Decreasing Particle Diameter Research Articles

Abstract MP28: Advanced Lipid Status Parameters in Women With Preeclampsia

Preeclampsia (PE) is a hypertensive disorder associated with pregnancy, usually occurring after the 20th week of gestation, followed by proteinuria or signs of end-organ dysfunction. Early-onset preeclampsia is associated with placental dysfunction, while late-onset preeclampsia is recognized as a maternal disorder, influenced by risk factors like maternal obesity, diabetes mellitus, or chronic hypertension. During physiological pregnancy, lipid metabolism changes to adequately supply the fetoplacental unit with nutrients and energy, consequently changing the composition of LDL and HDL particles. However, in preeclampsia, these changes become atherogenic. The study aimed to examine changes in advanced lipid status parameter concentrations and the dominant diameter of LDL and HDL particles during pregnancies affected by PE. In this study, 92 pregnant women at high risk for complication development were followed longitudinally throughout the first (T1), second (T2), and third (T3) trimesters. They were classified into high-risk (HR) (72 women) and PE (20 women) groups based on pregnancy outcomes. Total cholesterol (TC), HDL-C, triglycerides (TG), apoAI, and apoB concentrations were measured using commercial kits, while LDL-C concentrations and the atherogenic index of plasma (AIP) were calculated using established equations. Dominant LDL and HDL particle sizes were determined by gradient gel electrophoresis. TG levels were significantly higher in the PE group compared to the HR group across all trimesters (p<0.05; p<0.05; p<0.01), while AIP was significantly elevated in T2 (p<0.01) and T3 (p<0.01). HDL-C levels were lower in the PE group than in the HR group in T2 (p<0.05). In the HR group during pregnancy, concentrations of TC, TG, LDL-C, apoB, as well as HDL-C increased significantly (p<0.05 for all parameters), while the dominant LDL diameter decreased markedly (p<0.001) between all trimesters, without changes in the dominant HDL diameter. There were no changes in HDL-C concentration during pregnancy in the PE group. In contrast, TG concentrations increased significantly (p<0.01), accompanied by a significant decrease in dominant LDL particle diameter (p<0.05). In conclusion, pregnant women with PE exhibit atherogenic changes in lipid status parameters, including no increase in HDL-C concentration, potentially leading to a loss of HDL's protective effect.

A numerical study of Elasto-inertial particle-focusing in straight and serpentine microchannels

Microfluidic devices have gained popularity in recent years due to their low cost and simplicity. Cell focusing linked with cell counting and cell separation used in clinical tests and point-of-care devices stands towards the top of every list of microfluidic applications. To focus and manipulate particles in a Newtonian medium, inertial microfluidics has been widely used. There is a requirement to replace a significantly more efficient approach given various particle-focusing positions near the channel walls recorded by inertial microfluidics. Here, the synergetic effect of elastic and inertial forces in relatively low-concentration viscoelastic fluids was investigated numerically. Utilizing particle-focusing behavior in straight and serpentine channels with different corner angles, by applying the numerical results obtained using the developed direct numerical simulation method (DNS) for elastic and inertial forces, we created a microchannel with a remarkable performance. As the flow regime transitions to elasto-inertial, where inertial forces are comparable to elastic forces in a straight microchannel, particles tend to concentrate at the channel centerline. As the flow rate increases, however, particle defocusing develops, and shear gradient lift forces ultimately overcome elastic forces in the channel's central region. Given that fluid flows at a higher velocity in the serpentine channel with a corner angle of 75° than in other channels, the Dean drag force induced by secondary flow serves to reduce particle defocusing rate at a given flow rate, making this channel a desirable platform for Elasto-inertial microfluidics. Particle focusing in a vertical direction was noticed as a benefit of elasto-inertial microfluidics, regardless of the geometry or flow rate of the particles passing through the channel. Finally, the impact of particle diameter on focusing behavior was studied. As particle diameter decreases, focusing width decreases and the focusing band shifts to the left side of the cross-section. We expect that the numerical evaluation of using viscoelastic medium in complex geometries can contribute to accelerate the three dimensional particle-focusing mechanism and enhance the efficiency of microdevices for cell and particle manipulation.

Modelling alkali–silica reaction from micro-computed tomography images: role of particle size and water/cement ratio

An experimental programme was conducted to observe, non-destructively, the influence of aggregate particle size and low water/cement (w/c) ratios on alkali–silica reaction (ASR) in concrete using micro-computed tomography scanning. The results were analysed using a model developed as part of a previous study. ASR expansion and cracking was observed to increase to strain levels of around 0.010 with a decrease in particle diameter up to a ‘pessimum’ diameter of 1–2 mm. Below the pessimum diameter, expansion was low: around 0.001 strain. Analysis using the previously developed model clearly illustrated a transition from above the pessimum diameter, where ASR was the main process occurring, to below this size, where a pozzolanic reaction dominated. ASR expansion increased with a decrease in the w/c ratio, reaching strains of around 0.015. The model indicated that this is fundamentally a result of extended periods of restraint of ASR gel around aggregates, ultimately ending in much greater expansion when fracture eventually occurred. Additionally, cracking of aggregate coincided with an accelerated rate of expansion in mixes with w/c ratios below 0.6.

Oxidation-induced variations in the physical and fragmentation characteristics of exhaust soot from DMC-diesel blend: Effect of NO presence in the air atmosphere

This study investigated the changes in physical properties (including morphology, primary particle diameter, fractal dimension, and nanostructure) and fragmentation characteristics of exhaust soot from a modern direct injection diesel engine fueled with diesel (D100) and its blend with 7 vol% of dimethyl carbonate (DMC7) during oxidation processes in air and air-NO atmospheres. Soot particles (D100 soot and DMC7 soot) with specific oxidation degrees (0%, 20%, 50%, and 80%) were produced using a thermogravimetric analyzer, then applied to a high-resolution transmission electron microscopy to generate images. The results exhibited that the morphology for D100 soot and DMC7 soot transformed similarly through oxidation, experiencing an increase in fractal dimension, and a decrease in primary particle diameter, while the introduction of NO to the air accelerated these transformations. Additionally, the nanostructure of both soot particles was gradually ordered through oxidation, as evidenced by longer fringe length, narrower separation distance, and lower tortuosity, while DMC7 soot showed lower order degree compared to D100 soot. Interestingly, the ordering processes of soot nanostructure were decelerated as NO was involved in the oxidation process. Furthermore, the aggregate fragmentation rate for both soot particles declined over the oxidation process, while the possibility for primary particle fragmentation increased overall. Moreover, DMC7 soot exhibited significantly lower aggregate fragmentation rate and higher possibility for primary particle fragmentation than D100 soot at the same oxidation stage. This suggests that DMC7 soot is more susceptible to internal oxidation compared to D100 soot. Furthermore, the presence of NO in the air promoted aggregate fragmentation, while reducing the possibility of primary particle fragmentation.

The fluidization behavior of particles in supercritical water fluidized bed: A region-dependent analysis

The distribution and fluctuation of particle concentration in a supercritical water fluidized bed (SCWFB) are studied using a specially-designed capacitance probe measurement system. The measurement error of capacitance probe system is 2.48%. Results show that the particle concentration at the axial line fluctuates largely with time and the fluctuation is weakened when increasing the distance from axial line or decreasing particle diameter. At Uf/Umb=1.5, the largest difference between particle concentrations is 0.026, 0.04, 0.082 when the particles with a diameter of 0.124 mm, 0.198 mm, 0.235 mm are used, indicating a larger non-uniformity of larger particles. The probability density of local particle concentration mainly follows a unimodal distribution with the peak at right side. The main frequency of SCWFB ranges from 1.39 Hz to 2.73 Hz in this experiment and the main frequency decreases when larger particles are used.

Numerical simulation of transpiration cooling in porous nose cone under hypersonic conditions

Transpiration cooling in a two-dimensional porous nose cone under hypersonic flow have been numerically investigated. The numerical model intricately captures the interaction between compressible and incompressible flows in the boundary layer and the phase change of coolant within porous region. The validation of numerical method is performed by comparing the simulation results with experimental data. The simulation results are in reasonable agreement with the experimental data. The results show that the increase of blowing ratio can effectively improve the cooling efficiency of transpiration cooling，where the blowing ratio represents the mass flow rate ratio between the coolant of porous region and the mainstream free flow. Such as, the average cooling efficiency rises from 0.33 to 0.86 when the blowing ratio increases from 0.0459% to 0.2753%. Although the porous resistance force increases as the particle diameter and porosity decrease, the effect of these parameters and solid material of porous region on the cooling efficiency are marginal.

Performance of industrially implemented turbulent contact absorbers – A comparative study

The current study aims to assess the performance and industrial feasibility of using three-phase fluidized bed absorption columns for post-combustion carbon dioxide (CO2) capture. The analysis is based on a mathematical model of a scaled-up fluidized bed absorption column that has been validated using pilot plant experimental data. The focus is on evaluating the energy efficiency of the fluidized bed column in comparison to packed bed technologies, which are currently widely used. The results of the analysis are evaluated in terms of three performance indicators (i.e., absorption efficiency, carbon capture rate, and energy performance index) and compared to packed bed columns. Simulation results indicate that the best column configuration is represented by a three-stage absorber and that the system performs optimally when particle diameter and density decrease with each section. Consequently, this leads to an increase in the total fluidized bed height and carbon capture rate by up to 25%. The energy performance index is maintained below 3.6, indicating an energy-efficient operation of the system. As such, the findings of this study suggest that the use of gas-solid-liquid three-phase fluidized bed absorption columns for post-combustion CO2 capture is a promising technology for the implementation of CCUS and for achieving of climate neutrality targets.

Shear thickening in suspensions of particles with dynamic brush layers.

Control of frictional interactions among liquid-suspended particles has led to tunable, strikingly non-Newtonian rheology via the formation of strong flow constraints as particles come into close proximity under shear. Typically, these frictional interactions have been in the form of physical contact, controllable via particle shape and surface roughness. We investigate a different route, where molecular bridging between nearby particle surfaces generates a controllable constraint to relative particle movement. This is achieved with surface-functionalized colloidal particles capable of forming dynamic covalent bonds with telechelic polymers that comprise the suspending fluid. At low shear stress this results in particles coated with a uniform polymer brush layer. Beyond an onset stress σ* the telechelic polymers become capable of bridging and generate shear thickening. Over the size range investigated, we find that the dynamic brush layer leads to dependence of σ* on particle diameter that closely follows a power law with exponent -1.76. In the shear thickening regime, we observe an enhanced dilation in measurements of the first normal stress difference N1 and reduction in the extrapolated volume fraction required for jamming, both consistent with an effective particle friction that increases with decreasing particle diameter. These results are discussed in light of predictions for suspensions of hard spheres and of polymer-grafted particles.

Motion and dispersion characteristics of graphite particles in a bottom-blown converter for molten slag reduction

In order to improve the recovery of iron resource in molten basic oxygen furnace (BOF) slag through carbothermal reduction, bottom blowing argon gas is used to promote the mixing efficiency between molten slag and graphite particles in the converter. In the present work, computational fluid dynamic-discrete particle model (CFD-DPM) method coupled with the reduction kinetic model of FeO in molten slag by graphite particle is employed to simulate the multiphase system composed of molten slag, graphite particle and argon gas. The motion and dispersion characteristics of graphite particles in a bottom-blown converter were mainly investigated, and the decrease of graphite particle diameter caused by the reduction reaction was considered. A particle dispersion index was also proposed to evaluate the distribution uniformity of graphite particles in the molten slag. In addition, the effects of initial particle diameter and bottom tuyere arrangement on the dispersion characteristics of graphite particles were further discussed. The results show that the proportion of large-sized particles is higher in the inactive-flow zone and the motion trajectory of graphite particles can be divided into two regimes. Graphite particles with an initial diameter of 5 mm and the converter with six bottom-blown tuyeres are more conducive to the homo-dispersion of graphite particles.

Centrifugal Microfluidic Synthesis of Nickel Sesquioxide Nanoparticles.

Nickel sesquioxide (Ni2O3) nanoparticles were synthesized using centrifugal microfluidics in the present study. The obtained nanoparticles were characterized using SEM to investigate their morphology and microstructure, and XRD was employed to analyze their purity. The nanoparticle size data were measured and analyzed using ImageJ (v1.8.0) software. The flow process and mixing procedure were monitored through computational fluid dynamics simulation. Among the synthesized Ni2O3 nanoparticles, those obtained at the rotation speed of 1000 rpm for 10 min with angular acceleration of 4.2 rad/s2 showed the best performance in terms of high purity, complete shape and microstructure, small diameter, and narrow diameter distribution. The experimental results demonstrate that the rotation speed of the microfluidic chip and reaction time contribute to a decrease in particle diameter and a narrower diameter distribution range. In contrast, an increase in acceleration of the rotation speed leads to an expanded nanoparticle size range and, thus, a wider distribution. These findings contribute to a comprehensive understanding of the effects exerted by various factors in centrifugal microfluidics and will provide new insights into nanoparticle synthesis using centrifugal microfluidic technology.

A molecular dynamics study of the effects of velocity and diameter on the impact behavior of zinc oxide nanoparticles

Molecular dynamics simulations of particle impact have been conducted for a ceramic with mixed ionic-covalent bonding. For these simulations, individual zinc oxide (ZnO) nanoparticles (NPs) were impacted onto a ZnO substrate to observe the effects of impact velocity (1500–3500 m s−1) and particle diameter (10, 20, and 30 nm) on particle deformation and film formation mechanisms that arise during the micro-cold spray process for producing films. The study shows that a critical impact velocity range exists, generally between 1500 and 3000 m s−1, for sticking of the NP to the substrate. Results suggest that solid-state amorphization-induced viscous flow is the primary deformation mechanism present during impact. Decreasing particle diameter and increasing impact velocity results in an increased degree of amorphization and higher local temperatures within the particle. The impact behavior of mixed ionic-covalent bonded ZnO is compared to the behavior of previously studied ionic and covalent materials.

Crystalline and amorphous microstructure evolution of Zr-Cu-Al ternary alloys solidified in drop tube

High undercooling rapid solidification process has a significant impact on the solidified microstructure and mechanical properties of materials. In this study, particles with a diameter range between 100 and 1100 µm of ternary Zr50Cu40Al10 and Zr49Cu46Al5 alloys were prepared by a drop tube. The evolution process of particle-solidified microstructure with decreasing particle diameter was analyzed using XRD, SEM, and TEM. For Zr50Cu40Al10 alloy, the solidified microstructure in the particle diameter ranges of 200–1100 µm is composed of an amorphous phase and a primary B2-ZrCu high-temperature metastable phase. As the particle diameter reduces, the retained crystalline phase in the solidified microstructure decreases progressively, and the dendrite grain length gradually becomes finer. When the particle diameter is reduced to below 200 µm, the crystalline phase has completely disappeared, and the solidified microstructure evolves into a completely amorphous structure. For Zr49Cu46Al5 alloy, in the particle diameter range of 400–1100 µm, the solidified microstructure consists of primary B19'-ZrCu phase, a small amount of Cu10Zr7 phase and Zr14Cu51 phase. As the particle diameter reduces, a grain refinement phenomenon also occurs in the solidified microstructure and the dendritic morphology changes from equiaxed grain to rod-shaped dendrite. The amorphous phase appears when the particle diameter is lowered to 470 µm and solidified microstructure evolves into a completely amorphous structure as the particle diameter is reduced to 146 µm. The nanoindentation results show that the micromechanical properties of amorphous composite microstructures are superior to the single component composition of crystalline or amorphous phase for Zr50Cu40Al10 and Zr49Cu46Al5 alloys. The reinforcement effect on the amorphous phase is related to the content of the second crystalline phase. Moreover, under similar particle diameters, the mechanical properties of Zr50Cu40Al10 particles are always better than those of Zr49Cu46Al5 particles.

The reaction mechanism and interfacial crystallization of Al nanoparticle-embedded Ni under shock loading

The shock-induced reaction mechanism and characteristics of Ni/Al system, considering an Al nanoparticle-embedded Ni single crystal, are investigated through molecular dynamics simulation. For the shock melting of Al nanoparticle, interfacial crystallization and dissolution are the main characteristics. The reaction degree of Al particle first increases linearly and then logarithmically with time driven by rapid mechanical mixing and following dissolution. The reaction rate increases with the decrease of particle diameter, however, the reaction is seriously hindered by interfacial crystallization when the diameter is lower than 9 nm in our simulations. Meanwhile, we found a negative exponential growth in the fraction of crystallized Al atoms, and the crystallinity of B2–NiAl (up to 20%) is positively correlated with the specific surface area of Al particle. This can be attributed to the formation mechanism of B2–NiAl by structural evolution of finite mixing layer near the collapsed interface. For shock melting of both Al particle and Ni matrix, the liquid-liquid phase inter-diffusion is the main reaction mechanism that can be enhanced by the formation of internal jet. In addition, the enhanced diffusion is manifested in the logarithmic growth law of mean square displacement, which results in an almost constant reaction rate similar to the mechanical mixing process.

Electrolyte pH dependence of composition, roughness parameters, particle diameter and magnetic features of nanostructured Fe-Co-Ni/ITO deposits prepared by electrochemical deposition method.

The composition, structural features, surface morphology, roughness parameters, particle size, and magnetic features of nanostructured Fe-Co-Ni deposits manufactured on conducting indium tin oxide-coated glasses at various electrolyte pH values are studied. The deposit produced at low electrolyte pH contains slightly higher Fe and Co contents but lower Ni content compared to deposits fabricated at high pH values. Further composition analysis confirms that the reduction rates of Fe2+ and Co2+ are higher than the Ni2+ reduction rate. The films consist of nano-sized crystallites with a strong [111] preferred orientation. The results also reveal that the crystallization of the thin films is affected by the electrolyte pH. Surface analysis shows that the deposit surfaces are composed of nano-sized particles with different diameters. The mean particle diameter and surface roughness decrease as the pH of the electrolyte decreases. The effect of the electrolyte pH on the morphology is also discussed in terms of surface skewness and kurtosis parameters. Magnetic analysis shows that the resultant deposits have in-plane hysteresis loops with low and close SQR parameters ranging from 0.079 to 0.108. The results also reveal that the coercive field of the deposits increases from 29.4Oe to 41.3Oe as the electrolyte pH decreases from 4.7 to 3.2.

Three-dimensional pore structure characteristics of granite residual soil and their relationship with hydraulic properties under different particle gradation by X-ray computed tomography

The pore structure characteristics and hydraulic properties, including saturated hydraulic conductivity and soil water retention curve (SWRC), for granite residual soil under different particle gradation were carried out by high-resolution X-ray computed tomography (CT) and pressure plate. The relationship between three-dimensional pore structure characteristics and hydraulic properties were quantitatively analyzed. The results show that the decrease of the average pore/throat radius and the CT-connected porosity with the particle diameter decreases, but the fractal dimension value increases, indicating that the soil pore structure became complex. The effect on hydraulic properties is the comprehensive effect of soil properties and soil structure. Adding big particles improved the saturated hydraulic conductivity by increasing the soil pore connectivity and decreasing the fractal dimension. In addition, the micropore spatial variation and complex pore structure help to increase the water retention capacity.

Cr-substituted Fe[formula omitted]O[formula omitted] nanoparticles: The role of particle size in the formation of Fe[formula omitted]O sub-domains and the emergence of exchange bias

Here we study the influence of particle size on the formation of antiferromagnetic FexO subdomains and the emergence of exchange bias in novel ferrimagnetic Cr-substituted Fe3O4 nanoparticles generated using an aerosol technique based on spark ablation. Cooling in an applied magnetic field across the Néel temperature of the FexO subdomains results in significant shifts in the hysteresis loops, which decrease in magnitude with the particle diameter for the two large systems (D≈20nm&D≈40nm), whereas only minor exchange fields are observed for the smallest system (D≈10nm). The reduced exchange bias is attributed to the metastable FexO’s lower volume fraction and size due to a facile transformation into the thermodynamically stable (Fe,Cr)3O4 phase with decreasing particle diameter.

Particle trajectory and pulsation flame of magnesium combustion

Green recyclability, high-energy density and zero-carbon nature are among the pivotal benefits of magnesium sustainable fuel. In current study, two crucial issues corresponding to the premixed magnesium combustion comprising the trajectories of magnesium and magnesia and pulsation flame are assessed. Regarding the detailed multi-zone flame structure and consideration of thermal and dynamical non-equilibrium, the governing equations and boundary conditions are derived. These equations involve the impacts of decisive items, namely semi-variable thermophysical properties, thermophoretic motion, chamber heat loss and flame radiation. The results reveal that with decreasing particle diameter, the importance of the items considered in current modeling increases and its outputs become closer to experimental data. The heat loss of combustion chamber containing magnesium particles with 15 µm diameter has the greatest impact on flame velocity prediction. While for 34 and 70 µm particles, the semi-variable properties and flame radiation are the main influential items in the flame velocity calculation, respectively. Eventually, the magnesium pulsation combustion is scrutinized under the external perturbation in flow velocity. It is found that using helium as neutral gas instead of nitrogen lessens the maximum amplitude of flame oscillation by 16.75 times.

Microwave-assisted biosynthesis of flower-shaped ZnO for photocatalyst in 4-nitrophenol degradation

In this paper, the flower-shaped ZnO particles have been prepared via microwave-assisted biosynthesis technique using an aqueous extract of Sandoricum koetjape peel at various irradiation powers, i.e. 180, 360, 540, and 720 Watt. The synthesized flower-shaped ZnO particles were characterized using UV-Vis spectroscopy, x-ray diffraction (XRD), and field emission scanning electron microscope (FESEM). The UV-vis spectra exhibited ZnO absorption peaks in the UV region with band gap energy in the range of 3.25 - 3.29 eV. XRD analysis confirmed the hexagonal wurtzite crystal with the high purity of ZnO particles. The flower-shaped morphology of ZnO was evident in FESEM images with the decrease of particle diameter as the radiation power increased from 257 to 447 nm. ZnO prepared at 720 Watt (Z-720) succeeded in degrading 4-nitrophenol with the highest efficiency of 84.8 % after 240 min. Consequently, biosynthesis ZnO will have a great opportunity to be applied in degrading wastewater pollutants.

Effect of metal anti-wear device on the water wall erosion in CFB boiler

The erosion of water wall tube induced by the flushing of ash is one of the safest factors in the operation of the circulating fluidized bed (CFB) boiler. The reasonable installation of a metal anti-wear device on the water wall provides an effective protection method for reducing particle erosion on the wall surface. Seven metal anti-wear devices were designed and evaluated by comparing the erosion distribution of the local water wall surface in this work. The results show the type with an angle between the windward side and the water wall greater than 90° and the leeward side perpendicular to the water wall can obtain a good anti-wear effect. The erosion rate of water wall increases correspondingly with the increasing inlet velocity and particle size, but decreases to some extent by adding cohesive particles. The height of the ash deposition zone decreases correspondingly with the decreasing particle diameter and proportion of cohesive particles. The type G metal anti-wear device was preferably applied and tested in a CFD boiler for half a year according to its simple structure and its behavior of reducing erosion rates. The Type G anti-wear device can well protect the water wall of CFB boilers at the power plants.

Bed expansion of binary mixtures of irregular particles in solid–liquid fluidization: Experimental, empirical correlation, and GA‐ANN modelling

AbstractExpansion behaviour for a bed of binary mixture of the irregularly shaped particle in Newtonian liquid was measured in two different circular columns. Variations in the physical parameters on the expansion behaviour have been reported. Bed expansion increases with an increase in liquid velocity and a decrease in particle diameter. Static bed height and expansion of the bed are low for higher diameter columns. An empirical correlation has been developed for predicting the ratio of bed height at the fluidized condition to the initial bed height as a function of the physical and dynamic variables related to the system for the binary particle mixtures. The correlation coefficient and variance of the estimate are 0.9299 and 0.0013, respectively, which is acceptable statistical accuracy. A hybrid of the genetic algorithm and neural network modelling for the prediction of the same has also been attempted where the input parameters are optimized using the Levenberg–Marquardt algorithm. With a relative error of 1.46%, the genetic algorithm performed well. So, the modelling has successfully predicted the bed height ratio at fluidized conditions to the initial bed height.