Bulk Density Distribution Research Articles

Preparation of tenofovir amibufenamide fumarate spherical particles to improve tableting performance and sticking propensity by designing a spherical crystallization process

Tenofovir amibufenamide fumarate (TMF) is the first oral drug developed in Asia for the treatment of adult patients with chronic viral hepatitis B, however, further applications are limited by poor tableting performance and high sticking propensity. In this work, the spherulitic growth process of TMF has been designed and explored with the help of molecular dynamics simulation and process analysis technologies (ATR-FTIR, FBRM and EasyViewer). The spherical particles with high bulk density, good flowability and uniform particle size distribution are prepared by a simple quenching process. More importantly, experimental results show that spherical particles have higher average tensile strength (100.8% increase), higher plastic deformability and lower amount of punch sticking (87.4% decrease in 30 tablets) compared to the commercial powder products. These contributions not only shed light on the design principle of drug spherulitic growth processes, but also provide guidance for the manufacture of high-quality tablet products.

Spatial Variability in Soil Water-Physical Properties in Southern Subtropical Forests of China

Quantification of soil water-physical properties and their spatial variation is important to better predict soil structure and functioning, as well as associated spatial patterns in the vegetation. The provision of site-specific soil data further facilitates the implementation of enhanced land use and management practices. Using geostatistical methods, this study quantified the spatial distribution of soil bulk density (SBD), soil moisture (SM), capillary water-holding capacity (CWHC), capillary porosity (CP), non-capillary porosity (NCP), and total porosity (TP) in southern subtropical forests located at the Tropical Forest Research Center in Pingxiang City, China. A topographic map (scale = 1:10,000) was used to create a grid of l km squares across the study area. At the intersections of the grid squares, the described soil water-physical properties were measured. By calculating the coefficient of variation for each soil water-physical property, all measured soil water-physical properties were found to show moderate spatial heterogeneity. Exponential, gaussian, spherical, and linear models were used to fit the semivariograms of the measured soil water-physical properties. Across all soil water-physical properties, the range A0 variable (i.e., the separation distance between the semivariance and the sill value) measured between 3419 m and 14,156 m. The nugget-to-sill ratio ranged from 9 to 41%, indicating variations in the level of spatial autocorrelation among the soil water-physical properties. Many of the soil water-physical properties were strongly correlated (as assessed using Pearson correlation coefficients). Spatial distribution maps of the soil water-physical properties created via ordinary kriging (OK) showed that most water-physical properties had clumped (aggregated) distributions. SBD showed the opposite spatial pattern to SM and CWHC. Meanwhile, CP and TP showed similar distributions.

Mechanical Resistance to Penetration for Improved Diagnosis of Soil Compaction at Grazing and Forest Sites

Penetrometers and penetrographers are widely used to measure soil resistance to penetration, but the results are associated with other soil properties (such as bulk density, water content, and particle size distribution). Thus, for an adequate interpretation of results, site-specific studies are necessary to identify which properties are more related to soil resistance. We aimed to measure the resistance to penetration of a Typic Paleudalf under distinct soil uses and to identify soil properties that influence soil resistance. The soil uses in this study included anthropized forest (composed of tree and shrub species), pasture (5-year-old pasture), Eucalyptus 20 (a 20-year-old Eucalyptus saligna stand), and Eucalyptus 4.5 (a 4.5-year-old Eucalyptus saligna under the second rotation). Soil resistance to penetration was measured with an impact penetrometer, and the data were correlated with other physical and mechanical properties of soil, such as the particle size, soil moisture, air permeability, saturated hydraulic conductivity, porosity, bulk density, precompression stress, and compressibility index. We observed that a resistance of 1.3 MPa matches with other soil property values corresponding to soil compaction, and values greater than 1.3 MPa were verified at depths of 0–8 cm for pasture and 8–30 cm for Eucalyptus 4.5. Analyzing all soil uses together, the correlation was significant (p < 0.05) with gravel (r = 0.34), silt (r = −0.32), clay (r = 0.26), gravimetric moisture (r = −0.27), macroporosity (r = 0.24), and soil bulk density at the end of the compressibility test (r = 0.27). The penetrometer is useful for evaluating the physical conditions of soil, but we highlight that soil resistance is influenced by factors such as particle size and soil moisture, as examples. We recommend using a set of soil properties for a better interpretation of penetration resistance data and to support decision-making regarding soil management.

A Practicable Guideline for Predicting the Thermal Conductivity of Unconsolidated Soils

For large infrastructure projects, such as high-voltage underground cables or for evaluating the very shallow geothermal potential (vSGP) of small-scale horizontal geothermal systems, large-scale geothermal collector systems (LSCs), and fifth generation low temperature district heating and cooling networks (5GDHC), the thermal conductivity (λ) of the subsurface is a decisive soil parameter in terms of dimensioning and design. In the planning phase, when direct measurements of the thermal conductivity are not yet available or possible, λ must therefore often be estimated. Various empirical literature models can be used for this purpose, based on the knowledge of bulk density, moisture content, and grain size distribution. In this study, selected models were validated using 59 series of thermal conductivity measurements performed on soil samples taken from different sites in Germany. By considering different soil texture and moisture categories, a practicable guideline in the form of a decision tree, employed by empirical models to calculate the thermal conductivity of unconsolidated soils, was developed. The Hu et al. (2001) model showed the smallest deviations from the measured values for clayey and silty soils, with an RMSE value of 0.20 W/(m∙K). The Markert et al. (2017) model was determined to be the best-fitting model for sandy soils, with an RMSE value of 0.29 W/(m∙K).

A newly revised estimation of bulk densities and examination of the shape of individual Ryugu grains

The bulk density of grains from a celestial body is a fundamental property related to its composition and structure, contributing to the understanding of its evolutionary history. In this study, we provide the bulk density of 637 grains returned from the C-type near-Earth asteroid 162173 Ryugu. This is the largest number of grains to date for the curation activity, corresponding to 38 wt.% of the total returned samples (approximately 5.4 g). Although several densities of the Ryugu grains were reported, the volume estimation of some samples showed uncertainties. Therefore, we applied a new volume estimation model calibrated by X-ray micro-computed tomography (XCT) to the Ryugu grains to more accurately estimate their bulk density. The obtained average bulk density of 637 Ryugu grains was 1.79 ± 0.31 g/cm3 (1σ variation) for weights of 0.5‒100 mg (sub-mm ‒to 10 mm) irrespective of their 3D shapes characterized by three axial length ratios, considered to be a representative of the returned samples. The bulk density distributions of the grains in Chambers A and C were statistically distinguishable, with mean values of 1.81 ± 0.30 and 1.76 ± 0.33 g/cm3 (1σ variations), respectively. Despite the small difference, bulk density may have differed by sampling site. The obtained average bulk density value of A + C samples was almost the same as that of 16 Ryugu grains estimated based on CT scanned data, and was consistent with the densities of CI chondrites (1.57–1.91 g/cm3). The axial ratios of the grains in Chambers A and C were similar and those of the 724 returned samples and the flying particles ejected during the sampling operations were also similar, suggesting that relatively small Ryugu materials (mm‒cm in size) are similar in shape. The minor difference between the Rygu grains and flying particles could be attributed to events such as scraping during sampling operations and transportation.Graphical

Effect on Physico-chemical Properties of Soil under Various Land Use Planning of Kanpur Nagar, U.P., India

A research work conducted during 2020-21 at various land use planning of Kanpur Nagar (U.P.) to evaluate the fertility status of various land use planning on soil physico-chemical characteristics. The 504 representative soil samples with 3 depths viz. 0-15, 15-30 and 30-60 cm soil samples were taken with manually driven post hole auger and processed for soil analysis from different land use planning of Kanpur Nagar. Results revealed that physico-chemical properties viz. Bulk density, pH, Electrical Conductivity (E.C.), organic carbon (O.C.) varied vertically and horizontally in cultivated and fallow lands. The frequency distribution of soil bulk density of entire lands ranged 1.14 – 1.43 Mgm-3 and soil chemical properties, like, pH ranged from 7.1-8.9, the E.C. is found in ranged from 0.33 – 0.97 dS m-1. While organic carbon was ranged from 0.21- 0.68%.

Bentonite buffer under high temperature: laboratory experiments and coupled process modeling

Abstract. Bentonite buffer in a geological repository will be simultaneously heated from decaying radioactive waste and hydrated from the surrounding host rock, triggering complex and coupled THMC (thermal–hydrological–mechanical–chemical) processes. Understanding the THMC behavior of bentonite-based engineered barrier system (EBS) is key to the evaluation and prediction of its long-term performance. Studies on the THMC process have been focused on conditions under 100 ∘C, as most design concepts impose a thermal limit of 100 ∘C in bentonite. Recently, studies under high-temperature conditions have been conducted to evaluate the possibility of raising the thermal limit and expanding the data/knowledge base to increase the confidence level. In this abstract, we present a series of bench-scale laboratory experiments at high temperatures (up to 200 ∘C) and the corresponding modeling work. Two sets of column tests were conducted, and each set consisted of two test columns: a control column undergoing only hydration (non-heated) and an experiment column experiencing both heating and hydration (heated). During the experiment, frequent X-ray computed tomography (CT) images were collected to provide a 3D visualization of the density distribution and present the spatiotemporal evolution of (1) hydration/dehydration, (2) clay swelling/shrinkage, (3) displacement, and (4) mineral precipitation. The two sets of tests differ with respect to several experimental conditions, such as bentonite type, compacted density and water content, water chemistry, and hydration pressure, but the important difference is that the first set used bentonite powder with a dry density of 1.28 g cm−3, whereas the second set used granulated bentonite (mixture of pellets and powder) with a dry density of 1.45–1.5 g cm−3. In both sets of experiments, a comprehensive post-dismantling characterization of bentonite samples was carried out after the column tests had been running for 1.5 years. Comparing non-heated and heated columns, the temperature gradient led to lower degree of homogenization of bentonite after bentonite became fully saturated; comparing the first and second sets, granulated and powdered bentonite exhibited drastically different hydration behavior. A THM model with a 2D axisymmetric grid system was used to interpret the data from the first set of tests. The model considers the combined impact of saturation, fluid pressure, and porosity change due to swelling/compression on the spatiotemporal distribution of bulk density and movement of the thermocouple modules. Observations from the tests help us understand the early perturbation of bentonite buffer under high temperature, and data from these tests improve the calibration of key constitutive hydrological and mechanical models and, therefore, enhance the modeling capability with respect to calculating the long-term evolution of bentonite buffer.

SIMULATION OF THE PROCESS OF FORMING THE EDGE AND MIXING THE COMPONENTS OF THE COMPOST MIXTURE WITH A SINGLE-DRAMED AERATOR

The most widespread approach for implementing the technological process of organic compost production involves using mobile aerator-mixers of the rotary-drum type. Based on the analysis of various designs of mechanized composting equipment from previous theoretical and experimental studies conducted by renowned scientists, as well as our own research, it has been established that mechanized compost production requires further investigation. The analysis revealed that rotary drum-blade working elements are efficient. However, there is insufficient research on the dependencies of changes in the height of the pile during formation, indicators of homogeneity and structure of the mixture, energy consumption during the operation of drum-blade working elements in relation to the rotation frequency, working element's linear velocity, and geometric parameters of the blades. Additionally, changes in the bulk density, mixture structure, and temperature distribution within the pile under the influence of the working elements have not been investigated. This highlights the relevance of conducting research in the chosen direction. The analysis of developed models for the interaction of the working element with the compost mixture has shown that they cannot be used to assess the quality of mixing and pile formation, as it is necessary to consider the movement of discrete particles that make up the compost mixture. The mathematical description of the movement of discrete elements is achievable using modern CAE (Computer-Aided Engineering) systems, and one such system is Simcenter Star-CCM+. Through numerical simulation of the technological process of pile formation and mixture mixing, an argumentation of the constructive and technological parameters of the working element of a single-drum aerator was conducted. To construct the physical-mathematical model of the compost mixing and pile formation processes, the following mesh and physical models were utilized: meshless DEM (Discrete Element Method), solution interpolation, Lagrangian multiphase, unsteady implicit, DEM, multiphase interaction, gravity force, and boundary forces of DEM. As a result of simulating the compost mixture mixing process using a single-drum blade working element, dependencies of the height (H') and width (L') of the formed pile on the rotation frequency (n), linear velocity of the working element (V), and the blade's inclination angle (ξ) were established. A mathematical expression in the form of second-order regression equations was derived, linking the coefficient of variation of mixing quality (δ) with the research factors. Solving the compromise problem using the Wolfram Cloud software package allowed us to determine the rational parameters for the working element: rotation frequency (n) of 237 rpm, linear velocity (V) of 0.15 m/s, and blade inclination angle (ξ) of 15.8°. Consequently, the coefficient of variation of mixing quality (δ) was found to be 0.51, and the width (L') and height (H') of the formed pile were 1.23 m and 1.54 m, respectively.

Positive and Negative Impact of Nitrogen Fertilizer on Soil Properties and Nutrient Dynamic

Our study was conducted over the period of two years and explored the impact of nitrogen fertilization and non-fertilization systems on soil health indicators and crop yield. Our study hypothesized that no fertilization coupled with cover cropping would enhance soil health, carbon content, and bulk density. This study found that excessive nitrogen fertilization had negative impact on soil health factors such as bulk density increment and carbon content decline through deeper profiles. In contrast, the no-fertilization system exhibited improved bulk density and better carbon distribution near the soil surface, suggesting that reducing or eliminating nitrogen can promote soil health and prevent long-term fertility decline. The study also highlighted the imbalanced carbon to nitrogen ratio resulting from high nitrogen fertilizer rate can negatively impact soil microbial activity and nutrient mineralization.

Effect of Physico-Chemical Properties of Soil under Various Depths on Different Cropping Systems in Ayodhya, India

A research work conducted during 2018-19 at Agronomy farm of Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya (U.P.) to evaluate the fertility status and effect of different cropping systems on soil physico-chemical characteristics and their correlation. The 300 representative soil samples with 4 depths viz. 0-15, 15-30, 30-60 and 60-90 cm soil samples were taken with manually driven post hole auger and processed for soil analysis from different plots of Agronomy farm. Results revealed that physico-chemical properties viz. particle Density, bulk density pH, EC, organic corban, nitrogen phosphorus potassium Sulphur and zinc varied vertically and horizontally in cultivated and fallow lands. The soils were sandy loam, clay loam, loam and silt loam. The frequency distribution of soil bulk density of entire farm ranged from 1.128-1.58 Mgm-3, particle density ranged 2.50-2.76 Mgm-3 and soil chemical properties, like, pH ranged from 7.2-11.5, the E.C. is found in ranged from .13-1.01 dSm-1. While organic carbon was ranged from 1.4-6.70 g kg-1. and notable available Nitrogen in Agronomy farm was low in ranged from 170.15-221.36 kgha-1.The Phosphorus availability was found in ranged from 6.01-16.87 kgha-1 , while Potassium was found in ranged from 163.20-220.98 kgha-1. How ever the availability of Sulphur, was found in ranged from 8.62-18.32 kgha-1, Zinc ranged from in Agronomy farm 0.28-0.81mgkg-1. The significant positive correlation were observed among soil B.D with N, B.D with P, B.D with K, B.D with S, P.D. with S, P.D. with Zn. While the significant negative correlations were observed among PD with O.C., Zn with P, Zn with K and Zn with S in whole Agronomy Farm.

Experimental and numerical analysis of the hygric performance of earthen buildings after façade hydrophobization treatment

Earth is used extensively for buildings worldwide, as its thermal properties contribute to a favorable indoor thermal environment. However, earthen materials are sensitive to moisture ingress, which can result in structural damage and undesirable indoor humidity conditions. Through hydrophobization treatment, the capillarity of earth can be significantly reduced while hygroscopicity remains largely unchanged, thereby possibly improving the hygric performance of earthen buildings. In the present study, experiments and simulations were conducted to investigate the effect of hydrophobization on earthen materials and buildings. The experimental results show that the bulk density, open porosity, and pore-size distribution of rammed earth changed by only a few percent after hydrophobization treatment. The thermal properties (thermal conductivity, specific heat capacity, solar reflectivity and longwave emissivity) and hygroscopic properties (sorption isotherm and water vapor permeability) also showed limited changes (<20 % in most cases). In contrast, capillarity, represented by the capillary absorption coefficient, was reduced by over 80 %. Numerical simulations further showed that relative humidity and moisture content at the exterior and middle positions of earthen walls strongly decreased after hydrophobization treatment. The largest moisture flux discrepancy between untreated and treated walls was 652.1 g/(h·m2). Furthermore, the parametric analysis indicated that façade treatment dominated the hygric state of the exterior and middle positions of earthen walls, while ventilation was most important at the wall interior and in the indoor space. Therefore, combining façade hydrophobization treatment and ventilation is recommended to improve the performance of earthen walls and maintain a favorable indoor environment.

Effects of land use types on the depth distribution of selected soil properties in two contrasting agro-climatic zones

The depth distribution of soil properties are governed by several interacting factors including land use types (LUT) and agro-climate (AgC) factors. Yet, there is little information on the effects of LUT, AgC and their combination on soil properties along depth, which this study aimed to investigate. We collected a total of 36 composite soil samples using the manual percussion of a steel core tube layer by layer vertically up to 30 cm in sites representing both highland and lowlands, and analyzed for selected soil properties. A significant main effects of LUT on the depth distribution of bulk density (BD), Ca, Na, K and Cu, and AgC on soil texture, pH, EC, Ca, Na, K, P, Mn, Fe and Cu were noted. The two-way ANOVA analysis also revealed the significant effects of both LUT and AgC on the depth distribution of BD, Na, K, Cu and EC, reflecting their influences on the paths associated to bio-geo-recycling processes. Compared to crop and forestlands, the average SOC and Fe were lower while EC, CEC, Ca, Na, K, P, Mn and Zn were higher in homegarden located in highland than lowland, possibly the acid nature of the highland soil may make the extractable cations available. SOC was not significantly influenced by AgC, LUT and their interaction effect. Based on the Elemental Enrichment Ratio (EER), the SOC was concentrated in the upper surface soil in forest and cropland located both in highland (1.79, 1.33) and lowland (1.80, 1.57), respectively. The reverse propagation pattern SOC depth distribution in soils under homegarden with EER of 0.7 (highland) ad 0.8 (lowland) showed that implementing such system can accelerate carbon sinking and safely store it in subsoil. Also, diversified species composition associated with respective root architectures in the homegarden system, make it an efficient soil nutrient management, which should be widely promoted.

Lignin-Based Hydrogel Reinforced Dry Water as Inhibitor for Coal Spontaneous Combustion

ABSTRACT Dry water is a green fire extinguisher agent with good cooling and fluidity that is composed of hydrophobic silica and tiny liquid droplets. However, the structure of dry water is unstable and easily broken during production, transportation and storage. In this study, a lignin-based hydrogel was employed as the core material and hydrophobic silica as the wall material to develop a hydrogel reinforced dry water suitable for preventing coal spontaneous combustion. The bulk density, fluidity, stability and particle size distribution of the synthesized hydrogel reinforced dry water were all measured. Compared to traditional dry water, the lignin-based hydrogel reinforced dry water had a better angle of repose and outflow velocity, measuring 19.53° and 9.40 mL/s, respectively. Additionally, the bulk density and water retention in an open environment were 2.6% and 5.2% higher than traditional dry water, respectively. The particle size distribution of the lignin-based hydrogel reinforced dry water is likewise more uniform. Thermal analysis was used to examine the effect of the reinforced dry water on coal oxidation. The results showed that the reinforced dry water reduced the mass increase caused on by oxygen adsorption, hence inhibiting coal oxygen chemisorption. Further investigation revealed that addition of reinforced dry water improved the inhibitory performance of coal spontaneous combustion by decreasing coal oxidation heat release by 4.2% and 11.2%, respectively, in comparison to raw PING and YZ coal, and by increasing coal oxidation activation energy, with maximum increases of 23 and 265 kJ/mol for PING and YZ, respectively.

Cover crop and biofuel crop effects on hydraulic properties for claypan soils

AbstractPerennial biofuel and cover crops systems are important for enhancing soil health and can provide numerous soil, agricultural, and environmental benefits. The study objective was to investigate the effects of cover crops and biofuel crops on soil hydraulic properties relative to traditional management for claypan soils. The study site included selected management practices: cover crop (CC) and no cover crop (NC) with corn/soybean rotation, switchgrass (SW), and miscanthus (MI). The CC mixture consisted of cereal rye, hairy vetch, and Austrian winter pea. The research site was located at Bradford Research Center in Missouri, USA, and was implemented on a Mexico silt loam. Intact soil cores (76‐mm diam. by 76‐mm long) were taken from the 0–10, 10–20, 20–30, and 30–40 cm depths with three plot replicates and two sub‐samples per plot replicate per depth. Soil hydraulic properties evaluated for each sample included: saturated hydraulic conductivity (Ksat), water retention, bulk density, and pore size distributions. Results showed with the test of Duncan's least significant differences that treatments of MI (1.18 Mg m−3) and SW (1.21 Mg m−3) had lower values of bulk density averaging across soil depth than CC (1.27 Mg m−3) and NC (1.31 Mg m−3). Management systems significantly increased Ksat with the biofuel treatments at 0–10 cm compared to NC system. The MI management showed a significant increase in macroporosity and fine mesoporosity as compared to other management systems. Slight changes have occurred in the measured soil physical properties for CC system compared to NC plots. Overall, increasing soil organic matter from more plant roots from long‐term biofuel cropping systems can improve soil water storage and crop productivity.

Long-term impact of organic and conventional farming on soil physical properties under rice (Oryza sativa)-wheat (Triticum aestivum) cropping system in north-western Indo-Gangetic plains

Long-term (13 years) impact of organic and conventional farming on soil physical properties was evaluated under a rice (Oryza sativa L.) – wheat (Triticum aestivum L.) cropping system in a sandy clay loam soil at New Delhi. The treatments included unfertilized control (T1), conventionally managed (T2) and five organic treatments (T3: FYM @ 10 t/ha to rice and wheat, T4: SGM for rice and LGLM for wheat, T5: SGM + BGA for rice and LGLM + Azotobacter for wheat, T6: SGM + FYM for rice and LGLM + FYM for wheat, and T7: SGM + FYM + BGA for rice and LGLM + FYM + Azotobacter for wheat). The application of organic amendments had positive influence on soil physical properties such as saturated hydraulic conductivity (Ks), field capacity (FC) and permanent wilting point (PWP), plant-available water capacity (PAWC), water holding capacity (WHC), distribution of aggregate size fractions, bulk density (Db), and porosity in the 0-15 and 15-30 cm soil layer. A favourable effect of organic amendments was also found on soil strength (at depth 0-70 cm). Even, values related to these properties were significantly affected by the kinds of organic amendments. But, T1 and T2 had no improvement in soil physical properties over the organic ones. Value of Ks decreased with increase in soil depths. T7 and T3 were superior in Ks to other treatments for 0-15 and 15-30 cm soil depths. Volumetric moisture content at FC (θFC) and PWP (θWP) increased with addition of organic amendments and got varying response due to the kinds of organic amendments or their combinations. θFC and θWP were decreased substantially under T1 and T2, because of no addition of organic inputs. As a result of θFC and θWP, PAWC had also signified an improvement under the influence of different organic amendments over T1 and T2. Generally (for both depths), PAWC of T3, T6 and T7 were 17-26% more than T1, T2, T4 and T5. WHC of upper soil layer (0-15 cm) was greater for organic amended plots than plots devoid of organic inputs and lower values were recorded for 15-30 cm soil layer. WHC of T3, T7 and T6 was highest in comparison to plots amended only with (without FYM) green manure, BGA or Azotobacter as well as T1 and T2 for both depths (0-15 and 15-30 cm). A better soil aggregation was observed under organic amended plots for large and small macro-aggregates (LM - &gt;2 and SM-0.25-2 mm) in both soil depths. Lowest value of Db with highest percentage of pore space was noted under T7 than other treatments in both soil layers. Soil strength was significantly lower in organic amended plots than T1 and T2. This study clearly indicated that application of organic inputs especially FYM, improved the soil physical properties, which resulted in better soil aggregation, porosity and soil moisture retention.

Seismically-induced down-sagging structures in tephra layers (tephra-seismites) preserved in lakes since 17.5 cal ka, Hamilton lowlands, New Zealand

We analysed numerous soft-sediment deformation structures (SSDSs) identified in seven unconsolidated, up to 8-cm thick, siliceous tephra layers that had been deposited in ~35 riverine-phytogenic lakes within the Hamilton lowlands, northern North Island, New Zealand, since 17.5 calendar (cal) ka BP. Based on sediment/tephra descriptions and X-ray computed tomography scanning of cores taken from ten lakes, we classified these SSDSs into elongated load structures (i.e., down-sagging structures) of different dimensions, ranging from millimetre- to decimetre-scale, and centimetre-long dykes. Down-sagging structures were commonly manifested as intrusions of internal tephra beds of very fine to medium sand into underlying organic lake sediments. The tephra layers commonly exhibited an upper silt bed, which was not directly affected by deformation. Dry bulk density and grain size distribution analyses of both the organic lake sediment and the internal tephra beds provided evidence for the deformation mechanism of down-sagging structures and their driving force: the organic lake sediment and the upper silt bed are less liquefiable, whereas the very fine to medium sand internal tephra beds are liquefiable. The tephra layers and encapsulating organic lake sediments formed three-layer (a–b–a) density systems, where ‘a’ denotes the sediment unit of lower density. We infer that downward-directed deformation was favoured by the a–b–a density system with the upper, less-liquefiable, silt bed within the tephra layer preventing upward intrusion during the liquefaction process. The spatial distribution and ages of SSDSs within the lakes provided some evidence that liquefaction of the older tephra layers, i.e., Rerewhakaaitu, Rotorua, and Waiohau tephras, deposited 17.5, 15.6, and 14 cal ka BP, respectively, was triggered by a seismic source to the northeast of the Hamilton lowlands (i.e., Kerepehi and/or Te Puninga faults). In contrast, the liquefaction of the younger tephra layers, i.e., Opepe, Mamaku, and Tuhua tephras, deposited 10.0, 8.0, and 7.6 cal ka BP, respectively, may have been triggered by movement on local faults within the Hamilton lowlands, namely the Hamilton Basin faults, or by distant faulting at the Hikurangi subduction margin east of North Island.

Evaluation of the packed state of catalyst pellets in the gas phase reactor (Effect of catalyst pellet shape on its packed state)

In this paper, we propose a simulation method to evaluate the packed state of catalyst pellets in a pipe reactor for gas phase reaction. This simulation method is based on dynamic explicit FEM (finite element method) and consists of three steps. Specifically, first, the catalyst pellets freely fall under gravity and flow into a packing hose with a hopper-like inlet. Then, after the catalyst pellets reach the bottom of the pipe reactor, the packing hose is pulled up to create a random packing of the catalyst pellets in the pipe reactor. Finally, the bulk density and stress distribution of the catalyst pellets randomly packed in the pipe reactor are calculated, and the packed state of the catalyst pellets is evaluated. Using this simulation method, we simulated the packing of cylindrical catalyst pellets into the pipe reactor and evaluated the packed state of the catalyst pellets in the pipe reactor. As a result, it is clarified that the maximum equivalent stress generated at the bottom of the catalyst pellets packed in the pipe reactor approaches a constant value as the ratio of the packed height of the catalyst pellets to the diameter of the pipe reactor increases. In addition, the effects of the shape of the catalyst pellets on the bulk density and average equivalent stress of the catalyst pellets in the pipe reactor are elucidated, and the optimal shape of the catalyst pellets that can increase the bulk density and reduces the stress is found. The optimally shaped catalyst pellets are expected to improve their packed state in the pipe reactor, extend the durability of the catalyst pellets and increase the efficiency of production. In this paper, it is assumed that the packed state and durability of the catalyst pellets are evaluated based on the bulk density and stress distribution of the catalyst pellets in the pipe reactor.

Prediction of permeability of tight sandstones from mercury injection capillary pressure tests assisted by a machine-learning approach

Mercury injection capillary pressure analysis is a methodology for determining different petrophysical properties, including bulk density, porosity, and pore throat distribution. In this work, distinct parameters derived from mercury injection capillary pressure tests was considered for the prediction of permeability by coupling machine learning and theoretical approaches in a dataset composed of 246 tight sandstone samples. After quality checking the dataset, the feature selection was carried out by correlation analysis of different theoretical permeability models and statistical parameters with the measured permeability. Finally, porosity, median capillary pressure, Winland model, and mean pore-throat radius (corresponding to the saturation range 0.4-0.8) were chosen as the input features of the machine learning model. As the machine learning approach, a support vector machine (SVM) model with a radial basis function kernel was proposed. Furthermore, the model and its metaparameters were trained with a particle swarm optimization (PSO) algorithm to avoid over-fitting or under-fitting. In contradiction to the theoretical models, the implemented SVM-PSO model could acceptably predict the experimentally measured permeability values with an R2 rate of over 0.88 for training and testing datasets. The introduced approach could reduce the mean relative errors from about 10 to values less than 0.45. The improvements were more significant for low permeability samples. This successful implementation shows the potential of coupled usage of theoretical and machine learning methodologies for improved prediction of permeability of tight sandstone rocks. Cited as: Abbasi, J., Zhao, J., Ahmed, S., Jiao, L., Andersen, P., Cai, J. Prediction of permeability of tight sandstones from mercury injection capillary pressure tests assisted by a machine-learning approach. Capillarity, 2022, 5(5): 91-104. https://doi.org/10.46690/capi.2022.05.02

Spatial Variation in Soil Physico-Chemical Properties along Slope Position in a Small Agricultural Watershed Scale

Both cropland management and slop erosion are important factors influencing soil properties, but there are relatively few studies on their combined effects. Studies at the agricultural watershed scale can satisfy both of these conditions, and to reduce the effects of soil heterogeneity due to differences in spatial scale, it is better to select different slopes in the same small watershed. To understand how soil properties will respond to the variation of slope position and cropland management at an agricultural watershed, we present the distribution of soil bulk density (BD), saturated hydraulic conductivity (Ks), water-stable aggregates, soil organic carbon (OC), nitrogen (N), and phosphorus (P) at four slope positions in two cropland management systems of a small agricultural watershed in the black soil region of northeast China. The selected four slope positions include upper slope, middle slope, lower slope, and footslope positions. The two cropland management systems consist of a sustainable cropland system (i.e., contour ridge tillage at upper slope position, longitudinal ridge tillage at middle slope and lower slope positions, and grassland at footslope position) and a conventional cropland system (i.e., contour ridge tillage at upper slope position, longitudinal ridge tillage at middle slope, lower slope positions, and footslope positions). The results showed that soil bulk density and microaggregates decreased but the concentration of OC and nutrients, Ks, and small-macroaggregate increased from the upper slope position to the lower slope position in both the conventional and sustainable croplands, which was due to the interaction effect of cultivation with erosion. In comparison with conventional cropland, sustainable cropland has greater Ks, large-macroaggregate, small-macroaggregate, microaggregate, and concentrations and stocks of OC, N, and P, but showed lower bulk density and silt + clay fraction. However, the prominent differences in both croplands were presented in the footslope position, which is ascribed to the interaction of cultivation, erosion, and cropland management. These results highlighted that sustainable cropland management practice has the potential to improve soil structure and prevent soil and nutrient loss.

Preparation of ethyl vanillin spherical particles with functions of sustained release and anti-caking by an organic solvent-free process

Ethyl vanillin is an important synthetic flavor that occupies a large market share in food additives. However, the shortcomings in terms of too fast aroma release rate and poor powder properties have severely limited its further application. In this work, the intrinsic mechanism of ethyl vanillin oiling-out process is revealed with the help of process analytical technologies. Further, a green and efficient spherical particles preparation technology is developed by constructing the oiling-out phase diagram of ethyl vanillin in the aqueous solution of sodium chloride. The ethyl vanillin spherical product has excellent powder properties with high bulk density (0.74 g/cm3), good sphericity (93.4 %), high flowability (29°), high yield (>95 %) and adjustable particle size distribution. More importantly, the spherical product exhibits 57.9 % lower aroma release rate at 323.15 K and 1400 % higher critical caking cycle compared to irregularly shaped powder, which confirms its sustained release and anti-caking function.