Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Efficiency on Fungal Inhibition of Benzalkonium Chloride and Lemongrass Essential Oil on Polyester Fabric
Get PDFThese days, people spend most of their time indoors. Cinema is one example of an indoor place being full of people at a time. Upholstery fabrics in cinema are made of polyester fabrics, which are main food of fungi. Besides, fungi naturally grow in high humidity condition, seem expected in cinema. Fungi then are concerned regarding human health effect. This study applied Benzalkonium Chloride (BKC) and Lemongrass essential oil to inhibit the fungal growth on polyester fabric. The concentrations of BKC and Lemongrass essential oil applied were varied from 1 to 25 per cent. This research aims to seek minimum inhibitory concentration (MIC) and effective duration of both fungicides. The Polyester fabric 35 per cent (TC) and 100 per cent (TK) were determined according to AATCC Test Method 20-2008, 30-2004 Section III, and 81-2006. Moreover, we determine the damage of polyester fabric caused by both fungicides. Aspergillus niger was chosen for this experiment because it is a prevalent airborne fungi. This study indicates that BKC is more effective than Lemongrass essential oil regarding MIC and cost of fungicides. 1 and 5 per cent-BKC are suitable to inhibit the fungal growth on TC and TK fabrics respectively. Effective duration of 1 and 5 per cent-BKC are 18 and 30 days respectively. Furthermore, TK and TC fabrics are not damaged by 1 and 5 per cent-BKC. So 1 and 5 per cent-BKC would be recommended for practical use
Filling-and-Dragging Technique for A Particle-Entrapment Using Triangular Microwells
Get PDFTrapping particle such as a cell, cell spheroid or scaffold bead, in a large trapping spot, such as a microwell, is important in various biological aspects. To achieve high trapping efficacy, the management of two countering effects from hydrodynamic and gravitational force is a key requirement. To increase the possibility of controllable entrapment, this study proposed a new approach using the filling and dragging technique to trap particles. The investigation of the trapping efficacy in three different triangular microwells such as obtuse, equilateral and acute triangle was conducted. The extremely low flow rate was firstly introduced to fill the particles in the microwell, and the flow rate was subsequently increased to drag and rearrange the entrapped particles. High trapping rate of a single particle in an equilateral triangular microwell could reach 80% when trapping polystyrene beads. For biomaterial particle such as cell spheroid, the adhesiveness with the other and the microwell surface is the parameter that needs to be further investigated
Seismic Strengthening of RC Frame and Brick Infill Panel using Ferrocement and Expanded Metal
Get PDFThis paper presents the strengthening of reinforced concrete frame and brick infill panel by using ferrocement technique reinforced with expanded metal. Analytical models of the strengthened frame and infill panel were proposed. An experimental study on the strengthened frames was conducted to verify the proposed models. Two control specimens and two strengthened specimens were compared: the bare frame and the infilled frame. Special strengthening techniques were employed to protect against two major failures: the beam and columns of the frame were fully strengthened to prevent shear failure, and the infill panel was protected against corner compression failure. The frames were investigated under constant vertical load and lateral cyclic load. The seismic behavior of the retrofit frames was compared with the control specimens. The strengthened frames showed the significant increase of strength up to 64% and 87%, and the ductility capacity was also improved 77% and 66% for the bare frame and the infilled frame, respectively. The proposed model of strengthening for the frame and infill panel predicted the lateral resistance of the RC infilled frame with a reasonable accuracy when compared to the observed experimental results
Compressive Behaviors of Micropillar Sheets Made of PDMS Material Using the Finite Element Method
Get PDFThai Microelectronics Center fabricates micropillar sheets from soft lithography techniques and roll-to-roll process which were used as superhydrophobic and superoleophobic surfaces coated on marine structures and medical devices. This research aimed to study appropriate constitutive models and mechanical behaviours of PDMS micropillar sheets with two substrate thicknesses of 1,910 µm and 150 µm under compressive loading using ANSYS Mechanical APDL program. The constitutive models consisted of Mooney-Rivlin (2, 3 and 5 parameters), Ogden (1st, 2nd and 3rd orders), Neo-Hookean, Polynomial (1st and 2nd orders), Arruda-Boyce, Gent and Yeoh (1st, 2nd and 3rd orders) models were curved fitting with experiment data from uniaxial compression test. We found that the most accurate constitutive model was Mooney-Rivlin 5 parameter model for the low strain range . The compressive strength and the lateral collapse of micropillars depended on substrate thickness were studied. The lateral collapse of micropillars was found when the substrate thicknesses were 150 µm and 1,910 µm. As the substrate thickness decreased, the compressive strength decreased while the elastic stiffness increased. The maximum compressive forces per one micropillar were 21.060 µN and 18.549 µN for the 1,910 µm and 150 µm thick substrates respectively
Extraction and Enrichment of Lanthanide from Indonesian Low Grade Bauxite using Sulfuric Acid Heap Leaching and Phytic Acid
Get PDFThe Indonesian low grade bauxite from Wacopek, Bintan Island is of high economic value because it has 0.0052% lanthanum oxide (La2O3) and 0.0052% yttrium oxide (Y2O3). In this study, the lanthanides (La and Y) have been successfully extracted from the low grade bauxite using heap leaching method with sulfuric acid, precipitated with trisodium phosphate and complexing with phytic acid (PA). The optimal concentration of 0.1 M sulfuric acid 500 mL, 20 g bauxite could dissolve 24.39% lanthanum and 34.03% yttrium. After the extraction process using H2SO4, the extraction was followed by the precipitation reaction using trisodium phosphate (TSP). Phytic acid ligand has proven to precipitate some impurities such as Al, Fe and Mg ions. Here, PA has successfully removed 57.125% of Fe3+ impurities in pregnant leach solution (PLS). After two times precipitation and complexing methods using TSP and PA, concentration of lanthanum and yttrium increased to 83.6% (0.04411 ppm) and 89.20% (0.28431 ppm), respectively. The phosphate groups of PA as active sites is favorable selective to bind with heavy metal ions. Based on these results, PA is used to precipitate the impurities and formed complexes, thus PA was expected to have high effectiveness for lanthanide enrichment. Finally, this complexing process with PA have succeeded enrichment of lanthanum to 83.6% (0.04411 ppm) and yttrium up to 89.20% (0.28431 ppm)
Optimizing Extraction and Enrichment of Lanthanide from Indonesian Low Grade Bauxite Using Sequential Magnetic Separation, Acid Leaching, and Precipitation Processes
Get PDFIn this work, investigation on the extraction of lanthanide from Indonesian low grade bauxite using three processes, namely magnetic separation, acid leaching and precipitation methods. The magnetic separation produced three fractions, namely magnetic (3.37%), low magnetic (12.97%) and non-magnetic (81.54%) with recovery value of 97.9%. The non-magnetic fraction containing lanthanides with size of 200 mesh was used for leaching process using sulfuric acid (3 M) with a solid and liquid (S/L) ratio of 1: 5. The final treatment using precipitation reaction consisted of two stages using sodium sulfate and sodium hydroxide. The first stage using sodium sulfate produced lanthanide metal of ~ 13.00035% consisting of 11.84% (La), 1.16% (Ce), and 0.00035% (Y). The second stage using sodium hydroxide resulted lanthanide of ~0.00392% with consisting composition of La (0.00108%), Ce (0.00262%), and Y (0.00022%). After the series treatments, the concentration of lanthanides increased from 0.00396 % (39.6 ppm) to 13.00427 % (130,042.7 ppm). The total of lighter lanthanides La (54.66%) and Ce (4.80%) and heavy lanthanide of Y (0.013%) were obtained. These resulted showed that the application of acid leaching using sulfuric acid and precipitation reaction were recommended for enrichment of lanthanide from Indonesian low grade bauxite
Drag Reduction with Biopolymer-Synthetic Polymer Mixtures in Oil-Water Flows: Effect of Synergy
Get PDFThe search for lower cost materials that reduce pressure drop in fluid transport systems in oil and gas industries to conserve pumping energy is of paramount importance. Polymers are known to reduce pressure drop in pipeline oil-water flows in a process referred to as drag reduction (DR). The effect of partially hydrolysed polyacrylamide, polyethylene oxide, Aloe Vera mucilage and their mixtures as drag reducing polymers (DRPs) on pressure gradient (pressure drop; Δp) in pipeline oil-water flows were studied. The experiment was carried out in flow rig with 0.02-m diameter straight unplasticised polyvinylchloride (uPVC) pipe, two centrifugal pumps, control valves and two storage tanks. Tap water (ρ = 997 kg/m3 and µ = 0.89 cP) and diesel (ρ = 832 kg/m3 and µ = 1.66 cP) were used as the test fluid at ambient condition. The polymer mixture total concentration (MTC) of 30 and 400 ppm at different mixing proportion, mixture Reynolds number (Remix) and oil input volume were investigated. The results show increase in pressure gradient with increase in oil input volume in both single-phase water flow and oil-water flow before adding drag reducing polymers (DRPs). However, Δp decreased after adding DRPs with increase in Reynolds number (Re) or Remix and decrease in the oil-phase Re, and vice versa. The results further showed higher reduction in pressure drop by the polymer mixture than in each of the polymer used at the same conditions. The rigidness of the biopolymer was improved by adding synthetic polymers which resulted to increase in DR efficiency
Experimental Study on Anode Life and Effective Distance of Sacrificial Cathodic Protection in Reinforced Concrete
Get PDFThe purposes of this study were to examine influences of concrete quality and environmental severity on anode life and to determine effective distance of sacrificial cathodic protection in reinforced concrete. 100 x 100 x 400 mm3 concrete beams embedded with a reinforcement at distance of 25 mm from top surface were prepared and sacrificial zinc anode plates were attached on top surface of specimens. 700 x 700 x 75 mm3 concrete slabs embedded with reinforcement mesh of 150 mm spacing were prepared and sacrificial anode were attached on top surface of concrete slabs at lower-left corner. The concrete beams and slabs were then exposed to wet-dry cycle and impressed voltage corrosion accelerations. The anode life was determined by time taken for total consumption of anode in concrete beams and the effective distance was determined by distance influenced by polarization effect of sacrificial anode in concrete slabs. Time taken for total consumption of anode and polarization effect were interpreted from corrosion potential data conducted in accordance with the ASTM C876. As a result, the anode life increased with increasing of concrete quality and decreased with increasing of the environmental severity. The effective distance was approximately 500-600 mm from the anode-installed position
Two Different Portables Visible-Near Infrared and Shortwave Infrared Region for On-Tree Measurement of Soluble Solid Content of Marian Plum Fruit
Get PDFThe goal of this study was to predict the soluble solid content (SSC) of on-tree Marian plum fruit using two different wavelength range and algorithm. One of these was the commercial dispersion NIR spectrometer (MicroNIR 1700), providing shortwave infrared (SWIR), while the other was a making diode array spectrometer giving visible-near infrared (Vis-NIR). To search optimal model, the analytical ability of the two wavelength ranges spectrometers coupled with two algorithms: i.e. partial least squares regression (PLSR) and support vector machine regression (SVR), were investigated. Different spectral pre-processing methods were tested. The model providing the lowest root mean square errors of prediction (RMSEP) was selected. Overall, the proposed outcome was that the performance of SWIR was more accurate than Vis-NIR spectrometer, and that both SWIR and Vis-NIR coupled with PLSR algorithm had a higher accuracy than SVR algorithm. The best model for on-tree evaluation SSC was the SWIR constructed using the PLSR algorithm with the spectral pre-processing of the 2nd derivative, providing a coefficient of determination of calibration set (R2) of 0.81, a coefficient of determination of validation set (r2) of 0.76, RMSEP of 0.69 °Brix, and a relative standard error of prediction (RSEP) of 4.43%. The outcome showed that a portable SWIR spectrometer developed with PLSR could be used for monitoring the SSC of individual Marian plum fruit on-tree for quality assurance
Corrosion Resistance of Ti-6Al-4V Machined Surfaces Improved by Thermal Oxidation
Get PDFTi-6A-l4V alloy is widely used in implants and prosthesis applications. Although machining is a fast and economical process, the roughness generated can compromise corrosion resistance. Thus, the goal of this study was to overcome this limitation using thermal oxidation in machined surfaces. Samples with polished surfaces were used for comparison purposes. Two sets of machining parameters were used to generate different roughness, property evaluated in polished and machined samples before and after thermal oxidation. Vickers microhardness and polarization tests using simulated body fluid (SBF) were also performed. Thermal oxidation generated similar microhardness for polished and machined samples, higher than for polished and non-oxidized condition. On the other hand, oxidation increased the roughness only for polished condition. The corrosion resistance was improved in all oxidized samples, and the best result was found to the intermediate roughness (Ra = 0.76 um), in a machined sample. The results demonstrated that thermal oxidation can be used to overcome machining limitations regarding corrosion resistance, achieving behavior even better than polished samples