Search

This study investigated the effects of drying methods on the yield, bioactive compounds, and antibacterial activity of amla extract. Fresh amla was oven-dried and sun-dried at different temperatures and ground into powder. Bioactive compounds were extracted from amla using maceration with ethanol as a solvent. The amla extract was used for the antibacterial susceptibility test using the agar disc diffusion method. The yield of amla extract increased with increasing drying temperature. The highest yield (53.47%) was obtained at a drying temperature of 70 °C. Fourier Transform Infrared (FTIR) analysis confirmed that sun-drying and oven-drying exhibited no qualitative effect on the bioactive compound in amla extract. FTIR analysis also indicated that amla extract contains bioactive compounds, validated by phytochemical analysis. The antibacterial activity of oven-dried samples at 40 °C produced the largest inhibition zone (24.57 mm) compared to sun-drying and oven-drying at other temperatures. It can be concluded that drying temperature, especially higher temperatures, had a significant impact on the antibacterial activity of amla as its active components degraded. [ABSTRACT FROM AUTHOR]

In addition to giving a pleasant scent, essential oils in hand sanitizer formulation could contribute to the increase on its efficacy. Herein, we aimed to evaluate the antioxidant, antibacterial, as well as antiviral activities of eucalyptus oil (EO) and patchouli oil (PO), followed by their application in hand sanitizer formulation. Essential oils were obtained from a simple distillation and followed by fractionation using a rotary evaporator. Antioxidant activities of the essential oils were determined based on a DPPH scavenging assay. The antibacterial activities against Staphylococcus aureus as well as Escherichia coli were evaluated under the Kirby-Bauer method. The antiviral activities of EO and PO were based on the replication inhibition of Simian retrovirus-2 (SRV-2) in an A549 cells model. Our data suggest that the fractionation increases the purity of EO and PO based on the content of 1,8-cineole (from 54.08% to 85.05%) and patchouli alcohol (from 29.28% to 85.01%), respectively. IC50 values of fractionated EO and PO in DPPH scavenging activity were 131.21 and 118.20 ppm, categorized as moderately active antioxidants. The optimum inhibition zones against S. aureus along with E. coli were achieved by fractionated EO (10.49 and 15.79 mm, respectively). SRV-2 replication could be effectively attenuated even until day-7 post-infection. When applied in hand sanitizer formulation (in a small amount), only antibacterial activity against E. coli was found higher as compared with usual hand sanitizer. Moreover, in hand sanitizer formulation, the efficacy of antiviral activity against SRV-2 was reduced to only last for 5 days post-infection. EO and PO can be used as active ingredients in hand sanitizer formulation owing to their antibacterial, antiviral, and antioxidant activities. [ABSTRACT FROM AUTHOR]

The demand for bio-degradable lubricants has been increasing nowadays due to concerns on pollution free environment. Vegetable oil-based lubricant is one of promising sources of lubricant that can fulfill the requirement, especially when combined with eco-friendly nanomaterial additives. On the other hand, tribo-layer formation as the mechanism of friction and wear reduction in a tribo-pair has been generally accepted in tribology field. The tribo-layer layer can be formed due to the tribochemical reaction during friction process and its formation can be enhanced with incorporation of nanomaterials as additive. In this study, the tribo-layer characteristics formed on self-mated AISI52100 contact pair were investigated. The contact pair were lubricated by two kind of lubricant's specimens, i.e. palm methyl ester (PME) and palm methyl ester containing graphene nanosheet additive. It is found that in the case of palm methyl ester without graphene additive, the tribo-layer comprises oxidative layer of Fe and O elements. With the presence of graphene nanosheets in the lubricant, the tribo-layer was formed in a comparatively wider contact area. Carbon element was more observable in the layer besides oxygen, emphasizing the role of graphene nanoparticles. In both cases, the friction coefficient and wear are relatively similar. [ABSTRACT FROM AUTHOR]

The current development of the packaging industry is increasing as well as the dependence of non-renewable oil-based materials encouraging researchers to look for alternative polymeric strengthening materials from biomass. Especially used from agricultural waste because it is cheap and widely available in nature and it can be renewed. In this study, agriculture waste used were rice husk and rice husks ash that prepared as organic nanofillers for the development of polymer nanocomposites. XRF analysis showed that rice husk ash has the highest silica (SiO2) content of 89. 835%, while rice husk has SiO2 contents of 82.540%. From XRD analysis on 2 theta there is a crystalline silica region at 22° and this analysis shows the sample is amorphous. FTIR analysis showed Si-H at peak 2339 cm−1 in rice husk and 2129 cm−1 for rice husk ash.

Synthesis of palm oil-based polyurethane (PU) and the formation of nanocomposite from a mixture of PU with clay filler has been performed. Polyol which is the basic material of PU is formed by epoxidation and hydroxylation process and then mixed with isocyanate. Clay used as filler in this study was obtained from the local area of North Aceh, which is a type of swelling of clay that has been modified with cetyltrimethyl ammonium bromide surfactant. Nanocomposites are formed from PU with clay fill variations of 3%, 5%, and 8% by weight of the total mixture of 40 g. The resulting material is tested in character by some type of characterization. Based on the test results with Fourier transform infrared spectroscopy, the hydroxyl polyol group was obtained in groups of 3390.870 (O-H) and -NH as the PU microdomain structure was obtained at a wavelength of 2987 cm-1. Morphological test results using scanning electron microscopy revealed that the addition of modified clay increases the adhesion in the paint and PU coatings and also increases the gloss from the surface and homogeneous material. The thermal endurance test with thermogravimetric analysis reported that the addition of clay fillers in PU showed enhanced effects for better thermal stability in nanocomposite materials when compared with neat polymers. Samples of PU/clay nanocomposites with the addition of 8 wt% clay filler were the most optimum composites among other variations with the thermal degradation temperature value of 296°C. This research generates prospects for applying various industrial surface coatings that are resistant to corrosion and heat, have good mechanical properties, and are more environmentally friendly. [ABSTRACT FROM AUTHOR]

Magnesium-based hydrogen storage alloy is one of the most attractive hydrogen storage materials for fuel cell-powered vehicle application. However, a high desorption temperature and slow kinetics limit its practical application. Extensive efforts are required to overcome these problems, one of which is inserting a metal oxide catalyst. In this work, we reported the current progress of using nano-silica (SiO2) as a catalyst to improve the thermodynamics and kinetics of magnesium hydride (MgH2). Nano-SiO2 was extracted from local rice husk ash (RHA) using the co-precipitation method. Then, the MgH2 was catalyzed with a small amount of nano-SiO2 (1 wt%, 3 wt%, and 5 wt%) and prepared using a high-energy milling technique. The microstructure and hydrogen desorption performance were studied using x-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The results of the XRD test showed that the milling process over 5 h reduced the material to a nanometer scale. Then, SEM images showed that the powders were agglomerated after 5 h of milling. Furthermore, it was also found that nano-SiO2 reduced the hydrogen desorption temperature of MgH2 to 338°C in 14.75 min when the 5 wt% variation of the catalyst was applied. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine the effect of organic loading on the change of produced methane biogas and some wastewater parameters (i.e., pH, COD, MLSS, MLVSS, and ammonia) of the thermophilic stirred anaerobic reactor in treating tofu wastewater. The composition of the biogas produced was also measured. The reactor was studied at different organic loadings ranging from 65 to 162.5 g COD. The temperature in the reactor was maintained at 55oC. In general, the reactor showed a good performance in utilizing tofu waste, producing significant amount of methane biogas. The production of biogas changes with the change of organic loading rates. The biogas comprised methane (79.5%), CO2 (20%), and CO (0.5%). Based on the results of the analysis, since there were no corrosive materials, the biogas produced could be used directly for electricity or to power a generator. Other parameters such as pH, COD, MLSS, MLVSS, and NH3-N were changed during the process. [ABSTRACT FROM AUTHOR]