Particle Mass Research Articles

Human health impacts and indoor chemical reactions of VOCs from cleaning products and occupants

Occupants and indoor activities are sources of volatile organic compounds (VOCs). We propose a framework to simulate the pollutant pathway using the INCA-Indoor© model and VOC emission rates to derive dynamic concentrations, and the USEtox model to evaluate health impacts in DALYs (Disability-Adjusted Life Years). The applicability of the framework is tested on a case study, and the effect of indoor chemical reactions on health impacts is assessed. In this case study, health impacts were of 0.3 μDALY/day without and 0.4 μDALY/day (13 s/day) with indoor air chemistry (+28 %) out of which 12 % were linked to occupant breath and skin emissions. Cleaning activities led to the highest impacts without chemical reactions (terpinolene, responsible for 0.14 μDALY/day), but indoor air chemistry led to high impacts linked to formaldehyde formation (0.18 μDALY/day). These reactions led to the formation of more formaldehyde, hence leading to 20% more impacts, in summer than in winter. Occupants’ contribution to CO2 concentrations exceeded recommended limits under the given occupancy and ventilation scenario. Secondary organic aerosol (SOA) formation affected indoor particulate matter mass concentrations by up to a factor 1.2 and their number concentrations by up to a factor 25,000 in the presence of VOC emissions. Results of this study indicate that chemical reactions and SOA formation are important factors to consider in indoor air quality impact assessment. A larger number of activities and scenarios can be tested to improve the robustness of the conclusions, since, under different scenarios (for e.g. activities with lower emission rates) and with more complete toxicity data, these conclusions are likely to change.

An analytical model to predict the mass loading of air cleaners in typical indoor environments and to estimate the service interval from standardized filter loading tests

For indoor air cleaners, especially those using electret filters, it is known that the clean air delivery rate (CADR) can strongly decrease over time due to loading of the filters with particles. Standardized tests like in GB/T 18801 are used to determine the mass of test aerosol particles leading to a reduction of the initial CADR by 50 % (cumulative clean mass), but this method does not allow to draw conclusions on when this reduction is reached in a typical indoor environment. However, a good estimate would help manufactures to give reasonable recommendations in which intervals a service of the air cleaner becomes necessary. Therefore, we developed an analytical model including the most relevant parameters of a typical indoor environment and assumed different courses for the time-dependent decay of the CADR. We show that consistent estimates for the service interval can be derived, which do only slightly depend on the exact choice of the model. However, we partially find pronounced differences between scenarios dominated by either indoor or outdoor sources. We compare the new model to the model of GB/T 18801 and show that the standard overestimates the service interval for a given set of parameters by about 30 %. We finally propose a method for estimating the service interval from only one loading and one discharging step and give perspectives for further applications of the model.

Search for photons above 1018 eV by simultaneously measuring the atmospheric depth and the muon content of air showers at the Pierre Auger Observatory

The Pierre Auger Observatory is the most sensitive instrument to detect photons with energies above 1017 eV. It measures extensive air showers generated by ultrahigh energy cosmic rays using a hybrid technique that exploits the combination of a fluorescence detector with a ground array of particle detectors. The signatures of a photon-induced air shower are a larger atmospheric depth of the shower maximum (Xmax) and a steeper lateral distribution function, along with a lower number of muons with respect to the bulk of hadron-induced cascades. In this work, a new analysis technique in the energy interval between 1 and 30 EeV (1 EeV=1018 eV) has been developed by combining the fluorescence detector-based measurement of Xmax with the specific features of the surface detector signal through a parameter related to the air shower muon content, derived from the universality of the air shower development. No evidence of a statistically significant signal due to photon primaries was found using data collected in about 12 years of operation. Thus, upper bounds to the integral photon flux have been set using a detailed calculation of the detector exposure, in combination with a data-driven background estimation. The derived 95% confidence level upper limits are 0.0403, 0.01113, 0.0035, 0.0023, and 0.0021 km−2 sr−1 yr−1 above 1, 2, 3, 5, and 10 EeV, respectively, leading to the most stringent upper limits on the photon flux in the EeV range. Compared with past results, the upper limits were improved by about 40% for the lowest energy threshold and by a factor 3 above 3 EeV, where no candidates were found and the expected background is negligible. The presented limits can be used to probe the assumptions on chemical composition of ultrahigh energy cosmic rays and allow for the constraint of the mass and lifetime phase space of super-heavy dark matter particles. Published by the American Physical Society 2024

Accumulation kinetics of polystyrene nano- and microplastics in the waterflea Daphnia magna and trophic transfer to the mysid Limnomysis benedeni

Despite the pervasive presence of nano- and microplastics (NMPs) in aquatic environments, their movement through food chains remains poorly understood. In this study, we explored the uptake of polystyrene plastics (PSPs) of varying sizes (26, 500, and 4800 nm) in Daphnia magna and their subsequent transfer to the freshwater mysid Limnomysis benedeni, shedding light on the intricate dynamics of NMP transfer in freshwater ecosystems. Our results show that in D. magna the internal concentration of 4800 nm PSPs was 4–10 times higher than that of 26 and 500 nm PSPs, respectively. The uptake rate constants in daphnids decreased in the following order: 4800 nm (2.4 ± 0.5 L/g·h) > 26 nm (1.7 ± 0.4 L/g·h) > 500 nm (0.6 ± 0.1 L/g·h) PSPs. Importantly, only a small fraction (1–5 %) of the PSPs ingested by D. magna was transferred to L. benedeni. Additionally, larger particle sizes were associated with a higher extent of transfer in the food chain. Elimination rate constants in L. benedeni were found to be 0.03 ± 0.03, 0.1 ± 0.2, and 0.2 ± 0.8 per hour for 26, 500, and 4800 nm PSPs, respectively. Fluorescence observations revealed that PSPs were predominantly located in the stomach and intestine of L. benedeni. Furthermore, the calculated trophic transfer factor, based on the mass of particles accumulated in the organisms, was <1 for all PSP treatments. Our results indicate that NMPs can be transferred along the daphnia-mysids food chain, and that there is no evidence of biomagnification along this chain. These findings underscore the importance of understanding particle size effects on NMP transfer and accumulation in aquatic food webs, offering valuable insights for assessing the ecological risks associated with NMP pollution in freshwater ecosystems.

Moduli spaces in CFT: large charge operators

Using the large-charge expansion, we prove a necessary condition for a CFT to exhibit conformal symmetry breaking, under the assumption that a continuous global symmetry is also broken on the moduli space: there must be a tower of charged local operators whose scaling dimensions are asymptotically linear in the charge. In supersymmetric theories with a continuous R-symmetry and a holomorphic moduli space, the existence of such a tower of operators follows trivially from a BPS condition: their scaling dimensions are then exactly linear in the R-charge. We illustrate the more general statement in several examples of three-dimensional N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{N} $$\\end{document} = 1 CFTs, where the leading linear behavior receives nontrivial corrections. By considering a suitable scaling limit, we also relate the spectrum of states with large charge on the cylinder (isomorphic to local operators) to the spectrum of massive particles on the moduli space.

Effects of nonthermality on dust-acoustic surface waves with dust rotation

Abstract Dust Acoustic Surface Waves (DASWs) real frequency and group velocity are investigated for semi-bounded dusty plasma whose electrons and ions are modeled by Cairn s Distribution Function (CDF) while massive particles i.e. dust are treated Maxwellian. Kinetic approach based on Vlasov-Poisson s set of equations is used for the derivation of plasma dispersion relation. It is observed that in the presence of rotational parameter r and the variation of nonthermal index α affect both real frequency and group velocity of the wave significantly. This study has wide astrophysical applications.&amp;#xD;

DMRG study of the theta-dependent mass spectrum in the 2-flavor Schwinger model

We study the θ-dependent mass spectrum of the massive 2-flavor Schwinger model in the Hamiltonian formalism using the density-matrix renormalization group (DMRG). The masses of the composite particles, the pion and sigma meson, are computed by two independent methods. One is the improved one-point-function scheme, where we measure the local meson operator coupled to the boundary state and extract the mass from its exponential decay. Since the θ term causes a nontrivial operator mixing, we unravel it by diagonalizing the correlation matrix to define the meson operator. The other is the dispersion-relation scheme, a heuristic approach specific to Hamiltonian formalism. We obtain the dispersion relation directly by measuring the energy and momentum of the excited states. The sign problem is circumvented in these methods, and their results agree with each other even for large θ. We reveal that the θ-dependence of the pion mass at m/g = 0.1 is consistent with the prediction by the bosonized model. We also find that the mass of the sigma meson satisfies the semi-classical formula, Mσ/Mπ = 3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{3} $$\\end{document}, for almost all region of θ. While the sigma meson is a stable particle thanks to this relation, the eta meson is no longer protected by the G-parity and becomes unstable for θ ≠ 0.

Discovery of Limb Brightening in the Parsec-scale Jet of NGC 315 through Global Very Long Baseline Interferometry Observations and Its Implications for Jet Models

We report the first observation of the nearby giant radio galaxy NGC 315 using a global very long baseline interferometry (VLBI) array consisting of 22 radio antennas located across five continents, including high-sensitivity stations, at 22 GHz. Utilizing the extensive u v-coverage provided by the array, coupled with the application of a recently developed superresolution imaging technique based on the regularized maximum-likelihood method, we were able to transversely resolve the NGC 315 jet at parsec scales for the first time. Previously known for its central ridge-brightened morphology at similar scales in former VLBI studies, the jet now clearly exhibits a limb-brightened structure. This finding suggests an inherent limb brightening that was not observable before due to limited angular resolution. Considering that the jet is viewed at an angle of ∼50°, the observed limb brightening is challenging to reconcile with the magnetohydrodynamic models and simulations, which predict that the Doppler-boosted jet edges should dominate over the nonboosted central layer. The conventional jet model that proposes a fast spine and a slow sheath with uniform transverse emissivity may pertain to our observations. However, in this model, the relativistic spine would need to travel at speeds of Γ ≳ 6.0–12.9 along the deprojected jet distance of (2.3–10.8) × 103 gravitational radii from the black hole. We propose an alternative scenario that suggests higher emissivity at the jet boundary layer, resulting from more efficient particle acceleration or mass loading onto the jet edges, and consider prospects for future observations with even higher angular resolution.

Internal and surface temperature profiles of spherical biosolids particles during convective drying

The convective drying of spherical biosolids particles from two wastewater treatment plants (Type 1: anaerobic/anoxic treatment with belt filter press dewatering; Type 2: aerobic/anoxic treatment with centrifuge dewatering) was studied under 10 conditions across 44 trials. A wide spectrum of conditions including three drying temperatures (88, 109, and 138 ° C ), two gas velocities (1.6 and 2 m s − 1 ), and particle sizes of 2 cm and 4 cm were investigated. Measured variables included particle mass, center/internal temperature, surface temperature, shrinkage, and qualitative observations of morphological changes. Most samples showed two drying periods, a constant rate period followed by a falling rate period. Additionally, it was found that drying rates and morphological changes depended significantly on particle size and drying intensity (i.e., drying gas temperature and gas velocity) with higher intensities resulting in larger, more porous particles. Internal temperature profiles displayed a consistent pattern, an initial heating phase where internal temperatures quickly rose to approximately the wet bulb temperature of the drying gas, a quasi-constant temperature phase at that temperature, and a final sharp increase/spike to reach equilibrium with the drying gas temperature. Moreover, IR images showed that sub-surface temperatures (between the core and surface) were significantly lower than surface temperatures. Surface temperatures showed a more linear increase throughout drying until equilibrium with the drying gas temperature. The consistent temperature difference between the center and surface, as well as the internal temperature profile, suggests the existence of a drying front, moving radially inward as the particle dries. This research contributes to a better understanding of biosolids drying dynamics, offering insights to improve thermal treatment strategies thereby contributing to the broader field of waste management.

Light-absorbing black carbon and brown carbon components of smoke aerosol from DSCOVR EPIC measurements over North America and central Africa

Abstract. Wildfires and agricultural burning generate seemingly increasing smoke aerosol emissions, impacting societal and natural ecosystems. To understand smoke's effects on climate and public health, we analyzed the spatiotemporal distribution of smoke aerosols, focusing on two major light-absorbing components, namely black carbon (BC) and brown carbon (BrC) aerosols. Using NASA's Earth Polychromatic Imaging Camera (EPIC) instrument aboard NOAA's Deep Space Climate Observatory (DSCOVR) spacecraft, we inferred BC and BrC volume fractions and particle mass concentrations based on spectral absorption provided by the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm with 1–2 h temporal resolution and ∼ 10 km spatial resolution over North America and central Africa. Our analyses of regional smoke properties reveal distinct characteristics for aerosol optical depth (AOD) at 443 nm, spectral single-scattering albedo (SSA), aerosol layer height (ALH), and BC and BrC amounts. Smoke aerosols in North America showed extremely high AOD up to 6, with elevated ALH (6–7 km) and significant BrC components up to 250 mg m−2 along the transport paths, whereas the smoke aerosols in central Africa exhibited stronger light absorption (i.e., lower SSA) and lower AOD, resulting in higher-BC mass concentrations and similar BrC mass concentrations than the cases in North America. Seasonal burning source locations in central Africa, following the seasonal shift in the Intertropical Convergence Zone and diurnal variations in smoke amounts, were also captured. A comparison of retrieved AOD443, SSA443, SSA680, and ALH with collocated AERONET and CALIOP measurements shows agreement with RMSE values of 0.2, 0.03–0.04, 0.02–0.04, and 0.8–1.3 km, respectively. An analysis of the spatiotemporal average reveals distinct geographical characteristics in smoke properties closely linked to burning types and meteorological conditions. Forest wildfires over western North America generated smoke with a small-BC volume fraction of 0.011 and a high ALH with large variability (2.2 ± 1.2 km), whereas smoke from wildfires and agricultural burning over Mexico region shows more absorption and low ALH. Smoke from savanna fires over central Africa had the most absorption, with a high-BC volume fraction (0.015) and low ALH with a small variation (1.8 ± 0.6 km) among the analyzed regions. Tropical forest smoke was less absorbing and had a high variance in ALH. We also quantify the estimation uncertainties related to the assumptions of BC and BrC refractive indices. The MAIAC EPIC smoke properties with BC and BrC volume and mass fractions and assessment of the layer height provide observational constraints for radiative forcing modeling and air quality and health studies.

A field investigation of 3 masks proposed as respiratory protection for wildland firefighters: a randomized controlled trial in British Columbia, Canada.

Wildland firefighters are exposed through the lungs and skin to particulate matter, fumes, and vapors containing polycyclic aromatic hydrocarbons (PAH). Wearing respiratory protection should reduce pulmonary exposure, but there is uncertainty about the most effective and acceptable type of mask. Firefighters from 6 unit crews working with the British Columbia Wildfire Service were approached and those consenting were randomly allocated within each crew to a "no mask" control group or to use 1 of 3 types of masks: X, half-face respirator with P100/multi gas cartridge; Y, cloth with alpaca filter; Z mesh fabric with a carbon filter. Crews were followed for 3 consecutive firefighting days. The mask allocated was constant for each firefighter throughout. All participants completed a brief questionnaire at the start and end of each day, giving information on mask use, respiratory symptoms, and assessment of mask qualities. Spot urine samples were collected pre and post shift to assess 1-hydroxypyrene (1-HP) concentration as an indicator of total PAH absorption. Skin wipe samples from the hands and throat were collected pre and post shift and analyzed for PAH concentration. On each day monitored, 4 participants carried sampling pumps to measure total particulates and PAHs on particles and in vapor phase. The primary outcome was the concentration of urinary 1-HP at the end of the fire day. Secondary outcomes were changes in respiratory and eye symptoms during the course of the shift, reported mask use, and perception of mask qualities. The analysis used a 3-level random intercept regression model that clustered observations within individuals and crews. We aimed to detect any relation of allocated mask type to the 4 outcomes, having allowed for estimated exposure. Information was collected from 89 firefighters, including 14 women: 49% (37/75) of male firefighters were bearded. Nineteen fire days were monitored for a total of 263 firefighter × days, 64 to 68 for each intervention group. The end of shift 1-HP was higher than the start of the shift. Urinary 1-HP was more strongly related to PAHs on the skin than in the breathing zone. Men with beards had higher end-of-shift urinary log 1-HP/creat (ng/g) than other firefighters. None of the groups allocated a mask had lower 1-HP than the no-mask group, either in the study group overall or when stratified by beard-wearing. Among those without either beards or a failed fit-test, Mask Z reduced at the end of shift 1-HP where airborne PAH concentration was high. End-of-shift symptoms were related to particle mass in the breathing zone but was not mitigated by any of the masks. Hours electing not to wear a mask increased from the first to third shift for all mask types. Mask Z was rated as more comfortable than other types. Mask X was rated highest on fit and perceived protection. Mask Y gained the lowest ratings on fit, comfort and feelings of protection. Allocated masks did not provide protection overall, but the results highlighted the need for a wider understanding of the circumstances in which wearing efficient protection is well-advised.

Optimization and analysis of the inflow distribution influence on the middle discharge blow tank pneumatic conveying characteristics

The influence of different inflow gas distribution modes on the pneumatic conveying characteristics of the middle discharge blow tank was studied using an in-house pneumatic conveying experimental setup. The flow rates of pressurized gas, supplementary gas, and fluidized gas were varied in this study. The gas distribution mode was then optimized to improve the energy efficiency of the blow tank of a pneumatic conveying system. The results show that the particle mass flow rate, the solid-to-gas ratio, and the pressure drop increase first and then decrease with the pressurized gas and fluidized gas valves opening. In the case of supplementary gas, the particle mass flow rate and solid-to-gas ratio increase first and then decrease. However, an opposite trend is observed for the pressure drop, which decreases first and then increases. The results highlighted that the optimized gas distribution mode increases the mass flow rate of particles and the solid-to-gas ratio by 28.48% and 15.15%, respectively. The pressure drop of the blow tank has also increased slightly, by 0.88%. Therefore, the delivery capacity and efficiency of the middle discharge blow tank are greatly improved at the cost of a slight increase in energy consumption.

CFD–DEM modeling of particle segregation behavior in a simulated flash smelting furnace

Particle behavior plays a crucial role in flash smelting furnaces, but limited understanding is hindering further development of this modern pyrometallurgical process. This study presents a two-way coupled CFD–DEM approach to investigate particle distribution, collision, and segregation behaviors within a furnace. The simulation results are validated against experimental data, demonstrating good agreement. The effects of the particle mass–flow rate and size distribution are then analyzed. The results indicate that small particles are carried by airflows to the center of the particle-dense region, whereas large particles remain at the outer part, worsening segregation. Increasing the mass–flow rate significantly increases the particle number density and number of particle collisions but barely influences size-induced segregation. In contrast, enlarging the size of fed particles reduces particle number density and broadens dense distribution within a safe range. This ensures the necessary space and high mixing index of the particles, which benefits high-rate smelting processes.

A novel partition function for elementary particles

Three different partition functions are well-known and described in statistical physics. Here, a novel partition function for the description of intra-particular interactions and with this for the mass of particles is presented below. In statistical physics, three different partition functions are already well-established. These are the microcanonical, the canonical, and the macro-canonical partition functions. Here a fourth, novel partition function is added to these already well-established three. Thereby due to the properties of quantum mechanics and superposition, this novel partition function is of fundamental different nature. According to this concept, the new partition function for particles is first defined. The masses and energies of the elementary particles are then calculated using this novel partition function. The energy of an elementary particle is proportional to the mass on the one hand and to the novel partition function on the other. The constant of proportionality with respect to the new partition function is found to be identical with Rydberg constant and Rydberg energy. The relationships found for the proton, the electron, and the sigma particle are then generalized to all elementary particles.

Investigation on spectroscopy characteristics of different metamorphic degrees of coal-based graphite

To gain insights into the spectroscopy characteristics from coal to graphite, we investigated different metamorphic degrees of coal-based graphite which were collected from Hunan Province China. In this paper, by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy, graphite with different metamorphism degrees has been characterized to explore the evolution of macromolecular structure of organic matter during graphitization. The results show that with the increase of metamorphism degree, the 002-diffraction peak of the series of samples gradually shrinks and narrows, and the peak intensity becomes stronger, indicating that the microcrystalline structure gradually becomes regular and ordered. As the degree of graphitization increase, the uniformity of particle size in coal samples observed gradually increases, and the morphology becomes more regular, transitioning from disordered and irregular shapes to a structured large-scale flake pattern. The crystallinity improves, and the massive coal particles gradually coalesce into large plate crystals, with the inter-particle pores gradually closing. The graphite structure becomes increasingly evident. The FTIR spectra show that as the degree of graphitization increases, the peak at 1,581 cm−1 corresponding to C=C vibrations gradually intensifies. Some inert functional groups are retained throughout the graphitization process. The pores between coal particles gradually close, and the morphology of graphite particles becomes more regular and ordered. Additionally, during the graphitization process, structures similar to carbon nanotubes may develop. Throughout the structural transformation from coal macromolecules to graphite crystals, the size of the sp2 planar domains in single-layer graphene increases, and the lattice structure of carbon atoms gradually enlarges. These findings contribute to a comprehensive understanding of the properties and characteristics of coal-derived graphite, and can provide theoretical reference and basis for the metallogenic mechanism of coal-derived graphite and the efficient utilization of coal.

Sectoral Size‐Resolved Particle Number Emissions With Speciation: Emission Profile‐Based Quantification and a Case Study in the Yangtze River Delta Region, China

AbstractSizes and number concentrations are critical parameters for the impact of atmospheric particles on climate and human health. However, comprehensive studies focusing on size‐resolved particle number (PN) emissions from various sectors are scarce. This study aims to fill this research gap by developing sectoral size‐resolved PN emissions for major species including sulfate, organic mass (OM), and black carbon (BC). The size‐resolved emission profiles derived from various measurements in the literature were integrated with a particle mass emission inventory (EI) for 13 major sectors in the Yangtze River Delta region of China as a case study. The particle number size distribution (PNSD) of emitted particles exhibited two distinct peaks: one at approximately 10 nm and the other in the range of 40–60 nm. The primary contributors to PN emissions in the region in 2017 were power plants, gasoline vehicles, diesel vehicles, and cooking sources. In terms of species, OM dominated PN emissions, followed by primary sulfate and then BC. A regional size‐resolved aerosol model employing the size‐resolved PN EI developed here (referred to as the BIN‐SPE experiment) provided reasonably accurate temporal variations of the total PN concentration and captured the PNSD within the size range of 10–300 nm. Uncertainty analysis of sectoral PN emissions across size ranges was carried out and the performance of the BIN‐SPE experiment was compared with those of three commonly used PN emission parameterizations. Our model evaluations highlight future needs for in‐depth investigations into more advanced size‐resolved emissions and secondary OM formation mechanisms.

Impact of seasonal changes and environmental conditions on suspended and inhalable microplastics in urban air

Microplastics (MPs) are ubiquitous environmental pollutants extensively detected in atmospheric environments. Airborne MPs have raised concerns due to their transport and potential health risks of inhalation exposure. However, the factors influencing airborne MPs, particularly their concentrations and shapes suspended in urban air, remain unclear. We investigated MPs in total suspension particles with one-year measurements in Taipei City and identified their features using Nile Red staining combined with fluorescence microscopy and micro-Fourier transform infrared (μFTIR) spectroscopy. This study quantified the mean number concentration of total MPs as approximately 6.0 #/m³. We observed that MP abundance varied seasonally, with higher levels in the warm season than in the cold. A similar trend was noted for polymer types. Fragment-like MPs were the predominant shape, mainly found in polystyrene (PS), polyethylene (PE), and polypropylene (PP), while fibrous MPs, detected mostly as polyethylene terephthalate (PET) and polyamide (PA), were primarily observed at sizes greater than 300 μm. Both fiber and fragment-like MPs were positively associated with particle mass concentration, temperature, ultraviolet (UV) index, and wind speed, but negatively correlated with relative humidity and rainfall. Fibrous MPs were more affected by environmental factors than fragment-like MPs. Meteorological changes significantly influenced suspended MPs more than human activity within the city.

Constraints on Metastable Dark Energy Decaying into Dark Matter

We revisit the proposal that an energy transfer from dark energy into dark matter can be described in field theory by a first order phase transition. We analyze a metastable dark energy model proposed in the literature, using updated constraints on the decay time of a metastable dark energy from recent data. The results of our analysis show no prospects for potentially observable signals that could distinguish this scenario from the ΛCDM. We analyze, for the first time, the process of bubble nucleation in this model, showing that such model would not drive a complete transition to a dark matter dominated phase even in a distant future. Nevertheless, the model is not excluded by the latest data and we confirm that the mass of the dark matter particle that would result from such a process corresponds to the mass of an axion-like particle, which is currently one of the best motivated dark matter candidates. We argue that extensions to this model, possibly with additional couplings, still deserve further attention as it could provide an interesting and viable description for an interacting dark sector scenario based in a single scalar field.

Dark Matter-Dark Energy as Massive Bosons a Quantum Multi-Entanglement System with Dark Matter or Dark Energy as Some Massive Bosons-String Particles of Spin 2

A quantum multi-entanglement system with Dark matter or dark energy as some massive bosons-string particles of spin 2. Dark matter or dark energy are some particles of spin 2 instead of near spin 0 ones.

Cold idle vs hot idle: Gaseous and particulate emissions using a third-generation oxygenated biofuel

Engine idling is a significant contributor to vehicle emissions, however, it is often unaccounted for. Presented in this study is a comprehensive analysis of gaseous and particulate emissions during cold idle compared to hot idle operations. Fuels used in this study were B20 (20 %) and B10 (10 %) (%v/v) blends of di-octyl phthalate (a third-generation microalgae-based biofuel) and ultra-low sulphur diesel (B00), used as a reference fuel. Compared to cold idle operation, hydrocarbon (HC) emissions during hot idle showed marginal variation (±10 %) using blended fuels, and a significant increase (+55 %) using B00. Compared to cold idle operation, hot idle showed increased oxides of nitrogen (NOx) emissions, using all fuels (with a more significant increase shown using B00). During cold idle, particle concentrations (PNT) were 50–65 % higher using the blended fuels, compared to B00; however, during hot idle, the (PNT) using the blended fuels were one order of magnitude lower than B00. During cold idle operation, the average particle count mean diameter (CMD) in the Lower Aitken and Aitken modes was 5–10 % and 20–30 % higher using blended fuels, compared to B00, respectively. Higher CMD with the blended fuels during the cold idle operation caused a higher percentage increase in the particle mass (PMT), compared to B00. Sub-23 particles (<23 nm) were observed during cold and hot idle operations, using all fuels.