bluuebunny/crossref_metadata_2025 huggingface dataset:
Finding the fundamental solution of the bi-axially symmetric Laplace–Beltrami equation using generalized shift operator
Authors: Mavlyaviev R M , Garipov I B , Sadykova E R , Razumova O V
Published: November 2021

Many physical processes are described by partial differential equations. The relevance of this study is due to the need to solve applied problems of quantum mechanics, the theory of elasticity, and heat capacity. In this paper, an equation is considered that describes the field created by a contour with two axes of symmetry. The purpose of the study is to find a fundamental solution to this equation, which can later be used when solving boundary value problems.
Nonequilibrium evolution thermodynamic of poly- and two-components alloys affected by severe plastic deformation
Authors: Metlov L , Gordey M
Published: November 2021

The nonequilibrium evolutionary thermodynamics approach is generalized to the case of alloys prone to structural martensitic and diffusion phase transitions in them. A system of kinetic equations is written out to describe the evolution of the density of structural defects, grain boundaries, dislocations and point defects, as well as for the order parameter in the processing of these alloys by the severe plastic deformation way. The approach is illustrated by the numerical experiments results on a specific example of two-component copper-based alloys. Kinetic curves of the evolution of the grain boundaries, dislocations and atoms dissolved in a copper matrix are obtained, qualitative phase diagrams are constructed.
Bifurcation phenomenon in molecular dynamics model of coalescence/sintering on the nanoscale
Authors: Samsonov V M , Puytov V V , Talyzin I V
Published: November 2021

Using the isothermal molecular dynamics, coalescence/sintering of Au nanoparticles (NPs) was simulated. We have found that the solid NP sintering scenario is switched to the coalescence scenario not at the NP melting temperature T
m exactly but at a lower temperature T
0 ≈ 0.9T
m interpreted as the critical temperature corresponding to a coalescence/sintering bifurcation phenomenon: in the temperature range from T
0 – 2 K to T
0 + 2 K to the resulting (daughter) NPs of the same size can have either liquid-like or crystalline structure after coalescence/sintering at the same fixed temperature.
Mirror descent algorithm on the indefinite control horizon
Authors: Shiyan D N , Kolnogorov A V
Published: November 2021

We consider the problem of optimal control in a random environment in a minimax setting as applied to data processing. It is assumed that the random environment provides two methods of data processing, the effectiveness of which is not known in advance. The goal of the control in this case is to find the optimal strategy for the application of processing methods and to minimize losses. To solve this problem, the mirror descent algorithm is used, including its modifications for batch processing. The use of algorithms for batch processing allows us to get a significant gain in speed due to the parallel processing of batches. In the classical statement, the search for the optimal strategy is considered on a fixed control horizon but this article considers an indefinite control horizon. With an indefinite horizon, the control algorithm cannot use information about the value of the horizon when searching for an optimal strategy. Using numerical modeling, the operation of the mirror descent algorithm and its modifications on an indefinite control horizon is studied and obtained results are presented.
Polynomials, numerical triangles and sequences associated with the probability distribution of the hyperbolic cosine type for odd values of the parameter
Authors: Tokmachev M S
Published: November 2021

The article introduces a new class of polynomials that first appeared in the probability distribution density function of the hyperbolic cosine type. With an integer change in one of the parameters of this distribution, polynomials in the form of a product of positive factors are written out with an increasing degree. Earlier, the author found a connection between the distribution of the hyperbolic cosine type and numerical sets, in particular, in the simplest cases with the triangle of coefficients of Bessel polynomials, the triangle of Stirling numbers, sequences of coefficients in the expansion of various functions, etc. Also from the distribution formed numerous numerical sequences, both new and widely known. Consideration of polynomials separately from the density function made it possible to reconstruct numerical sets of coefficients, ordered in the form of numerical triangles and numerical sequences. The connections between the elements of the sets are established. Among the sequences obtained, in the simplest cases, there are those known from others, for example, physical problems. However, the overwhelming majority of the found number sets have not been encountered earlier in the literature. The obvious applications of this research are number theory and algebra. And the interdisciplinarity of the results indicates the possibility of applications and enhances their practical significance in other areas of knowledge.
Study of succinic anhydride amidation by 2-aminothiazol
Authors: Tyurina T G , Kryuk T V , Kudryavtseva T A , Semenova R G , Romanenko N A , Volkova G K
Published: November 2021

The reaction between succinic anhydride and 2-aminothiazole was carried out in polar organic solvents (acetone, 1,4-dioxane, isopropanol) and in a mechanochemical reactor. By of X-ray phase analysis, IR, 1H, 13C NMR spectroscopy it was found that in both techniques of carrying out the reaction, the only product was succinamide. It was shown that the process efficiency in the mechanochemical reaction conditions is higher in comparison with the traditional solution’s synthesis. The solid-phase interaction development was proceeded during 45 days after load removed, it was especially intense in the first 10 days.
Application of super cells for quantum-mechanical calculations of the mixing enthalpy of the BCC-phase of the Fe-V system for the basic state
Authors: Udovsky A L , Kupavtsev M V
Published: November 2021

In this work, the super-cells were used for quantum mechanical calculations of the mixing enthalpia of the BCC phase of the Fe-V system for the ground state. The values of total energy were calculated using 16 -th and 54- atomic super-cells for both clean components and alloys. The mixing enthalpy (ΔH) for the BCC phase was calculated on four 16- and 54- atomic super-cells in the vicinity of pure components, on the basis of which the dependence of the concentration ΔH for BCC alloys in the ferromagnetic state of the Fe-V system of the ground state was built.
Selective oxidation of AlGaAs aperture layers of a Vertical-cavity surface-emitting laser with a generation wavelength of 850 nm
Authors: Voropaev K O , Grebennikov V A , Zhelannov A V , Prokhorov A Yu , Seleznev B I
Published: November 2021

A study of the technology of selective oxidation of the buried AlGaAs layer used as an aperture layer in the structure of a Vertical-cavity surface-emitting laser has been carried out. Oxidation process was made as thermal oxidating in a humidified nitrogen atmosphere. The conditions of the oxidation process are described, images of the oxidation results and the dependence of the growth rate of the oxidized layer on the process temperature are presented. A technology for the formation of an oxide current aperture has been developed for vertical cavity surface emitting lasers with a generation wavelength of 850 nm, which makes it possible to accurately control the size and shape of the resulting aperture.
Toward a relativistic microscopic substantiation of thermodynamics: classical relativistic many-particle dynamics
Authors: Zakharov A Yu , Zubkov V V
Published: November 2021

An exact closed relativistic kinetic equation is derived for a system of identical classical particles interacting with each other through a scalar field. The law of variation of the energy of a system of particles in terms of the microscopic distribution function is obtained.
Data transformations when constructing a composite system quality index
Authors: Zhgun T V
Published: November 2021

The features of the data distribution can significantly affect the composite characteristics of objects, so composite indexes of objects must necessarily take into account the features of the data. Some types of data are characterized by distributions with a significant anomaly, when the vast majority of observations are concentrated near the boundary values. This type of data cannot always be characterized by an asymmetry coefficient. In addition, if the values of a variable are approximately symmetric with respect to zero or are concentrated near zero, the sample cannot also be characterized by the coefficient of variation. The paper proposes a transformation that allows us to identify the anomalous nature of variables using the signal-to-noise ratio. Variables are evaluated in the standard range, which is shifted to the right relative to zero. If it is necessary to logarithm, such a transformation will avoid the pressure of small values of variables that, after direct logarithm, would have large negative values. The application of logarithmic correction for the detected anomalous variables redistributes the values of the obtained weighting coefficients in the direction of a more correct interpretation and, in particular, solves the problem with the negativity of the weighting coefficients.
Synthesis, characterization and Stydy thermal stabilization effect of calcium complex of anthocyanin on the poly (vinyl chloride)
Authors: Ali Hikmat A , Shnawa Hussein A , Abidalimam Dhiaa A
Published: November 2021

In this study, calcium complex of anthocyanin was synthesized from anthocyanin, a flavonoid type natural phenolic product, which was extracted from eggplant peel. The structure of Ca-anthocyanin was characterized by FTIR spectroscopy. Its efficiency as bio-based thermal stabilizer to stabilize poly (vinyl chloride) was investigated and compared to that of Reapak B-NT/7060, a Ca/Zn-based commercial stabilizer. The influence of Ca-anthocyanin complex on the thermal degradation reaction of PVC was monitored by differential scanning calorimetry (DSC). The results indicated that the Ca-anthocyanin complex is an efficient thermal stabilizer and it reduces the rate of dehydrochlorination reaction of PVC already at a concentration as small as 2 phr, part per hundred of PVC resin. The thermal degradation reaction of PVC through the first degradation stage is clearly limited by the addition of Ca-anthocyanin complex as single (primary) stabilizer. Its efficiency is similar to that of Reapak B-NT/7060 used as reference stabilizer and it can enhance the performance of commercial stabilizer when used as co-stabilizer at mixing ratio (1:1). This study has allowed verifying and validating the usefulness of environmental friendly thermal stabilizer for PVC with very evident stabilization effect.
Preparation of Ethanol-Free Hand Sanitizers Gels and Studying its Sterile Efficacy
Authors: Fahad Mahmood M. , Al-Khuzaie Mohammed G.A.
Published: November 2021

Due to the spread of the Corona pandemic, the demand for hand sanitizers has increased dramatically. This led to a global scarcity of sterilizers. Therefore, this study was performed to produce and evaluate the effectiveness of new commercially available, cheap and ethanol-free hand sanitizers from various sources. The new hand sanitizers were prepared by mixing (glycerin) as a moisturizer and (carbomer) as thickening agents to form the gel with (tri-ethanolamine base) as pH neutralizer and (Tea tree oil, Aloe vera extract or Povidone 10%) respectively as antiseptic agents. All prepared hand sanitizers were examined with four kinds of bacteria (Enterococcus faecalis, E. coli, Pseudomonas aeruginosa and Staphylococcus aureus) And two kinds of fungi (Candida albicans and Aspergillus flavus). The prepared hand sanitizer gels showed good sterilization efficacy and similar to commercially prepared hand sanitizers (70% ethanol).
Removal of Carcinogenic Dyes Congo red (CR) and Bismarck brown Y (BBY) by Adsorption onto Reusable Hydrogels Derived from Acrylamide
Authors: Al-Niaeem Huda S , Abdulwahid Ali A , Hanoosh Whidad S
Published: November 2021

Hydrogels of acrylamide (AM), acrylamide\ 2-acrylamido-2-methyl-1-propane sulphonic acid (AMS), and acrylamide\ 2-acrylamido-2-methyl-1-propane sulphonic acid\graphene oxide (AMSGO) were prepared as adsorbents to remove carcinogenic dyes Congo red (CR) and Bismarck brown Y (BBY) from aqueous solutions. Hydrogels were characterized using FSEM and XRD analyses. For both dyes, the synthesized hydrogels demonstrated high adsorption capability at near-neutral pH. Experimental adsorption data were analyzed using the Langmuir and Freundlich isotherm models. It was found that the Langmuir model was more suitable for the experimental data. Kinetic studies found that the pseudo-second-order model demonstrated the best fitting to the experimental data. In addition, thermodynamic studies suggest that the adsorption process was spontaneous and endothermic. The prepared hydrogels were regenerated and reused in four consecutive cycles and it could be applied to remove anionic dyes from aqueous solutions as an effective adsorbent.
Synthesis, spectroscopic, and thermal studies of azo compounds from luminol and procaine with acetylacetone and their complexes
Authors: AlBaheley Noor Al , Fahad T A , Ali Asaad A
Published: November 2021

This The study entails the synthesis of two newly synthesized azo dyes luminol and procaine with acetylacetone (N1 and N2 correspondingly). Elementalanalysis, 1HNMR, T.G.A, and FTIR. have all been used to characterize dyes. These new dyes were reacted with Cpper and Nikel ionin 1:2 molar ratios to form of complexes of metals (II) with a general stoichiometry; CuL2, and NiL2 in complexes., FT IR, as well as the corresponding metal (II) complex, were used to characterize them. The dye acts as a bidentate ligand, according to elemental analysis and spectral results. The thermal properties of these compounds were investigated using thermogravimetric analysis (TGA). Thermal decomposition of these compounds is a process that occurs in stages.,
Production of biodiesel from heat-treated edible oil
Authors: Ahmed Hamza M , Abdeldaim Siddig O , Erwa Ibrahim Y
Published: November 2021

Among the urgent needs of developing countries are renewable sources of energy and a pollution-free climate. Acid-catalyzed transesterification for production of biodiesel from heat-treated peanut oil was investigated, and the produced biodiesel was characterized. The change in oil properties during the heating process was studied. The results showed an increase in the saponification number with heating time (from 115.47 mg KOH/g for crude oil, to 156.19, 172.7 and 184.68 mg KOH/g after 30, 60 and 120 minutes of heating respectively), a slight decrease in the acid value was observed after heating (from 5.91 to 5.87, 5.87 and 5.88 mg KOH/g after 30, 60, and 120 minutes of heating respectively) There is no obvious change in the refractive index during heating. The peroxide value increased from 2.87 to 3.95 meq O2/kg as the heating time was increased up to 60 minutes. The characteristics of the produced biodiesel were compared to ASTM D 6751 biodiesel standards and ASTM D 975 fossil diesel standards to validate their acceptability as a fuel in diesel engines, and a good agreement was observed. In contrast, to international standards, we notice that ethanol-based fuel has properties that are similar to those of global fuels. Peanut oil can be used to make renewable, low-cost biofuels that can meet a significant portion of the world’s energy needs.
Isolation, Preparation and Characterization of Polylactic Acid Film Reinforced with Nano silica
Authors: Ali Zainab A , Niamah Alaa Karem , Widad Salih Hannosh
Published: November 2021

Lactic acid was isolated by using microbial fermentation in whey media which was carried out by local strain Lactobacillus paraplantarum then polymerized using the acidic medium’s polycondensation method. FTIR and H-NMR were used to characterize the isolated lactic acid monomer and polyalctic acid (PLA), and the results confirmed the chemical structures of the isolated lactic acid and PLA. GPC techniques were used to determine the molecular weight and molecular weight distribution of the prepared PLA; the result showed that the Polydispersity index (PDI) was 2.51. The Biodegradable composite films of poly lactic acid (PLA)/Nano silica powder were prepared by the composite film casting method using dichloromethane as solvent. In contrast, Nano silica was synthesis from hydrolysis of tetra ethoxysilane and was loaded in PLA in 1 to5 wt. %. The films were subjected to a tensile strength study. Thermogravimetric analysis (TGA) and differential thermal analysis (DSC) were used to evaluate PLA. Also, water absorption of the prepared composites was studied, and the result showed that the thermal stability and water absorption of these prepared films were increased with an increasing percentage of Nano silica, while the percentage of crystallinity of the PLA evaluated from DSC was 28 %.
A mathematical optimization model for secondary settler
Authors: Bakiri Zahir
Published: November 2021

The study of secondary settler modelling, which aims to establish the main model (one-dimensional-1D model), which is involved in some fundamental processes of the hydrodynamic behaviour of this liquid/solid separation unit and to engender variations of the sludge blanket height as a function of the operating parameters and maintaining of the municipal wastewater treatment plant of Setif. The objective of this research is focused on solid/liquid separation in the secondary settler by attempting a mathematical model that allows us to evaluate the sedimentation velocity as a function of the sludge settleability parameters.
A review on graft compatibilizer for thermoplastic elastomer blend
Authors: Nitiyah K.K. , Musa Luqman , Rasidi M.S.M. , Rahim Shayfull Zamree Abd , Rahman Rozyanty , Azmi Ahmad Azrem , Rennie Allan
Published: November 2021

A biodegradable thermoplastic elastomer (TPE) blend is developed by blending poly (lactic acid) (PLA) and natural rubber (NR) or epoxidized natural rubber (ENR) and it is a sustainable substitution in recent years for synthetic polymers. PLA is high in mechanical strength and compostable, but it is highly stiff and brittle. The incorporation of NR or ENR to PLA increases the impact strength and toughness of PLA. However, the disparity in polarity between PLA and elastomer phase like NR and ENR results in TPE blend being incompatible. Hence, compatibilization is essential to improve its polarity and develop interactions. Compatibilizer that composed of two different polymer is known is graft compatibilizer with the aid of grafting agent. The graft compatibilizers are divided into two categories. The first type is made up of one polymer and grafting agent and, the other one is composed of two polymer groups and grafting agent. These two types of graft compatibilizer can be prepared via two different method such as direct melt blending and solution. Apart from this, the TPE blend is produced via the melt blending technique with mixing machines such as internal mixer and extruder. This article has reviewed the preparation of the graft compatibilizer and blending technique of TPE. Based on the findings, the graft compatibilizers has a significant role in improving miscibility and compatibility across blend composed of different phase.
A green approach of superhydrophobic surface fabrication on recycled high-density polyethylene using sodium chloride
Authors: Azizan Muhammad Aidil Adz’ryl Nor , Zakaria Muhammad Salihin , Nordin Razif Muhammed , Halim Khairul Anwar Abdul , Lim Bee Ying , Abdurrahman Muslim
Published: November 2021

In this work, the water-dissolved surface modifier method was introduced to recycled high-density polyethylene (rHDPE) matrix to fabricate green superhydrophobic surfaces. Surface cavities on rHDPE are formed by sodium chloride particles which can be readily rinsed off and reused. Water contact angle, self-cleaning properties, and surface morphology were characterized. By creating porosity onto the rHDPE matrix, the surface exhibits an excellent self-cleaning property with a water contact angle larger than 150°. Surface morphology reveals the porosity and roughness of the surface. In this fabricating process, no chemicals are used while rHDPE is selected for the purpose. Based on the findings, it is proven that the superhydrophobic surface can be fabricated with a simple yet green approach.
The potential of using sucrose particles for self-cleaning surface fabrication on recycled high-density polyethylene
Authors: Yap Yee Wen , Zakaria Muhammad Salihin , Nordin Razif Muhammed , Halim Khairul Anwar Abdul , Lim Bee Ying , Abdurrahman Muslim
Published: November 2021

Degradation properties of recycled plastic causing it less widely used. By adding extra physical properties, its commercial value and usage can be increased. In this current work, green self-cleaning surfaces from recycled high-density polyethylene (rHDPE) were fabricated using sucrose particles. Water contact angle and sliding angle, self-cleaning properties and surface morphology were characterized. Furthermore, the surface texture was also evaluated by conducting a surface roughness test. By creating porosity onto the rHDPE matrix, the surface exhibits an excellent self-cleaning property with a water contact angle larger than 150°. Surface morphology reveals the porosity and roughness of the surface. In this fabricating process, no chemicals were used while rHDPE is selected for the purpose. Hence, the process is environmentally friendly and low cost for self-cleaning surface fabrication.
Study on Mechanical Properties of Polyester with Addition of Recycle Gift or Members Card
Authors: Dam Aimimi Mat , Kamdi Zakiah
Published: November 2021

Increasing usage of gift cards will end up increasing the waste. Instead of throwing in the dustbin, re-cycling the cards may help in increasing the product usage and contribute to the environment sustainability. In this study, the re-cycle gift cards were combined with polyester to produce polymer blend. The composition of re-cycle gift cards was 2, 4 and 6 wt%. The gift card was crush and mix with the polyester and hardener followed by casting to get the suitable shape based on the testing. Three testing was undergone to evaluate the polymer blend properties which are tensile test, Charpy’s impact test and Durometer hardness test. Similar trend was shown for all mechanical testing which showing an increase of performance from 2 to 4 wt% addition of recycle cards but reduce when achieved 6 wt%.
Contact Force Measurement Approach for Measuring Glove-Skin Interfacial Pressure
Authors: Chen C. X. , Nasir S. H. , Sadun A. S. , Mustafa El Bakri H.
Published: November 2021

Pressure garments for medical had been widely used to enhance the recovery after an operation, for treatment of arthritis, deep vein thrombosis, leg ulcers, varicose veins or hypertrophic scars. This research aims to develop a contact force measuring approach to measure glove-skin interfacial pressure. With the aid of a force measuring sensors system, it is easier to study the efficiency of pressure garments. Besides, occupational therapists can also design a user-friendly pressure garment that is comfortable and easy to donning and doffing, especially for children. Two types of flexible force sensors were used to measure the glove-skin interfacial pressure using two types of pressure therapy gloves. Pressure therapy glove is selected to represent pressure garments. The measuring sensors were placed at three different locations on the dorsal side of the hand, and the glove-skin interfacial pressure was measured in two different postures, which is full fist and tabletop posture. It was found that different postures had led to different interfacial pressure. The glove-skin interfacial pressure was found to be greater during full fist posture compared to tabletop posture. This show that the applied glove-skin interfacial pressure is affected by postures and movement.
Effect of graphene nanoplatelet addition on the electrical conductivity of poly(hydroxybutyrate-co-hydroxyvalerate) biocomposites
Authors: Mahamud Syarifah Nuraqmar Syed , Ganesan Ovinesh , Pisal Mohd Hanif Mohd , Rabat Nurul Ekmi
Published: November 2021

Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) is one of the most promising biodegradable polymers used in many applications due to its biodegradability and non-toxicity. However, the usage of PHBV in electronic, biomedical, and biosensor applications has been limited due to its poor electrical properties. This study shows a simple method of producing and enhancing the electrical conductivity of PHBV-based biocomposites by adding graphene nanoplatelet (GNP) as a conductive filler. The biocomposite films were prepared using the solvent casting method, consist of five GNP loading (0-5 wt. %). The prepared PHBV/GNP biocomposites show enhanced electrical conductivity compared to neat PHBV. PHBV/GNP biocomposite with 5 wt. % filler loading exhibits the highest electrical conductivity at 3.83 × 10−3 S/cm. Higher crystalline regions in the PHBV/GNP biocomposites have facilitated the transfer of electrons between PHBV, resulting in the formation of conductive biocomposites, as evident from X-ray diffraction (XRD) characterization.
The Study of Recycled Ethylene Propylene Diene Monomer (EPDM-r)/Polypropylene (PP) Polymeric Blends
Authors: Zulkifli MH , Rasidi MSM , Rahim NAM , Musa L , Masa Abdul Hakim
Published: November 2021

In this study, recycled ethylene propylene diene monomer (EPDM-r) were blended with polypropylene (PP) by compounding via heated two roll mills with the various ratio of EPDM-r. Certain blends were included with PP-g-MA as a compatibilizer. In tensile tests, the increasing of EPDM-r content in blends resulted in the reduction of tensile strength and Young’s Modulus but increased elongation at break. Furthermore, the presence of compatibilizer in blends enhanced the tensile properties. It was found all the samples with compatibilizer performs better results in tensile strength, Young’s Modulus, and elongation at break than samples without compatibilizer. On the other hand, the aging affected were studied on compatibilized and uncompatibilized blends. It was found that aging affects the samples by decreasing the tensile strength, Young’s Modulus, and elongation at break. The crosslink density had been found higher in the blends with high EPDM-r content as the EPDM-r had the ability to swell. The morphological study related to the structure with the tensile properties. It was confirmed that the presence of a compatibilizer increased the compatibility between EPDM-r and PP matrix.
Effect of Carbon Nanotube Loading on Electrical Properties of Electrospun Polyvinylidene Fluoride (PVDF) Fiber
Authors: Lee Jia Wei , Sharifah Shahnaz S.B , Nur Hidayah A.Z , Yahud S. , Samat Noorasikin
Published: November 2021

Polyvinylidene fluoride (PVDF) is a high purity thermoplastic fluropolymer that use in the aircraft, electronics, and chemical industry. Carbon nanotube (CNTs) is made up of rolled up of graphite sheets, exhibits excellent chemical, thermal, mechanical properties, and large surface areas. PVDF fibers blended with CNTs were able to enhance the β-phase which contributes to piezoelectric properties. Electrospinning is the simplest and low-cost method to produce PVDF/CNT fibers by dissolving PVDF in solvent N, N-Dimethylformamide (DMF). 15wt% PVDF solution was used. CNT loading were varied at 0.0wt%, 0.35wt%, 0.80wt% and 1.00wt% with parameters of 20kV, tip-to-collector distance (TCD) 15cm and flow rate 1.0mLh-1. Scanning Electron Microscope (SEM), four-point probe and X-ray Diffraction (XRD) were used to determine the morphology and crystallinity of electrospun PVDF/CNT fibers. The SEM analysis concluded all fibers showed beaded structure due to low concentration of PVDF solution with insufficient ultrasonification and stirring, cause electrospraying and agglomeration. XRD and four-point probe analysis concluded PVDF/0.35wt%CNT showed the highest β-phase content with intense XRD peak and highest electrical conductivity. However, shift peak is observed among all fibres due to short electrospinning time leads to insufficient thickness of electrospun mat, which affects the mechanical properties of fibres and causes peak shift.
Citric acid leaching process for removal of iron (Fe) from rice husk
Authors: Pa Faizul Che , Chik Abdullah , Abdullah Hasan Zuhudi
Published: November 2021

Rice husk containing the highest amount composition of silica (SiO2) compared with other agricultural waste. With such a large availability of rice husk, it becomes economical to industrial by the implementation concept of sustainability beside decompose the rice rusk into ash. The extraction of silica and elimination of metallic element, such as iron (Fe) from rice husk (RH) was treated by leaching process. With this, the RH can be utilized to produce various types of useful renewable resources such as silica (SiO2). Using the organic acid as leaching solution is more eco-friendly instead using the inorganic acid that classified as very dangerous chemical due to the high level of hazard. The treated and untreated rice husk ash characterizes using scanning electron microscopy and X-ray diffraction spectroscopy. The morphology of treated rice husk shows the tubular aggregate due to the presence of alkaline earth metal such as Ca and Mg. Under the optimum condition with 90 °C solution temperature, 60 minutes stirring time, 3% of citric acid and calcination temperature of 800 °C for 3 hours, amorphous silica with more than 78% was prepared via citric acid leaching treatment and combustion process.
Effect of Liquid Feeding Rate on Carbonation of Precipitated Calcium Carbonate via Continuous Method
Authors: Salleh Emee Marina , Othman Rohaya , Mahim Zawawi , Sabri Siti Noorzidah
Published: November 2021

Precipitated calcium carbonate (PCC) is an innovative product generated from lime that significantly offers various functional characteristics in fulfilling numerous market demand. PCC is produced by hydrating high-calcium quicklime resulting slurry so-called milk-of-lime and reacting the slurry with carbon dioxide (CO2) via carbonation process. The resulting PCC product is extremely white and typically has a uniform narrow particle size distribution. PCC is available in various crystal morphologies and sizes, which can be tailored to optimize performance in a specific application. The final properties of the PCC can be diversified by controlling processing parameters. In this current work, effect of liquid air pressure corresponding to feeding rate on a formation of PCC was investigated. In enhancing the product yield, the quicklime was initially converted into a solution containing calcium ion (Ca2+) using natural promoter agent. Subsequently, CO2 gas was continuously supplied into the Ca-rich ionic solution, thus inducing carbonation reaction to form PCC. This present work showed the carbonation time of producing PCC was effectively reduced as a function of feeding rate from 15 minutes at 10 psi to only 7 minutes at 50 psi. The PCC yield slightly increased from 19 g to 23 g with increasing the feeding rate from 10 psi to 50 psi, respectively. Morphologically, the PCC particles were dominated by rhombohedral structures at various feeding rates with an indication of intergrowth mechanism. This current finding signified the increasing feeding rate offered a significant reduction of PCC production time that might be efficiently applied by the industrial manufacturers.
Effect of varying phosphate content on the structure and properties of sol-gel derived SiO2-CaO-P2O5 bio-glass
Authors: Syed Adam Syed Nuzul Fadzli , Zainuddin Firuz , Osman Azlin Fazlina
Published: November 2021

In this work, biocompatible glass (bioglass) particles were prepared by low temperature, acid catalysed sol-gel method. The effect of varying phosphate (P2O5) content (10, 15 and 20 mol %) in the sol-gel derived glass composition were studied. The sol-gel derived bioglass particles were compacted into cylindrical pellets via hydraulic press machine and sintered at 600°C for 3 hours. The bioglass particulates were analysed by x-ray fluorescence (XRF), Fourier Transformed Infrared (FTIR), X-Ray Diffraction (XRD) and nitrogen gas adsorption. Meanwhile, the sintered bioglass pellets were analysed by FTIR, XRD and FESEM-EDX. Furthermore, in vitro bioactivity analysis was performed by immersion in simulated body fluid (SBF) for 14 days. Bioglass particulates with high glassy phase, high surface area and high porosities were obtained for all compositions. Increasing of phosphate content to 20 mol% particularly reduced the porous characteristics of the bioglass particulates. Furthermore, leads to higher bridging oxygen (BO) atoms, higher amorphous silicate networks, lower glass crystallinity and higher number of phosphate crystallites within the amorphous glassy matrix. Increased to 20 mol% of phosphate also reduced the ability of the bioglass surface to induce carbonated apatite formation when immersed in simulated body fluid (SBF) solution.
Ultrasound-Assisted Surface Modifications on Ceramic Reinforcement for Lead-Free Composite Solders : Short Review
Authors: Leong Wai Keong , Mohamad Ahmad Azmin , Nazeri Muhammad Firdaus
Published: November 2021

The purpose of this paper is to review and examine the effect of ultrasound-assisted surface modifications of ceramic reinforcements on the properties of lead-free solders. The discussion will highlight the fundamental understanding, main parameters, configurations, and recent surface-modified ceramic reinforced composite lead-free solder developments. The review also identified and summarized the advantages, current trends, and significant findings in this field. The ultrasound-assisted surface modification was found to provide a crucial improvement on the wettability properties of molten solders as the matrix phase on the ceramic reinforcement. Further, the excellent distribution of ceramic reinforcement in solder matrix was also seen after the surface modification process. This has led to significant improvements in mechanical properties such as hardness and strength. The pinning of dislocation movement was seen as the reason for improving the mechanical properties. This positive impact in enhancing the ceramic reinforcement-solder interfacial reaction allows more explicit future research directions and opportunities for composite solder applications.
The Effectivity of Oil Palm Inhibitor Processed by Aminolysis to Control Corrosion on Steel in Sodium Chloride Environment
Authors: Hastuty Sri , Prasetyo Himawan Agus , Kirana Norma Nindya , Nugroho Agung , Oktaviano Haryo Satriya , Awwaluddin Muhammad
Published: November 2021

A green inhibitor based on Palm kernel oil (PKO) was prepared to investigate its corrosion inhibition behaviour against steel ASTM A36 in sodium chloride solution. The aminolysis method was used to synthesize the green inhibitor and produced fatty acid diethanolamine. Afterwards, the mixture of PKO and diethanolamine of 1:6 and 1:20 were prepared. These mixtures were added into sodium chloride solution with concentration 50, 100, 500, and 1,000 ppm and they were used as working solution in corrosion testing. Corrosion testing was conducted using anodic polarization. The confirmation of microstructure of steels surfaces were done by optical microscope. The results obtained from corrosion testing showed that inhibitors of palm oil, especially palm kernel oil (PKO), provided a good corrosion protection effect. The present work provided very promising results in the preparation of green corrosion inhibitors.
The use of ground & ultrasonicated dolomite (GUD) for improving the tensile performance of Poly (ethylene-co-vinyl acetate) copolymer composite
Authors: Fauzi Asfa Amalia Ahmad , Osman Azlin Fazlina , Halim Khairul Anwar Abdul , Mustafa Zaleha , Alakrach Abdulkader M. , Salleh Mohd Nazry
Published: November 2021

The combination of the organic and inorganic materials to fabricate a new form of material called ‘composite’ has been performed since several decades ago. However, the strategy to improve the homogeneity of the resultant composite system is still being the main focus of current research. In this study, dolomite and poly (ethylene-co-vinyl acetate) (PEVAc) were employed as filler and matrix, respectively. Dolomite was ground and ultrasonicated before being used as filler. It can be observed that the size of dolomite particles has been reduced significantly upon the grinding and ultrasonication processes. The effect of ground and ultrasonicated dolomite (GUD) addition on the mechanical performance of the PEVAc copolymer was investigated. Results indicate that the GUD filler has successfully increased the tensile strength, elongation at break, modulus of elasticity and tensile toughness of the PEVAc copolymer when being employed in 1 wt%. However, the use of higher content of GUD resulted in the decreasing trend of those properties. This shows that the ground and ultrasonicated dolomite with smaller and higher surface area particles than its pristine form could bring improvement to the mechanical performance of the copolymer when being used in low loading as it can be more easily dispersed in the copolymer matrix.
Accuracy and Bias of the Rasch Rating Scale Person Estimates using Maximum Likelihood Approach: A Comparative Study of Various Sample Sizes
Authors: Azizan Nurul Hafizah , Mahmud Zamalia , Rambli Adzhar
Published: November 2021

The focus of this article is to evaluate the maximum likelihood estimation (MLE) performance in estimating the person parameters in the Rasch rating scale model (RRSM). For that purpose, 1000 iterations of the Markov Chain Monte Carlo (MCMC) simulation technique were performed based on a different number of sample sizes and several number of items. The performance of MLE in estimating the person parameters according to the different number of sample sizes was compared through accuracy and bias measures. Root mean square error (RMSE) and mean absolute error (MAE) were used to examine the accuracy of the estimates, while bias in estimation was assessed through the mean difference of estimates and true values of the person parameters. The simulated survey data sets in this study were generated according to the RRSM under the assumption of normality was satisfied. Results from the simulation analysis showed that in comparison to the larger sample sizes, smaller sample sizes tend to produce higher RMSE and MAE. In addition, the maximum likelihood estimates of the person parameters in smaller sample sizes also recorded a higher value of the mean difference of the person estimates and its true values compared to larger sample sizes. Findings from this study imply that the use of the MLE approach in small sample sizes results in less accurate and highly biased person estimates across the number of items.
The Effect of Chemical Parameters on Water Quality Index in Machine Learning Studies: A Meta-Analysis
Authors: Malek Nur Hanisah Abdul , Yaacob Wan Fairos Wan , Nasir Syerina Azlin Md , Shaadan Norshahida
Published: November 2021

According to the World Health Organization (WHO), approximately 2 billion people worldwide use drinking water sources that are contaminated with faeces. This is a serious issue since contaminated water may lead to certain waterborne diseases such as cholera, hepatitis A, dysentery, jaundice, and typhoid fever. Therefore, many researchers around the world are interested in studying the water quality. One of the most commonly used approaches is by using machine learning. Machine learning approach has grabbed the interest of many researchers since the last several years due to its power to compute complicated mathematical computations on big data analysis. Therefore, this study explored the correlation between different water quality parameters and Water Quality Index (WQI) in water quality studies that used machine learning by using a meta-analysis approach. This study used estimated variance, heterogeneity index, Chi-squared heterogeneity test and the random effects model. Based on the selected articles, pH, dissolved oxygen (DO) and biochemical oxygen demand (BOD) are the parameters commonly used in water quality studies which use a machine learning approach. This study found that pH is the best chemical factor which greatly affects the Water Quality Index since it has the highest mean correlation and lowest estimated variance due to sampling error. The result showed that the correlation between pH and WQI are heterogeneous across studies based on the Chi-squared of heterogeneity, Q and heterogeneity index, I2
value. The 95% confidence interval of effect summary supports the findings that the correlation of pH is different among the studies. This study also found that there is no evidence of publication bias using Egger and Begg’s test. Therefore, in order to ensure good water quality supply, the local authorities and government agencies should give more attention to this parameter since pH of water plays an important role in determining the water quality status.
Identification of Inhomogeneous Temperature on Stainless Steel using Statistical Analysis
Authors: Afrianti Yuli Sri , Ardy Husaini , Pasaribu Udjianna Sekteria , Latief Fourier Dzar Eljabbar
Published: November 2021

Corrosion in stainless steel, abbreviated as SS, is still an exciting topic to study. Even though SS is a corrosion resistance material, this property will be degraded when exposed to high temperatures for a long time because of σ phase, such as a Fe-Cr compound, formation. The presence of this phase can be observed using a special chemical etchant solution that will give five specific colours to this phase: light brown, dark brown, bluish brown, light blue, and dark blue. In this study, the specimen sample is from ASTM A297. Furthermore, the metallography process is carried out to obtain microstructure images that describe the σ phase. Here, two grains were taken as objects to discretize with one of them was around the specimen sample center and the other was close to the boundary with the environment. The discretization resulted in a 2 x 5 frequency table, called contingency table, that is analysed by the independence χ2-test. The contingency table is also represented geometrically in cartesian. The study shows that two grains were not independent. The grain which was around the specimen sample center contained many σ phases dominated by light blue colour (43%). In other words, the prolonged heating did not give homogeneous corrosion level.
Global Warming in Cameron Highlands: Forecasting its Temperature Level via ARIMA vs ARAR
Authors: Zamri Nurzawanah Raihah , Azmi Nurul Nisa’ Khairol
Published: November 2021

The average global temperature has increased at a rapid rate over the past 50 years leading to global warming. The impact of climate change can be felt across the continents. In this research, analysis was conducted to model and forecast the monthly temperature of Cameron Highlands in 2020 and 2021, against its historical monthly average temperature from January 1990 until December 2019. Two (2) methods namely (i) Seasonal Autoregressive Integrated Moving Average (SARIMA) model and (ii) Autoregressive Autoregressive (ARAR) algorithm were compared to determine the best model to forecast the monthly temperature of Cameron Highlands. SARIMA (1,1,2)(1,1,1)12 was found to be the best at forecasting the monthly temperature in Cameron Highlands as RMSE and MAPE values were lower than ARAR. In year 2021, the temperature in Cameron Highlands is estimated to increase by 1.6 °C. The result of the forecast showed that its monthly temperature was expected to increase in the next two (2) years. Hence, this calls for serious action to be taken by higher authorities.
Machine Learning Models for COVID-19 Confirmed Cases Prediction: A Meta-Analysis Approach
Authors: Yaacob Wan Fairos Wan , Sobri Norafefah Mohamad , Nasir Syerina Azlin Md , Nordin Noor Ilanie , Yaacob Wan Faizah Wan , Mukhaiyar Utriweni
Published: November 2021

COVID-19, CoronaVirus Disease – 2019, belongs to the genus of Coronaviridae. COVID-19 is no longer pandemic but rather endemic with the number of deaths around the world of more than 3,166,516 cases. This reality has placed a massive burden on limited healthcare systems. Thus, many researchers try to develop a prediction model to further understand this phenomenon. One of the recent methods used is machine learning models that learn from the historical data and make predictions about the events. These data mining techniques have been used to predict the number of confirmed cases of COVID-19. This paper investigated the variability of the effect size on the correlation performance of machine learning models in predicting confirmed cases of COVID-19 using meta-analysis. It explored the correlation between actual and predicted COVID-19 cases from different Neural Network machine learning models by means of estimated variance, chi-square heterogeneity (Q), heterogeneity index (I2) and random effect model. The results gave a good summary effect of 95% confidence interval. Based on chi-square heterogeneity (Q) and heterogeneity index (I2), it was found that the correlations were heterogeneous among the studies. The 95% confidence interval of effect summary also supported the difference in correlation between actual and predicted number of confirmed COVID-19 cases among the studies. There was no evidence of publication bias based on funnel plot and Egger and Begg’s test. Hence, findings from this study provide evidence of good prediction performance from the Neural Network model based on a combination of studies that can later serve in the prediction of COVID-19 confirmed cases.
Ethnomathematics values in Temple of Heaven: An Imperial Sacrificial Altar in Beijing, China
Authors: Zhang Cheng , Wijaya Tommy Tanu , Zhou Ying , Chen Jihe , Ning Yimin
Published: November 2021

Many studies are proving that learning mathematics with an ethnomathematical approach can improve students’ mathematical skills. Developing and using ethnomathematics concepts are important to raise history and cultural awareness of mathematics. This study aims to analyse the ethnomathematics values of the Temple of Heaven. Temple of Heaven is one of the famous heritage sites in Beijing, China, which bears many ethnomathematics concepts. The researchers applied a qualitative method in this study. The subject of this research is the Temple of Heaven building that is located in Beijing, China. Researchers identified the geometrical concept present in the exterior, interior design, and building structure of the Temple of Heaven building. This research shows the existence of mathematical concepts in the architecture of the Temple of Heaven. This research result can help teachers in making mathematical practice questions with ethnomathematics concepts.