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Pedro J. J. Alvarez

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.


Papers
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TL;DR: It is shown that 20 mg/L GO interacts with the membrane-bound cytochrome c of E. coli in saline, shuttling electrons from the respiratory chain to extracellular molecular oxygen, which results in the formation of superoxide anions (O2•-), which reduces GO in 30 min.
Abstract: Microbial reduction of graphene oxide (GO) under aerobic conditions is poorly understood despite its critical role in changing GO toxicity and environmental fate. Here we show that 20 mg/L GO interacts with the membrane-bound cytochrome c of E. coli in saline, shuttling electrons from the respiratory chain to extracellular molecular oxygen. This results in the formation of superoxide anions (O2•–), which in turn reduce GO in 30 min. The critical role of superoxide was demonstrated by impeding GO reduction upon addition of superoxide dismutase, or by carrying out experiments under strictly anaerobic conditions that preclude O2•– formation. Coating GO with bovine serum albumin also stopped GO reduction, which indicates the need for direct contact between GO and the cell membrane. Cell death was observed as a consequence of GO bioreduction. Apparently, electron shuttling by GO (via membrane contact) interrupts the respiratory chain and induces oxidative stress, as indicated by a 20% decrease in electron tran...

32 citations

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TL;DR: Simulations with Monod’s equation, expressed in finite-difference form, were in reasonable agreement with the observed toluene degradation pattern in a denitrifying aquifer slurry, and illustrated the strong dependence of the degradation time on the initial active biomass concentration.
Abstract: Monod’s equation adequately described the kinetics of toluene degradation and biomass growth in denitrifying enrichments from a sandy aquifer. The cell yield was 0.6 g of cells per gram of toluene, and the Monod coefficients were \ik=0.28 g toluene/g cells/day and \IKs\N = 8.3 mg toluene/L. The specific first-order coefficient, k/\IKs\N, would be 0.033 L/mg/day. The estimated biokinetic parameters were validated in an independent kinetics experiment. Simulations with Monod’s equation, expressed in finite-difference form, were in reasonable agreement with the observed toluene degradation pattern in a denitrifying aquifer slurry, and illustrated the strong dependence of the degradation time on the initial active biomass concentration.

32 citations

Journal ArticleDOI
TL;DR: Proof of concept that permeable reactive iron barriers might be a viable approach to intercept and degrade RDX plumes is presented, and RDX was rapidly reduced in aquifier microcosms amended with Fe(0) powder, and in flow-through columns packed with steel wool.

32 citations

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TL;DR: Results illustrate the importance of considering the possibility of unintentional hindrance of catabolism associated with the addition of auxiliary carbon sources to bioremediate aquifers impacted with trace concentrations of dioxane.

32 citations

Journal ArticleDOI
TL;DR: It is demonstrated that facet-engineering significantly enhances transferrin binding to cadmium chalcogenide nanocrystals and their subsequent delivery into cancer cells, mediated by transferrin receptors, in a complex biological matrix.
Abstract: Binding of biomolecules to crystal surfaces is critical for effective biological applications of crystalline nanomaterials. Here, we present the modulation of exposed crystal facets as a feasible approach to enhance specific nanocrystal-biomolecule associations for improving cellular targeting and nanomaterial uptake. We demonstrate that facet-engineering significantly enhances transferrin binding to cadmium chalcogenide nanocrystals and their subsequent delivery into cancer cells, mediated by transferrin receptors, in a complex biological matrix. Competitive adsorption experiments coupled with theoretical calculations reveal that the (100) facet of cadmoselite and (002) facet of greenockite preferentially bind with transferrin via inner-sphere thiol complexation. Molecular dynamics simulation infers that facet-dependent transferrin binding is also induced by the differential affinity of crystal facets to water molecules in the first solvation shell, which affects access to exposed facets. Overall, this research underlines the promise of facet engineering to improve the efficacy of crystalline nanomaterials in biological applications.

31 citations


Cited by
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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

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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

Journal ArticleDOI
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

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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

Journal ArticleDOI
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