In general, surfactants are processed from petroleum and natural gas, which can cause environmental pollution. Therefore, an alternative approach has been identified: using vegetable oils, such as Virgin Coconut Oil (VCO), as raw materials for surfactant production. One type of surfactant that can be made from VCO is Methyl Ester Sulfonate (MES), an environmentally friendly anionic surfactant with great potential for development as a detergent base. This study aims to determine the effect of sulfonation temperature and time on the characteristics of MES synthesized from VCO. The synthesis process is carried out in two stages: transesterification of VCO to a methyl ester, followed by sulfonation with sodium bisulfite (NaHSO₃) as the sulfonating agent and calcium oxide (CaO) as the catalyst. The reaction temperatures were 90°C, 100°C, 110°C, and 120°C, with reaction times of 180, 210, 240, and 270 minutes, respectively. Parameters analyzed included yield, density, pH, and the FTIR spectrum of the MES product. The results showed that temperature and reaction time significantly influenced the characteristics of the resulting MES product. The highest yield of 90.25% was obtained at 110°C and 210 minutes. Product characterization showed that the optimum operating conditions produced MES with physical and chemical properties that meet the standards for good surfactants. This research contributes to the development of environmentally friendly, renewable, natural-based surfactants.

This manuscript deals with the modeling and energy simulation of waste from 5 mango varieties and charcoal from a mixture of mango pits. Two empirical studies have been carried out previously. The first allowed the determination of the waste rates (pits and skins) per unit of mango from the 5 varieties and the carbonization yield of a mixture of pits from different varieties. The second allowed the determination of the moisture levels and calorific values of these fuels. From these data, mathematical expressions of the masses, energies, wood, and charcoal equivalent masses of the studied fuels were established based on the masses of raw fresh mangoes in 2 case studies. A simulation carried out on all 5 varieties studied showed that 1000 kg of fresh mangoes could produce approximately 103 kg of wet pits, equivalent to 56 kg of anhydrous pits capable of producing approximately 900 MJ by combustion. This energy would be equivalent to the energy of approximately 48 kg of anhydrous wood. This quantity of fresh mangoes could produce approximately 48 kg of wet skins, equivalent to 12 kg of anhydrous skins, the combustion of which could produce approximately 182 MJ. This energy would be equivalent to the energy of approximately 10 kg of anhydrous wood. As for the pits charcoal, the 103 kg of moist pits that can be produced could produce, after carbonization, 23 kg of anhydrous pits charcoal, equivalent to the energy of 14.50 kg of anhydrous charcoal.

The application of CO2 laser cutting technology in the fabrication of medical implants holds significant promise for enhancing precision, efficiency, and quality in biomedical manufacturing processes. This paper describes a study that investigates the use of CO2 laser cutting to create mesh medical implants utilizing biocompatible material, specifically stainless steel 316L. Through a brief review of laser cutting principles and previous studies, the paper provides insights into the process parameters to achieve optimal outcomes. The study investigates the influence of laser power, cutting speed, and gas pressure on the quality and characteristics of the manufactured implants. The primary focus is on the attributes of the shape, dimensions, heat-affected zone (HAZ), thermal burr, and surface roughness. Experimental results reveal the capability of CO2 laser cutting to accurately reproduce intricate mesh medical implant designs with minimal material waste and high precision. Moreover, the study highlights the importance of CNC control systems in ensuring consistent and reproducible manufacturing processes. Overall, the findings underscore the potential of CO2 laser cutting technology to revolutionize the production of mesh medical implants, offering improved quality, functionality, and patient outcomes in biomedical applications.

The vulnerability of reinforced concrete buildings in Indonesia-especially in seismic regions like Padang-has been worsened by poor detailing and outdated codes. This study evaluates the seismic performance of a four-story office building designed initially under SNI 1726:2012 and SNI 2847:2013, considering the updated seismic demands in SNI 1726:2019. Linear analysis showed that several beams no longer met strength requirements, while columns remained adequate due to higher initial safety factors. The structure was then modeled with four confinement reinforcement scenarios, varying stirrup quantity and spacing, to reflect typical field practices. Shear strength validation was conducted beforehand to ensure plastic mechanisms could form without premature shear failure. Nonlinear pushover analysis using SAP2000, supported by moment-curvature results from XTRACT, focused on (1) base shear and drift capacity, (2) plastic hinge formation, and (3) energy dissipation capacity. While all models satisfied Life Safety (LS) criteria, Model D-with the widest stirrup spacing-showed early stiffness degradation, exceeded shear capacity in some columns, and recorded the lowest energy dissipation. These results confirm the key role of proper stirrup detailing in enhancing strength, ductility, and seismic resilience.

Graphene is used in a variety of chemical, thermal, mechanical, and electrical applications. It contains one carbon atomic slide. This paper proposes a graphene-based plasmonic antenna array for THz applications. Additionally, the THz SPP waves (Surface Plasmon Polariton) phenomenon in graphene is shown. The proposed antenna is made up of four by six graphene patches, which are excited by a graphene Nano ribbon feeder placed on top of an alumina layer. CST 2020 software was used to simulate and study the antenna. As per the findings, the antenna operates in the frequency ranges [(2.6-10), (2.28-2.5), (1.87-2.14), and (1.4-1.6) ] THz, where S11 is equal to or less than -10 dB. The antenna's gain is high in these frequency band regions.

This test aimed to determine the effect of loaded and unloaded coconut shell charcoal briquettes with tapioca and starch adhesives on the AC electric motor RPM during the briquette-making process, and to obtain optimal hardness values for both coconut shell charcoal briquettes with tapioca and starch adhesives. The hardness testing method for coconut shell charcoal briquettes used the Brinell hardness test, using samples of coconut shell charcoal briquettes with tapioca and starch adhesives. The measurement used was an optical one, measuring the size of the indentation left by the indenter. Standard optical hardness testing methods include the Brinell hardness test (ISO 6506, ASTM E10). Based on the results of the briquette machine test for 7 minutes with a load of 15 kg, the coconut shell charcoal with starch adhesive produced an AC electric motor RPM of 702.9, while the coconut shell charcoal with tapioca adhesive produced an AC electric motor RPM of 884.7. The average hardness test results of coconut shell charcoal briquettes with tapioca adhesive have a value of 17.33 HRB, while coconut charcoal briquettes with starch adhesive have a value of 21.36 HRB. The hardness value of coconut shell charcoal briquettes with starch adhesive is harder or more optimal than coconut shell charcoal briquettes with tapioca adhesive.

The new technology referred to as substrate integrated waveguide (SIW) is considered to be appropriate for fifth-generation (5G) networks. In the presented work, SIW antenna with two slots was developed at 28GHz for improving the antenna's parameters. The distance between vias was controlled for minimizing the antenna's losses. SIW technology was developed at higher frequency, also has compact size and good performance. Yet, SIW antennas have losses at high frequencies due to the distance between vias. The radiating patch of antenna that is being provided depending on without and with slots. For increasing the antenna's bandwidth and gain, two types of slots—zigzag and straight—were etched onto the patch. Low losses, significantly high gain and efficiency, also overall structural size of 7.11 x 14.8, both without and with slot, were attained with the suggested design. Straight slot as well as zigzag antennas that are suggested resonate at 28 GHz. The measured results have shown that the proposed antenna could provide 95% efficiency, 8.1 dB gain, also huge band-width of at least 3.1GHz at 28GHz. For boosting the antenna's primary parameters, single antenna was transformed into 1x4 array that was simulated as well as measured. SIW antenna is suitable for 5G applications base stations, according to measurement results.

This paper presents a new antenna in body system (AIBS) for wireless power transfer applications at the ISM band. The proposed antenna uses planar microstrip technology, providing a compact size, low signal absorbing ratio (SAR), and wide bandwidth, which are the big challenges of AIBS at the ISM band. This design uses a cavity slot antenna based on microstrip technology that resonates at the ISM band 2.45 GHz for an antenna in a body system. The proposed antenna system conforms to an implantable transmit antenna (TX) and a received antenna (RX) with a gap of 30mm. The transmit antenna is designed using a square metamaterial technique to increase the band width and resonant frequency at a certain frequency. Received antenna has been designed based on a cavity gridded slot to achieve a compact size. The transmit antenna uses Rogers RT5880 substrate with a thickness of 1.575mm, while the receive antenna is implemented on Rogers RO3010 substrate with a thickness of 0.25mm. Both structures are optimized for low specific absorption rate (SAR) to enhance the power transfer efficiency (PTE). The proposed design antenna system integrated with human-body tissue, including skin, fat, and muscle, is simulated by using Computer Simulation Technology (CST) software to create a similar environment to the human body. The proposed design was fabricated and measured at 2.45 GHz. The obtained results show good performance in terms of bandwidth of transmit and received antennas (0.9 GHz- 0.200 GHz), gain 4.5 dB, 2.5 dB, and efficiency 88 %, 81%, respectively. The received antenna has a compact size of 6.83mm × 6.5mm. The transmit and receive antennas provide a good VSWR of 1.2 and 1.17, respectively. In addition, the front-to-back radiation ratios of the transmit and receive antennas are 20.4dB and 16.07dB, respectively. Designs have been fabricated and measured with minced pork because it has similar tissue to the human body. Measurement results are in good agreement with simulation results, which validate the proposed antenna designs.

The essential oils of Cupressus sempervirens L (C. sempervirens) and Mentha pulegium L(M. pulegium), rich in α-ocimene, δ-3-carene (27.43%) and pulegone (72.68%), respectively, were evaluated for their insecticidal activity against Thaumetopoea pityocampa (T. pityocampa ) (Denis and Schiffermüller, 1775). In ingestion bioassays, M. pulegium EO showed the highest efficacy, reaching 100% mortality at 150 µL/mL for L4 and L5 instars, with LC50 values of 38.835 and 33.835 µL/mL.C. sempervirens essential oil exhibited the highest toxicity against third-stage T. pityocampaSchiff larvae, with LC50 values of 13.02 µL/mL (ingestion) and 47.59 µL/mL (contact), and corrected mortality up to 100%. Fumigant bioassays confirmed complete mortality of L4 larvae at 100ul/mL (LC50 = 22.1 µL/mL). In vivo, larval survival dropped from 100% to 0% within 18 days, and biochemical analyses revealed significant depletion of lipid, carbohydrate, and protein reserves.

This paper presents the research results of coal mining diversification scenarios. To achieve the purpose set, the Cobb-Douglas model is used, which takes into account the productive flows of a coal mine (coal, methane gas, rock, water). An algorithm for studying production scenarios has been developed, which includes the function logarithmization, determining elasticity coefficients, and studying scenarios. Four production scenarios have been analyzed, taking into account different production situations from the mutual influence of productive flows to the state when there is no coal mining. The obtained models have been validated for linear homogeneity. Coal as a productive flow has been found to have negative elasticity, which indicates direct influence on the efficiency level; that is, if it does not correspond to the rational level of mining, there is an uncontrolled curtailment in production capacity. The rock, like methane gas, has positive elasticity, indicating a constant return regardless of production volumes. Water has zero elasticity; however, in the absence of coal mining, it is the second most promising productive flow. Based on the scenario modeling, it has been found that under conditional production profitability of coal mining, the configuration of productive flows is constant, but when the level is reached. In the absence of coal mining, the most promising scenario is the recycling of coal mining waste. The hypothesis on the distribution of productive flows is confirmed by the AHP, PROMETHEE, ELECTRE, and VICOR hierarchy analysis methods. Appropriate software has been developed to implement the approach.