Adhesion failure of rubber / metal composites under chloride environment / Ismaliza Ismail

Maintaining a good adhesion between rubber to substrate bond in rubber composite structures is very crucial and of high importance to ensure a satisfactory and efficient products performance in service. The bond durability are influenced by factors of the environments such as moisture, chlorides and corrosion. Bond durability in bonded rubber components exposed in marine environment has been the main subject of study, focusing mainly on understanding the mechanisms resposible for its failures. The main objective of this work is to determine the adhesion failure mechanisms of rubber/metal composites exposed in a simulated chloride containing environment. The experimental works were divided into five major parts including salt spray test, alkaline exposure test, cathodic disbonding & anodic undermining tests, de-adhesion test in water and Linear Polarization Resistance (LPR) & Electrochemical Impedance Spectroscopy (EIS) tests. Characterization of the adhesion failures were conducted using Scanning Electron Microscopy (SEM) with Energy Dispersive X-rays Spectrometry (EDX) technique. The results found that the adhesion behaviour of the bonded rubber to metal exposed in salt environment is primarily controlled by cathodic disbonding induced by corrosion reaction. The disbondment front being cathodic due to the oxygen reduction reaction is alkaline in nature in which the alkaline media attack the 205 primer. The results were supported by cathodic disbonding, alkaline exposure and Fourier Transform Infrared Spectroscopy (FTIR). EIS analysis indicated the changes of the 205 primer barrier properties and concluded that the oxygen uptake within the water become a rate determining step towards attributing to the adhesion failure. The other results found that neither the oxidation reaction nor the water displacement are dominating the adhesion failure

Surface modification for enhancement of barrier and adhesion properties of rubber/mild steel bonding system in salt environment / Ismaliza Ismail

The bond durability of rubber/mild steel components exposed to aggressive environments depends on the types of environments and duration to which the components are exposed to. Corrosion reactions on mild steel substrate have induced premature adhesion failures of rubber/mild steel components after exposure to marine conditions. An alkaline media generated by the cathodic reduction reaction in a corrosion process, was found to have degraded the commercial phenolic modified chlorinated rubber primer coating used in the bonding system leading to premature adhesion failure of the components. Thus, the strategic goal of this research is to reduce corrosion and minimize the effects of its processes on adhesion loss of primer coating through surface modification of the mild steel substrate. This research emphasizes on developing a multifunctional mild steel surface modification system using silane-based compound with the intention of improving the surface energy for adhesion while simultaneously inhibiting corrosion through the use of inhibitors. In this work, a synergistic effect of silane coupling agent, 3-glycidoxypropyltrimethoxysilane (3-GPS), surfactant inhibitor, sodium dodecylbenzene sulfonates (SDBS) and ZnSO4 pretreatment on mild steel has been investigated. The surface characterizations were done using FTIR, SEM, EDX, XPS and contact angle analysis. The effects of surface modification on the electrochemical reactions were examined through potentiodynamic measurement combined with the electrochemical impedance spectroscopy (EIS), while, its effect on the surface energy was evaluated through adhesion analysis. A two-pack polyamide cured epoxy, and a commercial phenolic modified chlorinated rubber coatings were used to measure the effectiveness of the surface modification of mild steel. The overall performance of the coated mild steel against corrosion was further evaluated through EIS, cathodic, and anodic delamination tests. The result found that SDBS:ZnSO4 mixtures resist the mild steel corrosion in 0.05 M NaCl solution with inhibition efficiency of 96 % obtained at a 200:200 ppm ratio. This phenomenon was due to the formation of a compact insoluble layer of zinc hydroxide/oxide together with SDBS complex on the metal surface, which then impedes both the oxygen reduction and oxidation reactions on mild steel. The dense hydrophobic tail of SDBS compound that deposited on the metal surface further hinders the electrolyte diffusion towards the mild steel surface. This formation of the protective layer was confirmed through surface characterizations. A neat 3-GPS silane was not able to provide an effective corrosion-resistant film on mild steel although it did significantly improves the adhesion of epoxy coating. On the other hand, 3-GPS silane used in combination with SDBS:ZnSO4 inhibitors was found to have improved both the corrosion resistance of mild steel substrates as well as adhesion of the epoxy coating. However, the result shows that the adhesion strength is lower if compared to the neat silane indicating that SDBS:ZnSO4 inhibitors has distrupted the bond formation between epoxy and mild steel substrate. However, this sample has higher resistance towards cathodic and anodic delamination. These combined results show that there is no correlation between adhesion and corrosion resistance. It shows that excellent adhesion is not always necessary to prevent corrosion in which underfilm corrosion depends on inhibition rather than adhesion. Phenolic modified chlorinated rubber coating applied on 3-GPS/SDBS:ZnSO4 treated mild steel was found to be more resistant towards cathodic and anodic delamination despite having a lower adhesion compared to the untreated mild steel

Potential of a novel and thermostable recombinant phage endolysin of Escherichia phage KW1E_UTAR against Shigella spp.

Shigella causes millions of cases and hundreds of thousands of deaths annually, mainly affecting children in impoverished countries. Shigellosis outbreaks have been linked to waterborne transmission, and chlorination is commonly used to disinfect water. However, the emergence of chlorine-resistant Shigella spp. is a concern. Therefore, it is imperative to develop an alternative antibacterial agent such as endolysin against the Shigella spp. In this study, the Escherichia phage KW1E_UTAR gene encoding for endolysin was successfully cloned and expressed in Escherichia coli pET-28a. The purified endolysin was characterized, and its antibacterial activity was determined. The purified endolysin remained stable between pH 4 and 9, and at a broad range of temperature (4°C–75°C). The endolysin's storage stability was tested for one week, one month, and three months at different temperatures (4°C, −20°C, and −80°C). Despite over 50% drop in the lytic activity, the purified endolysin outperformed the commercial lysozyme. Besides, all four Shigella spp. tested were susceptible to the purified endolysin, with Shigella flexneri being the most prominent. Subsequently, the purified endolysin’s effectiveness in removing S. flexneri from spiked water samples was evaluated. After an hour of treatment, the number of viable bacteria in the water samples was reduced by 99.9%. Therefore, endolysin could be effective at eradicating Shigella spp. in various water sources

Production of calcined eggshell: Process description and economic analysis

Adsorbents derived from eggshell (ES) have been proven to be effective for a variety of pollutants including organic and inorganic pollutants from different types of wastewater. Calcined eggshell (CES) had demonstrated a significant performance in which are on par with or even exceeds the commercially available adsorbents for phosphorus removal or recovery. This study aims to develop the process flow diagram for large scale production of CES with an overall economic analysis. A process flow diagram was developed starting from the transportation to storage of final product, CES. Calculation of process parameters were based on 1,000kg ES/day with 50% yield after the calcination process, generating about 475 kg CES/day. The total production cost was RM542,809.82 for producing 148, 675 kg of CES per annum. Based on these values, the cost of CES production per kg was estimated as RM3.58 or 0.76 USD. There is a great potential for CES in the future for the remediation of water and air pollutants

Co-occurrence of trichotillomania and polycystic ovarian syndrome: A case report / Ismaliza Ismail ... [et al.]

Trichotillomania (TTM) or hair pulling disorder is characterized by repetitive pulling of hair on the body whereas Polycystic Ovarian Syndrome (PCOS) is a metabolic-endocrine disorder, manifested by irregular menstrual cycle and clinical hyperandrogenism. Both disorders commonly occur in young females. TTM and PCOS may be related and share the same pathophysiology. We reported a case of a teenager with TTM and PCOS, which were triggered by stress. Neurobiological mechanism may explain the co-occurrences between TTM and PCOS. Further research in the neurobiology of TTM and PCOS may better explain the co- occurrences between the two disorders

Sporadic malignant peripheral nerve sheath tumour in a 3-year-old girl: A diagnostic challenge

Introduction: Malignant peripheral nerve sheath tumour (MPNST) is an uncommon malignant neoplasm of childhood with unfavourable prognosis. Only 1.7% of the cases have been reported in children less than five years of age and approximately one-half arise from a benign peripheral nerve sheath tumour especially in background of neurofibromatosis type 1 (NF1). Primary MPNST in children are even rarer. Case Report: A 3-year-old Malay girl presented with painful right axillary swelling for 6 months duration, initially treated as axillary lymphadenitis and she defaulted follow up. She came back 4 months later with enlargement of the swelling. The biopsy was reported as Schwannoma which correlates with MRI findings of benign peripheral nerve sheath tumour. Final diagnosis after debulking surgery was consistent with MPNST. She succumbed to death 20 months after her initial diagnosis of advanced MPNST and lung metastasis. Pathological findings: Grossly, a huge partlycircumscribed soft tissue mass noted arising from a nerve with solid greyish yellowish myxoid cut surface. Spindle shaped cells arranged in herringbone pattern with marked pleomorphism, brisk mitosis and extensive necrosis are seen microscopically. Immunohistochemistry shows patchy S100 protein staining with loss of expression of H3K27 trimethylation. Conclusion: Although MPNST is rare in paediatric age group, diagnosis should be considered in children without NF1 with rapidly evolving and painful mass in the distribution of a peripheral nerve. In this case, the diagnosis was delayed and made after surgery. Due to its morphologic heterogeneity and lack of specific immunohistochemical markers, MPNST remains a diagnostic challenge

Alpha-Glucosidase Inhibitory and Antioxidant Activity of Solvent Extracts and Fractions of Typha domingensis (Typhaceae) Fruit

Purpose: To identify a solvent fraction with potent antiglucosidase and antioxidant activities from the fruit of Typha domingensis.Methods: Extracts were prepared using hexane, chloroform, ethyl acetate, acetone (AE), methanol, and water. Antiglucosidase and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities of extracts were assessed. The most active extract was partitioned into chloroform, ethyl acetate, butanol (BF) and water, and the antiglucosidase and radical scavenging activities of the fractions were determined. Mode of inhibition of the strongest antiglucosidase fraction was investigated. Polyphenol, coumarin, proanthocyanidin (TPro), and hydroxycinnamic acid contents of the extracts and fractions were evaluated.Results: AE had the highest antiglucosidase (EC50 = 12.36 μg/mL) and radical scavenging (EC50 = 8.57 μg/mL) activities. Solvent-partitioning of AE resulted in BF, which showed markedly stronger antiglucosidase activity (EC50 = 4.27 μg/mL) than quercetin (EC50 = 22.18 μg/mL). BF also had potent radical scavenging activity (EC50 = 7.20 μg/mL). BF was rich in TPro (735.65 mg/g) and was a competitive glucosidase inhibitor. TPro content correlated with antiglucosidase (R2 = 0.709) and DPPH scavenging activities (R2 = 0.838).Conclusion: TPro-rich BF of T. domingensis fruit is a highly potent glucosidase inhibitor and radical scavenger. The findings demonstrate a potential for the development of natural antihyperglycemic agents with antioxidant effect from T. domingensis fruit.Keywords: Typha domingensis, Antiglucosidase, Antioxidant, Proanthocyanidin, Hydroxycinnamic acid, Polyphenol, Coumari

Sporadic malignant peripheral nerve sheath tumour in a 3-year-old girl: A diagnostic challenge

Introduction: Malignant peripheral nerve sheath tumour (MPNST) is an uncommon malignant neoplasm of childhood with unfavourable prognosis. Only 1.7% of the cases have been reported in children less than five years of age and approximately one-half arise from a benign peripheral nerve sheath tumour especially in background of neurofibromatosis type 1 (NF1). Primary MPNST in children are even rarer. Case Report: A 3-year-old Malay girl presented with painful right axillary swelling for 6 months duration, initially treated as axillary lymphadenitis and she defaulted follow up. She came back 4 months later with enlargement of the swelling. The biopsy was reported as Schwannoma which correlates with MRI findings of benign peripheral nerve sheath tumour. Final diagnosis after debulking surgery was consistent with MPNST. She succumbed to death 20 months after her initial diagnosis of advanced MPNST and lung metastasis. Pathological findings: Grossly, a huge partlycircumscribed soft tissue mass noted arising from a nerve with solid greyish yellowish myxoid cut surface. Spindle shaped cells arranged in herringbone pattern with marked pleomorphism, brisk mitosis and extensive necrosis are seen microscopically. Immunohistochemistry shows patchy S100 protein staining with loss of expression of H3K27 trimethylation. Conclusion: Although MPNST is rare in paediatric age group, diagnosis should be considered in children without NF1 with rapidly evolving and painful mass in the distribution of a peripheral nerve. In this case, the diagnosis was delayed and made after surgery. Due to its morphologic heterogeneity and lack of specific immunohistochemical markers, MPNST remains a diagnostic challenge

Surfactant usage in nitrile rubber film development through metal plate dipping process

Developing rubber film in the lab is important for studying the mechanical changes on gloves with different developed formulation. The process in the lab differs from the factory, as the rubber film is formed from dipping a metal plate into the compounded mixture, while the factory uses a well-crafted former to make their gloves in a controlled environment. One issue arises during preparation rubber film in laboratory is the coagulant was unable to uniformly coat the metal plate, which result in producing uneven rubber films. Thus, this work focuses on the incorporation of surfactant into the coagulant solution (Ca(NO3)2) to allow a uniform coating. Two concentrations of two types of surfactants are tested by measuring the contact angle of coagulant to the metal plate. 0.5% of Wetpol 800 surfactant provides an even coating of rubber film on the metal plate after dipping through visual inspection compared to the Ca(NO3)2 alone. The rubber film formed has an average thickness of 0.065 mm, tensile strength of 22.348 MPa, ultimate elongation 1388.4 %, modulus E100 and E300 of 1.377 and 0.731 respectively