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The emergence of many new diseases due to viruses and bacteria demands for an increase in the discovery of natural alternative medicines. One example of sources of natural medicine is the honey and the propolis of Tetragonula laeviceps bee. The efficacy, physical and chemical properties of honey are known to be influenced by the type of pollen and the environment whilst the composition of propolis is influenced by the geological factors. Therefore, the purpose of this research was to study the composition of propolis’ bioactive compounds of T.laeviceps bee from Mount Merapi Slope, Sleman, Yogyakarta. The bioactive compound composition of the propolis sample were analysed by Gas Chromatograph-Mass Spectrometry (GC-MS). The analysis showed that the propolis has various type of compounds containing up to 20 bioactive compounds which can be classified in three different groups namely alkaloids (70%), phenolics (20%), and terpenoids (5%). Most of these compounds were found to be biologically important. However, further research is still required to confirm the potential antimicrobial properties of the propolis’ bioactive compounds.

Composite body armor has widely used as bulletproof material combined with hard plates made from ceramic or metals. That replaced the use of full-metals body armor that heavy, rigid, and restricts the user's movement. This study investigates the ballistic performance of SiC-based hard layer body armor on its possible impact position using finite element analysis. The body armor panel consists both of soft and hard layers. The soft layer is made from epoxy-ramie composite which is a natural fiber composite. The hard layer made from hexagonal chip l SiC with 4 mm thickness in an array. There are three possible impact points on the chip which are the center of the chip, between two chips, and between three chips. The soft layer is varied at a range of 6-25 mm depending on its capability to comply with the latest NIJ 0101.07-2019 criteria for RF1. NIJ has several criteria for ballistic performance. This paper discusses panel penetration and Back-face Deformation (BFD) based NIJ. Besides, this paper also discusses the impact of energy absorption and velocity reduction of the bullet by the panel.

This study uses an experimental approach to illustrate the significance of particle size and alkali-treated on the sound absorption coefficient of oil palm frond (OPF) particleboard. Two variables were investigated: Particle size and one hour of NaOH treatment of oil palm frond. The particleboard was manufactured based on OPF material with 10% urea-formaldehyde as the binder and 1% NHCl4 as the hardener. The mixing of OPF with UF was pressed under hot-pressing of 9 tons at 140°C for 5 minutes to obtain OPF particleboard. 100 mm and 29 mm diameter of OPF particleboard were fabricated with three different particle sizes in the constant density of 0.4 g/cm3 and thickness of 10mm. Three particle sizes were fine, medium, and coarse particle sizes with a diameter of 0.2-0.6, 1-2, 2.4-4.8 mm, respectively. The SAC was determined using a two-microphone impedance tube following ASTM E 1050 at frequencies 50 to 6400 Hz. The single rate number, noise reduction coefficient (NRC), the mean of arithmetical values for the SAC at four-octave bands frequency (250, 500, 1000, and 2000), was determined. The data from experimental and calculation were obtained and investigated.

This study aims to investigate the capability of sound absorption coefficient (SAC) of oil palm frond (OPF) composite. Also, to characterize the fiber surface without treatment and with alkali treatment. Two parameters were formulated to characterize the SAC ability of the OPF composite: chemical treatment and density of composite. The composite was manufactured from a waste OPF as a reinforcement and urea-formaldehyde (UF) resin as a matrix. The fibers were blended with UF 10% (weight fraction) and formed by hot-pressing under the pressure of 9 tons at 140°C for 5mn. The SAC was measured by the impedance tube respected with ASTM 1050 (the transfer function method) within the frequency of 125-6400 Hz. Morphological analysis is investigated by scanning electron microscopy (SEM) on untreated and alkali-treated OPF fiber. The measurement data were obtained and compared with different densities and treatments. It reveals that the SAC of OPF composite was proportion to density and alkali-treated. The SAC worsens as the composite becomes dense due to the greater density. The treated fibers have more roughness and friction area than untreated fiber; thereby, the incidence of sound energy rapidly dissipates to thermal energy, causing improved SAC performance