Particle Concentration Research Articles

Using Local Concentration to Model the Progress of Acoustophoretic Assembly of Microspheres in Planar Standing Waves

Abstract Acoustophoretic assembly uses a standing acoustic field to move dispersed small particles into a geometric pattern. The technique relies on the acoustic radiation force, which arises from the interaction between the acoustic field and the particles, and drives the particles towards areas of low acoustophoretic potential. Acoustophoretic assembly shows potential for a wide range of applications, including organizing filler materials in composites, creating metamaterials, and fabricating functional biological tissue. However, the method has not yet been incorporated into large-scale manufacturing processes. One barrier is the incomplete understanding of the assembly process. While an ideal final pattern geometry can be calculated from the acoustic field and the material properties, there are currently no widespread metrics for measuring the progress of the pattern formation. As a result, it is difficult to know how long the acoustic field should be applied during manufacturing. Our approach uses the local particle concentration to model the acoustophoretic assembly process. We show that an expression for the time-dependent local particle concentration can be derived from the force balance on the particles and a control volume analysis. The analysis is applied to microspheres in a planar acoustic standing wave, and an analytical expression is obtained, , which yields a time parameter for pattern assembly and suggests a cut-off time. We then use the local concentration to define measurements for the quality of the assembled microsphere pattern. Experiments were carried out using polystyrene microspheres in a glycerol-water mixture to validate the theoretical results.

Effects of Polyethylene Microplastics in Agricultural Soil on Eisenia fetida (Annelida: Oligochaeta) Behavior, Biomass, and Mortality

The presence of microplastic particles in agroecosystems has profound implications for soil quality, crop yield, and soil biota. Earthworms are widely recognized as valuable soil bioindicators due to their abundance, fast reproduction, and easy manipulation. The aim of this study was to observe Eisenia fetida avoidance behavior and changes in biomass and mortality rate in soil samples spiked with polyethylene microplastic particles. Three types of soil sampled from the agricultural fields (“Banat 1”, “Banat 2”, and “Bačka”) were tested, as well as three microplastic concentrations (0.1, 0.2, and 0.3%). The calculated avoidance percentages ranged from 18.67% for “Banat 1” and 23.70% for “Banat 2” to 27.40% in the case of “Bačka” soil samples. Generally, E. fetida specimens avoided the sections with plastic in all bioassays: 38.42% of the earthworms were in the chamber section that contained microplastics, as opposed to 61.58% in the control section. The changes in the earthworms’ post-test biomasses were directly proportional to the number of surviving earthworms, with the highest loss in “Bačka” soil samples with 0.3% MPs (−53.05%). The highest mortality rate (46%) was noted in “Bačka” soil samples spiked with the highest concentration of microplastic particles.

Monitoring of Microplastics in Water and Sediment Samples of Lakes and Rivers of the Akmola Region (Kazakhstan)

This paper provides a detailed description of the findings and methodology related to the monitoring of microplastics in three lakes and one river of the Akmola Region in Kazakhstan. The concentration of microplastic particles and the analysis of water and sediment quality of the Yesil River and Kopa, Zerendinskoye, and Borovoe lakes have been analyzed. A total of 64 water samples were collected across the spring, summer, and autumn seasons, with subsequent analysis revealing a seasonal increase in microplastic concentrations. The average microplastic content ranged from 1.2 × 10−1 particles/dm3 in spring to 4.5 × 10−1 particles/dm3 in autumn. Lakes exhibited higher concentrations compared to the Yesil River. Correlation analysis highlighted a connection between microplastic content and turbidity, particularly notable during the spring season. Analysis of sediments revealed a decrease in microplastic concentrations from the coastal zone toward open waters sediments. Microplastic fibers were predominant in sediments (69.6%), followed by fragments (19.1%), films (7.4%), and granules (3.9%). Larger particles (>500 µm) were found in beach sediments, constituting an average of 40.5% of the total plastics found. This study contributes valuable insights into the spatial and temporal distribution of microplastics, emphasizing the need for ongoing monitoring and management strategies to address this environmental concern.

Synthesis of Reusable CNF/Ag2Se Films as Visible-Light-Driven Photocatalysts for Photocatalytic Degradation of MB

AbstractIn our study’s scenario, flexible films were fabricated from TEMPO-oxidized cellulose nanofibers and silver selenide (CNF/Ag2Se) as efficient membranes for the degradation of methylene blue (MB). Different concentrations of Ag2Se particles were in situ prepared in the presence of CNF. The in-situ synthesis of Ag2Se nanoparticles in the presence of CNF was reported as efficient technique for the formation of submicrosize Ag2Se particles with a narrow size distribution and homogeneous dispersion onto CNF. TEM analysis revealed that the nanofibers had uniform width and diameter, while XRD demonstrated single-phase orthorhombic β-Ag2Se formation. 3D-FESEM showed tiny root measurer values of 28, 30, and 32.56 nm in polymeric films with 2.5, 5, and 10% Ag2Se-filled CNF. Polymeric films had visible-driven-light photocatalytic activity because the band gap fell from 4.61 eV (UV area) to 2.71 eV (visible region). The composite’s photocatalytic performance was assessed by MB degradation. 10% of CNF/Ag2Se demonstrated maximal photocatalytic activity under simulated sunlight for 60 min, pH 9, and 3 g/L composite weight. The factorial design statistical analysis showed that MB dye photodegradation is mostly affected by irradiation time and dye concentration. Environmental, social, and economic factors are all considered, making this study suitable for implementing photocatalysis to large-scale water treatment systems, which is a key component of sustainability.

ПЛАНИРОВАНИЕ И РЕАЛИЗАЦИЯ СТРОИТЕЛЬНЫХ РАБОТ ПРИ ТОЧЕЧНОЙ ЗАСТРОЙКЕ ДЛЯ ОПРЕДЕЛЕНИЯ УДЕЛЬНЫХ ПЫЛЕВЫХ ВЫБРОСОВ

Abstract. The construction industry is one of the significant sources of environmental damage. The effects of dust pollution have an impact on all stages of the building's life cycle, from the start of work on the construction site to completion, operation and demolition. Despite the fact that the stage of work implementation does not last long in comparison with other stages of the life cycle of an investment and construction project, the construction stage has a number of significant impacts on the environment. The development of the construction industry requires the comprehensive assessment and investigation of the construction site as a source of pollu-tion, identification and evaluation of all sources of dust pollution on the construction site, the processes of dust pollution propagation in an urban environment. 
 The article offers an analysis of data on field studies of the degree of atmospheric air pollution in the territory of Rostov-on-Don, an analysis of the volume of construction dust emissions from construction works, a method for calculating control over the implementation of construction processes and the spread of dust pollution generated in the atmospheric air, indi-cators of the maximum, average daily emission concentration of fine dust PM2.5 and PM10 formed from construction production and the ability to control the level of pollution on the construction site. There are no fundamental studies on the calculation of dust emission from construction works during spot construction. Based on the field studies conducted earlier using the Handheld 3016 particle counter, data on dust emissions from construction processes under various climatic influences were obtained.
 Subject: analysis of data on field studies of the degree of atmospheric air dustiness in the territory of Rostov-on-Don, the volume of emissions of construction dust from construction work on construction sites in urban conditions.
 Materials and methods: conducting systematic measurements of the degree of dust in Rostov-on-Don using the Lighthouse Handheld 3016 IAQ manual particle counter, taking into account typical climatic, heterogeneous factors of the territory on which the city is located. Systematic monitoring of several construction sites where residential complexes similar in technology and conditions were built in the most dusty area of Rostov-on-Don and the selection of five construction sites for the development of a calendar schedule for construction and installation work, taking into account specific emissions of dust particles and climatic conditions for calculating the dust pollution factor.
 Results: an effective approach that can be usefully applied to the determination of dust emissions on the construction site, to calculate the gross emission of dust released on the site from construction work, daily indicators of the maximum single and average daily concentration, as well as to dust dispersion with the determination of zones exceeding the MPC indicators is the use of network modeling with further calendarization to predict these types of indicators during the design and implementation of construction production.
 Conclusions: based on the data obtained, it can be concluded that with the existing implemented organization and technology of work, the concentration of fine dust particles are within the MPC, but given the background concentrations of atmospheric air in Rostov-on-Don, these indicators in a particular area will exceed the permissible MPC. The process of using existing SMR models taking into account specific dust emissions, the development of a schedule of dust pollution of a specific territory taking into account natural and climatic factors and the determination of zones of excess of MPC indicators in the process of modeling the dispersion of fine dust particles beyond the fence boundaries of the construction site will make it possible to draw up a passport of environmental safety of the nearby urbanized territory during spot development. Daily determination of dust pollution indicators will allow you to adjust the schedule of construction work. Modeling the dispersion of construction dust, taking into account the direction and speed of the wind, will make it possible to monitor the zones of exceeding the MPC of the neighboring territory on a daily basis and adjust measures to extinguish dust emissions at the construction site.

Evaluation of the spatial distribution of aerosols produced by various respiratory activities

This study investigated the dispersion and evaporation characteristics of droplets and droplet nuclei emitted during human respiratory activities. A specially designed wind tunnel was filled with purified air, wherein selected subjects performed various respiratory activities with their heads positioned inside. An optical particle sizer was used to collect particles with sizes of 0.3–10 μm at 63 points in front of the mouth. The dilution factors were analyzed to investigate the impact of combining the exhaled airflow with ambient air on droplet evaporation. At a distance of 0.01 m from the mouth opening, the volume concentration of the particles was the highest during breathing, followed by coughing and speaking. The volumetric concentration of particles decreased with an increase in the distance from the inlet for all activities. The spatial volume concentration distribution of particles showed that coughing tended to disperse the particles in the forward direction, whereas speaking tended to disperse them laterally. Utilizing these findings in CFD analysis can provide in-depth insights into dispersion and evaporation dynamics. This can contribute significantly to the development of preventive measures through the implementation of proactive HVAC systems to effectively remove infectious particles and control the spread of infectious diseases. Future studies should explore a wider range of particle sizes and advanced sampling techniques for a clear understanding of respiratory particle dynamics and infection control strategies.

Piezoresistive response of geopolymer pastes activated by silica fume-derived alkaline solution

This study examined the self-sensing performance of metakaolin-based geopolymer paste samples activated by an alkali activator, which is a solution mixture of potassium hydroxide and silica fume (SF). Their piezoresistive response under repeated compressive loads was found to improve with increasing SF content. It was found from their XRD, SEM, and FTIR results that the change in the SF content did not alter the phase composition of the geopolymer matrices. The factorial change in the electrical resistivity of geopolymer samples with a maximum SF content was calculated to be about 0.024. Their pore solutions were detected to be mainly filled with potassium and silicon ions due to the use of higher concentrations of SF particles. The UV spectrophotometry measurements of this study confirm that all the geopolymer samples displayed semiconductor behaviour. The SF-derived alkaline activator can enable the self-sensing character of geopolymer-based concrete, which isenvironmentally friendly and has recently shown great potential to monitor structural integrity under applied external loads.

Electrophoretic Deposition Interferometric Scattering Mass Photometry.

Interferometric scattering microscopy (iSCAT) has rapidly developed as a quantitative tool for the label-free detection of single macromolecules and nanoparticles. In practice, this measurement records the interferometric scattering signal of individual nanoparticles in solution as they land and stick on a coverslip, exhibiting an intensity that varies linearly with particle volume and an adsorption rate that reflects the solution-phase transport kinetics of the system. Together, such measurements provide a multidimensional gauge of the particle size and concentration in solution over time. However, the landing kinetics of particles in solution also manifest a measurement frequency limitation imposed by the slow long-range mobility of particle diffusion to the measurement interface. Here we introduce an effective means to overcome the inherent diffusion-controlled sampling limitation of spontaneous mass photometry. We term this methodology electrophoretic deposition interferometric scattering microscopy (EPD-iSCAT). This approach uses a coverslip supporting a conductive thin film of indium tin oxide (ITO). Charging this ITO film to a potential of around +1 V electrophoretically draws charged nanoparticles from solution and binds them in the focal plane of the microscope. Regulating this potential offers a direct means of controlling particle deposition. Thus, we find for a 0.1 nM solution of 50 nm polystyrene nanoparticles that the application of +1 V to an EPD-iSCAT coverslip assembly drives an electrophoretic deposition rate constant of 1.7 s-1 μm-2 nM-1. Removal of the potential causes deposition to cease. This user control of EPD-iSCAT affords a means to apply single-molecule mass photometry to monitor long-term changes in solution, owing to slow kinetic processes. In contrast with conventional coverslips chemically derivatized with charged thin films, EPD-iSCAT maintains a deposition rate that varies linearly with the bulk concentration.

Particle characterization in commercial buildings: A cross-sectional study in 40 offices in Singapore

There is a knowledge gap in understanding how existing office buildings are protecting occupants from exposure to particles from both indoor and outdoor sources. We report a cross-sectional study involving weekly measurements of size-resolved indoor and outdoor particle concentrations in forty commercial building offices in Singapore. The outdoor and indoor particles size distributions were single mode with daytime peak number concentrations at 36.5 nm and 48.7 nm. Outdoor concentrations were significantly greater than indoors for all particle diameters. Indoor particle concentrations were generally low due to: 1) relatively high indoor particle removal (IPR) rates; 2) low indoor source strengths; and 3) low indoor particle of outdoor proportion (IPOP). We found that the ventilation system type had a substantial effect on indoor particle levels, IPR and IPOP. Through linear mixed model analyses, we identified dependencies of IPR rates with the use of MERV13 filters in supply air and filter maintenance frequency, IPOP with the use of MERV13 filters in the fresh air and supply air ducts and low particle source strength with regular daily cleaning presumably due to dust reservoir removal. Lastly, the contribution of outdoor sources was mainly seen for ultrafine and fine particles but less pronounced for coarse particles. This study provided detailed understanding of particle exposure in building offices and their influencing factors, facilitating future research on health impact of particle exposures.

Validation of a Eulerian–Lagrangian numerical algorithm for simulating ultra-coarse particles transported in horizontal and vertical hydraulic pipes

Investigation on the characteristics of coarse and ultra-coarse particles transported in hydraulic conveying pipe is essential to design hydraulic conveying system with high efficiency and reliability. However, the modeling of the particles with a finite size larger than the mesh for fluid discretization is intractable, because the unresolved point-particle methods are difficult to converge in the calculation and the particle-resolved methods cannot afford the computational cost for engineering problem. A numerical algorithm based on the Eulerian–Lagrangian framework is developed to simulate such two-phase flows. The solvers of the computational fluid dynamics (CFD) and the discrete element method (DEM) are coupled through an in-house developed interface code. In the code, a diffusion-based averaging method is employed to smooth the contributions of large particle in the particle volume fraction, the interphase forces and the interactions between turbulence and particles. The interpolation of fluid velocity is also improved so that the calculations of the interphase forces are more accurate. The authenticity of the numerical algorithm is validated against available experimental results. The validating scenarios are the millimeter- and centimeter-sized particles conveyed in both horizontal and vertical pipes under various conveying speeds and particle concentrations. The results show the numerical algorithm can simulate large particles in the fine CFD meshes. More importantly, some distinct features in the particle distribution and the characteristics of turbulence in the experiments are well reproduced by the simulations.

Solidified water at room temperature hosting tailored fluidic channels by using highly anisotropic cellulose nanofibrils

Highly anisotropic cellulose nanofibrils can solidify liquid water, creating self-supporting structures by incorporating a tiny number of fibrils. These fibrillar hydrogels can contain as much as 99.99 wt% water. The structure and mechanical properties of fibrillar networks have so far not been completely understood, nor how they solidify the bulk water at such low particle concentrations. In this work, the mechanical properties of cellulose fibrillar hydrogels in the dilute regime from a wt% perspective have been studied, and an elastoplastic model describing the network structure and its mechanics is presented. A significant insight from this work is that the ability of the fibrils to solidify water is very dependent on particle stiffness and the number of contact points it can form in the network structure. The comparison between the experimental results and the theoretical model shows that the fibrillar networks in the dilute regime form via a non-stochastic process since the fibrils have the time and freedom to find contact points during network formation by translational and rotational diffusion. The formed, dilute fibrillar network deforms by sliding fibril contacts upon straining the network beyond its elastic limit. Our results also show that before macroscopic failure, the fibril contacts are restored once the load is released. The exceptional properties of this solidified water are exploited to host fluidic channels, allowing directed fluid transportation in water. Finally, the microfluidic channels formed in the hydrogels are tailored by the layer-by-layer technique to be interactive against external stimuli, a characteristic envisioned to be useful in biomedical applications.

Particle emissions from heated tobacco products.

This study determines the particle emissions from five heated tobacco products (HTPs). An aethalometer is used for the determination of black carbon (BC) and an aerosol monitor for total particulate matter (PM) concentration and also PM fractions (1, 2.5, 4, and 10 μm) in the mainstream emissions of 5 HTPs: IQOS, LIL, PULZE, ILUMA, and GLO. Fifteen different flavors were used, five sticks per flavor, which were smoked using a peristaltic pump under both ISO and Canadian smoking regimes. The method repeatability was determined using 15 sticks of one flavor for each brand for each smoking regime. All HTPs emit particles, and more than 99.7% of the particles emitted are smaller than 1 μm. Both BC and PM emissions show quite low repeatability. Particle emissions increase in relation to the heating temperature and the intensity smoking regime, and are depending on the flavor used. BC corresponds to a small percentage of total PM. Although HTPs are promoted as products of reduced risk compared to conventional cigarettes, high particle concentrations are detected in their emissions, depending on the smoking regime, the flavor used, and the operation parameters. PM emissions vary significantly between different brands under the ISO smoking regime, probably due to the heating temperature. In contrast, PM emissions under the Canadian smoking regime do not vary significantly between different brands. This could probably be attributed to the fact that increased puff frequency does not allow the device to cool down between puffs, resulting in an increase in PM emissions for all the brands, but not dependent on the maximum heating temperature of the device. BC emissions only consist of a very small fraction of PM and do not vary significantly between different brands under both smoking regimes.

Anthropogenic particle concentrations and fluxes in an urban river are temporally variable and impacted by storm events.

Anthropogenic particles (AP), which include microplastics and other synthetic, semisynthetic, and anthropogenically modified materials, are pollutants of concern in aquatic ecosystems worldwide. Rivers are important conduits and retention sites for AP, and time series data on the movement of these particles in lotic ecosystems are needed to assess the role of rivers in the global AP cycle. Much research assessing AP pollution extrapolates stream loads based on single time point measurements, but lotic ecosystems are highly variable over time (e.g., seasonality and storm events). The accuracy of models describing AP dynamics in rivers is constrained by the limited studies that examine how frequent changes in discharge drive particle retention and transport. This study addressed this knowledge gap by using automated, high-resolution sampling to track AP concentrations and fluxes during multiple storm events in an urban river (Milwaukee River) and comparing these measurements to commonly monitored water quality metrics. AP concentrations and fluxes varied significantly across four storm events, highlighting the temporal variability of AP dynamics. When data from the sampling periods were pooled, there were increases in particle concentration and flux during the early phases of the storms, suggesting that floods may flush AP into the river and/or resuspend particles from the benthic zone. AP flux was closely linked to river discharge, suggesting large loads of AP are delivered downstream during storms. Unexpectedly, AP concentrations were not correlated with other simultaneously measured water quality metrics, including total suspended solids, fecal coliforms, chloride, nitrate, and sulfate, indicating that these metrics cannot be used to estimate AP. These data will contribute to more accurate models of particle dynamics in rivers and global plastic export to oceans. PRACTITIONER POINTS: Anthropogenic particle (AP) concentrations and fluxes in an urban river varied across four storm events. AP concentrations and fluxes were the highest during the early phases of the storms. Storms increased AP transport downstream compared with baseflow. AP concentrations did not correlate with other water quality metrics during storms.

Experimental Study on Supersonic Combustion Characteristics of Al/B-Kerosene Nanofuels

Aluminum and boron nanoparticles are added to kerosene in this paper to improve the combustion properties of kerosene. When the particle concentration is 30 g/L, the volumetric heat value of fuel increases by 3 and 5%, respectively, with the addition of aluminum and boron nanoparticles. Meanwhile, combustion experiments in a supersonic combustor are conducted to study the combustion characteristics of Al-kerosene nanofuels and B-kerosene nanofuels. The air flow rates of all experiments are about 1.77 kg/s, the total temperature is 1500 K, and the total pressure is 1.2 MPa. The combustion flow and flame structures of kerosene with different particles and different concentrations are studied, and the results indicate that the addition of nanoparticles to the fuel enhances combustion and heat release enhanced, and the flame stabilization mode is changed from the cavity stabilization to the jet-wake stabilization mode with a higher particle concentration. Meanwhile, the unsteady characteristics of flame are studied. The flame oscillation is intensified, and the fundamental frequency of the flame increases with the increase in particle concentration. Besides, the addition of nanoparticles significantly improves the combustion efficiency of kerosene. When the particle concentration is 30 g/L, the combustion efficiencies of nanofuels are increased by 15% and 17.5%, respectively, with the addition of aluminum and boron nanoparticles.

Measuring the concentrations of some gaseous air pollutants and dust particles in the western city of Hamzah in Iraq

This research concentrates on studying and analyzing the spatial and temporal variation of the concentrations of air pollutants in the Hamzah-western city during the four seasons of the year 2022 by studying the concentrations of gaseous pollutants in the air, such as NO2, SO2, CO, CO2, and O3, as well as measuring the concentrations of dust particles suspended in the air, such as PM2.5 and PM10. The number of sampling sites reached six, distributed into five different sectors (industrial, residential, transport, agricultural, and a mixed sector combining industry and transportation) in order to show the discrepancies in the concentrations of pollutants and explain their causes. The results of in situ measurements and laboratory analyses showed that there is a spatial and temporal variation in the concentrations of air pollutants. The highest concentrations of carbon monoxide CO, carbon dioxide CO2, and sulfur dioxide SO2 were recorded in sector 1 and during the summer season at concentrations of 38.5, 337, and 2.9 ppm, respectively. While the highest concentrations of nitrogen dioxide (NO2) were recorded in sector (2) with a concentration of 0.65 ppm, and all those concentrations were outside the permissible limits, the lowest concentrations were recorded for gases in sector (6), which covered all the study semesters. As for the concentrations of suspended dust particles in their sizes (PM2.5 and PM10), the highest concentrations were recorded in Sector (2), during all seasons of the study, and at 383.81 and 389.38 ppm concentrations, respectively. While the lowest concentrations of suspended particles of both sizes were recorded in Sector 6, a value of 119.65 ppm was recorded for PM2.5 minutes and 115.65 ppm for PM10 minutes. Thus, all their values during the study period were greater than the permissible limits.

Understanding the impact of combined hydrodynamic shear and interfacial dilatational stress, on interface-mediated particle formation for monoclonal antibody formulations

During biomanufacturing, several unit operations expose solutions of biologics to multiple stresses, such as hydrodynamic shear forces due to fluid flow and interfacial dilatational stresses due to mechanical agitation or bubble collapse. When these stresses individually act on proteins adsorbed to interfaces, it results in an increase in protein particles in the bulk solution, a phenomenon referred to as interface-induced protein particle formation. However, an understanding of the dominant cause, when multiple stresses are acting simultaneously or sequentially, on interface-induced protein particle formation is limited. In this work, we established a unique set-up using a peristaltic pump and a Langmuir-Pockels trough to study the impact of hydrodynamic shear stress due to pumping and interfacial dilatational stress, on protein particle formation. Our experimental results together demonstrate that for protein solutions subjected to various combinations of stress (i.e., interfacial and hydrodynamic stress in different sequences), surface pressure values during adsorption and when subjected to compression/dilatational stresses, showed no change, suggesting that the interfacial properties of the protein film are not impacted by pumping. The concentration of protein particles is an order of magnitude higher when interfacial dilatational stress is applied at the air-liquid interface, compared to solutions that are only subjected to pumping. Furthermore, the order in which these stresses are applied, have a significant impact on the concentration of protein particles measured in the bulk solution. Together, these studies conclude that for biologics exposed to multiple stresses throughout bioprocessing and manufacturing, exposure to air-liquid interfacial dilatational stress is the predominant mechanism impacting protein particle formation at the interface and in the bulk solution.

Intelligent responsive self-assembled micro-nanocapsules: Used to delay gel gelation time

In the application of polymer gels to profile control and water shutoff, the gelation time will directly determine whether the gel can “go further” in the formation, but the most of the methods for delaying gel gelation time are complicated or have low responsiveness. There is an urgent need for an effective method for delaying gel gelation time with intelligent response. Inspired by the slow-release effect of drug capsules, this paper uses the self-assembly effect of gas-phase hydrophobic SiO2 in aqueous solution as a capsule to prepare an intelligent responsive self-assembled micro-nanocapsules. The capsule slowly releases the cross-linking agent under the stimulation of external conditions such as temperature and pH value, thus delaying gel gelation time. When the pH value is 2 and the concentration of gas-phase hydrophobic SiO2 particles is 10%, the gelation time of the capsule gel system at 30, 60, 90, and 120 °C is 12.5, 13.2, 15.2, and 21.1 times longer than that of the gel system without containing capsule, respectively. Compared with other methods, the yield stress of the gel without containing capsules was 78 Pa, and the yield stress after the addition of capsules was 322 Pa. The intelligent responsive self-assembled micro-nanocapsules prepared by gas-phase hydrophobic silica nanoparticles can not only delay the gel gelation time, but also increase the gel strength. The slow release of cross-linking agent from capsule provides an effective method for prolongating the gelation time of polymer gels.

Electric-field-assisted fabrication of metal-class thermal-conductive and elastomer-class-flexible composites comprising plasma-surface-modified hexagonal boron nitride and polyrotaxane

There is a growing demand for materials with high thermal conductivity, electrical insulation, flexibility, and toughness for application in flexible electronic devices. To develop materials with the aforementioned properties, composites comprising the flexible and tough polyrotaxane (PR) and highly thermally conductive hexagonal boron nitride particles (hBN) were fabricated in this study. An electric field was applied during the polymerization of the composites to improve their thermal conductivity in the out-of-plane direction of the composites without reducing their flexibility. Electric-field application during polymerization controlled the orientation of hBN in the as-synthesized composites, forming pillar-like structures comprising oriented hBN. The particle diameter and concentration of hBN were optimized to synthesize an electrically insulating composite with elastomer-class flexibility in the in-plane direction (a low Young’s modulus of 77 MPa) and metallic-alloy-class thermal conductivity in the out-of-plane direction (>10 W/mK) with a wide range of potential applications including thermal interface materials in electronic devices.

Investigation on the effect of particle parameters on the erosion and erosion prediction model of the Pelton turbine

The Pelton turbine will play a massive role in China's water conservancy and power generation development process. In practical engineering applications, sediment will erode the components of the Pelton turbine when they come into contact, threatening the safe and stable operation of the unit. Therefore, based on the Eulerian–Lagrangian method, this study analyzes the effects of particle size, concentration, and position angle on the degree and distribution of erosion of each component without considering the cavitation effect of the flow. The results show that the larger the particle size, the more concentrated the distribution, and the more severe the abrasion caused on the spray needle and water bucket. However, the degree of nozzle erosion weakens, and the erosion area increases. It was also found that the higher the concentration, the more severe the abrasion caused to each component. When the jet completely hits the position on the bucket, due to the low impact speed, the impact angle remains almost unchanged, resulting in less erosion. Finally, the classic Finnie model was refined by adjusting the average erosion rate, particle size, concentration, and rotation angle. This modification yielded an enhanced model, mainly showcasing improved performance for moderate particle sizes.

The Nutri-Score nutrition label: Associations between the underlying nutritional profile of foods and lipoprotein particle subclass profiles in adults

Background and aimsLipoprotein particle concentrations and size are associated with increased risk for atherosclerosis and premature cardiovascular disease. Certain dietary behaviours may be cardioprotective and public health strategies are needed to guide consumers’ dietary choices and help prevent diet-related disease. The Food Standards Agency nutrient profiling system (FSAm-NPS) constitutes the basis of the five-colour front-of-pack Nutri-Score labelling system. No study has examined FSAm-NPS index associations with a wide range of lipoprotein particle subclasses. MethodsThis was a cross-sectional study of 2006 middle-to older-aged men and women randomly selected from a large primary care centre. Individual participant FSAm-NPS dietary scores were derived from validated food frequency questionnaires. Lipoprotein particle subclass concentrations and size were determined using nuclear magnetic resonance spectroscopy. Multivariate-adjusted linear regression analyses were performed to examine FSAm-NPS relationships with lipoprotein particle subclasses. ResultsIn fully adjusted models which accounted for multiple testing, higher FSAm-NPS scores, indicating poorer dietary quality, were positively associated with intermediate-density lipoprotein (β = 0.096, p = 0.005) and small high-density lipoprotein (HDL) (β = 0.492, p = 0.006) concentrations, a lipoprotein insulin resistance score (β = 0.063, p = 0.02), reflecting greater lipoprotein-related insulin resistance, and inversely associated with HDL size (β = −0.030, p = 0.045). ConclusionsA higher FSAm-NPS score is associated with a less favourable lipoprotein particle subclass profile in middle-to older-aged adults which may be a potential mechanism underlying reported health benefits of a healthy diet according to Nutri-Score rating.