Evaluation of Isolated Impact of Trans Fatty Acids on Short Dough Product

In this study, the effects of trans fatty acids (TFAs) on rheological properties of dough (elastic moduli (G’), loss moduli (G”), complex modulus (G*)) and textural properties of dough and cookie (hardness) were studied. Two different groups of fat samples having different TFA composition but similar solid fat content (SFC) were prepared. Samples of the first group (group 1) had TFA between 0.0 and 56.23 %, while the samples of the second group (group 2) contained trans isomers ranging from 0.0 to 44.40 %. Texture measurements of different doughs and cookies prepared with different fat samples were performed. Texture measurements indicated that hardness values of doughs increased from 3950 ± 420 to 5498 ± 506 g in group 1 and 4700 ± 501 to 6787 ± 369 g in group 2 with increased amounts of TFAs. A particularly high, almost three‐fold increase in complex modulus values was observed in the dough samples containing the highest TFA levels compared with samples containing 0.0 % TFA. Although not significantly different, mean hardness and relative sound intensity values of cookies displayed an initial decreasing trend and then both parameters had maximum values when the TFA content was at maximum in both groups.     

Optimization of spray drying parameters for pink guava powder using RSM

The optimization of pink guava was executed using central composite face-centred design to optimize the spray drying parameters of inlet temperature, maltodextrin concentration (MDC) and feed flow (FF). The experimental results were significantly (p<0.01) fitted into second-order polynomial models to describe and predict the response quality in terms of the final moisture, particle size and lycopene with R ² of 0.9749, 0.9616, and 0.9505, respectively. The final moisture content significantly (p<0.01) decreased with increasing inlet temperature and MDC, whereas the particle size increased. In contrast, the lycopene content significantly (p<0.01) decreased with the higher temperature and increased with increasing MDC. However, according to multiple response optimization, the optimum conditions of 150°C inlet temperature, 17.12% (w/v) MDC and 350 mL/h FF-predicted 3.10% moisture content, 11.23 μm particle size and 58.71 mg/100 g lycopene content. The experimental observation satisfied the predicted model within the acceptable range of the responses.     

Effects of hydrogenation parameters on trans isomer formation,selectivity and melting properties of fat

Effects of hydrogenation conditions (temperature, hydrogen pressure, stirring rate) on trans fatty acid formation, selectivity and melting behavior of fat were investigated. To this aim, soybean oil was hydrogenated under various conditions and fatty acid composition, trans isomer formation, slip melting point (SMP), solid fat content (SFC) and iodine number (IV) of the samples withdrawn at certain intervals of the reactions were monitored. A constant ratio (0.03%) of Nysosel 222 was used in the various combinations of temperature (150, 165 and 180 °C), stirring speed (500, 750 and 1000 rpm) and hydrogen pressure (1, 2 and 3 bar). Raising the temperature increased the formation of fatty acid isomers, whereas higher stirring rates decreased this formation, while changes in hydrogen pressure had no effect or slightly reduced it, depending on other parameters. Results also indicated that the trans fatty acid ratio increased with IV reduction, reached the highest value when the IV was about 70 and decreased at IV < 70 due to saturation. Selectivity values (S₂₁) at that point ranged between 5.78 and 11.59. Lower temperatures and higher stirring rates decreased not only the trans isomer content but also the S₂₁ values at significant levels. However, same effects were not observed with the changes in hydrogen pressure. It was determined that a high SMP does not necessarily mean a high SFC. Selective conditions produced samples with higher SFC but lower SMP, which is possibly because of higher trans isomer formation as well as lower saturation.     

Circular discontinuities detection in welded joints using Circular Hough Transform

Conventional radiography is one of the common non-destructive testing which employs manual image interpretation. The interpretation is very subjective and depends much on the inspector experience and working conditions. It is therefore useful to have pattern recognition system in order to assist human interpreter in evaluating the quality of the radiographed sample, especially radiographic image of welded joint. This paper describes a system to detect circular discontinuities that are present in the joints. The system utilizes together two different algorithms, which are separability filter to identify the best object candidate and Circular Hough Transform to detect the presence of circular shape. The result of the experiment shows a promising output in recognition of circular discontinuities in a radiographic image. This is based on 81.82–100% of radiography film with successful circular detection by using template movement of 10 pixels.     

Influence of PTFE as a solid lubricant on the mechanical,electrical, and tribological properties of CF-reinforced PC composites

The objective of this research was to study the effects of polytetrafluoroethylene (PTFE) as a solid lubricant on the mechanical, electrical, and tribological properties of carbon fiber (CF)-reinforced polycarbonate (PC) composites. Samples were prepared by means of single-screw extrusion and injection molding processes. The mechanical tests included tensile, flexural, and failing weight impact tests, while the electrical tests consisted of surface and volume resistivity tests. The tribological testing was conducted under dry sliding conditions using pin-on-disk configuration. The results showed that the addition of CF managed to significantly reduce the electrical resistivity as the CF loading approached 10–15 wt%. The addition of PTFE managed to reduce the resistivity of the composite, that is, from 4.51 to 0.53 × 10 (Ωcm). The incorporation of 15 wt%. CF resulted with an increase of 45% in tensile strength and 51.5% in flexural strength, while the addition of PTFE had a negative impact on both properties. It was shown that PTFE was able to reduce the friction coefficient, μ and wear rate, K up to 0.257 and 6.35 × 10⁶ (mm³/Nm), respectively, which can be attributed to the excellent abilities of PTFE to form transfer film. The composite consisting of 15 wt% CF and 10 wt%. PTFE showed highest improvement in term of electrical resistivity, and is deemed the most suitable composition for this study. Scanning electron microscopy was also carried out to further elucidate the fracture and wear mechanism of the PC/CF/PTFE composites.     

Behavior of epoxy resin filled with nano-SiO2 treated with a Eugenol epoxy silane

Harvesting biobased silane coupling agent to enhance the connection between fillers and epoxy matrix is vital to achieve sustainable and environmentally friendly products. In this work, a eugenol based epoxy silane-coupling agent with high purity was prepared and used for the surface modification of nano-sized silica particles. The surface structure composition and physical properties of the modified nano-SiO₂ were characterized through nuclear magnetic resonance, Fourier transferred infrared spectrometer, X-ray photoelectron spectroscopy, and thermal gravimetric analyzer. An epoxy nanocomposite was subsequently prepared by incorporating the resulting modified nano-SiO₂ as an enhancing filler. The nanocomposites glass transition temperature, the morphology of fracture surface, dynamic mechanical properties, and thermostability were investigated. Results showed that the eugenol epoxy silane-coupling agent bearing a long chain structure of benzene ring in the molecular structure could improve the compatibility of silica fillers with epoxy resin and contribute to a better dispersion state in the matrix, thus enhancing the overall performance of epoxy-cured products.     

Thermo-responsive shape memory properties based on polylactic acid and styrene-butadiene-styrene block copolymer

This study aims to compare thermal, mechanical, and shape memory behavior of polylactic acid (PLA) blended with different structures of styrene-butadiene-styrene block copolymer (SBS), namely linear SBS (L-SBS), and radial SBS (R-SBS). The amount of L-SBS and R-SBS added was varied between 10 and 70 wt%, and the blending process was carried out using an internal mixer at 180°C before the shaping process by the compression molding. An improvement in the degree of crystallinity was observed across the entire composition range with less pronounced transition temperature change. Tensile strength and modulus of PLA/L-SBS blends were higher than PLA/R-SBS blends across all composition ranges. The results also revealed that the shape fixing ratio (R_f) and recovery ratio (R_r) of PLA/L-SBS were higher than PLA/R-SBS, with PLA70/SBS30 showed the best shape memory behavior. The morphology characteristics of the blend were also examined with the scanning electron microscope.     

Biodiesel production process optimization from Spirulina maxima microalgae and performance investigation in a diesel engine

Biodiesel is a renewable, easily biodegradable, eco-friendly and sustainable alternative energy source. In this investigation, crude oil was extracted from Spirulina maxima microalgae through biochemical conversion method with the help of soxhlet apparatus. Biodiesel production process parameters were optimized through base transesterification. Maximum biodiesel yield achieved was 87.75 % at optimal reaction condition after transesterification, when methanol to oil ratio was 6:1, catalyst loading was 1 % KOH (wt.%), temperature was 65 °C, and stirring speed was 600 rpm for a reaction time of 70 minutes. All the physicochemical properties of the produced biodiesel were determined and compared with the ASTM D6751 specification. Finally, performance and emission of an unmodified diesel engine was evaluated with 20 % and 40 % (v/v) biodiesel blends and compared the results with ordinary Diesel fuel (DF). Using biodiesel blends improves Hydrocarbon (HC) emission by 10-15 % and Carbon monoxide (CO) emission by 9.3-13.9 %. However, Brake specific fuel consumption (BSFC), Oxides of nitrogen (NOX), Carbon dioxide (CO₂) and smoke opacity were found to be slightly higher for biodiesel blends, and Brake thermal efficiency (BTE) was found slightly lower than DF. Thus, Spirulina maxima serves as a potential feedstock for biodiesel production and prospective fuel in diesel engine application.

     

Electrochemical behaviour of Mo‐containing austenitic stainless steels in buffer solution

The effect of pH on the electrochemical behavior of austenitic stainless steels in naturally aerated and nitrogen‐deaerated buffer solutions has been studied. Potentiodynamic and ac impedance techniques were used. The results indicate that corrosion current (I_corr) decreases with pH. By examining the impedance data for the seven tested steels under various conditions, it seems that the total resistance (R_T) value is a suitable indication parameter for explaining the role of molybdenum and the other supplementary alloying additions (Ni, N, Cu and Mn) on the passive film behaviors as a function of pH of the forming solutions. As a general trend, the R_T values for all steels tended to be lower in the basic buffer than in the acidic solutions.     

Nanopillar junctions

The fabrication of nanopillar devices has been essential to the understanding and development of metallic spin electronics. This paper discusses the processes that can be used for the fabrication of such structures and the challenges in which they present, with particular emphasis on extreme sub-micrometre pillar structures suitable for the study of spin-transfer torque effects.