1,721,070 research outputs found
Depolymerization of polystyrene at reduced pressure through a microwave assisted pyrolysis
No full textLarge amounts of styrene and other important aromatic hydrocarbons were obtained employing microwave assisted pyrolysis for the depolymerization of polystyrene in the presence of carbon as an absorber. Working at a reduced pressure the yield of liquid was increased (higher than 75%) with respect to those obtained at ambient pressure. This liquid was clear and showed a low viscosity and density. On the contrary a dark brown liquid was formed when pyrolysis was carried out in a stream of nitrogen, but the yield was 94.3 wt%. Using a fractionating system and a residual pressure of 21.3 kPa the maximum concentration of styrene in the liquid was reached (71.9 wt%) corresponding to the maximum amount of styrene recovered from the starting PS (60.6 wt%). The substitution of carbon with silicon carbide as MW absorber, gave almost the same amount of liquid but the rate of pyrolysis was strongly reduced.
Composition of liquids was affected by residence time into the reactor and some different compounds might be obtained by reaction among intermediates formed in the course of the process.
Reverse polymerization of PS through microwave assisted pyrolysis may be a way to solve some environmental problems caused by waste PS. Large amount of valuable chemicals such as styrene, α-methylstyrene and toluene was collected while gas and char, formed in low amount, may be used as fuel
Synthesis of dianols or BPA through catalytic hydrolyisis/glycolysis of waste polycarbonates using a microwave heating
No full textDianols (etherified derivatives of bis-phenol-A) and bis-phenol-A (BPA) itself were efficiently obtained from waste polycarbonate (PC) via a fast catalytic hydrolysis/glycolysis process using microwave heating. A complete conversion of waste PC was achieved using a microwave power of 3 kW in a very short time (10 min). A mixture of BPA, mono- and dianols were obtained working with a basic catalyst and ethylene glycol as solvent. This mixture was selectively converted into dianol 220 (2,2′-((propane-2,2-diylbis(4,1-phenylene))bis(oxy))bis (ethan-1-ol)) using diethyl carbonate. Furthermore several dianols were obtained through a more eco-friendly process through hydrolysis in the appropiate diol as solvent and Na2CO3 as catalyst followed by a one-pot etherification with urea, zinc oxide and a microwave heating for 15 min. On the contrary using THF/H2O as solvent and KOH as catalyst, PC was hydrolysed to BPA with high selectivity (80.6, wt%)
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
A friendly management of waste/contaminated polymeric materials from differentiated waste collection through microwave pyrolysis
No full textWaste/contaminated polymeric materials are present in a solid municipal waste, and in larger amount in a differentiated waste collection. These polymers can’t be easily disposed through mechanical processes. They still contain a large variety of compounds having different chemical and physical properties, thus they can’t be blended together. The conversion of these waste materials into a gas, a liquid and a solid, through a microwave assisted pyrolysis has been reviewed. The solid may be employed as filler to obtain composites or a solid fuel while the liquid is, usually, the more interesting product, as it may be a source of chemicals or liquid fuel. A study about upgrading of this liquid to a gasoline for automotive engine is also reported. The gas may be used as liquefied petroleum gas or converted into energy. Following a pyrolyis process, a complete recycle of waste polymeric materials may be realized. All the products may be reused, some items as the source of monomers for new polymerizations, as raw materials for new synthesis, or to produce energy: thus realizing the last step of a circular economy
Bunga rampai maestro seni Provinsi Bengkulu
Full text linkPerkembangan dan perubahan zaman menyebabkan sebagai besar masyarakat lebih bangga akan tradisi dan budaya yang datang dari luar. Faktor ini menyebabkan banyak tradisi dan budaya daerah atau lokal yang mulai terlupakan. Kondisi ini jelas mengkhawatirkan sebab masyarakat yang tidak lagi mengetahui tradisi dan budaya mereka renta terhadap krisis identitas. Seluruh anak bangsa memiliki peranannya masing -masing agar kekayaan budaya yang dimiliki tidak hilang ditelan masa. Balai Pelestarian Nilai Budaya (BPNB) Sumatera Barat sebagai salah satu Unit Pelaksana Teknis dari Direktorat Jenderal Kebudayaan, Kementerian Pendidikan dan Kebudayaan memiliki kewajiban agar kesenian dan tradisi yang dimiliki oleh setiap wilayah di daerah kerja dapat dipertahankan dan dilestarikan.
Langkah yang dilakukan oleh BPNB Sumatera Barat terkait dengan Tugas Pokok dan Fungsinya adalah melakukan kajian dan pelestarian tentang kebudayaan yang ada di wilayah kerja. Untuk itu pada tahun 2015, BPNB Sumatera Barat melakukan kajian tentang beberapa mestro seni di wilayah kerja. Tujuan kegiatan ini adalah menulis biografi beberapa mestro seni yang ada di Propinsi Bengkulu, dalam biografi tersebut akan menjelaskan riwayat hidup sang tokoh, serta kiprah yang telah dilakukan dalam mengembangkan dan mempertahankan kesenian daerah yang mereka miliki. Tahun 2017, hasil catatan tersebut diterbitkan dalam bentuk buku untuk masing – masing propinsi.
Buku yang saat ini yang disuguhkan kepada pembaca adalah buku mestro seni dari Propinsi Bengkulu, yakni M. Yusuf Mestro Tari dari Kota Bengkulu, yang ditulis oleh Refisrul, Siti Zahra : Mestro Tari Gandai dari Mukomuko yang ditulis Hasanadi. Buku ini juga menjelaskan tentang Syamsuri Zulkifli Tokoh Seni Tradis Sarapal Anam yang ditulis oleh Mutiara Al Husna, sedangkan tentang Aladin Bin Awam Menari Untuk Tradisi dan Negeri ditulis oleh Ferawati. Pada bagian terahir buku ini menjelaskan tentang Biografi Sayamsul Bahhri ditulis oleh Undri
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
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