Particles In Field Research Articles

Micromagnetic simulations of tetrataenite: A systematic study

The present work is a systematic study of tetrataenite's magnetic behavior based on micromagnetic simulations. Tetrataenite, a Fe50Ni50 intermetallic compound with L10 structure, is a chemically ordered alloy normally found in meteorites. In natural samples, like in meteorites, tetrataenite occurs as islands or clusters embedded in other Fe-Ni alloys. Its composition as well as its high magnetic anisotropy and magnetization make it a material of great technological application potential. Several properties of interest were studied in the simulations, such as the exchange coupling, magnetic texture, and particle size. The intention is to describe the tetrataenite's general magnetic behavior in order to assist the interpretation of experimental results and predict different scenarios which may occur in natural meteoritic samples. The results show the effects of the exchange magnetic coupling play an important role in the reversal of the magnetization, but they are less determinant for the coercivity than the effects of texture and island size. It is also concluded that the initial state is more decisive for the determination of the equilibrium state than the magnitude of the magnetic coupling between the islands and matrix.

Optimizing Biochar Particle Size for Plant Growth and Mitigation of Soil Salinization

Pyrolyzed waste biomass, or biochar, has been suggested as a means to increase plant growth and mitigate soil salinization, which is a widespread agricultural issue and can reach extreme levels in urban soils impacted by de-icing salts. Soil mixing is enhanced by reduced biochar particle size; however, biochar properties vary with particle size, and recent studies have suggested that plant growth responses may be maximized at intermediate particle sizes. We examined the responses of two plant species (cowpea (Vigna unguiculata) and velvetleaf (Abutilon theophrasti)) to biochar amendments that spanned a wide range of particle sizes obtained by sieving, with and without de-icing salt additions. The smallest size fractions of biochar reduced plant growth relative to unamended controls. Plant biomass production was generally maximized at intermediate biochar particle size treatments, with particle sizes of 0.5–2.0 mm showing the best response. Mitigation of salt effects was also improved at intermediate biochar particle sizes in this particle size range. Our results emphasize the importance of optimizing biochar particle size to best enhance plant responses to biochar, with particular reference to saline soils.

Meltwater layer dynamics in a central Arctic lead: Effects of lead width, re-freezing, and mixing during late summer

Leads play an important role in the exchange of heat, gases, vapour, and particles between seawater and the atmosphere in ice-covered polar oceans. In summer, these processes can be modified significantly by the formation of a meltwater layer at the surface, yet we know little about the dynamics of meltwater layer formation and persistence. During the drift campaign of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC), we examined how variation in lead width, re-freezing, and mixing events affected the vertical structure of lead waters during late summer in the central Arctic. At the beginning of the 4-week survey period, a meltwater layer occupied the surface 0.8 m of the lead, and temperature and salinity showed strong vertical gradients. Stable oxygen isotopes indicate that the meltwater consisted mainly of sea ice meltwater rather than snow meltwater. During the first half of the survey period (before freezing), the meltwater layer thickness decreased rapidly as lead width increased and stretched the layer horizontally. During the latter half of the survey period (after freezing of the lead surface), stratification weakened and the meltwater layer became thinner before disappearing completely due to surface ice formation and mixing processes. Removal of meltwater during surface ice formation explained about 43% of the reduction in thickness of the meltwater layer. The remaining approximate 57% could be explained by mixing within the water column initiated by disturbance of the lower boundary of the meltwater layer through wind-induced ice floe drift. These results indicate that rapid, dynamic changes to lead water structure can have potentially significant effects on the exchange of physical and biogeochemical components throughout the atmosphere–lead–underlying seawater system.

Solute transport through undisturbed carbonatic clay soils in dry regions under differing water quality and irrigation patterns

The often-indispensable use of poor-quality irrigation water in drylands instigates diverse physicochemical dynamics leading to soil salinization and sodicity which are recognized as major contributors to land degradation. This study aimed to examine the effects of water quality and irrigation mode on solute transport conditions in terms of ion exchange of colloidal particles. Laboratory studies with undisturbed soil columns were carried out with two water treatments - tap and sodic waters - as well as two water flow velocities: fast leaching which corresponds to Darcy velocity equal to the saturated hydraulic conductivity and slow leaching equal to half the fast-leaching case. Results indicated that the flow velocities did not significantly influence pH, EC and ion concentrations due to the high calcium carbonate and clay contents of the soil which make the soil less permeable. However, flow velocity rapidly decreased in the fast leaching compared to that in slow leaching as the sodic water was applied. This reveals the destructive effect of Na+ in the soil. The EC rapidly dropped at the beginning of leaching for both water qualities opposite to pH, then became steady. All sodic applications caused an increase in Na+ till the end of treatments. This also resulted in variations in measured soluble anions. In general, sharp decreases in highly soluble anions were observed in all treatments, leading to an increase in HCO3–, especially for sodic treatments. Overall, sodicity caused significant changes in flow dynamics and ion concentrations and created favorable conditions for secondary salinization in this low permeable soil system.

Dipole representation of half-filled Landau level

We introduce a variant of a dipole representation for composite fermions in a half-filled Landau level, taking into account the symmetry under an exchange of particles and holes. This is implemented by a special constraint on a composite fermion and a composite hole degree of freedom (of an enlarged space), which makes the resulting composite particle (dipole) a symmetric object. We study an effective Hamiltonian that commutes with the constraint on the physical space and fulfills the requirement for boost invariance on the Fermi level. The calculated Fermi liquid parameter ${F}_{2}$ is in good agreement with numerical investigations in Phys. Rev. Lett. 121, 147601 (2018).

Hydrodynamics for the ABC model with slow/fast boundary

In this article, we consider the ABC model in contact with slow/fast reservoirs. In this model, there is one particle per site, which can be of type α∈{A,B,C} and particles exchange positions in the discrete set of points {1,…,N−1} with a rate which is weakly asymmetric and depends on the type of particles involved in the exchange mechanism. At the boundary points x=1,N−1 particles can be injected or removed, and the rate at which this happens depends on the type of particles involved. We prove the hydrodynamic limit, in the diffusive time scale, given by a system of non-linear coupled equations with several boundary conditions, that depend on the strength of the reservoir’s action.

Effects of bottom profile on the circulation and classification of particles in cylindrical hydrocyclones

The cylindrical hydrocyclone has been increasingly used in coarse classification due to its reduced fine particle entrainment, but the loss of coarse particles to overflow remains an intractable problem. Based on the notion that the strong circulation flow caused by the flat bottom structure bears primary responsibility for the problem, this study designs eight unique bottom profiles to regulate the particle circulating flow and attempts to correlate particle circulation flow with classification performance. The effects of the bottom profile on flow field characteristics, particle spatial distribution, circulation flow rates, and grade efficiency are explored in detail using validated models in a Φ200 mm cylindrical hydrocyclone. The findings suggest that bottom profiles have the greatest effect on the axial velocity near the bottom and the grade efficiency of intermediate and coarse particles, while all unique designs have the potential to lower turbulence intensity. An ascending segment near the wall or a descending segment near the axis can help to mitigate the misplacement of coarse particles by reducing particle circulation flow without affecting the entrainment of fines appreciably. Additionally, two circles are found on each side of the cut plane, which is conducive to releasing coarse particles from the circulation flow. Regulation of particle circulation flow by adjusting bottom profile parameters can improve separation performance.

Helical inflation correlators: partial Mellin-Barnes and bootstrap equations

Massive spinning particles acquire helicity-dependent chemical potentials during the inflation from axion-type couplings. Such spinning fields can mediate sizable inflaton correlators which we call the helical inflation correlators. Helical inflaton correlators are approximately scale invariant, dS boost breaking, parity violating, and are promising observables of cosmological collider physics. In this work, we present complete and analytical results for 4-point helical inflation correlators with tree-level exchanges of massive spinning particles, including both the smooth background and the oscillatory signals. We compute the bulk Schwinger-Keldysh integrals in two independent ways, including the partial Mellin-Barnes representation and solving bootstrap equations. We also present new closed-form analytical results for 3-point functions with massive scalar or helical spinning exchanges. The analytical results allow us to concretely and efficiently explore the phenomenological consequences of helicity-dependent chemical potentials. In particular, we show that the chemical potential can exponentially enhance oscillatory signals of both local and nonlocal types, but only affects the background in a rather mild way. Our results extend the de Sitter bootstrap program to include nonperturbative breaking of de Sitter boosts. Our results also explicitly verify the recently proposed cutting rule for cosmological collider signals.

Influence of Carrier Agents Concentrations and Inlet Temperature on the Physical Quality of Tomato Powder Produced by Spray Drying

The study aims to obtain spray-dried tomato powders with a high and effective product yield and enhanced powder quality. The experiment for this investigation entailed the use of several carrier agents, which were maltodextrin (MD) of 4-7 dextrose equivalents (DE), MD of 10-12 DE, and gum Arabic (GA), each in varied concentrations of 5% and 10% with spray drying inlet temperatures of 140°C, 150°C, and 160°C. Powder yield, bulk density, hygroscopicity, moisture content, water solubility, water absorption, color properties, particle size, and powder morphology were all evaluated in spray-dried tomato powders. The results revealed that the stability of the tomato powder is considerably better at high temperatures and concentrations (at 10%, 160oC), with MD 4-7 DE being the best carrier agent among the three tested carrier agents. According to the powder analysis, the product has a moisture content of 3.17 ± 0.29%, the highest yield percentage of 32.1%, a low bulk density of 0.2943 ± 0.01 g/cm3, the lowest hygroscopicity at 5.67± 0.58 %, a high water solubility index (WSI) at 89.98 ± 1.25%, a low water absorption index (WAI) at 6.22 ± 0.22%, an intermediate particle size of 24.73 µm, and color L*, a*,b* values at 31.59 ± 0.03, 11.62 ± 0.08 and 13.32 ± 0.12. The result showed that at higher temperatures and higher concentrations, the powder characteristics are more likely to have a higher yield, WSI, and larger particle size, as well as lower bulk density, hygroscopicity, moisture content, WAI, and color index.

An analytical representation of raindrop size distribution in a mixed convective and stratiform precipitating system as revealed by field observations

AbstractThis study investigated a rainfall event under a typhoon influence using a 2D video disdrometer and weather radar observations to characterize raindrop size distribution (DSD) in a mixed convective and stratiform precipitating system. During the time period when both convective and stratiform rainfalls existed, the DSDs generally indicated a monotonically decreasing shape with increasing particle size, with a relatively gradual decrease at intermediate particle size observed at certain times; this feature is attributed to the combined effect of convective and stratiform rainfalls. During the transitional period between convective and stratiform rainfalls, the DSDs exhibited a bimodal shape. The DSDs were well approximated by a newly proposed gamma raindrop distribution combined with exponential (GRACE) distribution function, which was defined as the sum of the exponential distribution and the gamma distribution. A comparison of the volume ratio of the exponential and gamma components of the GRACE distribution revealed that the exponential component of the DSD was larger than the gamma component in the bimodal DSD. These results suggest that the DSD became bimodal during the period when stratiform rainfall predominated because of the weakening of convective rainfall. The GRACE distribution is useful for understanding cloud‐microphysical processes in mixed stratiform and convective precipitation conditions.

The quantum nature of the weak interaction

From the fundamental noνα = 1 formula, the up quark was identified as an exchange particle based on its mass, which implies that the particle is newly formed and not, as the current theory says, transformed from the d quark through ß-decay. The quark rotation most possibly imparts a fast oscillatory rotation to the quarks (weak interaction), which in turn imparts the rotation to the nucleon. The transferred rotation is partially decoupled from the quarks, which means that the transferred rotation velocity does not depend on the oscillation velocity of the quark structure, but on its radius r, where r is the virtual quantized radius of the quark rotation or quark oscillation. In case of the week interaction, when the quarks begin to oscillate, the rotation is partially decoupled from the individual quarks and transferred to the triple quark structure in the transverse direction to the main axis of rotation. From this, a unified formula for the gravitation and EM forces could be deduced.

Al2014-Alumina Aerospace Composites: Particle Size Impacts on Microstructure, Mechanical, Fractography, and Wear Characteristics.

An Al2014-alumina (Al2O3) composite's characteristics are significantly influenced by the reinforcement particle size variation. Therefore, this study examines the microstructure, mechanical, fractography, and wear performance of an Al2014-Al2O3p composite made using a unique two-stage stir casting method and various alumina weight fractions (9, 12, and 15 wt %). Three categories of alumina particle size are used, i.e., fine particle size (FPS, 8 μm), intermediate particle size (IPS, 53 μm), and coarse particle size (CPS, 88 μm). The shapes of the composites were characterized using scanning electron microscopy. According to scanning electron microscopic analyses of the microstructure, the FPS dispersion was more uniform than IPS and CPS, whereas CPS causes agglomeration. Additionally, the studies show that the FPS composite outperformed CPS and IPS composites in terms of mechanical characteristics and wear performance. The fractography study shows conical and equiaxed dimple failure in the Al2014 matrix and the circular cavities.

STOE “hod” is the quantum “graviton”

The graviton in quantum models is a particle or force carrier that accounts for the gravitational force. The “hod” in the Scalar Theory of Everything (STOE) is the component of the universe that is the most fundamental particle. The structure of hods emerge to form photons and other particles. This provides the unification of the big and the small. Many observations are explained such as interference of particles and galaxy’s asymmetric rotation curves.

Microscopic Quantum Jump: An Interpretation of Measurement Problem

Nearly a century has passed, since the birth of quantum mechanics, and yet the measurement problem has not been solved. We investigate the measurement problem from two aspects. First we scrutinize the basic postulates adopted by existing theories and identify the postulate of classicality of apparatus (PCA) to be the origin of the trouble. Second, we analyze the simplest possible experimental setup, a single photon particle as an observed system S and a detector as an apparatus A, and we find that a quantum jump occurs as a microscopic interaction between S and a single particle in A. We call this a microscopic quantum jump (MIJ). The MIJ selects system eigenvalues (SEVs) such as a two-dimensional position and arrival time for an incident photon. The MIJ outputs a microscopic particle (MIP), which carries the information of the SEVs potentially. In the apparatus A, the MIP triggers amplification cascade of secondary particles, which we call the intermediate particles (IMPs). The IMPs are initially a few, but become plenty after the amplification. The output of the amplification is a macroscopic observable (MAO) such as a current pulse, which carries the information of the SEVs in actuality. The measurement is complete when the MAO is obtained. By adopting the postulate of the MIJ and by discarding the PCA, we have constructed a measurement theory, which is consistent with standard quantum mechanics.

Techno-economic analysis of multi-tower solar particle power plants

Solar tower systems using solid particles as heat transfer and storage medium promise to achieve, in combination with advanced power cycles, lower levelized cost of electricity (LCOE) than state-of-the-art concepts. In this study the cost potential of a multi-tower solar power plant with centrifugal particle receiver is evaluated. Most of the underlying assumptions were chosen in accordance with those specified within the US-DoE Gen3 project “G3P3”. For the power block a high-efficiency supercritical CO2 system with 100MWe was assumed. The solar subsystem is built from 12 identical solar tower modules, each with heliostat field, tower, receiver and storage. The nominal thermal power of each module is 41MWth.Since the cost assumptions for the tower and the heat exchanger (HX) are still relatively uncertain, different correlations were used representing optimistic and conservative cases. For the particle receiver two outlet temperature levels were investigated, namely 800 °C and 1000 °C.The results of the techno-economic analysis indicate a strong impact of the cost assumptions for the primary heat exchanger and the tower. With 800 °C as particle outlet temperature, the estimated LCOE range from $56.18/MWh (optimistic values for tower and HX cost) to $67.30/MWh (conservative values for tower and HX cost).Increasing the particle outlet temperature to 1000 °C results in a significant reduction of LCOE (about 12% for the optimistic cases, down to $50.46/MWh). The reason for this is the significant reduction of heat exchanger area, particle inventory and particle mass flow, resulting from the larger temperature difference in the particle system. However, operating the system at such elevated particle temperatures will require some modifications to the components that are not fully reflected in the used cost correlations yet. Nevertheless, the results propose further investigation of this option. All in all the results indicate a clear potential to achieve the SunShot goal of less than $60/MWh.

Lab in a bottle, open-source technologies for the design of affordable environmental samplers integrating on-site extraction

Access to clean water, a Sustainable Development Goal, can only be accomplished worldwide using affordable technologies. In the analytical chemistry realm, developing cheap devices capable of on-site extraction results in a helpful tool. This article presents a new device based on open-source technologies for the on-site extraction of isoflavones from environmental waters as a proof of concept. The device is wholly operated by an Arduino microcontroller that also integrates sensors (temperature and conductivity) to provide on-site information. The extraction unit stirs into the sample, using a small motor, a planar sorptive phase consisting of Mixed-mode Anionic Exchange particles (MAX). After the on-site extraction, the sorptive phase is transported to the lab for its final analysis by liquid chromatography coupled with mass spectrometry. The analytical method provided detection limits of 1.5 ng L−1 (biochanin A and formononetin) and 15 ng L−1 (daidzein and genistein). The precision, expressed as relative standard deviation, was evaluated at three concentration levels providing results better than 9.8 %. The accuracy, with relative recoveries in the 85–119 % ranges, supports the application of the method. The relevance of isotopically labeled compounds to normalize the effect of some variables on the extraction of the analytes is also discussed in detail.

Dynamical indistinguishability and statistics in quantum fluids

For a system to qualify as a quantum fluid, quantum-statistical effects should operate in addition to quantum-mechanical ones. Here, we address the hitherto unexplored dynamical condition for the quantum-statistical effects to be manifested, and consider particle exchange events in the gaslike regime of fluid dynamics as a dynamical process with an intrinsic time scale. We subsequently propose a quantitative criterion of particle indistinguishability and associated quantum statistics to be inoperative at short time and emerge at long time. Experimentally verifiable, our predictions enable a systematic search for a transition between statistics-active and statistics-inactive regimes in quantum fluids.

Effect of biochar with different particle sizes on the sorption-desorption characteristics of soil phosphorus.

The size of particles determines the adsorption reaction. In this study, three different particle sizes of biochar (0.25-1 mm, 0.075-0.25 mm, <0.075 mm) were produced from rapeseed straw (SBC) and chicken manure (MBC). The biochar was mixed with high phosphorus (P) soil and low P soil and then incubated for 30 days. We conducted isothermal P sorption and desorption experiments to evaluate the effects of biochar particle size on sorption-desorption characteristics of soil P, and analyzed soil properties associated with P sorption. The results showed that P sorption capacity of SBC and MBC in the water system was highest for the smallest particle size (<0.075 mm) (SBC: 43125 mg·kg-1, MBC: 20083 mg·kg-1), followed by the intermediate particle size (0.075-0.25 mm) (SBC: 37376 mg·kg-1, MBC: 13199 mg·kg-1) and the largest particle size (0.25-1 mm) (SBC: 27749 mg·kg-1, MBC: 12251 mg·kg-1). However, there was little difference in soil P sorption between the three particle sizes of the same biochar in the soil system. In comparison with no biochar treatment, the addition of SBC increased the Langmuir P sorption maximum (Smax) by 236.8%-755.7%, and decreased soil P desorption rate. The addition of MBC increased Smax, but the enhancement was less than that of SBC. Soil P desorption rate was increased by 7.2%-295.9%. Both SBC and MBC significantly increased the contents of soil total P, available P, and exchangeable calcium (Ca) and magnesium (Mg). The increases in Ca and Mg contents due to biochar addition was 64.0%-257.1% (SBC) and 39.1%-205.3% (MBC), respectively. The contents of soil exchangeable Ca and Mg were positively correlated with Smax. These results suggested that biochar particle size had little effect on soil P sorption, but the enrichment of Ca and Mg due to biochar addition played a critical role in regulating soil P sorption. The rapeseed straw biochar had a high adsorption capacity for soil P, making it suitable for improving the P fixation capacity of soil rich in P and reducing the loss of excess P. Chicken manure biochar could be used to improve the P availability of low P soils and increase the contents of available P.

Cross‐depth connectivity shows that deep kelps may act as refugia by reseeding climate‐vulnerable shallow beds

AbstractRefugia are habitats where species can survive or retreat to during environmental disturbances. One key assumption of habitats that constitute refugia is that they may assist in the persistence of impacted populations through the provision of reproductive propagules. This “reseeding” hypothesis assumes that demographic connectivity exists between refugia and impacted habitats. We tested this hypothesis for the kelpEcklonia radiata, a temperate marine foundation species dominant in the temperate coast of Australia. Our study site was the coast of Western Australia, a system where deep habitats are considered to act as refugia for their shallow counterparts, yet, for which estimations of population connectivity have overlooked propagule dispersal across depth. Here, we simulated the dominant ocean circulation conditions in a three‐dimensional oceanographic model and the dispersal of kelp propagules by incorporating physical properties of zoospores within the model. The trajectories of kelp propagules were tracked and analyzed to identify their probability of settlement within the domain of the study. Measurements of kelp fecundity across depth were obtained within the study region, and used to estimate zoospore settlement densities. Here, we show that deep populations ofE. radiatahave the capacity to supply zoospores to shallow reefs. Our results show that zoospores released at deeper beds (40 m of depth) are transported to shallow reefs (&lt;20 m of depth) and that settlement densities are sufficient to drive kelp fertilization. Analysis of particle exchange among depths also indicates that mid‐depth reefs (~25 m of depth) act as important “stepping stones” for cross‐depth connectivity, enhancing dispersal between the shallowest and deepest locations, which is especially important when reefs of different depths are separated by tens of kilometers. We show that after an environmental disturbance, persistent deep kelps may act as refugia by sourcing propagules and reseeding impacted shallow reefs, provided that environmental conditions are adequate for kelp recruitment and growth. This study demonstrates that through propagule exchange, populations of habitat‐building species living in areas undamaged by biophysical disturbances may reseed their impacted counterparts, aid their recovery if conditions are adequate for regrowth, and ensure their persistence.

Parallelized domain decomposition for multi-dimensional Lagrangian random walk mass-transfer particle tracking schemes

Abstract. Lagrangian particle tracking schemes allow a wide range of flow and transport processes to be simulated accurately, but a major challenge is numerically implementing the inter-particle interactions in an efficient manner. This article develops a multi-dimensional, parallelized domain decomposition (DDC) strategy for mass-transfer particle tracking (MTPT) methods in which particles exchange mass dynamically. We show that this can be efficiently parallelized by employing large numbers of CPU cores to accelerate run times. In order to validate the approach and our theoretical predictions we focus our efforts on a well-known benchmark problem with pure diffusion, where analytical solutions in any number of dimensions are well established. In this work, we investigate different procedures for “tiling” the domain in two and three dimensions (2-D and 3-D), as this type of formal DDC construction is currently limited to 1-D. An optimal tiling is prescribed based on physical problem parameters and the number of available CPU cores, as each tiling provides distinct results in both accuracy and run time. We further extend the most efficient technique to 3-D for comparison, leading to an analytical discussion of the effect of dimensionality on strategies for implementing DDC schemes. Increasing computational resources (cores) within the DDC method produces a trade-off between inter-node communication and on-node work. For an optimally subdivided diffusion problem, the 2-D parallelized algorithm achieves nearly perfect linear speedup in comparison with the serial run-up to around 2700 cores, reducing a 5 h simulation to 8 s, while the 3-D algorithm maintains appreciable speedup up to 1700 cores.