Effect of Mixed Dispersants on Suppression of the Gel Effect during Aqueous Adiabatic Terpolymerization of AM,NaAA,and DMC

Gelation adversely affects the aqueous adiabatic terpolymerization of acrylamide (AM), sodium acrylate (NaAA),and 2-methacryloyloxyethyl trimethylammonium chloride (DMC). Here, the mixed dispersants sorbitan monooleate (Span80) and polyoxyethylene sorbitan monooleate (Tween 80) were introduced to the terpolymerization system in an attemptto mitigate the gel effect. This enabled the preparation of high-performance amphoteric polyacrylamides, which werecharacterized by Fourier-transform infrared spectroscopy and thermogravimetric analysis. The influences of the dispersanttype and content as well as the hydrophilic-lipophilic balance (HLB) on the gel effect were examined, and the mechanismunderlying the suppression of the gel effect was considered. The obtained results indicated that the gel effect can beeffectively mitigated using an aqueous adiabatic terpolymerization system containing mixed Span 80/Tween 80 dispersantsat various contents. In particular, mixed dispersant contents of 0.6%–0.8% with HLB values of 5.0–6.0 afforded the optimalperformance (e.g., high viscosity, fast aqueous dissolution time, and the like).

Influence of dispersants on coal-water slurry prepared from the solid residue of plasma pyrolysis of coal

This work presents the influence of dispersants on coal-water slurry(CWS),which was prepared from the solid residue of plasma pyrolysis of coal.The effects of dispersant type,solid concentration,dispersant content,and temperature on the rheological properties of CWS are examined.A suitable empirical model regarding the relation between viscosity and temperature is proposed.Through the sedimentation experiment of CWS,dispersants are found to significantly promote the stability of CWS.

Influence of the Precipitating Reagents and Dispersants on the Formation Nano-Aluminum Hydroxide

The influence of the precipitating reagents and dispersants on the formation of nano-aluminum hydroxide from sodium aluminate solution by chemical precipitation was investigated. The influence of the dispersed seeds on the decomposi-tion process was investigated too. The alkaline aluminate solutions were used as original solutions with a concentration of Al2O3 having 14.78 g/dm3, αk—1.6 and127 g/dm3, αk—1.6. For the precipitation processes there were used follow-ing precipitating reagents—solutions HCl, NaHCO3 and NH4HCO3 with a concentration of 80 g/dm3, dispersants—PEG 6000, (NaPO3)6 and Tween 20. For the decomposition process the dispersed seeds and factories seeds were used. Structural studies of the aluminum hydroxide particles were carried out by means of the electron-probe microanalysis and scanning electron microscopy, and phase composition of products was determined by means of X-ray diffraction analysis. Ammonium bicarbonate and Tween 20 were determined as the optimal precipitating reagent and dispersant, correspondingly, resulting in dispersed aluminum hydroxide, which is used as a seed in the decomposition process. It was established that this product in form of dispersed seed considerably reduces the duration of the decomposition process;the maximal decomposition of solution (73.9%) was observed after injection of dispersеd aluminum hydroxide into solution. The final aluminum hydroxide having 90% of particles less than 100 nanometers was obtained within 7 hours of steady decreasing temperature from 70°C to 48°C.

Simulation and Experimental Study on the Effect of Dispersants on Soot Aggregation

Diesel engine technology innovation causes excessive soot accumulated in engine oil.Due to its detrimental effect on lubricant and diesel engine,improving the dispersibility of engine oil to restrain soot aggregation efficiently is the key technique for formulations.In this study,the aggregation of soot and interaction between dispersant and soot were investigated by molecular dynamic simulation.It was found that the molecular interaction between the dispersant and the soot aggregation system had a significant influence on disrupting the soot aggregation.Bis-PIBSI was more beneficial to having more interaction sites with soot molecules,while the mono-PIBSI with a high proportion of polar groups had stronger interaction with soot molecules.According to the simulation result,suggestions for use of additives were proposed.Carbon black dispersancy test was exploited to verify the dispersion effect of different dispersants on carbon black.The results indicate that mono-PIBSI and bis-PIBSI added at suitable mixture ratio to lubricant could perform good dispersion ability.

Stability of aqueous nano-ceramic coatings with two different dispersants

The effects of sodium carboxymethyl cellulose and sodium citrate as dispersants on nano-ceramic aqueous suspension were examined by the measurements of ζ -potential and the sedimentation test. The results show that proper addition of sodium carboxymethyl cellulose or sodium citrate into nano-ceramic coating, exhibits an enhanced dispersion and stability compared with the coating without dispersants. The negative ζ -potential of the particles in the nano-coating increases with the increase of pH value of the coating, and the curve of ζ -pH moves to lower pH range when the dispersants are added into the coating. To ensure that the coating has not only good stability and dispersibility but also no corrosivity to substrate alloy, adding 1.00% sodium citrate into coating with pH value of 7-8 is preferable to adding sodium carboxymethyl cellulose.

Influence of Dispersants on Flow Ability of Colloidal Alumina Bonded Corundum Castables

In order to make corundum castables satisfy more severe service conditions in high temperature industries,colloidal alumina due to the same main component with corundum castables was introduced for a pure binding system.The influence of three dispersants(citric acid,FS10 and urea)on the flow ability of colloidal alumina bonded corundum castables was researched to choose a suitable dispersant for solving the shaping problem.In order to further understand the influence of dispersants on the flow ability and the mechanism,the rheological property and Zeta potential value of the colloidal aluminadispersant system and the matrix-colloidal alumina-urea-water system were tested.The results show the castables added with the urea have the best flow ability,and the appropriate addition of the urea is 0.5%.

Interfacial properties of oil spill dispersants and their effects on dispersion effectiveness

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Development of High Efficient and Low Toxic Oil Spill Dispersants based on Sorbitol Derivants Nonionic Surfactants and Glycolipid Biosurfactants

Dispersants, usually blending with several surfactants and a solvent, are used to enhance oil spill dispersion as small droplets in water column. Although there is growing acceptance of dispersants as a counter measure to marine oil spills around the world, the two major issues with the dispersants are their toxicity to marine life and dispersion effectiveness (DE) for crude-oil, especially for heavy oil. To develop more efficient and less toxic dispersants, two kinds of sorbitol derivant nonionic surfactant (polysorbate 85 and sorbeth-40 tetraoleate), two kinds of glycolipid biosurfactants (rhamnolipid and sophorolipid) and less toxic solvent ethylene glycol butyl ether were chosen in this study, and two dispersant formulations were optimized by uniform design methods. Effects of dispersant-to-oil ratio, temperature, salinity and pH on the performance of the two optimized dispersants were investigated. The two dispersants had high dispersion effectiveness (DE) for heavy crude oil, while both dispersants keep high DE at the dispersant-to-oil ratio below 1:25 and the temperature above 5 ℃. In addition, the two dispersants also performed well in a wide range of salinity and pH values. Finally, toxicity tests revealed that the two dispersants showed low toxicity to two kinds of fish (Danio rerio and Microgobius gulosus).

Clarification of the dispersion mechanism of three typical chemical dispersants in lithium-ion battery (LIB) slurry

This paper mainly clarified the dispersion mechanism of three typical chemical dispersants which are polyethylene glycol octylphenyl ether(Triton X-100,T-100),polyethylene pyrrolidone(PVP)and carboxymethyl cellulose(CMC)within lithium-ion battery(LIB)slurry.Initially,the optimum amounts of T-100,PVP and CMC are selected from 0%,0.5%,1.5%and 2.5%by evaluating the impedance of LIB slurry in the case of adding each typical chemical dispersant with EIS method.Moreover,the impedance spectrum of three different slurry samples which are PVDF-NMP solution,LiCoO_(2) slurry and Carbon Black(CB)slurry with the optimum amount of each dispersant are also investigated.After using SEM and C element distribution images of LIB slurry to verify the correctness of the dispersion mechanism of each dispersant,it is concluded that the dispersion CMC with its optimum amount 1.5%is the best one to promote the formation of conductive paths and CB-coated LiCoO_(2) network structure within LIB slurry,which has the considerably potential to improve the performance of LIB.

Patterns and drivers of avian taxonomic and phylogenetic beta diversity in China vary across geographical backgrounds and dispersal abilities

Geographical background and dispersal ability may strongly influence assemblage dissimilarity;however,these aspects have generally been overlooked in previous large-scale beta diversity studies.Here,we examined whether the patterns and drivers of taxonomic beta diversity(TBD)and phylogenetic beta diversity(PBD)of breeding birds in China vary across(1)regions on both sides of the Hu Line,which demarcates China’s topographical,climatic,economic,and social patterns,and(2)species with different dispersal ability.TBD and PBD were calculated and partitioned into turnover and nestedness components using a moving window approach.Variables representing climate,habitat heterogeneity,and habitat quality were employed to evaluate the effects of environmental filtering.Spatial distance was considered to assess the impact of dispersal limitation.Variance partitioning analysis was applied to assess the relative roles of these variables.In general,the values of TBD and PBD were high in mountainous areas and were largely determined by environmental filtering.However,different dominant environmental filters on either side of the Hu Line led to divergent beta diversity patterns.Specifically,climate-driven species turnover and habitat heterogeneity-related species nestedness dominated the regions east and west of the line,respectively.Additionally,bird species with stronger dispersal ability were more susceptible to environmental filtering,resulting in more homogeneous assemblages.Our results indicated that regions with distinctive geographical backgrounds may present different ecological factors that lead to divergent assemblage dissimilarity patterns,and dispersal ability determines the response of assemblages to these ecological factors.Identifying a single universal explanation for the observed pattern without considering these aspects may lead to simplistic or incomplete conclusions.Consequently,a comprehensive understanding of large-scale beta diversity patterns and effective planning of conservation strategies necessitate the consideration of both geographical background and species dispersal ability.

Alkyl dimethyl betaine activates the low-temperature collection capacity of sodium oleate for scheelite

The impact of alkyl dimethyl betaine (ADB) on the collection capacity of sodium oleate (NaOl) at low temperatures was evaluated using flotation tests at various scales. The low-temperature synergistic mechanism of ADB and NaOl was explored by infrared spectroscopy, X-ray photoelectron spectroscopy, surface tension measurement, foam performance test, and flotation reagent size measurement.The flotation tests revealed that the collector mixed with octadecyl dimethyl betaine (ODB) and NaOl in a mass ratio of 4:96 exhibited the highest collection capacity. The combined collector could increase the scheelite recovery by 3.48% at low temperatures of 8–12℃. This is particularly relevant in the Luanchuan area, which has the largest scheelite concentrate output in China. The results confirmed that ODB enhanced the collection capability of NaOl by improving the dispersion and foaming performance. Betaine can be introduced as an additive to NaOl to improve the recovery of scheelite at low temperatures.

Parkland trees on smallholder farms ameliorate soil physical-chemical properties in the semi-arid area of Tigray,Ethiopia

Proposed agroforestry options should begin with the species that farmers are most familiar with,which would be the native multipurpose trees that have evolved under smallholder farms and socioeconomic conditions.The African birch(Anogeissus leiocarpa(DC.)Guill.&Perr.)and pink jacaranda(Stereospermum kunthianum Cham.)trees are the dominant species in the agroforestry parkland system in the drylands of Tigray,Ethiopia.Smallholder farmers highly value these trees for their multifunctional uses including timber,firewood,charcoal,medicine,etc.These trees also could improve soil fertility.However,the amount of soil physical and chemical properties enhanced by the two species must be determined to maintain the sustainable conservation of the species in the parklands and to scale up to similar agroecological systems.Hence,we selected twelve isolated trees,six from each species that had similar dendrometric characteristics and were growing in similar environmental conditions.We divided the canopy cover of each tree into three radial distances:mid-canopy,canopy edge,and canopy gap(control).At each distance,we took soil samples from three different depths.We collected 216 soil samples(half disturbed and the other half undisturbed)from each canopy position and soil depth.Bulk density(BD),soil moisture content(SMC),soil organic carbon(SOC),total nitrogen(TN),available phosphorus(AP),available potassium(AK),p H,electrical conductivity(EC),and cation exchange capacity(CEC)were analysed.Results revealed that soil physical and chemical properties significantly improved except for soil texture and EC under both species,CEC under A.leiocarpus,and soil p H under S.kunthianum,all the studied soils were improved under both species canopy as compared with canopy gap.SMC,TN,AP,and AK under canopy of these trees were respectively 24.1%,11.1%,55.0%,and 9.3% higher than those soils under control.The two parkland agroforestry species significantly enhanced soil fertility near the canopy of topsoil through improving soil physical and chemical properties.These two species were recommended in the drylands with similar agro-ecological systems.

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.

Study on concentration distribution and detonation characteristics for non-axisymmetric fuel dispersal

The study of non-axisymmetric fuel dispersal and detonation can provide reference for the prevention of industrial cloud explosion accidents and the design of fuel air explosive(FAE).The concentration and detonation fields of 85 kg cylindrical and fan-shaped fuel are investigated by experiments and numerical simulations.A dynamic model of the whole process for fuel dispersal and detonation is built.The concentration distribution of fuel is used as the initial condition to calculate the detonation stage,thus solving the initial value problem of detonation field.The phase and component changes of fuel cloud at different locations are compared.The fuel cloud is divided into directions of 0°,90°,135°and 180°.The results show that the maximum cloud radius is 20.94 m in 135°and the minimum is 12.04 m in 0°.The diameter of the detonation fireball is 53.6 m,and the peak temperature is 3455 K.The highest peak overpressure is 3.44 MPa in 0°and the lowest is 2.97 MPa in 135°.The proportion of liquid phase in 0°is22.90%,and the fuel loss is 11.8% and 9% higher than that in 135°and cylindrical charge,respectively.The stable propagation distance of blast wave in 135°is 42.50% longer than 0°and 28.37% longer than cylindrical charge.

Atomically Dispersed Ruthenium Catalysts with Open Hollow Structure for Lithium-Oxygen Batteries

Lithium–oxygen battery with ultrahigh theoretical energy density is considered a highly competitive next-generation energy storage device,but its practical application is severely hindered by issues such as difficult decomposition of discharge products at present.Here,we have developed N-doped carbon anchored atomically dispersed Ru sites cathode catalyst with open hollow structure(h-RuNC)for Lithium–oxygen battery.On one hand,the abundance of atomically dispersed Ru sites can effectively catalyze the formation and decomposition of discharge products,thereby greatly enhancing the redox kinetics.On the other hand,the open hollow structure not only enhances the mass activity of atomically dispersed Ru sites but also improves the diffusion efficiency of catalytic molecules.Therefore,the excellent activity from atomically dispersed Ru sites and the enhanced diffusion from open hollow structure respectively improve the redox kinetics and cycling stability,ultimately achieving a high-performance lithium–oxygen battery.

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.

Impacts of road on plant invasions in the Middle Mountain region of central Nepal

Biological invasion is triggered by human development activities such as the construction and expansion of road networks.Road verges serve as important habitats and corridors for the distribution of invasive alien plant species(IAPS)between geographically distant habitats.However,the trajectory of plant invasion and the data regarding the impact of roads on IAPS distribution are relatively poor in Nepal.Here,we surveyed two road types(main roads and feeder road)in the Middle Mountain region of central Nepal in order to investigate how different road types are driving the dispersal of IAPS along road verges and the adjacent natural habitats.Systematic sampling was conducted at ca 2.5 km intervals along the roads.At each sampling site,paired plots(25 m×4 m)were sampled:one adjacent to and along the road,and another 20 m away and parallel to it in the interior habitat.Our results revealed that the main road verges had a higher cover(33%)and a larger number of IAPS(14 species)than the feeder road(25%;10 species).The IAPS cover and richness were significantly higher along verges than in the adjacent interior habitats for both road types,indicating that roads are contributing as corridors for the dispersal of IAPS in the Middle Mountain areas of central Nepal.Further,elevation,tree canopy,and disturbances(grazing/mowing/trampling)were found to be the key factors that determine spatial distribution of IAPS along road verges.We emphasize that regular monitoring of vegetation along the road verges can help with the early detection and control of potential IAPS in the region before they become problematic.

Effects of wind speed,underlying surface,and seed morphological traits on the secondary seed dispersal in the Tengger Desert,China

The maintenance of sand-fixing vegetation is important for the stability of artificial sand-fixing systems in which seed dispersal plays a key role.Based on field wind tunnel experiments using 11 common plant species on the southeastern edge of the Tengger Desert,China,we studied the secondary seed dispersal in the fixed and semi-fixed sand dunes as well as in the mobile dunes in order to understand the limitations of vegetation regeneration and the maintenance of its stability.Our results indicated that there were significant variations among the selected 11 plant species in the threshold of wind speed(TWS).The TWS of Caragana korshinskii was the highest among the 11 plant species,whereas that of Echinops gmelinii was the lowest.Seed morphological traits and underlying surface could generally explain the TWS.During the secondary seed dispersal processes,the proportions of seeds that did not disperse(no dispersal)and only dispersed over short distance(short-distance dispersal within the wind tunnel test section)were significantly higher than those of seeds that were buried(including lost seeds)and dispersed over long distance(long-distance dispersal beyond the wind tunnel test section).Compared with other habitats,the mobile dunes were the most difficult places for secondary seed dispersal.Buried seeds were the easiest to be found in the semi-fixed sand dunes,whereas fixed sand dunes were the best sites for seeds that dispersed over long distance.The results of linear mixed models showed that after controlling the dispersal distance,smaller and rounder seeds dispersed farther.Shape index and wind speed were the two significant influencing factors on the burial of seeds.The explanatory power of wind speed,underlying surface,and seed morphological traits on the seeds that did not disperse and dispersed over short distance was far greater than that on the seeds that were buried and dispersed over long distance,implying that the processes and mechanisms of burial and long-distance dispersal are more complex.In summary,most seeds in the study area either did not move,were buried,or dispersed over short distance,promoting local vegetation regeneration.

Strong synergy between physical and chemical properties:Insight into optimization of atomically dispersed oxygen reduction catalysts

Atomically dispersed catalysts exhibit significant influence on facilitating the sluggish oxygen reduction reaction(ORR)kinetics with high atom economy,owing to remarkable attributes including nearly 100%atomic utilization and exceptional catalytic functionality.Furthermore,accurately controlling atomic physical properties including spin,charge,orbital,and lattice degrees of atomically dispersed catalysts can realize the optimized chemical properties including maximum atom utilization efficiency,homogenous active centers,and satisfactory catalytic performance,but remains elusive.Here,through physical and chemical insight,we review and systematically summarize the strategies to optimize atomically dispersed ORR catalysts including adjusting the atomic coordination environment,adjacent electronic orbital and site density,and the choice of dual-atom sites.Then the emphasis is on the fundamental understanding of the correlation between the physical property and the catalytic behavior for atomically dispersed catalysts.Finally,an overview of the existing challenges and prospects to illustrate the current obstacles and potential opportunities for the advancement of atomically dispersed catalysts in the realm of electrocatalytic reactions is offered.

Frequency-dependent viscoelasticity effects on the wave attenuation performance of multi-layered periodic foundations

In this paper,layered periodic foundations(LPFs)are numerically examined for their responses to longitudinal and transverse modes in the time and frequency domains.Three different unit-cells,i.e.,2-layer,4-layer,and 6-layer unit-cells,comprising concrete/rubber,concrete/rubber/steel/rubber,and concrete/rubber/steel/rubber/lead/rubber materials,respectively,are taken into account.Also,the viscoelasticity behavior of the rubber is modeled with two factors,i.e.,a frequency-independent(FI)loss factor and a linear frequency-dependent(FD)loss factor.Following the extraction of the complex dispersion curves and the identification of the band gaps(BGs),the simulations of wave transmission in the time and frequency domains are performed using the COMSOL software.Subsequent parametric studies evaluate the effects of the rubber viscoelasticity models on the dispersion curves and the wave transmission for the longitudinal and transverse modes.The results show that considering the rubber viscoelasticity enhances the wave attenuation performance.Moreover,the transverse-mode damping is more sensitive to the viscoelasticity model than its longitudinal counterpart.The 6-layer unit-cell LPF exhibits the lowest BG,ranging from 4.8 Hz to 6.5 Hz.