Mass Ratio Of Particles Research Articles

Effect of particle grading on the properties of photosensitive slurry and BaTiO3 piezoelectric ceramic via digital light processing 3D printing

To improve the density and piezoelectric constant of BaTiO3 ceramics prepared by Digital Light Processing 3D printing, the properties of photosensitive slurry were investigated from the perspective of particle grading, and the nitrogen-air two-step debinding and sintering process on the relative density and electrical properties were explored. It was found that as the mass ratio of coarse particles increased, the viscosity, shear stress and cure depth of the slurry decreased. When the mass ratio of fine and coarse particles was 2:8 and sintered at 1350 °C, the ceramic had better performance, with relative density reaching 95.39 ± 0.63 %. The piezoelectric constant d33 was 215 ± 13 pC/N, 29.52 % higher than the single-peak powder. The relative permittivity (εr) and polarization (Pr) were 978 and 16.656 μC/cm2. Finally, BaTiO3 ceramics with Triply Periodic Minimal Surface structures were prepared as piezoelectric sensors, which had the highest output voltage at the same displacement when the mass ratio was 2:8.

Effects of spherical Al2O3 grades on crack initiation of thermal conductive silicone pads under high-temperature aging

ABSTRACT In this paper, the rule and mechanisms of crack initiation and propagation in the aging process of thermal conductive silicone pads (TCSP) were investigated by designing Al2O3 particle grading schemes with different particle sizes and mass ratios. Scanning electron microscope and energy dispersive spectrometer analysis showed that TCSP prepared with Al2O3 particles of various sizes according to the gradation ratio had the best anti-aging effect at high temperatures. At this time, the aging was mainly due to the aging degradation of the polymer matrix; When the proportion of small-size Al2O3 particles increases, aggregates and pore defects appear in TCSP. At this time, the main reason for its aging is that the high-temperature expansion of gas in pore defects accelerates the aging degradation of the polymer matrix; When the proportion of small-sized Al2O3 particles decreases, a large number of holes appear in TCSP and the coverage rate of the polymer matrix on Al2O3 particles decreases. The main reason for the high-temperature aging crack is that the gas between the holes expands at high temperature, resulting in the rapid extension of the crack and the polymer matrixes falling.

Role of Secondary Organic Matter on Soot Particle Toxicity in Reconstituted Human Bronchial Epithelia Exposed at the Air-Liquid Interface.

Secondary organic matter (SOM) formed from gaseous precursors constitutes a major mass fraction of fine particulate matter. However, there is only limited evidence on its toxicological impact. In this study, air-liquid interface cultures of human bronchial epithelia were exposed to different series of fresh and aged soot particles generated by a miniCAST burner combined with a micro smog chamber (MSC). Soot cores with geometric mean mobility diameters of 30 and 90 nm were coated with increasing amounts of SOM, generated from the photo-oxidation of mesitylene and ozonolysis of α-pinene. At 24 h after exposure, the release of lactate dehydrogenase (LDH), indicating cell membrane damage, was measured and proteome analysis, i.e. the release of 102 cytokines and chemokines to assess the inflammatory response, was performed. The data indicate that the presence of the SOM coating and its bioavailability play an important role in cytotoxicity. In particular, LDH release increased with increasing SOM mass/total particle mass ratio, but only when SOM had condensed on the outer surface of the soot cores. Proteome analysis provided further evidence for substantial interference of coated particles with essential properties of the respiratory epithelium as a barrier as well as affecting cell remodeling and inflammatory activity.

Using the Black Carbon Particle Mixing State to Characterize the Lifecycle of Biomass Burning Aerosols.

The lifecycle of black carbon (BC)-containing particles from biomass burns is examined using aircraft and surface observations of the BC mixing state for plume ages from ∼15 min to 10 days. Because BC is nonvolatile and chemically inert, changes in the mixing state of BC-containing particles are driven solely by changes in particle coating, which is mainly secondary organic aerosol (SOA). The coating mass initially increases rapidly (kgrowth = 0.84 h-1), then remains relatively constant for 1-2 days as plume dilution no longer supports further growth, and then decreases slowly until only ∼30% of the maximum coating mass remains after 10 days (kloss = 0.011 h-1). The mass ratio of coating-to-core for a BC-containing particle with a 100 nm mass-equivalent diameter BC core reaches a maximum of ∼20 after a few hours and drops to ∼5 after 10 days of aging. The initial increase in coating mass can be used to determine SOA formation rates. The slow loss of coating material, not captured in global models, comprises the dominant fraction of the lifecycle of these particles. Coating-to-core mass ratios of BC particles in the stratosphere are much greater than those in the free troposphere indicating a different lifecycle.

Applicability of Pressurized TiO2 Fixation Method to Existing Vertical Concrete Road Structures

The purpose of this study is to evaluate the pressurized titanium dioxide (TiO2) fixation method and its application to hardened vertical structures nearby the road. The usefulness of pressurized TiO2 fixation method for the application of vertical concrete road structures such as side ditches, barriers, and retaining walls was evaluated based on conditions of experiment taking cognizance of pressurization time and pressure. To confirm the TiO2 distribution characteristics, penetration depth and mass ratio of TiO2 particles in the concrerte specimens were measured after pressurezed fixation. Additionally, the removal efficiencies of nitrogen oxides (NOx) were evaluated using the NOx analyzing system. The penetration depth and surface mass ratio of TiO2 increased as increasing pressure and pressurization time. To achieve the efficiency of NOx removal more than 40%, a pressure 0.2 MPa and higher than 0.3 MPa with a pressurization time at least 10 seconds and 5 seconds were required, respectively. The finding demonstrated that the pressured TiO2 fixing method was effective, indicating that the suggested NOx removal technology is adequately appropriate to existing vertical concrete road constructions.

Quantum gravity effects in the infrared: a theoretical derivation of the low-energy fine structure constant and mass ratios of elementary particles

We have recently proposed a pre-quantum, pre-spacetime theory as a matrix-valued Lagrangian dynamics on an octonionic spacetime. This theory offers the prospect of unifying internal symmetries of the standard model with pre-gravitation. We explain why such a quantum gravitational dynamics is in principle essential even at energies much smaller than Planck scale. The dynamics can also predict the values of free parameters of the low-energy standard model: these parameters arising in the Lagrangian are related to the algebra of the octonions, which define the underlying non-commutative spacetime on which the dynamical degrees of freedom evolve. These free parameters are related to the exceptional Jordan algebra \(J_3(8)\), which describes the three fermion generations. We use the octonionic representation of fermions to compute the eigenvalues of the characteristic equation of this algebra and compare the resulting eigenvalues with known mass ratios for quarks and leptons. We show that the ratios of the eigenvalues correctly reproduce the [square root of the] known mass ratios. In conjunction with the trace dynamics Lagrangian, these eigenvalues also yield a theoretical derivation of the low-energy fine structure constant.

Unsteady two-temperature heat transport in mass-in-mass chains.

We investigate the unsteady heat (energy) transport in an infinite mass-in-mass chain with a given initial temperature profile. The chain consists of two sublattices: the β-Fermi-Pasta-Ulam-Tsingou (FPUT) chain and oscillators (of a different mass) connected to each FPUT particle. Initial conditions are such that initial kinetic temperatures of the FPUT particles and the oscillators are equal. Using the harmonic theory, we analytically describe evolution of these two temperatures in the ballistic regime. In particular, we derive a closed-form fundamental solution and solution for a sinusoidal initial temperature profile in the case when the oscillators are significantly lighter than the FPUT particles. The harmonic theory predicts that during the heat transfer the temperatures of sublattices are significantly different, while initially and finally (at large times) they are equal. This may look like an artifact of the harmonic approximation, but we show that it is not the case. Two distinct temperatures are also observed in the anharmonic case, even when the heat transport regime is no longer quasiballistic. We show that the value of the nonlinearity coefficient required to equalize the temperatures strongly depends on the particle mass ratio. If the oscillators are much lighter than the FPUT particles, then a fairly strong nonlinearity is required for the equalization.

Effects of inert dispersed particles on the propagation characteristics of a H2/CO/air detonation wave

In this study, numerical simulations are carried out by utilizing Eulerian-Lagrangian methods to investigate effects of the inert dispersed particles on the propagation characteristics of the H2/CO/air detonation wave. The results show that the inert particles reduce the temperature and velocity of both dispersed and continuous phases. The particles absorb heat from the gas, which alters the spatial location where the chemical equilibrium is achieved upstream of the detonation wave. Increasing the particle mass ratio reduces the detonation wave propagation velocity and hydrodynamic thickness, while it increases the velocity fluctuations at the detonation front. In contrary to this, enlarging the particle diameter leads to the augmentation of the detonation wave propagation velocity and hydrodynamic thickness, while it induces non-monotonic changes in the velocity fluctuations at the detonation front. The results show that the effects of the inert particles on the detonation wave are dominated by the relative scales of the particle relaxation time and the detonation propagation time.

Study on preparation and plugging effect of sawdust gel particle in fractured reservoir

In order to solve the problem of conventional preformed particle gel (PPG) with relatively high cost and poor strength and shearing resistance, a preformed sawdust gel particle (S-PPG) with a more superior performance than PPG was presented. A series of S-PPG with different mass ratio of sawdust particles to gelling liquid were prepared with free radical polymerization. It makes acrylic acid and acrylamide as polymerization monomers, N,N′-methylene bisacrylamide as crosslinking agent, ammonium persulfate as initiator and sawdust particles as enhancer. In general, enhancer content was less than 1%, but the content of enhancer in this work was increased by about 20–30%. The microscopic morphology, swelling property, viscoelasticity, yield stress, creep-recovery characteristics and shearing resistance of S-PPG in the formation water had been studied. The plugging behavior of S-PPG was studied using core flooding test. The results indicated that the swelling ratio of S-PPG (1:5) in the formation water was 8. S-PPG showed better viscoelasticity properties, shearing resistance and higher yield stresses than PPG. Moreover, the plugging rate of the plugging system with 3000 mg/L S-PPG (1:5) improved from 85.1% to 90.5% in fracture core compared with PPG. S-PPG (1:3) improved the plugging rate from 85.1% to 91.9%. The research results provide an alternative plugging material in fractured reservoirs.

The effect of particle size and mass ratio on the mechanical response of Al/PTFE/SiC composite with a 23 factorial design.

In order to study the effects of different SiC mass ratios, SiC particle sizes and Al particle sizes on the mechanical response of Al/PTFE/SiC, an experiment was conducted through the full 23 factorial design. The specimens were prepared by means of molding-vacuum sintering, while the mechanical response of the materials was measured through quasi-static compression. The regression models between failure stress, failure strain and various factors were established respectively and then verified through the analysis of variance (ANOVA) and residual analysis. Besides, the relationship between factors and response as well as that between factors were analyzed using response surface plots. According to the analytical results, the ultimate compressive strength of the material can be improved either by reducing the particle size of SiC and Al or increasing the mass ratio of SiC, while the ductility of the material can be enhanced by maintaining the interaction between SiC mass ratio and SiC particle size at high levels. The interaction effects are significant and can not be ignored, especially the interaction between SiC mass ratio and SiC particle size has an important impact on the mechanical responses, which shows that SiC has a greater influence than Al particles in the material system.

Failure Mechanism of Gas-Bearing Coal during Outburst and a New Method for Outburst Prediction.

Coal and gas outbursts are among the most serious disasters affecting the safety of coal mines. Gas is an important factor in these types of disasters. To analyze the characteristics of the damage caused by gas to the coal body during the sudden release of the gas process, a self-developed high-pressure gas release cause coal particle ejection experiment device was used to conduct gas release experiments under different conditions. The results show that at the moment of gas release, coal particles and gas are ejected at high speed, crushing coal particles into smaller particles. With the increase in gas pressure and gas adsorption performance, the crushing effect will increase. Also, the coal ejection strength (CES) will increase nonlinearly. By analyzing the mass ratio of ejected coal particles, based on the theory of crushing work and energy, we developed a new coal particle fragmentation index, which can be fitted linearly to CES. The index is based on the f value, which makes up for the limitations of the forecasting method, and can be used more flexibly to predict the coal sample crushing situation. Moreover, the fitting parameter values can more accurately describe the coal particle crushing grade.

Zein Colloidal Particles and Cellulose Nanocrystals Synergistic Stabilization of Pickering Emulsions for Delivery of β-Carotene.

In this study, we utilized different types of particles to stabilize β-carotene-loaded Pickering emulsions: spherical hydrophobic zein colloidal particles (ZCPs) (517.3 nm) and rod-shaped hydrophilic cellulose nanocrystals (CNCs) (115.2 nm). Either of the particles was incapable of stabilizing Pickering emulsions owing to their inappropriate wettability. When the mass ratio of ZCPs and CNCs was 1:4, the Pickering emulsion showed the best physical and photothermal stability. Compared to the ZCP-stabilized Pickering emulsion (9.29%), the retention rate of β-carotene in the Pickering emulsion costabilized by ZCPs and CNCs was increased to 60.23% after 28 days of storage at 55 °C. Confocal microscopy and cryoscanning electron microscopy confirmed that different types of particles could form a multilayered structure or induce the formation of an interparticle network. Furthermore, the complexation of ZCPs and CNCs delayed the lipolysis of the emulsion during in vitro digestion. The free fatty acid (FFA) release rate of Pickering emulsions in the small intestinal phase was reduced from 19.46 to 8.73%. Accordingly, the bioaccessibility of β-carotene in Pickering emulsions ranged from 9.14 to 27.25% through adjusting the mass ratio and addition sequence of distinct particles at the interface. The Pickering emulsion with the novel particle-particle complex interface was designed in foods and pharmaceuticals for purpose of enhanced stability, delayed lipolysis, or sustained nutrient release.

Turbulent flame propagation of polymethylmethacrylate particle clouds in an O2/N2 atmosphere

The combustion of solid particle clouds is extensively used in many engineering areas. However, experimental data describing the turbulent flame propagation behavior and the combustion mechanism of solid particle clouds have remained limited. In this work, the combustion of polymethylmethacrylate (PMMA) particle clouds was studied by employing a unique fan-stirred constant-volume chamber. For the quasi-monodispersed particle clouds, the flame propagation velocity increased with the increase in the turbulence intensity and the decrease in the quasi-monodispersed particle size. However, the particle concentration had little effect on the flame propagation velocity, which is unique in a turbulent flow field. The consistency of the results between the current study of PMMA particle clouds and the previous study for coal particle clouds showed that the heterogeneous combustion of char particles had little effect on the turbulent flame propagation velocity of the solid particle clouds. Further, two types of quasi-monodispersed particles were mixed to study how the interactions between small and large (polydispersed) particles affect turbulent flame propagation. We found that the turbulent flame propagation velocity had a nonlinear relationship with the mass ratio of small particles (J-shaped curve). The turbulent flame propagation velocity slightly increased with low mass ratio of small particles, while it sharply increased with high mass ratio of small particles. Increasing the turbulence intensity and decreasing the primary particle (large particle) size can advance the starting point of the sharp increase. These unique features were explained by a mechanism considering the polydispersed interparticle interaction proposed by the authors. In the combustion of turbulent polydispersed particle clouds, the particle–particle agglomeration and the agglomeration break-up in the turbulent flow field affect turbulent flame propagation. To the best of our knowledge, this is the first report on the fundamental spherical turbulent flame propagation phenomenon and the mechanism of solid particle cloud combustion considering the polydispersed interparticle interactions.

Optimization of Microalga Chlorella vulgaris Magnetic Harvesting.

Harvesting of microalgae is a crucial step in microalgae-based mass production of different high value-added products. In the present work, magnetic harvesting of Chlorella vulgaris was investigated using microwave-synthesized naked magnetite (Fe3O4) particles with an average crystallite diameter of 20 nm. Optimization of the most important parameters of the magnetic harvesting process, namely pH, mass ratio (mr) of magnetite particles to biomass (g/g), and agitation speed (rpm) of the C. vulgaris biomass–Fe3O4 particles mixture, was performed using the response surface methodology (RSM) statistical tool. Harvesting efficiencies higher than 99% were obtained for pH 3.0 and mixing speed greater or equal to 350 rpm. Recovery of magnetic particles via detachment was shown to be feasible and the recovery particles could be reused at least five times with high harvesting efficiency. Consequently, the described harvesting approach of C. vulgaris cells leads to an efficient, simple, and quick process, that does not impair the quality of the harvested biomass.

Ionic liquid electrospray behavior in a hybrid emitter electrospray thruster

Electrospray thrusters are most suitable for micro-nano satellites in advantage of small size, low power consumption and high specific impulse. However, conventional electrospray thrusters with capillary emitters operate at single mode with limited range of thrust. In order to expand range of thrust, novel electrospray thrusters with hybrid emitters which are capable of operating at dual-modes are recommended. Molecular dynamics simulation is used to study the behaviors of the novel electrospray thruster in this work, using EMIM-Tf2N as propellant. Electrospray behaviors for the capillary emitter and the hybrid emitter are compared at the same operating conditions, showing that droplets are more easily emitted from the capillary emitter. For the hybrid emitter, the externally-wetted emission mode is displayed at a low flow rate. Only ions are emitted from the hybrid emitter because of the stronger electric field and larger hydraulic impedance. Meanwhile the change in range of mean diameter and charge to mass ratio of particles are relatively small as compared to the capillary emitter. But the hybrid emitter transits into a capillary emission mode at a high flow rate. Furthermore, analysis of particle charge shows that if there exist particles with charge below the Rayleigh limit, droplets can be produced in electrospray beam.

Synthesis and Characterization of Polyaluminum Ferric Chloride (PAFC) Coagulant with Superior Turbidity Removal Capacity from K-feldspar/NaOH Extraction Residues

The aim of this work was to synthesize polyaluminum ferric chloride coagulant with significant coagulation performance employing K-feldspar/NaOH leaching residue as precursor. Potassium extraction from K-feldspar through sodium hydroxide calcination method is carried out at optimum, activation temperature, time, mass ratio of NaOH to K-feldspar ore in a muffle furnace followed by deionized water conventional leaching. The extraction residues are engaged in co-polymerization of aluminum and iron for the synthesis of polyaluminum ferric chloride (PAFC). The favorable conditions, concentration of hydrochloric acid, hydrochloric acid to residue ratio (v/m), temperature, time and pH are comprehensively investigated. Main process conditions for K extraction are: ore particle mass ratio of NaOH/ore 1.5:1, calcination temperature at 500 °C, and calcination duration of 2 hours, which all jointly yielded an extraction of 95% potassium, whereas polyaluminum ferric chloride (PAFC) synthesis favorable conditions are: HCl concentration of 5M, HCl/residue 5.5:1(v/m), time 2 hours, temperature 100 ℃ and pH 7. 99.8% turbidity elimination efficacy from an initial turbidity of 125 NTU kaolin suspension is obtained. The XRD study is implemented for raw ore, slag and leach residue and proved existing all possible structural changes occurred in extraction routes, additionally FTIR and ICP-MS employed in investigation of polyaluminum ferric chloride (PAFC) to reveal the functional group configuration within the elements of a coagulant and component analysis respectively.

Removal process and mechanism of lead in Zn-containing rotary hearth furnace dust

To deal with the removal of PbO2 during the purification process of the Zn-containing rotary hearth furnace (RHF) dust, this study adopts a choline chloride-urea (ChCl-urea) based deep eutectic solvent system and water-washed Zn-containing RHF dust as the main target of investigations, preparing ZnO nanoparticles using a Zn-induced PbO2 removal and thermal treatment of the precursor. The effects of the mass ratio of Zn particles and Zn dust (maked as Zn particles - Zn dust), reaction temperature, and reaction time on the removal of PbO2 were also investigated. The ZnO nanoparticles and the PbO2-removed products were characterized by X-ray diffractometry, X-ray fluorescence spectroscopy, scanning and transmission electron microscopy. The results showed that the optimal conditions for efficient removal of PbO2 included the reaction temperature of 80 °C, The Zn particles - Zn dust is 1.6, with a reaction time of 3 h. The final product had a ZnO content of 98.332% with a particle size distribution in the range of 10–100 nm with an average diameter of 39 nm, belonging to the Category-II ZnO nanoparticles. The PbO2 removal mechanism mainly involved the dissolving of PbO2 in ChCl-urea, forming [Pb(ClO·urea)2]2−, and the replacement reaction between Zn particles and [Pb(ClO·urea)2]2−, producing metallic Pb and [ZnClO·urea]−.

Inertia-induced nucleation-like motility-induced phase separation

Motility-induced phase separation (MIPS) is of great importance and has been extensively researched in overdamped systems, nevertheless, what impacts inertia will bring on kinetics of MIPS is lack of investigation. Here, we find a nucleation-like MIPS instead of spinodal decomposition in the overdamped case, i.e. not only the phase transition changes from continuous to discontinuous, but also the formation of clusters does not exhibit any coarsening regime. This remarkable kinetics of MIPS stems from a competition between activity-induced accumulation of particles and inertia-induced suppression of clustering process. More interestingly, the discontinuity of MIPS still exists even when the ratio of particle mass to the friction coefficient reduces to be very small such as 10−4. Our findings emphasize the importance of inertia induced kinetics of MIPS, and may open a new perspective on understanding the nature of MIPS in active systems.

Experimental study on pigmented coatings using two particle types with complementary optical features

One effective measure for building energy reduction is to pigment coatings on building exteriors. Conventionally, most coatings are designed using single particle types. Due to the limited particle optical features, these coatings usually perform well in one performance (e.g., thermal aspect) but poorly in another (e.g., aesthetic aspect). Thus, in practice they may not be able to meet the user-required performance in both aspects. Using particles with complementary optical features, such requirements may be fulfilled. To this end, this study experimentally investigates double-layered coatings using two particle types (i.e., CuO and TiO2) with complementary features. The performance of 24 coating samples is evaluated with selected total particle masses and mass ratios. Results show that in comparison with the conventionally designed coatings, the two proposed ones (i.e., TiO2 - CuO and CuO - TiO2 coatings) provide more performance alternatives under varied mass ratios; and they also present significant performance differences. For instance, when the TiO2 mass ratio increases, the total solar reflectance of the CuO-TiO2 coating increases slowly at first but quickly afterwards; while that of the TiO2-CuO coating increases quickly in the beginning but experiences a slow increase afterwards. It also illustrates that as the same required performance is met, the final choice of the two coatings is mainly determined by the initial costs of the utilized particles. Considering the optimal design in practice, the proposed coating is modelled. Validation results are shown at last.

Investigation of PolyVinyl Chloride Plastisol Tissue-Mimicking Phantoms for MR- and Ultrasound-Elastography

Objective: Realistic tissue-mimicking phantoms are essential for the development, the investigation and the calibration of medical imaging techniques and protocols. Because it requires taking both mechanical and imaging properties into account, the development of robust, calibrated phantoms is a major challenge in elastography. Soft polyvinyl chloride gels in a liquid plasticizer (plastisol or PVCP) have been proposed as soft tissue-mimicking phantoms (TMP) for elasticity imaging. PVCP phantoms are relatively low-cost and can be easily stored over long time periods without any specific requirements. In this work, the preparation of a PVCP gel phantom for both MR and ultrasound-elastography is proposed and its acoustic, NMR and mechanical properties are studied.Materials and methods: The acoustic and magnetic resonance imaging properties of PVCP are measured for different mass ratios between ultrasound speckle particles and PVCP solution, and between resin and plasticizer. The linear mechanical properties of plastisol samples are then investigated over time using not only indentation tests, but also MR and ultrasound-elastography clinical protocols. These properties are compared to typical values reported for biological soft tissues and to the values found in the literature for PVCP gels.Results and conclusions: After a period of two weeks, the mechanical properties of the plastisol samples measured with indentation testing are stable for at least the following 4 weeks (end of follow-up period 43 days after gelation-fusion). Neither the mechanical nor the NMR properties of plastisol gels were found to be affected by the addition of cellulose as acoustic speckle. Mechanical properties of the proposed gels were successfully characterized by clinical, commercially-available MR Elastography and sonoelastography protocols. PVCP with a mass ratio of ultrasound speckle particles of 0.6%–0.8% and a mass ratio between resin and plasticizer between 50 and 70% appears as a good TMP candidate that can be used with both MR and ultrasound-based elastography methods.