Mechanical Agitation Research Articles

Superhydrophobic alkylsilane functionalized cellulose beads for efficient oil/water separation

In this paper, cellulose beads (CBs) were fabricated through a simple and straightforward approach based on cellulosic pulp's mechanical agitation after the cellulose extraction from the palm fibers. Subsequently, the CBs were coated in a simple process with the hydrolysis and polycondensation of the triethoxy(octyl)silane (TEOS) for their further application in the separation of the oily wastewater, which seriously threatens the environment and human safety. The superhydrophobic CBs-g-TEOS (WCA ≈ 153°) exhibited good absorption capacities from 14.7 to 29.9 (g/g) for organic oils and solvents. They also showed good absorption capacity in acid, alkaline and saline environments as well as stable long-term recyclability and reusability (tested over 20 cycles) with an absorption capacity of 24.4 g/g for xylene and 23.6 g/g for toluene taken as an example. Due to their ecological qualities, low cost, and easy fabrication, coated cellulose beads with TEOS are a promising prospect for oil-water separation.

Genetic analysis of a phenotypic loss in the mechanosensory entrainment of a circalunar clock.

Genetic variants underlying traits that become either non-adaptive or selectively neutral are expected to have altered evolutionary trajectories. Uncovering genetic signatures associated with phenotypic loss presents the opportunity to discover the molecular basis for the phenotype in populations where it persists. Here we study circalunar clocks in populations of the marine midge Clunio marinus. The circalunar clock synchronizes development to the lunar phase, and it is set by moonlight and tidal cycles of mechanical agitation. Two out of ten studied populations have lost their sensitivity to mechanical agitation while preserving sensitivity to moonlight. Intriguingly, the F1 offspring of the two insensitive populations regained the sensitivity to mechanical entrainment, implying a genetically independent loss of the phenotype. By combining quantitative trait locus mapping and genome-wide screens, we explored the genetics of this phenotypic loss. QTL analysis suggested an oligogenic origin with one prevalent additive locus in one of the strains. In addition, it confirmed a distinct genetic architecture in the two insensitive populations. Genomic screens further uncovered several candidate genes underlying QTL regions. The strongest signal under the most prominent QTL contains a duplicated STAT1 gene, which has a well-established role in development, and CG022363, an ortholog of the Drosophila melanogaster CG32100 gene, which plays a role in gravitaxis. Our results support the notion that adaptive phenotypes have a complex genetic basis with mutations occurring at several loci. By dissecting the most prevalent signals, we started to reveal the molecular machinery responsible for the entrainment of the circalunar clock.

Importance of energy band theory and screening charge effect in piezo-electrocatalytical processes

The present study tries to shed more light on the controversial discussion around the ‘true’ mechanism behind piezo-electrocatalysis: energy band theory or screening charge effects. For this purpose, piezo-electrocatalysts made of three different materials with different energy band levels and piezoelectric properties, ZnO, BaTiO3 and BF-KBT-PT, were used to degrade Rhodamine B in aqueous solutions where combined ultrasound and mechanical agitation was used as the excitation method. The results suggest that both mechanisms may actually play an important role in the overall process, as the largest overall dye degradation was achieved with the piezo-electrocatalyst most likely to generate radicals via both piezo-electrocatalytic mechanisms.

Ultrasound application in alkaline pretreatment process of spodumene to improve particle floatability

Selective surface dissolution was found to be important in spodumene flotation. In this study, we proposed to introduce ultrasound into the pretreatment process to accelerate particle vibration and cavitation, as well as the migration of mineral surface components to solution. Micro-flotation results showed that the flotation recovery of spodumene can be 86.08% by ultrasound pretreatment, but only 39.30% by traditional mechanical agitation pretreatment. Compared with traditional mechanical agitation, ultrasonic pretreatment can shorten the pretreatment process, reduce the dosage of agents, reduce the mechanical agitation speed, and improve the efficiency of the pretreating process. Inductively coupled plasma analysis showed that, in the ultrasonic system, the amount of Li, Al, and Si species in the solution was twice as much as those in the traditional preprocessing system. Moreover, the scanning electron microscope results demonstrated a larger surface dissolution area in the ultrasonic system. X-Ray photoelectron spectroscopy results showed that the atomic concentration of Si species on the spodumene surface decreased, whereas the relative atomic concentrations of Li and Al species increased, indicating that the ultrasound effect strengthened the selective dissolution of elements on the mineral surface. The high-resolution spectra of O 1s showed that more collectors are adsorbed on the mineral surface treated by ultrasonic pretreatment.

Recent progress in food‐grade double emulsions: Fabrication, stability, applications, and future trends

AbstractCompared with ordinary emulsions, the unique structures endow double emulsions with special functions, which makes them have broad prospects in delivering biologically active substances and replacing fats. In recent years, due to the instability of double emulsions, numerous experiments have been carried out on their preparation technology as well as stabilization methods. This review emphatically summarizes the research progress of double emulsions, including preparation techniques, factors affecting stability, stabilization mechanisms, and related applications. At present, in addition to the traditional mechanical agitation and ultrasonic emulsification, membrane emulsification, phase inversion, and microfluidic emulsification are the main research directions, all of which can improve the stability. Moreover, the stabilizer is also a crucial factor affecting the stability of the double emulsion. Hence, in this article emphasis is placed on surfactants, biopolymers, and solid particles. The applications of double emulsions in food industry can be divided into the following categories: encapsulating substances, controlling the release, and being served as fat substitutes. Furthermore, in the future, the main challenges are to commercialize the double emulsions and enhance their safety in food applications. Additionally, developing high internal phase Pickering double emulsions and O/W/O double emulsions may become the major research trends.

A sustainable emulsion for separation and Raman identification of microplastics and nanoplastics

The extensive occurrence of small plastic particles in the environment and our foods, and the resulting hazardous effects to nature and people have become an issue of increasing concern worldwide. The currently established approaches and tools for the elimination of the emerging contaminants, in particular micro- and nano-scale plastic particles, from environmental and food matrices have been often limited to the use of poorly sustainable materials and complicated preparation/operation. Here we show a conceptually new strategy for the removal of microplastics and nanoplastics using an olive oil-based emulsion. By emulsifying naturally occurring olive oil, water and emulsifiers at an oil-to-water ratio of 5:12, a stable O/W emulsion can be produced by mechanical agitation, which can adsorb onto microplastics and nanoplastics via hydrophobic interactions. Upon demulsification, interestingly, the tiny plastic particles can be enriched at an efficiency up to ∼87%, attributable to the affinity-driven encapsulation of the plastics by the merged oil phase. We further demonstrate the emulsion affords the removal of tiny plastic particles from seawater, tea leaves, soil and toothpaste supernatants at considerably low concentration levels in efficiencies of 75%, 80%, 83% and 82%, respectively, while preserving uncompromised performance. The identification of the extracted plastics has been achieved using Raman spectroscopy, which has implications in health risk assessment and clarification of the contamination route. Given the high removal efficiency, green feature and generality of the emulsion coupled with Raman fingerprints, sustainable materials for the depollution of microplastics and nanoplastics are within reach.

Investigation into the Rheological Properties and Microstructure of Silt/Crumb Rubber Compound-Modified Asphalt.

Near the coast of China, a large amount of sediment is produced during construction work. In order to mitigate the environmental damage caused by sediment and enhance the performance of rubber-modified asphalt effectively, solidified silt material and waste rubber were prepared to modify asphalt, and its macroscopic properties, such as viscosity and chemical composition, were determined via a routine physical test, DSR, Fourier Transform Infrared Spectroscopy (FTIR), and Fluorescence Microscopy (FM). The results show that, with the increase in powder particles and the addition of a certain amount of hardened mud, the mixing and compaction temperature of modified asphalt can be significantly increased-still reaching the design standard. In addition, the high thermal stability and fatigue resistance of the modified asphalt were clearly better than those of the ordinary asphalt. From the FTIR analysis, rubber particles and hardened silt only exhibited mechanical agitation with the asphalt. Considering that excessive silt might result in the aggregation of matrix asphalt, the addition of an appropriate amount of hardened solidified silt material can eliminate the aggregation. Therefore, the performance of modified asphalt was optimum when solidified silt was added. Our research can provide an effective theoretical basis and reference values for the practical application of compound-modified asphalt. Therefore, 6%HCS(6:4)-CRMA have better performance. Compared to ordinary rubber-modified asphalt, the composite-modified asphalt binder has better physical properties and a more suitable construction temperature. The composite-modified asphalt uses discarded rubber and silt as raw materials, which can effectively protect the environment. Meanwhile, the modified asphalt has excellent rheological properties and fatigue resistance.

Facile formulation of graphene oxide modified commercial polyurea grease and its enhanced tribological capability under extremely high contact stress

Grease lubricants have been widely applied to the rubbing components to increase the operation stability and reliability. In this study, graphene oxide modified polyurea grease was prepared by formulating different amounts of exfoliated expandable graphite (EG) into commercial polyurea grease with combined mechanical agitation and grinding processes, tribological characteristics of graphene oxide modified polyurea grease were subsequently evaluated under extremely higher contacting stress. Among all the formulated polyurea grease specimens, polyurea grease with 2.0 wt.% graphene oxide displays better capabilities of minimizing friction and wear. In particular, the wear loss reduces considerably by 80% meanwhile the averaged friction coefficient decreases to 0.10, as referenced with existing polyurea grease. The improved tribological behavior is proposed to be associated with the in‐situ produced graphene oxide solids that enhances extremely lower shearing ability and promotes the fatigue resistance of grease, as well as its desired chemical compatibility with resulting iron sulfide tribofilm. Particularly, graphene oxide works as the dispersed precipitate within the dense iron sulfide/oxide layer induced from ZDDP that covers on the steel substrate.

Effect of Simulated Transport Conditions on Microbiological Properties of Bottled Natural Mineral Water

Bottled mineral water is distributed globally through complex supply chains, making it available far beyond its bottling plants. In low-viscosity food matrices, invisible changes may occur due to shaking. The primary purpose of this research was to investigate the potential correlation between the intensity of mechanical agitation and the number of detectable microorganisms in bottled mineral water. The simulation of dynamic mechanical vibration was conducted using both time-accelerated and real-time tests. Freshly bottled natural mineral water and commercially available mineral water brands from different bottling locations and times were subjected to random vibration at three intensities as specified by the ASTM D-4169-16 standard, which simulates road transport on semi-trailer trucks. The study investigated the specific growth rate, the generation time, and the maximum cell numbers of microorganisms. The quantitative PCR (qPCR) technique was used to determine and compare the concentrations of microbes. Dynamic mechanical vibration affected the microbiome of mineral waters, influencing growth rates and generation times. In the case of waters from different bottling locations and times, the specific growth rate varied significantly for each water and for each intensity. This finding demonstrates that the microbiome composition of the water source and the interaction between microbes influence the response to mechanical impact. The time-accelerated test was shown to be suitable for analyzing the reaction of the microbiome of the tested matrix to the intensity and duration of vibration. The applied test protocol enabled the monitoring of changes in cell numbers by qPCR. All three intensities of the time-accelerated method were effective in testing the effects of real-time mechanical agitation on the microbiome.

Mechanical agitation triggered crystallization of eutectic phase change material xylitol/erythritol with persistent supercooling for controllable heat retrieval

Towards latent heat storage for days, or even extending to months in the context of solar energy utilization, the exploration of phase change materials (PCMs) with stable supercooling and the following crystallization triggering are carried out. The present work confirmed the persistent supercooling property of the xylitol/erythritol eutectic mixture. The coupled technique combining mechanical agitation with seeding was proposed to trigger crystallization, so as to facilitate the heat retrieval whenever heat is in demand. The xylitol/erythritol eutectic keeps supercooling state without crystallization at ambient temperature for at least 10 days, thus it can serve as applicable PCM for controllable heat retrieval. Such severe supercooling is mainly attributed to the particular molecular structure of polyalcohols and dramatic increase of dynamic viscosity. In particular, on the basis of secondary nucleation principle, the coupled technique combining mechanical agitation and seeding can be a preferable technique to efficiently trigger crystallization of the present eutectic PCM, so as to realize controllable heat retrieval. Such combined technique has main advantages of high efficiency and reproducible crystallization process. The agitation duration is shortened to 1.8 min with seeding, in comparison to a longer value of 43.3 min without seeding. Although the single technique of mechanical agitation can also trigger the crystallization, the agitation is found to be time-consuming and the triggered crystallization process is in poor consistency among parallel specimens. Furthermore, the crystallization initiating is greatly advanced with high agitation rate (300 r/min), and the agitation duration to sufficiently activate crystallization can be significantly shortened. The results suggest that appropriately high agitation rate favors the efficient heat retrieval. The obtained results are helpful to gain a better understanding on the supercooled PCMs based controllable heat retrieval.

Study on the Aging Mechanism of Down Fiber Under the Daily Washing and Drying Conditions

ABSTRACT In order to clarify the aging mechanism of down fiber under the daily washing and drying conditions, fluffiness, whiteness, microscopic morphology, crystallinity and molecular structure of down fiber after different washing and drying treatments were observed. Results showed that the daily washing conditions of weak acid or alkali (pH = 5–9) and drying conditions of low temperature drying (55°C and sunlight) only slightly affected fluffiness, whiteness, and microscopic morphology of down fiber. However, the addition of short-term mechanical agitation reduced damage and even improved fluffiness, whiteness. Additionally, down fiber did not experience chemical damage in the above environment. However, the strong alkali (pH = 10, pH = 12) washing environment and high temperature (105°C,155°C) drying treatment not only caused the decline of fluffiness, whiteness, microscopic morphology but also caused the change of crystallinity and molecular structure. Additionally, the stronger the alkalinity, the longer the time, the higher the drying temperature, the more obvious the performance decline. Moreover, regardless of the washing and drying conditions, mechanical agitation for a long time easily led to performance degradation. Therefore, down fibers were suitable for the daily washing conditions of weak acid and alkali (pH = 5–9) and drying conditions of low temperature drying (55°C or sunlight) with slightly mechanical agitation.

Develop an optimal washing and care mode for knapsack

In order to develop a suitable washing mode for knapsack, mechanical agitation (1), water bath vibration (2), ultrasonic (3), micro-nano bubble (4) and complex washing mode of the two were systematically investigated. Results showed that regardless of fabric, the washing efficiency of composite washing mode {mechanical agitation + ultrasonic (1 + 3), mechanical agitation + micro-nano bubble (1 + 4)}, was highest among all washing modes. Moreover, the decrease of stiffness, tensile strength, smoothness and micro-morphology of knapsack by using complex washing mode {mechanical agitation + ultrasonic (1 + 3), mechanical agitation + micro-nano bubble (1 + 4)} significantly lower than that of mechanical agitation. This indicated that mechanical agitation was the key to remove stain, micro-nano bubbles and ultrasound only assisted its removal. But the addition of micro-nano bubbles and ultrasound was helpful to improve the washing efficiency and reduce the performance degradation caused by washing mode of mechanical agitation. Complex washing mode {mechanical agitation + ultrasonic (1 + 3), mechanical agitation + micro-nano bubble (1 + 4)} was optimal washing combination for knapsack, especially the composite mode of mechanical agitation + ultrasonic (1 + 3), due to its ability to remove residual stains in the inner layer and slit. Moreover, the complex washing mode was also more environmental-friendly and sustainable, compared to other washing mode, because of washing time and detergent dosage reducing occurred by its high washing efficiency. The results were not only helpful to guide manufacturers of washing machine to develop a program dedicated to the daily washing and care knapsack, but also provided scientific care guidance and optimization ideas for subsequent research and applications.

Water flow induced piezoelectric polarization and sulfur vacancy boosting photocatalytic hydrogen peroxide evolution of cadmium sulfide nanorods

Piezo-photocatalytic H2O2 production utilizing earth-abundant solar and mechanical energies, oxygen and water is a highly appealing route to produce renewable energy carriers. However, piezoelectric polarization always suffers from high-frequency mechanical vibration, which severely restricts its actual applications. Here, we report prominent piezo-photocatalytic H2O2 evolution from pure water triggered by low-frequency water flow induced mechanical stress over 1D CdS nanorods with sulfur vacancy (CdS NRs). The polar CdS NRs possess benign piezoelectric property and favorable morphology, enabling high sensitivity and respond to weak force of water flow, which contribute to yielding large piezoelectric polarization for photogenerated charges separation. Piezoelectric polarization also shows an inhibition effect on the photocorrosion of CdS to ·SO3-. Besides, DFT calculations demonstrate that sulfur vacancy allows enhanced O2 adsorption and formation of the intermediate *OOH on the surface of CdS. Under simultaneous visible light and high-speed stirring, CdS NRs display a remarkably synergetic piezo-photocatalytic H2O2 production (1631.4 µmol g−1 h−1) without any sacrificial agents, 2.4 and 73.8 times of that under sole visible light and mechanical agitation, respectively. Importantly, it achieves an apparent quantum efficiency (AQY) of 1.32% at wavelength up to 500 nm and a solar-to-chemical (STC) conversion efficiency of 0.05% under one-sun illumination, which far exceeds other reported sulfide-based catalysts. This work integrates well with polarization engineering, defect engineering and morphology engineering to enhance catalytic behavior, providing a feasible strategy for designing efficient piezo-photocatalysts sensitive to weak mechanical forces.

Nanocomposites Produced with the Addition of Carbon Nanotubes Dispersed on the Surface of Cement Particles Using Different Non-Aqueous Media

The inclusion of carbon nanotubes (CNTs) in cementitious composites has been studied due to their electrical, thermal, and mechanical enhancing properties. Considering the hydrophobic characteristics of CNTs, these nanomaterials need to be well dispersed in the aqueous media in which they are inserted to guarantee those gains. Among the methods applied to produce such composites is the dispersion of CNTs on the surface of anhydrous cement particles using non-aqueous suspensions such as acetone, ethanol, or isopropanol. Even though those non-aqueous media have been individually studied by researchers, comparisons of the efficiency of CNTs dispersion was not found in the literature. Therefore, as a novelty, the present article aims to analyze the influence of the addition of the multi-walled CNTs dispersed in the cited three types of non-aqueous suspensions on the cement paste’s electrical and mechanical properties. Pastes containing 0%, 0.5%, and 1.0% of CNTs were prepared on the surface of anhydrous cement particles using a pre-dispersion technique based on simultaneous sonication and mechanical agitation in the three cited media. Tests to determine electric-volumetric resistivity, compressive strength, and splitting tensile strength were performed. It was observed that acetone dispersion decreases the cement paste’s electrical resistivity, even without the addition of CNTs. The cementitious composites with CNTs demonstrated increased mechanical strength (both compressive and tensile) using all three dispersion media. Statistical analysis (analysis of variance—ANOVA—and Tukey’s Test) was performed to evaluate the significance of the results.

ZIF-8 Assisted Polyacrylamide Functionalized Silica Core-Shell Stationary Phase for Hydrophilic Interaction Liquid Chromatography

A novel ZIF-8 assisted polyacrylamide functionalized silica polar stationary phase was prepared by a facile method of adding ZIF-8 nanoparticles and silica into polyacrylamide (PAM) aqueous solution, and then stirring the mixture until the solution was evaporated absolutely with the help of mechanical agitator. Interestingly, the prepared stationary phase (PAM-Sil@ZIF-8/PAM) showed favorable hydrophilicity, as demonstrated by good separation performance and strong retention ability toward several types of polar compounds, such as amino acids, saccharides, and alkaloids. In addition, PAM-Sil@ZIF-8(50 mg)/PAM showed better separation performance compared with amino-modified silica and Sil/PAM stationary phase due to the addition of ZIF-8. Furthermore, it was demonstrated that the addition of ZIF-8 improved the specific surface area and provided extra interaction sites for the stationary phase and analytes, which is beneficial for the separation of samples. In addition, the column efficiency can reach 7861.9 plates/m for colchicine. Moreover, it exhibited good stability and reproducibility under our operation conditions. In short, a novel stationary phase, which can be used for hydrophilic interaction liquid chromatography, was obtained and proved that the separation performance of polymer modifying silica stationary phase can be greatly improved by the addition of MOF nanoparticles.

Decellularization of Mouse Kidneys to Generate an Extracellular Matrix Gel for Human Induced Pluripotent Stem Cell Derived Renal Organoids

Chronic Kidney Disease (CKD) is a major cause of morbidity and mortality characterized by progressive renal fibrosis, and in extreme cases, renal failure. Human CKD models that replicate the biological complexity of the kidney and CKD are lacking and will be invaluable in identifying drugs to revert and/or prevent fibrosis. To address this unmet need, we developed 3D renal organoids where human induced pluripotent stem cells (hiPSCs) were differentiated to renal progenitors within a renal extracellular matrix (rECM) gel, based on the premise that an rECM could recreate the renal niche to facilitate hiPSC-derived renal progenitor generation. We used mouse kidneys as a source of rECM and identified that superior detergent-mediated decellularization of mouse kidneys was achieved with a combination of 0.5% w/v Sodium Dodecyl Sulphate and 1% v/v Triton-X and mechanical agitation for 60 h. HiPSCs that underwent specification to become metanephric mesenchyme (MM) were subsequently cultured within the rECM gel and, notably, mesenchymal to epithelial transition (MET) was observed, as judged by expression of nephron markers K-cadherin, Nephrin and WT1. These data demonstrate a role for rECM gel in developing human renal organoids from hiPSCs, which will aid the further development of a human disease model for renal fibrosis.

Piezoelectric Metal-Organic Frameworks Mediated Mechanoredox Borylation and Arylation Reactions by Ball Milling.

Herein, metal-organic frameworks UiO-66 and UiO-66-NH2 were synthesized, and their piezoelectric properties were characterized by piezoresponse force microscopy. Under mechanical agitation, the highly polarized UiO-66 and UiO-66-NH2 can act as electron donors to reduce aryl diazonium salts, forming the aryl radical species, which further react with bis(pinacolato)diborane or heteroarenes to generate the desired products with broad substrate scope. For all substrates, it was found that the reactions mediated by UiO-66-NH2 , which exhibited better piezoelectric property, were more efficient than those promoted by UiO-66. Moreover, it was shown that the convenient regeneration of spent catalysts can be reused for promoting mechanoredox reactions without loss of activities by taking advantage of the unmatched repairability of metal-organic frameworks. Mechanistic studies revealed that a radical pathway was involved in these transformations.

Comparison of the Effect of Mechanical and Ultrasonic Agitation on the Properties of Electrodeposited Ni-Co/ZrO2 Composite Coatings

Ni-Co/ZrO2 composite coatings were fabricated by electrochemical deposition from sulfamate solutions containing zirconia nanoparticles. The main purpose of this research was to evaluate the effect of mechanical stirring and ultrasonic agitation in plating solutions on the structure and properties of Ni-Co/ZrO2 composite coatings. The morphology, microstructure, microhardness, anti-corrosion and wear resistance of the composites were investigated via scanning electron microscopy, X-ray diffraction, Vickers microhardness testing, electrochemical workstation utilization and friction wear testing. The hardness, friction coefficient, wear loss, corrosion rate of the composite coating prepared with mechanical stirring, and ultrasonic agitation were 533 and 680 HV; 0.40 ± 0.02 and 0.35 ± 0.02; 2.15 × 10−5; 0.85 × 10−5 g·m−1; and 0.36 and 0.07 mm/year, respectively. In comparison to mechanical stirring, ultrasonic agitation could more uniformly disperse the zirconia nanoparticles to obtain Ni-Co/ZrO2 composite coatings, which has simplicity and compactness.

The Internal Structure of the Velvet Worm Projectile Slime: A Small-Angle Scattering Study.

For prey capture and defense, velvet worms eject an adhesive slime which has been established as a model system for recyclable complex liquids. Triggered by mechanical agitation, the liquid bio-adhesive rapidly transitions into solid fibers. In order to understand this mechanoresponsive behavior, here, the nanostructural organization of slime components are studied using small-angle scattering with neutrons and X-rays. The scattering intensities are successfully described with a three-component model accounting for proteins of two dominant molecular weight fractions and nanoscale globules. In contrast to the previous assumption that high molecular weight proteins-the presumed building blocks of the fiber core-are contained in the nanoglobules, it is found that the majority of slime proteins exist freely in solution. Only less than 10% of the slime proteins are contained in the nanoglobules, necessitating a reassessment of their function in fiber formation. Comparing scattering data of slime re-hydrated with light and heavy water reveals that the majority of lipids in slime are contained in the nanoglobules with homogeneous distribution. Vibrating mechanical impact under exclusion of air neither leads to formation of fibers nor alters the bulk structure of slime significantly, suggesting that interfacial phenomena and directional shearing are required for fiberformation.

Generation and properties of organic colloids extracted by water from the organic horizon of a boreal forest soil

Organic colloids are an important part of dissolved organic matter (DOM) yet many of their properties remain elusive. The main aims of this study were to assess how the colloidal properties of DOM extracted with water from an organic boreal soil horizon varied with the extraction protocol, and thereby provide insight into the nature of the DOM colloids and develop a mechanistic understanding of how the colloids were generated from the parent soil aggregates. This was accomplished by systematic variations of extraction temperature (4 °C–100 °C), time, mechanical agitation, and pH, together with a combination of chemical analyses, and light and X-ray scattering. Our results agreed with the previous identification of two main colloidal DOM species, one fractal cluster and a second, smaller colloidal DOM species described as chains or coils. Fractal clusters completely dominated the colloidal DOM in extracts from our soil at room temperature and below. Colloidal coils only existed in DOM extracted above room temperature, and their amount increased significantly between 50 °C–100 °C. Moreover, the temperature variation indicated that the fractal clusters partly dissolved into colloidal coils at elevated temperatures. Mechanical agitation at 4 °C significantly increased the amount of DOM extracted, increasing the concentrations of both fractal clusters and low-molecular weight organic compounds. While the clusters were extracted from agitated and non-agitated soil suspensions, the low molecular weight organics were mainly released by agitation. Based on the experimental observations, we propose a conceptual model where parent soil aggregates contain the fractal clusters in mobile and occluded forms, and that the occluded clusters co-exist with occluded low molecular weight organics. These occluded forms may be released by mechanical forces, increasing pH and temperature. At higher temperatures, the soil aggregates and the fractal clusters start to break up, and subsequently individual colloidal coils, presumably carbohydrates, disperse in the water phase. The model explains the origin and properties of the fractal clusters that completely dominate the colloidal DOM extracted from our soil at room temperature and below.