1,720,957 research outputs found
Biosensor Superoksidamenggunakan Ekstrak Protein Deinococcus Radiodurans Diimobilisasi Dengan Ikat Silang Glutaraldehid.
No full textAntioksidan sangat diperlukan oleh tubuh manusia, pada dasarnya tubuh
manusia memiliki antioksidan endogen yaitu enzim katalase, peroksidase,
superoksida dismutase (SOD), dan glutationa S-transferase. Namun jika terjadi
paparan radikal bebas yang berlebih ke dalam tubuh, diperlukan antioksidan
eksogen yang biasanya bersumber dari makanan dan bahan alam. Kapasitas
antioksidan adalah kemampuan suatu bahan dalam mengukur senyawa penangkal
radikal bebas. Pengukuran antioksidan menggunakan metode spektrofotometri
terkendala dalam preparasi sampel dan memerlukan waktu pengukuran yang lama.
Oleh karena itu, dibutuhkan metode yang lebih mudah, akurat, cepat, dan sensitif
dalam penentuan kapasitas antioksidan seperti metode biosensor.
Biosensor superoksida menggunakan ekstrak protein dari mikroba
Deinococcus radiodurans yang diimobilisasi pada matriks karboksimetilselulosagelatin-
zeolit diikat silang glutaraldehid (CMC-G-Z-glutaraldehid) merupakan
salah satu cara untuk mengoptimumkan kinerja biosensor Superoksida sehingga
dapat digunakan secara efektif. Tujuan penelitian ini adalah menghasilkan
stabilitas yang lama.
Ekstrak protein dilisis dari D. radiodurans menggunakan metode
ultrasonikasi yang menghasilkan konsentrasi protein 1774.89 ppm. Proses
penghancuran dinding sel dibantu dengan penyinaran sinar UV yang berfungsi
untuk inisiasi protein SOD sehingga mampu ekstrak protein keluar dari inti sel.
Ekstrak protein diimobilisasi pada elektroda pasta karbon dengan CMC-gelatinzeolit
diikat silang glutaraldehid. Biosensor ini dilakukan optimasi dengan variasi
konsentrasi zeolit, konsentrasi glutaraldehid, konsentrasi ekstrak protein dan pH
menggunakan software Minitab metode respon surface methode.
Hasil dari optimasi biosensor yang diperoleh yaitu konsentrasi zeolit 5
mg/ml, konsentrasi glutaraldehid 0.005M, konsentrasi ekstrak protein 1075 ppm
dan pH 7. Hasil optimasi tersebut digunakan untuk mengukur kinerja analitik dari
biosensor yang meliputi stabilitas, limit deteksi, limit kuantisasi dan linieritas.
Pengujian stabilitas elektroda dengan ikat silang glutaraldehidmenghasilkan waktu
stabilitas selama 24 jam dengan sisa aktivitas 67.74%, sedangkan elektroda tanpa
ikat silang glutaraldehid bertahan selama 12 jam dengan sisa aktivitas 65.66%.
Pengujian limit deteksi dengan elektroda pada CMC-G-Z-glutaraldehid dihasilkan
sebesar 77.84 μM, dan limit kuantisasi sebesar 259.5 μM. Linieritas dihasilkan
rentang pengukuran 0.1-0.8 mM xantina dengan persamaan y = 1.5549x + 0.1617
dan r2 = 0.9905. Penggunaan ekstrak protein dari D. radiodurans dimobilisasi
dalam matriks CMC-G-Z dengan ikat silang oleh glutaraldehid dapat menjadi
biosensor superoksida alternatif untuk pengujian rutin dan dapat dikembangkan
sebagai prototipe
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
PENGARUH KONSENTRASI Na2CO3 TERHADAP RENDEMEN NATRIUM ALGINAT DAN KANDUNGAN PROKSIMAT ALGINAT DARI RUMPUT LAUT Sargassum sp.
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