Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 7.433
Filtrar
1.
J Parasitol ; 106(1): 56-70, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31995719

RESUMO

Rhadinorhynchus hiansi Soota and Bhattacharya, 1981 , has remained unknown since its original incomplete description from 2 male specimens collected from the flat needlefish Ablennes hians Valenciennes (Belonidae) off Trivandrum, Kerala, India. Recent collections of fishes along the Pacific coast of Vietnam in 2016 and 2017 produced many specimens of the same species from the striped bonito Sarda orientalis Temminck and Schlegel (Scombridae) off the southern Pacific coast of Vietnam at Nha Trang. We describe females for the first time, assign a female allotype status, and provide an expanded description of males from a larger collection completing missing information on hooks and hook roots, receptacle, lemnisci, cement glands, Saefftigen's pouch, and trunk spines. Specimens of R. hiansi characteristically have no dorsal spines in the posterior field of trunk spines and a long proboscis with 36-48 dorso-ventrally differentiated proboscis hooks per row becoming progressively smaller posteriorly then increasing in size near the posterior end to a maximum at the posterior-most ring. Trunk, testes, and lemnisci in our specimens were considerably larger than those reported in the original description, but the proboscis was relatively smaller. The females had long reproductive system and corrugated elliptic eggs without polar prolongation of fertilization membrane. Energy Dispersive X-ray Analysis (EDXA) demonstrates high levels of calcium and phosphorus in large gallium cut hooks and high levels of sulfur in tip cuts of large and small hooks and in spines. This EDXA pattern is a characteristic fingerprint of R. hiansi. The molecular profile of R. hiansi is described from 18S rDNA and COI genes, and phylogenetic relationships with most closely related species are discussed.


Assuntos
Acantocéfalos/anatomia & histologia , Acantocéfalos/genética , Beloniformes/parasitologia , Doenças dos Peixes/parasitologia , Helmintíase Animal/parasitologia , Acantocéfalos/classificação , Acantocéfalos/ultraestrutura , Algoritmos , Animais , Teorema de Bayes , Feminino , Peixes , Gálio , Funções Verossimilhança , Masculino , Microscopia Eletrônica de Varredura/veterinária , Oceano Pacífico , Filogenia , Espectrometria por Raios X/veterinária , Vietnã
2.
Food Chem Toxicol ; 135: 110974, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31743745

RESUMO

During tea preparation mineral elements are extracted from the dried leaves of tea (Camellia sinensis (L.) Kuntze) plants into the solution. Micro-particle induced X-ray emission was employed to investigate the spatial distribution of magnesium (Mg), calcium (Ca) and manganese (Mn) in the young and old leaves of tea plants grown in the absence and presence of aluminium (Al) in the substrate. Results revealed that in tea leaves the largest concentrations of Mg occurred in the epidermis, of Ca in oxalate crystals and of Mn in epidermis and oxalate crystals; there was a leaf-age effect on tissue-specific concentrations of Mg, Ca and Mn with all tissues of old leaves containing larger concentrations of Mg, Ca and Mn than young leaves; supplementation of substrate with Al reduced concentrations of Mg, Ca and Mn in the old leaves, and a link between the distribution of Mg, Ca and Mn in the tea leaves with the extraction efficiencies of these elements into the tea was possible. We conclude that old leaves of tea plants cultivated under conditions of low Al availability will have the largest concentrations of Mg, Ca and Mn and may represent most acceptable ingredient for the preparation of tea.


Assuntos
Cálcio/metabolismo , Camellia sinensis/química , Magnésio/metabolismo , Manganês/metabolismo , Folhas de Planta/química , Chá/química , Alumínio/metabolismo , Cálcio/análise , Magnésio/análise , Manganês/análise , Extração em Fase Sólida , Espectrometria por Raios X , Distribuição Tecidual
3.
J Photochem Photobiol B ; 203: 111740, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31887638

RESUMO

PURPOSE: The aims of this ex vivo study were to evaluate the effectiveness of the Nd:YAP laser in the treatment of dentin hypersensitivity, to compare the temperature rise during laser irradiation at three different dentine thicknesses, and to analyse the composition of the dentine-lased surface. METHODS: A total of 33 teeth were used in this study. For scanning electron microscopy (SEM) observation, 24 teeth were transversely sectioned and divided into 4 groups: group A was irrigated with EDTA; group B was irradiated by Nd:YAP laser with 180 mJ energy/per pulse, 0.9 W average power, and 5 Hz frequency (power density [PD] = 229 W/cm2); group C was irradiated by Nd:YAP laser with 280 mJ energy/pulse, 1.4 W average power, and 5 Hz frequency (PD = 356 W/cm2); and group D was irradiated by Nd:YAP with 360 mJ energy/pulse, 1.8 W average power, and 5 Hz frequency (PD = 458 W/cm2). Energy-dispersive spectroscopy (EDS) analysis was performed on the same teeth evaluated for SEM observations. For temperature increase evaluation performed with thermocouples, 9 teeth were transversely sectioned at 3 different thicknesses (3 for each group) of 1, 2, and 3 mm. RESULTS: Statistical analysis showed significant changes in the diameter of the dentinal tubule orifices among all groups; EDS did not show modification of the Ca/P ratio. Temperature increase under irradiation exceeded 5.5 °C only in the group D samples. CONCLUSIONS: This ex vivo study, based on temperature recording, SEM observation, and EDS analysis, demonstrated that Nd:YAP laser at a PD of 356 W/cm2, corresponding to an average power of 1.4 W, defines the best treatment for dentine hypersensitivity in terms of compromise between efficacy of the treatment and safety of the pulp.


Assuntos
Sensibilidade da Dentina/radioterapia , Lasers de Estado Sólido/uso terapêutico , Dentina/fisiologia , Dentina/efeitos da radiação , Humanos , Microscopia Eletrônica de Varredura , Espectrometria por Raios X , Temperatura Ambiente
4.
Chemosphere ; 239: 124775, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31521931

RESUMO

Enriched levels of thallium (Tl) in the environment are not only derived from anthropogenic sources but also have potential natural origins owing to Tl-rich sulphide mineralization. However, little is known regarding the geochemical fractionations of Tl in contaminated soils from geogenic sources. This study aims to reveal the Tl geochemical fractionations in different types of soils from a large-scale independent Tl mine in southwestern China, via a modified Institute for Reference Materials and Measurement (IRMM) sequential extraction (four-step) scheme. The results revealed that a large percentage of Tl was related to the labile portions (including reducible, weak-acid-exchangeable, and oxidizable fraction) of the soils (68.8-367 mg kg-1). Further analyses by Scanning Transmission Electron Microscopy-Energy Dispersive X-ray Spectrometer (STEM-EDS) found that Tl mainly existed in the Fe-containing minerals (such as jarosite and hematite) with fine particles (∼1 µm). These results highlight that, apart from the anthropogenically induced Tl pollution, the naturally occurring Tl contamination in soils may also pose significant risks to human health and ecological safety. Owing to the relatively high mobility and bioavailability of Tl in the labile fractions, it is important to understand geochemical fractionations of this element for alleviating Tl pollution and effective management of naturally occurring Tl contaminated soils.


Assuntos
Poluentes do Solo/química , Tálio/química , Fracionamento Químico , China , Monitoramento Ambiental/métodos , Compostos Férricos/química , Humanos , Mercúrio/análise , Microscopia Eletrônica de Transmissão e Varredura , Solo/química , Poluentes do Solo/análise , Espectrometria por Raios X , Sulfatos/química , Sulfetos/análise , Tálio/análise
5.
Chemosphere ; 238: 124624, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31472353

RESUMO

The capacity of two iron-based nanomaterials, namely goethite nanospheres (nGoethite) and zero valent iron nanoparticles (nZVI), to immobilize As in a polluted soil was evaluated and compared. The composition and morphology of the products were studied by energy dispersive X-ray analysis and transmission electron microscopy, while zeta potential and average sizes were determined by dynamic light scattering. To assess As immobilization, soil subsamples were treated with nGoethite or nZVI at a range of Fe doses (0.5%, 2%, 5% and 10%) and then studied by the TCLP test and the Tessier sequential extraction procedure. The influence of both nanoparticles on As speciation was determined, as was impact on soil pH, electrical conductivity, Fe availability and phytotoxicity (watercress germination). For nZVI, notable results were achieved at a dose of 2% (89.5% decrease in As, TCLP test), and no negative effects on soil parameters were detected. Indeed, even soil phytotoxicity was reduced and only at the highest dose was a slight increase in As3+ detected. In contrast, excellent results were obtained for nGoethite at the lowest dose (0.2%) (82.5% decrease in As, TCLP test); however, soil phytotoxicity was increased at higher doses, probably due to a marked enhancement of electrical conductivity. For both types of nanoparticle, slight increases in Fe availability were observed. Thus, our results show that both nZVI and nGoethite have the capacity to effectively immobilize As in this brownfield. The use of lower doses of nGoethite emerges as a promising soil remediation strategy for soils affected by As pollution.


Assuntos
Arsênico/análise , Poluição Ambiental/análise , Recuperação e Remediação Ambiental/métodos , Nanopartículas Metálicas/química , Poluentes do Solo/análise , Solo/química , Ferro/química , Compostos de Ferro/química , Microscopia Eletrônica de Transmissão , Minerais/química , Espectrometria por Raios X
6.
Chemosphere ; 239: 124750, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526995

RESUMO

Perfluoroalkyl substances (PFASs) were investigated in three types of vegetables (fruit, leafy, and root vegetables) that were cultivated and harvested from 2014 to 2017. The cultivated soil was mainly affected by perfluoroalkyl carboxylic acid (PFCAs; 91.8% detection rate) rather than perfluoroalkyl sulfonic acids (PFSAs; 8.2%). The cultivated soil (i.e., a volcanic cohesive soil) had a high total organic carbon (TOC = 3.4%) and therefore showed strong adsorption of long-chain PFASs. Short-chain PFCAs (i.e., under C9) were mainly detected in vegetables; specifically, PFBA showed high concentration in tomato shoots. Principal component analysis (PCA) plots clearly showed that PFASs in vegetables were different from those of cultivated soil, air, and rainwater. Interestingly, the whole potato (i.e., including peel) was in the same group as soil, indicating that the whole potato can easily be affected by the cultivated soil. Energy Dispersive X-ray Spectrometry-Scanning Electron Microscope (EDS-SEM) results showed that presence of unremovable micron-sized cultivated soil particles on the potato surface. Comparing the regional differences between the cultivated area of Tsukuba city (East Japan) and Osaka city (West Japan), PFASs patterns were similar in cucumber but differed in green perilla and potato.


Assuntos
Fluorcarbonetos/análise , Contaminação de Alimentos/análise , Verduras/química , Adsorção , Frutas/química , Japão , Análise de Componente Principal , Chuva , Solo/química , Poluentes do Solo/análise , Espectrometria por Raios X , Poluentes Químicos da Água/análise
7.
Chemosphere ; 238: 124663, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31472343

RESUMO

Ochrobactrum anthropi DE2010 is a microorganism isolated from Ebro Delta microbial mats and able to resist high doses of chromium(III) due to its capacity to tolerate, absorb and accumulate this metal. The effect of this pollutant on O. anthropi DE2010 has been studied assessing changes in viability and biomass, sorption yields and removal efficiencies. Furthermore, and for the first time, its capacity for immobilizing Cr(III) from culture media was tested by a combination of High Angle Annular Dark Field (HAADF) Scanning Transmission Electron Microscopy (STEM) imaging coupled to Energy Dispersive X-ray spectroscopy (EDX). The results showed that O. anthropi DE2010 was grown optimally at 0-2 mM Cr(III). On the other hand, from 2 to 10 mM Cr(III) microbial plate counts, growth rates, cell viability, and biomass decreased while extracellular polymeric substances (EPS) production increases. Furthermore, this bacterium had a great ability to remove Cr(III) at 10 mM (q = 950.00 mg g-1) immobilizing it mostly in bright polyphosphate inclusions and secondarily on the cellular surface at the EPS level. Based on these results, O. anthropi DE2010 could be considered as a potential agent for bioremediation in Cr(III) contaminated environments.


Assuntos
Biodegradação Ambiental , Cromo/farmacocinética , Ochrobactrum anthropi/metabolismo , Biomassa , Cromo/metabolismo , Viabilidade Microbiana , Ochrobactrum anthropi/crescimento & desenvolvimento , Espectrometria por Raios X
8.
Environ Monit Assess ; 192(1): 46, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31844991

RESUMO

A by-product of industrialization and population growth, automobile scrap yards are a potential source of metal contamination in soil. This study evaluated the use of portable X-ray fluorescence (pXRF) spectrometry and magnetic susceptibility (χ) analysis in assessing metal soil contamination in scrap yards located in Brazil. Five automobile scrap yards were selected in Curitiba, Paraná State (CB1, CB2, and CB3) and Lavras, Minas Gerais State (LV1 and LV2). By evaluating metal concentrations and geoaccumulation index values, we verified moderate Cu, Pb, and Zr contamination and moderate to high Zn contamination, primarily in the topsoil (0-10 cm). Soil Zn concentrations in automobile scrap yards were on average four times higher than in reference soils, suggesting that galvanized automobile parts may be the primary source of this soil contaminant. Although other elements (i.e., As, Cr, Fe, Nb, Ni, and Y) were slightly increased compared to reference values in one or more soils, concentrations did not constitute contamination. Automobile scrap yard topsoil had higher χ values (5.8 to 52.9 × 10-7 m3 kg-1) at low frequency (χlf) compared to reference soil (3.6 to 7.5 × 10-7 m3 kg-1). The highest values of χlf occurred in LV soils, which also represented the highest Zn contamination. Magnetic multidomain characteristics (percent frequency-dependent susceptibility between 2 and 10) indicated magnetic particle contributions of anthropogenic origin. The use of pXRF and χlf as non-destructive techniques displays potential for identifying soil contamination in automobile scrap yards.


Assuntos
Automóveis , Monitoramento Ambiental , Poluição Ambiental/estatística & dados numéricos , Poluentes do Solo/análise , Resíduos , Brasil , Meio Ambiente , Poluição Ambiental/análise , Fenômenos Magnéticos , Metais/análise , Metais Pesados/análise , Solo/química , Espectrometria por Raios X/métodos , Instalações de Eliminação de Resíduos
9.
J Agric Food Chem ; 67(47): 13010-13020, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31670946

RESUMO

Increasing the yield of soybean is a challenge to humankind dependent on several management practices, such as fertilizing and weed control. While glyphosate contributes to controlling weeds, it can interfere with spray mixture stability and, supposedly, complex with micronutrients within the plant tissue. This study investigated the effects of glyphosate on soybean foliar uptake and transport of Mn supplied as MnSO4, MnHPO3, Mn-ethylenediamine tetraacetic acid (EDTA), and MnCO3. These fertilizers induced ultrastructural changes in the leaf cuticle, regardless of the glyphosate mixture. Except for MnCO3, all tested sources increased the Mn content in the petiole. The mixture of glyphosate impaired Mn transport from MnSO4 and MnHPO3, but no evidence of Mn-glyphosate complexation within the plant was found. Manganese is rather transported in a similar chemical environment regardless of the source, except for Mn-EDTA, which was absorbed and transported in its pristine form. Interferences of glyphosate seem to be related to complexations in the tank mixture rather than affecting nutrients' metabolism.


Assuntos
Glicina/análogos & derivados , Herbicidas/farmacologia , Manganês/metabolismo , Folhas de Planta/química , Soja/efeitos dos fármacos , Soja/metabolismo , Transporte Biológico , Glicina/química , Glicina/farmacologia , Cinética , Manganês/química , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Soja/química , Espectrometria por Raios X
10.
Pan Afr Med J ; 33: 296, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31692868

RESUMO

Introduction: There is a growing interest on vital roles of micronutrients in the maintenance of good health and enhancement of the immune system for prevention of diseases. Methods: Energy dispersive X-Ray fluorescence (EDXRF) spectrometer was used for qualitative and quantitative analysis of selected micronutrients Zinc (Zn), Iron (Fe), Magnesium (Mg), Calcium (Ca) and Potassium (K) in ten African indigenous leafy vegetables (AILVs) (Corchorus olitorius, Cucurbita moschata, Amaranthus blitum, Brassica carinata , Cleome gynandra, Solanum scabrum , Crotalaria ochroleuca, Urticadioica, Manihot esculenta, Vigna unguiculata) which are cultivated, marketed and consumed in Kenya and across East and West Africa. Results: In this study, the highest levels of Calcium, Zinc and Iron were found in Urticadioica leaves (75.0 mg/g), Manihot esculenta leaves (0.1 mg/g) and Cucurbita moschata leaves (1.0 mg/g). Amaranthus blitum leaves exhibited the highest content of Magnesium (9.5 mg/g) and Potassium (36.5 mg/g) respectively. This study demonstrated that based on weight and bioavailabilty, 10 g of Cucurbita moschata (dried weight) provides between 57% to 136% daily value of iron for children age between 7 and 10 years old and can provide up to 41%, 81% and 27% daily value of iron for female aged 18+, lactating females aged 18+ and males aged 18+ respectively. A 10 g portion of Urticadioica leaves (dried weight) will provide 75% or 58% of the daily value of calcium based on the North American or western European recommendation respectively while the same amount of Amaranthus leaves provides between 37% to 50 % of daily value of magnesium for adults of nineteen years and older based on their weight. The daily value of zinc despite its dependency with age, weight and Zinc bioavailability can be supplied by 10 g of Manihot esculenta leaves (dried weight) at a percentage ranged from 8% to 39%. Based on the 3510 mg daily recommendation, 10 g of Amaranthus, Brassica carinata, Cleome gynandra and Cucurbita moschata (dried weight) will provide 10.4%, 10.0%, 9.8% and 9.3% daily value for potassium respectively. Conclusion: The research findings are scientific evidences of the nutritional contribution of African indigenous leafy vegetables.


Assuntos
Micronutrientes/análise , Necessidades Nutricionais , Verduras/química , Adulto , Criança , Feminino , Humanos , Quênia , Masculino , Folhas de Planta/química , Espectrometria por Raios X
11.
Braz Oral Res ; 33: e120, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31778475

RESUMO

The objective of this study is to compare the resin-enamel bond strength (mµSBS), in-situ degree of conversion (DC), and the enamel-etching pattern (SEM/EDX) of universal adhesive systems when applied to sound and fluorotic enamel. Ninety-eight human molars were sectioned into 4 parts and divided into 24 groups according to 1) enamel surface (sound or fluorotic enamel), 2) adhesive system (Clearfil Universal Bond [CUB], Futurabond U [FBU], iBond Universal [IBU], and Scotchbond Universal [SBU]), and 3) application mode (etch-and-rinse [ER], active self-etch [Active-SE], and passive self-etch [Passive-SE]). Specimens were stored at 37 °C, for 24 hours and tested at 1.0 mm/min (µSBS). Enamel-resin interfaces were evaluated for in-situ DC. The enamel-etching pattern was evaluated under a SEM/EDX. Data from mµSBS and in-situ DC was analyzed using a three-way ANOVA and Tukey's test at 5 % level of significance. For all adhesives, the ER resulted in a statistically significant higher mean mµSBS than the passive-SE in both substrates (p < 0.001). For all adhesives, active-SE resulted in mean mµSBS (p > 0.31) and in-situ DC (p > 0.45) that were statistically similar to those obtained with the ERs in both substrates. A statistically significant, higher mean mµSBS and in-situ DC were obtained in sound enamel (p < 0.001) than in fluorotic enamel. In general, SBU showed higher mean values for mµSBS and in-situ DC compared to those of CUB and IBU (p < 0.001). ER and active-SE showed the deepest enamel-etching pattern in both substrates. A higher amount of fluor was observed in fluorotic enamel. The active application of universal adhesives in the SE-mode may be a viable alternative to increase the adhesive properties in sound and fluorotic enamel.


Assuntos
Colagem Dentária/métodos , Esmalte Dentário/química , Esmalte Dentário/efeitos dos fármacos , Fluorose Dentária , Cimentos de Resina/química , Análise de Variância , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Distribuição Aleatória , Valores de Referência , Reprodutibilidade dos Testes , Resistência ao Cisalhamento/efeitos dos fármacos , Espectrometria por Raios X , Análise Espectral Raman , Propriedades de Superfície/efeitos dos fármacos
12.
Environ Monit Assess ; 191(11): 661, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31650240

RESUMO

Though not litigable in most European countries, portable X-ray fluorescence spectrometers (pXRF) provide cost- and time-effective as well as prompt information about hot spots of inorganic soil contaminants. The quality of aqua regia analysis of contaminants can be approximated by a thorough sample preparation, i.e., homogenization, grinding, and sieving of the examined soil before pXRF measurement is carried out. However, elaborate sample preparation causes a trade-off in terms of the desired straightforwardness of the pXRF method. For a first assessment of the in situ accuracy of pXRF measurements, two equal pXRF devices were used in parallel to determine the contents of As, Cu, Fe, Mn, Pb, Rb, Sr, Zn, and Zr of 9 identical points of a riparian soil profile. Maximum measurement values were not restricted to one pXRF device, but changed from element to element. Pearson correlation coefficients of the parallel measurements varied between 0.07 (Cu) and 0.80 (Zn), reflecting small-scale heterogeneity of the soil constituents as well as element-specific interferences. For each element, overall deviations between measurement parallels were expressed as the root-mean-square error (RMSE) and contrasted against the element-specific information depth in soil, i.e., the depth interval, from which the received spectral signals originate. From this, a gradual relation could be derived: The greater the information depth, the more stable the measured element value turns out. This context should be taken into account, when interpreting contents of elements with small atomic numbers.


Assuntos
Monitoramento Ambiental/métodos , Poluição Ambiental/análise , Metais/análise , Poluentes do Solo/análise , Solo/química , Europa (Continente) , Espectrometria por Raios X/métodos
13.
Int J Nanomedicine ; 14: 8105-8119, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31632021

RESUMO

Background: Super-paramagnetic iron oxide nanoparticles (SPIONs) are widely used metal nanoparticles for various applications for its magnetic property and biocompatibility. In recent years, pollution of our environment especially with heavy metals in waterbodies has become a major threat and has left us very minimal sources of freshwater to drink. SPIONs or surface modified SPIONs can be used to remove these heavy metals. Methods: SPIONs were synthesized by co-precipitation method and further coated with a biopolymer, chitosan. Chromium solution was treated with the synthesized SPIONs to study the efficiency of chromium removal by surface adsorption. Later, the adsorption was analysed by direct and indirect analysis methods using UV-VIS spectrophotometry and isotherm studies. Results: Stable chitosan-coated SPIONs were synthesized and they adsorbed chromium better than the uncoated SPIONs, where it was adsorbing up to 100 ppm. Adsorption was found to be increasing with decrease in pH. Conclusion: The surface-modified SPIONs expressed cumulative adsorption action. Even after the adsorption studies, chitosan-coated SPIONs were possessing magnetic property. Thus, the surface-modified SPIONs can become an ideal nanotechnology tool to remove the chromium from groundwater.


Assuntos
Cromo/isolamento & purificação , Compostos Férricos/química , Nanopartículas de Magnetita/química , Nanotecnologia/métodos , Adsorção , Concentração de Íons de Hidrogênio , Nanopartículas de Magnetita/ultraestrutura , Nanopartículas/química , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Propriedades de Superfície , Temperatura Ambiente , Fatores de Tempo , Difração de Raios X
14.
Environ Pollut ; 255(Pt 1): 113214, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31541812

RESUMO

Magnetic properties of urban street dust can be used as a proxy of urban pollution. In this study, magnetic measurements on 160 street dust samples, collected from five different functional areas (industrial, traffic, commercial, residential and clean areas) in sixteen administrative districts in Shanghai, China, were systematically conducted. It is showed that magnetic carriers were predominately coarse-grain ferrimagnetic particles. Meantime, concentration-related magnetic parameters showed significant variations among the functional areas and administrative units. Magnetic susceptibility (χ) decreased in the following order: industrial area (IA) > traffic area (TA) > commercial area (CoA) > residential area (RA) > clean area (ClA). Moreover, combined with the analyses conducted using a scanning electron microscope and an energy dispersive X-ray spectrometer (SEM-EDX), it is found that spherical magnetic particles originating mainly from anthropogenic sources were abundant in industrial areas. Baoshan district, which is heavily impacted by industrial activities, showed the highest χ value among the administrative units. Additionally, the correlations of street dust χ value with population, value of industrial output and the gross domestic product (GDP) in Shanghai and other cities indicated that χ is positively correlated with the city GDP as well as the population size (PS) to some extent. This study demonstrates that magnetic parameters of street dust can be used as an effective tool for monitoring environmental pollution and industrial activities in urban environments.


Assuntos
Poeira/análise , Monitoramento Ambiental , China , Cidades , Poluição Ambiental/análise , Poluição Ambiental/estatística & dados numéricos , Indústrias , Fenômenos Magnéticos , Magnetismo , Metais Pesados/análise , Espectrometria por Raios X
15.
Int J Nanomedicine ; 14: 6869-6889, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31507318

RESUMO

Introduction: Biodegradable polymers that contain radioactive isotopes such as Holmium 166 have potential applications as beta particle emitters in tumor tissues. Also, Ho(III) is paramagnetic, which makes it suitable as a contrast agent for magnetic resonance (MR) images. Methods: Holmium acetylacetonate (Ho(acac)3) loaded poly(3-hydroxy-butyrate-co-3-hydroxy-valerate) microspheres, with 5% or 8% of 3-hydroxy-valerate (HV), were prepared by emulsification/evaporation process within 20-53 µm size. Microspheres characterization was done using scanning electron microscopy, energy-dispersive X-ray, and infrared spectroscopies. The release of holmium(III) in sodium phosphate buffer (pH 7.4) was followed for 9 days with inductively coupled plasma. Finally, T2 and T2* magnetic resonance images (MRI) were acquired and compared with the MRI of the inclusion complex of holmium acetylacetonate in some ß-cyclodextrins. Results: Holmium acetylacetonate loading, evaluated by thermogravimetry, was up to 20 times higher for copolymer with 5% of HV. It was shown that microspheres loaded with Ho(acac)3 exhibited an accumulation of Ho(III) on their surfaces but were stable over time, as no expressive release of holmium(III) was detected in 9-day exposition to sodium phosphate buffer. Holmium acetylacetonate in both microspheres or inclusion complexes was very efficient in obtaining T2 and T2* weighted images in magnetic resonance, thus, might be used as contrast agents. Conclusion: This is the first description of the use of inclusion complexes of holmium acetylacetonate in biodegradable polymers as contrast agents. New investigations are underway to evaluate the resistance of PHB-HV polymer microparticles to nuclear activation to assess their potential for use as radiopharmaceuticals for the treatment of liver cancer.


Assuntos
Meios de Contraste/química , Hólmio/química , Hidroxibutiratos/química , Imagem por Ressonância Magnética , Microesferas , Pentanonas/química , Poliésteres/química , Radioisótopos/química , Calibragem , Humanos , Espectrometria por Raios X , Termogravimetria , Difração de Raios X
16.
Chemosphere ; 237: 124567, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549665

RESUMO

Hexavalent chromium reduction by microbes can mitigate the chromium toxicity to the environment. In the present study Cr[VI] tolerant fungal isolate (CR500) was isolated from electroplating wastewater, was able to tolerate 800 mg/L of Cr[VI. Based on the ITS region sequencing, the isolate was identified as Aspergillus flavus CR500, showed multifarious biochemical (reactive oxygen species, antioxidants response and non-protein thiol) and morphological (protrusion less, constriction and swelling/outwards growth in mycelia) response under Cr[VI] stress. Batch experiment was conducted at different Cr[VI] concentration (0-200 mg/L) to optimize the Cr[VI] reduction and removal ability of isolate CR500; results showed 89.1% reduction of Cr[VI] to Cr[III] within 24 h and 4.9 ±â€¯0.12 mg of Cr per gram of dried biomass accumulation within 144 h at the concentration of 50 mg/L of Cr[VI]. However, a maximum of 79.4% removal of Cr was recorded at 5 mg/L within 144 h. Fourier-transform infrared spectroscopy, energy dispersive x-ray spectroscopy and X-ray diffraction analysis revealed that chromium removal also happened via adsorption/precipitation on the mycelia surface. Fungus treated and without treated 100 mg/L of Cr[VI] solution was subjected to phytotoxicity test using Vigna radiata seeds and result revealed that A. flavus CR500 successfully detoxified the Cr[VI] via reduction and removal mechanisms. Isolate CR500 also exhibited efficient bioreduction potential at different temperature (20-40 °C), pH (5.0-9.0), heavy metals (As, Cd, Cu, Mn, Ni and Pb), metabolic inhibitors (phenol and EDTA) and in sterilized tannery effluent that make it a potential candidate for Cr[VI] bioremediation.


Assuntos
Aspergillus flavus/metabolismo , Cromo/metabolismo , Cromo/toxicidade , Águas Residuárias/microbiologia , Adsorção , Aspergillus flavus/efeitos dos fármacos , Aspergillus flavus/genética , Biodegradação Ambiental , Galvanoplastia , Metais Pesados/análise , Fenol/análise , Sementes/efeitos dos fármacos , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Vigna/efeitos dos fármacos , Águas Residuárias/análise , Águas Residuárias/toxicidade , Difração de Raios X
17.
Chemosphere ; 237: 124534, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549651

RESUMO

Information on the effects of multi-walled carbon nanotubes (MWCNTs) on topsoil around coal power plants (CPPs) is still very limited. In the present work, the influences of MWCNTs on potential hazardous elements (PHEs) and environmental carbonaceous compounds in agrarian topsoil around CPPs of Latin America were investigated. The environmentally elevated proportions of MWCNTs and PHEs can cause damage to developing a fetus. The ecological impacts of industrial energy byproducts generated by MWCNTs were also studied. The surface morphologies of MWCNTs and PHEs detected in topsoil samples were analyzed by advanced electron microscopy in a combination of energy dispersive X-ray spectroscopy (EDS). The alterations could be originated due to the different geophysical constituents and superficial structure, which in turn disturbed their geoavailability in studied topsoil. It was found that a large amount of MWCNTs and amorphous carbonaceous matters, which are responsible for adsorbing PHEs, existed in soils around CPPs. Hence, these findings could be used to better understand the geochemical properties of PHEs near CPPs.


Assuntos
Monitoramento Ambiental , Nanotubos de Carbono/química , Centrais Elétricas , Poluentes do Solo/análise , Adsorção , Carvão Mineral/análise , Solo/química , Espectrometria por Raios X
18.
Chemosphere ; 237: 124540, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549654

RESUMO

Lead can be immobilized in contaminated soils by phosphate rock (PR) amendment, but its efficiency is generally limited by low solubility of PR. Our study aimed to elucidate whether phosphate solubilizing bacteria (PSB) can promote Pb immobilization through PR solubilization. Results showed that P. ananatis HCR2 and B. thuringiensis GL-1 could effectively solubilize PR by producing citric, glucose, and α-Ketoglutaric acids. In broth assay, phosphate solubilized from PR by PSB rapidly reacted with Pb2+ and formed insoluble lead compounds, as confirmed by scanning electron microscope, energy dispersive X-ray, and X-ray photoelectron spectroscopy. Pot experiment using lettuce (Lactuca sativa L.) and diffusive gradients in thin films (DGT) verified the effectiveness of soil remediation using PR amendment and PSB inoculation, as plant shoot biomass and net photosynthetic rate as well as soil bioavailable phosphate concentration have significantly increased, while the phytoavailability of Pb, Cd, and Zn greatly reduced. This study suggested that PR amendment combined with PSB inoculation could be applied for remediation of agricultural fields contaminated with multiple heavy metals.


Assuntos
Recuperação e Remediação Ambiental/métodos , Chumbo/química , Fosfatos/química , Microbiologia do Solo , Poluentes do Solo/química , Bacillus thuringiensis/fisiologia , Disponibilidade Biológica , Chumbo/farmacocinética , Alface/efeitos dos fármacos , Alface/crescimento & desenvolvimento , Alface/fisiologia , Metais Pesados/análise , Metais Pesados/farmacocinética , Pantoea/fisiologia , Espectroscopia Fotoeletrônica , Fotossíntese/fisiologia , Brotos de Planta/crescimento & desenvolvimento , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/farmacocinética , Solubilidade , Espectrometria por Raios X
19.
Mater Sci Eng C Mater Biol Appl ; 104: 109919, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499980

RESUMO

An eco-friendly biosynthesized Pd NP anchored Thymbra spicata extract-modified graphene oxide (Pd NPs/rGO-T. spicata) nanohybrid material has been introduced. Initially, the herb, Thymbra spicata extract was immobilized on the surface of GO via their natural adhering capability. The polyphenolic function grafted in situ prepared RGO acted as the natural reductant of Pd precursor. The as-prepared nanocomposite (Pd NPs/rGO-T. spicata) was characterized using Fourier transform infrared (FTIR), UV-vis, X-ray diffraction (XRD), inductively coupled plasma (ICP), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), Fast Fourier Transform (FFT), Raman spectroscopy and EDX elemental mapping techniques. It has been observed that the Pd NPs with perfect crystal structure, uniform shape and size were dispersed homogeneously on the rGO surface. The material showed excellent water dispersibility due to the hydrophilicity of biomolecules attached over them, which is very essential in heterogeneous catalysis. The T. spicata contained biomolecules served as effective capping, reducing and stabilizing agents for the uniform immobilization of Pd precursors on graphene sheet surface without aggregation. The catalytic activity of this nano hybrid was assessed comprehensively in the cyanation of aryl halides with a wide range of substrates using K4[Fe(CN)6] as a cheap source of cyanide. The model reaction resulted outstanding catalytic performance with a great reusability of the catalysis.


Assuntos
Cianetos/química , Grafite/química , Halogênios/química , Nanopartículas Metálicas/química , Paládio/química , Extratos Vegetais/química , Catálise , Lamiaceae/ultraestrutura , Nanopartículas Metálicas/ultraestrutura , Espectrometria por Raios X , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Difração de Raios X
20.
Mater Sci Eng C Mater Biol Appl ; 104: 109981, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500056

RESUMO

Zinc oxide nanoparticles (ZnO-NPs) are multifunctional oxide metal nanoparticles that have been considered by many due to their unique properties including UV filtration, semiconducting, antimicrobial, antifungal, and photocatalytic activity. In the present study, ZnO-NPs have been synthesized from Zn(SO4)·7H2O through the use of "green synthesis" method that utilizes Prosopis farcta aqueous extract. The characterization of synthesized ZnO-NPs have been performed by UV-Vis absorption, Fourier-Transform Infrared spectroscopy (FT-IR), Raman, Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray analysis (EDX). Results have illustrated that the synthesized nanoparticles contain a hexagonal shape and sheet form with sizes of 40-80 nm. The antifungal activity of ZnO-NPs against Candida albicans has shown that the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were 128 and 256 µg/ml, respectively. The cytotoxicity activity of synthesized nanoparticles was tested on breast cancer cells (MCF7), while the IC50 was calculated to be 90 µg/ml.


Assuntos
Antifúngicos/química , Antifúngicos/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Nanopartículas Metálicas/química , Óxido de Zinco/química , Neoplasias da Mama/tratamento farmacológico , Candida albicans/efeitos dos fármacos , Feminino , Química Verde/métodos , Humanos , Células MCF-7 , Testes de Sensibilidade Microbiana/métodos , Microscopia Eletrônica de Varredura/métodos , Microscopia Eletrônica de Transmissão/métodos , Tamanho da Partícula , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Espectrometria por Raios X/métodos , Difração de Raios X/métodos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA