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Science and Technology Indonesia

JSTI
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Published by Universitas Sriwijaya

ISSN : 25804405 EISSN : 25804391 DOI : -

Core Subject : Science, Social, Engineering,

Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Environmental Science Materials Science & Nanotechnology Physics

An international Peer-review journal in the field of science and technology published by The Indonesian Science and Technology Society. Science and Technology Indonesia is a member of Crossref with DOI prefix number: 10.26554/sti. Science and Technology Indonesia publishes quarterly (January, April, July, October). Science and Technology Indonesia is an international scholarly journal on the field of science and technology aimed to publish a high-quality scientific paper including original research papers, reviews, short communication, and technical notes. This journal welcomes the submission of articles that covers a typical subject of natural science and technology such as: > Chemistry > Biology > Physics > Marine Science > Pharmacy > Chemical Engineering > Environmental Science and Engineering > Computational Engineering > Biotechnology Journal Commencement: October 2016

Arjuna Subject : -

Articles 521 Documents

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Cement Compressive Strength Control Using CUSUM and MCUSUM Control Chart Surya Puspita Sari; Ferra Yanuar; Dodi Devianto
Science and Technology Indonesia Vol. 5 No. 2 (2020): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Compressive strength is one of the test factors used to determine whether cement production is in a controlled state or not. Portland type composite cement or PCC is the cement that is widely used in infrastructure development. The Cement of 3-days compressive strength, 7-days compressive strength, and 28-days compressive strength are the variables that will be controlled in this study. The normal distribution test and correlation test show that the data on each variable is normally distributed, and each variable has a strong correlation. Univariate cement control using the cumulative sum control chart (CUSUM) and multivariate control using a multivariate cumulative sum (MCUSUM) control chart is performed to obtain the best control results. Correlated variables show that control using a multivariate control chart results in fewer outs of control observations compared to a univariate control chart. This explains that the MCUSUM control chart is more sensitive than the CUSUM control chart in controlling observations of data out of control.

Mathematical Model of Landslides with Curved Sliding Plane Using Fracture Criterion of Solid Soil-Rock System Ikah Ning Prasetiowati Permanasari; Lilik Hendrajaya; Gunawan Handayani
Science and Technology Indonesia Vol. 7 No. 1 (2022): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Alluvial cliff with high slope and step has been known to cause curving sliding plane. This phenomenon is adopted as a knowledge, but it has never been studied theoretically. In this paper, mathematics derivation phenomenon is proposed using special model of 11 fracture criterion ????-????. The quantity of ???? is A???? 2 with A is a friction coefficient of stress ???? 2 . The failure model was substituted to the corresponding Mohr circle resulting the expected curve. The curve was used to measure the observed field profile to obtain the friction coefficient A.

Effect of Plasticizer and Concentration on Characteristics of Bioplastic Based on Cellulose Acetate from Kapok (Ceiba pentandra) Fiber Rahmatullah; Rizka Wulandari Putri; Muhammad Rendana; Untung Waluyo; Tedi Andrianto
Science and Technology Indonesia Vol. 7 No. 1 (2022): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

The synthetic plastics that made from petroleum material have been widely used in all industrial sectors. They cause some serious problems for the environment. There are semi-synthetic plastics or biodegradable plastics which are made from natural polymers such as cellulose to mitigate this problem. Biodegradable plastics can fulfill the needs of society because they can be decomposed easily into the environment. This research used laboratory experimental methods through several processes: kapok fiber isolation, cellulose acetate production and purification, and manufacture of bioplastics. The characteristics of bioplastics was analyzed using some parameters such as density, tensile strength, elongation, Young's modulus, water absorption, biodegradability, compound group analysis using Fouier-Transform Infrared Spectrometer (FTIR) and bioplastic morphology analysis by using Scanning electrone microscopy (SEM). This study aimed to determine the effect of the plasticizer type and concentration on the bioplastics characteristics that was divided into several different concentrations of glycerol and sorbitol plasticizers (20%, 30%, and 40%). The fabrication of composite bioplastics used the cellulose acetat from kapok fiber, starch, and types of plasticizer (glycerol, and sorbitol). The results of the study showed that the addition of different plasticizers, such as glycerol and sorbitol gave distinct effects on the bioplastics product characteristics. The optimum concentration of glycerol addition affected the bioplastic characteristics with the best results were 40% concentration generate density of 0.836 g/mL, tensile strength of 0.818 MPa, water absorption value of 22.23%, and degradation plastic mass about 39.7%. The addition of sorbitol also affected the bioplastic characteristics, where the best results were 40% concentration produced bioplastic density of 0.941 g/mL, percent elongation at 3.94%, young’s modulus of 0.726 MPa, and degradarion mass of 32.05%. The morphology of bioplastic showed the high homogeneity on concentrations of 40% glycerol and 30% sorbitol.

The Impact of Climate Change on Cooling Energy Demand in Indonesia Based on Representative Concentration Pathways (RCP) Scenarios Desak Putu Okta Veanti; Rista Hernandi Virgianto; I Gusti Ayu Putu Putri Astiduari
Science and Technology Indonesia Vol. 7 No. 1 (2022): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Air conditioning system in a building is necessary to maintain air temperature at a certain comfort level, especially in tropical coun- tries such as Indonesia. Global warming was believed to accelerate the increase in energy consumption for air conditioning as a consequence of rising surface temperatures. This study aims to quantify the changes in energy consumption used for air condi- tioning systems based on Cooling Degree Days (CDD) that is calculated from the daily average temperature in Indonesia based on RCP4.5 and RCP8.5 scenarios. Projections for the future scenarios is compared with the energy consumptions in 2010. The results showed that energy consumptions increase up to 10 kWh/m2 year in 2030 for both scenarios. In 2050 RCP4.5 shows slightly higher Ew than RCP8.5 in some regions. However, in 2100, RCP8.5 shows significantly higher energy consumption for air conditioning sys- tem. The eastern part of Middle Kalimantan, South Kalimantan, Southern part of East Kalimantan, Northern East Java, Northern part of Lampung, South Sumatera, and Southern part of Papua shows the highest changes (51 to 68 kWh/m2 year)

The Film of Chitosan-ZnO Nanoparticles-CTAB : Synthesis, Characterization and In Vitro Study Ahmad Fatoni; Herlina Silvia Yessica; Aldilah; Mia Almi; Agnes Rendowaty; Romsiah; Lasmaryna Sirumapea; Nurlisa Hidayati
Science and Technology Indonesia Vol. 7 No. 1 (2022): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

The synthesis of film chitosan- ZnO nanoparticles-CTAB were studied. The aims of this research were synthesis of the film chitosan-ZnO nanoparticles-CTAB, its characterization and, application of the film chitosan-ZnO nanoparticles-CTAB as an antibacterial of Staphylococcus aureus. The film of chitosan-ZnO nanoparticles-CTAB was synthesized by the casting method and characterized by FTIR spectroscopy and X-ray diffraction, respectively. The film of chitosan-ZnO nanoparticles-CTAB was used as an antibacterial agent with the agar disk diffusion method. The result showed that the Zn-O group at the film of chitosan-ZnO nanoparticles-CTAB was detected at a wavenumber between 578-619 cm-1. The band at 2852.72-2854.65 cm-1 is the band of C-H groups in the film of chitosan-ZnO nanoparticles-CTAB. The effect of ZnO nanoparticles-CTAB changed of the physical structure of chitosan. The average of the inhibition zone in the film of chitosan-ZnO nanoparticles-CTAB I, II and III was 10.37 ± 0.55, 11.31± 1.27 and 10.38 ± 0.24 mm respectively.

Coefficient Bound of a New Generalized Class of Tilted Analytic Univalent Functions Abdullah Yahya; Mohd Najir Tokachil; Hasilatul Hana Hamzah; Shahriel Mohd Saifullah Pirman; Siti Asiah Che Muhammad
Science and Technology Indonesia Vol. 7 No. 1 (2022): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

This paper is concerned with the new generalized class of tilted analytic univalent functions, S*(q,a,s,t) which denoted as. Re{ei????f′(z) z }>????, m(z)for cos ???? > ????, |????| < ????, 0 ≤ ???? <1, m(z)= z , s ≠ 1, -1 ≤ t < 1, s ≠ t and s, t ∈ C which is analytic in the unit disk Δ={w:|w|<1}. The (1−sz) (1−tz)coefficient bound as well as representation theorem of extremal properties is obtained S∗(????,????,s,t).

Synthesis and Characterization of Fe-Doped CaTiO3 Polyhedra Prepared by Molten NaCl Salt Dwi Rahayu Novianti; Fikri Haikal; Usman Ali Rouf; Arie Hardian; Anton Prasetyo
Science and Technology Indonesia Vol. 7 No. 1 (2022): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

CaTiO3 as one of the perovskite-based photocatalysts has a band gap energy of 3.5 eV (~354 nm), thus will work at the ultraviolet light region. One of the strategies to decrease the band gap energy is doping metal. In this research, CaTiO3 was doped by Fe element as purposes to decreasing its band gap energy. Fe doped CaTiO3 compounds were synthesized using molten NaCl salt method. The diffractogram samples showed that the Fe-doped CaTiO3 crystal was successfully prepared. Meanwhile, the SEM images showed that the particle shape was regular polyhedral morphology, and doping Fe3+ caused the particle size to decrease and agglomerated. The UV-Vis DRS spectra showed that the Fe-dopant revealed the absorption light at visible range wavelength.

Effect of Synthesis Methods on Properties of Copper Oxide Doped Titanium Dioxide Photocatalyst in Dye Photodegradation of Rhodamine B Cheng Yee Leong; Hao Lin Teh; Man Ching Chen; Siew Ling Lee
Science and Technology Indonesia Vol. 7 No. 1 (2022): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Copper modified titanium dioxide photocatalysts have been widely reported for their excellent performance in the wastewater treatment. However, there is lack of information on the effect of different synthesis methods towards the properties and catalytic activity of the photocatalyst. In this research, a series of copper-doped titanium dioxide (Cu-TiO2) photocatalysts were synthesized via three different methods of sonochemical, impregnation and physical mixing. Cu-TiO2 with varied molar ratios of Cu dopant to TiO2 TR595 (100:0, 99:1, 98:2, 97:3 and 96:4) were prepared. Comparison of physical-chemical properties and photocatalytic activity among the synthesized samples were made. X-ray diffraction analysis depicted the formation of TiO2 rutile phase in all samples. Besides, diffuse reflectance UV-visible analysis proved that the synthesized samples were active under visible light region. According to the Tauc plot and photoluminescence spectra, the band gap energies and recombination rate of electron-hole pairs of Cu-TiO2 samples decreased upon loading of Cu. Moreover, EDX analysis confirmed the existence of Ti and Cu in all the samples. The photocatalytic efficiencies of the synthesized samples were discovered through photodegradation of Rhodamine B organic dye under 6 hours of visible light irradiation. Amongst, Cu-TiO2 photocatalysts synthesized via sonochemical method with molar ratio of 98:2 produced the highest photocatalytic activity of 64.8% which attributed to the lowest recombination rate of photogenerated charge carriers and availability of large number of reactive oxidative species.

Identification of Corn Plant Diseases and Pests Based on Digital Images using Multinomial Naïve Bayes and K-Nearest Neighbor Yulia Resti; Chandra Irsan; Mega Tiara Putri; Irsyadi Yani; Ansyori Ansyori; Bambang Suprihatin
Science and Technology Indonesia Vol. 7 No. 1 (2022): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Statistical machine learning has developed into integral components of contemporary scientific methodology. This integration provides automated procedures for predicting phenomena, case diagnosis, or object identification based on previous observations, uncovering patterns underlying data, and providing insights into the problem. Identification of corn plant diseases and pests using it has become popular recently. Corn (Zea mays L) is one of the essential carbohydrate-producing foodstuffs besides wheat and rice. Corn plants are sensitive to pests and diseases, resulting in a decrease in the quantity and quality of the production. Eradicate pests and diseases according to their type is a solution to overcome the problem of disease in corn plants. This research aims to identify corn plant diseases and pests based on the digital image using the Multinomial Naïve Bayes and K-Nearest Neighbor methods. The data used consisted of 761 digital images with six classes of corn plants disease and pest. The investigation shows that the K-Nearest Neighbor method has a better predictive performance than the Multinomial Naïve Bayes (MNB) method. The MNB method with two categories has an accuracy level of 92.72%, a precision level of 79.88%, a recall level of 79.24%, F1-score 78.17%, kappa 72.44%, and AUC 71.91%. Simultaneously, the K-Nearest Neighbor approach with k=3 has an accuracy of 99.54 %, a precision of 88.57%, recall 94.38%, F1-score 93.59%, kappa 94.30%, and AUC 95.45%.

A Simulation Study on The Simulated Annealing Algorithm in Estimating The Parameters of Generalized Gamma Distribution Amani A Idris; Sabri Shamsul Rijal Muhammad
Science and Technology Indonesia Vol. 7 No. 1 (2022): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

The gamma distribution is one of the most widely used statistical distribution in fitting various real life data set in the field of the reliability to fit failure data, because it is sufficiently flexible to deal with decreasing, constant, and increasing failure rates. In this article, the stock investment valuation model has been presented on the assumption of Gamma distribution. The purpose is to analysis profitability of investment in the property development sector in Malaysia based on the investment rate of return on investment. The flow of the investment cash and the accumulation of the share units over the investment period have been presented. it demonstrated the computing of MIRR by the case of a company which experienceed distributing a treasury share dividend, which increases the small portion of investor’s share units instead of receiving the dividend in cash. As the MIRR might exhibit negative values, the Gamma distribution of the transformed MIRR for certain investment periods is developed and the method of moment is applied to estimate the parameters. The study revealed that the transformed MIRR is well fitted with Gamma distribution for four years to eight years investment periods. It is shown that this approach has a better performance return on investment in Malaysia property sector from 2008 to 2018.

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