Diffusion Foundations and Materials Applications Vol. 37

Abstract: In this work, the effect of peat clay particles (PCP) was investigated as pore former of polysulfone (PSf) hollow fiber membrane properties. Preparation of polysulfone membrane dope solution conducted by phase inversion technique using wet spinning method. A homogeneous dope solution is added with peat clay from four composition variations of 0-6 wt%. Followed by mixed dope until homogeneous for an hour at room temperature (~29 °C). The preparation of peat clay before used is by having it calcinated at 600 °C for 1 hour, then sifted to a size of 120 mesh. The hollow fiber membrane is casted using the wet spinning method with the dope solution flow rate set at 4 mL/min and the bore fluid flow rate at 4 mL/min. The hollow fiber membrane that has been formed is analyzed by FTIR, contact angle, water absorption, and porosity. The characteristics of the membrane show that the functional group in the addition of peat clay in the absorption of Si-OH and Si-O-Si. The specific spectrum of PSf-PEG/PC is indicated by peak wavenumbers 872 – 874 cm^-1. Polysulfone hollow fiber membrane mixed with peat clay shows the contact angle on the membrane surface shows hydrophobic characteristics without addiction of peat clay particles and become slightly hydrophilic with peat clay addiction of 71.28°. In addition, water absorption in each sample increases with the addition of peat clay from 0 to 4 wt%. The ability of water absorption increased to 32.51%, and membrane porosity increased from 23.66% to 38.87%. It is concluded that polysulfone hollow fiber membranes are enhanced by adding peat clay as a pore builder and hydrophilic additives and become less fouling in future application for water/wastewater treatment.Keywords: Peat clay, hollow fiber membrane, polysulfone, wet spinning, montmorillonite

Abstract: The application of membrane technology in the separation process has led to the technology's present rapid development. Nylon 6.6 polyamide membrane has hydrophilic properties and has advantages such as low fouling tendency and resistance to high temperatures. This research aims to determine the effect of pectin on the characteristics of nylon 6.6 membranes. In this study, the membrane was made from nylon 6.6 using the phase inversion technique. Modification was carried out by adding pectin at variations of 0, 0.25, 0.5, and 0.75% by weight. The IR structure characterization results of the nylon6.6-pectin membrane show the same peak for the-NH group and the OH, C-H, amide I, amide II, amide III, CH₂, and C-C groups. Membrane contact angle measurements P0, P0.25, P0.5, and P0.75 were 59.37°, 67.70°, 63.48°, and 58.00° respectively, indicating hydrophilic properties. Meanwhile, the degree of swelling after the membrane was soaked in distilled water for 24 hours showed values of 55.32%, 44.44%, 60.38%, and 63.16% for membranes P0, P0.25, P0.5, and P0.75. The P0.75 membrane has the lowest contact angle which is increasingly hydrophilic and the highest swelling value which indicates the highest absorption level compared to other variations.

Abstract: Calcium hydroxide (Ca (OH)₂) is an intracanal medicament used as a disinfectant in cases of tooth inflammation with ad dubia prognosis. The success of root canal treatment depends on the ability of intracanal medicaments to eliminate pathogenic bacteria present in the walls of narrow and complex root canals by releasing calcium and hydroxyl ions at the closest contacts. This study aimed to evaluate the effect of particle size on the ability to penetrate Ca (OH)₂ in the coronal, middle, and apical root canals. Fifteen mandibular premolars extracted for orthodontic and periodontal purposes were collected and cut to produce root canals with a length of 12 cm. The root canals were then prepared with a Protaper SX-F3 needle and irrigated using a solution of 2.5% NaOCl, NaCl, and 17% EDTA as lubrication at each needle change. Ca (OH)₂ with different particle sizes in paste form was manipulated with distilled water at a concentration of 0.8 g/mL then the paste was applied to the prepared tooth root canals and covered with a temporary filling. The samples were then stored in an incubator at 37 °C for 7 days. Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX) was performed on the transverse surfaces of the coronal 1/3, middle 1/3 and apical 1/3 of the tooth. The maximum penetration depth was evaluated by measuring the maximum distance between the dentin canal wall and Ca (OH)₂ present in the dentinal tubules. In all three zones, the Ca (OH)₂ nanoparticles had a greater penetration depth than the Ca (OH)₂ nanoparticles (P<0.001). In both groups, the penetration depth increased from the apical to the coronal section. All differences in the penetration test ability of the Ca (OH)₂ nanoparticles and Ca (OH)₂ microparticles at all depths of the surface. Ca (OH)₂ nanoparticles penetrate deeper into the dentinal tubules than Ca (OH)₂ microparticles do.

Abstract: The quasi-lattice theory (QLT) is utilized for the prediction of the temperature and concentration dependence of the thermodynamic properties of the molten CdSn alloys. At first, the analytical expressions are employed to reckon the excess Gibbs free energy of mixing, Gibbs free energy of mixing, activity, enthalpy of mixing and entropy of mixing as well as concentration fluctuations, short range-order parameter and excess stability function ofCdSn melts at 773 K. For this, the model parameters i.e. size ratio and order energy parameter are assessed using the experimental data of the free energy of mixing for CdSnmelts at 773 K. The theoretical values of the thermodynamic functions are in well harmony with the interrelated experimental values. The theoretical values of the structure function like concentration fluctuations are in unison with the experimental values for molten CdSn system at 773 K. Again, the optimization procedure is applied to explore the excess Gibbs free energy of mixing, activity, concentration fluctuations, short-range order parameter and excess stability function at different temperatures for CdSnmelts. The present study discloses that the stability as well as the segregating nature of CdSnmelts decrease with the elevation of the temperature from 773 K to 1123 K. Further, the temperature dependency of the excess stability function reveals that there is a probability of transition from segregating character to the ordering character of CdSn melts near 1162 K. Keywords: Gibbs free energy of mixing; entropy of mixing; concentration fluctuations; short-range order parameter; excess stability function

Abstract: Nanocomposites, comprising reduced graphene oxide (rGO) and iron oxide nanoparticles (Fe₃O₄) have emerged as promising materials for various applications due to their exceptional properties. However, a critical research gap exists in understanding the electrostatic potential distribution within these complex molecular structures. This study aims to address this gap by employing advanced computational techniques to visualize the electrostatic potential within rGO/ Fe₃O₄ nanocomposites at the molecular level. The primary objective of this study is to map the spatial distribution of the electrostatic potential within rGO/Fe₃O₄ nanocomposites. This will provide molecular-level insights into the electrostatic environment and its influence on electronic structure, reactivity, and intermolecular interactions. By correlating the electrostatic potential with material properties, such as reactivity and stability, we aim to enable the rational design of improved nanocomposites. The novelty of this research lies in its interdisciplinary approach, bridging materials science, chemistry, and physics. The outcomes are expected to have significant implications for optimizing the performance of rGO/Fe₃O₄ nanocomposites in applications ranging from energy storage to catalysis and beyond. This study contributes to our fundamental understanding of nanocomposite behavior and paves the way for enhanced materials design.

Abstract: Sidoarjo mud contains 48.3% silica which is considered as the biggest impurity when compared to the content of rare earth metals which are 0.3% Eu and 0.02% Yb. The hydrothermal process is used to bind silica as a form of silica extraction activity in the Sidoarjo mud so that the Rare Earth Elements are purified further because their uses are urgently needed. This process compares the alkalis in the form of Na₂CO₃ and K₂CO₃ which are basic salts which will then be compared to the most optimum conditions of the two alkalis. Each alkali will be processed under operating conditions following the Taguchi method which aims to minimize research and optimize research results. Based on the research results, it was found that K₂CO₃ provided better silica recovery than Na₂CO₃ under operating conditions with a K₂CO₃ concentration of 2 M, 1 hour soaking time, 700°C melting temperature and 3 hours melting time, giving 95.24% silica recovery. In addition, by using the Taguchi method it can be analyzed that the main factors affecting the melting of the alkali are the melting time, the concentration of the alkali, the temperature of the melting, and the immersion time.

Abstract: Tire mobility with low compaction for off-road tires is considered necessary. In this regard, it is imperative to investigate the tire/ground interaction and finite element method has the capability to perform the fundamental analyses and simulations to present the results accordingly. A two-dimensional (2D) low-fidelity model pertaining to an off-road tire for a relatively light autonomous vehicle rolling on ground with consideration of different values of slipping percentages was simulated using a finite element (FE) software ABAQUS. A comprehensive parametric study was conducted to understand the essential effects on the tire/ground interaction specifically, the vertical stress distribution in the ground right beneath the tire after travelling a specific amount of time. The effect of several parameters including the autonomous vehicle weight, friction coefficient between the tire and the ground, Young’s modulus of tire as well as various types of ground such as natural soil, sand and soft soil (clay) were scrutinized and are discussed in detail. Keywords: Tire/ground interaction; Tire slipping; Soil compaction; Vertical stress distribution; Finite element method (FEM).

Abstract: Mangrove is an essential coastal vegetation with multiple abilities to protect the land from any hazards that come from the sea, also provides a contribution to combat global climate change by sequestering the carbon in the atmosphere on its stem and root system. Measuring the amount of carbon that can be stored by mangroves using terrestrial surveys is relatively challenging due to the harsh environment. Therefore, an optional method using satellite remote sensing and spatial modeling using Geographic Information Systems (GIS) is needed. This research will combine field sampling and a GIS approach to estimate how much mangroves can store in the research area with spatial interpolation techniques i.e., kriging, spline, topo to raster, and nearest neighbor. To check the accuracy, Root Mean Square Error (RMSE) was used. The most accurate model among others is Spline With Barrier with an RMSE of about 1.82 Mg C Ha-1 with a range of Above-Ground Carbon (AGC) values from 13.94 Mg C Ha-1 to 142.43 Mg C Ha-1. In conclusion, spatial interpolation may assist the mangrove’s carbon spatial modelling with promising accuracy.