Key Engineering Materials Vol. 818

Abstract: Special Region of Yogyakarta is one of the regions that has high potential for natural disasters. Food is the most consumable material which is needed when natural disasters occur. An alternative form of food preservative is needed to maintain nutritious foods that will be distributed to the victims of natural disasters. The foods must still appropriate to eat. In this research, watermelon rind was chosen as an ingredient to make natural preservatives because they contain flavonoids and anthocyanins. This research aims were to determine the total content of anthocyanins, flavonoids and phenolics in the red watermelon rind and yellow watermelon rind, also to determine the effect of chitosan composition to the ability of flavonoids and phenolics release in the food. This research was carried out by extraction and encapsulation methods. The analysis included the content of Total Anthocyanin (TA), Total Flavonoids (TF) and Total Phenolic (TPC) in the supernatant. The other analysis was in vitro tests that was done to know the ability of flavonoids and phenolics release in the food. The total anthocyanin content in the red watermelon rind was 0.0334 mg L^-1 while in the yellow watermelon rind was 0.0668 mg L^-1. The total content of flavonoids in the red watermelon rind was 0.7369 g mL^-1, while in the yellow watermelon rind was 0.3296 g mL^-1. The total phenolic content of red watermelon rind was 0.3669 g mL^-1, while in the yellow watermelon rind was 0.2273 g mL^-1. In both of red and yellow watermelon rind, the highest release of flavonoid and phenolic levels showed in the variations of chitosan mass 0.4 grams. The highest flavonoid content released was 0.0638 g mL^-1 in red watermelon rind and 0.0702 g mL^-1 in yellow watermelon rind. The highest phenolic content released was 0.0321 g mL^-1 in red watermelon rind and 0.0408 g mL^-1 in yellow watermelon rind.

Abstract: In this study membranes synthesized using cellulose acetate through chemical crosslinking process with polyethylene glycol (PEG) and dimethylformamide (DMF) acts as crosslinker agent. Cellulose is derived from corn husk, which known as agricultural waste that has potential sources of cellulosic fibers in producing cellulose acetate. The prepared membranes of corn husk cellulose were characterized by Fourier transform infrared and X-ray diffraction. The effect of various additives and additives concentration were investigated to obtain swelling degree and tensile strength of membranes. Result showed that highest swelling degree of 236% was achieved in the condition of DMF/S 10% w/w. This condition produce cellulose acetate membrane with thickness of 0.074 mm, tensile strength of 27.5kg/cm² and elongation of 3.5%.

Abstract: In the industry, stubborn emulsion still constitutes up to 20% of the total emulsion volume. The existing remediation strategies for emulsion treatment rely heavily on the study of heavy crude oil emulsion. However, minimal information is available on integrating interfacial rheology with emulsion stability on waxy crude oil emulsion. The proposed research provides a study to the development of integration between interfacial rheology and emulsion stability so that it can be a quick assessment but an accurate method to measure emulsion stability. The primary objectives of the research are to provide an extensional study to the design development of a comprehensive interfacial rheology protocol for the assessment of emulsion stability by developing a method of testing and monitoring the interfacial rheology and to investigate the demulsification ability of the waxy crude oil emulsion subjected to microbial treatment. The novelty of this study is to use the newly developed measurement protocol via interfacial rheology to predict emulsion stability. Application of the microbes on waxy crude oil to breakdown the water-in-oil emulsion using a rheometer will also be explored. The treatment is targeted to disintegrate the interfacial layer within the emulsion leading to better oil recovery. Rheological properties of the emulsion will be monitored upon the microbial injection to analyze the effects of the treatment on the rheology of emulsion. The outcomes from this research is that the newly developed protocol will predict emulsion stability that could resolve the stubborn emulsion issues via the developed interfacial rheology protocol, which could be time-saving and increases the production efficiency. This research paper is a study to develop a correlation on surface tension and interfacial tension between crude oil, water and a readily-mixed emulsion.

Abstract: Laser based powder bed fusion (LBPF) or selective laser melting (SLM) is making a leap march towards fabricating novel materials with improved functionalities. An attempt has been made here to fabricate hard quasicrystalline composites via SLM, which demonstrates that the process parameters can be used to vary the phases in the composites. The mechanical properties of the composite depend on their constituents and hence can be varied by varying the process parameters. The results show that SLM not only produces parts with improved functionalities and complex shape but also leads to defined phases and tunable properties.

Abstract: Removing lead ion in aqueous solution using petai (Parkia speciosa) residue was done well. Petai residue is modified with sodium hydroxide and sulfuric acid before batch adsorption process occured. The results showed that the highest adsorption capacity was found in acid modification that was 2.62 mg/g.Temkin and Dubininmodels fit the adsorption isotherms of all adsorbents.

Abstract: In this work, a novel type of δ-TRIP steel was designed, and the content and stability of retained austenite in δ-TRIP specimens under different annealing processes were detected and studied, respectively. The volume fraction of austenite was determined by X-ray diffraction (XRD). The microstructure and mechanical properties were analyzed systematically. The results show that a complex microstructure composed of three phases (ferrite, bainite and retained austenite) was obtained in the δ-TRIP steel. With the increasing of annealing temperature, both retained austenite and bainite content in the specimen increased, while the carbon content in retained austenite decreased, leading to a poor stability for retained austenite. Both tensile and yield strength improved with the increasing of annealing temperature, while the elongation reduced. The feature of retained austenite led to an excellent combination of ductility and strength, which was better than traditional TRIP steel.

Abstract: In the present work hard turning of AISI 52100 steel has been performed using Polycrystalline cubic boron nitride (PCBN) tools. The input parameters considered are cutting speed, feed, depth of cut, nose radius and negative rake angle and the measured responses are machining force and workpiece surface temperature. Experiments are planned as per Central Composite Design (CCD) of Response Surface Methodology (RSM). The effect of input parameters and their interactions are discussed with main effects plot. Further, the multi-objective optimization scheme is proposed by adopting Grey Relational Analysis (GRA) coupled with Principle Component Analysis (PCA). Results demonstrated that speed is the most significant factor affecting the responses followed by negative rake angle, feed, depth of cut, and nose radius. The optimum cutting parameters obtained are cutting speed 1000 rpm, feed 0.02 mm/rev, depth of cut 0.5 mm, Nose radius 1 mm and Negative rake angle 5^o.

Abstract: The constraint of frame column has a significant effect on its dynamic response under blast loading. To study the influence factors of column end constraint, the effect of adjacent members and distributed mass of floors is studied using numerical analysis. The results show that the members that are directly connected to the column end are the main contributors to its end constraint. And these adjacent members may be simplified as being fixed at the far ends. It has also been found that the displacement at the column end decreases with the increase of the column end floors mass. The results in this paper is useful for the further derivation of column end constraint model.

Abstract: Due to diminishing fossil fuel, energy alternative availability becomes very crucial. Bio-oil is one of the alternative energy sources obtaining from the biomass pyrolysis process. This study's aim is to determine the effect of temperature and the addition of catalysts in the pyrolysis process. The catalyst was made of natural zeolite which was activated with an H₂SO₄ solution of 0.5 N and then heated at 350 °C for 12 hours. The pyrolysis of dry pine cone powder was run in a fluidized bed reactor enclosed by a furnace at a heating rate of 15 °C/min and residence time for 3 hours. From the existing variations, the largest bio-oil yield i.e. 34.28% was obtained from non-catalytic pyrolysis at the temperature of 500 °C, however, the bio-oil conceived high acids. On the other hand, the bio-oil comprised high phenolics and aromatics were generated from catalytic pyrolysis with 5% wt catalyst at a temperature of 500 °C. Eventually, the bio-oil from Pinus Merkusii cone has the potential to be biofuel and biochemical materials.

Abstract: A Fourier series method based on Mindlin theory and Hamilton variation principle has been proposed for the vibration modeling and analysis of composite laminated plates with arbitrary boundary conditions, in which the vibration displacements are sought as the linear combination of a double Fourier cosine series and auxiliary series functions. Three types of constrained springs are introduced to establish a general structural model of composite laminates, and the vibration model is established by combining the Hamilton energy principle. The accuracy, efciency and validity of the two solutions presented are demonstrated via comparison with published results. The influence of boundary conditions, laying angle and laying layer on vibration characteristics is analyzed. And it can be seen that the frequency of the structure increases with the increasing of the spring stiffness and the number of laying layers of the boundary of the laminated plate structure.