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The Journal of Biological Chemistry Sep 1987The organic hydroperoxides tert-butyl hydroperoxide and cumene hydroperoxide are tumor promoters in the skin of SENCAR mice, and this activity is presumed to be mediated...
Generation of free radicals from organic hydroperoxide tumor promoters in isolated mouse keratinocytes. Formation of alkyl and alkoxyl radicals from tert-butyl hydroperoxide and cumene hydroperoxide.
The organic hydroperoxides tert-butyl hydroperoxide and cumene hydroperoxide are tumor promoters in the skin of SENCAR mice, and this activity is presumed to be mediated through the activation of the hydroperoxides to free radical species. In this study we have assessed the generation of free radicals from organic hydroperoxides in the target cell (the murine basal keratinocyte) using electron spin resonance. Incubation of primary isolates of keratinocytes from SENCAR mice in the presence of spin traps (5,5-dimethyl-1-pyrroline N-oxide or 2-methyl-2-nitrosopropane) and either tert-butyl hydroperoxide or cumene hydroperoxide resulted in the generation and detection of radical adducts of these spin traps. tert-Butyl alkoxyl and alkyl radical adducts of 5,5-dimethyl-1-pyrroline N-oxide were detected shortly after addition of tert-butyl hydroperoxide, whereas only alkyl radical adducts were observed with cumene hydroperoxide. Spin trapping of the alkyl radicals with 2-methyl-2-nitrosopropane led to the identification of methyl and ethyl radical adducts following both tert-butyl hydroperoxide and cumene hydroperoxide exposures. Prior heating of the cells to 100 degrees C for 30 min prevented radical formation. The radical generating capacity of subcellular fractions of these epidermal cells was examined using 5,5-dimethyl-1-pyrroline N-oxide and cumene hydroperoxide, and this activity was confined to the 105,000 X g supernatant fraction.
Topics: Animals; Benzene Derivatives; Carcinogens; Cyclic N-Oxides; Electron Spin Resonance Spectroscopy; Epidermis; Free Radicals; Keratins; Mice; Peroxides; tert-Butylhydroperoxide
PubMed: 2442158
DOI: No ID Found -
Microbiological Reviews Dec 1996Production and consumption processes in soils contribute to the global cycles of many trace gases (CH4, CO, OCS, H2, N2O, and NO) that are relevant for atmospheric... (Review)
Review
Production and consumption processes in soils contribute to the global cycles of many trace gases (CH4, CO, OCS, H2, N2O, and NO) that are relevant for atmospheric chemistry and climate. Soil microbial processes contribute substantially to the budgets of atmospheric trace gases. The flux of trace gases between soil and atmosphere is usually the result of simultaneously operating production and consumption processes in soil: The relevant processes are not yet proven with absolute certainty, but the following are likely for trace gas consumption: H2 oxidation by abiontic soil enzymes; CO cooxidation by the ammonium monooxygenase of nitrifying bacteria; CH4 oxidation by unknown methanotrophic bacteria that utilize CH4 for growth; OCS hydrolysis by bacteria containing carbonic anhydrase; N2O reduction to N2 by denitrifying bacteria; NO consumption by either reduction to N2O in denitrifiers or oxidation to nitrate in heterotrophic bacteria. Wetland soils, in contrast to upland soils are generally anoxic and thus support the production of trace gases (H2, CO, CH4, N2O, and NO) by anaerobic bacteria such as fermenters, methanogens, acetogens, sulfate reducers, and denitrifiers. Methane is the dominant gaseous product of anaerobic degradation of organic matter and is released into the atmosphere, whereas the other trace gases are only intermediates, which are mostly cycled within the anoxic habitat. A significant percentage of the produced methane is oxidized by methanotrophic bacteria at anoxic-oxic interfaces such as the soil surface and the root surface of aquatic plants that serve as conduits for O2 transport into and CH4 transport out of the wetland soils. The dominant production processes in upland soils are different from those in wetland soils and include H2 production by biological N2 fixation, CO production by chemical decomposition of soil organic matter, and NO and N2O production by nitrification and denitrification. The processes responsible for CH4 production in upland soils are completely unclear, as are the OCS production processes in general. A problem for future research is the attribution of trace gas metabolic processes not only to functional groups of microorganisms but also to particular taxa. Thus, it is completely unclear how important microbial diversity is for the control of trace gas flux at the ecosystem level. However, different microbial communities may be part of the reason for differences in trace gas metabolism, e.g., effects of nitrogen fertilizers on CH4 uptake by soil; decrease of CH4 production with decreasing temperature; or different rates and modes of NO and N2O production in different soils and under different conditions.
Topics: Animal Population Groups; Animals; Atmosphere; Bacteria; Carbon Monoxide; Enzymes; Hydrogen; Methane; Models, Biological; Nitric Oxide; Nitrous Oxide; Oxidation-Reduction; Plant Physiological Phenomena; Soil Microbiology; Sulfur Oxides
PubMed: 8987358
DOI: 10.1128/mr.60.4.609-640.1996 -
The Journal of Hospital Infection Sep 2019Biofilms that develop on dry surfaces in the healthcare environment have increased tolerance to disinfectants. This study compared the activity of formulated oxidizing...
BACKGROUND
Biofilms that develop on dry surfaces in the healthcare environment have increased tolerance to disinfectants. This study compared the activity of formulated oxidizing disinfectants with products containing active ingredients against Staphylococcus aureus dry-surface biofilm (DSB) alone.
METHODS
DSB was grown in the CDC bioreactor with alternating cycles of hydration and dehydration. Disinfectant efficacy was tested before and after treatment with neutral detergent for 30 s, and in the presence or absence of standardized soil. Biofilms were treated for 5 min with peracetic acid (Surfex and Proxitane), hydrogen peroxide (Oxivir and 6% HO solution) and chlorine (Chlorclean and sodium dichloroisocyanurate tablets). Residual biofilm viability and mass were determined by plate culture and protein assay, respectively.
FINDINGS
Biofilm viability was reduced by 2.8 log for the chlorine-based products and by 2 log for Proxitane, but these products failed to kill any biofilm in the presence of soil. In contrast, Surfex completely inactivated biofilm (6.3 log reduction in titre) in the presence of soil. HO products had little effect against DSB. Biofilm mass removed in the presence and absence of soil was <30% by chlorine and approximately 65% by Surfex. Detergent treatment prior to disinfection had no effect.
CONCLUSION
The additives in fully formulated disinfectants can act synergistically with active ingredients, and thus increase biofilm killing whilst decreasing the adverse effect of soil. It is suggested that purchasing officers should seek efficacy testing results, and consider whether efficacy testing has been conducted in the presence of biological soil and/or biofilm.
Topics: Biofilms; Chlorine; Disinfectants; Drug Synergism; Environmental Microbiology; Hydrogen Peroxide; Microbial Viability; Organic Chemicals; Oxidants; Peracetic Acid; Soil; Staphylococcus aureus
PubMed: 30391488
DOI: 10.1016/j.jhin.2018.10.019 -
Langmuir : the ACS Journal of Surfaces... Jan 2023[FeS] or [4S-4Fe] clusters are responsible for storing and transferring electrons in key cellular processes and interact with their microenvironment to modulate their...
[FeS] or [4S-4Fe] clusters are responsible for storing and transferring electrons in key cellular processes and interact with their microenvironment to modulate their oxidation and magnetic states. Therefore, these clusters are ideal for the metal node of chemically and electromagnetically tunable metal-organic frameworks (MOFs). To examine the adsorption-based applications of [FeS]-based MOFs, we used density functional theory calculations and studied the adsorption of CO, CH, HO, H, N, NO, O, and SO onto [FeS], [FeS], and two 1D MOF models with the carboxylate and 1,4-benzenedithiolate organic linkers. Our reaction kinetics and thermodynamics results indicated that MOF formation promotes the oxidative and hydrolytic stability of the [FeS] clusters but decreases their adsorption efficiency. Our study suggests the potential industrial applications of these [FeS]-based MOFs because of their limited capacity to adsorb CO, CH, HO, H, N, O, and SO and high selectivity for NO adsorption.
Topics: Adsorption; Carbon Dioxide; Metal-Organic Frameworks; Nitrogen Dioxide; Carboxylic Acids
PubMed: 36579674
DOI: 10.1021/acs.langmuir.2c02609 -
Proceedings of the National Academy of... Nov 2016Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models...
Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO by NO is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH neutralization or under cloud conditions. Under polluted environments, this SO oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH and NO control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world.
Topics: Aerosols; Air Pollutants; Air Pollution; China; Climate; Environmental Monitoring; Humans; London; Nitrates; Nitrogen Dioxide; Nitrogen Oxides; Particle Size; Particulate Matter; Sulfates; Sulfur Oxides; Weather
PubMed: 27849598
DOI: 10.1073/pnas.1616540113 -
International Journal of Molecular... May 2022Aurivillius oxides ferroelectric layered materials are formed by bismuth oxide and pseu-do-perovskite layers. They have a good ionic conductivity, which is beneficial...
Aurivillius oxides ferroelectric layered materials are formed by bismuth oxide and pseu-do-perovskite layers. They have a good ionic conductivity, which is beneficial for various photo-catalyzed reactions. Here, we synthesized ultra-thin nanosheets of two different Aurivillius oxides, BiWO (BWO) and BiMoO (BMO), by using a hard-template process. All materials were characterized through XRD, TEM, FTIR, TGA/DSC, DLS/ELS, DRS, UV-Vis. Band gap material (E) and potential of the valence band (E) were calculated for BWO and BMO. In contrast to previous reports on the use of multi composite materials, a new procedure for photocatalytic efficient BMO nanosheets was developed. The procedure, with an additional step only, avoids the use of composite materials, improves crystal structure, and strongly reduces impurities. BWO and BMO were used as photocatalysts for the degradation of the water pollutant dye malachite green (MG). MG removal kinetics was fitted with Langmuir-Hinshelwood model obtaining a kinetic constant k = 7.81 × 10 min for BWO and k = 9.27 × 10 min for BMO. Photocatalytic dye degradation was highly effective, reaching 89% and 91% MG removal for BWO and BMO, respectively. A control experiment, carried out in the absence of light, allowed to quantify the contribution of adsorption to MG removal process. Adsorption contributed to MG removal by a 51% for BWO and only by a 19% for BMO, suggesting a different degradation mechanism for the two photocatalysts. The advanced MG degradation process due to BMO is likely caused by the high crystallinity of the material synthetized with the new procedure. Reuse tests demonstrated that both photocatalysts are highly active and stable reaching a MG removal up to 95% at the 10th reaction cycle. These results demonstrate that BMO nanosheets, synthesized with an easy additional step, achieved the best degradation performance, and can be successfully used for environmental remediation applications.
Topics: Catalysis; Oxidation-Reduction; Oxides; Rosaniline Dyes
PubMed: 35628232
DOI: 10.3390/ijms23105422 -
Environmental Science & Technology Apr 2024The objective of this study was to determine if U sediment concentrations in a U-contaminated wetland located within the Savannah River Site, South Carolina, were...
The objective of this study was to determine if U sediment concentrations in a U-contaminated wetland located within the Savannah River Site, South Carolina, were greater in the rhizosphere than in the nonrhizosphere. U concentrations were as much as 1100% greater in the rhizosphere than in the nonrhizosphere fractions; however and importantly, not all paired samples followed this trend. Iron (but not C, N, or S) concentrations were significantly enriched in the rhizosphere. XAS analyses showed that in both sediment fractions, U existed as UO coordinated with iron(III)-oxides and organic matter. A key difference between the two sediment fractions was that a larger proportion of U was adsorbed to Fe(III)-oxides, not organic matter, in the rhizosphere, where significantly greater total Fe concentrations and greater proportions of ferrihydrite and goethite existed. Based on 16S rRNA analyses, most bacterial sequences in both paired samples were heterotrophs, and population differences were consistent with the generally more oxidizing conditions in the rhizosphere. Finally, U was very strongly bound to the whole (unfractionated) sediments, with an average desorption value (U/U) of 3972 ± 1370 (mg-U/kg)/(mg-U/L). Together, these results indicate that the rhizosphere can greatly enrich U especially in wetland areas, where roots promote the formation of reactive Fe(III)-oxides.
Topics: Ferric Compounds; Wetlands; Rhizosphere; Uranium; RNA, Ribosomal, 16S; Iron; Oxides; Oxidation-Reduction; Geologic Sediments
PubMed: 38547454
DOI: 10.1021/acs.est.3c10481 -
Chemosphere Dec 2022Adsorption of natural organic matter (NOM) to mineral surfaces is an important process determining the environmental fate and biogeochemical cycling of many elements....
Adsorption of natural organic matter (NOM) to mineral surfaces is an important process determining the environmental fate and biogeochemical cycling of many elements. Natural organic matter consists of a heterogeneous mixture of soft and flexible organic molecules. Upon adsorption, size fractionation may occur, as well as changes in molecular conformation. Although very important, these phenomena have been omitted in existing adsorption models. Filling this gap, a novel framework for NOM adsorption to metal (hydr)oxides is presented. Humic acid (HA) was used as an analog for studying experimentally the NOM adsorption to goethite and its size fractionation as a function of pH, ionic strength, and surface loading. Size fractionation was evaluated for adsorption isotherms collected at pH 4 and 6, showing HA molecules of low molar mass were preferentially adsorbed. This phenomenon was incorporated into the new model. Consistent description of the HA adsorption data over the entire range of pH (3-11), ionic strength (2-100 mM), and surface loading (0.1-3 mg m) indicated that the spatial distribution of HA molecules adsorbed in the interface is a trade-off between maximizing the interaction of the HA ligands with the oxide surface and minimizing the electrostatic repulsion between HA particles as a result of interfacial crowding. Our advanced consistent framework is able to quantify changes in molar mass and molecular conformation, thereby significantly contributing to an improved understanding of the competitive power of HA for interacting on oxides with other adsorbed small organic acids as well as environmentally important oxyanions, such as phosphate, arsenate, and others.
Topics: Adsorption; Arsenates; Humic Substances; Metals; Minerals; Organic Chemicals; Oxides; Phosphates
PubMed: 35995195
DOI: 10.1016/j.chemosphere.2022.136129 -
Yakugaku Zasshi : Journal of the... Apr 2011In this review, we show that intermolecular hypervalent I(III)…O interactions play an essential role in the complexation of organo-λ(3)-iodanes with crown ethers. In... (Review)
Review
In this review, we show that intermolecular hypervalent I(III)…O interactions play an essential role in the complexation of organo-λ(3)-iodanes with crown ethers. In addition to the well-known driving force for the complexation of crown ethers, ion-dipole interaction, and hydrogen bonding interaction, our result provides a new class of interaction in supramolecular chemistry of crown ethers. Both solid state structure analysis and solution chemistry indicate that diaryl-, 1-alkenyl(phenyl)-, 1-alkynyl(phenyl)-, and hydroxy(phenyl)-λ(3)-iodanes form stable complexes with 18-crown-6 through hypervalent I(III)…O interactions. The complexation not only increases the stability of these hypervalent λ(3)-iodanes but also holds its high reactivity toward nucleophiles. The complex of hydroxy(phenyl)-λ(3)-iodanes with 18-crown-6 serve as versatile oxidizing agents, especially in water.
Topics: Crown Ethers; Drug Stability; Hydrogen Bonding; Macromolecular Substances; Oxidants; Water
PubMed: 21467794
DOI: 10.1248/yakushi.131.545 -
Nature Communications May 2022Removal of organic micropollutants from water through advanced oxidation processes (AOPs) is hampered by the excessive input of energy and/or chemicals as well as the...
Removal of organic micropollutants from water through advanced oxidation processes (AOPs) is hampered by the excessive input of energy and/or chemicals as well as the large amounts of residuals resulting from incomplete mineralization. Herein, we report a new water purification paradigm, the direct oxidative transfer process (DOTP), which enables complete, highly efficient decontamination at very low dosage of oxidants. DOTP differs fundamentally from AOPs and adsorption in its pollutant removal behavior and mechanisms. In DOTP, the nanocatalyst can interact with persulfate to activate the pollutants by lowering their reductive potential energy, which triggers a non-decomposing oxidative transfer of pollutants from the bulk solution to the nanocatalyst surface. By leveraging the activation, stabilization, and accumulation functions of the heterogeneous catalyst, the DOTP can occur spontaneously on the nanocatalyst surface to enable complete removal of pollutants. The process is found to occur for diverse pollutants, oxidants, and nanocatalysts, including various low-cost catalysts. Significantly, DOTP requires no external energy input, has low oxidant consumption, produces no residual byproducts, and performs robustly in real environmental matrices. These favorable features render DOTP an extremely promising nanotechnology platform for water purification.
Topics: Decontamination; Environmental Pollutants; Oxidants; Water; Water Pollutants, Chemical
PubMed: 35637224
DOI: 10.1038/s41467-022-30560-9