SynopsisA multiordering parameter model for glass-transition phenomena has been developed on the basis of nonequilibrium thermodynamics. In this treatment the state of the glass is determined by the values of N ordering parameters in addition to T a n d P; the departure from equilibrium is partitioned among the various ordering parameters, each of which is associated with a unique retardation time.These times are assumed to depend on T, P , and on the instantaneous state of the system characterized by its overall departure from equilibrium, giving rise to the well-known nonlinear effects observed in volume and enthalpy recovery. The contribution of each ordering parameter to the departure and the associated retardation times define the fundamental distribution function (the structural retardation spectrum) of the system or, equivalently, its fundamental material response function. These, together with a few experimentally measurable material constants, completely define the recovery behavior of the system when subjected to any thermal treatment. The behavior of the model is explored for various classes of thermal histories of increasing complexity, in order to simulate real experimental situations. The relevant calculations are based on a discrete retardation spectrum, extending over four time decades, and on reasonable values of the relevant material constants in order to imitate the behavior of polymer glasses. The model clearly separates the contribution of the retardation spectrum from the temperature-structure dependence of the retardation times which controls its shifts along the experimental time scale. This is achieved by using the natural time scale of the system which eliminates all the nonlinear effects, thus reducing the response function to the Boltzmann superposition equation, similar to that encountered in the linear viscoelasticity. As a consequence, the system obeys a rate (time) -temperature reduction rule which provides for generalization within each class of thermal treatment. Thus the model establishes a rational basis for comparing theory with experiment, and also various kinds of experiments between themselves. The analysis further predicts interesting features, some of which have often been overlooked. Among these are the impossibility of extraction of the spectrum (or response function) from experiments involving cooling from high temperatures at finite rate; and the appearance of two peaks in the expansion coefficient, or heat capacity, during the heating stage of three-step thermal cycles starting a t high temperatures. Finally, the theory also provides a rationale for interpreting the time dependence of mechanical or other structure-sensitive properties of glasses as well as for predicting their long-range behavior.As mentioned above, the set of differential equations (20) cannot be integrated analytically. Nevertheless, they represent an "autonomous system"20 subject to some simplification. Since at fixed T,aT is invariant and a6 has the same strictly positive value for every i , one ...

The relation between acoustic signaling and reproductive success is important to understand the evolution of vocal communication systems and has been well studied in several taxa but never clearly shown in fish. This study aims to investigate whether vocal behavior affects the reproductive success in the Lusitanian toadfish (Halobatrachus didactylus) that relies on acoustic communication to attract mates. We recorded 56 nest-holding (type I) males during the breeding season and analyzed the calling performance and acoustic features of the mate advertising sounds (boatwhistles) exhibited over circa 2 weeks. Hormonal levels of the subjects and the number of eggs (reproductive success) present in the respective nests were quantified. Nesting males attracted both females and other males, namely smaller type I males with significantly lower total length (TL), body condition, sonic muscle mass, gonad mass, and accessory glands mass. Calling rate (CR), calling effort (CE) (% time spent calling), and sound dominant frequency were significantly higher in nesting males with clutches than in those without clutches. Sex steroids (11-ketotestosterone and testosterone) were not correlated with vocal parameters or number of eggs. Maximum CR and CE were the best predictors of the number of eggs. In addition, these vocal variables were best explained by male's TL, condition, and sonic muscle mass. We provide first evidence that vocal behavior significantly determines reproductive success in a vocal fish and show that acoustic signaling at higher and constant rates can operate as an indicator of the male's size and body condition and probably of elevated motivation for reproduction.

The main purpose of this work consists on the preparation of single layered zirconium oxynitride, ZrN x O y , thin films, deposited by rf reactive magnetron sputtering. The depositions were carried out by varying the process parameters such as substrate bias voltage and flow rate of the reactive gases. Independently of O content, the samples prepared with oxygen fractions revealed crystalline structures basically constituted by face centred cubic ZrN grains. Atomic force microscopy (AFM) observation showed lower values of surface roughness for low oxygen fractions and a second region where roughness grows significantly, corresponding to the highest oxygen fractions. Ion bombardment promoted a continuous smoothing of the surface up to a bias voltage of À66 V. At a bias voltage of À75 V, roughening is again observed. The small increase of film hardness in low oxygen fractions ZrN x O y films was attributed to lattice distortions occurring as a result of the possible oxygen incorporation within the ZrN lattice and also grain size reduction. Residual stresses appeared to be an important parameter to explain the observed behaviour, namely in the group of samples prepared with variation in the bias voltage. Regarding colour variations, it was observed a clear dependence of the obtained colorations with oxygen fraction.

The miscibility of homogeneous diblock copolymers of 1,4-polybutadiene and cis-l,4-polyisoprene with either or both of the corresponding linear homopolymers was found to depend upon the relative lengths of the block segments and upon the coordinates of the binary or ternary mixture on the appropriate triangular composition diagram. Evidence from a variety of experiments was used to draw overall conclusions regarding the location of the diblock in these blends and its influence on physical properties. Experimental methods employed were transmission electron microscopy on suitably stained specimens, thermomechanical analysis at a heating rate of 5 °C/min, and dynamic mechanical testing at 3.5 Hz over a temperature range from -130 to 40 °C.Complete details of the procedures employed in the various experiments are reported elsewhere.3,5,6