Browsing by Author "Bremer, Philip J."

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Applications of Fourier Transform Infrared Spectrometry to Studies of Copper Corrosion under Bacterial Biofilms
(1990) Geesey, Gill G.; Bremer, Philip J.
Atomic force microscopy examination of the topography of a hydrated bacterial biofilm on a copper surface
(1992-04) Bremer, Philip J.; Geesey, Gill G.; Drake, B.
A bacterium, designated CCI#8, that was isolated from a corroded copper coupon colonized both polished and unpolished copper surfaces under batch culture conditions. Atomic Force Microscopy (AFM) images revealed that the biofilm was heterogeneous in nature, both in depth and in cell distribution. Bacterial cells were shown to be associated with pits on the surface of the unpolished copper coupons. These observations support previous studies that CCI#8 is associated with the pitting corrosion of copper.
Biocorrosion
(2000) Geesey, Gill G.; Beech, Iwona; Bremer, Philip J.; Webster, Barbara J.; Wells, D. Bret
Characterization of a thin copper film to investigate microbial biofilm formation
(1991-10) Bremer, Philip J.; Geesey, Gill G.
Copper films, 6.7 nm nominal thickness, deposited by physical vapor deposition on germanium substrates appeared as coalescing aggregates of copper atoms when evaluated by atomic force microscopy. Evaluation of the Cu thin film by x-ray photoelectron spectroscopy indicated that the Cu at the surface of the film had the character of a 1 + oxidation state. These features were not significantly changed when the Cu thin film was exposed to ethylene oxide. No Ge signal was detectable prior to XPS depth profiling through the Cu thin film, indicating that the film was continuous. When films of this thickness were deposited on a cylindrical Ge internal reflection element and subsequently submerged in an aqueous medium, there was sufficient transmission of infra-red radiation through the Cu to obtain a significant water absorption band at 1640 cm−1. The intensity of the water absorption band was found to be very sensitive to changes in thickness of the copper thin film. This feature can be used to study the effect of microbial biofilms and their products on the integrity of oxidized copper surfaces in aqueous environments.
Chemical characterization of deposits associated with microbiologically influenced copper corrosion in potable water systems
(2002-04) Geesey, Gill G.; Baty, Ace M.; Bremer, Philip J.; Schamberger, P. C.; Henshaw, G. S.; Webster, Barbara J.; Wells, D. Bret
The internal surfaces of copper tubes, removed from potable water distribution systems in Australia and New Zealand, which experienced episodes of copper by-product release or "blue water," were evaluated by x-ray photoelectron spectroscopy (XPS) and dynamic secondary ion spectrometry (SIMS). Visual and microscopic inspection of the internal tube surface revealed a mosaic of deposits. Three distinct deposits were identified on the surface of tube recovered from a Grahamtown system in the Hunter Valley (HV) of Australia, whereas two distinct deposits were detected on the surface of tube retrieved from the Defense Scientific Establishment (DSE) facility in Auckland, NZ. XPSanalysis revealed the presence of organic nitrogen, with a C/N similar to living biomass, concentrated on the yellow green-surface deposit and the deposit-free area of tube from the HVsystem. In contrast, deposits and deposit-free areas on the tube from the DSE system contained no significant quantities of organic nitrogen. A secondary ion mass spectrometer (SIMS) depth profile of a corrosion deposit on the surface of tube from the HV system revealed a multi-layer structure, consisting of an organic carbon-enriched Cu(OH)2, Cu(OH)2CuCO3 layer on top of an organic carbon-depleted Cu2O layer. The structure and chemistry of the surface deposits on the HV tube were consistent with a mechanistic model involving growth of a copper oxide film under neutral or alkaline conditions modified by the presence and activities of surface-associated microorganisms. An alternative mechanism may be responsible for the copper by-product release from the tube in the DSE system, since significant quantities of organic nitrogen were not detected in deposits on tubes from this source. Based on the surface chemical data presented here, it is difficult to determine whether similar mechanisms were responsible for the copper by-product release associated with copper tube from these two different distribution systems. The results do suggests that previous models of copper surface film structure may not describe the range of reactions required to adequately explain copper by-product release under certain conditions.
Determination of the feasibility of using attenuated total reflectance fourier transform-infrared spectroscopy to evaluate thermal ageing of enamel-coated magnet wire
(1997-01) Bremer, Philip J.; Geesey, Gill G.
A study was initiated to determine the feasibility of employing attenuated total reflectance Fourier transform–infrared spectroscopy (ATR/FT–IR) to detect changes resulting from thermal ageing in the enamel of copper magnet wire. Polyamideimide (SX-81002) was cured on a zinc selenide (ZnSe) internal reflection element (IRE) coated with a thin film of metallic copper. The coated IRE was inserted in a Circle cell housed in a heating jacket and maintained at 250°C on the optical bench of an infrared spectrometer to simulate thermal ageing of enamel-coated magnet wire. Evaluation of the infrared spectra in the fingerprint region suggested that the polymer experienced chemical degradation within a 23 day period of thermal ageing. Through comparisons with controls containing no copper coatings, and ageing studies carried out at 28°C, it was determined that ageing at elevated temperature caused more pronounced chemical changes in the polymer than did exposure to the copper. These results indicate that ATR/FT–IR may be a useful tool to detect enamel fatigue after a short period of thermal ageing.
The dynamics of biofilms
(1992) Geesey, Gill G.; Stupy, M. W.; Bremer, Philip J.
The colonization of tissue and other surfaces by microbial cells results in the formation of a biofilm. The biofilm mode of existence results from selective pressures in the environment. Biofilms afford microbes greater access to nutrients, protection from antimicrobial agents and provide a buffer to changing conditions in the environment. Micro-organism that colonize a surface often compete with each other for resources but eventually form consorts which promote their survival. The population structure that develops within a biofilm on living tissue frequently reflects the health of the host organism and its surrounding environment. Displacement of a consort that is beneficial to the host by one that exhibits debilitating characteristics is a common feature of disease. A better understanding of the environmental factors that control microbial activity and population structure within biofilms should promote the development of novel approaches to control the undesirable effects of microbial colonization of surfaces relevant to medical, industrial and environmental processes.
An evaluation of biofilm development utilizing non-destructive attenuated total reflectance fourier transform infrared spectroscopy
(1991-04) Bremer, Philip J.; Geesey, Gill G.
Chemical changes that occur within a microbial biofilm during development on a germanium internal reflection element (IRE) were monitored by attenuated total reflection Fourier transform infrared spec‐troscopy (ATR/FT‐IR) for 188 h. The amount of protein detected at the IRE/medium interface increased throughout the course of the experiment. Extracellular polysaccharides were mainly produced during the initial stages of biofilm development. These results demonstrate that changes in metabolic activity of surface‐associated bacteria during biofilm development on surfaces exposed to a flowing bulk aqueous phase can be evaluated by ATR/FT‐IR.
Evaluation of biofilm microorganisms in copper corrosion
(1990) Geesey, Gill G.; Bremer, Philip J.
Influence of surface features on microbial colonization and susceptibility to corrosion of stainless steels used in the food processing industry
(1996) Geesey, Gill G.; Gillis, Richard J.; Zhang, Hong-Ji; Bremer, Philip J.
Interactions of bacteria with metals in the aquatic environment
(1993) Bremer, Philip J.; Geesey, Gill G.
Laboratory-based model of microbiologically induced corrosion of copper
(1991-07) Bremer, Philip J.; Geesey, Gill G.
The interactions of bacteria isolated from corroded copper coupons on thin films of copper evaporated onto germanium internal reflection elements were evaluated nondestructively in real time by attentuated total reflectance Fourier transform infrared spectroscopy. The films were stable in the presence of flowing or static sterile culture medium. When exposed to and colonized by the bacterium CCI 8, the copper thin film corroded. Corrosion was enhanced under quiescent conditions. In conjunction with corrosion of the copper thin film was an increase in the concentration of polysaccharide material at the copper-biofilm interface. A different bacterium (CCI 11) did not corrode the copper thin film, and the establishment of this bacterium on the copper surface prevented corrosion of the thin film by CCI 8.
Stability in aqueous media of 316l stainless steel films deposited on internal reflection elements
(1993-02) Pedraza, A. J.; Godbole, M. J.; Bremer, Philip J.; Avci, Recep; Drake, B.; Geesey, Gill G.
Thin films of 316L stainless steel were sputter-deposited on cylindrical internal reflection elements (IREs) made of germanium. These films are intended for use in Fourier transform infrared (FT-IR) spectroscopy studies on the stability of stainless steel in aqueous media. In these deposits the films tend to peel off the substrate when immersed in water, probably due to galvanic corrosion at the metal/substrate interface. Deposition of a 2-nm-thick layer of chromium oxide on the substrate prior to the deposition of the steel was beneficial on three counts. It provided an electrically insulating layer, it enhanced adhesion, and it solved the steel/germanium incompatibility problem. It was also found that annealing the substrate prior to deposition remarkably enhances the film adhesion and improves the optical properties of the substrate. The microstructure, the topography, and the chemical composition of the films were characterized by scanning and transmission electron microscopy, Auger electron spectroscopy, and atomic force microscopy. The only significant difference between the austenitic stainless steel target material and the film is that the crystalline structure of the film is body-centered cubic. The optical properties of the system germanium/metallic film/water were studied and calculated with the help of a computer program. The absorbance of the water bands in the IR range was measured in coated Ge-IRE.
Two-phase model for describing the interactions between copper ions and exopolymers from alteromonas atlantica
(1992-08) Geesey, Gill G.; Bremer, Philip J.; Smith, James J.; Muegge, M.; Jang, Larry K.
Interactions between copper ions and exopolymer from the marine film-forming bacterium Alteromonas atlantica were evaluated by a two-phase model that treats the polymer as if it exists in a phase separate from the bulk solution. The model takes into account electrostatic interactions and molecular volume changes within the polymer phase to determine the copper activity in the domain where copper interacts with the ligands on the polymer molecule(s). The volume of the polymer phase varied with pH, ionic strength, and copper ion concentration. Exopolymer recovered from chemostat cultures grown at different dilution rates exhibited unique interligand distances, number of ionizable ligands, and molecular volumes. The variations in physical properties, in part, reflected differences in polymer chemistry. The exopolymer contained a lower density of ionizable groups and a smaller molecular volume per number of ionizable groups than alginic acid. The numerical procedure yielded a stability constant of 1 × 105 L/mol for a type I complex between copper ion and exopolymer produced at a dilution rate of 0.02 h−1 that was valid over a range of hydrogen ion concentrations and ionic strengths. The approach provided useful insight on how environmental variables affect the physicochemical properties of microbial exopolymers. Key words: exopolysaccharide, metal ions, chemostat culture.
Unusual types of pitting corrosion of copper tubes in potable water systems
(1993) Geesey, Gill G.; Bremer, Philip J.; Fischer, W. R.; Wagner, D.; Keevil, C. W.; Walker, Johann; Chamberlain, A. H. L.; Angell, P.