BERKALA SAINSTEK
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Comparison of Online and Offline Learning During The COVID-19 Pandemic using Naïve Bayes Method and C4.5
Get PDFLearning is a process of interaction between educators and students who meet the elements of learning carried out in an educational environment, so that learning can develop student’s abilities, interests and talents optimally. In today's era learning is done online and inversely with offline. The purpose of this study is to analyze the comparison of percentages and classification results as well as the results of learning evaluations using the Naïve Bayes method and C4.5. This test is carried out with 4 variables and a comparison of the two methods. The results showed that the accuracy of Naïve Bayes was 74.07% and C4.5. of 77.77% so that the comparison results show that the level of accuracy of the C4.5 method is better than Naïve Bayes. The resulting importance variables are time and effectiveness as well as the results of the classification of learning decisions, namely the offline category as many as 16 data on the Naïve Bayes method and 19 data on the Decision Tree algorithm C4.5 method from 27 input testing data
Production of Photosynthetic Pigments from Spirulina platensis Under Different Light Intensities
Get PDFPhotosynthetic pigments from microalgae have great potential biotechnological applications, as healthy food colorants and cosmetics. The production of photosynthetic pigments depends on many environmental conditions, mainly light intensity during the cultivation period. The present study aimed to determine the productivity of photosynthetic pigments in the biomass of S. platensis, including total chlorophylls, carotenoids, and phycocyanin, under different light intensities: 40 µmol m–2 s–1 (lower light intensity) and 70 µmol m–2 s–1 (higher light intensity). The results showed that S. platensis culture responds to changes in light intensity by changing the composition of photosynthetic pigments as an adaptive mechanism. The higher carotenoids content (69.69 ± 7.47 µg/g dw) was found under high light intensity, meanwhile, the higher chlorophyll (1495.47 ± 279.00 µg/g dw) and phycocyanin (4995.49 ± 576.52 µg/g dw) contents were observed under low light intensity. The highest productivity of photosynthetic pigments in S. platensis was shown by phycocyanin (318.86 ± 44.22 µg/L/day) and cholophylls (95.38 ± 19.35 µg/L/day) which were produced under low light intensity. Our results show that changes in light intensity can contribute to a stronger effect on the productivity of algal pigments for human health benefits and food colorants
The Coating of Mahogany Leaves Composite Using Clove Leaf Essential Oil as An Anti-Fungal Ganoderma lucidum
Get PDFThis work has been carried out to use clove leaf oil as a composite coating component having anti-fungal properties. The mushroom growth testing was carried out with minimum inhibitory concentration (MIC) testing with variations in concentrations of 0%, 0.2%, 0.4%, 0.6%, 0.8%, up to 1% and obtained MIC values of clove oil found at a concentration of 0.4% in inhibiting the growth of white-rot fungi. Ganoderma lucidum mushroom is used as a weathering fungus applied in composites. The results of SSD testing showed that the growth of Ganoderma lucidum fungus began to be inhibited in composites coated with clove oil with a concentration of 0.6%.FTIR testing showed the presence of hydroxyl group (O-H), methylene group (C-H), alkenyl (C=C), and aromatic ring (C=C-C), GC-MS test results showed clove oil containing 67.40% eugenol, 17.42% beta-caryophyllene, 2.91% isopropenyl acetate, 1.56% caryophyllene oxide and 0.91% alpha-copaene. Based on research data, it shows that clove leaf oil can be used as an anti-fungal coating component in composites
Estimating The Distribution of Sea Water Intrusion in Sengkubang Village Based on The Resistivity Value
Get PDFThe fulfillment of clean water needs in Sengkubang Village is done by utilizing groundwater, which in some locations still has a brackish to salty. This situation is one indication of seawater intrusion into groundwater because Sengkubang Village is a coastal area. This study aims to estimate the distribution of seawater intrusion based on the subsurface resistivity value. The method used is the resistivity method with dipole-dipole configuration. Measurements in the field apply six lines with a length of 55 m and the smallest electrode distance of 5 m. The distance of each line from the coastline is approximately 410 m, 485 m, 560 m, 635 m, 710 m, and 785 m. The interpretation results show that the seawater intrusion at the study area has a resistivity value of 0.223 Ωm - 5.03 Ωm at a depth of 0.854 m to 10.9 m. The subsurface layer at the study site is composed of sand, sandy clay, and gravel sand mixed with silt. The unconfined aquifer layer, which is interpreted as sand, is thought to have experienced seawater intrusion to 785 m from the coastline
Synthesis of The Cu(II)-doped TiO2/Bi2O3 as a Photocatalyst for Rhodamin B Degradation Under Visible Light Ilumination
Get PDFThe Cu(II)-doped TiO2 and Cu(II)-doped TiO2 /Bi2O3 compound have been synthesized using the sol gel method with titanium tetraisopropoxide (TTIP) as the TiO2 precursor and Cu(NO3)2.3H2O as the Cu(II) dopant was carried out at various concentration of 0.075%; 0.250% and 1.000%, as well as Bi(NO3)3.5H2O as a Bi2O3 precursor. Based on characterization using the DRSUV-Vis spectrophotometric method with data analysis using a tauch plot, it is known that the band gap energy of Cu(II)-doped TiO2 is 2.89 eV; 2.72 eV; 2.54 eV. The addition of Bi2O3 to Cu(II)-doped TiO2 (1%) causes a decrease in the band gap from 2.54 to 2.18 eV which is equivalent to a wavelength of 567 nm. IR spectrophotometry spectra analysis shows a shift in Ti-O absorption towards smaller wave numbers. Characterization by the XRD method shows that 1% Cu(II)-doped TiO2 /Bi2O3 has an anatase phase with a crystallite size of 24 nm. Photocatalysis activity test on the degradation of rhodamine B solution at a concentration of 10 ppm, under visible light illumination for 180 minutes was able to degrade up to 85.85%
Vulnerability Analysis of Rectorate Building of UIN Mataram against Earthquakes Based on Microtremor Data
Get PDFLombok Earthquake in 2018 caused several damages to buildings, including buildings at UIN Mataram. Therefore, it is necessary to carry out mitigation efforts to reduce losses caused by the earthquake. This study aims to analyze the level of vulnerability of the Rectorate Building of UIN Mataram based on microtremor data. Microtremor signal recording was performed using a 3-component Digital Portable Seismograph, type TDL 303S with a Feedback Short Period Seismometer sensor type DS-4A, GPS, and Laptop. The recording time for each measurement point was 40 minutes with a sampling rate of 100 Hz. The natural frequency of the Rectorate Building of UIN Mataram is 4.15 Hz for the N-S component, and 4.05 Hz for the E-W component. The natural frequency of the Rectorate Building is following the SNI (2002) standard. The resonance index value of the Rectorate Building with the surrounding land is in a low category so that the Rectorate Building is classified as safe against earthquakes. The highest building Vulnerability Index is on the 3rd floor of the Rectorate building, especially in the south wing. For disaster mitigation, the 3rd floor can be converted as a room with minimal staff to reduce the possibility of casualties in the event of an earthquake in the future
Co(II)-TiO2/Ti Thin Film as Antibacterial Photocatalysts Escherichia Coli Under Visible Light Ilumination
Get PDFA thin layer of TiO2 doped with Cobalt (II) immobilized on the surface of a titanium foil (Co(II)-TiO2/Ti) has been synthesized from a titanium foil (Ti) as a TiO2 precursor as well as a thin layer matrix and CoCl2.6H2O as a source of Co(II) on variations of 0.5%, 1% and 2%. Synthesis was carried out by anodizing method using ethylene glycol electrolyte solution with the addition of NH4F and followed by calcination treatment at 450ºC for 3 hours. The obtained Co(II)-TiO2 /Ti thin films were characterized using Fourier-transform infrared (FT-IR) spectroscopy, Diffuse Reflectance UV-Vis (DRSUV-Vis) and X-ray diffraction (XRD) methods. Doping Co(II) variations of 0.5%, 1.0% dan 2.0% in the TiO2 structure causes a shift in the vibrational absorption peak of Ti-O (460.99 cm-1) towards a smaller wave number of 459.06 cm-1 respectively ; 453.27 cm-1 and 451.34 cm-1. This is supported by the results of the DRUV-Vis analysis using the tauc plot method, which shows a decrease in the band gap energy of TiO2 (3.24 eV) to 2.57 eV, 2.47 eV and 2.28 eV. Based on XRD analysis, it is known that the Co(II)-TiO2/Ti photocatalyst has anatase phase with a crystal size of 15-17 nm. The photocatalytic activity of Co(II)-TiO2/Ti under visible light illumination was evaluated for inhibition of Escherichia coli bacterial growth. Co(II)-TiO2/Ti photocatalyst at 2.0% Co(II) concentration had the best inhibition (43.2%) compared to 0.5% and 1.0% Co(II) concentrations, respectively 18% inhibition and 27%
Characterization of Seaweed Caragenan Eucheuma cottonii and Its Aplication as Edible coating
Get PDFSeaweed E. cottonii is carragaenophytes or carrageenan-producing plant. Carrageenan has a functions stabilizer, thickener and gel former, so it can be used as edible coating that can maintain fish quality. Tuna has nutritional content per 100 grams such protein around 25-26.2%; water 69.40%; fat 1.50%; and carbohydrates 0.03%. Tuna filets quickly decompose if proper handling is not carried out, it is necessary to apply edible coating because this edible coating can protect the product from air contamination and can prevent microbial growth. This study aims to determine the effect of extraction time characteristics of carrageenan and the appropriate concentration of carrageenan for edilbe coating tuna filet. The extraction process was carried out by heating dried seaweed samples with 8% KOH solution for 1 hour, 2 hours and 3 hours at a temperature of 50˚C. The best characteristics of carrageenan resulted from 2 hours of extraction time with 40% yield, 14.95% water content, 63 dPas viscosity and 12.396 ppm sulfate content. The best carrageenan was applied as edible coating on tuna filets with 3 concentrations, namely 1.5%, 2% and 2.5%, each of which was added with 2 mL of glycerol. Based on the Total Plate Count (TPC), it was found that a carrageenan concentration of 2.5% could prevent bacterial growth in the sample as indicated by the TPC number obtained at 2.7×106, which was lower than the control, which was 1.7×107