Granular Properties Research Articles

Structure stability and shear failure behaviors of asphalt mixtures from the perspective of aggregate particle migration

Shear deformation of asphalt mixtures is the macroscale accumulation of aggregate migration, addressing excessive aggregate slip and rotational migrations can reduce shear failure. In this research, the slip failure and torsional failure tests were introduced to achieve targeted investigations using developed instruments. Deformation resistance of the asphalt mixture was analyzed from the granular properties. The results indicate that shear energy is dissipated by structural self-organization induced by aggregate migration. Coarse gradation and complex aggregate morphology enhance the structure stability. The shear failure threshold resulting from aggregate slip exceeds that of rotation over fourfold. The packing coefficient (PC) and the critical moment of inertia (IC) were proposed to evaluate the slip and rotation resistances of asphalt mixtures, the indicators show good parabolic and linear relationships with the peak forces of slip and rotation as gradation changes, which can be illustrated by the interfacial friction and the spatial hindrance provided by the aggregate morphologies of texture and form. Finally, the findings were validated by the discrete element method.

Scaling laws of plume-induced granular cratering.

Extraterrestrial landing often requires firing a high-speed plume towards a planetary surface, and the resulting gas-granular interactions pose potential hazards to the lander. To investigate these jet-induced cratering dynamics, an experiment campaign covering a range of gas and granular properties relevant to the lunar and Martian environments was conducted in a large-scale vacuum chamber. Despite the variations in jet Mach number, mass flow rate, and composition of the granular phase investigated in this work, the observed time evolution of crater depth displays a consistent transition from an early-stage linear to a late-stage sublinear growth. To explain these scaling relations, a model that relates the kinetic energy gained by the particles per unit time to the power of the impinging jet is introduced. From this model, erosion rates and the critical depth at which the transition occurs can be extracted, and they are shown to depend on the gas impingement pressure, which was varied by changing ambient pressure, jet Mach number, mass flow rate, and nozzle height above the surface. These results highlight key mechanisms at work in the dynamics of plume-induced cratering and help to develop an understanding of optimal rocket engine firing times for future landings.

Impacts of granular sludge properties on the bioreactor performing nitrate/nitrite-dependent anaerobic methane oxidation/anammox processes

In this work, a bioprocess model was applied to first determine the impacts of influent substrates conditions on the granular bioreactor performing nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) and anammox integrated processes and then investigate the roles of granular sludge properties in regulating the bioreactor performance and start-up process. The ideal influent substrates conditions were identified at NO2−-N/NH4+-N of 1:1 and dissolved CH4 concentration of 85 g COD m−3, which achieved 98.6% total nitrogen removal and 87.7% dissolved CH4 utilization. Under such ideal influent conditions, the initial properties of granular sludge didn’t significantly affect the granular bioreactor performance. However, inoculation of granular sludge with a relatively small granular sludge size and a high abundance of n-DAMO archaea or/and anammox bacteria could effectively shorten the bioreactor start-up. Meanwhile, reducing the diffusivity of solutes within granular sludge was also beneficial for expediting the start-up process and promoting dissolved CH4 utilization.

Vododržnost hydrických skupin lesních půd v České republice

Forest soil moisture limits (hydrolimits) suggest variation in soil water availability for tree species. In this study, we focused on estimations of soil hydrolimits using multiple regression with grain size, Corg, pH/H2O and cation exchange capacity (CEC) in the overlays between forest site georelief and bedrock in the Czech Republic. The multiple regression parameters were optimized in a system of 615 pits from case studies in 32 natural forest areas during 2002–2020. Light anhydromorphic soils were characterized by a decrease in hydrolimits with a profile depth, while hydrolimit values were higher at greater depths in hydromorphic soils. The dependences of hydrolimits on the granularity and forest soil physico-chemical properties were closer in the subsurface horizons than in the top ones. Higher correlations suggested that the hydrolimit increase appears to be more easily achievable in subsurface soil horizons by stimulating variable contents of Corg and CEC. On the other hand, the dependence of hydrolimits on variable soil properties suggested sensitivity to environmental changes affecting ecosystems.

Cementation anisotropy associated with microbially induced calcium-carbonate precipitation and its treatment effect on calcareous and quartz sands

Microbially induced calcium-carbonate precipitation (MICP) can help cement sand particles together and has emerged as a promising alternative to traditional ground-improvement treatments for granular soils. Owing to precipitation and absorption in different directions, MICP leads to anisotropic cementation. This study was aimed at examining the mechanism of cementation anisotropy and its treatment effect on two commonly used granular soils in geotechnical engineering: quartz sand and calcareous sand. A novel MICP technique was used to prepare bio-cemented sand specimens with different anisotropic patterns of cementation. Microscopic detection techniques were applied to examine the microstructure of the produced MICP cementation. The cementation in the vertical and horizontal directions was different, owing to gravity. The granular surface properties affected the content, morphology, and cement force of the bio-cements produced by MICP treatment. The results of unconfined compression strength experiments confirmed the occurrence of cementation anisotropy and its substantial effects on the stiffness, strength, and fracture patterns of MICP-treated quartz sand and calcareous sand. These findings can help to clarify the formation mechanism of bio-cements and promote the optimised application of MICP for the treatment of granular soils.

Performance of an aerobic granular sludge membrane filtration in a full-scale industrial plant.

This study quantifies the hydraulic performance of a pilot-scale ultrafiltration system integrated into a full-scale industrial aerobic granular sludge (AGS) plant. The treatment plant consisted of parallel AGS reactors, Bio1 and Bio2, with similar initial granular sludge properties. During the 3-month filtration test, a chemical oxygen demand (COD) overloading episode took place, affecting the settling properties, morphology, and microbial community composition in both reactors. The impact on Bio2 was more severe than on Bio1, with higher maximal sludge volume index values, a complete loss of granulation, and the excessive appearance of filamentous bacteria extending from the flocs. The membrane filtration properties of both sludges, with these different sludge qualities, were compared. The permeability in Bio1 varied between 190.8 ± 23.3 and 158.9 ± 19.2 L·m-2·h-1·bar-1, which was 50% higher than in Bio2 (89.9 ± 5.8 L·m-2·h-1·bar-1). A lab-scale filtration experiment using a flux-step protocol showed a lower fouling rate for Bio1 in comparison with Bio2. The membrane resistance due to pore blocking was three times higher in Bio2 than in Bio1. This study shows the positive impact of granular biomass on the long-term membrane filtration properties and stresses the importance of granular sludge stability during reactor operation.

Documenting heritage language experience using questionnaires.

There exists a great degree of variability in the documentation of multilingual experience across different instruments. The present paper contributes to the "methods turn" and individual differences focus in (heritage) bilingualism by proposing a comprehensive online questionnaire building on existing questionnaires and the experience of using them to document heritage bilingualism: the Heritage Language Experience (HeLEx) online questionnaire. HeLEx is validated against and contrasted to an extended version of the Language and Social Background Questionnaire designed for heritage speakers (HSs), LSBQ-H. We compare data elicited with both questionnaires in turn from a group of Turkish HSs (n = 174, mean age=32). Our validation focuses on traditional language background variables, including language exposure and use, language proficiency, language dominance, as well as a more novel measure of language entropy. The analyses are based on a subset of key questions from each questionnaire that capture language experience for up to five languages, four modalities, and five social contexts. In a subsequent set of analyses, we explore the impact of different types of response scales, response mechanisms, and manners of variable derivation on the informativity of the data they can provide, in terms of the scope, granularity and distributional properties of the derived measures. Our results show that both HeLEx and LSBQ-H are successful at detecting the important distributional patterns in the data and reveal a number of advantages of HeLEx. In the discussion, we consider the impact of methodological choices regarding question phrasing, visual format, response options, and response mechanisms. We emphasize that these choices are not trivial and can affect the derived measures and subsequent analyses on the impact of individual differences on language acquisition and processing.

An efficient approach for improving granular cold water soluble starch properties using energetic neutral atoms treatment and NaOH/urea solution

The granular cold water soluble starch (GCWSS) was prepared from energetic neutral (EN) atoms treated kithul starch using the alkali/urea aqueous solution, and their properties were analysed. During preparation, significant morphological changes in the starch granules by cold plasma treatment facilitated the diffusion of alkali/urea solution. The plasma treatment induced a change from the A-type allomorph to a more amorphous structure, and the structural changes of GCWSS from cold plasma-treated starch improved their cold water solubility. The GCWSS from the kithul starch sample treated at 20W (EN-20W) exhibited the lowest amylose content, and their oil absorption capacity, moisture absorption and enzymolysis were considerably improved. The effect of alkali/urea solution on the plasma-treated starch decreased the storage modulus (G′), loss modulus (G″) and complex viscosity (Ƞ*) of GCWSS, representing their poor gelation due to lower retrogradation. The decrease in hardness and higher freeze-thaw stability and paste clarity also indicated their inferior ageing property. Therefore, this research provides an understanding of the use of EN atom treatment prior to the GCWSS preparation using the alkali/urea system.

AC/TiO2 granular photocatalysts optical properties: Material composition effect on the radiative transfer in a photoreactor

The radiative transfer analysis in photoreactor with heterogeneous media is still a challenge for reasons relative to solid particles structural complexity or materials complex optical properties. This article aims to study the radiative transfer in a photoreactor containing Activated-Carbon/Titanium Dioxide (AC/TiO2) composite particulate media. A focus was made on the analysis of the photon rate absorbed by these media, which is a key value for the further study of chemical photo-reaction for which they are intended into the system. The radiative properties of these media were first consistently defined using different mixing laws for refractive index calculation, coupled to Mie theory. A validation of the radiative properties was achieved by solving the radiative transfer equation using a Monte Carlo algorithm and by comparing the results of transmittance modelling of each media with transmittance experiments. The second part of the work consisted in the use of a second Monte Carlo algorithm for modelling local radiant energy repartition in the studied photoreactor and access the rate of energy absorbed. These parameters are some key tools for the description and the assessment of reactions in a defined photoreactor. An originality of the study comes from the wide range of AC/TiO2 composition studied through the work which allows to analyze the evolution of the radiative properties, radiant energy repartition and rate of energy absorbed as a function of the AC/TiO2 material composition.

Influence of Microgel and Interstitial Matrix Compositions on Granular Hydrogel Composite Properties.

Granular hydrogels are an emerging class of biomaterials formed by jamming hydrogel microparticles (i.e., microgels). These materials have many advantageous properties that can be tailored through microgel design and extent of packing. To enhance the range of properties, granular composites can be formed with a hydrogel interstitial matrix between the packed microgels, allowing for material flow and then stabilization after crosslinking. This approach allows for distinct compartments (i.e., microgels and interstitial space) with varied properties to engineer complex material behaviors. However, a thorough investigation of how the compositions and ratios of microgels and interstitial matrices influence material properties has not been performed. Herein, granular hydrogel composites are fabricated by combining fragmented hyaluronic acid (HA) microgels with interstitial matrices consisting of photocrosslinkable HA. Microgels of varying compressive moduli (10-70kPa) are combined with interstitial matrices (0-30vol.%) with compressive moduli varying from 2-120kPa. Granular composite structure (confocal imaging), mechanics (local and bulk), flow behavior (rheology), and printability are thoroughly assessed. Lastly, variations in the interstitial matrix chemistry (covalent vs guest-host) and microgel degradability are investigated. Overall, this study describes the influence of granular composite composition on structure and mechanical properties of granular hydrogels towards informed designs for future applications.

Investigation of the influence of bitumen emulsion and Reclaimed Asphalt Pavement content on the mechanical properties of Bitumen Stabilised Materials with high fine particle content

Cold recycling technology is gaining popularity as an economically and environmentally effective way of pavement rehabilitation. The main benefits of the use of cold recycling mixtures (CRMs) in road base courses are associated with the reduction of raw materials consumption by replacing them with recycled materials such as Reclaimed Asphalt Pavement (RAP), as well as the decrease in energy consumption during production and paving compared to Hot Mix Asphalt (HMA). Bitumen Stabilised Materials (BSMs), described as non-continuously bound CRMs, exhibit granular and viscoelastic materials properties due to the presence of local bituminous bonds and a reduced amount of cement. Their mechanical properties are still being investigated.In this paper, Bitumen Stabilised Materials with bitumen emulsion (BSM-E) were investigated. Mixtures characterised by high fine particle content and designed with different Reclaimed Asphalt Pavement (RAP) and bitumen emulsion contents were subjected to Indirect Tensile Strength (ITS) tests at 25°C. TSR water resistance parameter for the mixtures was calculated. Test results were analysed using two-way ANOVA statistical tests.The laboratory test results showed that BSM-E mixtures exhibited different trends of an increase in ITSdry, ITSwet and TSR values as a function of bitumen emulsion content, depending on the RAP amount used. The statistical significance of the effects of bitumen emulsion content, RAP content, and the interaction between these two factors on the tested ITS values was proven.

Granular structure, physicochemical and rheological characteristics of starch from yellow cassava (Manihot esculenta) genotypes

ABSTRACT This study examined the structural and physicochemical characteristics of starch isolated from seven yellow cassava genotypes. The structural properties of yellow cassava starch from these cultivars were elucidated by scanning electron microscopy, X-ray diffractometry and Fourier Transformed Infrared Spectroscopy (FTIR). Their water interaction properties, digestibility and viscoelastic behavior were also compared, and principal component analysis was used to establish factors associated with the variability in properties of the starch. All the starches were of the A-type diffraction pattern, with crystallinity ranging between 31 and 37%. Most of the granules exhibited spherical and oval shapes, some with a flat surface on one side. They had smooth surfaces and their sizes ranged from 4 µm for round granules to 23 µm for the major axis of oval-shaped granules. Significant differences (p < .05) were observed in amylose content, in-vitro digestibility, peak and breakdown viscosity of the starches, and these ranged between 13.6–18.1%, 11.4–18.5%, 354–520 BU and 233–366 BU, respectively. Significant differences were also recorded in the hydration and textural behavior of starches from these cassava cultivars. The differences observed in granular and physicochemical properties are likely to influence the performance of these cassava cultivars in food applications.

Improving anammox performance by limited filamentous bulking for wastewater treatment with organic stress

In this study, the filamentous bulking was demonstrated to improve anammox capability and anammox bacteria (AnAOB) population density under organic stress. The selective heterotrophic bacteria (HB) washout that involved in shear detachment, enmeshment and biomass washout was triggered. The microbial spatial distribution and granular detachment properties revealed that the filamentous bulking transferred the “location advantage” of HB from granules interior to surface, and endowed granular surface low shear tolerance for shear detachment, ultimately resulted in selective HB detachment. The detached filaments-mediated enmeshment provided additional selective pressure for free HB-flocs, eventually achieving the retention time differentiation between AnAOB (34 – 141 days) and HB (3 – 15 days), and a high anammox population density. Controlling dissolved oxygen level was crucial for regulating sludge bulking. Collectively, the filamentous bulking was developed as an effective anti-organic stress strategy to broaden the application of granular anammox process in actual wastewater treatment.

Improving the biomass retention and system stability of the anammox EGSB reactor by adding a calcium silicate hydrate functional material

Improving the biomass retention and the sludge system stability to promote the full-scale application of anammox process is the focus of current related research. In this study, a calcium silicate hydrate functional material with calcium-releasing ability and weak alkalinity was used for an enhanced anammox process. In the long-term operation, an increase in the nitrogen removal rate (NRR) from 2.75 to 13.38 gN/L/d was achieved after 50 days of operation, with the abundance of Candidatus Kuenenia increased from 40.1 % to 47.0 %. The anammox activity was strengthened from 0.089 to 0.55 gN/gVSS/d over 50 days, with a growth rate being fitted at 0.0310 d−1. The resilience of the EGSB anammox system after inhibitions was investigated by substrate shock and low pH shock in long-term operation and batch test. Besides that, the phosphorus removal efficiency of the reactor reached up to 90 % under the positive effect of functional material. The functional material was shown to continuously provide calcium in the long-term for the reaction of hydroxyapatite (HAP) formation, which further improved the granular properties of the sludge and the biomass retention ability of the reactor. The promotion effect of functional material on the sludge granulation and anammox microbes retaining efficiency was the key for a high-resilience anammox EGSB reactor.

Efficacy of Csaba stain to demonstrate mature and immature mast cells in oral inflammatory lesions: An in-vitro study.

Mast cells (MCs) are immune cells of the myeloid lineage and are present in connective tissues throughout the body. Mastocytosis regulates many physiologic processes and affects the pathogenesis of allergic conditions, anaphylactic reactions, autoimmune disorders and leukemias. Toluidine blue is commonly employed as a special stain for MCs that uniformly imparts blue color to both immature and mature cells. Csaba stain that distinguishes mature from immature MCs has not been widely explored. However, its use in differentiating mature and immature cells has not been reported in the literature. The identification of mature and immature MCs may provide a major clue for the diagnosis of any unrecognized systemic pathologies. To evaluate the staining efficacy of Csaba stain, toluidine blue and Leishman's stains in the identification of MCsTo compare the effectiveness of Csaba stain, toluidine blue and Leishman's stains to identify MCs in inflammatory pathologic lesions. Fifty sections of inflammatory lesions were subjected to Csaba stain, toluidine blue and Leishman's stains each for studying MCs. The staining efficacy of the three stains was compared for parameters such as homogeneity, specificity, staining intensity, granular staining property and differentiation between mature and immature cells. The Csaba, toluidine blue and Leishman's stains showed statistically insignificant P = 0.50, 0.95, 0.29, 0.48 for homogeneity, specificity, staining intensity and granular staining property respectively, but Csaba stain showed statistically significant P = 0.0001* in differentiating mature from immature cells. Csaba stain is more effective in differentiating mature from immature MCs compared to the other special stains.

Freeze‐Thawing Assisted Preparation of Acid‐Hydrolyzed Starch: Microstructure and Physicochemical Properties

AbstractThe modification of starch by a single freeze‐thawing process and acid hydrolysis has been reported, while the combination of freeze‐thawing and acid hydrolysis on the microstructure and physicochemical properties is unknown. The present study investigates the supporting effect of freeze‐thawing pretreatment by comparing single modifications with the corresponding freeze‐thawing assisted acid hydrolyzed starch in terms of granular, physicochemical, and thermal properties. Starch samples treated by combined treatment show the most severe damage on the surface and the oil adsorptive capacity is enhanced from 69.7% to 109.4%. In addition, the solubility of starch granules is notably improved by 35.9% and the swelling power decreases by 39.7% via the combined treatment, respectively. The results of Fourier transform infrared spectroscopy and X‐ray diffraction indicate that in comparison with native corn starch, the chemical groups of modified starch processed by combined treatment are not altered, while the relative crystallinity significantly increases from 31.4% to 33.9%. Significant changes in the thermal effects are attributed to molecular rearrangements after hydrolysis of amylose in the amorphous regions. Therefore, the combined treatment would be an efficient and useful method to prepare functional starch.

Formation mechanisms of fracture plugging zone and optimization of plugging particles

As formation mechanisms of plugging zone and criteria for fracture plugging remain unclear, plugging experiments and methods testing granular material mechanical properties are used to study the formation process of the plugging zone in fractured formations, analyze composition and ratios of different sizes of particles in the plugging zone, and reveal the essence and driving energy of the formation and damage of the plugging zone. New criteria for selecting lost circulation materials are proposed. The research results show that the formation of the plugging zone has undergone a process from inertial flow, elastic flow, to quasi-static flow. The plugging zone is composed of fracture mouth plugging particles, bridging particles and filling particles, and the proportion of the three types of particles is an important basis for designing drilling fluid loss control formula. The essence of the construction of the plugging zone is non-equilibrium Jamming phase transition. The response of the plugging zone particle system to pressure is driven by entropy force; the greater the entropy, the more stable the plugging zone. Lost circulation control formula optimized according to the new criteria has better plugging effect than the formula made according to conventional plugging rules and effectively improves the pressure-bearing capacity of the plugging zone. The research results provide a theoretical and technical basis for the lost circulation control of fractured formations.

The slope of dry granular materials surface is generally curved

As if it has become a consensus that the slope of the granular heap is straight, and from that, an angle of repose is defined. However, closer inspection shows that the slopes are not truly straight, instead, more often they have convex shapes, although with small convexity. Similar curvature is observed on the sand dunes' surfaces. We derive equations together with experiments on 10 types of granular materials to show that, in general, the slope of the granular heap is convex while the straight slope is a critical state that rarely occurs. The angle of repose is allowed to vary within a narrow range around a critical value. If the angle of repose is slightly greater (smaller) than the critical value, the slope is convex (concave). The model also answers why the surfaces of granular heaps, including sand dunes, are more often convex rather than concave or straight, and advocate the simultaneous estimation of the coefficient of friction on the grain and the type of packing in the heap. The results might open new understandings related to granular material properties as well as sand transport and geological records in several deserts.

Internal deformation monitoring of granular material using intelligent aggregate

Particle motion is the critical factor leading to the internal deformation of granular materials. However, relying on conventional techniques to monitor particle motion in internal deformation of granular materials has limitations. This study presents a novel method to monitor the internal movement of granular materials using intelligent aggregate. The intelligent aggregate packaging structure is fabricated through industrial CT technology and 3D printing. The six position method and fast fourier transform method are used to eliminate the measurement error caused by the packaging structure and the rutting tester vibration noise respectively. The results show that intelligent aggregate could maintain good linkage with surrounding aggregates under load, and the fine aggregates have a greater impact on the stability of the coarse aggregate skeleton. This method based on intelligent aggregates provides a basic technology for further real-time monitoring of granular material properties.

Partisan residential sorting on climate change risk

Is climate change partisanship reflected in residential decisions? Comparing individual properties in the same zip code with similar elevation and proximity to the coast, houses exposed to sea level rise (SLR) are increasingly more likely to be owned by Republicans and less likely to be owned by Democrats. We find a partisan residency gap for even moderately SLR exposed properties of more than 5 percentage points, which has more than doubled over the past six years. Findings are unchanged controlling flexibly for other individual demographics and a variety of granular property characteristics, including the value of the home. Residential sorting manifests among owners regardless of occupancy, but not among renters, and is driven by long-run SLR exposure but not current flood risk. Anticipatory sorting on climate change suggests that households that are most likely to vote against climate friendly policies and least likely to adapt may ultimately bear the burden of climate change.