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1.
Environ Int ; 158: 106991, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34991252

RESUMO

Magnetite (Fe3O4) nano-particles (MNPs) have been found in human tissues and causally linked to serious illnesses. The possible negative role of MNPs has been not still fully ascertained even though MNPs might cause health effects due to their magnetic property, redox activity and surface charge. The origin of MNPs in human tissues still remains to be unambiguously identified since biological processes, natural phenomena and anthropogenic production have been proposed. According to this latter increasingly convincing hypothesis, anthropogenic MNPs might enter mainly in the human body via inhalation, penetrate deeply into the lungs and in the alveoli and also migrate into the blood circulation and gather in the extrapulmonary organs and central nervous system. In order to identify the releasing source of the potentially inhalable MNPs, we pioneered an innovative approach to rapidly investigate elemental profile and morphology of a large number of airborne micron and sub-micron-sized Fe-bearing particles (FePs). The study was performed by collecting a large amount of micron and sub-micron sized inhalable airborne FePs in trafficked and densely frequented areas of Rome (Italy). Then, we have investigated individually the elemental profile and morphology of the collected particles by means of high-spatial resolution scanning electron microscopy, energy dispersive spectroscopy and an automated software purposely developed for the metal-bearing particles analysis. On the basis of specific elemental tracing features, the investigation reveals that almost the total amount of the airborne FePs is released by the vehicle braking systems mainly in the form of magnetite. Furthermore, we point out that our approach might be more generally used to identify the releasing sources of different inorganic airborne particles and to contribute to establish more accurately the impact of specific natural or anthropogenic particles on the environment and human health.


Assuntos
Poluentes Atmosféricos , Poluentes Atmosféricos/análise , Óxido Ferroso-Férrico , Humanos , Metais/análise , Tamanho da Partícula , Espectrometria por Raios X
2.
Spectrochim Acta A Mol Biomol Spectrosc ; 268: 120713, 2022 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-34896674

RESUMO

The nest of Eumeninae wasp is one of nature's creations, revealing the mysterious architectural beauty through its composition and nanostructuring. The present study unveils the compositional mystery of Eumeninae nest through the signal processing of the laser-induced breakdown spectrum (LIBS). The structure, morphological, and optical characterisations of the nest sample shows nanoparticles of oxides of silicon, aluminium, and iron with an optical bandgap of 2.5 eV, giving a fluorescence emission in the blue region upon ultraviolet excitation. Though, the energy dispersive spectroscopic study confirms the major elements present in the sample, the more elements are revealed through LIBS analysis. The intriguing properties of nest is attributed to the elemental compositions - oxygen, silicon, iron, manganese, chromium, cobalt, calcium and carbon - which necessitate deconvolution of peaks in the spectra for estimating the plasma temperature (4300-5045 K) and electron density (1.13 × 10-19 cm-3).


Assuntos
Cromo , Lasers , Cromo/análise , Ferro , Silício , Espectrometria por Raios X
3.
J Hazard Mater ; 423(Pt A): 126975, 2022 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-34788938

RESUMO

Pb(II) contamination imposes serious threats to human health and the environment. Biological reduction of Pb(II) to metallic Pb is an attractive method for the remediation of Pb(II)-contaminated water and sediments. In this study, Pb(II)-reducing microorganisms were isolated by the dilution-to-extinction (DTE) and streak-plate methods. As a result, Delftia acidovorans, Azonexus caeni, and Comamonas testosteroni were successfully isolated. At a high lead concentration (10 mg-Pb(II)/L), each of the isolated D. acidovorans strain Pb11 and A. caeni strain Pb2 cultures showed successful utilization of Pb(II), resulting in a 5.15- and 8.14-fold growth in 3 days, respectively. Pb(II) reduction to metallic Pb by D. acidovorans strain Pb11 and A. caeni strain Pb2 was confirmed using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) was coupled with X-ray photoelectron spectroscopy (XPS). This strategic analysis was necessary to confirm the formation of metallic Pb separately from lead phosphate precipitates which are inevitable in the biological Pb(II) removal experiments. Among the 3 isolated microbes, C. testosteroni strain Pb3 did not leave immobile and detectable Pb solids in SEM-EDS analyses. D. acidovorans and A. caeni are recommended for engineered remediation of Pb(II)-contaminated wastewater and sediments.


Assuntos
Comamonas testosteroni , Chumbo , Adsorção , Bactérias , Humanos , Chumbo/análise , Espectrometria por Raios X , Águas Residuárias
4.
Talanta ; 236: 122871, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635252

RESUMO

Bimetallic nanoparticles (NPs), including core-shell structure and bimetallic alloy nanoparticles, were synthesized and characterized using flow field-flow fractionation (FlFFF), single particle inductively coupled plasma mass spectrometry (SP-ICP-MS), and transmission electron microscope (TEM) with energy-dispersive x-ray spectroscopy (EDS). For the core-shell particles, a nominal 80 nm commercial core-shell AuAg bimetallic nanoparticle was used to examine the applicability of SP-ICP-MS to determine the core size of Au and shell thickness of Ag. Then, the method was applied to estimate the core size of Au and shell thickness of Ag for the laboratory synthesized particles. The results were compared with those obtained from TEM-EDS. For the alloy nanoparticles, two synthesis protocols, based on the galvanic replacement of Ag seed particles with Au, were used. One was to prepare a hollow AgAu particle by varying the volume of dissolved Au in basic solution (K-gold) to etch some parts of AgNPs to dissolved ionic silver with the formation of AuNPs covering the remaining AgNPs, producing a hole inside the core nanoparticles. Another protocol was to prepare AgAu alloy nanoparticles. SP-ICP-MS was used in combination with FlFFF to provide information on the changes of particle size with varying volume of K-gold reagent. Hydrodynamic diameter increased with increasing K-gold, as observed by FlFFF. With SP-ICP-MS without prior FlFFF, bimodal distributions were observed in the size distribution of Au and Ag. With prior FlFFF, monomodal distributions were observed by SP-ICP-MS, which allow the use of particle concentration and size to estimate the mass concentration of elements on the fractionated bimetallic nanoparticles. This study illustrates the potential use of SP-ICP-MS for gaining information about particle transformation during the synthesis of bimetallic nanoparticles.


Assuntos
Ouro , Nanopartículas Metálicas , Espectrometria de Massas , Prata/análise , Espectrometria por Raios X
5.
Environ Pollut ; 292(Pt A): 118324, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34637827

RESUMO

Traditional soil heavy metal (HM) investigation usually costs a lot of human and material resources. In-situ portable X-ray fluorescence spectrometry (PXRF) is a cheap and rapid HM analysis method, but its analysis accuracy is usually affected by spatially non-stationary field environment factors. In this study, residual sequential Gaussian co-simulation (RCoSGS) was first proposed to incorporate both continuous and categorical auxiliary variables for spatial simulation of soil Cu. Next, additional in-situ PXRF sampling sites (n = 300) were allocated in the subareas with high, medium, and low conditional variances in the proportions of 50%, 33.33%, and 16.67%, respectively. Then, robust geographically weighted regression (RGWR) was established to correct the spatially non-stationary effects of field environmental factors on in-situ PXRF and further compared with the traditionally-used multiple linear regression (MLR) and basic GWR in correction accuracy. Finally, RCoSGS with the RGWR-corrected in-situ PXRF as part of hard data (RCoSGS-PXRF) was established and further compared with the model with one or multiple auxiliary variables in the spatial simulation accuracy. Results showed that (i) RCoSGS effectively incorporated both SOM and land-use types and obtained higher spatial simulation accuracy (RI = 37.52%) than residual sequential Gaussian simulation with land-use types (RI = 19.44%) and sequential Gaussian co-simulation with SOM (RI = 20.92%); (ii) RGWR significantly weakened the spatially non-stationary effects of field environmental factors on in-situ PXRF, and RGWR (RI = 58.96%) and GWR (RI = 39.61%) obtained higher correction accuracy than MLR; (iii) the RGWR-corrected in-situ PXRF (RI = 66.57%) brought higher spatial simulation accuracy than both land-use types and SOM (RI = 37.52%); (iv) RCoSGS-PXRF obtained the highest spatial simulation accuracies (RI = 83.74%). Therefore, the proposed method is cost-effective for the rapid and high-precision investigation of soil HMs at a regional scale.


Assuntos
Metais Pesados , Poluentes do Solo , Monitoramento Ambiental , Humanos , Metais Pesados/análise , Solo , Poluentes do Solo/análise , Espectrometria por Raios X , Raios X
6.
Spectrochim Acta A Mol Biomol Spectrosc ; 265: 120260, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34507033

RESUMO

This paper presents the study of selected painted fragments from different contexts of Ostia Antica city, dating between 2nd century BCE and the end of the 1st century CE. The aim is to identify the raw materials used and to understand the execution techniques through a non-invasive protocol including techniques based either on multiband imaging (Visible-VIS, Ultraviolet induced Luminescence - UVL and Visible Induced Luminescence - VIL) and single spot analyses (Fiber Optic Reflectance Spectroscopy- FORS and portable X-Ray Fluorescence spectrometry - XRF). The most representative and interesting fragments were sampled for further studies with laboratory techniques such as optical microscopy (OM) and electron microscopy (SEM), Fourier Transform Infrared and micro-Raman Spectroscopies (FT-IR and µRaman). The extensive use of non-invasive techniques, even working on fragments, is proved to be the most robust and effective approach enabling the analysis of a high number of areas, dramatically increasing the statistical meaning of the collected data. The elaboration of such a huge number of data allows highlighting differences and similarities, thus achieving a more realistic overview of the materials composition and addressing the sampling to the more significant and complex areas.


Assuntos
Pinturas , Pintura , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman
7.
PLoS One ; 16(10): e0258313, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34637464

RESUMO

Particulate matter (PM) is considered the most severe environmental pollution problem due to its serious effects on human health associated with an increased risk of cardiovascular morbidity and mortality. In this work, a physicochemical characterization of PM10 from the city of Medellin was developed. The results evince that lead (Pb) is one of the most abundant elements since it is present in all analyzed samples. Therefore, Pb was chosen to perform an in-silico study to assess its effects on atrial arrhythmias generation. For this purpose, we developed a model representing the Pb2+ blocking effect on the L-type calcium channel. This formulation was incorporated in a human atrial cell mathematical model and in 2D and 3D models of human atria. The simulations showed a proarrhythmic effect at high Pb2+ concentrations, through shortening of action potential duration inducing the generation of reentrant activity and atrial flutter. The results contribute to the knowledge about the cardiac physiopathological processes, triggered by lead as one of the main PM10 metal components of air pollution, that yields the generation of arrhythmias.


Assuntos
Poluição do Ar/análise , Arritmias Cardíacas/etiologia , Simulação por Computador , Átrios do Coração/patologia , Chumbo/efeitos adversos , Material Particulado/efeitos adversos , Potenciais de Ação/fisiologia , Poluentes Atmosféricos , Arritmias Cardíacas/fisiopatologia , Fenômenos Químicos , Átrios do Coração/fisiopatologia , Humanos , Modelos Cardiovasculares , Espectrometria por Raios X
8.
Molecules ; 26(20)2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34684721

RESUMO

Green nanoparticle synthesis is an environmentally friendly approach that uses natural solvents. It is preferred over chemical and physical techniques due to the time and energy savings. This study aimed to synthesize zinc oxide nanoparticles (ZnO NPs) through a green method that used Phlomis leaf extract as an effective reducing agent. The synthesis and characterization of ZnO NPs were confirmed by UV-Vis spectrophotometry, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Dynamic light scattering (DLS), Zeta potential, and Field Emission Scanning Electron Microscope (FESEM) techniques. In vitro cytotoxicity was determined in L929 normal fibroblast cells using MTT assay. The antibacterial activity of ZnO nanoparticles was investigated using a disk-diffusion method against S. aureus and E. coli, as well as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) content concentrations. XRD results confirmed the nanoparticles' crystalline structure. Nanoparticle sizes were found to be around 79 nm by FESEM, whereas the hydrodynamic radius of nanoparticles was estimated to be around 165 ± 3 nm by DLS. FTIR spectra revealed the formation of ZnO bonding and surfactant molecule adsorption on the surface of ZnO NPs. It is interesting to observe that aqueous extracts of Phlomis leave plant are efficient reducing agents for green synthesis of ZnO NPs in vitro, with no cytotoxic effect on L929 normal cells and a significant impact on the bacteria tested.


Assuntos
Química Verde/métodos , Nanopartículas Metálicas/química , Phlomis/metabolismo , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Extratos Vegetais/química , Substâncias Redutoras/farmacologia , Espectrometria por Raios X/métodos , Espectrofotometria Ultravioleta/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Difração de Raios X/métodos , Óxido de Zinco/química
9.
Int J Mol Sci ; 22(19)2021 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-34638905

RESUMO

Silk fibroin has a high potential for use in several approaches for technological and biomedical applications. However, industrial production has been difficult to date due to the lengthy manufacturing process. Thus, this work investigates a novel procedure for the isolation of non-degraded regenerated silk fibroin that significantly reduces the processing time from 52 h for the standard methods to only 4 h. The replacement of the standard degumming protocol by repeated short-term microwave treatments enabled the generation of non-degraded degummed silk fibroin. Subsequently, a ZnCl2 solution was used to completely solubilize the degummed fibroin at only 45 °C with an incubation time of only 1 h. Desalting was performed by gel filtration. Based on these modifications, it was possible to generate a cytocompatible aqueous silk fibroin solution from degummed silk within only 4 h, thus shortening the total process time by 48 h without degrading the quality of the isolated silk fibroin solution.


Assuntos
Bombyx/química , Fibroínas/metabolismo , Pupa/química , Seda/metabolismo , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Eletroforese em Gel de Poliacrilamida/métodos , Fibroínas/farmacologia , Fibroínas/ultraestrutura , Camundongos , Microscopia Eletrônica de Varredura/métodos , Fosfolipídeos/isolamento & purificação , Fosfolipídeos/metabolismo , Reprodutibilidade dos Testes , Seda/farmacologia , Seda/ultraestrutura , Espectrometria por Raios X/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Temperatura , Fatores de Tempo
10.
Talanta ; 235: 122765, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517626

RESUMO

The f-ratio method is a new quantitative X-ray microanalysis method developed based on a cold field emission scanning electron microscope/energy dispersive spectroscopy system. The f-ratio is calculated with the characteristic X-ray intensities, and the Monte Carlo simulation is employed to build the theoretical relation between the system composition and the f-ratio. In this study, the f-ratio model is formulated with the elemental concentrations and the f-ratio coefficients. The f-ratio models in the binary S-Fe system and the ternary O-Al-Si system were studied, and the beam energy effects were investigated. The quantitative analyses were performed on the standard pyrite (FeS2) and kyanite (Al2SiO5) specimens, and the results show that the f-ratio model is able to achieve a satisfying accuracy.


Assuntos
Microanálise por Sonda Eletrônica , Simulação por Computador , Método de Monte Carlo , Espectrometria por Raios X , Raios X
11.
Molecules ; 26(17)2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34500589

RESUMO

The aim of this work was to deeply investigate the structure and properties of electrochemically synthesized silver nanoparticles (AgNPs) through high-resolution techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), Zeta Potential measurements, and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Strong brightness, tendency to generate nanoclusters containing an odd number of atoms, and absence of the free silver ions in solution were observed. The research also highlighted that the chemical and physical properties of the AgNPs seemed to be related to their peculiar oxidative state as suggested by X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRPD) analyses. Finally, the MTT assay tested the low cytotoxicity of the investigated AgNPs.


Assuntos
Química Verde/métodos , Nanopartículas Metálicas/química , Prata/química , Soluções/química , Microscopia Eletrônica de Transmissão/métodos , Espectrometria por Raios X/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Difração de Raios X/métodos
12.
An Acad Bras Cienc ; 93(4): e20200646, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34550165

RESUMO

Portable X-ray fluorescence (pXRF) spectrometry offers valuable information for prediction models of soil fertility attributes spatial variation, although this approach is yet scarce in tropical regions. This study aims to predict and build spatial variability maps of soil pH, remaining phosphorus (P-Rem), soil organic matter (SOM) and sum of bases (SB) using pXRF results through stepwise multiple linear regression (SMLR) and Random Forest (RF) in a highly variable tropical area. Composite samples from soil A horizon were collected at 90 points throughout the campus of the Federal University of Lavras, Minas Gerais, Brazil, for pH, P-Rem, SOM, SB and pXRF analyses. RF predictions showed the highest accuracies, especially for P-Rem and SB (R² values of 0.66 and 0.55, respectively). Attributes that showed higher R² in punctual predictions also exhibited higher R² in spatial predictions. Data obtained from pXRF in tandem with RF can be used to assist prediction models for soil fertility attributes, consequently enabling the digital mapping of such attributes and helping to improve the knowledge about the spatial variability of such attributes in soils of tropical climate. This technique can therefore assist in the identification and orientation of adequate management practices in tropical agricultural practices.


Assuntos
Poluentes do Solo , Solo , Agricultura , Monitoramento Ambiental , Poluentes do Solo/análise , Espectrometria por Raios X
13.
Environ Sci Technol ; 55(19): 13113-13121, 2021 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-34529917

RESUMO

Chronic exposure to inorganic pollutants adversely affects human health. Inductively coupled plasma mass spectrometry (ICP-MS) is the most common method used for trace metal(loid) analysis of human biomarkers. However, it leads to sample destruction, generation of secondary waste, and significant recurring costs. Portable X-ray fluorescence (XRF) instruments can rapidly and nondestructively determine low concentrations of metal(loid)s. In this work, we evaluated the applicability of portable XRF as a rapid method for analyzing trace metal(loid)s in toenail samples from three populations (n = 97) near the city of Chennai, India. A Passing-Bablok regression analysis of results from both methods revealed that there was no proportional bias among the two methods for nickel (measurement range ∼25 to 420 mg/kg), zinc (10 to 890 mg/kg), and lead (0.29 to 4.47 mg/kg). There was a small absolute bias between the two methods. There was a strong proportional bias (slope = 0.253, 95% CI: 0.027, 0.614) between the two methods for arsenic (below detection to 3.8 mg/kg) and for selenium when the concentrations were lower than 2 mg/kg. Limits of agreement between the two methods using Bland-Altman analysis were derived for nickel, zinc, and lead. Overall, a suitably calibrated and evaluated portable XRF shows promise in making high-throughput assessments at population scales.


Assuntos
Chumbo , Unhas , Humanos , Índia , Espectrometria por Raios X , Raios X , Zinco
14.
Molecules ; 26(18)2021 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-34576994

RESUMO

In this study, dark chocolates (DCh) containing zinc lactate (ZnL) were enriched with extracts from elderberries (EFrE), elderflowers (EFlE), and chokeberries (ChFrE) to improve their functional properties. Both dried plant extracts and chocolates were analyzed for antioxidant capacity (AC) using four different analytical methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), cupric ion-reducing antioxidant capacity (CUPRAC), and ferric-reducing antioxidant power (FRAP), while total phenolic content (TPC) was determined by Folin-Ciocalteu (F-C) assay. An increase in antioxidant properties of fortified chocolates was found, and the bioaccessibility of their antioxidants was evaluated. The highest AC and TPC were found in ChFrE and chocolate with chokeberries (DCh + ChFrE) before and after simulated in vitro digestion. Bioaccessibility studies indicated that during the simulated digestion the AC of all chocolates reduced significantly, whereas insignificant differences in TPC results were observed between chemical and physiological extracts. Moreover, the influence of plant extracts on physicochemical parameters such as moisture content (MC), fat content (FC), and viscosity of chocolates was estimated. Furthermore, scanning electron microscopy with dispersive energy spectroscopy (SEM-EDS) was used to analyze surface properties and differences in the chemical composition of chocolates without and with additives.


Assuntos
Antioxidantes/química , Cacau/química , Fenômenos Químicos , Chocolate/análise , Extratos Vegetais/análise , Extratos Vegetais/química , Simulação por Computador , Microscopia Eletrônica de Varredura , Fenóis/análise , Fenóis/química , Photinia/química , Sambucus/química , Espectrometria por Raios X
15.
ACS Appl Mater Interfaces ; 13(33): 39042-39054, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34375073

RESUMO

In developing a cluster-nanocarrier design, as a magnetic resonance imaging contrast agent, we have investigated the enhanced relaxivity of a manganese and iron-oxo cluster grafted within a porous polystyrene nanobead with increased relaxivity due to a higher surface area. The synthesis of the cluster-nanocarrier for the cluster Mn8Fe4O12(O2CC6H4CH═CH2)16(H2O)4, cross-linked with polystyrene (the nanocarrier), under miniemulsion conditions is described. By including a branched hydrophobe, iso-octane, the resulting nanobeads are porous and ∼70 nm in diameter. The increased surface area of the nanobeads compared to nonporous nanobeads leads to an enhancement in relaxivity; r1 increases from 3.8 to 5.2 ± 0.1 mM-1 s-1, and r2 increases from 11.9 to 50.1 ± 4.8 mM-1 s-1, at 9.4 teslas, strengthening the potential for T1 and T2 imaging. Several metrics were used to assess stability, and the porosity produced no reduction in metal stability. Synchrotron X-ray fluorescence microscopy was used to demonstrate that the nanobeads remain intact in vivo. In depth, physicochemical characteristics were determined, including extensive pharmacokinetics, in vivo imaging, and systemic biodistribution analysis.


Assuntos
Materiais Biocompatíveis/química , Meios de Contraste/química , Ferro/química , Manganês/química , Nanopartículas/química , Compostos Organometálicos/química , Poliestirenos/química , Animais , Materiais Biocompatíveis/farmacocinética , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular , Sobrevivência Celular/efeitos dos fármacos , Meios de Contraste/farmacocinética , Reagentes para Ligações Cruzadas/química , Humanos , Imageamento por Ressonância Magnética , Camundongos Endogâmicos BALB C , Imagem Multimodal , Porosidade , Espectrometria por Raios X , Distribuição Tecidual
16.
PLoS One ; 16(8): e0254760, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34347802

RESUMO

Little is known of the properties of the sarsen stones (or silcretes) that comprise the main architecture of Stonehenge. The only studies of rock struck from the monument date from the 19th century, while 20th century investigations have focussed on excavated debris without demonstrating a link to specific megaliths. Here, we present the first comprehensive analysis of sarsen samples taken directly from a Stonehenge megalith (Stone 58, in the centrally placed trilithon horseshoe). We apply state-of-the-art petrographic, mineralogical and geochemical techniques to two cores drilled from the stone during conservation work in 1958. Petrographic analyses demonstrate that Stone 58 is a highly indurated, grain-supported, structureless and texturally mature groundwater silcrete, comprising fine-to-medium grained quartz sand cemented by optically-continuous syntaxial quartz overgrowths. In addition to detrital quartz, trace quantities of silica-rich rock fragments, Fe-oxides/hydroxides and other minerals are present. Cathodoluminescence analyses show that the quartz cement developed as an initial <10 µm thick zone of non-luminescing quartz followed by ~16 separate quartz cement growth zones. Late-stage Fe-oxides/hydroxides and Ti-oxides line and/or infill some pores. Automated mineralogical analyses indicate that the sarsen preserves 7.2 to 9.2 area % porosity as a moderately-connected intergranular network. Geochemical data show that the sarsen is chemically pure, comprising 99.7 wt. % SiO2. The major and trace element chemistry is highly consistent within the stone, with the only magnitude variations being observed in Fe content. Non-quartz accessory minerals within the silcrete host sediments impart a trace element signature distinct from standard sedimentary and other crustal materials. 143Nd/144Nd isotope analyses suggest that these host sediments were likely derived from eroded Mesozoic rocks, and that these Mesozoic rocks incorporated much older Mesoproterozoic material. The chemistry of Stone 58 has been identified recently as representative of 50 of the 52 remaining sarsens at Stonehenge. These results are therefore representative of the main stone type used to build what is arguably the most important Late Neolithic monument in Europe.


Assuntos
Sedimentos Geológicos/química , Automação , Calibragem , Inglaterra , Imageamento Hiperespectral , Processamento de Imagem Assistida por Computador , Isótopos/análise , Minerais/análise , Imagem Óptica , Espectrometria por Raios X , Espectrofotometria Atômica , Tomografia Computadorizada por Raios X , Oligoelementos/análise
17.
Anal Chem ; 93(34): 11660-11668, 2021 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-34403244

RESUMO

An optimized micro-X-ray fluorescence confocal imaging (µXRF-CI) analytical method has been developed to determine the 2D distribution of elemental composition in small (1-3 mm) biological objects at a 10-20 µm spatial resolution. Plants take up chemical elements from soil, and the vascular system transports them toward shoots. In order to obtain biochemical information related to this biological process, 2D distributions of chemical elements in roots and in hypocotyls of cucumber plants were analyzed by synchrotron radiation based on micro-X-ray fluorescence computer tomography and µXRF-CI techniques. The experiments were carried out at HASYLAB Beamline L of the DORIS-III storage ring in Hamburg, a facility that provided optimal physical conditions for developing and performing these unique analyses: high flux monochromatic synchrotron beam, X-ray optical elements, precision moving stages, and silicon drift detectors. New methodological improvements and experimental studies were carried out for applicability of lyophilized samples and cryo-cooling. Experimental parameters were optimized to maximize the excitation yield of arsenic Kα radiation and improvement of the spatial resolution of the µXRF-CI analytical method.


Assuntos
Arsênio , Cucumis sativus , Hipocótilo , Espectrometria por Raios X , Síncrotrons , Raios X
18.
Occup Med (Lond) ; 71(6-7): 298-300, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34455439

RESUMO

We present a 29-year-old non-atopic male apprentice power lineman and recreational cowboy with a case of allergic contact dermatitis due to both occupational and recreational exposure. He presented with a 4-month history of a pruritic, steroid-responsive, intermittent hand, foot and leg dermatitis. Patch testing was positive for chromium, cobalt and a piece of leather from his cowboy boots. His leather work gloves, inner lining of work harness, work boots and cowboy boots were assessed for chromium and cobalt content with handheld fluorescence x-ray spectrometry. Upon replacement of all leather items including the items tested and his leather cowboy saddle, the rash resolved. This case demonstrates the clinical relevance of using a handheld fluorescence x-ray spectrometer to assess for chromium and leather content.


Assuntos
Cromo , Dermatite Alérgica de Contato , Adulto , Cromo/análise , Cobalto/efeitos adversos , Cobalto/análise , Dermatite Alérgica de Contato/diagnóstico , Dermatite Alérgica de Contato/etiologia , Humanos , Masculino , Testes do Emplastro , Espectrometria por Raios X
19.
Nutrients ; 13(8)2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34444730

RESUMO

Micronutrient deficiencies can arise in various conditions, including inflammatory bowel diseases (IBD), and diagnosing these deficiencies can be challenging in the absence of specific clinical signs. The aim of this study was to evaluate the status of various trace elements hair concentration in IBD patients compared to a healthy control group and to identify potential correlations between the micronutrient status and relevant parameters related to disease activity. The concentrations of iron, magnesium, calcium, zinc, copper, manganese, selenium and sulfur in the hair of 37 IBD patients with prior diagnosed IBD (12 Crohn's disease and 25 ulcerative colitis) and 31 healthy controls were evaluated by Energy Dispersive X-Ray spectroscopy (EDX). Significant differences in hair concentration profile of studied trace elements were identified for IBD patients compared to healthy controls. A significantly decreased hair concentration of iron, magnesium, calcium and selenium and a significantly increased sulfur hair concentration were observed in IBD patients at the time of evaluation. A decreased hair calcium concentration (r = -0.772, p = 0.003) and an increased sulfur concentration (r = 0.585, p = 0.046) were significantly correlated with disease activity. Conclusion: Hair mineral and trace elements evaluation may contribute to a proper evaluation of their status in IBD patients and improving the management of nutritional status of IBD patients.


Assuntos
Colite Ulcerativa/metabolismo , Doença de Crohn/metabolismo , Cabelo/química , Micronutrientes/análise , Adulto , Cálcio/análise , Cobre/análise , Feminino , Humanos , Ferro/análise , Magnésio/análise , Masculino , Pessoa de Meia-Idade , Estado Nutricional , Selênio/análise , Espectrometria por Raios X , Enxofre/sangue , Oligoelementos/análise , Zinco/análise
20.
Environ Monit Assess ; 193(8): 490, 2021 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-34258666

RESUMO

Field portable X-ray fluorescence spectroscopy (XRFS) has become increasingly prevalent for in situ detection of trace metals, as it is both rapid and cost effective. The accuracy of in situ XRFS analyses has been questioned due to possible interferences from elevated soil moisture and organic content. In this study, three metal analysis protocols (Cd, Pb, Zn) were compared for surface soil samples collected near the Tar Creek Superfund Site in northeastern Oklahoma. The protocols included the use of a field portable XRF spectrometer for in situ analyses and on homogenized, pulverized, air-dried soil samples sieved to < 250-µm fraction in the laboratory. A subset of soil samples was also analyzed after microwave-assisted hot HNO3 digestion followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) analyses. Moisture content and loss-on-ignition (as a surrogate for organic matter) were determined for each sample. Soil moisture exceeding 10% in situ caused underreporting of field XRF readings when compared to the laboratory XRF readings. Relationships between concentrations determined by laboratory XRFS and ICP-OES for Pb (r2 = 0.96) and Zn (r2 = 0.91) were not statistically different (p < 0.025 for both analytes). A strong relationship between ICP-OES analyses of Zn and Cd (r2 = 0.93) allowed prediction of Cd concentrations for additional samples not analyzed by ICP-OES. This study recommends that XRFS field readings be used for initial screening only and that samples analyzed via field portable XRFS be homogenized, air dried, sieved and re-analyzed in the laboratory to yield the most accurate results.


Assuntos
Poluentes do Solo , Solo , Monitoramento Ambiental , Mineração , Oklahoma , Poluentes do Solo/análise , Espectrometria por Raios X
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