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Commercially available powders of detonation nanodiamond (DND) contain extrastrong 20–120 nm sized aggregates, in an amount sometimes up to 50% by mass sustainable to the conventional methods of deaggregation. It demonstrates the significant inhomogeneity structure of products of detonation synthesis and noticeably reduces the yield of 4.0 − 5.0 nm individual isolated particles obtained from DNDs. The presence of these aggregates is obviously related to the some essential features of detonation synthesis. This work presents the results of studying such extrastrong aggregates from DND powder. In order to determine the structure we applied the heat treatment of samples in vacuum and in air, and the subsequent study using Raman spectroscopy, X-ray diffraction, UV–vis spectroscopy, analysis of specific surface and dynamic light scattering (DLS). As a result, a structural model of extrastrong aggregates is proposed. It is shown that extrastrong aggregates consist notably of relatively large (∼8.0 nm) single crystalline diamond particles bonded by facets and covered by smaller 4.5 − 3.0 nm and less crystalline grains. Our results add the details for description of formation processes of diamond particles and aggregates in detonation synthesis from excessive carbon in the composition of explosives. [ABSTRACT FROM AUTHOR]

A heterogeneous condensation process facilitates the growth of fine particulate matter, making it more easily removable. The aim of this study was to effectively eliminate pre-existing fine particles in the atmosphere by investigating the growth characteristics of particles in turbulent water vapor environments using experimental and numerical methods. The results reveal that the presence of soluble and hydrophilic particles in atmospheric fine particulate matter enhances their growth compared to coal particles. Increasing temperature differences, reducing particle number concentrations, and elevating the proportion of soluble particle components contribute to particle growth. When the temperature difference is below 10K, particle growth is less effective. The beneficial impact of particle collision and coagulation, partly offsetting water vapor competition, was observed with an increase in particle number concentration. The addition of soluble and hydrophilic components promoted particle activation, further fostering particle growth. The region near the wall exhibited more significant particle growth due to higher supersaturation and lower flow velocity. These findings theoretically support the application of heterogeneous condensation processes in atmospheric purification. [ABSTRACT FROM AUTHOR]

Droplet size is a crucial success factor for increased particle size in the agglomeration process. Thus, this work aimed to analyze the physicochemical properties of maltodextrin solutions used as the binder, their influence on the size of the formed droplets, and their relationship to particle growth. The primary CMC particles had an average size of 295.5 ± 10.0 µm, and at the end of the process, the agglomerates reached chord lengths ranging from 336.5 ± 10.6 µm to 378.3 ± 8.6 µm. Three maltodextrin solutions (5.0%, 20.0%, and 35.0% w/w) were characterized for that in terms of physicochemical properties and droplet size, and following that, the binder concentrations, binder flow rate, and atomizing air pressure were evaluated. The binder liquid concentration is the most outstanding parameter for the agglomeration process regarding particle growth under experimental conditions. [ABSTRACT FROM AUTHOR]

New particle formation (NPF) is considered a major source of aerosol particles and cloud condensation nuclei (CCN); however, our understanding of NPF and the subsequent particle growth mechanisms in coastal areas remains limited. This study provides evidence of frequent NPF events followed by particle growth in the middle Adriatic Sea during the summer months at the coastal station of Rogoznica in Croatia. To our knowledge, this is the first study to report such events in this region. Our research aims to improve the understanding of NPF by investigating particle growth through detailed physicochemical characterization and event classification. We used a combination of online measurements and offline particle collection, followed by a thorough chemical analysis. Our results suggest the role of bromine in the particle growth process and provide evidence for its involvement in combination with organic compounds. In addition, we demonstrated the significant influence of surface-active substances (SAS) on particle growth. NPF and particle growth events have been observed in air masses originating from the Adriatic Sea, which can serve as an important source of volatile organic compounds (VOC). Our study shows an intricate interplay between bromine, organic carbon (OC), and SAS in atmospheric particle growth, contributing to a better understanding of coastal NPF processes. In this context, we also introduced a new approach using the semi-empirical 1st derivative method to determine the growth rate for each time point that is not sensitive to the nonlinear behavior of the particle growth over time. We observed that during NPF and particle growth event days, the OC concentration measured in the ultrafine mode particle fraction was higher compared to non-event days. Moreover, in contrast to non-event days, bromine compounds were detected in the ultrafine mode atmospheric particle fraction on nearly all NPF and particle growth event days. Regarding sulfuric acid, the measured sulfate concentration in the ultrafine mode atmospheric particle fraction on both NPF event and non-event days showed no significant differences. This suggests that sulfuric acid may not be the primary factor influencing the appearance of NPF and the particle growth process in the coastal region of Rogoznica.

During the unprecedented COVID-19 city lockdown, a unique opportunity arose to dissect the intricate dynamics of urban air quality, focusing on ultrafine particles (UFPs) and volatile organic compounds (VOCs). This study delves into the nuanced interplay between traffic patterns and UFP emissions in a subtropical urban setting during the spring-summer transition of 2021. Leveraging meticulous roadside measurements near a traffic nexus, our investigation unravels the intricate relationship between particle number size distribution (PNSD), VOCs mixing ratios, and detailed vehicle activity metrics. The soft lockdown era, marked by a 20–27% dip in overall traffic yet a surprising surge in early morning motorcycle activity, presented a natural experiment. We observed a consequential shift in the urban aerosol regime: the decrease in primary emissions from traffic substantially amplified the role of aged particles and secondary aerosols. This shift was particularly pronounced under stagnant atmospheric conditions, where reduced dilution exacerbated the influence of alternative emission sources, notably solvent evaporation, and was further accentuated with the resumption of normal traffic flows. A distinct seasonal trend emerged as warmer months approached, with aromatic VOCs such as toluene, ethylbenzene, and xylene not only increasing but also significantly contributing to more frequent particle growth events. These findings spotlight the criticality of targeted strategies at traffic hotspots, especially during periods susceptible to weak atmospheric dilution, to curb UFP and precursor emissions effectively. As we stand at the cusp of widespread vehicle electrification, this study underscores the imperative of a holistic approach to urban air quality management, embracing the complexities of primary emission reductions and the resultant shifts in atmospheric chemistry.

• Selective sulfidation of nickel can be achieved under appropriate pO 2 and pS 2. • Appropriate carbon can facilitate the conversion of nickel oxide to nickel sulfide. • Sodium carbonate can improve the growth of synthetic Fe-Ni-S particles. • Under optimal conditions, 85.7% of Ni and only 27.1% of Fe in laterites could be sulfated. Nickel sulfide concentrate was an important raw material for battery-grade nickel sulfate. To efficiently separate nickel from saprolitic laterite to product nickel sulfide concentrate, a novel and clean sulfidation-flotation process aimed to enhance selective sulfidation and particle growth through sodium carbonate was proposed herein. The effects of temperature, time, sulfur dosage, Na salts, and carbon additions on the selective sulfidation of nickel are systematically studied. Experimental results show that sodium carbonate can destroy the silicate structure, release nickel in the silicate, and form a low-melting point phase, promoting the aggregation of nickel sulfide, thereby achieving the purpose of promoting the sulfidation of nickel and the growth of synthetic nickel matte particles. Under the optimal conditions, 85.7% Ni and 27.1% Fe could be sulfated. [ABSTRACT FROM AUTHOR]

Catalytic capacity of ceria mainly stems from a facile switch in the Ce oxidation states from +4 to +4 − x. While various experimental and computational studies pinpoint the reduction chemistry of Ce atom through the creation of oxygen vacancies, the analogous process when ceria surface is decorated with cations remains poorly understood. Where such results are available, a synergy between experimental and first principle calculation is scarce. Niobium materials are evolving and their use in catalysis is being widely investigated due to their high surface acidity and thermal and chemical stability. This study aims to report structural and electronic properties of various configurations of mixed Ce–Nb oxides and elaborates on factors that underpin potential catalytic improvements. Evaluations of the samples through X-ray diffraction (XRD), Fourier transform infrared (FTIR), N2-adsorption–desorption, scanning electron microscope (SEM), energy dispersive spectroscope (EDS), and thermogravimetric (TGA) analyses are examined and discussed. First principles density functional theory (DFT) calculations provide structural features of the Ce–Nb solutions at low concentration of Nb via computing atomic charge distribution. Contraction in the lattice parameter after Nb doping was confirmed with both XRD and DFT results. SEM analysis reveals particle growth at the loading of 50 wt%. FTIR results established the Ce–Nb–O bond at 1,100 cm−1 and the TGA analysis confirms the thermal stability of Nb-doped ceria. Tetrahedral O atoms demonstrate an increase in electronegativity and this in turn facilitates catalytic propensity of the material because the O atoms will exhibit higher affinity for adsorbed reactants. Cerium oxide (CeO2) after Nb doping displays a noticeable band gap narrowing, confirming the possible improvement in the catalytic behavior. The 4d states of the Niobium pentoxide (Nb2O5) is found to fill up the 4f states of CeO2 around the Fermi energy level promoting electrons excitation in the CeO2. Reported electronic, structural, and thermal characteristics herein indicate promising catalytic applications of niobium-promoted ceria.

Utilizing ionizing radiation for in situ studies in liquid media enables unique insights into nanostructure formation dynamics. As radiolysis interferes with observations, kinetic simulations are employed to understand and exploit beam‐liquid interactions. By introducing an intuitive tool to simulate arbitrary kinetic models for radiation chemistry, it is demonstrated that these models provide a holistic understanding of reaction mechanisms. This is shown for irradiated HAuCl4 solutions allowing for quantitative prediction and tailoring of redox processes in liquid‐phase transmission electron microscopy (LP‐TEM). Moreover, it is demonstrated that kinetic modeling of radiation chemistry is applicable to investigations utilizing X‐rays such as X‐ray diffraction (XRD). This emphasizes that beam‐sample interactions must be considered during XRD in liquid media and shows that reaction kinetics do not provide a threshold dose rate for gold nucleation relevant to LP‐TEM and XRD. Furthermore, it is unveiled that oxidative etching of gold nanoparticles depends on both, precursor concentration, and dose rate. This dependency is exploited to probe the electron beam‐induced shift in Gibbs free energy landscape by analyzing critical radii of gold nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract Utilizing ionizing radiation for in situ studies in liquid media enables unique insights into nanostructure formation dynamics. As radiolysis interferes with observations, kinetic simulations are employed to understand and exploit beam‐liquid interactions. By introducing an intuitive tool to simulate arbitrary kinetic models for radiation chemistry, it is demonstrated that these models provide a holistic understanding of reaction mechanisms. This is shown for irradiated HAuCl4 solutions allowing for quantitative prediction and tailoring of redox processes in liquid‐phase transmission electron microscopy (LP‐TEM). Moreover, it is demonstrated that kinetic modeling of radiation chemistry is applicable to investigations utilizing X‐rays such as X‐ray diffraction (XRD). This emphasizes that beam‐sample interactions must be considered during XRD in liquid media and shows that reaction kinetics do not provide a threshold dose rate for gold nucleation relevant to LP‐TEM and XRD. Furthermore, it is unveiled that oxidative etching of gold nanoparticles depends on both, precursor concentration, and dose rate. This dependency is exploited to probe the electron beam‐induced shift in Gibbs free energy landscape by analyzing critical radii of gold nanoparticles.

Colloidal metal nanoparticles in an electrolyte environment are not only electrically charged but also electrochemically active objects. They have the typical character of metal electrodes with ongoing charge transfer processes on the metal/liquid interface. This picture is valid for the equilibrium state and also during the formation, growth, aggregation or dissolution of nanoparticles. This behavior can be understood in analogy to macroscopic mixed-electrode systems with a free-floating potential, which is determined by the competition between anodic and cathodic partial processes. In contrast to macroscopic electrodes, the small size of nanoparticles is responsible for significant effects of low numbers of elementary charges and for self-polarization effects as they are known from molecular systems, for example. The electrical properties of nanoparticles can be estimated by basic electrochemical equations. Reconsidering these fundamentals, the assembly behavior, the formation of nonspherical assemblies of nanoparticles and the growth and the corrosion behavior of metal nanoparticles, as well as the formation of core/shell particles, branched structures and particle networks, can be understood. The consequences of electrochemical behavior, charging and self-polarization for particle growth, shape formation and particle/particle interaction are discussed.

• Multiphase Eulerian model along with population balance equations were applied. • To implement four-way coupling, aggregation and breakage were considered. • A rise in impeller speed is one of the major contributors to mass exchange. • The speed of 330 rpm showed to be optimal in terms of particles residence time. In the present paper, the liquid–solid two-phase turbulent flow in a Draft Tube Baffled crystallizer has been simulated using Computational Fluid Dynamics. In this respect, multiphase Eulerian model along with population balance equations were applied. To implement four-way coupling, aggregation and breakage were considered. The RNG k-ε and RSM turbulence models were employed to conduct numerical simulation of two phase turbulent flow. Results demonstrated that applying RNG k-ε and RSM turbulence models, a significant difference in axial velocity profiles along the x-axis is observed, while those along the z-axis exhibit less difference. Moreover, a significant difference in volume fraction between the two models was observed which mostly concerns the region within the draft tube and the distance between the baffle and crystallizer wall. Furthermore, changing the propeller speed from 165 to 495 rpm, the speed of 330 rpm showed to be optimal in terms of particles residence time. The results also showed that a rise in impeller speed is one of the major contributors to mass exchange enhancement between the liquid and the solid phases. Accordingly, as the impeller speed rises, the rate of mass exchange increases from 9.92 kg/h for 165 rpm to 29.07 kg/h for 495 rpm. [ABSTRACT FROM AUTHOR]

Supersonic plumes of water vapour and icy particles have been observed by the Cassini spacecraft during several flybys over Enceladus. These plumes originate from the Tiger Stripes located in the South Polar Terrain (SPT), and indicate the presence of a subsurface ocean under the icy crust which is salty and contains complex organic molecules. Other characteristics of the plumes, such as the vent temperature, mass flow rate, velocity and mass fraction of icy particles can be used to determine the conditions in the channel, linking the subsurface ocean to the icy surface. In this paper, we developed a fluid dynamics model that accounts for nucleation, particle growth, wall accretion and sublimation. The channel behaves similarly to a converging–diverging nozzle, which forms supersonic plumes due to a pressure difference between the reservoir where the subsurface ocean is located and the exosphere. The geometry of the channel and its evolution with accretion of gas and sublimation of ice are studied to reproduce the characteristics of the plumes observed by Cassini. We first performed a parameter study on the channel geometry to determine how it influences the plumes' velocity, solid fraction and exit temperature. Our results show that the size of the icy particles is primarily dependent on the length of the channel, indicating that large particles (∼ 75 μ m) must originate from within a kilometer below the surface, while smaller particles (∼ 3 μ m) can originate from only hundreds of meters below the surface. We further show that the velocity of the flow, exit temperature and nucleation depend directly on the exit-to-throat size ratio. We find that the channel geometry evolves within a few tens of hours until an equilibrium is reached, when considering the accretion of gas to the walls, or sublimation of ice from the walls. As the channel closes due to accretion, the flow becomes thinner, which in turn reduces accretion. After around 70 h, the accretion is sufficiently slowed such that the geometry does not evolve anymore. This equilibrium geometry produces higher Mach numbers and a larger particle size and solid fraction compared to the initial geometry. • On Enceladus, a Saturnian moon, supersonic plumes of water ice and vapour have been observed. • These plumes indicate the presence of a liquid subsurface ocean hidden under kilometers of ice. • We studied numerically the plumes as they develop from the ocean to the surface through channels. • We found that the size of the icy grains observed in the plumes can constrain the length of the channels. • The plumes' velocity and temperature constrain the expansion (throat to exit) ratio of the channel. • Water accretion changes the channel's geometry within hours and increases the expansion ratio. [ABSTRACT FROM AUTHOR]

[Display omitted] Combination of microwave irradiation (MWI) and ionic liquids (IL) is widely used for the synthesis of nanoparticles (NP) via decarbonylation of zero-valent metal carbonyl precursors. However, we carefully raise a question as to whether this combination is always beneficial. Upon MWI, highly-absorbing materials such as ILs would be subject to local intense heating, likely resulting in the occurrence of localized chemical decomposition. The decomposition is expected to influence the growth mechanism of NPs due to changes in the electrostatic and steric effects. If the assumption is valid, it should be possible to decompose IL and destabilize the NPs by modifying the amplitude of the incident microwaves. In other words, it should also be possible to control the particle aggregation by circumventing the decomposition of the IL. A series of comparative studies were conducted using a model system (i.e. [BMIm][BF 4 and Ru 3 (CO) 12). Variables were systematically controlled. After MWI, the decrease in colloidal stability of NPs was identified. In the formation of Ru NPs via decarbonylation, the association between incident microwave intensity, chemical decomposition of IL, and initiation of particle aggregation has been demonstrated. Conditions that can accelerate or alleviate the decomposition and the aggregation are also corroborated. [ABSTRACT FROM AUTHOR]

Definition: Colloidal metal nanoparticles in an electrolyte environment are not only electrically charged but also electrochemically active objects. They have the typical character of metal electrodes with ongoing charge transfer processes on the metal/liquid interface. This picture is valid for the equilibrium state and also during the formation, growth, aggregation or dissolution of nanoparticles. This behavior can be understood in analogy to macroscopic mixed-electrode systems with a free- floating potential, which is determined by the competition between anodic and cathodic partial processes. In contrast to macroscopic electrodes, the small size of nanoparticles is responsible for significant effects of low numbers of elementary charges and for self-polarization effects as they are known from molecular systems, for example. The electrical properties of nanoparticles can be estimated by basic electrochemical equations. Reconsidering these fundamentals, the assembly behavior, the formation of nonspherical assemblies of nanoparticles and the growth and the corrosion behavior of metal nanoparticles, as well as the formation of core/shell particles, branched structures and particle networks, can be understood. The consequences of electrochemical behavior, charging and self-polarization for particle growth, shape formation and particle/particle interaction are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Notable shifts of ultrafine particle (UFP) sources and dynamics during lockdown. • Motorbikes unexpectedly rise during lockdown spotlights a key pollution contributor. • Lockdown acts as a catalyst for frequent and significant UFP growth events. • Soft lockdown intensify aged traffic exhaust and solvent impacts on urban air quality. During the unprecedented COVID-19 city lockdown, a unique opportunity arose to dissect the intricate dynamics of urban air quality, focusing on ultrafine particles (UFPs) and volatile organic compounds (VOCs). This study delves into the nuanced interplay between traffic patterns and UFP emissions in a subtropical urban setting during the spring-summer transition of 2021. Leveraging meticulous roadside measurements near a traffic nexus, our investigation unravels the intricate relationship between particle number size distribution (PNSD), VOCs mixing ratios, and detailed vehicle activity metrics. The soft lockdown era, marked by a 20–27% dip in overall traffic yet a surprising surge in early morning motorcycle activity, presented a natural experiment. We observed a consequential shift in the urban aerosol regime: the decrease in primary emissions from traffic substantially amplified the role of aged particles and secondary aerosols. This shift was particularly pronounced under stagnant atmospheric conditions, where reduced dilution exacerbated the influence of alternative emission sources, notably solvent evaporation, and was further accentuated with the resumption of normal traffic flows. A distinct seasonal trend emerged as warmer months approached, with aromatic VOCs such as toluene, ethylbenzene, and xylene not only increasing but also significantly contributing to more frequent particle growth events. These findings spotlight the criticality of targeted strategies at traffic hotspots, especially during periods susceptible to weak atmospheric dilution, to curb UFP and precursor emissions effectively. As we stand at the cusp of widespread vehicle electrification, this study underscores the imperative of a holistic approach to urban air quality management, embracing the complexities of primary emission reductions and the resultant shifts in atmospheric chemistry. [ABSTRACT FROM AUTHOR]

In order to study the growth characteristics of submicron particles by water vapor condensation in the multi-section growth tube, the three-stage heterogeneous condensation process model was used to predict the size distribution of grown droplets. And the supersaturated environment is formed by the cool saturated flow into a warm-walled growth tube. The calculated results show that with the increase of the section number of the growth tube, the more obviously enhanced growth effect is presented when the growth tube length is shorter and the particle number concentration is lower. Nevertheless, the increase of the section number has more advantages of particle enlargement when the CO 2 concentration improved. Additionally, more section number of growth tube could strongly improve the particle growth on the condition of elevating the wall temperature compared with the situation of reducing the inlet temperature. Meanwhile, the final mean size of grown droplets could be enhanced by 16.03% and 3.46% with the section number from 5 increasing to 15 in the case of promoting wall temperature or declining inlet temperature by 10 K, respectively. [Display omitted] • The more section number improve growth strongly with the reduction of tube length. • The more section number is in favor of better growth with lower particle number. • The increase of section number is more beneficial to enlargement when CO 2 improved. • Strongly enhanced growth is shown on more section and elevating wall temperature. [ABSTRACT FROM AUTHOR]

This work aims to elucidate the particle growth mechanism during agglomeration using a bottom-spray fluidized bed process to produce technical catalysts. The influences of the fundamental operating parameters of the granulation process were investigated through (i) experiments in a newly designed small-scale bottom-spray fluidized bed reactor, (ii) morphological characterization of the catalytic particles produced, (iii) dimensionless number analysis, and (iv) principal component analysis. These results could define the growth stage as dust formation, seed formation, agglomeration, and dust integration or layering. The particle growth mechanism results from the complex interplay of several effects and forces (mass transfer, viscous force, inertial force, surface tension, and gravity), and the prevailing growth stage can be linked with the Weber (We) and capillary (Ca) numbers (i.e., low values of We = 5.7 and Ca = 1.4 leads to layering growth and high values of We = 19.1 and Ca = 7.1 results in dust formation). [Display omitted] • A newly designed bottom-spray fluidized bed to produce technical catalysts. • Elucidation of the particle stage growth during agglomeration. • Several dimensionless numbers enable the assessment of the growth stages. • Low We & Ca lead to layering and high We & Ca result in dust formation. • Principal component analysis identifies the main parameters controlling the growth. [ABSTRACT FROM AUTHOR]

The condition of oligo-micelle formation of sodium di-isodecyl sulfosuccinate (SDIDS) emulsifier in hydroalcoholic solutions is used to study particle formation of vinyl chloride emulsion polymerization in a batch reactor. The change on micellization behavior was investigated by critical micelle concentration (CMC) and zeta potential parameters. To detect the occurrence of secondary nucleation or particle aggregation, or both the particle size and number of particles were investigated as a criterion for the particle nucleation and growth process. The results showed that the alcohol (co-solvent) content had a strong effect on the oligo-micelles formation and emulsion polymerization performance. Namely, decreasing the alcohol content and increasing the anion content in the SDIDS samples increased the overall reaction rate and latex stability. This also decreased the chain growth rate, the particle size, and the coarse particle formation. Also, the results showed that different condition of oligo-micelle formation would lead to different particle growth history

The variations of the concentration and characteristics of particulate matter (PM) are influenced by several factors, such as emission sources and meteorological conditions. In this study, fine particles (PM2.5) and ultrafine particles (PM0.1) were simultaneously collected during summer and winter in Hanoi, Vietnam, to clarify the behavior of PM0.1 (which is rarely observed in this region) by characterizing the chemical components of each particle size in order to clarify particle formation and growth in two seasons with different humidity. The results showed that organic carbon (OC) and elemental carbon (EC) were the major compounds in both size ranges of PM, accounting for up to 56% and 80% of the analyzed components in PM2.5 and PM0.1, respectively. Secondary organic carbon (SOC) accounted for 36–41% and 37–47% of the total OC in PM2.5 and PM0.1, respectively, indicating an important contribution of secondary sources to OC. The strong correlations between water-soluble organic carbon (WSOC) and both sulfate (SO42−) and nitrate (NO3−) showed that photochemical reactions contributed considerably to WSOC formation. Furthermore, the correlations between absolute humidity and other chemical components suggest that the PM2.5 collected in Hanoi was formed by secondary processes in the aqueous phase on the aerosol surface. In contrast, no correlation was found between the relative humidity and other chemical components. These observations indicate that particle growth is dependent on the number of water molecules above a certain level under drizzle-like weather conditions particular to the study region, whereas occasional heavy rain during the sampling period might have hindered those processes. [ABSTRACT FROM AUTHOR]

New particle formation (NPF) can influence the Earth's radiative budget when the newly formed particles grow to climate‐relevant sizes. Here, we present analysis of 21 months of continuous aerosol size distribution measurements at a background remote site in the western Himalaya and provide observational evidence that newly formed particles grow to cloud condensation nuclei (CCN)‐active sizes (i.e., >20–100 nm in diameter). Out of total 55 NPF events, 38 (66%) events occurred in the pre‐monsoon season (March–May). NPF events were classified into those with and without pollution influence as polluted and cleaner, respectively, using black carbon data. The analysis of air mass age, based on the ratio of number concentration of Aitken to accumulation mode aerosols, indicated that NPF occurred in the relatively cleaner air masses reaching to the site. The median formation rate of 10 nm particles and particle growth rates for cleaner events were three‐fold and two‐fold, respectively, higher than polluted events. We present the first estimates of the survival probability of newly formed particles to 50 and 100 nm size, which was not attempted in an Indian environment previously. The survival probability to 50 nm particles ranged from 44% to 98%, with a mean and standard deviation of 82 ± 18%. On average, ∼60% of the particles surviving to 50 nm survived to 100 nm, making the overall survival probability of 100 nm to 53 ± 31%. This indicates that the probability of nucleated particles growing to CCN‐active sizes under a large source of condensing vapor (transported from nearby lower‐altitude regions) and low pre‐existing particle concentrations (background mountain site) is high compared to the previous studies. These findings highlight the importance of the efficiency of nucleation events for producing CCN, which is a critical basis of aerosol indirect effects. Key Points: We present new measurement‐based evidence of the contribution of new particle formation (NPF) to climate‐relevant aerosols in the Western HimalayaNPF occurred frequently in the pre‐monsoon (March–May) seasonNPF rates were higher for cleaner events than polluted events [ABSTRACT FROM AUTHOR]

New particle formation (NPF) is considered a major source of aerosol particles and cloud condensation nuclei (CCN); however, our understanding of NPF and the subsequent particle growth mechanisms in coastal areas remains limited. This study provides evidence of frequent NPF events followed by particle growth in the middle Adriatic Sea during the summer months at the coastal station of Rogoznica in Croatia. To our knowledge, this is the first study to report such events in this region. Our research aims to improve the understanding of NPF by investigating particle growth through detailed physicochemical characterization and event classification. We used a combination of online measurements and offline particle collection, followed by a thorough chemical analysis. Our results suggest the role of bromine in the particle growth process and provide evidence for its involvement in combination with organic compounds. In addition, we demonstrated the significant influence of surface-active substances (SAS) on particle growth. NPF and particle growth events have been observed in air masses originating from the Adriatic Sea, which can serve as an important source of volatile organic compounds (VOC). Our study shows an intricate interplay between bromine, organic carbon (OC), and SAS in atmospheric particle growth, contributing to a better understanding of coastal NPF processes. In this context, we also introduced a new approach using the semi-empirical 1 st derivative method to determine the growth rate for each time point that is not sensitive to the nonlinear behavior of the particle growth over time. We observed that during NPF and particle growth event days, the OC concentration measured in the ultrafine mode particle fraction was higher compared to non-event days. Moreover, in contrast to non-event days, bromine compounds were detected in the ultrafine mode atmospheric particle fraction on nearly all NPF and particle growth event days. Regarding sulfuric acid, the measured sulfate concentration in the ultrafine mode atmospheric particle fraction on both NPF event and non-event days showed no significant differences. This suggests that sulfuric acid may not be the primary factor influencing the appearance of NPF and the particle growth process in the coastal region of Rogoznica., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

New particle formation and growth greatly influence air quality and the global climate. Recent CERN Cosmics Leaving OUtdoor Droplets (CLOUD) chamber experiments proposed that in cold urban atmospheres with highly supersaturated HNO 3 and NH 3 , newly formed sub-10 nm nanoparticles can grow rapidly (up to 1000 nm h -1 ). Here, we present direct observational evidence that in winter Beijing with persistent highly supersaturated HNO 3 and NH 3 , nitrate contributed less than ∼14% of the 8-40 nm nanoparticle composition, and overall growth rates were only ∼0.8-5 nm h -1 . To explain the observed growth rates and particulate nitrate fraction, the effective mass accommodation coefficient of HNO 3 (α HNO 3 ) on the nanoparticles in urban Beijing needs to be 2-4 orders of magnitude lower than those in the CLOUD chamber. We propose that the inefficient uptake of HNO 3 on nanoparticles is mainly due to the much higher particulate organic fraction and lower relative humidity in urban Beijing. To quantitatively reproduce the observed growth, we show that an inhomogeneous "inorganic core-organic shell" nanoparticle morphology might exist for nanoparticles in Beijing. This study emphasized that growth for nanoparticles down to sub-10 nm was largely influenced by their composition, which was previously ignored and should be considered in future studies on nanoparticle growth.

A model is proposed for particle growth in the stabilizer‐free dispersion copolymerization of styrene (ST) and maleic anhydride (MAH). The model is based on the assumptions that 1) polymerization occurs in both the continuous phase and the polymer particles, 2) the nucleation step is fast, and the number of polymer particles is fixed during the process, 3) the particle population is monodisperse, 4) the propagation step between ST and MAH follows the terminal model, and 5) the termination step is diffusion‐controlled, causing an autoacceleration effect in the process. The model predicts the global conversion, copolymer composition and the polymer particle diameter during time. The validation data are obtained experimentally by stabilizer‐free dispersion copolymerization and the model predictions are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

X‐ray‐radiolysis‐induced photochemical reaction of a liquid solution enables the direct synthesis and immobilization of nano/micro‐scale particles and their aggregates onto a desired area. As is well known, the synthesis, growth and aggregation are dependent on the pH, additives and X‐ray irradiation conditions. In this study, it was found that the topography and composition of synthesized particles are also dependent on the types of substrate dipped in an aqueous solution of Cu(COOCH3)2 in the X‐ray‐radiolysis‐induced photochemical reaction. These results are attributed to the fact that a secondary electron induced by the X‐ray irradiation, surface or interface on which the particles are nucleated and grown influences the particle shape and composition. This study will shed light on understanding a novel photochemical reaction route induced under X‐ray irradiation. The development of this process using the X‐ray‐radiolysis‐induced photochemical reaction in aqueous liquids enables us to achieve the rapid and easy operation of the synthesis, growth and immobilization of special nano/micro‐scale complex materials or multifunctional composites. [ABSTRACT FROM AUTHOR]

An Eulerian–Eulerian model coupled with a population balance model (PBM) is adopted to investigate the growth process of polysilicon particles in a polysilicon fluidized bed reactor. A novel particle growth model, considering the effect of interphase velocity difference, is proposed and incorporated into PBM. The interphase mass transfer rate and particle growth rate are obtained based on the modified PBM. The effects of operating velocity and silane mole fraction on the particle growth rate and deposition efficiency are also analyzed. The results show that silicon fines scavenging occurs in the solid phase, especially in central and near-wall regions. Moreover, the increases of operating velocity and silane mole fraction lead to the decrease in the deposition efficiency. [ABSTRACT FROM AUTHOR]

Rock strength variation is closely related to its microstructure. With the development of computer technology, the numerical model of rocks can be constructed via computer programming, and the numerical simulation avoids a mass of redundant experimental tests and usually limited by the samples retrieved from the sub-surfaces. In previous studies, the microstructure in the numerical model is generated randomly. In this paper, a novel methodology for generating the polycrystalline rock microstructure by a Voronoi grain-based model with particle growth is proposed. The 3D Voronoi tessellations in this numerical model generation procedure do not consist of random poly-crystals; the distribution of the poly-crystals varies in shapes and sizes, which represent different mineral grains, and is determined by petrographic data with the 3D particle growth method. The uniaxial compression tests and tension tests are simulated via a combined FDEM and cohesive crack propagation model. The results demonstrate that the numerical simulation agrees well with the experimental study. More importantly, the fracture patterns in the micro-scale are gained, similar to the results obtained from laboratory experiments. The novel Voronoi grain-based model with the particle growth method can reconstruct the microstructure of polycrystalline rocks and provide further information in understanding the micro-behaviors of rock materials. [ABSTRACT FROM AUTHOR]

Microsilica particles arise as a byproduct of silicon furnace operation, created inside high temperature ames due to the combustion reaction of silicon monoxide with oxygen. These nanoparticles, which grow as silicon dioxide vapor condenses on the surface of existing particles, are used in a variety of composite materials. The size and quality of the particles affect the performance of the material used for such applications, and hence control of these quantities is of importance to manufacturers. Motivated by this, we derive a mathematical model that connects local thermal and chemical concentrations conditions to the formation and growth of microsilica particles. We consider two distinct reductions of our general model: the case of initially well-mixed or spatially homogeneous chemical species (modeling the region within the ame or reaction zone), and the case of initially spatially separated chemical species, in which diffusion will play a dominant role in providing material to a combustion front (modeling a larger cross section, which contains a reaction zone with limiting quantities of fuel which must diffuse into the reaction zone). In both cases, we provide asymptotic solutions for the temperature, chemical concentrations, and number density function of microsilica particles in the oxygen rich limit, and compare them to numerical simulations. Motivated by realistic furnace control mechanisms, we treat the relative quantity of oxygen to other fuel components and the saturation concentration of silicon dioxide as control parameters, discussing how each may be used to modify the properties (such as size and abundance) of microsilica particles formed. One physically interesting finding is the theoretical description of a bimodal distribution for microsilica particle size which was previously observed in experiments. [ABSTRACT FROM AUTHOR]

The paper deals with the issue of particle growth in a two-component alloy. The particle is formed from chemical reaction products that occur at the phase boundary. A generalized mathematical model of particle growth includes diffusion equations, mass transfer equations in the boundary layer, and equations characterizing a change in the growing particle radius. The paper proposes an approach that reduces issues to the system of PDEs and ODE that describes the state of growing particle. This approach provides a basis for developing a numerical method for calculating the growing particle radius as a function of time, based on the obtained equations. The computational scheme involves the finite-difference analogues of equations with an additional regularizing functional that ensure method stability with respect to accumulated computational error. In order to verify reliability of the proposed computational scheme and to obtain experimental error estimates of numerical solutions, computational experiments were carried out. In the experiments, the growing particle radius is determined with respect to the time via the proposed method. Also, comparative analysis of the calculated radius with test values was carried out and experimental estimates of deviations of the calculated radius from the test functions were obtained. The experiment results presented in the work indicate sufficient accuracy of the developed numerical method. [ABSTRACT FROM AUTHOR]

Bio-synthesis approach for gold nanoparticles (AuNPs) has received tremendous attention as an efficient and eco-friendly process. However, kinetic growth and colloidal stability of AuNPs synthesized by this process remained challenging. In this study, Elaeis guineensis (oil palm) kernel (OPK) extract prepared in an ionic liquid (IL)[EMIM][OAc] (1-ethyl-3-methylimidazolium acetate) was employed to control and tune the size and morphology of AuNPs. Synthesized AuNPs were characterized using UV-vis spectrophotometer, dynamic light scattering (DLS) and transmission electron microscopy (TEM) to observe any changes in absorbance, surface charge and particle size, respectively. IL mediated AuNPs were examined for 120 days and found well dispersed and stable at room temperature. UV-vis analysis demonstrated that volume of extract played an important role to control the stability of AuNPs. After 120 days, only 8.86% reduction from maximum absorbance was observed using 2 mL of volume of extract, which was elevated to 47.64% in case of 0.3 mL. TEM analysis was performed periodically after day 1, day 30, day 60, day 90 and day 120 and minor increase in the size was observed. Insignificant change in zeta potential value after 120 days supported enhanced stability of IL mediated AuNPs. Crystalline nature of AuNPs was confirmed by X-ray diffraction (XRD) pattern. The particles size and zeta potential of AuNPs was measured as 8.72 nm and −18.7 mV, respectively. However, the absence of [EMIM][OAc] from OPK extract resulted into larger particles size (9.64 nm), low zeta potential value (−13.9 mV) and enhanced aggregation of particles. Finally, experimental data were used to predict the theoretical and the experimental settling time for AuNPs to evaluate colloidal stability. [ABSTRACT FROM AUTHOR]

The microstructure and microhardness of isothermally aged Al-0.22Zr and Al-0.32Zr alloys were investigated. Peak microhardness occurred after aging at 650K for 100 h for both alloys and decreased slightly after aging at 400 h. Nanometer-scale spherical L12-structured Al3Zr precipitates were observed using Transmission Electron Microscopy, these presented r < 7 nm at the center of dendrite branches. In the Al-0.32Zr alloy, particles increased in radius after aging at 650 K from 100 to 400 h while in the Al-0.22Zr alloy, precipitate radii remained constant in the same range. This is possibly due to solute migration to the periphery of dendritic branches, where larger particles nucleated. After aging at 700 K for 100h, there are growth instabilities at the interface of the particles. A theoretical model, used to predict particle growth by diffusion, presented good agreement with the experimental findings.

The moving boundary problem of particle growth in the convective undercooled melt driven by a straining flow is studied by means of the multiple variable expansion method. The resulting uniformly valid asymptotic solution shows the growth behavior of a spherical particle in the straining flow. The straining flow enhances the energy transfer rate and results in higher local growth velocity of the particle near the interface where the flow is incoming, whereas near the interface where the flow is outgoing, the straining flow decreases the energy transfer rate and results in lower local growth velocity of the particle. Because of the difference in local interface growth velocities of the particle, the interface of the particle opposite to the incoming straining flow protrudes outward more significantly than that facing the outgoing straining flow, an initially spherical particle in the undercooled melt with the straining flow evolves to be gravely distorted into different shapes. [ABSTRACT FROM AUTHOR]

Abstract We developed a new modeling framework to simulate aerosol microphysics by incorporating a volatility basis-set (VBS) organic aerosol (OA) module into a three-dimensional (3-D) atmospheric transport model, namely, Nested Air Quality Prediction Modeling System with an Advanced Particle Microphysics (NAQPMS + APM). The new model calculates not only the condensation of sulfuric acid, nitrate, and ammonium and the coagulation of five types of particles (namely secondary, sea salt, dust, black carbon and organic carbon particles) but also the condensation of low-volatility organic vapors and the equilibrium partitioning of semi-volatile organic compounds. The new model was applied to simulate new particle formation (NPF) in summer in Beijing. The new model could noticeably improve the NPF simulation. On comparing the simulation with observation, the ion-mediated nucleation scheme was found to underestimate nucleation rates in summer in Beijing. By incorporating a nucleation formula involving the participation of organic compounds, NPF events could be reproduced satisfactorily. Reasonably calculating nucleation rates is essential for successfully simulating NPF. Accounting for the condensation of anthropogenic low-volatility organic vapors and the volatility of primary OA (POA) can improve the temporal variation of the number concentrations of particles in Aitken and accumulation modes. On a regional scale, anthropogenic low-volatility secondary organic gases (LV-SOGs) and the volatility of POA have large impacts on the aerosol number concentration and cloud condensation nuclei (CCN) concentration. Both anthropogenic LV-SOGs and volatility of POA must be considered to quantify the contribution of NPF to the aerosol number concentration and CCN concentration. Highlights • The study developed a new 3-D model with aerosol microphysics and VBS module. • The new model well improves the simulation of new particle formation events. • H 2 SO 4 -Org nucleation can enhance and improve the calculation of nucleation rates. • The anthropogenic low volatile organics significantly contribute to particle growth. • The volatility of POA has large impacts on particle number and CCN concentration. [ABSTRACT FROM AUTHOR]

Abstract A custom-built steam-based aerosol collector (SBAC) was developed to improve the detection limits in aerosol chemical analysis. The SBAC was coupled with wet chemical analytical instruments to characterize the chemical composition of ambient particulate matter with high-time resolution. The particulate matter was mixed with a jet of steam and formed large droplets because of the supersaturation condition in the cooling chamber. The enlarged droplets were subsequently collected using an inertial aerosol separator and delivered to selected instruments for chemical analysis. Experiments were subsequently conducted to evaluate our custom-built SBAC under various sampling flow rates. In particular, particle growth and particle collection efficiency experiments were conducted, and the SBAC was compared with a filter-based sampler. Sample solutions were collected, extracted, and analyzed to determine the influence of sampling flow rate, particle size, and aerosol chemical concentration on the SBAC's collection efficiency. The SBAC was found to provide data with a higher time resolution, to exhibit an improved detection limit, and to effectively perform aerosol chemical analysis compared with the filter-based samplers, although the effect of flow rate on SBAC performance is complicated and further experiments on this aspect are warranted. This paper contributes to the literature by providing guidelines for designing a SBAC for aerosol chemical analysis. [ABSTRACT FROM AUTHOR]

Background: Nanosuspensions, liquid dispersions with nanometer size distribution, are becoming trendy in pharmaceutical practice to formulate poorly water-soluble drugs and to enhance their bioavailability. Generally, nanosuspensions are produced in two main approaches; top-down or bottom-up. The former is based on size-reduction of large particles via milling or high pressure homogenization. The latter is focused on the mechanisms of nucleation and particle growth. Methods: In this review, the critical factors influencing the kinetics or dynamics of nucleation and growth are discussed. Subsequently, the mechanisms of nanosuspension instability as well as strategies for stabilization are elaborated. Furthermore, the effects of stabilizers on key parameters of instability as well as the process of choosing an appropriate stabilizer is discussed. Results: Steric and electrostatic stabilizations or combination of them is essential for nanosuspensions formulation to prevent coagulation. Accordingly, some characteristics of stabilizers play critical role on stability and optimization of nanosuspensions; i.e., HLB and concentration. Nevertheless, after reviewing various articles, it is ascertained that each formulation requires individual selection of surfactants according to the parameters of the particle surface and the medium. Conclusions: Based on the results, application of excipients such as stabilizers requires proper optimization of type and concentration. This implies that each formulation requires its own optimization process. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Precise control over particle composition and morphology is essential for the optimization of electroactive, multi-component transition metal oxides used as lithium-ion battery cathode materials. These transition metal oxide particles are often synthesized using precursors produced via coprecipitation reactions, in part due to the advantages provided by coprecipitation including scalability and homogeneous mixing of different transition metal ions. Understanding the kinetics of the nucleation and particle growth for each individual transition metal within a multicomponent blend solution is critical for rational and explicit control of particle composition, as well as to dictate the particle morphology. In this study, in-situ particle size distribution was measured during coprecipitation reactions using focused beam reflection. The transition metal concentrations were also in-situ tracked during the process which, in combination with the particle size information, provided detailed information on the reaction rate, reaction order, and mechanisms of particle nucleation and growth. This work is the first demonstration of application of such techniques to battery precursor particle synthesis, and provides insights into important observations during the coprecipitation process such as the change in the rate of coprecipitation of different transition metals when reacted in isolation or in a blend with other components. The techniques and analysis demonstrated in this paper could find application across many multicomponent transition metal coprecipitation systems important to various applications, including energy storage materials. [ABSTRACT FROM AUTHOR]

A mathematical model of particle growth taking nonlinear temperature-depended interface kinetics into account was investigated,and the particle interface evolution and morphological stability were analyzed. The asymptotic solution of particle growth and the change rate of interface perturbations were obtained by means of an asymptotic expansion method. The result shows that the interface kinetics undercooling and the particle growth velocity decrease with increasing interface kinetics,and that the nonlinear temperature-depended interface kinetics tends to stabilize particle growth. Compared with the situation of neglecting interfacial kinetics,the nonlinear interfacial kinetics significantly decreases the particle growth velocity.

Nitrogen and Sulfur in non-oriented electrical steel would form precipitates, which would severely affect its magnetic properties. Precipitates in compact strip production (CSP) process non-oriented electrical steel were investigated using a transmission electron microscope (TEM) and scanning electron microscopy (SEM). The precipitation mechanism and influence on grain growth were analyzed experimentally and theoretically. The results showed that the main particles in steel were AlN, TiN, MnS, Cu2S, and fine oxide inclusions. The spherical or quasi-spherical of MnS and Cu2S were more liable to precipitate along grain boundaries. During the soaking process, the amount of MnS precipitated on the grain boundary was much larger than that of Cu2S. AlN and TiN in cubic shape precipitated inside grains or grain boundaries. Precipitates preferentially nucleated at grain boundaries, and TiN, MnS mainly precipitated during soaking. In the subsequent processes after soaking, AlN and Cu2S would precipitate unceasingly with the decrease in the average size. The distribution density, the volume fraction, and the average size of the precipitates in the annealed sheets were 9.08 × 1013/cm3, 0.06%, and 54.3 nm, respectively. Precipitates with the grain size of 30–500 nm hindered the grain growth, the grains with 100–300 nm played a major role in inhibiting the grain growth, and the grains with the grain size of 70–100 nm took the second place.

A two-dimensional single particle finite element model was used to examine the effects of particle fragmental pattern on the average molecular weights, polymerization rate and particle overheating in heterogeneous Ziegler-Natta olefin polymerization. A two-site catalyst kinetic mechanism was employed together with a dynamic two-dimensional molecular species in diffusion-reaction equation. The initial catalyst active sites distribution was assumed to be uniform, while the monomer diffusion coefficient was considered to be different inside the fragments and cracks. In other words, the cracks were distinguished from fragments with higher monomer diffusion coefficient. To model the particle temperature a lumped heat transfer model was used. The fragmentation pattern was considered to remain unchanged during the polymerization. A Galerkin finite element method was used to solve the resulting two-dimensional (2-D) moving boundary value, diffusion-reaction problem. A two-dimensional polymeric flow model (PFM) was implemented on the finite element meshes. The simulation results showed that the fragmentation pattern had effects on the molecular properties, reaction rate and the particle temperature at early stages of polymerization.