Low Compressibility Research Articles

Experimental investigation of the flow properties of layered coal-rock analogues

Coals are heterogeneous and the zones of interest for gas production (high fracture density) are often friable. 3D printed (3DP) rocks can create a repeatable analogue by minimizing specimen variability. This study investigates a series of 3DP coal seam gas packages under various flow conditions to determine the impact of fracture network and interburden rock on the dynamics of permeability. The 3DP coal analogue is treated with sodium silicate and carbon dioxide to reduce porosity and permeability. Seven cylindrical specimens are analysed including: the intact 3DP coal analogue, the intact interburden analogue, the unidirectionally and multi-directionally fractured coal analogues, and packages of coal-interburden-coal with different fracture systems. These specimens are subjected to isotropic triaxial flow tests to compare the properties of natural and synthetic rocks. The experimental results revealed that the pore compressibility of 3DP rock treated with sodium silicate is in the same range as coal. 3DP specimens with multi-directional fractures exhibited lower fracture compressibility than ones with unidirectional fractures. The results suggested that the flow properties of a single coal layer might differ from that of a composite coal-interburden rock. The experimental outcomes indicate that 3D printing is a valuable tool to investigate coal behaviour under depletion conditions.

Experimental Study on Strength of Polypropylene Fiber Reinforced Cemented Silt Soil

To improve the poor characteristics of low strength and high compressibility of weak silty soil, a series of samples with different cement dosage, fiber content, and fiber length was prepared in this experiment, and unconfined compressive strength (UCS) tests, triaxial tests, and scanning electron microscopy (SEM) tests were carried out to explore the influence of polypropylene fiber on the strength of cement-stabilized soil and analyze the curing mechanism of fiber-reinforced cement soil. The test results show that the factors affecting the UCS of the sample from high to low were: cement dosage, fiber content, and fiber length. An orthogonal test found that the optimal ratio of the sample was cement dosage of 18%, fiber content of 0.4%, and fiber length of 3 mm, and the UCS of the sample can reach 1.63 MPa. The triaxial test shows that when the cement dosage is 15% and the fiber length is 9 mm, the incorporation of fiber can significantly improve the toughness and strength of soil. When the cement dosage is 15%, the UCS with 0.4% fiber content is 1.6 times that without fiber. With the increase of fiber content, the peak stress and axial strain of fiber-cured soil are increased, and the cohesion and internal friction angle are also increased. The failure mode and SEM test of fiber-reinforced cement soil show that when the cement dosage is 15% and the fiber length is 9 mm, the addition of fiber can improve the deformation ability of cement soil and slow down the development of cracks. With the increase in fiber content, the number and width of cracks are significantly reduced, and the failure mode changes from brittle failure to ductile failure.

Subgrade soil evaluation using integrated seismic refraction tomography and geotechnical studies: A case of Ajaokuta-Anyigba Federal highway, North-Central Nigeria

ABSTRACT Integrated seismic refraction tomography (SRT) and geotechnical tests were conducted on failed and stable sections of the Ajaokuta – Anyigba Highway, North-central Nigeria. This study was aimed at characterising the soil profile, determining the competence of the subgrade soils, and establishing relationships between geophysical and geotechnical parameters. Primary wave velocities (Vp) were calculated by using SeisImager/2D (V.2.9.1). The subgrade soils of the unstable segment were characterised by low Vp (358–607 m/s) while higher Vp (762–1417 m/s) characterised the stable segment. The geotechnical results confirmed the seismic refraction results. Geotechnical results revealed that the subgrades of the unstable section are generally classified as A-6 and A-7-6 clayey soils, with low to high plasticity, and a fair to poor subgrade rating. While the subgrades of the stable section are grouped as A-2-4 silty sands with low compressibility and good to excellent subgrade ratings. Simple linear regression analysis showed fairly strong positive correlations between Vp and sand with CBR (r = 0.81 and 0.78, respectively). On the other hand, fairly strong negative correlations were obtained between Vp and the plasticity index with fines (r = −0.63 and −0.82 respectively).

BEARING CAPACITY ANALYSIS OF SUBSOILS, FOR SHALLOW AND DEEP FOUNDATION IN UYO TOWN, EASTERN NIGER DELTA, NIGERIA.

The Geotechnical properties of soils in Uyo town were analysed to determine the bearing capacity and develop maps for shallow and deep foundation designs, which may serve as field models, for the planning of site investigation programmes for foundation purposes. Eleven boreholes were drilled to a maximum depth of 20 meters each across Uyo town. Standard penetration tests and cone penetration tests were also carried out on the field. Soil samples were retrieved during the field investigation for various laboratory tests including liquid limits, plastic limit, bulk density, shear strength and particle size distribution. The general soil profile consists of silty clays, sandy clays and sand from top to bottom. The silty clays are firm, low compressibility clays with liquid limit and plastic limit percentages between 32%-45% and 10%-45% respectively, cohesion averages of 4˚ to 12˚ and angles of internal friction between 48KN/m2-68KN/m2. Ultimate bearing capacities of this horizon range from 354.6kN/m2 to 866.7kN/m2.The sandy clays are also firm, low to intermediate plasticity clays with liquid limit and plasticity indexes of 29% - 42% and 9%-15% respectively. Their cohesion averages range between 50KN/m2-65KN/m2 and angles of internal friction between 6˚-12˚. The ultimate bearing capacities of this clay range from 482.5KN/m2 to 906.2KN/m2. The sand is a poorly graded, medium dense sand with standard penetration test N-values between 8 to 23. Pile bearing capacities of the sand gave ultimate and allowable bearing capacities between 10262.9KN-11510.2KN and 4105.2KN-4604.1KN respectively. The sand substratum is a suitable termination depth for piles.

Ionic liquid-catalyzed synthesis of carbon/polyurethane triboelectric nanocomposites with excellent flame retardancy and oil leak detection

A high-carbon (expandable graphite flakes and carbon black)–loaded polyurethane foam (PUF) composite was prepared using a green and efficient ionic liquid (IL) catalyst. The carbon/PUF composite exhibited excellent flame retardancy and was highly versatile for application in oil leak detection and as triboelectric nanogenerator (TENG). The effect of the IL on the foamability of the carbon/PUF composite was thoroughly investigated. The IL promoted the expansion of the carbon/PUF composite and the microcellular pore formation in it, thereby affording a sponge with low density, excellent flexibility, and compressibility. Owing to the presence of high-carbon fillers, the resultant sponge exhibited excellent flame retardancy by (i) avoiding melt dripping after ignition by a butane torch (∼1400 °C, applied for 20 s), (ii) self-extinguishing after torch removal, and (iii) preventing foam collapse. Additionally, it can pass the UL-94 V-0 rating and the critical fire retardancy metrics, i.e., peak heat release rate, total heat release, and total smoke release, were reduced by 73%, 78%, and 92%, respectively. A flame retardant (FR)-TENG was designed using the carbon/PUF composite. The FR-TENG could be attached to the insole of a shoe, generating an output of 36 and 100 V upon walking and running, respectively. This output was sufficient to concomitantly glow 38 LEDs. Interestingly, owing to the oil-induced reversible shape change, the carbon/PUF composite can be used for the fabrication of high-efficiency oil leak sensors to detect oil spills in pipelines and different water environments. This study offers a new perspective for the development of flame retardant and multifunctional foam-based materials.

Utilization of Dredged Mud in Land Reclamation: A Comparison Study of Several Soil Improvement Methods

Utilization of dredged mud in land reclamation will become more applicable in the future due to the increase of the need for space and the rising cost of granular fill materials. Dredged mud mainly consists of soft clay and has very low bearing capacity and high compressibility. Therefore, soil improvement is urgently required. In this paper, the effectiveness of using dredged mud as the fill material in land reclamation was analyzed for a case study of land reclamation. The performance of several soil improvement methods in using such reclamation material was calculated and compared. The soil improvement methods considered in this study were prefabricated vertical drain (PVD) with vacuum preloading, cement mixed dredged mud, and rigid inclusion. The load transfer mechanism in each method was analyzed using analytical and numerical methods. In addition, an elementary cost analysis was performed to compare the cost of the methods based on Indonesian prices. It was found that for the considered case study, cement mixing achieved the highest bearing capacity with the shortest time but with the highest cost. For the same increase in bearing capacity, PVD with vacuum preloading provided the lowest cost. This study provides a preliminary step towards the implementation of effective soil improvement for land reclamation in Indonesia.

Experimental investigation on performance test of 150-kW-class supercritical CO2 centrifugal compressor

• Supercritical CO 2 compressor is designed and manufactured for performance test. • Centrifugal impeller is adopted to accomplish optimum design of supercritical CO 2 compressor. • Reliability of designed compressor is confirmed through repeated compressor performance test. • Effects of controlling of control valve and impeller rotation speed are analyzed. Supercritical CO 2 is a promising working fluid for next generation power conversion systems. The key component in a supercritical CO 2 power generation system is turbomachinery, which particularly includes the compressor. Supercritical CO 2 has high density and low compressibility, similar to the liquid state near the critical point. Therefore, when the compressor is operated near the critical point of CO 2 , significant reduction of compression work can be attained, as compared to conventional air Brayton cycles. However, there are technical challenges concerning the design and operation of the compressor. Therefore, in this experimental study, a 150-kW-class supercritical CO 2 centrifugal compressor for a 500-kW power generation system is designed and investigated. The design point of compressor, pressure ratio, and efficiency, are 1.75, and 80% at rotational speed 36000 RPM. The purpose of this test is to evaluate the performance of the supercritical CO 2 centrifugal compressor and obtain accessible fundamental data. During the performance test, which is conducted by controlling the rotational speed of the impeller and the opening rate of the control valve, the compressor is operated by an electric motor, and the generated pressure from the compressor is consumed using a control valve. Repeated tests are conducted on the compressor to confirm the practicality of the designed compressor for the supercritical CO 2 power generation system. The compressor achieves a higher efficiency of 80% than the target efficiency during the repeated four tests. In addition, the reliability of the compressor performance is examined. Furthermore, the results of the test are analyzed to understand the effects of the opening rate of the control valve for load changing and the rotational speed of the impeller.

Study on Strength and Swell Behavioral Change and Properties of the Clay–Fiber Mixtures

Clayey soils are spread over large areas of the world. This soil type has numerous problems due to its low strength, high compressibility, and high level of volumetric changes. To overcome these difficulties, many researchers have concentrated their studies on soil improvement techniques. Recently, soil reinforcement has been considered an effective and reliable technique for improving the strength and stability of these soils by using different types of reinforcing materials. This paper aims to investigate the feasibility of using polypropylene fiber as a low-cost and environmentally friendly reinforcing material for high plasticity clay, and assess the strength and swelling behavioral change with fiber content to determine the optimum fiber content that meets the effective improvement rate. A series of laboratory experiments such as a direct shear test, swell test, and unconfined compressive strength (UCS) test were carried out to evaluate the fiber content effect on the strength and swell behavior of composite clay (clay mixed with fiber). The fiber content varied from 0% to 1.5% (by dry weight of the soil). The results show that the inclusion of fiber affects the shear strength (an average increase of 184% at 1.5% fibers), and unconfined compressive strength (an increase of 86% at 1.5% fibers). Likewise, the increase in fiber content causes an increase in the strength properties, cohesion, and friction angle (257% and 62% at 1.5% fibers, respectively). Also, the increase of fiber content causes a decrease in both swelling potential and swell stress (a decrease of 24% and 46% at 1.5% fibers, respectively) in the studied clayey soil.

Analysis of Load Transfer Law of Short Pile-Net Composite Foundation for High-Speed Railway

Although pile-net composite foundation has been widely used in the construction of high-speed railway, load transfer characteristics of its structural system during the filling of roadbed are seldom studied, so field studies are conducted in the Gan-Long (Ganzhou-Longyan) high-speed railway DK86 + 998.0–DK87 + 191.2 test section, aiming to explore the bearing characteristics of a short pile-net composite foundation over low to medium compressible soil. The study encompasses a field measurement of Earth pressure and pore water pressure which lasted almost two years, and a systematic analysis of variation law of soil pressure between piles and their tops and that of pore pressure in reinforcement zone and retaining layer in medium and low compressibility soil area. The results suggest that the soil in the test section bears the characteristic of a low water content, low porosity ratio, and high liquid limit, with compression factor being approximately 0.25, and test values of the natural soil pressure and the lateral distribution are close to the theoretical values. Soil pressure at the top of the piles is higher than that between the piles by approximately 2.4 times because of the differences in pile-net rigidity. Besides, the soil pressure of the pile-net composite foundation follows the pattern of “jagged” in the transverse direction of the roadbed. The filling load of the composite foundation soil arch is 80 kPa and the composite foundation reaction coefficient is 6.4 kN/m3 when the filling is stable. The pile-soil stress ratio at the shoulder and the center of the line is 3.2 and 2.8, respectively. The change of the hole pressure at the pile end point is larger than that at the reinforcement area, and the side verification short pile can effectively transmit the additional stress of the upper part to the pile end soil layer.

Flowability of spray‐dried sapodilla pulp powder

AbstractThis study aimed to evaluate the influence of maltodextrin, Arabic gum, and dextrin on phenolic compounds, morphology, and flowability of sapodilla pulp powder obtained in a spray dryer. Sapodilla pulp was characterized by its moisture and total polyphenols. The carriers were individually added to the pulp at a concentration of 20% (m/m), and the samples were dried in a spray dryer. The powders were analyzed for moisture, hygroscopicity, total polyphenols, and particle morphology, and their flowability was evaluated using the Powder Flow Tester (PFT). Total polyphenols of sapodilla pulp (average of 1055.30 mg GAE in 100 g of pulp solids) were more significant than in the powders (457.06 to 635.55 mg GAE in 100 g of pulp solids). The lowest moisture (1.16%) was obtained for maltodextrin. All carriers generated nonhygroscopic powders. The particles showed a rounded shape with greater roughness in samples containing Arabic gum. The powder with dextrin resulted in better flowability characteristics, with a higher flow index and lower compressibility index, Hausner ratio, and wall friction angle. Sapodilla pulp powder was classified as cohesive, with flow indices < 3, compressibility index from 53.2 to 59.9, and Hausner ratio between 2.14 and 2.50. The carriers used influenced the characteristics of sapodilla pulp powders, the Arabic gum promoting greater protection of total polyphenols and dextrin resulting in better flowability characteristics.Practical ApplicationsThe consumption of tropical fruits has increased in recent years, especially fruits considered exotic. The sapodilla fruit has many health benefits potential, but it has a short shelf life and seasonal crop. This research provides information on the spray‐dried sapodilla pulp powder containing different drying carriers, in order to evaluate the powder flowability behavior. This evaluation was based on particle morphology, wall friction angle, and bulk and tapped densities. It is important to determine the influence of carriers on the powder in order to produce a good quality product.

From the synthesis of hBN crystals to their use as nanosheets in van der Waals heterostructures

In the wide world of 2D materials, hexagonal boron nitride (hBN) holds a special place due to its excellent characteristics. In addition to its thermal, chemical and mechanical stability, hBN demonstrates high thermal conductivity, low compressibility, and wide band gap around 6 eV, making it a promising candidate for many groundbreaking applications and more specifically in van der Waals heterostructures. Millimeters scale hBN crystals are obtained through a disruptive dual method (polymer derived ceramics (PDC)/pressure-controlled sintering (PCS)) consisting in a complementary coupling of the PDC route and a PCS process. In addition to their excellent chemical and crystalline quality, these crystals exhibit a free exciton lifetime of 0.43 ns, as determined by time-resolved cathodoluminescence measurements, confirming their interesting optical properties. To go further in applicative fields, hBN crystals are then exfoliated, and resulting boron nitride nanosheets (BNNSs) are used to encapsulate transition metal dichalcogenides (TMDs). Such van der Waals heterostructures are tested by optical spectroscopy. BNNSs do not luminesce in the emission spectral range of TMDs and the photoluminescence width of the exciton at 4 K is in the range 2–3 meV. All these results demonstrate that these BNNSs are of high quality and relevant for future opto-electronic applications.

Soft Soil Consolidation with the Electroosmosis Effect

Areas with geomorphology in plains or lowlands, such as Pontianak City, have soft soil and peat covering most of their area. Lands in areas with low soil bearing capacity, high water content, high compressibility properties, and high groundwater levels or even practically the same as the land surface. Theoretically, soil improvement is preferred over several other options such as relocation, redesign, and replacement of unsuitable soils. Electroosmosis is one of the effective methods to reduce the moisture content in soft clay to reduce the amount of settlement that occurs when loading is carried out. The use of electroosmosis by placing a conductor in the ground with a certain distance, then between the conductors, an electric current is given. By reducing the water content in the soil, the decrease in soil subsidence will decrease and increase the strength of the soil. This electroosmosis test was carried out in a laboratory with a test model using a PVC pipe tube with a length of 19 cm and a diameter of 15 cm using five conductor rods. The soil specimens are subjected to two cases: direct loading and preloading during the electroosmosis test. Tests were conducted to study the effect of the current magnitude applied with a particular voltage on the physical and mechanical properties of the soil. The tests showed a significant of settlement with 0.0679 cm and 0.0663 cm for direct loading and preloading with the current effect. The mechanical properties showed an improvement in the soil samples, which was indicated by a low compressibility index and an increase in the shear strength of the soil.

Modeling of monotonic and cyclic behaviors of sand under small and normal confining stresses

Soil is commonly confined under very small stress at shallow depth of ground and in small scale 1 g model test. Considering Toyoura sand as example, it shows relatively less compressibility under small confining stress (<50 kPa) than normal confining stress (50∼1000 kPa) in both static and dynamic conditions. To investigate the mechanical behavior of Toyoura sand under different confining stresses (CS), a series of element tests were conducted. These tests were performed on loose and medium dense sand by applying isotropic consolidation and unloading conditions, under the confining stress ranged from very small to normal values (5 kPa∼700 kPa). It is found that the gradient of e -ln p curves of both loose and medium dense Toyoura sands consolidated under 700 kPa is about 2.5 times of the specimens consolidated under 50 kPa. While during unloading, the gradient of e -ln p curves of specimen consolidated under 700 kPa is about 3 times of the specimen consolidated under 50 kPa. Based on these test results, a new model is proposed based on Cyclic Mobility model, and this model has competency to describe the compressibility of sandy soils accurately even under small CS. In proposed model, a new power function relationship between void ratio and confining stress is established, and a new evolution equation for overconsolidation is also adopted. The proposed model is verified by isotropic consolidation tests, drained monotonic triaxial tests, and undrained cyclic triaxial tests. Moreover, it is also established that the predictive accuracy of compressibility of proposed model is significantly improved than the original model especially under small CS. • A new constitutive model was proposed to describe the low compressibility of sand under small confining stress (CS). • The isotropic loading and unloading tests with the stress range from small CS to normal CS (5 kPa∼700 kPa) were conducted. • The power function relation between void ratio and confining stress in the isotropic consolidation tests is almost linear. • The proposed model can describe the mechanical behavior of sands with various conditions in a unified way.

Numerical model for the settlement of loess subgrade in operation period reinforced by rotary jet grouting pile

The problems of subgrade settlement failure and uneven settlement are quite prominent due to hydraulic migration. The loess in the natural state has the characteristics of high strength and low compressibility. Composite foundation method is to set a certain proportion of reinforcement (pile) in the natural foundation, so that the pile and soil jointly bear the load, and has the effect of compaction method and displacement method. Based on the actual case of a highway disease in Shanxi Province, this paper studies the influence of treatment measures of rotary jet grouting pile penetrating or not penetrating the loess soil on the uneven settlement of highway subgrade in loess region by means of field investigation, analysis and numerical calculation. The results found that the lateral friction resistance of rotary-jet grouting pile penetrates through the loess is small. When the rotarjet pile is long and the underlying soft layer is relatively thick (4.5 m), the settlement of the foundation also quickly enters the stable state. When the underlying loess is deep, the settlement of the foundation increases with time.

Possible applications of Mo2C in the orthorhombic and hexagonal phases explored via ab-initio investigations of elastic, bonding, optoelectronic and thermophysical properties

Binary carbides demonstrate an attractive set of physical properties that are suitable for numerous and diverse applications. In the present study, we have explored the structural properties, electronic structures, elastic constants, acoustic behaviors, phonon dispersions, optical properties, and various thermophysical properties of binary orthorhombic and hexagonal Mo2C (O-MC and H-MC, respectively) compounds in detail via first-principles calculations using the density functional theory (DFT). The calculated ground state lattice parameters in both the symmetries are in excellent agreement with available experimental results. The calculated electronic band structure, density of states, and optical properties of Mo2C in both structures reveal metallic features. The orthorhombic crystal shows a higher level of mechanical and thermal anisotropy compared to that in the hexagonal phase. The elastic constants and phonon dispersion calculations show that, in both structures, Mo2C is mechanically and dynamically stable. A comprehensive mechanical and thermophysical study shows that both phases possess high structural stability, reasonably good machinability, ductile nature, high hardness, low compressibility, high Debye temperature and high melting temperature. Moreover, the electronic energy density of states, electron density distribution, elastic properties, and Mulliken bond population analyses indicate that the structures under consideration consist of mixed bonding characteristics with ionic and covalent contributions. Investigation of the optical properties reveals that the reflectivity spectra are anisotropic with respect to the polarization directions of the electric field in the visible to mid‑ultraviolet regions. High reflectivity over a wide spectral range makes the compound suitable as reflecting coating. Both the structures are efficient absorbers of ultraviolet radiation. The refractive indices are quite high in the infrared to the visible range. Both structures show directional optical anisotropy. Though, H-MC exhibits stronger optical anisotropy than the O-MC.

Pengaruh Penambahan Bubuk Gypsum Pada Tanah Lempung Dengan Pengujian Direct Shear

Clay soil is a type of cohesive soil that has low shear strength but high compressibility. The purpose of the study was to determine the physical properties of soil originating from Rantebua Village, Rantebua District, North Toraja Regency, and to determine the effect of adding gypsum to soil originating from Rantebua Village, Rantebua District, north Toraja Regency by direct shear testing. The research method includes testing the phy properties of the soil and mechanical testing on direct shear. The result of the direct shear test that has been obtained shows that each soil sample mixed with gypsum at a composition 12%, 20%, and 28% has an increase in value (c) and value (ϕ). According to the USCS, it is classified as a fine-grained soil type with low to moderate plasticity, then for the result of the direct shear test in the presence of a mixture of gypsum into four soil samples, it can have an increasing effect on the value of (c) and value (ϕ) so that the bearing capacity of the soil becomes better than the soil condition before it was mixed with gypsum.

Effect of Physical Properties and Chemical Substitution of Excipient on Compaction and Disintegration Behavior of Tablet: A Case Study of Low-Substituted Hydroxypropyl Cellulose (L-HPC)

As final attributes of dosage form largely depend on the properties of excipients used, understanding the effect of physicochemical properties of excipients is important. In the present study, six grades of L-HPC with varying degrees of particle size and hydroxypropyl content and the influence of the grade on compaction as well as disintegration behavior were studied. All grades of L-HPC were compressed at different compression loads to achieve different tablet porosity. Compressibility and compactibility of L-HPC grades were evaluated using a modified Heckel equation and percolation model. Further effects of particle size and hydroxypropyl content of L-HPC on tablet porosity and disintegration time were evaluated using a 32 full-factorial design. From compaction studies, it was found that compressibility of L-HPC largely depends upon the particle size with lower particle size grade showing lower compressibility. Whereas consolidation/bonding behavior of L-HPC is independent of particle size and % hydroxypropyl content. By factorial design, it was found that particle size and % hydroxypropyl content have a significant effect on the disintegration behavior of L-HPC. It was found that smaller particle sizes and higher hydroxypropyl content of L-HPC show longer disintegration time. Thus, careful consideration of excipients selection should be made to achieve desired quality attribute of the product.

Switching from batch to continuous granulation: A case study of metoprolol succinate ER tablets

Continuous manufacturing (CM) has been used to produce several immediate release drug products. No extended-release (ER) product manufactured employing CM technology has been approved yet. This study investigated the critical aspects of switching from the batch mode of high shear granulation to the continuous operation of twin-screw granulation for extended-release tablets. Metoprolol succinate ER tablets was used as a model ER formulation for this purpose. A central composite design (CCD) was employed to determine the effects of high shear granulator (HSG) parameters, namely impeller speed, granulation time, and binder liquid feeding rate, on the critical granulation characteristics important for product performance. These critical granulation characteristics served as a guide for switching from the batch processing to the continuous operation for achieving the same breaking strength and dissolution for this ER metoprolol tablets.The granulation time was the most critical factor affecting the bulk properties of granules which contributed to tablet dissolution. The higher density and lower compressibility of granules were attained at the longest granulation time of 5.4 min with the fastest liquid feeding rate of 75 g/min. The granules’ density was the primary factor negatively affecting the dissolution of metoprolol tablets. However, the breaking strength of tablets confounded the effect of granules density on metoprolol dissolution. Switching the processing parameters of high shear granulation to twin-screw granulation achieved similar dissolution profiles (F2 greater than 50). The screw speed was not found to affect bulk properties of granules. The root cause of granulation failures in twin-screw granulation, such as premature consolidation, excessive swelling, poor cohesion, inconsistent shearing effects, and formation of deformed agglomerates, were identified. In conclusion, the use of critical granulation characteristics through a performance-based approach of ER tablets facilitated the switching of manufacturing of an ER formulation form batch to continuous operation.

Suitability of Rice Husk Ash (RHA) with lime as a soil stabilizer in geotechnical applications

Soils containing significant levels of silt or clay generally exhibit unacceptable engineering properties (i.e. low strength, high compressibility and high level of volumetric changes) when exposed to variation in moisture content. Chemical stabilizers such as cement and lime which are currently practiced, are often high-priced and unhygienic in terms of environmental sustainability. The prevailing study intended to explore the potential of the local Rice Husk Ash (RHA) which is an agricultural waste, with lime as a soil stabilizer. This experimental study was conducted on clayey soil with high plasticity. Different mixture proportions of RHA (i.e. 5%, 10%, 20% and 30%) and lime (i.e. 10% and 20%) were used to treat the parent soil. Observations were made for variations in index (i.e. liquid limit, plastic limit, sieve analysis, etc.) and mechanical properties (i.e. compressibility, permeability and shear strength) of treated soils soon and 28 days after mixing. It was found that 10% of RHA and 20% of lime by dry soil weight as the optimum dosage for the treatment. This optimum dosage increases the unconfined compressive strength and internal friction angle by 54.05% and 60.48%, respectively and reduces plasticity index by 56.67% at 28 days after mixing. It could be identified that RHA and lime mixture was capable of improving index and mechanical properties of soil, positively.

Lightweight and Highly Compressible Expandable Polymer Microsphere/Silver Nanowire Composites for Wideband Electromagnetic Interference Shielding.

The exploration of lightweight and compressible electromagnetic interference (EMI) shielding materials with outstanding shielding effectiveness (SE) is still a tremendous challenge in the elimination of electromagnetic pollution. Lightweight and highly compressible expandable polymer microsphere/silver nanowire (EPM/AgNW) composites with micron-sized closed pores and an interfacial AgNW conductive network are fabricated via a facile thermal expansion process in an enclosed space. The EPM/AgNW composites with AgNW loading of 0.127 vol % show low density (0.061 g/cm3), high compressibility and compression strength (4.25 MPa at 92.6% of compressive strain), and high EMI SE (over 40 dB, 1 mm) at a wideband of 8-40 GHz. Their EMI SE can be improved to a record 111.5 dB by increasing the AgNW content to 0.340 vol %, which corresponds to the surface-specific SE (SSE/d; SE divided by density and thickness) up to 13433 dB·cm2/g. The EMI shielding mechanism is further discussed using the finite-element analysis software COMSOL Multiphysics, and the application of the EPM/AgNW composites is visually demonstrated via near-field shielding in a practical antenna radiation. The overall properties of light weight, high elasticity, excellent mechanical strength, and outstanding EMI shielding performance suggest that the as-prepared EPM/AgNW composites have a great potential for applications in modern electronics.