1,720,957 research outputs found
Ekstraksi Lilin Tebu (Saccharum officinarum L.) dari Blotong dengan Metode Ultrasonik dan Saponifikasi Lilin dalam Menghasilkan Polikosanol
No full textLilin tebu ( Saccharum officinarum L.) telah menjadi perhatian karena memiliki kandungan senyawa polikosanol yang bermanfaat untuk kesehatan sebagai penurun kadar kolesterol dan menghambat sintesis kolesterol. Ekstraksi dengan metode ultrasonik dikenal lebih cepat dengan hasil yang tinggi. Namun demikian ekstraksi lilin tebu menggunakan metode ultrasonik belum pernah dilaporkan.
Tujuan penelitian ini untuk mempelajari proses ekstraksi lilin tebu dari blotong menggunakan ultrasonik dan mempelajari pengaruh saponifikasi lilin tebu terhadap perolehan hasil polikosanol.
Penelitian ini terdiri dari tiga tahap. Penelitian tahap I adalah ekstraksi lilin tebu secara ultrasonik dipelajari pengaruh jenis pelarut (propanol, butanol, benzol, toluena, iso-oktana) dan waktu ekstraksi (10, 20 dan 30 menit) terhadap perolehan lilin tebu dan kandungan polikosanol. Analisis kandungan polikosanol dilakukan dengan kromatografi lapis tipis. Data penelitian diolah dengan statistik menggunakan analisis sidik ragam dalam Rancangan Acak Lengkap dengan faktorial dalam dua kali ulangan dilanjutkan uji Beda Nyata Terkecil (BNT).
Penelitian tahap II adalah saponifikasi lilin tebu dipelajari pengaruh jenis basa (NaOH, KOH, Ba(OH) 2 ) dan waktu reaksi (30, 60 dan 90 menit) terhadap perolehan rendemen dan polikosanol. Analisis kandungan polikosanol dilakukan dengan kromatografi gas. Analisis gugus fungsional dari lilin tebu diamati dengan spektroskopi infra merah (FTIR). Data penelitian diolah dengan statistik menggunakan analisis sidik ragam dalam Rancangan Acak Lengkap dengan faktorial dalam dua kali ulangan dilanjutkan uji Beda Nyata Terkecil.
Penelitian tahap III adalah ekstraksi polikosanol dari lilin tak tersaponifikasi menggunakan etilmetil keton dipelajari fraksi ekstraksi, jenis basa (NaOH, KOH, Ba(OH) 2 ) dan waktu saponifikasi (30, 60 dan 90 menit) terhadap perolehan rendemen dan polikosanol. Ekstraksi dilakukan menggunakan etilmetil keton untuk mengetahui distribusi polikosanol sebagai dasar untuk pemurniannya. Analisis kandungan polikosanol dilakukan dengan kromatografi gas. Data penelitian diolah dengan statistik menggunakan analisis sidik ragam dalam Rancangan Acak Lengkap dengan faktorial dalam dua kali ulangan dilanjutkan uji jarak Duncan.
Hasil penelitian Tahap I. Jenis pelarut berpengaruh beda nyata terhadap perolehan rendemen lilin tebu dan polikosanol. Semakin meningkat waktu ekstraksi semakin meningkat perolehan rendemen lilin tebu dan kadar polikosanol. Waktu ekstraksi memberikan pengaruh yang beda nyata terhadap rendemen lilin tebu. Perlakuan terbaik ekstraksi lilin tebu dari blotong secara ultrasonik pada penelitian ini menggunakan pelarut toluena, waktu ekstraksi 30 menit menghasilkan rerata rendemen lilin tebu 8,16% dan rerata kadar polikosanol diperoleh 43,79%.
Hasil penelitian Tahap II. Hidrolisis ester menggunakan basa NaOH dan KOH lebih baik daripada Ba(OH) 2 . Proses reaksi saponifikasi lilin tebu dapat diamati dengan analisis FTIR. Saponifikasi lilin tebu dapat meningkatkan kadar oktakosanol sebesar 4,60% dari 2,82% menjadi 7,42%. Kadar polikosanol meningkat 6,32% dari 24,04% menjadi 30,36% akibat saponifikasi. Kondisi perlakuan terbaik untuk saponifikasi lilin tebu pada penelitian ini menggunakan basa NaOH dengan waktu reaksi 90 menit berturut-turut menghasilkan rerata rendemen 59,74%, rerata kadar polikosanol 32,47% dan rerata kadar oktakosanol 10,34%.
Hasil penelitian Tahap III. Ekstraksi lilin tak tersaponifikasi dengan etilmetil keton dapat meningkatkan rerata kandungan polikosanol dari 35,75% menjadi 43,51%. Polikosanol cenderung berada pada fraksi terlarut dalam pelarut etilmetil keton
Production of Fatty Acid Methyl Ester Surfactants using Palm Oil with Various Reaction Temperatures and Duration
Full text linkMost surfactants are made from petrochemicals, posing significant environmental concerns due to the non- biodegradable and non-renewable nature. To address this challenge, surfactants from biodegradable, non-toxic, and harmless materials are required, such as Fatty Acid Methyl Ester (FAME) derived from palm oil. Therefore, this research aimed to investigate the effect of reaction tempetarures and durations as well as the interactions on the yield of FAME surfactants. The characteristics of the highest yield of FAME surfactants were also examined, including HLB (hydrophilic-lipophilic balance) value, surface tension, CMC (critical micelles concentration), density, and pH values. The study was conducted using Completely Randomized Factorial Design with three (3) factors, namely temperature (50 and 60 °C), reaction duration (60, 90, and 120 minutes), and the interaction. The results showed that the highest yield of 82.43% was produced at an interaction reaction temperature of 60 °C and a duration of 120 minutes. The characteristics of surfactants obtained were HLB value of 5.47, surface tension of 30.49 dyne/cm, capable of reducing surface tension by 73.20% (from 72.80 to 19.52 dyne/cm), CMC, density and pH values of 1.50% (v/v), 0.8757 g/cm 3 , and 6.86, respectively. These characteristics suggested that FAME has the potential for application as a water-in-oil (w/o) emulsifier. Moreover, the results could be applied to produce biodegradable surfactants using tropical oils through easy and simple technology
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
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
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