Author
Pedro J. J. Alvarez
Other affiliations: University of Minnesota, University of Michigan, Universidade Federal de Santa Catarina ...read more
Bio: Pedro J. J. Alvarez is an academic researcher from Rice University. The author has contributed to research in topics: Bioremediation & Medicine. The author has an hindex of 89, co-authored 378 publications receiving 34837 citations. Previous affiliations of Pedro J. J. Alvarez include University of Minnesota & University of Michigan.
Topics: Bioremediation, Medicine, Chemistry, Adsorption, Bioaugmentation
Papers published on a yearly basis
Papers
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TL;DR: Buckminsterfullerene (C60) can form water suspensions that exert toxic effects in bacteria as mentioned in this paper, with evidence of protein oxidation, changes in cell membrane potential, and interruption of cellular respiration.
Abstract: Buckminsterfullerene (C60) can form water suspensions (nC60) that exert toxic effects. While reactive oxygen species (ROS) generation has been implicated as the mechanism for mammalian cytotoxicity, we propose that nC60 exerts ROS-independent oxidative stress in bacteria, with evidence of protein oxidation, changes in cell membrane potential, and interruption of cellular respiration. This mechanism requires direct contact between the nanoparticle and the bacterial cell and differs from previously reported nanomaterial antibacterial mechanisms that involve ROS generation (metal oxides) or leaching of toxic elements (nanosilver).
217 citations
19 Feb 2020
TL;DR: This review assesses the occurrence and variability of ARGs in livestock wastes and their potential propagation pathways to human pathogens, and evaluates the ARG removal efficiency of common livestock waste management approaches.
Abstract: Antibiotics are widely used in animal husbandry, and various types of antibiotic resistance genes (ARGs) are frequently detected in livestock waste around the world. Conventional livestock waste treatment processes do not completely remove ARGs, resulting in their release to soil and water environments. Various exposure routes of these ARGs to humans, including inhalation and ingestion of antibiotic-resistant bacteria (ARB) that harbor them, may be contributing to the rise in resistant clinical infections that are increasingly difficult to treat with antibiotics. In this review, we assess the occurrence and variability of ARGs in livestock wastes and their potential propagation pathways to human pathogens. We also review the mechanisms and environmental factors that influence the dissemination of ARGs through these pathways, and evaluate the ARG removal efficiency of common livestock waste management approaches. Challenges and research needs for assessing and mitigating the risk of antibiotic resistance dissemination from livestock waste are also presented.
215 citations
TL;DR: Toxicity was mitigated by adding an antioxidant (glutathione), which suggests that a free radical—induced mechanism or another form of oxidative stress played a role in developmental toxicity.
Abstract: The present paper summarizes, to our knowledge, the first study regarding the developmental toxicity of stable buckminsterfullerene aggregates suspended in water (nC60) using zebrafish (Danio rerio) as a vertebrate model. Zebrafish embryo survival, hatching rate, heartbeat, and pericardial edema were noted and described within 96 h of exposure. Fullerol (a hydroxylated C60 derivative, C60(OH)16-18) at 50 mg/L did not exert toxicity to zebrafish embryos. In contrast, nC60 at 1.5 mg/L delayed zebrafish embryo and larval development, decreased survival and hatching rates, and caused pericardial edema. Toxicity was mitigated by adding an antioxidant (glutathione), which suggests that a free radical-induced mechanism or another form of oxidative stress played a role in developmental toxicity.
207 citations
TL;DR: It is warned that even moderately acidic or alkaline conditions could lead to significant and localized organism effects due to toxic exposure to dissolved heavy metals and biocompatibility and ecotoxicity tests for QDs should consider in vivo and/or in situ transformations to fully characterize the potential risks to environmental health.
Abstract: Quantum dots (QDs) are increasingly being used for electronics, solar energy generation, and medical imaging applications. Most QDs consist of a heavy metal core/shell coated with amphiphilic organics that stabilize the nanoparticles and allow conjugation with biological molecules. In this study, QDs were evaluated for their effects on bacterial pure cultures, which serve as models of cell toxicity and indicators of potential impact to ecosystem health. QDs with intact surface coatings decreased growth rates of Gram positive Bacillus subtilis and Gram negative Escherichia coli but were not bactericidal. In contrast, weathering of various types of QDs under acidic (pH ≤ 4) or alkaline (pH ≥ 10) conditions significantly increased bactericidal activity due to the rapid (<1 min) release of cadmium and selenite ions following QD destabilization upon loss of the organic coating. Toxicity was mitigated by humic acids, proteins, and other organic ligands that reduced metal bioavailability. The best available scie...
200 citations
01 Jan 2008
TL;DR: It is proposed that nC60 exerts ROS-independent oxidative stress in bacteria, with evidence of protein oxidation, changes in cell membrane potential, and interruption of cellular respiration.
198 citations
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TL;DR: It is anticipated that this review can stimulate a new research doorway to facilitate the next generation of g-C3N4-based photocatalysts with ameliorated performances by harnessing the outstanding structural, electronic, and optical properties for the development of a sustainable future without environmental detriment.
Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...
5,054 citations
TL;DR: The mechanisms of generation and potential impacts of microplastics in the ocean environment are discussed, and the increasing levels of plastic pollution of the oceans are understood, it is important to better understand the impact of microPlastic in the Ocean food web.
4,706 citations
TL;DR: In this paper, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed.
Abstract: Fenton chemistry encompasses reactions of hydrogen peroxide in the presence of iron to generate highly reactive species such as the hydroxyl radical and possibly others. In this review, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed. The review covers modified versions including the photoassisted Fenton reaction, use of chelated iron, electro-Fenton reactions, and Fenton reactions using heterogeneous catalysts. Sections are devoted to nonclassical pathways, by-products, kinetics and process modeling, experimental design methodology, soil and aquifer treatment, use of Fenton in combination with other advanced oxidation processes or biodegradation, economic comparison with other advanced oxidation processes, and case studies.
3,218 citations
TL;DR: Due to complexity of soil-water system in nature, the effectiveness of biochars on remediation of various organic/inorganic contaminants is still uncertain.
3,163 citations
TL;DR: The technical feasibility of various low-cost adsorbents for heavy metal removal from contaminated water has been reviewed and it is evident from the literature survey of about 100 papers that low- cost adsorbent have demonstrated outstanding removal capabilities for certain metal ions as compared to activated carbon.
3,072 citations