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Marine borers resistance of chemically modified portuguese wood
Get PDFThis study deals with the role of hardness and chemical toxicity in the resistance of pinewood to marine borers. Portuguese wood Maritime pine (Pinus pinaster Ait.) was modified with 1,3-dimethylol 4,5-dihydroxy ethylene urea (DMDHEU), methylated methylol melamine (MMF), tetraethoxysilane (TEOS) and two types of wax. In addition, for comparative purposes, different control species, Ipê, Beech and Blue Gum and CCA treated pine were included. All specimens were exposed over 2 years in sea (Porto, north of Portugal). Three inspections were performed after exposure (6, 12 and 24 months). The influence of type and level of modification as well as hardness was evaluated. As results: Specimens modified with resin have shown slight or trace attack by Teredinids in DMDHEU with low level of modification (10% of weight percent gain, WPG); MMF resin with high and low level of modification (25% and 10% of WPG) have shown trace to moderate attack, respectively. With the TEOS and wax impregnated wood which fill the cell lumens no significant difference in marine borers attack was found as compared to unmodified control specimens, despite the increased hardness
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
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
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
Technological improvement of Portuguese Pine wood by modification
No full textDas Ziel der Arbeit „The Technological improvement of Portuguese pinewood by chemical modification” bestand darin, die Charakteristiken des Holzes der See-Kiefer (Pinus pinaster Ait.) und den Einfluss der chemischen Modifizierung hinsichtlich des Widerstandes gegen Meeresorganismen, sowie ihrer physikalischen und mechanischen Eigenschaften zu untersuchen. Vier Modifizierungstypen wurden getestet: 1,3-Dimethylol-4,5-dihydroxyethylen-Harnstoff (DMDHEU), N-Methylol-Melamine (MMF), Tetra-alkoxysilane (TEOS) und Wachs.
Diese Arbeit besteht aus zwei Teilen: eine vorläufige und eine Haupt-Studie. In ersterer wurde eine Vielzahl von Materialeigenschaften untersucht - physikalische und mechanische Eigenschaften und ihre Wechselwirkungen. Besonderes Augenmerk wurde auf die Resistenz gegenüber Meeresorganismen gelegt, wobei die Rolle der Härte, der Form der Proben sowie der Toxizität der Chemikalien untersucht wurde.
Im zweiten Teil der Arbeit wurde eine ausführliche Studie zum Thema Kriechen durchgeführt. Art und Grad der Modifizierung wurden in Abhängigkeit von der Belastung, von verschiedenen Umgebungsbedingungen und vom mechano-sorptiven Effekt evaluiert.
Obwohl die Steifigkeit nicht signifikant verschieden war, traten Unterschiede in den anderen Eigenschaften auf. Einerseits waren die Anti-Quellungs-Effizienz und Steifigkeit-Stabilisierung erhöht. Andererseits waren die Bruchschlagarbeit und die Gleichgewichtsfeuchte signifikant durch Zellwand-Modifizierung (DMDHEU und MMF-Harz) reduziert, wobei eine enge Wechselbeziehung zwischen letzteren Variablen beobachtet wurde.
Unter hohem Belastungsgrad oder unter dem Einfluss des mechano-sorptiven Effekts war für das modifizierte Holz mit Zellwandreaktion (DMDHEU and MMF) das Ausmaß des Kriechens geringer als das des unmodifiziertem Holzes. Für beide Arten von Harz wurde das relative Kriechen deutlich verringert, trotz unterschiedlicher Veränderungen in der Ausgleichsfeuchte, Steifigkeit Stabilisierung und Festigkeit. Die Anti-Kriech-Effizienz zeigte eine enge Korrelation mit der Abnahme der Gleichgewichtsfeuchte, der Anti-Quell-Effizienz und der Steifigkeits-Stabilisationseffizienz. Die lumen-füllende Modifizierung mit TEOS-Lösung hatte weder einen Einfluss auf den Kriech-Faktor noch auf die Gleichgewichtsfeuchte und die Steifigkeits-Stabilisationseffizienz.
Bei den Meerwasseruntersuchungen waren die wichtigsten Schlussfolgerungen, dass die Härte und die Form der Proben keinen Einfluss auf die Resistenz gegenüber einem Befall durch die Meerwasser-Bohrschädlinge (Limnoriden und Terediniden) haben. Lumen-füllende Modifizierungen (TEOS und Wachs) hatten keine Wirkung hinsichtlich der Resistenz gegen Meerwasser-Bohrschädlinge. Hölzer, die mit Kondensationsharzen (DMDHEU und MMF) modifiziert waren, waren von einem Befall mit Limnoriden nicht betroffen. Aber nur DMDHEU mit einem Minimum an Modifizierung war geeignet, um einen Befall durch Terediniden über eine Expositionsdauer von 3 Jahren zu verhindern.
Die Verwendung von modifiziertem Holz als Baumaterial für nicht-tragende Bauteile wie Anwendungen in Feuchträumen, Wandfassaden oder Gartenmöbeln ist bekannt. Diese Untersuchung unterstützt die Ausweitung seiner Anwendung für tragende Bauteile, besonders wenn das Design durch die Möglichkeit von Deformation bestimmt wird, die seine Funktionsfähigkeit einschränkt. Deshalb müssen das Versprödungsverhalten, insbesondere bei der Zellwand-Modifizierung mit DMDHEU, und die Designmöglichkeiten für mechanische Verbindungen bestimmt werden, um die Anwendungsmöglichkeiten des modifizierten Holzes als tragende Komponente auszuweiten, bei denen oft der Grenzzustand der Tragfähigkeit das Design der strukturellen Komponenten bestimmt.Wood has a long tradition as a structural and building material in Portugal. In the last decade, the European trend to improve physical properties of wood by chemical modification allowed extending its performance on durability and improve its performances in properties relating to moisture, in general.
The objective of the Technological improvement of Portuguese pinewood by chemical modification was to study Maritime pine (Pinus pinaster Ait.) wood characteristics and the impact of the chemical modification at large range on resistance to marine organisms, physical and mechanical properties. Four modification methods were tested: 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU), N-methylol melamine (MMF), tetra-alkoxysilane (TEOS) and wax.
This work comprises two parts: a preliminary and a main-study. In the former, a large variety of material properties was studied - physical and mechanical properties, and their interactions. Particular attention was taken on the marine organisms, where the role of hardness, shape of specimens as well as the toxicity of chemicals were investigated.
In the second part of the work, a study on the subject of creep was carried out. Types and levels of the modification together with stress levels, different environmental conditions and mechano-sorptive effect were evaluated.
Although stiffness appeared to be statistically unaffected, significant differences in other properties occured. The anti-swell-efficiency and stiffness stabilization increased, on the one hand. On the other hand, the impact bending strength and the equilibrium moisture content appeared to be significantly reduced in the cell wall modification (with DMDHEU and MMF resins) where a close inter-connection between the latter variables was observed.
Under high stress level or under the mechano-sorptive effect, the creep was lower for both modifications with cell wall reaction (with DMDHEU and MMF) than for unmodified wood. For both types of resin, relative creep reduced significantly, despite different changes took place in the equilibrium moisture content, stiffness stabilization or strength. The anti-creep efficiency has shown a close correlation between the equilibrium moisture content reduction, anti-swelling efficiency and stiffness stabilization effciency. The lumen fill modification with TEOS solution had no effect in creep as well as in the equilibrium moisture content and stiffness stabilization efficiency.
In the marine trials, the main conclusions were the unimportant role of the hardness and the specimens shape against the attack of marine borers (Limnorids and Teredinids). Modified wood with lumen fill (with TEOS and wax) has no effect on the resistance to both marine borers. Modified wood with condensation resins (DMDHEU and MMF) were unaffected by Limnorids attacks. But, to prevent the attacks of Teredinids over 3 years of exposition, only DMDHEU resin was effective with a required minimum level of modification.
The use of modified wood as building material is well known in non-loaded bearing components, where applications in moist rooms, wall claddings or garden furniture are the main applications. This study supports the possible extension of its application for structural purposes, mainly if the design is governed by the serviceability limit state, deformation. Therefore, the brittleness behaviour, mainly in the cell wall modification with DMDHEU resin, and design properties for mechanical connections must be determined in order to extend the use of modified wood as load bearing components where often the ultimate limit state govern the design of structural components
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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