Characterization of SiO2 Nanoparticles by Single Particle - Inductively Coupled Plasma – Tandem Mass Spectroscopy

This work uses the tandem ICP-MS (ICPMS/MS) for obtaining interference-freeconditions to characterize SiO2 nanoparticles ranging between 80 and 400nm. These NPs have been detected and accurately characterized. For SiO2 NPs >100 nm, it was possible to provide accurateresults in a straightforward way, as theirsignal distributions are well resolved fromthat of the background

Characterization of SiO2 nanoparticles by single particle-inductively coupled plasma-tandem mass spectrometry (SP-ICP-MS/MS)

The increase in the use of SiO2 nanoparticles (NPs) is raising concern about their environmental and health effects, thus necessitating the development of novel methods for their straightforward detection and characterization. Single particle ICP-mass spectrometry (SP-ICP-MS) is able to provide information on the size of NPs, their particle number density and mass concentration. However, the determination of Si via ICP-MS is strongly hampered by the occurrence of spectral overlap from polyatomic species (e.g., CO+ and N2+). The use of tandem ICP-MS (ICP-MS/MS) enables interference-free conditions to be obtained, even in the most demanding applications. Upon testing several gases, the use of CH3F (monitoring of SiF+, mass-shift approach) and of H2 (monitoring of Si+, on-mass approach) were demonstrated to be the most suitable to overcome the spectral interference affecting ultra-trace Si determination (LoD < 15 ng L-1). By using these approaches, SiO2 NPs (ranging between 80 and 400 nm) can be detected and characterized. For SiO2 NPs > 100 nm, it was possible to provide accurate results in a straightforward way, as the signals they give rise to are well resolved from those of the background. In the case of 80 and 100 nm NPs, the use of a simple deconvolution approach following a Gaussian model was needed to characterize SiO2 NPs apparently showing incomplete distributions as a result of the presence of the background signal. Overall, the methods developed using SP-ICP-MS/MS are sensitive and selective enough for the interference-free determination of Si at ultra-trace levels, also in the form of SiO2 NPs

A novel approach for adapting the standard addition method to single particle-ICP-MS for the accurate determination of NP size and number concentration in complex matrices; 35414390

This paper presents a novel approach, based on the standard addition method, for overcoming the matrix effects that often hamper the accurate characterization of nanoparticles (NPs) in complex samples via single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). In this approach, calibration of the particle size is performed by two different methods: (i) by spiking a suspension of NPs standards of known size containing the analyte, or (ii) by spiking the sample with ionic standards; either way, the measured sensitivity is used in combination with the transport efficiency (TE) for sizing the NPs. Moreover, such transport efficiency can be readily obtained from the data obtained via both calibration methods mentioned above, so that the particle number concentration can also be determined. The addition of both ionic and NP standards can be performed on-line, by using a T-piece with two inlet lines of different dimensions. The smaller of the two is used for the standards, thus ensuring a constant and minimal sample dilution. As a result of the spiking of the samples, mixed histograms including the signal of the sample and that of the standards are obtained. However, the use of signal deconvolution approaches permits to extract the information, even in cases of signal populations overlapping. For proofing the concept, characterization of a 50 nm AuNPs suspension prepared in three different media (i.e., deionized water, 5% ethanol, and 2.5% tetramethyl ammonium hydroxide-TMAH) was carried out. Accurate results were obtained in all cases, in spite of the matrix effects detected in some media. Overall, the approach proposed offers flexibility, so it can be adapted to different situations, but it might be specially indicated for samples for which the matrix is not fully known and/or dilution is not possible/recommended. © 2022 The Author

Reduction of motion effects in myocardial arterial spin labeling

Purpose To evaluate the accuracy and reproducibility of myocardial blood flow measurements obtained under different breathing strategies and motion correction techniques with arterial spin labeling. Methods A prospective cardiac arterial spin labeling study was performed in 12 volunteers at 3 Tesla. Perfusion images were acquired twice under breath-hold, synchronized-breathing, and free-breathing. Motion detection based on the temporal intensity variation of a myocardial voxel, as well as image registration based on pairwise and groupwise approaches, were applied and evaluated in synthetic and in vivo data. A region of interest was drawn over the mean perfusion-weighted image for quantification. Original breath-hold datasets, analyzed with individual regions of interest for each perfusion-weighted image, were considered as reference values. Results Perfusion measurements in the reference breath-hold datasets were in line with those reported in literature. In original datasets, prior to motion correction, myocardial blood flow quantification was significantly overestimated due to contamination of the myocardial perfusion with the high intensity signal of blood pool. These effects were minimized with motion detection or registration. Synthetic data showed that accuracy of the perfusion measurements was higher with the use of registration, in particular after the pairwise approach, which probed to be more robust to motion. Conclusion Satisfactory results were obtained for the free-breathing strategy after pairwise registration, with higher accuracy and robustness (in synthetic datasets) and higher intrasession reproducibility together with lower myocardial blood flow variability across subjects (in in vivo datasets). Breath-hold and synchronized-breathing after motion correction provided similar results, but these breathing strategies can be difficult to perform by patients

Multiparametric renal magnetic resonance imaging: A reproducibility study in renal allografts with stable function

Monitoring renal allograft function after transplantation is key for the early detection of allograft impairment, which in turn can contribute to preventing the loss of the allograft. Multiparametric renal MRI (mpMRI) is a promising noninvasive technique to assess and characterize renal physiopathology; however, few studies have employed mpMRI in renal allografts with stable function (maintained function over a long time period). The purposes of the current study were to evaluate the reproducibility of mpMRI in transplant patients and to characterize normal values of the measured parameters, and to estimate the labeling efficiency of Pseudo-Continuous Arterial Spin Labeling (PCASL) in the infrarenal aorta using numerical simulations considering experimental measurements of aortic blood flow profiles. The subjects were 20 transplant patients with stable kidney function, maintained over 1 year. The MRI protocol consisted of PCASL, intravoxel incoherent motion, and T1 inversion recovery. Phase contrast was used to measure aortic blood flow. Renal blood flow (RBF), diffusion coefficient (D), pseudo-diffusion coefficient (D*), flowing fraction ( f ), and T1 maps were calculated and mean values were measured in the cortex and medulla. The labeling efficiency of PCASL was estimated from simulation of Bloch equations. Reproducibility was assessed with the within-subject coefficient of variation, intraclass correlation coefficient, and Bland-Altman analysis. Correlations were evaluated using the Pearson correlation coefficient. The significance level was p less than 0.05. Cortical reproducibility was very good for T1, D, and RBF, moderate for f , and low for D*, while medullary reproducibility was good for T1 and D. Significant correlations in the cortex between RBF and f (r = 0.66), RBF and eGFR (r = 0.64), and D* and eGFR (r = -0.57) were found. Normal values of the measured parameters employing the mpMRI protocol in kidney transplant patients with stable function were characterized and the results showed good reproducibility of the techniques

Respuestas de oyentes y expertos musicales a una encuesta para valorar la percepción musical en salas de conciertos, auditorios y teatros

Para valorar la percepción musical en salas de concierto se diseñó una encuesta de 58 preguntas en la que cada una se valoraba de 0 a 5 puntos. A esta encuesta han respondido 1057 personas entre público en general y expertos musicales, sin formación especializada en acústica, tras la audición de un concierto en alguno de los 14 auditorios, salas de conciertos y teatros ubicados en diferentes comunidades de nuestro país (8 en el sur y 6 en levante). El análisis de las respuestas obtenidas ha mostrado que la fluctuación de la valoración media de cada una de las preguntas de la encuesta en una sala es un patrón que se repite aproximadamente en todas las salas estudiadas, formando una banda de aproximadamente 1 punto de variación en cada respuesta que contiene a todas las salas. Los límites de esta banda indicarían los extremos de respuesta subjetiva asociada a las salas de conciertos.Ponencia presentada en el Encuentro Ibérico de Acústica. EAA Symposium. Gandía(España). 2006.In order to evaluate the quality of the musical perception in concert halls, a survey with 58 items was designed in which each question was valued from 0 to 5 points. This survey has been replied by 1057 people between general public and musical experts without any specialized formation in acoustics, after the audition of a concert in any of the 14 auditoriums, concert hall or theatres, located in different regions of our country (8 in the south and 6 in the east). The analysis has shown that the fluctuation of the mean valuation of each question of the survey in a determined room is a pattern that is repeated approximately in all of the studied spaces, forming a band of approximately 1 variation point in each answer and that contains to all rooms. The limits of this band would indicate the ends of the subjective response associated to concert halls

Elaboration process of a subjective response test from listeners and Musical experts, as a tool of evaluation of the musical perception in Concerts halls, auditoria and theatres

In order to tackle the study related to the requirements for musical audition in concert halls, some measurements and analyses of objective acoustic parameters have been made. However, the subjective evaluation of the sensation that the values of these acoustic parameters have on the listeners, can only be shown by means of a questionnaire that listeners have to answer. Such questionnaire has been formulated in an understandable way and the questions are directly or indirectly related to the abovementioned parameters. The aim of the present article is to present the elaboration process of a test of subjective response addressed to the general public and to some musical experts who have no special skills on acoustics. This study has been made in 13 auditoria, concert rooms and theatres distributed in different Autonomous Regions of Spain.Para abordar el estudio de las exigencias para la audición musical en salas de conciertos se realiza la medida y análisis de parámetros acústicos objetivos. Sin embargo, la valoración subjetiva de la sensación que unos u otros valores de esos parámetros acústicos producen en la audiencia, sólo puede ponerse de manifiesto a través de las respuestas de los oyentes a una encuesta cuyas preguntas, formuladas de manera comprensible, estén relacionadas, directa o indirectamente, con dichos parámetros acústicos. El objeto de este artículo es presentar el proceso de elaboración de un test de respuesta subjetiva dirigido al público en general y a expertos musicales pero sin formación especializada en acústica. Este estudio se ha realizado en 13 auditorios, salas de conciertos y teatros repartidos en diferentes Comunidades Autónomas de nuestro país. Ponencia presentada al Encuentro Ibérico de Acústica. EAA Symposium. Gandía (España). 200