Particle Density Research Articles

Flotation activation mechanism of trithiocyanuric acid to malachite

Malachite is a typical refractory copper oxide mineral. In this paper, trithiocyanuric acid (TMT) was used as a novel activator for the activated flotation of malachite for the first time. The effect of TMT on the flotation behavior of malachite was studied and the activation mechanism was discussed. The flotation test results showed that TMT exhibited superior activation performance over sodium sulfide, achieving a high flotation recovery rate of 97.50 % at TMT 90 mg/L and pH 7. The contact angle confirmed malachite improved from 53.3° to 90.1° after TMT treatment, indicating enhanced hydrophobicity of the mineral surface. FTIR and EDS analyses provided clear evidence of chemical adsorption of TMT tautomers onto the malachite surface. SEM images further illustrated the presence of dense particles formed after TMT treatment. XPS revealed that TMT exhibited a strong adsorption effect on malachite, leading to an increase in copper sites and the formation of highly reactive Cu+. The activation mechanism was elucidated as the reaction between Cu sites on malachite and S and N atoms in TMT, forming Cu-S and Cu–N fractions crucial for activation. The high efficiency and low dosage of TMT make it a promising activator for malachite, offering a novel avenue for the effective recovery of malachite-type copper oxide ore resources.

Simulation and Characterization of Micro-Discharge Phenomena Induced by Glitch Micro-Defects on an Insulated Pull Rod Surface

The reliability of GIS (gas-insulated switchgear) circuit breakers significantly depends on the condition of the insulated pull rods, with micro-defects on their surface posing a potential risk for micro-discharges and breakdown incidents. Experimentally investigating these micro-discharges is challenging due to their minute nature. This study introduces a framework to examine the linkage between micro-defects and micro-discharges, coupled with numerical simulations of the micro-discharge process in insulated pull rods afflicted by surface infiltration flaws under operational conditions. Initially, samples containing micro-defects were sectioned via water jet cutting for microstructural analysis through white light interferometry. Subsequently, a two-dimensional axisymmetric model simulating positive corona discharge from a needle to a plate electrode was employed to derive the relationship between charged particle density and the electric field in SF6 and air. Building on these observations, a micro-discharge model specific to micro-defects was developed. Comparative analysis of micro-discharge behaviors in SF6 and air for identical defect types was conducted. This research framework elucidates the discharge dynamics of charged particles in SF6 and air during micro-discharge events, shedding light on the mechanisms underpinning micro-discharges triggered by insulation rod defects.

Assessment of Physico-chemical Properties of Soil from Various Regions of Different Taluk of Pathanamthitta District in the State of Kerala, India

The assessment of Physico-Chemical Properties of Soil from Various Regions of Different Taluk of Pathanamthitta District of Kerala in 2023-24 was a valuable endeavour. A total of 27 samples were collected at profile depths of 0-15, 15-30, and 30-45. It is interesting to note the variations in soil colour between dry and wet conditions, ranging from light brown to dark reddish brown.The soil textural class was identified as Sandy clay Loam, and the sand, silt and clay percentage varied from 45.18% to 50.64%, 17.21% to 20.70%, 30.91% to 34.61%. Bulk Density was varied from 1.08 Mg m-3 to 1.28 Mg m-3. The Particle Density varied from 2.02 Mg m-3 to 2.55 Mg m-3. The Pore Space (%) ranged from 40.18% to 50.62%. The Water Retaining Capacity (%) ranged from 39.19 to 48.98%. The pH value ranged from 4.9 to 6.9. The Electrical Conductivity ranged from 0.03 to 0.30 dS m-1. The value of total Organic Carbon (%) varied from 0.16 to 1.68 %. The available Nitrogen content of soil ranged from 119.45 to 286.07 kg ha-1. The available Phosphorus content of soil ranged from 13.23 to 64.20 kg ha-1. Available Potassium content of soil ranged from 100.80 to 382.40 kg ha-1. Exchangeable Calcium content of soil ranged from 1.7(meq 100g-1) to 9.1(meq 100g-1). Exchangeable Magnesium content of soil ranged from 0.23 (meq 100g-1) to 0.74(meq 100g-1). The Sulphur content of soil ranged from 0.03 to 0.44 kg ha-1. The findings revealed minor increases in bulk and particle density with depth, yet the overall physical condition of the soil seems favourable for plant growth. It is evident that the soils are slightly acidic but meet the acceptable EC limit. The high levels of Organic Carbon are promising, while Nitrogen is lower and Phosphorus and Potassium levels are moderate to high. However, secondary nutrients like Calcium, Magnesium, and Sulphur are relatively low. Nutrient levels appear to be influenced by soil depth, with leaching due to higher precipitation levels in the area contributing to nutrient deficiencies. The results suggest that improvements can be made by implementing strategies such as cover crops, green manure, legume cultivation, mulching, and specific cropping systems to address leaching concerns.

Field theory of active chiral hard disks: A first-principles approach to steric interactions

Abstract A first-principles approach for active chiral hard disks is presented, that 
explicitly accounts for steric interactions on the two-body level. We derive an 
effective one-body equation for the joint probability distribution of positions 
and angles of the particles. By projecting onto the angular modes, we write a 
hierarchy for the lowest hydrodynamic modes, i.e. particle density, polarisation, 
and nematic tensor. Introducing dimensionless variables in the equations, we
highlight the assumptions, which - though inherent - are often included implicit in 
typical closure schemes of the hierarchy. By considering 
different regimes of the Péclet number, the well-known models in active 
matter can be obtained through our consideration. Explicitly, we derive 
an effective diffusive description and by going to higher 
orders in the closure scheme, we show that this first-principles approach 
results in the recently introduced Active Model B +, a natural extension of the 
Model B for active processes. Remarkably, here we find that chirality can 
change the sign of the phenomenological activity parameters.

Analytical Ultracentrifugation to Assess the Quality of LNP-mRNA Therapeutics

The approval of safe and effective LNP-mRNA vaccines during the SARS-CoV-2 pandemic is catalyzing the development of the next generation of mRNA therapeutics. Proper characterization methods are crucial for assessing the quality and efficacy of these complex formulations. Here, we show that analytical ultracentrifugation (AUC) can measure, simultaneously and without any sample preparation step, the sedimentation coefficients of both the LNP-mRNA formulation and the mRNA molecules. This allows measuring several quality attributes, such as particle size distribution, encapsulation efficiency and density of the formulation. The technique can also be applied to study the stability of the formulation under stress conditions and different buffers.

Properties of different graded coir pith by Keen-Raczkowski box and Brunauer-Emmett-Teller analysis

Aim: To evaluate the physical and hydrological properties of different graded coir pith and composted coir pith (CPOM) following the Keen-Raczkowski box and Brunauer-Emmett-Teller (BET) analysis. Methodology: The coir pith was collected and composted by PITH PLUS (Pleurotus-sajor-caju). Thereafter, the coir pith and composted coir pith were segregated into different groups based on the size of the particles as 1.0 mm (1000 microns), 0.5 mm (500 microns), and 0.25 mm (250 microns). Based on particle size, the hydrological properties of coir pith and composted coir pith were determined. The physical and hydrological properties were estimated by the Keen-Raczkowski box method and Brunauer-Emmett-Teller analysis. Results: Different graded coir pith and composted coir pith of size 0.25 mm showed the highest bulk density (0.60 and 0.48 g cm-3), followed by 0.5 mm size coir pith and composted coir pith, respectively. The highest particle density (0.18 and 0.19 g cm-3) was registered in 1.0 mm coir pith and composted coir pith whereas the lowest particle density was observed in 0.25 mm size coir pith (0.15 g cm-3). The water-holding capacity (817.93 % and 806.97 %) and water in air-dry substrate (25.03 % and 36.094 %) was high in 0.25 mm coir pith and composted coir pith. Interpretation: A 0.25 mm grade of coir pith and composted coir pith showed highest water holding and retaining capacity due to a greater number of small particles being compactly arranged and holding more surface area, and innumerable micropores than other graded particles. Key words: BET analysis, Coir pith, Composted coir pith, Water holding capacity

Importance of microphysical settings for climate forcing by stratospheric SO2 injections as modeled by SOCOL-AERv2

Abstract. Solar radiation modification by a sustained deliberate source of SO2 into the stratosphere (strat-SRM) has been proposed as an option for climate intervention. Global interactive aerosol–chemistry–climate models are often used to investigate the potential cooling efficiencies and associated side effects of hypothesized strat-SRM scenarios. A recent model intercomparison study for composition–climate models with interactive stratospheric aerosol suggests that the modeled climate response to a particular assumed injection strategy depends on the type of aerosol microphysical scheme used (e.g., modal or sectional representation) alongside host model resolution and transport. Compared to short-duration volcanic SO2 emissions, the continuous SO2 injections in strat-SRM scenarios may pose a greater challenge to the numerical implementation of microphysical processes such as nucleation, condensation, and coagulation. This study explores how changing the time steps and sequencing of microphysical processes in the sectional aerosol–chemistry–climate model SOCOL-AERv2 (40 mass bins) affects model-predicted climate and ozone layer impacts considering strat-SRM by SO2 injections of 5 and 25 Tg(S) yr−1 at 20 km altitude between 30° S and 30° N. The model experiments consider the year 2040 to be the boundary conditions for ozone-depleting substances and greenhouse gases (GHGs). We focus on the length of the microphysical time step and the call sequence of nucleation and condensation, the two competing sink processes for gaseous H2SO4. Under stratospheric background conditions, we find no effect of the microphysical setup on the simulated aerosol properties. However, at the high sulfur loadings reached in the scenarios injecting 25 Tg(S) yr−1 of SO2 with a default microphysical time step of 6 min, changing the call sequence from the default “condensation first” to “nucleation first” leads to a massive increase in the number densities of particles in the nucleation mode (R<0.01 µm) and a small decrease in coarse-mode particles (R>1 µm). As expected, the influence of the call sequence becomes negligible when the microphysical time step is reduced to a few seconds, with the model solutions converging to a size distribution with a pronounced nucleation mode. While the main features and spatial patterns of climate forcing by SO2 injections are not strongly affected by the microphysical configuration, the absolute numbers vary considerably. For the extreme injection with 25 Tg(S) yr−1, the simulated net global radiative forcing ranges from −2.3 to −5.3 W m−2, depending on the microphysical configuration. Nucleation first shifts the size distribution towards radii better suited for solar scattering (0.3 µm <R< 0.4 µm), enhancing the intervention efficiency. The size distribution shift, however, generates more ultrafine aerosol particles, increasing the surface area density and resulting in 10 DU (Dobson units) less ozone (about 3 % of the total column) in the northern mid-latitudes and 20 DU less ozone (6 %) over the polar caps compared to the condensation first approach. Our results suggest that a reasonably short microphysical time step of 2 min or less must be applied to accurately capture the magnitude of the H2SO4 supersaturation resulting from SO2 injection scenarios or volcanic eruptions. Taken together, these results underscore how structural aspects of model representation of aerosol microphysical processes become important under conditions of elevated stratospheric sulfur in determining atmospheric chemistry and climate impacts.

Evaluating the Physical and Chemical Characteristics of Soil from Several Blocks in Mirzapur District, Uttar Pradesh, India

An evaluation of the physical-chemical characteristics of soil was conducted in 2023–24 in several blocks within the Mirzapur district of Uttar Pradesh. This study's main goals were to assess the physico-chemical characteristics of soil in several blocks in Uttar Pradesh's Mirzapur District in ord`er to ascertain the soil's macronutrient availability. Samples of soil were taken at three different depths: 0–15 cm, 15–30 cm, and 30-45 cm. Sandy loam was the textural class of soil. 1.17 mg m-3 to 1.44 mg m-3 is the bulk density. Density of Particles (2.22 - 2.48 mg m-3). Pore Space Percentage (42.78% to 48.00%). It was evident that the soil had good physical conditions, an alkaline pH range of 7.43 to 8.15, a good water holding capacity (39.92 to 45.76%), and and all crops could benefit from the electrical conductivity (0.21 to 0.34 dSm-1). Organic carbon content in these soils is modest (0.27 to 0.38%). All villages have a medium nitrogen range (250 kg ha-1 to 380 kg ha-1). All villages have a medium phosphorus level (22.53 kg ha-1 to 37.49 kg ha1). (148.43 kg ha-1 to 282.4 kg ha-1) of potassium. is high in one place and medium in eight others.

Impingement of NPK and Rhizobium on Physico-chemical Properties of Soil under Cluster Bean (Cyamopsis tetragonoloba L.)

The study pertaining to the present topic under field investigation entitled “effect of different levels of NPK and Rhizobium on Physico-chemical properties of soil, growth and yield attributes of cluster bean” beginning from kharif seasons of the years 2023 at Research Farm, Department of Soil Science and Agricultural Chemistry. The excavated soil sample from experimental site before conducting research operation, mentioned that, the land topography range was nearly levelled with 1-3% slope, soil is of sandy loam texture with neutral to alkaline in reaction (7.140), electrical conductivity was non-saline (0.346 dS m-1) in nature, low organic carbon content (0.38%), low to medium available N (261.39 kg ha-1), available P (14.60 kg ha- 1) and available K (193.99 kg ha-1). Among nine treatments, during field experimentation, the conjunctive use of NPK and different Rhizobium levels, together come with best results significantly. However, the physical and chemical soil parameters, cumulative mean value for Bulk density (1.42 Mg m-3 and 1.45 Mg m-3),Particle density (2.64 Mg m-3 and 2.66 Mg m-3) and Soil pH (7.140 and 7.370) was found optimum in T1 (Absolute control) at 0-15 cm depth and 15-30 cm depth, respectively. Percentage porespace (45.17% and 43.17%), Water holding capacity (42.32% and 39.70%), Electrical conductivity (0.323 dS m-1 and 0.300 dS m-1), Percentage organic carbon (0.49% and 0.46%), Available N (284.41 kg ha-1 and 281.48 kg ha- 1 ), Available P (22.54 kg ha-1 and 21.29 kg ha-1 ), Available K (210.52 kg ha-1 and 203.98 kg ha-1 ) were found optimum in T9 consisting of (@ 100% NPK + @ 100% Rhizobium) in comparison to other NPK and Rhizobium levels application.

Optical Considerations for Designing Laser-Based Volumetric Particle Tracking Velocimetry

Abstract The trend to conduct volumetric Particle Tracking Velocimetry experiments with ever increasing volumes, at a given particle density, poses increasing challenges on the design of such experiments in terms of the power of the laser source and the image analysis. This, on one hand, requires a reliable model to estimate the signal level that is measured on a CMOS detector from a Mie scattering particle. On the other hand, it requires also a model for estimating the limiting factors upon the image resolution, where a large amount of particles within a 3D volume are mapped into a 2D image. Herein, we present a model that provides an analytical expression to estimate the signal level on a CMOS detector from a Mie scattering particle within an arbitrary large volume in a volumetric Particle Tracking Velocimetry experiment. We begin with a model for planar experiments and extend it into volumetric measurements. Our model considers the effect of the depth of field, particle density, Mie scattering signal and total Mie scattering loss, laser pulse-energy and relevant optical parameters. Later, we investigate the consequence of the Rayleigh criterion upon image resolution when it is applied to particles within a volume of interest. Finally, we demonstrate how we applied our model to estimate the signal level and the limit upon the spatial resolution in three experiments carried-out in our lab.

Response of Inorganic, Organic Fertilizer and Microbial Inoculants on Physico-chemical Properties of Soil in Cultivation of Wheat (Triticum aestivum. L) var. PBW-373

The objective of the experiment was to evaluate the response of inorganic fertilizer, organic fertilizer and microbial inoculants on soil health of wheat. The design applied was 3x3 randomized block design. It was observed that treatment T9 (100% RDF +FYM @ 15 t ha-1 + PSB 6.0 kg ha-1) improved the soil WHC, OC, available N,P and K resulted in a slight change in soil pH 7.34, EC 0.49 dS m-1, bulk density 1.14 Mg m-3 and particle density 2.54 Mg m-3. In post-harvest soil of fertilizers observations were resulted in significant increase in pore space 48.97 %, water holding capacity 46.85 %, organic carbon 0.48 %, and available N 286.92 kg ha-1 ,P20.05 kg ha-1,K 201.87 kg ha-1,significant increase in case of Nitrogenkg ha-1, Phosphorus kg ha-1, Potassium kg ha-1 was found to be significant among other treatments in wheat cultivation.

Characteristics of rice husk biochar briquettes with municipal solid waste cassava, sweet potato and matooke peelings as binders

AbstractRice husks are not readily biodegradable making their disposal challenging due to the common disposal method of open burning which has negative environmental effects. Additionally, banana, sweet potato and cassava peelings form a large percentage of organic municipal solid waste. Therefore, this study developed rice husk biochar briquettes with organic municipal peelings waste as binders. Rice husks biochar was formed via carbonization processes in a step-down kiln at temperatures ranging between 400 and 500 °C. Organic binders were mixed with the rice husk biochar at different ratios of 10% and 15% before being compacted at a pressure ≤ 7 MPa into briquettes. Thermogravimetric results showed that the developed briquettes had high ash contents ranging from 44% to 47%. Rice husk biochar briquettes with the highest particle density were observed for briquettes with 15% cassava peel binder at 427.1 kg/m3. The highest HHV and maximum attainable flame temperature of 21.75 MJ/kg and 828.7 °C were obtained for rice husk biochar briquettes with 15% matooke peeling organic binder. For all rice husk biochar briquettes, increasing the organic peeling binder had a positive impact of reducing the ash content, while at the same time increasing the peak temperatures, thus contributing to their enhanced thermal stability.

Scale-up prediction of the head loss of a high concentration, non-Newtonian particulate slurry

The design of a mineral slurry transportation system is difficult because of the non-Newtonian nature of the flow at high slurry concentrations. The behavior of the slurry depends on many physio-chemical properties such as particle density, particle size distribution (PSD), particle shape, chemical composition, pH etc. This work presents a comparative study between three preferred methods of scale-up of the head loss in larger diameter pipelines, namely Bowen’s Method, rheological method and Wilson’s Method. The performance of each method is validated with the pipe loop test data in a 200 DN pipeline. A high concentration (>50% by weight) iron ore concentrate slurry was used for carrying out the above study. This work would be beneficial for engineers involved in the design and maintenance of the slurry pipelines with respect to the choice of the scale-up methods available for estimation of the head loss for a time independent, homogenous, non-Newtonian particulate slurry for both laminar and turbulent regime.

Coordinated deformation mechanisms of high formability Al–Mg–Si–Cu–Zn–Fe alloys via coupling control of thermomechanical processes

Both the high formability and strengths are greatly important for the automotive application of Al–Mg–Si–Cu alloys. In the present work, four novel thermomechanical processing routes were designed to improve the comprehensive properties of Al–Mg–Si–Cu–Zn–Fe alloys. The results show that, the interspace between Fe-rich particles and Fe/Mn-containing dispersoids can be significantly reduced by an optimized thermomechanical processing route. This enhanced the interaction between them during subsequent cold rolling process, resulting in increased number density and uniform distribution level of multi-scale Fe-rich particles, which further substantially improve both the recrystallization microstructure and mechanical properties, i.e., higher bendability, average r value of 0.72 (0.59 for traditional sheet) and tensile strength of 302 MPa (283 MPa for traditional sheet). The microstructure evolution of alloy sheets was schematically illustrated, and in-depth analysis on the mechanism of high formability was proceeded from the aspects of grain boundary misorientations and recrystallization texture.

Transport of dust across the Solar System: Constraints on the spatial origin of individual micrometeorites from cosmic-ray exposure.

The origin of micrometeorites (MMs) from asteroids and comets is well-established, but the relative contribution from these two classes remains poorly resolved. Likewise, determining the precise origin of individual MMs is an open challenge. Here, cosmic-ray exposure ages are used to resolve the spatial origins of 12 MMs collected from urban areas and Antarctica. Their 26Al and 10Be concentration, produced during cosmic-ray irradiation in space, were measured by accelerator mass spectrometry. These data are compared to results from a model simulating the transport and irradiation of the MM precursors in space. This model, for the first time, considers a variety of orbits, precursor particle sizes, compositions and densities and incorporates non-isotropic solar and galactic cosmic-ray flux profiles, depth-dependent production rates, as well as spherical evaporation during atmospheric entry. While the origin for six MMs remains ambiguous, two MMs show a preferential tendency towards an origin in the Inner Solar System (Near Earth Objects to the Asteroid Belt) and four towards an origin in the Outer Solar System (Jupiter Family Comets to the Kuiper Belt). These findings challenge the notion that dust originating from the Outer Solar System is unlikely to survive long-term transport and delivery to the terrestrial planets. This article is part of the theme issue 'Dust in the Solar System and beyond'.

Effect of Ti/N Ratio on TiN Particles, Microstructures, and Toughness of Heat‐Affected Zone After High Heat Input Welding of the Ca‐Treated Steel Plates

The high heat input welding (HHIW) can greatly enhance the welding efficiency of the steel plates. However, coarse grains and brittle microstructures will be formed in the heat‐affected zone (HAZ) during the HHIW process, which deteriorates the toughness of HAZ. In the present study, the effect of the Ti/N ratio on the size and distribution of titanium nitride (TiN) particles, microstructures, and toughness of HAZ after HHIW of 400 kJ cm−1 is investigated for the Ca‐treated steels with different Ti/N ratios of 1.61, 3.79, and 5.00 for TN16, TN38, and TN50 steels. The TN38 steel has the highest number density of the TiN particles with the sizes between 20 and 25 nm and the highest pinning force of the particles in three steels, resulting the smallest grain sizes in its HAZ. In addition, in three steels, the TN38 steel has the main microstructure of intragranular aciculate ferrites with the highest high‐angle grain boundaries density in its HAZ, thereby obtaining the highest value of low‐temperature impact toughness of the HAZ.

Cross-calibration of quantum atomic sensors for pressure metrology

Quantum atomic sensors have shown great promise for vacuum metrology. Specifically, the density of gas particles in vacuum can be determined by measuring the collision rate between the particles and an ensemble of sensor atoms. This requires preparing the sensor atoms in a particular quantum state, observing the rate of changes of that state, and using the total collision rate coefficient for state-changing collisions to convert the rate into a corresponding density. The total collision rate coefficient can be known by various methods, including quantum scattering calculations using a computed interaction potential for the collision pair, measurements of the post-collision sensor-atom momentum recoil distribution, or empirical measurements of the collision rate at a known density. Observed discrepancies between the results of these methods call into question their accuracy. To investigate this, we study the ratio of collision rate measurements of co-located sensor atoms, 87Rb and 6Li, exposed to natural abundance versions of H2, He, N2, Ne, Ar, Kr, and Xe gases. This method does not require knowledge of the test gas density and is, therefore, free of the systematic errors inherent in efforts to introduce the test gas at a known density. Our results are systematically different at the level of 3% to 4% from recent theoretical and experiment measurements. This work demonstrates a model-free method for transferring the primacy of one atomic standard to another sensor atom and highlights the utility of sensor-atom cross-calibration experiments to check the validity of direct measurements and theoretical predictions.

Transferable local density-dependent friction in tert-butanol/water mixtures.

Coarse-grained (CG) models informed from molecular dynamics simulations provide a way to represent the structure of an underlying all-atom (AA) model by deriving an effective interaction potential. However, this leads to a speed-up in dynamics due to the lost friction, which is especially pronounced in CG implicit solvent models. Applying a thermostat based on the Langevin equation (LE) provides a way to represent the long-time dynamics of CG particles by reintroducing friction to the system. To improve the representability CG models of heterogeneous molecular mixtures and their transferability over the mixture compositions, we parameterize an LE thermostat in which the friction coefficient depends on the local particle density (LD). The thermostat friction was iteratively optimized with a Markovian variant of the recently introduced Iterative Optimization of Memory Kernels (IOMK) method. We simulated tert-butanol/water mixtures over a range of compositions, which show a distinct clustering behavior. Our model with LD-dependent friction reproduces the AA diffusion coefficients well over the full range of mixtures and is, therefore, transferable with respect to dynamics.

Characterization of the airborne aerosol inlet and transport system used during the A-LIFE aircraft field experiment

Abstract. Atmospheric aerosol particles have a profound impact on Earth's climate by scattering and absorbing solar and terrestrial radiation and by impacting the properties of clouds. Research aircraft such as the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) Falcon are widely used to study aerosol particles in the troposphere and lower stratosphere. However, transporting a representative sample to the instrumentation inside the aircraft remains a challenge due to high airspeeds and changing ambient conditions. In particular, for high-quality coarse-mode aerosol measurements, knowledge about losses or enhancements in the aerosol sampling system is crucial. In this study, the sampling efficiency of the aerosol inlet aboard the Falcon research aircraft is characterized for the first time with state-of-the art in situ measurements including sizing instruments operated behind the Falcon aerosol inlet and mounted at the aircraft wing not affected by the aerosol inlet. Sampling efficiencies were derived for different true airspeed ranges by comparing the in-cabin and ”full”-size-range particle number size distributions during 174 flight sequences with a major contribution of mineral dust particles during the ”Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics” project (A-LIFE). Additionally, experimentally derived Stokes numbers were used to calculate the cutoff diameter of the aerosol sampling system for different particle densities as a function of true airspeed. As expected, the results show that the velocity of the research aircraft has a major impact on the sampling of coarse-mode aerosol particles with in-cabin instruments. For true airspeeds up to about 190 m s−1, aerosol particles larger than about 1 µm are depleted in the sampling system of the Falcon during the A-LIFE project. In contrast, for true airspeeds higher than 190 m s−1, an enhancement of particles up to a diameter of 4 µm is observed. For even larger particles, the enhancement effect at the inlet is still present, but inertial and gravitational particle losses in the transport system get more and more pronounced, which leads to a decreasing overall sampling efficiency. In summary, aerosol particles are either depleted or enhanced in the Falcon aerosol inlet, whereas transport in sampling lines always leads to a loss of particles. Here, we have considered both effects and determined the cutoff diameter for the A-LIFE transport system (i.e., the sampling lines only), the cutoff diameter of the Falcon aerosol inlet (i.e., the effect of the inlet only), and the combined effect of the inlet and sampling lines.

Effect of Humic Amendment on Selected Hydrophysical Properties of Sandy and Clayey Soils

In recent years, products containing humic acids have been increasingly used in agriculture to improve soil parameters. Quantifying their impact on soil quality is, therefore, of key importance. This study seeks to evaluate the impact of the commercial humic acid product (HA) on the hydrophysical parameters of sandy and clayey soils sampled from different sites in Slovakia. Specifically, the study hypothesizes that humic amendment will enhance particle density (ρs), dry bulk density (ρd), porosity (Φ), saturated hydraulic conductivity (Ks), soil water repellency (SWR), and water retention capacity in sandy and clayey soils. The results of the laboratory measurements were analyzed using NCSS statistical software at a statistical significance of p < 0.05. In sandy soil, there was a statistically significant decrease in ρd and Ks and an increase in Φ and a contact angle (CA) after the application of 1 g/100 cm3 HA. At a dose of 6 g/100 cm3 HA, the values of ρs, ρd, and Ks decreased, and the Φ and CA values increased. In clayey soil, the Ks value significantly decreased by −35.5% only after the application of 6 g/100 cm3 HA. The addition of HA increased the full water capacity (FWC) and available water capacity (AWC) of clayey and sandy soils. The positive influence of HA on the studied soil parameters was experimentally confirmed, which can be beneficial, especially for their use in agricultural production.