Polyelectrolyte complexes (PECs) are attractive materials for drug delivery application as they offer simple preparations and high drug-loading efficiency. In this study, a novel method for preparing polyelectrolyte complex nanoparticles using a simple mixing method of chitosan and poly-2-acrylamido-2-methylpropane sulfonic acid (PAMPS) solutions is presented. The effect of chitosan concentrations was examined by fixing the PAMPS concentration at 0.01 %w/v, while chitosan concentrations were varied from 0.01 to 0.05 %w/v. Based on dynamic light scattering (DLS) and zeta sizer results, increasing the chitosan concentration led to increased average PEC particle sizes with broader particle distributions from 249.1 (polydispersity index/PDI 0.13) to 318.2 nm (PDI 0.19) and changed the particle surface charges from -5.85±0.34 to 11.95±0.84 mV. The addition of glutaraldehyde (GA) followed by dialysis eliminated sodium chloride (NaCl) and produced spherical PEC nanoparticles, confirmed via scanning electron microscopy (SEM) results. Among those samples, PECs with a chitosan concentration of 0.01 %w/v are the most promising drug carrier materials due to their negative surface charges, which promote prolonged circulation time in the bloodstream.

In 2015, a joint collaboration project to build a new observatory in Mount Timau, East Nusa Tenggara was initiated between LAPAN, ITB, UNDANA, Kupang Regency and East Nusa Tenggara governments. The site selection is based on preliminary studies conducted on nearby location. This paper presents in situ measurements report on seeing, weather and sky brightness obtained on July 2018 using Differential Image Motion Monitor (DIMM) with 20 cm-telescope, Davis Vantage Vue automatic weather station, and Sky Quality Meter, respectively. Despite the high humidity and foggy condition on the afternoon, the site has good seeing condition with median of 0.93 arcsecond and sky brightness around 22.18 magnitude per arcsecond square after midnight.

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Fabrication process determines the composite quality. Conventional method such as dry- and hand lay-up are commonly used. Dry lay-up method has known to be more controllable and produce less defect composites with good mechanical property. However, this method is more expensive. On the other hand, hand lay-up which is more simple and less expensive, is uncontrollable as well as produces more defect and poorer mechanical properties of composites. In this study, we creates instrument which is able to control wet lay-up fabrication process of Fiber Reinforced Composite Material (FRCM). Instead of using uncontrollable human hands, this instrument utilizes speed controllable paint roller which distributes the resin though all matrix. The result shows that the produced composites have more homogenous resin distribution, smaller size defects, and exhibits stronger mechanical properties compare to the one produced by hand lay-up method. This study is expected to open further innovations on low cost composite fabrication.