Changes In Particle Size Distribution Research Articles

Irrigation-Initiated Changes in Physicochemical Properties of the Calcisols of the Northern Part of Fergana Valley

Agriculture in Central Asia and in the Fergana Valley in general strongly depends on irrigation and drainage of agricultural lands. The Fergana Valley includes about 45% of the irrigated area in the Syr Darya River basin. Active use of irrigation in agriculture can lead to changes in the soil’s natural composition, as well as pollution and changes in the soil’s physical and chemical properties. Soil degradation in the process of irrigation can lead to a decrease in crop yields and, as a consequence, to a decrease in food security in the region. In this study, a comparative analysis of three main types of Calcisols (Dark, Light, and Typical) before (uncultivated soil) and after agricultural use (surface-irrigated agricultural soil) was carried out. Irrigation leads to increment of SOC stocks in Typical (from 113.8 to 126.3 t/ha) and Light (from 62.8 to 100.1 t/ha) Calcisols and to decreasing of SOC stocks in Dark Calcisols (from 160.1 to 175.3 t/ha). In general, the content of biophilic elements (SOC and TN) is lower in irrigated soils, and their distribution in the soil profile is close to the functional relationship (r2 0.98 to 0.99). In uncultivated Calcisols, the profile distribution of SOC and TN is more heterogeneous (r2 0.67 to 0.97). Changes in the humification processes of soil organic matter are also identified; in soils after irrigation the carbon ratio of humic/fulvic acids (CHA/CFA) is lower (<1) compared to their uncultivated counterparts (~1). The alteration of the soil water regime also resulted in transformation of the individual compositions of amino acids. All studied types of Calcisols are characterized by changes in particle-size distribution of soils especially in the number of the silt fraction (0.01–0.05 mm) and the difference between uncultivated and irrigated soils, 10–20%, which is associated with the processes of colmatage by accumulation of a fine fraction and replacement of sub-fractions in the fraction of sand. The highest concentrations of nutrients are characteristic of the upper soil horizons (P up to 231, K up to 2350 mg/kg), which indicate their pedogenic and agrogenic origins rather than inheritance from the parent material. Soil P and K availability is rather high, with non-labile forms prevailing, although of near reserve. The surface irrigation results in apparent accumulation of water-soluble Mg2+ (1.6–2.1 meq/100 g) and K+ (0.6–0.9 meq/100 g), but the cation of Ca2+ predominates in the base cations’ composition, which is the most favorable in terms of soil agrogenic property formation. Data obtained will be useful for development of strategies for effective land use in arid, subtropical, overpopulated regions of Central Asia that have deficient water sources and intensive soil degradation.

Influence of chemical pretreatment on the pozzolanicity of recycled glass microparticles used as a substitute for Portland cement

This research investigated the influence of using chemically treated glass microparticles as a partial replacement for cement in Portland cement pastes and mortars. The microparticles were obtained by grinding glass waste into three different particle size fractions (< 75 µm, < 45 µm, and < 25 µm), treated with calcium hydroxide (CH), and characterized using SEM/EDS and a laser particle size analyzer. Samples prepared with the incorporation of glass were characterized using XRD, TGA/DTG, and SEM/EDS. The pretreatment with calcium hydroxide induced the formation of C-S-H with different morphologies on the surface of the particles, in addition to causing changes in particle size distribution due to the formation of agglomerates. The pastes prepared with treated particles had lower amounts of CH and higher levels of hydrated silicates. However, when indirectly measuring the pozzolanicity of treated particles through the compressive strength of mortars, no significant differences were observed in the strengths of mortars made with treated and untreated particles.

Characterization of Respirable Coal Mine Dust Recovered from Fibrous Polyvinyl Chloride Filters by Scanning Electron Microscopy

The characterization of respirable dust on the basis of constituent fractions and particle sizes is increasingly of concern for evaluating exposure hazards. For high-resolution particle analysis, scanning electron microscopy with energy dispersive X-ray (SEM-EDX) can be an effective tool. However, it requires particles to be deposited on a smooth, uniform substrate such as a polycarbonate (PC) filter for optimal results. While direct sampling onto PC is possible, this is not the standard approach in many situations. For example, in coal mines, respirable dust samples have typically been collected onto polyvinyl chloride (PVC) filters because they are intended for gravimetric and/or infrared spectroscopy analysis. Such fibrous substrates are not ideal for SEM-EDX (or other microscopy), but an effective method to recover and redeposit the dust particles could render such samples suitable for the additional analysis. Here, we present a simple method and compare SEM-EDX results for paired samples analyzed directly on PC and following recovery from PVC and redeposition on PC. Both laboratory-generated dust samples (n = 10 pairs) and field samples of respirable coal mine dust (n = 44 pairs) are included in this study. Although some changes in particle size distributions were observed between samples analyzed directly and those that were recovered and redeposited prior to analysis, the results indicate the dust recovery method generally yields a representative sample in terms of mineral constituents. That said, results also highlighted the effects of high particle loading density on individual particle analysis. Considering all sample pairs, those with similar loading density between the directly analyzed and recovered sample tended to exhibit similar mineralogy distributions. This was generally the case for the lab-generated sample pairs, and the Freeman-Halton exact test of independence indicated that the samples in just three (of 10) pairs were in disagreement in terms of their mineralogy distributions. On the other hand, for the field samples, the directly analyzed sample often had higher loading density than the recovered sample; and the Freeman-Halton test showed that 25 (of 44) pairs were in disagreement. However, the effect of possible particle agglomeration on the directly analyzed samples cannot be ruled out—and exploration of this factor was beyond the scope of the current study.

An Image-based method for evaluating changes in particle size and morphology distributions of aggregate materials after vibratory compaction test

Particle breakage and abrasion of aggregate materials can be induced by field compaction during construction, which adversely affects their mechanical properties. However, current compaction quality control testing does not evaluate changes in particle size distribution and particle morphology of aggregate materials due to the lack of fast and inexpensive testing methods. In this study, a modified watershed-based segmentation image analysis method and computational geometry algorithms were used to quickly quantify changes in particle size and morphology distributions of a large amount of contacting aggregate particles. The accuracy and required minimum sample size of the image analysis method were statistically evaluated. Compared to the conventional ASTM C136 aggregate sieve analysis test, the image analysis method conducted on a 40% sample size of the conventional method yielded less than 6% difference between the results, which can meet the ASTM C136 test repeatability criteria. In addition, demonstration tests were conducted to incorporate the image analysis method into a laboratory vibratory compaction test for evaluating the overall particle size and morphology changes of an aggregate material after compaction. Results indicate that the initial gradation and water content of the aggregate material can influence the particle breakage and abrasion characteristics of aggregate materials under compaction.

The Effect of Heat- and Salt Treatment on the Stability and Rheological Properties of Chickpea Protein-Stabilized Emulsions

The aim of the study was to evaluate the effect of heat- (95 °C) and/or salt (0.1 M NaCl) treatment on the physical stability and rheological properties of oil-in-water emulsions stabilized with chickpea protein concentrates (CPCs) for various purposes. Thus, the particle size distribution (PSD), shear behavior, and long-term Turbiscan stability of the prepared emulsions were examined. The oscillatory (dynamic) measurements were also performed to obtain information on the viscoelasticity of tested fluids during thermal treatment. The obtained results indicated that the emulsion stabilized with gelling CPC (eCg) was Newtonian fluid with a homogeneous structure, but susceptible to creaming. Heat-treated eCg exhibited a sol–gel transition at 86 °C and formed fine-stranded aggregates without affecting stability. In turn, heat-induced gelation of eCg in the presence of 0.1 M NaCl resulted in the formation of an aggregated, spatial gel network, stabilization of the system, and a significant change in both shear rheological properties and PSD. Contrariwise, emulsions stabilized with standard CPC (eCs) were unstable heterogeneous systems containing both fine particles < 1 μm and coarse particles of about 100 μm, exhibiting shear-thinning and yield stress. The heat-induced viscoelasticity of eCs was reversible, while heat- and salt-treated emulsions did not form a gel.

Marine Fuel Regulations and Engine Emissions: Impacts on Physicochemical Properties, Cloud Activity and Emission Factors

AbstractMarine regulations aim to reduce sulfur and nitrogen exhaust emissions from maritime shipping. Here, two compliance pathways for reducing sulfur dioxide emissions, fuel sulfur content reduction and exhaust wet scrubbing, are studied for their effects on physicochemical properties and cloud forming abilities of engine exhaust particles. A test‐bed diesel engine was utilized to study fresh exhaust emissions from combustion of non‐compliant, high sulfur content fuel with (WS) and without (HiS) the usage of a wet scrubber as well as a regulatory compliant, low sulfur content fuel (LoS). Particle number emissions are decreased by ≈99% when switching to LoS due to absence of 20–30 nm sulfate rich particles. While number emissions for WS are also decreased, a shift in the sulfate mode toward larger sizes was found to increase particle mass emission factors by at least 31%. Changes in the mixing state induced by the compliance measures are reflected in the hygroscopicity of the exhaust particles. Fuel sulfur reduction decreased cloud condensation nuclei emissions by at least 97% due to emissions of primarily hydrophobic soot particles. Wet scrubbing increased those emissions, mainly driven by changes in particle size distributions. Our results indicate that both compliance alternatives have no obvious impact on the ice forming abilities of 200 nm exhaust particles. These detailed results are relevant for atmospheric processes and might be useful input parameters for cloud‐resolving models to investigate ship aerosol‐cloud interactions and to quantify the impact of shipping on radiative budgets from local to global scales.

Enhancing the Grinding Efficiency of a Magnetite Second-Stage Mill through Ceramic Ball Optimization: From Laboratory to Industrial Applications

Ceramic ball milling has demonstrated remarkable energy-saving efficiency in industrial applications. However, there is a pressing need to enhance the grinding efficiency for coarse particles. This paper introduces a novel method of combining media primarily using ceramic balls supplemented with an appropriate proportion of steel balls. Three grinding media approaches, including the utilization of steel balls, ceramic balls, and a hybrid combination, were investigated. Through an analysis of the grinding kinetics and the R–R particle size characteristic formulas, the study compares the breakage rate and particle size distribution changes for the three setups. The results indicate that employing binary media effectively improves the grinding efficiency for +0.3 mm coarse particles while maintaining the energy-saving advantages of ceramic ball milling. Simultaneously, the uniformity of the ground product is ensured. This proposed approach has been successfully validated in industrial applications, providing robust theoretical support for the expansion of ceramic ball milling applications.

Changes in some quality properties of frozen mare milk during 6 months of storage

The aim of this study was to determine how storage in the frozen state affects the quality of mare milk. Therefore, physicochemical properties such as pH, total dissolved solids (TDS), electrical conductivity (EC), particle size distribution and near-infrared (NIR) spectroscopy, as well as changes in antioxidant activity and the total phenol content were determined during 6 months of storage at -18°C. All of the determined parameters were compared to those in raw mare milk prior to freezing. According to the obtained results, frozen storage caused certain changes in mare milk quality, including increase in pH, electrical conductivity and TDS values, changes in protein structure recorded by NIR spectroscopy and SDS PAGE (Sodium dodecyl sulfate-polyacrylamide gel electrophoresis), as well as changes in particle size distribution. There was also a continuous decrease in the antioxidant activity and the total phenol content of frozen mare milk throughout the 6 months of frozen storage. Thus, after 6 months of frozen storage, a decrease in the DPPH value of approximately 59%, in the FRAP value of approximately 26% and in the TPC of approximately 70% was observed, respectively. In conclusion, freezing and frozen storage affected the quality of mare milk, which might have negative consequences on its therapeutic value.

Experimental study on the failure of loose accumulation landslides under rainfall conditions

Rainfall plays a pivotal role in triggering the failure of loose accumulation landslides. To understand their stability, it is essential to explore the deformation, failure patterns, fine particle migration, and infiltration behavior of such landslides under rainy conditions. Employing the Yuqiupo landslide as a case study, this research dissects the fundamental attributes of the Yuqiupo landslide through geological examinations. Moreover, the study replicates the failure of the loose accumulation landslide via artificial rainfall experiments. By employing acquired data on soil volumetric water content and matrix suction from these experiments and observing measurable shifts in the landslide’s failure progression and rainfall circumstances, the water-hydraulic conditions of the accumulation landslide are meticulously dissected. The conducted experiments disclose that the failure of the loose accumulation landslide emanates from the combined effects of preferential flow and matrix flow within unsaturated conditions. Rainfall triggers an elevation in soil moisture content and a concurrent decrease in matrix suction, compromising the slope’s stability and ultimately causing the landslide. Furthermore, our research includes a quantitative analysis of changes in particle size distribution before and after the landslide’s failure. This endeavor underscores the influence of distinct failure modes on the migration of fine particles, with these migration patterns distinctly shaped by prevailing rainfall conditions.

Analysis of product properties in counter-current spray drying with two nozzles system

Results of the experiments on drying of skin-forming material sprayed with two nozzles in counter-current pilot spray dryer are presented in the article. Phase Doppler Anemometry (PDA) measurements were conducted above, between, and below two nozzles spraying upward and downward which allowed us to track changes of particle size distribution (PSD) and particle velocities in the tower for different nozzle configurations. The analysis of PSD shows that for two nozzles pointing downwards, the drying zone was observed under the lower nozzle whereas the agglomeration zone develops between nozzles. For the upward orientation of the lower nozzle, a zone of simultaneous drying and agglomeration forms between the nozzles. Analysis of product moisture content, PSD, and bulk density showed the effect of nozzle configuration on product properties.

Influence of Supercritical Carbon Dioxide on the Activity and Conformational Changes of α-Amylase, Lipase, and Peroxidase in the Solid State Using White Wheat Flour as an Example.

Green technologies using renewable and alternative sources, including supercritical carbon dioxide (sc-CO2), are becoming a priority for researchers in a variety of fields, including the control of enzyme activity which, among other applications, is extremely important in the food industry. Namely, extending shelf life of e.g., flour could be reached by tuning the present enzymes activity. In this study, the effect of different sc-CO2 conditions such as temperature (35-50 °C), pressure (200 bar and 300 bar), and exposure time (1-6 h) on the inactivation and structural changes of α-amylase, lipase, and horseradish peroxidase (POD) from white wheat flour and native enzymes was investigated. The total protein (TPC) content and residual activities of the enzymes were determined by standard spectrophotometric methods, while the changes in the secondary structures of the enzymes were determined by circular dichroism spectrometry (CD). The present work is therefore concerned for the first time with the study of the stability and structural changes of the enzyme molecules dominant in white wheat flour under sc-CO2 conditions at different pressures and temperatures. In addition, the changes in aggregation or dissociation of the enzyme molecules were investigated based on the changes in particle size distribution and ζ-potential. The results of the activity assays showed a decrease in the activity of native POD and lipase under optimal exposure conditions (6 h and 50 °C; and 1 h and 50 °C) by 22% and 16%, respectively. In contrast, no significant changes were observed in α-amylase activity. Consequently, analysis of the CD spectra of POD and lipase confirmed a significant effect on secondary structure damage (changes in α-helix, β-sheet, and β-turn content), whereas the secondary structure of α-amylase retained its original configuration. Moreover, the changes in particle size distribution and ζ-potential showed a significant effect of sc-CO2 treatment on the aggregation and dissociation of the selected enzymes. The results of this study confirm that sc-CO2 technology can be effectively used as an environmentally friendly technology to control the activity of major flour enzymes by altering their structures.

Innovative Nanosuspension Formulation for Prochlorperazine and In-vitro Evaluation

Prochlorperazine is a dopamine antagonist and is used to control nausea and vomiting. It is a BCS class II drug which has low aqueous solubility and high permeability. The present study is aimed to formulate and evaluate prochlorperazine nanosuspension to improve solubility and enhance dissolution of Prochlorperazine with varying concentrations of stabilizers such as Tween 80, PVP K30, Poloxamer 188 by using nanoprecipitation method. The developed formulations were characterized for particle size and polydispersity index, total drug content, SEM, Zeta Potential and FTIR. The invitro drug release studies and invitro drug release kinetics were performed for all formulations. FTIR studies revealed that drug is compatible with the excipients. The particle size and poly dispersity index of optimized formulation was found to be 162nm and the zeta potential was found to be -30.2 mV and concluded that the system had sufficient stability. The invitro drug release was found within their acceptable ranges. The rate of dissolution of best batch was enhanced to 93.24 in 120min. Stability studies proved that nanosuspensions were more stable with no significant changes in particle size distribution. Thus the formulated nanosuspension of prochlorperazine offers a superior conventional dosage forms for drug release
 Keywords: Prochlorperazine, Nanosuspension, Solubility, Dissolution

Effect of Reaction Temperature on the Degradation and Oxidation Behavior of Particulate Matter by Nonthermal Plasma

Diesel particulate matter (PM), especially small particle size PM, has been highlighted as a hazard to the environment and people. Nonthermal plasma (NTP) has shown significant low temperature (<200°C) advantage for PM degradation. In this paper, we conducted online PM degradation experiments at different reaction temperatures with a self-built NTP injection system to investigate the changes of PM particle size distribution, micro-nano structure, graphitization degree and oxidation characteristics of elemental carbon (EC) before and after NTP action. The maximum removal rate increased from 90 ℃ (25% load) to 130 ℃ (100% load) with the increase of the load, and there was a “trade-off” effect between PM decomposition and NTP pyrolysis. The average microcrystalline length, microcrystalline spacing and microcrystalline curvature of PM particles showed an overall trend of decreasing and then increasing with the increase of temperature. When the reaction temperature was 130 ℃ (75% load), the microcrystalline structure parameters of the carbon particles showed extreme values, and the newly exposed “shells” were rearranged under the action of van der Waals force, and the graphitization of PM increased and the overall oxidation activity was weakened. The reaction between NTP and carbon particles goes through the process of surface oxidation, simultaneous oxidation of surface and interior, and the fragmentation of carbon particles to complete disappearance.

Application of the Hough Transform to Dispersion Control of Overlapping Particles and Their Agglomerates

The dispersion control of micro- and nanoparticles by their images is of great importance for ensuring the specified properties of the particles themselves and materials based on them. The aim of this article was to consider the possibilities of using the Hough transform for dispersion control of overlapping particles and their agglomerates. Analysis of the application of the Hough transform for overlapping particles and their agglomerates showed the following. The particularities of the conventional implementation lead to the preferred registration of large particles, the shift of the centers of overlapping particles, and the distortion of the size values. To use the Hough transform correctly, fine-tuning of all its parameters is required. To automate this process, the dependences of the number and size of particles recorded in the image on the parameters of the Hough transform was investigated. The studies were carried out on test images with a known number and size of particles. The results showed that when the threshold parameters of the Hough transform change, the number of detected particles stabilizes near their optimal values. When the size range of particles detected by the Hough transform changes, the histogram of the particle size distribution changes. In this case, the optimal width of the range is determined by the most stable extremes of the histogram. The maximum center-to-center distance is set at least half of the optimal range. The configuration algorithm is described and implemented. It implies repeatedly running the Hough transform with different combinations of parameters. The algorithm includes stages of coarse and fine-tuning, which allows to getting closer to the optimal parameters. The efficiency of the algorithm has been confirmed on test and real images. Tests have shown that the errors in determining the size and number of particles of the multi-pass Hough transform are on the same level or exceed these indicators for analog methods.

Enhanced sequestration of CO2 from simulated electrolytic aluminum flue gas by modified red mud

The aluminum industry is facing severe economic and environmental problems due to increasing carbon emissions and growing stockpiles of red mud (RM). RM is a strongly alkaline, high-emission solid waste from the alumina industry with potential for CO2 sequestration. However, the effectiveness of RM carbon sequestration is poor, and the mechanism behind it is not well understood. In this study, the effect of microwave and tube furnace activation of RM on CO2 sequestration in alumina was first investigated at different temperatures. The result showed that the CO2 sequestration capacity of unmodified RM (URM) was only 14.35 mg/g at ambient temperature and pressure, and the CO2 sequestration capacity could be increased to 52.89 mg/g after high-temperature activation and modification. Besides, high-temperature activation and modification will effectively improve the carbon sequestration capacity of RM. The carbonized RM was characterized by FT-IR, SEM, XRD, laser particle size, TG-DSC, and pH measurements. In addition, the mechanism of RM capturing CO2 was also proposed, which shows that CO2 was finally sequestered in the RM as CaCO3. The change in particle size distribution and the mineral phase in the RM indicated that high-temperature activation modification positively affects the application of RM to the sequestration of CO2. This study can provide a promising technology for the low-carbon and green development of the aluminum industry, as well as achieving the waste treatment and utilization objective.

Efficient Synthesis of Submicrometer‐Sized Active Pharmaceuticals by Laser Fragmentation in a Liquid‐Jet Passage Reactor with Minimum Degradation

AbstractOne challenge in the development of new drug formulations is overcoming their low solubility in relevant aqueous media. Reducing the particle size of drug powders to a few hundred nanometers is a well‐known method that leads to an increase in solubility due to an elevated total surface area. However, state‐of‐the‐art comminution techniques like cryo‐milling suffer from degradation and contamination of the drugs, particularly when sub‐micrometer diameters are aspired that require long processing times. In this work, picosecond‐pulsed laser fragmentation in liquids (LFL) of dispersed drug particles in a liquid‐jet passage reactor is used as a wear‐free comminution technique using the hydrophobic oral model drugs naproxen, prednisolone, ketoconazole, and megestrol acetate. Particle size and morphology of the drug particles are characterized using scanning electron microscopy (SEM) and changes in particle size distributions upon irradiation are quantified using an analytical centrifuge. The findings highlight the superior fragmentation efficiency of the liquid‐jet passage reactor setup, with a 100 times higher fraction of submicrometer particles (SMP) of the drugs compared to the batch control, which enhances solubility and goes along with minimal chemical degradation (&lt;1%), determined by attenuated total reflection‐Fourier transform infrared spectroscopy (ATR‐FTIR), high‐performance liquid chromatography (HPLC), and X‐ray diffraction (XRD). Moreover, the underlying predominantly photo‐mechanically induced laser fragmentation mechanisms of organic microparticles (MP) are discussed.

Studies on the Functional Properties of Titanium Dioxide Nanoparticles Distributed in Silyl-Alkyl Bridged Polyaniline-Based Nanofluids.

In the present work, a new kind of nanocomposite (NC)-based solid component was prepared for formulating nanofluids (NFs). The NC comprised metal oxide (titanium dioxide, TiO2) dispersed in a conducting polymer with polyaniline (PANI) and chemically linked silyl-alkyl units in it (PSA) that were designated as T-PSA NC. The NFs with ethylene glycol (EG) as a base fluid were prepared with T-PSA NCs with various compositions of TiO2 and PSA as well for various concentrations of T-PSA NCs. The scanning electron microscopic evaluation of the NC revealed that PSA deposition on TiO2 nanoparticles (NPs) decreased particle agglomeration. The PSA coating on the TiO2 NPs did not influence the crystalline structure of the TiO2 NPs, according to the X-ray diffraction patterns. The thermophysical characterization and molecular interaction features of the NFs at 303 K including a novel inorganic-organic T-PSA NC, were detailed. Furthermore, the stability of the T-PSA NC-based NFs was investigated experimentally using the zeta potential, and the particle size distribution change was analyzed using the dynamic light scattering (DLS) method. The T-PSA NCs had particle sizes that were significantly bigger than pristine PSA and pure TiO2. Most of the preparation conditions used to produce the T-PSA NCs resulted in moderately stable suspensions in EG. The results revealed that the ultrasonic velocity increased with the increase in the concentration of T-PSA NC mass % in the NFs, the refractive index and thermal conductivity increased with the increase in the concentration, and the surface tension exhibited a linear change when the ratio of mass % concentration of the T-PSA NCs increased. The combined presence of components that synergistically contribute to the electro, thermal, optical, and rheological properties is expected to attract advanced applications for NFs.

Thixotropy of superplasticized cement pastes – Underlying mechanisms considering the polycarboxylate molecular structure, interparticle interactions and hydration kinetics

This paper deals with the decisive mechanisms of thixotropic structural build-up in superplasticized cement-based suspensions related to the PCE molecular structure. We investigate the effect of the side chain length and anionic charge ratio of tailored PCE superplasticizers on thixotropic structural build-up under quantitative consideration of colloidal and contact interactions as well as very early hydration kinetics. The thixotropic structural build-up of superplasticized cement pastes with systematically varying the PCE molecular structure was investigated at constant workability, i.e. dynamic yield stress, by adjusting the individual PCE dosage. Thixotropy was quantified using plate-plate rheometry, while at the same time superplasticizer adsorption, specific surface area, granulometric measurements and quantitative XRD analysis provided an experimental basis for the identification of the respective contribution to the structural build-up.Our results show that the thixotropic structural build-up increases with decreasing PCE side chain length and increasing anionic charge ratio. This is due to accelerated very early hydration kinetics, causing an increase in the specific surface area. The latter is primarily attributed to ettringite, modifying the particle size distribution of the hydrated cement paste. Our approach of separating the colloidal and contact interactions indicates that the PCE-induced change in particle size distribution due to accelerated ettringite formation as well as the change in the average effective layer thickness are the dominant mechanisms for the thixotropic structural build-up in this context.

The role of abrasion in cyclically sheared soil–structure interfaces

A limiting factor in the drive to deliver performance-based design is the lack of knowledge regarding the constitutive behaviour of soil–structure interfaces, particularly in the case of cyclic loading. A series of experiments was undertaken using both a traditional interface shear apparatus (shearing a large body of soil grains over a structural interface) and a novel single-particle interface shear apparatus (involving shearing a single grain over a structural interface). In both cases the soil was sheared across the interface in a cyclical manner (more than 1500 cycles per test). For the traditional apparatus, a clear change in soil particle size distribution and abrasive wear of the structural interface occurs after many cycles. This change results in a significant increase of the interface friction ratio, which is the main parameter used in traditional design – increasing from approximately 0·2 (11°) to 0·7 (35°). The single-particle apparatus validated the results – where a significant increase in the friction ratio after many cycles was also observed. The novel interface behaviour presented in this paper may lead to improved interface constitutive models and consequently more economic and safer geotechnical designs.

The formation of high CO2 loading solid phase from 1,4-butanediamine/ethylene glycol biphasic solvent: Phase-changing behavior and mechanism

Liquid-solid phase change absorption has been considered a promising strategy for CO2 capture. To achieve efficient and economic CO2 capture in industrial-scale applications, it is essential to understand the phase-change behaviors and mechanisms of the biphasic system. In this study, a blend of 1, 4-Butanediamine (BDA) and ethylene glycol (EG) was developed as a biphasic solvent that can form a high CO2 loading solid phase product (BESP) after absorption. The total solvent loading reached 0.9039 mol·mol−1, with 90.74% of the loading enriched in the solid phase, which only accounts for 51.01% of the total solvent mass. Based on the 13C NMR analysis and quantum chemical calculations, the reaction and phase change mechanism of CO2 capture was proposed. The BDA/EG system absorbs CO2 to generate carbamate species, protonated amines and alkyl-carbonates, which combine each other through hydrogen bonding or electrostatic attraction. The self-aggregation of zwitterions and the high polarity of the absorption products are considered to be the main reasons for the phase change. Alkyl-carbonate species are believed to co-precipitate through organic gelation via van der Waals force with the carbamate or protonated amine. Moreover, the viscosity, turbidity, solid-phase mass, and particle size distribution changes also demonstrate the growth and aggregation of particles during absorption. BESP, identified as a coupling product of carbamate and alkyl-carbonate ([2BDAH+COO-]·[EG‐OCO2-]), decomposes at a peak temperature of 127.4 °C. The calorimetric method determined regeneration heat to be approximately 3.17 GJ·ton-1 CO2, indicating its potential for alternative uses rather than direct heat regeneration. Such a biphasic solvent may provide unique solutions for industries to reduce CO2 emissions.