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This research investigates the dynamic of sediment deposition in estuaries, focusing on the role of river branching and flow velocity, aspects that have not been comprehensively studied before. The study assesses the variation in sediment deposition characteristics before and after a river branch over a year. Monthly bed sediment samples were taken for a period of one year, which included both the monsoon and dry season and were tested using sieve analysis for sediment classification. Flow velocity, previously modelled using HEC-RAS, was considered when evaluating sediment deposition patterns. Preliminary findings reveal a marked seasonal variation in sediment characteristics. During the monsoon season, sediments upstream of the river branch predominantly comprised medium-to fine-grained material. Conversely, downstream of the river branch, a similar sediment texture was observed primarily during the dry season. It is concluded that while the river branch plays a substantial role in dictating sediment deposition characteristics, the impact of flow velocity must also be acknowledged. This research, therefore, adds a new dimension to the understanding of sediment deposition patterns and characteristics in estuaries, particularly the interactive influence of seasonal variations, river branching and flow velocity. This can have important implications for estuarine ecosystem management and sediment-related hazard prediction. [ABSTRACT FROM AUTHOR]

This research aims to identify the effect of acid attack caused by acid mine water with a pH of 2.65 on geopolymer paste based on CFBC fly ash class F with variations of alkaline activator solutions of 2M, 4M, and 8M. Cylindrical specimens of geopolymer paste were steam cured for 2 hours at 65 degrees Celsius to obtain initial strength at one day. The specimens were then cured under three conditions: acid mine water immersion, tap water immersion, and room temperature. The result shows that CFBC fly ash required more OH-for the geopolymerization reactions, resulting in 8M NaOH increased workability compared to 4M and 2M. However, excessive NaOH results in Na leaking out into the liquid, forming efflorescence on the surface and causing a decrease in compressive strength. The 50% fly ash composition required 8M NaOH to obtain a stable geopolymer paste at three different curing conditions. The interaction of acid mine water for 42 days failed to damage the polysialate bonds in the geopolymeration reaction. Therefore, the CFBC fly ash-based geopolymer paste was proven to resist acid attacks and has potential as a heavy metal adsorbent and pH adjuster in acid mine water. [ABSTRACT FROM AUTHOR]

This article discusses the methods to stabilize potentially liquefied soils in Yogyakarta International Airport (YIA) area. It presents an innovative bio-cementing soil improvement method to increase the shear strength of loose sand in soil conditions with initial salinity content 3.4%. The type of bacteria chosen was Bacillus sp, which can survive in salinity and aerobic conditions and precipitate microbial-induced calcium carbonate (MICP). This improvement was realized by mixing loose sand with fly ash as a source of Calcium (Ca) and microbial fluids. The aim of this article is to investigate the performance and mechanism of MICP in the binding process between loose sand particles by optimizing the percentage of fly ash and microbial in salinity conditions. During the MICP process, microbes require Ca2+ ions obtained from fly ash, which contains SiO2 and CaO to generate CaCO3 for the bonding process between particles. The percentage of fly ash used, loose sand moisture content, and curing time were examined to identify an increase in the shear strength value of the sample. The results showed that the shear strength of the samples treated with the addition of microbial fluid and a 35% fly ash mixture under salinity conditions exhibited a significant increase compared to other combinations. This indicated that the addition of 35% fly ash and 0.2 mL of microbial liquid can result in a shear strength of 78.08ᵒ, cohesion of 0.18 gr/cm3, and an increase in grain dimensions due to bonding between particles as observed in the results of the sieve analysis after a curing time of 28 days. Furthermore, the MICP mechanism, including the interaction of bacteria, fly ash, and sand in binding soil particles with the production of CaCO3, was observed using a digital microscope and scanning electron microscope based on the results of XRD and SEM. [ABSTRACT FROM AUTHOR]

Sepuluh Nopember Institute of Technology (ITS) has 4 canteens that are managed by the ITS Public Facilities Unit to fulfill the food and drink needs of students, lecturers, and other employees. There are Biology canteen, Information System canteen, Geomatics Engineering canteen, and Central canteen that have many foods and beverages stalls. To ensure the quality of food in the canteen, the quality of the foods’ raw materials will be tested. Some parameters tested are free fatty acid value analysis (FFA), peroxide value analysis (PY), and formaldehyde qualitative test. The analysis results are compared with the national standards (SNI 01-3741-2013). From 28 stalls that were sampled, only 9 stalls passed the test. Later, the stalls that passed the test has been labeled Healty Food Stalls Built By LPPM ITS (Warung Sehat Binaan LPPM ITS) in the form of stickers and those who have not passed will be given training in how to process healthy food and retest after training. [ABSTRACT FROM AUTHOR]

The existence of which is traversed by world plate meeting brings Indonesia in earthquake prone area. One of the dangers that occur in earthquake is soil liquefaction. At the time of the earthquake occurs, the soil changes the nature of solid into liquid due to the received cyclic load. As a result, the non-cohesive soil will lose its power. The consequence of soil liquefaction is the decline of the building. Measurement of soil strength and identification of soil type can be done by using the Cone Penetration Test (CPT). In this study, CPT measurement was used to evaluate the liquefaction potential of Puger coastal area, Jember Regency. The potential of liquefaction is determined by obtaining the value of Cyclic Resistance Ratio (CRR), Cyclic Stress Ratio (CSR), Safe Factor (SF) and subsequently calculating ground settlement due to soil liquefaction. As for the results of measurements on 13 points, 7 points of them have the potential for soil liquefaction. From those points, the largest ground settlement is up to 3.24 cm, hence based on the degree of damage to buildings developed by Ishihara and Yosimine [1], the category is included as minor damage. [ABSTRACT FROM AUTHOR]