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In this study, we report about the characteristics of ion transport of chitosan composite membranes "chitosan-silver nanoparticle". The chitosan composite membranes were prepared by a casting method using chitosan as a matrix, silver nanoparticle (AgNP) as filler, and acetic acid 1% as a solvent. The various amount of filler added e.g. 10, 100, 250, 500, 750, and 1000 ug. These membranes called chitosan composite membrane Ch-AgNP10, Ch-AgNP100, Ch-AgNP250, Ch-AgNP500, Ch-AgNP750, and Ch-AgNP1000. A membrane without AgNP has also been prepared named chitosan membrane (Ch membrane) as a comparison. The ion transport experiments conducted by using a cell model consisting of two chambers, chamber 1 and 2, and the area of the membrane was 9.616 cm2. The driving force used is a gradient concentration (dC/dx). The electrolyte solutions used were KCl and CaCl2 with concentrations of 0.1, 1, 10, 100, 250, 500, 750, and 1000 mM. The voltage difference (V) is measured using Ag/AgCl electrodes which connected to a voltmeter. All measurements were done at room temperature, 28.1degC. The result showed that the obtained Jdiff -V curves of chitosan composite membranes are similar to Jdiff -V curves of Ch membrane, where the diffusion current densities of chitosan composite membranes increased with increasing the concentration gradient of solution. It also depends on the electrolyte solutions. The diffusion current density of chitosan composite membranes had affected by the amount of AgNP added that is increased as increasing the mass of AgNP added.

This study reported the potency of 'biologically synthesized silver nanoparticles using Andrographis paniculata extract' (S-AgNp) as an antibacterial agent and its minimum inhibitory concentration (MIC). The antibacterial test was conducted to pathogenic bacteria of S. aureus and E. coli by using a diffusion-well method. The media used were Nutrient Agar (NA) and Nutrient Broth (NB). The tests were carried out in two steps. The first step was determining the potency of S-AgNp as an antibacterial agent. This step used S-AgNp with the concentration of 100%, Andrographis paniculata extract and AgNO3 solution as a positive control, and distilled water as negative control. It was found that S-AgNp were able to inhibit the growth of both bacteria. The second step was finding out the MIC of S-AgNp to both bacteria. In this step, the concentration of S-AgNp tested from 70% to 10% and amoxicillin of 5% was used as the positive control. It was found that the antibacterial activity on both bacteria increased as increasing the concentration of S-AgNp tested. The growth inhibition of S. aureus was greater than that of E. coli (p < 0.05). The MIC value of both bacteria was 0.0005 g/mL. Based on this result, it is concluded that S-AgNp has a potency to be used as an antibacterial agent, especially for S. aureus.

Under the existing regulation in Constitution Number 22 Year 2001 (UU No 22 Tahun 2001), Production Sharing Contract (PSC) continues to be the scenario in conducting oil and gas upstream mining activities as the previous regulation (UU No. 8 Tahun 1971). Because of the high costs and risks in upstream mining activities, the contractors are dominated by foreign companies, meanwhile National Oil Company (NOC) doesn't act much. The domination of foreign contractor companies also warned Indonesia in several issues addressing to energy independence and energy security. Therefore, to achieve the goals of energy which is independence and security, there need to be a revision in upstream oil activities regulating scenario. The scenarios will be comparing the current scenario, which is PSC, with the "full concession" scenario for National Oil Company (NOC) in managing oil upstream mining activities. Both scenario will be modelled using System Dynamics methodology and assessed furthermore using financial valuation method of income approach. Under the 2 scenarios, the author will compare which scenario is better for upstream oil management in reaching the goals mentioned before and more profitable in financial aspect. From the simulation, it is gathered that concession scenario offers better option than PSC in reaching energy independence and energy security.