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Sintesis N-palmitoiletanolamida dan Kinerjanya sebagai Antioksidan dengan Metode Penyapuan Radikal DPPH.
No full textN-palmitoiletanolamida adalah senyawa amida lemak yang dapat digunakan sebagai surfaktan, aditif pelumas, dan lainnya. Tujuan penelitian ini adalah menguji kinerjanya sebagai antioksidan menggunakan metode penyapuan radikal (DPPH) serta menentukan kinetika reaksinya. N-palmitoiletanolamida disintesis dari reaksi esterifikasi dan amidasi dengan rendemen 79%. Persen penyapuan DPPH naik dari 27% menjadi 30%, serta penyapuan oleh standar (BHT) naik dari 40% menjadi 59%. Hasil ini menunjukkan bahwa hasil sintesis dapat berfungsi baik sebagai antioksidan meskipun belum lebih baik daripada standar BHT dalam menyapu radikal DPPH. Evaluasi kinetika reaksinya menunjukkan bahwa N-palmitoiletanolamida dengan konsentrasi setara mengikuti orde reaksi ke-2 dengan tetapan laju reaksi (k2) 306 M-1 menit-1, dengan konsentrasi berlebih mengikuti orde pertama semu dengan tetapan laju reaksi (k1) 0.0095 menit-1
Sintesis dan Karakterisasi Membran Polistirena Terfluorinasi untuk nnnnnnnDirect Methanol Fuel Cell
No full textOne of common energy resources is direct methanol fuel cell (DMFC), which use methanol as fuel. The important component in DMFC is proton exchange membrane. The study used fluorinated polystyrene membrane (PSf) as proton exchange membrane through fluorination process. PSf membrane was made with PSf concentration of 5%, 10%, and 15 %. Fluorination has caused change of membrane physical properties with presence of pores in the membranes. The best water uptake was shown by PSf 5% that is 11.07%. Membrane activation increased the proton conductivity from 0.52 × 10-7 S/cm to 0.54 × 10-7 S/cm for polysryrene (PS) and 0.44 × 10-7 S/cm to 0.69× 10-7 S/cm for the PSf. Qualitative test of methanol permeability showed good result with dry underneath the surface of membrane because methanol did not pass through the membrane. In DMFC system, proton conductivity of the PSf membrane is higher than that of PS membrane, while variation of conductivity from PSf membranes is caused by gaps at the PSf membranes
Etanolamida Asam Lemak Minyak Sawit Mentah sebagai Inhibitor Korosi dengan Teknik Polarisasi Potensiodinamik
No full textEtanolamida disintesis dari asam lemak minyak sawit melalui proses
esterifikasi dan amidasi menggunakan katalis NaOMe dan NaOEt. Asam lemak
dapat dikonversi menjadi ester dengan baik sebesar 98.87% dengan kandungan
ester sebesar 93.87%. Pencirian produk etanolamida dengan menggunakan HPLC,
menunjukkan perbedaan profil kromatogram antara ester dengan etanolamida,
menghilangnya puncak ester pada kromatogram etanolamida menunjukan bahwa
produk amida telah terbentuk. Analisis gugus fungsi dengan menggunakan
spektrofotometer inframerah terdapat pita serapan amida yang khas pada bilangan
gelombang 3296 cm-1 (N−H), 1643 cm-1 (C=O), 1563 cm-1 (C−N), 1466 cm-1, dan
1379 cm-1. Uji kinerja antikorosi mengunakan potensiostat dengan variasi
konsentrasi inhibitor menunjukkan hubungan bahwa peningkatan konsentrasi
larutan amida menyebabkan penurunan arus korosi dan peningkatan efektivitas
inhibisi
Sintesis N-Oleoiletanolamida dan Uji Kinerjanya sebagai Inhibitor Korosi dengan Teknik Polarisasi Potensiodinamik.
No full textN-oleoiletanolamida dapat digunakan sebagai inhibitor korosi. Inhibitor ini disintesis melalui esterifikasi asam oleat dengan metanol lalu amidasi metil oleat dengan monoetanolamina. Asam oleat diamidasi dengan dua jenis katalis, yaitu NaOMe dan NaOEt, menghasilkan rendemen berturut-turut 82.9% dan 75.8%. Hasil amidasi kemudian dicirikan gugus fungsinya berdasarkan spektrum inframerah, untuk mengidentifikasi adanya gugus amida hasil konversi ester oleat dan N-oleoiletanolamida. Kinerja inhibitor korosi diuji dengan teknik polarisasi potensiodinamik menggunakan tiga jenis konsentrasi, yaitu 50, 100, dan 200 ppm terhadap elektrode kerja baja karbon. Hasil pengukuran menunjukkan bahwa N-oleoiletanolamida dengan katalis NaOMe dan NaOEt memiliki efektivitas inhibitor berturut-turut 64.4% dan 58.7%
Perubahan Struktur Fenantrena Selama Proses Biodegradasi oleh Bakteri Bacillus altitudinis
No full textPolycyclic aromatic hydrocarbons (PAHs) are toxic, mutagenic, and carcinogenic pollutants that are present in environment. Some bacterial species have ability to metabolize these compounds and use them as energy sources for their growth. Bacillus altitudinis was used to degrade phenanthrene, a three-ring aromatic PAH. The maximum degradation rate (14%) was obtained when Bacillus altitudinis was cultured for 28 days after the addition of 50 ppm phenanthrene to the liquid medium. Furthermore, the degradation was affected by addition of Tween 80 as surfactants. The observation parameters were total plate count (TPC) and pH. The value TPC increased for 28 days cultivation and pH value increased too from 6 to 8 during the 28 days cultivation. The mechanism of degradation was determined through identification of metabolites, the possible pathway of phenanthrene degradation is via phthalic acid. It has been proofed by a mass spectrum of phthalic acid at retention time of 7.607 with match quality of 72
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
Konversi Asam Stearat dan Asam Oleat Menjadi Senyawa Oksazolina dengan Katalis Zeolit Teraktivasi Berbantuan Gelombang Mikro.
No full textOksazolina adalah senyawa heterosiklik dengan R tertentu dapat digunakan
sebagai antikorosi karena mempunyai kerapatan elektron yang tinggi sehingga
dapat terabsorpsi kuat pada permukaan logam. Penelitian ini bertujuan
menyintesis senyawa 2-heptadesil-4,5-dihidrooksazol dan (Z)-2-heptades-8-en-1-
il-4,5-dihidrooksazol dengan melakukan konversi dari asam stearat dan asam oleat
menggunakan aminoalkohol sebagai reagen dan zeolit teraktivasi sebagai katalis
berbantuan gelombang mikro pada beragam daya. Daya optimum ialah 300 W.
Rendemen yang diperoleh yaitu 55% untuk senyawa (Z)-2-heptades-8-en-1-il-4,5-
dihidrooksazol dan 6,5% untuk senyawa 2-heptadesil-4,5-dihidrooksazol. Stuktur
oksazolina dicirikan berdasarkan spektrum inframerah yang menghasilkan pita
spektrum baru pada bilangan gelombang 1650 cm-1 dan 1044 cm-1, masingmasing
untuk gugus fungsi imina dan eter, selanjutnya dicirikan dengan teknik
resonansi magnetik inti
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
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