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Coating film thickness is one of many important aspects in the development of Quartz Crystal Microbalance (QCM) for chemical sensors and biosensors. The coating layer is utilized as a matrix layer for the bio-sensitive molecule or as a sensitive layer. Also, the coating thickness is an important physical parameter, which determines the sensitivity and stability of the QCM sensor. Commonly for the thin film or glassy film, the Sauerbrey equation was used to calculate the film thickness. However, the method is inaccurate for a rubbery film. In this study, a non-destructive method was developed to measure the thickness of a transparent layer deposited on QCM using the interferometry method. This interferometry method uses the principle of coherent light interference between the initial laser beam and the one that has passed through a transparent layer. In this work polystyrene film which is known as a glassy film was used. The results of this study show that the interferometry method can be used to measure the thickness of the polystyrene layer deposited on the QCM sensor, as a non-destructive measurement method. These results are validated by calculations from the Sauerbrey equation, in calculating the thickness of polystyrene-based on changes in the frequency of the QCM sensor, which is 0.421 micrometers.

This study was aimed to determine the viability of Lactobacillus plantarum and Lactobacillus pentosus isolated from soy milk waste as a candidate for poultry probiotics in vitro. This research was designed in the form of a laboratory experiment descriptively. This study was conducted in several stages, viability test at 37°C and 42°C, viability test at pH 2 and 7, viability test for 0.3% and 0.5% bile salts, viability test of adhesion [hydrophobicity] and antimicrobial activity against pathogenic bacteria [Escherichia coli 0157, Staphylococcus aureusATCC-25293 and Salmonella sp]. The result showed that Lactobacillus plantarum and Lactobacillus pentosus survived and grew at 37°C and 42°C [observation time at 30 and 60 minutes], pH 2, and resistant for 0.3% and 0.5% bile salts. Both bacteria also could inhibit the growth of pathogenic bacteria [active category], which produced clear zones with diameters Lactobacillus plantarum and Lactobacillus pentosus isolated from soy milk waste have potential as a probiotic for poultry.

One of the artisanal mining locations in West Nusa Tenggara Province is Pelangan Village, Sekotong Sub-district, West Lombok District. There are two main activities in the artisanal mine site, namely mining operations and material processing, that commonly use logs and mercury (Hg). This study aims to determine the effect of differences in log spacing from mercury content in well water at Pelangan Village, Sekotong Sub-district. This study uses the Cross-Sectional research method to obtain an overview of mercury levels in the Pelangan Village of Sekotong Sub-district based on distance and to determine the differences in variables using Chi-Square statistical test. The results showed that 46 water wells had mercury levels less than 0.001 mg/l and 8 water wells had mercury levels more than 0.001 mg/l. From the results of chi-square analysis, the Pearson Chi-Square value was 6.541 with df = 1 and a significant value less than 0.05. The Chi-Square value concluded that there is an effect between the distance of the log and the mercury content of the community water well. To avoid the mercury pollution, three strategies should be applied including distance of water well from the pollution source should bigger than 95 meters, the best distance, and replacing mercury with something that more environmentally friendly.

Aluminium nanoparticles (Al NPs) have been synthesized using electrochemical method. The synthesis was conducted by electrolysis of aluminium metal in a sodium citrate solution as an electrolyte solution. Formation of Al NPs was investigated on the variation of potential (5-50 V), concentration of electrolyte solution (0.02-0.42 M), and electrolysis time (15-75 minutes). The obtained product was characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray (EDX), and UV-Vis Spectrophotometer. XRD pattern indicate that the obtained product was aluminium nanoparticles. The result show that the size of Al NPs were 56-63 nm with the Al compositions of 7.08%. The optimum condition was reached at 40 V with 0.18 M sodium citrate solution during 45 minutes electrolysis process. The plasmon band peak was found at 234 nm. In this condition Al Nps is more stable.

The mineral iron oxide is the main component of sand iron that are abundant in nature. Mineral iron oxide not yet widely applied into more useful products. The main component of iron ore is magnetite. Magnetite can be used as a basic ingredient in the manufacture of magnetite-modified silica adsorbent sulfonate. In this research, the adsorbent made from sulfonic functionalized silica-coated magnetic particle has been successfully produced, with the magnetite was obtained from iron sand at Marina Beach, Semarang Indonesia. This adsorbent was then used as a metal ion preconcentration media. From the research that it was found that the sulfonic has been bound to the silica marked by the emergence of element S on EDX. Whilst, the evidence that silica has coated on the magnetite could be seen from the SEM images which showed the morphology of sulfonic functionalized silica-coated magnetic particles were larger than the sulfonic functionalized silica without magnetite. From the DSC results showed that the addition of magnetite on sulfonic functionalized silica did not change the heat resistance of the sulfonic functionalized silica. Based on the XRD patterns show that magnetite sulfonate silica was formed.