Spherical Particles Research Articles

The effect of extracellular polymeric substances on MICP solidifying rare earth slags and stabilizing Th and U.

Microbially induced carbonate precipitation (MICP) has been used to cure rare earth slags (RES) containing radionuclides (e.g. Th and U) and heavy metals with favorable results. However, the role of microbial extracellular polymeric substances (EPS) in MICP curing RES remains unclear. In this study, the EPS of Lysinibacillus sphaericus K-1 was extracted for the experiments of adsorption, inducing calcium carbonate (CaCO3) precipitation and curing of RES. The role of EPS in in MICP curing RES and stabilizing radionuclides and heavy metals was analyzed by evaluating the concentration and morphological distribution of radionuclides and heavy metals, and the compressive strength of the cured body. The results indicate that the adsorption efficiencies of EPS for Th (IV), U (VI), Cu2+, Pb2+, Zn2+, and Cd2+ were 44.83%, 45.83%, 53.7%, 61.3%, 42.1%, and 77.85%, respectively. The addition of EPS solution resulted in the formation of nanoscale spherical particles on the microorganism surface, which could act as an accumulating skeleton to facilitate the formation of CaCO3. After adding 20 mL of EPS solution during the curing process (Treat group), the maximum unconfined compressive strength (UCS) of the cured body reached 1.922 MPa, which was 12.13% higher than the CK group. The contents of exchangeable Th (IV) and U (VI) in the cured bodies of the Treat group decreased by 3.35% and 4.93%, respectively, compared with the CK group. Therefore, EPS enhances the effect of MICP curing RES and reduces the potential environmental problems that may be caused by radionuclides and heavy metals during the long-term sequestration of RES.

Diatom Chaetoceros Sp. as an Efficient Biological Antidote in Iron Toxicity: In‐Vitro and In‐Vivo Experiments

AbstractAll living organisms require mineral iron, but excess iron can lead to the production of free radicals and organ damage, such as liver damage in humans. This study investigated the diatom Chaetoceros sp. as an iron adsorbent in iron overload. First, the morphology and chemical composition of the diatom was characterized by spectroscopic and microscopic techniques. It was defined that diatoms have spherical particles with an average size of less than 2.0 μm. The affinity of diatoms for ionic Fe (II) uptake was evaluated. Fe (II) adsorption capacity was determined in vitro in two simulated intestinal and gastric aqueous media with pH values of 7.2 and 1.2. In both media, the diatom acted as a super‐adsorbent of Fe (II), while the highest adsorption occurred in a medium with a pH of 1.2. The correlation of the adsorption isotherm data was well studied with three well‐known equations, Langmuir, Fruindlich, and Redlich‐Peterson. The Langmuir model fitted the adsorption data best. The pseudo‐first‐order reaction model also provided a good fit for the adsorption kinetic data. In the in vivo study, the diatom was administered to iron‐overloaded rats. Biochemical parameters of organ damage and plasma Fe levels were determined at 2 h and 24 h intervals after diatom administration. The results show that diatoms can prevent acute iron poisoning by reducing plasma levels. Diatoms proved to be potent antidote agents in iron overdose conditions.

Direct force measurements between sub-micron rod-shaped colloids by AFM

The colloidal probe (CP) technique is an essential tool for quantitative direct force measurements by atomic force microscopy (AFM). By attaching a colloidal particle to the free end of an AFM-cantilever, not only a defined interaction geometry can be accomplished, but also a nearly arbitrary surface chemistry becomes possible. Commonly, the CP-technique is utilized for spherical particles in the sphere/sphere or sphere/plane interaction geometry. Here, the CP-technique has been extended to rod-shaped colloids with diameters well below one micrometer, thus preparing ‘rod probes’ based on a procedure similar to that known from DNA combing, allowing for a controlled alignment between these rods and the rod probe. In combination with AFM-imaging by the rod on the probe, sufficiently orthogonally aligned pairs of rods can be identified, and direct force measurements in the crossed-cylinder geometry, similar to the surface force apparatus (SFA), can be accomplished. A proof-of-concept of direct force measurements between silica rods with diameters of 270 ± 50 nm has been presented. The acquired interaction force profiles have been quantitatively evaluated within the framework of the full solutions of the Poisson-Boltzmann equation, including charge regulation.

CuO−La2O3 Nanocomposite as a Recyclable and Eco‐Friendly, Heterogeneous Catalyst for the One‐Pot Synthesis of Pyrano [2, 3‐c] Pyrazoles

AbstractIn this work, the unique performance of binary acid‐base CuO/La2O3 nanocomposite as a highly efficient heterogeneous catalyst was successfully examined for the one‐pot multicomponent synthesis of pyrano [2, 3‐c] pyrazole derivatives. The strong interactions between La and Cu had a profound effect on the catalytic activity of nanocatalysts. In addition, high selectivity, easy recovery, reusability, a very reasonable price, simple preparation and eco‐friendliness are other important advantages of this nanocatalyst. The characterized nanocomposite demonstrated excellent structural and morphological properties, leading to high catalytic efficiency. Characterization using Fourier Transform Infrared Spectroscopy (FT‐IR), X‐ray Powder Diffraction (XRD) confirmed crystallographic structure, and Field Emission Scanning Electron Microscopy (FE‐SEM) showed a spherical particle size of approximately 43 nm. Energy‐Dispersive X‐ray (EDX) analysis confirmed the composition of La, O, and Cu elements in the nanocomposite as 86.4 %, 13.5 %, and 0.2 %, respectively. The optimal condition for the synthesis resulted in a 98 % yield of pyrano [2, 3‐c] pyrazole derivatives under reflux with 0.02 g of CuO/La2O3 catalyst in a 10‐minute reaction time.

Pore-scale simulation of diffusion characteristics inside the bi-dispersed pore structure

The classical diffusion models fail to predict the diffusivity of bi-dispersed porous materials, particularly at low macro-porosity. In this work, a pore-scale simulation is carried out to investigate the diffusion process inside ordered and random bi-dispersed pore structures under different growth phases and shapes. The applicability of existing models is evaluated. The results reveal that Maxwell and Nield models are inadequate to predict the diffusivity of the ordered macropore structure under different growth phase types and shapes. Meanwhile, the ordered distribution of microporous spherical particles is superior to that of macropores. For random pore structure, the macropore-macropore diffusion path contributes to the error of the random pore model, which depends on the ratio of the micropore-macropore diffusivity.

Microphysical Characterization of Boundary Layer Ice Particles: Results from a 3-Year Measurement Campaign in Interior Alaska

Abstract A three-winter study has been conducted to better understand the relationship between atmospheric conditions and ice fog or diamond dust microphysics. Measurements were conducted east of downtown Fairbanks in interior Alaska during nonprecipitating conditions. Atmospheric conditions were measured with several weather stations around the Fairbanks region and two meteorological temperature profiler instruments (ATTEX MTP-5HE and MTP-5PE). Near-surface ice particle microphysical observations were conducted with the Particle Phase Discriminator mark 2, Karlsruhe edition (PPD-2K), instrument, which measures particles from 8 to 112 μm (sphere equivalent). Panoramic camera images were captured and saved every 10 min throughout the campaign for visual assessment of atmospheric conditions. Machine learning was used to classify both cloud particle microphysical characteristics from the PPD-2K data and to categorize boundary layer conditions using the panoramic camera images. For panoramic camera images, data were categorized as cloudy, clear, fog, snowing, and a nearby power plant plume. For the PPD-2K machine learning study, the scattering pattern images were used to identify rough surface, pristine, sublimating, and spherical particles. Three additional categories were used to identify indeterminant or saturated images. These categories and categories derived from weather station data (e.g., temperature ranges) are used to quantify ice microphysical properties under different conditions. For the complete microphysical dataset, pristine plates or columns accounted for 15.5%, 16.3% appeared to be sublimating particles, and 43.4% were complex particles with either rough surfaces or multiple branches. Although the temperature was as warm as −20°C during measurements, only 1.3% of the particles were classified as liquid. Significance Statement Boundary layer ice particles are frequently present in the near-surface atmosphere when surface temperatures drop below −20°C. Substantial human impacts can occur due to visibility degradation and deposition of particles on surfaces. Understanding particle shape, size, and phase (liquid or solid) is important for understanding those impacts. This study presents the results of a 3-yr measurement campaign in Fairbanks, Alaska, in which we relate ice particle characteristics to lower atmospheric conditions. Results should improve weather forecasting and hazard prediction.

Deterministic drag modelling for spherical particles in Stokes regime using data-driven approaches

In this paper, we develop a deterministic drag model for stationary spherical particles in a Stokes flow using a cascade of data-driven approaches. The model accounts for the variation in drag experienced by each particle within fixed random arrangements. The developed model is a symbolic expression that offers explainability, ease of implementation, and computational efficiency. Firstly, we generate particle-resolved direct numerical simulation data of the flow past periodic random arrangements of stationary spherical particles with volume fractions between 0.05 and 0.4 using the method of regularized Stokeslets. Secondly, we train graph neural networks (GNs) on the generated data to learn the pairwise influence of neighbouring particles on a reference particle. The GNs are converted to symbolic expressions using genetic programming (GP), unveiling repeated subexpressions. Finally, these subexpressions constitute the foundation of the proposed algebraic model, further refined via non-linear regression. The proposed model can qualitatively mimic the pairwise influences as predicted by the GN and can capture the drag variations with accuracy from 74% and up to 84.7% when compared to the particle-resolved simulations. Due to the interpretability of the proposed model, we are able to explore how neighbour positions alter the drag of a particle in an assembly. The proposed model is a promising tool for studying the dynamics of particle assemblies in Stokes flow.

Optimization and surface functionalization of biologically synthesized mesoporous silica nanoparticles to remove ASA drug from water: Sorption and regeneration study

Several studies have reported the rapid development of adsorbents with high efficacy, high stability and ample porosity for environmental remediation, where it still represents the significant challenges due to their expensive and less ecofriendly production. In present study, a newly optimized and functionalized green biosurfactant-mediated silica nanoparticle utilized to improve the surface properties and effectively remove the toxic drug acetylsalicylic acid (ASA) from water. The successful synthesis and physicochemical properties of BMSN (Biologically synthesized mesoporous silica nanoparticles), A-BMSN-NH2 and A-BMSN-CS was carried out through characterization techniques such as FESEM, HRTEM, EDXS, XRD, FTIR, BET, and XPS. However, FESEM and HRTEM analysis reveal the perfectly spherical particles with minimal aggregation (60–82nm). The XRD confirms amorphous characteristics and FTIR indicates the presence of Si-O and –NH groups. Furthermore, BET demonstrates a high surface area of 0.015 (40.1907m2/g), and XPS identifies Si-O-Si linkages with strong binding energy. Furthermore, the study also examined the influence of various experimental parameters during the optimization process of adsorption study, including adsorbent dosage, pH, initial concentration, contact time, and temperature. The adsorption study demonstrated the highest removal efficiency at pH∼6 with effective adsorbent (A-BMSN-CS) dosage of 3.25mg/40mL, and optimum initial concentration 100ppm over 180min at room temperature. Moreover, Freundlich isotherm model (R2=0.88014) exhibited well-fitted with higher adsorption capacity as compared to other isotherm models in case of A-BMSN-CS adsorbent. The adsorption kinetics described well-fitted by Pseudo second order model comprising R2=0.99999. In addition, thermodynamic parameters exhibited that the adsorption of ASA on adsorbents surface is spontaneous and exothermic process due to negative values of ΔH°, ΔS°, and ΔG°. Therefore, the promising formed adsorbents could be highly recommended to use in potential significant applications including use as drug carrier in pharmaceutics, heavy metals removal, energy storage, as biomarkers, etc.

Magnetic coagulant derived from Cassia fistula seed for real textile wastewater treatment: A pilot-scale study

Cassia fistula (C. fistula) seed-derived coagulants have demonstrated substantial potential for treating dye-based wastewater. Such coagulants exhibit notable coagulating-flocculating activity and are environmentally friendly. However, recovering these natural coagulants from aqueous media poses challenges. In this study, we introduce a novel plant-derived magnetic coagulant that is a combination of C. fistula seed gum with magnetic spinel ferrite. This research includes a pilot-scale study to simulate full-scale textile wastewater treatment using this composite. Material characterisations revealed that spherical CoFe2O4 particles could be effectively coated with the active coagulant, C. fistula gum. The saturation magnetisation of the composite, measured at 54.11 emu/g, facilitates its convenient separation from aqueous solutions using an external magnetic field. Bench-scale studies showed that initial pH and coagulant dosage substantially affect the removal efficiency of colour and chemical oxygen demand (COD). In the pilot-scale study, the C. fistula–CoFe2O4 composite demonstrated promising coagulant properties. It achieved a colour removal percentage of 94.0 % with a volume of 30 L and a coagulant dosage of 12.3 g L− 1. Using this coagulation–flocculation process as a primary treatment step, possibly followed by biological or membrane methods, can help meet Vietnamese environmental standards.

Finite-size inertial spherical particles in turbulence

Finite-size inertial spherical particles in turbulence

Increased Antibacterial Activity of Zinc-Silver Doped Hydroxyapatite Synthesized via Ultrasonic in Combination with Sol-Gel Technique using Glutinous Rice as a Template

T his work aims to synthesize Zn-Ag doped hydroxyapatite using glutinous rice (Zn-Ag doped GRHA) as a template through ultrasonic irradiation coupled with sol-gel technique. The prepared materials are referred to as Ca9.0Zn1.0-xAgx(PO4)6(OH)2 which consist of Zn2+ and Ag+ varying molar ratios (x= 0.0, 0.25, 0.50, 0.75 and 1.0). The synthesized samples were characterized by various techniques. XRD results revealed that Zn2+ and Ag+ were incorporated into a hexagonal framework of HA. FT-IR analysis showed that the main functional groups were hydroxyl and phosphate groups. SEM images showed a rough surface morphology, which consists of very small spherical particles. TEM images revealed the homogeneous distribution of Zn2+ and Ag+ in the synthesized samples. Antibacterial activity of the Zn-Ag doped GRHA against five strains of bacteria including S. aureus, B. cereus, B. subtilis, P. aeruginosa and E. coli was investigated. Zn0.75Ag0.25 doped GRHA showed excellent antibacterial activity against all strains except P. aeruginosa.

Effect of MnO2 Nanoparticles Stabilized with Cocamidopropyl Betaine on Germination and Development of Pea (Pisum sativum L.) Seedlings.

This study aimed to synthesize, characterize, and evaluate the effect of cocamidopropyl betaine-stabilized MnO2 nanoparticles (NPs) on the germination and development of pea seedlings. The synthesized NPs manifested as aggregates ranging from 50-600 nm, comprising spherical particles sized between 19 to 50 nm. These particles exhibited partial crystallization, indicated by peaks at 2θ = 25.37, 37.62, 41.18, 49.41, 61.45, and 65.79°, characteristic of MnO2 with a tetragonal crystal lattice with a I4/m spatial group. Quantum chemical modelling showed that the stabilization process of MnO2 NPs with cocamidopropyl betaine is energetically advantageous (∆E > 1299.000 kcal/mol) and chemically stable, as confirmed by the positive chemical hardness values (0.023 ≤ η ≤ 0.053 eV). It was revealed that the interaction between the MnO2 molecule and cocamidopropyl betaine, facilitated by a secondary amino group (NH), is the most probable scenario. This ascertain is supported by the values of the difference in total energy (∆E = 1299.519 kcal/mol) and chemical hardness (η = 0.053 eV). These findings were further confirmed using FTIR spectroscopy. The effect of MnO2 NPs at various concentrations on the germination of pea seeds was found to be nonlinear and ambiguous. The investigation revealed that MnO2 NPs at a concentration of 0.1 mg/L resulted in the highest germination energy (91.25%), germinability (95.60%), and lengths of roots and seedlings among all experimental samples. However, an increase in the concentration of preparation led to a slight growth suppression (1-10 mg/L) and the pronounced inhibition of seedling and root development (100 mg/L). The analysis of antioxidant indicators and phytochemicals in pea seedlings indicated that only 100 mg/L MnO2 NPs have a negative effect on the content of soluble sugars, chlorophyll a/b, carotenoids, and phenols. Conversely, lower concentrations showed a stimulating effect on photosynthesis indicators. Nevertheless, MnO2 NPs at all concentrations generally decreased the antioxidant potential of pea seedlings, except for the ABTS parameter. Pea seedlings showed a notable capacity to absorb Mn, reaching levels of 586.5 μg/L at 10 mg/L and 892.6 μg/L at 100 mg/L MnO2 NPs, surpassing the toxic level for peas according to scientific literature. However, the most important result was the observed growth-stimulating activity at 0.1 mg/L MnO2 NPs stabilized with cocamidopropyl betaine, suggesting a promising avenue for further research.

Convergence and accuracy of FDTD modelling for periodic plasmonic systems

Despite the widespread use of the finite-difference time-domain (FDTD) method for modeling plasmonic systems, there is a lack of detailed convergence and accuracy studies for periodic nanoparticle systems in which both particle radius and interparticle distance are critical parameters. Using an in-house parallelized 3D-FDTD code for which we implemented interface field averaging, convergence and accuracy were evaluated for various spherical particle radii, inter-distances, and radius-to-mesh size ratios. We found that Interface Field Averaging (IFA) FDTD improved accuracy and convergence with respect to per-component (Per-C) meshing. In the worst case of this study, the convergence error decreased from 4.9% to 2.6% only by using IFA. Accuracy was verified by benchmarking our simulation results with COMSOL Multiphysics software. Furthermore, we notice that there exists no general rule for choosing the mesh size. Careful convergence testing should therefore be carried out systematically.

A Nasal Vaccine Candidate, Containing Three Antigenic Regions from SARS-CoV-2, to Induce a Broader Response.

A chimeric protein, formed by two fragments of the conserved nucleocapsid (N) and S2 proteins from SARS-CoV-2, was obtained as a recombinant construct in Escherichia coli. The N fragment belongs to the C-terminal domain whereas the S2 fragment spans the fibre structure in the post-fusion conformation of the spike protein. The resultant protein, named S2NDH, was able to form spherical particles of 10 nm, which forms aggregates upon mixture with the CpG ODN-39M. Both preparations were recognized by positive COVID-19 human sera. The S2NDH + ODN-39M formulation administered by the intranasal route resulted highly immunogenic in Balb/c mice. It induced cross-reactive anti-N humoral immunity in both sera and bronchoalveolar fluids, under a Th1 pattern. The cell-mediated immunity (CMI) was also broad, with positive response even against the N protein of SARS-CoV-1. However, neither neutralizing antibodies (NAb) nor CMI against the S2 region were obtained. As alternative, the RBD protein was included in the formulation as inducer of NAb. Upon evaluation in mice by the intranasal route, a clear adjuvant effect was detected for the S2NDH + ODN-39M preparation over RBD. High levels of NAb were induced against SARS-CoV-2 and SARS-CoV-1. The bivalent formulation S2NDH + ODN-39M + RBD, administered by the intranasal route, constitutes an attractive proposal as booster vaccine of sarbecovirus scope.

Scattering matrices of particle ensembles analytically decomposed into pure Mueller matrices

Scattering matrices of particle ensembles are analytically decomposed into sums of pure Mueller matrices. The ensembles are assumed to have equal numbers of particles and their mirror particles, both in random orientation. In the general case, there are four pure Mueller matrices in the decomposition. In the present spectral decomposition, of these four matrices, there is a single matrix that qualifies as a scattering matrix, whereas the remaining three matrices represent other classes of pure matrices. For ensembles of spherical particles, there are two pure Mueller matrices in the decomposition. Again, there is a single matrix qualifying as a scattering matrix. The analytical decomposition unveils the explicit dependencies of the pure Mueller matrices on the ensemble-averaged scattering matrix. Applications are identified in scattering by single particles and by random media of particles.

Geochemical implications of uranium-bearing thucholite aggregates in the Upper Permian Kupferschiefer shale, Lubin district, Poland

AbstractNew inorganic and organic geochemical data from thucholite in the Upper Permian (Wuchiapingian) Kupferschiefer (T1) shale collected at the Polkowice-Sieroszowice Cu-Ag mine in Poland are presented. Thucholite, which forms spherical or granular clusters, appears scattered in the T1 dolomitic shale at the oxic-anoxic boundary occurring within the same shale member. The composition of thucholite concretions and the T1 shale differs by a higher content of U- and REE-enriched mineral phases within the thucholite concretions compared to the T1 shale, suggesting a different mineralising history. The differences also comprise higher Ntot, Ctot, Htot, Stot contents and higher C/N, C/S ratios in thucholite than in the T1 shale. The hydrocarbon composition of the thucholite and the surrounding T1 shale also varies. Both are dominated by polycyclic aromatic compounds and their phenyl derivatives. However, higher abundances of unsubstituted polycyclic aromatic hydrocarbons in the thucholite are indicative of its pyrogenic origin. Pyrolytic compounds such as benz[a]anthracene or benzo[a]pyrene are more typical of the thucholite than the T1 shale. Microscopic observations of the thucholite and its molecular composition suggest that it represents well-rounded small charcoal fragments. These charcoals were formed during low-temperature combustion, as confirmed by semifusinite reflectance values, indicating surface fire temperatures of about 400 °C, and the absence of the high-temperature pyrogenic polycyclic aromatic hydrocarbons. Charred detrital particles, likely the main source of insoluble organic matter in the thucholite, migrated to the sedimentary basin in the form of spherical carbonaceous particulates, which adsorbed uranium and REE in particular, which would further explain their different contents and sorption properties in the depositional environment. Finally, the difference in mineral content between thucholite and the T1 shale could also have been caused by microbes, which might have formed biofilms on mineral particles, and caused a change in the original mineral composition.

SYNTHESIS AND CHARACTERIZATION OF ACTIVATED CARBON PREPARED FROM RICE HUSK BY PHYSICS-CHEMICAL ACTIVATION

Activated carbon is an amorphous carbon material predominantly composed of free carbon atoms with high adsorption capacity. The amorphous structure in activated carbon affects its adsorption capacity; the higher the percentage of amorphous carbon, the greater the adsorption capacity of the activated carbon. Activated carbon can be obtained from rice husk waste containing 30-40% C in cellulose, hemicellulose, and lignin. Therefore, this study was conducted to observe activated carbon's phases, morphology, elemental composition, and particle size. Activated carbon was synthesized using a physics-chemical activation method, which began with washing the rice husk samples, followed by air drying, carbonizing into charcoal, and grinding it finely. The rice husk charcoal powder was then physically activated at a temperature of 500℃. The physically activated product was then chemically activated using 6M HCl with a charcoal-to-activator ratio of 1:10 (m/V), stirred at 250 rpm for 1 hour, and then allowed to settle for 24 hours. It was then washed and dried to produce activated carbon powder. XRD test results showed diffraction peaks at 2θ = 22.23° without sharp or pointed peaks, indicating that the activated carbon has an amorphous structure. SEM test results showed the morphology of rice husk-activated carbon with spherical particle shapes and a particle size distribution of 20-70 nm. EDX test results showed that the rice husk activated carbon is predominantly composed of C, O, and Si with respective percentages of 54.31%, 40.04%, and 2.49%.

The Roles of Oil-Water Interfaces in Forming Ultrasmall CaSO4 Nanoparticles.

In natural and engineered environmental systems, calcium sulfate (CaSO4) nucleation commonly occurs at dynamic liquid-liquid interfaces. Although CaSO4 is one of the most common minerals in oil spills and oil-water separation, the mechanisms driving its nucleation at these liquid-liquid interfaces remain poorly understood. In this study, using in situ small-angle X-ray scattering (SAXS), we examined CaSO4 nucleation at oil-water interfaces and found that within 60 minutes of reaction, short rod-shaped nanoparticles (with a radius of gyration (Rg) of 17.2 ± 2.7 nm and a length of 38.2 ± 5.8 nm) had formed preferentially at the interfaces. Wide-angle X-ray scattering (WAXS) analysis identified these nanoparticles as gypsum (CaSO4·2H2O). In addition, spherial nanoparticles measuring 4.1 nm in diameter were observed at oil-water interfaces, where surface-enhanced Raman spectroscopy (SERS) revealed an elevated pH compared to the bulk solution. The negatively charged oil-water interfaces preferentially adsorb calcium ions, collectively promoting CaSO4 formation there. CaSO4 particle formation at the oil-water interface follows a nonclassical nucleation (N-CNT) pathway by forming ultrasmall amorphous spherical particles which then aggregate to form intermediate nanoparticles, subsequently growing into nanorod-shaped gypsum. These findings of this study provide insights into mineral scaling during membrane separation and can inform more efficient oil transport in energy recovery systems.

Promoting Thermal Conductivity of Alumina-Based Composite Materials by Systematically Incorporating Modified Graphene Oxide

Small amounts of thermally conductive graphene oxide (GO) and modified GO are systematically introduced as a second filler to thermal interface materials (TIMs) consisting of alumina (Al2O3) particles and polydimethylsiloxane (PDMS). The surface of GO is covalently linked with an organic moiety, octadecylamine (ODA), to significantly improve the miscibility and dispersity of GO across the TIM matrix. Subsequently, two series of PDMS-Al2O3 composite TIMs are manufactured as a function of GO and ODA-GO content (0.25 wt%–2.5 wt%) to understand the effect of these second additives. The incorporation of GO into the Al2O3-PDMS composite materials generally increases the thermal conductivity (TC), ranging from 18% to 29%. Conversely, the use of ODA-GO further enhances the overall performance of TIMs (22–54%) by facilitating the dispersion degree of GO across the composite matrix. The great improvement in TC is presumably related to the formation of conductive pathways by uniformly integrating 2D-type GO flakes across spherical Al2O3 particle networks. The ability to simply regulate the polarity of the thermally conductive second filler can provide an idea for designing cost-effective and practical TIM-2-type pads that can be commercially applicable in between an integrated heat spreader and a heat sink.

Effects of rock types and crushing mechanism on the 3D morphological parameters of manufactured sands: a combination study of 3D scanning and spherical harmonic analysis

This study aims to investigate the effect of rock types, i.e., granite, conglomerate rock, limestone, and crushing mechanism, i.e., Vertical Shaft Impact (VSI) crusher, Horizontal Shaft Impact (HSI) crusher, on the morphology of manufactured sands. By combining the 3D scanning and spherical harmonic analysis, the morphological parameters of manufactured sands such as elongation ratio (EL), flatness ratio (Fl), aspect ratio (AR), edge angle (EA), sphericity (SH), and fractal dimension were quantified. The results indicate limestone is more readily broken into blade-shaped particles without being able to blunt sharp edges through constant abrasion. The proportion of bladed particles in manufactured sand prepared from limestone is 1.91 times higher than the proportion of bladed particles in conglomerates. Additionally, the HSI crusher has a more significant effect on rocks with smaller strength. For the same parent rock, manufactured sand from a VSI crusher contains 30% more spherical and oblate particles than from an HSI crusher.