1,720,954 research outputs found
Pembuatan Biodiesel dari Ulat Jerman (Zophobas morio L.) dengan Metode Transesterifikasi Langsung Menggunakan Pelarut N-Heksana Metanol
Full text linkAbstrak
Penelitian ini bertujuan untuk mengetahui waktu reaksi optimum pembuatan biodiesel dari ulat jerman (Zophobas morio L.) menggunakan katalis H2SO4 dengan metode transesterifikasi langsung. Variasi yang dilakukan adalah waktu reaksi 8, 12, 16, dan 20 jam pada dua kondisi berbeda (perbandingan pelarut n-heksana metanol 1:2 dan 1:5). Hasil dari penelitian inimenunjukkan belum ditemukan waktu optimum pada kedua kondisi. Ditemukan kondisi produk biodiesel paling berpotensi yang telah memenuhi dua dari tiga parameter standar biodiesel yaitu pada kondisi perbandingan pelarut n-heksana metanol 1:5 dengan waktu reaksi 20 jam menghasilkan 20mL biodiesel, densitas 0,8950 g mL-1, viskositas kinematik 12,17 cSt, dan bilangan asam 0,41 mg KOH/g sampel. Berdasarkan uji GC-MS pada biodiesel paling berpotensi didapatkan 4 jenis metil ester yaitu metil palmitat, metil palmitoleat, metil linoleat dan metil stearat.
Kata kunci: Biodiesel, metil ester, transesterifikasi langsung, ulat jerman
Abstract
The aims for this studies was to determine the optimum reaction time of biodiesel from superworm (Zophobas morio L.) using H2SO4 catalyst by direct transesterification method. Reaction times 8, 12, 16, and 20 hours in two different conditions (comparison of hexane-methanol solvents 1:2 and 1:5) were investigated. The results of this study have not yet found optimal time in both conditions. It was found that the most potential condition of biodiesel products had fulfilled two of the three standard biodiesel parameters, was the condition of the comparison of hexane-methanol 1:5 solvents with a reaction time of 20 hours producing 20 mL biodiesel, density 0.8950 g mL-1, kinematic viscosity 12.17 cSt, and acid number 0,41 mg KOH/g sample. The GC-MS result showed the methyl ester from biodiesel product are contains methyl palmitate, methyl palmitoleate, methyl linoleic, and methyl stearat
Keywords: Biodiesel, direct transesterification, methyl ester, superwor
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Pembuatan Biodiesel Dari Minyak Biji Alpukat (Persea americana) Melalui Proses Transesterifikasi Langsung
Full text linkAbstrak
Penelitian ini bertujuan untuk menentukan kondisi optimum pembuatan biodiesel dari minyak biji alpukat melalui proses transesterifikasi langsung. Variasi yang digunakan pada penelitian ini adalah variasi waktu reaksi 8, 12, 16 dan 20 jam serta variasi perbandingan campuran heksana-metanol 1:2 dan 1:5. Katalis yang digunakan adalah H2SO4 sebesar 20% berat yang diimpregnasi ke dalam serbuk biji alpukat. Hasil penelitian menunjukkan kondisi optimum pembuatan biodiesel dari biji alpukat adalah pada waktu reaksi 16 jam dengan perbandingan campuran heksana-metanol 1:5. Volume akhir biodiesel yang didapatkan sebesar 1,6 mL dengan densitas sebesar 910,7 kg m-3, viskositas kinematik sebesar 3,3051 cSt dan bilangan asam 1,9418 mg KOH g-1 lemak. Berdasarkan analisis GC-MS produk biodiesel dari kondisi optimum yang berhasil terkonversi adalah metil palmitat
Kata kunci: biji alpukat, biodiesel, metil ester, transesterifikasi langsung
Abstract
The aim of this study was to determine the optimum conditions of making biodiesel from avocado seed oil through a direct transesterification process. The variations used in this study were reaction time of 8, 12, 16 and 20 hours and hexane-methanol mixture of 1:2 and 1:5. The catalyst used was H2SO4 of 20% (wt) that has been impregnated into avocado seed powder. The results showed that the optimum conditions for making biodiesel from avocado seeds were at the reaction time of 16 hours with a hexane-methanol mixture ratio of 1:5. The final volume of biodiesel was 1.6 mL with a density of 910.7 kg m-3, kinematic viscosity of 3.3051 cSt and acid number 1.9418 mg KOH g_1. Based on GC-MS analysis of biodiesel products from the optimum conditions the resulted of fatty acid methyl ester is methyl palmitate.
Keywords: avocado seeds, biodiesel, direct transesterification, methyl ester
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
- …
