SummaryThe effects of the addition of fibres of bacterial cellulose (FBC) to commercial starch of Mater-Bi® have been investigated. FBC produced by cultivating Acetobacter xylinum for 21 days in glucose-based medium were purified by sodium hydroxide 2.5 wt % and sodium hypochlorite 2.5 wt % overnight, consecutively. To obtain water-free BC nanofibres, the pellicles were freeze dried at a pressure of 130 mbar at a cooling rate of 10 °C min−1. Both Mater-Bi and FBC were blended by using a mini twin-screw extruder at 160 °C for 10 min at a rotor speed of 50 rpm. Tensile tests were performed according to ASTM D638 to measure the Young’s modulus, tensile strength and elongation at break. A field emission scanning electron microscope was used to observe the morphology at an accelerating voltage of 10 kV. The crystallinity (T c) and melting temperature (T m) were measured by DSC. Results showed a significant improvement in mechanical and thermal properties in accordance with the addition of FBC into Mater-Bi. FBC is easily incorporated in Mater-Bi matrix and produces homogeneous Mater-Bi/FBC composite. The crystallinity of the Mater-Bi/FBC composites decrease in relation to the increase in the volume fraction of FBC.

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Province of North Sumatera has been well known as a territory having multi kind of industrial minerals which have not been used and maintained properly and optimally. One of which is a natural Pahae zeolite derived from Tarutung, Tapanuli Utara-Indonesia. The objective of this research is to exploit Pahae zeolite to absorb water molecules flowing into the combustion chamber of a hydrogen fueled motorcycle. The generation of water molecules was as a result of water splitting process in water to hydrogen converter of the motorcycle. The grain size of Pahae zeolite was lessened up to 60 and 200 meshes which were then chemically activated by soaking with 30% KOH solution and calcination at a temperature of 300°C for 2 hours. The test results conducted on the intake pipe of combustion chamber showed that the particle size of 200 meshes had more absorption than that of 60 meshes. It was also found that type of Pahae zeolite had better absorption compared with Cikalong zeolite.

Research on antimicrobial and toxicity tests of flavonoid total Dendrophthoe pentandra (L) Miq from false ashoke tree (Polyalthia longifolia) have been done. This study aims to determine the activity of toxicity of total flavonoid of Dendrophthoe pentandra (L) Miq as mistletoe of false ashoke tree (P. longifolia) based on Brine Shrimp Lethality Test (BSLT) method using Artemia salina Leach shrimp larvae obtained Lethal Concentration (LC 50) of 30.06 mg / L which means strong toxic activity. Antimicrobial test of flavonoid total has used the diffusion method in order to obtain the inhibit zone diameter on Streptococcus mutans at the total flavonoids concentration of 3%, 6% and 9% were 6; 9 and 17.25 mm, in Escherichia coli is 3.55; 4.25 and 9.15 mm and at Candida albicans is 8.30; 4 and 5.30 mm where S. mutans and E. coli are greater but C. albicans less affect but still have good inhibitory activity so effective to be developed as antimicrobial agents.

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