Absorption of Aramid Prestressing Rods in Aggressive Solutions

Fiber-reinforced plastic (FRP) reinforcing bars are not prone to classical electrochemical corrosion. However, this material may suffer from other degradation mechanisms when exposed to moisture, alkaline, or acid solutions for a long period of time. In the present study, the absorption characteristic of aramid fiber-reinforced plastic (AFRP) prestressing rods with epoxy matrix was investigated in terms of weight gain or loss by immersing the rods in water, alkaline, and acid solutions for more than a year. The results showed that the weight of the 8 mm diameter AFRP rods immersed in water increased in weight marginally. The weight of the rods immersed in an alkaline or acid solution increased significantly. A scanning electron microscope photograph showed the penetration zone at the cross section of the rods when immersed in three different solutions. An electron probe microscope analyzer examination is useful to detect the presence of the ion Na+ from the NaOH solution where the rods were immersed. A Simplified Diffusion Model can predict the depth of penetration and was verified by a scanning electron microscope measurement.     

Comparative study between supported and doped MgO catalysts in supercritical water gasification for hydrogen production

Different catalyst structures may influence the catalytic performance of catalysts in supercritical water gasification (SCWG). This study reports the catalytic activity of supported (SP) and doped (DP) MgO catalysts in catalyzing the gasification of oil palm frond (OPF) biomass in supercritical water to produce hydrogen. Two types of supported catalysts, labelled as Ni-SP (nickel supported MgO) and Zn-SP (zinc supported MgO), were synthesized via impregnation method. Another two types of doped catalysts, labelled as Ni-DP (nickel doped MgO) and Zn-DP (zinc doped MgO), were synthesized by using the self-propagating combustion method. All the synthesized catalysts were found to be pure with the doped catalysts exhibited small crystallites, in comparison to that produced by the supported catalysts. The specific surface area increased in the order of Ni-DP (67.9 m² g⁻¹) > Zn-DP (36.3 m² g⁻¹) > Ni-SP (30.1 m² g⁻¹) > Zn-SP (13.1 m² g⁻¹). Regardless of supported or doped, the Ni-based catalysts always had larger specific surface area than that in the Zn-based catalysts. Unexpectedly, the Zn-based catalysts with smaller surface area for SCWG produced higher hydrogen (H₂) yield from the OPF biomass. When compared to the non-catalytic reaction, the H₂ yield increased by 187.2% for Ni-SP, 269.0% for Zn-SP, 361.7% for Ni-DP, and 438.1% for Zn-DP. Among the studied catalysts, the Zn-DP displayed the highest H₂ yield because it had the highest number of basic sites; approximately twenty-fold higher than that of the Zn-SP catalyst. The Zn-DP also proved to be the most stable catalyst, as verified from the X-Ray photoelectron spectroscopy (XPS) results. As such, this study concludes that the catalytic performances of the synthesized catalysts do not only depend on the specific surface area, but they are also influenced by the number of basic sites and the catalyst stability. It is trustworthy to note that this is the initial study that associated SCWG with doped catalysts. The doped catalysts, hence, may serve as a new catalyst system to generate SCWG reactions.     

The effect of nitrogen supplementation on the efficiency of colour and COD removal by Malaysian white-rot fungi in textile dyeing effluent.

White-rot fungi, namely Coriolus versicolor and Schizophyllum commune, were studied for the biodecolorization of textile dyeing effluent in shaker-flask experiments. The results showed that C. versicolor was able to achieve 68% color removal after 5 days of treatment while that of S. commune was 88% in 9 days. Both fungi achieved the above results in non-sterile condition with diammonium hydrogen phosphate as the nutrient supplement. On the other hand, the best COD removal of 80% was obtained with C. versicolor in 9 days in sterile effluent with yeast extract as nutrient supplement, while S. commune was able to remove 85% COD within 8 days in non-sterile textile effluent supplemented with diammonium hydrogen phosphate.     

The investigation of work-related musculoskeletal disorders among female workers in a hazelnut factory: Prevalence,working posture,work-related and psychosocial factors

BackgroundWork-related musculoskeletal disorders (WMSDs) are the most common occupational health problems in the industrialized world. The identification of WMSDs specific to occupation is essential to plan and implement preventative programs. This study investigated the prevalence of WMSDs and determined the factors related to the severity of the most common disorders among female workers in a hazelnut factory.MethodsA total of 114 female workers were examined in this cross-sectional study using the Nordic Musculoskeletal Questionnaire, the Dutch Musculoskeletal Questionnaire, and an author-developed questionnaire (for socio-demographic characteristics and psychosocial factors). Working posture, craniovertebral angle, thoracic kyphosis angle (TKA), and lumbar lordosis angle were evaluated based on a photogrammetry method using the ImageJ program.ResultsThe prevalence of WMSDs in at least one body part during the last 12 months was 92.1%. The highest prevalence of WMSDs was in the lower back (61.4%), neck (57.9%), shoulder (53.6%), and upper back (45.6%). The least affected part was the elbow. Lower back, shoulder, and neck disorders were the most common causes of activity limitation. The severity of lower back pain was associated with stress in the workplace and work-related factors. The neck pain severity was related to craniovertebral angle and work-related factors. The shoulder pain severity increased with TKA and employment duration. TKA was related to upper back pain severity.ConclusionsWMSDs are common among female workers in a hazelnut factory. Reorganizing of working posture, work-related factors, and stress at work may be beneficial to decrease the prevalence of WMSDs and pain severity.Relevance to Industry; The female workers in the hazelnut factory are vulnerable to the work-related musculoskeletal disorders, particularly in the spinal region. The employers should endeavor to improve the health of the workers by the adjustment of the working posture and environmental factors.     

Humanoid robot arm performance optimization using multi objective evolutionary algorithm

As humanoid robots are expected to operate in human environments they are expected to perform a wide range of tasks. Therefore, the robot arm motion must be generated based on the specific task. In this paper we propose an optimal arm motion generation satisfying multiple criteria. In our method, we evolved neural controllers that generate the humanoid robot arm motion satisfying three different criteria; minimum time, minimum distance and minimum acceleration. The robot hand is required to move from the initial to the final goal position. In order to compare the performance, single objective GA is also considered as an optimization tool. Selected neural controllers from the Pareto solution are implemented and their performance is evaluated. Experimental investigation shows that the evolved neural controllers performed well in the real hardware of the mobile humanoid robot platform.     

Techno-economic comparison of three biodiesel production scenarios enhanced by glycerol supercritical water reforming process

In this study, techno-economic comparison of three different biodiesel production scenarios integrated with glycerol supercritical water reforming (SCWR) process to produce electricity is conducted. In the first scenario, biodiesel is synthesized from acid-pretreated waste cooking oil (WCO) in the presence of alkali catalyst. In the second scenario, biodiesel is obtained from WCO by acid catalyst. In the third scenario, biodiesel is derived from WCO using acid catalyst, followed by hexane extraction of the produced methyl esters. The glycerol evolved from all the above-mentioned pathways is then subjected to the SCWR process in order to produce hydrogen. The produced hydrogen is then combusted to provide thermal energy required by biodiesel production and purification processes as well as to generate electricity. All the developed scenarios are modeled and simulated in Aspen HYSYS software environment. In order to simplify the simulation process, canola-based WCO is considered as triolein with 6 wt% oleic acid (free fatty acid) and, accordingly, the prepared biodiesel is taken into account as methyl oleate. In order to compare the economic profitability of the developed approaches, several economic indicators including net present value (NPV), internal rate of return (IRR), payback period (PBP), discounted payback period (DPBP), and return on investment (ROI) are used. A sensitivity analysis is also carried out to show how variations in feedstock, biodiesel, and electricity prices can affect the NPV of the developed scenarios. According to the results obtained, the highest IRR and ROI values as decision-making parameters are obtained for the first scenario, manifesting its suitability from the techno-economic viewpoint. The economic indicators of the second scenario are also acceptable and very close to the first approach. Overall, upgrading glycerol into hydrogen using SCWR process appears to be an attractive strategy for enhancing the economic viability of biodiesel production plants.     

Model development for quality features of resistance spot welding using multi-objective Taguchi method and response surface methodology

In this research, the effect of parameters in Resistance Spot Welding (RSW) on the weld zone development was first investigated using Taguchi Method. Further, the RSW parameters were to be optimized based on multiple quality features, focusing on weld nugget and Heat Affected Zone using multi-objective Taguchi Method (MTM). The optimum welding parameter for MTM was obtained using Multi Signal to Noise Ratio and the significant level was further analyzed using Analysis of Variance. Lastly, Response Surface Methodology was employed to develop the mathematical model for predicting the weld zone development. The experimental study was conducted under varied welding current, weld time and hold time. To validate the predicted model, experimental confirmation test was conducted for plate thickness of 1 and 1.5 mm. Based on the results, the developed model can be effectively used to predict the size of weld zone which can improve the welding quality and performance in RSW.     

Supermacroporous poly(vinyl alcohol)-carboxylmethyl chitosan-poly(ethylene glycol) scaffold: an in vitro and in vivo pre-assessments for cartilage tissue engineering

This study aims to pre-assess the in vitro and in vivo biocompatibility of poly(vinyl alcohol)-carboxylmethyl-chitosan-poly(ethylene glycol) (PCP) scaffold. PCP was lyophilised to create supermacroporous structures. 3-(4, 5-dimethyl-thiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and immunohistochemistry (IHC) were used to evaluate the effectiveness of PCP scaffolds for chondrocytes attachment and proliferation. The ultrastructural was assessed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Extracellular matrix (ECM) formation was evaluated using collagen type-II staining, glycosaminoglycan (GAG) and collagen assays. Histological analysis was conducted on 3-week implanted Sprague–Dawley rats. The MTT, IHC, SEM and TEM analyses confirm that PCP scaffolds promoted cell attachment and proliferation in vitro. The chondrocyte-PCP constructs secreted GAG and collagen type-II, both increased significantly from day-14 to day-28 (P < 0.05). PCP scaffolds did not elicit any adverse effects on the host tissue, but were partially degraded. These results suggest that supermacroporous PCP is a biocompatible scaffold for clinical applications.