Scanning electron microscope (SEM) is the most important tool used for characterizing brake pad surfaces. Case studies on characterizing five different friction composite formulations are presented in this paper. Different features of SEM are related to explain the increase or decrease of friction and wear values. Different wear mechanisms operating at different temperatures are discussed. Special features in SEM results are highlighted for better understanding. Surface morphology, loose particles, friction films, primary and secondary plateaus are identified on worn surfaces. The case studies presented in this paper are expected to impart knowledge and skills to practicing R & D Engineers to characterize brake pad surfaces.
The mechanical properties of Al-Mg-Si alloys are depending upon many factors such as alloy composition, casting method, heat treatment procedures (solution treatment temperature, aging time and temperature) and other parameters which could affects the aging response and behaviors. In this study, aging response and fracture surface morphology of two Al-Mg-Si alloys with different wt% of Mg and Si compositions of Al-Mg-Si alloys were investigated. The experimental procedures were started with a heat treatment process where firstly both alloy samples were solution treated at 540 °C for 30 minutes, followed by quenched into cold water. The solution treated alloy samples were artificially aged at an elevated temperature of 170 oC for 0.1 to 100 hours. The aging response and mechanical properties were examined by Vickers hardness and tensile test. The surface fractured morphology from the tensile specimen in peak-aged condition at 170 °C was carried out using a field emission scanning electron microscope (FESEM). It was found that the composition of Mg and Si present in the alloys affects the aging response and mechanical properties. As the composition of Mg and Si increased, the mechanical properties of the alloys also increased and gave a stronger aging response to the alloys. The FESEM analysis exhibited that the alloy P which contained higher composition of Mg and Si showed a less ductile behaviour and lower elongation properties, hence the results of the FESEM analysis are in line with the results of hardness and tensile test.
The successful interactions between the sawdust and matrix are among the significant factors determining the strength and durability of wood-plastic composites (WPCs). This work aims to evaluate the structural and mechanical properties of high-density polyethylene (HDPE) composites reinforced with sawdust pretreated with ionic liquids 1-butyl-3-methylimidazolium chloride (BMIMCl) followed surface modification by cationic surfactant, n-hexadecyl trimethylammonium bromide (C16H33N(CH3)3Br, (CTAB). The chemical and structural properties of raw and pretreated sawdust were analysed using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD). The morphology of the sawdust was observed using field emission scanning electron microscopy (FESEM). After sawdust analysis, the raw and pretreated sawdust was mixed into the HDPE, in a proportion of 30/70 wt% using a single screw extruder followed by injection moulding. Furthermore, the specimens for tensile and flexural testing was prepared to evaluate the mechanical properties. The fractured surface of the composites was also analysed using FESEM. The results showed that the pretreatment with BMIMCl and CTAB had improved the crystallinity and functionalisation of CTAB into sawdust structure. The mechanical results showed that the composites reinforced with BMIMC- and CTAB- treated sawdust showed only an improvement in elongation but did not improve tensile and flexural strength.
Stress-depression disorder comprised of 29 % and 12 % among adults and children in Malaysia, respectively. It involves a series of pathological stages associated with weight loss and anhedonia. Previous studies on stress-depression model mainly focused on changes at molecular level. Therefore, this study aims to investigate the sucrose preference activity, body weight changes and histopathological changes in kidney and liver of stress-depression disorder induced-rats by chronic unpredictable mild stress (CUMS) model supplemented with acacia honey (AH). Eighteen male Sprague-Dawley rats were divided into three groups [(1) normal control (NC), (2) CUMS-induced stress-depression and (3) CUMS supplemented with AH] and were subjected to sucrose preference test (SPT). The body weight was recorded weekly whereas the liver and kidney were collected at the end of the experiment. The results showed CUMS-induced stress-depression rats (28.60 % ± 1.86) had a significant decrease in the percentage of body weight whereas CUMS supplemented with AH demonstrated no significant changes (31.34 % ± 1.88, p > 0.05) compared to NC (38.60 % ± 2.67). SPT demonstrated a significant increase in the sucrose preference ratio for CUMS supplemented with AH group (83.67 % ± 1.20) compared to CUMS-induced rats (44.33 % ± 12.17). CUMS-induced rats had abnormal histopathology for kidney and liver compared to NC and AH supplemented groups. In conclusion, AH improved body weight, sucrose preference ratio and protect the liver and kidney of the stress rats against abnormal histopathological changes.
This study determined the anti-cancer properties of proteinaceous postbiotic metabolite (PPM) produced by Lactobacillus plantarum I-UL4, against colorectal cancer model in rats and elucidated the immunomodulatory activities involved. The rats were subjected to injection with azoxymethane for two subsequent weeks to induce colorectal cancer, and subsequently fed with PPM (0.25%, 0.5% and 0.75% (w/v)) added into drinking water, at week 26, once daily for 12 weeks. Cancer severity and immunomodulatory properties of PPM were determined by histopathology analysis and level of cytokines (IFN-γ, TNF-α, IL-12 and IL-5) in serum, spleen and thymus cell suspensions, respectively. Treatment with PPM significantly (p<0.05) reduced the total number of aberrant crypt foci (ACF) and crypt multiplicity, incidence of tumor, adenoma and adenocarcinoma, with decreased expression of s-catenin in a dose-independent manner. The level of all cytokines, except for IL-12 in serum, increased significantly (p<0.05) in both spleen and thymus cell suspensions after treatment with PPM compared to control. PPM produced by Lactobacillus plantarum I-UL4 exhibited anti-colorectal cancer properties and enhanced the level of several cytokines that play crucial roles in the inhibition of colon carcinogenesis.
