A simple atomization approach enables monolayer dispersion of nano graphenes in cementitious composites with excellent strength gains

Carbon nano additives(CNAs)are critical to achieving the unique properties of functionalized composites,however,controlling the dispersion of CNAs in material matrix is always a challenging task.In this study,a simple atomization approach was successfully developed to promote the dispersion efficiency of graphene nanoplatelets(GNPs)in cement composites.This atomization approach can be integrated with the direct,indirect and combined ultrasonic stirrings in a homemade automatic stirring-atomization device.Mechanical and microstructure tests were performed on hardened cement pastes blended with GNPs in different stirring and mixing approaches.Results show that the direct ultrasonic stirrings enabled more homogeneous dispersions of GNP particles with a smaller size for a longer duration.The atomized droplets with the mean size of~100μm largely mitigated GNPs’agglomerations.Monolayer GNPs were observed in the cement matrix with the strength gain by up to 54%,and the total porosity decrease by 21%in 0.3 wt%GNPs dosage.The greatly enhanced dispersion efficiency of GNPs in cement also raised the cement hydration.This work provides an effective and manpower saving technique toward dispersing CNAs in engineering materials with great industrialization prospects.

CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer

Kenics static mixers(KSM)are extensively used in industrial mixing-reaction processes by virtue of high mixing efficiency,low power homogenization and easy continuous production.Resolving liquid droplet size and its distribution and thus revealing the dispersion characteristics are of great significance for structural optimization and process intensification in the KSM.In this work,a computational fluid dynamics-population balance model(CFD-PBM)coupled method is employed to systematically investigate the effects of operating conditions and structural parameters of KSM on droplet size and its distribution,to further reveal the liquid-liquid dispersion characteristics.Results indicate that higher Reynolds numbers or higher dispersed phase volume fractions increase energy dissipation,reducing Sauter mean diameter(SMD)of dispersed phase droplets and with a shift in droplet size distribution(DSD)towards smaller size.Smaller aspect ratios,greater blade twist and assembly angles amplify shear rate,leading to smaller droplet size and a narrower DSD in the smaller range.The degree of impact exerted by the aspect ratio is notably greater.Notably,mixing elements with different spin enhance shear and stretching efficiency.Compared to the same spin,SMD becomes 3.7-5.8 times smaller in the smaller size range with a significantly narrower distribution.Taking into account the pressure drop and efficiency in a comprehensive manner,optimized structural parameters for the mixing element encompass an aspect ratio of 1-1.5,a blade twist angle of 180°,an assembly angle of 90°,and interlaced assembly of adjacent elements with different spin.This work provides vital theoretical underpinning and future reference for enhancing KSM performance.

Tunable dispersion relations manipulated by strain in skyrmion-based magnonic crystals

We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. Especially, the allowed bands and forbidden bands in dispersion relations shift to higher frequency with strain changing from compressive to tensile,while shifting to lower frequency with strain changing from tensile to compressive. We also confirm that the spin wave with specific frequency can pass the magnonic crystal or be blocked by tuning the strains. The result provides an advanced platform for studying the tunable skyrmion-based spin wave devices.

Effect of trigger system on experimental dispersion characteristics of active surface wave testing

A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data acquisition.The effect of the trigger system on the dispersion image of surface waves is empirically known to be negligible,however,theoretical explanation regarding the effect of the trigger system is insufficient.This study systematically examines the theory for surface wave dispersion analysis and proves that the effect of the trigger system on a dispersion image is negligible via a solid theoretical explanation.Subsequently,based on the new theoretical explanation,an alternative method that uses only the relative phase difference between sensors to extract dispersion characteristics with better conceptual clarity is proposed.Two active surface wave testing cases are considered to validate the theory and method.The results indicate that(1)an accurate trigger system is not necessary for surface wave data acquisition,and(2)it is unnecessary to assume that the impact point is the generation point of the surface waves for the experimental dispersion analysis.

A seismic elastic moduli module for the measurements of low-frequency wave dispersion and attenuation of fluid-saturated rocks under different pressures

Knowledge about the seismic elastic modulus dispersion,and associated attenuation,in fluid-saturated rocks is essential for better interpretation of seismic observations taken as part of hydrocarbon identification and time-lapse seismic surveillance of both conventional and unconventional reservoir and overburden performances.A Seismic Elastic Moduli Module has been developed,based on the forced-oscillations method,to experimentally investigate the frequency dependence of Young's modulus and Poisson's ratio,as well as the inferred attenuation,of cylindrical samples under different confining pressure conditions.Calibration with three standard samples showed that the measured elastic moduli were consistent with the published data,indicating that the new apparatus can operate reliably over a wide frequency range of f∈[1-2000,10^(6)]Hz.The Young's modulus and Poisson's ratio of the shale and the tight sandstone samples were measured under axial stress oscillations to assess the frequency-and pressure-dependent effects.Under dry condition,both samples appear to be nearly frequency independent,with weak pressure dependence for the shale and significant pressure dependence for the sandstone.In particular,it was found that the tight sandstone with complex pore microstructure exhibited apparent dispersion and attenuation under brine or glycerin saturation conditions,the levels of which were strongly influenced by the increased effective pressure.In addition,the measured Young's moduli results were compared with the theoretical predictions from a scaled poroelastic model with a reasonably good agreement,revealing that the combined fluid flow mechanisms at both mesoscopic and microscopic scales possibly responsible for the measured dispersion.

The Turbulent Schmidt Number for Transient Contaminant Dispersion in a Large Ventilated Room Using a Realizable k-εModel

Buildings with large open spaces in which chemicals are handled are often exposed to the risk of explosions.Computational fluid dynamics is a useful and convenient way to investigate contaminant dispersion in such large spaces.The turbulent Schmidt number(Sc_(t))concept has typically been used in this regard,and most studies have adopted a default value.We studied the concentration distribution for sulfur hexafluoride(SF_(6))assuming different emission rates and considering the effect of Sc_(t).Then we examined the same problem for a light gas by assuming hydrogen gas(H_(2))as the contaminant.When SF_(6) was considered as the contaminant gas,a variation in the emission rate completely changed the concentration distribution.When the emission rate was low,the gravitational effect did not take place.For both low and high emission rates,an increase in S_(ct) accelerated the transport rate of SF_(6).In contrast,for H_(2) as the contaminant gas,a larger S_(ct) could induce a decrease in the H_(2) transport rate.

P-and SV-wave dispersion and attenuation in saturated microcracked porous rock with aligned penny-shaped fractures

P-and SV-wave dispersion and attenuation have been extensively investigated in saturated poroelastic media with aligned fractures.However,there are few existing models that incorporate the multiple wave attenuation mechanisms from the microscopic scale to the macroscopic scale.Hence,in this work,we developed a unified model to incorporate the wave attenuation mechanisms at different scales,which includes the microscopic squirt flow between the microcracks and pores,the mesoscopic wave-induced fluid flow between fractures and background(FB-WIFF),and the macroscopic Biot's global flow and elastic scattering(ES)from the fractures.Using Tang's modified Biot's theory and the mixed-boundary conditions,we derived the exact frequency-dependent solutions of the scattering problem for a single penny-shaped fracture with oblique incident P-and SV-waves.We then developed theoretical models for a set of aligned fractures and randomly oriented fractures using the Foldy approximation.The results indicated that microcrack squirt flow considerably influences the dispersion and attenuation of P-and SV-wave velocities.The coupling effects of microcrack squirt flow with the FB-WIFF and ES of fractures cause much higher velocity dispersion and attenuation for P waves than for SV waves.Randomly oriented fractures substantially reduce the attenuation caused by the FB-WIFF and ES,particularly for the ES attenuation of SV waves.Through a comparison with existing models in the limiting cases and previous experimental measurements,we validated our model.

Particle residence time distribution and axial dispersion coefficient in a pressurized circulating fluidized bed by using multiphase particle-in-cell simulation

The particle residence time distribution(RTD)and axial dispersion coefficient are key parameters for the design and operation of a pressurized circulating fluidized bed(PCFB).In this study,the effects of pressure(0.1-0.6 MPa),fluidizing gas velocity(2-7 m·s^(-1)),and solid circulation rate(10-90 kg·m^(-2)·s^(-1))on particle RTD and axial dispersion coefficient in a PCFB are numerically investigated based on the multiphase particle-in-cell(MP-PIC)method.The details of the gas-solid flow behaviors of PCFB are revealed.Based on the gas-solid flow pattern,the particles tend to move more orderly under elevated pressures.With an increase in either fluidizing gas velocity or solid circulation rate,the mean residence time of particles decreases while the axial dispersion coefficient increases.With an increase in pressure,the core-annulus flow is strengthened,which leads to a wider shape of the particle RTD curve and a larger mean particle residence time.The back-mixing of particles increases with increasing pressure,resulting in an increase in the axial dispersion coefficient.

First results of CO_(2) dispersion interferometer on EAST tokamak

A dispersion interferometer(DI)has been installed and operates on the Experimental Advanced Superconducting Tokamak(EAST).This DI system utilizes a continuous-wave 9.3μm CO_(2)laser source to measure line-averaged electron densities accurately.In contrast to conventional interferometers,the DI does not require substantial vibration isolations or compensating systems to reduce the impact of vibrations in the optical path.It also employs a ratio of modulation amplitudes,ensuring it remains immune to the variations in detected intensities.Without a variation compensation system,the DI system on EAST reaches a density resolution of less than1.8×10^(-2)πrad and a temporal resolution of 20μs.The measurements made by the POlarimeterINTerferometer(POINT)system and the far-infrared hydrogen cyanide(HCN)interferometer are remarkably consistent with the DI’s results.The possibility of fringe jumps and the impact of refraction in high-density discharge can be significantly decreased using a shorter wavelength laser source.A rapid density change of 3×10^(19)m^(-3)during 0.15 s has been measured accurately in shot No.114755 of EAST.Additionally,the DI system demonstrates dependability and stability under 305 s long-pulse discharges in shot No.122054.

Nonlinear wave dispersion in monoatomic chains with lumped and distributed masses:discrete and continuum models

The main objective of this paper is to investigate the influence of inertia of nonlinear springs on the dispersion behavior of discrete monoatomic chains with lumped and distributed masses.The developed model can represent the wave propagation problem in a non-homogeneous material consisting of heavy inclusions embedded in a matrix.The inclusions are idealized by lumped masses,and the matrix between adjacent inclusions is modeled by a nonlinear spring with distributed masses.Additionally,the model is capable of depicting the wave propagation in bi-material bars,wherein the first material is represented by a rigid particle and the second one is represented by a nonlinear spring with distributed masses.The discrete model of the nonlinear monoatomic chain with lumped and distributed masses is first considered,and a closed-form expression of the dispersion relation is obtained by the second-order Lindstedt-Poincare method(LPM).Next,a continuum model for the nonlinear monoatomic chain is derived directly from its discrete lattice model by a suitable continualization technique.The subsequent use of the second-order method of multiple scales(MMS)facilitates the derivation of the corresponding nonlinear dispersion relation in a closed form.The novelties of the present study consist of(i)considering the inertia of nonlinear springs on the dispersion behavior of the discrete mass-spring chains;(ii)developing the second-order LPM for the wave propagation in the discrete chains;and(iii)deriving a continuum model for the nonlinear monoatomic chains with lumped and distributed masses.Finally,a parametric study is conducted to examine the effects of the design parameters and the distributed spring mass on the nonlinear dispersion relations and phase velocities obtained from both the discrete and continuum models.These parameters include the ratio of the spring mass to the lumped mass,the nonlinear stiffness coefficient of the spring,and the wave amplitude.

Treatment of Coronary Heart Disease from the Perspective of Liver Controlling Dispersion

The liver is in charge of distributing and regulating the movement of qi throughout the whole body,coordinating the transportation and transformation of the internal organs in the middle part of the body,promoting the biochemical circulation of qi,blood,and body fluids,and regulating emotions.Liver dysfunction can disrupt the transportation and transformation of qi,blood,and body fluids,causing phlegm turbidity,blood stasis,and other unwanted symptoms.Poor regulation of emotion further aggravates the accumulation of pathological substances,resulting in the obstruction of heart vessels,and ultimately coronary heart disease(CHD).Through regulating lipid metabolism,inflammatory reaction,vasoactive substances,platelet function,neuroendocrine,and other factors,liver controlling dispersing qi plays a comprehensive role in the prognosis of atherosclerosis,the primary cause of CHD.Therefore,it is recommended to treat CHD from the perspective of liver-controlling dispersion.

Sensitivity of seismic attenuation and dispersion to dynamic elastic interactions of connected fractures: Quasi-static finite element modeling study

Prediction of seismic attenuation and dispersion that are inherently sensitive to hydraulic and elastic properties of the medium of interest in the presence of mesoscopic fractures and pores,is of great interest in the characterization of fractured formations.This has been very difficult,however,considering that stress interactions between fractures and pores,related to their spatial distributions,tend to play a crucial role on affecting overall dynamic elastic properties that are largely unexplored.We thus choose to quantitatively investigate frequency-dependent P-wave characteristics in fractured porous rocks at the scale of a representative sample using a numerical scale-up procedure via performing finite element modelling.Based on 2-D numerical quasi-static experiments,effects of fracture and fluid properties on energy dissipation in response to wave-induced fluid flow at the mesoscopic scale are quantified via solving Biot's equations of consolidation.We show that numerical results are sensitive to some key characteristics of probed synthetic rocks containing unconnected and connected fractures,demonstrating that connectivity,aperture and inclination of fractures as well as fracture infills exhibit strong impacts on the two manifestations of WIFF mechanisms in the connected scenario,and on resulting total wave attenuation and phase velocity.This,in turn,illustrates the importance of these two WIFF mechanisms in fractured rocks and thus,a deeper understanding of them may eventually allow for a better characterization of fracture systems using seismic methods.Moreover,this presented work combines rock physics predictions with seismic numerical simulations in frequency domain to illustrate the sensitivity of seismic signatures on the monitoring of an idealized geologic CO_(2) sequestration in fractured reservoirs.The simulation demonstrates that these two WIFF mechanisms can strongly modify seismic records and hence,indicating that incorporating the two energy dissipation mechanisms in the geophysical interpretation can potentially improving the monitoring and surveying of fluid variations in fractured formations.

Experimental study on the dispersion behavior of a microemulsion collector and its mechanism for enhancing low-rank coal flotation

As the poor dispersion of oily collectors and the inferior hydrophobicity of the mineral surface, the lowrank coal has an unsatisfactory flotation performance when using traditional collectors. In this paper, an ionic liquid microemulsion was used as a collector to enhance its floatability. Flotation test results demonstrated the microemulsion collector exhibited a superior collecting ability. A satisfactory separation performance of 78.66% combustible material recovery was obtained with the microemulsion collector consumption of 6 kg/t, which was equivalent to the flotation performance of diesel at a dosage of25 kg/t. The dispersion behavior of the microemulsion collector was investigated using the CryogenicTransmission Electron Microscopy. The interaction mechanism of the microemulsion collector on enhancing the low-rank coal flotation was elucidated through the Zeta potential and contact angle measurements, the Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis.The microemulsion collector exhibited superior dispersibility, which was dispersed into positively charged oil droplets with an average size of 160.21 nm in the pulp. Furthermore, the nano-oil droplets could be more efficiently adsorbed on the low-rank coal surface through electrostatic attraction, resulting in the improvement of its hydrophobicity. Thus, the microemulsion collector shows great application potential in improving the flotation performance of low-rank coal.

Analysis of particle dispersion in a turbulent flow considering particle rotation

Non-spherical particles exist widely in natural and industrial fluid systems and the motions of nonspherical particles are significantly different from that of spherical particles.In this paper,a simplified model of non-spherical particles considering particle drag correction,lift,and rotation was established.Based on the Eulerian-Lagrangian simulation,the dispersion characteristics of spherical and nonspherical particles with different Stokes numbers in a high-speed turbulent jet were analyzed and compared considering the effect of particle rotation.The results show that,the differences in particle dispersion and radial velocity fluctuation between non-spherical particles and spherical particles in the jet are significant,especially when Stokes number is large.Moreover,the effects of different type of forces on the dispersion of non-spherical particles and spherical particles were compared in detail,which revealed that the change of the Magnus force caused by the increase in the angular velocity of non-spherical particles plays a dominant role in the differences of particle dispersion.

Advances in the development of amorphous solid dispersions:The role of polymeric carriers

Amorphous solid dispersion(ASD)is one of the most effective approaches for delivering poorly soluble drugs.In ASDs,polymeric materials serve as the carriers in which the drugs are dispersed at the molecular level.To prepare the solid dispersions,there are many polymers with various physicochemical and thermochemical characteristics available for use in ASD formulations.Polymer selection is of great importance because it influences the stability,solubility and dissolution rates,manufacturing process,and bioavailability of the ASD.This review article provides a comprehensive overview of ASDs from the perspectives of physicochemical characteristics of polymers,formulation designs and preparation methods.Furthermore,considerations of safety and regulatory requirements along with the studies recommended for characterizing and evaluating polymeric carriers are briefly discussed.

Effect of Free-fall Nozzle Channel Dispersion Angle on TC4 Discontinuous Droplets Pre-breakup in EIGA

The effect of the inlet gas pressure,supplementary gas pressure and nozzle channel dispersion angle on the pre-breakup behavior of Ti-6Al-4V(TC4)discontinuous droplets during EIGA was investigated by combining numerical simulation with experiments.The results show that the axial velocity at the recirculation zone before the stagnation location was first increased and decreased then increased significantly after the peak value,while the pressure of the recirculation zone increased with the increase in inlet pressure.With the supplementary pressure increasing,the velocity magnitude and range of the recirculation zone gradually decreased.As the dispersion angle of the nozzle channel increased,the pre-breakup efficiency of droplets gradually decreased,but the adhesion phenomenon of droplets on the inner wall surface of the nozzle channel(IWSNC)gradually weakened.Under the inlet pressure of 4 MPa,a supplementary pressure of 0.05 MPa,and the dispersion angle of 15°,the uniform and spherical TC4 powders with diameter of 70μm were prepared,which was consistent with the simulation results.The optimized process parameters is a balance between the size of the pre-atomized particles and the back-spraying and bonding phenomenons of droplets.

Study on two-phase cloud dispersion from liquefied CO_(2) release

The knowledge of two-phase cloud dispersion mechanism from HLG(hazardous liquefied gas) release is the prerequisite for accurate assessment and precise rescue of such accidents. In this paper, an experiment of two-phase cloud dispersion from liquefied CO_(2) hole release is performed. The source terms, such as vapour mass fraction, release velocity and mean droplet diameter, are calculated based on thermodynamic theory. Taking phase transition of CO_(2) droplets to gas into account, CFD(computational fluid dynamics) model for two-phase cloud dispersion is established. The predicted cloud temperatures at the downstream agree well with the experimental data, with the maximum relative error of 5.8% and average relative error of 2.3%. The consequence distances in the downstream direction and in the crosswise direction calculated through two-phase model are larger than those through single-phase model,with the relative differences of 57.8% and 53.6% respectively. CO_(2) concentration calculated by twophase model is smaller in the vicinity of release hole, and larger beyond 0.135 m downstream. A smaller leakage rate results in a lower CO_(2) concentration and a higher cloud temperature.

Can the Prediction of Intrauterine Insemination Results by Used Aniline Blue Stain (ABS) and Sperm Chromatin Dispersion (SCD) Levels?

Introduction: This study aimed to perform routine seminal fluid analysis, sperm DNA fragmentation, and sperm function tests at the chromatin maturation level and evaluate pregnancy in the patients passing intrauterine insemination before starting Intrauterine Insemination (IUI) method. Materials and Methods: In this prospective study, 111 couples who underwent Intrauterine Insemination (IUI) in unexplained infertility patients were admitted to Al-Farah IVF and assisted reproductive center in Baghdad, Iraq between November 2020 and February 2021 were evaluated. Semen fluid analysis was performed based on (WHO 4th) guiding rules. In addition, Sperm Chromatin Dispersion (halo test) and sperm maturation were performed with Aniline Blue Stain (ABS). Results: Sperm Chromatin Dispersion (SCD) groups were compared in terms of pregnancy outcome;the positive pregnancy rate was found to be above in the normal SCD groups (p = 0.0005). In addition, Aniline Blue Stain (ABS) groups were compared in the terms of pregnancy outcome;the positive pregnancy rate was found to be higher in the normal ABS group (p = 0.017). Conclusion: Our study showed that the use of DNA fragmentation (SCD) and sperm maturation tests (ABS) together with routine semen analysis in intrauterine insemination cases will make a significant contribution to the prediction of Intrauterine Insemination (IUI) increased results. So, these results indicate a defect in the effect of DNA fragmentation on the outcome of intrauterine insemination.

Preliminary estimation of rock-fall lateral dispersion by laboratory test

Lateral dispersion significantly directs the assessment of rockfall hazard and design of countermeasures. In the present study, the dependence of lateral dispersion on different controlling factors has been systematically evaluated by performing laboratory tests using three different rock block types, namely circular block, and two types of elliptical block. The three types of rock block are released onto an inclined surface with the identical initial status. Parallel, anti-parallel, and oblique impact tests set at slope angles of 22.5° and 45°are conducted to study the block-slope interaction of rockfall. Lateral dispersion of rockfall is less influenced by the block shape for the oblique impact, while the post-impact behaviors are greatly affected by the block shape. The key factors influencing the deviation of the post-impact trajectory direction are the slope angle (θ) and direction difference (Δφ). An empirical model is then developed to characterize the deviation distribution of lateral dispersion by 5th and 95th percentile values with the inclusion of the two key factors. Linear function can be used to describe the 5th percentile boundary, while hyperbolic function is good for the 95th percentile boundary, which need to be validated by field tests in the subsequent research.

Effect of Polyisobutylene Succinimide on the Physical Stability of an Environmentally Friendly Pesticide Oil Dispersion Suspension

Oil dispersible suspension concentrates are safe,green,and environmentally friendly formulations.Problems such as layering,pasting,and bottoming are frequently encountered during the production,storage,and transportation process.Polyisobutylene succinimide functions as a dispersant and exhibits great potential to improve the physical stability of the oil dispersible suspension concentrate.From a microscopic perspective,the sorption characteristics of the polyisobutylene succinimide dispersant T151 on penoxsulam particle surfaces were comprehensively evaluated with XPS,FTIR,and SEM.The T151 adsorption procedure complied with a pseudo-second-order kinetic adsorption model,and it was a kind of physical sorption with an Ea of 22.57 kJ⋅mol^(−1).The T151 sorption model was consistent with the Langmuir isotherm.The adsorption process was spontaneous and followed by an entropy increase.TheΔH^(θ)of dispersant T151 on the surface of penoxsulam particles was 31.59 kJ⋅mol^(−1).The adsorption procedure was endothermic,and the primary force was hydrogen bonding.The XPS results showed that the F and S electronic peaks at the penoxsulam interface decreased,and that the C electronic peak increased significantly after the adsorption of dispersant T151,indicating the adsorption on the surface of penoxsulam particles.The results of this study provide a vital theoretical basis for the application of polyisobutylene succinimide dispersants in oil dispersible suspension systems.