Mass Depositions Research Articles

PM10-bound microplastics and trace metals: A public health insight from the Korean subway and indoor environments

Inhalable airborne microplastics (MPs) presented in indoor and outdoor environments, can deeply penetrate the lungs, potentially triggering inflammation and respiratory illnesses. The present study aims to evaluate human health risks from respirable particulate matter (PM)-bound trace metals and MPs in indoor (SW- subway and IRH- indoor residential houses) and outdoor (OD) environments. This research provides an initial approach to human respiratory tract (HRT) mass depositions of PM10-bound total MPs and nine specific MP types to predict potential human health threats from inhalation exposure. Results indicate that PM-bound trace metals and MPs were around 4 times higher in SW microenvironments compared to OD locations. In IRH, cancer risk (CR) levels were estimated 9 and 4 times higher for PM10 and PM2.5, respectively. Additionally, MP particle depositions per gram of lung cell weight were highest in IRH (23.77), followed by OD and SW. Whereas, lifetime alveoli depositions of MPs were estimated at 13.73 MP/g, which exceeds previously reported respiratory disease fatality cases by 10 to 5 times. Prolonged exposure duration at IRH emerged as a key factor contributing to increased CR and MP lung deposition levels. This research highlights severe lung risks from inhaling PM-bound MPs and metals, offering valuable health insights.

Reliable compositional analysis of airborne particulate matter beyond the quantification limits of total reflection X-ray fluorescence

Knowledge on the temporal and size distribution of particulate matter (PM) in air as well as on its elemental composition is a key information for source appointment, for the investigation of their influence on environmental processes and for providing reliable data for climate models. While cascade impactors allow for time- and size-resolved collection of airborne PM, total reflection X-ray fluorescence (TXRF) allows for element-sensitive investigation of minute sample amounts thanks to its detection sensitivity. But during quantification by means of TXRF it is crucial to be aware of the linear calibration limits of TXRF in order to identify situations where collection times or pollution levels in the different size partitions were exceedingly long or high. Indeed, TXRF can only be reliably used when the amount of matter collected on the top of the substrate is sufficiently small. By means of grazing incidence X-ray fluorescence (GIXRF), where the excitation conditions are varied in a controlled and reliable manner and include also the TXRF regime, a self consistent quantification of elemental mass depositions can be performed in order to validate or falsify TXRF quantification results. For low mass depositions an agreement within a few percent for the different excitation conditions was found, while for increasing amounts of material relative errors of up to a factor of 4 were found for TXRF as compared to GIXRF. Thus, TXRF cannot be applied to all samples regardless of their coverage and threshold values for the validity of quantification results need to be determined. As a flexible solution, GIXRF allows extending the dynamic range of reliably quantifiable mass depositions beyond the linear regime of TXRF, an important advantage when variable amounts of airborne PM need to be quantified as in the case of collection with cascade impactors. The presented more reliable quantification approach can be transferred to mobile tabletop instrumentation as well. This aspect is highly relevant for air quality monitoring in terms of supporting the introduction of appropriate legislation and measures for health and climate protection as well as for supporting their enforcement.

Reference-free grazing incidence x-ray fluorescence and reflectometry as a methodology for independent validation of x-ray reflectometry on ultrathin layer stacks and a depth-dependent characterization

Nanolayer stacks are technologically very relevant for current and future applications in many fields of research. A nondestructive characterization of such systems is often performed using x-ray reflectometry (XRR). For complex stacks of multiple layers, low electron density contrast materials, or very thin layers without any pronounced angular minima, this requires a full modeling of the XRR data. As such a modeling is using the thicknesses, the densities, and the roughnesses of each layer as parameters, this approach quickly results in a large number of free parameters. In consequence, cross correlation effects or interparameter dependencies can falsify the modeling results. Here, the authors present a route for validation of such modeling results which is based on the reference-free grazing incidence x-ray fluorescence (GIXRF) methodology. In conjunction with the radiometrically calibrated instrumentation of the Physikalisch-Technische Bundesanstalt, the method allows for reference-free quantification of the elemental mass depositions. In addition, a modeling approach of reference-free GIXRF-XRR data is presented, which takes advantage of the quantifiable elemental mass depositions by distributing them depth dependently. This approach allows for a reduction of the free model parameters. Both the validation capabilities and the combined reference-free GIXRF-XRR modeling are demonstrated using several nanoscale layer stacks consisting of HfO2 and Al2O3 layers.

Parameter sensitivity of cantilever beam with tip mass to parametric excitation

The sensitivity of the response of a parametrically excited cantilever beam with a tip mass to small variations in elasticity (stiffness) and the tip mass is performed. The governing equation of the first mode is derived, and method of multiple scales is used to determine the approximate solution based on the order of the expected variations. We demonstrate that the system can be designed so that small variations in either stiffness or tip mass can alter the type of bifurcation. Notably, we show that the response of a system designed for a supercritical bifurcation can change to yield a subcritical bifurcation with small variations in the parameters. Although such a trend is usually undesired, we argue that it can be used to detect small variations induced by fatigue or small mass depositions in sensing applications.

Development and characterization of sub-monolayer coatings as novel calibration samples for X-ray spectroscopy

With the advent of both modern X-ray fluorescence (XRF) methods and improved analytical reliability requirements the demand for suitable reference samples has increased. Especially in nanotechnology with the very low areal mass depositions, quantification becomes considerably more difficult. However, the availability of suited reference samples is drastically lower than the demand. Physical vapor deposition techniques have been enhanced significantly in the last decade driven by the need for extremely precise film parameters in multilayer production. We have applied those techniques for the development of layer-like reference samples with mass depositions in the ng-range and well below for Ca, Cu, Pb, Mo, Pd, Pb, La, Fe and Ni. Numerous other elements would also be possible. Several types of reference samples were fabricated: multi-elemental layer and extremely low (sub-monolayer) samples for various applications in XRF and total-reflection XRF analysis. Those samples were characterized and compared at three different synchrotron radiation beamlines at the BESSY II electron storage ring employing the reference-free XRF approach based on physically calibrated instrumentation. In addition, the homogeneity of the multi-elemental coatings was checked at the P04 beamline at DESY. The measurements demonstrate the high precision achieved in the manufacturing process as well as the versatility of application fields for the presented reference samples.

Modeled deposition of fine particles in human airway in Beijing, China

Abstract This study aims to simulate depositions of size-segregated particles in human airway in Beijing, China during seasons when fine particulate matter concentrations are high (December 2011 and April 2012). Particle size distributions (5.6–560 nm, electrical mobility diameter) near a major road in Beijing were measured by the TSI Fast Mobility Particle Sizer (FMPS). The information of size distributions provided by FMPS was applied in the Multiple-Path Particle Dosimetry model (MPPD) to quantify number and mass depositions of particles in human airway including extrathoracic (ET), tracheobronchial (TB), and pulmonary (PUL) regions of exposed Chinese in Beijing. Our results show that under ambient conditions, particle number concentration (NC) deposition in PUL is the highest in the three major regions of human airway. The total particle NC deposition in human airway in winter is higher than that in spring, especially for ultrafine particles (1.8 times higher) while particle mass concentration (MC) deposition is higher in spring. Although particle MC in clean days are much lower than that in heavily polluted days, total particle NC deposition in human airway in clean days is comparable to that in heavily polluted days. NC deposition for nucleation mode particles (10–20 nm, aerodynamic diameter) in clean days is higher than that in heavily polluted days. MC deposition for accumulation mode particles (100–641 nm, aerodynamic diameter) in heavily polluted days is much higher than that in clean days, while that of nucleation mode is negligible. The temporal variation shows that the arithmetic mean and the median values of particle NC and MC depositions in the evening are both the highest, followed by morning and noon, and it is most likely due to increased contribution from traffic emissions.

Are obesity and body fat distribution associated with low back pain in women? A population-based study of 1128 Spanish twins.

To investigate the relationship between different measures of obesity and chronic low back pain (LBP) using a within-pair twin case-control design that adjusts for genetics and early shared environment. A cross-sectional association between lifetime prevalence of chronic LBP and different measures of obesity (body mass index-BMI; percent body fat; waist circumference; waist-hip ratio) was investigated in 1128 female twins in three stages: (i) total sample analysis; (ii) within-pair case-control analysis for monozygotic (MZ) and dizygotic (DZ) twins together; (iii) within-pair case-control analysis separated by DZ and MZ. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. BMI (OR 1.12; 95% CI 1.02-1.26) and percent body fat (OR 1.15; 95% CI 1.01-1.32) were weakly associated with lifetime prevalence of chronic LBP in the total sample analysis but were absent when shared environment and genetic factors were adjusted for using the within-pair case-control analysis. Greater waist-hip ratios were associated with smaller prevalence estimates of chronic LBP in the within-pair case-control analysis with both MZ and DZ twins (OR 0.67; 95% CI 0.47-0.94). However, this association did not remain after the full adjustment for genetic factors in the MZ within-pair case-control analysis. BMI, percent of fat mass and greater depositions of fat and mass around the hips are associated with increases in chronic LBP prevalence in women but these associations are small and appear to be confounded by the effects of genetics and early shared environment. Therefore, our results do not support a causal direct relationship between obesity and chronic LBP.

Top-down silicon microcantilever with coupled bottom-up silicon nanowire for enhanced mass resolution

A stepped cantilever composed of a bottom-up silicon nanowire coupled to a top-down silicon microcantilever electrostatically actuated and with capacitive or optical readout is fabricated and analyzed, both theoretically and experimentally, for mass sensing applications. The mass sensitivity at the nanowire free end and the frequency resolution considering thermomechanical noise are computed for different nanowire dimensions. The results obtained show that the coupled structure presents a very good mass sensitivity thanks to the nanowire, where the mass depositions take place, while also presenting a very good frequency resolution due to the microcantilever, where the transduction is carried out. A two-fold improvement in mass sensitivity with respect to that of the microcantilever standalone is experimentally demonstrated, and at least an order-of-magnitude improvement is theoretically predicted, only changing the nanowire length. Very close frequency resolutions are experimentally measured and theoretically predicted for a standalone microcantilever and for a microcantilever-nanowire coupled system. Thus, an improvement in mass sensing resolution of the microcantilever-nanowire stepped cantilever is demonstrated with respect to that of the microcantilever standalone.

Modeling CaCO3 crystallization fouling on a heat exchanger surface – Definition of fouling layer properties and model parameters

Crystallization fouling occurs when dissolved salts precipitate from an aqueous solution to the walls of process equipment. In the case of inversely soluble salts, like CaCO3, this may lead to crystal growth on heated surfaces. In this study, crystallization fouling of CaCO3 on a flat-plate heat exchanger surface is studied. The mass deposition rates are determined from the measurements of the fouling thermal resistance and the properties of the porous fouling layer. The uncertainty of the fouling layer properties and the mass depositions rate are quantified with a detailed uncertainty analysis, which shows that the proposed method and experimental analysis provide values that are reasonably defined and acceptable. The obtained mass deposition rates are used to determine the kinetic parameters of different fouling models using a regression analysis. The validation of the models against the experimental data shows that the closest correspondence between the experimental and modeled results occurs when the crystallization fouling is described by the surface integration model including the time scaling factor which depends on the flow velocity.

Salp-falls in the Tasman Sea: a major food input to deep-sea benthos

Large, fast-sinking carcasses (food-falls) are an important source of nutrition to deep-sea benthic communities. In 2007 and 2009, mass depositions of the salp Thetys vagina were observed on the Tasman Sea floor between 200 and 2500 m depth, where benthic crustaceans were observed feeding on them. Analysis of a long-term (1981 to 2011) trawl survey database determined that salp biomass (wet weight, WW) in the eastern Tasman Sea regularly exceeds 100 t km(-3) yr(-1), with biomasses as high as 734 t km(-3) recorded in a single trawl. With fast sinking rates, salp fluxes to the seafloor occur year-round. Salps, like jellyfish, have been considered to be of low nutritional value; however, biochemical analyses revealed that T. vagina has a carbon (31% dry weight, DW) and energy (11.00 kJ g(-1) DW) content more similar to that of phytoplankton blooms, copepods and fish than to that of jellyfish, with which they are often grouped. The deposition of the mean yearly biomass (4.81 t km(-2) WW) of salps recorded from the trawl database in the Tasman Sea represents a 330% increase to the carbon input normally estimated for this region. Given their abundance, rapid export to the seabed and high nutritional value, salp carcasses are likely to be a significant input of carbon to benthic food webs, which, until now, has been largely overlooked.

Ion Dispositions in Polyelectrolyte Multilayer Films

Polyelectrolyte multilayers (PEMs) fabricated through layer-by-layer.(LbL) assembly from sodium chloride containing solutions of poly(diallyldimethylammonium chloride) (PDDA) and poly(styrene sulfonate) (PSS) were examined by quartz crystal microbalance (QCM), QCM with dissipation (QCM-D), UV-vis spectroscopy, and X-ray photoelectron spectroscopy (XPS) to determine the dispositions of polyelectrolytes and counterions across the PEM thickness. The key experiment was dry film QCM, which by quantifying the incremental mass depositions during LbL assembly uncovered :excess polyelectrolyte charge and excess polyelectrolyte charge density as functions of deposition number. Counterion dispositions depended strongly on salt concentration, and trends in the two PEM charge parameters established three salt concentration regimes: zero to near zero salt ([NaCl] less than or similar to 0.1 M), low salt (0.1 M less than or similar to [NaCl] less than or similar to 0.75 M), and high salt ([NaCl] greater than or similar to 1.5 M]). The first two are associated with linear LbL growth while the latter is associated with exponential LbL growth. At zero salt, no counterions are present in the PEM bulk (middle), while at low salt, an excess of PDDA charge across the bulk coincides with an excess of counteranions. Differently, at high salt, deposited PSS permeates the PEM bulk, conveying an excess of countercations. At all salt concentrations, the PEM surface charge alternates according to the capping polyelectrolyte's identity. Accumulations of small ions in the PEM bulk can be ascribed to property asymmetries between the two deposited polyelectrolytes, but the roles played by different chain properties remain incompletely understood.

Systematic experimental study of the pollution deposition impact on the energy yield of photovoltaic installations

The current study experimentally investigates the performance of two identical pairs of photovoltaic (PV) panels, the first being clean and the second being artificially polluted with three different, commonly met in urban and other environments, air pollutants (i.e. red soil, limestone and carbonaceous fly-ash particles). The PV-panels under comparison are both operating under the same environmental conditions, being nearby located and adjusted at the same inclination. The effect of pollution deposition on PVs’ power output, energy yield and conversion efficiency is examined, considering also various pollutants’ mass depositions on the PV-panels’ surfaces. According to the results obtained, a considerable reduction of PVs’ energy performance is recorded, depending both on particles’ composition and origin and on the total mass accumulated on the PV-panels’ surfaces. Based on the results, the highest reduction is caused by the deposition of red soil particles, followed by the deposition of limestone and finally by the carbon-based ash.

Ash deposition impact on the energy performance of photovoltaic generators

A little known side effect of the atmospheric air pollution is the degradation of photovoltaic (PV) cells’ performance due to the deposition of solid particles varying in composition, size and origin. In this context, an experimental-based investigation is conducted in order to compare the energy performance of two identical pairs of PV-panels; the first being clean and the second being artificially polluted with ash, i.e. a by-product of incomplete hydrocarbons’ combustion mainly originating from thermal power stations and vehicular exhausts. A series of systematic measurements of current intensity, voltage output and solar radiation are executed simultaneously for the clean and the polluted PV-panel, so that the effect of several mass depositions on the PVs’ power output, energy yield and conversion efficiency may be determined. According to the results, a considerable deterioration of the PV-panels’ performance is obtained, i.e. almost 30% energy reduction per hour or 1.5% efficiency decrease (in absolute terms) for ash accumulation on the panels’ surface reaching up to 0.4 mg/cm 2.

Substrates for zero temperature coefficient Love wave sensors

Microacoustic Love wave delay lines show high sensitivity to perturbations such as mass depositions on the wave-guide surface. Furthermore, because of their shear polarization, Love waves are ideally suited for liquid sensing applications. Using a Love wave delay line as feedback element in an oscillator allows the realization of viscosity sensors, and, using a chemical interface, chemical sensors, where the output signal is the oscillation frequency. To achieve a high effective sensitivity, the cross-sensitivity to temperature has to be kept low. We outline the proper choice of a material and especially focus on the influence of crystal cut and the major device design parameters (mass sensitivity and coupling coefficient) on the temperature coefficient of the sensor.

The fate of CO 2 sequestered in the deep ocean

Based on published phase diagrams, laboratory and in situ observations we predict that liquid CO 2 released from a diffuser below 500 m depth in the ocean will form solid hydrate particles of composition CO 2·6H 2O with bulk density 1.1 gcm −3 . Being heavier than seawater the hydrate particles will sink to the ocean bottom. The sedimentation rate w depends on the particle diameter, drag coefficient, and the difference between particle and seawater bulk density. For particles in the size range 10 −5-10 −3 m, w=5×10 −6−0.02 ms −1. The dispersion of the particles on the ocean bottom also depends on the distance between the diffuser and the ocean bottom and the turbulent characteristics of the water column. For the above particle size range and a fall distance of 500 m, the median radius of the mound varies from 1 km for large particles to more than 500 km for small, slowly falling particles For a 500 MW(el) coal fired power plant with a discharge rate of 170 kgs −1 of CO 2, these parameters correspond to mass depositions of 4×10 −3−1×10 3 kgm −2 yr −1 at the plume centerline, or mound thicknesses that grow at rates of 4×10 −6−1 myr −1. Hydrate particles may (1) interfere with the feeding habits of swimming creatures as they descend and (2) bury benthic organisms as they deposit to the ocean floor.

Characteristics of radioactive aerosols generated from a hot nuclear fuel sample

As a part of the CANDU ∗ ∗ CANDU (Canada Deuterium Uranium) is a registered trademark of AECL. reactor safety research program on the release, transport and deposition of fission products in the primary cooling system during a postulated accident, data have been obtained on the physical and chemical characteristics of aerosols generated in an experiment by heating a Zircaloy-4 clad, irradiated CANDU fuel sample in a flowing gas mixture of steam plus argon. This paper describes the aerosol collection and the results obtained from a post-test analysis of the radioactive aerosols, including the elemental composition of the aerosol mass, particle sizes, shapes, and fractional mass depositions along the flow path.

Seagrass wrack-induced dune formation on a tropical coast (Banc d'Arguin, Mauritania)

The Banc d'Arguin (Mauritania) is a shallow water area with mudflats bordering on the Sahara desert. Mass depositions of seagrass litter were observed on some parts of the shore. Soil profiles of the low dune formations separating the flood debris zone from the desert showed that layers of seagrass detritus, in various stages of decay, extended under the dune formations. The tentative mechanism of dune formation, involving the interacting processes of beaching of seagrass litter and wind-blown transport of desert sediment in a seaward direction, is described. This role in dune formation adds a new element to the significance of seagrass vegetation for the coastal environment.

Cool Infalling Gas and its Interaction with the Hot Ism of Elliptical Galaxies

AbstractWe describe work leading to the suggestion that interaction between infalling cool gas and ambient hot, coronal plasma in elliptical galaxies is responsible for emission filaments, and might remove the need for large mass depositions in cooling flows. A test of the hypothesis is undertaken — the run of surface brightness with radius for the emission lines — and the prediction agrees well with the data.

European Corn Borer (Lepidoptera: Pyralidae) Infestations: Predicting Second Generation Egg Masses from Blacklight Trap Captures and Relating Their Abundance to Several Corn Crop Characters

Investigations conducted at Waseca, Minn., during 1981 and 1982 indicated that European corn borer, Ostrinia nubilalis (Hubner), egg mass counts were related to crop maturity and planting date when a significant range in these variables was present. Egg mass counts were related to first generation shot holes when a significant range in crop maturity and planting date was absent. Egg mass counts were not related to crop height, yield, plant population, or soil type under the conditions of this study. A significant simple linear relationship existed between egg mass depositions and blacklight trap captured females in 1981. A significant range in crop maturity and planting date, however, necessitated incorporating these variables into the 1982 egg mass prediction model.

European Corn Borer (Lepidoptera: Pyralidae) Infestations: Relating Captures in Pheromone and Black-light Traps in Southern Minnesota Cornfields

A significant relationship existed between second-flight European corn borer (ECB), Ostrinia nubilalis (Hubner), females captured in black-light traps (BLT) and pheromone traps (PT) under low population densities in 1981 and 1982. Results of our experiments also suggested that the black-light and pheromone traps measured different responses from male moths. A two-step model was proposed for predicting ECB egg mass depositions in specific corn fields based on captures in PT.