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1.
J Environ Manage ; 261: 110265, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32148322

RESUMO

For the first time, the operational feasibility of the solar photo-Fenton process at neutral pH in continuous flow has been tested for three consecutive days. The aim of the treatment was to remove of contaminants of emerging concern (CECs) from wastewater treatment plant secondary effluents. To this end, a 5 cm-deep raceway pond reactor was run in continuous flow mode and the degradation of the CECs present in real secondary effluents was monitored at their natural concentrations. To keep dissolved iron at neutral pH, ethylenediamine-N,N'-disuccinic acid (EDDS) was used to form the complex Fe(III):EDDS as an iron source for the photo-Fenton reactions. At pilot scale the effects of the Fe(III):EDDS molar ratio (1:1 and 1:2) and hydraulic residence time (HRT) (20 and 40 min) on CEC removal were studied. The best operating condition was 20 min of HRT, giving rise to a treatment capacity of 900 L m-2 d-1 with CEC removal percentages of around 60%. The reactant concentrations were 0.1 mM Fe(III):EDDS at a 1:1 M ratio and 0.88 mM H2O2. Under these operating conditions, the short-term stability of the process was also demonstrated, thus pointing out the potential of this solar technology as a tertiary treatment.


Assuntos
Peróxido de Hidrogênio , Poluentes Químicos da Água , Compostos Férricos , Concentração de Íons de Hidrogênio , Oxirredução , Luz Solar , Águas Residuárias
2.
Water Res ; 174: 115629, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32113013

RESUMO

A novel technique for phosphorus recovery from the liquid phase of anaerobic digestate was developed using biochar derived from iron-rich sludge (dewatered sludge conditioned with Fenton's reagent). The biochar pyrolyzed from iron-rich sludge at a low temperature of 300 °C (referred to as Fe-300 biochar) showed a better phosphorus (P) adsorption capacity (most of orthophosphate and pyrophosphate) than biochars pyrolyzed at other higher temperatures of 500-900 °C, with the maximum P adsorption capacity of up to 1.843 mg g-1 for the liquid phase of anaerobic digestate. Adsorption isotherms study indicated that 70% P was precipitated through chemical reaction with Fe elements, i.e., Fe(II) and Fe(III) existed on the surface of the Fe-300 biochar, and other 30% was through surface physical adsorption as simulated by a dual Langmuir-Langmuir model using the potassium dihydrogen orthophosphate (KH2PO4) as a model solution. The seed germination rate was increased up to 92% with the addition of Fe-300 biochar after adsorbing most of P, compared with 66% without the addition of biochar. Moreover, P adsorbed by the chemical reaction in form of iron hydrogen phosphate can be solubilized by a phosphate-solubilizing microorganism of Pseudomonas aeruginosa, with the total solubilized P amount of 3.045 mg g-1 at the end of an incubation of 20 days. This study indicated that the iron-rich sludge-derived biochar could be used as a novel and beneficial functional material for P recovery from the liquid phase of anaerobic digestate. The recovered P with biochar can be re-utilized in garden soil as an efficient P-fertilizer, thus increasing the added values of both the liquid phase of anaerobic digestate and the iron-rich sludge.


Assuntos
Fósforo , Esgotos , Adsorção , Anaerobiose , Carvão Vegetal , Compostos Férricos , Fertilizantes , Ferro
3.
Water Res ; 174: 115631, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32114017

RESUMO

Low-molecular-weight thiols (LMWTs) are widely occurring in waters and soils, which can act as electron shuttles in biogeochemical cycles. It is interesting to study the interactions between LMWTs and clay minerals, which would produce free radicals on clay surfaces and influence As(III) transformation. Batch experiments and spectroscopic analysis in combined with computational modeling were conducted with three Fe-bearing clay minerals (Na-NAu-1, Na-NAu-2 and Na-SAz-2) and four LMWTs (l-cysteine, cysteamine, homocysteine, and glutathione) to investigate the reaction mechanisms of LMWTs with Fe-bearing clay minerals and influences of clay types and LMWT structures on the interactions. The results showed that Fe-bearing clay minerals can improve 2.4-3.7 times of •OH formation in 96-h LMWTs oxidation. Quenching experiments confirmed surface-Fenton-like reactions were the main pathways of •OH formation in the presence of Fe-bearing smectite clay minerals. The most possible hypothesis is that structural Fe (III) can accept electrons from LMWTs through proton-coupled transfer from -SH functional group, which was supported by FTIR, XRD and Mössbauer spectroscopies. The results of DFT calculations suggested that clay surfaces could accelerate RS• formation and stabilize the radicals. The addition of Na-NAu-2 in the cystein solution could increase As(III) oxidation to As(V) from 16.3% to 42.0%. The results imply that in-situ •OH formation in the presence of LMWTs and smectite clays may be an important geochemical process for the transformation of environmental contaminants.


Assuntos
Argila , Compostos de Sulfidrila , Silicatos de Alumínio , Compostos Férricos , Oxirredução , Silicatos
4.
Monaldi Arch Chest Dis ; 90(1)2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32124586

RESUMO

Iron deficiency (ID) is recognized as an important comorbidity in patients undergoing cardiac surgery; however, it still remains under-diagnosed and under-treated in clinical practice. This study aims at comparing efficacy and the effects on exercise capacity of intravenous ferric carboxymaltose (FCM) versus ferric gluconate (FG) in patients with ID anemia (IDA) resulting from cardiac surgery. We retrospectively analyzed data from our records of in-hospital patients with IDA after cardiac surgery undergoing cardiac rehabilitation. Group I was treated with FG, group II with FCM. Efficacy measures included changes (baseline vs discharge) in hemoglobin (Hb) and in distance traveled at six-minutes walking test (6MWT). Data from 74 in-patients (mean age 67.5±10.4 years, 43% women) were analyzed. At discharge, patients treated with FCM showed higher levels of Hb (11.1±1.2g/dl vs 10.2±1.1 g/dl; p=0.001), greater distance traveled at 6MWT (279.2±108.8 meters vs 236.3±72.7 meters; p=0.048), and lower in-hospital rehabilitation length of stay (20.3±7 vs 25.3±11.7 days; p=0.043) as compared to FG group. At multivariate analysis, the most powerful predictors of Hb increase >1 g/dl at discharge were transferrin levels (p=0.019) and treatment with FCM (p<0.001). FCM replacement therapy and iron serum levels were the most powerful predictors of 6MWT distance improvement (>100 meters) at discharge (p=0.13 and p=0.003, respectively). In patients with IDA following cardiac surgery, intravenous FCM is effective in restoring Hb levels and in improving exercise capacity after cardiac surgery.


Assuntos
Anemia Ferropriva/tratamento farmacológico , Procedimentos Cirúrgicos Cardíacos/efeitos adversos , Tolerância ao Exercício , Compostos Férricos/uso terapêutico , Hematínicos/uso terapêutico , Maltose/análogos & derivados , Idoso , Anemia Ferropriva/etiologia , Feminino , Humanos , Infusões Intravenosas , Masculino , Maltose/uso terapêutico , Pessoa de Meia-Idade , Estudos Retrospectivos , Resultado do Tratamento
5.
Chemosphere ; 244: 125517, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050332

RESUMO

The speciation and mobility of As are controlled by both Fe and Mn (oxyhydr)oxides through a series of surface complexation and redox reactions occurring in the environment, which is also complicated by the solution chemistry conditions. However, there is still a lack of quantitative tools for predicting the coupled kinetic processes of As reactions with Fe and Mn (oxyhydr)oxides. In this study, we developed a quantitative model for the coupled kinetics of As adsorption/desorption and oxidation in ferrihydrite-Mn (oxyhydr)oxides and ferrihydrite-Mn(II)-O2 systems. This model also accounted for the variations in solution chemistry conditions and binding site heterogeneity. Our model suggested that Mn (oxyhydr)oxide and ferrihydrite mainly served as an oxidant and an adsorbent, respectively, when they coexisted. Among the three types of binding sites of ferrihydrite, the adsorbed As(V) was mainly distributed on the nonprotonated bidentate sites. Our model quantitatively showed that the oxidation rates of different reaction systems varied significantly. The rates of As(III) oxidation were enhanced with higher pH values and higher molar ratios of Mn(II)/As(III) in the ferrihydrite-Mn(II)-O2 system. This study provides a modeling framework for predicting the kinetic behavior of As when multiple adsorption/desorption and oxidation reactions are coupled in the environment.


Assuntos
Arsênico/química , Manganês/química , Adsorção , Compostos Férricos , Cinética , Modelos Químicos , Oxirredução , Óxidos/química
6.
Chemosphere ; 244: 125568, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050347

RESUMO

Persulfate (PS) is widely used for environmental remediation, but its organic contaminant removal performance strongly depends on its activation. In this study, we demonstrate that pyrite (FeS2) can more effectively activate PS than the commonly used FeSO4 for atrazine degradation. When 3.0 mM of PS and 4.2 mM of iron salts were used, the atrazine degradation efficiency of FeS2/PS was 1.4 times that of FeSO4/PS, while the amount of consumed PS in case of FeS2 was only 53% of that by FeSO4. The better PS activation performance of FeS2 could be attributed to its slow and sustainable release of dissolved Fe(II), inhibiting the quenching reaction between •SO4-/•OH and Fe(II) ions, and thus producing more reactive oxygen species for the atrazine degradation. More importantly, the surface bound Fe(II) of FeS2 could activate molecular oxygen to generate superoxide radical (•O2-), which could further promote the effective decomposition of PS by accelerating the Fe(III)/Fe(II) redox cycle. This study unravels the roles of dissolved Fe(II) and surface bound Fe(II) on the persulfate activation, and provides a promising heterogeneous persulfate activator for pollutant control and environmental remediation.


Assuntos
Atrazina/química , Ferro/química , Sulfetos/química , Poluentes Químicos da Água/química , Compostos Benzidrílicos , Compostos Férricos , Oxirredução , Sulfatos , Poluentes Químicos da Água/análise
7.
Life Sci ; 245: 117361, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32001268

RESUMO

AIMS: Evaluation of the anti-diabetic effect of superparamagnetic iron oxide nanoparticles (SPIONs) on Type 2 diabetic rats and compared their effect to metformin treatment. MAIN METHODS: Diabetic rats were treated with different doses of nanoparticles one time per week for 4 weeks. Fasting blood glucose level was determined for studied groups during the experimental period (30 days). At the end of the experiment, oral glucose tolerance test was carried out, serum samples were collected for biochemical assays. Then animals were sacrificed to obtain tissues for assessment of glucose transporters, insulin receptors and insulin signaling proteins. KEY FINDING: SPIONs treatment normalized fasting blood glucose and lowering insulin level in diabetic rats compared to untreated diabetic rats. SPIONs significantly ameliorate the glucose sensing and the active components of insulin signaling pathway. The anti-diabetic effects of SPIONs may be mediated through its effect on (i) hepatic peroxisome proliferator-activated receptor gamma coactivator 1-alpha content, which induced by SPIONs treatment in a dose-dependent manner, (ii) adipocytokines as SPIONs treated diabetic rats showed significantly higher levels of adiponectin and lower retinol binding protein 4 compared to untreated diabetic rats, (iii) lipid profile as SPIONs treatment significantly corrected the lipid profile in a dose-dependent manner and to a similar extent as metformin or even better. SIGNIFICANCE: To our knowledge, this is the first study that explores the anti-diabetic effects of SPIONs on diabetic model.


Assuntos
Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Tipo 2/tratamento farmacológico , Compostos Férricos/uso terapêutico , Glucose/metabolismo , Hipoglicemiantes/uso terapêutico , Insulina/sangue , Nanopartículas de Magnetita/uso terapêutico , Animais , Glicemia/análise , Teste de Tolerância a Glucose , Masculino , Metformina/uso terapêutico , Ratos , Ratos Sprague-Dawley
8.
Chem Commun (Camb) ; 56(20): 3089-3092, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32052805

RESUMO

Reaction of FeIII(O2˙-)(TPP) with 2,3-dimethylindole at -40 °C gives the ring-opened, dioxygenated N-(2-acetyl-phenyl)-acetamide product. The reaction was monitored in situ by low-temperature UV-vis and 1H NMR spectroscopies. This work demonstrates that a discrete iron(iii)(superoxo) porphyrin is competent to carry out indole oxidation, as proposed for the tryptophan and indoleamine 2,3-dioxygenases.


Assuntos
Compostos Férricos/química , Indolamina-Pirrol 2,3,-Dioxigenase/química , Indóis/química , Metaloporfirinas/química , Superóxidos/química , Triptofano Oxigenase/química , Compostos Férricos/metabolismo , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Indóis/metabolismo , Metaloporfirinas/metabolismo , Estrutura Molecular , Oxirredução , Superóxidos/metabolismo , Triptofano Oxigenase/metabolismo
9.
Water Res ; 174: 115626, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32101786

RESUMO

In this work, Fe(II) catalyzing sodium percarbonate (Fe(II)/SPC) was managed to facilitate waste activated sludge (WAS) dewatering for the first time. The results showed that after WAS was treated by 20 mg/g total suspended solids (TSS) Fe(II) and 50 mg/g TSS SPC, the water content of sludge cake (WCSC) by press filtration and capillary suction time (CST) dropped from 90.8% ± 1.6% and 96.1 ± 4.0 s (the control) to 55.6% ± 1.4% and 30.1 ± 2.5 s, respectively. The mechanism investigations indicated that four intermediates or products (i.e., •OH, H2O2, Fe(II), and Fe(III)) generated in the Fe(II)/SPC process were responsible for the improved WAS dewaterability, and •OH and Fe(III) were the two major contributors. It was found that •OH collapsed and fragmented extracellular polymeric substances, damaged cell wall and permeabilized cytoplasmic membrane, and transformed conformation of the extracellular proteins secondary structure via both affecting the hydrogen bond maintaining α-helix and cracking disulfide bond in cysteine residues while Fe(III), the oxidization product of Fe(II), decreased the surface electronegativity and water-affinity surface areas of WAS flocs. As a result, the bound water release, flocculability, surface hydrophobicity, drain capability, and flowability of WAS flocs were strengthened whereas the compact surface structure, colloidal forces, network strength, gel-like structure, and apparent viscosity of WAS flocs were weakened. In addition, Fe(II)/SPC process also reduced the recalcitrant organics and fecal coliforms in sludge, which facilitated land application of dewatered sludge. The findings acquired in this work not only deepens our understanding of Fe(II)/SPC-involved WAS treatment process but also may guide engineers to develop both effective and promising strategies to better condition WAS for dewatering in the future.


Assuntos
Esgotos , Eliminação de Resíduos Líquidos , Carbonatos , Compostos Férricos , Compostos Ferrosos , Peróxido de Hidrogênio , Água
10.
Water Res ; 172: 115528, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32004914

RESUMO

The study demonstrated a novel anammox-like process to remove high-concentration ammonium using nitrate as terminal electron acceptor under Fe(III)/Fe(II) cycle. Compared with NO2- in common anammox, NO3- used here is more available in practice, suitable for in-situ removal of high-concentration NH4+ in a single anaerobic system. The NOx- and Fe(II) produced from Feammox [Fe(III) reduction coupled to anaerobic ammonium oxidation] subsequently react together via NOx--dependent Fe(II) oxidation to regenerate Fe(III) that potentially stimulates next round of Feammox. However, these processes couldn't be lasting due to inadequate Fe(III) regeneration because NOx- is non-dominant product during Feammox. In this study NO3- was added to supplement the insufficient NOx- to enhance Fe(III) regeneration and remove nitrogen successively. Results showed that periodically adding nitrate caused oscillations between Fe(III) and Fe(II) in the sludge, implying Fe(III) regeneration and consumption. Consequently, nitrogen removal of the digester with an initial total nitrogen of 1036.7 mg/L reached 90.1% after 98-day operation, much higher than that of control (41.6%) without NO3- addition. Adding NO3- in the digester to trigger Fe(III)/Fe(II) cycle for removing ammonium is just equivalent to an anammox-like process using NO3- as terminal electron acceptor to oxidize NH4+.


Assuntos
Compostos de Amônio , Anaerobiose , Reatores Biológicos , Elétrons , Compostos Férricos , Compostos Ferrosos , Nitratos , Nitrogênio , Oxirredução
11.
J Environ Manage ; 255: 109926, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32063307

RESUMO

Treatment of polluted wastewaters from industrial activities has become a source of major concern for the environment. In this work, real wastewater from a physico-chemical (WWFQ) treatment was tested through different oxidation technologies: Fenton and Fenton-like reagent and persulfate activated by NaOH and Fe(II). Oxidation reactions with Fenton's reagent were carried out in a 0.25 L batch reactor at 25 °C by adding either Fe(II) or Fe(III) and H2O2 to an aqueous solution of wastewater, whose pH was previously adjusted to 2 or 3. Iron concentration ranging from 25 to 100 mg/L and peroxide concentration from 2500 to 10000 mg/L were used. The total organic carbon slightly decreased when WWFQ was treated. Moreover, better results were obtained when Fe(II) was used than Fe(III). Both iron concentration and oxidant dosage had a positive influence on the chemical oxygen demand (COD) removal, until an asymptotic value of 30% was obtained. Oxidation of pollutants contained in WWFQ was studied with persulfate (18.4-294 mM) activated with NaOH and Fe(II) (36.8-588 mM). Again, a positive influence of both persulfate and NaOH was observed, although a similar asymptotic COD value was observed. This parallelism between both technologies confirms recalcitrant compounds were obtained.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Compostos Férricos , Compostos Ferrosos , Peróxido de Hidrogênio , Oxirredução , Hidróxido de Sódio , Eliminação de Resíduos Líquidos
12.
JAMA ; 323(5): 432-443, 2020 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-32016310

RESUMO

Importance: Intravenous iron enables rapid correction of iron-deficiency anemia, but certain formulations induce fibroblast growth factor 23-mediated hypophosphatemia. Objective: To compare risks of hypophosphatemia and effects on biomarkers of mineral and bone homeostasis of intravenous iron isomaltoside (now known as ferric derisomaltose) vs ferric carboxymaltose. Design, Setting, and Participants: Between October 2017 and June 2018, 245 patients aged 18 years and older with iron-deficiency anemia (hemoglobin level ≤11 g/dL; serum ferritin level ≤100 ng/mL) and intolerance or unresponsiveness to 1 month or more of oral iron were recruited from 30 outpatient clinic sites in the United States into 2 identically designed, open-label, randomized clinical trials. Patients with reduced kidney function were excluded. Serum phosphate and 12 additional biomarkers of mineral and bone homeostasis were measured on days 0, 1, 7, 8, 14, 21, and 35. The date of final follow-up was June 19, 2018, for trial A and May 29, 2018, for trial B. Interventions: Intravenous administration of iron isomaltoside, 1000 mg, on day 0 or ferric carboxymaltose, 750 mg, infused on days 0 and 7. Main Outcomes and Measures: The primary end point was the incidence of hypophosphatemia (serum phosphate level <2.0 mg/dL) between baseline and day 35. Results: In trial A, 123 patients were randomized (mean [SD] age, 45.1 [11.0] years; 95.9% women), including 62 to iron isomaltoside and 61 to ferric carboxymaltose; 95.1% completed the trial. In trial B, 122 patients were randomized (mean [SD] age, 42.6 [12.2] years; 94.1% women), including 61 to iron isomaltoside and 61 to ferric carboxymaltose; 93.4% completed the trial. The incidence of hypophosphatemia was significantly lower following iron isomaltoside vs ferric carboxymaltose (trial A: 7.9% vs 75.0% [adjusted rate difference, -67.0% {95% CI, -77.4% to -51.5%}], P < .001; trial B: 8.1% vs 73.7% [adjusted rate difference, -65.8% {95% CI, -76.6% to -49.8%}], P < .001). Beyond hypophosphatemia and increased parathyroid hormone, the most common adverse drug reactions (No./total No.) were nausea (iron isomaltoside: 1/125; ferric carboxymaltose: 8/117) and headache (iron isomaltoside: 4/125; ferric carboxymaltose: 5/117). Conclusions and Relevance: In 2 randomized trials of patients with iron-deficiency anemia who were intolerant of or unresponsive to oral iron, iron isomaltoside (now called ferric derisomaltose), compared with ferric carboxymaltose, resulted in lower incidence of hypophosphatemia over 35 days. However, further research is needed to determine the clinical importance of this difference. Trial Registration: ClinicalTrials.gov Identifiers: NCT03238911 and NCT03237065.


Assuntos
Anemia Ferropriva/tratamento farmacológico , Dissacarídeos/efeitos adversos , Compostos Férricos/efeitos adversos , Hematínicos/efeitos adversos , Hipofosfatemia/induzido quimicamente , Maltose/análogos & derivados , Adulto , Anemia Ferropriva/complicações , Biomarcadores/sangue , Biomarcadores/urina , Dissacarídeos/uso terapêutico , Feminino , Compostos Férricos/uso terapêutico , Cefaleia/induzido quimicamente , Hematínicos/uso terapêutico , Humanos , Hipofosfatemia/epidemiologia , Incidência , Masculino , Maltose/efeitos adversos , Maltose/uso terapêutico , Pessoa de Meia-Idade , Náusea/induzido quimicamente , Fosfatos/sangue , Fosfatos/urina
13.
Environ Sci Technol ; 54(6): 3209-3218, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32064861

RESUMO

Iron (Fe) biogeochemistry in marine sediments is driven by redox transformations creating Fe(II) and Fe(III) gradients. As sediments are physically mixed by wave action or bioturbation, Fe gradients re-establish regularly. In order to identify the response of dissolved Fe(II) (Fe2+) and Fe mineral phases toward mixing processes, we performed voltammetric microsensor measurements, sequential Fe extractions, and Mössbauer spectroscopy of 12 h light-dark cycle incubated marine coastal sediment. Fe2+ decreased during 7 days of undisturbed incubation from approximately 400 to 60 µM. In the first 2-4 days of incubation, Fe2+ accumulated up to 100 µM in the top 2 mm due to Fe(III) photoreduction. After physical perturbation at day 7, Fe2+ was re-mobilized reaching concentrations of 320 µM in 30 mm depth, which decreased to below detection limit within 2 days afterward. Mössbauer spectroscopy showed that the relative abundance of metastable iron-sulfur mineral phases (FeSx) increased during initial incubation and decreased together with pyrite (FeS2) after perturbation. We show that Fe2+ mobilization in marine sediments is stimulated by chemical changes caused by physical disturbances impacting the Fe redox distribution. Our study suggests that, in addition to microbial and abiotic Fe(III) reduction, including Fe(III) photoreduction, physical mixing processes induce chemical changes providing sediments and the inhabiting microbial community with Fe2+.


Assuntos
Compostos Férricos , Sedimentos Geológicos , Compostos Ferrosos , Oxirredução , Enxofre
14.
Environ Sci Technol ; 54(6): 3297-3305, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32078305

RESUMO

"Green rust" (GR), a redox-active Fe(II)-Fe(III) layered double hydroxide, is a potential environmentally relevant mineral substrate for arsenic (As) sequestration in reduced, subsurface environments. GR phases have high As uptake capacities at circum-neutral pH conditions, but the exact interaction mechanism between the GR phases and As species is still poorly understood. Here, we documented the bonding and interaction mechanisms between GR sulfate and As species [As(III) and As(V)] under anoxic and circum-neutral pH conditions through scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray (EDX) spectroscopy and combined it with synchrotron-based X-ray total scattering, pair distribution function (PDF) analysis, and As K-edge X-ray absorption spectroscopy (XAS). Our highly spatially resolved STEM-EDX data revealed that the preferred adsorption sites of both As(III) and As(V) are at GR crystal edges. Combining this data with differential PDF and XAS allowed us to conclude that As adsorption occurs primarily as bidentate binuclear (2C) inner-sphere surface complexes. In the As(III)-reacted GR sulfate, no secondary Fe-As phases were observed. However, authigenic parasymplesite (ferrous arsenate nanophase), exhibiting a threadlike morphology, formed in the As(V)-reacted GR sulfate and acts as an additional immobilization pathway for As(V) (∼87% of immobilized As). We demonstrate that only by combining high-resolution STEM imaging and EDX mapping with the bulk (differential) PDF and extended X-ray absorption fine structure (EXAFS) data can one truly determine the de facto As binding nature on GR surfaces. More importantly, these new insights into As-GR interaction mechanisms highlight the impact of GR phases on As sequestration in anoxic subsurface environments.


Assuntos
Arsênico , Adsorção , Compostos Férricos , Sulfatos , Espectroscopia por Absorção de Raios X
15.
Environ Sci Technol ; 54(5): 2832-2842, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32019302

RESUMO

Underground repository in crystalline bedrock is a widely accepted solution for long-term disposal of spent nuclear fuels. During future deglaciations, meltwater will intrude via bedrock fractures to the depths of future repositories where O2 left in the meltwater could corrode metal canisters and enhance the migration of redox-sensitive radionuclides. Since glacial meltwater is poor in reduced phases, the quantity and (bio)accessibility of minerogenic Fe(II) in bedrock fractures determine to what extent O2 in future meltwater can be consumed. Here, we determined Fe valence and mineralogy in secondary mineral assemblages sampled throughout the upper kilometer of fractured crystalline bedrock at two sites on the Baltic Shield, using X-ray absorption and Mössbauer spectroscopic techniques that were found to deliver matching results. The data point to extensive O2-consuming capacity of the bedrock fractures, because Fe(II)-rich phyllosilicates were abundant and secondary pyrite was dispersed deep into the bedrock with no overall increase in Fe(II) concentrations and Fe(II)/Fe(III) proportions with depth. The results imply that repeated Pleistocene deglaciations did not cause a measurable decrease in the Fe(II) pool. In surficial fractures, largely opened during glacial unloading, ferrihydrite and illite have formed abundantly via oxidative transformation of Fe(II)-rich phyllosilicates and recently exposed primary biotite/hornblende.


Assuntos
Compostos Férricos , Geologia , Oxirredução , Espectroscopia de Mossbauer , Espectroscopia por Absorção de Raios X , Raios X
16.
Environ Sci Technol ; 54(5): 2951-2960, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32023050

RESUMO

Permafrost contains a large (1700 Pg C) terrestrial pool of organic matter (OM) that is susceptible to degradation as global temperatures increase. Of particular importance is syngenetic Yedoma permafrost containing high OM content. Reactive iron phases promote stabilizing interactions between OM and soil minerals and this stabilization may be of increasing importance in permafrost as the thawed surface region ("active layer") deepens. However, there is limited understanding of Fe and other soil mineral phase associations with OM carbon (C) moieties in permafrost soils. To elucidate the elemental associations involved in organomineral complexation within permafrost systems, soil cores spanning a Pleistocene permafrost chronosequence (19,000, 27,000, and 36,000 years old) were collected from an underground tunnel near Fairbanks, Alaska. Subsamples were analyzed via scanning transmission X-ray microscopy-near edge X-ray absorption fine structure spectroscopy at the nano- to microscale. Amino acid-rich moieties decreased in abundance across the chronosequence. Strong correlations between C and Fe with discrete Fe(III) or Fe(II) regions selectively associated with specific OM moieties were observed. Additionally, Ca coassociated with C through potential cation bridging mechanisms. Results indicate Fe(III), Fe(II), and mixed valence phases associated with OM throughout diverse permafrost environments, suggesting that organomineral complexation is crucial to predict C stability as permafrost systems warm.


Assuntos
Pergelissolo , Alaska , Carbono , Compostos Férricos , Solo
17.
Food Chem ; 312: 126069, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31901702

RESUMO

The effects of low frequency magnetic field (0-12 mT) on hydrogen peroxide oxidized myoglobin-isolate (MbI) were investigated. The results indicate that the primary target of the hydrogen peroxide oxidation was Met(FeIII)Mb, leading to the fall off of iron ions from the porphyrin ring. Additionally, the increased magnetic field (≥9 mT) enhanced the release of more iron ions to react with H2O2, giving rise to the production of more hydroxyl radicals and the shift of oxidation site from porphyrin ring to Mb skeleton. Moreover, the directional movement of iron ions induced by magnetic field caused the generation of local micro-electric field and the rearrangement of charged groups on the protein surface or near-surface, thus affecting Mb aggregation. Overall, the magnetic field interfered with the hydrogen peroxide chain reaction process, changed the redox equivalents of Mb, and shifted the oxidation sites of Mb.


Assuntos
Peróxido de Hidrogênio/química , Mioglobina/química , Compostos Férricos/química , Radical Hidroxila/química , Ferro/química , Campos Magnéticos , Oxirredução , Porfirinas/química
18.
Top Curr Chem (Cham) ; 378(1): 13, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31925680

RESUMO

The use of magnetic nanoparticles (MNPs), such as iron oxide nanoparticles (IONPs), in biomedicine is considered to be a valuable alternative to the more traditional materials due to their chemical stability, cost-effectiveness, surface functionalization, and the possibility to selectively attach and transport targeted species to the desired location under a magnetic field. One of the many main applications of MNPs is DNA separation, which enables genetic material manipulation; consequently, MNPs are used in numerous biotechnological methods, such as gene transfection and molecular recognition systems. In addition, the interaction between the surfaces of MNPs and DNA molecules and the magnetic nature of the resulting composite have facilitated the development of safe and effective gene delivery vectors to treat significant diseases, such as cancer and neurological disorders. Furthermore, the special recognition properties of nucleic acids based on the binding capacity of DNA and the magnetic behavior of the nanoparticles allowing magnetic separation and concentration of analytes have led to the development of biosensors and diagnostic assays; however, both of these applications face important challenges in terms of the improvement of selective nanocarriers and biosensing capacity. In this review, we discuss some aspects of the properties and surface functionalization of MNPs, the interactions between DNA and IONPs, the preparation of DNA nanoplatforms and their biotechnological applications, such as the magnetic separation of DNA, magnetofection, preparation of DNA vaccines, and molecular recognition tools.


Assuntos
DNA/química , Compostos Férricos/química , Nanopartículas de Magnetita/química , Nanomedicina , DNA/isolamento & purificação , Portadores de Fármacos/química , Humanos , Neoplasias/diagnóstico , Neoplasias/tratamento farmacológico , Neoplasias/imunologia , Vacinas de DNA/química , Vacinas de DNA/imunologia
19.
World J Microbiol Biotechnol ; 36(2): 25, 2020 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-31980951

RESUMO

In a search for novel therapeutic agents against pathogenic fungal species, Candida in addition to bacterial species, novel spinel nanoferrites were assayed against four pathogenic fungi isolated from different clinical samples of ear and skin infections: Aspergillus flavus, A. niger, A. terrus and A. fumigatus, four Candia species: Candida albicans, C. parapsilosis, C. krusei and C. tropicales, and four bacterial species: two Gram +ve: Bacillus subtilis and Streptococcus pyogenes, and two Gram -ve: Pseudomonas vulgaris and Escherichia coli. It was found that the assayed compounds displayed different levels of antifungal and antibacterial activities against all tested microorganisms. The antimicrobial potency depends on the method of synthesis of the nanoparticles and also on the microbial species.


Assuntos
Antibacterianos/síntese química , Antifúngicos/síntese química , Compostos Férricos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/química , Antifúngicos/farmacologia , Compostos Férricos/química , Compostos Férricos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Nanopartículas , Relação Estrutura-Atividade
20.
Chem Commun (Camb) ; 56(15): 2300-2303, 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-31989132

RESUMO

A novel signal self-enhancement photoelectrochemical immuno-sensor has been developed based on the curing of sacrificial agent SO32- coated-Au NPs sensitizing Ag2S/CuS/α-Fe2O3 n-p-n hetero-structure films for the first time. This strategy has acquired high sensitivity and low background without addition of a sacrificial agent in solution in the detection of prostate antigen.


Assuntos
Técnicas Biossensoriais , Cobre/química , Técnicas Eletroquímicas , Compostos Férricos/química , Imunoensaio , Antígeno Prostático Específico/análise , Compostos de Prata/química , Humanos , Tamanho da Partícula , Processos Fotoquímicos , Soluções , Propriedades de Superfície
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