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Pengaruh Penambahan Aditif dan Waktu Perendaman pada Pembuatan Membran Cellulose Acetate dan Polyethersulfone untuk Aplikasi Pemisahan Mikroplastik dalam Air
No full textPlastik erat kaitannya dengan keseharian masyarakat Indonesia. Sampah plastik di Indonesia mencapai 64 juta ton/tahun dimana 3,2 juta ton di antaranya merupakan sampah plastik yang dibuang ke laut. Dengan membutuhkan waktu yang lama, plastik akan terdekomposisi menjadi mikroplastik (MPs) dengan diameter kurang dari 5 mm, yang dimana MPs dalam matriks air menimbulkan beberapa kerugian. Salah satu metode penghilangan MPs yang dinilai efisien yaitu mikrofiltrasi MPs menggunakan teknologi membran. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh penambahan aditif dan waktu perendaman terhadap karakteristik dan kinerja membran penghilang MPs. Dalam penelitian ini, proses pembuatan membran menggunakan polimer Cellulose Acetate (CA) dan Polyethersulfone (PES), pelarut N-methyl-2-pyrrolidone (NMP), dan bahan aditif Polyvinyl Pyrrolidone (PVP) dengan metode inversi fasa. Hasil dari penelitan ini menunjukkan bahwa seiring bertambahnya waktu perendaman, nilai PWF dan rejeksi MPs semakin menurun karena ukuran diameter pori yang semakin menurun pula. Penambahan aditif PVP 10K dan 40K menyebabkan sifat membran menjadi hidrofilik sehingga dapat meningkatkan kinerja dari membran dalam memisahkan MPs. Membran PES dengan PVP 40K sebanyak 4%, waktu perendaman selama 10 menit dan suhu penguapan 60⁰C memiliki hasil PWF optimum. Sedangkan nilai rejeksi MPs optimum dicapai pada membran PES dengan penambahan PVP 40K sebanyak 4%, waktu perendaman selama 25 menit dan suhu penguapan 30⁰C.
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Plastic is closely related to the daily lives of Indonesians. Plastic waste in Indonesia reaches 64 million tonnes/year of which 3.2 million tonnes are plastic waste disposed into the sea. By taking a long time, plastic will decompose into microplastics (MPs) with a diameter of less than 5 mm, which MPs in the water matrix cause several losses. One method of MPs removal that is considered efficient is MPs microfiltration using membrane technology. The purpose of this study was to determine the effect of additive addition and immersion time on the characteristics and performance of MPs removal membrane. In this study, the membrane manufacturing process used Cellulose Acetate (CA) and Polyethersulfone (PES) polymers, N-methyl-2-pyrrolidone (NMP) solvent, and Polyvinyl Pyrrolidone (PVP) additive by phase inversion method. The results showed that as the immersion time increased, the PWF and rejection values of MPs decreased due to the decreasing pore diameter size. The addition of PVP 10K and 40K additives causes the membrane properties to be hydrophilic so as to improve the performance of the membrane in separating MPs. PES membrane with PVP 40K as much as 4%, immersion time for 10 minutes and evaporation temperature of 60⁰C has optimum PWF results. While the optimum MPs rejection value was achieved in PES membrane with the addition of PVP 40K as much as 4%, immersion time for 25 minutes and evaporation temperature of 30⁰C
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Optimasi Kolom Absorber Dan Stripper Pada Pabrik Karbon Disulfida Dengan Proses Hidrokarbon-Sulfur
No full textBerdasarkan data dari Badan Pusat Statistik Indonesia dari tahun 2014 hingga tahun tahun 2020 menunjukkan bahwa kebutuhan karbon disulfida yang tinggi di Indonesia dan produksi dalam negeri yang tidak mencukupi, maka akan didirikan pabrik karbon disulfida dengan kapasitas 20.000 ton/tahun dengan bahan baku sulfur dan metana. Pabrik karbon disulfida ini direncanakan akan didirikan pada tahun 2025 yang berlokasi di Brangsong Utara, Kecamatan. Brangsong, Kabupaten Kendal, Jawa Tengah dengan kapasitas 20.000 ton/tahun dan beroperasi secara kontinyu selama 330 hari kerja/tahun dan 24 jam/hari. Pabrik karbon disulfida akan menggunakan proses hidrokarbon-sulfur yang terdiri dari empat tahap. Tahap pertama adalah tahap pre-treatment yaitu proses pengkondisian sulfur dan natural gas agar sesuai dengan kondisi operasi dalam reaktor. Tahap kedua yaitu tahap reaksi yaitu reaksi untuk menghasilkan karbon disulfida dan hidrogen sulfida. Tahap ketiga adalah tahap separasi yaitu pemisahan sulfur untuk direcycle dan karbon disulfida untuk dimurnikan lebih lanjut. Tahap terakhir adalah tahap pemurnian karbon disulfida yaitu proses mengurangi kadar hidrogen sulfida dalam karbon disulfida. Bahan baku yang dibutuhkan dalam proses produksi karbon disulfida adalah natural gas sebanyak 14.095,789 kg/hari, sulfur padat sebanyak 106.934,002 kg/hari, MEA sebanyak 0,5856 kg/hari, dan silika gel sebanyak 370,166 kg/tahun. Efisiensi dan optimasi proses yang dilakukan yaitu pemilihan jenis tray pada kolom absorber dan stripper. Metode yang dilakukan dengan pendekatan parameter yaitu mempertimbangkan beberapa parameter seperti flooding, entrainment, serta maintenance pada tray jenis bubble cap dan sieve tray tipe aliran cross flow, reverse flow, dan double pass flow. Dari hasil pemilihan didapatkan bahwa jenis kolom tipe sieve tray dengan tipe aliran reverse flow menghasilkan nilai flooding dan entrainment yang memenuhi syarat serta biaya maintenance lebih ekonomis. Analisa ekonomi didapatkan yaitu Internal Rate of Return (IRR) sebesar 44%, Pay Out Time (POT) selama 3,41 tahun, Net Present Value (NPV) sebesar Rp. 1.727.651.316.575,00 dan Break Event Point (BEP) sebesar 5,62%
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Based on data from the Indonesian Central Bureau of Statistics from 2014 to 2020 showing that the demand for carbon disulfide is high in Indonesia and domestic production is insufficient, thus a carbon disulfide plant will be established with a capacity of 20,000 tons/year with sulfur and methane as raw materials. This carbon disulfide plant is planned to be established in 2025 which is located in North Brangsong, District. Brangsong, Kendal Regency, Central Java with a capacity of 20,000 tons/year and operates continuously for 330 working days/year and 24 hours/day. The carbon disulfide plant will use a four-step hydrocarbon-sulfur process. The first stage is the pre-treatment stage, namely the process of conditioning sulfur and natural gas to suit the operating conditions in the reactor. The second stage is the reaction stage, namely the reaction to produce carbon disulfide and hydrogen sulfide. The third stage is the separation stage, namely the separation of sulfur for recycling and carbon disulfide for further purification. The last stage is the carbon disulfide purification stage, which is the process of reducing the hydrogen sulfide content in carbon disulfide. The raw materials needed in the carbon disulfide production process are natural gas is 14,095,789 kg/day, solid sulfur is 106,934,002 kg/day, MEA is 0.5856 kg/day, and silica gel is 370,166 kg/year. Efficiency and optimization of the process carried out by selecting the type of tray on the absorber and stripper columns. The method used is a parameter approach, which considers several parameters such as flooding, entrainment, and maintenance on bubble cap and sieve trays with cross flow, reverse flow, and double pass flow. From the results of the selection, it was found that the sieve tray type column with the reverse flow flow type resulted in flooding and entrainment values that met the requirements and maintenance costs were more economical. Economic analysis is obtained, namely the Internal Rate of Return (IRR) is 44%, Pay Out Time (POT) is 3,41 years, Net Present Value (NPV) is Rp. Rp 1.727.651.316.575,00 and Break Event Point (BEP) is 5,62
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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