Influence of heart rate in non-linear HRV indices as a sampling rate effect evaluated on supine and standing

The purpose of this study is to characterize and attenuate the influence of mean heart rate (HR) on nonlinear heart rate variability (HRV) indices (correlation dimension, sample, and approximate entropy) as a consequence of being the HR the intrinsic sampling rate of HRV signal. This influence can notably alter nonlinear HRV indices and lead to biased information regarding autonomic nervous system (ANS) modulation. First, a simulation study was carried out to characterize the dependence of nonlinear HRV indices on HR assuming similar ANS modulation. Second, two HR-correction approaches were proposed: one based on regression formulas and another one based on interpolating RR time series. Finally, standard and HR-corrected HRV indices were studied in a body position change database. The simulation study showed the HR-dependence of non-linear indices as a sampling rate effect, as well as the ability of the proposed HR-corrections to attenuate mean HR influence. Analysis in a body position changes database shows that correlation dimension was reduced around 21% in median values in standing with respect to supine position (p < 0.05), concomitant with a 28% increase in mean HR (p < 0.05). After HR-correction, correlation dimension decreased around 18% in standing with respect to supine position, being the decrease still significant. Sample and approximate entropy showed similar trends. HR-corrected nonlinear HRV indices could represent an improvement in their applicability as markers of ANS modulation when mean HR changes

To shift, or not to shift: Adequate selection of an internal standard in mass-shift approaches using tandem ICP-mass spectrometry (ICP-MS/MS)

The use of an internal standard to correct for potential matrix effects and instrument instability is common practice in ICP-MS. However, with the introduction of a new generation of ICP-MS instrumentation with a tandem mass spectrometry configuration (ICP-MS/MS), the use of chemical resolution in a mass-shift approach has become much more popular, suggesting that the appropriate selection of an internal standard needs revision. In this particular case, it needs to be decided whether the internal standard should also be subjected to a mass-shift or can simply be monitored on-mass ("to shift, or not to shift"). In this work, 17 elements covering a wide range of masses (24-205 amu) and ionization energies (3.89-9.39 eV) were measured via on-mass and/or mass-shift strategies, and the corresponding atomic ions and reaction product ions were monitored during various systematic experiments. For mass-shifting, an NH3/He gas mixture was used to obtain NH3-based reaction product ions (cluster formation). Product ion scanning (PIS) was used for assessing the differences in reactivity between the different analytes and for the identification of the best suited reaction product ions. It was found that the use of chemical resolution can significantly affect the short-term signal stability and that ion signals measured on-mass are not affected in the same way as those measured mass-shifted. Variations affecting the signal intensities of both atomic and reaction product ions can be attributed to the ion-molecule chemistry occurring within the collision/reaction cell and were found to be related with some degree of initial instability in the cell and differences in reactivity. The use of a sufficiently long stabilization time, however, avoids or at least mitigates such differences in the behavior between signals monitored on-mass and after mass-shifting, respectively. Furthermore, the introduction of cell disturbances, such as those generated after quickly switching between different sets of operating conditions in a multi-tune method, revealed significant differences in signal behavior between atomic and reaction product ions, potentially hampering the use of an internal standard monitored on-mass when the analysis is based on an analyte monitored after mass-shifting. However, the use of a reasonable waiting time again greatly mitigates such differences, with the duration of this stabilization time depending on the magnitude of the cell disturbances (e.g., switch between vented and pressurized mode or only between pressurized modes using different gas flow rates). In addition, also the effect of varying different instrument settings (plasma power, torch position, and gas and liquid flow rates) was evaluated, but no remarkable differences were found between signals monitored on-mass and those mass-shifted. Interestingly, a statistical evaluation of the influence of the different settings on the signal intensities of all ions monitored did not reveal the a priori important role of some properties traditionally suggested for adequate selection of analyte/internal standard pairs, such as mass number or ionization energy, as also suggested in other recent studies. © The Royal Society of Chemistry

An approach to the natural and engineered nanoparticles analysis in the environment by inductively coupled plasma mass spectrometry

Different approaches to the most relevant and recent studies and applications of inductively coupled plasma mass spectrometry (ICP-MS) applied to the analysis of natural and engineered nanoparticles in the environment are described. Usually several separation methods like polyacrylamide gel electrophoresis (PAGE), field-flow fractionation (FFF) and size exclusion chromatography (SEC) are used prior to the mass spectrometric measurements. In many cases the use of these hyphenated techniques provides important methodologies to know the bioavailability, mobility and toxicity of elements in life and environmental sciences. Alternatively, the capabilities of the single particle detection by ICP-MS (SD-ICP-MS) for the selective identification, characterization and determination of engineered nanoparticles will be also discussed

A simple dilute-and-shoot approach for the determination of ultra-trace levels of arsenic in biological fluids via ICP-MS using CH3F/He as a reaction gas

The performance of a mixture of CH3F/He (1/9) as a reaction gas for the determination of As in biological fluids using a quadrupole ICP-MS instrument has been explored. A simple (dilute-and-shoot) interference-free method has been developed to quantify As concentrations at trace and ultra-trace levels in matrices with a high Cl content. As+ reacts with CH3F (through CH3F addition, followed by HF elimination) with high efficiency forming AsCH2 + as the primary reaction product, which can be monitored at a mass-to-charge ratio of 89, free from the Cl-based interferents (e.g., 40Ar35Cl+ and 40Ca35Cl+) that hamper the monitoring of 75As+. Matrix effects are overcome by the use of Te as an internal standard and the addition of 3% v/v ethanol to all samples and calibration standard solutions. The method presented was validated by analysing a set of reference materials (blood, serum and urine) and by assessing As recovery from a set of real blood samples. With this method, the limit of detection was calculated to be 0.8 ng L-1 As, favourably comparable to the vast majority of values reported in the literature, even with those obtained using more sophisticated sector-field instrumentation

Living in a transient world: ICP-MS reinvented via time-resolved analysis for monitoring single events

After 40 years of development, inductively coupled plasma-mass spectrometry (ICP-MS) can hardly be considered as a novel technique anymore. ICP-MS has become the reference when it comes to multi-element bulk analysis at (ultra)trace levels, as well as to isotope ratio determination for metal(loid)s. However, over the last decade, this technique has managed to uncover an entirely new application field, providing information in a variety of contexts related to the individual analysis of single entities (e.g., nanoparticles, cells, or micro/nanoplastics), thus addressing new societal challenges. And this profound expansion of its application range becomes even more remarkable when considering that it has been made possible in an a priori simple way: by providing faster data acquisition and developing the corresponding theoretical substrate to relate the time-resolved signals thus obtained with the elemental composition of the target entities. This review presents the underlying concepts behind single event-ICP-MS, which are needed to fully understand its potential, highlighting key areas of application (e.g., single particle-ICP-MS or single cell-ICP-MS) as well as of future development (e.g., micro/nanoplastics)

Stigmatella aurantiaca, un mixobacteri amb aspecte de mixomicet, trobat al Parc de Collserola (Catalunya)

Stigmatella allrantiaca, un mixobacteri amb aspecte de mixomicet, trobat al Parc de Collserola (Catalunya). Stigmatella aurantiaca ha estat trobada sobre restes vegetals recol&middot;lectades a Collserola, prop de Barcelona (Catalunya). Es tracta d'un mixobacteri que rarament es pot veure formant cossos fructífers a la natura i es pot confondre fàcilment amb un mixomicet immadur. Forma grups de cossos fructífers molt petits, de color taronja, portats per pedicels blancs.Stigmatella allrantiaca, a myxomycete-looking myxobacterium, found in Collserola Park (Catalonia). Stigmatella aurantiaca has been found on plant debris collected in ColIserola, near Barcelona (Catalonia). It belongs to myxobacteria, a group of procariotes rarely found fonuing fruiting bodies in the nature, where it may easily be confused with an immature myxomycete. It forms clusters of tiny fruiting bodies, orange coloured, on white stalks.Stigmatella aurantiaca, una mixobacteria con aspecto de mixomicete, hallada en el Parque de Collserola (Cataluña). Stigmatella aurantiaca ha sido encontrada sobre restos vegetales recolectados en Collserola, cerca de Barcelona (Cataluña). Se trata de una mixobacteria que raramente se puede ver formando cuerpos fructíferos en la naturaleza y que fácilmente se puede confundir con algún mixomicete inmaduro. Forma grupos de diminutos cuerpos fructíferos de color naranja, sostenidos por pedicelos blancos

High-precision isotopic analysis sheds new light on mercury metabolism in long-finned pilot whales (Globicephala melas)

Eduardo Bolea-Fernandez acknowledges BOF-UGent for his postdoctoral grant. We acknowledge Arnout Laureys for his support, Jonas Kunigkeit and Magali Perez for isolation of HgSe particles, and Dr. Andrew Brownlow for given access to the Pilot Whale samples.Peer reviewedPublisher PD

Human emotion characterization by heart rate variability analysis guided by respiration

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksDeveloping a tool which identifies emotions based on their effect on cardiac activity may have a potential impact on clinical practice, since it may help in the diagnosing of psycho-neural illnesses. In this study, a method based on the analysis of heart rate variability (HRV) guided by respiration is proposed. The method was based on redefining the high frequency (HF) band, not only to be centered at the respiratory frequency, but also to have a bandwidth dependent on the respiratory spectrum. The method was first tested using simulated HRV signals, yielding the minimum estimation errors as compared to classical and respiratory frequency centered at HF band based definitions, independently of the values of the sympathovagal ratio. Then, the proposed method was applied to discriminate emotions in a database of video-induced elicitation. Five emotional states, relax, joy, fear, sadness and anger, were considered. The maximum correlation between HRV and respiration spectra discriminated joy vs. relax, joy vs. each negative valence emotion, and fear vs. sadness with p-value = 0.05 and AUC = 0.70. Based on these results, human emotion characterization may be improved by adding respiratory information to HRV analysis.Peer ReviewedPostprint (author's final draft

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 &gt;100 nm, it was possible to provide accurateresults in a straightforward way, as theirsignal distributions are well resolved fromthat of the background