Analysis of hydrogen fueling, recycling, and confinement at Wendelstein 7-X via a single-reservoir particle balance

A single-reservoir particle balance for the main plasma species hydrogen has been established for Wendelstein 7-X (W7-X). This has enabled the quantitative characterization of the particle sources in the standard island divertor configuration for the first time. Findings from attached scenarios with two different island sizes with a boronized wall and turbo molecular pumping are presented. Fueling efficiencies, particle flows and source locations were measured and used to infer the total particle confinement time $\tau_{\rm{p}}$. Perturbative gas injection experiments served to measure the effective particle confinement time $\tau_{\rm{p}}^*$. Combining both confinement times provides access to the global recycling coefficient $\bar{R}$. Hydrogen particle inventories have been addressed and the knowledge of particle sources and sinks reveals the core fueling distribution and provides insight into the capability of the magnetic islands to control exhaust features. Measurements of hydrogen fueling efficiencies were sensitive to the precise fueling location and measured between 12~\% and 31~\% with the recycling fueling at the strike line modeled at only 6~\%, due to much higher densities. 15~\% of the total \SI{5.2E+22}{a/s} recycling flow ionizes far away from the recycling surfaces in the main chamber. It was shown that 60~\% of recycled particles ionize above the horizontal and 18~\% above the vertical divertor target, while the remainder of the recycling flow ionizes above the baffle (7~\%). Combining these source terms with their individual fueling efficiencies resolves the core fueling distribution. Due to the higher fueling efficiency in the main chamber, up to 51~\% of the total \SI{5.1E+21}{1/s} core fueling particles are entering the confined plasma from the main chamber. $\tau_{\rm{p}}$ values in the range of 260 ms were extracted for these discharges. Together with $\tau_{\rm{p}}$, the global recycling coefficient $\bar{R}$ was resolved for every $\tau_{\rm{p}}^*$ measurement and a typical value close to unity was obtained. An increase of the island size, resulted in no change of $\tau_{\rm{p}}$, but doubled $\tau_{\rm{p}}^*$, indicating the feasibility of the control coils as an actuator to control exhaust features without affecting core confinement properties.

Measurement report: Three years of size-resolved eddy-covariance particle number flux measurements in an urban environment

Size-resolved particle number fluxes in the size range of 10 nm < particle diameter (Dp) < 200 nm were measured over a 3-year period (April 2017–March 2020) using the eddy-covariance technique at an urban site in Berlin, Germany. The observations indicated the site as a net source of particles with a median total particle number flux of FTNC=0.86 × 108 m−2 s−1. The turbulent surface–atmosphere exchange of particles was clearly dominated by ultrafine particles (Dp < 100 nm) with a share of 96 % of total particle number flux (FUFP=0.83 × 108 m−2 s−1). Annual estimates of median FTNC and FUFP slightly decreased by −9.6 % (−8.9 % for FUFP) from the first to the second observation year and a further −5.9 % (−6.1 % for FUFP) from the second to the third year. The annual variation might be due to different reasons such as the variation of flux footprints in the individual years, a slight reduction of traffic intensity in the third year, or a progressive transition of the vehicle fleet towards a higher share of low-emission standards or electric drive. Size-resolved measurements illustrated events of bidirectional fluxes, i.e. simultaneous emission and deposition fluxes within the size spectrum, which occurred more often in spring, late summer, and autumn than in winter. Multi-year observations of size-resolved particle fluxes proved to be important for a deeper understanding of particle exchange processes with the urban surface and the pronounced influence of traffic at this urban site.

Encapsulation of agrichemicals by renewable cellulosic derivatives

<p>Cellulose derivatives, charged with fungicides, have been prepared as particles for use as a wood preservative. The particles were designed to encapsulate the current industry-standard chemical agents used to minimise wood degrading fungal action and to deter termites. A detailed study on the most effective methodology that would be suitable for scaled-up production was undertaken. The methods explored included: double emulsions, solvent diffusion by dialysis membrane and phase inversion emulsification. Particles formed by these methods were characterised by scanning electron microscopy, dynamic light scattering, nuclear magnetic resonance spectroscopy and infrared spectroscopy. The fungicide incorporation was confirmed by nuclear magnetic resonance studies and gas-chromatography analytical analysis. The phase inversion emulsion process was found to be highly effective and readily manipulated to modify particle formation. Particles were successfully prepared containing fungicides in a yield of 35-75% (method dependant), containing the biocide at approximately 50% mass of biocide to total particle mass. Thus, this process was optimised through modifying the addition time of the aqueous phase, as well as variation of the surfactant and salt concentrations. With an optimised particle forming method, three fungicides were incorporated into the formulation and subsequently analysed to demonstrate successful biocide incorporation. The biocide charged mesoparticles underwent testing for antifungal action by our industrial partners Lonza.</p>

Encapsulation of agrichemicals by renewable cellulosic derivatives

<p>Cellulose derivatives, charged with fungicides, have been prepared as particles for use as a wood preservative. The particles were designed to encapsulate the current industry-standard chemical agents used to minimise wood degrading fungal action and to deter termites. A detailed study on the most effective methodology that would be suitable for scaled-up production was undertaken. The methods explored included: double emulsions, solvent diffusion by dialysis membrane and phase inversion emulsification. Particles formed by these methods were characterised by scanning electron microscopy, dynamic light scattering, nuclear magnetic resonance spectroscopy and infrared spectroscopy. The fungicide incorporation was confirmed by nuclear magnetic resonance studies and gas-chromatography analytical analysis. The phase inversion emulsion process was found to be highly effective and readily manipulated to modify particle formation. Particles were successfully prepared containing fungicides in a yield of 35-75% (method dependant), containing the biocide at approximately 50% mass of biocide to total particle mass. Thus, this process was optimised through modifying the addition time of the aqueous phase, as well as variation of the surfactant and salt concentrations. With an optimised particle forming method, three fungicides were incorporated into the formulation and subsequently analysed to demonstrate successful biocide incorporation. The biocide charged mesoparticles underwent testing for antifungal action by our industrial partners Lonza.</p>

Acute Toxicity of Cigarette from Vietnam on in vivo Model Zebrafish (Danio rerio) Larvae

Smoking is widely known to has a major contributor to public health issues both in worldwide and Vietnam. At the same time, Vietnam have a large number of smokers and the market is filled with diverse brand of tobacco products. In this study, we sampled 6 types of cigarette: ThangLong, Vina, Craven, Demi, Maxx and Bastos from local stores and conducted toxicological test on zebrafish larvae. Our results show that there are varied in toxicological properties of total particle matter collected from different cigarette brands in lethal and morphology effects on zebrafish embryos. LC50 of 6 brands after 96 hours of exposure were: ThangLong = 48.7 mg/L, Vina = 45.96 mg/L, Craven = 80.52 mg/L, Demi = 30.91 mg/L, Maxx = 83.54 mg/L and Bastos = 74.92 mg/L. They are lower than 100 mg/L, which put them under Category 2 and 3 in the GHS classification criteria for acute toxicity.

How many interstellar visitors are there in the Solar System?

По результатам краткого обзора наблюдений вошедших в Солнечную систему межзвездных пылинок, метеороидов и более крупных тел и на основе моделей, описывающих спектры масс таких тел, отмечен огромный разброс (много порядков величины) в оценках отношения η потока межзвездных частиц к общему потоку частиц в окрестности Земли и в целом в Солнечной системе. Этот разброс означает, что современные возможности не позволяют определенно ответить на вопрос в заголовке статьи. При анализе результатов наблюдений необходимо учитывать характер зависимости отношения η от размера частиц r, т. е. η(r). Эта зависимость определяется процессами генерации и динамической эволюции населения малых тел в Солнечной системе и за ее пределами. According to the results of a brief review of observations included in the Solar system, interstellar dust, meteoroids and larger bodies, and on the basis of models describing the spectra of the masses of these bodies, we mark a huge spread (many orders of magnitude) in estimates of the relationship η of the flow of interstellar particles to the total particle flux near the Earth and in the whole Solar system. These differences mean that modern capabilities do not allow us to definitely answer the question in the title of the article. When analyzing the results of observations, it is necessary to take into account the nature of the dependence of the ratio η on the particle size r, i.e. η(r). This dependence is determined by the processes of generation and dynamic evolution of the population of small bodies in the Solar system and beyond.

The Aerosol Research Observation Station (AEROS)

Information on atmospheric particles’ concentration and sizes are important for environmental and human health reasons. Air quality monitor stations (AQMSs) for measuring Particulate Matter (PM) concentrations are found across the United States, but only three AQMSs measure PM2.5 concentrations (particles with an aerodynamic diameter of < 2.5 μm) in the Southern High Plains of West Texas (area ≥ 1.8 × 105 km2). This area is prone to many dust events (~21 per year), yet no information is available on other PM sizes, total particle concentration, or size distribution during these events. The Aerosol Research Observation Station (AEROS) was designed to continuously measure these particles’ concentrations to better understand the impact of dust events on local air quality. The AEROS aerosol measurements unit features a temperature-controlled shed with a dedicated inlet and custom-built dryer for each of the three aerosol instruments used. This article provides a description of AEROS as well as an intercomparison of the different instruments using laboratory and atmospheric particles, which shows that the instruments used provided similar concentration measurements. Measurement with AEROS can distinguish between various pollution events (natural dust events vs anthropogenic haze) to improve knowledge of the air quality in this region.

Comparative analysis of the dust retention capacity and leaf microstructure of 11 Sophora japonica clones

We used fresh leaves of Sophora japonica L. variety ‘Qingyun 1’ (A0) and 10 superior clones of the same species (A1–A10) to explore leaf morphological characteristics and total particle retention per unit leaf area under natural and artificial simulated dust deposition treatments. Our objectives were to explore the relationship between the two methods and to assess particle size distribution, X-ray fluorescence (XRF) heavy metal content, and scanning electron and atomic force microscopy (SEM and AFM) characteristics of leaf surface microstructure. Using the membership function method, we evaluated the dust retention capacity of each clone based on the mean degree of membership of its dust retention index. Using correlation analysis, we selected leaf morphological and SEM and AFM indices related significantly to dust retention capacity. Sophora japonica showed excellent overall dust retention capacity, although this capacity differed among clones. A5 had the strongest overall retention capacity, A2 had the strongest retention capacity for PM2.5, A9 had the strongest retention capacity for PM2.5–10, A0 had the strongest retention capacity for PM>10, and A2 had the strongest specific surface area (SSA) and heavy metal adsorption capacity. Overall, A1 had the strongest comprehensive dust retention ability, A5 was intermediate, and A7 had the weakest capacity. Certain leaf morphological and SEM and AFM characteristic indices correlated significantly with the dust retention capacity.

Screening Coarse Airborne Dust for Lead-Rich Phase Occurrence during Characterisation of Particle Mineralogy, Chemistry and Provenance: Application to Deposits in the Vicinity of an Integrated Steelworks

A method has been developed to screen large numbers (~103–104 per sample) of coarse airborne dust particles for the occurrence of Pb-rich phases, together with quantification of the particles’ mineralogy, chemistry, and inferred provenance. Using SEM-EDS spectral imaging (SI) at 15 kV, and processing with the custom software PARC, screening of individual SI pixels is performed for Pb at the concentration level of ~10% at a length-scale of ~1 µm. The issue of overlapping Pb-Mα and S-Kα signal is resolved by exploiting peak shape criteria. The general efficacy of the method is demonstrated on a set of NIST particulate dust standard reference materials (SRMs 1649b, 2580, 2584 and 2587) with variable total Pb concentrations, and applied to a set of 31 dust samples taken in the municipalities surrounding the integrated steelworks of Tata Steel in IJmuiden, the Netherlands. The total abundances of Pb-rich pixels in the samples range from none to 0.094 area % of the (total) particle surfaces. Overall, out of ca. 92k screened particles, Pb was found in six discrete Pb-phase dominated particles and, more commonly, as superficial sub-particles (sub-micron to 10 µm) adhering to coarser particles of diverse and Pb-unrelated provenance. No relationship is apparent between the samples’ Pb-rich pixel abundance and their overall composition in terms of particle provenance.