Applied Mechanics and Materials Vol. 891

Abstract: Hydrazine hydrate is a highly toxic chemical widely used in agricultural and pharmaceutical industries. Exposure to hydrazine can induce an irritation of respiratory tract, blindness, damage of the DNA and central nervous system. In this paper, we will show the hydrazine hydrate (N₂H₄) detection using fluorescence carbon nanodots synthesized from mandarin rind, the so-called R-CNDs. Highly sensitive detection can be seen by naked eyes in a fluorescence red-shifting and by analyzing absorption spectra in case of micromolar concentrations of hydrazine hydrate solution.

Abstract: In this work, we investigated ethanol production from the common aquatic plant hydrilla by hydrolysis process. This was achieved using a fermentation medium mixed with aqueous solutions of H₂SO₄ (0.5%) and NaOH (1%). Firstly, fermentation medium was obtained from washing rice. Samples were left to ferment in the acidic and basic solutions for different time scales and tested for alcohol concentration. The resulting of producing ethyl alcohol were at 4.0% for H₂SO₄ cont. 0.5% , 3.5% for NaOH cont. 1% and 5.0% for H₂O solution at measuring of time ~6 hours.

Abstract: In this study, ultrasound-assisted extraction (UAE) was compared with conventional extraction methods, including conventional solvent extraction without agitation (CSE), conventional solvent extraction with agitation at 50 rpm (CSE50) and 150 rpm (CSE150), for the extraction of phenolic compounds from coconut (Cocos nucifera L.) husk. The extraction yield, total phenolic content (TPC) and total flavonoid content (TFC) were examined. The antioxidant capacity of C. nucifera extracts was determined by using 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. Experimental results showed that UAE gave the highest extraction yield, TPC, TFC and antioxidant capacities (ABTS and DPPH), followed by CSE150, CSE50 and CSE, respectively. UAE was found to be more effective than conventional extraction methods. Conventional solvent extraction with higher agitation speed exhibited higher extraction efficiency than those with lower agitation speed and without agitation.

Abstract: Amperometric biosensors were fabricated by immobilizing alcohol oxidases (AOX) from two different sources onto glutaraldehyde (GA)-activated supports. Alcohol oxidases from Hansenula sp. and from Pichia pastoris were employed for immobilization. The biosensor with AOX from Hansenula sp. showed a linear response to ethanol in the concentration range of 0.1-0.6 mM with a sensitivity of 88.534 µA mM^-1 cm^-2 and a detection limit of 0.1 mM (S/N=3). In comparison, the biosensor with AOX from P. pastoris showed a linear response from 0.1-0.5 mM ethanol with a sensitivity of 76.886 µA mM^-1 cm^-2 and a detection limit of 0.1 mM. The study of stability of biosensors revealed that after 90 measurements, the biosensor with AOX from Hansenula sp. retained 97% of its original current response whereas the current response of the biosensor with AOX from P. pastoris decreased to 81% of its initial value. The biosensor with AOX from Hansenula sp. demonstrated slightly higher sensitivity and stability than the biosensor with AOX from P. pastoris.

Abstract: Nowadays, most people are living with busy schedule. Consequently, people have to select the most convenient option to save their time. Instant rice is considered as one of the possible solutions to serve most people present lifestyle. However, the problems with instant rice including slow rehydration and poor quality affect the consumer acceptability. This research focused on drying methods in order to improve the quality of instant rice. Two drying methods were investigated: Industrial microwave drying (IMD) and fluidized bed drying (FBD). The results of quality evaluation revealed that whiteness and texture of IMD had no significant difference with freshly cooked rice. In addition, IMD had better quality of product compared to FBD in term of texture and whiteness. IMD (6,400 watt, 2,450 MHz) was appropriate drying method to produce instant rice because of the fast rehydration time for 4 minutes by boiling water while FBD (85°C 60 min) took slower rehydration time for 9.5 minutes. Furthermore, after rehydration, the rice physical appearance of FBD and IMD were not coagulated and not broken and good quality. Therefore, instant rice processing by IMD is recommended for the instant rice production at the industrial scale.

Abstract: Surface plasmon resonance (SPR) based biosensor is a gold standard optical sensor for biological protein interaction in life science. In this paper, we firstly discuss how the SPR based sensor can give unique advantages over other sensing techniques for food safety and food quality control in food industry. We discuss the differences in sample preparation process for the SPR system and other screening methods and point out that the SPR can reduce the food screen quality control cost and time. A brief review of food analysis that has been tested under SPR system. Key requirements for building up a surface plasmon resonance based sensor for food industry especially in Thailand are highlighted. An SPR based sensor has been recently developed and constructed based on the requirements. We also discuss practical issues and how to possibly get around them.

Abstract: The purpose of this research was to fabricate the particle board from the coffee husk. The coffee husk from Chumphon province of Thailand was collected, prepared and separated into four groups such as outer husk, inner husk, the mixture of inner and outer husk and husk from the milling process. The coffee husk particle sheet was formed by the compression molding with the heater. Then the coffee husk particle sheets were the mechanical properties testing. The results showed the coffee husk particle sheet from milling process pass the Thai industrial standard (TIS.876/2547). However, the results of swelling and water absorption indicated that all the coffee husk sheet were not passed the TIS.876/2547. The effect of coffee husk particle size on mechanical properties was clarified. The coffee husk particle sheet from the particle size of 2, 4 and 6 mm was mechanical testing and follow TIS.876/2547. The coffee particle size of 2 mm showed the passing the standard. Moreover, the effect of isocyanate adhesive on mechanical properties was investigated. The weight percentage range of isocyanate adhesive on coffee husk from 7 to 13 %wt was carried out. The weight percentage of 9, 11 and 13 showed according to TIS.876/2547. From the experiment indicated that the coffee husk could be applied to the wood particle board industrial.

Abstract: Drought indices analysis plays a vital role in flood and drought monitoring and early warning, which is a main responsibility of Thai Meteorological Department (TMD), especially the basins that are limited in use o¬¬f water resources such as Kok and Ing river basins. This study aims to analyze drought situations utilized Standardized Precipitation Evapotranspiration Index (SPEI) at Chiangrai and Phayao provinces (located Kok and Ing basins). Both observed data, precipitation and temperature, are used for calculation (data in between 1951-2018 for Chiangrai and 1981-2018 for Phayao). The result shows that SPEI can determine drought probability and its potential impact in the observed area. This study could be applied to drought monitoring over other basins.

Abstract: The rapid development of advanced technology in Thailand has resulted in an increased impact from micro-pollutant accumulation through wastewater. Phenolic compounds, generally originating from synthetic and plastic products, have been frequently detected in industrial and municipal wastewater. Releasing these compounds into the environment affects the human body at trace levels. In terms of economic perspective and environmental considerations, filtration is an appropriate process for wastewater treatment. In this research, filtration material made from eggshell ash was investigated for organic micro-pollutant removal. The mechanical strength of the derived filtration materials was evaluated in terms of compressive strength. For the fabrication process, the different proportions were composed in a range of 45% – 55% of eggshell ash. Eggshell ash contents could increase the porosity of the filtration specimen by heat at a temperature of 750 °C. The removal efficiency of filtration material approximately more than 80%. The ratio of 55% of eggshells showed better results with permeability value of 57±3.5 L/m²/h and compressive strength of 5.25 MPa.

Abstract: Utilizing coconut coir fiber can offer an alternative method of adding value to agricultural wastes and help to conserve the environment with green products. The aim of this research was to investigate the potential use of coconut coir fiber as an eco-friendly material for cement composites. The properties of these cement composites mixed with varying proportions of paper waste were compared to ordinary white Portland cement. In addition, the surface structure and chemical characteristics of the samples were examined with a scanning electron microscope (SEM) and an energy-dispersive x-ray spectrometer (EDS). The results showed that the cement composites consisted mainly of the elements carbon (C), oxygen (O), and calcium (Ca) in the range of 34-44%, 42-49%, and 11-19% by weight, respectively. The density of OPC, 0%, 50%, 100% of coconut coir fiber cement composite at 28 days curing time were found 1.85±0.03 g/cm³,1.72±0.02 g/cm³, 1.66±0.05 g/cm³, 1.56±0.02 g/cm³, respectively. Moreover, the compressive and flexural strength of the cement composites decreased with an increase in the coconut coir fiber volume fraction.