Increasing Particle Concentration Research Articles

Effects of Protein Content on Pickering‐assisted Interfacial Enzyme Catalysis

AbstractIn recent years, water‐in‐oil Pickering emulsions have been introduced as promising reaction systems for multiphase enzyme catalysis, in particular lipase‐catalyzed esterification and transesterification. Here, we for the first time gained insight into the effects that the presence of the proteins exert on the fineness and stability of the emulsion system and thus, the catalytic performance. We demonstrated a distinct, concentration‐ and enzyme‐dependent decrease of droplet sizes in the dispersed phase, accompanied by decreasing stability against coalescence. This was due to a probably quantitative adsorption of lipases at the interphase intercalating the solid particles. Destabilization was reduced slightly at increased particle content and increased volume portion of the dispersed phase, respectively. However, the low tolerable lipase concentrations in the reaction system considerably limited its productivity. Thus, our study points at the enzyme content, or rather enzyme location, in Pickering emulsions being the crucial parameter for optimizing catalytic performance.

Magnetorheological behavior of isotropic silicone rubber-based magnetorheological elastomers under coupled static–dynamic compressive loads

The primary goal of this work is to test and model the magnetorheological (MR) properties of the isotropic magnetorheological elastomers (MREs) under the coupled static–dynamic compressive loads. Isotropic MREs with different contents of magnetic particles were fabricated based on the silicone elastomer. In order to apply the controllable magnetic field to the MREs and directly measure the viscoelastic force of the deformed MREs during the dynamic tests, an electromagnet with a magnetic flux density of up to 0.9 T was developed and integrated into an electric dynamic test system. The stress–strain hysteresis loops of the produced MREs were experimentally characterized under the dynamic compressive loads coupled with different static pre-strains. Effects of particle content, strain amplitude, static pre-strain and load frequency on the MR properties of the MREs were examined in terms of the characteristics of the hysteresis loops, as well as the MR effects in the storage modulus, loss modulus and pre-stress. The results revealed that irrespective of the applied magnetic field, the deformation behavior of the produced MREs was in an approximate linear viscoelastic state when the strain amplitude was less than 7.5%. Both the absolute and relative MR effects increase with the increasing particle content, and decrease with the increasing strain amplitude. Only the absolute MR effect increases with the increasing pre-strain. While varying the load frequency has almost no effect on the MR effect of the MREs. Furthermore, two empirical models were proposed respectively for predicting the storage modulus and loss modulus of the MREs as functions of the magnetic flux density, particle content, strain amplitude, pre-strain and load frequency. The graphical comparison and quantitative evaluation show that the proposed models can give effective predictions of the storage and loss moduli of the produced MREs under the applied load conditions in this work.

Machine Learning Analysis Provides Insight into Mechanisms of Protein Particle Formation Inside Containers During Mechanical Agitation

Container choice can influence particle generation within protein formulations. Incompatibility between proteins and containers can manifest as increased particle concentrations, shifts in particle size distributions and changes in particle morphology distributions. In this study, flow imaging microscopy (FIM) combined with machine learning-based goodness-of-fit hypothesis testing algorithms were used in accelerated stability studies to investigate the impact of containers on particle formation. Containers in four major container categories subdivided into eleven container types were filled with monoclonal antibody formulations and agitated with and without headspace, producing subvisible particles. Digital images of the particles were recorded using flow imaging microscopy and analyzed with machine learning algorithms. Particle morphology distributions depended on container category and type, revealing differences that would not have been obvious by analysis of particle concentrations or container surface characteristics alone. Additionally, the algorithm was used to compare morphologies of particles generated in containers against those generated using isolated stresses at air-liquid and container-air-liquid interfaces. These comparisons showed that the morphology distributions of particles formed during agitation most closely resemble distributions that result from exposure of proteins to moving triple interface lines at points where container-air-liquid interfaces intersect. The approach described here can be used to identify dominant causes of particle generation due to protein-container interactions.

Laser scattering from the Ag nanofluids droplet on a plate and the surface tension measurement by scattering technique

We developed a new optical method to detect the variation of the surface tension in this work. The distribution of laser scattering from Ag nanofluids droplet on the inclined plate was collected experimentally, and the Airy structures were found in the scattering distribution. The relationship between the scattering field distribution and the liquid surface tension was derived theoretically, and the dependence of the Airy peak of the laser scattering on the surface tension was provided. Based on the relationship between the scattering field distribution and the surface tension, an optical method for the relative measurement of surface tension is established. The surface tensions of Ag nanofluids at different concentrations were measured by this optical means, and it is easy to detect the variation of Airy peak gap vs the Ag particle concentration. The results show that the surface tension of Ag nanofluids decreases with the particle concentration increase when the concentration is less than 3.16 wt. %. This work provides a new idea for surface tension measurement of nanofluids, and it has applications in the field of nanofluids wetting.

The second law of thermodynamic analysis for longitudinal strip inserted nanodiamond-Fe3O4/water hybrid nanofluids

Experiments to estimate the Nusselt number, friction factor, exergy efficiency, and thermal entropy generation of longitudinal strip inserted water diluted nanodiamond-Fe3O4 hybrid nanofluids circulate in a conduit have been carried out. The studies were carried out using Reynolds numbers ranging from 2000 to 22000, particle volume concentrations ranging from 0% to 0.2%, and longitudinal strip insert aspect ratios ranging from 0 to 4, respectively. In contrast to water data, the Nusselt number of 0.2% vol. hybrid nanofluid is raised by 29.55% at a Reynolds number of 18572. Similarly, when 0.2% vol. hybrid nanofluid with a longitudinal strip inserts aspect ratio of 1, the Nusselt number is 87.21% higher than water in a plain tube. In comparison to water, the friction factor penalty is 11.36% at 0.2% vol. of hybrid nanofluid and 46.33% at 0.2% vol. of nanofluid and with longitudinal strip insert aspect ratio of 1. Increased particle concentrations reduce the thermal entropy generation, which is further reduced by using a longitudinal strip insert with an aspect ratio of 1. Furthermore, the formation of frictional entropy is increased as particle concentrations and inserts. The exergy efficiencies for water and 0.2% vol. of hybrid nanofluid are 18.95% and 25.55%, respectively, but at 0.2% vol. of hybrid nanofluid and with longitudinal strip insert of aspect ratio 1 and at a Reynolds number of 18521, it is raised by 64.85%. The calculated thermal performance factor for all of the test situations is more than 1, indicating that hybrid nanofluids and inserts are effective at enhancing heat transfer. Nusselt number and friction factor generalized correlations were developed.

Progressive and Prospective Technology for Cloud Seeding Experiment by Unmanned Aerial Vehicle and Atmospheric Research Aircraft in Korea

This study applies a novel cloud seeding method using an unmanned aerial vehicle (UAV) and a research aircraft in Korea. For this experiment, the UAV sprayed a cloud seeding material (calcium chloride), and the aircraft monitored the clouds in the southern part of the Korean Peninsula on April 25, 2019. Cloud observation equipment in the aircraft indicated an increase in the number concentration and average particle size of large cloud particles after the seeding. Weather radar reflectivity increased by approximately 10 dBZ above the experimental area due to the development of clouds and precipitation systems. Rain was observed after seeding, and 0.5 mm was recorded, including natural and mixed precipitation from the cloud seeding. In addition, it showed that the rapid increase in the number of raindrops and vertical reflectivity was approximately 10 dBZ. Therefore, these results showed the possibility of cloud seeding using UAVs and atmospheric research aircraft. The effects of cloud seeding are indicated through the increased number concentration and size of cloud particles, radar reflectivity, and ground-based precipitation detection.

SPION based magnetic PLGA nanofibers for neural differentiation of mesenchymal stem cells

Recently, magnetic platforms have been widely investigated in diagnostic, therapeutic and research applications due to certain properties, such as cell and tissue tracking and imaging, thermal therapy and being dirigible. In this study, the incorporation of magnetic nanoparticles (MNPs) in nanofibers has been proposed to combine the advantages of both nanofibers and MNPs to induce neural differentiation of mesenchymal stem cells. Magnetic poly (lactic-co-glycolic acid) nanofibers (containing 0%, 5% and 10% SPION) were fabricated and utilized as the matrix for the differentiation of mesenchymal stem cells (MSCs). Morphological, magnetic and mechanical properties were analyzed using FESEM, VSM and tensile test, respectively. The expression of neural markers (TUJ-1, NSE, MAP-2) was assessed quantitative and qualitatively utilizing RT-PCR and immunocytochemistry. Results confirmed the incorporation of MNPs in nanofibrous scaffold, presenting a saturation magnetization of 9.73 emu g−1. Also, with increase in magnetic particle concentration (0%–10%), tensile strength increased from 4.08 to 5.85 MPa, whereas the percentage of elongation decreased. TUJ-1 expression was 3.8 and 1.8 fold for 10% and 5% magnetic scaffold (versus non-magnetic scaffold) respectively, and the expression of NSE was 6.3 and 1.2-fold for 10% and 5%, respectively. Consequently, it seems that incorporation of magnetic biomaterial can promote the neural differentiation of MSCs, during which the augmentation of super paramagnetic iron oxide concentration from 0% to 10% accelerates the neural differentiation process.

Impacts of the Variations of Aerosols Components and Relative Humidity on the Visibility and Particles Size Distribution of the Desert Atmosphere: Validating Results Obtained from OPAC 4.0 using MERRA-2 Model (Angstrom Exponent and Extinction Coefficient) Data

In this work, data extracted from OPAC 4.0 was compared and validated with 11 years data record from MEERA-2 model (average Angstrom Exponent and average Extinction Coefficient). The 11 years MEERA-2 model data for 10 selected deserts was extracted at an average relative humidity (RH) condition of 78%RH while OPAC considers eight different (RH) levels (00% to 99%RH). Based on the investigation, MEERA-2 model has the highest angstrom exponent (a) values for (Arabian, Danakil, Ferlo, Lompoul, Patagonian, Registan and Syrian deserts), which is greater than 1, and this signifies the dominance of fine mode particles over coarse mode particles when compared to OPAC 4.0. It can be seen that Chalbi (0.845), Karoo (0.482) and Sahara (0.417) deserts have an a values which is less than 1(indicating the dominance of coarse mode particles over fine mode particles). It can also be said that, MEERA-2 (a) is still greater than that of OPAC and this shows that the deserts atmosphere can be dominated by fine mode particles. The angstrom exponent (a) for OPAC 4.0 fluctuate all through the four studied components except for WASO which increases with the increase in RH and particles concentration (and this signifies that the particles dissolved as they uptake water and reach their saturation level). Based on the results of the investigation (time series analysis), it was found that the model’s significance (b) level are very high, and this shows that the aerosols distribution fluctuates around a reasonable stable, which signifies that the models are very significant. The analysis further found that, the significance (d) from the seasonal aspect is very poor except for Ferlo and Lompoul deserts, this signifies that season effect is consistent over time. It was also found that, the MEERA-2 has the highest visibility (km) over (OPAC 4.0). The investigation further revealed that the Arabian, Syrian and Patagonian deserts have the highest visibility (km) in the months of January, February, June, November and December. OPAC model underestimated the visibility when compared to MEERA-2 model.

Strength properties and microscopic mechanism of lime and fly ash modified expandable poly styrene lightweight soil reinforced by polypropylene fiber

Lime and fly ash modified expandable poly styrene (EPS) lightweight soil reinforced by polypropylene fiber (FELS) is a new type of lightweight subgrade material. In order to study the road performance and strength formation mechanism of this material, California Bearing Ratio Test (CBR) and Scanning Electron Microscopy (SEM) were performed on FELS with different EPS and fiber content. The results show that: (1) the CBR value of FELS decreases with the increase of EPS particle content. EPS particles can take on a part of the skeleton, and at the same time play the role of weight reduction and volume replacement. (2) The addition of fiber can improve the CBR value of FELS and bear part of the tensile stress and shear stress of soil under pressure. The reinforcement effect of 0.1% fiber is the best content. (3) With the increase of curing age, the CBR value of the sample increases continuously. The increase of curing age can make the internal ion exchange and hydration reaction of the structure more complete and enhance the shear resistance. The results of this study can provide a reference for the application of FELS in subgrade engineering.

A novel approach for pore-scale study of fines migration mechanism in porous media

The migration of fine particles in oil reservoir rock is the most important cause of formation damage and permeability impairment. The mechanism of this phenomenon includes fines detachment, mobilization, agglomeration, and re-attachment, which lead to throat clogging and/or blocking. Therefore, accurate modeling of this complex mechanism requires a model with high solver efficiency.In this work, based on the physical features of fines migration in pore throat, the conventional DPM model of ANSYS FLUENT software was initially modified by UDF code. Then, predetermined scenarios of suspension injection into a two dimensional (2D) microchannel were simulated for predicting pressure drop as a function of injected pore volume using the modified DPM model. Next, based on these simulation results, a proxy model using the artificial neural network (ANN) was developed for computational cost reduction of fines migration modeling in the microchannel (pore throat). Secondly, a dual pore scale numerical model by combination of proxy model and pore network modeling approach was developed to predict pressure drop as well as permeability impairment in a network of microchannels (porous media). Moreover, for rapid computation of pressure drop in the network model, a meta-heuristic method of rain optimization algorithm (ROA) has been used. Finally, for model validation, a series of laboratory tests including suspension injections into the glass micromodels were conducted.A comparison of simulation results using both proxy model and dual pore scale model with experimental data shows a good agreement and according to the obtained results, a decrease in the particles mean size, and Reynolds number as well as increase in particles concentration lead to increase in pressure drop and permeability reduction. On the other hand, use of a proxy model based on artificial neural network and a meta-heuristic method of rain optimization algorithm lead to significant computational cost reduction, while the accuracy of fines migration modeling is high enough. Hence, using our modeling approach for fines migration study in porous media as an accurate and fast computational tool can help for a better understanding of this phenomenon, which is very important in the petroleum industry.

Comparative study on recycled iron filings and glass particles as a potential fine aggregate in concrete

This study comparatively investigated the strength characteristics and workability performance of partial replacement of natural fine aggregate with waste glass particles and iron filings in concrete production. Fine aggregate was replaced with 0%, 5%, 10%, 15%, 20%, and 25% of waste glass particles and iron filings respectively at a water-cement ratio of 0.55. The result indicated that an increase in percentage replacement of iron filings reduced the slump value and workability of the concrete, while the increase in the percentage content of glass particles increased its slump value and workability. The result showed that concrete with 20% replacement of sand by iron filing and waste glass particles attained the optimum strength. Furthermore, concrete samples containing glass particles exhibited a steady increase in flexural strength at all replacement levels. The use of iron filings and glass particles in the production of concrete will enhance preservation of natural resources and waste management

Variability of near-surface aerosol composition in Moscow in the spring of 2020

The paper studies variability in mass concentration and elemental composition of near-surface aerosol in Moscow in March-April 2020. During the study period, noticeable fluctuations in concentration of surface aerosol caused by atypical synoptic and meteorological conditions were revealed. Sharp increase in PM10 particle concentration (March 25-29, April 13) is associated with anticyclonic activity and advection of air containing combustion aerosols from the areas with biomass fires. In April as a whole, anomalously low values of aerosol particle concentrations were recorded in comparison with the long-term average. The prevailing dry Arctic air masses significantly decreased the atmospheric aerosol pollution. The decrease of anthropogenic load during COVID-19 non-proliferation actions affected on daily variations of the surface aerosol, smoothing out its typical daily maximal concentration values. Results of spring experiment at the IAP RAS showed good agreement with the data of the Obuchi nearest station of State Budgetary Institution "Mosecomonitoring". We analyzed geochemical spectrum of chemical elements in aerosol and its variability under different synoptic and weather conditions in Moscow. Possible sources and sinks of aerosols are discussed taking into account both abnormal weather conditions and decreased anthropogenic load during a lockdown period in the spring of 2020.

Generation of ash particles from different lube oil mists

Ash and soot particles are generated during engine combustion and are deposited in particulate filters. In order to understand the basic processes that occur in a particulate filter during the filtration process the particles have to be generated quickly and replicably. In this study, fundamental investigations are conducted on the generation of ash particles independently of an engine to produce a defined aerosol. The formation of ash particles from engine oils with differences in sulfate ash content (SAC; 0.7%, 2.6%, 4.5%) as well as the variation of process parameters (oil temperature, nozzle volume flow) are investigated. The ash particles are produced by nebulizing engine oil and a subsequent thermal conversion in a furnace. The SAC of the oil does influence the ash particles that are generated. With the increase of the SAC, the ash mass flow and the number weighted median diameter increase. Raising the nozzle volume flow as well as the oil temperature leads to an increase in total number concentration and mass flow of the ash particles. The number median diameter of the oil mist and ash particles decrease with the increase of oil temperature and nozzle volume flow. For the fast loading of a particulate filter, the SAC of the oil should be 4.5%. The oil temperature and nozzle volume flow should be set at 30 °C and 6 L·min−1. In conclusion, the ash generation method can be used for the rapid loading of a particulate filter.

Impact of increased particle concentration on magnetorheological fluid properties and their damping performance

Impact of increased particle concentration on magnetorheological fluid properties and their damping performance

Dynamic viscosity and surface tension of propylene glycol containing TiO2 nanoparticles

Adding nanoparticles with high thermal conductivity into the work fluid is one of the most significant ways to enhance heat transfer. In this article, the influences of nanoparticle mass concentration (0.5–10.0 wt.%) and temperature (5–25 °C) were investigated on the viscosity of TiO2-propylene glycol nanofluid. At the same time, eight kinds of mass concentrations (0.5–10.0 wt.%) were used to investigate the changing regularity on the surface tension of nanofluid; Accordingly, the modified correlations including nanoparticle concentration were proposed respectively. The experimental results show that the viscosity of the nanofluid increases with the increase in particle concentration. Within the concentration of 10.0 wt.%, the viscosity increases by about 7.0% for every 1.0 wt.%. While the viscosity decreases with the increase in the temperature. The surface tension of the mixture increases slowly with the increase in particle concentration. Within 2.0 wt.%, the surface tension of nanofluid increases by less than 1.0% for every 0.5 wt.%, when the concentration of nanofluid exceeds 2.0 wt.%, surface tension raises less than 1.0% per 2.0 wt.%.

Effects of residual stress and intragranular particles on mechanical properties of hot-pressed Al2O3/SiC ceramic composites

Al2O3/SiC ceramic composites with different SiC contents have been prepared by powder metallurgy at 1600 °C for 120 min at 30 MPa pressure. The effect of second phase particles on the microstructure and mechanical properties of composites have been studied. The results show that SiC particle has a significant impact on the matrix subjected to residual stress, and on the microstructure of the composites as well. The average grain size of alumina matrix decreases as the SiC particle content increases. Simultaneously, it has been found that the mechanical properties of the material are significantly enhanced in comparison with monolithic Al2O3. The highest strength and toughness are obtained when the SiC content is 15 vol%, and the values are 1237 MPa and 5.68 MPa m1/2, respectively. The mechanisms of strengthening and toughening have been discussed.

Evaluation of Wear Measurement with Radioactive Isotopes for DLC Coatings Affected by Abrasive Particles

Diamond-like carbon (DLC) coatings protect engine parts from wear and provide low-friction. Unfortunately, the nature of DLC coatings does not allow progressing wear measurement using conventional methods. Therefore, we applied a radioactive isotope-based wear measurement method (RIC method). A tribometer with oscillating contact and one with sliding contact were used to provide different loading conditions. The RIC method was evaluated for DLC coatings, and the DLC wear was investigated regarding the presence of abrasive particles. The results indicate that an increase in abrasive particle concentration leads to an increase of DLC wear rate and a decrease in usage-time until wear-off.

Atmospheric deposition of anthropogenic particles and microplastics in south-central Ontario, Canada

Microplastics are ubiquitous in the environment; however, few studies have examined their abundance in atmospheric deposition in pristine environments, remote from anthropogenic emission sources. In the current study, atmospheric deposition samples were collected for 13 months (February 2019–March 2020) from four precipitation chemistry monitoring stations located in Muskoka-Haliburton, south-central Ontario, Canada. Anthropogenic particles (i.e., synthetic particles but not necessarily plastic) were observed at each station with an average deposition rate of 57 particles/m2/day (range from 32 to 73 particles/m2/day). Of the anthropogenic particles identified, 12% were plastic resulting in an average microplastic (mp) deposition rate of 7 mp/m2/day (range 4–9 mp/m2/day). Approximately 85% of the particles were fibres with fragments comprising only 15%. The most common particle colours were blue and red with 50% of the fragments and 84% of fibres being one of these two colours. Raman spectroscopy determined that polyamide and polyethylene terephthalate were the two most abundant polymers at 24% and 19%, respectively. Across the four stations anthropogenic particle concentrations were significantly related to wind speed (rs = 0.32 to 0.62) and temperature (rs = −0.53 to −0.84), with a noticeable increase in particle concentration when wind shifted from the west (average of 7.2 mp/L) to the south-east (average of 11.5 mp/L). Faster wind speed resulted in a larger airshed source area, and the seasonal effect associated with changes in temperature and wind direction led to changes in potential source regions that were contributing microplastics, such as the Greater Toronto Area (>200 km away).

Effect of Bionic Nonsmooth Surface Vane on the Antiwear Characteristics of Double-Vane Pump.

In order to improve the antiwear characteristics of the double-vane self-priming pump, the surface structure of the Scapharca subcrenata was extracted and reconstructed according to bionic principles. Three types of nonsmooth surface models were established at the outlet end of the suction surface of the vanes, which is the most severely worn in the double-vane pump. The external characteristics, pressure field distribution, wear area distribution, and wear degree of the volute and vanes at different concentrations of nonsmooth vane structure were investigated by numerical simulation to reveal the mechanism of the nonsmooth surface structure of the wear characteristics of the vanes. The results show that the head and efficiency of pumps with four different vanes decrease and the average wear rate increases as the particle concentration increases. The different vane structures have a very small effect on the wear resistance of the volute, but a larger effect on vane wear. The circular nonsmooth surface structure, which reduces the low pressure area of the inlet section of the impeller while ensuring a smaller drop in head and efficiency, produces the best antiwear effect and improves the antiwear performance of the double-vane pump.

Ethanol-tolerant pickering emulsion stabilized by gliadin nanoparticles

In this paper, ethanol-tolerant Pickering emulsion was prepared using gliadin nanoparticles (NPs) based on pH adjustment coupled heat treatment. The effects of gliadin NPs concentration on ethanol-tolerant Pickering emulsions in terms of emulsion size, microstructure, and rheology were investigated. The results indicated that gliadin NPs exhibited an elliptical appearance. At pH 7, the particle size was 600.04 ± 4.80 nm, and the polydispersity coefficient was 0.18 ± 0.29. Fluorescence spectra showed that this method destroyed the tertiary structure of the protein and initiated the self-assembly of gliadin. With the increase of particle concentration, the size of the Pickering emulsion decreased, and the emulsion gradually became gelatinized. The increase of particle concentration made the oil-water interface in emulsion more robust. This study showed that the preparation of gliadin NPs based on pH regulation coupled heat treatment could stabilized the emulsion in the presence of ethanol. The structural and functional properties of Pickering emulsion could be regulated by the concentration of particle stabilizers, thus providing a theoretical basis for constructing structured and functionalized Pickering emulsions.