Different Degrees Of Agglomeration Research Articles

Effect of dispersion behavior of silica fume on the rheological properties and early hydration characteristics of ultra-high strength mortar

Silica fume plays a crucial role in ultra-high performance cementitious materials, but its dispersion, influenced by varying densification levels, leads to different degrees of agglomeration. However, the precise impact of this on rheological properties and early hydration characteristics of ultra-high performance cementitious materials remains unclear. This study assesses the impact of highly densified silica fume (HDSF), moderately densified silica fume (MDSF), and raw silica fume (RSF) on the rheological prperties of ultra-high strength mortar (UHSM). Additionally, the early hydration characteristics of UHSM influenced by these silica fumes are investigated through both heat of hydration and penetration resistance methods. The results showed that HDSF contained numerous large agglomerates, contrasting with MDSF and RSF, where the agglomerate sizes were comparable to those of cement particles. As the content of HDSF increased, the yield stress, viscosity, and thixotropy of UHSM gradually rose, accompanied by a notable decrease in hydration rate. Conversely, increasing MDSF and RSF content initially decreased and then increased these rheological properties, while the hydration rate remained relatively unchanged. The distribution behavior of the silica fumes influences the rheological properties of UHSM through water film thickness (particle spacing). Large agglomerates in HDSF reduce the activity of the entire cementitious system, significantly decreasing the hydration rate. In contrast, MDSF and RSF primarily influence the particle spacing within the cementitious system, subsequently impacting the hydration rate. This study provides theoretical insights and practical guidance for construction professionals in selecting appropriate silica fume for designing and regulating ultra-high performance cementitious materials performance.

Predicting Bulk Density for Agglomerated Raspberry Ketone via Integrating Morphological and Size Metrics Using Artificial Neural Networks

The bulk density of the particles, which is directly related to transportation and storage costs, is an important basic characteristic of products as well as an important parameter in many processing systems. This work quantified the relationship between the tapped bulk density of raspberry ketone with different degrees of agglomeration and morphological metrics (particle shape descriptors and roughness descriptors) and size metrics (size descriptors) and developed an artificial neural network (ANN) prediction model for the tapped bulk density of raspberry ketone. Samples prepared under different conditions were sieved and remixed, the tapped bulk density of the particles was then measured, and the descriptor features of the particles were obtained by combining them with image processing. The dimensions of the variables were decreased by principal component analysis and variance processing. To overcome the hyperparameter estimation of the heuristic-based artificial neural networks, the network model architectures were optimized by a neural architecture search strategy combining two-objective optimization. The results demonstrated that the tapped bulk density of raspberry ketone products is not only related to the descriptors of particle size and shape but also has a non-negligible relationship with particle roughness descriptors. The performance of the optimal ANN model demonstrated that the model can well predict the tapped bulk density of raspberry ketone with different degrees of agglomeration. The ANN model obtained by extracting morphology and size metrics through online image analysis can be used to measure the tapped bulk density in real-time and has the potential to be used for developing model-based online process monitoring.

An Empirical Study of Logistics Industry Clustering on Regional Economic Growth in Liaoning Province

Using the relevant data of Liaoning Province from 2010 to 2021, an econometric model is established with the C-D production function as the theory combined with the new economic theory, and dummy variables are introduced according to the three degrees of logistics industry agglomeration and the division of the three major economic zones in Liaoning Province, to explore the effect of logistics industry agglomeration on the promotion of regional economic growth under different degrees of agglomeration and economic zones. It is found that the clustering of logistics industry has a significant effect on the regional economic growth of Liaoning Province, and the effect of clustering varies with the degree of clustering, and as the degree of clustering grows, the degree of contribution changes with an inverted U trend; the effect of clustering varies with different economic zones, and the effect of clustering varies with the more economically developed regions. The more economically developed the region, the more obvious the promotion effect.

Effect of processing methods on the electrical conductivity properties of silver-polyurethane composite films (Experimental and numerical studies)

This research investigates the electrical properties of micro silver polyurethane (Ag-PU) composite films with different degrees of agglomeration. Ag-PU composite films were prepared by adding micro silver particles (<3.5 μm) into the thermoplastic PU matrix using a solution mixing method, followed by spin-coating or casting techniques. For some composite preparation, the silver solution was shear-mixed in an ultrasonic bath before being added to the PU solution to obtain higher filler dispersion within the polymer matrix. This method produced several composite films with variable degrees of silver aggregation with concentrations from 0 to 14 vol%. All composites showed only electrical conductivity through thickness when compressed under pressure in a range from 0.5 to 20 kPa. Generally, the percolation threshold and conductivity values of the composite film prepared by spin-coating were lower than those of the casting composite. The maximum conductivity value found in these composites was about 2.45 S/m. All composites’ electrical performance was numerically simulated using the finite element analysis method based on the representative volume element model (FE-RVE) with Digimat software. A correlation was observed between the experiments and those simulations. A semi-analytical model was used to estimate the composite electrical parameters.

Temporal and Spatial Analysis of the Changes in the Supply of Ecological Products in State-Owned Forest Farms after the Reform

To reveal the changes in the supply efficiency of forest farm ecological products after the reform of state-owned forest farms, this study uses the ecological product accounting method to calculate the physical quantity and value of state-owned forest farm ecological products using data from 2015 and 2020. Through exploratory spatial data analysis, the spatial distribution of the supply efficiency of ecological products of state-owned forest farms and its primary index are studied to explore the temporal and spatial evolution of ecological products from state-owned forest farms in China. The results show the following: (1) Through the reform of state-owned forest farms, the supply capacity of forest farms’ ecological products has been greatly improved, and the physical quantity and value quantity of ecological products have shown an increasing trend, with growth rates of 31.7% and 24.2%, respectively. (2) There is strong spatial heterogeneity in the supply efficiency of ecological products from state-owned forest farms in various provinces, and the overall distribution pattern is gradually decreasing from the northwest to the southeast coastal provinces. (3) There is a negative correlation between the supply capacity of ecological products and provincial GDP. The supply capacity of ecological products in provinces with high per capita GDP is relatively low. (4) The comprehensive index of the supply efficiency of ecological products and its first-level index of state-owned forest farms are characterized by different degrees of agglomeration in space, which are mainly represented by three distribution modes: “H–H”, “L–L”, and “L–H”. Therefore, it is necessary to clarify the ecological function orientation of state-owned forest farms, improve the endogenous power of ecological product supply, actively explore and connect social ecological needs, and achieve coordinated progress in terms of ecological environmental protection and economic development.

Biocompatibility and colorectal anti-cancer activity study of nanosized BaTiO3 coated spinel ferrites

In the present work, different nanoparticles spinel ferrite series (MFe2O4, Co0.5M0.5Fe2O4; M = Co, Mn, Ni, Mg, Cu, or Zn) have been obtained via sonochemical approach. Then, sol–gel method was employed to design core–shell magnetoelectric nanocomposites by coating these nanoparticles with BaTiO3 (BTO). The structure and morphology of the prepared samples were examined by X-ray powder diffraction (XRD), scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscope (HR-TEM), and zeta potential. XRD analysis showed the presence of spinel ferrite and BTO phases without any trace of a secondary phase. Both phases crystallized in the cubic structure. SEM micrographs illustrated an agglomeration of spherical grains with nonuniformly diphase orientation and different degrees of agglomeration. Moreover, HR-TEM revealed interplanar d-spacing planes that are in good agreement with those of the spinel ferrite phase and BTO phase. These techniques along with EDX analyses confirmed the successful formation of the desired nanocomposites. Zeta potential was also investigated. The biological influence of (MFe2O4, CoMFe) MNPs and core–shell (MFe2O4@BTO, CoMFe@BTO) magnetoelectric nanocomposites were examined by MTT and DAPI assays. Post 48 h of treatments, the anticancer activity of MNPs and MENCs was investigated on human colorectal carcinoma cells (HCT-116) against the cytocompatibility of normal non-cancerous cells (HEK-293). It was established that MNPs possess anti-colon cancer capability while MENCs exhibited a recovery effect due to the presence of a protective biocompatible BTO layer. RBCs hemolytic effect of NPs has ranged from non- to low-hemolytic effect. This effect that could be attributed to the surface charge from zeta potential, also the CoMnFe possesses the stable and lowest zeta potential in comparison with CoFe2O4 and MnFe2O4 also to the protective effect of shell. These findings open up wide prospects for biomedical applications of MNPs as anticancer and MENCs as promising drug nanocarriers.

Agglomeration Production, Industry Association and Carbon Emission Performance: Based on Spatial Analysis

Current emission reduction policies have struggled to adapt to the reality of industrial spatial agglomeration and increasing industrial linkages. In response, this paper incorporates new economic geography factors such as agglomeration production and industrial (trade) association into the analysis framework of carbon emission performance factors through China’s provincial panel data and conducts empirical research. It has been found that large-scale industrial production under economic agglomeration is conducive to improving carbon emission performance and that different forms of agglomeration at different degrees of agglomeration correspond to different carbon emission performances. As the degree of agglomeration increases, the effect of reducing emissions by specialized agglomeration decreases while the effect of reducing emissions by diversified agglomeration increases. Specialized agglomeration externalities and diversified agglomeration externalities can coexist at the same time, depending on the appropriate degree of agglomeration. There is a strong negative environmental efficiency effect in the provinces with close commodity trade links, which has triggered environmental dumping and pollution transfer between provinces. In the work of energy conservation and emission reduction, we must attach great importance to the hidden carbon in domestic merchandise trade and the resulting intergovernmental environmental game, and furthermore, give full play to the “self-purification” effect of aggregate production on energy conservation and emission reduction.

Synthesis and characterization of copper-nickel ferrite catalysts for ethyl acetate oxidation

Materials with nominal composition Cu0.5Ni0.5Fe2O4 were prepared by sol-gel auto-combustion technique using corresponding metal nitrates and citric acid as complexating agent/fuel agent. Different ratios between citric acid and metal ions were used to control the combustion reaction. For comparison, Cu0.5Ni0.5Fe2O4 ferrite was also synthesised by co-precipitation. Mossbauer spectroscopy was used for analysis of synthesised samples both at room temperature and liquid nitrogen boiling temperature. Iron distribution in tetrahedral and octahedral positions of spinel lattice was determined. Different degrees of agglomeration of the ferrite phase were estimated by super-paramagnetic behaviour of samples. In addition, methods of X-Ray Diffraction, UV-Vis, FTIR, nitrogen physisorption, TPR with hydrogen were applied for structural characterization of the materials. Some quantities of secondary phases (Cu, Cu-Ni alloy and hematite) were found out in samples prepared by auto-combustion method. The catalytic activities of the samples in ethyl acetate oxidation reaction strongly depended on the variations in the structural and texture characteristics of the samples. The sample synthesized at the highest ratio of citric acid to metal ions is characterized by the smallest ferrite crystallite size, the higher surface area and the best catalytic activity.

The effect of Ti on the microstructure and mechanical properties of (Ti + Mg3Sb2)/Mg composites

In the present research work, (titanium (Ti) + magnesium antimonide (Mg3Sb2)/magnesium (Mg) composites with Ti contents of 0, 5%, 10%, and 15% (mass fraction, %) were fabricated by powder metallurgy. The effect of different Ti contents on the microstructure and mechanical properties of (Ti + Mg3Sb2)/Mg composites was investigated. The results show that the volume of Mg3Sb2 compounds can be significantly refined and the distribution uniformity of Mg3Sb2 compounds can be improved by adding an appropriate amount of Ti. Part of Sb reacts with Ti in situ to form TiSb2 compounds at the periphery of Ti particles. However, the reaction is not sufficient, and there is still the remaining Ti distribution in composites. Both Ti particles and TiSb2 compounds form (Ti + TiSb2) microstructures, which have different degrees of agglomeration with the increase of Ti contents in composites. The appropriate amount of Ti can improve the mechanical properties of the composite, but excessive Ti can reduce the tensile strength of the composite.

Purification characteristics of fine particulate matter treated by a self-flushing wet electrostatic precipitator equipped with a flexible electrode

ABSTRACTA self-flushing wet electrostatic precipitator was developed to investigate the removal performance for fine particles. Flexible material (polypropylene, 840A) and carbon steel in the form of a spiked band were adopted as the collection plate and discharge electrode, respectively. The particle concentration, morphology, and trace-element content were measured by electric low-pressure impactor, scanning electron microscope, and energy-dispersive x-ray spectroscopy, respectively, before and after the electrostatic precipitator. With increasing gas velocity, the collection efficiency of fine particles (up to 0.8 μm in diameter) increased, while it decreased for particles with diameters larger than 0.8 μm. Increasing the dust inlet concentration increased the collection efficiency up to a point, from which it then declined gradually with further increases in the inlet concentration. The particulate matter after the wet electrostatic precipitator showed different degrees of agglomeration. The collection efficiency of trace elements within PM10 was less than that of the PM10 itself. Notably, the water consumption in the current setup was significantly lower than for other treatment processes of comparable collection efficiencies.Implications: Wet electrostatic precipitators, as fine filtration equipment, were generally applicable to coal-fired plants to reduce PM2.5 emissions in China. However, high energy consumption and unstable operation, such as water usage and spray washing directly in the electric field, seriously restricted the further development. The utilization of self-flushing wet electrostatic precipitator can solve these problems to some extent.

The role of agglomeration in the conductivity of carbon nanotube composites near percolation

A detailed study of agglomeration in composite materials containing carbon nanotubes (CNT) is presented. Three dimensional samples with different degrees of agglomeration were created in three different ways, leading to a wider range of geometries available to study. Virtual charges are injected into the computer-generated samples and move through these samples according to a Monte Carlo hopping algorithm. Results show that there is an optimal level of agglomeration that is actually beneficial for charge transport at low volume concentrations, lowering the percolation threshold. It is found that near percolation, a more uniform CNT distribution (less agglomeration) leads to more conductive paths, but with a lower mobility. The optimum level of agglomeration comes from a trade off between these two properties. Beyond this optimum agglomeration state, it is observed that conductivity tends to decrease as dispersion increases at all concentrations studied here. At high concentration (percolated samples), where CNT clumps merge, conductivity seems to be less sensitive to agglomeration.

Synthesis and Characterization of Core-Shell Magnetic Mesoporous Silica and Organosilica Nanostructures

ABSTRACTInitial results en route toward construction of complex magnetic core-shell silica and organosilica nanotheranostics are presented. Magnetite nanoparticles are synthesized by three different methods and embedded within mesoporous silica and organosilica frameworks by different surfactant-templated procedures to produce three types of core-shell nanoparticles. Magnetite nanoparticles (15 nm in diameter) are embedded within mesoporous silica nanoparticles to produce cell-like material with predominantly one magnetite nuclei-resembling core per nanoparticle, with final particle diameter of ca. 150 nm, specific surface area of 573 m2/g and hexagonally structured tubular pores (2.6 nm predominant diameter), extended throughout the volume of nanoparticles. Two forms of spherical core-shell nanoparticles composed of magnetite cores embedded within mesoporous organosilica shells are also obtained by employing ethylene and ethane bridged organobisalkoxysilane precursors. The obtained nanomaterials are characterized by high surface area (978 and 820 m2/g), tubular pore morphology (2 and 2.8 nm predominant pore diameters), different diameters (386 and 100-200 nm), in case of ethylene- and ethane-composed organosilica shells, respectively. Different degree of agglomeration of magnetite nanoparticles was also observed in the obtained materials, and in the case of utilization of surfactant-pre-stabilized magnetite nanoparticles for the syntheses, their uniform and non-agglomerated distribution within the shells was noted.

Synthesis and photoluminescence properties of cerium-doped terbium–yttrium aluminum garnet phosphor for white light-emitting diodes applications

Cerium-doped terbium-yttrium aluminum garnet phosphors were synthesized using the solid-state reaction method. The crystalline phase, morphology, and photoluminescence properties were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), and fluorescence spectrophotometer, respec- tively. The XRD results indicate that with an increase of the amount of x (Tb 3þ ), all of the samples have a pure garnet crystal structure without secondary phases. The SEM images reveal that the samples are composed of sphere-like crystallites, which exhibit different degrees of agglomeration. The luminescent properties of Ce 3þ ions in ðTbxY1−xÞ 2.9 Al5O12∶Ce0.1 have been studied, and it was found that the emission band shifted toward a longer wavelength. The redshift is attributed to the lowering of the 5d energy level centroid of Ce 3þ , which can be explained by the nephelauxetic effect and compression effect. These phosphors were coated on blue light- emitting diode (LED) chips to fabricate white light-emitting diodes (WLEDs), and their color-rendering indices, color temperatures, and luminous efficiencies were measured. As a consequence of the addition of Tb 3þ , the blue LED pumped ðTb0.4Y0.6Þ2.9Al5O12∶Ce0.1 phosphors WLEDs showed good optical properties. © 2015 Society of

Effect of particle agglomeration in nanotoxicology.

The emission of engineered nanoparticles (ENPs) into the environment in increasing quantity and variety raises a general concern regarding potential effects on human health. Compared with soluble substances, ENPs exhibit additional dimensions of complexity, that is, they exist not only in various sizes, shapes and chemical compositions but also in different degrees of agglomeration. The effect of the latter is the topic of this review in which we explore and discuss the role of agglomeration on toxicity, including the fate of nanomaterials after their release and the biological effects they may induce. In-depth investigations of the effect of ENP agglomeration on human health are still rare, but it may be stated that outside the body ENP agglomeration greatly reduces human exposure. After uptake, agglomeration of ENPs reduces translocation across primary barriers such as lungs, skin or the gastrointestinal tract, preventing exposure of "secondary" organs. In analogy, also cellular ENP uptake and intracellular distribution are affected by agglomeration. However, agglomeration may represent a risk factor if it occurs after translocation across the primary barriers, and ENPs are able to accumulate within the tissue and thus reduce clearance efficiency.

The beneficial use of HCl‐activated natural zeolite in ultrasound assisted synthesis of Cu/clinoptilolite–CeO2 nanocatalyst used for catalytic oxidation of diluted toluene in air at low temperature

AbstractBACKGROUNDTo remove toluene (a representative volatile organic compound (VOC)) from a waste gas stream, catalytic oxidation was utilized over Cu/Clinoptilolite–CeO2 nanocatalyst. The nanocatalyst with different loadings of Cu (5, 10, 15 wt%) was sonochemically synthesized and its performance in catalytic oxidation of toluene was studied. Characterization by XRD, FESEM, BET, EDX and FTIR were applied.RESULTSXRD results indicated well‐dispersed small copper particles even at high loadings of copper. Non‐sonicated Cu/Clinoptilolite–CeO2 catalyst showed agglomerated, non‐uniform morphology, while small particles with uniform shape and size with different degrees of agglomeration were observed in sonicated Cu/Clinoptilolite–CeO2 catalyst. A narrow particle size distribution with average size 21 nm was observed in the sonicated sample. BET analysis demonstrated considerable effects of HCl treatment in increasing the specific surface area of clinoptilolite. It also showed the strong influence of CeO2 addition as a promoter that sharply enhanced the surface area to 71.7 m2 g−1.CONCLUSIONCatalytic performance tests revealed that Cu(15%)/Clinoptilolite–CeO2 synthesized with ultrasound had the best performance of about 98% toluene abatement even at high concentrations of toluene (3000 ppm). A stability test of the synthesized nanocatalyst confirmed its constant activity for 1440 min, making it a promising catalyst for removal of VOCs. © 2014 Society of Chemical Industry

Ni nanoparticles: Study of Particles Formation and Agglomeration

We report the synthesis of nikel (Ni) nanoparticles produced by modified polyol method using N2H4.6H2O and ethylene glycol (EG) without any protective agent. The synthesis was conducted in 1 hour of heating at 60˚C. Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FE-SEM) have been used to characterize the Ni nanoparticles. TEM results showed that as-resulted Ni nanoparticles were almost spherical with size between 2nm to 600nm. XRD analysis indicated that the as-synthesized nanoparticles were Ni nanoparticles of face-centered cubic <fcc> crystal structure. Reaction rate increased as molar ratio of N2H4/Ni2+ increased with different degree of agglomeration. Particles produced at the highest molar ratio showed the highest degree of agglomeration as compared to other lower molar ratios. Also, we speculate the reduction of Ni2+ and formation of by product though colour changes of the reaction.

Effects of carbon nanotubes on primary neurons and glial cells

Carbon nanotubes (CNTs) are among the most promising novel nanomaterials and their unique chemical and physical properties suggest an enormous potential for many areas of research and applications. As a consequence, the production of CNT-based material and thus the occupational and public exposure to CNTs will increase steadily. Although there is evidence that nanoparticles (NPs) can enter the nervous system via the blood stream, olfactory nerves or sensory nerves in the skin, there is still only little knowledge about possible toxic effects of CNTs on cells of the nervous system. The goal of the present study was to analyse the influences of single-walled CNTs (SWCNTs) with different degrees of agglomeration on primary cultures derived from chicken embryonic spinal cord (SPC) or dorsal root ganglia (DRG). As measured by the Hoechst assay treatment of mixed neuro-glial cultures with up to 30 μg/mL SWCNTs significantly decreased the overall DNA content. This effect was more pronounced if cells were exposed to highly agglomerated SWCNTs as compared to better dispersed SWCNT-bundles. Using a cell-based ELISA we found that SWCNTs reduce the amount of glial cells in both peripheral nervous system (PNS) and central nervous system (CNS) derived cultures. Neurons were only affected in DRG derived cultures, where SWCNT treatment resulted in a decreased number of sensory neurons, as measured by ELISA. Additionally, whole-cell patch recordings revealed a diminished inward conductivity and a more positive resting membrane potential of SWCNT treated DRG derived neurons compared to control samples. The SWCNT suspensions used in this study induced acute toxic effects in primary cultures from both, the central and peripheral nervous system of chicken embryos. The level of toxicity is at least partially dependent on the agglomeration state of the tubes. Thus if SWCNTs can enter the nervous system at sufficiently high concentrations, it is likely that adverse effects on glial cells and neurons might occur.

Agglomeration of α-Al 2O 3 powders prepared by gel combustion

Ultrafine α-Al 2O 3 powders were prepared by a gel combustion method and the agglomeration characteristic of the resultant powders was studied. A variety of fine crystallite α-Al 2O 3 powders with different agglomeration structures could be obtained by altering the citrate-to-nitrate ratio γ and calcining the precursors at 1050 °C for 2 h. All the powders were of nearly equivalent crystallite size (60–80 nm) except for the P1 powder (113 nm) from the gel with γ = 0.033. The primary crystallites of the obtained α-Al 2O 3 powders were formed into large secondary particles with different degree of agglomeration. Except for the powder P1, the mean particle sizes from specific surface area and particle size distribution measurement increase with increasing citrate-to-nitrate ratio in the fuel-lean condition and decrease in the fuel-rich condition. Densities of alumina ceramics from powders P4 and P5 sintered at different temperatures were relatively low due to the wide particle size distribution.

The Effect of Cerium Precursor Agglomeration on the Synthesis of Ceria Particles and Its Influence on Shallow Trench Isolation Chemical Mechanical Polishing Performance

The level of agglomeration in the cerium precursor and its effect on the physicochemical properties of the synthesized ceria particles and how these properties influence shallow trench isolation chemical mechanical polishing (STI CMP) performance were investigated. Two different types of ceria particles were synthesized from cerium precursors of different degrees of agglomeration. The crystallinity and particle size distribution of the synthesized ceria particles were markedly different between these two types of particles. The ceria particles synthesized from agglomerated cerium precursors had a smaller crystallite size than the other particles due to the incomplete decarbonation reaction, which resulted in large agglomerations of particles. The different physical characteristics of the ceria particles resulted in remarkable discrepancies between the STI CMP performances of the ceria slurries, such as the oxide removal rate, the selectivity and the uniformity.

Controlling the agglomeration of anisotropic Ru nanoparticles by the microwave–polyol process

A rapid polyol process for the synthesis of ruthenium nanoparticles was developed using microwave irradiation. A colloidal solution of monodispersed anisotropic Ru metal nanoparticles (mean particle size 2–6 nm) with different aspect ratios was obtained first. Particles with different degrees of agglomeration have also been synthesized using monodisperse particles as seeds and PVP (poly- N-vinyl-2-pyrrolidone) as the stabilization reagent. The stabilization mechanisms of different protective reagents were studied by UV–vis spectra. The HRTEM images indicated that dendritic particles formed by controlling agglomeration consisted of single-crystal domains with a random crystalline orientation.