1,721,008 research outputs found
Dataset - Nanoparticulated Bimodal Contrast Agent for Ultra-High-Field Magnetic Resonance Imaging and Spectral X-ray Computed Tomography
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Fig 1
F1b: Size histogram of Ba40Dy60 NPs
F1c: EDX spectrum of Ba40Dy60 NPs
F1e: Size histogram of Ba51Dy49 NPs
F1f: F1c: EDX spectrum of Ba51Dy49 NPs
Fig 2
F2: Experimental XRD patterns of Ba40Dy60 and Ba51Dy49 samples
Fig 3
F3b: XRD patterns of the precipitates obtained in the conditions used for the synthesis of Ba51Dy49 NPs but using different aging times
F3c: Unit cell parameters and Ba/(Ba+Dy) ratio of the precipitates versus aging time
Fig 4
F4a: DLS intensity curves of the Ba51Dy49 NPs suspended in water after different periods of time at rest
F4b: FTIR spectrum of the Ba51Dy49 NPs
Fig 5
F5g: Total number of cells per well after exposure to increasing concentration of NPs
F5h: Percentage of dead cells after exposure to increasing concentration of Ba51Dy49 NPs.
F5i: MTT assay of cells exposed to increasing concentration of Ba51Dy49 NPs
Fig 6
F6a: 1/T2 values obtained in aqueous suspensions of Ba51Dy49 NPs at 9.4 T and 1.44 T versus Dy concentration of the suspensions
Fig 7
F7b: X-ray attenuation at 80 kVp, in Hounsfield Units (HU), of aqueous suspensions containing Ba51Dy49 NPs and Iohexol, versus suspension concentration.
F7c: X-ray attenuation, in HU, of aqueous suspensions containing 20.0 mg·mL-1 of Ba51Dy49 and DyF3 NPs, versus working voltageBimodal medical imaging based on Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) is a well-known strategy to increase diagnostic accuracy.
The most recent advances in MRI and CT instrumentation are related to the use of ultrahigh magnetic fields (UHF-MRI) and different working voltages (spectral CT), respectively.
Such advances require the parallel development of bimodal contrast agents (CAs) that are efficient under the new instrumental conditions. In this work, we have synthesized, through
a precipitation reaction from a glycerol solution of the precursors, uniform barium dysprosium fluoride nanospheres with cubic fluorite structure, whose size was found to depend on the Ba/(Ba+Dy)
ratio of the starting solution. Moreover, irrespective of the starting Ba/(Ba+Dy) ratio, the experimental Ba/(Ba+Dy) values were always lower than those used in the starting solutions.
This result was assigned to a lower precipitation kinetics of barium fluoride compared to dysprosium fluoride, as inferred from the detailed analysis of the effect of reaction time on the chemical composition of the precipitates.
A sample composed of 34 nm nanospheres with a Ba0.51Dy0.49F2.49 stoichiometry, showed a transversal relaxivity (r2) value of 147.11 mM-1·s-1 at 9.4 T and gave a high negative contrast in the phantom image.
Likewise, it produced high X-ray attenuation in a large range of working voltages (from 80 KVp to 140 KVp), which can be attributed to the presence of different K-edge values, high Z elements (Ba and Dy) in the nanospheres.
Finally, these nanospheres showed negligible cytotoxicity for different biocompatibility tests. Taken together, these results show that the reported nanoparticles (NPs) are excellent candidates as UHF MRI/Spectral CT bimodal imaging CAs.This publication is part of the I + D + I Grants PID2021-122328OB-I00 and PID2020-118448RB-C21 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”.
This work was supported as well by Junta de Andalucía under grant no. P20_00182, co-financed by EU FEDER funds. High-field relaxivity measurements were performed at the ICTS “NANBIOSIS”,
specifically in Unit 28 at the “Instituto de Investigación Biomédica de Málaga y Plataforma en Nanomedicina (IBIMA Plataforma BIONAND)”.Peer reviewe
Dataset - Multimodal lanthanide vanadate-based nanoparticles for T1 -T2 MRI and NIR luminescent imaging
No full textWe report the development of a multimodal lanthanide vanadate system suitable as dual T1-T2 MRI contrast agent as well as a luminescent imaging probe in the near-infrared region, using Dy3+ and Gd3+ as T2 and T1 components, respectively, and Nd3+ as the luminescent center. The vanadate matrix was chosen to avoid the undesired solubility associated to previously reported fluoride-based contrast agents. With such aim, we first optimized the design of the MRI system by comparatively evaluating the magnetic relaxivities of two different architectures consisting of i) uniform NPs incorporating both paramagnetic cations in solid solution (single-phase NPs), and ii) core-shell NPs consisting of a DyVO4 core coated with a homogeneous GdVO4 shell (DyVO4@GdVO4). We found that, although both samples presented magnetic relaxivity properties that make them adequate for their use as dual T1-T2 contrast agents for magnetic resonance imaging, the core-shell architecture would be more suitable because of their higher magnetic relaxivity values. Secondly, to prepare the multimodal system, the GdVO4 layer of such optimal dual T1-T2 MRI probe was doped with Nd3+ cations. An inert YVO4 intermediate shell was also introduced between the cores and the outer layer aiming to avoid energy transfer from Nd3+ to Dy3+, which would cause luminescence quenching. These core-shell-shell nanoparticles showed magnetic relaxivity values similar to those of the core-shell system and an intense luminescence in the near-infrared region. Moreover, they were dispersible and chemically stable under conditions that mimic the physiological media, and they were nontoxic for cells. Therefore, such multimodal nanoparticles meet the main requirements for their use as a dual T1-T2 contrast agent for magnetic resonance imaging and as a probe for luminescent imaging in the near-infrared region.This publication is part of the I + D + I Grants PID2021-122328OB-I00 and PID2020-118448RB-C21, funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. This work was supported as well by Junta de Andalucía under grant no. P20_00182, co-financed by EU FEDER funds. Grant PRE2019-090170 funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future” is also acknowledged.F2 F2b_ FTIR spectrum of single-phase nanoparticles. F2c_ TGA curve of the single-phase nanoparticles. F2d_XRD pattern of the single-phase nanoparticles_ black. F2d_GdVO4 PDF_red. F2d_DyVO4 PDF_navy. F4 F4b_ XRD pattern of the core-shell nanoparticles_ black F4b_GdVO4 PDF_red. F4b_DyVO4 PDF_navy. F4c: FTIR spectrum of the core-shell nanoparticles. F4d: TGA curve of the core-shell nanoparticles. F6 F6_top_blue: The longitudinal (1/T1) relaxation rates at 1.44 T for different contents of single-phase nanoparticles. F6_top_red: The longitudinal (1/T1) relaxation rates at 1.44 T for different contents of core-shell nanoparticles. F6_bottom_blue: The transverse (1/T2) relaxation rates at 1.44 T for different contents of single-phase nanoparticles. F6_bottom_red: The transverse (1/T2) relaxation rates at 1.44 T for different contents of core-shell nanoparticles. F7 F7b_XRD pattern of the Dy@Y@Nd:Gd sample_black. F7b_DyVO4 PDF_grey. F7b_GdVO4 PDF_red F7b_YVO4 PDF_blue F7c_FTIR spectrum of the Dy@Y@Nd:Gd sample. F7d_TGA curve of the Dy@Y@Nd:Gd sample. F9 F9_blue: Relaxation rates (1/T1) measured at 1.44 T for different lanthanide (Dy+Gd+Nd) concentration in the Dy@Y@Nd:Gd sample. F9_red: Relaxation rates (1/T2) measured at 1.44 T for different lanthanide (Dy+Gd+Nd) concentration in the Dy@Y@Nd:Gd sample. F10 F10_top: Excitation spectrum for the Dy@Y@Nd:Gd sample. F10_ bottom: Emission spectrum for the Dy@Y@Nd:Gd sample. F11 F11_grey: DLS curve obtained for DyVO4@YVO4@Nd-doped GdVO4 nanoparticles suspensions in water. F11_red: DLS curve obtained for DyVO4@YVO4@Nd-doped GdVO4 nanoparticles suspensions in MES medium. F11_blue: DLS curve obtained for DyVO4@YVO4@Nd-doped GdVO4 nanoparticles suspensions in PBS medium. F11_green: DLS curve obtained for DyVO4@YVO4@Nd-doped GdVO4 nanoparticles suspensions in saline medium. F12 F12_Histogram_1 day: Histogram of Dy@Y@Nd:Gd nanoparticles after aging in PBS medium at 37 ºC during one day. F12_Histogram_21 days: Histogram of Dy@Y@Nd:Gd nanoparticles after aging in PBS medium at 37 ºC during 21 days. F12_Histogram_35 days: Histogram of Dy@Y@Nd:Gd nanoparticles after aging in PBS medium at 37 ºC during 35 days. F13 F13d_Analysis of the total number of cells per well exposed to increasing concentration of DyVO4@YVO4@Nd-doped GdVO4 nanoparticles. F13e_Dead cell percentage to increasing concentration of DyVO4@YVO4@Nd-doped GdVO4 nanoparticles. F13f_Mitochondrial activity of the cells to increasing concentration of DyVO4@YVO4@Nd-doped GdVO4 nanoparticles. FS1 FS1a_Size distribution histogram of the single-phase nanoparticles containing Gd and Dy as a solid solution. FS1b_Size distribution histogram of the DyVO4 nanoparticles coated with a GdVO4 shell. FS1c_Size distribution histogram of the DyVO4 nanoparticles coated with a first YVO4 shell and with a second shell consisting of GdVO4 doped with Nd3+. FS2 FS2b_Size distribution histogram for the DyVO4 nanoparticles functionalized with PAA used as cores. FS2c_ DLS curve in water suspension for the DyVO4 nanoparticles functionalized with PAA used as cores. FS2d_XRD pattern for the DyVO4 nanoparticles functionalized with PAA used as cores. FS2d_DyVO4_PDF FS2e_FTIR spectrum for the DyVO4 nanoparticles functionalized with PAA used as cores. FS2f_TGA curve for the DyVO4 nanoparticles functionalized with PAA used as cores.Peer reviewe
Mn2+-doped MgGeO3 nanophosphors with controlled shape and optimized persistent luminescence
No full textMn2+-doped MgGeO3 (MgGeO3:Mn2+) is an efficient persistent phosphor that emits red luminescence for long time after stopping excitation with UV light. For optical and biotechnological uses a precise control of particle size and shape is highly desired since these parameters may have a strong influence on the properties and suitability of phosphor materials for the intended applications. To the best of our knowledge, MgGeO3:Mn2+ has been synthesized by conventional solid-state-reaction, which yields particles of heterogeneous size and shape. Here, we report for the first time in the literature a salt-assisted method for the synthesis of MgGeO3:Mn2+ nanoparticles with uniform shape (nanorods) and a mean size of 350 nm × 99 nm. The rigorous study of the luminescence properties of the MgGeO3:Mn2+ nanorods revealed that whereas the optimum doping level for photoluminescence was 2.0 mol% Mn2+, the best persistent luminescence was attained with just 0.5 mol% Mn2+, which is ascribed to the different mechanisms of both luminescence processes. The optimum persistent nanophosphor showed an intense red emission, which persisted at least 17 h after stopping the excitation. Such excellent properties make the developed nanophosphor an attractive candidate for use in optical and biotechnological applications.This publication is part of the I + D + I Grant PID2021-122328OB-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. E.A. acknowledges Grant FPU19/00527 funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future”.Peer reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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