1,721,030 research outputs found
Molar heat capacity of AgI : evaluation of the cationic and anionic contributions from thermoelectric power data
No full textThermoelectric power data provide a useful tool for the evaluation of the thermodynamic properties of ionic species of both solid and molten electrolytes in equilibrium with electrodes of thermocells; however, a previous evaluation of the heat of transport of the mobile ions is necessary. This is the case of AgI, whose standard modifications have been investigated with silver electrode thermocells some years ago. The interpretation of the thermoelectric power change at the melting point allows one to recognize that the heat of transport of the silver ions in the high conductivity BCC modification is practically the same as in molten AgI. This result has been used to evaluate the molar heat of the silver ions in the BCC phase from the corresponding thermoelectric power data reported in the literature. The analysis of the thermoelectric power change at the transition point, from the wurtzitic to the BCC phase, as well as a more speculative interpretation or thermoelectric power data obtained with iodine electrode thermocells, allows one to evaluate the molar heat of the iodide ions in the BBC modification of AgI. The summation of the ionic contributions so computed reproduces rather satisfactorily the trend of AgI molar heat data obtained with adiabatic calorimetr
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
Epoxy polymers : Glass transition/cure degree correlation
No full textThe correlation between the glass transition temperature,T g , and the cure degree, α, of epoxy polymers has been analysed on the basis of an extension of the Vogel-Tamman-Fulcher equation for the viscosity of polymers and glasses.
A physical meaning has been given to the coefficients of the series expansion of the functionT g=T g (α).
This analysis allows one to verify that the experimental (T g ,α) data support the conclusion that, in the case of thermoset polymers, the ideal glass transition temperature,T o, appearing in the VTF equation, is larger thanT g .
This conclusion may be supported by the thermodynamic interpretation ofT 0 as the temperature at which the excess entropy of the systems tends to vanish: in the case of partially cured thermosets;T 0 would represent the minimum temperature at which the system becomes able to enhance its cure degree.Die Korrelation zwischen der Glasumwandlungs-temperaturT g und dem Aushärtungsgrad α von Epoxidpolymeren wurde analysiert, und zwar basierend auf einer Erweiterung der Vogel-Tamman-Fulcher-Gleichung für die Viskosität von Polymeren und Gläsern. Den bei der Reihenentwicklung der FunktionT g =T g (α) auftretenden Koeffizienten wurde eine physikalische Bedeutung zugeschrieben. Diese Analyse ermöglicht nachzuweisen, daß die experimentellen Daten (T g ),α die Schlußfolgerung stützen, daß im Falle von hitzehärtbaren Polymeren die in der VTF-Gleichung auftretende sogenannte ideale GlasumwandlungstemperaturT 0 höher alsT g ist. Diese Konklusion wird auch durch die thermodynamische Interpretation vonT 0 gestützt, nämlich als die Temperatur, bei der die Überschußentropie des Systems gegen Null geht: im Falle von teilweise ausgehärteten hitzehärtbaren Polymeren würdeT 0 die minimale Temperatur darstellen, bei der eine Erhöhung des Aushärtungsgrades des Systems einsetzt
Thermoelectric power and ionic molar entropy of solid, vitreous, and molten salts
No full textThe determination of the thermoelectric power of cells of solid, vitreous, or molten salts enables the molar entropy of the ionic species exchanged at the electrode to be obtained. This is of interest for polyatomic anion salts in some solid and vitreous electrolytes where the Pitzer relationship between the overall entropy of a simple salt and single-ion contribution to it cannot be used. The proposed procedure applies to cases in which an evaluation of the transport terms in the expression for the overall thermoelectric power is possible. If the molar ionic entropy can be evaluated at various temperatures the corresponding ionic molar heat capacity can be foun
Epoxypolymers: effect of the elastomer in the kinetics of polymerization
No full textThe polymerization kinetics of three epoxy adhesives HX-205, HX-206 and F-185 was defined by means of thermal analysis techniques (DSC and TMA). It was found that the liquid carboxy-terminated butadiene acrylonitriles (CTBN) and the solid rubber elastomer present in HX-206 and F-185 do not affect the phenomenological kinetics of the isothermal cure process by comparison with HX-205, which contains the same epoxy but no elastomer. It was also found that the isothermal (373 K) cure of these adhesives follows a two-range behaviour, i.e., the phenomelogical order of the cure kinetics is close to zero before and close to one after a "critical" time of cure. The trend of the glass transition temperature Tg vs the cure degree α for HX-206 and F-185 was always below that for HX-205. Tg did not approach the temperature of cure tc for α = 1 for elastomer-added adhesives, whereas HX-205 displayed an almost liear trend, with e.g. Tg = 87° C for α. = 85%
Thermoelectric power of AgI-AgPO3 glasses
No full textThe aim of the present work is to suggest a way to gain further knowledge about the effect of the oxyanionic component from determinations of the thermoelectric power of Ag electrode thermocells containing a binary AgI-AgPO//3 glass as an electrolyte
Epoxypolymers: temperature-time-transformationdiagram by means of DSCinvestigations
No full textThe aim of this work is to show that isothermal and non-isothermal DSC investigations allow the temperature-time-transformation diagram of a polymer system to be drawn. DSC data can be worked out according to a simple model which supports the interpretation of the gelation process in terms of viscosity. It is seen that the degree of cure attained at the gelation point depends on the temperature of cure and that this crucial process is similar to the formation of a glass phase from a melt
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