Effects of vertical confinement on gelation and sedimentation of colloids

We consider the sedimentation of a colloidal gel under confinement in the direction of gravity. The confinement allows us to compare directly experiments and computer simulations, for the same system size in the vertical direction. The confinement also leads to qualitatively different behaviour compared to bulk systems: in large systems gelation suppresses sedimentation, but for small systems sedimentation is enhanced relative to non-gelling suspensions, although the rate of sedimentation is reduced when the strength of the attraction between the colloids is strong. We map interaction parameters between a model experimental system (observed in real space) and computer simulations. Remarkably, we find that when simulating the system using Brownian dynamics in which hydrodynamic interactions between the particles are neglected, we find that sedimentation occurs on the same timescale as the experiments, however the thickness of the "arms" of the gel is rather larger in the experiments, compared with the simulations. An analysis of local structure in the simulations showed similar behaviour to gelation in the absence of gravity

The recovery of microplastics from rock oysters using digestion method

The widespread deposition of microplastics (<5.0 mm) in the marine environment have appeared to be pervasive across the globe. It has led to major attention of many researchers to study this problem. Despite the amount of work conducted to understand these infamous microplastics, there is still no standard procedure for microplastics extraction from marine organism samples. This study investigated three types of digestion treatments; (1) KOH, (2) KOH/H2O2, and (3) KOH/NaClO, followed by density separation using 50% KI to extract the spiked microplastics from the rock oyster. Each treatment was tested to study the digestion effectiveness of the organic soft tissue materials while preserving the microplastic particles. Aside from recovering the spiked microplastics, other small contaminants have been detected in each treatment. All the spiked microplastics and the contaminants obtained were analysed using microscope and FTIR for characterisation. From this study, it was observed that each treatment resulted in high microplastics recovery. Among the three treatments, using 10% KOH alone provided the highest digestion rate, but it required more time to digest the oyster soft tissue. The contaminants detected in the oyster suggested the possibility of microplastics accumulation in non-digestion organs through adherence

Financial network (FiNe): a web application to assist investors in avoiding herding behaviour in stock market

Herding behaviour is one of the behavioural phenomena that can be observed among investors in the financial markets. Generally, investors feel more secure if they copy and follow other investors. Regardless of the market's performance, Investors are focused on their own personal and confidential information, rather than relying on publicly available market data. During market stress, herding will be more common. Investors herding together would cause market imbalances and stock prices may deviate from their fundamental values as a result of the herding phenomenon. To avoid herding behaviour among investors, a web application of financial network (FiNe) is developed to assist investors in making informed decisions quickly in order to select stocks for their portfolios based on their own analyses rather than solely relying on what other investors are doing. FiNe application displays an interactive financial network that visualizes the relationship between stocks in which the input is based on closing prices of stocks. In addition, it is also able to display financial networks for different filters such as duration and sectorial basis. With the relationships between stocks displayed in the network, investors are able to run a quick analysis and financial information on stocks for portfolio selection

The evaluation of amine-functionalized iron oxide Nnanoparticles as potential dye removal from aqueous medium

Magnetic nanoparticles (MNP) are superparamagnetic nanoparticles that are gaining significant interests due to their high surface-to-volume ratio and unique physicochemical properties. However, anisotropic dipolar attraction may cause the MNP to aggregate and undergo biodegradation when their surfaces are exposed directly to biological environment MNP (Souza et al., 2013)⁠⁠. This can be overcome by encapsulating the MNP with biocompatible and stabilizer shell using polymers or inorganic compounds (Mourdikoudis et al., 2021)⁠⁠. In this work, amine-functionalized iron oxide (Fe3O4) magnetic nanoparticles (MNP) were synthesized using a facile one-pot method in Teflon-lined stainless steel autoclave. In this work, we ran the reaction for 6 hours at 150ºC and 200ºC, respectively. The temperatures were varied to investigate their effects on the physicochemical properties of MNP. The morphology and size of the amine-functionalized MNP, and their functional groups were investigated using transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The synthesis reaction that was carried out for 6 hours at 150ºC produced brown precipitate indicating incomplete Fe3O4 formation (Songvorawit et al., 2011)⁠⁠. On the other hand, after 6 hours of reaction at 200ºC, black precipitate of Fe3O4 was obtained. Based on the FTIR results, significant peaks at 600-560 cm-1 representing Fe-O functional groups were absent for products from 150ºC but can be clearly observed for 200ºC product. Similarly, significant peaks at ~1600 cm-1 were observed for the 200ºC product indicating amine-functionalized MNP (A-MNP). In summary, this work showed a facile technique for the synthesis of amine-functionalized MNP by a solvothermal process using one-pot method and an autoclave as the reactor. The reaction time and temperature play important roles in determining the formation of amine-functionalized MNP. Preliminary results have shown that A-MNP have the potential to be utilized as dye adsorbents from aqueous medium

Microplastics contamination in bivalves off the island in the strait of malacca and its potential health risks

The widespread presence of microplastics in the ocean is a significant threat to marine life and humans. A study was conducted to investigate the extent of microplastic contamination in the coastal waters of Langkawi and Penang, situated on the northern coast of Peninsular Malaysia. Rock oysters (Saccostrea cucullata) were utilized as bioindicators due to its availability in all sampling sites to evaluate microplastics,by considering its abundance, types, polymer composition, and potential health risks related to consumption. Soft tissues were digested with 10% KOH, and the resulting microplastics were examined using a stereo microscope and microplastics polymer were identified through ATR-FTIR. Kok Beach and Penarak Beach exhibited notably higher microplastic abundance, mainly in the form of filaments with predominant black and red colours. The most common polymer types were cellulose triacetate (CTA) and polycyclohexanedimethylene terephthalate (PCT). Hazard Quotient values, indicating potential health risks from consuming S. cucullata, surpassed a critical threshold at all locations. The study's findings suggest that it serves as a fundamental reference for future research on microplastic contamination in the islands along the northern coast of Peninsular Malaysia

Microplastics impact assessment on Langkawi Island off Strait of Malacca waters using rock oyster as bioindicator

Microplastics (MPs) assessment was conducted in five sites along Langkawi Island off Strait of Malacca coastal shoreline. In this paper, an improved protocol of digestion for soft tissue digestion and multi-steps of MPs identification had been developed and the polymer identification of MPs are performed by ATR-FTIR. Number of MPs found varied from 0.47 to 1.0 items/w. weight (g) and 0.73 to 1.47 items/individual of rock oysters. The MPs composition was dominated by threadlike shapes and the color found are black, blue, red, grey, and yellow. Size of MPs ranging between 500 to 1000μm and based on MPs polymer analysis, polymers identified are PVDF, PP and PET. The overall abundancy of MPs in bivalve found in Langkawi is 1.46 ± 0.007 items/w. weight (g), however, it is still necessary to do periodic monitoring in this tourists’ attraction island that is well-known for seafood

Local structural changes in colloid-polymer mixture: colloids as atomic model

Colloidal suspension undergoes phase transition: gas, liquid and crystal states, as was observed in the phase diagram of argon atoms. Linked by these similarities, colloids have often been used as atomic models and have been given the term “designer atoms”1. The addition of polymer induces aggregation in colloidal dispersion by creating attractive interaction potential between the colloids. The addition of polymer to colloidal suspensions will cause the colloidal particles to aggregate at low volume fraction, φ2-5 forming a gel. The arrested behaviour in gels due to the polymer addition is analogous to colloidal suspensions quenching. The colloid-polymer mixture can be considered as one component system where the effective interaction is mediated by the polymer according to Asakura and Oosawa6,7 and Vrij8. In our work, we employed a well understood colloid-polymer system in order to investigate the local structural changes in reaching equilibrium ordered state. We studied the ageing of gels with different interaction strengths in experiment and simulation. Then, we also examined the effects of confinement to the sedimentation of colloids and gels. We have investigated the local structures evolution within the far from equilibrium state of gel using a confocal microscope