Changes In Size Distribution Research Articles

Analysis of transient characteristics of droplets in the DFFB regime during single-rod channel reflood experiment

This study aims to explore the dynamic distribution and hydrodynamic characteristics of droplets during the highly transient process of reflood. However, the quasi-steady state analysis is generally adopted in existing studies reported in the literature, ignoring the dependence of droplet formation and breaking mechanism in the Dispersed flow film boiling (DFFB) mechanism on the time-related historical behaviors such as the propagation of the quench front. A series of reflood cooling visualization experiments of zirconium alloy high-temperature rod-shaped heating surface were carried out to achieve this research goal. The wall surface and fluid temperature history curves were recorded, and the parameters, such as the size and velocity of DFFB regime droplets, were quantitatively extracted by visual image processing technology. Based on the formation and breakup mechanism of droplets in the dispersed flow, the reasons for droplet size distribution and velocity change with input heat flux, initial wall temperature, inlet subcooling, and inlet flow rate are well analyzed and explained. At the same time, the experimental results also show a strong correlation between droplet behavior and the reflood process in time. This study can provide more detailed physical support for the subsequent development of droplet behavior models more suitable for the strong transient reflood process and the evaluation of existing models.

The technical approach of using mobile positioning data to support urban population size monitoring

This paper summarizes the methods and approaches of using mobile positioning data to estimate and monitor urban population size. It starts with the necessity of using big data to monitor urban population size in territorial spatial planning. Then it elaborates on the difference between the definition of "population size" reflected by mobile positioning data and the common concept of urban population size, and the necessity of verifying the logic and measurement of sample expansion at four levels. Finally, taking Wuhan city as a case, this paper proposes the technical approach of monitoring the size of urban permanent population through multi-source data verification. The study finds that when it comes to monitoring urban population size, mobile positioning data have the advantage of monitoring short-period changes in population size and spatial distribution, yet special attention must be paid to the three technical links of definition, sample expansion and verification.

The changes in microstructural features and physical properties of ceramic matrix composite bonding tools under ultrasonic service

Tape automated bonding (TAB) process plays a key role in the production of disk drives, microchips and other microelectronics components. Such tools should sustain their structures and properties throughout ultrasonic operation and are expected to last until reaching the targeted numbers of TAB cycles. This project aims to evaluate the changes in microstructures and physical properties of the bonding tools under ultrasonic service. Three commercial waffle-type tools from different suppliers were focused, namely Tool A, Tool B and Tool C. They provide different levels of bonding efficiency up to 50k cycles under relatively similar ultrasonic practice. Non-destructive and destructive testing methods were examined by the means of X-Ray and mass spectroscopy techniques, respectively. The waffle-end tips of the selected tool were observed using a confocal microscope. The changes in grain size and grain size distribution before and after ultrasonic service were quantitatively analyzed via electron micrographs. Also, their bulk density, hardness and toughness were determined. The experimental work revealed the variation in microstructural features and properties among the three, leading to the difference in ultrasonic efficiency, even they all contained similar phase composition. The relationship between microstructures, properties and ultrasonic efficiency was also reported and discussed.

Kinetic control of liposome size by direct lipid transfer

Spontaneous lipid vesiculation and related size distribution are traditionally studied in the framework of equilibrium thermodynamics and continuum mechanics, overlooking the kinetic aspects of the process. In the scenario of liposomes consisting of different lipid molecules dispersed in the same medium - a non-equilibrium situation -, the system evolves driven by lipid monomer transfer among the different liposomes. This process encompasses time-dependent changes in liposome size and size distribution, thus predicting size and composition at a given time would entail the control of the size of liposomes by kinetic means, an asset in the framework of diagnostics and synthetic biology. We introduce a direct transfer model, based on the fact that monomers are highly reactive species and apply it to saturated phospholipid molecules differing in hydrophobic chain length. Considering a well-defined gamma-type liposome size distribution, we demonstrate a clear liposome size-composition correlation and are able to predict liposome size and size distribution at any time in the transfer process. The size-composition correlation opens up new prospects for the control of the self-assembling properties of lipids and thereby the control of the liposome size.

Impact of Polymer Chain Rearrangements in the PA Structure of RO Membranes on Water Permeability and N-Nitrosamine Rejection.

The use of solvents is overall recognized as an efficient method to improve the water permeability of polyamide thin film composite membranes (PA-TFC). The objective of this work was to test the performance of the membranes after exposing them to n-propanol (n-PrOH) to improve the permeability of the membranes while maintaining the rejection factor for small uncharged organic molecules, namely N-nitrosamines (NTRs). After the membranes were exposed to n-PrOH, the water permeability of the UTC73AC membrane increased by 98%, with minimal change in rejection. N-nitrosodiethylamine (NDEA) rejection decreased (3.4%), while N-nitrosodi-n-propylamine (NDPA) and N-nitrosodi-n-butylamine (NDBA) rejection increased by 0.9% and 2.8%, respectively. In contrast, for the BW30LE membrane, water permeability decreased (by 38.7%), while rejection factors increased by 14.5% for NDEA, 6.2% for NDPA, and 15.0% for NDBA. In addition, the morphology of the membrane surface before and after exposure to n-PrOH was analyzed. This result and the pore size distribution (PSD) curves obtained indicate that the rearrangement of polymer chains affects the network or aggregate pores in the PA layer, implying that a change in pore size or a change in pore size distribution could improve the permeability of water molecules, while the rejection factor for NTRs is not significantly affected.

Deagglomeration of Asphalt Binder Using Kraft Lignin: A Sustainable Valorization of Waste from the Pulping Industry

This study assessed the potential of lignin, derived from black liquor, for deagglomerating asphaltene fractions. Chemical and rheological tests were employed to evaluate the efficacy of the lignin additives. Gas chromatography-mass spectrometry (GC–MS) analyzed the chemical components of lignin (L1) isolated with sulfuric acid and lignin (L2) isolated with hydrochloric acid. Gel permeation chromatography (GPC) examined changes in molecular size distribution and deagglomeration effectiveness of the lignin additives. Fourier transform infrared spectroscopy (FTIR) assessed the chemical functional groups of asphalt, while the rheological performance of asphalt was evaluated through the crossover modulus (|G*c|) and frequency (ωc) analysis. L1, possessing high phenolic content and low pH, demonstrated deagglomeration effectiveness, achieving a 6% reduction in weight-average molecular weight, 3% in polydispersity index (PDI), and 16% in asphaltene fraction. Both L1 and L2 decreased the combination aging index of aged asphalt by 28% and 7%, respectively. Moreover, L1 and L2 enhanced the |G*c| of virgin and aged asphalt, consistent with the reduction in the PDI value. These findings suggest that lignin additives possess the potential to deagglomerate asphaltene fractions. The study highlights the potential of repurposing harmful substances from black liquor, traditionally incinerated to reclaim certain chemicals in pulp mills, for use in the pavement industry, promoting sustainability and resource conservation.

Studies on the Functional Properties of Titanium Dioxide Nanoparticles Distributed in Silyl-Alkyl Bridged Polyaniline-Based Nanofluids.

In the present work, a new kind of nanocomposite (NC)-based solid component was prepared for formulating nanofluids (NFs). The NC comprised metal oxide (titanium dioxide, TiO2) dispersed in a conducting polymer with polyaniline (PANI) and chemically linked silyl-alkyl units in it (PSA) that were designated as T-PSA NC. The NFs with ethylene glycol (EG) as a base fluid were prepared with T-PSA NCs with various compositions of TiO2 and PSA as well for various concentrations of T-PSA NCs. The scanning electron microscopic evaluation of the NC revealed that PSA deposition on TiO2 nanoparticles (NPs) decreased particle agglomeration. The PSA coating on the TiO2 NPs did not influence the crystalline structure of the TiO2 NPs, according to the X-ray diffraction patterns. The thermophysical characterization and molecular interaction features of the NFs at 303 K including a novel inorganic-organic T-PSA NC, were detailed. Furthermore, the stability of the T-PSA NC-based NFs was investigated experimentally using the zeta potential, and the particle size distribution change was analyzed using the dynamic light scattering (DLS) method. The T-PSA NCs had particle sizes that were significantly bigger than pristine PSA and pure TiO2. Most of the preparation conditions used to produce the T-PSA NCs resulted in moderately stable suspensions in EG. The results revealed that the ultrasonic velocity increased with the increase in the concentration of T-PSA NC mass % in the NFs, the refractive index and thermal conductivity increased with the increase in the concentration, and the surface tension exhibited a linear change when the ratio of mass % concentration of the T-PSA NCs increased. The combined presence of components that synergistically contribute to the electro, thermal, optical, and rheological properties is expected to attract advanced applications for NFs.

Three-dimensional angular scattering simulations inform analysis of scattering from single cells.

Organelle sizes, which are indicative of cellular status, have implications for drug development and immunology research. At the single cell level, such information could be used to study the heterogeneity of cell response to drugs or pathogens. Angularly resolved elastic light scattering is known to be sensitive to changes in organelle size distribution. We developed a Mie theory-based simulation of angular scattering from single cells to quantify the effects of noise on scattering and size estimates. We simulated randomly sampled organelle sizes (drawn from a log normal distribution), interference between different organelles' scattering, and detector noise. We quantified each noise source's effect upon the estimated mean and standard deviation of organelle size distributions. The results demonstrate that signal-to-noise ratio in the angular scattering increased with the number of scatterers, cell area, and exposure time and decreased with the size distribution width. The error in estimating the mean of the size distributions remained below 5% for nearly all experimental parameters tested, but the widest size distribution tested (standard deviation of 600nm) reached 20%. The simulator revealed that sparse sampling of a broad size distribution can dominate the mismatch between actual and predicted size parameters. Alternative estimation strategies could reduce the discrepancy.

SaTransformer: Semantic‐aware transformer for breast cancer classification and segmentation

AbstractBreast cancer classification and segmentation play an important role in identifying and detecting benign and malignant breast lesions. However, segmentation and classification still face many challenges: 1) The characteristics of cancer itself, such as fuzzy edges, complex backgrounds, and significant changes in size, shape, and intensity distribution make accurate segment and classification challenges. 2) Existing methods ignore the potential relationship between classification and segmentation tasks, due to the classification and segmentation being treated as two separate tasks. To overcome these challenges, in this paper, a novel Semantic‐aware transformer (SaTransformer) for breast cancer classification and segmentation is proposed. Specifically, the SaTransformer enables doing the two takes simultaneously through one unified framework. Unlike existing well‐known methods, the segmentation and classification information are semantically interactive, reinforcing each other during feature representation learning and improving the ability of feature representation learning while consuming less memory and computational complexity. The SaTransformer is validated on two publicly available breast cancer datasets – BUSI and UDIAT. Experimental results and quantitative evaluations (accuracy: 97.97%, precision: 98.20%, DSC: 86.34%) demonstrate that the SaTransformer outperforms other state‐of‐the‐art methods.

Thixotropy of superplasticized cement pastes – Underlying mechanisms considering the polycarboxylate molecular structure, interparticle interactions and hydration kinetics

This paper deals with the decisive mechanisms of thixotropic structural build-up in superplasticized cement-based suspensions related to the PCE molecular structure. We investigate the effect of the side chain length and anionic charge ratio of tailored PCE superplasticizers on thixotropic structural build-up under quantitative consideration of colloidal and contact interactions as well as very early hydration kinetics. The thixotropic structural build-up of superplasticized cement pastes with systematically varying the PCE molecular structure was investigated at constant workability, i.e. dynamic yield stress, by adjusting the individual PCE dosage. Thixotropy was quantified using plate-plate rheometry, while at the same time superplasticizer adsorption, specific surface area, granulometric measurements and quantitative XRD analysis provided an experimental basis for the identification of the respective contribution to the structural build-up.Our results show that the thixotropic structural build-up increases with decreasing PCE side chain length and increasing anionic charge ratio. This is due to accelerated very early hydration kinetics, causing an increase in the specific surface area. The latter is primarily attributed to ettringite, modifying the particle size distribution of the hydrated cement paste. Our approach of separating the colloidal and contact interactions indicates that the PCE-induced change in particle size distribution due to accelerated ettringite formation as well as the change in the average effective layer thickness are the dominant mechanisms for the thixotropic structural build-up in this context.

Critical transition of thermal rectification on complex networks

Thermal rectification is a mechanism that controls the direction of heat conduction, allowing it to flow freely in one direction and hindering it in the opposite direction. In this study, we propose a heat conduction model on a complex network where the node masses are non-uniformly distributed according to mi∼kiα. Our findings show that the existence of a critical point, α=1, determines the working mode of thermal rectification. For α>1, the working mode of thermal rectification is positive, whereas for α<1, the working mode is negative. Additionally, we discovered that this critical transition is a general phenomenon and does not vary with changes in network size, average degree, or degree distribution. By conducting theoretical analyses based on phonon spectra, we also identified the physical mechanism of the critical transition. These results provide a new approach to implement and enrich thermal diodes, opening up new possibilities for more efficient thermal management.

Significant changes in size distribution of aerosols in Beijing after clean air actions

Over the past few years, the physicochemical characteristics and sources of aerosols have changed following the implementation of strict clean air policies in Beijing. In this study, size-segregated particulate matters (PM) were collected using a micro-orifice uniform deposit impactor (MOUDI) in Beijing from July 2021 to June 2022 to understand the responses of particle size distribution and chemical composition to the implemented emission reduction measures. The results showed that although particulate pollution greatly improved, it is still severe in Beijing, especially in autumn and winter, with the annual average PM1.8 (aerosol particle with aerodynamic diameter less than 1.8 μm) concentration reaching 46.7 ± 37.4 μg/m3. NO3− was the most abundant ion in the particles throughout all seasons, and its proportion to water-soluble inorganic ions increased significantly with the aggravation of pollution. This highlights the importance and urgency of controlling mobile sources in future control measures. The highest concentration of SO42− occurring during summer demonstrates the effectiveness of fossil fuel combustion control in winter. The measured size distributions of PM and secondary inorganic ions were trimodal, which significantly differed from the observations conducted in Beijing using MOUDI before 2017, in which the measured size distributions of PM and secondary inorganic ions were bimodal. The enhancement of atmospheric oxidation and reduction of gaseous precursors can affect the formation path of aerosols, and thus, their particle size distribution. Aerosol aqueous-phase reactions play a vital role in pollution development, with the droplet mode further growing hygroscopically into a coarse mode during pollution maintenance.

The role of abrasion in cyclically sheared soil–structure interfaces

A limiting factor in the drive to deliver performance-based design is the lack of knowledge regarding the constitutive behaviour of soil–structure interfaces, particularly in the case of cyclic loading. A series of experiments was undertaken using both a traditional interface shear apparatus (shearing a large body of soil grains over a structural interface) and a novel single-particle interface shear apparatus (involving shearing a single grain over a structural interface). In both cases the soil was sheared across the interface in a cyclical manner (more than 1500 cycles per test). For the traditional apparatus, a clear change in soil particle size distribution and abrasive wear of the structural interface occurs after many cycles. This change results in a significant increase of the interface friction ratio, which is the main parameter used in traditional design – increasing from approximately 0·2 (11°) to 0·7 (35°). The single-particle apparatus validated the results – where a significant increase in the friction ratio after many cycles was also observed. The novel interface behaviour presented in this paper may lead to improved interface constitutive models and consequently more economic and safer geotechnical designs.

Effect of Aging on Physicochemical Properties and Size Distribution of PET Microplastic: Influence on Adsorption of Diclofenac and Toxicity Assessment.

Microplastics (MPs) are detected in the water, sediments, as well as biota, mainly as a consequence of the degradation of plastic products/waste under environmental conditions. Due to their potentially harmful effects on ecosystems and organisms, MPs are regarded as emerging pollutants. The highly problematic aspect of MPs is their interaction with organic and inorganic pollutants; MPs can act as vectors for their further transport in the environment. The objective of this study was to investigate the effects of ageing on the changes in physicochemical properties and size distribution of polyethylene terephthalate (PET), as well as to investigate the adsorption capacity of pristine and aged PET MPs, using pharmaceutical diclofenac (DCF) as a model organic pollutant. An ecotoxicity assessment of such samples was performed. Characterization of the PET samples (bottles and films) was carried out to detect the thermooxidative aging effects. The influence of the temperature and MP dosage on the extent of adsorption of DCF was elucidated by employing an empirical modeling approach using the response surface methodology (RSM). Aquatic toxicity was investigated by examining the green microalgae Pseudokirchneriella subcapitata. It was found that the thermooxidative ageing process resulted in mild surface changes in PET MPs, which were reflected in changes in hydrophobicity, the amount of amorphous phase, and the particle size distribution. The fractions of the particle size distribution in the range 100-500 μm for aged PET are higher due to the increase in amorphous phase. The proposed mechanisms of interactions between DCF and PET MPs are hydrophobic and π-π interactions as well as hydrogen bonding. RSM revealed that the adsorption favors low temperatures and low dosages of MP. The combination of MPs and DCF exhibited higher toxicity than the individual components.

Changes in Physicochemical Properties of Organic Aerosol During Photochemical Aging of Cooking and Burning Emissions

AbstractPhotochemical aging is a key atmospheric processing, yet the changes in physicochemical properties of organic aerosol (OA) during photochemical aging of primary emissions from cooking and burning are less understood. Here we conducted 12 burning (straw, wood, and coal) and cooking experiments to characterize the evolution of size distributions, volatility, and glass transition temperature (Tg) from fresh smoke to aged OA with an equivalent photochemical age of ∼1.5 days using an oxidation flow reactor‐thermodenuder‐aerosol mass spectrometer system. The mass spectra of OA showed significant changes during photochemical aging, for example, the rapid degradation of m/z 60 for straw and wood burning OA, and the large increase in f44 (fraction of m/z 44 in OA) for all OA. The contributions of non‐volatile compounds to the total OA in aged burning OA (1.6%–5.3%) decreased considerably compared with those in fresh burning smoke (2.3%–17.1%), suggesting that photochemical aging of primary emissions for ∼1.5 days produced more volatile secondary OA (SOA). Consistently, the pronounced formation of SOA below 150 nm was observed, and it showed more volatile properties than aged large particles. The Tg of OA under dry conditions (Tg,org) was estimated based on volatility distributions, and the results showed increased Tg,org during photochemical aging of biomass burning and coal combustion emissions, while decreased Tg,org for aged cooking OA. Overall, our results illustrate the different changes in size distributions, volatility, and Tg,org through photochemical aging of different primary emissions, which in turn affect their impacts on radiative forcing and human health.

Impact of Silicon Content and Particle Size in Lithium-Ion Battery Anodes on Particulate Properties and Electrochemical Performance

Silicon (Si) is considered a promising anode active material to enhance energy density of lithium-ion batteries. Many studies have focused on new structures and the electrochemical performance, but only a few investigated the particulate properties in detail. Therefore, a comprehensive study on the impact of Si content (5, 10, 15 wt.%) and particle size (120, 160, 250 nm) of core–shell structured Si@Gr composites on particulate and electrode properties was conducted. It was shown that both parameters had significant impact on the specific surface area (SSA) of particles, which was later correlated to the initial capacities and coulombic efficiencies (ICEs). Furthermore, changes in pore size distribution and electrical conductivity were found. The built full cells showed high initial capacities (>150 mAh g−1), good rate capability (75% at 1 C, 50% at 2 C) and ICEs (>80%). The energy density was found to increase by 32% at 15 wt.% Si compared to graphite (Gr), indicating the future potential of Si. In addition, the impact of a carbon coating was investigated (Si@Gr/C), which led to a reduction in SSA, improved particle stability and higher capacity retention. Consequently, this study emphasizes the importance of also investigating the particulate properties of Si anodes.

Kinetics of nanoparticle nucleation, growth, coalescence and aggregation: A theoretical study of (Ag)n nanoparticle formation based on population balance modulated by ligand binding

Understanding the mechanism of nanocluster formation during their synthesis is important in determining the different variables that govern their formation, size distributions, and stability. Here, we use the method of moments to solve the rate equations for the kinetics of metal cluster formation starting from a well-mixed solution of metal ions and reducing agents. With the incorporation of coalescence, we detected a drastic change in size distribution with a small change of a parameter – the initial ion concentration or the coalescence rate coefficient. This is a manifestation of a threshold beyond which the number of possible combinations for aggregation of clusters increases abruptly during coalescence. We observe the sensitivity of nanocluster size distribution to the coalescent growth rate and the effect of a strong ligand stabilizer in impeding coalescence.

The formation of high CO2 loading solid phase from 1,4-butanediamine/ethylene glycol biphasic solvent: Phase-changing behavior and mechanism

Liquid-solid phase change absorption has been considered a promising strategy for CO2 capture. To achieve efficient and economic CO2 capture in industrial-scale applications, it is essential to understand the phase-change behaviors and mechanisms of the biphasic system. In this study, a blend of 1, 4-Butanediamine (BDA) and ethylene glycol (EG) was developed as a biphasic solvent that can form a high CO2 loading solid phase product (BESP) after absorption. The total solvent loading reached 0.9039 mol·mol−1, with 90.74% of the loading enriched in the solid phase, which only accounts for 51.01% of the total solvent mass. Based on the 13C NMR analysis and quantum chemical calculations, the reaction and phase change mechanism of CO2 capture was proposed. The BDA/EG system absorbs CO2 to generate carbamate species, protonated amines and alkyl-carbonates, which combine each other through hydrogen bonding or electrostatic attraction. The self-aggregation of zwitterions and the high polarity of the absorption products are considered to be the main reasons for the phase change. Alkyl-carbonate species are believed to co-precipitate through organic gelation via van der Waals force with the carbamate or protonated amine. Moreover, the viscosity, turbidity, solid-phase mass, and particle size distribution changes also demonstrate the growth and aggregation of particles during absorption. BESP, identified as a coupling product of carbamate and alkyl-carbonate ([2BDAH+COO-]·[EG‐OCO2-]), decomposes at a peak temperature of 127.4 °C. The calorimetric method determined regeneration heat to be approximately 3.17 GJ·ton-1 CO2, indicating its potential for alternative uses rather than direct heat regeneration. Such a biphasic solvent may provide unique solutions for industries to reduce CO2 emissions.

The impact of material chemistry and morphology on attrition behavior of excipients during high shear blending

Particle breakage by attrition is unavoidable in some unit operations and can lead to uncontrolled behavior of materials during processing. The aim of this study is to clarify the impact of material properties on attrition behavior. For the first time, an integral study with varying morphologies and chemistries is performed to identify the key drivers that impact attrition during high shear blending. Based upon the observed changes in particle size distribution, it was concluded that dicalcium phosphate (DCP) was the most prone to attrition, followed by mannitol, lactose and microcrystalline cellulose (MCC). Granular particles were more sensitive to attrition than sieved and spherical particles. Changes in bulk density, flow function coefficient and tablet tensile strength were observed as the result of attrition. The magnitude and direction of change in these parameters was not only dependent on the amount of attrition, but also on the morphology and the material deformation properties.

Cooperative interaction of a highly hydrophilic pluronic with bile salts of different hydrophobicity

In this study, we investigated the association of bile salts with pluronic F127 (F127) as a function of their hydrophobicity. Sodium cholate (NaC), sodium deoxycholate (NaDC) and sodium taurodeoxycholate (NaTDC) were used as bile salt. Our interpretations are based on the observations of isothermal titration calorimetry (ITC), high sensitivity differential scanning calorimetry (HSDSC), dynamic light scattering (DLS) and small angle neutron scattering (SANS) experiments. Bile salts affected the aggregation of F127 in accordance to their hydrophobicity, i.e. NaC<NaDC<NaTDC. Thermodynamically stable mixed aggregates were formed with NaC which remained confined at the interface even at high concentration (∼10 mM). On the contrary, hydrophobic NaTDC engaged more profoundly with F127 which manifested into dissociation of aggregates. With 4 mM NaTDC, the number density of aggregates increased more than ten-fold. We argue that dissociation would have occurred because of development of electrostatic repulsive forces in the presence of NaTDC molecules. This could be verified from bile salt driven changes in size distribution, aggregation number and thermodynamic parameters. For instance, upshift in critical micelle concentration and micellization temperature of F127 was recorded depending upon concentration of NaDC and NaTDC. Inspite of this, neutron scattering data ruled out the possibility of morphological transitions during these associations.