A5004306492- Pharmaceutical and Antibiotic Environmental Impacts
- Water Treatment and Disinfection
- Advanced oxidation water treatment
- Antibiotic Resistance in Bacteria
- Water Quality Monitoring and Analysis
- Antibiotics Pharmacokinetics and Efficacy
- Chemical Analysis and Environmental Impact
- Wastewater Treatment and Reuse
- Dental Education, Practice, Research
- Healthcare professionals’ stress and burnout
- Innovations in Medical Education
- Microplastics and Plastic Pollution
- Environmental Chemistry and Analysis
- Chemical Reactions and Mechanisms
- Phenothiazines and Benzothiazines Synthesis and Activities
- Advanced Photocatalysis Techniques
- Global Health Workforce Issues
- bioluminescence and chemiluminescence research
- Diversity and Career in Medicine
- Chemistry and Chemical Engineering
- Medical and Biological Ozone Research
- Medical Education and Admissions
- Atmospheric chemistry and aerosols
- Odor and Emission Control Technologies
- Sleep and Work-Related Fatigue
University of Washington
2013-2024
Seattle University
2012-2020
Swiss Federal Institute of Aquatic Science and Technology
2005-2010
ETH Zurich
2006-2010
Swiss Federal Laboratories for Materials Science and Technology
2010
Georgia Institute of Technology
2004-2006
VNU University of Science
2006
Astley Ainslie Hospital
1997-1999
In U.S. Pacific Northwest coho salmon (
Ozone and hydroxyl radical (•OH) reaction kinetics were measured for 14 antibacterial compounds from nine structural families, to determine whether municipal wastewater ozonation is likely result in selective oxidation of these compounds' biochemically essential moieties. Each substrate oxidized by ozone with an apparent second-order rate constant, > 1 × 103 M-1 s-1, at pH 7, the exception N(4)-acetylsulfamethoxazole ( 2.5 102 s-1). values (pH 7) macrolides, sulfamethoxazole, trimethoprim,...
Antibiotic resistance genes (ARGs), in association with antibiotic resistant bacteria (ARB), have been identified as widespread contaminants of treated drinking waters and wastewaters. As a consequence, concerns raised that ARB or ARG transport between aquatic compartments may enhance the spread amongst non-resistant bacterial communities by means horizontal gene transfer processes. Most often, discussion focuses on probable role conjugative plasmid transposon exchange, which requires live...
This work investigated degradation (measured by qPCR) and biological deactivation culture-based natural transformation) of extra- intracellular antibiotic resistance genes (eARGs iARGs) free available chlorine (FAC), NH2Cl, O3, ClO2, UV light (254 nm), eARGs •OH, using a chromosomal ARG ( blt) multidrug-resistant Bacillus subtilis 1A189. Rate constants for four 266-1017 bp amplicons adjacent to or encompassing the acfA mutation enabling blt overexpression increased in proportion #AT+GC...
Transformation products (TPs) originating within tire tread wear particles (TWPs) are likely pervasive contaminants of roadway environments although their formation, fate, and risks poorly characterized. Here, we investigated TP formation occurring during heterogeneous reaction gas-phase ozone with the common rubber antioxidant 6PPD (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine); exposures included both pure compound TWP rubbers. Oxidative transformation occurred ozonation (∼360 ppbv),...
6PPD, a tire rubber antioxidant, poses substantial ecological risks because it can form highly toxic quinone transformation product (TP), 6PPD-quinone (6PPDQ), during exposure to gas-phase ozone. Important data gaps exist regarding the structures, reaction mechanisms, and environmental occurrence of TPs from 6PPD ozonation. To address these gaps, ozonation was conducted over 24–168 h were characterized using high-resolution mass spectrometry. The probable structures proposed for 23 with 5...
Recently, roadway releases of
We here report chemical characteristics relevant to the fate and transport of recently discovered environmental toxicant 6PPD-quinone (2-((4-methylpentan-2-yl)amino)-5-(phenylamino)cyclohexa-2,5-diene-1,4-dione or “6PPDQ”).
Sulfamethoxazole (SMX)a member of the sulfonamide antibacterial classhas been frequently detected in municipal wastewater and surface water bodies recent years. Kinetics, mechanisms, products SMX reactions with free chlorine (HOCl/OCl-) were studied detail to evaluate effect chlorination processes on fate sulfonamides wastewaters affected drinking waters. Direct available (FAC) quite rapid. A half-life 23 s was measured under pseudo-first-order conditions ([FAC]0 = 20 μM (1.4 mg/L) [SMX]0 2...
Kinetics, products, and mechanistic aspects of reactions between free available chlorine (HOCl/OCl-), ciprofloxacin (CF), enrofloxacin (EF) were extensively investigated to elucidate the behavior fluoroquinolone antibacterial agents during water chlorination processes. Although molecular structures these two substrates differ only with respect degree N(4) amine alkylation, CF EF exhibit markedly different HOCl reaction kinetics transformation pathways. reacts very rapidly at CF's secondary...
A wide variety of antibacterial compounds is rapidly oxidized by O3 and hydroxyl radical (•OH) during aqueous ozonation. Quantitative microbiological assays have been developed here or adapted from existing methods utilized to measure the resulting changes in potencies •OH treatment 13 molecules (roxithromycin, azithromycin, tylosin, ciprofloxacin, enrofloxacin, penicillin G, cephalexin, sulfamethoxazole, trimethoprim, lincomycin, tetracycline, vancomycin, amikacin) 9 structural classes...
Kinetics and mechanisms of As(III) oxidation by free available chlorine (FACthe sum HOCl OCl-), ozone (O3), monochloramine (NH2Cl) were investigated in buffered reagent solutions. Each reaction was found to be first order oxidant As(III), with 1:1 stoichiometry. FAC−As(III) O3−As(III) reactions extremely fast, pH-dependent, apparent second-order rate constants, , 2.6 (±0.1) × 105 M-1 s-1 1.5 106 at pH 7, whereas the NH2Cl−As(III) relatively slow ( = 4.3 (±1.7) 10-1 7). Experiments conducted...
Oxidation of β-lactam antibiotics by aqueous ferrate(VI) was investigated to determine reaction kinetics, sites, antibacterial activity changes, and transformation products. Apparent second-order rate constants (kapp) were determined in the pH range 6.0–9.5 for with penicillins (amoxicillin, ampicillin, cloxacillin, penicillin G), a cephalosporin (cephalexin), several model compounds. Ferrate(VI) shows an appreciable reactivity toward selected β-lactams (kapp 7 = 110–770 M–1 s–1). The...
Reactions of dissolved organic matter (DOM) with photochemically generated reactive halogen species (RHS) may represent an important natural source organohalogens within surface seawaters. However, investigation such processes has been limited by difficulties in quantifying low organohalogen concentrations the presence background inorganic halides. In this work, sequential solid phase extraction (SPE) and silver-form cation exchange filtration were utilized to desalt preconcentrate seawater...
Degradation kinetics of antibiotic resistance genes (ARGs) by free available chlorine (FAC), ozone (O3), and UV254 light (UV) were investigated in phosphate buffered solutions at pH 7 using a chromosomal ARG (mecA) methicillin-resistant Staphylococcus aureus (MRSA). For FAC, the degradation rates extracellular mecA (extra-mecA) accelerated with increasing FAC exposure, which could be explained two-step reaction model. The extra-mecA O3 followed second-order kinetics. UV exhibited tailing...
Reactions of ozone (O3) with the β-lactam antibiotics penicillin G (PG) and cephalexin (CP) have previously been found to yield products retaining antibacterial activities. These are unequivocally identified here as stereoisomeric (R)-sulfoxides each parent molecule characterized by a combination chemical analysis an activity assay. PG-(R)-sulfoxide, which is ∼15% potent PG itself, formed in ∼55% yield, whereas CP-(R)-sulfoxide, ∼83% active CP, maximum ∼34% yield. PG-(R)-sulfoxide...
Aqueous free available chlorine (FAC) can be photolyzed by sunlight and/or artificial UV light to generate various reactive oxygen species, including HO• and O(3P). The influence of this chemistry on inactivation chlorine-resistant microorganisms was investigated using Bacillus subtilis endospores as model microbial agents simulated natural solar radiation sources. Irradiation FAC solutions markedly enhanced B. spores in 10 mM phosphate buffer; increasing rate constants much 600%, shortening...