Background: Although serious health effects associated with paniculate matter (PM) with aerodynamic diameter ≤ 10 μm (PM) and ≤ 2.5 μm (PM₂.₅; fine fraction) are documented in many studies, the ...effects of coarse PM (PM₂.₅-₁₀) are still under debate. Objective: In this study, we estimated the effects of short-term exposure of PM₂.₅-₁₀ on daily mortality in Stockholm, Sweden. Method: We collected data on daily mortality for the years 2000 through 2008. Concentrations of PM₁₀ , PM₂.₅, ozone, and carbon monoxide were measured simultaneously in central Stockholm. We used additive Poisson regression models to examine the association between daily mortality and PM₂.₅-₁₀ on the day of death and the day before. Effect estimates were adjusted for other pollutants (two-pollutant models) during different seasons. Results: We estimated a 1.68% increase 95% confidence interval (CI): 0.20%, 3.15% in daily mortality per 10-μg/m³ increase in PM₂.₅-₁₀ (single-pollutant model). The association with PM₂.₅-₁₀ was stronger for November through May, when road dust is most important (1.69% increase; 95% CI: 0.21%, 3.17%), compared with the rest of the year (1.31% increase; 95% CI: -2.08%, 4.70%), although the difference was not statistically significant. When adjusted for other pollutants, particularly PM₂.₅, the effect estimates per 10 μg/m³ for PM₂.₅-₁₀ decreased slightly but were still higher than corresponding effect estimates for PM₂.₅· Conclusions: Our analysis shows an increase in daily mortality associated with elevated urban background levels of PM₂.₅-₁₀· Regulation of PM₂.₅-₁₀ should be considered, along with actions to specifically reduce PM₂.₅-₁₀ emissions, especially road dust suspension, in cities.
Magnetoelectric (magnetic/piezoelectric) heterostructures bring new functionalities to develop novel transducer devices such as (wireless) sensors or energy harvesters and thus have been attracting ...research interest in the last years. We have studied the magnetoelectric coupling between Metglas films (2826 MB) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) in a laminate structure. The metallic Metglas film itself served as bottom electrode and as top electrode we used an electrically conductive polymer, poly(3,4-ethylene-dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). Besides a direct electrical wiring via a graphite ink, a novel contactless readout method is presented using a capacitive coupling between the PEDOT:PSS layer and an electrode not in contact with the PEDOT:PSS layer. From the experimental result we determined a magnetoelectric coupling of 1445 V/(cm·Oe) at the magnetoelastic resonance of the structure, which is among the highest reported values for laminate structures of a magnetostrictive and a piezoelectric polymer layer. With the noncontact readout method, a magnetoelectric coupling of about 950 V/(cm·Oe) could be achieved, which surpasses previously reported values for the case of direct sample contacting. 2D laser Doppler vibrometer measurements in combination with FE simulations were applied to reveal the complex vibration pattern resulting in the strong resonant response.
Measurements of the ac susceptibility (ACS) as a function of frequency have been widely applied for the determination of structure parameters of magnetic nanoparticles (MNP). The analysis of spectra ...of real and imaginary parts measured on suspensions of MNP is generally based on the Debye model, extended by distributions of size parameters. Here, we compare different modifications of the Debye model with experimental data recorded on suspensions of single-core and multi-core iron-oxide nanoparticles. The applied models also depend on whether the nanoparticle's magnetic moments are thermally blocked and whether both Brownian and Néel relaxation have to be taken into account. The obtained core and hydrodynamic size parameters are compared with those from transmission electron microscopy and dynamic light scattering. Whereas structure parameters can be reliably determined for single-core nanoparticles, the interpretation of ACS spectra measured on multi-core nanoparticles is more complicated, especially regarding the contribution of particles relaxing via the Néel mechanism. Depending on the packing density and thus the interaction between cores in a particle, the effective core parameters derived from the spectrum must be interpreted with care.
Kerbside concentrations of NOx, black carbon (BC), total number of particles (diameter > 4 nm) and number size distribution (28–410 nm) were measured at a busy street canyon in Stockholm in 2006 and ...2013. Over this period, there was an important change in the vehicle fleet due to a strong dieselisation process of light-duty vehicles and technological improvement of vehicle engines. This study assesses the impact of these changes on ambient concentrations and particle emission factors (EF). EF were calculated by using a novel approach which combines the NOx tracer method with positive matrix factorisation (PMF) applied to particle number size distributions. NOx concentrations remained rather constant between these two years, whereas a large decrease in particle concentrations was observed, being on average 60% for BC, 50% for total particle number, and 53% for particles in the range 28–100 nm. The PMF analysis yielded three factors that were identified as contributions from gasoline vehicles, diesel fleet, and urban background. This separation allowed the calculation of the average vehicle EF for each particle metric per fuel type. In general, gasoline EF were lower than diesel EF, and EF for 2013 were lower than the ones derived for 2006. The EFBC decreased 77% for both gasoline and diesel fleets, whereas the particle number EF reduction was higher for the gasoline (79%) than for the diesel (37%) fleet. Our EF are consistent with results from other on-road studies, which reinforces that the proposed methodology is suitable for EF determination and to assess the effectiveness of policies implemented to reduce vehicle exhaust emissions. However, our EF are much higher than EF simulated with traffic emission models (HBEFA and COPERT) that are based on dynamometer measurements, except for EFBC for diesel vehicles. This finding suggests that the EF from the two leading models in Europe should be revised for BC (gasoline vehicles) and particle number (all vehicles), since they are used to compile national inventories for the road transportation sector and also to assess their associated health effects. Using the calculated kerbside EF, we estimated that the traffic emissions were lower in 2013 compared to 2006 with a 61% reduction for BC (due to decreases in both gasoline and diesel emissions), and 34–45% for particle number (reduction only in gasoline emissions). Limitations of the application of these EF to other studies are also discussed.
•Traffic-related pollutants were measured within a street canyon in 2006 and 2013.•Emission factors (EF) were calculated from these measurements for both years.•Large reduction in black carbon (BC) and particle number (PN) concentrations.•EF are consistent with on-road studies but higher than simulated by emission models.•Traffic emissions largely decreased for BC (61%), but less for PN (34%).
We have experimentally verified the ac susceptibility model by Shliomis and Stepanov which accounts for the anisotropy caused by the different directions of the easy axes of the magnetic nanoparticle ...(MNP) cores with respect to the applied ac magnetic field. To experimentally access the anisotropy, single-core MNPs were immobilized in the absence of a magnetic field, thus causing random orientations of easy axes, and in a static magnetic field of 170 mT, thus orienting the nanoparticles' easy axes either parallel or perpendicular to the ac field. In agreement with theory, the real part of the sample with easy axes aligned perpendicularly to the ac field is constant while the imaginary part is zero. In contrast, the real part of the sample with parallel-oriented easy axes decays with increasing frequency. The susceptibility spectra of the sample with random orientation of easy axes are in between the other two cases according to χ(ω) = (χ II (ω) + 2χ ⊥ (ω))/3. This anisotropic behavior also explains why the real part of suspensions of thermally blocked MNPs does not drop down to zero at high frequencies but to a finite value. This value allows one to independently estimate the effective anisotropy constant of MNPs.
This study investigates the use of eddy-current technology and impedance spectroscopy in sensing the change in rubber properties after it is exposed to accelerated thermal aging. The thermal aging ...process, by application of temperature and pressure over time, of ethylene propylene diene monomer (EPDM) rubbers containing both carbon black (CB) and graphene are investigated. Both eddy-current sensing and electrical impedance measurement techniques were used for electromagnetic analysis. Both methods measure the in- and out-of-phase responses as a function of excitation frequency at room temperature. The measurements were performed before and after the aging process. The electrical percolation threshold was detected in the rubber samples by varying the CB content from 0 to 40 wt%. In the rubber sample containing 30 wt% CB, 0-5 wt% of the CB was replaced with graphene flakes. The substitution of graphene for CB in the EPDM rubber formulation provided an enhanced eddy-current and electrical impedance response. The findings demonstrate the feasibility of employing electromagnetic analysis techniques to investigate the extent of aging.
Because of the serological cross-reactivity among the flaviviruses, molecular detection methods, such as reverse-transcription polymerase chain reaction (RT-PCR), play an important role in the recent ...Zika outbreak. However, due to the limited sensitivity, the detection window of RT-PCR for Zika viremia is only about one week after symptom onset. By combining loop-mediated isothermal amplification (LAMP) and AC susceptometry, we demonstrate a rapid and homogeneous detection system for the Zika virus oligonucleotide. Streptavidin-magnetic nanoparticles (streptavidin-MNPs) are premixed with LAMP reagents including the analyte and biotinylated primers, and their hydrodynamic volumes are dramatically increased after a successful LAMP reaction. Analyzed by a portable AC susceptometer, the changes of the hydrodynamic volume are probed as Brownian relaxation frequency shifts, which can be used to quantify the Zika virus oligonucleotide. The proposed detection system can recognize 1 aM synthetic Zika virus oligonucleotide in 20% serum with a total assay time of 27min, which can hopefully widen the detection window for Zika viremia and is therefore promising in worldwide Zika fever control.
•Synthetic Zika virus oligonucleotide is quantified by an AC susceptometer.•Amplicons of the LAMP reaction are attached to the magnetic nanoparticles.•Mg2P2O7 deposits onto the nanoparticles and further improves the signal.•An LOD of 1 aM oligos can be achieved with a total assay time of 27min.
We investigated, in depth, the interrelations among structure, magnetic properties, relaxation dynamics and magnetic hyperthermia performance of magnetic nanoflowers. The nanoflowers are about 39 nm ...in size, and consist of densely packed iron oxide cores. They display a remanent magnetization, which we explain by the exchange coupling between the cores, but we observe indications for internal spin disorder. By polarized small-angle neutron scattering, we unambiguously confirm that, on average, the nanoflowers are preferentially magnetized along one direction. The extracted discrete relaxation time distribution of the colloidally dispersed particles indicates the presence of three distinct relaxation contributions. We can explain the two slower processes by Brownian and classical Néel relaxation, respectively. The additionally observed very fast relaxation contributions are attributed by us to the relaxation of disordered spins within the nanoflowers. Finally, we show that the intrinsic loss power (ILP, magnetic hyperthermia performance) of the nanoflowers measured in colloidal dispersion at high frequency is comparatively large and independent of the viscosity of the surrounding medium. This concurs with our assumption that the observed relaxation in the high frequency range is primarily a result of internal spin relaxation, and possibly connected to the disordered spins within the individual nanoflowers.
In this study, the effects on daily mortality in Stockholm associated with short-term exposure to ultrafine particles (measured as number of particles with a diameter larger than 4 nm, PNC₄), black ...carbon (BC) and coarse particles (PM
) have been compared with the effects from more common traffic-pollution indicators (PM
, PM
and NO₂) and O₃ during the period 2000⁻2016. Air pollution exposure was estimated from measurements at a 20 m high building in central Stockholm. The associations between daily mortality lagged up to two days (lag 02) and the different air pollutants were modelled by using Poisson regression. The pollutants with the strongest indications of an independent effect on daily mortality were O₃, PM
and PM
. In the single-pollutant model, an interquartile range (IQR) increase in O₃ was associated with an increase in daily mortality of 2.0% (95% CI: 1.1⁻3.0) for lag 01 and 1.9% (95% CI: 1.0⁻2.9) for lag 02. An IQR increase in PM
was associated with an increase in daily mortality of 0.8% (95% CI: 0.1⁻1.5) for lag 01 and 1.1% (95% CI: 0.4⁻1.8) for lag 02. PM
was associated with a significant increase only at lag 02, with 0.8% (95% CI: 0.08⁻1.4) increase in daily mortality associated with an IQR increase in the concentration. NO₂ exhibits negative associations with mortality. The significant excess risk associated with O₃ remained significant in two-pollutant models after adjustments for PM
, BC and NO₂. The significant excess risk associated with PM
remained significant in a two-pollutant model after adjustment for NO₂. The significantly negative associations for NO₂ remained significant in two-pollutant models after adjustments for PM
, O₃ and BC. A potential reason for these findings, where statistically significant excess risks were found for O₃, PM
and PM
, but not for NO₂, PM
, PNC₄ and BC, is behavioral factors that lead to misclassification in the exposure. The concentrations of O₃ and PM
are in general highest during sunny and dry days during the spring, when exposure to outdoor air tend to increase, while the opposite applies to NO₂, PNC₄ and BC, with the highest concentrations during the short winter days with cold weather, when people are less exposed to outdoor air.