Equivalent Particle Size Distribution Research Articles

A remote sensing algorithm for vertically resolved cloud condensation nuclei number concentrations from airborne and spaceborne lidar observations

Abstract. Cloud condensation nuclei (CCN) are mediators of aerosol–cloud interactions (ACIs), contributing to the largest uncertainties in the understandings of global climate change. We present a novel remote-sensing-based algorithm that quantifies the vertically resolved CCN number concentrations (NCCN) using aerosol optical properties measured by a multiwavelength lidar. The algorithm considers five distinct aerosol subtypes with bimodal size distributions. The inversion used the lookup tables developed in this study, based on the observations from the Aerosol Robotic Network, to efficiently retrieve optimal particle size distributions from lidar measurements. The method derives dry aerosol optical properties by implementing hygroscopic enhancement factors in lidar measurements. The retrieved optically equivalent particle size distributions and aerosol-type-dependent particle composition are utilized to calculate critical diameters using κ-Köhler theory and NCCN at six supersaturations ranging from 0.07 % to 1.0 %. Sensitivity analyses indicate that uncertainties in extinction coefficients and relative humidity greatly influence the retrieval error in NCCN. The potential of this algorithm is further evaluated by retrieving NCCN using airborne lidar from the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) campaign and is validated against simultaneous measurements from the CCN counter. The independent validation with robust correlation demonstrates promising results. Furthermore, the NCCN has been retrieved for the first time using a proposed algorithm from spaceborne lidar – Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) – measurements. The application of this new capability demonstrates the potential for constructing a 3D CCN climatology at a global scale, which helps to better quantify ACI effects and thus reduce the uncertainty in aerosol climate forcing.

Mechanical alloying of AlCoCrFe and AlCoCrFeNi: Design and experimental evaluation of medium- and high-entropy alloy particles for cold spraying

The manufacturability of equiatomic high-entropy alloy (HEA) particles with single- and dual-phase crystal structures using the high-energy mechanical alloying (HE-MA) method was explored in this study. Following a material design-of-experiment (DoE) curriculum, particles were synthesized in a planetary mill. Milling times varied while operating under two distinct HE-MA manufacturing regimes: the conventional approach (simultaneous milling of constituent elements) and the sequential method (progressive milling with the introduction of elements in a specific order). Within the conventional regime, equiatomic AlCoCrFe and AlCoCrFeNi blends were milled, focusing on the influence of incorporating nickel (Ni) as a transient element into the base composition. This led to an equivalent particle size distribution ranging from 5 to 100 μm. Notably, the presence of Ni resulted in an increased fraction of the face-centered cubic (FCC) phase, coupled with a simultaneous reduction in grain and crystallite sizes, thereby enhancing the overall material strength. This knowledge was applied to the design and synthesis of a target equiatomic FeNiCoCrAl HEA system. In this context, individual elements were added to the starting/milled Fe + Ni alloy at four-hour intervals, in line with the sequential milling regimen. The results showed an interesting evolution: the conventionally milled AlCoCrFeNi particles exhibited a dual-phase body-centered cubic (BCC) and FCC structure, with a composition of 55% BCC and 45% FCC phase fractions, while the sequentially milled FeNiCoCrAl particles demonstrated a single-phase BCC structure after 24 h of milling.

Effects of mono and binary recycled aggregates on the rheological properties of geopolymer mortars synthesized with construction and demolition waste-based binders

This study comprehensively investigated the effect of different types of fine construction and demolition waste (CDW)-based aggregates, including recycled concrete aggregate (RCA), recycled ceramic tile aggregate (RTA) and recycled brick aggregate (RBA) on the fresh rheological properties of geopolymer mortars (GPMs) derived from CDW-based aluminosilicate binders. The results were compared to those of silica sand (SSA) and natural sand (NSA) with equivalent particle size distribution. In addition, the binary inclusion of RCA, RTA and RBA with 50% SSA or NSA fine aggregates was also considered in an attempt to reach rheological behavior closer to that of SSA and NSA-based GPMs. All mortars were blended with a CDW-binder composed of a ternary mixture of brick (RBP), ceramic (RTP) and concrete waste (RCP) powders optimized at pre-targeted chemical parameters of SiO2/Al2O3 and Na2O/SiO2 of 5.7 and 0.18, respectively. The geometrical shape parameters and packing densities of RCA, RTA, RBA, SSA and NSA aggregate skeletons and geopolymer mortar systems were also evaluated to examine their relationship with the rheological parameters of static and dynamic yield stresses, apparent and plastic viscosities, shear stresses and strains and thixotropy of GPMs. Although the incorporation of CDW-based aggregates resulted in enhanced rheological parameters, they exhibited shear-thinning or pseudoplastic behavior similar to SSA and NSA-GPMs. Yet the addition of RCA with a lower consumption of suspending fluids and reduced non-colloidal interactions than RBA and RTA resulted in overall rheological properties closer to those of SSA and NSA-GPMs, which further improved when combined with SSA or NSA in binary-aggregate-based GPM systems.

Precise mix-design of Ultra-High Performance Concrete (UHPC) based on physicochemical packing method: From the perspective of cement hydration

• A physicochemical packing method to optimize the design of UHPC is proposed. • A new equivalent particle size distribution of hydrated cement is calculated. • The macro characteristics of the newly developed UHPC is evaluated. • The hydration kinetics of the newly developed UHPC is evaluated. • The microstructure development of the newly developed UHPC is evaluated. It is widely accepted that Ultra-High Performance Concrete (UHPC) could be designed by the employment of Modified Andreasen and Andersen (MAA) particle packing model. However, the traditional MAA model only takes into account that dry particles reach the dense packing status under physical conditions, without considering the chemical hydration of wet cement particles. To solve this problem, this study adopts a physicochemical packing method to optimize the mix-design of UHPC through establishing a new equivalent particle size distribution of hydrated cement by applying a multilayer spherical shell model. Based on this, the mix proportion of UHPC is redesigned and the properties of the optimized UHPC are evaluated afterwards. The results show that the optimized mix-design leads to higher particle packing density of UHPC, thereby improving the durability on the premise of guaranteeing the workability and mechanical properties. Meanwhile, the optimized mix-design can also achieve denser micro structures of UHPC matrix, which provides a valuable reference to design UHPC more scientifically and reasonably.

Resuspension of carbon dust collected in Tore Supra and exposed to turbulent airflow: Controlled experiments and comparison with model

This work presents the results of experiments conducted with carbon microparticles collected in the tokamak Tore Supra in order to characterize their resuspension behaviour from a stainless-steel substrate when exposed to turbulent airflow. Experiments were conducted in a wind tunnel with controlled velocity profiles and monitored environmental conditions. A consequent amount of dust has been collected in the vessel of the tokamak and a bimodal particle size distribution of samples is first demonstrated. Comparison with resuspension of alumina powders with equivalent particle size distributions under turbulent airflow is also discussed. Results for both carbon and alumina microparticles are then compared to a theoretical resuspension model. Data reveal that exposing multilayer deposits with bimodal particle size distributions to low-speed flows (i.e. 3–10m/s) induces a significant reduction of the mobilized fractions compared to what was predicted by the model. In addition, results helped to highlight some limitations in the model to physically describe changes in the adhesive strength that can occur with a polydisperse deposit.

Size and density measurement of core–shell Si nanoparticles by analytical ultracentrifugation

Si nanocrystals, terminated with cyclohexane and allylamine, were analyzed using analytical ultracentrifugation (AUC), dynamic light scattering (DLS) and transmission electron microscopy. We found that AUC yielded equivalent particle size distribution data to other nanoparticle characterization techniques, while also providing important information not probed by techniques such as DLS regarding the relative size of the particle core and shell components and the overall effective particle density. Estimates of particle core and shell dimensions are consistent with the particle’s optical properties within the quantum confinement representation and available theoretical Si nanocrystal models. Measurement of sedimentation velocity in several solvents with different densities presents a way to circumvent the ambiguity of simultaneous fitting of particle density and sedimentation coefficient and allows us to significantly reduce the uncertainty in the estimates of particle hydrodynamic diameter by finding the effective particle density value.

Relevance of the setting reaction to the injectability of tricalcium phosphate pastes

The aim of the present work was to analyze the influence of the setting reaction on the injectability of tricalcium phosphate (TCP) pastes. Even if the injection was performed early after mixing powder and liquid, powder reactivity was shown to play a significant role in the injectability of TCP pastes. Significant differences were observed between the injection behavior of non-hardening β-TCP pastes and that of self-hardening α-TCP pastes. The differences were more marked at low liquid-to-powder ratios, using fine powders and injecting through thin needles. α-TCP was, in general, less injectable than β-TCP and required higher injection loads. Moreover, clogging was identified as a mechanism hindering or even preventing injectability, different and clearly distinguishable from the filter-pressing phenomenon. α-TCP pastes presented transient clogging episodes, which were not observed in β-TCP pastes with equivalent particle size distribution. Different parameters affecting powder reactivity were also shown to affect paste injectability. Thus, whereas powder calcination resulted in an increased injectability due to lower particle reactivity, the addition of setting accelerants, such as hydroxyapatite nanoparticles, tended to reduce the injectability of the TCP pastes, especially if adjoined simultaneously with a Na2HPO4 solution. Although, as a general trend, faster-setting pastes were less injectable, some exceptions to this rule were found. For example, whereas in the absence of setting accelerants fine TCP powders were more injectable than the coarse ones, in spite of their shorter setting times, this trend was inverted when setting accelerants were added, and coarse powders were more injectable than the fine ones.

The use of equivalent size distributions of natural phytoplankton assemblages for optical modeling

The effective cell size is expected to be one of the principal causes of variability in the inherent optical properties (IOPs) of a phytoplankton population. However, establishing simple size descriptors is complicated by the typically complex particle size distributions of natural phytoplankton assemblages. This study compares the use of measured and equivalent particle size distributions on the modeled IOPs of a wide range of natural phytoplankton assemblages. It demonstrates that several equivalent size distributions, using simple parameterizations of complex size distributions based on the effective radius or diameter, are capable of modeling phytoplankton IOPs with sufficient accuracy for further use in marine bio-optical models. The results offered here are expected to be of use in bio-optical studies of phytoplankton dynamics e.g. harmful algal bloom oriented inverse reflectance models.

Laser Diffractometry as a Technique for the Rapid Assessment of Aerosol Particle Size from Inhalers

The rapid assessment of aerosols produced by medicinal inhalers is highly desirable from several standpoints, including the assurance of product quality, the development of new delivery systems, and the need to meet an increasing requirement by regulatory bodies for reliable in vitro performance data. Particle size analysis has traditionally been undertaken by cascade impactor on account of the direct assessment of active pharmaceutical ingredient(s) (APIs) that is possible by this method. However, laser diffractometry is less labor-intensive, more rapid, and can be a less invasive procedure. The technique provides meaningful results; as long as precautions are taken to validate that the measurements are an accurate reflection of the distribution of API mass as a function of particle or droplet size. We begin the review by examining the underlying theory of the laser diffraction method. After a brief description of current laser diffractometers used in inhaler measurements, we continue by examining the range of applications by inhaler class. We then examine the basis upon which inhaler measurements made by laser-diffractometry can be compared with equivalent particle size distribution data from compendial techniques. We conclude the assessment of the technique by developing guidelines for its valid application as a component of the range of in vitro methods that are available for inhaler performance assessment.

Measuring Size Distribution of Organic Crystals of Different Shapes Using Different Technologies

AbstractThe ultrasonic attenuation (UA) technique was developed to measure not only particle size distribution (PSD) but also concentration for on‐line and off‐line analysis of high concentration dispersions. Another significant characteristic along with particle size is particle shape. Particle shape influences the apparent particle size as measured by various instruments. Shape factors have been calculated from microscopic images using conventional image analysis (IA) techniques. Particle sizing data measured by UA is more representative than by IA because much larger samples are used for analysis. In this study UA, laser diffraction (LD) and IA size measurements are compared and the influence of particle shape is investigated.Data obtained from UA has been combined with information on shape factor from imaging to obtain equivalent particle size distributions. In a previous study [1], the influence of shape on size measurement has been investigated using different sizing techniques for non‐fragile materials. These particles showed significant variation in measured PSD with their different shapes. In this paper, the same phenomenon was observed with evolving polymorphs of L‐glutamic acid crystals (α and β form), oxalic acid, sucrose and monosodium glutamate.

Transformation of Diffraction Pattern due to Ellipsoids into Equivalent Diameter Distribution for Spheres

If a particle is not spherical, the Fraunhofer diffraction pattern is not circular, however the particle size distribution obtained from conventional particle sizer are made under the assumption of spherical particle. It is, therefore, necessary to discuss or interpret the relationship between the obtained equivalent diameter and the diffraction pattern. In this paper, this transformation problem was discussed principally for the case of ellipsoid particle. A relationship between an original size of ellipsoid and obtained equivalent particle size distribution was given in an analytical expression. The equivalent particle size clearly had double peaks in the size corresponding both to the minor and major diameter of the original ellipsoid. On the other hand, if the original particle had its own size distribution, the double peak was eliminated due to the effect of this original size distribution. In the case of random orientation of the ellipsoid in the sensing zone, the double peak was also eliminated and a rather clear single peak appeared at the minor diameter of the original ellipsoid.

Silicate Mineralogy of the Dust in the Inner Coma of Comet C/1995 01 (Hale‐Bopp) Pre‐ and Postperihelion

We present 7.5-13.4 μm infrared (IR) spectrophotometry (R≃180-360) of the 10 μm silicate emission from dust in the inner coma (i.e., within a diameter of 3'') of comet C/1995 O1 (Hale-Bopp) at four temporal epochs from 1996 October through 1997 June during Hale-Bopp's approach to, arrival at, and recession from perihelion. Hale-Bopp's silicate feature is the strongest observed from any comet to date: the flux-to-continuum ratio at 10.0 μm is 2.5 at 2.8 AU preperihelion, increases to 3.0 at 0.93 AU, and then decreases to 2.4 at 1.7 AU postperihelion, dropping more rapidly in strength than expected from preperihelion spectra and indicating a diminishment in the relative abundance of submicron sized grains by perihelion passage. The silicate feature also evolves with heliocentric distance. When far from perihelion, at ~2.8 AU, the High Efficiency Faint Object Grating Spectrometer (HIFOGS) 10 μm silicate feature contains a 9.3 μm shoulder attributable to amorphous pyroxene, broad emission from amorphous olivine (9.7 μm), and the 11.2 μm peak associated with crystalline olivine. Concurrent with the HIFOGS spectra at 2.8 AU, the Infrared Space Observatory (ISO) Short Wavelength Spectrometer (SWS) spectrum also shows the strong far-IR peaks of crystalline olivine at 18 μm, 23 μm, and 33 μm. When close to perihelion the HIFOGS spectra include a newly discovered 9.3 μm peak, identifiable as Mg-rich crystalline pyroxene. We hypothesize that the crystalline pyroxenes are cooler than the other silicates, too cool to be detected at 9.3 μm at 2.8 AU but warm enough to be detected at 1.2 AU. The best-fit empirical model for the temporal evolution of Hale-Bopp's silicate feature constrains the Mg-rich crystalline pyroxenes to be dominated by ortho-pyroxene rather than clino-pyroxene. The crystalline pyroxenes have a color temperature that is 0.6 times cooler than and an abundance that is about 9 times greater than the other silicates at all epochs, assuming equivalent particle size distributions for all components. Comparing crystalline ortho-pyroxene and crystalline olivine in radiative equilibrium, both with Mg number 0.9, the ortho-pyroxene crystals are cooler because they are less absorbing at visible and near-IR wavelengths. Thus, it is the high Mg content of the crystalline pyroxenes that accounts for their cooler temperature. The dominance of Mg-rich pyroxenes among Hale-Bopp's cometary silicates is consistent with PUMA-1 mass spectrometer measurements of comet P/Halley 1986 III and with cometary interplanetary dust particles. The high Mg content of the pyroxenes in comet Hale-Bopp implies that they are either pristine solar nebula condensates or presolar grains such as the Mg-rich crystals recently discovered by ISO around asymptotic giant branch stars.

Light Scattering Properties of Biotissue Versus Equivalent Particle Size Distribution

An equivalent particle size distribution function n(r) is applied to describe optical scattering property of tissue. Under the Fraunhofer diffraction approximation, both the scattering coefficient μs and the scattering phase function S(θ) are educible from n(r). Moreover, such a scheme provides a new feasible method based on the light scattering techniques for particle size analysis to measure the optical properties of tissue. Experimental results of the whole human blood and a thin porcine muscle sample are also provided and so is a calculation resulting from an optical phantom of tissue. The light scattering equivalency between the practical tissue and the corresponding equivalent particles has been verified.