Linear Potential Sweep Voltammetry in Conjunction with Small Amplitude Cyclic Voltammetry Study for Chalcopyrite-Xanthate Electrochemical Flotation System

Abstract. The present study was undertaken to investigate the electrochemical aspects of reactions on platinum, copper, and chalcopyrite aqueous xanthate solution interfaces by the small amplitude cyclic voltammetry (SACV) technique. In the technique, the potential of an electrode is swept linearly with time within very narrow potential limits. Typically a 10 to 20 mV peak-to-peak triangular potential excitation has been used. Characteristic parameters of the observed current-potential response loop, like apparent polarization resistance, was used to analyze the surface reaction mechanism in the flotation of chalcopyrite minerals. The analysis of the electrochemical interaction between platinum, copper and xanthate ions has also been carried out by using linear potential sweep voltammetry (LPSV) techniques in different xanthate concentrations. The voltammograms obtained on platinum appear due to the possibility of the formation of dixanthogen from the oxidation of xanthate ions, and the formation of copper-xanthate species from elecbochemical reactions between xanthate ions and copper. Studi Voltametri Penyapuan Potensial Linier Dikaitkan dengan Voltametri Siklus Amplitudo Kecil untuk Sistem Flotasi Elektrokimia Kalkopirit-xantatSari. Penelitian ini memberikan gambaran reaksi elektrokimia pada antarmuka elektroda platina, tembaga, dan kalkopirit di dalam larutan encer xantat. Penelitian dilakukan dengan metode SACV (Small Amplitude Cyclic Voltammetry), dengan rentang eksitasi potensial segitiga yang sangat kecil, yaitu 10 mV sampai 20 mV eksitasi dipakai untuk menganalisis mekanisme reaksi flotasi mineral kolkopirit. Untuk mempertegas hasil SACV penelitian dilanjutkan dengan metode LPSV (Linear Potential Sweep Voltammetry). Voltammogram yang diperoleh menggambarkan terbentuknya dixantogen di permukaan elektroda platina, dan terbentuknya senyawa tembaga-xantat karena adanya reaksi permukaan antara ion xantat dengan tembaga

Analisis Kronopotensiometri Arus Balik pada Interaksi Elektrokimia Platina-Xantat

The electrochemical interaction of xanthate ions commonly used as a sulphide minerals flotation collector with platinum electrodes is analyzed by using chronopotentiometric methods. Currents were applied to a platinum electrode immersed in xanthate free and xanthate containing borate solutions. The formation of dixanthogen from xanthate ions oxidation was observed at the application of positive currents. Its reduction is observed at negative currents. The equilibrium of xanthate-dixanthogen couple is applied current dependent. At low applied currents, the time required to reach the equilibrium is longer than the one of high applied currents. Interaksie letrokimia antara xantat sebagai reagen flotasi dengan logam platina dipelajari dengan cara pemuatan berganti. Pemuatan dilakukan dengan memberikan arus pada elektroda platina yang tercelup dalam larutan xantat dengan berbagai konsentrasi. Oksidasi ion xantat menjadi dixantogen teramati beberapa saat setelah pemberian arus positif dan reduksi dixantogen terjadi beberapa saat setelah pemberian arus negatif. Tercapainya kesetimbangan antara ion xantat dengan dixantogen sangat bergantung pada kuat arus yang diberikan. Pada kuat arus yang rendah diperlukan waktu yang relatif lebih lama untuk mencapai kesetimbangan

The Antidepressant Effects of (Arcangelisia flava (l.) Merr) Water-Soluble Extract in Balb-C Mice Reviewed from Immobility Time by Forced

This study was conducted to examine / determine the antidepressant effects of (Arcangelisiaflava L.) on immobility time of the white male mice strain Balb-c by the forced swim test method. The method of research using laboratory animals such as 25 micewas divided into 5 groups. As a negative control group was only given distilled water ad libitum. Amitryptiline was used as the positive control group; the experiment group was a water-soluble extract of A.flava by  multiple doses. The results showed that the best antidepressant effects were312 mg/kgBW ; it had a minimum of immobility time compared with the other groups

Identification of active anti-inflammatory principles of betabeta wood (Lunasia amara Blanco) from Siawung Barru- South Sulawesi, Indonesia

Purpose: To identify the anti-inflammatory components of beta-beta (Lunasia amara Blanco.) wood.Methods: The wood material was extracted with 96 % ethanol and fractionated with dichloromethane using a liquid-liquid continuous extraction (LLCE). The fractions were subjected to silica gel column chromatography. Components of the extracts were identified by thin layer chromatography (TLC) scanner and UV-visible spectroscopy, using scopoletin as standard.Results: TLC results for Lunasia amara extract showed the same spot as standard scopoletin. UVvisible spectrum for scopoletin displayed maximum absorption at 213, 228, 255 and 344 nm, while betabeta wood extract showed characteristic bands at 344, 336, 299 and 255 nm. The results indicate that the main components of the extracts are scopoletin and its derivatives.Conclusion: The active anti-inflammatory compound in beta-beta (Lunasia amara) wood is scopoletin.Keywords: Beta-beta wood (Lunasia amara Blanco.), Scopoletin, Thin layer chromatograph

Study on the Making of Blended Cement by Mixing Granulated Blast Furnace Slag with Portland Cement Clinker

Abstract. This paper presents the results of laboratory into the effect of slag fineness and slag composition added to portland cement clinker, to the compressive strength of the paste. The results showed that slag of 4260 cm2/gram fineness can be added up to 3O% to a portland cement clinker to increase compressive strength from 28 MPa to about 40 MPa. Scanning electron micrograph of the pastes showed that the inter granular voids between slag particles and sand particles were densely filled with line CaO-SiO2-H2O gel after 28 days observation, and in case clinker without slag, densification of CaO-SiO2-H2O gel still left pores even after 23 days of observation. The fineness of slag is more important than its composition in the blended cement. Studi Pembuatan Semen Campur (Blended Cement) dari Campuran Terak Tanur Tiup dan Klinker Semen PortlandSari. Paper ini menyajikan hasil percobaan laboratorium yang meneliti pengeruh kehalusan terak dan komposisi terak yang ditambahkan ke dalam klinker semen Portland. Hasil percobaan menunjukkan bahwa terak dengan kehalusan 4260 cm2/gram dapat ditambahkan ke dalam klinker sampai maksimum 30%, untuk meningkatkan kuat tekan dari semula 28 Mpa menjadi 40 Mpa. Foro SEM menunjukkan bahwa kekosongan antarbutir partikel terak dengan partikel pasir terisi dengan baik oleh pasta halus CaO-SiO2-H2O setelah pengamatan selama 28 hari. Untuk klinker tanpa terak, pasta masih mempunyai pori mesipun setelah 28 hari pengamatan. Kehalusan terak lebih penting daripada komposisinya di dalam semen campur

Indonesian Automatic Speech Recognition For Command Speech Controller Multimedia Player

The purpose of multimedia devices development is controlling through voice. Nowdays voice that can be recognized only in English. To overcome the issue, then recognition using Indonesian language model and accousticc model and dictionary. Automatic Speech Recognizier is build using engine CMU Sphinx with modified english language to Indonesian Language database and XBMC used as the multimedia player. The experiment is using 10 volunteers testing items based on 7 commands. The volunteers is classifiedd by the genders, 5 Male & 5 female. 10 samples is taken in each command, continue with each volunteer perform 10 testing command. Each volunteer also have to try all 7 command that already provided. Based on percentage clarification table, the word “Kanan†had the most recognize with percentage 83% while “pilih†is the lowest one. The word which had the most wrong clarification is “kembali†with percentagee 67%, while the word “kanan†is the lowest one. From the result of Recognition Rate by male there are several command such as “Kembaliâ€, “Utamaâ€, “Atas “ and “Bawah†has the low Recognition Rate. Especially for “kembali†cannot be recognized as the command in the female voices but in male voice that command has 4% of RR this is because the command doesn’t have similar word in english near to “kembali†so the system unrecognize the command. Also for the command “Pilih†using the female voice has 80% of RR but for the male voice has only 4% of RR. This problem is mostly because of the different voice characteristic between adult male and female which male has lower voice frequencies (from 85 to 180 Hz) than woman (165 to 255 Hz).The result of the experiment showed that each man had different number of recognition rate caused by the difference tone, pronunciation, and speed of speech. For further work needs to be done in order to improving the accouracy of the Indonesian Automatic Speech Recognition system.Keywords: Automatic Speech Recognizer, Indonesian Acoustic Model, CMU Sphinx, indonesian Language Model, Recognition Rate, XBMC

Relation Between the Constitutional Court of the Republic of Indonesia and the Legislators According to the 1945 Constitution of the Republic of Indonesia

This research aims to analyze and to describe the relation between the Constitutional Court of the Republic of Indonesia (CC) with the People Representatives' Council and the President of the Republic of Indonesia as legislators by looking on implementation of CC's decision through the legislation in the period 2004-2015. Using doctrinal research, it can be seen how the constitutional mandate in the CC's decision are implemented by the legislator through the legislation. The results are: (a) legal opinions of the CC's decision have a binding power; (b) a constitutional mandate in the legal opinion is intended as guidance for the legislators regarding what the 1945 Constitution requires; (c) directives to the legislator in the legal opinions should be implemented because it is the implementation of the principle of checks and balances according to the 1945 Constitution, (d) implementation of the CC's decisions through legislation does not have standard mechanism and does not become the priority of legislation, and (e) relation between the CC with the legislators can not be categorized in black and white in cooperative or confrontative, but shows ups and downs between cooperative and confrontative relations. Cooperative relations are realized when the constitutional mandate is formulated strongly so it is implemented by the legislator as the formula. Relationships tend to be cooperative in the implementation of the constitutional mandate of the decision, but not a priority of legislation. Meanwhile, the confrontative relations is seen from the constitutional mandate of the CC decisions which are not implemented

Development of Android-Based Student Performance Tool (Tunersindro) to Improve Work Readiness of Vocational High School Students

Work readiness has an effect on the unemployment rate for Vocational High School (SMK) graduates. Work readiness can be improved by improving learning patterns and tools. This study aims to develop learning aids, test the feasibility and effectiveness of the product. The research design used is the ADDIE Research Development (R&D) design with the stages of Analysis, Design, Development or Production, Implementation or Delivery and Evaluations. The research site is at SMK Muhammadiyah 2 Tempel with research subjects of 134 students, 14 teachers of Automotive Engineering Vocational School and 5 automotive industry practitioners. Data collection techniques used were questionnaires and tests with interview research instruments, media and product questionnaires and practice test sheets. Android-based student performance aids (Tunersindro) have a very high feasibility of being used in vocational learning. Not only that, with two trials, Tunersindro has a very high level of effectiveness in increasing the work readiness of SMK students Keywords: Improving Work Readiness, Students Performance Aid, Development Tool Tunersindr

MODEL EXPLICIT INSTRUCTION: STRATEGI EFEKTIF UNTUK PRESTASI PRAKTIK SISWA SMK OTOMOTIF

Keterampilan praktik memainkan peran krusial dalam mempersiapkan lulusan SMK menghadapi tantangan di dunia kerja. Untuk meningkatkan prestasi belajar dalam keterampilan praktik, diperlukan strategi pembelajaran yang efektif. Penelitian ini bertujuan untuk mengevaluasi penerapan model pembelajaran Explicit Instruction pada siswa SMK jurusan Teknik Kendaraan Ringan (TKR), dengan fokus pada peningkatan prestasi praktik siswa. Melalui metode penelitian tindakan kelas, 25 siswa dari SMK Muhammadiyah 1 Pakem yang mengambil jurusan teknik otomotif menjadi subjek penelitian. Data dikumpulkan menggunakan lembar kinerja praktik yang diverifikasi oleh industri. Hasil penelitian menunjukkan bahwa model pembelajaran Explicit Instruction dapat diimplementasikan secara efektif oleh siswa, dengan terjadi peningkatan signifikan dalam rata-rata skor kompetensi keterampilan praktik setiap kali siklus penelitian dilakukan. Aspek persiapan kerja meningkat dari 1,4 di siklus pertama menjadi 2,3 di siklus kedua dan 3,8 di siklus ketiga. Sementara itu, aspek kompetensi pengetahuan kerja meningkat dari 1,6 di siklus pertama menjadi 2,2 di siklus kedua dan 3,4 di siklus ketiga. Aspek kompetensi keterampilan kerja juga mengalami peningkatan dari 1,5 di siklus pertama menjadi 1,8 di siklus kedua dan 3,2 di siklus ketiga

Developing learning and training within industry model to improve work readiness of vocational high school students

Unemployment is still a national priority that needs to be addressed. In 2022, vocational high schools in Indonesia had the highest open unemployment rate. The highest open unemployment rate is a result of vocational high school students’ insufficient work readiness. Therefore, this research aims to develop a learning and training within industry (LTWI) model, and to evaluate the model’s efficacy in increasing vocational high school students’ work readiness. The research employed a research and development (R&D) design by Richey and Klein with the phases of needs analysis, internal validation, and external validation. There were 12 teachers and 89 students from the automotive engineering department at Muhammadiyah 1 Pakem Vocational High School and 1 Puring Vocational High School, as well as six instructors from the automotive industry: GAS Auto Service, Automotive Jogjakarta Center (OJC), Bengkel Barokah, and RND Auto Service, participated in the research. Data collection strategies adopted were interviews, questionnaires, and performance tests. The data were descriptively evaluated, and the conclusions were drawn using a categorization formula. With an average score of 3.43, the LTWI model can be used to learn very well. With an average final score of 3.32, the efficacy of the LTWI learning model falls into the category of “very good”. The LTWI model can be applied effectively to learning in vocational high schools since it has a positive influence on students’ work readiness