008
The complementary tools of atomic force microscopy (AFM) and Raman spectroscopy are used to extra... more The complementary tools of atomic force microscopy (AFM) and Raman spectroscopy are used to extract information on the microstructural properties of nanocomposite n-doped Si (n-Si) and Ag/n-Si films deposited on Si(111) substrates at 400 °C and 550 °C. AFM measurements indicated that Ag/n-Si films had grain sizes and roughness values one order of magnitude higher than n-doped Si films. The onset of metal-mediated crystallization of a-Si in Ag/n-Si films at ~ 400 °C is confirmed by Raman spectroscopy. Spectral Raman red-shifts of the transverse optical phonon region compared to monocrystalline silicon originate from the interplay of phonon confinement and higher defect density caused by n-type doping. Two protocols using the etchants ammonium fluoride -HF (2%::4% ) and ammonium citrate-acetic acidhydrogen peroxide (2.5%::2.5%::2%) solutions were investigated. A comparison between non-etched and etched films showed little variability in roughness indicating retention of the microstructure.
Review of Scientific Instruments, 1999
A fiber-optic-based multichannel time-correlated single-photon-counting device with subnanosecond... more A fiber-optic-based multichannel time-correlated single-photon-counting device with subnanosecond time resolution was developed. A passively mode-locked Ti:sapphire laser provided the excitation source for 12 separate time-correlated single-photon counting channels in which three single-photon avalanche diode detectors were used to analyze the fluorescence from the channels. Single-mode optical fibers provided the conduit for the excitation light as well as the fluorescence emission. We determined that the excitation pulses undergo a temporal spread of 50 fs, a spectral spread of 0.2 nm, and remained nearly transform limited. The average instrument response function of each channel was determined to be 181 ps ͑full width at half maximum͒. The fluorescence lifetime of a representative near-infrared dye, aluminum tetrasulfonated naphthalocyanine, was determined to be 3.08 ns using this fiber-optic-based multichannel time-correlated single-photon-counting device.
Microsystem Technologies, 2013
This work manifests the use of microstructures made in Apex TM photosensitive glass for in-plane ... more This work manifests the use of microstructures made in Apex TM photosensitive glass for in-plane investigation of microfluidic systems by demonstrating the ability to detect chemical fluids through etched glass sidewalls. Absorption spectra of liquid ethanol in the near infrared (NIR) region and Raman spectroscopy of dimethyl sulfoxide in microcuvettes made in Apex TM photosensitive glass demonstrate the high potential of photosensitive glass processing in microfluidic applications in which stacks of microfluidic systems are analyzed from the sidewalls. This eliminates the need for non-planar observation of microfluidic systems.
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Papers by emanuel waddell