Mixed Particles Research Articles

The effect of surface micropatterns on the flow in a lab-on-a-chip with nanowires

Nanowire-anchored microfluidic devices have opened new opportunities for in situ extractions of microRNAs (miRNAs) from extracellular vesicles (EVs) in body fluids. The diagnosis precision of the devices largely depends on the EV extraction efficiency. In this article, we demonstrated a maskless photolithography process with direct covalent bonding for fabricating microfluidic devices embedded with zinc oxide (ZnO) nanowires as a lab-on-a-chip for extracting urinary EVs. The chips were designed with two distinct surface micropatterns: herringbone arrow and cylindrical micropillars. We investigated the effect of surface pattern, groove height-to-width ratio and nanowire orientation on the microflow. The computational fluid dynamics (CFD) simulations suggested that the herringbone pattern is more effective in reducing the flow velocity thus prolonging the mixing time. Furthermore, a critical inter-pattern groove width-to-height ratio was shown to induce circulating currents in the concave regions of the micropatterns. This design shows potential in increasing the fluid residency time within the device, thus increasing the probability of trapping EVs in circulating flows. In addition, the randomly oriented nanowires resulted in a significant amount of near-wall vorticity. Overall, the combination of a surface micropattern and the randomness of nanowire orientation suggests enhanced particulate mixing in the wall-adjacent zones and the potential to improve the EV extraction efficiency.

Axial segregation characteristics and size-induced flow behavior of particles in a novel rotary drum with curved sidewalls

Particle mixing and segregation are common phenomena in rotary drums, which are challenging to be controlled and driven artificially in powder technology. In this work, the discrete element method (DEM) was applied to construct the novel rotary drum composed of different shaped curved sidewalls. By varying the operation parameters of particle and sidewall shapes as well as the length-to-diameter (L/D) ratio of drums, the axial mixing and segregation processes of binary size-induced particles were investigated. The results show that the axial flow velocity of the particle mixtures is noticeably weakened once the particle angularity increases, making the non-spherical particles to mix better in rotary drums compared to the spherical particles. Besides, in the short drums with size-induced spherical particles, the axial segregation characteristics are significantly enhanced by the convex sidewalls while suppressed by the concave sidewalls. However, for size-induced non-spherical particles, the axial segregation structure can be present in rotary drums with plane and concave sidewalls while not in drums with convex sidewalls. Moreover, the axial segregation band structure of spherical particles eventually increases proportionally with the increased drum L/D ratios. In contrast, the non-spherical particles cannot form obvious multi-proportional segregation bands.

Comparative CFD-DEM study of flow regimes in spout-fluid beds

Spout-fluid beds are unique systems that require thorough study prior to their industrial application. In this study, the hydrodynamics of spout-fluid beds were investigated using 3D computational fluid dynamics coupled with discrete element method (CFD-DEM). Three flow regimes, including jet-in-fluidized bed, spouting-with-aeration, and intermediate/spout-fluidization were studied, and the particle mixing was quantified in these regimes using the Lacey mixing index. The results showed that both axial and lateral mixing rates are better in jet-in-fluidized bed and the spouting-with-aeration flow regimes, with the axial mixing being superior to the lateral in all flow regimes. Examining the diffusivity coefficient revealed that mixing in the jet-in-fluidized bed flow regime is better due to the formation and eruption of bubbles in the annulus. Additionally, the granular temperature was analyzed in all flow regimes, and higher particle velocity fluctuations were observed in the spouting-with-aeration and the jet-in-fluidized bed flow regimes due to the higher spout gas velocity and formation of bubbles in the annulus. This study provides valuable insights into the hydrodynamics of spout-fluid beds in different flow regimes, which can aid in the design and optimization of spout-fluid bed reactors for various industrial applications.

Uniform thickness in the process of ore-mixed characteristics of particles passing through experimental research

The nature of fine particulate matter is caused by the deterioration of the lean ore loss index and the important influence factors of a mine disaster accident. In this paper, fine moraine particles and coarse-grained ore from the Pulang Copper Mine are studied. The flow of fine particles in mixed particles under the condition of uniform ore drawing was studied by using the laboratory 3D physical model test method. This experiment explored the flow of hybrid particles in the system and characteristics of the particle size of fine particles passing through, and suggested a transit index to quantify the draining effect of fine particles. The experimental results show the following: ①Hybrid particles in the flow system of fine particulate matter under their own gravity use mixed ore particles flow in the process of formation of the pore to implement down through sports. ②The fine particles with the particle sizes of 2.5–1.25 mm, 1.25–0.63 mm, 0.63–0.315 mm, and 0.315–0.16 mm all have the flow-through characteristics, and the smaller the particle size, the more significant the flow-through degree. ③The cumulative ore drawing height of fine particles with different particle sizes increases, while the permeability index of the appropriate discharge decreases. ④The relative motion of coarse and fine particles is the internal control factor that leads to the flow of fine particles. The more significant the relative motion of coarse and finely mixed particles is, the more pores are randomly generated in the particle flow system and the larger the pores are, resulting in the more obvious fine particle flow effect. This study provides some theoretical reference value for revealing the flow-through characteristics of the fine particulate matter in the mixed particle flow system. At the same time, it has practical engineering significance for ore lean loss index control and mine disaster accident prevention and control in caving mining.

Effects of grinding aids on the grinding kinetics and surface morphological characterization of quartz

The kinetic parameters of a grinding process can be used to study the variations in particle size reductions and grinding efficiencies. Appropriate grinding aids usually change the surfaces of a material and the properties of the pulp, thus improving the grinding efficiency. In this paper, pure quartz samples with mixed particle sizes and single particle sizes were selected as the raw materials. The effects of different sodium tripolyphosphate (STPP) and citric acid (CA) dosages on the dynamic parameters k, selection function S1 and breakage function B for quartz grinding were studied. The results showed that the STPP and CA enhanced the grinding process of the quartz. In other words, the parameter k, the selection function S1 and the breakage function B were all increased to varying degrees. The results of SEM, BET and contact angle measurements showed that the surfaces of the quartz particles became rounder, the specific surface area and average pore size increased, and the surface hydrophilicity increased. As a result, the grindability of the quartz increased, and the grinding kinetic parameters changed. Finally, the results showed that the improvements in the quartz grindability were consistent with the influence of grinding aids on the kinetic parameter k, selection function S1 and breakage function Bi,1.

Rapid particle concentration for immunofluorescence enhancement by a surface acoustic wave microchip

At the initial stages of pathogenesis, biomarkers are generated in an insignificant concentration. Hence, the rapid screening for these low-abundance indicators is immensely critical for early disease diagnosis. Enhancement of the immunofluorescence signal emitted from little concentrated biomarkers can aid their detection among other molecules in complex body fluids. Here, we developed an advanced bead-based immunosensing technique combining surface acoustic wave (SAW) for a rapid and sensitive on-chip detection of the diabetic retinopathy biomarker lipocalin 1. As a result, the implementation of the SAW microchip-enabled particle mixing, separation, and concentration in the droplet delivered a 3.6-fold enhanced immunofluorescence signal within 5 s. The integration of fluorescent signal enhancement by SAW, along with the high sensitivity of the immunoassay, featured a limit of detection of 40 pg/mL in 3 min with a sample volume as low as 4 µL. A simple addition of cover glass on the SAW microchip allowed the immuno-sensing process to be completed without any direct sample contact with the interdigital transducer, minimizing the risk of cross-contamination and damage to the chip due to frequent washing. This study demonstrated the potential of the developed SAW device and insights into its utility as an early diagnostic tool.

Enhanced injectability of aqueous β-tricalcium phosphate suspensions through PAA incorporation, gelling and preshearing

The major shortcoming of aqueous calcium phosphate suspensions used in biomedical applications is their unstable flow during delivery by mechanical means. In this study, microstructural changes and the resulting flow instabilities of aqueous β-TCP suspensions are demonstrated under both pressure-induced and drag-induced flow regimes and then remedied with the incorporation and subsequent gelling and preshearing of Carbopol 940, a biocompatible hydrogel. Mixing and dispersion of calcium phosphate particles into the hydrogel matrix was not efficient under simple agitation conditions. Swelling of the polymer chains was induced at approximately pH = 9.0 by water and particle intrusion within the opened-up coil structure due to deprotonation of the carboxylic acid groups by NaOH. As a result the composite material underwent a rapid viscoplastic transition into a doughy state which was not amenable to further processing without preshearing. Manual kneading converted the material into viscous state and enhanced the flow behavior significantly. Preshearing and probing the microstructure by mechanical spectrometer revealed multiple microstructural mechanisms responsible for the observed stable flow behavior, including improved dispersion of the particles, attrition of the polymeric network into microgel domains, enhanced adhesion and lubrication between the solid and liquid phase, crosslinking of the polymeric network. The net effect of these probable mechanisms was stiffening of the composite matrix, mobilization of solid particles and a marked enhancement in the stability of pressure-induced flow. The resistance of the material to liquid phase migration and its ability to undergo wall-slip and relax under stress were confirmed by simultaneous capillary rheometry and thermogravimetric analyses. The processing method enables improvements in the delivery of this composite material for injection and direct ink writing of scaffolds.

Effects of vibration conditions, spatial confinement and friction on mixing and segregation characteristics of mixed pebble beds for CFETR WCCB blanket

This paper presents the study of the dynamic characteristics of confined mixed pebble beds with different friction under different vibration conditions using the discrete element method. The λ segregation index is used to quantify the degree of particle mixing or segregation. The percolation, convection and diffusion mechanisms are responsible for the segregation patterns of the mixed pebble. The results show the degree of segregation can be suppressed by decreasing the vibration acceleration or free space height below a threshold. Further simulation reveals the threshold of vibration acceleration or free space height both are related to the bed height increment which determines the strength of the percolation mechanism. In addition, the strength of percolation and convection becomes weaker by decreasing the friction of particles and walls, which makes the pebbled bed remains in a mixed state under vibration. These findings are significant to clarify the main factors behind the three segregation mechanisms and hence provide solutions to retaining the mixed state of the Li2TiO3&Be12Ti mixed pebble bed.

Parameterization of Multi-Angle Shaker Based on PSO-BP Neural Network

It was possible to conduct a study on the shape and parameterization of the vibrating screen so as to explore the relationship between detailed vibrating screen motion parameters and particle group distribution under different screen surface states. The motion characteristics of particle groups in various scenes were investigated, screening performance of vibrating screen with complex parameters was studied, interaction between motion parameters of screen surface and motion of material groups in multi-component mixed particle groups was analyzed, segregation distribution law of multi-component mixed material groups was revealed, and this study presents simulation findings based on the discrete element program EDEM. The ensemble learning approach was used to examine the optimized model screen. It was revealed that the screen’s amplitude, vibration frequency, vibration direction angle, swing frequency, swing angle, and change rate of screen surface inclination all had a major impact on its performance. As a result, the vibrating screen’s running state was described by various parameter combinations, and the trend changes of several factors that affected the performance of the screen were examined. The investigation revealed that the particle swarm optimization backpropagation (PSO-BP) neural network model outperformed the backpropagation (BP) neural network model alone in terms of prediction. It had lower root mean square error (RMSE), mean square relative error (MSRE), mean absolute error (MAE), and mean absolute relative error (MARE) than the BP neural network model, but a larger R2. This model’s greatest absolute error was 0.0772, and its maximum relative error was 0.0241. The regression coefficient R value of 0.9859, which displayed the model’s strong performance and high prediction accuracy, showed that the PSO-BP model was feasible and helpful for parameter optimization design of vibrating screens.

Widespread Pb contamination in urban backyard soils for >100 years identified in soil cores constrained by 210Pb and 137Cs

Contaminated soil in urban residential areas is often overlooked as a source of childhood exposure to toxic levels of lead (Pb). We document mean Pb concentrations of 1200 ± 1000 mg/kg, three times the now outdated EPA soil hazard standard of 400 mg/kg, for 370 surface soils collected from 76 homes in the boroughs of Brooklyn and Manhattan of New York City. The mean Pb content of 250 ± 290 mg/kg Pb for 571 surface soils collected from tree pits and public parks was much lower. A subset of 22 surface samples analyzed by EPA Method 1340 extracted 86 ± 21 % (±1SD) of total soil Pb, indicating that it the Pb was highly bioavailable. To investigate the origin of backyard contamination, 49 cores were collected to an average depth of 30 cm from a subset of 27 homes. Twelve soil cores were analyzed for 210Pb and 137Cs to constrain processes that impact contaminant distribution and inventories (particle focusing, soil accumulation, loss, and mixing). Concentrations of Pb declined with depth in 60 % of the cores but usually did not reach background. Mean uncorrected Pb inventories of 340 ± 210 g/m2 Pb (mean ± 1SD, n = 12) were more than five times higher than the radionuclide corrected inventory of 57 g/m2 from Central Park soil cores. Average inventories of 210Pbxs (3.5 ± 0.9 kBq/m2) and 137Cs (0.9 ± 0.6 kBq/m2) corresponded to 71 ± 19 % and 50 ± 30 % of the predicted atmospheric inventories. Elevated Pb concentrations were found both in the fine (<1 mm) and coarse (>1 mm) fractions, the latter suggesting a local non-atmospheric source. This was confirmed by individual grains containing up to 6 % Pb and visible pieces of coal, bricks, and ash. Regardless of the source of contamination in backyard soils, systematic testing is needed to identify contaminated areas and reduce child exposure.

Investigation of particle size impact on dense particulate flows in a vertical pipe

In this work, a semi-resolved computational fluid dynamics-discrete element method is employed to study the effects of fluid–particle and particle–particle/wall interactions on particle mixing and segregation behaviors and particle dynamics with different particle sizes in a vertical pipe. There are two species of particles with the same density in the vertical pipe: d1 = 10 (species 1) and d2 = 2–7 mm (species 2), and species 2 contains both fine and coarse particles. The Stokes number Stp is introduced to characterize the effects of different particle sizes on particle dynamics. First, the particle mixing and segregation behaviors with different size ratios are qualitatively analyzed. By comparing with smaller size ratios, obvious granular plugs and stronger contact force networks occur at larger size ratios. Second, after the segregation of species 1 and 2, the differences in dynamic characteristics between fine and coarse particles are explored. The normalized autocorrelation length scale, which is the ratio of propagation length of particle velocity fluctuations and particle diameter, is significantly different from fine to coarse particles. One notable feature is that two different flow regimes are found through the radial distribution function. Furthermore, the hydrodynamic stress and collision stress are defined to study the mechanism for the differences between fine and coarse particles. The results imply that the reason for the differences is that the collision effects go beyond the hydrodynamic effects with the increase in the Stokes number.

Influences of nano-green lubricants in the friction-stir process of TiAlN coated alloys

The present article investigates the effect of the friction stir process on the ultimate tensile strength and microhardness of an TiN-coated AA 6061 alloy using a green nanolubricant to reduce wear and minimise environmental impacts. In this study, a one-variable-at-a-time approach is utilized to conduct the experiment using aluminium oxide nanoparticles mixed with sunflower oil as a green lubricant. The matrix material used is AA6061 alloy, and TiN particles are used as reinforcement to form the aluminium surface composite (AA6061/TiN) through the friction stir process. The input parameters considered to improve the tensile strength and microhardness of the surface composites are axial thrust, tool speed, table travel speed, and percentage of TiN. The results indicate that by increasing the tool speed, table speed, axial thrust, and mixed TiN particle percentages, the maximum tensile strength and microhardness of the aluminium composites can be achieved. However, the lowest response values are obtained at their lowest values. To summarize, the findings suggest that the friction stir process can effectively enhance the mechanical properties of the aluminium composites by optimizing the processing parameters.

Study on Preparation of Homogenized Highly Dispersible AlON Powder

The quality of Aluminum oxynitride (AlON) powder is the main factor affecting the properties of ceramics. To accurately control the nitrogen AlON content and improve the dispersion degree of powder, AlON powder was prepared from γ-Al2O3 and activated carbon powder by carbothermic reduction and nitridation. The uniformity of distribution of raw materials and the dimension and microstructure of AlON powder was controlled by changing the time and rotation rate of the ball milling process. The influences of ball milling process parameters on the microstructure and distribution uniformity of Al2O3/C mixed powder, microstructure, and particle size of AlON powder were studied. The results show that powder agglomeration was effectively reduced, and the uniformity of raw material distribution was increased by controlling the time and rotation rate of the ball milling process. The Al2O3/C mixed powder has good particle size and uniform distribution with roller ball milling for 24 h. After holding the powder at 1700 °C for 60 min, the homogenized AlON powder was obtained, and the residual carbon content was about 0.04 wt%. When the time of planetary ball milling at 250 rpm was 16 h, highly dispersible AlON powder was obtained.

Assessment of Air pollution in Benghazi City during February and March periods using Airvisual Outdoor Monitor

Particulate matter is a major indicator of the level of air pollution. The ratio of fine and coarse particles and particle type determine the ability of atmospheric processes and affect human health. The aim of this work is to assess the spatiotemporal variation of particulates (PM1, PM2.5, and PM10) during the monitoring period from February 2023 to March 2023 and to assess the correlations between pollutants and the impact of meteorological factors. The results showed the main average air quality index (AQI) in the February period was about 138 μg/m3, which reflected the air quality is unhealthy for sensitive groups, while the main average AQI in the March period was about 89 μg/m3, which reflected the air quality is moderate. Based on PM2.5/PM10 ratios in February the mixed particles and anthropogenic source are more common in the atmosphere and PM2.5/ PM10 ratios in March period the mixed particles and natural sources are more common in the atmosphere in Benghazi city. The February period has more pollutants than the March period due to more than type of pollution. The bivariate polar plots of temperature AQI, PM1/PM2.5, and PM2.5/PM10 were negatively correlated with temperature while positively correlated with wind speed. SE directions of wind have a major impact on increasing PM and natural pollution type concentrations in Benghazi city.

Cross-scale study of the evolution of interparticle contact behavior using smart aggregate

Structural internal health monitoring is a critical step in the construction and maintenance of pavement, the current pavement health monitoring methods need to be improved in terms of accuracy, timeliness, and the understanding of the interaction mechanism between the sensors and surrounding media. In this paper, compaction and splitting tests of cement stabilized macadams (CSM) are conducted using the wireless embedded sensors-Smart aggregate (SA) and a new evolution indicator Sv is proposed to describe the generation and propagation of damage within the material. In addition, spherical and mixed particle assemblies are modeled using the discrete element method to investigate the variation of microscopic contact parameters between the SA and the surrounding granular medium under loading. The results show that SA sensor is an effective tool to monitor the inter-particle force and rotation changes within the mixture at meso-scale, and the fluctuation coefficient Sv can be used to more accurately characterize the evolution of inter-particle contact parameters. Moreover, there is a strong correlation between the SA readings and the microscopic contact parameters (e.g., coordination number, normal contact force), while the size and shape of particles in the medium can likewise significantly affect the monitoring results of SA sensors.

Electrochemical, Optical and Impedance Studies on Photoactive Assemblies Consists of Mixed TiO2-CdS Particles Occluded in Poly 2,2’ Bithiophene in Aqueous Acetate Electrolytes

Electrochemical, Optical and Impedance Studies on Photoactive Assemblies Consists of Mixed TiO2-CdS Particles Occluded in Poly 2,2’ Bithiophene in Aqueous Acetate Electrolytes

A pairwise mixing model with kernel constraint and its appraisal in transported PDF simulations of ethylene flames

Modeling micro-mixing remains a primary challenge for the transported probability density function (TPDF) method. In this study, the pairwise mixing with kernel constraint (KerM) model is proposed and evaluated in TPDF simulations of a turbulent non-premixed ethylene flame. The new model features controllable localness by selecting mixing particle pairs with a probability that depends on their distance in composition space, normalized by a characteristic kernel size. To evaluate the model in a controlled setting, TPDF simulations were carried out with the mean velocity, turbulent diffusivity and scalar mixing frequencies extracted from a direct numerical simulation (DNS) dataset. The predictions of the mean statistics and the conditional PDFs illustrate that the KerM model exhibits asymptotic behavior to the modified Curl (MC) and the Euclidean minimum spanning trees (EMST) model, respectively, depending on the kernel size. For the flame considered, results for KerM approach those for EMST when the kernel size is less than 0.01, while they approach those for MC when the kernel size is larger than 1.0. Given a kernel size of 0.1, KerM yields a notably better prediction of the overall combustion process than the conventional MC model. The predictions of the mean temperature and species mass fractions by KerM are similar to those by EMST, while KerM better predicts the conditional PDF of temperature than EMST that overdamps the conditional fluctuations. In addition, its complexity with the number of particles per cell is instead of O(Np2) for EMST. By incorporating different mixing timescales among species, the KerM-DD model better predicts the mean temperature field at the time instant close to local extinction than the KerM and EMST models. This work demonstrates that the KerM model, apart from being simple and robust in terms of implementation, features the advantages of being flexible in localness and being capable of incorporating differential diffusion.

Microwave heating of silicon carbide and polypropylene particles in a fluidized bed reactor

Microwave-assisted recycling of plastics has become an increasingly attractive technology. In this study, the effects of microwave power, fluidization velocity, particle size and mass ratio on heating performances of polypropylene (PP), silicon carbide (SiC), and the binary mixed (PP/SiC) particles in a microwave fluidized bed reactor were experimentally investigated. The maximum temperature of SiC particles was increased when the microwave power, particle size increased and fluidization velocity decreased. The maximum temperature of SiC particles was 965.7 °C in this study, whereas the maximum temperature of PP particles was only 113.5 °C, and the heating rate of SiC particles was about 7.8–77.2 times that of PP particles. For SiC/PP mixture particles, when the microwave power was 400 W, fluidizing velocity was 3.54 × 10−3 m/s, and the mass ratio of SiC-to-PP was 40:5, the temperature of the mixture particles increased to 600 °C rapidly and then fixed at 600 °C. However, when the fluidizing velocity was slow (1.18 × 10−3 m/s) or the mass ratio was changed (40:1 and 40:10), the temperature decreasing phenomenon appears during the microwave heating process of mixture particles.

Fabrication of heat-stable composite microparticles from egg and whey proteins and their application in emulsion stabilization

This study investigated the feasibility of egg and whey proteins (WPI-EGG) mixture in developing heat-stable O/W emulsions at high concentrations of proteins (10%). Different pHs of 3, 4, 5, 6, and 7 were applied to fabricate heat-stable protein particles. The composite microparticles of WPI-EGG were prepared by heating at 95 °C for 10 min, followed by homogenization under sonication. Moderate pHs of 4–6 were appropriate for aggregate formation and particles whose size varies from 215 to 1333 nm. According to the results, particles generated at pH 5 and 6 showed the viscosity less than 1000 cp due to spherical morphology contrast to the mix of linear and spherical particles fabricated at pH 4 exhibiting viscosity higher than 2000 cp. The particles were characterized with hydrogen bonds and hydrophobic interactions. The lowest surface hydrophobicity was observed for particles prepared at pH 5. Although the greatest denaturation enthalpy and temperature were observed for particles of pH 6, those obtained at pH 5 were capable to form heat-stable emulsions with appropriate viscosity following thermal pasteurization. The increase of disordered random coil structures in the particles (pH 6) was found as main reason of the increased thermal stability at pH 6.

The Potency of Cowpea Mosaic Virus Particles for Cancer In Situ Vaccination Is Unaffected by the Specific Encapsidated Viral RNA.

Plant virus nanoparticles can be used as drug carriers, imaging reagents, vaccine carriers, and immune adjuvants in the formulation of intratumoral in situ cancer vaccines. One example is the cowpea mosaic virus (CPMV), a nonenveloped virus with a bipartite positive-strand RNA genome with each RNA packaged separately into identical protein capsids. Based on differences in their densities, the components carrying RNA-1 (6 kb) denoted as the bottom (B) component or carrying RNA-2 (3.5 kb) denoted as the middle (M) component can be separated from each other and from a top (T) component, which is devoid of any RNA. Previous preclinical mouse studies and canine cancer trials used mixed populations of CPMV (containing B, M, and T components), so it is unclear whether the particle types differ in their efficacies. It is known that the CPMV RNA genome contributes to immunostimulation by activation of TLR7. To determine whether the two RNA genomes that have different sizes and unrelated sequences cause different immune stimulation, we compared the therapeutic efficacies of B and M components and unfractionated CPMV in vitro and in mouse cancer models. We found that separated B and M particles behaved similarly to the mixed CPMV, activating innate immune cells to induce the secretion of pro-inflammatory cytokines such as IFNα, IFNγ, IL-6, and IL-12, while inhibiting immunosuppressive cytokines such as TGF-β and IL-10. In murine models of melanoma and colon cancer, the mixed and separated CPMV particles all significantly reduced tumor growth and prolonged survival with no significant difference. This shows that the specific RNA genomes similarly stimulate the immune system even though B particles have 40% more RNA than M particles; each CPMV particle type can be used as an effective adjuvant against cancer with the same efficacy as native mixed CPMV. From a translational point of view, the use of either B or M component vs the mixed CPMV formulation offers the advantage that separated B or M alone is noninfectious toward plants and thus provides agronomic safety.