The objective of this study was to elucidate the role of microbial cell-to-cell communication through quorum sensing (QS) mechanisms on bioflocs characteristics and functionality in aquaculture systems. This study comprised of four experimental stages, i.e. (1) inhibition of microbial aggregation and its effect on biofloc characteristics, (2) the effect of QS signal molecules addition on bioflocs characteristics and functions, (3) the effect of a QS signal molecule addition on bioflocs consumption by African catfish juvenile, and (4) quantification of QS molecule in a biofloc-based African catfish culture. For experiment one to three, bioflocs suspension was obtained from a biofloc sequencing batch reactor with a hydraulic retention time of 24 h using N-NH4Cl as the nitrogen source. Vanillin was used as a quorum sensing inhibitor in the first experiment to demonstrate the effect of a QS inhibitor on the formation of microbial aggregates in bioflocs and biofloc characteristics. The addition of vanillin at 0.30 mg/ L significantly reduced microbioal aggregation, particle size and protein content of bioflocs. On the other hand, adding QS signal molecules significantly enhanced the protein content and the physical characteristics of bioflocs, as indicated by the increase in total suspended solids, floc volume, floc volume index and bioflocs particle size. Interestingly the addition of QS signal molecules notably increased the total ammoniacal nitrogen removal capacity of biofloc resuspension and the consumption of bioflocs by African catfish juveniles to almost double. The assessment of QS signal concentration in bioflocs pellet collected from biofloc-based African catfish production units at different culture age by using Chromobacterium violaceum 026 demonstrated that the concentrations of QS signals molecules increased with the increase of the culture age. In conclusion, the results of the present study clearly demonstrated that microbial quorum sensing plays some important roles in bioflocs characteristics and functionality in aquaculture systems.
Putat plant (Planchonia valida) is a medicinal plant that grows in Mahulu, East Kalimantan. Empirically putat leaves are used to treat skin diseases and reduce black spots on the face. Characterization is the initial stage to determine the quality of an extract. Non-experimental research was conducted to determine the specific and non-specific characteristics of putat plants. Samples in the form of putat shoots were obtained from Mahulu Long Melaham Village, Long Bagun District, Mahakam Ulu Regency, East Kalimantan. The stages of the research include plant determination, sample collection, processing of simplicia, extraction using maceration methods, specific and non specific extracts characterization. Specific characteristics of putat leaf extract include organoleptic test in the form of thick extract, blackish brown color, characteristic odor, bitter taste, average water soluble extract content of 62.50% and ethanol soluble extract 48.75%. Secondary metabolites of putat leaf ethanol extract are alkaloids, flavonoids, tannins, saponins, and steroids. The non-specific characteristics of putat leaf extract include average water content of 23.00%, ash content of 6.47% and acid insoluble ash content of 0.06%. Keywords: Planchonia valida, Characterization, Ethanol extract
Nanocomposites are a new material discovery in the 21st century. One of the nanocomposite materials which are useful in life is epoxy-clay nanocomposites. Epoxy clay nanocomposites have a reasonably wide application in industrial fields such as aerospace, defense, automobile, etc. The purpose of writing this review is to conduct a literature review on mechanical properties in various Cloisite as a filler of Epoxy-clay Nanocomposites. There are several examples of cloisite, namely Cloisite 10A, Cloisite 15A, Cloisite 20A, Cloisite 25A, Cloisite 30B, and Cloisite 93A. Cloisite has the advantage of producing mechanical properties, especially in the tensile modulus and strength, which is more increased than conventional reinforcing materials. These methods' synthesis results were then characterized using TEM, SEM, XRD, and other tests to determine their mechanical properties. The material parameters resulting from nanocomposites' synthesis are well seen from the high Tensile strength and modulus values. The highest increase in mechanical properties was found in the cloisite 93A by the ultrasonic synthesis method or mechanical stirring based on the study results.
The main objective of this study is to determine the most effective factors that can play an important role in increasing the effectiveness of Islamic internal audit in the Islamic banking industry. This research is a qualitative method using scientific journal literature searches, and data collection was carried out using the Emerald online database. Sharia banking was established which has the aim of increasing economic activity in accordance with sharia principles, there is no usury, speculation, maysir, gharar and other activities that have been prohibited in sharia. Sharia internal audit is a way to maintain and ensure the integrity of Islamic financial institutions in implementing sharia principles. The existence of sharia internal audit for Islamic banking, provides assurance and independent accountability for stakeholders. the competence of the internal auditors is not enhanced, especially competencies related to the auditor's knowledge of muamalah sharia/fiqh or sharia audit which can be proven by holding a sharia-related certification. In carrying out their duties as an internal auditor, they must have competency qualifications to know and understand how the actual condition of sharia principles is so that they can identify if a violation occurs that is not in accordance with sharia principles both in transactions and operations.
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