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Biomedical subjects

B C Anderson

Publications and source records attributed to B C Anderson.

At least 19 recordsLinked to original sources
PubMed2006

Field investigation of advanced filtration for phosphorus removal from constructed treatment wetland effluents.

Three sorptive media, blast furnace slag, cement clinker, and gravel were investigated for their capacity to remove phosphorus in a subsurface flow constructed treatment wetland post-treatment filter. Three filters were designed: two containing a mixture of either slag and gravel or clinker and gravel, and one with gravel only as the control filter. They were installed as a demonstration polishing treatment step to a constructed treatment wetland treating residential wastewater collected from 137 mobile home units at the Sunny Creek Estates Mobile Home Park. The filters were commissioned during the summer of the field season, with the data gathering taking place over a period of one year. The slag filter consistently had the lowest outflow dissolved phosphorus concentrations (0.27 +/- 0.08 mg l(-1), n=21), whereas the clinker filter had the highest outflow dissolved phosphorus concentrations (0.72 +/- 0.20 mg l(-1), n=23). The clinker filter performed well below expectations based on previous laboratory investigations, possibly due to lower pH conditions encountered in the field study. All of the filters maintained relatively constant outflow concentrations of phosphorus below 1 mg l(-1), despite varying input conditions and environmental factors such as temperature and phosphorus loading, and the occurrence of net export of phosphorus from the wetland. Net export of phosphorus from the filters occurred in the winter months, which was attributed to the decrease in input phosphorus concentrations below the maintained outflow concentrations (leading to phosphorus desorption), rather than cold temperatures or failure of the filter. Although the exact mechanisms of phosphorus removal are still under investigation, the results from this field study allowed for recommendations to be made for improving phosphorus removal at the Sunny Creek Estates constructed treatment wetland, in addition to providing valuable information for new and existing constructed treatment wetlands in cold climate areas.

Adsorption↗
PubMed2006

Trace metal levels in sediments deposited in urban stormwater management facilities.

Characteristics of solids recovered from stormwater best management practice (BMP) facilities, including stormwater ponds, constructed wetlands, an infiltration basin, a biofilter, a stormwater treatment clarifier, and three-chamber oil and grit separators were described with respect to their metal chemistry. The reported trace metal concentrations in BMP sediments were assessed against the Ontario Sediment Quality Guidelines. Between 80 to 100% of all samples were marginally-to-intermediately polluted by Cd, Cr, Cu, Fe, Pb, Mn, Ni and Zn. Severe pollution of sediments was noted for Cr (122 microg/g), Cu (151 and 196 microg/g), Mn (1,259 and 1,433 microg/g), and Zn (1,116 microg/g), at several facilities studied, and even higher levels of metals were reported in the literature for certain oil and grit separators. With respect to individual BMPs, the severe pollution was found in sediments from oil and grit separators (for Cd, Cr, Cu, Pb and Zn), the stormwater clarifier sludge (Cu, Mn and Zn), a biofilter (Cu and Mn), an industrial area stormwater pond (Cu only), and a commercial/residential pond (Cr only). Finally, the chemical pollution of pond sediment triggered toxicity testing at some of the facilities studied, and sediment toxicity was confirmed at several sites.

Canada↗
PubMed2003

Winter operation of an on-stream stormwater management pond.

The winter operation of an on-stream stormwater management pond in Kingston, Canada is characterised. The pond froze over in late November. Ice thickness varied from 0.2 to 0.5 m, and initially, was well described by Stefan's formula. The measured and modelled velocity field indicated a fast flow region, a small dead zone and a large recirculating zone. During a snowmelt event, near-bottom velocities reached 0.05 m x s(-1), but were not sufficient to scour the bottom sediment. Pond water temperature increased with depth, from 0.5 degrees C to 3.5 degrees C. The dissolved oxygen (DO) levels observed in the pond (6-13 mg x L(-1)) indicated stable aerobic conditions at the sediment-water interface. In one brief episode, DO fell to zero after a long cold spell. Reduction in DO readings from inlet to outlet indicated an oxygen consumption of about 1.7 kg x day(-1). pH ranged from 7.1 to 8.9. Conductivity readings indicated large quantities of total dissolved solids, representing mostly chloride from de-icing agents. During baseflow, conductivity increased with depth (total dissolved solids concentrations up to 1,200 mg x L(-1) near the bottom), indicating density stratification. Average trace metal concentrations were mostly below detection limits.

Geologic Sediments↗
PubMed2002

Use of leaching chambers for on-site sewage treatment.

An innovative chamber system was installed for on-site sewage treatment beneath an active parking lot at a restaurant near Cornwall, Ontario. The configuration of this prototype system used polyethylene leaching chambers over which wastewater was allowed to trickle. The chambers were vented to the surface to provide direct, passive air transfer. This demonstration project was examined as a cost-effective wastewater treatment alternative for a very constrained site. The leaching chambers were installed over a geotextile-covered sand filter bed. Chamber sidewall contact contributed an additional 50% to the total soil contact area hence justification for a footprint reduction. A labile carbon source (sawdust) was added into one half of the bed to encourage dissimilatory denitrification. Average hydraulic loading was 50 l m(-1) day(-1) (5 cm day(-1)). Treatment rates exceeded more than 4 orders of magnitude removal for E. coli; 90% biochemical oxygen demand; ammonium; and 99% total phosphorus. Nitrate-N on the carbon-amended side averaged 0.6 mg l(-1) compared with 8.6 mg l(-1) on the (non-carbon) control side. This project has demonstrated that effective on-site treatment can be accomplished. Flow and load equalization, pulse dosing, chamber venting, phosphorus precipitation, and denitrification were keys to treatment success. Applications include domestic and commercial sites.

Biodegradation, Environmental↗
PubMed2002

Critical issues for stormwater ponds: learning from a decade of research.

The Queen's University/National Water Research Institute Stormwater Quality Enhancement Group has been actively researching stormwater ponds for the past decade, using a fully instrumented on-line system in Kingston, Ontario, Canada as a representative field installation of this group of stormwater best management practices, along with comprehensive surveys of other facilities as well. From this body of research, the Group has concluded that there are a number of identifiable factors, termed critical issues, which will significantly influence the success, failure and sustainability of these BMPs. Such factors will be important to a very diverse group of stakeholders in stormwater management, including designers, owners/operators, regulatory authorities and the general public. These factors can be grouped within the categories of initial design, operation and maintenance, performance and adaptive design. From this work, it is concluded that the so-called first generation quantity-control ponds may be outdated today, compared with the modern focus on quantity and quality issues in the second generation systems; nonetheless, without consideration of these critical issues and flexible design practices which can account for emerging or future issues, the current systems also run the risk of becoming outdated before the end of their design lives.

Benchmarking↗
PubMed2001

Understanding drug release from poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) gels.

Experimental and mathematical studies were performed to understand the release mechanism of small molecular weight compounds from poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) polymer gels (trademarked Pluronic by BASF Corp.) of various concentrations. Studies of the diffusion coefficient of solutes in the polymer gels were performed using a novel technique to predict movement of drugs within the gel as release occurs. Studies were also performed to determine the diffusion coefficient of water in the polymer gel, as it is this parameter that controls the dissolution rate of the polymer, and in turn, the drug release rate. A model was formulated and solved numerically to determine the controlling release mechanism. By parameter modification, this algorithm for determining the overall mass of drug released from a drug loaded gel can be used for a number of drugs and for a wide range of initial polymer concentrations. Drug release data were obtained with a novel experimental setup and were used to verify the accuracy of the overall solution of the model. The results of the model indicate that although the rate of polymer dissolution ultimately controls the drug release, about 5% of the release is due to diffusion at the gel/liquid interface, giving rise to a slightly non-linear release. It was also found that agitation speed greatly affects the dissolution rates of these polymer gels.

Drug Delivery Systems↗
PubMed2000

Effect of camera angulation on adaptation of CAD/CAM restorations.

PURPOSE: A significant concern with computer-assisted design/computer-assisted manufacturing (CAD/CAM)-produced prostheses is the accuracy of adaptation of the restoration to the preparation. The objective of this study is to determine the effect of operator-controlled camera misalignment on restoration adaptation. MATERIALS AND METHODS: A CEREC 2 CAD/CAM unit (Sirona Dental Systems, Bensheim, Germany) was used to capture the optical impressions and machine the restorations. A Class I preparation was used as the standard preparation for optical impressions. Camera angles along the mesio-distal and buccolingual alignment were varied from the ideal orientation. Occlusal marginal gaps and sample height, width, and length were measured and compared to preparation dimensions. For clinical correlation, clinicians were asked to take optical impressions of mesio-occlusal preparations (Class II) on all four second molar sites, using a patient simulator. On the adjacent first molar occlusal surfaces, a preparation was machined such that camera angulation could be calculated from information taken from the optical impression. Degree of tilt and plane of tilt were compared to the optimum camera positions for those preparations. RESULTS: One-way analysis of variance and Dunnett C post hoc testing (alpha = 0.01) revealed little significant degradation in fit with camera angulation. Only the apical length fit was significantly degraded by excessive angulation. The CEREC 2 CAD/CAM system was found to be relatively insensitive to operator-induced errors attributable to camera misalignments of less than 5 degrees in either the buccolingual or the mesiodistal plane. The average camera tilt error generated by clinicians for all sites was 1.98 +/- 1.17 degrees.

Analysis of Variance↗
PubMed1999

Congenital Baylisascaris sp. larval migrans in a newborn lamb.

A 3-day-old domestic lamb, moribund since birth, was submitted as part of a diagnostic effort concerning weak newborn lambs due possibly to congenital Bluetongue virus infection. Gross lesions were consistent with such an event. Histologic examination of cerebrum and cerebellum revealed multiple granulomas, the age of which required prenatal development. These contained larvae compatible with those of Baylisascaris sp. This finding together with evidence that parents of children with neural larval migrans have been seropositive for ascarid antigen suggests that mammalian fetuses in general should be added to the list of those at risk for neural larva migrans due to ascarid parasites.

Animals↗
PubMed1998

Cryptosporidiosis in bovine and human health.

Cryptosporidiosis, which is caused by Cryptosporidium parvum and was discovered in mice at the turn of the century, emerged as a frequently reported intestinal disease of animals and humans in the 1980s when its zoonotic potential was recognized. In recent years, the public has become aware of severe cryptosporidiosis because of its incidence in AIDS patients and because of massive outbreaks of cryptosporidial enteritis among the general populace worldwide from contaminated drinking water. Livestock and human wastes that were laden with oocysts of cryptosporidia have been incriminated in some cases. Intestinal cryptosporidiosis of livestock causes a brief diarrheal disease and probably does not hinder lifetime production in most cases. However, serious disease and deaths may sometimes result from complications from other pathogens and various other detrimental factors. Adolescent and adult cattle can carry C. parvum but probably do not shed large numbers of the parasite. However, certain cattle of all ages shed billions of the apparently nonzoonotic Cryptosporidium muris, which also was first discovered in mice around the turn of the century. Cryptosporidium muris infects only the glands of the stomach (abomasum in cattle), usually causes no overt illness, but retards acid production. Protein digestion in the abomasum probably is retarded, and, in fact, milk production in cows that are chronically afflicted with C. muris is reduced about 13%. Growing calves may be adversely affected also. Therefore, as concerns the dairy industry, the discussion of cryptosporidia involves efficient cattle agriculture, public health, and the environment.

Animals↗
PubMed1997

Possible transmission of parvovirus B19 from intravenous immune globulin.

To look for genetic changes in human parvovirus B19 that might be associated with chronic infection, we sequenced B19 DNA obtained from serum specimens collected over an approximately 1-year period from a patient with systemic vasculitis. A comparison of the nucleotide sequences of the VP1/VP2 gene from four specimens revealed an abrupt change in the B19 genotype that coincided with initiation of intravenous immune globulin (IVIG) therapy. We suspect that one or more of the lots of IVIG administered to the patient were contaminated with B19. If true, this finding suggests that investigators must be careful in linking B19 infection to disease based on detection of B19 DNA in persons who have received multiple unit blood products.

Antibodies, Viral↗