scholarly journals Delayed Release of Intracellular Microcystin Following Partial Oxidation of Cultured and Naturally Occurring Cyanobacteria

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 335
Author(s):  
Katherine E. Greenstein ◽  
Arash Zamyadi ◽  
Caitlin M. Glover ◽  
Craig Adams ◽  
Erik Rosenfeldt ◽  
...  
Keyword(s):  
Partial Oxidation ◽  
Chlorine Dioxide ◽  
Drinking Water Treatment ◽  
The United States ◽  
Oxidation Processes ◽  
Filter Surface ◽  
Effective Barrier ◽  
Delayed Release ◽  
Naturally Occurring ◽  
Extracellular Form

Oxidation processes can provide an effective barrier to eliminate cyanotoxins by damaging cyanobacteria cell membranes, releasing intracellular cyanotoxins, and subsequently oxidizing these toxins (now in extracellular form) based on published reaction kinetics. In this work, cyanobacteria cells from two natural blooms (from the United States and Canada) and a laboratory-cultured Microcystis aeruginosa strain were treated with chlorine, monochloramine, chlorine dioxide, ozone, and potassium permanganate. The release of microcystin was measured immediately after oxidation (t ≤ 20 min), and following oxidant residual quenching (stagnation times = 96 or 168 h). Oxidant exposures (CT) were determined resulting in complete release of intracellular microcystin following chlorine (21 mg-min/L), chloramine (72 mg-min/L), chlorine dioxide (58 mg-min/L), ozone (4.1 mg-min/L), and permanganate (391 mg-min/L). Required oxidant exposures using indigenous cells were greater than lab-cultured Microcystis. Following partial oxidation of cells (oxidant exposures ≤ CT values cited above), additional intracellular microcystin and dissolved organic carbon (DOC) were released while the samples remained stagnant in the absence of an oxidant (>96 h after quenching). The delayed release of microcystin from partially oxidized cells has implications for drinking water treatment as these cells may be retained on a filter surface or in solids and continue to slowly release cyanotoxins and other metabolites into the finished water.

scholarly journals Indigenous bacterial spores as indicators of Cryptosporidium inactivation using chlorine dioxide

2003 ◽  
Vol 1 (2) ◽  
pp. 91-100 ◽  
Author(s):  
Sophie Verhille ◽  
Ron Hofmann ◽  
Christian Chauret ◽  
Robert Andrews
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Chlorine Dioxide ◽  
Treatment Plant ◽  
Drinking Water Treatment ◽  
Water Treatment Plant ◽  
Common Species ◽  
Plant Performance ◽  
Inactivation Kinetics ◽  
Naturally Occurring

This objective of this study was to explore the practicality of monitoring naturally occurring organisms to predict drinking water treatment plant performance, in this case for the reduction of Cryptosporidium. Surface and ground water from seven drinking water treatment plants across North America that use chlorine dioxide were surveyed for aerobic and anaerobic bacterial spore concentrations. The concentrations of total spores were usually high enough in both raw and treated water to allow 4- to 5-log reductions to be observed across the treatment train by filtering up to 2 l of sample. These results suggested that naturally occurring treatment-resistant spores could be candidates as indicators of treatment performance. However, to be useful as indicators for Cryptosporidium reduction, the organisms would have to exhibit similar resistances to disinfection (chlorine dioxide in this case) in order to be useful. The inactivation kinetics of seven of the most common species were determined, and all were observed to be considerably more susceptible to chlorine dioxide inactivation than Cryptosporidium as reported in the literature. This study therefore did not identify an appropriate ambient microbial indicator for Cryptosporidium control.

scholarly journals International Real Estate Review

2008 ◽  
Vol 11 (2) ◽  
pp. 75-104
Author(s):  
Robert A. Simons ◽  
◽  
Jesse Saginor ◽  
Aly H. Karam ◽  
Hlengani Baloyi ◽  
...  
Keyword(s):  
South Africa ◽  
Contingent Valuation ◽  
Probit Model ◽  
The United States ◽  
Research Issues ◽  
Face To Face ◽  
Perceptions Of Risk ◽  
Bidder Behavior ◽  
Naturally Occurring ◽  
Residential Properties

This study reports the results of a contingent valuation (CV) survey that was carried out in Johannesburg, South Africa. Students at Wits University conducted more than 300 face-to-face interviews with Africans living and/or working in Soweto, an African township located on the outskirts of Johannesburg, and nearby areas. The questions they asked were designed to determine the perceptions of risk regarding airborne mine dust and radon, a naturally occurring gas, and the effect that these perceptions had on the valuation of residential properties impacted by these substances. A probit model was used to evaluate the determinants of bidder behavior, using respondent demographics and other characteristics as independent variables. Residential property discounts for potentially contaminated housing sites by marginal bidders at the top of the market varied from -24% to -50%. Research issues in developing countries were addressed. Contingent valuation results in South Africa were compared to published results in the United States.

scholarly journals Chloroplast Noncoding DNA Sequences Reveal Genetic Distinction and Diversity between Wild and Cultivated Prunus yedoensis

2017 ◽  
Vol 142 (6) ◽  
pp. 434-443
Author(s):  
Eun Ju Cheong ◽  
Myong-Suk Cho ◽  
Seung-Chul Kim ◽  
Chan-Soo Kim
Keyword(s):  
United States ◽  
Dna Sequences ◽  
The United States ◽  
Jeju Island ◽  
Noncoding Dna ◽  
Noncoding Regions ◽  
Naturally Occurring ◽  
Prunus Yedoensis ◽  
History Of ◽  
Ornamental Trees

Cultivated flowering cherries (Prunus subgenus Cerasus), which are one of the most popular ornamental trees around the world, have been developed through artificial hybridizations among wild flowering cherries. Among the hundreds of cultivars of flowering cherries, Prunus ×yedoensis ‘Somei-yoshino’ is the most common and widespread. However, its origin and genetic relationship to wild P. yedoensis, naturally occurring on Jeju Island, South Korea, have long been debated. We used sequence polymorphisms in eight chloroplast DNA (cpDNA) noncoding regions to distinguish wild and cultivated flowering cherries among 104 individuals (55 accessions). We were able to distinguish two distinct groups, one corresponding to wild P. yedoensis collections from Jeju Island and the other collections of cultivated P. ×yedoensis from Korea, Japan, and the United States. The chlorotype diversity of wild P. yedoensis in Jeju Island and cultivated P. ×yedoensis collections in the United States was quite high, suggesting multiple natural hybrid origins and long history of cultivation from different original sources, respectively.

scholarly journals Current State of Anthrax Vaccines and Key R&D Gaps Moving Forward

2020 ◽  
Vol 8 (5) ◽  
pp. 651 ◽  
Author(s):  
Adam Clark ◽  
Daniel N. Wolfe
Keyword(s):  
Vaccine Development ◽  
The United States ◽  
Post Exposure Prophylaxis ◽  
Vaccine Research ◽  
Anthrax Vaccine ◽  
Current State ◽  
Naturally Occurring ◽  
Regulatory Frameworks ◽  
Exposure Prophylaxis ◽  
Anthrax Vaccines

A licensed anthrax vaccine has been available for pre-exposure prophylaxis in the United States since 1970, and it was approved for use as a post-exposure prophylaxis, in combination with antibiotic treatment, in 2015. A variety of other vaccines are available in other nations, approved under various regulatory frameworks. However, investments in anthrax vaccines continue due to the severity of the threat posed by this bacterium, as both a naturally occurring pathogen and the potential for use as a bioweapon. In this review, we will capture the current landscape of anthrax vaccine development, focusing on those lead candidates in clinical development. Although approved products are available, a robust pipeline of candidate vaccines are still in development to try to address some of the key research gaps in the anthrax vaccine field. We will then highlight some of the most pressing needs in terms of anthrax vaccine research.

Naturally Occurring Asbestos Assessment, Exposure Prevention Strategies During Construction, and Capping for Long-Term Protection: a California, USA Example

2020 ◽  
Author(s):  
Sarah Kalika
Keyword(s):  
School Improvement ◽  
Best Practices ◽  
Residential Buildings ◽  
The United States ◽  
Guidance Document ◽  
School Construction ◽  
Improvement Project ◽  
Naturally Occurring ◽  
Naturally Occurring Asbestos ◽  
Sampling Procedures

<p>The government of California, in the United States, has created requirements that are intended to protect the public from naturally occurring asbestos (NOA), partly due to the widespread areas in which asbestos minerals (including chrysotile and various amphiboles) are found within the state.Over ten years ago, the California Department of Toxic Substances Control Schools Unit published a thorough set of guidelines for addressing NOA at school construction sites.Their guidance document includes soil sampling procedures and frequency, recommended laboratory analytical testing methods, construction best practices to protect nearby residents from airborne exposures, capping methods to prevent re-exposure to students and public following the completion of the school improvement project, and follow-up procedures to ensure the capping method remains protective.Many of these best practices have been adapted into the construction process for commercial and residential buildings.<span>  </span>In California, protection of air is the regulated by Air Quality Management Districts, who regulate the generation of airborne asbestos as an air pollutant.Additionally, workers who are employed by a company, and working at a job site where asbestos is present, are protected by California Occupational Safety and Health (Cal-OSHA). Cal-OSHA requires varying protective measures to be implemented, based on the amount of asbestos that the worker is exposed to during their time at the construction project.This presentation will review the various regulations and best practices used in California by comparing a school construction project with a commercial office building. </p>

scholarly journals Development of chlorine dioxide-related by-product models for drinking water treatment

2002 ◽  
Vol 36 (1) ◽  
pp. 330-342 ◽  
Author(s):  
Caroline Korn ◽  
Robert C. Andrews ◽  
Michael D. Escobar
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Chlorine Dioxide ◽  
Drinking Water Treatment ◽  
Product Models

scholarly journals Blood Chimerism Confounds Genetic Relative Susceptibility Testing for Classical Scrapie in Sheep

2009 ◽  
Vol 21 (3) ◽  
pp. 295-305 ◽  
Author(s):  
David A. Schneider ◽  
Ahmed Tibary ◽  
Terje Raudsepp ◽  
Pranab J. Das ◽  
Katherine I. O'Rourke
Keyword(s):  
Susceptibility Testing ◽  
Transmissible Spongiform Encephalopathy ◽  
The United States ◽  
Classical Scrapie ◽  
Spongiform Encephalopathy ◽  
Nucleotide Polymorphisms ◽  
Tissue Samples ◽  
Relative Susceptibility ◽  
Prnp Genotype ◽  
Naturally Occurring

Classical scrapie disease is a transmissible spongiform encephalopathy of sheep that is enzootic in the United States. Susceptibility of sheep to classical scrapie is linked to single nucleotide polymorphisms in the prion protein gene ( PRNP), forming the basis for genetic testing strategies used by national efforts to eradicate scrapie. Such efforts are occasionally hampered by inconclusive results stemming from the detection of “complex” genotypes. Naturally occurring cases of ovine chimerism are thought to account for some of these instances. In the current report, 4 naturally occurring ovine chimeras are documented through cytogenetic and molecular analyses. All 4 of these sheep had chimeric cells circulating in their blood. Blood and alternate tissue samples of ear punch and hair bulbs from one of these chimeras was submitted in batch with similar samples from control sheep for routine scrapie genetic relative susceptibility testing. A complex PRNP genotype was detected in the blood of the chimeric female but not in the alternate tissue samples or in the control sheep samples. The results demonstrate that naturally occurring blood chimerism can confound current testing efforts. The potential impacts of undetected chimeras on current scrapie eradication efforts are discussed.

Role of membrane technology in drinking water treatment in the United States

Desalination ◽  
1997 ◽  
Vol 113 (2-3) ◽  
pp. 119-127 ◽  
Author(s):  
Joseph G. Jacangelo ◽  
R. Rhodes Trussell ◽  
Montgomery Watson
Keyword(s):  
United States ◽  
Drinking Water ◽  
Water Treatment ◽  
Drinking Water Treatment ◽  
The United States ◽  
Membrane Technology
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