bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quand négocier l'ouverture du terrain c'est déjà enquêter. Obtenir la passation de questionnaires aux congressistes de partis marocains
Authors: Bennani-Chraïbi Mounia 
Published: February 2011

Résumé Négocier le lancement pour la première fois une enquête par questionnaires et à grande échelle, sur les membres de 8 partis politiques marocains en plein congrès national, est une voie d’accès ethnographique privilégiée pour comprendre les modalités de prise de décision au sein de ces organisations. Cet article se penche sur les circonstances qui favorisent ou entravent l’ouverture du terrain. L’insertion dans des cercles de confiance, la « scientificité » du projet, la création d’un précédent par le premier parti à autoriser l’enquête semblent être les clés du succès. Toutefois, un refus révèle que tolérer une telle recherche revient pour les dirigeants à accepter avec plus ou moins d’enthousiasme une production « démocratisée » et hors contrôle de l’image de leur parti.
Levinas et Bergson
Authors: Vieillard-Baron Jean-Louis 
Published: February 2011

Résumé Le premier volume d’inédits de Levinas comprend un hommage à Bergson rédigé en 1946. Levinas voit en Bergson celui qui s’est opposé au temps de la science et des machines au nom du temps vécu ; ceci a rendu possible la conception heideggérienne du temps comme être. Levinas souscrit à la grande découverte de Bergson. Il souligne l’intérêt de la critique bergsonienne du néant comme être biffé, mais rejette la critique du désordre qui ne serait qu’un ordre différent ; pour lui, le désordre est le chaos préalable à tout ordre. Surtout, il voit dans la durée un temps fondamental, une diachronie première, qui rend possibles les trois dimensions du temps. Et il note que la durée est une vie que la mort ne limite pas ; le temps n’est pas la marque de notre finitude. Pour Bergson, seule la matière meurt, par manque d’énergie. Bien qu’il n’ait pas suivi la méthode bergsonienne, Levinas reconnaît la supériorité de l’analyse de la durée et la prolonge dans le sens d’un immémorial subjectif.
An Investigation of Online Course Management Systems in Higher Education
Authors: Ray Julie A. 
Published: February 2011

Colleges and Universities across the United States have experienced an unprecedented growth in the demand for online course instruction in the recent years. With the large increase in the number of students participating in courses in the online format, there is a lack of research or empirical data that examines both the overall effectiveness and the quality of instruction. This study was designed to examine three major components of online instruction: 1) Course Management Systems (CMS), 2) Instructor training and support and, 3) The evaluation of online courses. Thirty institutions of higher education in the tri-state area of Pennsylvania, Ohio, and West Virginia participated in the research. The study was a Mixed-Methods approach with both quantitative and qualitative data gathered and analyzed. The methodology and results examined the process of selecting an institutional CMS, the training practices for online instructors, and the evaluation of online courses from an administrative and student perspective.
Every Need to be Alarmed
Authors: Young Ed 
Published: February 2011

Demand for contemporary IT systems to support chronic availability, expansive integration and extensibility has never been greater. Distributed infrastructures and particularly, the advent of Service Oriented Architecture (SOA) introduce new challenges for meeting these demands. Despite architectural conventions to prescribe a common structure and simplifed approach, these systems are becoming more complex, heterogeneous and critical. Comprehensive System Management is no longer a luxury. Faults and potential failures have to be identified, isolated and addressed, and ideally pre-emptively. Our front-line indicators are alarms.
Some Results Obtained in a Study of the Development of Stickiness by Vulcanized Rubber
Authors: Toullec Lucien 
Published: February 2011

Abstract
The experiments described in the present paper show the possibility of reproducing artificially the stickiness which appears during natural aging, and the results show the experimental conditions which are most favorable to a study of the phenomenon. The indications are that it is best to use an oxygen bomb of small capacity, at a temperature of 60–70° C, and with a pressure of 1–4 kg. per sq. cm. of oxygen. The factor which under no conditions must be disregarded if almost certain failure is to be avoided is unquestionably the problem of ventilation. The Geer oven does not seem to be of any service in such experimentation. The appearance of stickiness during aging is not indicative of an advanced stage of deterioration, but is a manifestation of one form or type of aging rather than the consequence of an extreme state of deterioration. Finally, the influence of certain factors has been established. As far as factors inherent to the rubber mixtures themselves are concerned, the accelerator-vulcanizing agent system plays a determinant part. The character of the phenomenon depends on the aging conditions, particularly on the rate of oxidation. The tendency of a vulcanizate to become sticky on aging is particularly great when the temperature is relatively low and the pressure of oxygen is likewise low.
A Chemical Study of Accelerators of the Plasticization of Rubber
Authors: Montu Michel 
Published: February 2011

Abstract
Substances which peptize rubber, of which the most active fall within the class of aromatic thiols such as 2-naphthalenethiol and xylenethiol, are also accelerators of plasticization. Their action, which differs from that of “plasticizers”, is of a chemical nature, and it can be modified by certain agents, such as metalloids of the sulfur family. The use of plasticization accelerators requires certain precautions. A study of the oxidizability of rubber in the presence of plasticization accelerators has shown that these substances make rubber more sensitive to oxygen, whose part in the plasticization of rubber is already well known. At the beginning of the reaction, oxygen is absorbed rapidly under the catalytic influence of the thiol, which is simultaneously transformed into the corresponding disulfide. By means of ultraviolet spectrography, this transformation of thiols while playing the part of catalytic agents can be followed.
Some Effects of Solid Fillers in Rubbers
Authors: Williams Ira 
Published: February 2011

Abstract
The presence of pigments in rubber compounds produces physical properties which are of importance both before and after vulcanization. The ability of the unvulcanized mixture to calender or extrude smoothly with minimum swelling and to maintain shape during air cures, and the tensile strength, tear resistence, and abrasion resistance of vulcanized stocks all are affected. The methods by which these changes are brought about have been considered by many investigators and have been summarized by Parkinson1 and by Shepard, Street, and Park. Since carbon black is the most generally useful reinforcing pigment, it is natural that investigations have been directed particularly to this product. However, while it is recognized that differences exist in the final properties imparted by different pigments, all solid compounding ingredients have something in common. This point can be illustrated by the tear resistance imparted by such a variety of pigments as carbon black, zinc oxide, whiting, and clay. The effect of volume loading on the tear resistance of vulcanized stocks containing these materials, determined by the method of Zimmerman is shown in Figure 1. The effect of solid compounding ingredients can be studied only by considering the compound as a whole, since the properties are determined very largely by the relation between the solid particle and the matrix which surrounds it. Since the introduction of the many types of synthetic rubbers, the complexity of the problem has been greatly increased by the different states of polymerization, which affect the ability of the rubber to conform to the shape of the pigment particle and by the differences in polar nature which affect the type and the degree of adhesion between filler and matrix.
Apparatus for the Measurement of the Dynamic Shear Modulus and Hysteresis of Rubber at Low Frequencies
Authors: Fletcher W. P. , Gent A. N. 
Published: February 2011

Abstract
An apparatus is described which subjects a rubber test-piece to a force in simple shear, varying sinusoidally with time in the frequency range of 0.0017– 17 c/s, the instantaneous values of force and displacement being measured by photoelectric pickups. From the display on the screen of a cathode-ray tube of the mechanical hysteresis loop described by the vibrating rubber, measurements are made which make possible calculation of the dynamic shear modulus and hysteresis. Typical results are given.
Wear Resistance of Vulcanized Elastomers
Authors: Burns J. C. , Storey E. B. 
Published: February 2011

Abstract
The use of a stainless steel wire screen on the National Bureau of Standards abrader will produce a wearing action on a vulcanized elastomer and 41° and 122° F GR-S vulcanizates exhibit the same relative order of wear resistance that has been observed in road tests. The wear resistance determined on this surface is sensitive to the state of cure of the vulcanizate, and a maximum value is obtained at a cure slightly longer than the optimum tensile cure. The method is very sensitive to the type and quantity of carbon black and softener loading in the vulcanizate. These factors are ranked also in the same order as observed in road tests. The method may be applied to footwear compounds as well as to tread vulcanizates of synthetic elastomers. The use of a metal screen offers a uniform and reproducible test surface for determining wear resistance; it suffers little change during continued use; and the material is not affected by minor changes in the ambient temperature or relative humidity. The reproducible nature of the wire screen greatly reduces the need for a reference standard, and comparisons may be made between tests conducted at relatively long intervals of time on either the same or a duplicate screen.
Mooney Viscosity Changes in Freshly Prepared Raw Natural Rubber
Authors: Wood R. I. 
Published: February 2011

Abstract
In the course of investigations carried out in connection with the technical classification of natural rubber, large permanent increases in Mooney viscosity of the order of 30 to 40 units have been observed when freshly prepared raw or masticated rubber is stored under conditions of low relative humidity. The rate of change and the extent of the increase are both affected by the relative humidity of storage, the effects being most marked in the region below about 30 per cent relative humidity. Rate of change in dry air increases with decreasing sample thickness and with increasing temperature, although the effects are masked somewhat by oxidative breakdown on prolonged storage at temperatures higher than about 30° C. Mooney values continue to increase long after the rubber has reached constant weight on drying; the removal of acetone soluble and nitrogenous non-rubber components and of oxygen does not prevent the changes taking place. The effects are only partially reversed by subsequent storage at high relative humidity, and there is evidence to suggest that the hardening is associated with the development of a cross-linked benzene-insoluble gel structure throughout the rubber. The rate of mill-breakdown of dry stored rubber is greater than for fresh rubber, but in comparisons using a fixed breakdown procedure, the hardened rubber still has a higher Mooney value after mastication. Rubbers hardened by dry air storage exhibit slightly improved vulcanized properties in a pure-gum mix even after the additional breakdown required to reach normal stock viscosity levels. Fluctuation of temperature and humidity in commercial smokehouses and drying sheds may well account for part of the variability of natural rubber as measured by Mooney viscosity determinations on the freshly prepared product, and different conditions of storage will add a further contribution to the total hardness variation experienced by the consumer.
A Study of the Stage of Dispersion of Synthetic Latexes by the Intensity of Light Scattering
Authors: Yurzhenko A. I. , Gusyakov V. P. 
Published: February 2011

Abstract
1. Light scattering in synthetic latexes of varying dilutions was studied as a function of the conditions under which the latexes were prepared. When the polymer concentration is increased, the intensity of light scattering reaches a maximum; this is related to the absorption of scattered light in the latex itself. 2. When the polymer concentration is less than 1×10−2 per cent, the turbidity-concentration relation is linear. Calculation of the radius of polymer particles for this region of concentration by Rayleigh's equation gives results approximating those obtained by ultramicroscopy, but tending to be slightly lower. A similar picture is observed in the application of Debye's equation. 3. When the conversion is increased, the size of the latex particles increases. Accumulation of the polymer in the aqueous phase of the emulsion is largely the result of an increase of volume of the polymer particles, and not of their number.
Classifying Butyl Rubber with Respect to Modulus. A Chemical Method
Authors: Currie L. L. 
Published: February 2011

Abstract
The stress-strain method of determining the modulus of Butyl rubber possesses severe shortcomings when applied to plant control, the most serious being the time lag in reporting reliable results. A chemical method is described which is less time-consuming and at the same time is more reproducible. The basic iodine-mercuric acetate method for Butyl unsaturation has been improved by the standardization of reaction conditions, and a correlation between unsaturation and stress strain values in the National Bureau of Standards formula has been developed. This comprehensive study has covered commercial grades of Butyl rubber over an 18-month period. The application of the method to plant control is described, and improved product uniformity is indicated. Reliable results suitable for control purposes are available in 3 to 4 hours.
Physical Aspects of GR-S and Alfin Polymer Modifications
Authors: Dinsmore R. P. 
Published: February 2011

Abstract
It seems that the possibilities of this development, both as a lead to improved rubbers and as a spur to the explanation of rubber behavior, are exceptionally stimulating. Far from being a completed work, this is more likely to be the first and exciting chapter of a series yet to be unfolded. It is a distinct possibility that useful improvements to natural rubber, as well as to synthetic, may result from further investigation of the field. It is perhaps unnecessary to caution that the quantitative relationships developed are not sacrosanct and may be altered by more extensive data. The importance of the results, however, is not entirely dependent on their numerical values.
Changes of Fatigue Resistance of Vulcanized Natural Rubbers during Swelling
Authors: Gul V. E. , Dorokhina T. V. , Dogadkin B. A. 
Published: February 2011

Abstract
A method of fatiguing swollen vulcanizates of natural rubber while maintaining a minimum deforming load, independent of the change of modulus of elasticity of the experimental specimens, was devised. The effect of swelling vulcanized natural rubber in petrolatum and in dibutyl phthalate on fatigue resistance was studied. With increase of swelling of a vulcanizate in dibutyl phthalate and in petrolatum, an initial increase of fatigue resistance was observed up to 1.8 times the fatigue resistance of the unswollen vulcanizate. Following this, a decrease of fatigue resistance was observed. The equation obtained for the change of fatigue resistance as a function of the degree of swelling is explained by two simultaneous processes: (1) increase of fatigue resistance because of decrease of energy loss in the destructionof intermolecular bonds, and (2) initiation of chemical processes leading to destruction, and a smaller difference between the deformation and the relative elongation at rupture. The effect of the character of the solvent used for swelling on the nature of the fatigue resistance-swelling relation is shown.
Studies of the Mechanism of Mastication of Rubber. V. The Viscosity Lowering of Rubber Solutions by Phenyl Disulfide Derivatives
Authors: Imoto Minoru , Kiriyama Shigeru 
Published: February 2011

Abstract
Nine derivatives of phenyl disulfide having substituents in the o- or p-position, were synthesized, and the lowering of the viscosity of toluene solutions of rubber by means of these derivatives was measured. Compounds substituted in o-position were more effective than were compounds substituted in p-position, and the effects of the substituents were in the order : C6H5CONH &gt; CH3CONH &gt; NH2. These conclusions are in agreement with electronic interpretations.
The Meaning of Terms Related to Curing
Authors: Schade J. W. 
Published: February 2011

Abstract
Anyone unfamiliar with rubber technology would naturally assume that the terms used in describing vulcanization convey the same concepts to all technologists in the industry. This is not the case. For example, the term optimum cure is variously defined, and compounders utilize a variety of methods for selecting optimum cures. Some technologists rely mainly on the shape of the modulus-time curve; others include tensile strength values in their analysis; still others depend on sensory indications, such as resistance to tearing by hand, before choosing an optimum. That there is no common basis for selecting optimum cures from moduli, tensile strengths, and ultimate elongations of a series of five cures ranging from 30 to 150 minutes was clearly demonstrated some years ago. Data of this kind were obtained for specimens of GR-S supplied by the fifteen GR-S plants then operating. These data were presented to six technologists employed in the larger rubber companies and at the Government Laboratories, with a request that they select the optimum cures for the specimens. In one company the estimates of four technologists were averaged; in another company two estimates were considered. The differences in optimum cures selected by the technologists for the fifteen specimens varied from 15 to 45 minutes, with an average difference of 28 minutes. If the values selected for optimum cure of the fifteen specimens had been such as to indicate agreement on a common basis for selecting optimum cure, a great variation among the commercial GR-S produced by the fifteen plants at that time would have been evidenced. The values reported from identical data varied, however, for the different specimens over a range of 10 to 40 minuutes. These results show that the compounders could not have used a common method of selecting the optimum cures. The term optimum cure obviously meant different intervals to the technologists who analyzed the data. Furthermore, discussions at various meetings of technical men have disclosed that concepts of the meaning of rate of cure and of state of cure also differed materially. Therefore an attempt at logical definitions of terms seems desirable.
Stress Relaxation in Compression of Rubber and Synthetic Rubber Vulcanizates Immersed in Oil
Authors: Beatty J. R. , Juve A. E. 
Published: February 2011

Abstract
The practical implications of this study are that rubber compounds which swell in the presence of oil have a property which may be utilized in some applications where it may serve a useful purpose. Examples are O-ring seals and other types of gaskets, where the rubber is used in compression. In these cases the stress decays more slowly with time, and in some cases the force would increase, and the tendency to leakage would be minimized. In these experiments the sample was relatively unconfined except for the direction of loading with only low frictional forces which tended to prevent increase in volume. It was noted (Figures 4 and 6) that, with natural rubber and GR-S at 70° C the stress reached a maximum between 1000 and 10,000 hours, which is a result of the sample reaching equilibrium with respect to swelling by the oil, and the stress then decreases, depending on the oxidative scission of bonds in the same manner as found for tests conducted in air. However, according to Scott, the attack of swelling agents accelerates oxidation; so it is possible that this oxidative scission might be in addition to that normally measured in air.
Simultaneous Effects of Phenyl-β-Naphthylamine, Sulfur, and Vulcanization Accelerators on the Oxidation of Rubber
Authors: Kuzminskii˘ A. S. , Lezhnev N. N. 
Published: February 2011

Abstract
Most rubber mixtures contain, besides antioxidants, sulfur and vulcanization accelerators, and these latter have a substantial influence on the oxidation process. Consequently a study of the action of these substances when present simultaneously with antioxidants is important, particularly since there have been no reports concerning this question in the scientific literature. In an earlier article we showed that sulfur, when dissolved in purified sodium-butadiene rubber, is a negative catalyst of oxidation. Above 70° C, the inhibitory effect of sulfur is only slight, and is manifest in a retardation of the autocatalytic process. This retarding effect is much more characteristic of sulfur than of ordinary rubber antioxidants. For example, when added to purified rubber, phenyl-β-naphthylamine prolongs the induction period, but has little influence on the rate of the final auto-accelerated reaction. This behavior of phenyl-β-naphthylamine can be explained by its great inhibitory activity. It acts as a true inhibitor, even in the smallest concentrations'. Consequently, the autocatalytic reaction commences only when almost no phenyl-β-naphthylamine is present, whereas the period of partial retardation of this reaction in the case of an ordinary inhibitor is negligible.