Nanocomposite materials have distinctive potential for various types of captivating usage in drilling fluids as a well-designed solution for the petroleum industry. Owing to the improvement of drilling fluids, it is of great importance to fabricate unique nanocomposites and advance their functionalities for amplification in base fluids. There is a rising interest in assembling nanocomposites for the progress of rheological and filtration properties. A series of drilling fluid formulations have been reported for graphene-derived nanocomposites as additives. Over the years, the emergence of these graphene-derived nanocomposites has been employed as a paradigm to formulate water-based drilling fluids (WBDF). Herein, we provide an overview of nanocomposites evolution as engineered materials for enhanced rheological attributes in drilling operations. We also demonstrate the state-of-the-art potential graphene-derived nanocomposites for enriched rheology and other significant properties in WBDF. This review could conceivably deliver the inspiration and pathways to produce novel fabrication of nanocomposites and the production of other graphenaceous materials grafted nanocomposites for the variety of drilling fluids.
This study was focused on investigating the optimum fluidising velocity during the combustion of rice husk in a bench-scale fluidised bed combustor (ID 210mm) to obtain low carbon ash in the amorphous form. When all other parameters are held constant, the optimum fluidizing velocity aids in almost complete combustion, thereby releasing the entrapped carbon for further conversion. This results in ash with consistently low carbon content (less than 2wt%). The range of fluidising velocities investigated was from as low as 1.5U(mf) to as high as 8U(mf). It was found that the optimum fluidising velocity was approximately 3.3U(mf) as the mixing of rice husk with the bed was good with a high degree of penetration into the sand bed. The resulting ash retained its amorphous form with low residual carbon content (at 2.88wt%) and minimal sand contamination as shown by the X-ray diffraction analysis.
Electrical capacitance tomography (ECT) velocimetry technique was utilized in this study to quantify the flow structure of gas-liquid based on the ECT images. A new 8 electrodes sensor ECT has been successfully developed to provide 2D images in a cross section of pipeline. The ECT has been attentively applied in the test section of the flow rig for imaging the gas-liquid distribution. The inside diameter of ECT pipeline sensor is 100mm. Meanwhile, the flow rig consists of close loop of “CPVC” pipes that includes a pipe test section, two tanks of oil and water respectively and allows the working pressure up to 5 bars. Transparent pipe is used for visual monitoring. A portable Doppler flow meter that utilizes the ultrasonic signal has also been placed at the test section to measure the velocity. The images obtained by ECT show that the different flow patterns have been observed in the horizontal pipe during the experiment. The technique enables realization of the time and position at which particle density fluctuations with respect to dominant time-space levels pass through the pipeline.
The possible relationships between the main emulsion components (namely, Arabic gum, xanthan gum, and orange oil) and the physicochemical properties of orange beverage emulsion were evaluated by using response surface methodology. The physicochemical emulsion property variables considered as response variables were emulsion stability, viscosity, fluid behavior, zeta-potential, and electrophoretic mobility. The independent variables had the most and least significant ( p < 0.05) effect on viscosity and zeta-potential, respectively. The quadratic effect of orange oil and Arabic gum, the interaction effect of Arabic gum and xanthan gum, and the main effect of Arabic gum were the most significant ( p < 0.05) effects on turbidity loss rate, viscosity, viscosity ratio, and mobility, respectively. The main effect of Arabic gum was found to be significant ( p < 0.05) in all response variables except for turbidity loss rate. The nonlinear regression equations were significantly ( p < 0.05) fitted for all response variables with high R (2) values (>0.86), which had no indication of lack of fit. The results indicated that a combined level of 10.78% (w/w) Arabic gum, 0.56% (w/w) xanthan gum, and 15.27% (w/w) orange oil was predicted to provide the overall optimum region in terms of physicochemical properties studied. No significant ( p > 0.05) difference between the experimental and the predicted values confirmed the adequacy of response surface equations.
Microfluidics-based lab-on-chip (LOC) systems are an active research area that is revolutionising high-throughput sequencing for the fast, sensitive and accurate detection of a variety of pathogens. LOCs also serve as portable diagnostic tools. The devices provide optimum control of nanolitre volumes of fluids and integrate various bioassay operations that allow the devices to rapidly sense pathogenic threat agents for environmental monitoring. LOC systems, such as microfluidic biochips, offer advantages compared to conventional identification procedures that are tedious, expensive and time consuming. This paper aims to provide a broad overview of the need for devices that are easy to operate, sensitive, fast, portable and sufficiently reliable to be used as complementary tools for the control of pathogenic agents that damage the environment.
In this study, a new magnetorheological (MR) grease was made featuring plate-like carbonyl iron (CI) particles, and its magnetic field-dependent rheological properties were experimentally characterized. The plate-like CI particles were prepared through high-energy ball milling of spherical CI particles. Then, three different ratios of the CI particles in the MR grease, varying from 30 to 70 wt% were mixed by dispersing the plate-like CI particles into the grease medium with a mechanical stirrer. The magnetic field-dependent rheological properties of the plate-like CI particle-based MR grease were then investigated using a rheometer by changing the magnetic field intensity from 0 to 0.7 T at room temperature. The measurement was undertaken at two different modes, namely, a continuous shear mode and oscillation mode. It was shown that both the apparent viscosity and storage modulus of the MR grease were heavily dependent on the magnetic field intensity as well as the CI particle fraction. In addition, the differences in the yield stress and the MR effect between the proposed MR grease featuring the plate-like CI particles and the existing MR grease with the spherical CI particles were investigated and discussed in detail.
The conventional powder flow testers require sample volumes larger than 40g and are met with experimental hiccups due to powder cohesion. This study designed a gas-pressurized dispersive powder flow tester where a high velocity air is used to disaggregate powder (9g) and eliminate its cohesion. The pressurized gas entrained solid particles leaving an orifice where the distance, surface area, width and weight of particle dispersion thereafter are determined as flow index. The flow indices of seven lactose grades with varying size, size distribution, shape, morphology, bulk and tapped densities characteristics were examined. They were compared against Hausner ratio and Carr's index parameters of the same powder mass. Both distance and surface area attributes of particle dispersion had significant negative correlations with Hausner ratio and Carr's index values of lactose. The distance, surface area and ease of particle dispersion varied proportionately with circular equivalent, surface weighted mean and volume weighted mean diameters of lactose, and inversely related to their specific surface area and elongation characteristics. Unlike insensitive Hausner ratio and Carr's index, an increase in elongation property of lactose particles was detectable through reduced powder weight loss from gas-pressurized dispersion as a result of susceptible particle blockage at orifice. The gas-pressurized dispersive tester is a useful alternative flowability measurement device for low volume and cohesive powder.
In this study the possibility of replacing current surfactants in chocolate formulations with natural lipids extracted from spinach leaf (SPLIP) or spinach chloroplast (CH.SPLIP) was evaluated. SPLIP and CH.SPLIP were extracted with chloroform/methanol following enzyme deactivation with hot isopropanol. Results showed a higher extraction yield for SPLIP while glycolipids were more concentrated in CH.SPLIP. Sugar/oil suspensions with dispersed volume fractions of 0.28, 0.33 and 0.37 containing 0.1% to 0.7% (w/w) surfactant (SPLIP, CH.SPLIP, lecithin and PGPR as commercial references) based on oil phase were prepared and analyzed in shear rheology. Apparent viscosity at 40 s-1 was significantly lower for the natural surfactants compared to lecithin at 0.5-0.7% (w/w) addition. With regard to yield stress, taken as the shear stress at 5 s-1, both natural surfactants showed comparable performance to PGPR at 0.3% to 0.7% addition. As SPLIP and CH.SPLIP behaved similar (p > 0.05), SPLIP, due to higher extraction yield, would be the preferred choice for application in chocolate matrices.
The synthesis of kojic acid derivative (KAD) from kojic and palmitic acid (C16:0) in the presence of immobilized lipase from Rhizomucor miehei (commercially known as Lipozyme RMIM), was studied using a shake flask system. Kojic acid is a polyfunctional heterocycles that acts as a source of nucleophile in this reaction allowing the formation of a lipophilic KAD. In this study, the source of biocatalyst, Lipozyme RMIM, was derived from the lipase of Rhizomucor miehei immobilized on weak anion exchange macro-porous Duolite ES 562 by the adsorption technique. The effects of solvents, enzyme loading, reaction temperature, and substrate molar ratio on the reaction rate were investigated. In one-factor-at-a-time (OFAT) experiments, a high reaction rate (30.6 × 10-3 M·min-1) of KAD synthesis was recorded using acetone, enzyme loading of 1.25% (w/v), reaction time of 12 h, temperature of 50 °C and substrate molar ratio of 5:1. Thereafter, a yield of KAD synthesis was optimized via the response surface methodology (RSM) whereby the optimized molar ratio (fatty acid: kojic acid), enzyme loading, reaction temperature and reaction time were 6.74, 1.97% (w/v), 45.9 °C, and 20 h respectively, giving a high yield of KAD (64.47%). This condition was reevaluated in a 0.5 L stirred tank reactor (STR) where the agitation effects of two impellers; Rushton turbine (RT) and pitch-blade turbine (PBT), were investigated. In the STR, a very high yield of KAD synthesis (84.12%) was achieved using RT at 250 rpm, which was higher than the shake flask, thus indicating better mixing quality in STR. In a rheological study, a pseudoplastic behavior of KAD mixture was proposed for potential application in lotion formulation.
The influence of oyster mushroom (pleurotus sajor-caju, PSC) powder on the physical
properties of herbal seasoning (HS) was investigated. The pH, total solid, viscosity, rheology
and texture of semi solid HS containing different PSC powder level (0%, 20%, 40%, 60%,
8%, 100% w/w) of coconut milk powder were measured. The pH of the products were in the
range of 4.05 - 4.15. Rheological behavior was characterized by oscillatory rheometry. Stress
sweep, frequency sweep and steady stress experiments were conducted to study the behavior
of the products. The products showed non Newtonian characteristic or shear thinning. All
samples were G’> G’’ showed the gel like network. In addition, the back extrusion rig texture
analysis showed the correlation among the samples were also studied. Total substitution of PSC
powder (100% w/w) in the formulation resulted more viscous product and the combination
of the coconut milk powder and PSC powder showed the best spreadability and flow to the
product characteristics. No added PSC powder (0% w/w) showed the least viscous products
and the less moduli among the samples studied. The present study suggested the incorporation
of more than 40% PSC powder to replace coconut milk powder give better flowability and not
affect the viscosity of the products.
The structural and hydrodynamic features for granules were characterized using settling experiments, predefined mathematical simulations and ImageJ-particle analyses. This study describes the rheological characterization of these biologically immobilized aggregates under non-Newtonian flows. The second order dimensional analysis defined as D2=1.795 for native clusters and D2=1.099 for dewatered clusters and a characteristic three-dimensional fractal dimension of 2.46 depicts that these relatively porous and differentially permeable fractals had a structural configuration in close proximity with that described for a compact sphere formed via cluster-cluster aggregation. The three-dimensional fractal dimension calculated via settling-fractal correlation, U∝l(D) to characterize immobilized granules validates the quantitative measurements used for describing its structural integrity and aggregate complexity. These results suggest that scaling relationships based on fractal geometry are vital for quantifying the effects of different laminar conditions on the aggregates' morphology and characteristics such as density, porosity, and projected surface area.
Carbonyl iron particles (CIPs) is one of the key components in magnetic rubber, known as magnetorheological elastomer (MRE). Apart from the influence of their sizes and concentrations, the role of the particle' shape is pronounced worthy of the attention for the MRE performance. However, the usage of CIPs in MRE during long-term applications may lead to corrosion effects on the embedded CIPs, which significantly affects the performance of devices or systems utilizing MRE. Hence, the distinctions between the two types of MRE embedded in different shapes of spherical and plate-like CIPs, at both conditions of non-corroded and corroded CIPs were investigated in terms of the field-dependent rheological properties of MRE. The plate-like shape was produced from spherical CIPs through a milling process using a rotary ball mill. Then, both shapes of CIPs individually subjected to an accelerated corrosion test in diluted hydrochloric (HCl) at different concentrations, particularly at 0.5, 1.0, and 1.5 vol.% for 30 min of immersion time. Eight samples of CIPs, including non-corroded for both CIPs shapes, were characterized in terms of a morphological study by field emission scanning electron microscope (FESEM) and magnetic properties via vibrating sample magnetometer (VSM). The field-dependent rheological properties of MREs were analyzed the change in the dynamic modulus behavior of MREs via rheometer. From the application perspective, this finding may be useful for the system to be considered that provide an idea to prolong the performance MRE by utilizing the different shapes of CIPs even when the material is fading.
Proper design of stent for application at specific aneurysm effect arteries could help to reduce the issues with thrombosis and aneurysm. In this paper, four types of stent configuration namely half-Y (6 mm), half-Y (4 mm), cross-bar, and full-Y configuration will implanted on real 3D artery bifurcation aneurysm effected arteries. Comparisons were then conducted based on the flow patterns after stent placement using both LBM-based solver and PIV experimental findings. According to the data obtained from all 4 stent designs, the flow profiles and the computed velocity from both methods were in agreement with each other. Both methods found that half-Y (6 mm) stent configuration is by far the best configuration in reducing the blood velocity at the vicinity of the aneurysm sac. The analysis also show that the half-Y (6 mm) stent configuration recorded the highest percentage of velocity reduction and managed to substantially reduce the pressure at the bifurcation region. This high flow velocity reduction through the use of half-Y stent could consequently promote the formation of thrombus thereby reducing the risk of rupture in the aneurysm sac.
β-Lactoglobulin (β-lg) can produce fibrils that have multi-functional properties. Impacts of different stirring speeds on characteristics of β-lg fibrils as a stable form in β-lg fibril solutions were investigated. Fibril concentration, fibril morphology, turbidity, particle size distribution, zeta potential, and rheological behavior of solutions were studied. Stirring enhanced fibril formation and stability of a fibril solution, in comparison with unstirred solutions. Increasing the stirring speed produced more turbidity and a greater distribution of particle sizes, higher viscosity values, but no differences in zeta potential values of β-lg fibril solutions. However, a high stirring speed is not feasible due to reduction of the fibril yield and changes in fibril morphology.
The rheological properties, microstructure, textural properties, colour and droplet size distribution of mayonnaise-like emulsion models prepared using 10-30wt.% of palm olein-based diacylglycerol (POL-DAG) oil were compared with those of the control (100wt.% VCO) model. There were significant (P<0.05) differences in the particle size distribution of the oil droplets, the textural properties, and the rheological properties of the various emulsion models. The rheological analysis included the determination of the flow curves, yield stress, thixotropy, apparent viscosity, and viscoelastic parameters. The concentrated oil-in-water (O/W) emulsion with 30wt.% POL-DAG substitution exhibited high thixotropy. The POL-DAG content had a substantial effect on the rheological properties of yield stress, storage modulus (G') and loss modulus (G″). The pseudoplastic behaviour of the emulsions was demonstrated. The size of the particles in the 30% POL-DAG-substituted emulsion was dramatically increased after one day and 30days of storage. All of the emulsion samples with POL-DAG substituted for VCO showed a relatively non-uniform bimodal droplet size distribution after one day of storage. In general, substitution of 10-20wt.% POL-DAG oil is appropriate for preparing O/W emulsions that had flow curves and textural properties similar to those of the control sample.
The steady-state flow test was conducted on pink-fleshed guava, pink-fleshed pomelo and soursop juice concentrates using a rheometer to understand its rheological behaviour. The power law model was used and a master-curve was created using the shear rate-temperature-concentration superposition technique to predict rheological properties from a wide range of temperatures and concentrations. All three juice concentrates undergo a double horizontal shift whilst the pink-fleshed guava required an additional vertical shift. The final equations show shear-thinning behaviour of pink-fleshed guava, pink-fleshed pomelo and soursop with flow behaviour index of 0.2217, 0.7507 and 0.6347, respectively. The final master-curve predicts shear stress at wide range of shear rates, i.e. between 10-2 and 106 s-1 for the pink-fleshed guava, 100 and 106 s-1 for the pink-fleshed pomelo and 100 and 107 s-1 for the soursop. The results provide useful information and effective technique to predict fruit juice concentrates behaviour affected by heat changes during processing.
This study aims to investigate the use of palm olein as the oil phase for betamethasone 17-valerate (BV) emulsions. The physicochemical properties of the formulations were characterized. In vitro drug release study was performed with the Hanson Vertical Diffusion Cell System; the samples were quantified with HPLC and the results were compared with commercial products. Optimized emulsion formulations were subjected to stability studies for 3 months at temperatures of 4, 25, and 40°C; the betamethasone 17-valerate content was analyzed using HPLC. The formulations produced mean particle size of 2-4 μm, viscosities of 50-250 mPa.s, and zeta potential between -45 and -68 mV. The rheological analyses showed that the emulsions exhibited pseudoplastic and viscoelastic behavior. The in vitro release of BV from palm olein emulsion through cellulose acetate was 4.5 times higher than that of commercial products and more BV molecules deposited in rat skin. Less than 4% of the drug was degraded in the formulations during the 3-month period when they were subjected to the three different temperatures. These findings indicate that palm olein-in-water emulsion can be an alternative vehicle for topical drug delivery system with superior permeability.
The incorporation of kenaf fiber fillers into a polymer matrix has been pronounced in the past few decades. In this study, the effect of multiwalled carbon nanotubes (MWCNTs) with a short kenaf fiber (20 mesh) with polypropylene (PP) added was investigated. The melt blending process was performed using an internal mixer to produce polymer composites with different filler contents, while the suitability of this melt composite for the injection molding process was evaluated. Thermogravimetric analysis (TGA) was carried out to investigate the thermal stability of the raw materials. Rheological analyses were conducted by varying the temperature, load factor, and filler content. The results demonstrate a non-Newtonian pseudoplastic behavior in all samples with changed kenaf fillers (10 to 40 wt %) and MWCNT contents (1 to 4 wt %), which confirm the suitability of the feedstock for the injection molding process. The addition of MWCNTs had an immense effect on the viscosity and an enormous reduction in the feedstock flow behavior. The main contribution of this work is the comprehensive observation of the rheological characteristics of newly produced short PP/kenaf composites that were altered after MWCNT additions. This study also presented an adverse effect on the composites containing MWCNTs, indicating a hydrophilic property with improved water absorption stability and the low flammability effect of PP/kenaf/MWCNT composites. This PP/kenaf/MWCNT green composite produced through the injection molding technique has great potential to be used as car components in the automotive industry.
A study was conducted to evaluate the cross flow tubular ultrafiltration behavior of aqueous solutions of pectin. The effectiveness of pulsatile flow as a cleaning-in-place (CIP) technique to improve permeate flux was undertaken on the above mentioned solution. This investigation is part of a study to apply membrane filtration in the clarification of tropical fruit juice. The main variables, which were investigated, include the concentration of pectin, pulse frequency and amplitude. It was found that the amount of pectin in the solution significantly affects its ultrafiltration behavior. From the observed profiles, it is evident that the formation of gel layer on the membrane surface is responsible for the leveling of flux at high pressures. The presence of pectin was found to affect the properties of the solution such as viscosity, pH and the size of pectin colloid. Improvements in the permeate flux for pectin solution were obtained by employing pulsatile flow cleaning-in-place technique. Both pulse frequency and amplitude are important parameters that can improve the improvement of in-situ cleaning method. Similar to several findings reported in the literature, pulsatile flow showed significant effectiveness of about 60% higher flux when the ultrafiltration process is operated under laminar condition.
The transient response of magnetorheological (MR) materials, in general, is very important for design consideration in MR-based devices. Better response to magnetic fields is beneficial for a better response rate to the electrical current applied in the electromagnetic coil. As a result, MR-based devices would have a high response to external stimuli. In this work, the principal characteristics of magnetorheological greases (MRGs) which have two different particle shapes are experimentally investigated. One type of particle distributed in the grease medium is conventional spherical-shaped carbonyl iron (CI) particles, while the other is plate-like CI particles made using a high-energy rotary ball mill from spherical CI particles. A set of bidisperse MRG samples are firstly prepared by adjusting the weight percentage of the plate-like CI particles and mixing with the spherical CI particles. Subsequently, three important properties of MRGs in terms of their practical application are measured and compared between the two different particle shapes. The field-dependent apparent viscoelastic properties of the prepared MRG samples are measured, followed by the field-dependent storage and loss moduli using an oscillatory shear rheometer. In addition, the transient response time, which indicates the speed in the actuating period of MRGs, is measured by changing the strain amplitude. Then, a comparative assessment on the three properties are undertaken between two different particle shapes by presenting the corresponding results in the same plot. It is shown that the bidisperse MRG with plate-like CI particles exhibits an increase in the initial apparent viscosity as well as stiffness property compared to the MRG with spherical particles only.