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Recent development of natural fibre for nanocellulose extraction and application
No full textNatural fibers garnered fame amongst researchers and scientists due to their potential as an alternative material in countless sectors, including automotive, packaging, construction, and medicine. This work began with the classification of natural fibers and an overview of their chemical compositions. Then, the retting process, which is a process separating the fiber from the woody core, was discussed. The latest technology has attracted researchers’ attention in the alteration of natural fibers to form nanostructures. Hence, this paper will also discuss the extraction method for nanocellulose. Following that, the methods for the preparation of these cellulose nanofibers, which are nanocrystalline cellulose (CNC), nano-fibrillated cellulose (CNF), and bacterial nanocellulose (BNC), are summarized. Finally, the application of this nanomaterial in advanced applications was explored, and a way forward of this nanocellulose technology was also scrutinized
The characteristics, swelling ratio and water content percentage of chitosan-gelatin/limestone-based carbonate hydroxyapatite composite scaffold
No full textThe tissue engineering field has developed a scaffold that can be used to increase the bone regeneration process. Carbonate hydroxyapatite (CHA) is a well-known scaffold due to its human bones resembling components. The scaffold was synthesized from K, G, and limestone-based CHA using a freeze-drying method with K-G/CHA ratios (w/w) of 40:60, 30:70, 20:80, and 10:90. A Fourier transform infrared spectroscopy (FTIR), a scanning electron microscope-energy dispersive X-ray (SEM-EDX), and X-ray diffraction (XRD) were used to characterize the scaffold. The FTIR test showed some functional groups, such as hydroxyl, amide I, amide II, carbonate, and phosphate. The SEM-EDX test showed micropore ([removed]50 um) structures as well as elements of C, N, O, Mg, Al, Si, P, and Ca. The XRD analysis obtained crystalline and amorphous particles. The water content percentage (WCP) values obtained were 61.29%, 64.30%, 67.71%, and 67.78%. The K-G/CHA composite scaffold with a ratio of 30:70 has ideal characteristics, a swelling ratio, and a water content percentage
The impact of tourism on entrepreneurship in developing countries
No full textAs an important factor of production, economist traditionally considers entrepreneurship as a key factor for encouraging economic growth, especially in developing countries. With tourism is one of the fastest growing economic sectors and closely linked to development of most developing countries, this study aims to examine the effect of tourism on entrepreneurship by using panel data of 56 developing countries for the period between 2010 and 2017. Using a panel data technique, namely the generalized method of moments (GMM) estimator, the results suggest that tourism play an important role in improving the level of entrepreneurship in developing countries, which are robust across different specification. Therefore, governments should aim to further develop the tourism industry to support a more sustainable entrepreneurship development in developing countries
Enduring performance of alkali-activated mortars with metakaolin as granulated blast furnace slag replacement
Get PDFIn the construction industries worldwide, improving the materials durability and achieving sustainability are the main goal. Owing to their excellent strength performance various alkali-activated binders can be one of the alternative solutions to the polluting traditional cement. Currently, ground blast furnace slag (GBFS) is the major base material used in the alkali-activated binders. High drying shrinkage and low resistance to sulfuric acid attack affect negatively the durability performance and life span of alkali-activated paste, mortars, and concretes made from GBFS. Thus, a series of alkali-activated mortars (AAMs) were designed with various contents (5, 10, 15, 20 and 25, mass%) of metakaolin (MK) as GBFS replacement to improve their strength performance. In addition, the strength and durability performance of the designed mixes were compared with the control mixture prepared using 100% of GBFS. The impact of varying MK level on the long-term performance such as compressive strength, porosity, resistance to sulfuric acid attacks, wet-dry cycles, drying shrinkage, and carbonation were evaluated. Various recommended standards were followed to cast the specimens in different shapes (cubes, cylinders, and prisms) and sizes. Mortar containing 10% of MK as GBFS replacement showed the highest compressive strength (63.4 MPa) at 28 days of curing age. Furthermore, the inclusion of MK as GBFS replacement was shown to improve the AAMs durability performance wherein the drying shrinkage was reduced and the resistance to aggressive environments was increased. The specimens containing 5% and 10% of MK revealed a lower porosity and carbonation depth compared to the control specimen. It was concluded that the proposed AAMs due to their long-term stability can be the sustainable and potential substitutes to the traditional construction materials
Structural and thermal characteristics of Ti6Al4V (Ti64) metal powders for direct energy deposition
No full textTi6Al4V metal powder has been widely utilized in direct energy deposition (DED) of additive manufacturing (AM) technology, especially in aerospace applications. However, to secure excellent weldability between metal powder and substrate requires a proper understanding of heat-dissipation energy/created, especially when involving two components/materials with different thermal coefficients or properties. Therefore, an attempt is made in this work to investigate the structural and thermal characteristics of powder metals, including precursor powders such as Ti, Al, V, Al-V, and commercial established powder of Ti6Al4V (Ti64), respectively. Qualitative and quantitative analyses were employed accordingly to determine phase composition via X-ray diffraction (XRD) analyses. While phase stability, such as the thermal reaction and transition (ΔH) of these powders, was evaluated using differential scanning calorimetry (DSC). These findings are essential, especially in determining the reaction mechanism involved in various applications such as deposition process, mechanical alloying, and reaction sintering under a controlled environment. These fundamental characteristics are essential in producing high purity Ti64 metal powders and improve the weldability of the metal joining
Hydrogen and value-added liquid fuel generation from pyrolysis-catalytic steam reforming conditions of microplastics waste dissolved in phenol over bifunctional Ni-Pt supported on Ti-Al nanocatalysts
Get PDFThis research looks at the potential of utilizing microplastics waste (MPW) found in oceans and soil as a source of liquid fuel. A significant portion of this pollutant is presently untreated and ends up in landfills, exacerbating the worldwide issue of marine and land pollution. Pyrolysis is a tertiary recycling process that is presented as a solution in the presence of a catalyst. This study aimed to develop bifunctional Ni-Pt nanocatalysts supported on TiO2 and Al2O3 for hydrogen and valued fuels generation from pyrolysis-catalytic steam reforming conditions of microplastics waste dissolved in phenol. The chemical and physical properties of nanocatalysts were characterized by BET, XRD, TEM, FESEM, FTIR, H2-TPR, CO2-TPD, NH3-TPD, TGA, ICP and CHNS. It was found that the introduction of a small portion of Pt (2 wt%) metal to the Ni/Ti-Al nanocatalyst was found to significantly enhance the reducibility, acidity, basicity nanocatalyst performance and stability. C–O(H), C[dbnd]C–C, and C–O were the major functional clusters of the liquid yields surveyed from the FTIR spectrums during pyrolysis. A valuable liquid product such as trimethyl-(2-trimethylsilylphenyl)silane, cyclohexane-1,3-dione, 2-allylaminomethylene-5,5-dimethyl-, bis(2-ethylhexyl)phthalate (BEHP), etc. compounds were produced from the pyrolysis-catalytic steam reforming reaction. This sight is a crucial indication of utilizing microplastics pollution for value-added fuel production and decreasing the risk threats of marine life
The pattern of epistemological belief in design among engineering students
Get PDFThis study was geared toward identifying the pattern of epistemological belief in design among engineering students enrolled in one of the research universities in Malaysia. To this end, data collection was carried out by employing an adapted instrument of a Likert-type questionnaire with five scales consisting of 68 items. Then, 120 engineering students from several engineering disciplines, such as electrical engineering, mechanical engineering, and civil engineering, were selected from the overall population of Universiti Teknologi Malaysia to determine their epistemological beliefs on design. According to the literature, six dimensions of beliefs were commonly perceived. The students were to describe their beliefs about design knowledge and the nature of knowing and learning design, including the source of knowledge, the certainty of knowledge, structure of knowledge, speed of knowledge acquisition, innate ability of personal and general knowledge, and real-world applicability of knowledge. The study's findings revealed that the epistemological beliefs of engineering students in each dimension yielded a difference across varying engineering majors
A review on production and surface modifications of biochar materials via biomass pyrolysis process for supercapacitor applications
No full textBiochar (BC) based materials are solid carbon enriched materials produced via different thermochemical techniques such as pyrolysis. However, the non-modified/non-activated BC-based materials obtained from the low-temperature pyrolysis of biomass cannot perform well in energy storage applications due to the mismatched physicochemical and electrical properties such as low surface area, poor pore features, and low density and conductivity. Therefore, to improve the surface features and structure of the BC and surface functionalities, surface modifications and activations are introduced to improve its properties to achieve enhanced electrochemical performance. The surface modifications use various activation methods to modify the surface properties of BC to achieve enhanced performance for supercapacitors in energy storage applications. This article provides a detailed review of surface modification methods and the application of modified BC to be used for the synthesis of electrodes for supercapacitors. The effect of those activation methods on physicochemical and electrical properties is critically presented. Finally, the research gap and future prospects are also elucidated
Hyperelastic properties of bamboo cellulosic fibre-reinforced silicone rubber biocomposites via compression test
No full textMaterials that exhibit highly nonlinear behaviour are intricate to study. This is due to their physical properties, as they possess a very large deformation. Silicone rubber is among the materials that can be classified as possessing such characteristics, despite their being soft and frequently applied in medical applications. Due to their low mechanical properties, however, it is believed that a filler addition could enhance them. This study, therefore, aims to investigate the effect of the addition of bamboo cellulosic filler to silicone rubber in terms of its compressive properties in order to quantify its material constants using the hyperelastic theory, specifically the Neo-Hookean and Mooney–Rivlin models. The specimens’ compressive properties were also compared between specimens immersed in seawater and those not immersed in seawater. The findings showed that the compressive properties, stiffness, and compressive strength of the bamboo cellulosic fibre reinforced the silicone rubber biocomposites, improved with higher bamboo filler addition. Specimens immersed in seawater showed that they can withstand a compressive load of up to 83.16 kPa in comparison to specimens not immersed in seawater (up to 79.8 kPa). Using the hyperelastic constitutive models, the Mooney–Rivlin model displayed the most accurate performance curve fit with the experimental compression data with an R2 of up to 0.9999. The material constant values also revealed that the specimens immersed in seawater improved in stiffness property, as the C1 material constant values are higher than for the specimens not immersed in seawater. From these findings, this study has shown that bamboo cellulosic filler added into silicone rubber enhances the material’s compressive properties and that the rubber further improves with immersion in seawater. Thus, these findings contribute significantly towards knowledge of bamboo cellulosic fibre–reinforced silicone rubber biocomposite materials
An overview into polyethylene terephthalate (PET) hydrolases and efforts in tailoring enzymes for improved plastic degradation
Get PDFPlastic or microplastic pollution is a global threat affecting ecosystems, with the current generation reaching as much as 400 metric tons per/year. Soil ecosystems comprising agricultural lands act as microplastics sinks, though the impact could be unexpectedly more far-reaching. This is troubling as most plastic forms, such as polyethylene terephthalate (PET), formed from polymerized terephthalic acid (TPA) and ethylene glycol (EG) monomers, are non-biodegradable environmental pollutants. The current approach to use mechanical, thermal, and chemical-based treatments to reduce PET waste remains cost-prohibitive and could potentially produce toxic secondary pollutants. Thus, better remediation methods must be developed to deal with plastic pollutants in marine and terrestrial environments. Enzymatic treatments could be a plausible avenue to overcome plastic pollutants, given the near-ambient conditions under which enzymes function without the need for chemicals. The discovery of several PET hydrolases, along with further modification of the enzymes, has considerably aided efforts to improve their ability to degrade the ester bond of PET. Hence, this review emphasizes PET-degrading microbial hydrolases and their contribution to alleviating environmental microplastics. Information on the molecular and degradation mechanisms of PET is also highlighted in this review, which might be useful in the future rational engineering of PET-hydrolyzing enzymes