Potensi Ekstrak Daun Pepaya sebagai Inhibitor Korosi dalam Media Asam Klorida pada Baja ST37

Corrosion is a decrease in the quality of a metal material caused by a reaction with the environment. Reducing the corrosion rate on steel can be done by adding an inhibitor. Papaya leaf extract (Carica papaya.L) can be used as a corrosion inhibitor by immersion method. The effect of inhibitor on corrosion rate had been studied using weight loss method, potentiodynamic polarization method, and observation of steel surface using photooptic. It was found that corrosion rate decrease with increase concentration of papaya leaves extract. The highest inhibiton efficiency is 87.8% in 0.2 M hydrochloric acid with 2% concentration of papaya leaves extract. Potentiodynamic polarization method showed that papaya leaves extract decrease corrotion current. Inhibiton efficiency reached 81.58% in 2% extract concentration in which corrosion current decrease from 0.0266 mA/cm2 to 0.0049 mA/cm2. Analysis of photooptic showed that there is difference on steel surface corroded in hydrochloric acid with inhibitor and without it.

OBTAINING CONDITIONS FOR TECHNOLOGY NEUTRALITY OF COMMUNICATION SYSTEMS WITH MINIMUM COUPLING LOSS METHOD

Background. Technology neutrality is widely used in frequency bands, where communication systems are evolving, but there are strict restrictions on the parameters and deployment of base stations of different technologies using adjacent channels. Ways to mitigate this effect have not been sufficiently studied and require further analysis and development. Objective. The purpose of this article is to investigate the methodology for obtaining technical conditions of technological neutrality with minimum coupling loss method to determine the value of additional filtering requirements and present the results of practical implementation of this technique. Methods. The method of detailed power analysis of frequency characteristics of filters for base stations’ transmitter and receiver is applied. Results. The article presents the results of obtaining minimal guard band and additional filtering requirements in the adjacent channels of transmitter and receiver belonging to different technologies. Examples of practical implementation of the minimum guard band and frequency characteristics of additional filters are given. Conclusions. The general method of determining the technical conditions for ensuring technology neutrality is presented and the value of the minimal required guard band between the adjacent transmitter and receiver channels is obtained.

Pelatihan Penerapan PSAK 71 (Instrumen Keuangan) pada Perusahaan Daerah Air Minum di Wilayah Sumatera Selatan dan Bangka Belitung

Kegiatan Pengabdian Kepada Masyarakat ini bertujuan untuk memberikan pendampingan kepada bagian pengelolaan piutang usaha Perusahaan Daerah Air Minum di Wilayah Sumatera Selatan dan Bangka Belitung untuk mengestimasi besarnya penyisihan piutang tidak tertagih dengan menggunakan Expected Loss Method. Metode kegiatan ini dengan memberikan penyuluhan dan pendampingan kepada PDAM dalam membuat perhitungan estimasi piutang tak tertagih. Hasil pengabdian masyarakat ini ditandai dengan antusias dan kemampuan peserta dalam menerima materi dan mampu melakukan praktik untuk menghitung penyisihan piutang usaha dan penurunan nilai piutang usaha. Hasil kegiatan ini diharapkan bermanfaat bagi PDAM untuk meningkatkan pengelolaan piutang usaha yang nantinya akan meningkatkan pendapatan PDAM dan Pendapatan Asli Daerah.

Study of Factors Influencing Medical, Psychological and Pedagogical Rehabilitation Efficacy in Preschool Children with Hearing Disorders

Objective. The aim of the study is to identify the most significant factors influencing the audio-verbal rehabilitation outcomes in preschool children.Methods. The study included 104 children, 3–7 years of age, with hearing loss who underwent course of audioverbal rehabilitation in audiology center: 50 children after cochlear implantation, 51 children with hearing aids, 3 children without hearing care. The following data was collected at the beginning of the course: gender, type and degree of hearing loss, comorbidities, method and age of hearing care, family structure, preschool organization type. The scale of social and psychological diagnostics was filled in. The dynamics of indicators were estimated at the end of the course. The overall result was rated as high, good, medium or low. Correlations between clinical, audiological, social, psychological data and different rehabilitation outcomes were estimated.Results. Degree and type of hearing loss, method of hearing care, gender, age, and social aspects do not affect the rehabilitation outcomes. Hearing aid was performed before 3 years of age in 67% of children, and after 3 years of age in 33% of children in the group with high and good results. Hearing aid was performed after 3 years of age in 61% of children, and before 3 years of age in 39% of children in the group with medium and low results (p < 0.01). Burdened anamnesis and comorbidity was determined in 28% of children with high/good outcomes and in 59% of children with medium/low outcomes (p < 0.01). Children with medium results rarely have previous audiology therapy, 43.8% of cases (p < 0.01). Children with medium and low outcomes have statistically worse score according to the scale of social and psychological diagnostics (p < 0.05 and p < 0.01, respectively).Conclusion. High results of audio-verbal rehabilitation in preschool children can be predicted by the age of primary hearing care (before 3 years of age), absence of comorbidities, previous audiology therapy, score at the scale of social and psychological diagnostics less than 17 points.

Performance and boiler efficiency using low-grade coal on 400 MWe coal-fired power plant: case study of Suralaya Power Plant Unit 2

In a coal steam power plant, changes in coal quality significantly affect plant performance, especially in its boiler. A coal-fired power plant with a capacity of 400 MWe had been commissioned using coal with a calorific value of 5,242 kCal/kg. This study aims to determine the effect on unit performance and boiler efficiency due to changes in fuel use with the typical calorific value of 3,520 kCal/kg, 34,17% lower than the initial design. The performance tests were conducted using the heat loss method at loads: 50%, 65%, 75%, and 100%. The test result showed that using low-grade coal reduces boiler efficiency by 6.26%. There were four dominant boiler losses: heat loss due to moisture in dry flue gas, heat loss due to combustible in refuse, heat loss due to moisture in fuel, and heat loss due to hydrogen burning. Furthermore, the gross plant heat rate using low-grade coal was increased from 2,120 kCal/kWh to 2,718 kCal/kWh; however, the electric price becomes cheaper from 1.99 cent-USD/kWh becomes 1.31 cent-USD/kWh.

The performance of Pacitan Power Plant (pulverized boiler) toward the blending coal: an experimental

Coal blending testing of medium rank coal (MRC) and low-rank coal (LRC) in the Pacitan power plant with pulverized boiler type was conducted to increase the use of readily available coal. It was necessary to ensure the impact of the blending coal on the boiler performance. Therefore, this study was aimed to examine the performance of the plant. There were two coal blending configurations in testing; a) Combo #1: 75% of LRC and 25% MRC; b) Combo #2: 60% of LRC and 40% MRC. Each combination was held in 4 schemes of load at 165 MW, 210 MW, 255 MW, and 300 MW. Heat rate calculation was determined with the heat loss method (energy balanced approach). As a result, compared to the commissioning test (2,270 kCal/kWh), the power plant performance decreased. The performance of combo #1 obtained 2,517 kcal/kWh; meanwhile, combo #2‘s performance showed 2,360 kcal/kWh.

Mechanism of Inhibitive Action of Dl-Methionine Towards the Corrosion of Mild Steel in Hydrochloric Acid Solution

DL-methionine has been investigated as inhibitor for the corrosion of mild steel in 1.0M hydrochloric acid solution using weight loss method and Scanning Electron Microscope (SEM) analysis. The investigated results showed that the inhibition efficiency increases with the increase in concentration of the inhibitor and decreases with the increase in temperature. SEM analysis indicated that the metal surface was in a better condition in the presence of inhibitor than the specimen exposed in the absence of the inhibitor. DL-methionine acted as a very good inhibitor and is also environmentally friendly, non -toxic, biodegradable and relatively cheap. Keywords: DL-methionine, mild steel, SEM, Corrosion inhibitor.

Optimization of Blended Guava and Fluted Pumpkin Leaves extract as corrosion inhibitor of mild steel in 0.5 m hydrochloric acid

There are many plant extracts that have been studied for possible use as corrosion inhibitors in the oil and gas industries. Hence, this work is focused on optimization of blended Guava and Fluted Pumpkin Leaves extract as corrosion inhibitor of mild steel in HCI using Weight loss method. Response Surface Methodology of Design Expert trial version 12 StatEase was used to design and analyze the result of the 35-run experiments. Three factor-three level was adopted in the design. Time, Temperature and Inhibitor Quantity were the independent variables, while the acid concentration of 0.5M was constant throughout the experiments and Inhibition Efficiencies were measured using IE formula. Intervals of 1 hr, 0.2g, and 10°C were chosen for the immersion time, inhibitor quantity and temperature, respectively. Phytochemical analysis carried out on the Guava and Fluted Pumpkin Leaves shows that each leaf extract contains phytochemicals which are responsible for inhibiting corrosion. Weight loss result shows that the Blended extract reduces the corrosion rate of mild steel in 0.5M HCl. Additionally, 4 experiments for Blended Extract, Fluted Pumpkin, Guava Extract and Industrial Inhibitor were carried out at optimal conditions as predicted by the software at time 4.036 hr, temperature 49.5°C, inhibitor quantity 0.487g and ratio of 59.21GE:FP40.79 Inhibition Efficiencies of the Blended, Fluted Pumpkin, Guava Extracts and Industrial Inhibitor were 93.70%, 78.14%, 63.7% and 95.18%, respectively. The results show that the blended and Industrial Inhibitor compared well with the software predicted IE of 96.085%. Therefore, the blended extract could serve as good substitute to the industrial inhibitor.

ENVIRONMENTAL FRAGILITY OF THE IRAÍ RIVER BASIN – WATER SUPPLY SOURCE FOR CURITIBA, PARANÁ

This research aimed to compare two methods of determining the environmental fragility of a vital source in the region of Curitiba, Paraná, the Iraí river basin. The determination of the environmental fragility was carried out based on the integration of geological, pedological, geomorphological characteristics and land use, using the emergent fragility and Natural Vulnerability to Soil Loss methods. Most of the Iraí River basin was classified as weak to intermediate environmental fragility by both methods. The methods showed equal fragility ratings in 74% of the basin area. The greatest fragilities were found in areas with recent sedimentation, soils with high instability, slopes higher than 12% and land use areas with low protective potential. The emergent fragility method highlighted the effect of land use, accentuating the fragility of the most vulnerable classes. In contrast, the Natural Vulnerability to Soil Loss method attenuated this land-use effect, softening the vulnerability. The fragility maps indicated that different results might be obtained, especially on the threshold between fragility classes and polygons where land-use makes the environment more vulnerable. Thus, the method selection for determining environmental fragility depends on the relevance necessary for land-use. The emergent fragility method is advantageous for showing the fragility in areas mainly occupied by classes of land use of high vulnerability.