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1.
J Photochem Photobiol B ; 202: 111734, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31837584

RESUMO

A simple and one-step microwave digestion method was utilized to synthesize the highly photoluminescent glucosamine derived nitrogen and zinc doped carbon dots (N, Zn-CDs) with a bluish-green luminescence property. The synthesized N, Zn-CDs inherited a good photoluminescence property with a quantum yield of 74% and which were characterized by XPS, XRD, TEM, FT-IR, UV-Vis, and fluorescence spectrometry. More importantly, N, Zn-CDs served as a fluorescence sensor for the detection of Fe3+ ions, under optimal conditions, a good linear relationship was established in the concentration range of 0.25-125 µM. Also, the experimental results showed the detection limit of N, Zn-CDs against Fe3+ was 0.15 µM, this could be a promising assay for sensing Fe3+ ions. Also, the role of zinc doping was explored by conducting the detection under similar experimental conditions in the absence of zinc, and reports revealed that the reason for high photoluminescence was due to the zinc doping. Along with the sensing application, our group had investigated the bactericidal property of synthesized N, Zn-CDs against gram-negative (Escherichia coli), and gram-positive pathogens (Staphylococcus aureus). N, Zn-CDs displayed good bactericidal activity against both pathogens under light conditions, but Escherichia coli, even under the dark condition proved its activity. Besides, the morphology of both the strains was displayed before and after the treatment via a scanning electron microscopic images. Also, a plausible mechanism for bactericidal activity was also explained. The reported synthesis method could provide a novel approach for the design of high photoluminescent N, Zn-CDs with good sensing and bactericidal property towards Fe3+ ions, gram-negative and positive bacterial strains.


Assuntos
Carbono/química , Compostos Férricos/análise , Nitrogênio/química , Pontos Quânticos/química , Espectrometria de Fluorescência , Zinco/química , Catálise , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Água Doce/análise , Íons/química , Luz , Limite de Detecção , Micro-Ondas , Pontos Quânticos/toxicidade , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
2.
Chemosphere ; 240: 124953, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574435

RESUMO

Chemical characterization of PM2.5 and PM10 is important to identify potential compounds that induce biological responses that translate into cardio-respiratory health problems. This study shows the reliability of the use of crystalline phases, identified in samples from receptor sites, as source markers, helping researchers to infer the main sources of air pollution, even without the use of receptor models. PM2.5 and PM10 samples were collected at two sites in an urban industrialized region located at southeast of Brazil and analyzed by Synchrotron X-ray Diffraction to identify crystalline compounds. Results show 5 PM10 and PM2.5 species not previously reported in the literature. We propose reaction mechanisms for these species and identify specific sources for each crystalline phase found: BaTiO3 was found in PM10 receptor samples and proved to be a vehicular marker formed during brake action; maghemite (γ-Fe2O3), pyracmonite [(NH4)3Fe(SO4)3], ammonium perchlorate (NH3OHClO4) and potassium ferrate (K2Fe2O4) were found in PM2.5 proved to be markers of industrial activities. The crystalline phases found in PM samples from receptor sites and the mechanisms of reactions showed the reliability of the use of crystalline phases as source markers in the identification of potential sources of air pollution without misinterpretation of the likely source.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/análise , Monitoramento Ambiental/métodos , Material Particulado/análise , Material Particulado/química , Sulfato de Amônio/análise , Compostos de Bário/análise , Brasil , Compostos Férricos/análise , Indústrias , Compostos de Ferro/análise , Tamanho da Partícula , Percloratos/análise , Compostos de Potássio/análise , Compostos de Amônio Quaternário/análise , Reprodutibilidade dos Testes , Síncrotrons , Titânio/análise , Difração de Raios X/métodos
3.
Chem Asian J ; 14(23): 4246-4254, 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31571387

RESUMO

A new coordination polymer (H2 bpy)0.5 ⋅[(UO2 )1.5 (ipa)2 (H2 O)] (1) (H2 ipa=isophthalic acid, bpy=4,4'-bipyridine) was synthesized by hydrothermal condition. It was characterized by IR spectroscopy, elemental analysis, TG-DTA analysis, and powder X-ray diffraction. Analysis of single-crystal X-ray diffraction results showed that the title compound exhibited a double chain bridged by the different uranyl ions and ipa2- ligands. Through the hydrogen bond interactions and π⋅⋅⋅π stacking interactions, the double chains were assembled into the three-dimensional supramolecular framework. Furthermore, the compound can be used as a promising bifunctional luminescence sensor for detecting and identifying Fe3+ and tetracycline hydrochloride antibiotic molecules with high selectivity and sensitivity in aqueous solutions. Moreover, the luminescent sensing mechanisms for different analytes were proposed. Moreover, the electronic properties of title compound were explored by density functional theory (DFT) calculations. The sensor system has been successfully applied for the detection of Fe3+ and tetracycline hydrochloride with high recovery percentages and low relative standard deviation in real river water samples.


Assuntos
Compostos Férricos/análise , Corantes Fluorescentes/química , Estruturas Metalorgânicas/química , Tetraciclina/análise , Água/química , Ligantes , Polímeros/química , Teoria Quântica , Espectrometria de Fluorescência , Compostos de Urânio/química
4.
Environ Pollut ; 255(Pt 1): 113134, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31520910

RESUMO

Sediment porewater can be an important source of contaminants in the overlying water, but the mechanisms of metal(loid) and phosphorus (P) remobilization remain to be investigated. In this study, high-resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) samplers were used to determine the porewater dissolved iron (Fe), manganese (Mn), cobalt (Co), chromium (Cr), vanadium (V), selenium (Se), arsenic (As), P and DGT-Labile S in coastal sediments in the Jiulong River Estuary (JRE), China. The results showed that high concentrations of dissolved Mn, Se and P were present in the overlying water, indicating potential water pollution with excessive amounts of Mn, Se and P. The dissolved Mn concentrations in the porewater were higher than the dissolved Fe concentrations, especially at submerged sites, demonstrating that Mn(III/IV) reduction is the dominant diagenetic pathway for organic carbon (OC) degradation, which directly affects Fe cycling by the competitive inhibition of Fe(III) reduction and Fe(II) reoxidation. Dissolved Co, Cr, V, Se, As and P show significant positive correlations with Mn but nearly no correlations with Fe, suggesting that the mobility of these metal(loid)s and P is associated with Mn but not Fe cycling in this region. In addition, the coelevated concentrations of the metal(loid)s, P and Mn at the submerged sites are attributed to the strengthened Mn reduction coupled with OC degradation fueled by hypoxia. The higher positive diffusion fluxes of Mn, Se and P were consistent with the excess Mn, Se and P concentrations in the overlying water, together with the approximately positive fluxes of the other metal(loid)s, indicating that sediment Mn(III/IV) reduction and concomitant metal(loid) and P remobilization might be vital pathways for metal(loid) and P migration to the overlying water.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Metais Pesados/análise , Fósforo/análise , Rios/química , Poluentes Químicos da Água/análise , Arsênico/análise , China , Cromo/análise , Cobalto/análise , Estuários , Compostos Férricos/análise , Ferro/análise , Manganês/análise , Selênio/análise , Vanádio/análise , Água/química
5.
Artigo em Inglês | MEDLINE | ID: mdl-31364465

RESUMO

This paper presents the results of laboratory investigations conducted on gold mine tailings (GMT) to assess their chemical, mineralogical and geotechnical characteristics in view of assessing its suitability as an alternative backfilling solution in mine reclamation. Chemical characterization revealed that GMT is dominated by Si, Al, and Fe with notable amounts of Cr, Zr, Zn, Pb, Ce, As, Ba, Ni, V, Sr, Nd, Cu, U, and Co. Mineralogical characterization revealed a composition of silicate minerals with secondary minerals such as jarosite, goethite and hematite. GMT composites showed improved strength characteristics. The particle sizes of the tailings are capable of producing a good paste fill that will require lower water-cement ratio. Moreover, the plasticity of the tailings provide for a likelihood for shear resistance to sliding in fluvial conditions. Curing and addition of cement showed positive effects on the compressive strength and shear strength of the tailings. However, the effect of curing and cement addition on the compaction characteristics and permeability of the tailings were negligible. GMT showed favorable characteristics for use in mine backfilling; it would be interesting to evaluate higher cement ratios to improve the characteristics of the tailings.


Assuntos
Ouro/análise , Ácidos/análise , Monitoramento Ambiental/métodos , Compostos Férricos/análise , Compostos de Ferro/análise , Minerais/análise , Mineração , África do Sul , Sulfatos/análise
6.
Environ Sci Pollut Res Int ; 26(26): 27268-27280, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31321722

RESUMO

In this study, we investigated the Sb(V) adsorption on ferrihydrite (Fh) at different pH values, in the presence and absence of common competing anions in soil such as phosphate (P(V)) and arsenate (As(V)). Batch adsorption experiments, carried out at pH 4.5, 6.0, and 7.0, showed a greater affinity of Fh towards P(V) and As(V) with respect to Sb(V), especially at higher pH values, while the opposite was true at acidic pH. The capacity of Fh to accumulate greater amounts of phosphate and arsenate in the 6.0-7.0 pH range was mainly linked to the different acid properties of P(V), As(V), and Sb(V) oxyanions. The Sb(V) adsorption on Fh was highly pH-dependent and followed the following order: pH 4.5 (0.957 mmol·g-1 Fh) > pH 6.0 (0.701 mmol·g-1 Fh) > pH 7.0 (0.583 mmol·g-1 Fh). Desorption of antimonate from Sb(V)-saturated Fh, treated with citric and malic acid solutions, was ~equal to 55, 68, and 76% of that sorbed at pH 4.5, 6.0, and 7.0, respectively, while phosphate, arsenate, and sulfate were able to release significantly lower Sb(V) amounts. The FT-IR spectra revealed substantial absorbance shifts related to the surface hydroxyl groups of Fh, which were attributed to the formation of Fe-O-Sb(V) bonds and supported the formation of inner-sphere bonding between Sb(V) and Fh.


Assuntos
Arseniatos/química , Compostos Férricos/análise , Fosfatos/química , Solo/química , Sulfatos/química , Adsorção , Compostos Férricos/química , Concentração de Íons de Hidrogênio , Espectroscopia de Infravermelho com Transformada de Fourier
7.
ACS Appl Mater Interfaces ; 11(31): 28546-28553, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31309830

RESUMO

This work reports an interferometric optical microfiber sensor functionalized with nitrogen- and sulfur-codoped carbon dots (CDs) for the detection of ferric ions (Fe3+). Compared to other CD-based ferric ion sensors, the sensing mechanism of this presented sensor is dependent on the refractive index modulations due to selective Fe3+ adsorption onto the CD binding sites at the tapered region. This is the first study in which CD-based sensing was performed at the solid phase as a chelator, which does not rely on its fluorescence properties. The detection performance of the proposed sensor is not only comparable to a conventional fluorescence-based CD nanoprobe sensor but also capable of delivering quantitative analysis results and ease of translation to a sensor device for on-site detection. The presented sensor exhibits Fe3+ detection sensitivity of 0.0061 nm/(µg/L) in the linear detection range between 0 and 300 µg/L and a detection limit of 0.77 µg/L based on the Langmuir isotherm model. Finally, the potential use of the CD-functionalized optical microfiber sensor in the real environmental and biological Fe3+ monitoring applications has also been validated in this work.


Assuntos
Carbono/química , Compostos Férricos/análise , Fluorescência , Fibras Ópticas , Pontos Quânticos/química , Compostos Férricos/química , Interferometria , Luz , Limite de Detecção
8.
Environ Pollut ; 252(Pt B): 1106-1116, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252108

RESUMO

Hardpans are massively indurated layers formed at the top layer of sulfidic tailings dams, which develop cementation structures and result in heavy metal immobilization. However, the micro-structural and complex forms of the cementing materials are not fully understood, as well as the mechanisms by which Zn and Pb are stabilized in the hardpans. The present study deployed synchrotron-based X-ray fluorescence microscopy (XFM) to have characterized the cementing structures, examined the distribution of Fe, Zn and Pb, and obtained laterally-resolved speciation of Zn within the hardpans using fluorescence X-ray absorption near-edge structure (XANES) imaging. The XFM analyses revealed that the Fe-rich cement layers consisted of Fe (oxyhydr)oxides coupled with amorphous Si materials, immobilizing Zn and Pb. Through laterally-resolved XANES imaging analyses, Zn-ferrihydrite-like precipitates were predicted to account for >76% of the total Zn within the Fe-rich cement layers. In contrast, outside of the cement layers, 9-63% of the Zn was estimated as labile ZnSO4.7H2O, with the remainder in the form of Zn-sulfide. These findings demonstrated that the Fe-rich cement layers were critical in immobilizing Zn and Pb within hardpans via mineral passivation and encapsulation, as the basis for long-term geochemical stability in the hardpan layer of sulfidic mine tailings.


Assuntos
Cobre/análise , Compostos Férricos/análise , Resíduos Industriais/análise , Chumbo/análise , Minerais/análise , Sulfetos/análise , Zinco/análise , Mineração , Queensland
9.
J Chromatogr A ; 1599: 203-214, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31047657

RESUMO

Colloidal iron(III) oxyhydroxides (FeOx) are important reactive adsorbents in nature. This study was set up to determine the size of environmentally relevant FeOx colloids with new methods, i.e. Flow Field Flow Fractionation (FlFFF-UV-ICP-MS) and single-particle ICP-MS/MS (sp-ICP-MS) and to compare these with standard approaches, i.e. dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), microscopy (TEM), membrane filtration, centrifugation and dialysis. Seven synthetic nano- and submicron FeOx with different mineralogy and coating were prepared and two soil solutions were included. The FlFFF was optimized for Fe recovery, yielding 70-90%. The FlFFF determines particle size with high resolution in a 1 mM NH4HCO3 (pH 8.3) background and can detect Fe-NOM complexes <5 nm and organo-mineral FeOx particles ranging 5-300 nm. The sp-ICP-MS method had a size detection limit for FeOx of about 32-47 nm. The distribution of hydrodynamic diameters of goethite particles detected with FlFFF, NTA and DLS were similar but the values were twice as large as the Fe cores of particles detected with sp-ICP-MS and TEM. Conventional fractionation by centrifugation and dialysis generally yielded similar fractions as FlFFF but membrane filtration overestimated the large size fractions. Particles formed from Fe(II) oxidation in the presence of NOM showed strikingly smaller organo-mineral Fe-Ox colloids as the NOM/Fe ratio increased. The soil solution obtained with centrifugation of an acid peat was dominated by small (<30 nm) Fe-OM complexes and organo-mineral FeOx colloids whereas that of a mineral pH neutral soil mainly contains larger (30-200 nm) Fe-rich particles. The FlFFF-UV-ICP-MS is recommended for environmental studies of colloidal FeOx since it has a wide size detection range, it fractionates in an environmentally relevant background (1 mM NH4HCO3) and it has acceptable element recoveries.


Assuntos
Técnicas de Química Analítica/métodos , Coloides/análise , Compostos Férricos/análise , Fracionamento por Campo e Fluxo , Minerais/análise , Espectrometria de Massas em Tandem , Técnicas de Química Analítica/normas , Coloides/química , Difusão Dinâmica da Luz , Compostos de Ferro/análise , Compostos de Ferro/química , Minerais/química , Nanopartículas/análise , Tamanho da Partícula , Solo/química , Análise Espectral
10.
Spectrochim Acta A Mol Biomol Spectrosc ; 219: 248-256, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31048254

RESUMO

A new Cu-doped carbon dots (Cu-CDs) were synthesized rapidly and simply via one-step thermolysis of Na2[Cu(EDTA)] and ascorbic acid (AA) at 250°C for 2h with a high quantum yield of 9.8%. The Cu-CDs exhibits two signals of fluorescence at 396nm and second-order scattering (SOS) at 617nm under a single excitation wavelength of 308nm, and can be obviously enhanced by tryptophan (Trp) or Fe(III) leading to the ratiometric fluorescence and SOS response with a good linear wider range of 0.5-250µM and 0.1-50µM, respectively. This sensing system exhibits good selectivity and sensitivity toward Trp and Fe(III) over other analytes with a low detection limit of 275nM and 46nM, respectively. Furthermore, the proposed sensing system displays a prospective application for quantitative assay of Trp and Fe(III) in practical sample.


Assuntos
Carbono/química , Cobre/química , Compostos Férricos/análise , Corantes Fluorescentes/química , Triptofano/análise , Animais , Bovinos , Difusão Dinâmica da Luz , Lagos/análise , Limite de Detecção , Leite/química , Espectrometria de Fluorescência
11.
Nano Lett ; 19(6): 3618-3626, 2019 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-31074627

RESUMO

Two major technical challenges of magnetic hyperthermia are quantitative assessment of agent distribution during and following administration and achieving uniform heating of the tumor at the desired temperature without damaging the surrounding tissues. In this study, we developed a multimodal MRI/MPI theranostic agent with active biological targeting for improved magnetic hyperthermia therapy (MHT). First, by systematically elucidating the magnetic nanoparticle magnetic characteristics and the magnetic resonance imaging (MRI) and magnetic particle imaging (MPI) signal enhancement effects, which are based on the magnetic anisotropy, size, and type of nanoparticles, we found that 18 nm iron oxide NPs (IOs) could be used as superior nanocrystallines for high performance of MRI/MPI contrast agents in vitro. To improve the delivery uniformity, we then targeted tumors with the 18 nm IOs using a tumor targeting peptide, CREKA. Both MRI and MPI signals showed that the targeting agent improves the intratumoral delivery uniformity of nanoparticles in a 4T1 orthotopic mouse breast cancer model. Lastly, the in vivo antitumor MHT effect was evaluated, and the data showed that the improved targeting and delivery uniformity enables more effective magnetic hyperthermia cancer ablation than otherwise identical, nontargeting IOs. This preclinical study of image-guided MHT using cancer-targeting IOs and a novel MPI system paves the way for new MHT strategies.


Assuntos
Compostos Férricos/uso terapêutico , Nanopartículas de Magnetita/uso terapêutico , Neoplasias/diagnóstico por imagem , Neoplasias/terapia , Animais , Linhagem Celular Tumoral , Compostos Férricos/análise , Hipertermia Induzida/métodos , Terapia de Campo Magnético/métodos , Imagem por Ressonância Magnética/métodos , Nanopartículas de Magnetita/análise , Camundongos , Nanomedicina Teranóstica/métodos
12.
Environ Pollut ; 252(Pt A): 119-127, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31146225

RESUMO

Feammox is a newly discovered and important anaerobic nitrogen (N) loss pathway, and its variation and role in removing N following the application of N fertilizer and its migration from paddies to other land use types and from surface soils to deep soils have not been thoroughly elucidated to date. In this study, field sampling and slurry incubation experiments were performed to evaluate the Feammox rate between different land use types (paddy, irrigation ditch, riparian zone and lake, 0-10 cm) and different paddy soil depths (0-70 cm) in a wheat-rice rotation area in China. Based on a 15N-labelled isotope-tracing technique and analysis of microbial communities, it was estimated that the potential Feammox rate ranged from 0.031 to 0.42 mg N kg-1 d-1 in this area. In the soil profile of the paddy, the depth of 20-30 cm was the active region of Feammox, with a value of 0.37 ±â€¯0.057 mg N kg-1 d-1. Compared with the surface soil (0-10 cm) of the paddy (0.18 ±â€¯0.031 mg N kg-1 d-1), the potential Feammox rate of the irrigation ditch soil was not significantly different, but that of the lake riparian soil and lake sediment were decreased by 27.27% and 32.11%, respectively (p < 0.01). Fe(III) content was the best predictor of the Feammox rate and explained the variation of the Feammox rate by 36.00% in the surface soil. At the genus level, the paddy soil at a depth of 20-30 cm had the greatest abundance of the genera in which the Fe reduction bacteria were distributed; and where Bacillus, Geobacter and Anaeromyxobacter had higher proportions. It was estimated that the potential N loss by Feammox was in the range of 7.36 (the lake) ∼43.35 (the paddy) kg N ha-1 year-1 in the surface soil of this area. Considering denitrification and the Feammox rate as a whole, we found that denitrification remained to be the main contributor to N loss in the surface soil (94.72-96.89% of N loss), although Feammox dominated N loss in the deep soil (below 0-10 cm).


Assuntos
Bactérias/metabolismo , Desnitrificação/fisiologia , Fertilizantes/análise , Nitrogênio/metabolismo , Oryza/metabolismo , Triticum/metabolismo , Compostos de Amônio/análise , Bactérias/classificação , China , Compostos Férricos/análise , Sedimentos Geológicos/química , Lagos , Nitrogênio/análise , Ciclo do Nitrogênio , Oryza/crescimento & desenvolvimento , Solo/química , Triticum/crescimento & desenvolvimento
13.
Food Chem ; 294: 414-422, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31126482

RESUMO

A sequential fractionation procedure based on (i) water extraction, (ii) hexane extraction, (iii) saccharification, and (iv) proteolysis was developed to provide the first ever data on the molecular distribution of iron in maize. This was completed by the operational determination of the iron bioavailability using an in-vitro simulated model for gastro-intestinal digestion. The coupling of hydrophilic interaction chromatography (HILIC) and size exclusion chromatography (SEC) with the parallel detection by inductively coupled plasma mass spectrometry (ICP-MS) and high resolution electrospray mass spectrometry (HR-ESI-MS) allowed the identification of water-soluble Fe(III)-mugineate, Fe(III)-(citrate)2, and Fe(III)2-(phytate)2. The procedures were applied to study some well characterized maize varieties having shown previously differences in iron bioavailability during cell culture and animal model feeding studies. The combined analytical methods developed in this work could unambiguously discriminate low from high Fe bioavailable seeds in these closely related maize varieties.


Assuntos
Ferro/análise , Ferro/farmacocinética , Espectrometria de Massas/métodos , Zea mays/química , Disponibilidade Biológica , Cromatografia em Gel , Cromatografia Líquida , Compostos Férricos/análise , Análise de Alimentos/métodos , Interações Hidrofóbicas e Hidrofílicas , Ácido Fítico/análise , Ácido Fítico/química , Sementes/química , Espectrometria de Massas por Ionização por Electrospray
14.
J Appl Microbiol ; 127(1): 150-158, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31004543

RESUMO

AIMS: This study investigated the effects of ferric citrate, nitrate and saponin, both individually and in combination, on sulphidogenesis, methanogenesis, rumen fermentation and abundances of select microbial populations using in vitro rumen cultures. METHODS AND RESULTS: Ferric citrate (50 mg l-1 ), Quillaja saponin (0·6 g l-1 ) and sodium nitrate (5 mmol l-1 ) were used in in vitro ruminal fermentation. Ferric citrate alone, its combination with saponin and/or nitrate lowered the aqueous sulphide concentration and total sulphide production. Methane production was suppressed by nitrate alone (by up to 32·92%), its combination with saponin (25·04%) and with both saponins with nitrate (25·92%). None of the treatments adversely affected feed digestion or rumen fermentation. The population of sulphate-reducing bacteria was increased by nitrate and saponin individually, while that of total Archaea was decreased by nitrate alone and the combination of the three inhibitors. CONCLUSIONS: Nitrate and its combination with saponin or both ferric citrate and saponin substantially decreased methane production. Most importantly, the decreased methane production was not at the expense of feed digestion or fermentation. Sulphidogenesis from the sulphate present in the high-sulphur diets can be suppressed competitively by ferric citrate, although it was elevated by saponin and nitrate. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study demonstrated that combinations of certain methane inhibitors, which have different mechanisms of antimethanogenic actions or inhibit different guilds of microbes involved in methane production and sulphate reduction, can be more effective and practical than individual inhibitors, not only in mitigating enteric methane emission but also in lowering the risk of sulphur-associated polioencephalomalacia in feedlot cattle fed high sulphur diets.


Assuntos
Metano/antagonistas & inibidores , Metano/metabolismo , Consórcios Microbianos , Rúmen/microbiologia , Sulfetos/metabolismo , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Bovinos , Fermentação , Compostos Férricos/análise , Compostos Férricos/metabolismo , Nitratos/análise , Nitratos/metabolismo , Saponinas/análise , Saponinas/metabolismo
15.
Chemosphere ; 227: 614-623, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31009868

RESUMO

The mining and smelting of lead-zinc (Pb-Zn) ores cause widespread As contamination. The fractions and colloidal distribution of As associated with Fe oxide minerals in Pb-Zn mine-contaminated soils have not been well understood. In this study, As fractions associated with Fe oxide minerals in Pb-Zn tailings- and smelter-contaminated soils were compared using sequential extraction techniques. Kinetic experiments were conducted to characterize the reactivity of Fe oxide minerals. The distribution of As and Fe oxide minerals in soil colloids were analyzed. The results show that in mining-contaminated soils (both tailings and smelter) the relatively active fraction (amorphous hydrous oxide-bound As, AsF3) has a strong relationship with easily reducible Fe (Feox1). In smelter-contaminated soils, relatively stable fractions (crystalline hydrous oxide-bound As, AsF4) were closely associated with reducible Fe (Feox2). Although the average proportions of specifically-bound As (AsF2) and AsF3 in contaminated soils were similar, high As release in tailings-contaminated soils was observed because of the high reactivity of Fe oxide minerals in those soils compared with that in smelter-contaminated soils. Some slightly polluted soils with high pH and TOC concentrations formed As-bearing colloidal suspensions. Especially in smelter-contaminated soils, many small-sized soil colloids could facilitate As migration with surface runoff or vertical transport.


Assuntos
Arsênico/análise , Compostos Férricos/análise , Chumbo/análise , Mineração , Poluentes do Solo/análise , Zinco/análise , China , Coloides , Minerais/análise , Solo/química
16.
Mater Sci Eng C Mater Biol Appl ; 100: 62-69, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30948099

RESUMO

A novel supramolecular organic framework gel (PQPA) has been constructed by a novel bilateral 8-hydroxyquinoline modified pillar[5]arene host (P5Q) and a bilateral bromohexyl functionalized pillar[5]arene guest (P5C6). Interestingly, the gel PQPA shows special selective and ultrasensitive sensing property for Fe3+. The limit of lowest detection (LOD) of gel PQPA for Fe3+ is 0.102 nM. Meanwhile, by adding Fe3+ into the gel PQPA, a no fluorescence Fe3+ coordinated metallogel (PQPA-Fe) could be constructed. Due to the competitive coordination of F-, fluorescent "turn-on" ultrasensitive response of the Fe3+ coordinated metallogel (PQPA-Fe) for F- is achieved. The limit of lowest detection of the Fe3+ coordinated metallogel (PQPA-Fe) for F- is 9.79 nM. In addition, the xerogel of the supramolecular organic framework gel (PQPA) is capable for removing Fe3+ in a lower concentration aqueous solution at an adsorption rate of 99.9%. More importantly, the supramolecular organic framework gel (PQPA) could be used to detect Fe3+ in the Yellow River Water samples. The supramolecular organic framework gel (PQPA) and Fe3+ coordinated metallogel (PQPA-Fe) could act as ultrasensitive reversible fluorescent chemosensor, test kits and fluorescent display materials for Fe3+ and F-.


Assuntos
Calixarenos/química , Compostos Férricos/análise , Fluoretos/análise , Água Doce/análise , Géis/química , Espectrometria de Fluorescência , Limite de Detecção , Fotografação
17.
Anal Chim Acta ; 1066: 112-120, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31027525

RESUMO

A new boronic acid derivative functionalized with a 4-(3-(4-(4,5-diphenyl-1H-imidazole-2-yl)phenyl)-1,2,4-oxadiazol-5-yl)phenyl (IOP) moiety was synthesized for use as a sequential "on-off-on"-type relay fluorescence probe for Fe3+ ions and F- ions with high selectivity and sensitivity under physiological conditions. The introduction of Fe3+ to IOP boronic acid (IOPBA) formed an Fe3+IOPBA complex, which led to quenching of the blue fluorescence intensity at 458 nm. The lowest-energy conformation of IOPBA was theoretically predicted to adopt an extended structure, and the Fe3+ ion in the Fe3+IOPBA complex was coordinated to two phenyl groups to form a π-complex. Upon addition of F- to the Fe3+IOPBA complex, the original fluorescence was recovered due to formation of [FeF6]3‒, resulting in "on-off-on"-type sensor behavior. IOPBA showed high selectivity towards Fe3+ among other cations. Moreover, the Fe3+IOPBA complex showed specific selectivity towards F-, with other cations and anions not interfering with detection. Both sensing processes showed 1:1 stoichiometry with binding constants of 6.87 × 106 and 4.49 × 106 mol-1 L for Fe3+ with IOPBA and F- with Fe3+IOPBA, respectively. The limits of detection for Fe3+ and F- were 10 and 1 nM, respectively. The proposed method was successfully applied in real water samples. Furthermore, the probe had low cytotoxicity and was successfully used as a bioimaging reagent to detect intracellular Fe3+ and F- in living HeLa cells.


Assuntos
Compostos Férricos/análise , Fluorescência , Fluoretos/análise , Sobrevivência Celular , Células HeLa , Humanos , Íons/análise , Estrutura Molecular , Imagem Óptica
18.
Anal Bioanal Chem ; 411(12): 2715-2727, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30941477

RESUMO

In this work, dried flowers of Osmanthus fragrans Lour. were applied as green precursors to synthesize carbon dots (CDs) by a green hydrothermal method for the first time. The CDs showed strong blue fluorescence at 410 nm under 340-nm excitation with a quantum yield of approximately 18.53%. Furthermore, the CDs were applied for the sensitive detection of Fe3+. The linear response of Fe3+ ranged from 10 nM to 50 µM with a limit of detection as low as 5 nM. In addition, other ions were used as competitive substances to explore the selectivity of CDs for Fe3+. The fluorescence quenching effect of Fe3+ was much stronger, which demonstrated that the CDs had high selectivity for Fe3+ and they can be employed for the selective detection of Fe3+. The potential fluorescence quenching mechanism between CDs and Fe3+ was identified as the inner filter effect. The CDs were then used as a fluorescent sensor for the detection of Fe3+ in water samples and human serum; the recovery range was 93.76-113.80% (relative standard deviation less than 0.79%). These results indicate that the CDs can be applied for the sensitive and selective detection of Fe3+ in real samples. Moreover, on the basis of the redox reaction between Fe3+ and ascorbic acid (AA), the CD-Fe3+ system can be used as a fluorescent "off-on" sensor for the detection of AA with a limit of detection of 5 µM. What is more, because of their low toxicity and biocompatibility, the CDs can also be used for cell imaging and acted as a fluorescent probe for fluorescence imaging of Fe3+ and AA in living cells. These results demonstrate that the CDs have great potential for application in the fields of sensing, bioimaging, and even disease diagnosis.


Assuntos
Ácido Ascórbico/análise , Carbono/química , Compostos Férricos/análise , Flores/química , Química Verde/métodos , Nanopartículas/química , Oleaceae/química , Células A549 , Meios de Cultura , Humanos , Limite de Detecção , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica , Espectrometria de Fluorescência
19.
Talanta ; 199: 581-589, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30952301

RESUMO

Heteroatom doping can endow graphene quantum dots (GQDs) with various new or improved structural, optical and physicochemical properties. In contrast to the widely reported oxygen, nitrogen or sulfur doping in GQDs, simple and scalable synthesis of boron-doped GQDs (B-GQDs) with high yield and quantum yields remains challenge. In this work, B-GQDs are one-step synthesized and serve as the fluorescence probes for the fabrication of sensors towards Fe3+ ion or phosphate (Pi) as well as biosensor towards cytochrome C (Cyt C). The B-GQDs are facile synthesized using one-step bottom-up molecular fusion between 1,3,6-trinitropyrene and borax in sodium hydroxide under hydrothermal process. The synthesis can be performed using large volume autoclave (500 ml) with a high yield of 71%, indicating possibility for gram-scale production of B-GQDs. The as-prepared B-GQDs exhibit single or bilayer graphene structure, high crystallinity, uniform size, bright (absolute photoluminescence quantum yield of 16.8%) and excitation-independent green fluorescence (maximum excitation wavelength and emission wavelength of 480 nm and 520 nm, respectively). Successful doping of B atoms in the lattice of GQDs enables high selectivity towards Fe3+. Based on quenching of fluorescence of B-GQDs by Fe3+ (turn-off model), detection of Fe3+ (with limit of detection-LOD of 31.2 nM) and Fe3+-rich Cyt C (with LOD of 5.9 µg/ml) are demonstrated. As Pi can recover Fe3+-quenched fluorescence of B-GQDs (turn-off-on model), indirect fluorescent detection of Pi is also achieved with LOD of 340 nM. In addition, detection of Fe3+, Cyt C and Pi in real samples is achieved.


Assuntos
Técnicas Biossensoriais , Boro/química , Citocromos c/análise , Compostos Férricos/análise , Fluorescência , Grafite/química , Fosfatos/análise , Pontos Quânticos/química , Tamanho da Partícula , Espectrometria de Fluorescência , Propriedades de Superfície
20.
Food Chem Toxicol ; 127: 173-181, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30878530

RESUMO

Iron Oxide Nanoparticles (IONPs) are used in several fields of application, mainly in the biomedical field for their magnetic properties and in food additive known as "E172" for their colour. In the present investigation, we focused on IONP effects on Wistar rat following acute oral exposure. We performed a multiscale physiopathological investigation in order to elucidate potential toxic effects linked to IONP ingestion, especially on cognitive capacities, trace element distribution, blood constituents, organ functions, organ structure and iron deposit. We demonstrated that oral exposure to IONPs induces disturbances of certain parameters depending on the dose. Interestingly, the histopathological examination evidenced inflammatory effects of IONPs in the liver with iron deposits in hepatocytes and Kuppfer cells. Neurobehavioral examination showed that oral exposure to IONPs did not affect nor rat emotions, exploration and locomotion capacities, nor spatial reference memory status. Furthermore, oral administration of IONPs did not disrupt the trace element homeostasis nor in the liver neither in the stomach. Altogether, our study evidenced low signs of toxicity, but some effects lead us to a careful use of these NPs. Thereby, their use in foods should be further studied to better evaluate the potential toxic risks of the oral exposure to IONPs.


Assuntos
Cognição/efeitos dos fármacos , Exposição Dietética , Compostos Férricos/análise , Compostos Férricos/farmacocinética , Nanopartículas Metálicas , Oligoelementos/farmacocinética , Animais , Comportamento Animal/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Testes de Química Clínica , Compostos Férricos/química , Testes Hematológicos , Homeostase , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Nanopartículas Metálicas/química , Tamanho do Órgão/efeitos dos fármacos , Ratos Wistar , Distribuição Tecidual , Testes de Toxicidade Aguda/métodos
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