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Perubahan Sifat Kimia Kayu Kapuk Terdensifikasi Akibat Perlakuan Pendahuluan Alkali
No full textDensifikasi pada kayu kapuk merupakan salah satu upaya untuk meningkatkan sifat fisis dan mekanis kayu dengan stabilisasi dimensi kayu yang tetap. Masalah yang sering ditemukan pada produk kayu terdensifikasi adalah kembalinya dimensi kayu terpadatkan ke dimensi awal (recovery set) akibat tidak tercapainya fiksasi permanen kayu hasil densifikasi. Penelitian sebelumnya menunjukkan bahwa perlakuan pendahuluan alkali sebelum densifikasi dapat meningkatkan stabilisasi dimensi kayu terpadatkan. Penelitian ini bertujuan untuk mengevaluasi perubahan sifat kimia kayu terdensifikasi dengan perlakuan pendahuluan alkali. Sampel yang diuji dihasilkan dari perlakuan perebusan natrium hidroksida 1.25 N selama 3 jam. Perubahan sifat kimia diuji melalui perubahan kadar komponen kimia, gugus fungsi, dan kristalinitas. Hasil penelitian menunjukkan bahwa perlakuan alkali menyebabkan penurunan kadar holoselulosa sebesar 21.81% yang menyebabkan menurunnya hemiselulosa dan selulosa amorf. Kelarutan kayu dalam NaOH 1% dan kelarutan dalam air panas sampel kayu setelah perlakuan alkali lebih rendah dibandingkan dengan kayu tanpa perlakuan. Analisis FTIR mengkonfirmasi terjadinya perubahan kadar gugus fungsi O-H, C=C, dan C-H. Analisis XRD menunjukkan bahwa densifikasi dan perlakuan alkali menurunkan indeks kristalinitas kayu
Kraft Pulp of Jabon-wood as Raw Material For Producing Bioethanol
No full textINTRODUCTION Fast growing species such as Jabon-wood can be a potential lignocellulosic raw material for bioethanol production. Jabon is characterized by its high cellulose content, relatively low lignin content, fast growing species, and unsuitable for contruction materials due to its low strength and durability. This research was intended to evaluate the potential of bioethanol production from jabon-wood. Determination of the most appropriate lignin content and freeness level of pulp that will produce the highest conversion degree of wood into ethanol were also carried out. MATERIALS AND METHODS Jabon-wood chips were cooked by Kraft method with different alkali active and temperature to achieved kappa number 0, 10, 20, 30, 40, and 80. Oxygen delignification and bleaching are used for kappa number 15 to achieved kappa number 0. Pulp with adjusted kappa number was beaten with PFI mill to achieved freeness level 400, 300, 200, and 100 mL CSF (Canadian Standard Freeness). Simultaneous Saccharification and Fermentation (SSF) method is used to produce ethanol. Medium volume is 10 mL, where 3% cellulose (w/v), 0.04% NPK (w/v), 0.15% ZA (w/v), 20% Saccharomyces cerevisiae filtrate (v/v) of the medium volume, cellulase enzyme (activity 4.5-7 IU/mL) three times from the amount of cellulose (v/w) and citric acid 1M 0,5 mL as buffer. Water bath shaker is used to medium incubation for three days (72 hours) with temperature 40 0C. Reducing sugars is determined by using Somogyi-Nelson with spectrophotometer, while ethanol content is determined by compare between samples area and ethanol standard chromatogram with gas chromatography. RESULT The result showed that lignin and freeness level influenced sugars and ethanol production. Much lower kappa number and freeness of produced pulp, will tend to resulting as more higher yield on converted reducing sugars to ethanol, ethanol content, and cellulosic convertion. Pulp with kappa number 0 (bleached pulp) and 10 with freeness level 100 mL CSF had highest percentage of reduced sugars that converted to ethanol (8.36% and 7.32%), ethanol content (0.52% dan 0.47%), cellulosic convertion (24.15% and 22.12%), and ethanol yield (16.39% and 14.35%). Based on the data, jabon-wood was potential as raw material for producing bioethanol.Semakin menipisnya energi fosil dan keinginan manusia menggunakan energi yang ramah lingkungan mendorong pencarian energi alternatif yang terbarukan. Salah satu energi alternatif tersebut adalah bioetanol. Jabon (Anthocephalus cadamba Miq) adalah salah satu jenis tanaman kehutanan yang potensial sebagai bahan baku etanol karena kadar selulosanya yang tinggi, umur panen yang singkat dengan kelas kuat dan awet yang rendah (tidak cocok dijadikan sebagai bahan baku konstruksi). Serpih kayu jabon dimasak dengan proses Kraft dengan kadar alkali aktif dan suhu yang berbeda bergantung pada bilangan kappa pulp yang diinginkan yaitu 0, 10, 20, 30, 40, dan 80. Bilangan kappa 0 (lignin Klason 0%) diperoleh dengan memberi perlakuan pulp dengan bilangan kappa 15 dengan ODL (Oxygen Delignification) dan bleaching. Pulp-pulp tersebut digiling dengan PFI mill untuk mendapat level freeness 400, 300, 200, dan 100 mL CSF (Canadian Standard Freeness). Simultaneous Saccharification and Fermentation (SSF) merupakan metode yang dipilih untuk memproduksi etanol. Volume media 10 mL dengan kadar selulosa 3% (w/v), NPK 0,04% (w/v), 0,15% (w/v), 20% filtrat Saccharomyces cerevisiae (v/v) dari volume media, enzim selulosa beraktivitas 4,5-7 IU/mL 3 kali kadar selulosa (v/w), dan 0,5 mL asam sitrat 1M. Media diinkubasi pada suhu 40 0C selama 3 hari (72 jam). Gula pereduksi ditentukan dengan spektrofotometer mengacu pada metode Nelson-Somogyi dan kadar etanol ditentukan dengan menggunakan gas kromatografi (GC) dengan membandingkan area kromatogram sampel dengan standar. Hasil penelitian secara umum menunjukkan bahwa semakin rendah bilangan kappa (kadar lignin pada pulp) dan semakin kecil level freeness (semakin besar perlakuan beating) maka kadar gula pereduksi yang terkonversi jadi etanol, kadar etanol, konversi selulosa dan rendemen etanol akan semakin tinggi. Pulp dengan lignin Klason 0% dan 1.5% pada level freeness 100 mL CSF merupakan pulp dengan kombinasi perlakuan terbaik dalam menghasilkan etanol dibanding dengan kombinasi perlakuan lainnya. Kombinasi perlakuan tersebut masing-masing menghasilkan kadar gula pereduksi terkonversi menjadi etanol 8,36% dan 7,32%, kadar etanol 0,52% dan 0,47%, konversi selulosa 24,15% dan 22,12% dan rendemen etanol 16,39% dan 14,35%. Berdasarkan data yang diperoleh, disimpulkan bahwa pulp kayu jabon cukup potensial dijadikan sebagai bahan baku bioetanol
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
Fortifikasi Perekat Lateks Karet Alam-Stirena dengan Isosianat: Karakteristik dan Aplikasinya pada Kayu Lapis (Fortification of Natural Rubber Lateks-Styrene with Isocyanate: Characteristics and its Application for Plywood Adhesive)
No full textThis study was to evaluate the blending composition effects of natural rubber lateks-styrena (NRL-St)/isocyanate adhesive on their properties and sengon plywood quality. The blending mixture consists of 100/0, 90/10, 80/20, 70/30 and 0/100. Physico-chemical properties of these adhesives in therms of solid content (gravimetric method), pH (pH indicator paper), viscosity (Viscometer Brookfield), and contact angle (Motic software) were characterized. The bond strength (SNI 01-2704-1992) and formaldehyde emission (WKI bottle method) of plywood were also determined. Isocyanate fortification increased the solid content and viscosity of adhesive mixture, while pH was vice versa. The contact angle of adhesive mixture was about 450.Isocyanate fortification onto NRL-St improved plywood bond strength and significant improvement was happened on the composition of 80/20. Plywood hot pressing for 5 minutes increased the bond strength until isocyanate fortification 20%, while 10 minutes hot pressing also improved the bond strength on all of the composition adhesive. Only adhesive mixture of 70/30 that gave the lowest formaldehyde emission and fulfiled E1 standard (<0.1 ppm). Generally,the increasing of hot pressing time tended to decrease formaldehyde emmision of plywood. Bond strength of plywood fulfill SNI standard and E1 standard was isocyanate fortification of 30%
Six species of bamboos, that were andong bamboo (Gigantochloa verticillata), tali bamboo (Gigantochloa apus), hitam bamboo (Gigantochloa nigrocillata), ampel bamboo (Bambusa vulgaris), betung bamboo (Dendrocalamus asper), and kuning bamboo (Bambusa vulgaris), were analyzed for their fiber morphological as well as their physical-chemical properties. Results of these analysis would be used as a matter of consideration in choosing species of bamboos to be used as raw material for pulp and paper. Fiber morphological analyses include determination of fiber dimensions and followed by calculation of derivation of fiber dimensions. Determination of fiber dimensions includes fiber length, fiber diameter, lumen diameter and cell wall thickness, while calculation of derivation fiber dimensions includes runkell ratio, felting power/slenderness), muhlsteph ratio, coefficient of rigidity and flexibility ratio. Physical analyses include moisture content and specific gravity, while chemical analyses include determination of extractive (ethanol-benzene), hot water solubles, cold water solubles, lignin, holocellulose, ash and silicate contents. Results of this study showed that of the six species of bamboos studied, kuning bamboo had the most suitable properties as raw material for pulp and paper, followed by betung, tali, andong, hitam, and ampel bamboos. Keywords : Bamboo, fiber morphology, physical-chemical properties, pulp, paper
No full textSix species of bamboos, that were andong bamboo (Gigantochloa verticillata), tali bamboo (Gigantochloa apus), hitam bamboo (Gigantochloa nigrocillata), ampel bamboo (Bambusa vulgaris), betung bamboo (Dendrocalamus asper), and kuning bamboo (Bambusa vulgaris), were analyzed for their fiber morphological as well as their physical-chemical properties. Results of these analysis would be used as a matter of consideration in choosing species of bamboos to be used as raw material for pulp and paper. Fiber morphological analyses include determination of fiber dimensions and followed by calculation of derivation of fiber dimensions. Determination of fiber dimensions includes fiber length, fiber diameter, lumen diameter and cell wall thickness, while calculation of derivation fiber dimensions includes runkell ratio, felting power/slenderness), muhlsteph ratio, coefficient of rigidity and flexibility ratio. Physical analyses include moisture content and specific gravity, while chemical analyses include determination of extractive (ethanol-benzene), hot water solubles, cold water solubles, lignin, holocellulose, ash and silicate contents. Results of this study showed that of the six species of bamboos studied, kuning bamboo had the most suitable properties as raw material for pulp and paper, followed by betung, tali, andong, hitam, and ampel bamboos. Keywords : Bamboo, fiber morphology, physical-chemical properties, pulp, pape
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
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