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1.
Biomed Eng Online ; 20(1): 28, 2021 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-33743713

RESUMEN

BACKGROUND: The structural changes of gastric mucosa are considered as an important window of early gastric lesions. This article shows an imaging method of the stomach that does not use imaging agents. X-ray phase-contrast images of different stages of gastric development were taken using micrometer level X-ray in-line phase-contrast imaging (XILPCI) technique on synchrotron radiation facility. The aim of the study was to demonstrate that the imaging technique is an appropriate method for micron imaging of the gastric structures. METHODS: The stomachs of 4-, 6- and 12-week-old rats were removed and cleaned. XILPCI has 1000 times greater soft tissue contrast than that of X-ray traditional absorption radiography. The projection images of the rats stomachs were recorded by an XILPCI charge coupled device (CCD) at 9-µm image resolution. RESULTS: The X-ray in-line phase-contrast images of the different stages of rats' gastric specimens clearly showed the gastric architectures and the details of the gastro-duodenal region. 3-dimensional (3D) stomach anatomical structure images were reconstruction. CONCLUSION: The reconstructed gastric 3D images can clearly display the internal structure of the stomach. XILPCI may be a useful method for medical research in the future.


Asunto(s)
Estómago/diagnóstico por imagen , Sincrotrones , Animales , Artefactos , Procesamiento de Imagen Asistido por Computador , Imagenología Tridimensional , Masculino , Microscopía de Contraste de Fase , Radiografía , Ratas , Tomografía Computarizada por Rayos X , Rayos X
2.
Sci Total Environ ; 768: 144604, 2021 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-33444867

RESUMEN

Fe-modified biochar (FeBC) has been considered for aqueous hexavalent chromium (Cr(VI)) removal, but a better understanding is needed with respect to the removal behavior, chemical processes, and removal mechanisms under aerobic and anaerobic conditions. Aqueous Cr(VI) removal was evaluated using unmodified (BC) and FeBC. The Cr(VI) was completely removed in a pH range of 2-10. The removal behavior was properly depicted using pseudo-second-order (PSO) and Langmuir models under aerobic conditions, and using PSO and Freundlich models under anaerobic conditions. Removal rate and capacity were enhanced by up to 3.8 times under anaerobic conditions. Desorption experiments indicated removed Cr in FeBC was stable except under strong acid condition. X-ray absorption spectroscopy (XAS) analysis suggested removed Cr in FeBC was 100% in Cr(III) form and bound to Fe with a bond length of 3.01 Å in the stable form of Fe(III)nCr(III)(1-n)(OOH). The removal mechanisms of Cr(VI) under aerobic conditions by FeBC mainly included electrostatic adsorption, chemical reduction, and complex precipitation.


Asunto(s)
Sincrotrones , Contaminantes Químicos del Agua , Adsorción , Anaerobiosis , Carbón Orgánico , Cromo/análisis , Compuestos Férricos , Contaminantes Químicos del Agua/análisis
3.
Chemosphere ; 270: 129388, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33423005

RESUMEN

Auriferous sulphide ores often incorporate micro-fine (or invisible) gold and silver particles in a manner making their extraction difficult. Nobel metals are lost in the tailings due to the refractory nature of these ores. Bioleaching is an environment-friendly alternative to the commonly used and toxic cyanidation protocols for gold extraction from refractory ores. In this paper, we investigate gold and silver bioleaching from porphyry and epithermal mineralisation systems, using iron-oxidizing bacteria Acidithiobacillus ferrooxidans. The invisible Au, sequestered in refractory ores, was characterised in situ by synchrotron micro X-Ray Fluorescence (SR-µ-XRF) and X-ray Absorption Spectroscopy (XAS), offering information on Au unaltered speciation at the atomistic level within the ore matrices and at a micro-scale spatial resolution. The SR-µ-XRF and XAS results showed that 10-20 µm sized elemental Au(0) nuggets are sequestered in pyrite, chalcopyrite, arsenopyrite matrices and at the interface of a mixture of pyrite and chalcopyrite. Moreover, the preliminary bioleaching experiments of the two types of ores, showed that Acidithiobacillus ferrooxidans can catalyse the dissolution of natural heterogeneous Fe-rich geo-matrices, sequestering Au and Ag and releasing particulate phases or partially solubilising them within 60 days. These results provide an understanding of noble metal sequestration and speciation within natural ores and a demonstration of the application of synchrotron-based micro-analysis in characterizing economic trace metals in major mineral structures. This work is a contribution to the ongoing efforts towards finding feasible and greener solutions of noble metal extraction protocols.


Asunto(s)
Acidithiobacillus , Sincrotrones , Cobre , Metales , Espectroscopía de Absorción de Rayos X
4.
Am J Physiol Heart Circ Physiol ; 320(3): H1021-H1036, 2021 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-33481696

RESUMEN

Pulmonary hypertension (PH) causes cardiac hypertrophy in the right ventricle (RV) and eventually leads to RV failure due to persistently elevated ventricular afterload. We hypothesized that the mechanical stress on the RV associated with increased afterload impairs vasodilator function of the right coronary artery (RCA) in PH. Coronary vascular response was assessed using microangiography with synchrotron radiation (SR) in two well-established PH rat models, monocrotaline injection or the combined exposure to chronic hypoxia and vascular endothelial growth factor receptor blockade with Su5416 (SuHx model). In the SuHx model, the effect of the treatment with the nonselective endothelin-1 receptor antagonist (ERA), macitentan, was also examined. Myocardial viability was determined in SuHx model rats, using 18F-FDG Positron emission tomography (PET) and magnetic resonance imaging (MRI). Endothelium-dependent and endothelium-independent vasodilator responses were significantly attenuated in the medium and small arteries of severe PH rats. ERA treatment significantly improved RCA vascular function compared with the untreated group. ERA treatment improved both the decrease in ejection fraction and the increased glucose uptake, and reduced RV remodeling. In addition, the upregulation of inflammatory genes in the RV was almost suppressed by ERA treatment. We found impairment of vasodilator responses in the RCA of severe PH rat models. Endothelin-1 activation in the RCA plays a major role in impaired vascular function in PH rats and is partially restored by ERA treatment. Treatment of PH with ERA may improve RV function in part by indirectly attenuating right heart afterload and in part by associated improvements in right coronary endothelial function.NEW & NOTEWORTHY We demonstrated for the first time the impairment of vascular responses in the right coronary artery (RCA) of the dysfunctional right heart in pulmonary hypertensive rats in vivo. Treatment with an endothelin-1 receptor antagonist ameliorated vascular dysfunction in the RCA, enabled tissue remodeling of the right heart, and improved cardiac function. Our results suggest that impaired RCA function might also contribute to the early progression to heart failure in patients with severe pulmonary arterial hypertension (PAH). The endothelium of the coronary vasculature might be considered as a potential target in treatments to prevent heart failure in severe patients with PAH.


Asunto(s)
Angiografía Coronaria , Vasos Coronarios/diagnóstico por imagen , Hipertrofia Ventricular Derecha/diagnóstico por imagen , Hipertensión Arterial Pulmonar/diagnóstico por imagen , Sincrotrones , Vasodilatación , Disfunción Ventricular Derecha/diagnóstico por imagen , Animales , Antihipertensivos/farmacología , Vasos Coronarios/efectos de los fármacos , Vasos Coronarios/metabolismo , Vasos Coronarios/fisiopatología , Modelos Animales de Enfermedad , Antagonistas de los Receptores de Endotelina/farmacología , Endotelina-1/genética , Endotelina-1/metabolismo , Hipertrofia Ventricular Derecha/tratamiento farmacológico , Hipertrofia Ventricular Derecha/metabolismo , Hipertrofia Ventricular Derecha/fisiopatología , Hipoxia/complicaciones , Indoles , Monocrotalina , Valor Predictivo de las Pruebas , Hipertensión Arterial Pulmonar/tratamiento farmacológico , Hipertensión Arterial Pulmonar/metabolismo , Hipertensión Arterial Pulmonar/fisiopatología , Pirimidinas/farmacología , Pirroles , Ratas Sprague-Dawley , Índice de Severidad de la Enfermedad , Sulfonamidas/farmacología , Vasodilatación/efectos de los fármacos , Disfunción Ventricular Derecha/tratamiento farmacológico , Disfunción Ventricular Derecha/metabolismo , Disfunción Ventricular Derecha/fisiopatología , Función Ventricular Derecha , Remodelación Ventricular
5.
Anal Chem ; 93(3): 1237-1241, 2021 01 26.
Artículo en Inglés | MEDLINE | ID: mdl-33378151

RESUMEN

The development of three-dimensional (3D) single-cell imaging and protein quantitative methods can provide more comprehensive information for diagnoses. We report the design and synthesis of a multisignal nanoprobe (AuGdNC@BSA-CV) for single-cell 3D imaging and quantifying the integrin αIIbß3 using correlated synchrotron radiation soft X-ray tomography microscopy and an iterative tomographic algorithm termed equally sloped tomography for the first time. Moreover, on the basis of the Au or Gd content of our nanoprobe, the number of integrin αIIbß3 on a single cell also can be accurately quantified (1.5 × 107 per cell) via inductively coupled plasma mass spectrometry.


Asunto(s)
Imagenología Tridimensional , Integrinas/análisis , Nanopartículas/química , Análisis de la Célula Individual , Tomografía Computarizada por Rayos X , Línea Celular Tumoral , Gadolinio/química , Oro/química , Humanos , Albúmina Sérica Bovina/química , Sincrotrones
6.
Radiat Res ; 194(6): 698-706, 2020 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-33348374

RESUMEN

Spatially fractionated radiation therapy (SFRT) has been based on the delivery of a single high-dose fraction to a large treatment area that has been divided into several smaller fields, reducing the overall toxicity and adverse effects. Complementary microbeam studies have also shown an effective tissue-sparing effect (TSE) in various tissue types and species after spatially fractionated irradiation at the microscale level; however, the underlying biological mechanism remains elusive. In the current study, using the combination of an ex vivo mouse spermatogenesis model and high-precision X-ray microbeams, we revealed the significant TSE for maintaining spermatogenesis after spatially fractionated microbeam irradiation. We used the following ratios of the irradiated to nonirradiated areas: 50:50, 150:50 and 350:50 µm-slit, where approximately 50, 75 and 87.5% of the sample was irradiated (using center-to-center distances of 100, 200 and 400 µm, respectively). We found that the 50 and 75% micro-slit irradiated testicular tissues showed an almost unadulterated TSE for spermatogenesis, whereas the 87.5% micro-slit irradiated tissues showed an incomplete TSE. This suggests that the TSE efficiency for spermatogenesis is dependent on the size of the nonirradiated spermatogonial stem cell pool in the irradiated testicular tissues. In addition, there would be a spatiotemporal limitation of stem cell migration/competition, resulting in the insufficient TSE for 87.5% micro-slit irradiated tissues. These stem cell characteristics are essential for the accurate prediction of tissue-level responses during or after SFRT, indicating the clinical potential for achieving better outcomes while preventing adverse effects.


Asunto(s)
Fraccionamiento de la Dosis de Radiación , Espermatogénesis/efectos de la radiación , Animales , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos ICR , Ratones Transgénicos , Sincrotrones
7.
Elife ; 92020 12 15.
Artículo en Inglés | MEDLINE | ID: mdl-33317696

RESUMEN

The ontogenetic trajectory of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically most basal stem osteichthyan, visualized by synchrotron microtomography, reveals a developmental relationship between teeth and dermal odontodes that is not evident from the adult morphology. The earliest odontodes are two longitudinal founder ridges formed at the ossification center. Subsequent odontodes that are added lingually to the ridges turn into conical teeth and undergo cyclic replacement, while those added labially achieve a stellate appearance. Stellate odontodes deposited directly on the bony plate are aligned with the alternate files of teeth, whereas new tooth positions are inserted into the files of sequential addition when a gap appears. Successive teeth and overgrowing odontodes show hybrid morphologies around the oral-dermal boundary, suggesting signal cross-communication. We propose that teeth and dermal odontodes are modifications of a single system, regulated and differentiated by the oral and dermal epithelia.


Asunto(s)
Evolución Biológica , Dentición , Peces/anatomía & histología , Fósiles , Odontogénesis , Piel/anatomía & histología , Diente/anatomía & histología , Animales , Filogenia , Piel/diagnóstico por imagen , Sincrotrones , Diente/diagnóstico por imagen , Microtomografía por Rayos X
8.
J Vis Exp ; (163)2020 09 23.
Artículo en Inglés | MEDLINE | ID: mdl-33044452

RESUMEN

A facility for performing serial crystallography measurements has been developed at the Australian synchrotron. This facility incorporates a purpose built high viscous injector, Lipidico, as part of the macromolecular crystallography (MX2) beamline to measure large numbers of small crystals at room temperature. The goal of this technique is to enable crystals to be grown/transferred to glass syringes to be used directly in the injector for serial crystallography data collection. The advantages of this injector include the ability to respond rapidly to changes in the flow rate without interruption of the stream. Several limitations for this high viscosity injector (HVI) exist which include a restriction on the allowed sample viscosities to >10 Pa.s. Stream stability can also potentially be an issue depending on the specific properties of the sample. A detailed protocol for how to set up samples and operate the injector for serial crystallography measurements at the Australian synchrotron is presented here. The method demonstrates preparation of the sample, including the transfer of lysozyme crystals into a high viscous media (silicone grease), and the operation of the injector for data collection at MX2.


Asunto(s)
Cristalografía por Rayos X/métodos , Sincrotrones , Viscosidad/efectos de los fármacos , Australia , Inyecciones
9.
J Environ Qual ; 49(1): 184-193, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33016369

RESUMEN

Phosphorus deficiency and excess are concomitant problems in agricultural soils of the mid-Atlantic region. A fundamental understanding of soil P speciation is essential to assess P fate and transport in these soils. Current methods for soil P speciation often rely on sequential chemical extractions, which can introduce artifacts during analysis. To overcome limitations of current methods, this study evaluated synchrotron-based micro-focused X-ray fluorescence (µ-XRF) and X-ray absorption near-edge spectroscopy (µ-XANES) techniques to assess soil P speciation in agricultural soils collected from the mid-Atlantic region of the United States. Three soils with varying chemical and physical properties were analyzed with µ-XRF maps collected at high (12,000 eV) and tender (2240 eV) energies to evaluate colocation of P with Fe, Al, Ca, and Si in soil samples, and µ-XANES spectra were collected at the P K-edge for P hotspots. Combined µ-XRF and µ-XANES analysis was useful for identifying Ca phosphate, Fe phosphate, Al-sorbed P, and Fe-sorbed P species in heterogeneous soil samples. X-ray fluorescence maps were valuable to distinguish Al-oxide sorbed P from Fe-oxide sorbed P species. A low signal-to-noise ratio often limited µ-XANES data collection in regions with diffuse, low concentrations of P. Therefore, some P species may not have been detected during analysis. Even with varying degrees of self-absorption and signal-to-noise ratios in µ-XANES spectra, important inferences regarding P speciation in mid-Atlantic soils were made. This study highlights the potential of µ-XANES analysis for use in environmental and agricultural sciences to provide insights into P fate and transport in soils.


Asunto(s)
Contaminantes del Suelo/análisis , Suelo , Fósforo , Sincrotrones , Espectroscopía de Absorción de Rayos X
10.
Int J Nanomedicine ; 15: 5289-5298, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32821095

RESUMEN

Background: Type I collagen is the major component of the extracellular matrix of the knee's meniscus and plays a central role in that joint's biomechanical properties. Repair and reconstruction of tissue damage often requires a scaffold to assist the body to rebuild. The middle zone of bovine meniscus is a material that may be useful for the preparation of extracellular matrix scaffolds. Methods: Here, synchrotron-based small-angle X-ray scattering (SAXS) patterns of bovine meniscus were collected during unconfined compression. Collagen fibril orientation, D-spacing, compression distance and force were measured. Results: The collagen fibrils in middle zone meniscal fibrocartilage become more highly oriented perpendicular to the direction of compression. The D-spacing also increases, from 65.0 to 66.3 nm with compression up to 0.43 MPa, representing a 1.8% elongation of collagen fibrils perpendicular to the compression. Conclusion: The elasticity of the collagen fibrils under tension along their length when the meniscus is compressed, therefore, contributes to the overall elastic response of the meniscus only under loads that exceed those likely to be experienced physiologically.


Asunto(s)
Colágeno/química , Meniscos Tibiales/química , Meniscos Tibiales/fisiología , Animales , Fenómenos Biomecánicos , Bovinos , Colágeno/metabolismo , Colágeno Tipo I/química , Colágeno Tipo I/metabolismo , Elasticidad , Masculino , Dispersión del Ángulo Pequeño , Estrés Mecánico , Sincrotrones , Difracción de Rayos X
11.
Chemosphere ; 260: 127577, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32758784

RESUMEN

Tungsten (W) occurrence and speciation was investigated in sediments collected from Fallon, Nevada where previous studies have linked elevated W levels in human body fluids to an unusual cluster of childhood leukemia cases. The speciation of sedimentary W was determined by µ-XRF mapping and µ-XANES. The W content of the analyzed surface sediments ranged between 81 and 25,908 mg/kg, which is significantly higher than the W content in deeper sediments which ranged from 37 to 373 mg/kg at 30 cm depth. The µ-XANES findings reveal that approximately 20-50% of the total W in the shallow sediment occurs in the metallic form (W0); the rest occurs in the oxide form (WVIO3). Because W0 does not occur naturally, its elevated concentrations in surface sediments point toward a possible local anthropogenic origin. The oxidation of metallic W0 with meteoric waters likely leads to the formation of WVIO3. The chief water-soluble W species was identified as WO42- by chromatographic separation and speciation modeling. These results led us to postulate that W0 particles from a currently unknown but local source(s) is (are) deposited onto the soils and/or surface sediments. The W0 in interaction with meteoric water is oxidized to WVIO3, and as these sediment-water interactions progress, WO42- is formed in the water at pH ∼7. Under pH < 7, and sufficient W concentrations, tungstate tends to polymerize, and polymerized species are less likely to adsorb onto sediments. Polymerized species have lower affinity than monomers, which leads to enhanced mobility of W.


Asunto(s)
Sedimentos Geológicos/química , Tungsteno/química , Adsorción , Concentración de Iones de Hidrógeno , Nevada , Suelo/química , Sincrotrones , Compuestos de Tungsteno/química , Espectroscopía de Absorción de Rayos X
12.
Environ Sci Pollut Res Int ; 27(33): 42168-42174, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32860190

RESUMEN

Brominated flame retardants (BFRs) are commonly used in consumer products and they shed off these products and eventually build up in household dust. Polybrominated diphenyl ethers (PBDEs), in particular, are known endocrine-disrupting chemicals affecting various hormone syntheses. Portable X-ray fluorescence spectroscopy (XRF) is the most common non-destructive method in identifying BFRs in environmental samples. However, the method is insensitive to bromine speciation. Synchrotron-based XRF has been shown to have very low detection limits (< 1 µg/g) that is suitable for detecting BFRs and can be combined with X-ray absorption near-edge spectroscopy (XANES) to identify the bromine species present in the household dust. Twenty indoor dust samples were collected from rural homes in Newfoundland (Canada) to assess the use of synchrotron-based techniques to identify BFRs. Synchrotron-based XRF analysis identified bromine in all the samples, with concentrations ranging from 2-19 µg/g. XANES analysis identified organic-based bromine species in several samples that are likely BFRs based on the spectral line shape. The accuracy of using XANES to identify BFRs is highly dependent on the source and size of the dust samples. Therefore, for future research, it is important to take into account the sources of dust sample and to focus on fine dust particles.


Asunto(s)
Contaminación del Aire Interior , Retardadores de Llama , Hidrocarburos Bromados , Contaminación del Aire Interior/análisis , Canadá , Polvo/análisis , Monitoreo del Ambiente , Retardadores de Llama/análisis , Éteres Difenilos Halogenados/análisis , Hidrocarburos Bromados/análisis , Terranova y Labrador , Sincrotrones , Rayos X
13.
J Vis Exp ; (160)2020 06 18.
Artículo en Inglés | MEDLINE | ID: mdl-32628166

RESUMEN

The externally-heated diamond anvil cell (EHDAC) can be used to generate simultaneously high-pressure and high-temperature conditions found in Earth's and planetary interiors. Here we describe the design and fabrication of the EHDAC assemblies and accessories, including ring resistive heaters, thermal and electrical insulating layers, thermocouple placement, as well as the experimental protocol for preparing the EHDAC using these parts. The EHDAC can be routinely used to generate megabar pressures and up to 900 K temperatures in open air, and potentially higher temperatures up to ~1200 K with a protective atmosphere (i.e., Ar mixed with 1% H2). Compared with a laser-heating method for reaching temperatures typically >1100 K, external heating can be easily implemented and provide a more stable temperature at ≤900 K and less temperature gradients to the sample. We showcased the application of the EHDAC for synthesis of single crystal ice-VII and studied its single-crystal elastic properties using synchrotron-based X-ray diffraction and Brillouin scattering at simultaneously high-pressure high-temperature conditions.


Asunto(s)
Diamante/química , Elasticidad , Hielo/análisis , Presión , Temperatura , Cerámica/química , Cristalización , Análisis Espectral , Sincrotrones , Difracción de Rayos X
14.
Science ; 369(6500): 211-216, 2020 07 10.
Artículo en Inglés | MEDLINE | ID: mdl-32647004

RESUMEN

The dentitions of extant fishes and land vertebrates vary in both pattern and type of tooth replacement. It has been argued that the common ancestral condition likely resembles the nonmarginal, radially arranged tooth files of arthrodires, an early group of armoured fishes. We used synchrotron microtomography to describe the fossil dentitions of so-called acanthothoracids, the most phylogenetically basal jawed vertebrates with teeth, belonging to the genera Radotina, Kosoraspis, and Tlamaspis (from the Early Devonian of the Czech Republic). Their dentitions differ fundamentally from those of arthrodires; they are marginal, carried by a cheekbone or a series of short dermal bones along the jaw edges, and teeth are added lingually as is the case in many chondrichthyans (cartilaginous fishes) and osteichthyans (bony fishes and tetrapods). We propose these characteristics as ancestral for all jawed vertebrates.


Asunto(s)
Evolución Biológica , Dentición , Maxilares/anatomía & histología , Vertebrados/anatomía & histología , Vertebrados/clasificación , Animales , República Checa , Tomografía con Microscopio Electrónico , Fósiles , Filogenia , Sincrotrones , Diente/anatomía & histología
15.
Phys Med Biol ; 65(16): 16TR01, 2020 08 31.
Artículo en Inglés | MEDLINE | ID: mdl-32604077

RESUMEN

Semiconductor dosimeters are ubiquitous in modern external-beam radiation therapy. They possess key features. The response, electronically available in real time, is stable and linear with absorbed dose for given irradiation conditions; the radiation-sensitive volume can be rather small in size, while retaining mechanical strength and high sensitivity. We describe three common semiconductor dosimeters: diodes, metal-oxide-semiconductor field-effect transistors and diamonds. We discuss in detail their operation principles and applications in modern external-beam radiation therapy, primarily with megavoltage photon beams. We also explore their use in proton and heavy ion therapy, and in experimental radiotherapy techniques such as synchrotron-based micro-beam radiation therapy.


Asunto(s)
Dosímetros de Radiación/normas , Radiometría/métodos , Radiometría/normas , Planificación de la Radioterapia Asistida por Computador/normas , Semiconductores , Sincrotrones/normas , Humanos , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/métodos , Sincrotrones/instrumentación
16.
J Vis Exp ; (160)2020 06 12.
Artículo en Inglés | MEDLINE | ID: mdl-32597861

RESUMEN

Bone is a dynamic and mechanically active tissue that changes in structure over the human lifespan. The products of the bone remodeling process have been studied substantially using traditional two-dimensional techniques. Recent advancements in X-ray imaging technology via desktop micro-computed tomography (µCT) and synchrotron radiation micro-computed tomography (SRµCT) have allowed for the acquisition of high-resolution three-dimensional (3D) scans of a larger field of view (FOV) than other 3D imaging techniques (e.g., SEM) providing a more complete picture of microscopic structures within human cortical bone. The specimen should be accurately centered within the FOV, however, to limit the appearance of streak artifacts known to impact data analysis. Previous studies have reported procurement of irregularly shaped rectilinear bone blocks that result in imaging artifacts due to uneven edges or image truncation. We have applied a geological sampling protocol (coring) to procure consistently sized cortical bone core specimens for SRµCT experiments from the anterior aspect of human femora. This coring method is efficient and minimally destructive to tissue. It creates uniform cylindrical samples that decrease imaging artifacts by nature of being isometric during rotation and providing a uniform path length for X-ray beams throughout scanning. Image processing of X-ray tomographic data of cored and irregularly shaped samples confirms the potential of the technique to improve visualization and analysis of cortical bone microarchitecture. A goal of this protocol is to deliver a reliable and repeatable method for the extraction of cortical bone cores that is adaptable for various types of high-resolution bone imaging experiments. An overarching goal of the work is to create a standardized cortical bone procurement for SRµCT that is affordable, consistent, and straightforward. This procedure may further be adapted by researchers in related fields who commonly evaluate hard composite materials such as in biological anthropology, geosciences, or material sciences.


Asunto(s)
Hueso Cortical/anatomía & histología , Procesamiento de Imagen Asistido por Computador , Sincrotrones , Microtomografía por Rayos X , Fémur/anatomía & histología , Humanos , Imagenología Tridimensional
17.
Environ Pollut ; 265(Pt A): 115002, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32563950

RESUMEN

Mercury (Hg) is commonly extracted from solid phase samples using aqua regia for total Hg (tHg) analysis. However, uncertainties exist regarding the complete extraction of Hg by aqua regia, especially from carbonaceous materials. To investigate whether aqua regia can completely extract Hg from biochars, batch-style experiments were carried out to evaluate extraction efficiency of aqua regia with respect to Hg-loaded biochar and to characterize the residual Hg speciation and spatial distribution. Different types of biochars (raw, FeCl3-modified, and FeSO4-modified, prepared at different temperatures) were reacted with Hg-spiked solution before the digestion experiments. Adsorption analyses indicate the biochars were successfully loaded with Hg and that the Hg content was higher in biochars pyrolyzed at higher temperature (900 versus 300 or 600 °C). The results of digestion experiments indicate Hg could not be completely extracted from the biochars tested, with a greater percentage of residual Hg in biochars pyrolyzed at 600 (60 ± 15%) and 900 (75 ± 22%) than 300 °C (7 ± 2%). Furthermore, the fraction of residual Hg in FeSO4-modified biochars after aqua regia digestion was significantly lower than in FeCl3-modified and unmodified biochars. Confocal micro-X-ray fluorescence imaging (CMXRFI) showed residual Hg in biochars is concentrated on surfaces prior to digestion, but more homogeneously distributed after digestion, which indicates Hg on biochar surface is more easily digested. Hg extended X-ray absorption fine structure (EXAFS) spectra modelling showed residual Hg in biochars mainly exists as Hg(II)-Cl. These results indicate extra caution should be paid for tHg determinations using aqua regia digestion method in soil (especially in forest), sediment, and peat samples containing black carbon, activated carbon, or biochar.


Asunto(s)
Carbón Orgánico , Mercurio , Adsorción , Ácido Clorhídrico , Ácido Nítrico , Extractos Vegetales , Sincrotrones
18.
Waste Manag ; 113: 80-87, 2020 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-32505978

RESUMEN

Biogas residues (BR) contaminated with potentially toxic metals pose environmental risks to soils and food chains, and strategies are needed to decrease the concentration and bioavailability of potentially toxic metals in BR. Here, metal fractions and removal mechanisms were quantified by synchrotron radiation-based Fourier transform infrared and micro X-ray fluorescence spectromicroscopies on BR and earthworms subject to vermicomposting. Vermicomposting resulted in decreases in concentrations of potentially toxic metals in BR and increases in metal removal efficiencies due to uptake by earthworms. Prior to vermicomposting, Zn, Cu and Pb were associated with N-H, O-H, aromatic C, aliphatic C, and amide functional groups, but following maturation during vermicomposting, metals were associated with N-H, O-H, aliphatic C and polysaccharide functional groups. Following vermicomposting, Zn and Cu were mainly distributed in the dermal portions of earthworms, whereas Pb was more homogeneously distributed among the inner and outer portions of the earthworms, revealing that different metals may have different uptake routes. These findings provide a new strategy for safe utilization of BR by using earthworms via vermicomposting to remove potentially toxic metals and in situ insights into how metals binding and distribution characteristics in BR and earthworms during compost and vermicomposting processes.


Asunto(s)
Metales Pesados/análisis , Oligoquetos , Contaminantes del Suelo/análisis , Animales , Biocombustibles , Suelo , Sincrotrones
19.
Sci Rep ; 10(1): 8833, 2020 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-32483249

RESUMEN

Synchrotron facilities produce ultra-high dose rate X-rays that can be used for selective cancer treatment when combined with micron-sized beams. Synchrotron microbeam radiation therapy (MRT) has been shown to inhibit cancer growth in small animals, whilst preserving healthy tissue function. However, the underlying mechanisms that produce successful MRT outcomes are not well understood, either in vitro or in vivo. This study provides new insights into the relationships between dosimetry, radiation transport simulations, in vitro cell response, and pre-clinical brain cancer survival using intracerebral gliosarcoma (9LGS) bearing rats. As part of this ground-breaking research, a new image-guided MRT technique was implemented for accurate tumor targeting combined with a pioneering assessment of tumor dose-coverage; an essential parameter for clinical radiotherapy. Based on the results of our study, we can now (for the first time) present clear and reproducible relationships between the in vitro cell response, tumor dose-volume coverage and survival post MRT irradiation of an aggressive and radioresistant brain cancer in a rodent model. Our innovative and interdisciplinary approach is illustrated by the results of the first long-term MRT pre-clinical trial in Australia. Implementing personalized synchrotron MRT for brain cancer treatment will advance this international research effort towards clinical trials.


Asunto(s)
Neoplasias Encefálicas/radioterapia , Gliosarcoma/radioterapia , Animales , Encéfalo/patología , Encéfalo/efectos de la radiación , Neoplasias Encefálicas/mortalidad , Neoplasias Encefálicas/patología , Modelos Animales de Enfermedad , Gliosarcoma/mortalidad , Gliosarcoma/patología , Masculino , Ratas , Ratas Endogámicas F344 , Tasa de Supervivencia , Sincrotrones , Microtomografía por Rayos X , Rayos X
20.
Pharm Res ; 37(6): 97, 2020 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-32409985

RESUMEN

PURPOSE: Subcutaneously or intramuscularly administered biodegradable microsphere formulations have been successfully exploited in the management of chronic conditions for over two decades, yet mechanistic understanding of the impact of formulation attributes on in vivo absorption rate from such systems is still in its infancy. METHODS: Suspension formulation physicochemical attributes may impact particulate deposition in subcutaneous (s.c.) tissue. Hence, the utility of synchrotron X-ray micro-computed tomography (µCT) for assessment of spatial distribution of suspension formulation components (PLG microspheres and vehicle) was evaluated in a porcine s.c. tissue model. Optical imaging of dyed vehicle and subsequent microscopic assessment of microsphere deposition was performed in parallel to compare the two approaches. RESULTS: Our findings demonstrate that synchrotron µCT can be applied to the assessment of microsphere and vehicle distribution in s.c. tissue, and that microspheres can also be visualised in the absence of contrast agent using this approach. The technique was deemed superior to optical imaging of macrotomy for the characterisation of microsphere deposition owing to its non-invasive nature and relatively rapid data acquisition time. CONCLUSIONS: The method outlined in this study provides a proof of concept feasibility for µCT application to determining the vehicle and suspended PLG microspheres fate following s.c. injection. A potential application for our findings is understanding the impact of injection, device and formulation variables on initial and temporal depot geometry in pre-clinical or ex-vivo models that can inform product design. Graphical abstract.


Asunto(s)
Materiales Biocompatibles/química , Medios de Contraste/química , Microesferas , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/química , Suspensiones/química , Tomografía Computarizada por Rayos X/métodos , Animales , Composición de Medicamentos , Imagenología Tridimensional , Inyecciones Subcutáneas , Intensificación de Imagen Radiográfica , Porcinos , Sincrotrones , Andamios del Tejido/química
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